Journal of Science and Engineering-Volume 1

JOURNAL OF SCIENCE AND ENGINEERING

JOURNAL OF

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SE Journal Science and Engineering

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EDITORIAL BOARD

(Alphabetically)

Bădescu Gabriel

Academic Title: Assistant Professor

Affiliation: North University of Baia Mare, Romania

Expertise Fields: Geodesy, Photogrammetry, Cartography and Remote Sensing

Bensafi Abd-El-Hamid

Academic Title: Associate Professor

Affiliation: Department of Chemistry and Physics, Faculty of Sciences, Abou Bekr Belkaid

University of Tlemcen, P.O. Box 119, Chetouane, 13000 Tlemcen, Algeria.

Expertise Fields: Chemical Engineering, Materials Science, Chemical Sciences, Physical

Sciences, Chemistry, Physical Chemistry, Polymer Chemistry, Polymer Thermodynamics,

Chemical Thermodynamics, Polymer Physics.

Faraj A. El-Mouadib

Academic Title: Professor

Affiliation: University of Benghazi, Faculty of Information Technology, Department of

Computer Science, P. O. Box 1308, Benghazi, Libya

Expertise Fields: Data Mining, Clustering, Data Warehouse

Ghalib Y. Kahwaji


Affiliation: Mechanical Eng., Colorado State University, USA

Expertise Fields: Heat transfer and fluid dynamics, Refrigeration and A/C Systems design,

Solar systems, Numerical computations, Energy related topics.

Lamyaa Gamal Eldeen Taha

Academic Title: Associate professor

Affiliation: Head (Supervisor) of the Aviation and aerial photography division –NARSS-

Egypt

Expertise Fields: Image Fusion -change detection-DEM-Orthoimage-LIDAR-SAR-mapping

from satellite images- feature extraction from remote sensing images

Moinuddin Sarker


Affiliation: Vice President of Research and Development, Head of Science Team, Natural

State Research (NSR) Inc.,Stamford, USA.

Expertise Fields: Waste Plastics to Fuels Technology, Waste to Energy, Electricity Storage

and backup, Electricity Production, UHV and Surface Sciences, Analytical Chemistry,

Inorganic and Solid State Chemistry, Molecular Beam Epitaxy (MBE), Single and Poly

Crystal, Bio-Diesel and Bio-Fuel, High Temperature Superconducting Oxides, Alternating

Fuels / Low Sulfur Diesel

Waheed Sabri


Affiliation: Military Technical College (MTC), Cairo, Egypt

Expertise Fields: Electrical Power Engineering (Power System Analysis), and Mathematics

(Statistics)

Zakaria Zubi


Affiliation: Department of Computer Science, Faculty of Science, Sirte University

Expertise Fields: Data Mining and Web Mining, Clustering Analysis, Classification,

Association Rule Mining.

REVIEWERS LIST Vol. 1 (1-2), 2013

We thank the following reviewers for the time and energy they have given to Journal of

Science and Engineering, Vol. 1, 2013:

Achyut Kumar Panda

Ajani Olasunmbo Oyeniyi

Clifford.I.O. Kamalu

Guettaf abdelrazak

Hamza Bentrah

Jean Christian Bernède

Naser Kordani

Nima Vaziri

R.A Ganiyu

Said Benramache

Waheed Sabry

TABLE OF CONTENTS

2013 (Vol. 1, No: 1)

EFFECT OF AMBIENT AIR TEMPERATURE ON SPECIFIC FUEL CONSUMPTION OF

NATURALLY ASPIRATED DIESEL ENGINE

Hindren A. Saber, Ramzi R. Ibraheem Al-Barwari, Ziyad J. Talabany

1-7

DESIGN AND IMPLEMENTATION OF A REMOTE CONTROL BASED AUTOMATIC

CHANGE OVER

Segun O. Olatinwo , O. Shoewu , Oluwabukola Mayowa Ishola

9-15

MODELING AND SIMULATION OF OPEN CYCLE LIQUID PROPELLANT ENGINES

Mahyar Naderi Tabrizi, Seyed Ali Reza Jalali Chime, Hassan Karimi

17-34

EVOLUTION OF STRUCTURAL DAMPING FOR CROSS-PLY LAMINATE BY

MODAL ANALYSIS

D. Bensahal, M. N. Amrane, F. Chabane, O. Belahssen, S. Benramache

35-42

REMOTE SENSING SATELLITE DESIGN USING MODEL BASED SYSTEM

ENGINEERING

Mohammad Sayanjali, Oldouz Nabdel

43-54

INERTIAL NAVIGATION ACCURACY INCREASING USING REDUNDANT

SENSORS

Mahdi Jafari, Jafar Roshanian

55-66

OPTIMAL FREE-DEFECT FUNCTION GENERATION SYNTHESIS OF FOUR-BAR

LINKAGE WITH JOINT CLEARANCE USING PSO ALGORITHM

A. Sardashti, H.M. Daniali, S.M.Varedi

67-78

IMPROVEMENT OF THE INJECTION EFFICIENCY IN ORGANIC LIGHT EMITTING

DEVICES BY ADDITIONAL SPRAY DEPOSITED HOLE TRANSPORTING LAYER

M.P. Aleksandrova, G.H. Dobrikov, G. D. Kolev, I. N. Cholakova

79-83

http://www.oricpub.com/SE-1-1-8.pdf





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http://www.oricpub.com/SE1-1-16.pdf

http://www.oricpub.com/SE1-1-16.pdf

2013 (Vol. 1, No: 2)

EFFECT OF ARTIFICIAL ROUGHNESS ON HEAT TRANSFER IN A SOLAR AIR

HEATER

F. Chabane, N. Moummi, S. Benramache, D. Bensahal, O. Belahssen

85-93

THE PREPARATION OF POLYETHYLENE AND MINERAL MATERIAL

COMPOSITES, AND EXPERIMENTAL AND THEORETICAL (USING MCNP CODE)

VERIFICATION OF THEIR CHARACTERISTICS FOR NEUTRON BEAM

ATTENUATION

Majid Zarezadeh

95-101

NATURAL FREQUENCY, MODE SHAPE, BUCKLING AND POST-BUCKLING

ANALYSIS OF MEMS WITH VARIOUS CLAMPED POSITION

Milad Faraji, Morteza Dardel, Mohammad Hadi Pashaei

103-120

PHASOR MEASUREMENT UNITS FOR OUT-OF-STEP DETECTION OF A MULTI-

MACHINE SYSTEM USING SYSTEM REDUCTION

A. Y. Abdelaziz, Amr M. Ibrahim, Zeinab G. Hasan

121-132

DEVELOPMENT OF A MICROCONTROLLER BASED ALARM SYSTEM FOR

PIPELINE VANDALS DETECTION

O. Shoewu, L. A Akinyemi, Kola A. Ayanlowo, Segun O. Olatinwo, N. T. Makanjuola

133-142

PILOT STUDY FOR QUANTIFICATION OF EMISSIONS OF GREEN HOUSE GAS FOR

MARINE TRANSPORTATION DECISION SUPPORT

O. S. Oladokun, B. Michel, N. Stark, H. Azman, A.S.A.Kader

143-154

STUDY OF PROPERTIES OF COMPONENTS FOR OFFSHORE AQUACULTURE

TECHNOLOGY FARMING

O. S. Oladokun, W.B. Wan Nik, A.S.A.Kader

155-161

ANALYSIS OF THE ELASTIC ENERGY AND CRACK TIP OPENING

DISPLACEMENT WITH INCREASED YIELD STRESS

Hannachi Mohamed Tahar, Djebaili Hamid

163-172



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http://www.oricpub.com/SE-1-2-29-2-2.pdf

http://www.oricpub.com/SE-1-2-29-2-2.pdf

http://www.oricpub.com/Se-1-2-13.pdf

http://www.oricpub.com/Se-1-2-13.pdf





2013 (Vol. 1, No: 1)

All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any

means without the written permission of ORIC Publications, www.oricpub.com.

www.oricpub.com

Journal of Science and Engineering

Vol. 1 (1), 2013, 1-7

Online available since 2013/Mar/30 at www.oricpub.com © (2013) Copyright ORIC Publications

http://www.oricpub.com/journal-of-sci-and-eng

EFFECT OF AMBIENT AIR TEMPERATURE ON SPECIFIC

FUEL CONSUMPTION OF NATURALLY ASPIRATED DIESEL

ENGINE

Hindren A. Saber1a

, Ramzi R. Ibraheem Al-Barwari2a

, Ziyad J. Talabany3a

1Mechanical Engineer

2Assistant professor of Mechanical Engineering Department

3Assistant Lecturer of Mechanical Engineering Department

aMechanical Engineering Department, Engineering College,

Salahaddin University, Erbil, Iraq

Abstract This paper aims it finding the effect of increase of the ambient air temperature before

entering the naturally aspirated diesel engine on specific fuel consumption. The

experimental investigation was carried out on a diesel engine four strokes, water cooled

and indirect injection. The experiments covered all tests. The tests included heating of

the inlet air temperature by designing an electric heater then increasing the air

temperature entering into the diesel engine. The results showed that brake specific fuel

consumption increased with increasing inlet air temperature. Also the results showed

that the brake specific fuel consumption decreased with increasing the brake mean

effective pressure. Experimental data obtained in this work were compared with other

references were found to be in good agreement with experimental results.

1. INTRODUCTION

The internal combustion engine is a heat engine that converts

chemical energy in a fuel into mechanical energy. The power is usually

made available on a rotating output shaft. The chemical energy of the

fuel is first converted to thermal energy by means of combustion or

oxidation with air inside the engine. This thermal energy raises the

temperature and pressure of the gases within the engine and the

high-pressure gas then expands against the mechanical mechanisms of

the engine. This expansion is converted by the mechanical linkages of

the engine to a rotating crankshaft, which is the output of the engine. The

crankshaft, in turn, is connected to a transmission and/or power train to

transmit the rotating mechanical energy to the desired final use [1].

The internal combustion engines which were invented in the last

decades of the 19th century began to influence on human activities and

environment in the beginning of the 20th century. At the end of the

century the air pollution with combustion products and immoderate

consumption of energy resources became unbearable [2]. Lin C. Y. [3]

investigated systematically the effects of humidity and temperature of

intake air on the performance and emission characteristics of diesel

engines in order to improve their design and operations.

Received: 03 Mar 2013 Accepted: 23 Mar 2013

Keywords: Components Naturally Aspirated Diesel Engine Inlet Air Temperature Brake Specific Fuel Consumption Electric Heater Engine Speed

Correspondence: Ramzi R. Ibraheem

Al-Barwari

Assistant professor

Mechanical Engineering

Department, Engineering

College, Salahaddin

University, Erbil, Iraq

Journal of Science and Engineering Vol. 1 (1), 2013, 1-7 P a g e | 2

Nomenclatures:

A/F Air/fuel ratio N Engine speed [r.p.m]

Bmep Brake mean effect pressure [N/m2] T Engine torque [Nm]

Bp Brake power [kW] Ap Piston area [m2 ]

Bsfc Brake specific fuel consumption [kg/kW-h] B Bore diameter [mm]

Cc Cubic capacity L Stroke [mm]

am

Mass flow rate of air [kg/s] k Number of cylinder

fm

Mass flow rate of fuel [kg/s] n Number of power stroke

P Power [kW] .

fQ Fuel discharge [m3/s]

Sfc Specific fuel consumption [kg/kW-h] ρf Fuel density [kg/m3]

p Pressure [N/m2 ]

This study shows that the air consumption rate, brake torque, and nitrogen oxides decrease, while the

brake specific fuel consumption, carbon monoxide, and sulfur dioxide increase with both the temperature

and humidity of the charge air. Talal F. [4] Canned out experimentally a performance and emission testing

for a single cylinder four-stroke diesel engine to determine the optimum operation conditions for this engine.

The studied operation parameters included brake specific fuel consumption (BSFC), the results indicated

that the lowest( BSFC) of the engine was found when the engine ran around 1

kW charging load at a speed

ranging between 1900 rpm and 2700 rpm.

Brian D.Feldman [7] Modeling an engine through software methods to obtained reasonably accurate data

based on reasonably accurate assumptions. Modeling the 2.5LDetroit Diesel engine will help the Future

Truck team to make quick and informed decisions .Assumptions were made in the construction of the model

because all operating parameters were not obtainable. However, it can be seen that the model is sufficiently

similar to the actual engine because major characteristics such as (BSFC) and exhaust gas temperatures are

similar. The most effective strategy for balancing emissions, fuel economy, performance, and cost in a diesel

engine requires a combination of techniques.

The aim of this study is to test the influence of increasing ambient air temperature on brake specific fuel

consumption of naturally aspirated diesel engines.

2. PERFORMANCE PARAMETERS 2.1 ENGINE POWER

Power is the amount of work done per unit time or the rate of doing work. The measure of the engine's

ability to apply power generation is called torque.

Engine torque is normally measured by a dynamometer. The engine is clamped on a test bed and the shaft

is connected to the dynamometer rotor, Brake power refers to the amount of usable power delivered by the

engine to the crankshaft [5].

bp = 100060

2

TN (1)

2.2 SPECIFIC FUEL CONSUMPTION (SFC)

The fuel consumption characteristics of an engine are generally expressed in terms of specific fuel

consumption in kilograms of fuel per kilowatt-hour. In engine tests, the fuel consumption is measured as a

flow rate-mass flow per unit time (.

fm ). A more useful parameter is the specific fuel consumption (SFC) the

fuel flow rate per unit power output. It measures how efficiently an engine uses the fuel supplied to produce

work [5]:

SFC = P

m f

(2)

3 | P a g e Hindren A. Saber1a, Ramzi R. Ibraheem Al-Barwari, Ziyad J. Talabany

fm

= Qf ρf (3)

Qf = time

fuelofvolume (4)

2.3 BRAKE MEAN EFFECTIVE PRESSURE (BMEP) For any particular engine, operating at a given speed and power output, there is brake mean effective

pressure (Bmep) derived from the brake power [6].

Bmep = KnAL

bp

P

100060 (5)

3. EXPERIMENTAL APPARATUS The experimental work for this study was carried out in the laboratory of the mechanical engineering

department. Experiments were performed on (Ford XLD 416 indirect injection diesel engine). The test rig

can be shown in Figure (2).

3.1 SCHEMATIC CHART OF EXPERIMENTAL SETUP

The experimental setup of the present work step by step can be shown in Figure ( 1 ). According to

the Figure ( 1 ), all the procedures were taken in into consideration during the investigation along with the

ranges of engine parameters and were then analyzed. The data collected was applied by direct mathematical

equations to find the influence of increase in the ambient of air temperature on performance of the aspirated

diesel engine.

Figure (1) A schematic chart for the experimental setup.

4. RESULTS AND DISCUSSION Experiments were performed to study the effect of inlet air temperature on brake specific fuel


consumption, Figure (3) illustrates the effect of inlet air temperature on brake specific fuel consumption at

constant engine speed (1500 r.p.m) and varying torques. It was observed that the brake specific fuel

consumption increased with increasing inlet air temperature while brake specific fuel consumption

decreased with increasing engine torque. Figure (4) illustrates the variation of the brake specific fuel

consumption with inlet air temperature at constant engine torque (50 N.m) and different engine speed. It was

also observed that the brake specific fuel consumption increases with increasing inlet air temperature.

Figure (4) also shows the effect of engine speed on the brake specific fuel consumption, decreased with the

increase in the engine speed due to the shorter time for heat loss during each cycle. At higher engine speeds

(2700 and 3000 r.p.m) fuel consumption again increases because of high friction lose. Figure (5) illustrates

the variation of the brake specific fuel consumption with engine speed and different engine torque. It can

also be observed that the brake specific fuel consumption decreases with increasing engine speed. The figure

also shows that brake specific fuel consumption decreased with increase in the engine torque. Figure (6)

illustrates the variation of the brake specific fuel consumption with brake mean effective pressure. It can

observed that brake specific fuel consumption decreased with increase in the brake mean effective pressure,

because the brake mean effective pressure does not depend on engine speed. Rather, it depends on engine

torque ,as well as on the increasing brake mean effective pressure. This means increasing brake torque

leads to increase in the brake power as a result of decreasing brake specific fuel consumption. It also shows

that the decreasing of brake specific fuel consumption decreased with increasing engine speed. Figure (7)

illustrates the variation of the brake specific fuel consumption with engine speed specified in the present

work and [7]. It can be observed that the brake specific fuel consumption decreased with increasing engine

speed for both works. It also showed that the decreasing of brake specific fuel consumption with engine

speed of the present work is in a good agreement with [7]. The main reason for the existence of a difference

between the present work and researcher [7] is the diesel engine used in present work ( Old laboratory-made

engine) and consumer testers and currently does not exist in our laboratories( new laboratory-made engine)

compared to the engine and Model used by the researcher [7]. Figure (8) illustrates the variation of the brake

specific fuel consumption with brake power of the present work and [7]. It can be observed that the brake

specific fuel consumption decreased with increasing brake power for both works. It also shows that the

decreasing of brake specific fuel consumption with brake power of present work is in a good agreement with

[7].

4. CONCLUSIONS The results of this investigation show that:

1. Brake specific fuel consumption increases with increasing inlet air temperature in all experimental

results used in the present work and decreases with both engine torque and engine speed. The decreasing of

brake specific fuel consumption with engine speed occurs until reaching (2500 r.p.m) then increases at

(2700 r.p.m) and above. The brake specific fuel consumption decreases with increasing brake mean effective

pressure.

2. At higher engine speeds (above 2500 r.p.m) the brake specific fuel consumption increases because of

high friction lose.

3. Brake thermal efficiency increases with increasing brake mean effective pressure.

4. The heating of air affected combustion, because of enlargement of air size at heating with same amount

of fuel, leads to less air available to burn with fuel led to high fuel consumption.

REFERENCES [1] Willard W. Pulkrabek, (1997), Engineering Fundamentals of the Internal Combustion Engine,

Prentice Hall, Upper Saddle River, New Jersey 07458, Pages 1- 27.

[2] Algis Butkus, Saugirdas Pukalskas and Zenonas Bogdanovičius, (2007), The Influence Of

Turpentine Additive On The Ecological Parameters Of Diesel Engines, Dept of Automobile Transport,

Vilnius Gediminas Technical University, J. Basanavičiaus g. 28, LT-03224 Vilnius, Lithuania, Volume 22,

Page 80.

[3] Lin C. Y. and Jeng Y. L., (1996), Influences of charge air humidity and temperature on the

performance and emission characteristics of diesel engines, Society of Naval Architects and Marine

Engineers, Jersey City, NJ, ETATS-UNIS, Volume 40, pp. 172-177 .


[4] Talal F. Yusaf, (2009), Diesel Engine Optimization for Electric Hybrid Vehicles, Journal of Energy

Resources Technology, Volume 131, Issue 1, Pages 12203-12207.

[5]. U.S. Department of Energy Washington, D.C, Department Of Energy Fundamentals Handbook,

mechanical Science, Module 1: Diesel Engine Fundamentals, Volume 1of 2, Pages 2 − 19, (1993).

[6]. V. Ganesan, (2004), Internal Combustion Engines, Tata, McGraw-Hill, second edition, Pages 25 −

597,

[7] Brian David Feldman, (2004), Diesel Engine Modeling in wave, The Pennsylvania State University,

Schreyer Honors College, Pages 11-13.

Figure (2) Diesel engine with air heater.

Figure (3) Effect of inlet air temperature on the brake specific fuel consumption, at constant engine speed (1500 r.p.m) and

different engine torques.

Figure (4) Effect of inlet air temperature on the brake specific fuel consumption, at constant engine torque (50 N.m) and different

engine speeds.


Figure (5) Brake specific fuel consumption as a function of engine speed for different engine torques.

Figure (6) Effect of brake mean effective pressure on brake specific fuel consumption for different engine speeds.

Figure (7) Comparison between acquired experimental results and experimental results for the [7].

0.25

0.3

0.35

0.4

0.45

0.5

500 1000 1500 2000 2500 3000 3500

Engine speed (r.p.m)

bsf

c (k

g/k

Wh

)

Torque=15 N.m

Torque=30 N.m

Torque=50 N.m

Torque=75 N.m

Torque=100 N.m


Figure (8) Comparison between acquired experimental results and experimental results for the [7].

Please cite this article as: Hindren A. Saber1a, Ramzi R. Ibraheem Al-Barwari, Ziyad J. Talabany, (2013), Effect Of Ambient Air Temperature On Specific

Fuel Consumption Of Naturally Aspirated Diesel Engine, Science and Engineering, Vol. 1(1), 1-7.


means without the written permission of ORIC Publications,www.oricpub.com

www.oricpub.com


Vol. 1 (1), 2013, 9-15

Online available since 2013/Mar/30 at www.oricpub.com © (2013) Copyright ORIC Publications


DESIGN AND IMPLEMENTATION OF A REMOTE CONTROL

BASED AUTOMATIC CHANGE OVER

Segun O. Olatinwo

1, O. Shoewu

2, Oluwabukola Mayowa Ishola

3

1 Department of Computer Engineering, Moshood Abiola Polytechnic, Abeokuta, Nigeria.

2 Department of Electronics and Computer Engineering, Lagos State University, Epe Campus, Nigeria.

3 Department of Computer Science, University of Lagos, Akoka, Lagos State, Nigeria.

Abstract In this paper, an attempt is made to design and implement an automatic change over

with remote control. The design and construction of an automatic changeover with

remote control will ease the use of an electrical power generating system. This paper

focuses on the design of an automatic changeover with timer system that will enhance

user control over a power generating set. It is intended for use with a single phase

power generating set operating at 220V AC. This research work is limited to the design

of an automatic changeover with timer system that will enhance user control over a

power generating set. It is intended for use with a single phase power generating set

operating at 220V AC.

1. INTRODUCTION

Electrical power is a very important form of energy that is needed in

homes, laboratories, schools, industries and the society at large. However,

in Nigeria, it is not generated in adequate amounts and thus, making it

one of the principal needs everybody in the society have to fulfill. Most

people use small generating sets for this purpose, some use solar means,

some use wind means while others combine all the different methods of

self power generation to form a special power generating scheme and

thus maintain 24 hours uninterrupted power supply.

In order to make self power generation enhanced, requiring less

human control and more efficient, then modern automation and control

systems needs to be installed on even the smallest power generation

systems. Control and automation systems are electronic, electrical or

electromechanical systems that can take future actions based on present

and past actions or take an action based on input from another system.

Present technological advancements have seen the evolution of special

control systems into domestic equipments. These control systems include

remote control systems, thermostats, temperature controllers and timers.

Most control systems were originally reserved for industrial purposes

due to cost implication of such systems. Control systems add more

control functions to the devices and make them much easy to control.

The control systems often found in consumer equipments function in one

of two ways. Some control systems perform their functions by taking an

action based on change in the immediate physical environment such as

change in temperature, pressure, light intensity, e.tc. Examples of

devices that use this type of control systems include; Iron, solar street

lights, air conditioners and automatic emergency lights.

Received: 14 Mar 2013 Accepted: 26 Mar 2013

Correspondence:

Segun O. Olatinwo

Department of Computer

Engineering, Moshood Abiola

Polytechnic, Abeokuta, Nigeria.

Keywords: Automatic change over Remote control Timer PHCN


Other control systems perform their functions by taking an action when they receive data wirelessly or

via wires from another device. Examples of such control systems are seen in remote controlled systems such

as; television sets, DVD players, audio player systems, home theaters, remote controlled cars and micro

wave timing systems. This type of control system is also found in mobile phones where an incoming call or

text message will trigger the ringer system of a phone.

This project report describes the design and construction of an automatic change over with remote control

which is a control system that serves two purposes; allows the user of a generator to be able to switch off the

generator after working for a predefined period of time and also monitors whenever there is supply from

PHCN, switch off the generator if it is running and switch the supply to PHCN automatically without human

intervention.

2. MATERIALS AND METHODS 2.1 Design concept

The design of the proposed system is made up of the following component parts:

i. The power supply stage

ii. The inverter stage

iii. The infra red receiver stage

iv. The mono stable stage

v. The switching relay and buzzer stage

vi. The power relay and PHCN indicator stage

The block diagram of the proposed system is shown in figure 1.

Figure 1: Block diagram of the proposed system

2.2 The power supply stage

This stage is made up of two bridge rectifier circuits with voltage regulators to regulate their outputs. One

of the bridge rectifier circuits is used with to rectify input power from the generator and used to power the

inverter stage, the infrared receiver stage, the mono stable stage and the switching relay and buzzer stage.

The other bridge rectifier circuit is used to rectify input power from PHCN and the output is used to power

the power relay stage. The output of this bridge rectifier also serve as an input to the inverter stage and such

MONOSTABL

E STAGE

GEN POWER

SUPPLY

STAGE

POWER RELAY

AND PHCN

INDICATOR

STAGE

SWITCHING

RELAY AND

BUZZER STAGE

PHCN POWER

SUPPLY

STAGE

INVERTER

STAGE

INFRA RED

RECEIVER

STAGE

11 | P a g e Segun O. Olatinwo, O. Shoewu, Oluwabukola Mayowa Ishola

serves as an indicator for the availability of supply form PHCN to the circuit. The circuit diagram of the

power stage is shown in figure 2.

Figure 2: The power supply stage

The output of the bridge rectifier connected to the generator supply is filtered by the 470µF capacitor and

fed to the inputs of two voltage regulators, the 7805 and 7812 voltage regulators. The 7805 regulator

regulates the filtered output of the rectifier to 5V necessary to power the inverter circuit which is TTL logic

gate IC and the 7812 regulates the rectifier output to 12V necessary to drive the switching relay and also

power the mono stable circuit. The 0.1µF capacitors at the outputs of the regulators are to prevent the

regulators from going into oscillation. The maximum input voltage for 78XX regulators is 24V and the input

voltage must be greater than or equal to the expected output voltage.

For each cycle of conduction, two diodes are in operation. The output voltage of the rectifier can be

calculated as follows:

√

(1)

√

Thus, both conditions for using the 78XX regulators are satisfied by the first part of the power circuit.

For the rectifier circuit connected to the supply from PHCN,

√

This output is fed to the second 7805 voltage regulator which gives a 5V regulated output. The unregulated

output is also used to directly drive the power relays.

2.3 The inverter stage

This stage is used to invert the power supplied by the bridge rectifier connected to the PHCN source and the

output is used to trigger the mono stable stage. It is also used to invert the output of the mono stable stage and

used to drive the switching relay appropriately. The IC used for the inverting is a 7400 NAND gate IC. This IC

is powered by the 5V regulator connected to the bridge rectifier associated with the generator power source.

2.4 The infrared receiver stage This stage is used to detect the presence of remote control signals from a hand held remote controller. The

circuit diagram of this stage is shown in Figure 3.


Figure 3: The infra red receiver stage

The infra red detector is made up of TSOP1836; an infra red detector IC which is powered by the 5V

supply provided by the rectifier and regulator circuit connected to the generator source. The IC has three

pins. Pin 1 is data output, pin 2 is ground and pin 3 is supply pin. The data received from the transmitter is

output directly at pin 1 of the IC. This data is then sent to the mono stable stage where it is interpreted. The

100Ω and 4.7µF capacitor between the main supply, the supply pin of the IC and ground is to reduce power

supply disturbances while the 10KΩ resistor is to pull the output normally high.

2.5 The mono stable stage

This stage serves as a 11s short pulse generator which generates the control signals to switch off the

generator whenever there is a triggering condition and also sounds the buzzer for a short period of time.

When the generator is first switched on, it generates a 11s pulse which sounds the buzzer and waits for the

generator output to stabilize while allowing the infra red receiver stage to initialize properly. The trigger

source of the mono stable stage comes from an OR gate which have inputs from the PHCN power source

and the infra red receiver stage. The output of the mono stable stage is used to drive the buzzer and also fed

to the inverter stage where it is inverted and used to drive the switching relay. The circuit diagram of the

mono stable stage is shown in figure 4.

Figure 4: The mono stable stage

The mono stable is triggered when ever there is low going pulse on pin 2 which is held high by the

100KΩ resistor to prevent spurious triggering. The length of the output pulse that is generated whenever

there is a trigger is determined by the values of capacitor C1 and resistor R1 and is given by the equation;


2.6 The switching relay and buzzer stage This stage is used to switch the generator off whenever there is a trigger at the mono stable stage and also

used to sound a buzzer to indicate the condition. A 3-24V buzzer was used and is driven directly by the

output of the mono stable stage. The switching relay is driven by the inverted output of the mono stable

stage via a transistor. The following analysis describes the switching action that occurs in the switching

stage.

Figure 5: The switching relay

Minimum voltage expected at the base of the transistor whenever there is a high output from the inverter

stage, is assumed to be 3V

Resistance in the base circuit, Rb = 1kΩ

The corresponding base current that flows in the circuit is given by,

Ib =

=

= 3mA

Resistance of the relay in the collector circuit, Rc = 330Ω

At saturation, current flowing in the collector circuit,

Ic =

=

= 35.7mA

Minimum hfe for the transistor (BC547) is 110

Therefore, the base current required to cause saturation is,

Ibreq =

=

= 0.32mA

Since the actual current that is flowing through the base of the transistor is higher than that required to

cause saturation, the relay will be latched on whenever the inverter stage gives a high output on the pin

connected to the base of the transistor.

2.7 The power relay and PHCN indicator stage

This is the stage in which the actual switching of power from GEN to PHCN and vice versa is done. It

consists of two relays that are powered by the part of the power source connected to the PHCN supply. By

default, the output of this stage is connected to the generator supply. When there is supply from PHCN, the

output is switched away from the generator source to the PHCN source. The circuit diagram of this stage is

shown in figure 6.


Figure 6: Power relay and PHCN indicator stage

The complete circuit diagram for the design is shown in Figure 7

Figure 7: Complete circuit diagram of the design

3. RESULT AND DISCUSSION 3.1 Construction

The construction of this project refers to the techniques by which the circuit in this project is designed

and the way the final project is cased. Thus, construction of the device in this project work is divided into

two; the soldering stage and the packaging stage.

3.2 Packaging

The whole project is packed in a metallic container. The container is a commercially available adaptable

box often used by electrical engineers for complex installation works and this justifies why it was used. The

container was drilled where necessary to allow rooms for indicators, switches, buzzers and other required

devices. The circuit was fitted into the box and held tightly in place with the aid of screws and nuts. The

transformers to be used in the power circuit were also held tightly in place with the aid of screws and nuts.

3.3 Testing The first set of testing was done after the soldering of each stage. The second testing was done after the

whole circuit has been soldered appropriately. The final testing was done after the whole devices had been

packaged. The final circuit of the proposed system is shown in Figure 8.


Figure 8: Circuit of the proposed system

4. CONCLUSION This paper has presented the development of a remote control based automatic change over. Several

components were integrated to achieve the proposed system. The proposed system eases the use of an

electrical power generating system. The system is applicable to a single phase power generating set

operating at 220V AC.

REFERENCES [1] Theraja, B.L and Theraja, A.K. (2002), A textbook of electrical technology, 21

st ed., Rajendra

Ravindra Printers (P) Ltd., S. Chand & Company Ltd., Ram Nagar, New Delhi, India.

[2] Theraja, B.L. and Theraja, A.K. (1995). Electrical Technology, Delhi: Publication of Ram Naogar.

[3] Ragnar, H. (1958). Electric Contacts Handbook, 3rd

ed., Springer-Verlag, Berlin Heidelberg.

[4] Terrell, C. and Wilford, S. (1987). American Electricans' Handbook, 11th ed., New York:

McGraw Hill.

[5] Thomas, L.F. (1997). Digital fundamentals: Integrated circuits, 6th

ed., Prentice-Hall, Englewood

Cliffs, NJ, USA.

Please cite this article as: Segun O. Olatinwo, O. Shoewu , Oluwabukola Mayowa Ishola, (2013), Design And Implementation Of A Remote Control Based

Automatic Change Over, Vol. 1(1), 9-15.

All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of ORIC Publications, www.oricpub.com.

www.oricpub.com


Vol. 1 (1), 2013, 17-34

Online available since 2013/Apr/11 at www.oricpub.com © (2013) Copyright ORIC Publications


MODELING AND SIMULATION OF OPEN CYCLE LIQUID

PROPELLANT ENGINES

Mahyar Naderi Tabrizi1ab, Seyed Ali Reza Jalali Chime2ab, Hassan Karimi3b

1M.Sc. Graduate, Aerospace Engineering Department

2PHD Candidate, Aerospace Engineering Department

3Associate Professor of Aerospace Engineering Department

aPower and Propulsion Systems Engineering Research Center,

bK. N. Toosi University of Technology, Daneshgah Street, Dorahi Rahbar,

Eastern Vafadar Avenue, 4th

Square of Tehran-pars, Tehran, Iran

Abstract

In this article using physical and mathematical equations for propulsion systems; major

elements of an open cycle LPE1

(such as pipes, valves, Gas Generator (GG),

Combustion Chamber (CC), turbo pump assembly and solid grain starter) are modeled

and using Fortran 90 programming language, the nonlinear and dynamic governing

differential equations are numerically solved and a general simulator for open cycle

LPE is developed. The developed simulator has the capability to simulate the hydraulic

circuit for any arrangements of open cycle engine elements, received from the user via

a suitable graphical interface.

1. INTRODUCTION

One of the main objectives in modifying space launch vehicles is

increasing the payload or/and orbital capability of space missions.

According to the important role of propulsion systems in providing the

required power to fulfill the aforementioned objective; propulsion

engineers using the available technologies, tend to improve the

performance of the existing engines. Open cycle LPEs are used for lower

stages in a majority of world’s Launch vehicles. Despite the lower

energetic performance of open cycle LPEs (in comparison to closed

cycle LPEs); these engines are less complicated. That’s why designers

tend to enhance the performance of the existing open cycle LPEs. Taking

into account the considerable expenses; prior to any experimental tests or

modifications, propulsion engineers use LPE computer modeling and

simulators to analyze the effects of any modification on propulsion

system’s performance. The most important elements that can change a

LPE’s performance parameters (such as engine’s weight, thrust, Specific

Impulse Isp) are the engine’s turbo pump assembly, starter, GG2, CC

3

and control valves. If there is any possibility to change the operating

condition of these elements, one can enhance the performance of a

Propulsion system or launch vehicle.

1 Liquid Propellant Engine

2 Gas Generator

3 Combustion Chamber

Received: 14 Mar 2013 Accepted: 06 Apr 2013

Keywords: Simulation Software Nonlinear Dynamic Analysis Propulsion Systems

Aerospace Engineering

Correspondence: Mahyar Naderi Tabrizi M.Sc. Graduate, Aerospace

Engineering Department,

Power and Propulsion Systems

Engineering Research Center,

K. N. Toosi University of

Technology, Daneshgah Street,

Dorahi Rahbar,

Eastern Vafadar Avenue, 4th

Square of Tehran-pars, Tehran,

Iran


This would reveal the importance of precise modeling of each element especially the abovementioned

ones. Using the experimental data acquired from cold/hot tests of each element, it is possible to obtain a

correct mathematical model for the unpredicted coefficients of elements. By solving the system of equations

for the LPE, it is possible to analyze the effect of each element on Engine.

Recent studies in simulation, dynamic analysis and parametric study of LPEs are developed by Karimi,

2003, [1]; Karimi and Nassirharand, 2006, [2]; Mohammadi 2007, [3]. This paper complements a set of

limited previous works on the whole LPE systems Ruth et al., 1990, [4]; Binder et al., 1997, [5]; Shahani,

1997, [6]; Lozano, 1998, [7]; Belyaev et al., 1999, [8]; Kun and Yulin, 2000, [9]; Tarafder and Sarangi,

2000, [10]; Holt and Majumdar, 2000, [11]; and also Static models for engine components Tishin and

Gurova, (1989). [12]. Many of papers in this field are written to study the behavior of particular equipment,

e.g. a pump or a controller, or a phenomenon such as combustion instability. For example, general relations

for simulations of the combustion chambers are given by Liang and Mason, (1986), [13]; Habiballah et al.,

(1991), [14]; Jiang and Chiu, (1992), [15]; Wang, (1993), [16]; Khosravi and Mazaheri, (2000), [17]; and

Ivancic and Mayer,(2002), [18]. Analysis of LPRE turbo machinery is covered by McDaniel and

Snellgrove, (1992), [19] and Chen, (1995), [20]. The presentation of engine feed systems are given by

Ovsiyanikov, (1983), [21] and Lin and Baker (1995), [22]. The governing nonlinear equations for the

regulator valve of a specific LPE are presented by Karimi, (1999) [23] and mixture ratio control of LPEs by

Nassirharand and Karimi,(2005), [24]. The primary goal of this paper is to complete the previous researches

in modeling and simulation of liquid propellant engines specifically studies done by Mohamadi in ref. [3].

2. MATERIAL AND METHODS

In this article the pipes, valves, Turbo pump assembly, solid grain starter, GG and CC are dynamically

modeled and using a simulating program written in Fortran 90 programming language the obtained

equations were numerically solved. The mathematical model used for each element and the algorithm of the

simulation also the results for a special study case is introduced further in this article. The nonlinear

dynamic equations are derived for each element and afterwards using the Newton-Raphson trial and error

correction method the system of equations is solved explicitly. This article is based on the previous

researches done in references mentioned in section.1 with the difference that in this article; the combustion

process is simulated in more detail therefore the modeling of combustion chamber, gas generator is

enhanced. In this research, the engine’s solid propellant starter is fully modeled and coupled to the program.

More over a graphical interface has been developed so that the users can easily simulate their desired engine

in the least time and sophistication.

2.1. MATHEMATICAL MODELING AND GOVERNING EQUATIONS FOR LPES

In this section the governing equations for some of the major elements in open cycle LPEs are derived.

These elements include the pipe and valves, turbo pump assembly including the turbine and propellant main

pumps, combustion chamber, gas generator and the solid propellant starter.

2.1.1. PIPES AND VALVES

One of the equations in LPE’s mathematical modeling is the equation for pipes and valves. In this article

both of these elements are considered as an orifice with a specific equivalent discharge coefficient. Using

the first law of thermodynamics and Bernoulli equation and also defining the discharge coefficient factor for

incompressible flows, the mathematical model for pipes and valves can be derived, as equation (1).

In which eqK is the equivalent discharge factor, as equation (2).

And P is the pressure drop due to a combination of frictional and geometrical losses and is calculated

via equations (3) to (5).

The moody factor and the local frictional loss factor are obtained from experimental data and graphs in

hydraulic handbooks [25]. It should be mentioned that in valves, the frictional pressure drop is negligible

compared to geometrical pressure drop and in pipes it’s vice versa. The geometrical pressure drop in valves

is calculated by Darcy equation (6).

19 | P a g e Mahyar Naderi Tabrizi, Seyed Ali Reza Jalali Chime, Hassan Karimi

2.1.2. COMBUSTION CHAMBER AND GAS GENERATOR

The combustion process in combustion chamber and gas generator are described by the following the

equation. This equation is derived from combining the first and second law of thermodynamic combined

with the perfect gas law. Using a combustion modeling software (such as CEA1, Astra …) or experimental

results, the exhaust gas thermodynamic properties such as *, ,R T C can be prepared. After the thermodynamic

properties are obtained, using equation (7) one can compute the pressure change in CC or GG.

2.1.3. TURBO-PUMP ASSEMBLY

The high pressure gas in the exit of the GG and/or starter rotates the turbine and the turbine drives the

propellant pumps. The work, done on the propellants causes the fluid to be pumped and delivered to the

subsystems at a higher pressure. The rotational acceleration of the rotor is obtained from equation (8).

This difference between the generated torque from GG-starter and the consumed torque for driving the

pumps divided by turbine’s inertial moment eqJ ; determines the changing rate of the turbines rotational

speed. By integrating the above equation, the rotational speed of the shaft can be calculated in each time

step.

The torque of each pump is calculated from equation (9).

In which H is the pump head and is calculated from equation (10) [26].

Where;

1 1 1, ,A B C are Ovsianokov’s experimental coefficients (dependant on the nominal volumetric flow

rate, nominal rotational speed and the geometrical characteristics of the pumps). The turbine’s efficiency is

also calculated similarly via equations (11) to (13). In these relations, 0 0 0, ,A B C Are constant values [26].

The torque of GG or starter is calculated from equation (14).

In equation (14), spW is the turbine’s specific work and is defined in equation (15).

2.1.4. STARTER

At this research, using basic equations of thermodynamics and also gas dynamics; the internal ballistic

variation of the starter has been simulated and the required data for engine’s transient phase of simulation,

such as pressure, specific heat coefficient fraction, and mass flow rate are calculated in each time step, using

equation (16) [27,28].

This equation relates the pressure change of the starter to the produced mass and the discharged mass.

Equation (16) demonstrates the starter’s operation in the nominal phase where there is either mass

production or exit flow from the nozzle. During the starter’s first transient phase, the nozzle is clogged by a

special sealing diaphragm therefore, there is no exit mass flow from the starter and the burned mass

accumulates in the chamber. In this condition the second term on the right hand side of equation (16) is set

to be zero. During starter’s shut down phase the first term on the right hand side (mass production term) is

omitted because there is no grain left for burning.

2.2. SIMULATION ALGORITHM OF A PROPULSION SYSTEM

The hydraulic circuit of the selected engine in this research is as shown in Fig.1. The engine is of open

cycle type with a single thrust chamber. The feeding system is of turbo pump type in which a single turbine

drives two pumps on a common shaft. A thrust regulating valve is installed on GG’s oxidizer line and in

order to keep a constant mixture ratio, a stabilizer is positioned on the fuel line leading to GG. The main fuel

line of the CC has got a stabilizer too. The controlling elements of this engine have to keep the engine’s

parameters such as CC’s mixture ratio and pressure within the desired range. The controlling elements of

this engine (regulator and stabilizer) are mathematically modeled and simulated so that by changing the

discharge coefficient factors of them, the engine’s operation would vary. In current simulation, the required

data for combustion product thermodynamic properties such as gas constant, specific heat ratio, temperature

and etc are provided via CEA combustion modeling software which has been linked to the engine simulator.

Therefore in each time step, the required data are calculated online which will prevent the complex process

1 Combustion Equilibrium Application


of data generation where the user had to run such programs for a wide range of pressure for each mixture

ratio, so that a data bank would be created to allow interpolation. Indeed in current simulator the user can

select his desired type of propellants and easily use the simulator without any other preparation which will

save time. On the other hand, the starter has also been modeled and simulated so that the user can enter the

physical and chemical properties of the starter and its solid grain. After the required data of this element has

been entered, the simulator would solve the equations so the required data for turbine equations would be

provided [27-29].

