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ASPECTS OF GRAPHIC METHODS APPLICATION INMANAGING BUILDINGPROCESSES

Jonas Zemkauskas1, Lionginas iupaila2, Ryt irien3

1Vilnius Gediminas Technical University, Sailtekio al.11., Vilnius, Lithuania,

E-mail: [email protected] Gediminas Technical University,E-mail: [email protected]

3Vilnius Gediminas Technical University,E-mail: [email protected]

Abstract. Calendar work planning can be presented in calendar or network graphs. The main information in calendargraph is presented visually, and in network one it is located in auxiliary documents. However, there are possible

calculations of different optimization variants (duration, resources, outage) in network graph. Contemporary

information technologies enable reduction of weaknesses of network graph by applying extra data technologies andgraphical methods. Graphical methods for initial data preparation, situation analysis at a particular time moment and

practical management of the graph are under consideration.

Keywords: Computer graphics, Network diagram; Project management; Graph layout algorithm; Modelling thegraphical extend data; AutoCAD; VisualLISP

1. Introduction

Planning is one of the most important stages ofproject and work realization. Working plans can be

presented in different ways. One of them is the sequence

of works and their interdependence shown by network

graph. It is one of effective methods in solving calendar

planning problems which first were used in the USA. In

1958 a group of scientists created so called plan

evaluation and review technique Program Evaluation

and Review Technique (PERT). In spite of this fact in

practice there is not a small number of programme

software, calendar methods of work management are still

applied. It can be influenced by a rather difficult and

handy way of creating schemes and their management

possibilities.

One of the most important challenges of projectmanagement arising in wishing successfully control a

large project is proper creation of project work calendar

plan and its convenient viewing. Constantly changing

programming possibilities enable to enlarge the influence

of graphics methods in management and analysis of the

process itself. The following problems in the article are

solved in a new way:

initial data management;

analysis and optimization of a working situation(resources, idle time, work risk, etc.);

presentation of information in a graphical form (atany stage).

In spite of the possibilities of a network diagram, its

application has not expanded an the scale as it was hoped

at the time of its creation. The reason can be a quite

complicated mechanism of its formation and not clear

connection with time what is presented in an expanded

calendar diagram. The study of practical application

improvement is carried out in the works of Engineering

Graphics Department postgraduates (example. [1]),

where the created basic programme is incorporated into

the general solving environment of engineering graphics

problems TAIGRASI [2, 3].

Graphical methods can be used in elimination of

application shortcomings. The main accent of solution issymbiosis and analysis of graphical elements with

additional information and presentation in a graphical

form.

2. Initial data management

The initial data for a network diagram consists of

the work title, its duration and sequence and also

resources. The work duration and resources are usually


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determined by additional calculations, and sequence is

determinated according to the execution running.

Forming the data block, the text is written down the inter,

connections of which are determined interactively.

For making calendar plan the network graph form

the following is important:

Event coding. An event number reduplication isunwished. According to the network graphcalculation methods, the number of the final event

should be bigger than the number of the starting

one.

Open contour. A closed contour should not beformed in a network model. This happens when a

mistake is made in work technological dependence.

Presentation of nonfactual works. The usage of thisarbitrary element enables correct visualization of

particular work dependence on one or few works.

To implement these requirements an advertence and

knowledge of initial data formation are needed especially

if a complex management process is planned. An

interactive data input method is usually used which is

implemented in this work. In this case all information ispresented by user, but even in the interactive method

there is a possibility to rationalize some stages. In the

presented example (Fig. 1) you can see that initial data ofgraph formation consists of work code, work name, work

duration, work priority. Such kind of table is usually

fulfilled by most common data management system (for

example, MS Excel Fig. 1).

Fig 1. Data input with MS Excel

That is a common variant and its application doesnt

provoke any problems because management of such kind

of system is included in elementary computer literacy.

However, disadvantages arise if correction of data is

needed, so application of adapted systems is morerational as they make data management more

comfortable and protect from accidental mistakes.

A building object is projected using drawings;

therefore a certain graphical system is necessary. The

most popular computer aided design system currently is

AutoCAD, so it would be handy to manage the biggest

part of processes by this system. It is possible to do

because AutoCAD has some programming languages.

