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A 3D-printing based learning
Stefan Andrei, PhD
Associate Professor and Chair
Presentation, Lamar University, 201611/17/2016 1
Summary
Innovative ways to learn and teach
3D Printing technologies
Designing 3D artifacts for learning and teaching
Engaging students, staff, and instructors in the 3D-
printing based learning and teaching at Lamar
University
11/17/2016 Presentation, Lamar University, 2016 2
Innovative ways to learn and teach The collaborative way of learning, where children sit around a
table to work out a problem together
(http://www.bbcactive.com/BBCActiveIdeasandResources/Innov
ativeteachingmethodsvsthetraditionaluni.aspx).
The use of educational video during lectures, which has
transformed the engagement levels of students and has created
a greatly enhanced learning experience
(http://www.bbcactivevideoforlearning.com/).
Tom Drummond, University of North Carolina at Charlotte,
compiled a list of 12 best practices for learning and teaching
concepts (http://teaching.uncc.edu/learning-resources/articles-
books/best-practice/instructional-methods/best-practices-
summary)
11/17/2016 Presentation, Lamar University, 2016 3
Drummond’s 12 best practices1. Lecture Practices: effective ways to present new information
orally to fit differences in learning styles.
interaction with audience, questions, surveys, explanations, stories
2. Group Discussion Triggers: effective ways to present a
common experience to engage a group in a discussion.
short readings, individual task review, case studies
3. Thoughtful Questions: effective ways to formulate questions
that foster engagement and confidence.
descriptions, reflections, analogies, predictions, justifications
4. Reflective Responses to Learner Contributions: effective
ways to establish mutually beneficial communication by
reflective listening.
paraphrase, parallel personal comment
11/17/2016 Presentation, Lamar University, 2016 4
Drummond’s 12 best practices (cont’d)5. Rewarding Learner Participation: effective ways to support
learner actions with well-timed, encouraging positives.
avoid praise, description, narration, self-talk
6. Active Learning Strategies: effective ways to foster active,
constructive participation.
construction spirals, rounds, brainstorm, writing in class, concept
models, simulations/games, peer teaching, question pairs, examinations
7. Cooperative Group Assignments: ways to assign formal
cooperative tasks.
5. team member teaching, team effectiveness design, poster sessions
8. Goals to Grades Connections: establish a logical agreement of
goals and objectives, flowing to measures of performance,
criteria, and grading.
grades are referenced to criteria, requirements are detailed in writing
11/17/2016 Presentation, Lamar University, 2016 5
Drummond’s 12 best practices (cont’d)9. Modeling: represent openness, continuous learning, and trust.
openness to experience in the here and now, incorporation into oneself
of the process of change
10. Double Loop Feedback: facilitating mutual awareness of how
one learns to learn.
objective description of physical reality, culturally accepted meaning,
judgments and personal reality
11. Climate Setting: regulate the physical and mental climate.
meet the learner's needs for physical comfort and accessibility, define
negotiable and non-negotiable areas, clarify the instructor's role, and the
learner's role as members of a learning community
12. Fostering Learner Self-Responsibility: allow learners to plan
and evaluate much of their learning.
involve learners in mutual planning, involve learners in formulating their
learning objectives11/17/2016 Presentation, Lamar University, 2016 6
https://www.sculpteo.com/blog/2015/11/17/3d-
printing-in-education-from-elearning-to-emaking/
Learning by making has a long established story in education,
and thanks to 3D Printing this educational principle makes a real
come-back (November, 2015).
Introducing 3D Printing into classrooms changes both the way
students learn and the way educators teach.
Every professor using a 3D printer in the classroom or using a
cloud 3D Printing Service has observed:
3D Printing is changing the relationship between students and teachers.
First because 3D Printing technology is new and evolving constantly in
many manners.
There are a limited amount of experts in 3D Printing around the world and
it’s difficult to be aware of every application of 3D printing that takes place.
3D Printing classes are more open to discussion and student contributions
are an important factor of success.
11/17/2016 Presentation, Lamar University, 2016 7
11/17/2016 Presentation, Lamar University, 2016 8
Main idea of Additive Manufacturing
Additive Manufacturing (AM) is a term to describe a set of
technologies that create 3D objects by adding layer-upon-
layer of material, which can vary from technology to
technology, e.g.:
plastic, liquid, metal, powder filaments, sheet of paper, etc.
