29/8:

hihi 3 2, this is 1, one of the Fyp student doing decentralised vibration control, umm its regarding some fyp thingy, both me and 2 was wondering if we can meet up on thursday to clarify some doubts regarding our project, please get in touch with us if u can make it on thursday

Fu1...90297880

t1ks for everything:)

p/s: paiseh have to trouble you:P

30/8:

2 & 1,

sorry... i was a bit harsh on my words just now...let's check thro' our tasks:

Structural characteristics: max transmitted force & deformation experienced (using response spectra method) --> let's do separately & compare

Actuator: stroke>Dmax & Fa~=Fmax --> we select actuators accordingly

Matlab: both the CD & software on Monday

Labview: contact e other FYP w/i manual --> sign up with Mr Sit --> use Labview tutorial (also Internet for introduction)

Network sharing (start-->find-->Computer-->y2h7x2):use the files shared on network (I'm not closing my PC over e weekend) --> for Matlab (Quek eg.) goto --> FYP2002 --> Examples --> 30/8

let's meet up on Monday 2pm ... to discuss the structure frame & to use Matlab (it's easy to pick up) to calculate & plot dynamic responses

2/9:

2, remember to bring along e CD (on Control) I lent u last week ... the frame stiffness K needs static condensation technique (inside the notes with the e.g.) to reduce to SDOF ... how's ME & EE contacts ... how's Labview?

1, pls read up on LQR control (Quek's notes) ... e Matlab CD & manual is here (it requires nearly 500MB of space after installation) ...

5/9:

2 & 1, let's keep this straight ... your internal email should not come to me or the supervisors ... my batch tried it before ... & e consensus is that all programs, codes & results should not be email ... but only presented conscientiously during meetings ... remember e weekly meeting is not some FAQ .. but a c1ce to train your focus that is invaluable for thesis writing & presentation skills

6/9:

1, I checked your codes for uncontrolled responses ... only 2 errors:

"ode.m" should be named "ex101sys.m": same as the function name

"interpl" should be "interp1": 1 (one) @ back

On the network (y2h7x2 --> FYP2002 --> LQR --> Continuous time folder), I provide 2 sets of codes:

ex101.zip: corrected code for uncontrolled responses

excont1.zip: Quek's code for controlled (LQR) responses [try different weightings Q,R]

The benchmark problem is a rather complex one in that u need Matlab & Simulink skills plus LQR/LQG knowledge. In addition, the structure is "bilinear", hence we need consider two separate linear models with control gain Ki for each one.

I'll print out the benchmark paper for u. to access soft copy: goto y2h7x2 --> Bencmarks --> NLbench_seismic.pdf

let's meet on Monday (3pm). In the meantime, try out LQR & use Matlab textbook for plotting (plot, subplot): shown in Zip files.

2, u need to perform the following:

Labview headstart: Edgar (woman) around this week only, your friends & Labview tutorial

Structure: there is also a rod @ shake-table, we can use the same response spectra method to calculate Fmax & Dmax

Actuator capacity: u need both the material data specifications (Fuji specs & Quek's paper) & piezoelectric relations to calculate the piezo force actuation capacities (I have e relations, so I try working it for u as a rough estimate)

Sourcing: actuator requires calibration set-up (piezo is like concrete --> poor in tension --> normally requires pre-compression, done in Kamada 1997/8) --> the set-up can be like the one @ Annie air-con room

Sensor: although actuator is important, prepare for sensors - their properties, set-up & how Goh Kok 5 uses different sensors for different uses

For now, concentrate on learning Labview (I/O interface) & actuator sourcing & calibration.

2, I have compiled a collection on piezo materials ... plus constitutive relations (needed to calculate max actuation stress [sigma] & electric field E) ... look @ piezo constitutive.doc first ... interesting websites are also available

if the constitutive relations looks confusing ... reduce to scalars .. then apply piezo accordingly ... can use Excel .... another alternative is that we directly test Annie's actuators ... then we try fitting in the relationships

9/9:

2, a Labview compilation

11/9:

2 & 1, here are a compilation of useful journals & books that u might need ... they are all available in our library as well as Internet ...

For useful Internet journal sites, goto y2h7x2 --> favourites --> publications (lots of publishers' sites with abstracts of all current journals ... very useful)

2, this is a very relevant site for piezo actuators ... everything from material, fundamentals, calibration & usage:

http://www.physikinstrumente.com/tutorial/

also see how e benchmark researchers set-up their experiments:

http://www.nd.edu/~quake/facilities/sdceel.html

1, here's a short write-up on benchmarks

10/9:

5 4...

I left the book at home.

I will return it to you tomorrow.

I am learning labview under Eagar's guidance.

And as for the setting up of the experiment, shall I have a short discussion with you, tomorrow?