Generally in hydraulic systems, in order to solve the propellant flow in pipes and engine elements it is

necessary to know two of three unknown variables for each element, which are

1. Inlet pressure

2. Outlet pressure

3. Mass flow

In hydraulic circuits of liquid propellant engines; as the first element, the pressure of propellant tanks is

known. Initial pressure at the exit of each element is also known to be equal to atmospheric pressure.

Therefore after the main inlet valve is opened, the first element would have a specific inlet pressure (equal

to the pressure at lower part of each tank) and atmospheric pressure at exit. Using the governing equation

between the mass flow and pressure differential and also by knowing the required geometrical and discharge

coefficients, the mass flow can be calculated. After the mass flow in the first element is calculated the pressure at the exit of this element should be

increased so that the propellant can flow to the next element but the problem is that, only the exit pressure of

the next element is known (atmospheric pressure) so there is still two unknown values, the inlet pressure and

the new mass flow. This trend is the same for the remaining elements of the engine. In order to solve this

problem, the method of trial and error has been used to find one of the remaining unknown variables of

engine.

For simulating the operation of a determined LPE, the simulator needs a set of inputs to be determined by

the user. As the first step, the user will have to introduce the hydraulic circuit of his desired LPE in a special

form so that the simulator can understand the number, type and position of the elements used in the engine.

For this purpose the engine is divided into some smaller sections. In this research the engine’s hydraulic circuit is separated in two major sections

A) Fuel line

B) Oxidizer line

In each line there are three blocks

1. Block(I) : Elements from tank to the GG/CC branch

2. Block(II): Elements from branch to GG

3. Block(III) : Elements from branch to CC

The user will determine the elements used in each block by entering the codes attributed to each element.

The type of elements in a LPE is one of the following elements: Tank, pipe, valve (including start and cut

off valves and controlling valves) pump, Turbine, Starter, GG and CC (thrust chamber). In programming,

for each element a data type is allocated in which the required coefficients of that element should be

specified. These include pressure of tanks, frictional coefficients of the pipes, discharge coefficients of

valves and injectors, geometric specifications and nominal parameters of turbo pump assembly and

geometrical specifications of CC and GG. For computing the combustion properties of the gas in GG and

CC, the user will have to specify the type of engine’s propellant, (fuel and oxidizer). Then using CEA

combustion software which has been decoded and linked to the developed engine simulator, the combustion

properties of the selected propellants (required for equation (7)) are computed for each mixture ratio and

pressure online. The thermodynamic chemical properties required for equation (16) such as ,R are obtained

from a solid motor combustion simulation program, GDL Prop.

The steps needed for simulation are described below.

1) The simulation is started by calling the starter subroutine in which, in each time step the data

required for equation (8) are obtained by solving equations (9) to (15). By equation (14) the torque of starter


is computed and by integrating equation (8) the rotational speed of the turbine shaft is calculated (the torque

of pumps are zero at the first time step).

2) The start command is transferred to start valves and propellants fill the lines of engine by the

algorithm described in 3.

3) The filling process of elements is as following the exit pressure of any element which is not filled is

equal to ambient pressure (in this case 1atm). In each time the pressure in the tanks is known but the exit

pressure of the first pipe (which runs between tank and start valve varies with time. In the first time step the

exit pressure of pipe 1 is equal to ambient pressure (1atm) which gives a known value of p . Using

equation (1) the mass flow by which the elements are being filled is determined. For the next elements a

similar procedure is used with the difference that we should guess the exit pressure of the first pipe because

1outp is not known now. Using the guessed pressure, the subsequent elements are filled. If the exit pressure

of the element that is being filled is 1atm (with some tolerances) then we conclude that the guessed pressure

was correct else if the computed pressure differs from 1atm we have to change the guessed value for1outp . In

order to minimize the required iterations to reach the correct pressure, the error term is computed and using

Newton-Raphson method, a new value for 1outp is calculated. With this procedure the rest of engine

elements are filled until the propellants reach the CC or GG. In this time fluid enters GG or CC with a

calculated m but with atmospheric pressure. It should be mentioned that the filling process is rather

complicated because in each time step, a finite value of propellant mass is transferred through pumps, so

special care should be taken into account that only a small volume of the element will be filled by fluid. The

rest of filling process will be completed in next time steps, that is; it may take several time steps for an

element to be filled and in each time step the pumps would have different rotational speeds. At the end of

this step, all of the engine elements are filled.

4) After all elements are filled, pressure of CC and GG are the check points for Newton Raphson loop.

This means; from now on the pressure at the exit of pipe 1 should be guessed so that the calculated pressure

from simulation process for GG and CC, matches the pressure calculated from equation (7). When the shaft

of the turbine rotates, the pump’s impeller will also rotate and because of the suction produced, the mass

flow of engine and the head of pumps will be increased as mentioned in equation (10) but because of the

dynamic behavior of the equations, the mass flow is not known and must somehow be determined. In order

to determine the mass flow of engine, in each time step the pressure in the inlet of the start valve (valve

beneath the tanks) is guessed. With the known tank pressure and the guessed pressure in the inlet of the

valve 2, the mass flow rate can be calculated using equation (1). Now with the calculated mass flow we will

solve the flow in elements and check if the pressure in CC and GG match the value which is calculated by

equation (7). If the pressure didn’t match we should change the guessed value of 1outp using Newton

Raphson method.

5) The propellants that enter the GG or CC have a known mixture ratio. With the mixture ratio and the

entering pressure, the combustion gas properties required in equation (7) can be calculated. Using equation

(7) the pressure changedt

dp ; is computed. Using Euler integration method the pressure for the next time step

will be calculated. Now For the next time step 1outp must varied so that the fluid enters the GG and CC with

the calculated pressure for this time step.

6) After a couple of seconds (that is btw 0.5-0.8 sec) the propellants in the GG will be ignited and the

turbo pump’s rotational speed will increase till the starter is shut down and GG enters its nominal operating

phase. The simulation is repeated until the simulation time is finished. The simulation flowcharts are as

following.


2.3. SIMULATION OF THE CONTROLLING ELEMENTS IN LPE

In a LPE the valves can be classified in two categories.

1) Controllable valves such as stabilizers, pressure or thrust regulators

Non controllable valves such as main inlet valves, cut-off valves, discharge valves. Because this paper deals with controllable valves, the simulation method for modeling these types of

valves is being discussed.

2.3.1. REGULATOR

As it is visible in Fig.1 the thrust regulator is in the oxidizer line of the gas generator. This valve is

modeled as an orifice with adjustable discharge coefficient. The regulator will control the GG’s oxidizer

mass flow so that the combustion pressure is within the nominal range. The pressure is checked with the

reference pressure in each time step and in case of pressure differentiation, the related subroutine is called

and the new discharge coefficient is found via Newton-Raphson method therefore the engine will always

operate in nominal range. The flowchart of this element is shown in Fig.5.

2.3.2. STABILIZER

Two stabilizers are installed on the fuel line of CC and GG. This valve will control the propellant mixture

ratio to always be within the desired range. The propellant mass flow is sensed in each time step in both

lines. The mixture ratio is calculated if there is any deviation from the nominal value, then using Newton-

Raphson method; the coefficient of the stabilizer is varied in order to maintain the allowable ratio. The

flowchart of this element is shown in 0Fig.6.

2.4. LIQUID PROPELLANT ENGINE SIMULATING SOFTWARE

In order to enhance the user’s interaction with the developed simulator, using the C-Sharp programming

software a graphical user interface has been written for the code. As it is obvious in the following figures,

the interface has four main tabs including: Fuel tab, Oxidizer tab, Subsystems tab and Simulation tab. In

each of the Fuel and Oxidizer tabs, the engine’s hydraulic line is divided into 3 parts. In each part the type of

elements (tank, pipe, valve, etc) can be selected and afterwards the required characteristic of each element

can be entered. For example according to Fig.1, in the fuel line from tank to first branch, the existing

elements are fuel tank, start valve, pipe, fuel pump and again a pipe. Therefore in the relevant tab the

number of elements is entered 5, and then by choosing the type of elements, the required characteristics are

entered. The other two tabs and also the oxidizer tab are filled with the same method. In the Subsystems tab,

the required data of the pumps, combustion chamber, gas generator and the starter is determined by the user

and finally in the Simulation tab the user can press the simulation button in order to execute the computer

program and view the related plots.

3. RESULTS

After entering the required data for the related LPE of this research, the figures presented at the end of

the paper were obtained for a special open cycle LPE study case. A brief table for the modeled engine

properties is as Table2.

4. DISCUSSION

Fig.11 describes the changes of engine’s turbo pump assembly shaft rotational speed versus time. As it

can be seen, at the first step (time less than 0.5 sec) the turbine is rotated via starter’s exhaust hot gases.

After the Gas Generator is activated (at t=0.5 sec), there will be a rise in turbine rotational speed and finally

after starter shutdown at t= 0.9sec, the speed will be reduced to its nominal rotating speed. Such a behavior

will affect the operating condition of the pumps, combustion chamber pressure and mixture ratio, thrust and

Isp, that is; these diagrams will have the same trend. It is evident that before time= 0.6s only the starter is

operating. At time between 0.5 and 0.9 GG and starter work together. After t=0.9s the starter’s operation is

terminated and only the GG operates. Fig.12 describes the pressure change in GG versus time and Fig.13

describes the mixture ratio change in engine due to the changes of Turbine’s rotational speed.


In order to verify the results achieved from the software, the simulator was executed for a special open

cycle liquid propellant engine. The experimental results obtained from reference [2, 30-31] and the

simulation results were both normalized and compared for some of the engine’s available parameters. The

results are demonstrated in the presented figures. From the achieved results for a special open cycle liquid

propellant engine It can be concluded that the method of modeling and the simulation program produces

reasonable physical results which satisfies the expected trends from an experimentally tested liquid

propellant engine behavior. Furthermore the simulator has the capability of simulating and solving various

open cycle LPEs that users enter. The developed software for simulating the open cycle liquid propellant

engines, prepares the application of the simulator for all type of users.

ACKNOWLEDGMENT

We like to acknowledge the Power and Propulsion Systems Engineering Research Center (PPSERC) and

Aerospace faculty of K.N Toosi University of Technology for their help and supports.

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[17] Khosravi, A. and Mazaheri, K. (2000), “Transient simulation of liquid rocket engines combustion chamber”, Proceedings of

the First Conference of Aerospace Industries Organization on Scientific and Application Aspect, Tehran, pp. 41-5.

[18] Ivancic, B. and Mayer, W. (2002), “Time and length scales of combustion in liquid rocket thrust chambers”, AIAA Journal of

Propulsion and Power, Vol. 18 No. 2, pp. 247-53.

[19] McDaniel, D.M. and Snellgrove, L.M. (1992), “Liquid propulsion turbomachinery model testing”, Aerospace Engineering,

Vol. 12 No. 7, pp. 8-12.

[20] Chen, W.C. (1995), “CFD as a turbomachinery design tool:code validation”, paper presented at Fluid Engineering & Laser

Anemometry Conference, American Society of Mechanical Engineers, New York.


[21] Ovsiyanikov, B.V. (1983), Theory and Calculation of Feeding Systems, Mashinostroenie, Moscow (in Russian).

[22] Lin, T.Y. and Baker, D. (1995), “Analysis and testing of propellant feed system, priming process”, AIAA Journal of

Propulsion and Power, Vol. 11 No. 3, pp. 505-12

[23] Karimi, H. (1999), “Dynamics and control of a liquid engine”, PhD dissertation, Moscow Aviation Institute, Moscow.

[24] Nassirharand, A. and Karimi, H. (2005), “Mixture ratio control of liquid propellant engines”, Aircraft Engineering &

Aerospace Technology: International Journal, Vol. 77 No. 3, pp. 236-42.

[25] Mohinder L. Nayyar.(1999), “Piping Handbook 7th

edition”, McGraw-Hill Professional Publishing, NewYork

[26] Kazlov, A.A.(1988), “Control and feed system’s elements of liquid propellant rocket engines”, Mashinostroenie, Moscow.

[27] Jalali Chimeh, A.R.,”Modeling and Simulation Of Apparent Velocity Regulation System” master thesise in Aerospace

engineering in Khaje Nassire dine Toosi University of Technology (KNTU),Spetember 2010.

[28] M.Naderi Tabrzi,”Modeling and Simulation Of Propllant Utilization System in LPEs” master thesise in Aerospace

engineering in Khaje Nassir e dine Toosi University of Technology (KNTU),Spetember 2010.

[29] Jalali.S.A.R, Naderi.M, Karimi.H,(2009), “Nonlinear Dynamic Modeling and Simulation of LPEs”, paper presened at DSTC

Conference, 7th Oct, Malaysia.

[30] Karimi,H., Taheri, E.E.,(2006),"Simulation of the Internal Ballistics of A Liquid Propellant Engine Start System In

Comparison With Experimental Verification ", paper presented at European Conference on Computational Fluid Dynamics,

5-8th Sep., Netherland.

[31] Karimi,H., Mohamadi,R, and Taheri,E.E (2007), “Dynamic Simulation And Parametric Study Of LPEs”, IEEE , pp.219-244.

4.1. Tables

Table1. LPE elements

EL1-Oxid Tank EL10-Fuel Valve

EL2-Pipe EL11-Fuel Main CC Pipe

EL3-Oxid Pump EL12-CC Stabilizer Valve

EL4-Oxid Valve EL13-Turbine

EL5-Oxid Main CC Pipe EL14- Starter

EL6-Oxid GG Pipe EL15-Gas Generator

EL7-Fuel Tank EL16-Thrust Regulator

EL8- Pipe EL17-GG Stabilizer Valve

EL9- Fuel Pump EL18-Combustion Chamber

Table2- Major Characteristics of the simulated LPE

1 Number of Combustion Chambers

N2O4+UDMH Propellants

12.5-13.75 ton thrust Thrust (sl-vac)

270-300 s Specific Impulse (sl-vac)

80 bar CC Pressure

11.5 cm CC Throat Diameter

2.6 Propellant Mixture Ratio in CC

14.55 CC Nozzle Area Ratio

70 bar GG Pressure

3 cm GG Throat Diameter

0.18 Propellant Mixture Ratio in GG

14.55 GG Nozzle Area Ratio

10 cm Pump’s Impeller Diameter

20 cm Turbine’s Impeller Diameter

21300 rpm Turbine’s Nominal Rotational Speed

Cold Gas Propellant Tank Pressurization


4.2. Figures

Fig.1 Modelled Engine Schematic

Fig.2 Mass flow Ccalculation in a Hydraulic System


Fig.3 Main Program’s Flowchart

Fig.4 Gas Generator Simulation Flow chart


Fig.5 Combustion Chamber Simulation Flow Chart

Fig.6 Thrust Regulator simulation Flowchart


Fig.7 Satabilizer Simulation Flowchart

Fig.8 LPE Simulator Interface


Fig.9 Oxidizer Tab

Fig.10 Main Combustion Chamber Tab

Fig.11 Turbine Rotational speed vs. time


Fig.12 GG Pressure vs. time

\ Fig.13 CC mixture ratio vs. time

Fig.14 CC’s normalized pressure comparison diagram

Normalized time

No

rma

lize

dC

Cp

ressu

re

0.2 0.4 0.6 0.8 1 1.20

0.2

0.4

0.6

0.8

1

1.2Pcc_Simulation

Pcc_Experimental


Fig.15 GG’s normalized pressure comparison diagram

Fig.16 Turbine’s normalized comparison diagram

Fig.17 Starter’s normalized pressure comparison diagram

Normalized time

No

rma

lize

dG

Gp

ressu

re

0 0.2 0.4 0.6 0.8 1 1.2

0.2

0.4

0.6

0.8

1

1.2

1.4Pgg_Simulation

Pgg_Experimental

Normalized time

No

rma

ilze

dP

um

psp

ee

d

0.2 0.4 0.6 0.8 1 1.2

0.2

0.4

0.6

0.8

1

1.2Pump speed _ Simulation

Pump speed _ Experimental

Normalized time

No

rma

lize

dP

sta

rte

r

0 0.2 0.4 0.6 0.8 10

0.2

0.4

0.6

0.8

1

Normalized Pstarter_ Simulation

Normalized Pstarter_Experimental


Fig.18 Starter’s Normalized mass flow comparison diagram

Normalized time

No

rma

lize

dM

do

t

0 0.2 0.4 0.6 0.8 10

0.2

0.4

0.6

0.8

1

Normalized Mdot _ Simulation

Normalized Mdot _ Experimental


4.3. Equations

2eqm K p (1)

11 ( )

D teq

t

C AK

A A

(2)

f lP P P (3)

2

V

d

LfP

2

f

(4)

2

2l

VP k

(5)

2

VkP

2 (6)

*f ox th

PdP RTm m A

dt C V

(7)

GG St fuel pump oxid pump

eq

Tq Tq Tq Tqd

dt J

(8)

p

gHmTq

(9)

2

1 1 12

Q Q A B ( ) C ( )

H

(10)

2

0 0 0( ) ( )turbine

ad ad

U UA B C

C C

(11)

)60/( meanDU (12)

spad WC 2

(13)

spmWTq

(14)

1

11

spW RT PR

(15)

( 1)

( 1)

0

2( ) ( )

1

no ob b o o

o o

V dPA aP A P

RT dt RT

(16)


Nomenclature

A a constant that is experimentally

determined for solid starter Keq

equivalent discharge

factor Tqst

Torque produced by the starter

exhausts acting on the turbine

A cross section area 2m L pipe length u tangential velocity

A* starter’s nozzle throat area 2m m

mass flow rate in pipe,

valve, or pump Kg / s v liquid velocity in pipe or valve

Ath CC throat cross section area 2m fm fuel mass flow rate, kg / s V chamber volume

A1 Ovsianokov’s experimental

coefficient oxm oxidizer mass flow rate,

Kg / s V0 gas volume in the starter

B1 Ovsianokov’s experimental

coefficient n

starter burn rate exponent

that is experimentally

determined,

(dimensionless)

Wsp turbine specific work

C1 Ovsianokov’s experimental

coefficient P

pressure in combustion

chamber or gas

generator, Pa

blade angle

Cad adiabatic speed coefficient P0 starter total pressure, Pa Specific heat ratio coefficient

C* characteristic speed PR

turbine expansion ratio,

(dimensionless) liquid density

D pipe diameter Q volumetric mass flow

rate b solid propellant density

D blade diameter R gas constant Pump efficiency

F moody factor t time variable 3.14…

G Acceleration due to gravity T Temperature angular velocity of turbo-

pump shaft

H Pump head Tq-fuel

pump

fuel-pump required

torque P

pressure drop due to a

combination of frictional and

geometrical losses

Jeq equivalent moment of inertia

Tq-

Oxidiser

pump

oxidizer-pump required

torque fP pressure drop due to frictional

losses

K loss factor due to friction TqGG

Torque produced by gas-

generator exhausts acting

on the turbine lP pressure drop due to

geometrical losses

Please cite this article as: M. N. Tabrizi, S. A. J. Chime, H. Karimi, (2013), Modeling And Simulation Of Open Cycle Liquid Propellant Engines, Science

and Engineering, Vol. 1(1), 17-34.



www.oricpub.com


Vol. 1 (1), 2013, 35-42



EVOLUTION OF STRUCTURAL DAMPING FOR CROSS-PLY

LAMINATE BY MODAL ANALYSIS

D. Bensahal1, M. N. Amrane

1, F. Chabane

1, O. Belahssen

2, S. Benramache

2

1 Mechanics Department, Faculty of Sciences &Technology, University of Biskra, Algeria

2Material Sciences Laboratory, Faculty of Science, University of Biskra, Algeria

Abstract The work concerned exactly a structural damage of cross-ply laminate as function of

loading rate. In this paper also involves the effect of loading rate on the damping of the

composite. The calculation of laminate damping is performed by use of a strain energy

method. The modal analysis of the structure for different loading rates is based on the

analytical method used to solve the equation of free vibrations. The difference between

strain energies for both cases damaged and undamaged are calculated by the finite

element method. The structural damping of the beam is evaluated from these energies.

The result deduced from the damping by finite element analysis that the structural

damping η increases when the loading rate becomes higher. This study shows clearly the

decrease of the frequencies when the loading rate increases; this should have high utility

as a decisive test for non-destructive damage detection.

1. INTRODUCTION The increasing need for high-performance structures has stimulated

considerable research in the characterization of damping in advanced

composite materials. Helicopter rotor blades, turbine compressor blades

and space structure truss elements are examples of aerospace applications

of composites where damping properties are important. Damping is a

measure of the energy dissipation in any vibrating structure. The progress

has been achieved in the analysis and measurement of dynamic properties

of composite materials. For example, closed –form solutions for dynamic

stiffness and damping properties of laminated plates and laminated beams

have been derived, and finite element methods have been used in both

macro mechanical and micromechanical modeling [1, 3]. Viscoelastic

materials combine the capacity of an elastic type material to store energy

with the capacity to dissipate energy. So, the use of an energy approach for

evaluating the material or structure damping is widely considered. In this

energy approach, the dissipated energy is related to the strain energy

stored by introducing a damping parameter [4]. The initial works on the

damping analysis of fibre composite materials were reviewed extensively

in review paper by Gibson and Plunkett [5] and Gibson and Wilson [6]. A

damping process has been developed initially by Adams and Bacon [7]

who sees that energy dissipation can be described as separable energy

dissipations associated to the individual stress components. This analysis

was refined in later paper of Ni and Adams [8]. The damping of

orthotropic beams is considered as function of material orientation and the

papers also consider cross-ply laminates and angle-ply laminates, as well

as more general types of symmetric laminates.


Keywords: Structural Damping

Finite Element Method

Modal Analysis

Frequencies

Cross-Ply Laminate

Correspondence: D. Bensahal

Mechanics Department,

Faculty of Sciences

&Technology, University

of Biskra, Algeria


The damping concept of Adams and Bacon was also applied by Adams and Maheri [9] to the investigation

of angle-ply laminates made of unidirectional glass fibre or carbon layers. The finite element analysis has been

used by Lin et al. [10] and Maheri and Adams [11] to evaluate the damping properties of free-free fibre

reinforced plates. These analyses were extended to a total of five damping parameters, including the two

transverse shear damping parameters. More recently the analysis of Adams and Bacon was applied by Yim

[12] and Yim and Jang [13] to different types of laminates, then extended by Yim and Gillespie [14] including

the transverse shear effect in the case of 0° and 90° unidirectional laminates. For thin laminate structures the

transverse shear effects can be neglected and the structure behavior can be analyzed using the classical

laminate theory.

The natural frequencies and mode shapes of rectangular plates are well described using the Ritz method

introduced by Young [15] in the case of homogeneous plates. The Ritz method was applied by Berthelot and

Safrani [16] to describe the damping properties of unidirectional plates. The analysis was extended to the

damping analysis of laminates [17]. In this study, we considered that there is the simplicity of calculations

while assuming that the structure is subjected of free vibration and undamped. After each fatigue cycle, we

have a new value of Young’s modulus as reported in Figure 1. Our assumption supposed that the material of

each beam studied is homogeneous and it established a relation between the results of Young’s modulus found

experimentally that will be consequently injected into the model which is simple basing on the finite element

method. The idea is to replacing the Young’s modulus found experimentally in the equations of finite element

method. Hence, we keep the same programs developed. This paper presents an evaluation of the structural

damping as function of loading rate using finite element method for cross-ply laminate C1.

2. MATERIAL The laminate was prepared by hand lay-up process from SR1500 epoxy resin with SD2505 hardener and

unidirectional E-glass fibre fabrics of weight 300 (g/m2). Beam had a nominal width of 20 mm, were cured

at room temperature with a pressure of 30 kPa using vacuum moulding process, and then post-cured for 8h

at 80°C in an oven. Beams had a nominal thickness of 2 mm with a volume fraction of fibres equal to 0.40.

The laminated beams with height lengths for each material are analyzed. The mechanical modulus of

elasticity of the material was measured in static tensile. Unidirectional composites have exceptional

properties in the fibre direction and mediocre properties perpendicular to the fibre directions. There are very

few situations where composites are used purely in a unidirectional configuration. In most applications there

will be some form of loading away from the direction of the fibres. In this situation, it is only the resin that

resists this load which has no reinforcement. Hence, composites structures are made by combining

unidirectional laminates in different directions to resists these loads as material C1. Many products in a

variety of industries are fabricated from composites, from fighter aircraft to bath tubs. There are more

examples in different industries including: Automotive and rail, boating, general engineering, aerospace,

sporting goods, civil engineering, domestic and medical. The mechanical characteristics of C1 material are

reported in table 1:

Table 1. Mechanical characteristics of composite material C1

Stacking Sequences [(0/90)s]2

Young’s modulus (GPa) 14.51

Max load of rupture (KN) 20.020

The experimental Young’s modulus was obtained by using tensile cyclic tests. The applied load ratio is

10 % of maximum load of rupture or failure. The loading rate is the ratio of the load relative to the

maximum load failure. We divided the maximum force of rupture in ten equal parts (10 cycles), for each

cycle the load is increased by 10% of the maximum load failure. After each fatigue cycle, we have a new

value of Young’s modulus as reported in Figure 1. It established a relation between the results of Young’s

modulus found experimentally that will be consequently injected into the model which is simple basing on

the finite element method. The idea is to replacing the Young’s modulus found experimentally in the

equations of finite element method. Hence, we keep the same programs developed. Fig.1 shows the results

obtained for the Young’s modulus reduction as a function of cycle number or load rate.

37 | P a g e D. Bensahal, M. N. Amrane, F. Chabane, O. Belahssen, S. Benramache

Fig. 1. Stiffness reduction of cross-ply laminate C1as function of load rate.

3. FINITE ELEMENT METHOD IN THE DYNAMIC ANALYSIS

The flexural vibrations of beams are analyzed by the finite element method [20], using the stiffness

matrix and mass matrix of beam element with two degrees of freedom per node as shown in Fig.2, where:

Fig. 2. Beam element with four degrees of freedom.

E: the Young modulus.

I: the moment of inertia of the beam.

L: the length of the beam.

S: the section of the beam.

ρ: the density.

22

22

3e

L4L6L2L6

L612L612

L2L6L4L6

L612L612

L

IEK

(1)

22

22

e

L4L22L3L13

L22156L1354

L3L13L4L22

L1354L22156

420

LSM

(2)

The global matrix of mass and stiffness are obtained by using assembly method:

BdesMTBM

BdesKTBK

(3)


Where B is the Boolean matrix and Kdes and Mdes are unassembled matrix, they contain only elementary

matrices of mass and stiffness. The number of elements used in this study is 40 elements.

N

eK0

01

eK

desK

(4)

N

eM0

01

eM

desM

(5)

4. RESOLUTION OF EIGENVALUES PROBLEM We have two cases where the structure is undamaged or damaged.

The equation of motion (undamped and free vibration)[23]:

0tqktqm

(6)

The equation (6) can be written in matrix form:

0qKqM

(7)

With q is the vector of degrees of freedom. For the first case [K] is the global stiffness matrix but for the

second case [K] = [KD]. Where [KD] is the global stiffness matrix with damage, that takes into account the

decrease in the rigidity of the structure when the loading rates change [20].

The general solution of equation (7) is:

ti0 eqq (8)

By substituting the equation (8) in equation (7), we have:

02

0 qMqK (9)

Then, the determinant must be zero:

0)M2K(det (10)

There are many methods to calculate the eigenvalues; the most of these methods are to write the equation

(9) as follows:

XXH (11)

Where [H] is a positive and symmetric matrix, it is clear that if we write directly the equation (9) as:

0201

q1

qMK

(12)

Where [K]-1

is the inverse of the matrix [K], the symmetry property is not always preserved. Therefore, it

is necessary to write the matrix [K] using the Cholesky decomposition:

TLLK (13)


[L]T is the transpose of the matrix [L] and [L] is a lower triangular matrix. The equation (9) is written:

020T1

qL1

qLLML

(14)

By writing equation (14) as similar form as equation (9):

T1LMLH

(15)

0qLX (16)

2

1

(17)

5. EVALUATION OF STRUCTURAL DAMPING The calculation of structural damping factors of modal energies for the first three modes of vibration of

the structure is done by evaluating the ratio of the strain energies of beam for damaged and undamaged cases

[20, 21].

The modal strain energy of the beam for the undamaged case is given by:

qKTq2

1nU (18)

With:

[K]: Stiffness matrix;

[q]: Eigenvector of displacement.

The modal strain energy for damaged case is given by:

DqDKT

Dq2

1nDU (19)

With:

[KD]: Stiffness matrix (damaged case);

[qD]: Eigenvector of displacement (damaged case).

The structural damping coefficient [20] for different stages of damage (different loading rates) is given

by:

n

nDn

n

nn

U

UU

U

U

(20)

With Un and UnD are the modal strain energies for undamaged and damaged case.

6. Results The modal analysis of the structure for different loading rates is based on the analytical method used to

solve the equation of free vibrations. The programming of this resolution method was performed under the

Matlab software. The figures 3, 4 and 5 show the frequencies obtained by the model for different loading rate.

The decrease in frequency since undamaged case (0% loading rate) which not subject to any cyclic loading

until damaged case (90% loading rate), shows the loss of stiffness of the materials C1 studied [16, 19]. The

decrease in frequency can be used also as a means of non-destructive control of composite materials. Simply,

we limit ourselves to the first three modes due to congestion of results. For the compute of the damaged

stiffness matrix is simulated by replacing the Young’s modulus of undamaged structure Eo by another

Young’s modulus derived from Figure 1 for example for the fifth cycle (for loading rate 50%) and ninth cycle

(for loading rate 90%). For the material C1:

EoC1 = 14.51 GPa


Loading rate 50%:

95.0*1CEo%50E95.0

1CEo

%50E

Loading rate 90%:

93.0*1CEo%90E93.0

1CEo

%90E

Figures 3-5 provide information on the evolution of the first three modes of the structure under the action of

different loading rate and show also the frequencies obtained by the model. The steps to calculate them are:

•First, we calculate the natural frequencies of the structure for different loading rate (10%-90%) by using

finite element method,

•Comparing the natural frequencies obtained by the model for different loading rate (0%, 10%… and 90%),

we observed that has been a decrease in frequency when the loading rate increases [18, 19] confirm the

decrease of the Young’s modulus shown in Figure 1. This is very important for the behavior of composite

materials during their service. This can be used as a control of loss of stiffness of the structure and

subsequently its life time.

The increase of structural damping indicates simply the maximum values it can attain, in the same way the

decrease of structural damping indicates the minimum values it can attain.

Fig. 3. Natural frequencies obtained by the model for the first mode of structure

Fig. 4. Natural frequencies obtained by the model for the second mode of structure


Fig. 5. Natural frequencies obtained by the model for the third mode of structure

Fig. 6. Evolution of structural damping as function of the load rate

Figure 6 reports the results deduced for the structural damping η [22] by finite element analysis shows an

increase in damping between 1 % until 7% when the loading rate increases.

7. CONCLUSION For the case of dynamic analysis, the finite element technique was used to calculate modal analysis in

composite structure. Of particular interest are the resulting modal parameters such as frequencies and

damping. The strain energy calculation is performed by using a finite element analysis of the vibrations of a

composite structure. Figure 6 give us information about the evolution of structural damping value for each

mode which is not constant and varies in load rate to another. The decrease in frequency of different loading

rates shows the loss of stiffness for the beam studied. The structural damping of the composite material can be

deduced by applying modeling to the flexural vibrations of free-clamped beams. The results deduced from the

damping by finite element analysis for the first mode shows that the evaluation of laminate damping takes

account the variation of the structural damping η with load rate for the laminate beam C1. The damping begins

by cracks and leads to a loss of stiffness witch can be appreciable when the loading rate increases; this should

be taken into account in all analysis. The decrease in frequency can be considered as an important tool test for

damage detection.


REFERENCES

[1] Gibson, R.F. (1987). Dynamic mechanical properties of advanced composite materials and structures: a

review. Shock Vibration Digest, 19(7), pp.13-22.

[2] Johnson, C.D. & Kienholz, D.A. (1984). Finite element prediction of damping in structures with

constrained viscoelastic layers. AIAA, 20(9), pp.1284-1290.

[3] Hwang, S.J. & Gibson, R.F. (1987). Micromechanical modeling of damping in discontinuous fiber

composites using strain energy/ finite element approach. J. Eng. Mat. Tech., 109, pp.47-52.

[4] Berthelot, J.M. (1999). Composite materials, Mechanical behaviour and structural analysis. Springer,

New York.

[5] Gibson, R.F. & Plunkett, R.A. (1977). Dynamic stiffness and damping of fibre-reinforced composite

materials. Shock Vibration Digest, 9(2), pp.9-17.

[6] Gibson, R.F. & Wilson, D.G. (1979). Dynamic mechanical properties of fibre-reinforced composite

materials. Shock Vibration Digest, 11(10), pp. 3-11.

[7] Adams, R.D. & Bacon, D.G.C. (1973). Effect of fibre orientation and laminate geometry on the

dynamic properties of CFRP. J. Compos. Mater. , 7, pp. 402-408.

[8] Ni, R.G. & Adams, R.D. (1984). The damping and dynamic moduli of symmetric laminated composite

beams. Theoretical and experimental results. Compos. Sci. Technol., 18, pp. 104-121.

[9] Adams, R.D. & Maheri, M.R. (1994). Dynamic flexural properties of anisotropic fibrous composite

beams. Compos. Sci. Technol., 50, pp. 497-514.

[10] Lin, D.X., Ni, R. & Adams, R.D. (1984). Prediction and measurement of the vibrational parameters of

carbon and glass-fibre reinforced plastic plates. J. Compos. Mater. , 18, pp. 132-152.

[11] Maheri, M.R. & Adams, R.D. (1995). Finite element prediction of modal response of damped layered

composite panels. Compos. Sci. Technol., 55, pp. 13-23.

[12] Yim, J.H. (1999). A damping analysis of composite laminates using the closed form expression for the

basic damping of Poisson’s ratio. Compos. Struct., 46, pp. 405-411.

[13] Yim, J.H. & Jang, B.Z. (1999). An analytical method for prediction of the damping in symmetric

balanced laminates composites. Polymer Compos., 20(2), pp. 192-199.

[14] Yim, J.H. & Gillespie, Jr. J.W. (2000). Damping characteristics of 0° and 90° AS4/3501-6

unidirectional laminates including the transverse shear effect. Compos .struct., 50, pp. 217-225.

[15] Young, D. (1950). Vibration of rectangular plates by the Ritz method. J. Appl. Mech., 17, pp. 448- 453.

[16] Berthelot, J.M. & Sefrani, Y. (2004). Damping analysis of unidirectional glass and Kevlar fibre

composites. Compos. Sci. Technol., 64, pp. 1261-1278.

[17] Berthelot, J.M. (2006). Damping analysis of laminated beams and plates using the Ritz method.

Compos. Struct., 74, pp. 186-201.

[18] Whitworth, H.A. (1998). A stiffness degradation model for composite laminates under fatigue loading.

Compos. Struct., 40(2), pp. 95-101.

[19] Whitworth, H.A. (2000). Evaluation of residual strength degradation in composite laminates under

fatigue loading. Compos. Struct., 48, pp. 261-264.

[20] Amrane, M.N. & Sidoroff, F. (2011). Residual modal energy evaluating of fatigue damaged composite

structure. Mechanika., 17(1), pp. 45-49.

[21] Elmahi, A., Assarar, M., Sefrani, Y. & Berthelot, J.M. (2008). Damping analysis of orthotropic

composite materials and laminates. Composite: part B, 39, pp. 1069-1076.

[22] Hwang, S.J. & Gibson, R.F. (1991). The effect of three-dimensional states of stress on damping of

laminated composites. Compos. Sci. Techno., 41, pp. 379-393.

[23] Bensahal, D., Amrane, M.N. & Alloua, B. (2012). Comparison of the dynamic behavior of a

manipulator with two flexible arms. Ijsei, 1(10), pp. 20-24.

Please cite this article as: D. Bensahal, M. N. Amrane, F. Chabane, O. Belahssen, S. Benramache, (2013), EVOLUTION OF STRUCTURAL DAMPING

FOR CROSS-PLY LAMINATE BY MODAL ANALYSIS, Science and Engineering, Vol. 1(1), 35-42.



www.oricpub.com


Vol. 1 (1), 2013, 43-54



REMOTE SENSING SATELLITE DESIGN USING MODEL

BASED SYSTEM ENGINEERING

Mohammad Sayanjali

1, Oldouz Nabdel

2

1Dept. of Aerospace

Sharif University of Technology

Tehran, Iran 2Dept. of Aerospace

Amirkabir University of Technology

Tehran, Iran

Abstract

In this paper, remote sensing (RS) satellite conceptual design phase, by utilizing model

based system engineering method and system modeling language (SysML) is studied.

The RS satellite captures image in two visual and IR spectrum, in low Earth orbit.

Block definition diagrams (BDD) are created to specify physical architectures for

systems and subsystems. By defining parametric diagram (PD) for system sizing and

efficiency measuring, trade-off study is implemented. Two parameters are defined to

compare different architectures; total image, could be captured in satellite lifetime, and

cost per image scene. Design parameters considered in trade-off study are: Image

Resolution, Orbit Altitude, Lifetime, Solar Array and Battery Type, Number of Ground

Stations, AODCS architecture (with or without propulsion), Imaging Time in each orbit

and etc.

1. INTRODUCTION

Conceptual design includes definition of physical architecture, interfaces,

functional requirements and allocation of design budgets (mass, power

and data processing). Furthermore in Conceptual phase, designer must

select an architecture among different architectures based on defined

parameters such as Measure of Effectiveness (MOE) or Measure of

Success (MOS). Model based system engineering (MBSE) based on

SysML language is a new method of system engineering against

document based system engineering. MBSE contrasts with

document-based approaches by stating that they aim to develop the

design through model elaboration rather than document elaboration [1].

The problem with most complex system is that of integrating information

across many large teams. As designs grow and change, ripple effects

develop and maintaining documentation a Sisyphean task. On the other

hand, a major drawback of a document based approach is due to inherent

difficulties in maintaining the consistency and validity of the documents,

provided by different design teams, while at MBSE it is possible to

maintain a good synchronization between system requirements and the

evolving design. Plus, variant system design options and the quality of

the evolving design can be checked using the developed system model

[2].


Keywords: Model Base System Engineering

Spacecraft Conceptual Design

SysML

Trade-off Study

Correspondence: Mohammad Sayanjali

Department of Aerospace

Sharif University of

Technology

Tehran, Iran


In this method, several defined diagrams model process of conceptual design. Block Definition

Diagram (BDD) defines physical architecture of system [3], Internal Block Diagram (IBD) defines

mechanical or electrical interface between elements or subsystem of system. Requirement Diagram (RD)

defines requirements, tractability and test case that verify each requirement.

Parametric Diagram (PD) defines equation that used for design budget allocation and provides

appropriate tool for trade-off study.

In this paper, remote sensing satellite conceptual design process modeled in MagicDraw 16.6. RS satellite

design parameters include the following: orbit altitude, solar array and battery type, payload data

compression factor and etc. In Microsoft Excel, design scenarios and variables are defined in rows and

columns, sequentially. Using equations defined in parametric diagrams, mass, power and data storage

capability of each subsystem are computed. Using cost estimation relationship (CER) for small satellites [4]

total cost of satellite is computed. By calculating total image captured in satellite lifetime, measure of

effectiveness (cost per image) is computed to compare different designed scenarios.

2. REMOTE SENSING SATELLITE DESIGN PROCESS

2.1. Overall Conceptual Design Process

In this section, the process used for RS satellite design is introduced briefly. Each design has numbers of

input information or input design parameters which based on them, other parameters extracted. Then, the

extracted parameters are input for design of below subsystem. On the other hand, each design, have some

constraints or specification that bound design domain. One of mission constraints is capturing images in two

visual and infrared spectrums in low earth orbit.

Input design variables within various values for trade-off study are: Ground Sampling Distance (GSD) or

Resolution, Orbit Altitude, Global Coverage Time, Revisit Time, Number of Ground Station and Allowed

Altitude Decent, payload data compression factor, solar array, battery type and lifetime.

Two parameters, global coverage time and orbit altitude h , define swath based on (1)

2

GlobalCoverageTime×OrbitRevolutionPerDay

earthRSwath

(1)

Revisit time m and orbit altitude define roll angle attitude maneuver (along x axis, directed toward

satellite’s linear velocity) by (2)

3

2 1 14 cos( )

2

earth

E ES

d

d

maneuver

aR Latitude

FOVm Altitude

FOV FOV

(2)

Swath is related to optical payload’s field of view, opticFOV , which is input parameter for payload design.

Using orbit altitude and diffraction limited diameter relation, diameter of Optical payload, opticD , can be

sized. Decision about optical diameter is not only based on diffraction limited, but also considered Aperture

diameter obtained from detector noise limited and Photon noise limited [5]. After computation of optical

diameter, mass and consumed power of payload estimated using relation defined in payload section design

(3). 6.5323.8598 D

payloadM e

(3)

Utilizing statistical method that relate total satellite mass and power to payload mass and power

respectively, total mass (4), power, dimension and satellite’s moment of inertia (MOI) could be calculated.

This information is input parameters for AODCS, Power subsystem and etc. As an example, mass relation

is:

45 | P a g e Mohammad Sayanjali, Oldouz Nabdel

3.15 15.7satellite payloadM M

(4)

In AODCS design two architectures are considered:

A1- Propulsion+ Reaction Wheel + Magnetic Torquer

A2- Reaction Wheel + Magnetic Torquer

If computed descent altitude (5), is larger than allowed altitude descent, A1 architecture would be selected.

In this configuration propulsion subsystem used for orbit correction, reaction wheel momentum dumping

and attitude maneuver. In A2 architecture, reaction wheel is used for both attitude control and maneuver, and

Magnetic torquer is used for reaction wheel momentum dumping.

One of payload’s output parameters is data rate (DR). This parameter is input for communication and

C&DH subsystem. Using payload DR, Housekeeping (HK) data rate, communication time cT (5) and

number of ground station, mass and power of communication subsystem can be calculated.

3

1

2

sin sin

com c

c c h c

p

rT

r

R

(5)

In (5), c is nadir angle to effective communication horizon, h is nadir angle to horizon and c is nadir

angle reduction to avoid communication problems.

Similarly using DR_Payload, DR_HK, imaging time in each orbit (design parameter) and number of

ground station, mass and power of data storage and CPU can be estimated. Detailed description is brought in

the following section.