But the common feature for all Addictive Manufacturing is the:
usage of a computer together with a special 3D modeling software.
So, first thing to start:
create a CAD sketch.
Then:
AM device reads data from CAD file and builds a structure layer by
layer from printing material.
11/17/2016 Presentation, Lamar University, 2016 9
Examples of 3D printers: http://3dprintingfromscratch.com/common/types-
of-3d-printers-or-3d-printing-technologies-overview/
11/17/2016 Presentation, Lamar University, 2016 10
Types of input files1. Standard Tessellation Language (STL) file.
2. Virtual Reality Modeling Language (VRML), a newer digital 3D file
type that also includes color.
3. Additive Manufacturing File Format (.AMF) is a new XML-based
open standard for 3D printing.
4. GCode - this file contains detailed instructions for a 3D printer to
follow for each slice, such as the starting point for each layer and
the "route" that the nozzle or print head will follow in laying down
the material.
5. In addition, 3D printer manufacturers may have their own
proprietary input file formats that contain instructions specific to
the methodology for that make or model, and that are compatible
only with that manufacturer's software.
Note. This does not create a barrier to printing with these machines, as the
proprietary file format is generated from the user's own STL or VRML file.
11/17/2016 Presentation, Lamar University, 2016 11
Free 3D software
1. Google SketchUp
2. 3DCrafter
3. 3Dtin
4. Anim8or
5. Art of Illusion
6. Blender
7. BRL-CAD
8. Creo Elements/Direct - formerly
CoCreate
9. DrawPlus Starter Edition
11/17/2016 Presentation, Lamar University, 2016 12
10. Wings 3D
11. FreeCAD
12. GLC Player
13. LeoCAD
14. Netfabb Studio Basic
15. K-3D
16. OpenSCAD
17. Tinkercad
3DS Max - High-end commercial 3D
modeling tools
1. Alibre - One of the most
affordable CAM programs.
2. AC3D
3. AutoCAD
4. AutoQ3D
5. Cheetah3D
6. Cloud9
7. FormZ
11/17/2016 Presentation, Lamar University, 2016 13
8. Maya
9. Magics
10. NetFabb
11. Rhino3D
12. Solidworks
13. ZBrush
Free STL software:
1. MeshLab:
Open source software for processing and editing of unstructured 3D
triangular meshes.
It also has an extremely fast slide function.
2. Google SketchUp plugin:
A plugin script to import and export STL files for Google SketchUp.
Supports both binary and ASCII import and export.
3. STL-viewer:
Display and manipulate the contents of stereolithography or STL file.
4. Netfabb Studio:
A free Windows program for 3D printing to view, edit, analyze and
repair STL files.
11/17/2016 Presentation, Lamar University, 2016 14
Google: context free grammar for
"standard tessellation language" (STL)
11/17/2016 Presentation, Lamar University, 2016 15
The STL file structure (byte code – 7MB)
11/17/2016 Presentation, Lamar University, 2016 16
The STL file structure (text file – 1.3 MB)
11/17/2016 Presentation, Lamar University, 2016 17
The STL file structure (snippet of text
representation)
11/17/2016 Presentation, Lamar University, 2016 18
solid OpenSCAD_Model
facet normal 0 0 0
outer loop
vertex -12.892 -0.886857 15.3505
vertex -12.8413 -1.22597 15.1614
vertex -13.2 -1.22597 15.1142
endloop
endfacet
. . .
endsolid OpenSCAD_Model
The STL file structure (similar to reverse
engineering) The following Context-Free Grammar can generate the previous
text (Open-Source Computer Assisted Design model):
1. S → solid OpenSCAD_Model Facets endsolid OpenSCAD_Model
2. Facets → Facet Facets | Facet
3. Facet → facet Position Origine OuterLoop endfacet
4. Position → normal | orthogonal
5. Origine → X_origine Y_origine Z_origine
6. X_origine → Number
7. Y_origine → Number
8. Z_origine → Number
9. OuterLoop → Vertex_A Vertex_B Vertex_C
. . .
11/17/2016 Presentation, Lamar University, 2016 19
The STL file structure (reverse engineering)
. . .
