3. Message by Dr. Lee Chiaw Meng, President
"
After three years of hard work you have now success
fully completed your studies and are ready to make con
tributions to society. In design'ing your courses of study,
the College has taken care of the actual needs of industry
and the business world with which most of you will be
associated for the greater part of your working life. The
practical aspects of the course syllabuses and the opportuni
ties you were given to participate in orientation programmes
in industrial, commercial or other establishments are the
main features aimed towards this end. You have also been
educated in bi·lingual environment so essential in a multi
racial society like ours in Singapore. You can be sure, there
fore, that you are placed on a firm footing at the very start
when you step out of College,
Those who graduated before you have obtained mea
ningful employment without difficulty, and you will no
doubt find yourselves in the same advantageous position.
This confidence that the public have placed on us is
most encouraging, and it is for you to up-hold this con
fi dence and the good name of the College.
Principal
Or. Lee Ch iaw Meng
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$ag~it±
3
4. MESSAGE BY MR. PHILlP LIMB
During your time at Ngee Ann you have worked hard,
learnt many thin!Ji and acquired new skills. You are now
fitted to take your place in the skilled workforce of
Singapore. That workforce will need to become more skilled,
so although you have done well, you cannot rest on your
laurels. You will need to continue to learn as you work, and
this will represent a real challenge. I am confident that you
will be able to meet it.
Congratulations on completing your course and my
best wishes for the future.
/1
ILL, U Vice - Principal
Mr. Philip Limb
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10. MESSAGE BY MR. CHAN SlOW POH
Congratulations - your period with us has been re
warded by the successful completion of your course of study.
Recently, some of our "old boys" have visited me
at the College and have mentioned that what they learned
here was not sufficient for them to cope with their jobs.
They said that in view ofthis they would like an opportunity
for further study.
I would like to point out that our main objective is
to provide a foundation which will enable you to embark
on your career with confidence. However, it would be a
fallacy to think that in three years we can equip you to
handle all the problems encountered as a technician engineer.
Experience and knowledge are essential requirements to be
successful in any profession. It is in the working environment
that practical experience is gained, whilst at the same time
further knowledge can also be acquired "if you wi 11 put your
mi nd to the task. It is not al ways necessary that further
".
study must be undertaken in.a formal way. I am confident
that the foundation which we have laid here at NATC will
enable you to pursue any further knowledge through self
HEAD OF MECHANICAL ENGINEERING DEPARTMENT
study.
Mr. Chan Siew Poh
To conclude, may I send you all my best wishes for
the future.
tJL~.If£*£1:f
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11
11. VISITING PROFESSOR/ADVISER
OF MECHANICAL ENGINEERING
DEPARTMENT
Dr. Alan Phillips
;fJL ~ .I tt ~ ± if
( $ E[ )
MESSAGE BY DR. ALAN PHILLlPS
In response to your request for a message, I am taking his skill and technique in the live situation on the road.
this opportunity to convey my congratulations to those
Engineering students graduating for the NATC Diploma. You will, I hope, set forth into industry armed with
the knowledge you have already gained here, but you must
This is for you the cui mination of three years hard go there expecting to find an environment which will test
~
endeavour, studying to attain this award. It is not only a you in many different ways. Industry is a situation in which
test of your ability to learn the essential knowledge which there are many problems to which practical solutions are
will be the foundation for your future career as a technician required. It is in this environment that you will find your
engi·neer but also of your competence to pass the numerous selves and gain valuable experience together with financial
examinations along the way. reward for your la bours.
I feel that an analogy can be made to that of a learner I wish you all well in this new and challenging venture
driver who has just passed his driving test and is given his into the Industrial Society.
certificate of competence. He must now set out to improve
13
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Mr. Kan Siew Tong
i#ViP ( :l: M )
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SENIOR ACADEMIC INSTRUCTOR
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Mr. Soo Kia Hua
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Mr. Chan Puan Jui
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ACADEMIC INSTRUCTOR
Mr. Thong Foo Kong
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CADET ACADEMIC INSTRUCTOR
Mr. Hoon Heng Jow
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Mr. Keith Hargreaves
V.S.O.