Auxiliary systems (for example, MS Excel) can also be

used, but that will complicate the problem because data

is filed in another system and they have a tendency to be

constantly modified. That raises additional relationship

problems during updating. Modification problems

become not so important when adapted supplements are

generated; because fewer amounts of systems are used in

the process and management more comfortable can be

created (Fig. 2). In adaptation case all actions needed for

data input and management are encoded like separatecommands in corresponding buttons Data correction,

Delete and others.

Fig 2. Adapted data input

Hereby only simple adaptation enables to solve theproblem of comfortable work, though the problems of

priority and work list formation are still not solved. The

priority is especially relevant at the educational stage andin application of up-to-date technologies, which can have

particular limitations. In addition, an advance work list is

possible and therefore its desirable. The list should be

only modified and adapted for particular case. We

suggest two variants for solution of these questions:

Visual graphical model (applied in construction;when building construction process is modeled in

an interactive way; the process is automatically

transferred in to initial data file);

Textual heuristic model (the sequence ofparticular process is fixed in textual list by aproficient expert; later this list is loaded into

adapted dialog box (Fig. 2) and corrected by adding

work duration and resources).

Connecting data of spatial model visualization or

data of heuristic database with calculations of work

amount according to the model (Fig. 3), automatically

prepared initial data for network graph modeling become

available.

Fig 3. Initial data model

Both variants are under consideration and

realization in the works of Engineering Graphics


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Department postgraduates. We hope the main problems

of initial data management in network graph formation

will be solved in this way, and application of graphics

will take a proper place both in educational and industrial

processes.

3. Graphs management parameters activation

There are some popular methods of project calendar

visualization: Gantt graph, PERT diagram, network

graph [4-7]. There are possibilities of realization and

comparison of some critical way calculation strategies in

a network graph [5]:

Common (traditional) calculation of critical way; Calculation of critical way according to

indeterminacy method with possibility to choose

optimistic, pessimistic or the most probable

scenario.

Analyzing network graph, it is possible to get evenmore benefit, which enables to evaluate the project risk

more precisely and to predict possible problems early.

Thereto some additional analytical functions are

required:

Time resources determination for works, which arenot in critical way. The works which do not dependon the critical way can be late for some period of

time and do not determine all project process. But it

is very important to determine precisely what time

reserve a particular work has works, which have

relatively little time reserve, also have a higher risk

degree. Changing of circumstances such works can

become critical ones [5].

Determination of the earliest and latest dates ofevents.

Analysis of resources needs (workers, equipment):

for the whole project; for any time moment;

Determination of requirement peak for eachresource;

Determination and elimination of resourcesoutages;

Finding of works with the highest risk (according tocriticality, resource demand and duration);

Project optimization in regard to time (allowingoverextend of resources);

Project optimization in regard on resources(prolonging duration).

Network planning and managing method was and is

has been the most effective one, though it was invented

in the middle of the last century. According to thismethod the projects are analyzed like a net of

accomplished work events. Looking for the optimal

solution to accomplish these works, three variants are

possible:

1) the most probable, optimistic,2) the most improbable, pessimistic,3) the most optimal or critical way.Network graph reveals wide possibilities to apply

different methods of mathematical analysis numerical,

graph theory and others. However, depending on the

method and network graph specificity, application of

those methods brings specific problems. This is the

analysis of critical way, demand of resources and works

risk.

There are a lot of algorithms in references for

finding of critical way in network graph. But before

applying them some aspects should be estimated [6]:

in certain circumstances there can be more than onecritical way in a graph;

calculations should be provided with indeterminatenumbers according to the logical rules of

indeterminate numbers;

an algorithm should be effective enough, and evenprocessing a big amount of works (over 100) the

calculation of a critical way should not make user

wait for too long;

it should be possible to calculate a critical waybefore drawing a graph in order to visualise the

works of the critical way by different graphicalprimitives;

an algorithm should work even in presence offictional works, the duration of which equals tozero.