2

-----Original Message-----

From: Lai 5 4

Sent: Tue 9/10/2002 12:32 PM

To: Ooi Shein 2

Cc:

Subject: Ogata book

2, i need the Ogata textbook (Prentice Hall) on linear optimal control ... if u have it, pls return me ASAP, thx

-----Original Message-----

From: Lai 5 4

Sent: Friday, September 06, 2002 9:46 PM

To: Ooi Shein 2

Subject: RE: Project update

2, I have compiled a collection on piezo materials ... plus constitutive relations (needed to calculate max actuation stress [sigma] & electric field E) ... look @ piezo constitutive.doc first ... interesting websites are also available

if the constitutive relations looks confusing ... reduce to scalars .. then apply piezo accordingly ... can use Excel .... another alternative is that we directly test Annie's actuators ... then we try fitting in the relationships

14/9:

i apologise for my harsh comments ... let's re-train our focus on the project:

1,

objective: to realise (verify all formulations) numerically with robust LQR controller for the benchmark problem (Ohtori et al 2001)

intermediate step (tools): verify controller parameters for a SDOF bilinear system, then 2DOF & dynamic condensation

2,

objective: to realise (make SDOF set-up work) experimentally with robust LQR controller using piezoelectric sensors & actuators (Kamada et al 1997)

intermediate step (tools): Labview interfacing, actuator sourcing & calibration

Lai,

objective: To control dynamic response of an unbraced frame under ground excitations with parametric uncertainties and bounded disturbances for minimal energy requirement & optimal stable performance using a network of independent decentralized subsystem controllers, each with sensors and force-inserting stacked actuators

intermediate step (tools): structural knowledge, modern control knowledge, robust reliable controller (for FYP), adaptive controller (for non-linear systems), unification (of both controllers), verifications

20/9:

2, like to suggest the following procedure:

Check the formulations: response spectrum method (Fmax), Kamada bending moment control (my report - theoretical)

Calibration set-up: set a +ve sign convention for entire system; no need for shaking (not use shake table), mount the actuator(s) [note the nos. of actuators used, locations, their actuation directions]

Calibration requirements: actuation capacity (<10V with factor of safety: set at least 2) - need to investigate actuator failures, so more actuation required; (N/V) graph - {how many volts (V) to nos. of actuators at their locations, in their actuation directions in order to produce how many lateral shearing force (N) on the lumped mass}

Accelerometers: need to measure & interface

also, note the time delays: (1) between sending volts (V) to actually producing intended lateral shearing force (N) on the mass; (2) time between sensor pickup time & interface period

1, like to put forward the following remarks:

Plots: responses (x,vel,acc) & controls (u) with labels (weights used)

Counter-check & try calculate controlled acc: (1) same stiffness for bilinear model, (2) different stiffness

Resonance control: fix 2*pi*f=w=wn=sqrt(K/M) --> fix M --> derive K, then simulate: (1) uncontrolled, (2) controlled linear, (3) controlled bilinear

MDOF: how modal analysis (or mode superposition method) works --> how to control each mode (using Wang et al)

From benchmark (Ohtori et al 2001), pick the uncontrolled modes & characteristics of floor locations (bottom, middle, top) --> derive SDOF wn --> investigate the optimal parameters for LQR controller to use for each type of SDOF

Model reduction: compare Qu (dynamic condensation) & Ritz

23/9:

1, i realise that for acceleration responses, researchers & practioners are concerned only with the absolute acc. ... as the absolute acc. is the acc. at the DOF ... which directly affects occupants' safety & mec1ical excitations .... hence, plots (relative x, relative vel, abs acc., controls)

In benchmark, the relative x (=abs displacement of DOF - ground displacement) is not that important also, what matters is the relative drift storey drift (which is difference between relative x of lower DOF with relative of upper DOF) .... take note

2, like to point out the following:

Calibration set-up: to measure the actuation force (Fa) --> use either load cell or accelerometer (only for dynamics, not statics, since acc. in static=0)

Sensors: for accelerometer, when U stick it on the mass, & it is dynamic, the accelerometer output is volts (V) --> u need to calibrate the accelerometer to find its sensitivity: (g/V) which is how many volts (V) from the accelerometer is actually how much acceleration (in g or m/s/s) of the mass

Actuators: need to derive transmitted DOF actuated force (N) for input voltage (V) --> derive (N/V)

Shake table: i have done a short write-up here ... Mr Sit (Justice?) told me we can arrange for all of us (u, Liow Zee Ping & me) to learn the safe operation of the shake table from either Mr Koh or Mr Ow(l?) ... when both u & Liow are ready to use the shake table ... pls contact them & let me know when ... i like to learn with u all ... hopefully the transfer function iteration method works better t1 double integration

26/9:

2 & 1, i'm attending the seminar below & would be late for the meeting, u go ahead with Prof Ang:

2, there's a conference proceedings that has a lot of piezo. materials suitable for u on my table ... yellow cover ... just take it (but return to Central library yourself) if i'm not around ...

27/9:

I found quite a bit of piezo journels. Their discussion on piezo is much more clearer t1 the one in the text.

Me also contacted piezo supplier in Singapore and the one in Japan. And spoke to ur colleague on some piezo stuff. Haven't got to know piezo as an expert but much better now.

Soon, I will refabricate the cantilever beam myself.

Hopefully by end of next week we can test the piezo on the cantilever structure SDOF.

T1ks for the piezo info, will get it from you tomorrow.

2

28/9:

hihi 5 4

Actually i finished all the bilinear thingy comparison with the uncontrolled structure

and i have managed to derived the acceleration for the bilinear too

Plus i have also done matlab on controlled linear and uncontrolled and controlled linear subjected to resonance and bilinear subjected to resonance....

infact i have done many senarios and found that i have too much datas that i havent studied in precise....

so this week , i have a talk with prof ang and prof quek and so we agree that the pace should be made slower so that i can go into the details and they also mentioned that it i have to do it in such a way that i dont miss out the details and that it can be possible that the thesis eventually end up only solving for 1 dof and 2 dof (using LQR as the control algorithm) depending on the speed cause they dun want me to rush into the benchmark unless im pretty sure of wat im doing

But i have in the past week also read up on the notes of MDOF from prof queks notes and have returned the first set plus ur library book to u :)

its on your table:)

This week i will be analysing the graphs that i have chunk up and will ask prof quek regarding any discrepancy:)

Oh by the way i also have informed Prof Quek about your seminar thingy liaoz

-----Original Message-----

From: Lai 5 4

Sent: Fri 9/27/2002 4:21 PM

To: Lee Foo 1

Cc:

Subject: Summary of yr studies

1, can u email a summary of what u have studied in this week & what's to be studied next week?