Power that solar array should be generated can be set equal to total satellite power estimated from

statistical relationship or from summation of AODCS, Payload, communication and C&DH power. By

selecting type of solar array, one of design parameters, area of solar array can be computed. If computed

area is larger than surface of satellite then deployable solar panel must be selected rather than body-mounted

solar panel. Structure mass computed using proportional relation between total satellite mass and structure

mass. Thermal Subsystem mass is considered proportional to radiator area which computed using

heat-balance equation.

2.2. SysML Diagram

Block definition diagram (BDD) of satellite system’s general structure is shown in Fig. 1. Note that in the

figure physical architecture of Satellite system is shown. In some of the figures, attribute of block is

suppressed. In Fig. 2 one of parametric diagrams used in satellite system is shown.

Fig.1. BDD of Satellite System


3. SUBSYSTEM DESIGN EQUATIONS

In this section, conceptual design of satellite subsystem is explained briefly.1

3.1. Payload

The Earth observation sensor is sized and configured for imaging in the visual (6 6: 0.3 10 to 0.75 10V m )

and infrared 6 6: 0.75 10 to 100 10IR m spectrum. Physical architecture of payload is shown in Fig. 3. As

shown in Fig. 3 payload system consists of Optical Unit, Data Storage Unit and Cryogenic cooler that used

for imaging in IR spectrum. Calculation of aperture’s diameter depends on whether the dominating system

noise is internally generated detector- noise or externally generated photon-noise. The two types are often

called detector-noise limited (dnl) and photon- noise limited (pnl) respectively. Diameter obtained from dnl

and pnl computed as follows:

1/2 1/2

2

*

4 /

arctan

e

s n d

dnl

dem

S N f AD

dF D

f

(6)

2

2

4 /

arctan

e p

s

pnl

dem i

S N c cD

dF T

f

(7)

Fig.2. Parametric Diagram for "Satellite System" Block

In (6) and (7) parameters define as follows:dA , Area of detector,

dd , diameter or width of detector, f ,

sensor focal length, *D , detectivity figure of merit, , payload wavelength and iT , integration time.

Integration time has proportional relation with dwell time (8).

/

i d

d

d

pix

T T

h d fT

VN

(8)

1Most of equations of this part are based on reference [5].


is degree of overlap between pixels on the ground. 1 indicates that there is no overlap and 0.5

indicates there is a 50% overlap between pixels. V is satellite linear velocity in orbit.

Fig.3. BDD of Imaging Payload

Payload data rate is a parameter that should be computed in conceptual design for sizing C&DH and

Communication Subsystem. Instantaneous detector field of view computed by (9)

tan ddh

f

(9)

Number of pixels in pushbroom scanning method is equal to

pix

FOVN

(10)

And finally payload data rate computed as follows:

/payload pix SF iDR N sbe T (11)

Where SFe , sensor frame efficiency or time fraction for data transmission is typically in the range of

0.9-0.95%, b number of bit per sample and s is number of sample per pixel which typically has values 1.4

to 1.8.

3.2. AODCS

In this study, AODCS architecture is the common one that utilized in remote sensing missions. In most

RS satellites, three-axis stabilized method with combination of reaction wheels (RWs), magnetic torquers

(MTs) or thrusters are used. In trade-off study, implemented in the software, two architectures are

considered (actuator architecture):

First Configuration: Reaction Wheels + Magnetic Torquers

RWs used for both attitude control and maneuver, and MTs used for momentum dumping.

Second Configuration: Reaction Wheels + Thrusters+ Magnetic Torquers


RWs used for attitude control, Thrusters used for attitude maneuver, momentum dumping and orbit

correction, and MTs used for specified modes.

If altitude descent of satellite is larger than allowed descent value then second architecture is used. In the

following, equations used for sizing of actuators in both configurations are explained.

Satellite altitude descent time computed by:

2/ 2 /h c D SCT h T C A M r (12)

Where ch is allowed descent value. If hTis smaller to satellite’s lifetime then propulsion subsystem

would be included.

In first AODCS configuration, reaction wheel sized for attitude maneuver because the torque required for

attitude maneuver is larger than the one for attitude control (disturbance rejection).

In second AODCS configuration reaction wheel is sized for disturbance rejection, or attitude control, and

thruster sized for reaction wheel momentum dumping and attitude maneuver. Reaction wheel mass is equal

22 /rw AD rw rwM r

(13)

Where rw , angular acceleration of the reaction wheel, AD , aerodynamic torque and rwr is reaction

wheel radius. Common reaction wheel radius range is 0.1-0.25 m. Time between reaction wheel momentum

dumping or time that reaction wheel will be saturated is equal to

max /md rw rwT (14)

max

rw is maximum angular velocity, about 6000 rpm 26.28 10 rad/sec . Power required to accelerate each

reaction wheel is equal to

2

rw rw rw mdP I T (15)

In the following part, propellant mass and thrust force are calculated for both reaction wheel momentum

dumping and attitude maneuver. Thrust force for momentum dumping calculated by

max

/

rw

Th md

b Th

HF

T l

(16)

Where bT , burn time per thruster pulse in sec, is between 0.02 and 0.1 sec and Thl is distance from satellite

principal axes to thruster. Total propellant used for momentum dumping is equal to

max

/ .lifeTimerw

p md

sp Th md

THM

gI l T

(17)

Thrust force level and propellant mass for one attitude maneuver computed by

/ 2

/

/

4Th Maneuvr

maneuver

Th Maneuver b

p maneuver

sp

FIt

F TM

I g

(18)


Propellant mass needed for orbit correction depends on allowable altitude descent and mission life time.

Number of orbit correction maneuvers can be written as follows:

missionLife

orbitCorrection

h HC

TN

T T

(19)

HCT is time in the Hohmann reboosting transfer. Propellant mass depends on total V which is needed for

altitude correction using Hohmann transfer method.

For a typical thruster system, the propellant tank mass is 5-15% of the propellant mass and propellant

management system has 20-30 % of the propellant tank mass.

Fixed architecture for determination part is considered. Star tracker, Gyroscope, Sun sensor and

magnetometer used as attitude sensors. The Star tracker provides a high accuracy. The gyroscope is added to

give the AODCS system a high accuracy attitude reference, in the time gap between star observations.

Frequently, gyroscope is referred as inertial sensor, and Star tracker, Sun sensor and magnetometer are

referred as reference sensors. The mass and power for sensors are given as independent input variables.

Fig.4. BDD of AODCS subsystem

Block definition diagram of AODCS subsystem is shown at Fig. 4. Parametric diagram used for reaction

wheel sizing in architecture 1 is shown in Fig. 5.

Fig.5. Parametric Diagram for reaction wheel sizing

3.3. Power Subsystem

The Power subsystem includes solar panels, a battery unit, a power control unit (PCU), a


regulator/converter unit and power wiring. Mass budgets of power subsystem’s elements computed as

follows.

The power should be generated by solar array computed by (20)

max max max/ / /sa ec ec SBS d ec SS ecP P T e P T T e T T

(20)

Area of solar array is function of spacecraft power, saP , the power produced by array at spacecraft end of

life EOLP and solar cell packing density, csq .

/sa sa EOL csA P P q (21)

EOLP is a function of the power, can be generated by the solar array per unit area at spacecraft beginning of

life BOLP , and the remaining efficiency of solar cells at spacecraft end of life EOLe which is function of type

of solar cells annual degradation and mission life time. For Silicon (Si) cells employed in LEO orbits, the

worst-case value for annual degradation, /s ye , equals to 3.75% and for Gallium-Arsenide (GaAs) cells the

worst case value equals to 2.75%. Finally proportional relation between solar array mass and its area, as a

function of solar cell type is defined.

Required battery capacity BC to power all spacecraft system during the eclipse time can be calculated as:

max / B

B ec ec l avg BSC P T DoD EP e (22)

Battery depth of discharge (DoD) range is between 40% to 60% for NiH2 batteries, and between 10% to

20% for NiCd batteries. In (22), B

avgEP is average discharge level of the batteries which assumed constant for

both battery types. Finally battery mass computed with equation: B

BAT B avg EM C EP

(23)

E , inverse specific energy range is 1/25 to 1/40 for NiH2 and 1/45 to 1/60 for NiCd batteries.

Trade-off study for this subsystem includes type of solar cell, Type of battery, DoD and E for each

type of batteries. Block Definition Diagram (BDD) for power subsystem is shown in Fig. 6.

Fig.6. BDD of Power Subsystem

3.4. Communication Subsystem

The communication subsystem consists of transmitter/receiver units, filters/switches/diplexers, and


uplink and downlink antenna (Fig. 7).

Fig.7. BDD of communication subsystem

The communication system is sized to dump, during available communication time over any ground

station, the payload data and housekeeping data stored on the data storage system. Total data rate for

communication system equals to

payload HK

c ca cb

DS DSDR

T T T

(24)

payloadDS is computed in payload subsystem design. In the above equation, caT is the time to set up

communication (set 30 sec). cbT is the buffer time at the end of the communication segment (set 30 sec).

Diameters of uplink and downlink antenna are design parameters that included in the scenario defined in

Excel worksheet for trade-off analysis. Antenna gain is computed using (25)

2 2 2/a a cG D (25)

a is figure of merit between 0 to 1 and c is communication wavelength. The power required by

communication subsystem calculated using Link antenna as follows:

0/T B

COM b S c l l s a r TP E c t DR L G L L G N e (26)

Where bE , received communication energy per bit and 0N , is communication system noise density. sL ,

space loss, lL , transmitter to antenna line loss and Te , is transmitter efficiency. 0/bE N is another design

variable in communication subsystem design which should be between 5 to 10.

Mass of transmitter has proportional relation to transmitter power. It’s assumed a proportional relation

between antenna mass and its diameter.

3.5. Data Storage and Processing Subsystem

The data processing and data storage (DP & DS) system is dimensioned to store and process the data


flows generated by the payload and the satellite housekeeping system. The DS&DP consists of a data

processing unit (CPU) and a data storage unit (DS).

Computing mass and power of CPU, assumed a proportional relation between mass, power and the total

number of instructions that need to be handled by the onboard CPU per second. Parametric diagram for

calculation of mass and power of CPU is shown in Fig. 8.

On-board processing compression of sensor data is a design variable that included in scenario for

trade-off study. Suggested value for compression factor is 50% to 90%. The data storage system (DS) is

sized to store HK and payload data between the time data is being generated and the time it can be

downloaded to ground station. In the following equation, GST is the time gap between download and CT is

the time of the download.

%payload payload GS T

HK HK C GS

DS DR K T

DS DR T T

(27)

Equations for mass and power estimation of data storage part are as follows

/

/

SS SS SS SS SS

DS F F inc inc

SS SS SS SS SS

DS F F inc inc

P P DS DS DS P

M M DS DS DS M

(28)

In above equation, DS , total data storage, SS

DSP , solid state data storage power and SS

DSM , solid state

data storage mass are computed and other parameters are constant.

Fig.8. Parametric Diagram for CPU Sizing

3.6. Thermal

A satellite contains many components that will function properly only if they are maintained within

specified temperature range. Thermal subsystem accounts on average for only 6% of a spacecraft's dry mass.

A satellite thermal design is highly dependent on the mission class and attitude stabilization type.

All of thermal subsystem architectures contain radiators. Radiators are sized for the hottest conditions.

The heat-balance equation can be written as follows [6]:

sin( )A

rad sT A AI P (29)


In (29) parameters define as follows: sI solar intensity, solar aspect angle, A area of radiator, Stefan-Boltzmann constant, absorptivity of the radiator and emissivity of radiator. The area of the

radiator, and consequently its mass, is proportional to the power dissipation

4 sin( )S

PA

T I

(30)

To first order it is considered the mass of the radiator to be proportional to BOLP

1rad BOLM k P (31)

It is also assumed that the rest of the thermal subsystem mass scales with the mass of the radiator

2thermal BOLM k P (32)

For an active thermal control subsystem, values of 2K , reflect realistic thermal control subsystem mass,

range between 0.02 and 0.035 kg/W.

3.7. Structure

The function of spacecraft structure is to provide mechanical support to all subsystems within the

framework of assumed configuration. Besides, it satisfies the subsystem requirements, such as alignment of

sensors, actuators, antennas, etc. and system requirements for launch vehicle interfaces and integration.

Spacecraft structure is a major contributor to the spacecraft dry mass and accounts for 21% of its dry mass

[6].

4. SATELLITE PARAMETRIC COST MODELING

Parametric cost modeling is a series of mathematical relationships that relates satellite cost to physical,

technical and performance parameters that are known to strongly influence satellite costs. The basis for the

relationships is a database of actual costs and technical parameters for several satellites. Parametric cost

modeling is one of the three typical ways to estimate costs of future systems, the other two are engineering

buildup and analogy [7]. The cost estimation relationships (CER), used in this study are from [4]. In the

reference, cost of each subsystem is computed using parameters related to the subsystem. For example

payload cost is computed using (33).

0.562

( ) 356,851payload Visible Light SensorC D

(33)

Where D is optical diameter (meter) and the cost is based on FY00$K.

5. TRADE-OFF STUDY

As mentioned before, purpose of this study is trade-off analysis of remote sensing satellite design. Design

parameters, mentioned in the paper context, mathematical calculation outputs, defined in parametric diagram,

and MOE are written in Microsoft Excel software. MagicDraw reads input design parameters from Excel

worksheet and writes computed parameters in the same excel file. As shown in Fig. 9, each row defines a

unique design scenario and each column contains a design parameter.

6. CONCLUSION

In this paper, Model Based System Engineering (MBSE) implemented for RS satellite design. An

advantage of this method is its capability to survey various architectures and values for design parameters.

The trade-off study is an important task in conceptual design phase according to ECSS. Using MBSE can

perform less effort than document based system engineering. Moreover, by modeling total system in a


model, trace of changes and interfaces between subsystems become easier. In future by linking MagicDraw

with STK software, parameters related to orbital dynamics such as communication time, altitude descent and

etc. can be computed more precisely. Noting that creation of block definition diagrams, parametric diagrams

and etc. are time consuming task but after creation of a model in the software, system engineering task

becomes easier and furthermore, it can be explore large domain of design solution.

Fig.9. Excel Worksheet for Trade-off Study

REFERENCES

[1] Cole, B. & Donahue, K. (2010). Piloting Model Based Engineering Techniques for Spacecraft Concepts

in Early Formulation. INCOSE.

[2] Qamar, A., & Wikander, J. (2009). Designing Mechatronic Systems, a Model-based Perspective, an

Attempt to Achieve SysML-Matlab/ Simulink Model Integration. IEEE/ASME International

Conference on Advanced Intelligent Mechatronics, pp.1306-1311.

[3] Weilkiens, T. (2006). Systems Engineering with SysML/UML, Modeling, Analysis, Design. London:

Elsevier, 2006.

[4] Larson, W. J., & Wertz , J., (2005). Space Mission Analysis and Design. London: Kluwer Academic

Publishers, 2005.

[5] Oxnevad, K. I.,(1996). A Total System Analysis Method For The Conceptual Design of Spacecraft : An

Application to Remote Sensing Imager System. PhD Dissertation: Old Dominion University, 1996.

[6] Saleh, J. (2002). Spacecraft Design Lifetime. Journal of Spacecraft and Rocket, Volume(39), No.2. pp.

244-257.

[7] Lao, N. Y. (1998). Small Satellite Cost Model, Version 98 InTRO. LosAngles: The Aerospace

Corporation, 1999.

Please cite this article as: M. Sayanjali, O. Nabdel, (2013), Remote Sensing Satellite Design Using Model Based System Engineering, Science and

Engineering, Vol. 1(1), 43-54.



www.oricpub.com


Vol. 1 (1), 2013, 55-66



INERTIAL NAVIGATION ACCURACY INCREASING

USING REDUNDANT SENSORS

Mahdi Jafari, Jafar Roshanian Aerospace Department, Khageh Nasir Toosi University of Technology, Tehran, Iran

ABSTRACT The inertial instruments can achieve high accuracy for long periods of time only by

redundancy. Redundant inertial measurement unit is an inertial sensing device

composed by more than three accelerometers and three gyroscopes. This paper analyses

the performance of redundant inertial measurement unit and their various sensors

configurations. By suitable geometric configurations it is possible to extract the

maximum amount of reliability and accuracy from a given number of redundant

single-degree-of-freedom gyroscopes or accelerometers. This paper gives particularly

attractive configurations of four, five and six sensors. These combinations are capable

of functioning with any three sensors, of detecting a malfunction with any four, And of

isolating a malfunction with any five. In contrast, arrangements with redundant sensors

whose input axes are parallel to only three orthogonal axes require five sensors to detect

and nine sensors to isolate a malfunction. The sensors configurations shown not only

minimize system error when all sensors are operable, but when all but three have

malfunctioned as well the reliability and accuracy of these redundant configurations are

compared to a conventional unit of three orthogonal instruments.

INTRODUCTION

Redundant sensors can provide highly accurate sensor data and also

reconfigure sensor network systems if some sensors failed. These create

the fundamentals for the design of fault-tolerant navigation systems and

the achievement of reliability and integrity of inertial navigation systems.

Overall navigation improvement is to be expected as there is more input

information. Through increased redundancy we can obtain noise

reduction in the navigation output parameters. In [1, 2] a comprehensive

analysis of the optimal spatial configuration of sensors for fault detection

applications is provided together. In addition, the performance for

fail-isolation systems in case a sensor is removed due to failure. Using

multiple sensors over a single sensor, We can improve the accuracy of

acquired information about an object have been recognized and

employed by many engineering disciplines ranging from applications

such as a medical decision-making aid system to a combined navigation

system [3]. Weis and Allan presented a high-accuracy clock with a

month error of one second through combining three inexpensive wrist

watches with month errors of 40 seconds in 1992 [4]. Actually this

technology used heterogeneous sensor data fusion to improve the

accuracy. Recently, some researchers have begun to take the similar idea

to improve the accuracy of sensor. Bayard combined four inexpensive

gyroscopes to form a virtual sensor with higher accuracy output, and

called this technology ’virtual gyroscope’ [5]. In the virtual gyroscope

the random noise of the gyroscope was estimated by using the Kalman

filtering for the further compensation, thus its accuracy was improved.


Keywords: Inertial Navigation

Fault-tolerant

Optimal Configuration

Redundant Sensor

Accuracy Increasing

Correspondence: Mahdi Jafari

KNTU University of

technology, Tehran, Iran


The correlation between the sensors was used to establish the covariance matrix of the system random

noise for filtering computation and better accuracy improvements. Lam proposed a very interesting concept

to enhance the accuracy of sensors via dynamic random noise characterization and calibration [6, 7]. The

first compensation uses external aiding sensors data such as GPS sensors, thus the high noise drift errors

such as bias, scale factor, and misalignment errors inherently existing in MEMS sensors will be eliminated.

The second compensation uses signal isolation and stochastic model propagation to dynamically monitor

changes and identify random noise parameters of MEMS inertial sensors such as angular random walk,

angular white noise and rate random walk, etc. Through analyzing the current various multi-sensor fusion

methods, we find that these approaches could be improved further in several ways for better accuracy

improvements. In the virtual gyroscope, Bayard established the covariance matrices of process noises and

measurement noises separately for the Kalman filtering.

The use of redundant inertial measurement units for navigation purposes is not new. From the very early

days of the inertial technology, the inertial navigation community was aware of the need and benefits of

redundant information. However, the focus of the research and development efforts was fault detection and

isolation (FDI). In the early days, the idea was to make use of the redundancy in order to support fault-safe

systems. A fault-tolerant system is able not only to detect a defective sensor, but also to isolate it. After

isolating a defective sensor, the system may keep working as a fault-tolerant or a fault-safe system

depending on the number of remaining sensors. By means of voting schemes [11], it can be shown that a

minimum of four sensors are needed to devise a fault-safe system and a minimum of five to devise a

fault-isolation one. Sensor configuration for optimal state estimation and optimal FDI was, as well, a topic

of research in the early works.

More recent results on the use of redundant inertial sensors for FDI can be found in [13] and [10]. The

former is mainly concerned with the use of skewed redundant configurations for unmanned air vehicles

while the latter focuses in guidance, navigation and control of underwater vehicles. The two references are

good examples of the wide range of applications for skewed redundant configurations that are currently

under research. The clustered sensor has different configurations. Two approaches to the configuration of a

redundant inertial measurement unit (IMU) system have been suggested in the past.

One is an orthogonal configuration shown in Figure 1(a) where the sensing axes of redundant inertial

sensors are orthogonal or parallel with respect to the body axes. In the orthogonal configuration, the inertial

measurement sensed by one sensor mounted on one axis is independent of other measurements sensed by

other sensors mounted on other axes. Therefore, the orthogonal IMU measurements are decoupled along the

orthogonal axes.

The other uses a non-orthogonal configuration relative to the body axes shown in Figure 1(b),

referred to as skewed redundant IMU (SRIMU) configurations. In a non-orthogonal configuration,

the measurement sensed by one sensor can be decomposed into three components along the

orthogonal axes, red dash arrows shown in Figure 1(b). Therefore, the measured states are coupled

with each other in the SRIMU measurements. This nature allows fewer sensors to be used in an

SRIMU configuration in order to achieve system performance equivalent to the orthogonal IMU

system.

Although the orthogonal IMU system is a conventional configuration, it is not the most efficient way to

exploit the benefits of redundant sensor systems in a fault-tolerant navigation system. The orthogonal

configuration has been used in traditional fault-tolerant navigation systems.

Figure 1. Sensor Installation Orientation

57 | P a g e Mahdi Jafari, Jafar Roshanian

SRIMU systems can most effectively make use of redundant measurements provided by multiple sensors

and have various configuration geometries dependent on the number of sensors. The typical configuration

geometries are based on regular polyhedrons in order to simplify the engineering implementation. Several

geometries commonly used in redundant sensor configurations are summarized in Table 1.

Table 1. Polyhedrons in Redundant Sensor Configurations

Polyhedron Number of Faces Min Number of Sensors

for Redundancy

Cube 6 4

Cone (Pyramid) 4

Dodecahedron 12 6

OPTIMAL CONFIGURATION OF INERTIAL REDUNDANT SENSOR SYSTEM

Redundancy can be provided by installing a few independent, identical copies of a system and comparing

their outputs. Inertial navigation systems are often used in threes, and a computer correlates their outputs. If

two of the three consistently differ from the third, the third is considered to have failed and its data is

ignored. Deciding between two might be possible if other data from separate sensors are available.

Redundant systems are expensive; the cost of providing backup systems must include the cost of carrying

their-extra weight. Rather than installing three copies of a system, redundancy can be provided at the

component level.

Particular system designs include one in which a fourth single-axis sensor is mounted with its sensitive

axis skewed to the three basic sensor axes. This sensor can then act as a check on the basic three and can

provide information if one should be determined to have failed.

CRITERIA FOR OPTIMAL SRIMU CONFIGURATIONS

In an SRIMU (Sensors Redundant IMU) configuration, the orientation of each sensor axis is defined by

its azimuth and elevation angles with respect to an orthogonal reference frame, such as the body frame.

Let each axis of the instrument frame be presented by a unit vector along the sensing direction of

sensor i, the unit vector can be defined in the orthogonal reference frame by:

( ) ( ) ( ) ( ) ( ) (1)

Where:

The bold symbols i, j and k are three unit vectors along the corresponding axes of the reference frame

( .

The superscript i denotes a sensor and its sensing axis.

and are the elevation and azimuth angles of the instrument axis i with respect to the reference

frame, as shown in Figure 1 (b).

If we suppose that an SRIMU system encloses n sensors, identified by 1, 2, 3… n, the measurement

equations of the SRIMU system can be formulated as follows:

[

]

[

]

[

]

[

]

(2)

Or in vector form

(3)


Where:

and are three measured physical input quantities, such as accelerations or angular rates in

the body frame.

is the measurement of sensor i .

is the measurement error, which is a Gaussian white noise with a zero-mean value and standard

deviation .

H is known as the sensor geometry matrix, or design matrix and describes the configuration of an

SRIMU system.

The symbol (.) Presents the operation of dot product of two vectors.

In essence, H matrix defines the geometrical arrangement of the sensors with respect to the orthogonal

body frame. The matrix formulation is same for accelerometer or gyro.

COVARIANCE MATRIX

Applying a weighted least-squares estimator, the estimate of the measured state vector is given by:

(4)

Where is the weight matrix and is referred as transformation matrix from the inertial

instrument frame to the body frame. Defining the estimate error vector then:

(5)

Therefore, the estimate error is the normal distribution and the covariance matrix of the estimate errors

according to the covariance transfer law is given by:

(6)

Where:

is the noise covariance matrix.

To simplify the analysis of performance of an SRIMU configuration, assume that all of sensor noises are

independent and that the standard deviation of the noise for each sensor measurement is identical

if the weight matrix is taken as the inverse of , then the covariance matrix of the estimate error

becomes

(7)

Or is represented by the following normalized form

(8)

The probability density function of the estimate error can be given by

√ √| |

(

)

(9)

Then, the locus of the point is determined by


(10)

This represents an error ellipsoid with a surface of constant likelihood. For any K, the volume of this

ellipsoid is given by

√ √|

| (11)

From the analysis above, the smaller the volume of this ellipsoid, the smaller the estimate errors, and the

performance of navigation systems with various SRIMU configurations can be determined by √| |.

Defining a performance index (PI) as:

√| | √ (12)

This equation can be used to determine the azimuth and elevation angles of each sensor to construct an

optimal SRIMU configuration.

THE CRITERION OF MINIMUM GDOP

If the square root of the trace of the normalized covariance matrix is selected as a criterion to optimize an

SRIMU configuration, known as the geometric dilution of precision (GDOP), then

√ (13)

We use the criterion of minimum GDOP to analyses the optimal installation angles for several cone

configurations. However, this criterion cannot be applied to non-cone SRIMU configurations.

THE OPTIMAL PERFORMANCE OF NON-CONE SRIMU CONFIGURATIONS

To evaluate the optimal performance of non-cone SRIMU configurations, the estimate error variances of

the measured states in the body frame can be formulated as follows.

∑

(14)

Based on the assumption that all measurement noises have an identical variance

a normalized

error variance is given by

∑

(15)

Where is the corresponding element of

accordingly.

The criterion for determining the optimal SRIMU installation angles is based on the allocation of the

uncertainty of SRIMU measurement to three orthogonal reference axes, usually the body axes. For example,

to precisely sense aircraft motion along a specific body-axis direction, the criterion for minimizing the

corresponding can be used to determine the SRIMU installation angles. To allocate the uncertainty of

SRIMU measurement equally to three body axes, then the following criteria

(16)


can be selected to determine the SRIMU installation angles.

FOUR-SENSORS CUBE CONFIGURATION

The figure 2 shows this configuration:

Figure 2. Four-Sensors Cube configuration

From the above figure we can find the following equations:

√

(17)

So the relation between the redundant sensors and the body frame can be written as:

[

]

[

√

√

]

[

] (18)

Therefore, the measurements matrix for the Four-Sensors Cube configuration is:

[

√

√

]

(19)

The optimal angle for this configuration is:

⇒ (20)

For the Four-Sensors Cube configuration the matrix relating the body axes to those of sensors axes is:


[

]

(21)

The matrix that relates the output sensors to the body axes when all sensors operating properly is given by

[

]

(22)

FOUR-SENSORS CONE WITH ONE AXIS CONE SENSOR CONFIGURATION

The figure 3 shows this configuration. From figure 3 we can find the following equations:

√

(23)

Figure 3. Four-Sensors Cone with one axis cone sensor configuration


[

]

[

√

√

]

[

] (24)

Therefore, the measurements matrix for the Four-Sensors Cone with one axis cone sensor configuration

is:


[

√

√

]

(25)


⇒ (26)

The matrix relating the body axes to those of sensors axes is:

[

]

(27)


[

]

(28)

FOUR-SENSORS CONE CONFIGURATION WITHOUT ONE AXIS CONE SENSOR

The most symmetric configuration of four sensors input axes is the normal to the faces of a regular

tetrahedron. The figure 4 shows this configuration.

Figure 4. Four-Sensors Cone without one axis cone sensor configuration



√

√

(29)


[

]

[ √

√

√

√

√

√

√

√

]

[

] (30)

Therefore, the measurements matrix for the Four-Sensors Cone without one axis cone sensor

configuration is:

[ √

√

√

√

√

√

√

√

]

(31)


⇒ (32)


[

]

(33)


[

]

(34)


SEX-SENSORS CONE CONFIGURATION

The figure 5 shows this configuration:

Figure 5. Sex-Sensors Cone configuration


(35)


[ ]

[

]

[

] (36)

Therefore, the measurements matrix for the Sex-Sensors Cone configuration is:

[

]

(37)


⇒ (38)


[

]

(39)



[

]

(40)

ERROR ANALYSIS

Based on the equation (12) and (13), for SRIMU configuration, the effective errors are given in Table 2.

For comparison of the errors for different sensors configurations, we suppose PI error of conventional

three-sensors is unity and normalize PI error of another SRIMU with it.

Table 2. The comparison of the errors for different sensors configurations

Number of sensors Errors

Total Operating GDOP PI

Three- sensors orthogonal 3 1.7321 1

Four-Sensors Cube 4 1.5811 0.7071

3 2.6458 1.7321

Four-Sensors Cone with one axis cone

sensor

4 1.5000 0.6495

3 2.1213 1.2990

Four-Sensors Cone without one axis cone

sensor

4 1.5000 0.6495

3 2.1213 1.2990

Five-Sensors Cone

5 1.3416 0.4648

4 1.6432 0.7348

3 3.0468 1.9767

Sex-Sensors Cone

6 1.2247 0.3536

5 1.4142 0.5000

4 1.7321 0.7906

3 2.0361 1.3143

CONCLUSION

In this paper the performance of redundant inertial measurement units and their various sensors

configurations was analyzed. This paper gives general derivation of the optimum matrix which can be

applied to the outputs of any combination of three or more sensors to obtain three orthogonal vector

components based on their geometric configuration and error characteristics. Comparing the third and fourth

columns of Table 2, if sensor failures occurred, optimal configurations may not obtain better measurement

accuracy in comparison with a non-optimal configuration. Therefore, the selection of an skewed redundant

IMU (SRIMU) configuration is a tradeoff between failure detection performance and measurement accuracy

under conditions of no sensor failures and sensor failures.

Figure 6. Errors comparing for different sensors configuration

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5

GDOP

GDOP-1

PI

PI-1


REFERENCES [1] M. Sturza, (1988), ”Navigation systems integrity monitoring using redundant measurements",

NAVIGATION, no. 35(4), pp. 69–87.

[2] M. Sturza, (1988), "Skewed axis inertial sensor geometry for optimal performance", AIAA/IEEE

Digital Avionics Systems Conference, pp. 128–135.

[3] Q. M. Lam, Jr. T. Wilson, R. Contillo, D. Buck, (2004), "Enhancing MEMS sensors accuracy via

random noise characterization and calibration", Proceedings of SPIE, 5403, pp. 427-438.

[4] M. Weis, D. Allan, (1992), "Smart Clock: A New Time", IEEE Transactions on Instrumentation

and Measurement , no. 41, pp. 915-918.

[5] D.S. Bayard, S.R. Ploen, (2003), "High accuracy inertial sensors from inexpensive components",

US Patent.US20030187623A1.

[6] Q. M. Lam, N. Stamatakos, C. Woodruff, S. Ashton, (2003), "Gyro modeling and estimation of its

random noise sources", AIAA Guidance, Navigation, and Control Conference and Exhibit, Austin, Texas,

no. 5562, pp. 1-11.

[7] Q. M. Lam, T. Hunt, P. Sanneman, S. Underwood, (2003), "Analysis and design of a fifteen state

stellar inertial attitude determination system", AIAA Guidance, Navigation, and Control Conference

andExhibit, Austin, Texas, no. 5483, pp. 11-14.

[8] D. Gebre-Egziabher, H. Gabriel, (2000), "A gyro-free quaternion-based attitude determination

system suitable for implementation using low cost sensors", IEEE Position Location and Navigation

Symposium, pp. 185-192.

[9] D. Gebre-Egziabher, R. C. ayward, J. D. Powell, (2004), "Design of multi-sensor attitude

determination systems", IEEE Transaction on Aerospace and Electronic System, no. 40, pp. 627-649.

[10] A. Lennartsson, D. Skoogh, (2003), "Sensor Rredundancy for Inertial Navigation", Technical

report, FOI (Swedish Defence Research Agency), SE.

[11] A. Pejsa, (1973), "Optimum skewed redundant inertial navigators", AIAA Journal, no. 12(7), pp.

899–902.

[12] P. Savage, (2000), "Strapdown Analytics", Strapdown Associates, Maple Plain, MN, Vol. 1, US.

[13] S. Sukkarieh, P. Gibbens, B. Grocholsky, K. Willis, and H. Durrant Whyte, (2000), "A low-cost,

redundant inertial measurement unit for unmanned air vehicle", The International Journal of Robotics

Research, no. 19(11), pp. 1089–1103.

Please cite this article as: M. Jafari, J. Roshanian, (2013), Inertial Navigation Accuracy Increasing Using Redundant Sensors, Science and Engineering, Vol.

1(1), 55-66



www.oricpub.com


Vol. 1 (1), 2013, 67-78



OPTIMAL FREE-DEFECT FUNCTION GENERATION

SYNTHESIS OF FOUR-BAR LINKAGE WITH JOINT

CLEARANCE USING PSO ALGORITHM

Arash Sardashti

1, H.M. Daniali

1, S.M.Varedi

1

1 Department of Mechanical Engineering, Babol University of Technology, Babol, P.O. Box 47148-71167,

Iran.

ABSTRACT This paper presents the design of planar four-bar linkages free of branch and circuit

defects, for the purpose of function generation; having clearances at one, two, three or

all of its joints. Joint clearance is treated as a mass-less virtual link which its direction is

known by the joint force. A Particle Swarm Optimization based algorithm is given here

to solve this highly nonlinear optimization problem with some constraints, namely; the

Grashof’s and free of the foregoing defects conditions. An example is included in

which the optimal problem is solved for all the cases. For all the designs, the generated

functions, the errors and the directions of the virtual links are plotted. Finally, we

compare the optimal designs with reality.

1. INTRODUCTION

In ideal case of kinematic synthesis of linkages, geometrical perfection

is usually assumed and they are treated without clearance at the joints. But

in practice, joint clearance is necessary for a linkage since it provides

allowance for the links to move relative to each other. In the presence of

joint clearances, contact forces generate impulsive effects and deteriorate

the performances of the linkages. Many researchers have investigated the

effects of joint clearance [1-4]. Some considered clearance only in one

joint [5-11], while the others considered the effects of clearance in more

joints of linkages [12-14]. On the other hand, most of the reported works

are related to analysis of linkages with joint clearances [1-14] and the

reported works on the synthesis of linkages are more limited [15-16].

Ting et al. [12] presented an approach to identify maximum errors due

to the joint clearance. They modeled joint clearance as a small virtual

link at the joints. Tsai and Lai [13] analyzed the transmission

performance of linkages with joint clearances. Pramanik and Naskar [16]

designed a four-bar linkage, for the purpose of path generation, having

clearances at two revolute joints connecting the driver and the driven

links to the coupler. Kolhaktar and Yajnik [17] studied the effects of

joint clearances on the output of function generation linkages. Huang and

Zhang [18] presented a method for robust tolerance design of function

generation mechanisms with joint clearances. The objective of the

present work is to design a planar four-bar linkage free of branch and

circuit defects for the purpose of function generation, having clearances

at one, two, three and all of the joints.


Keywords: Branch defect Circuit defect Joint clearance Optimal function generation- -synthesis Four-bar linkage PSO

Correspondence: Arash Sardashti

Department of Mechanical

Engineering, Babol

University of Technology,

Babol, P.O. Box

47148-71167, Iran.


Nomenclatures

ia Length of ith link

iK Position of the center of gravity of ith link

ir Length of ith VJCL joint

i Direction of ith VJCL joint

i Angle of ith link

iGx x-coordinate of the mass center of ith link

iGy y-coordinate of the mass center of ith link

im Mass of ith link

3GI Central Moment of inertia of the coupler

0BI Moment of inertia of the follower around the axis passing through B0

xijF The x-coordinate of the Joint force acting from ith link to jth link

yijF The y-coordinate of the Joint force acting from ith link to jth link

inT Input torque

If the sign of transmission angle changes in target points, branch defect will happen [19], i.e. the solutions

related to the different target points are from different assembly modes and thus are not feasible.

Furthermore, if the mechanism path through all the target points without reassembling any of its joints, then

its motion will be in a circuit [20]. When a potential solution linkage cannot move between all target points

without changing the assembly, the circuit defect arises. Although synthesis of linkages with joint clearance

is not new, but designing them free of these defects have not reported in the literature.

Function generation synthesis, free of the foregoing defects and in the presence of clearance is highly

nonlinear and should be solved numerically. Recently Evolutionary Algorithms are becoming increasingly

popular for solving nonlinear problems in various fields [21-22]. Here we present an algorithm based on

Particle Swarm Optimization (PSO) to solve this highly nonlinear optimization problem with some

constraints, namely; the Grashof’s conditions and free from the foregoing defects. The joints clearances were

modeled by some virtual links, the directions of which are determined by the Newton second law. The

problem is solved for the clearances in one, two, three, all the joints and without clearance, as well.

Comparison is done between all the foregoing designs and the linkage in its ideal cases, namely without joint

clearance.

This paper is organized as follows; Section 2 describes the equivalent model of the virtual joint clearance.

In Section 3, analysis of four-bar linkage in the presence of joint clearance is presented. Section 4 devoted to

the synthesis of four-bar function generation. An algorithm based on PSO is outlined in section 5. A case

study is presented in section 6 and finally, conclusion is outlined in Section 7.

2. THE MODELING OF THE CLEARANCES In this study, a planar four-bar linkage with joint clearances is considered. A planar revolute joint includes

a pin attached to the ith link with radius ri that turns in a hole attached to the (i+1)th link with radius ri+1, as

shown in Fig. 1. Under this condition, the connecting position of two coupled links depends on the joint force.

It is convenient to assume that the center points of two coupled links are connected by a virtual joint clearance

link (VJCL), r in the direction of the joint force [15]. On the other hand, each joint clearance gives an extra

degree of freedom to the linkage which is controlled by the direction of the joint force. Moreover, r is given as

[5,12]:

1 -i ir r r

(1)

69 | P a g e A. Sardashti, H.M. Daniali, S.M.Varedi

( 1)thi link

thi linkr

1ir

ir

( )a ( )b

Force

Direction

Fig. 1. (a) Equivalent model of VJCL. (b) joint clearance.

3. ANALYSIS

In this section we include the kinetostatic analysis of planar four-bar linkage. It is assumed that the input

link rotates with a constant angular velocity 2( ) . Thus, the free-body diagrams of the links under the effect

of inertia forces and moments are depicted in Fig. 2. Therefore, One can write the following equations for

the input link:

212 32 2 Gx xF F m x

(2)

212 32 2 2y y GF F m y m g

(3)

32 2 2 32 2 2 2 2 2 2sin( ) cos( ) cos( ) 0x y inF a F a T m gK a (4)

Similarly, one can write the followings for the coupler and the output link:

323 43 3 Gx xF F m x

(5)

323 43 3 3y y GF F m y m g

(6)

323 3 3 3 23 3 3 3 43 3 3 3 43 3 3 3 3sin( ) cos( ) (1 )sin( ) (1 )cos( )x y x y GF k a F k a F k a F k a I

(7)

434 14 4 Gx xF F m x

(8)

34 14 4 44y y GF F m y m g

(9)

034 4 4 34 4 4 4 4 4 4 4sin( ) cos( ) (1 ) cos( )x y BF a F a m g k a I

(10)

Where ( 1) ( 1)i i x i ixF F , ( 1) ( 1)i i y i iyF F

Eqs. (5) – (10) can be solved for 43xF , 43yF as:

1 2

43

3 4

1det( )x

B BF

B B

(11)

5 1

43

6 3

1det( )y

B BF

B B

(12)

In which:

3 3 3 3

4 4 4 4

sin( ) cos( )det( )

sin( ) cos( )

a a

a a

(13)

3

3

1 3 3 3 3 3 3

3 3 3 3 3

sin( )

( ) cos( )

GG

G

B I m x k a

m y m g k a

2 3 3cos( )B a

(14)

3 4 4 4 4 4(1 ) cos( )BB I m g k a

4 4 4cos( )B a

5 3 3sin( )B a

6 4 4sin( )B a


Then, one can solve Eqs. (5) and (6) for 23xF and 23yF . Similarly, substituting the values of 23xF

and

23yF

into Eqs. (2) and (3) leads to 12xF , 12yF . Finally, substituting the values of 34xF

and

34yF into Eqs. (8)

and (9) yields to 14xF , 14yF .

2G

4G

3G

21xF

21yF

12yF

12xF2m g

2 2m y

22m x

32xF

32yF

23yF

23xF

43xF

43yF34yF

34xF4 4GI

4 4m g

4 4m y

3 3m y

3m g

3 3m x

3 3GI

14xF

14yF

41yF

4

3

2

inT

44m x

41xF

Fig. 2. The free body diagrams of the links of four-bar linkage.

It is noteworthy that the direction of VJCL is the same as the directions of the foregoing forces. Therefore,

the direction of VJCL at joint A is given as:

2 23 23arctan( / )y xF F (15)

Similarly, the directions of VJCLs at joints A0, B and B0 are given as:

1 12 12arctan( / )y xF F (16)

3 43 43arctan( / )y xF F (17)

4 14 14arctan( / )y xF F

(18)

3.1 Four-bar linkage with clearances in four joints

In this subsection we analyze planar four-bar linkage in reality, i.e. with four joints clearance as depicted

in Fig. 3, while its kinematic model is depicted in Fig. 4. Without losing of generality, a reference frame is

attached to point A0. Therefore, the mass centers of the links are given as:

y

x2

0B0A

33r

2G

4G

3G

A

'A22r

B

B

41

4r1r0B 4

33a

4a

2a

1a

Fig. 3. Four-bar function generation linkage with four joints clearance.


2

0B0A

3

3r

A

'A22r

B

B

41

4r1r0B0A 4

33a

4a

2a

1a

Fig. 4. A kinematic model of the four-bar linkage with four joints clearance.