While planning resources by the existing methods

in a network graph some aspects should be estimated,

because not all the methods can be applied for some

particular purpose or can provide not correct results:

overextending of resource should be permissible; the problems related to resources information

saving into file should be solved;

if indeterminate numbers are used, works durationand time resources can change depending on work

risk evaluation;

resource can be assigned to some works which areexecuted simultaneously and in diagram can exist

works which do not have any resources at all.Executing outage analysis, the network graph

should be converted into a flat structure similar to that

used in Grannt graph in order to identify the

simultaneous works more comfortably.

Executing works risk analysis it is important to

choose a proper expression of risk coefficient which

should reflect not only work criticality according to its

presence in critical way and time reserve, but also its

resource demand and relationship with other works. It is

also important to evaluate that in formulas should be

used relative number, but not absolute expressions (for

example, 6 day time reserve is very long for work of 5

day duration, but it is short for work of 50 day duration).

It is also important to observe and explore how varypositions of works and risk coefficients vary when

changes in diagram are made, because works influence

each other, and changes of one work parameters can have

unexpected influence on the status of other works [7].

There are some ways of network graph realization:

stringed [8], method of circles and spacing [9], layered

algorithms [10], calculations in fuzzy logic method [11]

and others.

Expressions of heuristic calculations of network

graph can be easy realized in a program way using LISP


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programming language [12, 13], the versions of which

are included into AutoCAD [14] graphical system. For

example, ascription of additional data to graphical

element Visual LISP, which enables to automate the

analysis, is realized in the following way:

(while kod

(progn

(textscr)(princ "[Ciklo Nr.")(princ ii)(princ"

]")(princ)

(setq tipas(atoi (getstring T"\t Aplikacijos vardas ->:\n

\t0 - Papildymo pabaiga

\t1 - Parametras 1

\t2 - Parametras 2

\tN - Parametras n

\t - ?:")))

(if (= tipas 1)(setq apl_var "Parametro_1_aplikacija")

(if (= tipas 2)(setq apl_var "Parametro_2_aplikacija")

(if (= tipas N)(setq apl_var

"Parametro_n_aplikacija"))))

(if (or (= tipas 0)(= tipas " "))(setq kod nil)

(progn

(setq papild(getstring T (strcat "\n veskite duomenis

aplikacijai"apl_var" ?:")))

(if (= papild "")(setq papild "Duomenu_nera"))

(terpri)(princ)

(setq papild_tipas(getstring (strcat "\n

Aplikacija"apl_var" tekstin ?:")))

(if (= (ASCII papild_tipas) 0)(setq papild_tipas "T"))

(if (= papild_tipas "T")

(setq darinys(list apl_var (cons 1000 papild)))

(progn

(setq papild (atof papild))

(setq darinys(list apl_var (cons 1040 papild)))) )

(if (not (assoc -3 prad_duom))

(progn

(regapp apl_var)

(setq nauj_duom(append prad_duom (list (list -3

darinys))))

(entmod nauj_duom)

(setq prad_duom nauj_duom))

(progn

(setq sen_duom(assoc -3 prad_duom))

(setq nauj_prid(append sen_duom (list darinys)))

(setq nauj_duom(subst nauj_prid sen_duom

prad_duom))

(regapp apl_var)

(entmod nauj_duom)

(setq prad_duom nauj_duom)

)))))

(setq ii (+ ii 1))

)

Network graph is used for process management, so

its view should be comfortable for analysis and

informative. Comparing a calendar diagram (Fig. 4a)with a network graph (Fig. 4b) the difference of

information is obvious. The calendar diagram is directly

related to time scale, and work names, its place and

duration in the process can be seen, which is only

partially reflected in the network graph (Fig. 4b).

a)

b)Fig 4. Shapes of diagrams. a network, b calendar

Besides in a calendar diagram reserves and critical

works cannot be seen though these parameters are very

important in practical process management. As to

implement that in a calendar diagram is tricky, we offer


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to improve network graph in order to make it comfortable

for usage. We consider the visualization tasks the

following ones:

critical works of network graph to interconnect withtime scale (Fig. 5);

Fig 5. Interconnected diagram

to present information about particular date state(works, resources Fig. 6a);

to present information in any section (date, works,resources Fig. 6c);

to present information about indicated work (Fig.6c);

The solution of tasks is possible by interconnecting

graphical elements with additional data and executingautomatic analysis according to the model presented in

Fig. 7. The visual elements of network graph is event

(marked with circle which is divided into four parts

wherein (1) event number, (2) the earliest event time, (3)

the latest event time, (4) event time reserve) and work(line, which is drawn from the previous event to next

event and has a name).