10. Vertex_A → vertex A_coord B_coord C_coord
11. Vertex_B → vertex A_coord B_coord C_coord
12. Vertex_C → vertex A_coord B_coord C_coord
13. A_coord → Number
14. B_coord → Number
15. C_coord → Number
16. Number → IntegerPart . FractionalPart
17. IntegerPart → Digit | IntegerPart Digit
18. FractionalPart → Digit | Digit FractionalPart
19. Digit → 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
11/17/2016 Presentation, Lamar University, 2016 20
Is reverse engineering legal?
In the U.S., Section 103(f) of the Digital Millennium
Copyright Act (DMCA) (17 USC § 1201 (f) - Reverse
Engineering) specifically states that it is legal to
reverse engineer and circumvent the protection to
achieve interoperability between computer programs
(such as information transfer between applications).
Interoperability is defined in paragraph 4 of Section
103(f).
11/17/2016 Presentation, Lamar University, 2016 21
Popular 3D printers technologies
1. Stereolithography (SLA)
2. Fused Deposition Modeling (FDM)
3. Selective Laser Sintering (SLS)
4. Selective Laser Melting (SLM)
5. Electronic Beam Melting (EBM)
6. Laminated Object Manufacturing (LOM)
7. Bio Printers (recent technology)
11/17/2016 Presentation, Lamar University, 2016 22
1. Stereolithography (SLA)
This method was patented by Charles Hull, co-founder of
3D Systems, Inc., in 1986.
He then set up 3D Systems Inc to commercialize his patent
(www.3Dsystems.com).
In fact, Japanese researcher Dr. Hideo Kodama first (1981)
invented the modern layered approach to stereolithography
by using ultraviolet light to cure photosensitive polymers.
The process of printing involves a uniquely designed 3D
printing machine called a stereolithograph apparatus (SLA),
which converts liquid plastic into a solid 3D object
(represented as a computer aid design (CAD) file, such as
STL).
11/17/2016 Presentation, Lamar University, 2016 23
The SLA machine and its 3D
generated object
11/17/2016 Presentation, Lamar University, 2016 24
2. Fused deposition modeling (FDM) Fused deposition modeling (FDM) technology was developed and
implemented at first time by Scott Crump, Stratasys Ltd. founder, in
1987.
Other 3D printing companies have adopted similar technologies but
under different names.
A well-known nowadays company MakerBot coined a nearly
identical technology known as Fused Filament Fabrication (FFF).
With the help of FDM you can print not only functional prototypes,
but also concept models and final end-use products (resolution
1/20 per mm).
high-performance and engineering-grade thermoplastic,
very beneficial for mechanic engineers and manufactures.
the only 3D printing technology that builds parts with production-grade
thermoplastics,
excellent mechanical, thermal and chemical qualities.
11/17/2016 Presentation, Lamar University, 2016 25
Similarity with SLA printing method
3D printing machines that use FDM Technology
build objects layer by layer from the very bottom up
by heating and extruding thermoplastic filament.
FDM is a bit similar to stereolithography (SLA).
Comparing to stereolithography, this technique is
slower in processing, but with better resolution.
When printing is completed, support materials can
easily be removed either by placing an object into a
water and detergent solution or snapping the support
material off by hand.
11/17/2016 Presentation, Lamar University, 2016 26
Examples of FDM 3D-printed objects
11/17/2016 Presentation, Lamar University, 2016 27
Benefits to the society FDM technology is widely spread nowadays in variety of
industries such as:
automobile companies like Hyundai and BMW or
food companies like Nestle and Dial.
end-use products, particularly small, detailed parts and specialized
manufacturing tools.
food, drug packaging, and the medical industry.
FDM is used for new product development, model concept
and prototyping and even in manufacturing development.
The most common filaments are:
ABS (acrylonitrile butadiene styrene),
PC (polycarbonate) filaments,
PLA (polylactic acid) made out of corn.
11/17/2016 Presentation, Lamar University, 2016 28
Price ranges
The price for those 3D printers depends on size and
model.
Professional ones usually cost from $10,000 and more.
3D Printers designed for home use are not so expensive.
There are several models like Replicator of MakerBot,
Mojo of Stratasys and Cube of 3D Systems.
The price for these models varies from $1,200 to $10,000.