2

2

0 1 2

1 2 2

0 1 2

cos( ) cos( )

sin( ) sin( )

G

G

x xr K a

yy

(19)

3

3

0 1 2 2 3

1 2 2 3 3

0 1 2 2 3

cos( ) cos( ) cos( ) cos( )

sin( ) sin( ) sin( ) sin( )

G

G

x xr a r K a

yy

(20)

4

4

0 1 4 4

1 4 4 4

0 1 4 4

cos( ) cos( ) cos( )

sin( ) sin( ) sin( )

G

G

x xa r K a

yy

(21)

The loop closure equation can be written as:

0 0 0 0 0 0 0 0A A A A AA A B A B B B B B B B (22)

The same equation can be written in component- wise as:

4 4 1 1 2 2 2 2 3 3

4 4 1 1 2 2 2 2 3 3

3 31 1 4 4

3 31 1 4 4

cos( ) cos( ) cos( ) cos( ) cos( )

sin( ) sin( ) sin( ) sin( ) sin( )

cos( )cos( ) cos( )

sin( )sin( ) sin( )

a r a r a

a r a r a

ra r

ra r

(23)

The above equation can be solved for3 , namely;

1 2 2 2 2 0.5 2 2

3 2 3 1 1 2 3 2 3

2 2 2 0.5 2

1 1 2 3

cos ((( ) ( (( ) ( ) ( ) ) ) ) / (( )

( (( ) ( ) ( ) ) ) ))

A A A A A A A A

A A A A

(24)

Where A1, A2 and A3 are given as:

1 3 1 1 2 2 2 2 3 3 1 1 4 42 ( sin( ) sin( ) sin( ) sin( ) sin( ) sin( ))A a r a r r a r (25)

2 3 1 1 2 2 2 2 3 3 1 1 4 42 ( cos( ) cos( ) cos( ) cos( ) cos( ) cos( ))A a r a r r a r (26) 2 2 2 2 2 2 2 2

3 1 1 2 2 3 3 4 4 1 2 2 1 1 2 2 1

1 3 3 1 1 1 1 1 1 4 4 1 2 2 2 2

3 2 2 3 1 2 2 1 4 2 2 4 2 4 4 2

3 1

2 cos( ) 2 cos( )

2 cos( ) 2 cos( ) 2 cos( ) 2 cos( )

2 cos( ) 2 cos( ) 2 cos( ) 2 cos( )

2

A a r a r a r a r r a r r

r r r a r r r a

r a a a r a r r

r a

1 3 3 4 4 3 4 1 1 4cos( ) 2 cos( ) 2 cos( )r r r a

(27)


Substituting the value of 3

from Eq. (24) into Eq. (23), upon simplifications, yields to:

1

4 1 1 2 2 2 2 3 3 3 3 1 1

4 4 4

cos (( cos( ) cos( ) cos( ) cos( ) cos( ) cos( )

cos( )) / )

r a r a r a

r a

(28)

The angular velocities of the coupler and the follower can be written as: 4

2

12

, for 3,4i ii j

j j

i

(29)

Moreover, the linear velocities of the mass centers of the input, the coupler and the follower are given as:

42

2

1

2

, for 2,3,4

ii

i

i i

i

GG

G j

j

jG GG

j

xx

xi

y yy

(30)

Finally, time derivatives of Eqs. (29) and (30) yields to: 22 2 2 24 4 4 4 4

2

2 22 21 1 1 1 12 2

2 ,

3,4,

i i i i ii j j j j k

j j j j kj j j j k

for i k j

(31)

2 2

22 24 4 4222

2 2 2 21 1 1

2 2

2 2

4 4

1 1

2

i i ii

i

i i i i

i

G G GG

G j j j

j j j

j j jG G G GG

j j j

j k

j k

x x xx

x

y y x yy

2

2for 2,3,4, ,

i

i

G

j k

G

j k

x

i k jx

(32)

3.2. Special cases of Four-bar linkages

Substituting 1 0r , 2 0r , 3 0r , 4 0r , 1 0 , 2 0 , 3 0 and 4 0 into Eqs. (19)-(32),

leads to the relations for four-bar linkages without joint clearance. Moreover, substituting 1 0r , 3 0r ,

4 0r , 1 0 , 3 0 and 4 0 into Eqs. (19)-(32), leads to the relations for four-bar linkage with

clearance at joint A. Furthermore, substituting 1 0r , 4 0r , 1 0 , and 4 0 into Eqs. (19)-(32),

leads to the relations for four-bar linkage with clearances at joints A and B. Finally, substituting 1 0r

and 1 0 into Eqs. (19)-(32), leads to the relations for four-bar linkage with clearances at joints A, B

and B0.

4. SYNTHESIS FOUR-BAR LINKAGES FOR FUNCTION GENERATION PROBLEM

Here we design planar four-bar linkages for function generation problem in five different cases, namely;

without joint clearance, with clearance at joint A , with clearances at joints A and B, with clearances at

joints A, B and B0 and with joint clearances in all the joints.


Design parameters: There are three design parameters for function generation problem, namely; 2a , 3a ,

4a , all are summarized in a vector form as 2 3 4, , .T

a a ax It is noteworthy that 1a acts as the scale factor

here.

The Design Objective: The objective function in this study has two parts, namely; the position error and

the constraints which are applied here by some penalty functions. In the optimization problem here, the

former is defined as the mean-square distances between the generated and the desired functions, while the

latter are defined as some inequality constraints. Here, we have three types of constraints, namely; the

Grashof’s conditions, branch defects and circuit defects.

The Grashof’s conditions of a crank-rocker are given as [23]:

1 2 3 4max , , ,l a a a a (33)

1 2 3 4min , , ,s a a a a (34)

1

2 2

1 1 2

( ) (( ) ( ))

( )

( ) : ( ) ( ( ) 0 & & ( ) 0)

g X s l p q

g X s a

a g X g X g X

(35)

The constraints of branch and circuit defects are given, respectively as [23]:

2 4 3( ) : ( ) 0, for 1,2,...,i ib g x i N (36)

3 2 3( ) : ( ) 0, for 1,2,...,i ic g x i N (37)

Therefore, an objective function for function generation linkage with the foregoing constraints can be

defined as:

Minimize

2

4 4 1 1 2 2 3 3

1

( ) (1/ ) ( [( ( )) ( ) ( ) ( ))n

i i

d

i

F X N X M g X M g X M g X

(38)

Where 4

i

d and

4

i are the desired precision points and the generated points, respectively. Moreover,

1M , 2M and 3M

are constants that penalize the objective function when the constraints fail.

5. PSO ALGORITHM

In this section, we illustrate a PSO based algorithm for the synthesis of planar four-bar linkages for the

purpose of function generation with some constraints as explained in section 4. The idea of PSO is based on

the social behavior and dynamic movement of bees, ant, termites, fish and birds. The path of a particle in

swarm is a function of its own knowledge and information and also the knowledge and information of

swarm which might be modified in each iteration. The best position of jth particle is called “Pbest,j” and the

best position of swarm in each iteration is being called “Gbest”.

The position and velocity of jth particle in ith iteration are calculated, as follows:

( ) ( 1) ( ), for 1,2,...,j j jX i X i V i j N (39)

1 1 , 2 2( ) ( 1) ( 1) ( 1) , for 1,2,...,j j best j j best jV i V i c u P X i c u G X i j N (40)

The constants of c1 and c2 are called “social parameters” and their values are usually scantling 2; u1 and

u2 are random number between 0 and 1 and ( )i is called “weighting factor” that change linearly in the

iteration, i.e.

max max min max( ) (( ) / )i i i (41)


The values of max and min are usually 0.9 and 0.4, respectively; i is the number of iteration number and

imax is the maximum of iteration number.

In the algorithm presented here, the Grashof’s conditions and the probable defects of the feasible design

such as branch and circuit defects is considered, as well. However, finding probability of initial random

population which satisfies the foregoing constraints is very slim. Moreover, the complexity of function

generation synthesis problem increases with the number of the desired target points. These might lead to a

time consuming solutions. To alleviate this drawback, a subroutine is included here to find new boundaries

for each independent variable instead of the initial ones. The goal is obtained by ascending probability of

constraints satisfaction and pre optimization of the main objective function. Therefore, the optimization

problem tends to converge in fewer iterations. The algorithm is depicted in Fig. 5.

6. CASE STUDY

As a case study, we design Grashof planar four-bar linkage, free of branch and circuit defects for function

generation problem with 20 ordered precision points as:

o o o o o o o o

o o o o o o o o

o o

[( )] = [(35.0192 ,35.2254 ), (44.7365 ,36.8756 ), (60.8367 ,41.6082 ), (74.5819 ,46.6502 ),

(89.5533 ,52.6548 ), (101.2130 ,57.5192 ), (113.8811 ,62.8936 ), (124.6470 ,67.4772 ),

(137.8365 ,73.0693 ), (1

i i

2 4dθ ,θ

o o o o o o

o o o o o o o o

o o o o

49.9946 ,78.1686 ), (168.7533 ,85.8520 ), (183.1173 ,91.5357 ),

(201.3546 ,98.4170 ), (228.6388 ,107.7734 ), (249.2997 ,113.7894 ), (275.7245 ,119.2612 ),

(297.8349 ,120.3154 ), (317.1207 ,115.7547 ),(336.532 o o o o5 ,99.7405 ), (353.6410 ,69.8779 )]

It is noteworthy that the algorithm presented here, at the first step will check the Grashof’s condition and

excludes those solutions with branch and circuit defects from the feasible ones. Therefore, the problem leads

to minimizing Eq. (38) with the following limits for the design variables:

[400,2000]2 3 4a ,a ,a

We solve the foregoing optimal function generation problem without clearance at joints (design 1); in the

presence of clearances at joint A (design 2), in the presence of clearances at joints A and B (design 3), in the

presence of clearances at joints A, B and B0 (design 4) and finally in the presence of clearances at joints A, B, B0

and A0 (design 5).

The synthesized geometric parameters, the number of iteration, the corresponding values of the objective

function and the error are given in Table 1. Moreover, the desired target points and the generated points for

all the designs are shown in Fig. 6; while the errors of the designs are illustrated in Fig. 7.

Furthermore, the directions of VJCLs of the joints A0, A, B and B0 are shown in Figs. 8-11, respectively.

Finally, Fig. 12 shows a typical plot of the convergence speeds of the algorithm for the designs which is very

fast. Now, we evaluate the designs in reality, i.e. in the presence of joint clearances at all joints. The desired

target points and the generated points for the designs are shown in Fig. 13; while the errors of the designs are

illustrated in Fig. 14. These figures clearly reveal that designing four-bar linkages for function generation

problem in the presence of joint clearances lead to more accurate results.

Table 1. The optimal designs.

Design 5 Design 4 Design 3 Design 2 Design 1 Design

variables

648.0476 646.8454 645.9018 644.6358 643.3739 2 ( )a mm

6517.4230 6593.5524 6553.5330 6639.6374 6674.8889 3 ( )a mm

6318.842 6395.6189 6354.833 6441.3258 6476.7397 4 ( )a mm

98 94 86 80 74 No. of

iterations

0.0182 0.0154 0.0141 0.0109 0.0098 Error (deg)


Yes Yes Yes

1 0g No 2 0g

No No 3 0g

1 1g 2 1g

3 1g

No

Yes

Fig. 5. Flowchart of the PSO algorithm for the synthesis of planar four-bar linkages.

Start

Start to initialize population

Refinement the initial boundaries with respect to the Grashof’s condition

Refinement the initial boundaries with respect to the branch defect constraint

Refinement the initial boundaries with respect to the circuit defect constraint

Initialize Objective Function value from Eq. (38)

Is constraint

(a)

satisfied?

Is constraint

(b)

satisfied?

Is constraint

(c)

satisfied?

Evaluate Objective function from Eq. (38)

Choose the best design vector (Gbest)

Is

convergen

ce criteria

satisfied?

Output results

Stop


Finally, 4 3

i i and 2 3

i i are plotted verses the target points for all the designs in Figs. 15 and 16,

respectively. These continuous curves clearly show that the designs are free from branch and circuit defects,

respectively.

Fig. 6. The angles of input and output links: Desired Target

points (o); Generated points, Design 1 (-*), Generated points,

Design 2 (-), Generated points, Design 3 (--), Generated points,

Design 4 (-.), Generated points, Design 5 (…).

Fig. 7. The errors of the angle of output link: Design 1(-*),

Design 2 (-), Design 3 (--), Design 4 (-.), Design 5 (…).

Fig. 8. The Direction of VJCL in the joint A0: Design 5 (…).

Fig. 9. The Direction of VJCL in the joint A: Design 2 (-),

Design 3 (--), Design 4 (-.), Design 5 (…).

Fig. 10. The Direction of VJCL in the joint B: Design 3, (--),

Design 4 (-.), Design 5 (…).

Fig. 11. The Direction of VJCL in the joint B0: Design 4 (-.),

Design 5 (…).


Fig. 12. The convergence of PSO algorithm for design 1.

Fig. 13. The angles of input and output links in reality and in

the presence of the joint presence of clearance: Desired Target

points (o); Generated points Design 1 (-*), Generated points

Design 2 (-), Generated points Design 3 (--), Generated points

Design 4 (-.), Generated points Design 5 (…).

Fig. 14. The errors of the angle of output link in reality and in

the presence of the joint clearances: Design 1 (-*), Design 2 (-),

Design 3 (--), Design 4 (-.), Design 5 (…).

Fig. 15. The satisfaction of branch constraint: Design 1 (-*),

Design 2 (-), Design 3 (--), Design 4 (-.), Design 5 (…).

Fig. 16. The satisfaction of circuit constraint: Design 1

(-*), Design 2 (-), Design 3 (--), Design 4 (-.), Design 5 (…).

7. CONCLUSIONS

Here the optimal function generation of planar four-bar linkages free of branch and circuit defects; having

clearances at one, two, three or all of the joints have been designed. Joint clearance has been treated as a

mass-less virtual link. A PSO based algorithm has been given here to solve this highly nonlinear constrained

optimization problem. Optimal designs of four-bar linkage having clearances at one, two, three, all of the

joints and without clearance have been included. We compared the functions generated in these designs with

reality. The comparison results clearly revealed that designing four-bar linkages for function generation

problem in the presence of joint clearances leads to more accurate results.


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237-244.

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linkages with clearances. Mech. Mach. Theory, 26(7), pp. 669-676.

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with slider clearance. J. Sound Vib., 177(3), pp. 307-324.

[8] Seneviratne, L. D., & Earles, S. W. E. (1992). Chaotic behavior exhibited during contact loss in a

clearance joint of a four-bar mechanism. Mech. Mach. Theory, 27(3), pp. 307-321.

[9] Li, Z., & Li, L. & Bai, S. (1992). A new method of predicting the occurrence of contact loss between

pairing elements in planar linkages with clearances. Mech. Mach. Theory, 27(3), pp. 295-301.

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linkage. Mech. Mach. Theory, 14(2), pp. 99-110.

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clearance in revolute joints using a new hybrid contact force model. I. J. mech. Sci., 54(2), pp. 190-205.

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[13] Tsai, M. J., & Lai, T. H. (2004). kinematic sensitivity analysis of linkage with joint clearance based on

transmission quality. , Mech. Mach. Theory, 39, pp. 1189-1206.

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National Conference on Machines and Mechanisms, pp. 7-14.

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Please cite this article as: A. Sardashti, H.M. Daniali, S.M.Varedi, (2013), Optimal Free-Defect Function Generation Synthesis Of Four-Bar Linkage With

Joint Clearance Using Pso Algorithm, Science and Engineering, Vol. 1(1), 67-78



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Vol. 1 (1), 2013, 79-83



IMPROVEMENT OF THE INJECTION EFFICIENCY IN

ORGANIC LIGHT EMITTING DEVICES BY ADDITIONAL

SPRAY DEPOSITED HOLE TRANSPORTING LAYER M.P. Aleksandrova

1, G.H. Dobrikov

1, G. D. Kolev

1, I. N. Cholakova

1

1 Technical University of Sofia, Department of Microelectronics, Kliment Ohridski blvd, 8, 1000 Sofia, Bulgaria

Abstract Novel approach for deposition of thin films from low molecular weight compounds by

pulverization is presented. The method was supplied for preparation of flexible organic

light emitting device with tris(8-quinolinolato)-aluminum (Alq3) emissive layer.

Additional film of N-N′-diphenyl-N-N′-bis (1-naphthyl)-1,1′-biphenyl-4,4′-diamine

(NPB) was also spray deposited as a hole transporting layer (HTL) to increase the

injection efficiency of the organic electroluminescent structure. Suitable substrate

temperature was set to avoid dissolving and damage of both layers, caused by solvent

penetration from NPB in Alq3. After optimization of the deposition conditions and

because of the energy level alignment with introduction of NPB, it was measured

reduction of the turn-on voltage with approximately 2 V. Current-voltage characteristics

show 6 mA higher current at given voltage for the structure with HTL and the

brightness-voltage characteristics show that the emission intensity is 300 cd/m2 higher.

In this way the injection efficiency was improved 3 times.

1. INTRODUCTION

Organic light-emitting devices (OLEDs) have been attracted attention

as possible application in the displays due to their easy deposition in form

of thin films with simple and cheap equipment, leading to low cost

manufacturing [1]. In comparison with the liquid crystal displays (LCD)

which are currently in trend, OLEDs generate own light emission,

allowing both wider viewing angles and lower consumed energy saved

from the lack of back lightening.

Efficiency improvement is still open problem for OLED technology in

comparison with the other portable displays (for example liquid crystal

LCD). One of the most often applied approaches is insertion of buffer

injecting layers for energy level alignment between the electrodes and the

emissive layer. In this way the interface energy barrier is reduced and the

charge balance is bettered. Because more of the emissive materials are

also electron transporting layers (ETL), then hole transporting layers

(HTL) are crucial points. In the literature are reported many results

concerned HTL from different materials – inorganic, organic low

molecular weight substances, conjugated polymers, organic-inorganic

blends, different nano-particles and self assembling particles, etc. [2-6].

The most spread combination is NPB/Alq3 and PEDOT/Alq3 [7,8].

Typical values of the injection efficiency in these cases are 4-6 cd/A.

However, in the above cited papers emissive layers are usually vacuum

thermal evaporated, and the HTLs are spin coated or thermal evaporated

too.


Keywords: Organic light emitting devices Hole transporting layer Injection efficiency Spray deposition Organic thin films

Correspondence: M.P. Aleksandrova Technical University of

Sofia, Department of

Microelectronics, Kliment

Ohridski blvd, 8, 1000

Sofia, Bulgaria


In the flexible OLEDs high temperature processes like thermal evaporation are more recommended,

because of the weaker bond in the material after heating during evaporation. As well, it has been found that the

temperatures higher than 100oC (most often revealed during thermal evaporation) can cause anisotropic

shrinkage in the PET substrates [9]. This leads to mechanical stress induced in the soft organic layers, which in

combination together with the multiple cycles of bending cause degradation of the device. In addition fast

luminescent decay is supposed to occurs due to the growth of crystallites on the electrode surfaces from the

annealing and/or non-uniformity of the electrical field [10]. The above mentioned results imply alternative

technology at lower deposition temperature to be developed and smoother organic films to be produced. Spray

deposition can be appropriate tool to achieve the necessary effects and can be performed even at room

temperature for precise nanofilms deposition with well controllable thickness and uniformity. By setting of

suitable deposition conditions like aerosol size and pressure, substrate temperature, distance between the

nozzle and the substrate, it is possible to produce high quality defect free layers at temperatures low enough to

avoid flexible substrates deformation. Until now several reports exist in the literature, concerning spray

deposition of polymers for application in solar cells and piezoelectrical MEMS sensors [11, 12]. By the

authors’ knowledge there is no investigation of multilayer, spray deposited low molecular weight organic

compounds.

In this paper we present results from preparation and testing of bilayer ITO/NPB/Alq3/Al organic light

emitting devices by using of spray coatings on polyethylenetherephtalate (PET) flexible substrates. We made

comparison with OLED structures, building by thermal evaporated organic layers.

2. MATERIALS AND METHODS

On PET substrate, indium-tin oxide (ITO) film was deposited by low-temperature RF sputtering at

oxygen partial pressure 2.10-4

Torr, total gas pressure 2.5.10-2

Torr, sputtering power varies between 75 W

and 105 W with rate 0.5 W/s during deposition of the initial ITO monolayer. Sheet resistance reaches 19.2

Ω/sq after 10 minutes of ITO treatment with UV light (UV 365 nm, source power 250 W). The basic

structure of the OLED devices is double layer type, consisting of

N-N′-diphenyl-N-N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine NPB as a HTL and

tris(8-hydroxyquinolinato)aluminium Alq3 as light emitting layer, commercially available (Sigma Aldrich)

and used without further purification. They were situated between transparent ITO anode and aluminum

cathode. The structure is presented schematically on Fig. 1.

Fig. 1. Prepared flexible OLED structure

with two organic layers.

Fig. 2. Spray coater for organic solutions pulverization.

The organic dusts were dissolved in solvent mixture from chloroform and methylethylketon heated to

40oC. Solution was stirred for several hours until fully dissolving. For spraying, atomizer with nozzle having

regulating orifice up to 200 μm was used. The established optimal deposition conditions regarding layers

uniformity were as follows: substrate temperature 70оС; distance nozzle to substrate 15 cm; atomizing

pressure 4 bars; solution concentration 5 mg/ml for Alq3 and 7 mg/ml for NPB. Fig. 2 shows the principle of

pulverization of the solved low-molecular weight compounds. Detailed information about the specifity of

spraying of organic solutions can be found in [13]. Alternative structure with single layer of Alq3 was

prepared for comparison of the current-voltage (I-V) and brightness voltage (B-V) characteristics. The

thickness of the emissive layer in both types of OLEDs structures was the same – 140 nm and the thickness

of the HTL was 40 nm, measured by profilometer. The current was measured by a Keithley 6485

PET

ITO

NPB

Alq3AlAg

PET

ITO

NPB

Alq3AlAg

81 | P a g e M.P. Aleksandrova, G.H. Dobrikov, G. D. Kolev, I. N. Cholakova

picoammeter and the brightness was measured by luminancemeter with collor correction factor Konica

Minolta LS-110.

3. RESULTS

Fig. 3 shows the current-voltage characteristics of the both structures – single layer and bilayer OLED. As

can be seen after introduction of the HTL the conductivity tend to increases with 6 mA and the turn-on voltage

is 2 V lower (for stable turn on voltage can be taken the value of 4V for single layer device). This is evidence

that the interface between both organic layers is not destroyed during spray deposition of the Alq3 solution

onto the NPB underlying film. Such behavior can demonstrate only structures that consist of layers with

abrupt boundaries with each other. According to reported values [14] the energy diagram clearly shows that

the anode injection barrier ITO/Alq3 can be divided on two smaller hole energy barriers – 0.4 eV at the

ITO/NPB interface and 0.6 eV at the NPB/Alq3 interface, which can be overcame at lower power supply (Fig.

4). This is the reason for the earlier turning on of the device. Presented results are achieved after series of

experiments at different substrate temperatures of spraying, varying around the temperature of evaporation of

the used solvent. Also structures with different thicknesses of NPB between 30 and 70 nm were produced (not

shown) to establish the optimal 40 nm for the hole transport. If the spraying conditions were not set

appropriately, the layers will penetrate in each other and the I-V curves would be even worsened. We believe

that the current in the part of the I-V characteristic with deviations from the main points in not leakage,

because they are in the range of several hundreds of microamperes, not several miliamperes and could not

excite molecules for generation of stable and measurable electroluminescence. Because of this, the deviation

of I-V curve around 3.5V for the single layer device may be ascribed to implemented impurities, but this is

object of further more extensive investigations.

The bilayer device shows not only higher current density, but higher luminescent output too. The

corresponding B–V curves present a similar behavior (Fig. 5) – the stable emission at same operation voltage

is 300 cd/m2 higher when the charge carriers are balanced with HTL. If the physical contact between the layers

in the stack is irregular, then even the appropriate energy level alignment between HTL and emissive layer

would not assist the charge carriers to overcome the electrical resistance at the organic/organic interface,

caused by the lower mutual contact area. If the layers were partially blended, the contact resistance in this

region would destroy the charge balance, the voltage drop and emission losses would increase. As well, if

defects in the hole organic layer exist, hole traps would be formed and the charge carriers could not reach the

recombination zone [15]. Based on these observations and because of the lack of losses in the light emission,

we conclude that the spray technique is the reason for additional improvement of the characteristics, not only

due to the favorable energy level positions of NPB and Alq3, but due to uniform physical contact between the

layers.

Fig. 3. I-V characteristics of single layer and bilayer

OLED structures.

Fig. 4. Energy levels alignment in the

proposed bilayer OLED structure.


Fig. 5. B-V characteristics of single layer

and bilayer OLED structures.

Fig. 6. Current efficiency of single layer and

bilayer OLED structures.

The current efficiency is one the most important parameters for the OLED’s operation. It was found that the

current efficiency (Fig. 6) increases due to the charge balance caused by the efficient hole injection in the

sample. The best achieved stable value is 6 cd/A for 5.5V versus 2.3 cd/A for the same voltage for the single

layer OLED. The values are close to the reported in the literature [16], where the NPB and Alq3 layers are

consequently thermally evaporated. In previous experiments [13] it was found that spray coatings are

smoother than spin coated or vacuum deposited. This give us reason to believe that not only favorable energy

level alignment, but the lower contact resistance at the interfaces with the smoother sprayed layers may cause

such improvement of the efficiency.

Fig. 7. Photo of the prepared sample in light emissive mode.

4. CONCLUSION

In this study solved buffer layer was used to find a stable anode hole injecting system for low molecular

weight electroluminescent devices. OLED shows an enhanced electroluminescent performance after inserting

spray deposited NPB film as a hole transporting layer. The shape and the tendency in the I-V and B-V curves

after insertion of HTL are proof for the quality of the spray deposited stack of organic layers and lack of the

change in the composition near the interface NPB/Alq3. Continuity and smoothness of the NPB layer leads to

improvement of the flexible OLED’s electro-optical efficiency.

ACKNOWLEDGEMENT The work is financial supported by grant DMU 03/5 – 2011 of Fund “Scientific Research”, Bulgarian

Ministry of Education, Youth and Science.

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[4] Aleksandrova, M., Rassovska, M. & Dobrikov, G. (2011). Efficiency improvement of polymer

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[13] Aleksandrova, M. (2012). Improvement of the Electrical Characteristics of Polymer Electroluminescent

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Please cite this article as: M.P. Aleksandrova, G.H. Dobrikov, G. D. Kolev, I. N. Cholakova, (2013), Improvement Of The Injection Efficiency In Organic

Light Emitting Devices By Additional Spray Deposited Hole Transporting Layer, Science and Engineering, Vol. 1(1), 79-83

2013 (Vol. 1, No: 2)



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Vol. 1 (2), 2013, 85-93



EFFECT OF ARTIFICIAL ROUGHNESS ON HEAT TRANSFER

IN A SOLAR AIR HEATER

F. Chabane

1,2, N. Moummi

1,2, S. Benramache

3, D. Bensahal

1, O. Belahssen

3

1 Mechanics Department, Faculty of Sciences &Technology, University of Biskra, Algeria.

2 Mechanical Laboratory, Faculty of Sciences &Technology, University of Biskra, Algeria

3 Materials Science Department, Faculty of Science, University of Biskra, Algeria.

Abstract

The heat transfer of a solar air heater duct can be increased by providing artificial

roughness on the heated wall (i.e. the absorber plate).The thermal performance of a single

pass solar air heater with five fins attached was investigated experimentally.

Longitudinal fins were used inferior the absorber plate to increase the heat exchange and

render the flow fluid in the channel uniform. The effect of mass flow rate of air on the

outlet temperature, the heat transfer in the thickness of the solar collector was studied.

The effect of parameters on the heat transfer is compared with the result of smooth duct

under similar flow conditions. Experiments were performed for air mass flow rate m =

0.016 kg/s. Moreover, the maximum efficiency values obtained for the 0.016 with and

without using fins were 51.50 % and 43.94% respectively.

1. INTRODUCTION

Comparison of results reveals that the thermal efficiency of a single

pass solar air collector a function of mass flow rate it is higher with an

increasing the flow rate. Increasing the absorber area or fluid flow

heat-transfer area will increase the heat transfer to the flowing air, on the

other hand, will increase the pressure drop in the collector, thereby

increasing the required power consumption to pump the air flow crossing

the collector [1, 2]. On the other hand, several configurations of absorber

plates have been designed to improve the heat transfer coefficient.

Artificial roughness obstacles and baffles in various shapes and

arrangements were employed to increase the area of the absorber plate. As

a result, the heat transfer coefficient between the absorber plate and the air

pass is improved [3]. Reporting an on experimental investigation of the

thermal performance of a single and double pass solar air heater with fins

attached and a steel wire mesh as absorber plate [4]. The bed heights were

7 cm and 3 cm for the lower and upper channels respectively. The result of

a single or double solar air heater, when compared with conventional solar

air heater shows much more substantial enhancement in the thermal

efficiency. It studied numerical of the performance and entropy generation

of the double-pass flat plate solar air heater with longitudinal fins [5]. The

predictions are done at air mass flow rate ranging between 0.02 and 0.1

kg/s. Reporting used the fins serve as heat transfer augmentation features

in solar air heaters, however, they increase pressure drop in flow channels.

Results show that high efficiency of the optimized fin improves the heat

absorption and dissipation potential of a solar air heater [6]. It designed

double flow solar air heater with fins attached over and under the

absorbing plate.

Received: 08 Apr 2013 Accepted: 13 Apr 2013

Keywords: Solar Irradiation Thermal Efficiency Heat Transfer Coefficient Nusselt Number

Correspondence: F. Chabane

Mechanics Department &

Mechanical Laboratory,

Faculty of Sciences

&Technology, University

of Biskra, Algeria.


This resulted in considerable improvement in collector efficiency of double flow solar air heaters with fins

compare to single flowing, operating at the same flow rate [7]. An experimental investigation carried out on

the thermal performance of the offset rectangular plate fin absorber plates with various glazing [8], in this

work, the offset rectangular plate fins, which are used in heat exchangers, are experimentally studied. As the

offset rectangular plate fins, mounted in staggered pattern and oriented parallel to the fluid flow, high thermal

performances are obtained with low-pressure losses. [9] Conducted experiments to study the performance of

three types of solar air heater, namely flat plate, finned and V-corrugated solar air heaters. The V-corrugated

collector was found to be most efficient while, the flat plate collector was the least efficient. Another work

used the cross-corrugated absorbing plate and bottom plate to enhance the turbulence and the heat transfer rate

inside the air flow channel and tested its thermal performance [10, 11]. The work titled of the studied of a

novel solar air collector of pin-fin integrated absorber was designed to increase the thermal efficiency [12]; in

the performance analysis of varying flow rate on PZ7-11.25 pin-fin arrays collector, the correlation equation

for the heat transfer coefficient is obtained and the efficiency variation vs. air flow rate is determined in this

work. Another work reported of results is compared with those obtained with a solar air collector without fins,

using two types of absorbers selective (in copper sun) or not selective (black-painted aluminum) [13]. The

report presents a solar water heater designed with a local vegetable material as insulating material, The study

focuses on the comparative thermal performance of this collector and another collector, identical in design,

fabrication, and operating under the same conditions, using glass wool as heat insulation [14]. Work reported

the effect the mass flow rate in range 0.0078 to 0.0166 kg/s on the solar collector with longitudinal fins

[15,16].The flat-plate solar air heater [17−21] is considered to be a simple device consisting of one

(transparent) covers situated above an absorbing plate with the air flowing under absorber plate [20, 21] Fig. 2.

The conventional flat-plate solar air heater has been investigated for heat-transfer efficiency improvement by

introducing forced convection [22, 23] extended heat-transfer area [24, 25] and increase of air turbulence [26,

27].

2. EXPERIMENTAL

2.1. Thermal analysis and uncertainty a. Heat transfer coefficients

The convective heat transfer coefficient hw for air flowing over the outside surface of the glass cover

depends primarily on the wind velocity Vwind. McAdams [28] obtained the experimental result as:

windwV..h 8375

(1)

where the units of hw and Vwind are W/m²K and m/s, respectively. An empirical equation for the loss

coefficient from the top of the solar collector to the ambient was developed by Klein [29].The heat transfers

coefficient between the absorber plate and the airstream is always low, resulting in low thermal efficiency of

the solar air heater. Increasing the area of the absorber plate shape will increase the heat transferred to the

following air.

b. Collector Thermal Efficiency

The efficiency of a solar collector is the ratio of the amount of useful heat collected to the total amount

of solar radiation striking the collector surface during any period of time. [30−32]:

C

u

AI

Q

SurfaceCollectorStrikingSolarTotal

CollectedEnergySolar

0

(2)

The equation for mass flow rate (m) is

Qm

where ρ is the density of air, which depends on the air temperature and Q are the volume flow rate which

depends on the pressure difference at the orifice which is measured from the inclined tube manometer and

temperature.

Useful heat collected for an air-type solar collector can be expressed as:

87 | P a g e F. Chabane, N. Moummi, S. Benramache, D. Bensahal, O. Belahssen

inoutp

.

uTTCmQ (3)

where Cp is the specific heat of the air, Ac is the area of the collector. The fractional uncertainty about the

efficiency from Eq. (3) is a function of ΔT, m, and I0, considering Cp and Ac as constants.

S.VmWithf

.

So, collector thermal efficiency becomes,

C

inout

p

.

AI

TTCm

(4)

2.2. Thermal performance of conventional solar air heaters

Fig. 1 illustrates the thermal network of conventional smooth plate solar air heater. The thermal

performance of flat plate solar air heater could be observed by considering the energy balance between solar

energy absorbed by absorber plate and useful thermal energy output of the system accompanied by some

losses. The energy balance equation could be written as follows

Where Qa is the energy absorbed by the absorber plate, Ac is the area of the absorber plate, I is the intensity

of insolation, R is the conversion factor to convert radiation on horizontal surface to that on the absorber

plane, (τα)e is the effective transmittance absorptance product of the glass cover-absorber plate combination,

Qu is the useful energy gain and Ql is energy loss from the collector show in Fig.1.

The useful energy gain can be expressed in terms of inlet air temperature Tin and other system and operating

parameters as:

airinleRpt

TTUIRFAQ (6)

p

.

pl

'

lp

p

.

R

Cm

AUFexp

UA

CmF 1 (7)

Where FR is the collector heat removal factor which indicates the thermal resistance meet by the absorbed

solar energy in reaching to the flowing air. Ul is the overall loss coefficient and Tin and Tair are the inlet air

and ambient temperatures respectively. F’ is termed as collector efficiency factor which provides the relative

measurement of thermal resistance between absorber plate and ambient air to that of thermal resistance

between the air flowing through collector and the ambient air.

Collector efficiency factor (F’) is expressed as:

e

l

'

h

UF

1

1 (8)

luca QQIRAQ (9)

Where he is the effective heat transfer coefficient between the absorber plate, and flowing air. The thermal

efficiency of the collector is the ratio of useful heat gain to the incident solar energy falling on the collector.

Therefore

I

TTU

IA

Q airinle

p

u (10)

According to the above equation, the thermal efficiency of the solar collector could be improved by

increasing the value of FR which depends on collector efficiency factor F’. By enhancing the heat transfer


coefficient between absorber plate and air, higher values of F’ could be achieved. Roughening of absorber

surface has been found to be the convenient and effective technique to enhance the convective heat transfer

rates from the absorber surface to air.

The thermo-physical properties of the air have been taken at the corresponding mean temperature Tf from

the following relations of thermo-physical properties, obtained by correlating data from NBS (U.S.) [33]:

0155.0

2931006

f

p

TC

86.0

2930257.0

fTk

735.0

5

2931081.1

fT

fT

293204.1 (11)

Equations used for calculation

The following equations were used for calculating the mass flow rate of air, m (Saini and Saini, 1997), heat

energy transfer, Qu, heat transfer coefficient, h (Saini and Saini, 1997)[34].

50

4

0

1

2.

pCdm

(11)

fpp

u

TTA

Qh

(12)

where Tp and Tf are average values of absorber plate temperature and air temperature, respectively. The

average temperature of the plate was determined from the temperature recorded at three different locations

along the test section of the absorber plate. It was found that the temperature of the absorber plate varies

predominantly in the flow direction only and is linear. The air temperature was determined as an average of

the temperatures measured at three central locations over the test length of the duct along the flow direction.

The Nusselt number was calculated by using the following equation:

k

hDNu h (13)

The Prandtl Number is a dimensionless number approximating the ratio of momentum diffusivity (kinematic

viscosity) and thermal diffusivity and can be expressed:

k

C pPr (14)

2.3. Description of solar air heater considered in this work

A schematic view of the constructed single flow under an absorber plate and in hollow of semi cylindrical

fins which located under an absorber plate system of collector is shown in Fig. 1, the photographs of two

different absorber plates of the collectors and the view of the absorber plate in the collector box are shown in

Fig. 2, respectively. The absorbers were made of galvanized iron sheet with black chrome selective coating.

The plate thickness of a collector was 0.5 mm. The cover window type the Plexiglas of 3 mm thickness was

used as glazing. Single transparent cover was used of a collector. Thermal losses through the collector backs

are mainly; due to the conduction across the insulation (thickness 4 cm), those caused by the wind and the

thermal radiation of the insulation are assumed negligible. After installation, the collector was left operating

several days under normal weather conditions for weathering processes.

Thermocouples were positioned evenly, on the top surface of the absorber plates, at identical positions along

the direction of flow, for both collectors. Inlet and outlet air temperature were measured by two well

insulated thermocouples. The output from the thermocouples was recorded in degrees Celsius by using a

digital thermocouple thermometer DM6802B: measurement range −50 to 1300 °C (−58 to 1999 °F),

resolution: 1°C or 1°F, accuracy: ± 2.2 °C or ± 0.75 % of reading and Non-Contact digital infrared

thermometer temperature laser gun model number: TM330: accuracy ±1.5 C/±1.5 %, measurement range

−50 to 330 °C (−58 to 626 °F) resolution 0.1 °C or 0.1 °F, emissivity 0.95. A digital thermometer measured

the ambient temperature with sensor in display LCD CCTV-PM0143 placed in a special container behind


the collectors’ body. The total solar radiation incident on the surface of the collector was measured with a

Kipp and Zonen CMP 3 Pyran-ometer. This meter was placed adjacent to the glazing cover, at the same

plane, facing due south. The measured variables were recorded at intervals of 15 min and include: insolation,

inlet and outlet temperatures of the working fluid circulating through the collectors, ambient temperature,

absorber plate temperatures at several selected locations and air flow rates (Lutron AM-4206M digital

anemometer). All tests began at 9 AM and ended at 4 PM.

The layout of the solar air collector studied is shown in Figs. 2, 3. The collector A served as the baseline

one, with the parameters as:

- The solar collecting area was 2 m (length) × 1 m (width);

- The installation angle of the collector was 45° from horizontal;

- Height of the stagnant air layer was 0.02 m;

- Thermal insulation board EPS (expanded polystyrene board), with thermal conductivity 0.037 W/(m

K), was put on the exterior surfaces of the back, and side plates, with a thickness of 40 mm.

- The absorber was of a plate absorption coefficient α = 0.95, the transparent cover transmittance τ = 0.9

and absorption of the glass covers, αg = 0.05;

- 16 positions of thermocouples connected to plates and two thermocouples to outlet and inlet flow.

- Five fins under the absorber plate with a semi cylindrical longitudinal form was 1.84 m (length) × 0.03

m (Radian); the distance between two adjacent fins and fins are 120 and mm respectively and 5 mm

thickness Fig. 3.

Fig. 1. Thermal network of flat plate solar air heater.

Fig. 2. Schematic view of the solar air collector


Fig. 3. Composition of a solar box with and without fins.

3. RESULTS

Fig. 4 Average temperature in the thickness of a solar collector versus the whole area of the solar collector plates for a single pass

solar air heater, with flow rates of 0.016 kg/s, for the solar collectors with & without using fins.

Figs. 4a & 4b show the average temperature distribution in the thickness of a solar collector, indicated

the variation of the average temperature correspondent the transparent cover, absorber plate, bottom plate

and exterior plate. We can be seen the difference in Figs. 4a, 4b; at the mass flow rates 0.016 kg.s-1

the

change curves it’s remarkable; and the role of the fins that allows cooled absorber and ensures a better heat

exchange, we can be seen in the figures, when to increase the mass flow rates are effect on the temperature

of the bottom plate and the temperature of an absorber plate by rates between 4 and 6 °C, for the solar

collector without using fins and with fins; the temperature of the bottom plate and the absorber plate

correspondent 0.016 kg.s-1

were (Tbp = 78.75 °C), (Tab= 93.03 °C) and (Tbp = 74.50 °C), (Tab= 94.02 °C)

respectively. The collectors are mounted on a metal frame galvanized. In field the solar energy passing

through the cover glass is absorbed by the absorber plate. The heat generated is then transferred to the

collector fluid [32].

Fig. 5. Hourly variation of solar irradiation, for months of February & May (2012).

b a


Fig.5 shows the hourly variations of the measured solar radiation of different conditions of the days with

about flat-plate and with using fins back the absorber plate, correspondent of months such as January,

February and May when m = 0.016 kg/s, respectively Fig. 5 that the maximum values of solar radiation I are

895 W/m², about flat-plate corresponding the day 19/02/2012 and the solar intensity in the day 15/05/2012

are 757 W/m², when m = 0.016 kg/s, correspondent solar collector with fins; while, their daily average

values are obtained as 803.5 W/m² for flat-plate, about solar collector with fins as 673.5 and 691 W/m². The

temperatures of the various elements its increase with time as the solar radiation increases to show their

maximum values at 13:00, Comparisons between the measured solar intensity of the following time of the

day, are shown in (Fig. 3), on 19 February 2012 and 15 May 2012 of the flat-plate and with using fins, when

mass flow rate m = 0.016 kg/s [35–39]; the difference solar irradiation same 138 W/m². Remark that the low

solar intensity in May cause the tilt angle kept for all the months, the effect tilt angle onto the thermal

characteristics or performance of solar air heaters [16, 17].

Fig. 6. Average temperature along the length of solar collectors versus thickness of panel of between 0 and 0.1 m for single pass

solar air heater, at flow rates of 0.016 kg/s, corresponding with & without using fins.

Figs. 6a & 6b shows the average temperature of a solar collector as a function to length from 0.388 to

1.552 m, correspondent the mode without using fins at mass flow rate were 0.012 kg/s. We can be seen the

curves of the bottom plate in a length of x2 = 0.776 m at m = 0.016 kg.s-1

is (Tbp = 84.50 °C) and the average

temperature of an absorber plate (Tab = 89.50 °C), the average temperature of the bottom plate take the more

heat from an absorber plate; means the fluid which is between the bottom plate and an absorber plate take to

the heat from the absorber plate. The temperature of an absorber plate at the point x2 decreased; cause the air

flow in channel and become stable for all points.