AI":. --- VOLUNTEER SERVICE OVERSEAS
SENIOR ACADEMIC INSTRUCTOR
~ Mrs. Christine Tan San Yee
(ENGLISH LANGUAGE UNIT)
%J~~*±
21
21. MESSAGE BY MR. YEH SHOW KUN
Over the last three years you have not really learnt
very much. You have, however, learnt sufficient amount
HEAD OF ELECTRICAL &
to enable you to learn more. What is more important is
that you have now been trained to be able to learn more. ELECTRONIC ENGINEERING DEPARTMENT
Mr. Yeh Show Kun
There is an abundance of knowledge waiting for you.
You can learn something every day, only if you make a
point to learn. You do not learn from the books only. You
It {Jl. & It -f .r- t[
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learn from your work and the people around you.
When you leave the College, you are beginning a new
phase of life. Let it be a fruitful and pleasant one.
) ,~~~}L_(_~
Yeh Show Kun
23
22. MESSAGE BY MR. T.B. RI LEY
VISITING PROFESSOR/ADVISER
I amsure you will feel jubilant now you have qualified. OF ELECTRICAL & ELECTRONIC
hope you agree that your effort was well worth while.
ENGINEERING DEPARTMENT
Congratulations! Now you are in top gear so to speak it
Mr. Riley, Thomas Brian
should be possible for you to maintain the pace in your
next assignment. You have proved your ability yet you 1t~,&.It-=fI.ff-*3:.1f
cannot rest on your laurels. (:tlf.)
• Wherever you go from here contribute while still
learning and set a standard of excellence which will inspire
o'h'" folio";", yo, 'hm"h ,h;, COII'~~
IT.B. RILEY)
25
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28. SENIOR ACADEMIC INSTRUCTOR
Miss Wang Yea Ping
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SENIOR ACADEMIC INSTRUCTOR
Mr. Tang Kee Chi
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29. SENIOR ACADEMIC INSTRUCTOR
Mr. Tan Siak Teng @ Tan Siak Cheok
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SENIOR ACADEMIC INSTRUCTOR
Mr. Sitoh Chong Hon ~
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ACADEMIC INSTRUCTOR
Mr. Tang Kim Seng
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ACADEMIC INSTRUCTOR
Mr. Tan Yew Kin
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TAN YEW TENG
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WANG KOK HENG
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Kluang, Johore,
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46
44. WONG MUI TONG
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132-E, Jalan Alsagoff,
Singapore 14.
YEaH ENG CHIANG
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35, Main Road,
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Negri Sembilan,
West Malaysia.
47
45. YONG CHO YEIT ....
;fh 1£ ~
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Kuala Lumpur,
Selangor,
Malaysia.
"The important thing in life is not
the triumph but the struggle.
The essential thing is
not to have conquered
but to have fought
well"
CHAN KHAM HONG
~* iX *
220, Main Road,
Rengit, Batu Pahat,
"
Johore.
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18·A. Jalan Petua.
Jurong Road gy> ms.
Singapore 21.
48
46. CHIA YONG SIAN
~5R~
25-F, Upper Bukit Timah Road, 7'1.. m.s.,
Si ngapore 21.
"Success is counted sweetest
by those who never succeed
to comprehend a nectar
requires sorest need"
CHUA YAP SOON
• l1f jlWi
2-A, Jalan Merbah,
Batu Pahat,
,) Johore, Malaysia.
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49. L1M CHENG HOCK
*JR;f&
Chop Kean Seng,
Talang, Kuala Kansar, Perak, Malaysia.
''The twin purposes of education
inspiration and information."
L1M ENG SENG
* ~fi] ~
Blk. 43, 1030-G,
Bendemeer Road,
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Singapore 12.