However, new start-ups offer more and more affordable
versions of FDM 3D printers, the price of which can be just
about $300-$400.
11/17/2016 Presentation, Lamar University, 2016 29
3. Selective Laser Sintering (SLS)
… is a technique that uses laser as power source to form
solid 3D objects.
This technique was developed by Carl Deckard, a student
of Texas University, and his professor Joe Beaman in
1988.
Later on they took part in foundation of Desk Top
Manufacturing (DTM) Corp., that was sold to its big
competitor 3D Systems in 2001.
The main difference between SLS and SLA is that it uses
powdered material in the vat instead of liquid resin as
stereolithography does.
11/17/2016 Presentation, Lamar University, 2016 30
Comparison with SLA and FDM
Unlike some other additive manufacturing processes,
such as stereolithography (SLA) and fused deposition modeling (FDM),
SLS does not need to use any support structures as the
object being printed is constantly surrounded by unsintered
powder.
11/17/2016 Presentation, Lamar University, 2016 31
Example of an SLS 3D printed object
11/17/2016 Presentation, Lamar University, 2016 32
Materials and prices used by SLS
Like all other methods listed above the process starts with
creation of computer-aided design (CAD) file, which then needs to be converted to .stl format by special software.
The material to print with might be anything from nylon,
ceramics and glass to some metals like aluminum, steel or
silver.
Due to wide variety of materials that can be used with this
type of 3D printer the SLS technology is very popular for 3D
printing customized products.
SLS is more spread among manufactures rather than 3D
amateurs at home as this technology requires the use of high-
powered lasers, which makes the printer to be very
expensive.
11/17/2016 Presentation, Lamar University, 2016 33
4. Selective laser melting (SLM)
… is a technique that also uses 3D CAD data as a source
and forms 3D object by means of a high-power laser
beam that fuses and melts metallic powders together.
In many sources SLM is considered to be a subcategory
of selective laser sintering (SLS).
But this is not so true as SLM process fully melts the
metal material into solid 3D-dimentional part unlike
selective laser sintering.
The history of SLM started with German research project
held by group of Fraunhofer-Institut für LaserTechnik in
1995.
11/17/2016 Presentation, Lamar University, 2016 34
The main design of SLM
11/17/2016 Presentation, Lamar University, 2016 35
Example of an SLM 3D printing object
11/17/2016 Presentation, Lamar University, 2016 36
The main idea of SLM printing
The fine metal powder is evenly distributed onto a plate,
then each slice of 2D layer image is intensively fused by
applying high laser energy that is directed to the
powdered plate.
The energy of laser is so intense that metal powder
melts fully and forms a solid object.
After the layer is completed the process starts over again
for the next layer.
Metals that can be used for SLM include stainless steel,
titanium, cobalt chrome and aluminum.
11/17/2016 Presentation, Lamar University, 2016 37
Applications
1. parts with complex geometries and structures with thin walls
and hidden voids or channels.
2. aerospace application for different lightweight parts.
3. tooling and physical access difficulties to surfaces for
machining, as well as restrict the design of components.
4. manufactures of aerospace and medical orthopedics.
11/17/2016 Presentation, Lamar University, 2016 38
5. Electronic Beam Melting (EBM)
EBM is another type of additive manufacturing for metal
parts.
It was originally coined by Arcam AB Inc. in 2001.
The same as SLM, this 3D printing method is a powder
bed fusion technique.
While SLM uses high-power laser beam as its power
source, EBM uses an electron beam instead, which is
the main difference between these two methods.
The rest of the processes is pretty similar.
11/17/2016 Presentation, Lamar University, 2016 39
The main idea of EBM 3D printing
The material used in EBM is metal powder that melts
and forms a 3D part layer by layer by means of a
computer, that controls electron beam in high vacuum.
Contrary to SLS, EBM goes for full melting of the metal
powder.
The process is usually conducted under high
temperature up to 1000 °C.
11/17/2016 Presentation, Lamar University, 2016 40
Prices and applications
Comparing to SLM the process of EBM is rather slow
and expensive, also the availability of materials is
limited.
So the method is not so popular though still used in
some of manufacturing processes.
Currently the most well spread materials that are used
for EBM are commercially pure Titanium, Inconel 718
and Inconel 625.