We can be seen in Fig. 6, that the difference average temperature both x1 and x2; means Tab(x2) <

(Tab(x3), Tab(x4)) < Tab(x1) this make clear the fluid take a few heat energies for each location a length of a

solar collector exceptional in a point x2. We can be said when increase the mass flow rate are effected on the

average temperature of an absorber plate and decreases slightly, exceptional in x2, about this location x2; we

can be seen the average temperature of the bottom plate approaching to the average temperature of an

absorber plate does not prospective; it’s could be the fluid take more the heat energy from the absorber plate

and in the same time that the bottom plate take this energy too, this is a result not to air distribution well.

4. CONCLUSION

The present studied that aim to review of designed and analyzed a heat transfer of solar air heater.

Experimental study comparison of a solar collector without using fins and with using fins attached back the

absorber plate. The efficiency of the solar air collectors depends significantly on the solar radiation; mass

flow rate and surface geometry of the collectors and with using fins back the absorber plate. The temperature

of the solar collector improve with increasing solar intensity at mass flow rate 0.016 kg/s, due to enhanced

b a


heat transfer to the air flow. The efficiency of the solar air collector is proven to be higher. The highest

collector efficiency and air temperature rise were achieved by the finned collector with a tilt angle of 45°,

whereas the lowest values were obtained from the collector without using fins.

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Please cite this article as: F. Chabane, N. Moummi, S. Benramache, D. Bensahal, O. Belahssen, (2013), Effect Of Artificial Roughness On Heat Transfer In A

Solar Air Heater, Science and Engineering, Vol. 1(2), 85-93



www.oricpub.com


Vol. 1 (2), 2013, 95-101



THE PREPARATION OF POLYETHYLENE AND MINERAL MATERIAL

COMPOSITES, AND EXPERIMENTAL AND THEORETICAL (USING MCNP

CODE) VERIFICATION OF THEIR CHARACTERISTICS FOR NEUTRON BEAM

ATTENUATION

Majid Zarezadeh

Standard Organization of Hormozgan, Bandar Abbas, Iran

Abstract

In this research, attenuation of neutron flux from Cf252 source and neutron generator

in collision with polyethylene shields containing different wt% of Boric acid has been

studied experimentally and theorically using MCNP Code. The results show that with

changing the energy of neutron for obtaining optimum attenuation, the wt% of Boric

acid should be changed. The experimental results were matched with simulation data.

It has been shown that the polyethylene shields containing 15%wt boric acid the proper

shield for attenuation Cf252neutron flux. For 14MeV neutron generator flux the

polyethylene with 7%wt Boric acid are reasonable.

1. INTRODUCTION

Regard to increase in using nuclear energy in countries and industrial

scientific centers, the importance protect of employee of this place is

clear for scientist. Nuclear equipment and instrumentation make a large

use of neutron shield materials. among nuclear particles neutron has a

especial place for research works because it has no any charge and

power of influence. Employees that work in reactor and neutron

generator accelerator may damage from neutron. Mix of Polyethylene

and mineral element like Cadmium, Lithium, Boron are good absorbent

for neutron[2,3,4]. These materials have been always used in

complexes like B4C and LiF that are expensive materials and high cost

prevents their generalized use. Regarding the big cross section of boron

for neutron complexes of boron is employed more than other complexes.

Boric acid B(OH)3 is cheaper than other boron materials and we can mix

this complex with polyethylene and make a good shield for neutron. In

this paper we have presented a method to make and test a new neutron

shield. The percentage of mixture is an important point to make

neutron shield so at first some mixture has been simulated with MCNP4c

code for mix7%,15%,25%,35% boric acid and tested with Cf252,neutron

generator with code then through experiment[2].

2. HOW TO MAKE NEUTRON SHIELD MATERIALS

For making polymeric shield complex of Boric acid and polyethylene

has been used. After wt% chemical calculation in different %wt and

simulation with computer the sample with 7,15,25,35 wt% boric acid and

polyethylene have been made.


Correspondence: Majid Zarezadeh

Standard Organization of

Hormozgan

Bandar Abbas, Iran


For making polymeric shield we must attend to some point. First because of the low density of boric

acid as compared with polyethylene and more melt temperature of boric acid with regard to polyethylene,

the boric acid powder has been deposited. Second point regard to toxic hot boric acid at the moment of

warming up, the user should be cautious.

Making polymeric layer shield has three phases is that the:

Melting PE and mixing with boric acid

Cooling mix sample and rolling pin

Re melting and pressing mix sample then shaping shield

Phases and the needed time are shown in table1.

Table 1.phase of work and time

Stage of phases Needed time(in minute)

Melting and mixing the samples 20

Cooling and to dough samples 60

Re melt and pressing samples 15

In the first stage in regard to chemical calculation mix sample material was hold in plant. This machine is

adjustable in temperature and time, capacity of this plant was 200 cm3 in any use. Melting temperature of PE

is 180o in centigrade degree and the machine should be fixed in this temperature. At first PE must be strew

in the machine and heated for 5 min then boric acid must to strewed in it, mixed and melted with PE for 15

min simultaneously. In any use of machine total time was 20 minutes. After this stage let them get cold

for 60 min. At last stage the mix must be re melt and pressed. This stage has five sub stages that we can

see in table2.

Table2.re melt and to press sub stage

stage Temperature(in

centigrade)

Time(in second) Press(bar)

1 120 50 10

2 180 65 20

3 180 100 25

4 180 140 15

5 0 120 0

The three dimensions of mix sample shield was 10cm width*15cm length*2mm of thickness. It must be

noted in sub stage temperature 1800 centigrade was the melt temperature of PE and is needed to shape the

mix sample lactic and in this way the distribution of boron in PE became homogeneous.

Table3.density of sample

Shield model Density of sample gr/cm3

PE mix with 7% boric acid 0.85




3. ATTENUATION OF NEUTRON BEAM THROUGH SHIELDS

In order to experiment the attenuation of neutron beams in polymeric shield two methods was committed.

once through using Cf252with middle energy 2Mev and second through using neutron generator with

14Mev energy. the simulation of this experiment has been done through MCNP4c code.

3.1 Attenuation of neutron beams of Cf252source through polymeric shield

The activity of Cf252source was 100µCi. In this experiment to detect neutron, a gaseous BF3 detector

has been used[1]. Cf252 source has a gamma spectrum and reaction of neutron with polymeric shield

materials has (n,γ) reaction. Regard to this point in experiments separating of gamma from neutron is

97 | P a g e M. Zarezadeh

important. BF3 detector detect and count both gamma and neutron particles. Simulation with MCNP4c

Code has shown that neutron collision with material shield causes gamma ray with 2.2Mev for hydrogen,

4.9Mev for carbon, 0.47Mev for boron. other gammas of material shield have been imperceptible on

gamma spectrum in simulation. Regard to this gamma spectrum in MCNP4c Code, BF3 detector has been

placed in a gamma shield in order to reduce the gamma detect and count through BF3 detector. This shield

was a layer of lead that was simulated whit code. The use of collimator helps to collimate the neutron

beams. This collimator was made of Iron, paraffin, cadmium. Backscattering neutrons can damage count

and detect so a neutron shield includes 5cm lead,1mm cadmium , 5 cm polyethylene that have been placed

around detector. The set up has been shown in figure1. Important point in this experiment was the

separation of neutron and gamma ray. Gamma separation has been done through proper electronic or place

lead between sample and detector. The electronic has been shown in figure 2.

Fig1. Set up of neutron attenuation experiment with Cf252

Fig2. Electronic of experiment with Cf252

3.2 Attenuation of neutron beams of Neutron generator14Mev through polymeric shield

The yield of neutron generator was 109-10

10 neutron per second in each use. In the second experiment

neutron generator with 14Mev energy has been used. Neutron generator output has mono energy beams.

Regard to the high energy of neutron in this experiment the probability of production (n,2n) reaction

increases. In simulation with MCNP4c code fast neutron reaction with iron and cadmium in neutron

spectrum (n,2n) has been seen. There was two peaks in neutron (n,2n) reaction spectrum in 8 Mev for


cadmium and 5 Mev for iron. The set up of this experiment was like the set up with Cf252 source. Gamma

spectrum simulation has shown that gamma peaks were more than gamma peaks of Cf252 source reaction.

In this spectrum added gamma peaks in (n,γ) of Cf252were because of fast neutron, gammas of oxygen and

metals of collimator has been traced in simulation so in this experiment gamma ray was more than the first

experiment with Cf252 source. For detect and count neutrons in this experiment two NE102 scintillator

detectors have been used [4]. One of these detectors was counter and the other was used to normalize each

count. In each use neutron generator yield changed so one detector has been used for normalize was

necessary. Gamma and neutron backscattering was more than Cf252source experiment so the shield round

detector should be more thick than in the first experiment. Electronic of this experiment has been shown in

figure3.

Fig3. Electronic of experiment with Neutron generator

4 .EXPRIMENT RESULTS

After doing the experiment and radiation of polymeric shields analysis the result was analyzed. To

reduce error and increase accuracy, each experiment repeated for 3 times. Half Value Layer (HVL) of each

polymeric shield has been shown in table4 , 5. Neutron attenuation on polymeric shields is shown in

figure4,5.

Table4.HVL in experiment with Cf252 source

Shield class Mix 7%wt

boric acid

Mix 15%wt

boric acid

Mix 25%wt

boric acid

Mix 35%wt

boric acid Polyethylene

HVL(mm) 18 12 14 14 18

Table5.HVL in experiment with neutron generator

Shield class Mix 7%wt

boric acid

Mix 15%wt

boric acid

Mix 25%wt

boric acid

Mix 35%wt

boric acid Polyethylene

HVL(cm) 7 8 8 8 8


fig4. Neutron attenuation of Cf252

source on polymeric shields

fig5. Neutron attenuation of neutron generator on polymeric shields

The results show that for 14Mev neutron mix 15%wt boric acid with polyethylene had the best

attenuation and for Cf252 source with a middle 2Mev energy mix 7%wt boric acid with polyethylene had

the best attenuation. Results show that increase of boron in mix composite isn’t a good method, being

hydrogen and moderator property of these elements are important causes of decreasing neutron energy.

Neutron collisions with hydrogen atom in shield have reduced the neutron energy to thermal, then boron

atom with a big cross section absorbs neutron particles so much increase in boron composite may be

damaging and decrease the attenuation property of shields.

14Mev neutron attenuation on polymeric shields

0.00E+00

5.00E+06

1.00E+07

1.50E+07

2.00E+07

2.50E+07

0 2 4 6 8

Thickness of polymeric shields[cm]

pa

rtic

le f

lux

/[c

m-2

.s-1

]

Polyethylene(PE)

Mix 15 wt% boric acid

with PE


with PE


with PE


with PE

Neutron Attenuation on polymeric shields

0.00E+00

5.00E+03

1.00E+04

1.50E+04

2.00E+04

2.50E+04

3.00E+04

0 5 10 15 20

Thickness of polymeric shields[mm]

Pa

rtic

les

flu

x/c

m-2

.s-1

Mix 35 wt% boric acid wit

PE


with PE


with PE

Mix 7 wt% boric acid with

PE

Polyethylene(PE)


Fig6. Gamma spectrum of Cf252with polymeric shields

Fig7. Gamma spectrum of neutron generator(14Mev) with polymeric shields

Figures 6,7show the gamma spectrum of (n,γ) reaction of Cf252and neutron generator with polymeric

shields. in both spectrums 6.13Mev for oxygen and 4.7Mev for carbon. A 0.47Mev for boron atom can be

seen.

5. CONCLUSIONS

Percentage of materials in making polymeric shield is an important point. Regard to this point increase or

decrease of each material can change the attenuation or HVL of each shield. Increase of some materials like

hydrogen can make prompt gamma so this is one of the short comings of shields. Because simulation with

MCNP4c Code had a good mach well with experiment, mix of PE and boric acid between 7-15 wt% can

have an optimum attenuation for shields.

REFERENCES

[1]S.C.Gupta, G.L.Baheti, B.P.Gupta(2000) . Applcation of hydrogel system for neutron attenuation.

Radiation Physics and Chemistry , vol 59, pp103-107

[2]Y.Sakurai,A.Sasaki,T.Kobayashi(2004) . Development of neutron shielding material using

metathesis-polymer matrix , Nuclear Instrument and Method in Physics Research A,vol 522 , pp 455-461

Gamma spectrum of neutron generator(14Mev)

with sample

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

0 2 4 6 8 10

Energy[Mev]

Pa

rtic

le f

lux

[cm

-2.s

-1]

Mix 35% wt boric acid

with PE

Mix 7% wt oric acid

with PE

Mix 15% boric acid

with PE


with PE

Gamma spectrum of 252Cf source with sample

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

0 3 6 9 12

Energy[Mev]

Pa

rtic

le f

lux

[cm

-2.s

-1]

Mix 25% wt boroc

acid with PE


with PE

Mix 15% wt boric

acid with PE

Mix 35% wt boric

acid with PE

Polyethylene(PE)


(2004)

[3]V.E.Aleinikov, L.G.Beskrovnaja, B.V.Florko(2002) .Characteristics of polyethylene-moderatored

Cf252neutron source , Nuclear Instrument and Methods in Physics Research A , vol476 , pp378380

[4]El-Khatib, A.M., Fawzy, M.A., Abou Taleb, W.M.(1996) .Attenuation of D-T puls neutron in borated

low density polyethylene” , Material Letters , vol 26(1/2),pp59-63

Please cite this article as: M. Zarezadeh, (2013), The Preparation Of Polyethylene And Mineral Material Composites, And Experimental And Theoretical (Using Mcnp Code) Verification Of Their Characteristics For Neutron Beam Attenuation, Science and Engineering, Vol. 1(2), 95-101



www.oricpub.com


Vol. 1 (2), 2013, 103-120



NATURAL FREQUENCY, MODE SHAPE, BUCKLING AND

POST-BUCKLING ANALYSIS OF MEMS WITH VARIOUS CLAMPED

POSITION

Milad Faraji

1, Morteza Dardel

1, Mohammad Hadi Pashaei

1

1Babol Noshirvani University of Technology, Mazandaran, Iran

Abstract

In this paper the buckling and post-buckling analysis of parallel beams with various

clamped position between them for different ends supports were investigated

analytically. Moreover, the natural frequencies of this mechanism were obtained. In this

way, the equations of motions and boundary conditions derived based on Euler-

Bernoulli theory and Hamilton principle. Also, by solving linear part of equations of

motion statically, the buckled critical loads and corresponded mode shapes were

acquired. Considering buckled configuration as multiplication of linear mode shape

with unknown amplitude then solving nonlinear equations of motions statically, gives

buckled configuration amplitude. In addition, by solving dynamic equation of motions,

the natural frequencies of system have been obtained in each given axial loads. The

effects of numbers and location of clamped positions, between parallel beams and end

supports on buckled and post-buckled mode shapes, as well as the natural frequencies

has been investigated.

1- INTRODUCTION

Micro electro mechanical systems (MEMS) have large usage in

various fields such as surgery’s instruments, bio-mechanic, valves and

generally in precision engineering. In addition, since the range of motion

of MEMS is limited so, additional movement is not suitable and reduced

the performance. Consequently, mechanisms with specified stable

positions such as bi-stable and multi-stable mechanisms appropriated. So

there are several articles which have been these issues such as: Jin Qiu

[1] presented a monolithic mechanically bi-stable mechanism that

doesn’t rely on residual stress for its bi-stability and investigated force-

displacement curve of parallel center clamped beams with clamped end

supports. Nima Tolou [2] obtained the effect of change of parameters

such as initial angle, pre-loading and thickness on the behavior of force-

displacement curve. J.Prasad [3] presented a formulation for the

automatic synthesis of two-dimensional bi-stable, compliant periodic

structures. Daniel. L. Wilcox [4] developed and introduced a new class

of micro bi-stable mechanisms, the fully compliant tensural bi-stable

mechanism class, by describing the basic phenomena. Enikov et al [5]

designed a v-shaped thermal micro actuator with buckling beams.

Nevertheless, the precise computation model for the buckled and post-

buckled beam based on the large deflection theory has not been built yet.

Seide [6] discussed the accuracy of some numerical methods for column

buckling. Mau [7] studied the stability of the post-buckling paths of

columns with discrete spring supports.


Keywords: MEMS Center Clamp Beam Buckling Post-Buckling Axial Load

Correspondence: Morteza Dardel

Babol Noshirvani


Mazandaran, Iran


Fang and Wickert [8] studied the static deformation of micro machined beams under in-plane

compressive stress. Wang [9] presented the complete post-buckled and deformation of an elastic rod, one

end fixed and one end pinned. Coffin and Bloom [10] analyzed the post-buckled response of an elastic and

hygrothermal beam fully restrained against axial expansion.

Li and Zhou [11] studied the post-buckled behavior of a hinge-fixed beam under evenly distributed follower

forces. Zhao and Jia [12] have studied the governed differential equations of post-buckled clamped-clamped

inclined beams. They also, investigated the effects of central force on beam’s behavior. But, the influences

of changing different parameters specially clamped position between parallel beams on buckled and post-

buckled mode shapes and natural frequencies haven’t been investigated, so, in this article this issue was

investigated. Generally, stable mechanisms can be divided into three main categories: mono-stable, bi-stable

and multi-stable. A mechanism with two stable equilibrium positions within its range of motion is called bi-

stable. Also, a mechanism with more than two stable positions is called multi-stable. One of the unique

advantages of these mechanisms is their ability to hold system stable in the presence of small external

disturbance without applying external force. These mechanisms have an important force-displacement

curve, which explain important advantages of bi-stable and multi-stable mechanisms such as negative

stiffness [13], input and output energy, input and output force and so on. With these especial advantages, bi-

stable and multi-stable mechanisms have widely usage in MEMS such as relays [14, 15], valves [16-18] and

in particular in precision engineering like laparoscopic graspers with two or more stable positions [19].

Figure 1. Curve-shaped center clamped beam with clamped end supports and axial and center force loads.

Bi-stable and multi-stable mechanisms in their simplified model can be assumed as a parallel beams with

different shape such as v-shape or curve-shaped.

In this article buckling and post-buckling mode shapes and natural frequencies of parallel beams with

various clamped positions and different end support were investigated analytically. In this way, linear and

non-linear equations of motions of beams were derived based on Euler-Bernoulli theory and Hamilton

principle. By solving the linear equation of motion of beams the critical buckled axial loads for different

mode shapes and buckled mode shapes with unknown amplitudes obtained. Then, by solving the nonlinear

equation of motion with initial values which were obtained by solving the linear equation of motion, the

post-buckled mode shapes were obtained. In addition, by solving the dynamic equation of motion with the

time terms the natural frequencies for different mode shapes were acquired.

2- NONLINEAR EQUATION OF MOTION OF PARALLEL BEAMS WITH CLAMPED

BETWEEN THEM

In this part shown how the buckled and post-buckled mode shapes obtained. In this way firstly non-linear

equation of motion of beam according to Euler-Bernoulli theory investigated. Then, the buckled mode

obtained from solving the linear equation of motion of beam which extracted from non-linear equations.

Afterward, by solving linear equation of motion buckled modes, critical axial loads and initial values for

post-buckled modes investigated. Hence, by solving the non-linear equations of motions with initial values

which were extracted from solving the linear part, the post buckled mode shapes investigated. In addition,

this post-buckled mode generated by axial load which is deforms beams shape into curve shape.

According to Euler-Bernoulli beam theory, displacement component of any point of a beam are given by

[20]:

00 0,i

i i i i i

wu u z w w

x

(1)

105 | P a g e M. Faraji, M. Dardel, M. H. Pashaei

Where the axial displacement was denoted by iu and the transverse displacement was denoted by iw of a

point with height of iz . In addition, 0iu and 0iw denotes these quantities for mid-plane of the beam. The

subscript i refer to i’th segment of the beam as shown in Fig. 1.

The components of strain and stress were given by [20]:

22

0 0 0

2

1

2

i i ixx i

u w wz

x x x

(2)

0zz zx (3)

22

0 0 0

2

1

2

i i ixx i i i i

u w wE E z E

x x x

(4)

0zz zx (5)

Where , and are the beam’s young modulus, axial strain and shear strain, respectively for each

segment of the beam. Accordingly, xx , zz , and zx are related stresses For Euler-Bernoulli beam

theory. The strain energy (Π ) and kinetic energy (T ) and work of the beam is given by [20]:

22 4 2 22 2 220 0 0 0 0 0 0 0 0

2 2 2

1 1Π 2

2 4

i i i i i i i i ii i i i

i V

u w w u w u w w wE z z z dV

x x x x x x x x x

(6)

22 22 220 0 0 0 01

22i i i i i

i

i V

ii

u w u wT d

wz z

t t x t t xV

t

(7)

2

1

2

0 01,

2

i

i

L

i iP

i L

u wW P x t dx

x x

(8)

Where:

, ,P x t p x t A

By using extended Hamilton’s principle, two coupled nonlinear equations of motions are as follows:

24 2 2 2 4 2

0 0 0 0 0 0 0 0 0

2 2 2 2 2 4 2

2

0 0

2

3

2

,, 0

i i i i i

i

i i i ii i i i i i i i i i

i i

w w u w u w w w wI A E A E I E A

x t t x x x x x x x

P x t w wP x t

x x x

(9)

2 2 2

0 0 0 0

2 2 2

,0

i

i i i ii i i i i i

P x tu w w uA E A E A

t x x x x

(10)

And boundary conditions are as follows:

2

1

33 3

0 0 0 0 0 002 3

1,

20i

i

Li i i i i ii i i i i i i i i L

w u w w w wI E A E A E I P x t w

x t x x x x x

(11)

2

1

2

0 00

1

20,

i

i

Li i

i i i i iL

w uE A E A P x t u

x x

(12)

iE xx zx


2

1

2

0 0

20

i

i

L

i ii i

L

w wE I

x x

(13)

Following dimensionless quantities were introduced as:

2

2 2 2 2

1 1 1 1 1 1

, , , , , , ,i i i i ii i i i

i i

I E I E Ax w u L PLW U r s

L L L A r E I E A E I (14)

So, equations of motions and boundary conditions in final dimensionless forms will be:

22 2 4 2 22

2 2 2 20 0 0 0 0 0 0 0

2 2 4 2 2 2

30

2

i i i i i i i ii i i i

i

U W U W W W W Ws s

(15)

2 2

0 0 0

2 2

0i i iW W U

(16)

2

1

3322 20 0 0 0 0

02 3

1

20

i

i

Li i i i i

i i i Li

W U W W Ws s W

(17)

12

0 0

2

0

0

iL

i iW W

(18)

2

1

22

0 002 2

20

1i

i

L

i ii

i iL

U WU

s

(19)

3- Analytical Solution for buckled mode For investigating buckled and post-buckled mode of beam with different clamped position, the time

dependent terms were ignored and P was assumed to be constant. In buckling analysis critical values of

( )c cP at which a change in beam shape deformation due to axial load occurs, was determined. Buckling

load can be determined from linear theory. Meanwhile, buckling loads show bifurcation values for changing

beam deformation due to axial loads.

For investigating the buckled mode of the beam, the linear part of Eq. (15) and Eq. (17) should be

derived. So the buckling equation of motion was obtained as:

4 22

0 0

4 2 2

0i i

i

W W

(20)

A solution in the form of 0

sx

i iW C e was assumed for Eq. (20). By solving the related characteristic

equation, following form of the solution will be obtained:

0 1 2 3 4cos sin( )i i i i iW C C C C (21)

Where ii

. In addition, the constants and value of buckling load P in can be

determined by applying boundary conditions to Eq.(21).

For example, solution of 0iW for center clamped with clamped-clamped end supports were obtained in

follows. Boundary conditions at the end supports are:

1 2 3 4, , ,i i i iC C C C


10

10

20

20

00 0, 0

11 0, 0

WW

WW

(22)

And boundary conditions at the clamp point between parallel beams which was defined with 1L are:

10 1 20 1

10 1 20 1

W L W L

dW L dW L

d d

(23)

3 3

20 102 2 1 13 3

2 2

20 102 2 1 12 2

0

0

w wE I E I

x x

w wE I E I

x x

(24)

Now, by substituting 10W and 20W in boundary condition of Eq.(22-24), following equations resulted:

11 13 0C C (25)

12 14 0C C (26)

21 22 23 24cos sin 0C C C C (27)

22 23 24sin cos 0C C C (28)

11 12 1 13 1 14 1 21 22 1 23 1 24 1cos sin cos sin( ) 0C C L C L C L C C L C L C L (29)

12 13 1 14 1 22 23 1 24 1sin cos sin cos 0C C L C L C C L C L (30)

3 3 3 3

23 2 2 24 2 2 13 1 1 14 1 1sin cos( ) sin cos( ) 0C E I C E I C E I C E I (31)

2 2 2 2

23 2 2 24 2 2 13 1 1 14 1 1cos sin cos sin 0C E I C E I C E I C E I (32)

Which by writing Eqs. (25-32) in matrix form, and solving the related eigenvalue problem, the buckled

mode shapes and critical buckling loads of cP were determined.

4- Analytical Solution for post-buckled mode For investigating post-buckled mode the nonlinear form of Eq. (15) without considering time dependent

terms should be solved. The buckling load as described in section 3, give the critical values for which a

change in which the beam mode shape due to axial load will occur. Before the first buckling load, the beam

deflection is zero. Greater than this critical value, a deflection occur in the beam. But the deflection of beam

for values of axial load greater than critical buckling load cannot be determined from linear theory. Linear

theory only gives the limiting values for changing the shape of the deflection of the beam. The defection of

the beam after deflection must be obtained through the including the nonlinear terms.

For post-buckling analysis, ( )P is assigned to the valued obtained from linear buckling analysis of

( )c cP . Hence in post-buckling analysis P is known.

For solving this nonlinear equation, firstly axial deflection ( ) should be solved in Eq. (16) and

substituted in Eq. (15) as:

22

0 0

2

1

2

i iU W

(33)

0iU


2

0 01

1

2

i ii

U WC

(34)

2

00 1 2

0

1

2

ii i i

WU d C C

(35)

Then, by applying boundary conditions for in-plane displacement at each ends of beams, 0i

U can be

expressed in terms of 0i

W . Hence 0i

U can be removed from equations, and nonlinear equation of motion can

be described in terms of 0i

W . The procedure in applied to center clamped beams with clamped-clamped end

supports as follows.

For this beam boundary conditions of 0iU at each ends and clamped point are:

10 200 0, 1 0U U (36)

10 1 20 1U L U L (37)

2 2

2 210 20 20 102 2

1 10

2 2

U U W W

(38)

By applying boundary conditions of Eq.(36), 0iU can be obtained as follows:

2

1010 11

0

1

2

WU C d

(39)

21

2020 21

11

2

WU C d

(40)

Then, by substituting 0iU into Eq. (15), the following equation will be obtained.

4 22

210 10

1 114 2 2

1

0

W Ws C

(41)

4 22

220 20

2 214 2 2

2

0

W Ws C

(42)

Where 11C and 21C are 10U and 20U ’s constant values. Afterward, by assuming the solution in the form of

0

x

iW e and substituting into Eqs. (41) and (42), the post-buckling mode shape will be:

10 10 11 12 1 13 1 cos sinW D D D D (43)

20 20 21 22 2 23 2 cos sinW D D D D (44)

Where the ’s values were given by:

2 2

2 2

1 1 11 2 2 212 2

1 2

,s C s C

(45)

By substituting Eqs.(43) and (44) in Eq. (39) and applying boundary conditions of Eq.(37) and (38) on these

equations, constant of 11C and 21C could be rewritten in forms of ij

D as follows:


2

2 211 2 2

1 1 2 2

E AC

E A s

(46)

2 22 2 3 2 3 4 2 5 2 2

22 11 1 11 12 1 11 13 1 12 1 12 13 1 13 1 1 12 2 2 2

2 2 1 1 2 2

1 2 3 9

2 3 2 10

E AC D L D D L D D L D L D D L D L L L

s E A s

(47)

Also, constants of ij

D could be obtained by applying following boundary conditions:

10

10

00 0, 0

WW

(48)

20

20

11 0, 0

WW

(49)

10 1 20 1

10 1 20 1( ) ( )

W L W L

dW L dW L

d d

(50)

3 32 2 220 10 20 10

11 1 13 3

2

2

0

W W W WC s

(51)

2 2

20 10

2

2

2 20

W W

(52)

Consequently, Eqs. (39-42) and (48-52), present complete equations for determining post-buckling mode

shapes. In these equations ij

D , 11C , , 1 and should be obtained by numerical method. In addition, for

obtaining them, initial estimates which can be obtained from buckling analysis of section 3 are necessary.

5- ANALYTICAL SOLUTION FOR NATURAL FREQUENCIES AND MODE SHAPES

For investigating natural frequencies and mode shapes of beams with different clamped position,

nonlinear terms and axial load of P are ignored. Hence linear part of equations with considering time

dependent terms were retained. So, linear equations of motion for obtaining these characteristics are:

4 2 4

0 10 10

2 2 2 40i

i i i i i i

w w wI A E I

t x t x

(53)

Also, this equation can be written in dimensionless form as follow:

4 2

2 4 40 004 2

0i ii ni ni i

d W d WW

d d

(54)

Where:

2 24 2

0 02,, nti i n i

ni i i i

i i i

A L Iw W e

E I A L

(55)

By solving Eq. (54), the roots of the characteristics equation were obtained as:

21C 2


2 2 4 4

1

4 4 2 2

2

12 4

14 2

i ni i nii ni

i ni i nii ni

(56)

In accordingly to these characteristics values the mode shapes are:

10 11 11 21 11 31 21 41 21cos sin cosh sinhW C C C C (57)

20 12 12 22 12 32 22 42 22cos sin cosh sinhW C C C C (58)

In addition, natural frequencies of n and the ratios of the constants of 11ijC C can be obtained from

applying boundary conditions at each supports and clamped position. The boundary conditions for each ends

are similar to the buckling case, but boundary conditions at each middle clamped point were defined as

follows:

3 3

20 1 20 1 10 1 10 12 22 2 1 12 2 1 12 3 2 3

0n n

d W dW d W dW LE I E II I

L d d L d d

L L L

(59)

2 2

20 1 10 12 2 1 1

2 2 2 20

d W d WE I E I

L d L d

(60)

Now by substituting the Eqs. (57, 58) in boundary conditions which were shown at Eqs.(59,60) and Eqs (22-

24), the natural frequencies were obtained.

6- RESULTS AND DISCUSSION

In this part the buckled, post-buckled mode shapes and natural frequencies of parallel beams with one or

more clamped between them which were obtained from previous parts investigated.

6-1. Investigating buckled and post-buckled mode of various clamped beams with different end

supports

The buckled mode shapes and critical axial loads which caused deformation in parallel beams were

obtained by solving the linear equations of motions. In addition, the post-buckled mode shapes which shown

the amplitude of deformation were obtained by solving the nonlinear equations of motions. In this part,

results of buckled mode shapes with values of critical axial loads for each mode shapes investigated.

Furthermore, the post-buckled mode shapes for parallel beams with one or more clamped between them and

different end supports investigated.


Figure 2. Buckled mode shapes with critical axial loads for different mode shapes for parallel beams

with a clamped at the center of them with clamped end supports

In Fig. 2 the buckled mode shapes and critical axial loads of parallel beams with a clamped at the center

of them which were supported by clamped end supports investigated. As shown in this figure, the second

and forth mode shapes have one and three nodes respectively. On the other hand, the third mode doesn’t

have any nodes which were occur because of the clamped at the center of beams.

Figure 3. Buckled mode shapes with critical axial loads for different mode shapes for parallel beams with

two clamped at 0.25 and 0.75 of the length of the beams with clamped end supports

Fig. 3 shows the buckled mode shapes for first two mode shapes. As shown in this figure the second

mode shape at the clamped positions flatted which were occur because the clamped positions have bigger

stiffness than other parts. In addition, increasing the clamped numbers caused the critical axial load in

second mode increased.


Figure 4. Buckled mode shapes with critical axial loads for different mode shapes for parallel beams with three

clamped at 0.25, 0.5 and 0.75 of the length of the beams with clamped end supports.

In Fig. 4, by increasing clamped numbers to three, at the 0.25, 0.5 and 0.75 of the length of the beam the

buckled mode shape of second mode same as previous type at the clamped positions flatted. In addition, the

critical axial loads in first and second modes in compared with basic type which was shown in Fig. 2,

increased.

Figure 5. Buckled mode shapes with critical axial loads for different mode shapes for parallel beams with a

clamped at the center of them with simply end supports


Figure 6. Buckled mode shapes with critical axial loads for different mode shapes for parallel beams

with a clamped at the center of them with clamped-simply end supports

In Figs. 5 and 6, the influence of changing end supports on buckled mode shapes and critical axial loads

were investigated. As shown in these figures, by changing the end supports to simply-simply and clamped-

simply the critical axial loads in compared with clamped end supports decreased. These reductions occur,

because by changing the end supports from clamped-clamped to other ones the stiffness of mechanisms

decreased. In addition, as shown in these figures, changing end supports caused the numbers of nodes in

different mode shapes rebounded to normal values. Hence, the second mode has a node and third and forth

modes have two and three nodes respectively.

Figure 7. Influence of increasing the axial load on first mode of post buckled graph of parallel

beams with a clamped at the center of them which were supported by clamped end supports.


Figure 8. Influence of increasing the axial load on second mode of post buckled graph of parallel

beams with a clamped at the center of them which were supported by clamped end supports.

In Figs. 7 and 8, the influence of increasing the axial load on the post buckled mode shapes of parallel

beams with a clamped at the center of them with clamped end supports investigated. As shown in Fig. 7, by

increasing the axial load from 7.5 to 20 which these values were dimensionless, the post buckled graph goes

up. In addition, as shown in this figure the pick of plot flatted because of a clamped which placed at the

center of parallel beams. Furthermore, in Fig. 8 influence of increasing this force from 10 to 20 on second

mode of post-buckled mode were investigated. As illustrated in this figure, by increasing this force, the

picks of the post buckled mode shifted up. In addition, the initial value of axial load for changing the mode

shape to second mode in compare with first mode increased, because bigger axial load needed to change the

mode shapes.

Figure 9. Influence of increasing the axial load on first mode of post buckled graph of parallel beams with

two clamps at the 0.25 and 0.75 of the length of the beams which were supported by clamped end

supports.


Figure 10. Influence of increasing the axial load on second mode of post buckled graph of parallel beams with

two clamps at the 0.25 and 0.75 of the length of the beams which were supported by clamped end supports.

Effect of increasing the axial load on different post-buckled mode shapes of parallel beams with two

clamped between them with clamped end supports in Figs. 9 and 10 was investigated. As shown in Fig. 9,

by increasing the axial load from 7.5 to 20 the pick of post-buckled mode shapes increased. In addition, as

shown in this figure the pick of graph in maximum level smaller than the maximum pick of Fig. 7. So, by

increasing the clamped numbers the stiffness of mechanism increased. Furthermore, the pick of graph in this

figure is not flatted because the center of beams don’t have clamp. In Fig. 10, influence of increasing the

axial load from 10 to 20 on second mode of post-buckled mode shape was investigated. As shown in this

figure by increasing the axial load in addition of increasing the picks of graph in both sides, the picks of

graph at the clamped position flatted.

Figure 11. Influence of increasing the axial load on first mode of post buckled graph of parallel beams with three

clamps at the 0.25, 0.5 and 0.75 of the length of the beams which were supported by clamped end supports.


Figure 12. Influence of increasing the axial load on second mode of post buckled graph of parallel beams with three

clamps at the 0.25, 0.5 and 0.75 of the length of the beams which were supported by clamped end supports.

As illustrated in Figs. 11 and 12, picks of graphs at the clamped positions flatted which show the clamped

positions in each places are stiffer than other positions of beams. In addition, the dimensionless values of

increasing the picks of graphs in Fig. 11 for increasing the axial load from 7.5 to 20 and in Fig. 12 for

increasing the load from 10 to 20 were obtained. In addition, results show that by increasing the clamped

numbers the stiffness of mechanism totally increased.

Figure 13. Influence of increasing the axial load on first mode of post buckled graph of parallel beams with a

clamped at the center of them which were supported by simply end supports.


Figure 14. Influence of increasing the axial load on second mode of post buckled graph of parallel beams with a

clamped at the center of them which were supported by simply end supports.

In Fig. 13 and 14, the influence of changing the end supports on post-buckled mode shapes in different

mode shapes was investigated. As shown in Fig. 13, by increasing the axial load from 7.5 to 20 the pick of

post-buckled mode shapes increased but this rise smaller than similar mechanism with simply end supports.

This reduction occurs, because of decreasing the end supports stiffness by changing them to the simply-

simply. In addition, as illustrated in Fig. 14, the symmetry of the picks of the graph destroyed. So, by

changing the end supports the post-buckled mode shapes in different modes changed which values and

shapes of changes in Figs. 13 and 14 illustrated.

Figure 15. Influence of increasing the axial load on first mode of post buckled graph of parallel beams with a clamped

at the center of them which were supported by clamped-simply end supports.


Figure 16. Influence of increasing the axial load on second mode of post buckled graph of parallel beams with a

clamped at the center of them which were supported by clamped-simply end supports.

Also, in Figs. 15 and 16, influence of changing the end supports to clamped- simply on post-buckled

mode shapes in different modes were investigated. As shown in these figures values and shapes of changing

in compare with Figs. 7 and 8 were shown.

6-2- Natural frequency of the parallel beams with one or more clamped between them and different

end supports In this part influence of changing parameters on natural frequencies of the first two modes shapes of

parallel beams with one or more clamped between them and different end supports were investigated. As

obtained in [20], the natural frequencies for simple beams with clamped end supports in first two mode

shapes are 4.7300407448627 and 7.853204624096065 respectively. In addition these values for simply end

supports are 3.1416 and 6.2832 and first two modes shapes of natural frequencies as obtained in [20] are

3.9266 and 7.0686.

Table 1. Dimensionless values of natural frequencies for various clamped position due to their end supports

Type Natural frequency

First mode Second mode

Clamped end supports with a clamped at the center of beam 4.644869 7.852394

Clamped end supports with two clamped at 0.25L and 0.5L 4.635212 7.683577

Clamped end supports with three clamped at 0.25L, 0.5L and 0.75L 4.562812 7.683108

Simply end supports with a clamped at the center of beam 3.119798 6.282856

Clamped-simply end supports with a clamped at the center of beam 3.871434 7.060027

As obtained in table 1, by changing the structure of simple beam to Fig. 1, the natural frequencies of them

in compare with simple beams decreased. This reduction occur, because of increasing the stiffness of the

beams by adding a clamped between parallel beams. Furthermore, as obtained in this table, by increasing the

clamped numbers the natural frequencies in these modes decreased which this reduction occur because of

amplification of the stiffness of the mechanism.

Also, by changing the end supports to simply-simply and clamped-simply the natural frequencies in

compare with clamped end supports decreased.

7- CONCLUSION

In this article, the general equation of motion for parallel beams with a clamped at the center of them and

clamped end supports by Euler-Bernoulli theory and Hamilton principle was obtained. Then, by solving the

linear and non-linear equations of motions the buckled and post-buckled modes shapes were obtained. In

addition, by solving the non-linear equation of motion with response to time terms the natural frequencies of

this mechanism were obtained. Also, influence of changing parameters on buckled and post-buckled mode

shapes and natural frequencies were investigated.


As concluded from results, by increasing the clamped numbers the stiffness of mechanism totally

increased. So, this amplification in stiffness caused the critical axial loads in different modes increased. On

the other hand, increasing the stiffness caused the amplitude of the post-buckled mode shapes and natural

frequencies in different modes decreased. Also, results showed by changing the end supports to simply-

simply and clamped-simply the end supports stiffness in compare with clamped end supports decreased. As

well, this reduction causes the amplitude of post-buckled mode shapes and critical axial loads in different

modes shapes decreased.

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Please cite this article as: M. Faraji, M. Dardel, M. H. Pashaei, (2013), Natural Frequency, Mode Shape, Buckling And Post-Buckling Analysis Of Mems With

Various Clamped Position, Science and Engineering, Vol. 1(2), 103-120



www.oricpub.com


Vol. 1 (2), 2013, 121-132



PHASOR MEASUREMENT UNITS FOR OUT-OF-STEP

DETECTION OF A MULTI-MACHINE SYSTEM USING

SYSTEM REDUCTION

Almoataz Y. Abdelaziz1, Amr M. Ibrahim

1, Zeinab G. Hasan

2

1Electrical Power and Machines Department, Faculty of Engineering, Ain Shams University, Cairo, EGYPT

2Electrical Power Department, Higher Institute of Engineering and Technology, Fifth Settlement, Cairo,

EGYPT

Abstract

This paper presents an approach to design power system transient stability assessment

using direct methods for a multi-machine system that uses measured values of the

currents and voltages of the three phases of two buses (equivalent to Phasor

Measurement Unit data). The multi-machine system is reduced to a single machine

infinite bus system using system reduction. The measured data is transformed from time

domain into phasor domain using Discrete Fourier Transform to predict whether the

swing is a stable or an unstable one. The performance of the method has been tested on

a simulated multi-machine system using PSCAD and MATLAB software. The

proposed scheme can be used for the detection of out-of-step condition using an

extension of the equal-area criterion.

1. INTRODUCTION

The first requirement of reliable service is to keep the synchronous

generators running in parallel and with adequate capacity to meet the

load demand. Out-of-step conditions on a power system are caused by an

attempt to transfer a given amount of power through excessive

impedance or by deficient voltage levels as a result of fault conditions,

automatic or manual circuit switching or loss of machine excitation.

Many techniques are introduced for out-of-step protection.

Conventional out-of-step distance-type relaying schemes have been used

in most utilities [1]. Another concept augmenting the measured apparent

resistance (R) with its rate of change (R) has been introduced [2].

Another out-of-step relaying concept has been presented in [3], where

the relay scheme utilizes the direct method of Lyapunov to determine

when a disturbed system phase plane trajectory leaves the post-disturbed

system region of stability.

The Time Domain Simulation (TDS) technique is the most accurate

method for assessing the power system transient stability [4, 5]. The TDS

approach can be applied to any level of detail of power system models

and gives visual information about state variables. One of the main

disadvantages of the TDS approach, except for being time-consuming, is

that it does not provide information about the stability margin of the

system [6].