As analysis is executed by a graphical system which

modifies drawings, there is a great number of

possibilities to visualize current information presentation

using working drawings (For example, on the 9th

of July2007, at 3 p.m. bricklayers works on axis 15-15 on the 5

th

floor; fitters work between axes 1-5 on 4th

floor, etc., Fig.

8).

Fitters Bricklayers

Fig 8. Drawings in management process

The evolvent of work for particular date in which all

works, materials, workers and equipments are presented

enables facilitation of resources order and

implementation control (Fig. 9).

Under the necessity there is a possibility to print (for

example Order form of materials, prescription for

taskmaster and other).

Fig 9. Evolvent of process of day

a) b)

c)

Fig 6. Diagram data: a resources, b work, c data ofsection

Fig 7. Diagram management model


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Information system provision consists of initial data

preparation, which can be interactive or automatic,

diagram shape formation and visualization, additional

information attachment and reading for graphical

elements and formation of analysis data (report

presentation Fig. 10)

Application of AutoCAD graphical system enables

management from pull-down menu (Fig. 11)

4. Summary and future perspectives

Graphical and program possibilities of computer

science highly changes methods of engineering tasks

solution, which become more and more obvious, enable

variability, operative and comfortable processmanagement. Pending network graph application

distinguishes for:

applying heuristic databases it is possible toevaluate and transfer the experience what enables

avoidance of mistaken solutions even if the user is

not highly qualified;

application of graphical methods makes planningprocess visual, what is very important at the

educational stage;

communication of additional data with graphicalelements enables to provide versatile automatic

process analysis and on that basis to realize

material-technological provision.

The solution of task by one system (in this case

AutoCAD) has the following advantages:

1) network graph in methodical way is related to workdrawings of object, therefore they can be used not

only in construction but also in management process

as well;

2) the problems related to modification of differentsystems do not arise, what is unavoidable applying

some different data management systems;

3) the interface of network graph management does notdiffer from interface of drawing realization;

4) data preparation can be related to graphics ofproject;

5) all data is located in one graphical file (if the userdoes not request otherwise), consequently, the

possibilities of losing information between different

data files become lower.

References

1. Stonkus, A. Aspects of network diagram application inindustrial process management // Masters final thesis,

2005, 58p.2. iupaila, L. Applied graphics in building engineering (in

Lithuanian). Vilnius: Technika, 2002. 326 p.3. iupaila, L. Management of graphics (inLithuanian).Vilnius:Technika, 2005. 226 p.

4. Feng Tse Lin, Critical Path Method in Activity Networkswith Fuzzy Activities Duration Times, Department of

applied Mathematics, Chinese Culture University

5. A Guide to th Project Management Body of Knowledge,Project Management Institute, 2004, [irta 2007-01-10]Prieiga per internet: http://www.pmi.org

6. R. Klein, PROGRESS: Optimally solving the generalizedresource-constrained project scheduling problem, 2000,

p.467-488

7. K. Neumann, Active and stable project scheduling, 2000,p.441-465

8. Gabriel Valiente, Advanced Graph Algorithms, TechnicalUniversity of Catalonia, 2003.

9. Hyun Woo Kim, Kyoung Jun Lee, Criteria of Good ProjectNetwork Generator and Its Fulfillment Using a DynamicCBR Approach, 2004, Nr.11, p. 630-644.

10. Kalanta St., Taikomosios optimizacijos pagrindai. Tiesiniudavini formulavimas ir sprendimo metodai. Vilnius,Technika, 2003

11. Sofjan H.Nasution, Fuzzy critical path method, IEEETransactions on systems, man, and cybernetics, vol. 24,No. 1., 1994.

12. iupaila, L. Technologies of Applied graphics (inLithuanian).Vilnius:Technika, 2007. 180 p.

13. .. Visual LISP AutoCAD. .: X- 2006. 576 .: .

14. .. AutoCAD2007 . .:X- 2006. 348 .: .

Fig 10. Diagram of information provision

Fig 11. System management

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