A
52
50. LYE SHOON KONG
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NG YOO K KOONG
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CHUA CHUAN HONG
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56. ""
GOH KONG LING
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864, Penda Maran,
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LEE CHING YEEN
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85. By Wong Kok Heng/Mechanical Engineering
ADAPTIVE CONTROL
When we say that we have something "Under Control" employed in industry could be increased substantially, with
... we mean that we know what we intend to do, and are
confident that we can see that it does. Therefore, any
very considerable imporvements in the profitability of
machine shops. This is particularly true of batch production
control system will have the essential features, as follows: shops employing numerically controlled machines. It is
believed that conventional machines take too much time
(a) There is a plan. on toolssetting and work accuracy will be depending on
(b) We prepare to carry out that plan. specified geometry and operator skill. Numerical control
(c) We compare what is being done to what is being aims to overcome this by specifying component geometry
done to what is being planned at all time. on a tape which then operates the machine automatically.
(d) Instructions would be 'feedback' when any deviation Since feedrates are also specified on the tape, job durations
occured and we return to the plan. are more accurately forecast at the planning stage.
Hence, the essence of any control system is this The metallurgical properties of workpieces which
constant 'feedback' of instructions so as to correct any influence acceptable maximum machining rates are unpre
deviation from plan. Everytime the control system detects dictable and variable. Cutters are subjected to· variations.
deviations, it sends instructions back to the control, and Since cutting speeds are determined by the planner before
corrective measures would be taken immediately on receipt the event, machining rates with numerical control must
of these instructions. make adequate allowance all the time because no metal is
homogenous throughout. This raises limitation on the ulti
INPUT J .1
INPUT CONTROL
... UNIT -- PROCESS rOUTPUT mate economics of numerical control, and put forward the
question of ADAPTIVE CONTROL.
CORRECTIVE I
j
ACTION
In recent years, great emphasis has been placed on
optimum machining. However, to successfully achieve this
',," JFEEDBACKJ-. goal presents many difficult problems. The latest and most
promising approach has been adaptive control.
Fig.1 FEEDBACK PRINCIPLE.
The work "adaptive" is borrowed from biology which
abounds with examples of adaptive system. A person makes
It is generally accepted that the metal-cutting rates .a fairly rapid move from sea level to 10,000 ft. altitude,
87
86. experiences some discomfort the first day, due to the rather Obviously, under any of these conditions, a conven
substantial decrease in oxygen. However, the adaptive con tional feedback control system is no longer indifferent to
troller of his body go into automatic operation, and in a variations, and system performance soon degrades to-beyond
matter of a few days, the oxygen-carrying capacity of the acceptable limits.
blood is raised to suit the body in the new environments.
If the altitude change had occured so slowly that adaptive There are always at least two elements that always "
processes had kept pace with the changes, then the period appear in some form in adaptive control systems.
of discomfort would be avoided.
(1) Identification - - - which refers to the measurement
In a broad sense, any system in which a parameter is of the dynamic characteristics of the process to be '"
adjusted to counteract a degradation in performance, controlled.
brought a bout by a change in the system's environment
could be called adaptive. In this sense, there are hundreds (2) Actuation - - - which signifies the generation of
of adaptive control systems in present-day operation. Al an appropriate actuate signal, which in turn modifies
most every jet-aircraft fuel control is temperative com the adjustable characteristics.
pensated, for example.
Identification is probably the most important aspect
of adaptive control, and is the central element of such a
system because adaptivity implies frequent, automatic, and
t rapid solution of the identification problem.
JNPUTS CONTROLLING control 110UTPUTS
ELEMENTS signals lPROCESS I ..... And Actuation acts upon information about the
present system performance, and the desired or optimum
performance, to decide what corrective measures to take,
Adjustment Signals and to determine the required controller characteristics. It
also acts upon the decision taken, and initiates the required
IDEAL STRUCTURE OF ADAPTIVE CONTROL. modification so as to drive the system towards the optimum.