Keywords: Phasor Measurement Unit (PMU) Global positioning system (GPS) Power system transient stability Discrete Fourier Transform (DFT) Equal-area criterion (EAC) Out-of- step detection Multi-machine Time Domain Simulation (TDS)

Correspondence: A. Y. Abdelaziz

Professor, Electrical Power

and Machines Department,

Faculty of Engineering,

Ain Shams University,

Cairo, EGYPT


The transient energy function method [7, 8] and extended equal-area criterion [9, 10] have also been

applied in power system transient stability assessment. However, these methods have some modeling

limitations and they still need a lot of computations to determine an index for transient stability [11].

Artificial intelligence has been also introduced in the out-of-step field. The K-means clustering pattern

recognition technique gives good results in detecting out-of-step conditions [12]. Another out-of-step

prediction approach based on neural networks has been also presented in [13].

Nowadays Phasor Measurement Units (PMUs) are capable of tracking the dynamics of an electric power

system in real time, and with modern telecommunication technologies, utilities are becoming able to

respond intelligently to an event in progress [14, 15]. By synchronized sampling of microprocessor-based

systems, phasor calculations can be placed on a common reference [16-18] to achieve Synchronized Phasor

Measurement Units (SPMUs). A new approach considering synchronized measurement data from both ends

of a transmission line to protect transmission line is presented in [19].

Synchro-phasor measurements of synchronized voltage and current are used by utilities to control and

stabilize the power network. The dependence of the machine on the position of the rotor makes it difficult

for the application of phasor measurements for stability control methods. Under transient conditions, it is not

easy to find solutions to obtain machine voltages, currents and flux linkages when expressed in phase

quantities. The time varying coefficients need to be stabilized to obtain stationary mechanical coefficients

[20, 21]. Phasor measurement units equipped with Global Positioning System (GPS) receivers and a

time-stamp device are placed at power plants to obtain power plant variables. The gathered data is then

transmitted to a central location where the data can be compared, analyzed and processed. With some local

processing power they can be used to determine the generator angles, speeds, accelerations and powers from

terminal voltages and currents [20, 22]. Prior knowledge of the system is necessary since the network

topology changes would influence proper machine identification. Lack of direct measurement of the plant

auxiliaries may result in phasor measurements not providing a real picture of rotor angles. Previously two

multi-layered feed-forward artificial neural networks have been used to estimate rotor angles and speed from

phasor measurements. This solution did not consider the lack of direct measurements as a source of

uncertainties. Selection of input variables was also not considered [23, 24]. The generator measurable

outputs with its electrical parameters have been used to estimate the state variables. The results did not use

the availability of the field voltage Efd, which provides additional insight into the internal machine flux

linkages [21].

This paper presents a modification on an existing algorithm in [18], which presents a study for power

oscillations with a laboratory model comprising a strong network, a transmission line and a generator, an

algorithm tested for a three phase short circuit fault for a single machine infinite bus system . An approach to

design power system transient stability assessment using direct methods for a multi-machine system that

uses measured values of the currents and voltages of the three phases of two buses (equivalent to PMU data)

is presented. The multi-machine system was reduced to a single machine infinite bus (SMIB) system using

system reduction. The measured data is transformed from time domain into phasor domain using Discrete

Fourier Transform (DFT) to predict whether the swing is a stable or an unstable one. The performance of the

method has been tested on a simulated multi-machine system using PSCAD and MATLAB software. The

proposed scheme can be used for the detection of out of step condition using an extension of the equal-area

criterion. A three phase fault was simulated at test system comprises 4-machine network for validating the

proposed algorithm.

2. PHASOR MEASUREMENT UNIT

Instead of using relays to detect Out-Of-Step events, new measurement systems are available where it is

possible to measure phase angles in the whole power system with the same time and angle reference. The

main device in such a system is called a phasor measurement unit, PMU. The value of data provided by

PMUs has been recognized, and installation of PMUs on power transmission networks of most major power

systems has become an important current activity.

The modern PMUs use one pulse per second signals provided by the Global positioning system (GPS)

satellite receivers. GPS system consists of 24 satellites in six orbits at an approximate altitude of 10,000

miles above the surface of the earth. The accuracy of the GPS timing pulse is better than 1μs, which for a 50

Hz system corresponds to about 0.018 degrees, this accuracy is more than enough to ensure that the

123 | P a g e A. Y. Abdelaziz, Amr M. Ibrahim, Zeinab G. Hasan

measurements obtained by such clocks will be simultaneous for the purpose of estimation and analysis of the

power system state [25]. PMUs are nowadays increasingly used to measure and monitor the state of the

power systems [26]. Successful commercialization of this technology now makes it possible to build wide

area measurements systems, which enable on-line control of power systems and implementation of new

protection schemes [27].The main advantage of PMU is that measured values have same time reference.

PMU uses GPS signals to time synchronizing and after calculating voltage and current phasors, using DFT,

PMU adds a time tag to sampled data and synchronize them with GPS signals [28].With the advancement in

technology, the micro-processor based instrumentation such as protection Relays and Disturbance Fault

Recorders (DFRs) incorporate the PMU module along with other existing functionalities as an extended

feature [29].

3. APPLICATIONS OF PMUS IN POWER SYSTEM

The synchronized phasor measurement technology is relatively new, and consequently several research

groups around the world are actively developing applications of this technology. It seems clear that many of

these applications can be conveniently grouped as follows:

3.1. Advanced network protection

This category of applications of synchronized phasor measurements is that of enhancing the effectiveness

of power system protection. This involves equipment and system protection, as well as remedial action

schemes [30].

3.2. Detection of Instability

In a power system consisting of two synchronous machines and a connecting network over which

synchronizing power can flow, the problem of instability detection can be solved in real-time. The

equal-area criterion is applicable in this case, and if the machine rotor angles and speeds can be measured in

real-time a prediction algorithm can be developed for the detection of instability [31].

4. PROBLEM FORMULATION

4.1. System

In stability assessment of multi-machine systems, the following simplifying assumptions are often made:

1. Each synchronous machine is represented by a constant internal voltage behind the transient

reactance.

2. The governor's actions may be neglected. It means that input mechanical power of turbine

generator remains constant during and after the disturbance.

3. During the transients, loads are modeled as constant admittances to ground.

By these assumptions discussed in [32] the system can be modeled using system reduction, and then the

proposed out-of-step detection algorithm can be applied. A multi-machine system was chosen for this study.

The assumption was made that voltages and current can be measured by synchronized phasor measurement

devices at the terminal of the generator. Additionally, the generator parameters were known. According to

[12], if the external bus voltage has a magnitude of V and phase θ, and , which are the components of

the bus voltage after they have been converted by Parks transformation; , can be calculated by:

(

) (

)

(1)

The rotor angle δ can then be computed by:

(2)

And be used in the swing equations to calculate the acceleration power of machines [33].

4.2. Equal Area Criterion

When there is a loss of synchronism in an interconnected system, the areas must be separated at


predetermined locations to maintain load generation balance, avoid equipment damage and power blackouts.

The Out-of-Step Trip function differentiates between stable and unstable power swings and initiate system

area separation at the predetermined network locations to maintain power system stability [34]. The

equal-area criterion can be used to calculate the maximum fault clearing time before the generator loses

synchronism. The equal-area criterion integrates the energy gained when the turbine-generator is

accelerating, during the fault (area A1, in Figure 1) and compares that area with the decelerating area, (area

A2, in Figure1) when the generator exports the energy stored during the fault.

Fig. 1. Equal-area criterion with an acceleration area 1A and a decelerating area 2A

Area 1A represents the total kinetic energy gained during the acceleration period. As soon as the fault is

cleared at angle δc the angle will continue to increase and the kinetic energy gained during the fault period

will expand into the power system, when area 2A is equal to area 1A angle δ has reached its maximum

value [18, 35].

The area under the power-angle curve can be calculated by:

dPPA

D

c

o

)sin(1max

0

(3)

dPPA

P

P

c

)sin(2 0max

(4)

where

D= during fault

P= post fault

When area 1A < 2A the system will be stable and if 1A > 2A the system will be unstable.

For multi-machine system, we will reduce it to two machines system and then converted into an equivalent

single machine system. We will be able to use out-of-step detection algorithm in [36].

4.2.1. Combining Machines

It is easier to study the stability of a network with fewer synchronous machines than the one with many.

The number of machines may be reduced in a network by combining several machines which swing together

or almost together to form a single equivalent machine [37]. The inertia constant of the equivalent machine

can be calculated by summing the inertia of the individual machines. The machine which swing together

were combined together to form one group and the other machines another group. The network was reduced

to a two machine system. The two machine network was further reduced to a single finite machine and an

infinite bus. The equivalent inertia constant, delta and electric power were computed.

4.2.2. Single Machine Equivalent

The system having two finite machines is replaced by an equivalent system having one finite machine

and an infinite bus, so that the swing equations and swing curves of angular displacement between the two

machines are the same for both systems. The equivalent inertia constant is a function of the inertia constant

of the two actual machines. The equivalent input and output are functions of the inertia constants, inputs and

outputs of the two actual machines.


The area under the power-delta curve, assuming that the pre-fault and post-fault network conditions are

similar, can be calculated from the swing equation, with a three phase fault as follows:

(5)

where B is one group of machines that swing together and C represents another group.

(6)

where is the electrical power.

(7)

2

2

dt

dMPa

(8)

ea PPP 0 (9)

where Pa is the accelerating power and P0 is the mechanical power.

4.2.3. Assessing Stability

The ability of power system to survive the transition following a large disturbance and reach an

acceptable operating condition is called transient stability [38]. The physical phenomenon following a large

disturbance can be described as follows. Any disturbance in the system will cause the imbalance between

the mechanical power input to the generator and electrical power output of the generator to be affected. As a

result, some of the generators will tend to speed up and some will tend to slow down. If, for a particular

generator, this tendency is too great, it will no longer remain in synchronism with the rest of the system and

will be automatically disconnected from the system. This phenomenon is referred to as a generator going out

of step [38].Transient stability studies are needed to ensure that the system can withstand the transient

condition following a major disturbance [39]. A single small machine connected to a very large power

system behaves as if it is connected to an infinite bus. The infinite bus is regarded as a zero impedance and

infinite inertia not affected by the amount of current drawn from it and is a source of constant voltage (both

in phase and magnitude) and frequency [40]. It has a voltage and an angle that is constant under all

conditions and it can absorb infinite power.

4.2.4. Out of Step Detection Algorithm

Figure 2 shows a flow chart for the proposed out-of-step detection algorithm. First the algorithm takes

data from the EMTDC/PSCAD program at different time steps which is the same as the sample interval for

the PMU, 0.02 seconds. This data will be converted by a DFT to complex phasors of voltages and currents.

The algorithm takes complex current and voltage. From these vectors it calculates new vectors with

impedance, phase angle and power for all time steps. After that the program determines the areas 1A , 2A

and finally checks if there is out-of-step condition or not, this may be considered as an extension for

out-of-step detection algorithm used [36].

Explanation of the steps of the algorithm is as follows:

1- The multi-machine system will be converted to its equivalent and then simulated in PSCAD/EMTDC

program.

2- The data taken from PSCAD/EMTDC (equivalent to PMU data) will be saved in a MATLAB program.

These data will be transformed from time domain to phasor domain by DFT.

3- At t=0, first line of data, it is assumed to have a stable values (stable angle and mechanical input power

are calculated).

4- Angle and power are calculated at each time step Δt = 0.02 sec.

5- IF statement for change in angle.

A difference larger than the threshold value will operate the power swing algorithm, the threshold value is


taken from studying the graphs of the change of phase angle.

6- IF statement for change in angle and value of electric power output.

If the angle has changed too much and the electric power output has decreased to a level below the

mechanical power input, the system will experience a power swing, and the algorithm will calculate area A

and area B. If these changes in angle and electric power output don’t occur, the algorithm tells that there will

be a disruption but the system will stay synchronized.

7- Warning message that the system has had a failure but will not lose synchronism.

8- Calculation of areas A and B.

9- IF statement to compare between areas A and B.

As long as area A is smaller than area B, the algorithm will continue, and if area A is larger than area B, the

algorithm will stop and sends out a warning Out of Step condition.

10- A warning message, the system will lose synchronism (Out of Step condition).

Fig. 2. Flowchart of Algorithm

Convert the multi-machine system

to its equivalent after applying

system reduction

No

No

Yes

Yes

Data from EMTDC program is read

into MATLAB program

If |angle (n)-angle (n+1)| ‹

Threshold value (0.1)

At t=0, initial angle and mechanical

input power are calculated

Angle and power are calculated at

each time-step

If angle (n) >

initial angle

&Pm (n) ≤ Pe

Print: system has a

failure but will stay

synchronized

Calculate area A and B

If area A1 > area A2

Print: OUT-OF-STEP

Yes

No


5. MODELIG AND SIMULATION

The proposed algorithm will be tested on 4-machine network used in [33]; system configuration is shown in

Figure 3. The four machine system was reduced to form a two machine system by combining the machines that

swing together, that is, G1+G2 and G3+G4 based on the swing curves in Figure 4. The two machine network

was further reduced into SMIB. The inertia constant, delta and the electrical power were calculated according

to equations (6), (7) and (8) respectively. The resulting SMIB is used in PSCAD program. The voltages and

currents measurements at the generator and at the infinite bus are the two required readings to operate the

algorithm. The system is simulated under several fault duration for three phase short circuit fault.

Fig. 3. Four machine system

Fig. 4. Rotor angle movement for the 4 generators


5.1. Case 1: 3-phase short circuit using frequency-dependent model

Time of fault: 0.1 sec.

Duration of fault: 0.4sec.

Transmission line: frequency-dependent model.

Figures 5, 6, 7 and 8 show voltage and current waveforms at both sides (generator bus and infinite bus)

obtained from the simulation using the PSCAD/EMTDC program.

Fig. 5. Voltage of infinite bus

Fig. 6. Voltage of generator

0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65-1500

-1000

-500

0

500

1000

1500Voltage versus time

time [sec]

Infinite b

us v

oltage [

kv]

0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65-400

-300

-200

-100

0

100

200

300

400Voltage versus time

time [sec]

genera

tor

voltage [

kv]


Fig. 7. Current of infinite bus

Fig. 8. Current of generator

The proposed scheme is tested by calculating areas A1 and A2 for this fault and determines that the

generator will be out of step (unstable condition), this fault is tested by TDS and determines instability of the

system as shown in Figure 9.

Fig. 9. Rotor angle against time for an unstable case

0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65-2

-1.5

-1

-0.5

0

0.5

1

1.5x 10

-13 Current versus time

time [sec]

Infinite b

us c

urr

ent

[A]

0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65-3

-2

-1

0

1

2

3

4

5

6Current versus time

time [sec]

genera

tor

curr

ent

[A]

0 0.1 0.2 0.3 0.4 0.50

200

400

600

800

1000

1200

1400

1600

1800

2000Time versus angle

time [s]

angle

[degre

es]


5.2. Scheme Responses to Different Faults

The proposed algorithm is tested for detecting the system stability. The program output to number of

faults at different time durations is shown in Table 1.

Table 1. Test results of the proposed algorithm to number of faults at different time durations

Fault type Time of applying fault

(tf)

Duration of

fault (Df)

Proposed

Algorithm Output

Time Domain

Simulation

Result in Ref.

[33]

ABCG 0.1 0.1 Stable Stable Stable




ABCG 0.1 0.3 Unstable Unstable Unstable



It is concluded from Table 1 that duration of fault is directly related to the angle difference between the

generator and infinite bus (δ) which will affect the accelerating and decelerating area affecting the stability

of the system. When Df increases for the same tf the system will tend to be unstable. All cases are compared

by TDS and give identical results. This is the same for single machine infinite bus system discussed in [36].

6. CONCLUSIONS

This paper presents an approach to design power system transient stability assessment using direct methods

for a multi-machine system which uses measured values of the currents and voltages of the three phases of

two buses (equivalent to PMU data) to detect the out-of-step condition accurately. The multi-machine

system was reduced to a single machine infinite bus (SMIB) system using system reduction. The Discrete

Fourier Transform is used to transform the sampled data in phasor domain which is equivalent to PMU

readings. The EAC is used and proved that it is an efficient method for determining the transient stability of

a power system and detecting the out of step condition for multi-machine system as one machine against

infinite bus or two machine systems. Test results show that the proposed algorithm is able to detect transient

stability on a multi-machine system with a temporary fault, through PMU measurements and generator

parameters for different durations. It would be interesting to make simulations on larger networks that

include more generators and machines and to find possible nodes to implement PMUs.

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Please cite this article as: A. Y. Abdelaziz, Amr M. Ibrahim, Zeinab G. Hasan, (2013), Phasor Measurement Units For Out-Of-Step Detection of A

Multi-Machine System Using System Reduction, Science and Engineering, Vol. 1(2), 121-132

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http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=5707362

Online available since 2013/Apr/27 at www.oricpub.com

© (2013) Copyright ORIC Publications


Vol. 1 (2), 2013, 133-142


ORICPublications www.oricpub.com




DEVELOPMENT OF A MICROCONTROLLER BASED ALARM

SYSTEM FOR PIPELINE VANDALS DETECTION

O. Shoewu 1, L. A Akinyemi

1, Kola A. Ayanlowo

2, Segun O. Olatinwo

2,3 , N. T. Makanjuola

1

1 Department of Electronic and Computer Engineering, Lagos State University, Epe Campus, Nigeria.

2 Department of Computer Science, Moshood Abiola Polytechnic, Abeokuta, Nigeria.

3 Department of Computer Science and Engineering, Ladoke Akintola University of Technology, Ogbomoso, Nigeria.

Abstract

This paper focuses on the design of a microcontroller based alarm system for pipeline

vandals detection. In this paper, a robust advance and fast mechanism of pipeline detection

was adopted for the system design. The design was in modular forms i.e. communication

system (transceiver), microcontroller, power system, simulation of system and all modules

were tested individually and the whole system was tested to perform the required task of

detecting any leakage when the rubber on the pipes is removed which quickly triggers the

microcontroller and thereby alerts the personnel for necessary actions to be taken.

1. INTRODUCTION

Acts of pipeline vandalism in onshore operations of major

multinational oil prospecting and producing companies, like SPDC and

Chevron have been a major challenge in recent times. The companies

affected took several steps in the past to address this problem; however,

these efforts were not very successful. Hence, the need to design, develop

and install a system that will adequately monitor and report acts of

vandalism and their location for ease of remediation has become necessary;

this is the focus of this work. The existing practice is that all crude and gas

transporting lines are either laid on land surface, buried at a depth of 1.3m

on land or 3m across creek waters. This however, has failed to stop the

vandals from carrying out their nefarious activities, by digging through the

right-of-ways (ROW) of pipelines and damaging them. Scada monitors that

report condition of lines were strategically installed; but the vandals

discovered a way of demobilizing them prior to carrying out their

operations. They simply destroyed these monitors or removed the power

packs because they were installed externally. Fencing of strategic valves

and lines across creeks to limit accessibility of pipeline vandals also failed

as they simply used oxyacetylene flames to cut through the fence and gain

access to the assets. This became more pronounced because there is no

continuous manning or surveillance of the lines. The companies also

introduced the Pipelines and flow lines surveillance program; this approach

was based on the understanding that utilizing community constructive

engagement approach and partnership will stem the acts of vandalism.

Received: 02 Apr 2013

Accepted: 11 Apr 2013

Keywords:

Transceiver

Pipelines

Vandals

Microcontroller

Alarm System and Sensors

Correspondence:

Segun O. Olatinwo

Department of Computer

Engineering, Moshood Abiola

Polytechnic, Abeokuta, Nigeria.

Department of Computer Science

and Engineering, Ladoke Akintola


Ogbomoso, Nigeria.


Eight youths were hired from each host community to watch over the company assets within their

locality. Incentives were introduced as rewards at end of year. This system also failed as some of the “bad

eggs” within the groups diverted logistics resources provided to enhance their operation to other uses and

even aided and abetted the acts of vandalism that were being perpetrated.The Federal Government

introduced the Joint task force (JTF) operations, in a bid to curtail the illegal activities of vandals. The

presence of this military outfit worsened the security situation, oil workers, expatriates and their family

became targets of kidnapping for a ransom fee. In an attempt to dislodge these vandals, their activities

gradually snowballed into more criminal acts and several oil workers lost their lives and properties worth

millions of dollars have been lost to their nefarious activities. The new invention, having weighed all

previous options, aims at developing a simple mechatronics system that is capable of performing a spying

function around pipelines at strategic locations where acts of vandalism have been prevalent. The new

system would be capable of collecting and transmitting information to a processing unit via wireless signals.

It would also have the capacity to decode the exact location(s) where vandalism is taking place. This

approach has become an attractive option to pursue, due to the concealed and secret nature of its installation

and operation. What this means is that access to it will be highly limited. Additionally, the device is capable

of sensing light, pressure drops and mechanical breaks in the line as long as there is power supply to the

component units of the system. The device can also be adapted to perform other desired functions as needed

including sounding an audible alarm and shutting down fluid flows automatically. In addition, the device is

compact and concealed in such a way that the vandals cannot easily destroy it. This work is based on the

onshore operations in the oil and gas industry.

1.1 Theory of the System

Several regulations both local and international have been put in place to govern the smooth operation

of the oil and gas industry; in Nigeria for instance, some of these are listed as Oil Pipelines Act, 1965;

Mineral oil (safety) regulations, 1997;Petroleum regulations, 1967; Petroleum Drilling and Production

regulations, 1969; Oil in navigable water Act, 1968; Oil Terminal Dues Act, 1969; Petroleum refining

Regulations, 1974; Federal Environmental Regulations, 1974; Federal Environmental Protection Agency

Act, 1990; National Oil Spill Detection and Response Agency Act, 2006. Ministry of Niger Delta.Acts of

pipeline vandalism attribute to the frequent pipeline fires, accompanying loss of lives and lost profit

opportunities (LPO). According to Johnson (2004) pipeline explosions have killed hundreds of looters,

bystanders and innocent residents. The most recent of these explosions happened at Ilado, Lagos on May,

2006; more than 200 people were incinerated in the pipeline fire that enveloped the area (Balogun et al

2006). Several deaths recorded from pipeline fires in recent times are a few of the horrendous effects of

crude oil theft from oil transport lines, which are a leading cause of oil spills, environmental degradation and

ecological destruction in Nigeria today. Oil spills through pipeline vandalism by idle youths in Nigeria

reached alarming peaks in the last few decades. Poor implementation of memoranda of understanding

(M.O.U) between oil companies and host communities, lack of employment and dilapidating environmental

conditions have all been blamed for this rising trend. (Uwhejevwe-Togbolo 2005). Ojediran and Ndibe

(2005) reported that an average of 35,000 barrels of crude oil is stolen per day in circumstances that threaten

lives, the environment and the ecosystem in general. Apart from the loss of lives and property through

pipeline fires, the long time ecological effects on impacted sites usually degrade the quality of fresh water

sources which serve the domestic water supply needs of most the host communities. Marine creatures are

not spared and increases in water borne diseases are visibly noticeable. The enormous numbers of oil

installations in the Niger Delta region explain their vulnerability to vandalism. Presently, the Niger Delta

region plays host to over 600 oil fields of which 360 fields are onshore while 240 are offshore with over

3000 kilometres of pipelines crisscrossing the region and linking some 275 flow stations to various tank

farms which concurrently serve as export terminals. It is pertinent therefore to note that oil spills resulting

from pipeline vandalism constitute a major challenge to emergency management efforts, despite the

contingency arrangements in place by industry operators. Table1 below shows that for the period 1995-

2005, Shell Petroleum Development Company recorded a total of 2944 oil spill incidents. The data reveals a

noticeable increase from 235 oil spill incidents in 1995 to 330 in 2000. The least number of 224 oil spill

incidents was observed in 2005.

135 | P a g e O. Shoewu , L. A Akinyemi , Kola A. Ayanlowo , Segun O. Olatinwo , N. T. Makanjuola

Table 1. Oil spill data: SPDC1995 -2005

Source: SNAR, 2005.

Below are some pictures showing deliberate acts of vandalism.

Fig. 1 Burning AGGE Manifold North Bank March 2006 Fig. 2 Fire incident at Fusokiri December2000

Fig. 3 Illegal bunkering at Eteo

It is near impossibility to deploy a workforce that will monitor these assets physically on a 24/7 hour

basis considering the fact that we have over 3000km length of pipe network criss-crossing this region. A

better approach will be to use an automated system capable of monitoring activities and alerting a control

station of any act of vandalism.

According to Ajiboye O.E et al (May 2009), in their paper titled “poverty, Niger Delta and the youth

response”, the general impoverishment of the host communities can be linked to the years of perennial

neglect and abuse of the environment. Major operators do not have recognisable reclamation or remediation

programme in place after major oil spills occur. The situation is worsened by a visible show of apathy to the

fate of the environment by successive governments. While the drive is towards increasing the petro-dollars

the country gets from oil, sadly enough, there is no corresponding passion directed towards ensuring

ecological sustainability. This is evident in the way successive administrations have been shifting the

dateline on gas flaring stoppage in oil field operations in Nigeria. The absence of a strong political will and

YEAR NUMBER OF SPILLS VOLUME IN BARRELS (bbl)

1995 235 31,000 1996 326 39,000 1997 240 80,000 1998 248 50,000 1999 320 20,000 2000 330 30,000 2001 302 76,960 2002 262 19,980 2003 221 9,916 2004 236 8,317 2005 224 11,921

TOTAL 2944 377,194


alignment by the legislature and executive has worsened the hope for entrenching an environmentally

friendly legal system that would protect the ecosystem.

2. MATERIALS AND METHODS

2.1 Component Design – Communication The design of this device is governed by the principle of radio frequency modulation and de-

modulation. Through this means communication is established. Messages are sent from one point to another

within the range of the radio frequency coverage. A radio wave travels through the atmosphere or space at

the speed of light (3x108 meters/second). If a radio wave strikes another antenna, a high-frequency current

will be induced that is a replica of the current flowing in the transmitting antenna. Thus, it is possible to

transfer high-frequency electrical energy from one point to another without using cables. The energy in the

receiving antenna is typically only a fraction of the energy delivered to the transmitting antenna. The

transceiver is capable of transmitting and receiving signals across a space in this form. The transceiver unit

has a transmitter with a receiver incorporated in it.

Modulation is the process through which a radio wave transmits information to different points. A radio

frequency can be modulated in various forms. For example, it can be amplitude modulated (AM) or

frequency modulated (FM).

2.1.1 The amplitude modulator

In amplitude modulation, the intelligence or information controls the amplitude of the radio frequency

(RF) signal. It also transmits voice, music, data, or even multimedia information (video). In amplitude

modulation, the RF signal amplitude varies in accordance with the audio frequency (AF) signal. The RF

signal could just as well be amplitude-modulated by a video signal or digital (on-off) data. The figure below

shows a typical circuit for an amplitude modulator.

INFORMATION OUTANTENNA

C1

T1

C2

RL

(CARRIER+SIDEBANDS)

RERB2

RB1

C3

C4

Vcc

AM SIGNAL INPUT

+V

+

+

PNP+

+

Fig. 4 The amplitude modulator circuit

2.1.2 The frequency modulator

Frequency modulation (FM) is an alternative to amplitude modulation (AM). Frequency modulation has

some advantages that make it attractive for some commercial broadcasting and two way radio traffic. One

problem with AM is its sensitivity to noise. Lightning, automotive ignition, and sparking electric circuits all

produce radio interference. This interference is spread over a wide frequency range. It is not easy to prevent

such interference from reaching the detector in an AM receiver. An FM receiver can be made to be

insensitive to noise interference. This noise free performance is highly desirable. The principle of frequency

modulation can be explained using the figure below.

R1

R2

C1

D1

R3

C3

C5

C4R4

C6

RFC1

L1

RFC2

Q1

C7

C2

SIGNAL

INPUT

FM OUTPUT

Vcc

+V

+

+

+

++

++

Fig. 5 The Frequency modulation circuit


Transistor Q1 and its associate parts make up a series tuned oscillator. Capacitor C3 and coil L1 have

the greatest effect in determining the frequency of oscillation. Diode D1 is a varicap diode. It is connected in

parallel with C3. This means that as the capacitance of D1 changes, so will the resonant frequency of the

tank circuit. Resistors R1 and R2 form a voltage divider to bias the varicap diode. Some positive voltage is

applied to the cathode of D1. Thus, D1 is in reverse bias. A varicap diode uses its depletion region as the

dielectric. More reverse bias means a wider depletion region and less capacitance. Therefore, as a signal

goes positive, D1 will reduce in capacitance. This will shift the frequency of the oscillator up. A negative-

going signal will reduce the reverse bias across the diode. This will increase the capacitance and shift the

oscillator to some lower frequency. The signal is modulating the frequency of the oscillator. The amplitude

of the modulated frequency is constant. Demodulation is the means by which modulated signals are

recovered. Demodulators are called radio receivers. An AM radio receiver must recover the information

from the modulated signal. This process reverses what happened in the modulator section of the transmitter.

This process is also called detection. A diode and a transistor can be used for AM detection.

The circuit below shall be used to explain the principle of AM detection.

INFORMATION OUTANTENNA

C1

T1

C2

RL

(CARRIER+SIDEBANDS)

RERB2

RB1

C3

C4

Vcc

AM SIGNAL INPUT

+V

+

+

PNP+

+

Fig. 6 The amplitude detection circuit

The circuit shown is a common emitter amplifier. Transistor T1 and capacitor C1 form a resonant

circuit to pass the modulated signal (carrier plus sidebands). Capacitor C4 is added to give a low pass filter

action, since the high-frequency carrier and the sidebands are no longer needed after detection. Bi-polar

Junction transistor (BJT) can demodulate signals because they are also nonlinear devices. The base-emitter

junction is a diode. The transistor detector has the advantage of producing gain. This means that the circuit

will produce more information amplitude than the simple diode detector. Detection of FM signal is more

complicated than for AM. Since FM contains several sidebands above and below the carrier, a simple

nonlinear detector will not demodulate the signal. A double- tuned discriminator circuit is required. The

discriminator works by having two resonant points. One is above the carrier frequency, and one is below the

carrier frequency. There are many other FM detector circuits. Some of the more popular ones are the

quadrature detector, the phase-locked-loop detector, and phase-width detector. These circuits are used with

integrated circuits.In the design of this device, the transceiver operates at a frequency of 900MHz. This is

the operating frequency of a GSM phone. The transceiver is a modified GSM phone. Through it a wireless

information exchange can be achieved. The mode of communication here is similar to that of FM but it is

not a broadcast.GSM (Global System for Mobil communication) is a standard wireless communication

system. Its commercial service began in 1991, at the beginning of 1994; there were about 1.3 million

subscribers in the world. GSM is the dominant communication standard in the world today, communication-

base stations are not needed to be set up. The most fundamental service supported by GSM was wireless

phone. Since 2001 this service has been available to us in Nigeria. The potential of the GSM service is

beyond what is known in the country. The system can be adopted to serve designs such as the pipeline

vandalism alert. A GSM system has wide coverage area; the extent of coverage is determined by the

availability of repeating stations to boost the strength of the signal. Wherever there is a GSM signal, a GSM

device like a mobile phone can be reached from any place in the world. In the same vain it can reach any

where, too. This means of communication requires no cable. Space satellites are used to relay signals from

one continent to another or from one very remote place to another. The transceiver which is a GSM device is

a modified Nokia 1100 phone. It is hosted on a network through a SIM module. Every SIM module has an

identification number. Through this identification number it can send and receive data on the local and

global GSM network.


2.2 Component Design – Sensors.

The device operates through the use of sensors, which sense a variation in stable operating conditions of

pressure, break or light.

2.2.1 The pressure sensor

Fig. 7 The pressure sensor

The Operation of the Pressure Sensor

The pressure sensor is designed with a normally closed push switch connected in series with a resistor

R1. The output voltage (Vo) at the junction of these two components depends on the state of the switch.

When the switch is not depressed, the contacts are closed. Hence, Vo is 0V. This is the state of the sensor

when the joint of two pipes is opened. When this joint is closed, the switch is in the open contact state, and

the value of Vo is 5V.

The resistor R1 is a pull-up resistor. Its value is determined with respect to the maximum current

sinkable by the microcontroller. The microcontroller can sink a maximum current of 25mA. To reduce the

current drain on the power supply port Ao of the microcontroller is made to sink 0.5mA. Therefore, the

value of R1 is obtained by this equation:

V= IR, R=V/I, R=5/0.5X10-3

, R1=10K

2.2.2 The light sensor

OPTICAL FIBER

50K

TO MICROCONTROLLER

PHOTO

RESISTOR

R2

Q1

R3

+V5V

100mA

NPN

10k

Fig 8. The light sensor Fig. 9 The light sensor circuit

The Operation of the Light Sensor

This senses light around the pipe line whenever there is an opening along the pipe. This sensor is a

network of optical fibres and a photo resistor. The optical fibres are to receive and transmit light from source

to the photo resistor. The light sensor is covered with a black rubber to cut out light from the optical fibres.

The optical fibres are laid along the pipe so as to provide proper coverage in a zigzag form. When the rubber

insulation is removed during vandalism, the optical fibres pick up light rays which are transmitted to the

surface of the photo resistor. The photo resistor converts light signals into electrical signals which are sent to

the microcontroller for processing. The optical fibres are channels for transferring light from source to a

point of use. It is used in this project to pick up light and focus it on the surface of a photo resistor. The

photo resistor and the variable resistor R2 convert the light energy to electrical signal. The electrical signal is

then converted to digital signal by the transistor before it gets to the microcontroller. The essence of this

sensor is to detect the presence of light. This will happen when the black rubber sheet covering the pipe is

removed during vandalism. During installation of this sensor, the optical fibres are laid concurrently as

shown below. This pattern of distribution of fibre optics is to enable coverage of the surface of the pipe. The

photo resistor and the 50K variable resistor convert the light energy on the surface of the photo resistor to

electrical energy. The sensitivity of this sensor is determined by the resistance of the variable resistor (R2).

The higher its value the more the sensitivity and light sensor, and vice versa. The output of this connection is


digitalized by the transistor Q1. The transistor is used as a switch in this mode; and the resistor R3 is to limit

the current to the microcontroller to 0.5mA.

2.2.3 The break sensor

R4-R11

B1

B2

B3

B4

B5

B6

B7

B0

10K

PIPE

OPTICAL FIBER

TO MICROCONTROLLER

+V5V

Fig. 10 The break sensor Fig. 11 The break sensor circuit

The Operation of The Break Sensor This is a network of thin coils connected to the ports of the microcontroller and to the body of the pipe

at the other end. These coils are wrapped around the pipe in a thread like fashion to provide surface cover of

the pipe. When any of these tiny coils is broken, a signal is sent to the microcontroller for interpretation.

These coils are concealed using black rubber insulation over the pipe. This rubber wrapping also protects the

sensors from adverse environmental conditions.

2.3 Component Design – Microcontroller

This is the brain of the system. It is the component responsible for interpretation of signals received

from the various sensors. It is also responsible for information transmission between the system and the base

station unit. This means that it directly controls the functions of the transceiver. The microcontroller in this

system performs the same functions a processor does to a computer system; it governs its operations. The

microcontroller selected for this function is the PIC16F 628A, a product of Microchips. The Functions of the

microcontroller-16F628A include: To turn on the system automatically when power is connected, To

interpret signals, To send an alert signal to the base station, To clear the transceiver’s screen and To relay

audio signals around the pipe to the base station.

2.3.1 The transceiver

This module is capable of sending and receiving signals via wireless communication. The transceiver is

a very important part of the system, and its mode of operation is better explained by the operation of radio

signal transmitter and receiver. The transceiver module transmits and receives signals at a certain frequency.

2.4 Component Design – Power System

6V

220/12

VAC

TO THE DEVICE

CHARGER

POWER SUPPLY 6v,3A

BACK-UP BATTERY

C1

F1S1

T1

C2

REGULATOR

Q2

D1

D2

D4

D3

5.4V

R12

R13

UTILITY

SUPPLY

+6V

NPN

MMSZ7V5T1

IN

COM

OUT

78L06

+

BRIDGE

10TO1

50.0Hz

-220/220V

Fig.12 The power supply


Fig.13 The power circuit

Light sensor Break sensor

Pressure sensor

Fig.14 The block diagram of the design of a microcontroller based alarm system for pipeline vandals detection

This is the part that supplies the energy that keeps the device active and running. It has a main power

supply which is sourced from utility supply (PHCN), and a back-up power supply which is sourced from a

battery. Its power consumption is low, 3Watts maximum. The reason for dual power supply is to keep the

device active even when main power supply fails due to erratic power.

Algorithm of the design

1. stand by the alarm system

2. Monitor the pipeline

3. If there is break

4. Send the break signal or light signal to microcontroller

5. Microcontroller

6. If yes, alert the personnel

7. If No, go to step (2)

JOINT SENSOR

LIGHT

SENSOR

BREAK SENSOR(WEB)

CLRDIAL ON

C181 5

C181 5 C181 5C181 5

ON/OFF

TRANSCEIVER

MICRCONTROLLER

BATTERY

PIC 16F628

NPN

+

8V

y4

y3

y2

y1

x4x1x2x3

C D E F

8 9 A B

4 5 6 7

0 1 2 3

NPN

+

470uF

IN

COM

OUT

78L05

22uF22uF

4.000MHZ

NPNNPNNPN

10k

10k

10k

47

10k10k

390390390

Microcontr-

oller Power

supply

Transceiver

Base

station


Fig. 15 Flow Chart of the design of a Microcontroller based alarm system for Pipeline Vandals Detection

3. SYSTEM SIMULATION

3.1 Computer Simulation of the Alarm System

Under normal operating conditions (when there is no pressure drop, break or exposure of optical fibres

to light rays), the digital signal to the microcontroller is 00000000. The zeros are eight because the sensor is

an eight bit system. Whenever the microcontroller senses a different digital input, it reads it as a break in one

of the coils which also means a break in the pipe. The 10K resistors are to limit the maximum current into

the microcontroller to 0.5mA.All the signals from the sensors are received and processed by the

microcontroller. The processing of the signals is controlled by a written program that is downloaded into the

controller. These operations of these sensors can best be explained using the control program.

3.2 Simulation of the Pressure Sensors This can be done by pulling two pipe connections apart. The pressure switch loses contact and sends a

signal for the transceiver to alert the receiving phone. This receiving phone stores the number of each SIM,

on a module, with the pipe number. With this the exact location of the alerting module can be known. The

phone is programmed to alert thrice to compensate for bad network scenarios.

3.3 Simulation of Light Sensors

The light sensors at normal operating condition should be kept in the dark. This condition will not cause

any alert signal to be sent. When the light sensors are exposed to light by removing the protective cladding

over the pipe, an alert signal is sent to the control station. The call rings three times. This means that while

the vandals are trying to get to the pipe by removing the covering over it, the control station gets alerted of

their activity.

3.4 Simulation of the Break Sensors

These sensors can be tested by drilling a hole into the pipe using a hand drilling machine. The drill bit

cuts break sensors, and as a result the alert signal rings three times. This means that when the vandals are


trying to bore a hole into the oil pipe, one or more break sensors will be broken by their activity and the

control station would be alerted.

The Audio Spying Function: In order to listen to the conversation of the vandals or their activities, the

transceiver can be called from the control station by dialling its SIM card number .When this is done, voices

around the sensor station can be heard. The spy operation does not reduce the credit balance of the module

transceiver. It is the caller that is charged. This operation could be repeated several times and the same

results will be obtained. This confirms the consistency and proper functionality of the device.

4. TESTING AND RESULTS

The various tests were carried out on the different modules and striking results were obtained for

different circuit diagrams.

5. CONCLUSION

The various ways of designing of security gadgets from analog to digital circuit was used in this paper.

However, various components were designed and tested to ensure it did meet the specification of the users

by warding off or alerting the personnel when things go wrong in the pipelines.

REFERENCES

[1] Abubakar, S. (2006). Pipeline vandalism caused fuel shortages at northern depots. Weekly Trust

(Abuja), 7–13 October

[2] Abdulkadir, B. M (2009). NSCDC Urges Security Networking Against Vandalism [online]. Available at

www.guardian.co.uk [accessed 6 August 2009]

[3] Adeniyi, O. (2007). Playing with fire (1). Thisday (Lagos), 18 January.

[4] Ahmed, O. S. (2007). Nigeria, oil terrorism and pipeline safety [online]. Available at guardian.co.uk

[accessed 23 October 2006].

[5] Akintola, T. (2006). Pipeline vandalism and oil scooping in the Niger Delta and Others [online].

Available at vanguardngr.com [accessed 21 October 2006].

[6] Ali, A. (2006). Pipeline sabotage in Nigeria and oil pollution damage out of context [online]. Available

at ipec.utulsa.edu/conf/2008/…/Eyo_Essien [accessed 21 October 2006].

[7] Alimeka, C. (2001). Poverty, social exclusion and social dislocation in Nigeria. Paper presented at the

National Conference on Law and Poverty in Nigeria, Kaduna.

[8] Amanze-Nwachukwu, C. and Ogbu, A. (2007). Kupolokun cries over pipeline vandalism. Thisday

(Lagos), 15 January.

[9] Brume, F. (2006). Oil pipeline vandalism in the Niger Delta: the way out [online]. Available at

guardian.uk.co [accessed 21 October 2006].

[10]Helen, Y. (2007). Sharpening the strategic focus of livelihoods programming in the Darfur region. A

report at the Darfur Peace conference.

[11]Lex de Waal, (2007). War in Darfur and the search for peace. Cambridge press.

[12]Manze-Nwachukwu, C. (2007). Boxing Day tragedy: it is time for solution. Thisday (Lagos), 2 January.

[13]Nelles, W. (2003). Comparative education, terrorism and human security: from critical pedagogy to

peace building. New York: Palgrave Macmillan.

[14]Nelson-Smith (1973). Oil pollution and marine ecology. Cambridge press.

[15]United Nations Development Programme (UNDP) 1994. Human Development Report. New York:

Oxford University Press.

[16]Victor, A. Y. (2009). NNPC, Police Connive With Pipeline Vandals – Nupeng. Available at

www.guardian.co.uk

[17]Wall Street Journal (2008). Pipeline vandalism, Hillsborough, U.S.

[18]White, J. (1998). Who is responsible for the oil explosion in Nigeria [online]. Available at

www.guardian.co.uk [accessed 21 October 2006].

Please cite this article as: O. Shoewu , L. A Akinyemi , Kola A. Ayanlowo , Segun O. Olatinwo , N. T. Makanjuola, (2013), Development Of A

Microcontroller Based Alarm System For Pipeline Vandals Detection, Journal of Science and Engineering, Vol. 1(2), 133-142.