The application of EBM is mainly focused on medical
implants and aerospace area.
11/17/2016 Presentation, Lamar University, 2016 41
6. Laminated object manufacturing (LOM)
… is one more rapid prototyping system that was
developed by the California-based company Helisys Inc.
in 2013.
During the LOM process, layers of adhesive-coated
paper, plastic or metal laminates are fused together
using heat and pressure and then cut to shape with a
computer controlled laser or knife.
Post-processing of 3D printed parts includes such steps
as machining and drilling.
11/17/2016 Presentation, Lamar University, 2016 42
The main steps of LOM 3D printing
The LOM process includes several steps.
Firstly, CAD file is transformed to computer format, which
are usually STL or 3DS.
LOM printers use continuous sheet coated with an
adhesive, which is laid down across substrate with a
heated roller.
The heated roller that is passed over the material sheet
on substrate melts its adhesive.
Then laser or knife traces desired dimensions of the part.
Also the laser crosses hatches of any excess material in
order to help to remove it easily after the printing is done.
11/17/2016 Presentation, Lamar University, 2016 43
Prices and speed of LOM
Probably LOM is not the most popular 3D printing
method but one of the most affordable and fastest.
The cost of printing is low due to not expensive raw
materials.
Objects printed with LOM can be relatively big, that
means that no chemical reaction needed to print large
parts.
11/17/2016 Presentation, Lamar University, 2016 44
A LOM 3D printed object
11/17/2016 Presentation, Lamar University, 2016 45
LOM Vendors
Currently Cubic Technologies, the successor to Helisys
Inc., is the main manufacturer of LOM printers.
There are not too many companies these days that work
with LOM technology.
Additional vendor: the Irish company Mcor Technologies
Ltd. sells LOM 3D printers.
Their devices are widely being used by artists, architects and
product developers to create affordable projects from usual letter
paper.
The printers that are being sold by Cubic Technologies for
home use are pretty expensive comparing to Makerbot
Replicator or 3D System’s Cube devices.
11/17/2016 Presentation, Lamar University, 2016 46
7. BioPrinting … is the process of creating cell patterns in a confined space
using 3D printing technologies.
Applications:
to print tissues and organs to help research drugs and pills
to incorporate the printing of scaffolds for regenerating joints and
ligaments
Organovo (San Diego, 2007): designs and develops functional,
three dimensional human tissue with NovoGen MMX Bioprinter
(www.organovo.com)
The living test tissues provide researchers the opportunity to test drugs
before administering the drug to a living person.
Inkredible (Sweden, 2015): the first true bench-top 3D bioprinter
with Clean Chamber Technology (http://www.cellink3d.com/)
With a HEPA filtered positive air pressure inside the printing chamber, it is
sure that the bioprinting is sterile.
11/17/2016 Presentation, Lamar University, 2016 47
LU: Recent acquisitions
We recently acquired a MakerBot Desktop 3D Printer
which uses PLA material to be extruded into layers.
We also recently acquired an Inkredible printer.
We have also designed, implement, and test two DIY 3D
printers: Ultimaker and PrntBot
http://galaxy.lamar.edu/~sandrei/Ultimaker/index.html
11/17/2016 Presentation, Lamar University, 2016 48
Makerbot
Replicator Z18
11/17/2016 Presentation, Lamar University, 2016 49
College of Arts and Sciences’ Facebook
11/17/2016 Presentation, Lamar University, 2016 50
Example … of an innovative and unique way for content, mode of
delivery and pedagogy of teaching courses using 3D printed
artifacts.
To the best of our knowledge, all ‘Foundations in Computer
Science’ courses are currently taught like this:
A pushdown automata is a 7-tuple M = (Q, , , q0, Z0, A, ), where Q is a
finite set of states, the input and stack alphabets and are finite sets, q0
Q is the initial state, Z0 is the initial stack symbol, A Q is the set of
accepting states, and the transition function is : Q ( {}) the
set of finite subsets of Q *.
A configuration of a PDA is a triple (q, x, ), where q Q is the current
state, x * is the portion of the input string that has not yet been read, the
contents of the stack is *.
According to the student evaluations and other sources, most of students
struggle to understand this complicated concept (and the configuration
transitions).