28/9:

1, it's great that u have progressed a lot, but consolidation is as impt. Take the supervisors' advice ... plus for acc. plot only the abs acc. = rel. acc. + EQ ... just add the EQ into xdot (rel acc.) for all time steps ... when u r ready for LQR, u can approach me to intro u to robust reliable LQR

29/9:

1, study LQR properties thoroughly .. both simulating & formulating ... understand inside out .. outside in ... then we'll go into robust & reliable

-----Original Message-----

From: Lee Foo 1 <[email protected]>

To: Lai 5 4 <[email protected]>

Date: Saturday, September 28, 2002 8:21 PM

Subject: RE: Summary of yr studies

Is there a big difference between the LQR and the robust reliable LQR?

I thought our subject was to investigate if the structure can be control using LQR?

cause im moving towards that direction for my FYP

Do advise me for this cause the prof seems ok that im inverstigating the LQR

2/10:

1 & 2, i'm have attend a seminar on Fri ... pls go ahead w/i supervisors

Intelligent Transportation Systems Applications in Singapore

3/10:

1, how's it going? ... can we meet up earlier tomoro ... around 2.40p.m. ... like to intro u to a new layered control ... it chains up two or more separate LQR controls ... s.t. they perform tracking (remember regulation -->0, tracking is non-zero) ... see u

2, can u email abt yr work & plans after tomoro's meeting ... e schedule that i drew up for u is only tentative ... can modify it anytime ... pls inform me of c1ges

4/10:

always prepare contingency ... always backup the lastest successful program ... then work on a copy of that, instead of the original ... come earlier around 2.30 ... it doesn't sound big ... probably just coding errors on FFT & bilinear interfacing ... fundamentals should be sound

-----Original Message-----

From: Lee Foo 1

Sent: Thursday, October 03, 2002 10:26 PM

To: Lai 5 4

Subject: RE: friday meeting

got bigbig problem

its regarding the algorithm

I was checking on some small details after finishing deriving the FFt when i realise that the bilinear portion of the algorithm cannot work

Am still cracking my head...........See u tomorrow at 2:40pm

...............im drowning.........

5/10:

2, Prof Ang told me that we have to check our static calculation from response spectra method with dynamic response ... i think he means to carry out a dynamic response for all time steps using methods like Newmark-beta method & Runge Kutta method ... u can either carry out the evaluation using state space evaluation ... 1 knows this ... or u can use time-stepping method like Newmark which i have ... both are equivalent ... check that the peak dynamic response is smaller or equal to response spectra method

-----Original Message-----

From: Ooi Shein 2 <[email protected]>

To: Lai 5 4 <[email protected]>

Date: Saturday, October 05, 2002 1:34 AM

Subject: RE: friday meeting

Yup yup.. I brought it to school today but I've forgotten to return it to you.

Will be on ur table tomorrow.

T1ks

cheers

2

-----Original Message-----

From: Lai 5 4

Sent: Fri 10/4/2002 4:18 PM

To: Ooi Shein 2

Cc:

Subject: RE: friday meeting

2, remember to return e NLB book ... on materials engineering .. thnx

8/10:

Dear 5 4:

Hi... I have some questions to consult you.

It is mainly about the formulation of dynamic equation. I worked out the relation between actuating force and the response of the structure but it is not corrent as a static solution is not adequate or not correct to be precise... according to Prof Quek.

Anyway, can I see you this afternoon... may be about 5pm?

As for my plan for fyp, I will explain it to you later.

t1ks & regards

2

-----Original Message-----

From: Lai 5 4

Sent: Sat 10/5/2002 6:21 AM

To: Ooi Shein 2

Cc:

Subject: Re: friday meeting

2, Prof Ang told me that we have to check our static calculation from response spectra method with dynamic response ... i think he means to carry out a dynamic response for all time steps using methods like Newmark-beta method & Runge Kutta method ... u can either carry out the evaluation using state space evaluation ... 1 knows this ... or u can use time-stepping method like Newmark which i have ... both are equivalent ... check that the peak dynamic response is smaller or equal to response spectra method

-----Original Message-----

From: Ooi Shein 2 <[email protected]>

To: Lai 5 4 <[email protected]>

Date: Saturday, October 05, 2002 1:34 AM

Subject: RE: friday meeting

Yup yup.. I brought it to school today but I've forgotten to return it to you.

Will be on ur table tomorrow.