Online available since 2013/May/03 at www.oricpub.com



Vol. 1 (2), 2013, 143-154






PILOT STUDY FOR QUANTIFICATION OF EMISSIONS OF

GREEN HOUSE GAS FOR MARINE TRANSPORTATION

DECISION SUPPORT

O. S. Oladokun1, B. Michel

2, N. Stark

2, H. Azman

3, A.S.A.Kader

4

1Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Malaysia

2Universiti Technology Malaysia, 21030, Kuala Lumpur, Malaysia

3Jeppesse, GmBH

4H. Azman, Lloyd Register

Abstract

The shipping industry is responsible for the carriage of 90% of world trade. Thus, it remains

the most energy efficient mode of transport. Shipping is expected to have greater impact on

global warming considering size of vessel plying the world ocean. The Green House Gas

(GHG) emissions are the main air pollutants in maritime transportation. In 2007, CO₂ emission from the shipping amounted to 847 million tones or about 2.7% of global CO₂ emission and it is expected to reach 18% in 2050. In July 2009, Marine Environment

Protection Committee (MEPC) approved to circulate interim guidelines on the method of

calculation of Energy Efficiency Design Index (EEDI) to create stronger incentives for

further improvements in ship’s fuel consumption, resulting CO₂ emissions on a capacity

basis. This paper present outcome of GHG emission data collection and quantification from

ship, the study hope to contribute to regulation for reduction of GHG emission in shipping

industry and subsequent mitigation of climate change. Equipment used to measure the

concentration of gas and total suspended particulate in the atmosphere are MiniVol Portable

Air Sampler, Graywolf Direct Sense Monitoring Kit, TSI IAQ-Calc and Gas Detector

IQ-1000. The equipment’s are used to determine the gas concentration, nitrogen dioxide

(NO₂), sulphur dioxide (SO₂) and carbon dioxide (CO₂) concentration respectively. Carbon

dioxide (CO₂) is the most important anthropogenic GHG. The experimental data analysis is

used to validate recommended EEDI calculation.

1. INTRODUCTION

Air pollution is the on demand case as it has been debated all over the world.

The sources of air pollution vary, starting from the individual pollutants to the

huge industry activities. Maritime industry is responsible for part of Green

House Gas Emission pollution, since there are many types of maritime

transports sailing and maneuvering at the sea. The Green House Gas (GHG)

emissions from maritime transport must be reduced because it is expected to

increase if no mitigations are taken. This paper discusses the result of exhaust

emission quantification for University Malaysia of Terengganu (UMT) vessel

(Discovery II).

The experiment analysis two types of gas, Carbon Dioxide (CO₂) and

Nitrogen Dioxide (NO₂).The is a pilot study in preparation for data collection

Received: 17 Mar 2013


Keywords:

Emissions

International Maritime-

-Organization (IMO)

Green House Gas (GHG)

Vessel

Bidong Island

GHG

Emission, Ship

IMO

EEDI

Climate Change

Correspondence: O. S. Oladokun

Universiti Malaysia Terengganu,

21030 Kuala Terengganu,

Malaysia


on larger ships. The pilot study involves sailing from Pengkalan Arang Jetty to Bidong Island and it is divided

into two modes, maneuvering mode and hoteling mode.

The international shipping is considered the most carbon efficient mode of commercial transport and

generally considered as an environmentally friendly means of transportation. This help shipping economy of

large scale, as a result of this, maritime and shipping industry experience rapid development and the number of

vessels sailing in the ocean continues to increase. However, the significant improvements that have taken

place in these industries lead to the increasing of Green House Gas (GHG) considering the large involve of

vessel that sail the world ocean. The use of hydrocarbons and their derivatives as fuel contributes to air

pollution. The amount of emissions depends on the design, operating conditions and the characteristics of the

fuel. Complete combustion of fuel leads to the exhaust that contains only Carbon Dioxide (CO₂) and water

vapor. Carbon Dioxide (CO₂) emission depends on fuel consumption and carbon content in the fuel.

Some factors that influencing emission are cold starts, speed, maintenance, engine design and fuel

used [1]. The most troublesome GHG emission from diesel engine is NOx and soot (particulates). The black

smoke observed from certain ships or boats are due to high carbon particles content and it is obvious during

rapid load increase and when older engine at high load. As a response towards the GHG emissions problem,

another dimension has been added to the ship’s design and operational practices. The improvement in design

includes the propeller, hull, superstructure and use of retrofitting system for machineries (exhaust gas after

filter, humidification, exhaust gas recirculation, electronics injection and lubrication. For the operational

practices, the maintenance of the ships are to ensure that ship follow the schedule and guidelines and also by

slowing the speed of the ship during at sea as well as cold ironing. Other option being adopted is alternative

energy and hybrid concept.

This study focuses on the emissions concentration of Carbon Dioxide (CO₂) and Nitrogen Dioxide

(NO₂) that are released from the exhaust of Discovery II. The emissions concentrations are measured by using

the Gas Detector IQ-1000. The RV Discover II started sailing to Bidong Island at initial speed 6 knots and

continue at speed 12 knots during at sea. The distance of Bidong Island from Kuala Terengganu is 40km.

Table 1 show the principal particulars of the Discovery II that has been operated in 12 years.

Table 1: The principal particulars of Discovery II

Length overall 16m

Breadth 4.05m

Depth 2.15m

Fuel 4000L

Fresh water 1000L

Main engine 300HP/1800RPM

Speed (design) 12 knots

Cruise speed 10knots

Gross tonnage 43T

Net tonnage 16.82T

The experiment is divided into two which are maneuvering mode and hoteling mode. The hoteling mode data

is recorded near Bidong Island so that the data is not influence by the land activities.

2. BACKGROUND

The quests for an efficient fuel friendly to the environment have been recognized in maritime industry for a

long time. Need for improvements of gasoline and diesel by chemical reformulation that can lead to decrease

in GHG release and ozone forming pollutants and carbon monoxide emissions have become issues of the time.

Beside this, machineries that cannot use such conditional and additional inconvenience posed by these

reformulation chemicals are subject to performance problems like cold start ability, smooth operation and

avoidance of vapor lock.

Emission from combustion impacts generation of fossil fuel scarcity, photochemical smog, and oil

dependent world. Aggressive quest for alternative energy, international and local regulation build-up as well

as reassessment and revolution work on plan to reduce emission of existing and new engine are faced with new

145 | P a g e O. S. Oladokun, B. Michel, N. Stark, H. Azman, A.S.A.Kader

challenge of matching energy efficiency at minimum emission. Pollution control of emission is linked to

traditional factors of reliability, fuel economy per shaft power, capital cost and maintenance. Maximizing

overall energy efficiency that includes performance of temperature, electrical, thermodynamic and

mechanical as well insulated boiler system to achieve combustion efficiency close to 100% and thermal

efficiency of the order of 90% has a ways been the drive of the time for new low pollution and high efficiency

technology. Technology try to recuperate or prevent heat loss by high temperature exhaust gas and in coolant

systems reduces the thermal efficiency[6].

For marine electrical energy, technology is after 70 percent of the primary energy that is lost in the

power generation & transmission stage, while thermal efficiency improvement sough insulation, recycling of

gaseous effluents, rate of heat transfer in combustion chamber and liquid coolants. Designer of combustion

chamber aim to achieve high combustion efficiency as unburnt fuel is considered to be pollutants, this create

new directions for new engine and retrofit system for existing engines. The issue of emission compliance is a

disguise blessing of doubles incentive opportunity for humanity to develop complete combustion efficiency

and reduces emission. A good combustion require high temperature, a resident time sufficient long, present of

oxidizer heat transfer from flame to solid surface that compose of conduction, convection and radiation

luminosity and present of solid particles that can lead to significance change in ratio of radioactive to

convective heat transfer.

Problem associated with achieving maximum efficiency are linked to pollution control, complete

oxidation and burning of fuel, combustion efficiency and pollution prevention. However, oxide of nitrogen

presents major problems due to contradictory requirement of pollutant formation and combustion efficiency,

because, formation of oxides of nitrogen has affinity to high temperature. Compare to formation sulfur,

control require removal of sulphur before burning or extraction from effluent before send it for combustion

task.

3. GLOBAL WARMING AND ITS IMPACT

Global warming is the unusually rapid increase in Earth’s average surface temperature over the past century

primarily, due to the greenhouse gases released of exhaust waste from burning fossil fuels. The current

climatic warming is occurring much more rapidly than past warming events. In Earth’s history before the

Industrial Revolution, Earth’s climate changed due to natural cause unrelated to human activity. These natural

causes are still in play today, but their influence is too small or they occur too slowly to explain the rapid

warming seen in recent decades. Models predict that as the world consumes more fossil fuel, greenhouse gas

concentrations will continue to rise and Earth’s average surface temperature will rise with them. Based on

plausible emission scenarios, average surface temperatures could raise between 2°C and 6°C by the end of the

21st century. Some of this warming will occur even if the future of greenhouse gas emissions are reduced,

because the Earth system has not yet fully adjusted to environmental changes that is currently being

experienced.

The "greenhouse effect" is the warming that happens when certain gases in Earth's atmosphere trap

heat. These gases let in light but keep heat from escaping, like the glass walls of a greenhouse. The sunlight

shines onto the Earth's surface, where it is absorbed and then radiates back into the atmosphere as heat. In the

atmosphere, “greenhouse” gases trap some of this heat, and the rest escapes into space. The more greenhouse

gases are in the atmosphere, the more heat gets trapped. Levels of greenhouse gases (GHGs) have gone up and

down over the Earth's history, but they have been fairly constant for the past few thousand years. Global

average temperatures have stayed fairly constant over that time as well, until recently. Through the burning of

fossil fuels and other GHG emissions, humans are enhancing the greenhouse effect and warming Earth.

Some impacts from increasing temperatures that already happened are ice is melting worldwide,

especially at the Earth’s poles. Besides, the number of penguins on Antarctica has fallen from 32,000 breeding

pairs to 11,000 in 30 years. Sea level also rises faster over the last century. Some butterflies, foxes, and alpine

plants have moved farther north or to higher, cooler areas. Precipitation (rain and snowfall) has increased

across the globe, on average. Spruce bark beetles have boomed in Alaska thanks to 20 years of warm

summers. The insects have chewed up 4 million acres of spruce trees.

The ozone layer is a belt of naturally occurring ozone gas that sits 9.3 to 18.6 miles (15 to 30

kilometers) above Earth and serves as a shield from the harmful ultraviolet radiation emitted by the sun. Ozone


is a highly reactive molecule that contains three oxygen atoms. It is constantly being formed and broken down

in the high atmosphere, 6.2 to 31 miles (10 to 50 kilometers) above Earth, in the region called the

stratosphere[7].

The carbon trading came about in response to the Kyoto Protocol. Signed in Kyoto, Japan, by some

180 countries in December 1997, the Kyoto Protocol calls for 38 industrialized countries to reduce their

greenhouse gas emissions between the years 2008 to 2012 to levels that are 5.2% lower than those of 1990. A

carbon trading system allows the development of a market through which carbon (carbon dioxide) or carbon

equivalents can be traded between participants, whether countries or companies. Each carbon credit is equal to

one hundred metric tons of carbon dioxide, which can be traded or exchanged in market. There are two kinds

of carbon trading which are emission trading and trading in Project-based credits. The two categories are put

together as hybrid trading system. Carbon trading is also called pollution trading [8].

The exhaust fumes contain a large number of different chemicals or emissions. Once released into the

air, exhaust Emissions are breathed in and transported in the bloodstream to all the body's major organs. Diesel

seems potentially to be more of a problem than petrol. Potentially dangerous vehicle emissions include carbon

monoxide, nitrogen dioxide, sulphur dioxide and particulate matter. Although research has clearly linked

exhaust emissions to a range of health problems in the population, the exact risk to any individual is difficult to

define. The most obvious health impact is on the respiratory system. It's estimated that air pollution of which

emissions are the major contributor is responsible for 24,000 premature deaths in the UK every year. A Dutch

study confirm that,of 632 children aged seven to 11 years found that respiratory disorders worsened as air

pollution increased and a longer term study of older Dutch residents, published in 2009 found that illness due

to lung disorders increased in areas of high nitrogen dioxide and particulate matter associated with exhaust

emissions. Some of the impacts to health due to the emissions are cancer, central nervous system may grow

older and blood implication.

3.1 Green House Gas (GHG) Emission from Shipping

If global shipping were a country, it would be the sixth largest producer of greenhouse gas emissions. Only the

United States, China, Russia, India and Japan emit more carbon dioxide than the world’s shipping fleet.

Nevertheless, carbon dioxide emissions from ocean-going vessels are currently unregulated. These measures

can have an almost immediate effect on emission reductions, and a reduction of 33 percent below the

business-as-usual baseline could be attained at no cost. Previous attempts by the industry to calculate levels of

carbon emissions were largely based on the quantity of low grade fuel bought by shipowners. The latest UN

figures are considered more accurate because they are based on the known engine size of the world's ships, as

well as the time they spend at sea and the amount of low grade fuel sold to shipowners. The UN report also

reveals that other pollutants from shipping are rising even faster than CO2 emissions. A spokesman for the

Department for Environment, Food and Rural Affairs said the government would support the development of

a global emissions trading scheme through the IMO, and was also "investigating the feasibility of including

maritime emissions" in the EU's trading scheme. He said the shipping industry must take its "share of

responsibility" for tackling climate change.

3.2 IMO and GHG Emission

According to the Second IMO GHG Study 2009, the level of GHG emitted by international shipping was

estimated to have 870 million tones or about 2.7% of the global man made emission of COx in 2007. Exhaust

gases are the main source of GHG emissions from ships and COx is the most important GHG that contribute to

global warming. The COx emission is expected to increase to 6% in 2020. If no mitigation measures are taken,

it can increase to 250% in 2050. Figure 1 showed the exhaust emissions from shipping industry between 1997

and 2007.


Figure 1: CO2 exhaust emissions from shipping industry between 1997 and 2007

Figure 2 revealed one of the reason, regulatory institution for stepping up the On July 2011,

International Maritime Organization (IMO) adopted a new chapter to MARPOL annex VI which is to reduce

GHG emission from international shipping by improving the energy efficiency for ships. The hull design,

propulsion techniques and operational practices are expected technology that can be improved in order to

increase the energy efficiency for ships. The Marine Environment Protection Committee (MEPC) approved

the interim guidelines on the method of calculation of Energy Efficiency Design Index (EEDI) towards

determining minimum energy efficiency level for new ships. It is apply to all merchant ships of 400 gross

tonnages and above regardless of the national flag the fly or the nationality of the owner [5].

Emission is inherent consequence of powered shipping, fuel oil burning as main source of continuous

combustion machineries like boilers, gas turbines and incinerators. GHG emission is closely linked to

machineries combustion. For a long time environmental issues in shipping has focused more on release to

water, only lately release to air and soil has become serious issue of concern because of pressure from climate

change impacts. Shipping is still considered far less emission pollutant compare to other mode transportation,

but a thorough analysis on the volume ship and risk impose to the ocean media that support all activities on

earth pose a big question on the actual quantity of emission. However, since environment differs, so are the

impact and the presence of pollutants, thus they are dependent on the volume of shipping traffic. Yet the

science of transportation of atmospheric gas dictates more about need for the whole world to work together.

Recent IMO resolution on these mandated nations to collect data on emission so that reliable compliance

measures can be incorporated into annex of MARPOL in order to meet the requirement for Energy Efficiency

Design Index (EEDI), Ship Energy Efficient Management Plan (SEEMP) and Ship Energy Efficiency

Operational indicator (SEEOI). Study of emission from ship has not been fully initiated or studied in

Malaysia.

The purpose of this multidiscipline research project is therefore to record and analyse the different

Green House Gas Emison from boat, ships, near or within the vicinity of port, inlandwater port areas,

shipping lanes in order to determine the characteristics and source of emison at different locations for require

rule making and decisuon support for choice of environmental prevention and contriol technology. Table 2

shows Inland waterways environmental performance in European waters concluded the following.

Table 2: Emission reduction potential

NOx PM FC Cox Sox

% % % % %

After treatment

SCR (Selected catalytic reduction) -81 -35 -7.5 -7.5 -7.5

PMF (Particulate matter filter) None -85 2 2 2

Drive management systems

ATM (Advising temporal) -10 -10 -10 -10 -10

Diesel fuel quality / substitutes

(BD) Bio – Diesel -10 -30 15 65 ~-100

BDB (Biodiesel blend , 20%BD) 2 -6 3 -13 ~-20

LSF (Low sulfur fuel) None -1.7 none None ~-100

New engine technology

NGE (Natural Gas Engine) -98.5 -97.5 4.5 -10 -100


4. METHODOLOGY

4.1 Study Location

Thus, there are recent GHG gas emission quantification in other part of the world, but the data are hard to to be

applied to pother region, because, reliability of environmental research require localization. RV Discovery II

is sailed from Pengkalan Arang Jetty to Bidong Island. The data is collected during its saling, maneuvering

and hoteling mode, the data is recorded near to the Bidong Island that is far from the land. Therefore, the

concentration of gases recorded by the equipment is mainly coming from the vessel engine. Data information

related the following are used:

Emission factors for each components air emission factors for air is established by regulatory bodies

Fleet information on board data based ship performance information

Ship operational data (power consumption, speed time at sea)

Shipping movement information from different source within fleet that call Malaysia and European

ports

Analysis will be made for contribution by vessel and operations

4.2 Equipment

The equipment used for collecting the concentration of gases is the Gas Detector IQ-1000. It can detect over

100 toxic and combustible gases using a single sensor. The calibration is automated with no manual

adjustments necessary. The power is provided by 6 ‘D’ size alkaline or nickel cadmium batteries. The data that

is successfully recorded is displayed on the unit and stored in data acquisition system and then transferred to

through the RS 232 computer port or send to printer for further analysis. This equipment is placed on the safe

and balance area near the exhaust of Discovery II. The sensor is then pointed 20 cm away from the exhaust

hole. The setting of the equipment is changed by selecting three types of gases, Carbon Dioxide (CO₂), Nitrogen Dioxide (NO₂) and Sulphur Dioxide (SO₂) as parameters that are going to be measured. The

procedure of using the Gas Detector IQ-1000 is as followed (Figure 2):

i. AC power supply is connected to the unit.

ii. Sensor is connected to the unit.

iii. Gas detector IST IQ-1000 is turned on by pressing the POWER button and waits until the reading

appeared at every sensor.

iv. The pump is turned on by pressing the PUMP button.

v. The LOG DATA button is pressed to record the data.

vi. The LOG DATA and PUMP are turned off after the sampling is finished.

Figure 3 shows the experimental setup of the pilot study conducted on Discovery II.

Figure 2: Experimental setup


EEOI represent performance index that provides the CO2 level per unit of cargo/passenger moved by unit of

distance.

EEOI estimation takes into consideration:

cargo mass term (mcargo) which is expressed as tonnes, TEU, passengers, etc.

• actual fuel consumption (FC).

• carbon factor (CF) selected based on fuel type

• actual distance (D) over ground.

• acceptable damping factor voyage fluctuations and rolling

(1)

EEDI represent combined impact of commercial, operation and technical aspects. Its estimation face

challenges related voyage definition, data collection, data quality, bunker consumption uncertainty, sea state

conditions, weather, etc. Figure 4 shows the flow chart EEDI calculation for new ships. EEDI values that can

be used to calculate overall EEDI for anticipated operations like loaded voyage at a range of operating speeds,

ballast voyage at a range of operating speeds, loading alongside and discharge alongside. At design stage

EEDI could be used to support decisions for suitability of ships for different trades. Comparison of EEOI and

EEDI define improvement in auxiliary power to more closely represent actual operation. Calm water EEOI

values could be compared with EEDI values to assess degradation in performance. Such comparison could

also be used to compare different transport modes (Figure 3).

EEDI(new ships)

CO₂ emission Transportwork

Lloyd’s data ormanufacturer

Ship’s dataMain

engineAuxiliaryengine

fj Cf Power SFC Power Cf SFC

CO₂ efficiency

Figure 3: Research methodology flowchart

EEDI is the abbreviation of Energy Efficiency Design Index. Marine Environment Protection

Committee (MEPC) has developed the EEDI formula for new ships in order to require the minimum energy

efficiency level for new ships and to stimulate continued technical development of all the components

influencing the fuel efficiency of a ship. It also separate the technical and design based measures from the

operational and commercial measures as well as enable the comparison of the energy efficiency of individual

ships to similar ships of the same size which could have undertaken the same transport work. The EEDI

formula provides a specific figure for an individual ship design, expressed in grams of CO per ship’s capacity


mile (a smaller EEDI value means a more energy efficient ship design) and calculated by a given formula

based on the technical design parameters of a given design:

(2)

Where: ME and AE represent main engine(s) and auxiliary engine(s); P, the power of engine (kW); CF

a conversion factor between fuel consumption and CO2 based on carbon content; SFC, the certified specific

fuel consumption on the engines (g/kWh); Capacity, the deadweight (tonnes); Vref is the ship speed (knot);

and fj is a correction factor to account for ship specific design elements fw is a non-dimensional coefficient

indicating the decrease of speed in representative sea conditions of wave height, wave frequency and wind

speed. fi is the capacity factor for any technical/regulatory limitation on capacity, and can be assumed one

(1.0) if no necessity of the factor is granted. The EEDI formula can be simplified to:

EEDI = CO₂ emission / transport work

The CO₂ emission represents total CO₂ emission from combustion of fuel at design stage, including

propulsion and auxiliary engines, taking into account the carbon content of the fuels in question. If shaft

generators or innovative mechanical or electrical energy efficient technologies are incorporated on board a

ship, these effects are deducted from the total CO₂ emission. If wind or solar energy is used to board a ship, the

energy save by such measures will also be deducted from the total CO₂ emissions, based on actual efficiency

of the system. The transport work is calculated by multiplying the ship’s capacity as designed (deadweight for

cargo ships and gross tonnage for passenger ships) with the ship’s design speed measured at the maximum

design load condition and at 75% of the rated installed shaft power. Speed is the most essential factor in the

formula and may be reduced to achieve the required index. Table 3 shows necessary input data and

assumption.

The nitrogen emission per year can be estimated from;

(5.34lb/Hr).(8760hr/year).(ton/200lb)

Where 5.34lb is assumed emission factor

Table 3: Input data

Activities Category Source

Ship

Movements

Data Records for each vessel: vessel type,

Previous and current ports, date of

movement, etc

Navigation data

Main engine

power

Correlations for vessel type and DWT

Navigation data, Marine Department, or Environmental

department’s

Aux engine

power Estimate

using aux/main engine power ratio From Within Malaysia and European ports

Load factors by mode Factors Malaysian ports environmental department best practices

methods. Emission factors Entec, 2002, Swedish Methodology

for Environmental Data, 2004, Starcrest, 2004, MAN B&W,

2004. Vessel speed Navigation data or default values.

Time underway Port-to-port distances were estimated

individually for 80% of movements.

Simplified distance estimates for balance.

Equal to distance/vessel underway speed.

Time

manoeuvring

For each vessel type. Includes intraport

distances in large ports

Equal to manoeuvring distance/vessel speed

Time hoteling By vessel type, based on vessel arrival &

departure., fuel statistics and emission

factors OR trading pattern vessels

Navigation data


IMO SEEMP guidelines are a mechanism for a shipping company to improve energy efficiency of a

ship’s operation. SEEMP provides guidance for the development of model plan for characteristics and needs

of individual companies and ships.

5. RESULT AND DISCUSSION

From three types of gases that have been selected, only two types are successfully detected by the Gas

Detector IQ-1000 which is Carbon Dioxide (CO₂) and Nitrogen Dioxide (NO₂). The data of exhaust

emissions are analyzed by using Microsoft Excel and Minitab 15. Table 4 shows the summary of the test when

Discovery II starts maneuvering at 6 knots.

Table 4: The concentration of Carbon Dioxide (CO₂) and Nitrogen Dioxide (NO₂)

Time (am) Carbon Dioxide (ppm) Nitrogen Dioxide (ppm)

9:21:59 0 0

9:22:07 0 0.7

9:22:08 70 4.2

9:22:09 290 8.7

9:22:10 820 13.4

9:22:11 1650 17.5

9:22:12 2000 20

9:22:59 2000 20

Based on the data collected, the graph time versus amount of gas concentration (ppm) is plotted. Figure

3 and Figure 5shows the graph of the concentration of the Carbon Dioxide (CO₂) and Nitrogen Dioxide (NO₂) respectively.

Figure 4: The concentration of Carbon Dioxide (CO₂) versus

time Nitrogen Dioxide Figure 5: The concentration of (NO₂) versus time

According to the graph for both gases concentration, the reading recorded increasing drastically until

they reached the maximum value. This is because; the engine of the boat needs high energy to maneuver at the

initial. The maximum reading for Carbon Dioxide (CO₂) is 2000 ppm while for the Nitrogen Dioxide (NO₂) the maximum reading is 20ppm. The Figure 6 and Figure 7 below show the data analyzed by using Minitab 15.

The histogram shows acute skew to the left and agreement to the rise in the release of the gas during the

experiment.

09:22:5909:22:1209:22:1109:22:1009:22:0909:22:0809:22:0709:21:59

2000

1500

1000

500

0

Time (am)

Ca

rbo

n D

ioxid

e (

pp

m)

Chart of Carbon Dioxide (ppm)

09:22:5909:22:1209:22:1109:22:1009:22:0909:22:0809:22:0709:21:59

20

15

10

5

0

Time (am)

Nit

ro

ge

n D

ioxid

e (

pp

m)

Chart of Nitrogen Dioxide (ppm)

Figure 6: The concentration of Carbon Dioxide Figure 7: The concentration of Nitrogen Dioxide


Table 5 shows the summary of the test during Discovery II maneuvering at sea.

Table 5: The concentration of Carbon Dioxide (CO₂) and Nitrogen Dioxide (NO₂)

Time (am) Carbon Dioxide (ppm) Nitrogen (ppm)

9:57:47 2000 0.9

9:57:50 2000 0.9

9:57:51 2000 1.6

9:57:54 2000 2.1

9:57:55 2000 3.6

9:57:56 2000 6.2

9:57:57 2000 8.8

9:57:58 2000 11.1

9:57:59 2000 13.1

9:58:00 2000 14.9

9:58:01 2000 16.4

9:58:02 2000 17.7

9:58:03 2000 18.7

9:58:04 2000 19.5

9:58:17 2000 20

Based on the data collected, the graph time versus amount of gas concentration (ppm) is plotted.

Figure 8 and Figure 9 show the graph of the concentration of the Carbon Dioxide (CO₂) and Nitrogen Dioxide

(NO₂) respectively.


time

Figure 9: The concentration of Nitrogen Dioxide (NO₂) versus

time

According to the graph, The concentration of Carbon Dioxide become constant at maximum value of

2000 ppm. For the concentration of Nitrogen Dioxide, the graph plotted is smoother than the previous graph,

because the vessel starts to sail then. It is increasing slowly at the beginning and continue without drastic until

it reach the maximum value. The Figure 10 below shows the data analyzed by using Minitab 15 for Nitrogen

Dioxide only. The histogram shows similar trend with previous Nitrogen reading.

09:58:1509:58:1009:58:0509:58:0009:57:5509:57:5009:57:45

30

25

20

15

10

5

0

Time (am)

Nit

rog

en

Dio

xid

e(p

pm

)

S 3.67642

R-Sq 76.7%

R-Sq(adj) 74.9%

Fitted Line PlotNitrogen Dioxide(ppm) = - 32270 + 77735 Time (am)

Figure 10: The concentration of Nitrogen Dioxide


Table 6 shows the summary of the test during Discovery II is in hoteling mode.

Table 6: The concentratio of Carbon Dioxide (CO₂) and Nitrogen Dioxide (NO₂)

Time (pm) Carbon Dioxide (ppm) Nitrogen (ppm)

12:21:52 2000 0.4

12:21:52 2000 0.4

12:21:55 2000 0.9

12:21:56 2000 1.8

12:21:57 2000 2

12:21:59 2000 3.8

12:22:00 2000 6.8

12:22:01 2000 10.1

12:22:02 2000 12.9

12:22:03 2000 15.2

12:22:04 2000 17.1

12:22:05 2000 18.7

12:22:06 2000 20

12:23:10 2000 20

Based on the data collected, the graph time versus amount of gas concentration (ppm) is plotted.

Figure 11 and Figure 12 show the graph of the concentration of the Carbon Dioxide (CO₂) and Nitrogen

Dioxide (NO₂) respectively.


time

Figure 12: The concentration of Nitrogen Dioxide (NO₂) versus

time

According to the graph, the concentration of Carbon Dioxide (CO₂) still not change and keep consatnt.

For the concentration of Nitrogen Dioxide, it is increasing slowly and sometimes constant at the beginning

then it continue to increase until it reach maximum value. The Figure 13 below shows the data analyzed by

using Minitab 15 for Nitrogen Dioxide only. Similar histogram trend is obtained.

12:2

3:10

12:2

2:06

12:2

2:05

12:2

2:04

12:2

2:03

12:2

2:02

12:2

2:01

12:2

2:00

12:2

1:59

12:2

1:57

12:2

1:56

12:2

1:55

12:2

1:52

20

15

10

5

0

Time (pm)

Nitr

ogen

Dio

xide

(ppm

)

Chart of Nitrogen Dioxide(ppm)

Figure 13: The concentration of Nitrogen Dioxide


7. CONCLUSION

The maximum reading of Carbon dioxide and Nitrogen Dioxide that can be detected by the Gas Detector IST

IQ-1000 are 2000ppm and 20ppm respectively. At the initial stage of the experiment, the amount of Carbon

Dioxide increased dramatically and it remains constant until the experiment is finished. For the Nitrogen

Dioxide, it also increased dramatically at the initial of the experiment and its amount keeps changing and not

constant until the experiment is finished. The overall data showed that the Nitrogen Dioxide measured keep

changing and not uniform. For the first reading, the data collected finished in 5 seconds while the second

reading, third reading and fourth reading finished in 33 seconds, 18 seconds and 8 seconds respectively. For

the hoteling mode which is fifth reading and sixth reading, the data collected finished in 25 seconds and 14

seconds respectively. The amount of Nitrogen Dioxide in each data collected is increasing, decreasing and

sometimes constant. The data collected in this pilot study is based on the unsophisticated device. The

experimental set up is the first experiment we have done in measuring the gas emission. The pilot study is

preparation for similar experiment on ocean going vessel, and inadequacy experience in the pilot study will be

mitigated for better accuracy.

Acknowledgement

Author thanks Nurul Akmar for direct contribution to the research.

REFERENCES

[1]. B.P. Pundir (2007). Engine Emissions Pollutant Formation and Advances in Control Technology,

Genesis and formation of pollutants, page 13, Alpha Science International Ltd., Oxford, UK

[2]. Hans Otto Kristensen (2001). Cargo Transport by Sea and Road-Technical and Economic Environmental

Factors

[3]. Sulaiman o.,Shamila A., Hanis Wahab M., Saman AB., Saharuddin A.H. Emissions of Green House Gas

of Ships in Port in Johor Port (Malaysia), UTM, Johor

[4] Clark,J.K. (1999). Humidity sensor. Journal of Physics, 2(2): 9-13 (online). http://www.cit.edu/phy/

sensor/phy/sensor.html, access on 20 July 1999.

[5]. IMO (2000). Marine Environmental Protection Committee. 44th session available at: http:

www.imo.org/meeting/44.html.

[6] O. O. Sulaiman, A.S.A. Kader, A.H. Saharuddin, W.B. Wan Nik (2011). Air Emission from Ship Driving

Force for Next Generation Marine Technological and Policy Change: A Review, African Journal of Business

Management, Vol. 5(33), pp. 12664-12683

[7] N Slocombe,D. S (1993). Environmental planning, ecosystem science, and ecosystem approaches for

integrating environment and development. Environmental Management

[8] Ghai, Dharam and Jessica M. Vivian, .Introduction. in Dharam Ghai and Jessica M. Vivian (eds.). (1992)

Grassroots Environmental Action: People.s Participation in Sustainable Development, Routledge, London

[9] Jeremy Colls (2002). Air Pollution Second Edition, Shipping emissions, page 150, Spon Press 29 West

35th

Street, New York, USA and Canada

Please cite this article as: O. S. Oladokun, B. Michel, N. Stark, H. Azman, A.S.A.Kader, (2013), Pilot Study for Quantification of Emissions of Green House Gas for Marine Transportation Decision Support, Journal of Science and Engineering, Vol. 1(2), 143-154.

http://www.cit.edu/phy/

http://www.imo.org/meeting/44.html




Vol. 1 (2), 2013, 155-161






STUDY OF PROPERTIES OF COMPONENTS FOR OFFSHORE

AQUACULTURE TECHNOLOGY FARMING

O. S. Oladokun

1, W.B. Wan Nik

1, A.S.A.Kader

2

1Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Malaysia

2University Technology Malaysia, Skudai, Johor

Abstract

This study outlines analysis about selection of suitable material for offshore technology

farming, especially in seaweed farming. Floating structures has proved to have economical

and dependable, operational advantages and it emerging to be more acceptable from an

environmental point of view. Generally, floating structure is used for the construction of

various facilities and accommodations. Study of properties of components for offshore

aquaculture technology farming involved the properties of material selection that is suitable

for floating offshore structure, and is conducted based on the case study area which is in

Setiu, Terengganu. The materials are two types of rope; manila and polyester, and SHE-20

type of buoy. The result from the tensile test showed that manila rope has better usage for

larger force and polyester rope can be use within smaller scale of force. The result from

water absorption test showed that the buoy absorbed water with lower percentage, which

means it can be used for longer period. This study also involved other tasks; for example data

gathering, experimental test, field works, and prototype modelling. The result of the study

hopes to contribute to ocean farming, especially seaweed farming in the future.

1. INTRODUCTION

Floating structure in general have been used for the construction of

floating houses, storage for liquid and dry bulk materials, bridges, airports,

golf courses, and miscellaneous industrial facilities (Gregory, 1995). In

maritime industry, there are many activities that can be done and give back

benefit for community, especially in Shipyard industry, Marine leisure, and

Support services. Nowadays, the world seems to look forward to the present

fast-developing seaweed farming (NMIF, 2010) and use of floating structure.

Seaweed farming was first devoted in Japan at least 1500 years ago, based on

the early written records. It started in Japan in early 1670 in Tokyo Bay. In

autumn of each year, farmers would throw bamboo branches into shallow,

muddy water, where the spores of the seaweed would gather. A few weeks

later these branches would be changed place to a river estuary.

Correspondence: O. S. Oladokun

Universiti Malaysia Terengganu,

21030 Kuala Terengganu,

Malaysia

Received: 17 Mar 2013


Keywords:

Offshore aquaculture

Material

Structure

Seaweed

Ocean


NOMENCLATURE DNV Det Norske Veritas NMIF National Marine Industries Forum

JTM Jabatan Teknologi Maritim UTS Ultimate Tensile Strength

ISOS International Ship and Offshore Structures VLFS Very Large Floating Structure

The nutrients from the river would assist the growth of seaweed. In the 1940s, the Japanese enhanced this

technique by placing nets of synthetic material tied to bamboo poles. This efficiently doubled the production.

A lower cost alternative of this technique is known the hibi technique; simple ropes stretched between bamboo

poles. In the early 1970s demand for seaweed and seaweed products, outstripping supply and cultivation was

seen as the best way to increase productions (Borgese et al, 1980).

On the other hand, the production itself is giving some useful information. It is almost entirely derived

from culture in floating cages, which is essentially an open system. The open nature of this culture system

allows the outputs to participate in exterior biological, chemical and ecological systems, where they may cause

unwanted effects. These effects are often complex, varying by orders of scale on temporal and spatial scales

(Black et al, 2008). Commercial seaweed farming in Malaysia started in Sabah coastal area in the 1970s.

Sabah is tranquilly the main manufacturer of seaweed in Malaysia on a commercial scale, and this is primarily

in Semporna, Lahad Datu, Kudat, and Kunak. Besides, the recent implementation of the National Aquaculture

Centre, and the latest declaration of the 2010 Budget on October 23, 2009, has seaweed being mentioned

specifically as one of the most important food farming production for the country. Although the sector has

developed extremely over the past few years (about 111,298 tonnes wet weight in 2008), seaweed production

national target by 2010 of 250,000 tonnes in wet weight is however yet to be achieved. There are some major

issues and challenges to this, for example the unavailability of good quality seedlings, pollution in cultivation

areas, diseases, shortage of raw materials, lack of capital to venture into the industry, lack of research and

development agenda listed by the government itself. This research involved the study of properties of

components for offshore aquaculture technology farming. System and structure will go through the sources

from seaweed farming, the regulation of offshore aquaculture with respect to the components within

technology seaweed farming, together with some of models that have been developed, the relationships with

other coastal users and finally consideration for site selection and some commercial aspects.

Based on the general view, the study about properties of components for offshore aquaculture technology

farming has wide range of area. The study focused on areas which are fieldwork, experimental set up and

validation with standard based on the classification society recommendation. The fieldwork is within Kuala

Terengganu and Setiu area to provide environmental data suitability components used for offshore

aquaculture technology farming, especially seaweed farming. The components that are used are ropes and

buoy. One of the most important parts is the experimental set up. This is required to provide data to achieve the

aim and the objectives of the research. The experiment is done at marine technology laboratory using Gotech

Universal Testing Machine, and also Kampung Pak Tuyu area; which are to test the properties of components.

The tests that have been done are Tensile Test and Water Absorption Test.

2. OFFSHORE AQUACULTURE

Open ocean aquaculture or offshore aquaculture is an up-and-coming approach to mariculture or marine

farming where fish farms operations some distance offshore. The offshore aquaculture involves farms that are

located in deeper and less sheltered waters, where ocean currents are stronger than they are inshore. One of the

concerns with inshore aquaculture especially fish farming is that unnecessary nutrients and feces can resolve

beneath the farm on the seafloor and harm the benthic ecosystem (Lisac, 1996). Proponents of the wastes from

aquaculture that has been moved offshore tend to be swept away from the site and diluted with it. However,

moving aquaculture offshore also provides more gaps where aquaculture production can enlarge to meet the

increasing demands for fish. Moving aquaculture offshore avoids numerous of the conflicts that arise with

other marine resource users in more crowded inshore waters, there can still be consumer conflicts offshore.

Beside this, there is criticism regarding issues such as the ongoing consequences of using antibiotics and other

drugs and the potential of cultured fish evasion and distribution of disease among feral fish. Furthermore

aquaculture is the most swiftly growing food industry in the world, resulting from the declining of wild

157 | P a g e O. O. Sulaiman, W.B. Wan Nik, A.S.A.Kader

fisheries stocks and profitable business. In 2008, aquaculture provided 45.7% of the fish produced worldwide

for human consumption; increasing at a mean rate of 6.6% a year since 1970 (Harold et al, 2010). Nonetheless,

using some of the offshore Very Large Floating Structures (VLFS) technology system as well as suitable

material can improve productivity. VLFS are artificially man-made floating land parcels on the sea. The

system appears like giant plates resting on the sea surface. VLFS may be broadly categorized into the

semisubmersible-type and the pontoon-type. The semisubmersible-type VLFS has a raised platform above sea

level by using column tubes and is suitable for deployment in high seas with large waves. On the contrary, the

pontoon-type VLFS platform rests on the water surface and is intended for deployment in calm waters such as

in a cove, a lagoon or a harbor (Wang et al, 2011).

3. SEAWEED FARMING

Seaweed farming is defined as the perform act of cultivating and harvesting seaweed. In its most simple

outline, it involves the management of naturally found batches. In its most sophisticated form, it involves fully

controlling the life cycle of the plant. The main seaweed species grown by aquaculture in Japan, China and

Korea include Gelidium, Pterocladia, Porphyra, and Laminaria. The Long Line system allows for culture of

shellfish (in mussel collectors) as well as seaweed growing on ropes suspended from the surface line (Buck et

al, 2005). Figure 1 shows the Long Line System that is used for the seaweed farming.

Fig. 1: Long Line System

Seaweed farming has commonly been developed as an alternative to improve economic conditions and to

decrease fishing pressure and over exploited fisheries. In addition, seaweeds have been harvested throughout

the world as a food source as well as an export product for manufacture of agar and carrageenan products.

(Moan, 2004). The offshore ring system consists of a submerged ring with culture lines descending from it,

surface flotation and anchoring system. The rigging is adjusted to maintain the growing lines below the

surface at the optimum light depth for growth. This system continues to undergo tests and improvements and

should be watched as a potential large-scale seaweed cultivation platform (Reith, 2005). The ring system can

be completed rigged on-shore then towed to the location and anchored, decreasing the need for costly

construction at sea (Buck & Buchholz, 2004). Figure 2 shows the Offshore Ring system.

Fig. 2: Offshore Ring System

4. OFFSHORE SYSTEM DESIGN


For specific reasons, the analysis and design of floating structures need to account for some special

characteristics (Clauss et al, 1992) when compared to land-based structures; namely:

i. Horizontal forces due to waves are in general several times greater than the (nonseismic)

horizontal loads on land-based structures and the effect of such loads depends upon how the

structure is connected to the seafloor.

ii. It is distinguished between a rigid and compliant connection; a rigid connection virtually

prevents the horizontal motion while a compliant mooring will allow maximum horizontal

motions of a floating structure in the order of the wave amplitude.

iii. Structures which are piled to the seafloor, the horizontal wave forces produce extreme bending

and overturning moments as the wave forces act near the water surface.

iv. The structure and the pile system need to carry virtually all the vertical loads due to selfweight

and payload as well as the wave, wind and current loads.

iv. If a floating structure has got a compliant mooring system, consisting for instance of catenary

chain mooring lines, the horizontal wave forces are balanced by inertia forces.

v. If the horizontal size of the structure is larger than the wave length, the resultant horizontal

forces will be reduced due to the fact that wave forces on different structural parts will have

different phase (direction and size).

vi. A particular type of structural system, denoted tension-leg system, is achieved if a highly

pretensioned mooring system is applied; additional buoyancy is then required to ensure the

pretension.

vii. Sizing of the floating structure and its mooring system depends on its function and also on the

environmental conditions in terms of waves, current and wind. The design may be dominated

either by peak loading due to permanent and variable loads or by fatigue strength due to cyclic

wave loading.

ix. It is important to consider possible accidental events such as ship impacts and ensure that the

overall safety is not threatened by a possible progressive failure induced by such damage.

x. Due to the corrosive of sea environment, floating structures have to be provided with a good

corrosion protection system.

xi. Possible degradation due to corrosion or crack growth (fatigue) requires a proper system for

inspection, monitoring, maintenance and repair during use.