11/17/2016 Presentation, Lamar University, 2016 51
Our approach is 3D-model oriented…
The below photos show a group of students explaining the concept
of pushdown automata with the help of a physical 3D printed artifact,
the behavior of a pushdown automata becomes crystal clear (COSC
3302 – Introduction to Computer Theory) – Mr. Tim Gonzales
11/17/2016 Presentation, Lamar University, 2016 52
Student assessment about this concept
While the definition of the pushdown automata looked
complicated, once they’ve seen the 3D printed artifact,
the students have now a very clear understanding and
using the concept of pushdown automata.
11/17/2016 Presentation, Lamar University, 2016 53
11/17/2016 Presentation, Lamar University, 2016 54
Case Study: COSC 5328 Real Time Systems
A game board for Example of slide 5
The below figure shows the scheduling game board representation of this task set at time i = 0.
The x-axis shows the laxity of a task and the y-axis shows its remaining computation time.
11/17/2016 Presentation, Lamar University, 2016 55
Scheduling single-instance tasks with
game board Let C(i) denote the remaining computation time of a
task at time i, and let L(i) denote the laxity (slack) of a task at time i (i.e., L(i)=D(i)-C(i)-S(i)).
On the L-C plane of the scheduling board, executing any n of the m tasks in parallel corresponds to moving at most n of the m tokens one division (time unit) downward and parallel to the C-axis.
Thus, for tasks executed: L(i+1) = L(i), C(i+1)=C(i)-1
Tokens corresponding to the remaining tasks that are not executed move to the left toward the C-axis.
Thus, for tasks not executed: L(i+1) = L(i)-1, C(i+1)=C(i)
11/17/2016 Presentation, Lamar University, 2016 56
Rules for the Scheduling Game Board
Each configuration of tokens on the L-C plane represents the scheduling problem at a point in time.
The rules for the scheduling game are: Initially, the starting L-C plane configuration with tokens
representing the tasks to be scheduled is given.
At each step of the game, the scheduler can move at most ntokens one division downward toward the horizontal axis.
The rest of the tokens move leftward toward the vertical axis.
Any token reaching the horizontal axis can be ignored (it has completed its execution).
The scheduler fails if any token crosses the vertical axis into the second quadrant before reaching the horizontal axis.
The scheduler wins if no failure occurs.
11/17/2016 Presentation, Lamar University, 2016 57
EDF scheduler fails (ex. From slide 5)
Example of two-processor system (n = 2) for three
single-instance non-preemptive tasks:
J1: S1 = 0, c1 = 1, D1 = 2
J2: S2 = 0, c2 = 2, D2 = 3
J3: S3 = 0, c3 = 4, D3 = 4
J1 and J2 have earlier absolute deadline, so they are
assigned to start.
11/17/2016 Presentation, Lamar University, 2016 58
LL scheduler wins (ex. From slide 5)
Their laxities are l1 = 1, l2 = 1, and l3 = 0.
At time 0, J3 has the lowest laxity, so it is assigned to start.
The other one can be J1 (since it has same laxity as J2).
LLF is not optimal Example of two-processor system (n = 2) for six single-instance
non-preemptive tasks:
J1: S1 = 0, c1 = 2, D1 = 2
J2: S2 = 0, c2 = 2, D2 = 2
J3: S3 = 0, c3 = 3, D3 = 6
J4: S4 = 0, c4 = 3, D4 = 6
J5: S5 = 0, c5 = 1, D5 = 5
J6: S6 = 0, c6 = 1, D6 = 5
Their laxities are sorted increasingly: l1 = 0, l2 = 0, l3 = 3, l4 = 3, l5 = 4, l6 = 4.
This is because tasks J1 and J2 will be chosen to be first executed on
processors 1 and 2, respectively.
Then, J3 and J4 will be scheduled for processors 1 and 2, but tasks J5 and
J6 cannot be scheduled because they will miss their deadline of 5.
11/17/2016 Presentation, Lamar University, 2016 59
However, EDF is optimal for previous
example
We re-arrange the jobs according to earliest
deadline first strategy:
J1, J2, J5, J6 ,J3 and J4
This arrangement will lead to a feasible
schedule.