T1ks

cheers

2

9/10:

Ok

5 4 .. t1ks for the support:)

will look into it next week...have a test on coming monday ...need to strive for it:P

u take care and if u ever have a c1ce to find ur specs...heehee dun forget to inform me:P

...stay cheerful....1

-----Original Message-----

From: Lai 5 4

Sent: Wed 10/9/2002 3:53 PM

To: Lee Foo 1

Cc:

Subject: Syntax error corrected

1, just a syntax error (how u specify the command parameters):

a = fscanf(fid,'%i')

should be:

a = fscanf(fid,'%g')

g: floating-point, which is anything other t1 integer (i)

2, we can use wave propagation ... remember geology earthquake ... Chew Soon Hoe ... P-wave velocity Vp ... S-wave velocity Vs ... then these vibrations due to applied actuation/seismics travel thro' combination of Vp & Vs to reach the lumped masses ...

now ... refer to Kamada et al 1997, once u apply Mo(t), assume dynamic for generality, ... how does this deformation travels to the extreme ends? ... 1 way (not e only way) is thro' wave propagation (Tam Tiam Soon) ... we can 1st order wave propagation to estimate the dynamics

Here, i provide here a paper (Berryman 2001) ... focus on eq (1-2) is enough .. then Chew's notes on Vp & Vs .. plus our structure (M,C,K) ... u can arrive @ actuation transfer dynamics

11/10:

2, take note of e following when u test e piezo:

According to Jin Jing, a piezo patch breakdown voltage (when any more voltage has no actuation effects & piezo is spoilt) is abt. 100V per 1mm thickness of piezo patch

Pre-compression: needs to be > the max piezo expansion @ max -ve voltage s.t. piezo does not have net tension (brittle in tension like concrete)

Pre-compression also c1ges the piezo structure --> N-V graph would be different

If need be, u can test it past the 10V limit, but might have non-linear N-V & hysteresis

Wiring: approach those with experience how best to attach wires to the piezo. & in what directions

Actuation direction: +ve voltage (expansion or contraction) & -ve voltage

Voltage sequence: start 0, 0+dV,0+2dV...Vmax,Vmax-dV,Vmax-2dV,...,0,-dV,-2dV,...-Vmax,-Vmax+dV,...,0

N-V graph: actuation force (N) vs. actuation voltage (V) --> if suitably linear, then we can use a constant (N/V) ratio for both experimentation & simulation --> similar to Kamada's paper: 19.6kN/100V

Stroke insignificant: indept. due to our force-equilibrium calculations

Insufficient actuation force: either put in more actuators or put in a bigger, more powerful actuator

13/10:

2, like to request the following:

As the piezo properties c1ges with precompression (since induced piezo strain is non-zero, in the constitutive equations), for each precompression applied, (N-V) graph would be different.

Hence, each (N-V) graph should have the following labels:

type of actuator

precompression applied

piezo dimensions (esp. thickness)

plus any others should be included

16/10:

Hi... 5 4

I had my second attempt yesterday. The pieze seems to be still not responding.

I applied 10V, 20V and 30V of DC accordingly. No strain was observed. I also tried appling 10V AC, again, nothing was observed.

In fact, I already applied 500N precompression load to the piezo.

But again, when I apply loads to the piezo, there is voltage generated. At the range of 10V.

Running out of idea, I directly paste a strain guage onto the piezo and hoping to see strain in piezo, again no strain was observed when voltage is applied.

I will have final attempt today. To use osciloscope to detect and see if the piezo actually vibrate under AC.

2

18/10:

2, e talk is impt ... & next week's talk even more impt (legal) ... yes ... but e actuator calibration is critical @ this pt in this ... before exams & procurement must be done before then ... if Prof Quek is around, can u pls discuss this with him before making any moves ... also compile what u have done up to now (fundamentals, Labview, set-up) properly, so that after exams, u can pick easily ... else can be nightmare, re-learning all over again

-----Original Message-----

From: Ooi Shein 2

Sent: Friday, October 18, 2002 11:23 AM

To: Lai 5 4

Subject: Friday meeting

I am attending the Friday talk at 3pm.

So, I won't be meeting Prof Ang for today.

1, as exams is near ... no need to do anything further ... just compile & consolidate what u have done up to now (fundamentals, Matlab programs, formulations, ideas) properly, so that after exams, u can pick up easily ... else can be nightmare, re-learning all over again ...

20/11:

2,

yap, in e afternoon after 3p.m. ... if i'm not wrong, we should have e following:

Energy approach --> dynamics equation --> affects wn & damping ratio

Sinusoidal approach --> actuator operating: amplitude & frequency

Equate the two --> by fixing one constant --> derive required actuation

Calibration --> verify required actuation achievable w.r.t. piezo, equipment, EQ (El Centro) & our system (M,C,K)

Checking --> state space --> LQR feedback --> closed-loop system --> controlled wn & damping ratio --> check: should equate

-----Original Message-----

From: Ooi Shein 2

Sent: Wednesday, November 20, 2002 6:45 PM

To: Lai 5 4

Subject: RE: Piezo Testing

Would u be coming to NUS tomorrow? I think I will meet u tomorrow instead of today.