In the metal-cutting industry, the concept of adaptive
An adaptive control system is required when a con control means that the tool can react for the optimum
ventional controller cannot work. For example, a controller advantage to unpredictable changes in cutting conditions.
might be required to compensate for such things as: An operation usually selects speeds on the conservative side
(a) Changes in the process transfer function, or in para to avoid risking damage to the part on machine. Adaptive
meter value, with changes in its environment, example control, on the other hand, responds to the actual cutting
an aircraft's transfer function changes with air speed, conditions. When the tool is sharp and the workpiece not
height, air pressure, temperature etc. too difficult to machine, the speed will be high, but as the
tool becomes dull or hits hard spots the automatic control
(b) Changes in the system itself, example wear, mechanical
will cut the speed back to suit the cutting conditions. In
failure.
this way optimum production rate can be maintained.
88
87. Initial speeds and feeds do not have to be carefully 3) 'Proceedings' of IEEE. 1840, July 1970.
chosen. Sensors, usually based on spindle torque, tool 4) Handbook of Automation, Computation and Control.
vibration and tool tip temperature, will feed the required
1)
By Eugene M. Grabbe
information back to the performance measurement com
puter. The computer calculates the metal removal rate, tool
vvear rate, and surface finish. When this information is
received, the controller will modify the initial feed and
speed to opti mize the overall machining performance.
There are disadvantages to adaptive control which
must at all times be borne in mind. Generally, an adaptive
control is necessarily complex and expensive. It should be
remembered that adaptive control can hardly be justified,
and should not be used unless parameter variations are wide
and unpredictable.
position
Programmed commands
N. C. machine output
feeds, speeds, System . tool
& tool positions corrected
feed and speed
sense
Feed & speed parar
correction (vibr
"'"' ADAPTIVE I-- torql
CONTROLLER tip-t l e
etc.
ADAPTIVE CONTROL SYSTEM
~
Reference:
1) System Identification For Self-Adaptive Control.
By W.D.T. Davies
2) System Engineering Handbook.
By Robert E. Machol
89
90. You Are
Dreaming!
1st Roku-Roku N.C.
Machine Around.
A Hydraulic
Copying Machine
93
91. Gas Cutti ng of Pi pes Blind Man Detecting Refrigerant Flow
Gas Turbine Engine
Anything Funny!
»
,
, i;}0
?:>o
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~,
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(I (M. loG. Welding)
95
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93. Not sure . . . . .
Refer to the Procedures
Again.
Let's Check and See.
Designers
At Work.
Ol.l{ ShOOIf!d
CI.lP
.)
se~lCfI~ Electronic Workshop
. n aflO Practice
~ eS'("
97
94. Graduation Souvenir Committee
So Hong Hin
Chiew Chong Yow
Chio Che Ooi
Yeo Siang Kiang
Chairman
Editor (English)
Editor (English)
Editor (Chinese)
Koh Han Chuan
Hong Hock Chuan
Ong Tiam Teck
Tan Chai Heng l
Asst. Business Manager
Circulation Manager
Asst. Circulation Manager
Business Manager
Chan Kham Hong Lee Hing Guan
Lee Hoon Lai Ng Yook Koong
General Officer Treasurer Auditor
Photographer
10'2
95. ACKNOWLEDGEMENTS
We wish to express our sincere thanks to the following The members ot the staff of the Mechanical En
for helping us with the Graduation Souvenir. gineering and Electrical and Electronic Engineering Depart
ments for their co-operation.
The following for their messages.
The Students' Union and the Electrical & Electronic
Dr. Lee Chiaw Meng, Principal, Ngee Ann Technical
Engineering Society for their financial aids.
College.
Mr. Philip Limb, Vice Principal, Ngee Ann Technical
All our contributors and advertisers.
College.
Mr. Chan Siew Poh, Head of Mechanical Engineering
All those who have assisted in one way or another to
Department, Ngee Ann Technical College.
make this publication possible.
Dr. Alan Phillips, Visiting Professor/Adviser of Mec
hanical Engineering Department, Ngee Ann Technical
And to all those whom we have inadvertantly left
College.
out.
Mr. Yeh Show Kun, Head of Electrical and Electronic
Engineering Department, Ngee Ann Technical College.
Thank you.
Mr. Riley, Thomas Brian, Visiting Professor/Adviser
of Electrical and Electronic Engineering Department,
Ngee Ann Technical College.
103