11/17/2016 Presentation, Lamar University, 2016 60
EDF and LLF are not optimal for
multiprocessor non-preemptive case Three-processor system (n = 3) for seven single-instance non-
preemptive tasks:
J1: S1 = 0, c1 = 2, D1 = 2
J2: S2 = 0, c2 = 7, D2 = 7
J3: S3 = 0, c3 = 8, D3 = 9
J4: S4 = 0, c4 = 3, D4 = 6
J5: S5 = 0, c5 = 1, D5 = 5
J6: S6 = 0, c6 = 5, D6 = 12
J7: S7 = 0, c7 = 3, D7 = 11
Their laxities are: l1 = 0, l2 = 0, l3 = 1, l4 = 3, l5 = 4, l6 = 7, and l7 = 8.
LLF assigns J1, J2, and J3 to processors 1, 2, and 3, respectively.
Then J4 is executed by processor 1.
Hence, J5 will miss its deadline.
11/17/2016 Presentation, Lamar University, 2016 61
EDF and LLF do not work for previous
example, but there is a feasible schedule!
EDF assigns J1, J5, and J4 to processors 1, 2, and 3,
respectively.
Hence, J2 will miss its deadline.
But … is the previous task set feasible?
Actually, it is … the feasible schedule is:
First, J1, J2, and J3 to processors 1, 2, and 3, respectively.
Then, J5, J6, and J7 are executed by processors 1, 2, and 3.
Finally, J4 is executed by processor 1.
11/17/2016 Presentation, Lamar University, 2016 62
11/17/2016 Presentation, Lamar University, 2016 63
Causal Order in the Declarative Model
In a concurrent program all execution states
of a given thread are totally ordered.
The execution state of the concurrent
program is partially ordered.
computation step
thread T1
thread T2
thread T3
fork a thread
3D model for teaching the scheduling
problem for multiprocessor platform
11/17/2016 Presentation, Lamar University, 2016 64
Example of two-processor system (n=2) for three single-instance tasks:
J1: S1 = 0, c1 = 1, D1 = 2J2: S2 = 0, c2 = 2, D2 = 3J3: S3 = 0, c3 = 4, D3 = 4
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Case Study: COSC 3308 Programming Languages Concepts
Causal Order in the Declarative Model
computation step
thread T1
thread T2
thread T3
fork a thread
bind a dataflow variable
synchonize on a dataflow variable
x
y
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Nondeterminism
An execution is nondeterministic if there is a
computation step in which there is a choice
what to do next.
Nondeterminism appears naturally when
there are multiple concurrent states.
3D model for teaching the ‘fork and
join’ concept
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In parallel computing, the fork–join
model is a way of setting up and
executing parallel programs, such
that execution branches off in
parallel at designated points in the
program, to "join" (merge) at a
subsequent point and resume
sequential execution.
Bucket Sort and Radix Sort
(COSC 2336 – Data Structures)
All sort algorithms discussed so far are general
sorting algorithms that work for any types of keys
(e.g., integers, strings, and any comparable objects).
These algorithms sort the elements by comparing
their keys.
The lower bound for general sorting algorithms is
O(n · log n).
So, no sorting algorithms based on comparisons
can perform better than O(n · log n).
However, if the keys are small integers, you can
use bucket sort without having to compare the keys.
11/17/2016 68COSC-2336, Lecture 6
Bucket Sort and Radix Sort (cont)
Bucket sort, or bin sort, is a sorting algorithm that works
by partitioning an array into a number of buckets.
Each bucket is then sorted individually, either using a
different sorting algorithm, or by recursively applying the
bucket sorting algorithm.
It is a distribution sort, and is a “cousin” of radix sort in
the most to least significant digit manner.
Since bucket sort is not a comparison sort, the Ω(n · log
n) lower bound is not applicable.
The computational complexity estimates involve only the
number of buckets.
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Bucket Sort The bucket sort algorithm works as follows.
Assume the keys are in the range from 0 to N-1.
We need N buckets labeled 0, 1, ..., and N-1.
If an element’s key is i, the element is put into the bucket i.
Each bucket holds the elements with the same key value.
Given n the number of integers, the worst-case time
complexity of the bucket sort algorithm is O(n).