2

-----Original Message-----

From: Lai 5 4

Sent: Wed 11/20/2002 12:19 PM

To: Ooi Shein 2

Cc:

Subject: RE: Piezo Testing

2, Inverted Pendulum formulation into state-space tutorial:

http://www.engin.umich.edu/group/ctm/examples/pend/invpen.html

21/11:

2,

regarding yr questions:

Force equilibrium or displacement approach: Both are equivalent ... i.e. if we use Force Method (assume force equilibrium, impose compatibility), the dynamic equation is exactly same as Displacement Method (assume compatibility, impose equilibrium; e.g. Stiffness method) --> this is because both are consistent & can be derived from Energy Approach (Conservation of Energy) fundamentals --> whether we use either force or displacement, the dynamic results must be the same --> our M,C,K dynamic equation is actually an extension of the Stiffness Method (static) --> hence, displacement method (which is unique, as compared to force method which is non-unique)

Effect of actuation: 1) increase overall stiffness (k+A) --> stiffen system --> harder to displace from equilibrium; 2) increase damping (c+Aw) --> damping means energy loss from EQ-excited system --> use active means to apply energy to cancel out excitation energy --> i.e. similar to waves --> excitation waves are canceled out by almost perfectly anti-excitation waves [N.B. this is an expensive way - Xia strategy]; 3) Decrease inertia (m-Aw^2) --> less inertia --> less energy transmitted to lumped mass --> less excited acceleration --> less exponential effects on velocity & displacement

Effect of fixing actuator operating amplitude (A) & varying frequency (w): actuator is operated as a relay --> constant amplitude --> time-varying w --> switching between the extremes of amplitude by the frequencies --> relay is like a switch --> jumping between amplitudes depending on feedback requirements

25/11:

2 & 1,

welcome back online ... e end of an era makes e start of another ... w.r.t. our projects ... i'm here neither as a supervisor nor a worker ... i'm more of a remainder ... here are e impt milestones along the way:

Jan 2003: Interim report + presentation (30min) --> your prelim. results or methodologies must be completed, written & shown by 31Dec

May 2003: Presentation --> hardcore technical sparring + thesis draft

June 2003: Thesis in full

the time seems 2 yet is short ... like they used to say "an apple a day keeps the doctor away" ... i hope the same goes for us "a result a day keeps the supervisors at bay" ...

Below are remainders of our objectives ... if you like to c1ge them ... you must finalise them around the interim period ... beyond which would be too late (like Back to the Future):

2,

objective: either (1) to realise (make SDOF set-up work) experimentally with robust LQR controller using piezoelectric sensors & actuators (Kamada et al 1997)

or (2) to complete piezo calibration methodology and achieve realisation (both numerical & experimental)

intermediate step (tools): Labview interfacing, actuator sourcing & calibration

1,

objective: to realise (verify all formulations) numerically with robust LQR controller for the benchmark problem (Ohtori et al 2001)

intermediate step (tools): verify controller parameters for a SDOF bilinear system, then 2DOF & dynamic condensation

1: i'm finishing my layered paper formulation ... you can concentrate on MDOF fundamentals (the notes, mode superposition) ... we can then combine our efforts ... also Prof Ang is not available this Friday 29/11 & Prof Quek is busy with 2 conferences here in Singapore ...

Lai,

objective: To control dynamic response of an unbraced frame under ground excitations with parametric uncertainties and bounded disturbances for minimal energy requirement & optimal stable performance using a network of independent decentralized subsystem controllers, each with sensors and force-inserting stacked actuators

intermediate step (tools): structural knowledge, modern control knowledge, robust reliable controller (for FYP), adaptive controller (for non-linear systems), unification (of both controllers), verifications

if in any query, try various ways of doing the same things ... if all else fails ... approach people who can help ... also keep in mind two things:

Active progress: researching a new problem (created) or a new methodology or new tools (Labview, Simulink, materials) --> proper catalog & reporting

Active maintenance: consistent revision of fundamentals & merger of old problems/methodologies with the new ones

As an engineer myself, there are 3 aspects that i think most are some what afraid of:

Dynamics: as opposed to statics --> note Dynamics can be w.r.t. time (our case), space (geometry), concentration (chemical variation), or any c1ging parameters (which is everything)

Non-linearity: as opposed to linear --> although non-linear can be linearised, certain effects (sometimes critical) may not be captured --> many accidents happen this way --> traffic situations are inherently non-linear, hence need to take note

Inelastic: as opposed to elastic --> like elastic-plastic, elasto-plastic, ductility, yielding, fatigue, creep

i hope that we can all learn along the way ... there is just too much to learn .. hence, "a result a day keeps the supervisors at bay"

26/11:

1,

my comments:

* Stages 1-4: are tutorial in that people are already studying them in courses ... hence, you have to do things differently ... one of these is to use new improved LQR (rather t1 the same old LQR with simple Q,R weighting) ... i suggest you relate the energy-weighted LQR (Wang Shengyin et al) to the system considered (bilinear, hysteresis) and formulate your own effective weighting measure that is both physically intuitive & simple

* Stage 5: sounds interesting ... i like you to source out & consider simple yet effective hysteresis model ... i believe they should contain around 2 parameters to define ... hysteresis model set ... then approach in 2 ways: (1) numerical - use simulations using the new LQR --> (2) analytical - try formulating the problem and show that LQR can indeed control it

no need to worry abt me ... follow the sup ... keep on the good work

-----Original Message-----

From: Lee Foo 1

Sent: Monday, November 25, 2002 11:39 PM

To: Lai 5 4

Subject: RE: Our Projects

hey 5 4:) t1ks for the reminder:)

i have just finish my papers on thursday and have been working on my thesis, currently my literature review portion is done and thruohg the last discussion with prof quek i think he wants me to work on the hysterisis style of elasticity which i think i will find out more from him ...sigh...I have just worked out the scope of my FYP in my thesis and have set that as the target

After i finish prof queks hysterisis, i will immediately fly to u for ur portion on the robust LQR controller for the benchmark problem can?

below is the scope i have came up with for my thesis for ur reference, but of course i will try my utmost best to cover all that we aspire...:)

Below is the scope and my objective:

1.3.1 Objectives

The objective of this project is to use the commercial software MATLAB 6.0 to study the effect of varying the types of elasticity of the structure in question and justifying if the LQR control algorithm is capable of dealing with the c1ge.