In spite of these, the allowable strength limit state is intended to confirm that a structure has strength for

safe use throughout a service period with appropriate reserve. Buckling and yielding strengths of principal

structural members are evaluated on their elastic responses. The first class environmental load that

corresponds to a return period of at least double the number of service years is considered a characteristic

value. DNV's recommendations of good engineering practice for general use by the offshore industry, the

offshore standards also provide the technical basis for DNV classification, certification and verification

services. Buoys designed, built, installed, tested and intended to be followed up in-service under supervision

of the Society in compliance with the requirements of this standard will be entitled to the Class Notation:

Offshore Loading Buoy. Due to the particular nature of offshore loading buoys' operations and ownership, the

precise scope of classification is decided on a case-by case basis after agreement with the client (DNV, 2008).

Functionality and safety criteria are key issues that dominate the structural design. The excessive

structural response could lead to the sinking of the floating structure due to progressive flooding and drifting

of the floating structure due to the failure of system. However, the motions of a floating structure become large

when the length of mooring line is rather long. Moreover, the tension leg system is adopted to which the

pretension is applied to the mooring line in order to restrain heaving motion especially in deep seas. In such a


station keeping system, it is difficult to restrain the horizontal motion and usually the mooring lines experience

significant tension forces (I.A. Hinojosa, 2009).

5. RESULT

Figure 3 shows the graph for tensile stress-strain test of manila rope. When the load was applied, stress of

the rope was higher and at point of 5.3117 kN/mm2 stress, the value was constant. Until it reached its highest

load which is 1.0023 of strain, it was sharply decreased. The rope was broken that it cannot withstand higher

load any more. At that point, it was its ultimate strength.

Fig. 3: Graph for Manila Rope’s Tensile Stress-Strain

When the load was applied, stress of the rope was higher and at point of 5.3117 kN/mm2 stress, the value

was constant. Until it reached its highest load which is 1.0023 of strain, it sharply decreased. That means the

rope was broken that it cannot withstand higher load any more. Figure 4 shows the graph of modulus of

elasticity and break elongation for Manila rope.

Fig. 4: Graph of Modulus of Elasticity and Break Elongation for Manila Rope

The highest point of which the rope was broken when time is 37.112 s and load applied on the rope is

3906.213 kN. The result was that the stress is 4.4311 kN/mm2 and the strain is 0.0621 %. Figure 5 shows the

graph for tensile stress-strain test of polyester rope.

Fig. 5: Graph for Polyester’s Tensile Stress-Strain

Stress of the rope was higher and at point of 4.4355 kN/mm2 of stress, the value is constant. Until it

reached its highest load which is 1.0023 of strain, it was sharply decreased. The rope was broken that it cannot


bear the higher load applied onto it any more. It recorded that it was the ultimate strength. Figure 6 shows the

graph of modulus of elasticity and break elongation for Polyester rope.

Fig. 6: Graph of Modulus of Elasticity and Break Elongation for Polyester Rope

Figure 7 and figure 8 below show the graph for differences between manila with polyester’s modulus of

elasticity and break elongation.

Fig. 7: Graph for Difference between Manila and Polyester’s Modulus of Elasticity

Fig. 8: Graph for Difference between Manila and Polyester’s Break Elongation

Each of the figures indicates the difference in capability of two types of rope that could be use in two different

situation and usage. The figures show that Manila rope has higher modulus of elasticity and break elongation

than Polyester rope.

6. CONCLUSION

This study is about the study of floating material for offshore aquaculture technology farming. The study

is aimed to provide a recommendation for development of seaweed farming in local coastal area. Some parts

of this study have the ability to develop better system. In this study the validation with the standard of

classification society to meet its expectation is important. The study uses the classification society as bench

mark for criteria. The properties of the material were investigated and determined by the calculation of each

part of the test theory. Observed error or other circumstances is given and recommendation is provided for

future research. Laboratory test provides the required data to validate the result, and the theoretical analysis

can be useful generally for seaweed farming.


As future baseline, the rule and regulation development was about to avoid any error that could bring any

bad incident to take place. For example, risk assessment approaches are now available tools to use for

developing rules and regulations for better workplace. Based on this study, it is recommended to continue for

further research that focuses on the following issues:

i. Environmental impact study and carbon footage

ii. Cost of the material.

iii. Other properties that can be determined such as corrosion resistivity and fatigue analysis.

iv. Other material that involved in the seaweed farming such as anchor, shackle and chain.

Aknowledgement

Author thank Azri Akif for direct contribution to the research.

REFERENCES

[1] Black, K.D., Hansen, P.K. and Holmer, M. (2008). Salmon Aquaculture Dialogue: Working Group

Report on Benthic Impacts and Farm Siting. 54 pages.

[2] Buck, B. H. And Buchholz, C. M. (2004). The offshore-ring: A new system design for the open ocean

aquaculture of macroalgae. Journal of Applied Phycology, 16, 355-368.

[3] Buck, B. H. And Buchholz, C. M. (2005), Response of offshore cultivated Laminaria saccharina to

hydrodynamic forcing in the North Sea. Aquaculture, 250, 674-691.

[4] Borgese, Elisabeth Mann (1980). Seafarm: The Story of Aquaculture. Accepted on 25th of October 2011.

[5] Clauss, G., Lehmann, E. and Ostergaard, C. (1992). Vol 1 Conceptual Design and Hydromechanics.

Offshore Structures.

[6] Det Norske Veritas (DNV), Offshore Standard DNV-OS-E403 (2008).

[7] Fujikubo M. (2005). Structural Analysis for the Design of VLFS: Marine Structures 18. Page 201–226.

[8] Gregory P. Tsinker (1995), Port Engineering. WILEY – John Wiley and Sons, Inc. Publisher. Page 422 –

577.

[9] Harold F. Upton and Eugene H. Buck (2010). Open Ocean Aquaculture. CRS Publisher.

[10] Hinojosa I. A. and Thiel M. (2009). Marine Pollution Bulletin. Page 58.

[11] International Ship and Offshore Structures (ISOS) Congress (2006) the 16th. Accepted on 24th of

October 2011.

[12] Lisac D. (1996). A Tension Leg Cage System for Offshore Aquaculture in the Mediterranean, CIHEAM

Publisher. Page 109 – 113.

[13] Moan, T. (2004). Safety of Floating Offshore Structures.

[14] Naval Facilities Engineering Command, Mooring Design Physical and Empirical Data, Design Manual

26.6 (1986).

[15] Reith, J. H., E.P. Deurwaarder, K. Hemmes, A.P.W.M. Curvers, P. Kamermans, W. Brandenburg, G.

Zeeman (2005). Grootschalige teelt can zeewieren in combinatie met offshore windparken in de Nordzee.

Energy Commission of the Netherlands.

[16] Wang C. M. and Tay Z. Y. (2011). Very Large Floating Structures: Applications, Research and

Development: Procedia Engineering 14. Page 62–72.

[17] Buoy. http://shfloats21.en.ec21.com/Purse_Seine_Gill_Net_Floats--1043047_1043435.html [7th of

January 2012]

[18] First National Marine Industries Forum (NMIF), 2010. http://www.mima.gov.my [8th of October 2011]

[19] Tensile Property Testing of Plastics. http://www.matweb.com/reference/tensilestrength.aspx [19th

January 2012]

[20] Universal Testing Machine. http://www.servo-utm.com/products.htm [1st of October 2011]

Please cite this article as: O. O. Sulaiman, W.B. Wan Nik, A.S.A.Kader, (2013), Study of Properties of Components for Offshore Aquaculture Technology Farming, Journal of Science and Engineering, Vol. 1(2), 155-161.




Vol. 1 (2), 2013, 163-172




All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of ORIC Publications, www.oricpub.com.

ANALYSIS OF THE ELASTIC ENERGY AND CRACK

TIP OPENING DISPLACEMENT WITH INCREASED YIELD

STRESS

Hannachi Mohamed Tahar1, Djebaili Hamid

2

1Depatment of mechanic, University sheik Larbi Tébessi, Tébessa 12000, Algeria

2Depatment of mechanic, University Abbas Lagrour, Khenchela 40000, Algeria

Abstract

This study is a calculus and computational of Aluminum alloys sent Tension specimen was

considered. We tempted to determine some parameters (Crack tip opening displacement

(CTOD), size of plastic zone and elastic energy) for three values of yield stress. The

distribution of stresses, under both plane stress and plane strain conditions, can be

obtained for region near the crack tip by simulation by finite elements (FE) by

Castem2001.

1. INTRODUCTION

The concept of CTOD (δ) came into existence by the independent

works of Wells, Cottrell and Barenblatt. It is proposed that when a

significant amount of plasticity occurs at the crack tip, the fracture

process is essentially controlled by the attainment of a critical strain

adjacent to the crack tip which can be measured be the CTOD. Dugdale

postulated a strip yield model that gives a plastic zone size in plan

stress for an ideal plastic non-strain hardening material. Alloys of Al-cu

have been widely used for aircraft issue for the aerospace industry [1-17].

The latest and upcoming generation of Al-Cu alloy has received much

attention for military, space and commercial application because they offer

low density, improved specific strength, damage tolerance and high

stiffness to weight ratio as compared to the conventional commercial 2xxx

and 7xxx series aluminium alloys [18-23]. Although these alloys have the

desired lower density, higher modulus and improved fatigue resistance, they

also exhibit lower ductility and fracture toughness in the short-transverse

[24]. Facing the competition of composite materials in the aeronautic

industry, recent alloy developments have produced a new generation of Al-

Cu. Among these alloys, 2198 Al-Cu-Mg alloy, shows a good combination

of static tensile properties, damage tolerance and formability. For this

reason, they have been considered for the application of fuselage of new

generation commercial airplanes.


Keywords: Crack Simulation Tenacity Point of the Crack Plastic Zone

Correspondence:

Hannachi Mohamed Tahar

Department of mechanic,

University sheik Larbi Tébessi,

Tébessa 12000, Algeria


A new generation of Al-Cu alloys which contain less than 2 % Li and have a higher Cu/Li ratio than the

second generation alloys (2090, 2091 and 8090). This work is part of a project aiming at investigating

damage tolerance of the current Al-Cu alloys for aeronautic application, better understand the relationship

between microstructure evolution and damage tolerance properties. This project is divided into three main

research subjects. The second one started at the same time as present work; it deals with the fatigue

behaviour of Al-Cu alloys. In this study, four different Al-Cu-Mg thin sheet materials are investigated

analytic and numerically. Finally cohesive zone model is used to model ductile tearing behaviour of tested

materials, transferability from small sized. We consider a crack of a side plate aluminium alloy 2024, to

calculate and determine the CTOD in simple tension, the comparison of these two methods gives us a clear

idea about what is the effect of the crack opening space, and we end up with a Toy finite element (FE) code

by CASTEM2001 to see plastic zone of crack.

2. MATERIAL AND PROCEDURE

The material used to better reflect the formability of materials, since they reflect two important plastic

properties of metals (see table 1) . The numerical designation has been adopted in the NF A 02-104 (1980)

and is identical to the designation of EN 485-2. EN AW-2024 [AlCu4Mg1] 4% copper, 1% magnesium.

Table 1. Mechanical properties [25]

Alloy

(MPa) σ(MPa) A(%)

2024-T3 343 480 17

The theory of critical crack spacing (Crack-opening displacement, abbreviation CTOD.) was first

formulated by Wells [26]. The critical distance from the lips of a crack is considered a test of resistance to

boot tears. This theory of the critical crack spacing is especially applicable in the case of steels where the

plasticized zone at the crack tip becomes important and makes possible the separation of the lips of the

cracks years increasing its.

We show that the lamination produces a blunting the crack tip whose surfaces differ at this level of δ,

called COD (Crack Opening Displacement).

Fig. 1: Alloys of airplane

From the expressions of displacement and taking into account the plastic zone correction, this is

expressed as:

[

] (1)

165 | P a g e Hannachi Mohamed Tahar, Djebaili Hami

small enoughFor a constraint to , then :

with √ (2)

Indeed the equation (1) can be written in the form of a Taylor expansion:

[

]

[

]

[

]

(3)

The Calculations of Burdekin and Stone [27] show that the crack spacing δ (at the bottom of the real

crack) is given by the displacement in x ± a is:

the first term.

(4)

Using the model proposed by Dugdale and Barenblatt [28] [29], we link the critical crack spacing and the

fracture energy per unit area GC.

(5)

Comparing equations (4) and (5) we obtain the relation:

if ⁄ (6)

The value of the total deformation ε can be obtained experimentally by measuring the distance of

cracking on a gauge length equivalent (ie twice the value of the spacing of cracks).

(7)

Recently, Carboni [30] and Yamada and Newman [31] used micro-strain gauges glued near the front of

the crack locally to detect the small change of convenience for small cracks. In elastoplasticity, the crack tip

becomes blunt and some authors have proposed using the crack opening as a parameter of fracture

mechanics. The CTOD, crack or gap δ, has been defined from the displacement of the crack tip, measured at

the intersection of the boundary of the plastic zone with the lips of the crack. There are many ways to

calculate this distance δ. For example, Tracey has proposed to define this distance at the intersection of two

lines passing at 45 ° to the axis and the lips of the crack (see figure 2). Fellows and Nowell [32] used the

method of Moiré interferometry to measure the displacement of the lips of the crack to detect the closed

position. Chang et al. [33] proposed a technique for detecting acoustic emission to detect the closure of

small cracks. The main quantities in fracture mechanics is the stress intensity factors and energy release rate.

These quantities can be connected to each other, we propose to calculate the energy release rate using the

method presented above Gθ. Then we will compare the results with analytical results on geometrical

configurations known. After showing the good accuracy of the method Gθ, we study the influence of the

mesh on the results. For Linear isotropic elastic material, the value of the integral J is easily obtained in

plane strain:

(8)

and in plane stress:


(9)

To determine the accuracy and robustness of the method Gθ, we will compare the results obtained by this

method with known analytical results for certain geometric configurations.

For single specimens, and elasticity, it is possible to calculate stress intensity factors by analytical

formulas that can be found in several books. Then, the energy release rate is calculated using the following

formulas:

• Specimen SEC (Single Edge Crack):

It is a semi-infinite plate, subjected to a stress homogeneous, and having a crack length of side 2a (see

fig. 3). For this type of geometry, the stress intensity factor for pure opening mode (mode I), is:

√ (10)

(11)

This method is available to the technical progress of the crack developed by Park [34]. This method is

still effective and widely used in recent studies [35].

In a two-dimensional diagram, the elastic behavior of a material connects the constraints 11, 22 and 12

to deformation ε11, ε22 and ε12 In the case where the material is isotropic, the elastic behavior of the material

is characterized by its Young'smodulus (E) and its Poisson's ratio (υ). For a state of plane stress, the stress-

strain relationship can be written:

12

22

11

2

12

22

11

2

100

01

01

1

E

(12)

and in the case of a state of plane deformation, it is written:

12

22

11

12

22

11

)1(2

2100

011

01

1

)21)(1(

)1(

E

(13)

Stress values plotted on the curves of simulated behaviors for various distributions studied were

calculated using the relation of strength of materials giving the maximum tensile stress as a function of the

applied load P.

Critical factor of stress intensity (Tenacity):


w

af

bt

PK C

IC 2 (15)

The decomposition of the spacing critical crack (CTOD) an elastic portion and a plastic part.

plec (16)

Manufacturers demonstrate the need for modeling tools and / or simulation of welding, methodological or

predictive, to improve the reliability of assemblies. A major challenge for development teams of structure

lies in the prediction of the mechanical effects of welding (stresses and deformation). Castem 2000 use finite

element method. For an elastoplastic material, it is possible to represent the shape of the plastic zone at the

crack tip. Indeed, in plane strain, the theoretical models of the plastic zone at the crack tip provides a form

resembling butterfly wings.

Fig. 2: Single Edge Crack Specimen Fig. 3: Records of deformation

Fig. 4: Von Mises stress after 10 seconds of loading Fig. 5: Von loading after 50 seconds of loading


Fig. 6: Records of constraints SMXX and MYY

Table 2. results of CTOD, Size plastic zone and energy for three values of yield stresses.

Stress

Load

(MPa)

a

(mm)

Re=250 MPa Re = 450 Mpa Re= 650 Mpa

δ (mm) Rp

(mm)

G*

J.mm-2

δ (mm) Rp (mm) G*

J.mm-2

δ (mm) Rp (mm) G*

J.mm-2

= 200

MPa

2.5 0.0089 0.879 2.225 0.0036 0.763 1.620 0.0024 0.323 1.560

5 0.0178 1.758 4.450 0.0073 1.527 3.240 0.0048 0.646 3.120

7.5 0.0267 2.637 6.675 0.0109 2.290 4.860 0.0072 0.970 4.680

10 0.0356 3.516 8.900 0.0145 3.054 6.480 0.0096 1.293 6.240

12.5 0.0445 4.395 11.125 0.0182 3.817 8.100 0.0120 1.617 7.800

15 0.0534 5.274 13.350 0.0218 4.581 9.720 0.0144 1.940 9.360

17.5 0.0623 6.153 15.575 0.0255 5.344 11.340 0.0168 2.263 10.920

20 0.0712 7.032 17.800 0.0291 6.108 12.960 0.0192 2.587 12.480

*G unit: (1 J = 1 N.m)

Fig. 7: CTOD function of yield stress Fig. 8: CTOD function of size plastic zone

250 300 350 400 450 500 550 600 6500.008

0.01

0.012

0.014

0.016

0.018

0.02

0.022

yield stress Re(MPa)

CT

OD

(m

m)

2.5 3 3.5 4 4.5 5 5.5 60.008

0.01

0.012

0.014

0.016

0.018

0.02

0.022

Size of plastic zone Rp(mm)

CT

OD

(m

m)


Fig. 9: size of plastic zone function of yield stress Fig. 10 : CTOD and size of plastic zone function of length

of crack

Fig. 11 : energy function of CTOD for Re = 250 MPa Fig. 12 : energy function of CTOD for Re = 450 MPa

Fig. 13: energy function of CTOD for Re = 650 MPa Fig. 14: energy function of CTOD for Re = 250, 450 and 650

MPa

3. DISCUSSION

To obtain the best compromise between different properties to use an alloy, it is necessary to follow the

evolution of these properties in an integrated manner throughout the production process [37]. The precision

of the parts is related to the first functional tolerances tooling and a similar deformation or other validated.

250 300 350 400 450 500 550 600 6502.5

3

3.5

4

4.5

5

5.5

6

yield stress Re(MPa)

Siz

e o

f pla

stic z

one R

p(m

m)


To better improve the step of calculating, it has been a change in crack length, in order to determine the

spacing elastic, plastic and any corresponding critical by comparing the results obtained in two main

standards data. However in recent years aluminum alloy have emerged as attractive and viable commercial

materials for automotive aerospace [38]. The results are recorded in Table 2. The test was simulated in 2D

and illustrated in figure 2. . The numerical method allows us to describe the behavior of a structure to the

point of resistance is therefore the finite element method. In our case, it is a calculation program for

aluminum alloy (2024-T3) isotropic elastic behavior in a state of plane stress with the software Castem2001.

These deformations are recorded at different amplitudes in figure 3 in parallel induce Von Mises stresses in

the figures 4 and 5. The purpose of the mesh is to discretize the field of analysis so as to associate a further

geometrical formulation. Weibull speculated known as the weakest link, whereby a solid volume V consists

of the juxtaposition of these N samples rupture of the weakest severing the entire solid. Visually spacings

cracks are remarkable in the amplitudes of the deformations are important (10 to 50 seconds), and at the tip

of the crack can clearly see the plasticized zone having residual stress due the gaps, with sharp shapes of

butterflies along the y axis. The other two curve (fig. 6) which register the constraints according to axes X

(SMXX) and Y (SMYY). The method of simulation is made by the energy method G-Θ, with full resolution

J. The program allows us to obtain the dimensions of the plastic zone, and the distance to the crack tip

element on which the finite element gives the amplitude of the equivalent strain after a load operation. The

increased effort in terms of the evolution of plate movement is remarkable, which explains the greater the

thickness of the plate increases the more you need extra effort mainly due to increasing resistance to thick

walls and reinforced that requires that extra effort and load to be deformed. Values of the crack opening

during loading are shown in the figures (see Fig. 7 to fig.14). It is easy to evaluate the deformation locally

by the metal locally measuring its thickness. The evolution can reach 6.63 mm for the largest value of the

crack 5 mm which corresponds to the center of the plate, is a tremendous value but reasonable mechanical

point of view, giving a ductile appearance is a boon to the industry We know that determining the tensile

strength of brittle materials is usually done by a tensile test specimen on a rectangular section. The CTOD

vary depending on the lengths of the cracks, in fig. his variation is registered fig. 10. By analyzing the two

curves in figures 7 and 8, marked the first view is the continued evolution of the CTOD curves according to

yield stress and size of plastic zone. The explanation of the decay curves of the CTOD as a function of

plastic crack lengths involves the phenomenon of hardening due mainly referred to hardening during the

loading operation and the resulting gap in the plastic, it is a phenomenon of hardening mechanism favored

by blocking the so-called dislocation, which are specific configurations of atoms found in all crystalline

bodies. The evolution of CTOD and the size plastic zone is the result to failure criterion is associated with a

critical stress distribution near the crack tip (fig. 8 and 10) will be worth the stress intensity factor equal to

the critical value, or (KI = KIC), other state mode I stress the immediate vicinity of the crack extension. The

physical process of crack propagation evoked, McClintock proposed that the crack is due to the

accumulation of damage in an area around the crack tip to the sudden break. The size of this area of activity

is taken as a fraction of the cyclic plastic zone. The energy is calculate from CTOD variation with three

values of yield stress (250, 450 and 650 MPa), see fig. 11 to 14, but we can see the greet evolution of energy

for a middle value of yield stress (fig. 11 and 12) and diminution to great values of yield stress (fig. 14).

4. CONCLUSION

This work presents an interesting approach to modeling and calculation of spacing of cracks in a plate in

aluminum alloy. The behavior model G-theta isotropic hardening was used. Considering the lateral fissure of

the plate, we have successfully calculated key parameters in fracture mechanics which are the distances

elastic, plastic and critical. By completing the simulation of the plate 2 cracked before and after applying the

load is concentrated together with stresses and strains recorded. For the designer and producer of such

default is driven by all means.


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[31] Yamada Y, Newman Jr JC. Crack under high load ratio condition for Inconel-718 near threshold

behavior. Engineering Fracture Mechanics 2009;76(209-220).

[32] Fellows LJ, Nowell D. Crack closure measurements using Moiré interferometry with photoresist

gratings. International Journal of Fatigue 2004;26:1075-1082.

[33] Chang H, Han EH, Wang JQ, Ke W. Acoustic emission study of fatigue crack closure of physical short

and long cracks for aluminum alloy LY12CZ. International Journal of Fatigue 2009;31:403-407.

[34] Parks DM. A stiffness derivative finite element technique for determination of elastic crack tip stress

intensity factors. International Journal of Fracture 1974;10:487-502.

[35] Hwang CG, Wawrzynek PA, Ingraffea AR. On the virtual crack extension method for calculation the

derivatives of energy release rates for a 3D planar crack of arbitrary shape under mode-I loading.

Engineering Fracture Mechanics 2001;68 (7):925-947.

[36] Temmar M., Khati M., Sellam M., study of the ductile-fragile transition welding effects on mechanical

properties and microstructure evolution of 7075T6 aluminium alloys. International Review of

mechanical Engineering (IREME) November 2010 Vol. 4, N.6 : 755-760.

[37] Remach B., Senthilvelan, Statistical modeling of Auminium based composites and aluminium alloys

using desigh of experiments. International Review of mechanical Engineering (IREME) November

2010 Vol. 4, N.7 : 833-839.

[38] Budiman H., Omar M.Z., Jalar A. Effect of slope length to the sphericity of A356 aluminium alloy.

International Review of mechanical Engineering (IREME) November 2010 Vol. 4, N.7 : 840-845.

Please cite this article as: Hannachi Mohamed Tahar, Djebaili Hami, N. T. Makanjuola, (2013), Analysis of The Elastic Energy and Crack Tip Opening

Displacement With Increased Yield Stress, Journal of Science and Engineering, Vol. 1(2), 163-172.

GUIDELINES HANDBOOK 2013

ORIC PUBLICATIONS

1

Guidelines Handbook 2013

www.oricpub.com

Oric Products

Journals

eBooks

Thesis

Proceedings

2

About us

ORIC Publications, a broad-based open access e-publisher, publish in all fields of Science in both book and journal format. It was founded on two key tenets: In addition to publish the qualified researches, provide a rapid turn-around time possible for reviewing and publishing. It is the vision of ORIC Publications to publish without financial restriction to readers using the open access model of publication. We strongly believe that the open access model will spur research across the world especially as researchers gain unrestricted access to high quality research articles.

Our goal at ORIC Publications is to provide an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Sciences.

We think ahead, move fast to meet international standards and promote quantity and quality of inventive products, and mutually beneficial international partnerships have established us as a trusted supplier and pioneer in the information age.

Submission

Authors are invited to send their manuscripts (written in English) as Word files to the journal editorial office to e-mail address: [email protected]. The manuscripts will be reviewed by our experts (referees). According to their conclusions, the authors will be notified on paper acceptance or rejection; or about expert suggestions on paper revision. If a paper is accepted for publication, the authors should email the corresponding signed copy of the Copyright Transfer Agreement form. File type: MS Word file of the manuscript should be prepared according to the general instructions; we are kindly asking the authors to look through the sample. Besides, please prepare and email to Science and Engineering Journal Editorial Office a copy of the manuscript written in Adobe PDF format.

Guide for Authors

Authors should submit only papers that have been carefully proof read and polished. Before submission please make sure that your paper is prepared using the paper template. This will ensure fast processing and publication. Acceptance or rejection notification will be sent to all authors. The Journal of Science and Engineering invites contribution in the following categories: 1. Original research. 2. Survey/Review articles, providing a comprehensive review on a scientific topic. 3. Fast Communications: Short, self-contained articles on ongoing research. We accept extended version of papers previously published in conferences and/or journals. Submitted papers MUST be written in English. Download the paper template (submitted papers need to be in MS Word format with file extension .doc or .docx).

Preparing the Manuscripts The manuscript should be prepared exclusively in Microsoft Word doc format. Use A4 paper in file settings, set all margins (top, left, right, and bottom) of 1.27cm. Please, check that all paper parts

mailto:[email protected]

http://www.oricpub.com/Template-5.doc




3

(figures, tables, equations, etc.) are within these margins. For details on other than the textual materials see the below section of the guideline. Format of Research Articles: Research articles present original research and address a clearly stated specific hypothesis or question. Papers should provide novel approaches and new insights into the problem addressed. A research article should divide into the following headlines:

1. Title page 2. Author's information 3. Present address 4. Abstract 5. Keywords 6. Introduction 7. Materials and Methods 8. Results 9. Discussion 10. Acknowledgments 11. References 12. Tables 13. Figures

Format of Review Articles: Review articles are an attempt by one or more authors to sum up the current state of the research on a particular topic. Ideally, the author searches for everything relevant to the topic, and then sorts it all out into a coherent view of the "state of the art" as it now stands. Interested scientists may write their review articles under the following headlines:

1. Title page 2. Author's information 3. Keywords 4. Present address 5. Abstract 6. Text 7. Acknowledgments 8. References 9. Tables 10. Figures

Format of Short Communication and Letter: A short communication is for a concise, but independent report representing a significant contribution. Short communication is not intended to publish preliminary results. It should be no more than 2500 words, and could include two figures or tables. It should have at least 8 references. Scientists may prepare their short communications under the following headlines.

1. Title page 2. Author's information 3. Present address 4. Abstract 5. Keywords 6. Introduction 7. Materials and Methods 8. Results 9. Discussion 10. Acknowledgments 11. References 12. Tables 13. Figures

4

Title Page The title of the paper should be concise but informative. This title should be written with all capital: Times New Roman 14 font. The name by which each author is known, with his or her institutional affiliation. This also should be written with normal style including the name, address and affiliation and current email address of all authors: Times New Roman 12 font. Abstract and Keywords The submission should carry an abstract of no more than 250 words. Below the abstract authors should provide, and identify as such, 3 to 10 keywords. Please use Times New Roman 10 font for abstract and keywords. The Headlines of Original Research Textbody (Please use Times New Roman 12 font with single line spacing). Introduction State the purpose of the article and summarize the rationale for the study or observation. Give only strictly pertinent references and do not include data or conclusions from the work being reported. Materials and Methods Describe clearly how you carried out your study. Results and Discussion Present your results in logical sequence in the text, tables, and illustrations. Conclusion Emphasize the new and important aspects of the study and the conclusions that follow from them. Link the conclusions with the goals of the study but avoid unqualified statements and conclusions not com-pletely supported by the data. References References should be subsequently numbered by Arabic numerals in square brackets, e.g. [1,3,5-9], following the sample style below: Conferences: [1] Last, F. M., & Last, F. M. (Year). Article title. Conference Name, pp. Page(s). Journals: [2] Last, F. M., & Last, F. M. (Year Published). Article title. Journal Name, Volume(Issue), pp. Page(s). Books: [3] Last, F. M., & Last, F. M. (Year Published). Title. City: Publisher, Year.

Join us

Propose a NEW Journal We welcome proposals for new journals in all areas of science, technology, and medicine. If you are interested in starting a new journal to provide a home for an emerging field of research or simply want to provide a fast publishing and an open access alternative to existing journals, submit your proposal for launching of a new journal. Also you can serve at the journal as chief editor or editor. For any queries, please contact us at [email protected].

Become a Reviewer A double blind, impartial peer reviewing process is executed on every submitted original research paper/ review papers. The aim of review process is to make an appropriate and timely decision to adjudge, whether a submission, should be recommended for publishing or comments/suggestions to improve level of research suggested. The reviewing process may take one to two weeks. ORIC will be pleased to accept services of experts in all fields of science and engineering as referees. If you are interested in fulfilling this vital role we would be very pleased to hear from you. Suggested names of other potential reviewers for us to approach are always welcome. Reviewers are listed alongside Editorial Board members in the journal. Reviewers are an essential part of any journal's success, ensuring that the papers published are of the high quality. In fact, a Journal cannot meet


5

international standards without renowned and devoted peer reviewers. We expect from one to fulfill following criteria before applying to become a reviewer:

1. One should hold Ph. D. degree or MSc with 3 years research experience. 2. Have at least 5 international publications. 3. Have paper review experience relevant to his/her area or at least should be familiar with

reviewing process. If you want to join us as a reviewer, please email your CV and Reviewer Application Form (doc), (or) Reviewer Application Form (pdf) to: [email protected]. Your application for peer reviewer will be forwarded to the authorities to adjudge. It may take near about two weeks to complete the process. Benefits of Reviewers

1. Reviewers can request an appreciation certificate for reviewed papers. 2. The names of all the colleagues who reviewed papers are included in the journal website. 3. Reviewers are listed alongside Editorial Board members in related published journal volume. 4. Reviewers who write clear, detailed comments and judge a significant number of papers may be

appointed as editorial board. 5. 50% Discount on Publishing. 6. Free of charge for corresponding authors.

http://www.oricpub.com/Reviewer%20Application-Form.doc

http://www.oricpub.com/Reviewer%20Application-Form.pdf


6

EBOOK

ORIC PUBLICATIONS

Welcome, Authors!

ORIC publishes eBooks in both academic and general categories.

Academic group covers all areas of science. ORIC offers fast and at

minimal cost publications. Although the editors will edit your book, it

takes less than two months. ORIC publishes and distributes your book

to millions of potential readers. Don’t worry about formatting your

manuscript. We will turn your manuscript into a book.

You keep all rights

Ready (in less than two months) 4-6 weeks.

ISBN assigned to eBooks

Copyright registration service

THESIS PUBLICATION Electronic thesis publication Do you want to complete your PhD or MSc thesis and do you think about publishing your thesis as an online book? With our thesis publishing services, we provide you with a professional looking thesis which will be made available online for worldwide visibility.

1. ORIC publication is open access and your thesis will be available to anyone in the world to download / read for free directly from the website.

2. Your thesis will be accessible from Google Scholar and etc. 3. Our publications are online and therefore there are not any

limitations on the number or size of the pages. 4. Each thesis will receive an ISBN number.

-How to publish?

1. Send your original work in Doc and PDF formats. 2. Send us the filled Copy Right form. 3. If your work has been published elsewhere, you have to send

Permission/ Consent or Request letter to us for re-printing / publication.

4. All information and contact details of corresponding authors will be included in our press release service.

5. If English is not the first language of authors, they are advised to have their article edited by a native English speaker before submission.

6. A submission that does not comply with our requirements will be rejected.

7. Submissions must be supported by an ethical statement on behalf of all authors. This should be included in the submission covering letter with the corresponding author taking responsibility for having consulted with all the authors.

EBOOK

Academic Category: Area Studies, Arts, Audiology and Hearing Science, Behavioral Sciences, Bioscience, Built Environment, Communication Studies, Computer Science, Development, Studies, Earth Sciences, Economics, Finance, Business & Industry, Education, Engineering & Technology, Environment & Agriculture, Environment and Sustainability, Food Science & Technology, Geography, Health and Social Care, Humanities, Language & Literature, Law, Mathematics & Statistics, Medicine, Dentistry, Nursing & Allied Health, Museum and Heritage Studies, Physical Sciences, Politics & International Relations, Reference & Information Science, Social Sciences, Sports and Leisure, Tourism, Hospitality and Events, Urban Studies and etc.

General Category:

Religious, Poetry, Story

and so on.

How to Submit

You can email to

[email protected] for

any query related to

book publication.

Thesis Submission Email:

[email protected]

Please specify "Thesis

Publication" in subject

line.


7

CUSTOMERS’

PERCEPTION

TOWARD CELLULAR MOBILE

TELEPHONE OPERATORS

BOOK DESCRIPTIONS Given the importance of customers’ perception in telecommunication

business and the recent development of cellular phone business in

Malaysia, a critical research agenda have arisen that requires attention

of understanding the perception of consumers towards operators and

the factors those are influencing in the choice of the providers. The

research has set as its objective in the discovery of the influencing

factors of customers’ perception in their decision-making towards

purchasing mobile phone line, to determine services information for

formulating customers’ perception of the mobile phone operators…

AUTHORS

Dr. Muhammad Sabbir Rahman

Prof. Ahasanul

Haque

Prof. Sayyed Ismail Ahmed

For questions regarding methods of payment please contact: [email protected]

ISBN: 978-0-9895590-0-3 PRICE: 25 USD

ISBN: 978-0-9895590-0-3 Publisher: ORIC Publications Pages: 255 Publication Date: 17-06-2013



8

Upcoming Products:

The Lost Gem

Three Short Stories Author(s): Prof. Wangari Mwai ISBN: TBD Publisher: ORIC Publications Pages: 255 Publication Date:

Development and Validation of

Chromatographic Methods

Analytical Methods for the Estimation of Paracetamol, Domperidone and Tramadol Hcl in Bulk and Pharmaceutical Dosage Form Author(s): E. M.Patelia ISBN: TBD Publisher: ORIC Publications Pages: 88

Editorial Board

Bădescu Gabriel

Bensafi Abd-El-Hamid

Faraj A. El-Mouadib

Ghalib Y. Kahwaji

Lamyaa Gamal Eldeen Taha

Moinuddin Sarker

WaheedSabri

ZakariaZubi

Reviewers List

Aissat Sahraoui

Amir Samimi

Atta Oveisi

Basim Obaid Hassan

Bharath K N

Djamel Bensahal

Foued Chabane

Hannachi Mohamed tahar

Hassan Jafari

Idris El-Feghi

Kamlesh Kumar

Majid Zarezadeh

Mehdi Gheisari

Mohammad Gudarzi

Okba Belahssen

Said Benramache

Umar Sidik

The journal stimulates the exchange and sharing of knowledge and best

practice in all fields of engineering science and technology including:

Mechanics, Civil, Electronics, Computer science, Material science,

Industrial Engineering, Chemical Engineering, Energy, Agricultural

Engineering, Aerospace, Nuclear Engineering and alternative

technologies. As the Journal is international in scope, papers dealing with

state-of-the-art developments in various nations, or comparative studies

of engineering fields in several countries will be accepted.

SE Journal

[email protected]

www.oricpub.com/hssr-journal

ORIC Publications

[email protected]

www.oricpub.com

Benefits of publishing with SE:

Fast peer-review and publishing process

A rigorous double-blind peer review process to ensure

complete impartiality.

Indexing and abstracting by various open access sources

Shortly after acceptance for publication, the article is published

on the journal’s website.

Your paper will be published less than 15 working days after

submission (If it is accepted by referees).

Guaranteed quality - peer review managed by qualified

international reviewers.

All content is free

High readership visibility


is an open access journal which will

deliver timely information online to

all professionals and expertise

involved in basic and/or applied

engineering research. It will fulfil this

role by rapidly publishing a range of

peer-reviewed original or extended

papers, including:

• Research papers

• Reviews

• Communications

©Copyright by ORIC Publications http://www.oricpub.com



http://www.oricpub.com/hssr-journal


http://www.oricpub.com/

Editorial Board

Hakan Akyildiz

Istanbul Technical University,

Istanbul, Turkey

Ming-Jyh Chern

National Taiwan University

of Science and Technology,

Taipei, Taiwan

Tzyy-Leng Horng

Feng Chia University,

Taichung, Taiwan

Taro Kakinuma

Kagoshima University,

Kagoshima, Japan

Long Lee

University of Wyoming,

Wyoming, USA

Sam Syamsuri

Adhi Tama Institute of

Technology, Surabaya,

Indonesia

Nima Vaziri

Islamic Azad University

Karaj Branch, Karaj, Iran

Design of offshore structures; Subsea engineering; Ocean energy

systems; Offshore engineering; Naval architecture; Marine structural

mechanics; Safety and reliability; Computational fluid dynamics; Port

and waterfront design and engineering; Underwater technology;

Geotechnology; Ocean mining; Coastal engineering; Marine

environmental engineering; Ocean acoustics; Oceanographical

engineering; Buoyancy and Stability; Ocean modeling and Natural fluid

systems.

OEFR

[email protected]

www.oricpub.com/j-oefr

ORIC Publications

[email protected]

www.oricpub.com

Benefits of publishing with OEFR:

Fast peer-review (about one month) and publishing process

(less than 2 weeks after acceptance), Indexing and abstracting

by various open access sources, guaranteed quality (peer

review managed by qualified international reviewers), High

readership visibility.

Ocean and Environmental Fluid

Research (OEFR) provides an open

access medium for the publication of

the original research and

development work in a range of fields

relevant to ocean engineering and

environmental fluid mechanics. Some

of the main topics include: Wave

mechanics; Fluid-structure

interaction; Hydrodynamics; Floating

and moored system dynamics;


Ocean and Environmental Fluid Research




Editorial Board

Alexandros Psychogios

Arzu Şener

Monoranjan Bhowmik

Muhammad Sabbir Rahman

Namita Rajput

Syed Iftikhar Hussain Shah

Broad Areas

Anthropology, Business

Studies, Communication

Studies, Psychology,

Philosophy, Corporate

Governance, Criminology,

Crosscultural Studies,

Demography, Development

Studies, Economics,

Education, Ethics,

Geography, History,

Industrial Relations,

Information Science,

International Relations, Law,

Linguistics, Library Science,

Media Studies, Methodology,

Political Science, Population

Studies, Public

Administration, Sociology,

Social Welfare, Linguistics,

Literature, Paralegal,

Performing Arts (Music,

Theatre & Dance), Religious

Studies, Visual Arts, Women

Studies

The journal is published in online versions including:

• Research papers

• Reviews

• Communications

As the Journal is international in scope, authors of several countries

are welcome from all fields which have relevant to the humanities

and social sciences.

HSSR

[email protected]

www.oricpub.com/hssr-journal

ORIC Publications

[email protected]

www.oricpub.com







Human and Social Science Research

(HSSR), is an academic open access,

peer-reviewed, interdisciplinary and

online journal. The purpose of the

journal is to publish scholarly work in

all aspects of humanities and Social

Sciences defined in the classical sense

that is in the social sciences, the

humanities, and the natural sciences.


Human and Social Science Research

Benefits of publishing with HSSR:

Fast review process and publication

Publishing in a ranked journal

Your paper will be published less than 15 working days

after submission (If it is accepted by referees).

Guaranteed quality - peer review managed by qualified

international reviewers

All content is free

High readership visibility




Broad Areas

Anatomy, Physiology,

Biochemistry, Pharmacology,

Pathology, Forensic medicine,

Microbiology, Community

Medicine, Ophthalmology,

Otorhinolaryngology,

Internal Medicine, General

Surgery, Paediatrics,

Obstetrics and Gynecology,

Orthopedics, Psychiatry,

Radiology, Pulmonary

Medicine, Dermatology and

Venereal diseases, Infectious

Diseases, Anaesthesia,

Cardiology, Diabetes, Cancer

research, Endocrinology,

Urology, Neurosurgery,

Geriatric Medicine,

Gastroenterology, Neurology,

Nephrology, Dentistry and

Medical education. Animal

Research, Free radical

biology, Immunology,

Infertility, Hematology,

Medical Genetics, Laboratory

Medicine, Medical Statistics,

Biotechnology and Nursing.

MSPH welcomes contributions in these fields in the form of:

Research papers

Reviews

Communications

Case reports

The Journal seeks to provide its readers with the highest quality scientific

information published through a process of careful peer reviews and

editorial comments. All publications are in English.

HSSR

[email protected]

www.oricpub.com/j-med-sci-pub-health

ORIC Publications

[email protected]

www.oricpub.com







The Journal of Medical Sciences and

Public Health (MSPH), is a bi-

monthly, an editorially independent

and interdisciplinary journal

published by ORIC and aims to be a

publication of international repute

for reporting international adventures

in all areas of the medicine and

medical sciences.


Medical Sciences and Public Health

Benefits of publishing with MSPH:

Fast peer-review and publishing process A rigorous double-blind peer review process to ensure complete

impartiality. Indexing and abstracting by various open access sources Shortly after acceptance for publication, the article is published on

the journal’s website. Your paper will be published less than 15 working days after

submission (If it is accepted by referees). Guaranteed quality - peer review managed by qualified international

reviewers. All content is free High readership visibility




Documents

Journal of Science and Engineering-Volume 1