More precisely, it is n · N · D, where D is the maximum
number of digits of the given integers. You can use an ArrayList or a Bag to implement a bucket.
bucket[0]
Elements
with key 0
bucket[1]
Elements
with key 1
bucket[2]
Elements
with key 2
…
bucket[N-1]
Elements
with key N-1
11/17/2016 70COSC-2336, Lecture 6
Bucket Sort (cont)
Sort 331, 454, 230, 34, 343, 45, 59, 453, 345, 231, 9
230
bucket[0]
331
231
bucket[1]
bucket[2]
343 453
bucket[3]
454
34
bucket[4]
45
345
bucket[5]
bucket[6]
bucket[7]
bucket[8]
59
9
bucket[9]
230, 331, 231, 343, 453, 454, 34, 45, 345, 59, 9
9
bucket[0]
bucket[1]
bucket[2]
230
331
231 34
bucket[3]
343 45
345
bucket[4]
453 454
59
bucket[5]
bucket[6]
bucket[7]
bucket[8]
bucket[9]
9, 230, 331, 231, 34, 343, 45, 345, 453, 454, 59 9
34
45
59
bucket[0]
bucket[1]
230 231
bucket[2]
331
343
345
buckets[3]
453 454
buckets[4]
bucket[5]
bucket[6]
bucket[7]
bucket[8]
bucket[9]
9, 34, 45, 59, 230, 231, 331, 343, 345, 453, 454
11/17/2016 71COSC-2336, Lecture 6
The 3D-printed artifact for bucket sort
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3D LU logo approval
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LU logo, LU nut and bolt, and the
mechanical clock
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Methyl methacrylate (C5H8O2 )
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A medical weekly planner
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Photos taken by Ms. Paula Gregory
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LU cup, cell-phone holder, LU avatar
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Inkredible 3D printer The creators of the INKREDIBLE started their company with
CELLINK, a bioink that has become the most widely used bioink in
the world thanks to its excellent biocompatibility, printability, and
structure that ensures 98% cell viability (study made with RoosterBio
cells at Chalmers University in Sweden) – September 2015.
Another great feature of the INKREDIBLE is its clean chamber
technology.
The printer has a highly filtered air flow with positive pressure
created inside the chamber so it reduces contamination and particle
count inside the printing area basically down to zero.
The bioprinting services that CELLINK provides has been a great
success for many partners and the fact that these partners can
receive cell specific expertise enables for new proprietary tissue
model creation for internal product development testing platforms.
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The newly optimized desktop bioprinter for the
ultimate bioprinting of human tissues and 3D cell
culturing
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Our INKREDIBLE at LU (calibrating and
then printing a human ear) – Mr. Greg Yera
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Less than 4%
universities
worldwide
purchased
BioInkredible.
Wollongong
University in
Australia and
Leading schools
in South Korea
and
Switzerland.
Assembling the Ultimaker 3D printer and
designing 3D-printed artifacts (Mr. Vraj Pandya)
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https://3dprint.com/19305/biobots-3d-
bioprinter/
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The V. W. Keck Printing Center at UTEP
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Future of 3D printing
Richard D’Aveni, The 3-D Printing Revolution. 3-D Printing Will
Change the World, Harvard Business Review-Innovation, May
2015, [available online at https://hbr.org/2015/05/the-3-d-printing-
revolution]
Industrial 3-D printing is at a tipping point, about to go mainstream in a
big way. Most executives and many engineers don’t realize it, but this
technology has moved well beyond prototyping, rapid tooling, trinkets,
and toys.
“Additive manufacturing” is creating durable and safe products for sale to
real customers in moderate to large quantities.
It may be hard to imagine that this technology will displace today’s
standard ways of making things in large quantities. Traditional injection-
molding presses, for example, can spit out thousands of widgets an hour.
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Our plan at LU on 3D printing
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Engaging students, staff, and instructors in the
3D-printing based learning and teaching at LU1. Think for an initial idea of a 3D model with the functionality
described in lecture notes
2. Check the existing databases of 3D models
3. While (prototype needs changes) {
1. Design the 3D software model (e.g., Blender)
2. Print a 3D model, a.k.a., prototype (e.g., Makerbot)
3. Test the prototype, ask feedback from students/colleagues/
collaborators
4. }
5. Collaborate with other departments/universities/institutions
6. Create a database with STL 3D files published under the
Creative Commons License
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Thank you for your attention!
Questions?
Presentation, Lamar University, 201611/17/2016 88