1.3.2 Scope of Study

Stage 1: The first stage of the study investigates the responses of the structures; each with its independent value of elasticity subjected to a same earthquake excitation. The purpose is to emphasize that a stiffer building is more likely to be better in withstanding the effects of earthquakes.

Stage 2: The next stage, our investigation of the capability of the LQR control algorithm will begin by first studying the responses of 2 structures (single-storey) when they are subjected to an earthquake's vibration; one of the structure will have no external forces to stabilize it whereas the other is subjected to LQR control algorithm. Both the structure will assumed a linear elastic stiffness and the efficiency of the responses will be looked into. This property of linear elastic stiffness is most commonly assumed in elementary studies; but is the most deviant from the real world scenario.

Stage 3: Upon the completion of studying the linear elastic stiffness, the next stage will be to conduct a similar study on 2 structures like that of the first stage but this time subjected to a bi-linear elastic stiffness instead. This type of elasticity (bi-linear) is frequently used to simulate real life cases whereby the structures will c1ge its elasticity from the initial stage of linear to a final stage of non-linear. Usually, the second portion of the bi-linear elasticity is used to simulate the non-linear portion of the real life case. Therefore, in this stage, the elasticity can take 2 different values depending on the stage of the loading.

In order to see the en1ced effect of the c1ges in elasticity, the second portion of the elasticity is first assumed to take a value of 90% of the original elasticity and a second test is then conducted whereby the second portion of the elasticity is then assumed to take 10% of the original elasticity. This is done because in a real scenario, the stiffness of typical structures is likely to decrease to 10% of its original value after subjection to a large vibration and the differences in result between the two tests will emphasize on the importance of the simulation of elasticity.

Stage 4: The project will be taken one step further after this point to the study of second storey scenarios. The bi-linear elastic stiffness studies in stage 3 are repeated for a 2 storey structure and the responses are then looked into. This is done to justify the adequacy of the LQR in the supporting of multi-degree of freedom structures.

Stage 5: The project will then be wrapped up with the investigation of the adequacy of LQR in 1dling hysterical model of elasticity. This kind of fluctuation of elasticity has the closest proximity t1 comparing with the bi-linear models. Hence, its results are of utmost importance to future studies.

I will try to add in stage 6 for other progress .....rest assured that the thesis will be updated

3/12:

2, to yr questions:

1. Open-loop: as active controls are dependent on structural system & loading ... then if both system & loading (like sinusoidal) are completely defined & known ... we can use open-loop controls ... no need LQR controller which is closed-loop that is used when either system or loading (EQ is inherently arbitrary) or both are not well-defined & unknown ... hence, we will use closed-loop active controls (i.e. one version of LQR) ... but, if we measure the shake table acc. ... then we can know the ground acc. ... this can be used as open-loop control (as we already know the structure) ... both closed-loop & open-loop controls can be used together ...

2. Inputs required: this depends on (1) the locations of sensors (types like accelerometer for acc. & transducer for displacements) ... (2) where we like to know the excited structural responses ... (3) Our control objectives ... the industry is using accelerometers, so we would use them ... we should pick up the roof acc. & shake table (ground) acc. ... like Goh Kok 5's ...

3. Outputs req: the controller calculates a gain K (just a matrix) ... then the shake table starts exciting ... at each time sample ... control voltage u is calculated as ... u = -K.X ... u is in Volts ... from state space: Xdot = A.X + B.u + H.(EQ) ... hence, the virtual controller in Labview need only calculate this voltage u(t) at time (t) ... then this signal is either sent to A/D converter to c1ge to analog signal ... or sent as a step signal over the time interval (t + dt), where dt is the sampling time interval ... then the control signal would go into the piezo actuator ... N.B. if excitation is sinusoidal, then we can specify a control voltage amplitude & frequency ... but in actual EQ, it is arbitrary ... no fixed harmonics ... then both control amplitude & control frequency c1ge ... then control voltage u(t) at each sample is only a value ...

1. My fundamental concern is to show that this controller can regulate (eliminate or drastically reduce) both controlled displacement & velocity ... if acc. gets reduced, it's a bonus ...

2. also, i like to show that this controller still works even when the system c1ges ... like mass c1ges, stiffness drops, damping c1ges ...

3. thirdly & lastly, this controller still works even when one actuator fails (i.e. it has control signal u(t) coming in from Labview, but the piezo does not deform or apply force ... or in real conditions, fire might have burned it past its Curie temperature), but another actuator still working (i.e. Labview gives u(t), piezo still diligently follows & actuates) ...

The seminar would be quite useful ...

-----Original Message-----

From: Ooi Shein 2

Sent: Tuesday, December 03, 2002 11:04 AM

To: Lai 5 4

Subject: Controller in labview

Hi... 5 4:

For now, I am working on labview. Perhaps, I can get things run in 2 weeks time.

I think very soon I will need to insert the controller into my labview program. Could you please let me know is there any specific controller that you wish me to use?

Open loop or close loop?

What are the continuous inputs that the controller requires?

1) Shake table acceleration and displacement?

2) Roof acceleration and displacement?

And what would be the output from the controller?

1) Controlling force or the control voltage?

2) Frequency of the controlling force?

T1ks...

2

9/12:

2 & 1

here are the controller design ... using Matlab ... but u can see the Word document for e results ... acceleration controls work best ... velocity feedback is arbitrarily stable --> damper is unconditionally stable ... the Powerpoint slides are useful for understanding various aspects of control ... supplementary

2 & 1,

u should glance at this seminar summary by Chase ...

? 2:

1. Piezoelectric actuator calibration

2. Labview interfacing & controller

3. Shake table dynamics & experiment

? 1:

1. Bilinear: SDOF, 2DOF

2. SDOF/MDOF controls: LQRx, LQRy

3. Hysteresis

9/12:

2 & 1,

when u encounter difficulties in research, there are 3 approaches:

1. Seek people

2. Seek equipment, tools

3. Seek papers, textbooks

When seeking papers, i realise that there are 3 types of papers that must be encountered, if not, the research is incomplete:

1. General research papers: survey, comparison, overview or collection of historical, current & potential future developments --> For: the big picture, get an idea of the state-of-the-art, discover or uncover loop-holes or niches for us to explore & exploit --> e.g. for our cases, we need survey of seismic structural design, isolation & control --> then, control is surveyed for passive, semi-active & active --> split into theory, R&D, constructed & commercialised

2. Specific complementary papers: detailed papers targeted & focused on their narrow objectives & scope that fits our needs --> e.g. Kamada et al 1998 researches (active control), for (Frames), (EQ), using (piezo) sensors & actuators, robust (controllers), with (shake table), & reduction of (structural responses) --> this type helps to highlight things for us to target or those that we have missed out, ignored or assumed

3. Specific contrary papers: these detailed papers have objectives that do not fit our objectives or needs, in fact can be totally opposite to our research --> e.g. Chase 2002 researches (semi-active control), using (semi-active dampers) & tries to diminish potential of active control (cost, power - nuclear plant (small one), complexity, design difficulty) --> this type helps us to see the inherent weakness of our side --> ideally, we should try to merge the strength of these into our designs

13/12:

1 & 2,

beware of these phenomena during simulation & experimentation:

• Aliasing: http://www.cbi.polimi.it/glossary/Aliasing.html
• Fast Fourier transform: http://www.cbi.polimi.it/glossary/FastFourierTransform.html
• Frequency resolution: http://www.cbi.polimi.it/glossary/FreqResol.html
• Power: http://www.cbi.polimi.it/glossary/Power.html
• Power spectral Density (PSD): http://www.cbi.polimi.it/glossary/PowerSpectralDensity.html
• Transfer function: http://www.cbi.polimi.it/glossary/TransferFunction.html
• Wavelets analysis: http://www.cbi.polimi.it/glossary/Wavelets.html

1 & 2,

i apologise for my harsh comments ... all of us are rather busy ... Prof Ang & i are involved in the ICSSD conference from tomorrow until Wednesday ... Prof Quek is busy with meetings of overseas Docs & an NUS conference KKCNN symnosium from next Thu to Fri ... it is right here in NUS ... refer to file attched ... i like to keep radio silence for the next whole week ... try keeping these tricks in mind in our absence:

• Theorem of Least Work: always (not sometimes) do the least work to get done ... if it needs to be done in the 1st place ... never run 400m & come back sweating, but nothing done
• Principle of Priority: prioritize yr tasks ... some are definitely more needy & fundamental t1 others ... aim for the most basic ... an analogy is to fly needs to walk needs to move ... ensure can move first
• Doctrine of Stepping Stones: to get things done fully & completely ... all the inherent steps must be carried out ... identify all the necessary yet shortest (Theorem of Least Work) path of stones ... never try to skip stones (tasks) that are essential
• Way of fundamentals: anything we don't know, not sure or ignored ... are probably important ... when mistakes arise ... question the observed mistake ... then conduct a thorough revision of the fundamental trilogy --> Dynamics, Control, Optimisation ... this is the way of fundamentals
• TRIZ: we know monkeys can climb trees ... but TRIZ ... try this tried & tested methodology of problem solving: http://www.mazur.net/triz/

18/12:

1 & 2,

radio silence lifted ... i'm back from conf. ... for e next two days, we (both supervisors) would be busy with the symposium ... i'm attending the seminars as if they are like tutorials ... if u like to clarify anything ... come along to these sessions:

Thu:

time: place: topic

12noon EA EQ train accident

1.30pm EA Controls & reliability analysis (!)

3.30 pm EA base isolation

Fri:

9.20am EA System identification & sub-structuring

3.30pm EA Nonlinear FEM

early birds catch the fleshy worms ... here are my presentation & a sample progress report for yr ref. ... try to get only the overall idea of how to report & how to present .... see u @ e symposium

20/12:

2:

• Physical meaning of active control: modeling in sinusoidal responses à at extremal positions, mass velocity zero, displacement & acceleration max. à KE+SE à only restoring non-dissipative energies à should not apply active control: since already purely restoring
• At desired positions, zero mass displacement & acceleration à max. velocity à DE+PE à only dissipative energies à should apply max active control: since en1ce dissipative energies

23/12:

1 & 2,

i understand that it's a risky & uncertain task in research ... especially when it comes to reporting & presenting ... i observe that people always ponder on 3 aspects:

• Knowledge of subject-matter
• Reporting as communicating or transferring this knowledge to others
• Presenting as convincing others against their bias

• U don't know, U can't communicate: worst-case, poor fundamentals, insignificant research, non-existent transfer, can't understand & can't talk
• U don't know, U can communicate: poor fundamentals, but able to communicate difficulties, so others can relate to yr problems
• U know, U can't communicate: good fundamentals, but can't write, can't talk --> a tragedy --> implication: use the pyramid approach to reporting & communicating
• U know, U can communicate: best, choose right research techniques --> & go all e way

• Large base: good fundamentals to fall back on during difficulties --> good, broad-based introduction & literature review (use comprehensive papers, overview)
• Narrowing body: narrow down your research topic from the general to the specific, from the overview to the detailed, from the conceptual to the detailed, from the superficial to the in-depth, from perceptions to your objectives & scope
• Pointed tip: short, sharp & piercing arguments towards your research focus, provide all that's absolutely necessary to make the shortest, sharpest ordering & transferring your work to others

Treat the others as if they are "yourselves a few months ago, before you started this research" ... remember the idea beats the details ... the best type of response that U can get is ... "Oh ... like this lah ... so simple!"

26/12:

2,

i like u to take these books from me:

• Vibrations & Waves: Central Library book --> immediately return & re-borrow for yrself
• Engineering Materials: NLB book --> return me in 2 weeks

The energy approach u discussed can be represented & solved by LQR

1,

u must return the mode-superposition by tomorrow, then re-borrow yrself

this is a controller for nonlinear & hysteretic structures ... U can suggest to supervisors to use the hysteretic models in equations (55-57):

Also, there are some papers in the ICSSD proceedings that accounts for hysteretic behaviour by including rate-dependent characteristics:

• Higher strain rate: higher stiffness, higher brittleness
• Vice versa.

Also, if U like to learn Visual Basic or C programming, U can also borrow from me ...

27/12:

1 & 2,

i understand Prof Balendra is the examiner ... plus our supervisors ... N.B. to relate yr audience (sup + examiner + me) ... use the Chinese saying: know yourself, know your adversary ... take these steps:

• Ground yr fundamentals
• Sharpen yr writing & speech

i'll now reveal their (audience) interior concerns to U:

• T.Balendra: teacher of all of us ... very fundamental ... go as deep into theory, analysis & knowledge as possible ... he has a way of questioning that tends to shaken people ... so hold on your fundamentals - Dynamics, Control, Optimisation ... no flashy business, he's straight as a rod ... give yr basics, not beautiful diagrams ... if u seem stuck, 2 ways: (1) out of scope of present studies; (2) for future studies ...
• Quek: another teacher & fundamentalist ... question all sides ... so buck up yr theory, concepts, simulation, experiment ... he likes ideas & concepts ... if he questions U on details ... remember to relate yr detailed answer back to the underlying concepts ... no need to be afraid of him ... he's friendly if U are able to make him think ... so always mix the details with the ideas ... he likes that
• Ang: the reporter ... always come here knowing nothing ... but intense concentration during presentation ... excellent in reporting & presenting ... so 2 as U are very clear, concise and sharp ... it's okay ... best to have backing (literature) or reasons for doing or not doing something ... ensure smooth-flowing ... make sure everything are related & substantiated ... according to the text (as they say)
• Me: everything is fine with me ... so 2 as U realise what U set out to do on this journey

• Intro
• Literature review
• Obj & Scope
• Set-up: assumptions, model, actuators, sim/expt
• Results: how well they reach the objective
• Conclusion: remaining work

2 & 1,

in communications - talk & write ... there can be millions of approaches ... but i realise that all are composed of 2 extremes ... like the tension & compression ... push & pull ... structure capacity & exciting load ... the 2 extremes are:

• From general to detailed: pyramid approach --> from thin to thick
• From detailed to general: inverted pyramid approach --> from thick to thin

30/12:

2 & 1,

i realise that the LQR weighting I showed u: Q=diag(K,M) ... is fundamentally not right ... the energies (Wong et al, 2000) are:

• strain energy: x.K.x, where (x: the relative displacement)
• damping energy: dx.C.dx, where (dx: the relative velocity)
• kinetic energy: dy.M.dy, where (dy: the absolute velocity dy=dx + dx_g, dx_g: the ground velocity)

• Q=diag(K,C) to minimise the strain & damping energies ... or
• Q=(-M\K -M\C) to minimise the estimated kinetic energy --> what Chase has done

• non-dissipative energies: if (mass, stiffness) are relatively high, control energy limited & dissipative sources (for DE & PE) are large enough
• dissipative energies: if (mass, stiffness) are relatively low (non-dissipative components low), control energy limited & dissipative sources (for DE & PE) are too small or need to be kept to some minimum (too much PE means lots of yielding & hinges formed - too dangerous)
• both non-dissipative & dissipative energies: if control energy not limited

2/1/3

1 & 2,

i have highlighted the following to U:

3 types of papers:

• General research papers
• Specific complementary papers
• Specific contrary papers

• Theorem of Least Work
• Principle of Priority
• Doctrine of Stepping Stones
• Way of fundamentals
• TRIZ

• Pyramid approach
• Inverted pyramid approach

• Open-loop control: internal dynamics are exactly, unambiguously known or measurable without delay ... then active control can be applied directly using these known dynamics ... then only open-loop or feedforward control is done ... if the system is only & truly governed by these known dynamics ... then there is perfect regulation ... i.e. error is zero ... all responses for all time is zero ... perfect controls
• Closed-loop control: when the internal dynamics (like variations in M,C,K) or external disturbances (like unknown EQ, noises, fluctuations, imperfections in understanding, modelling or construction) ... then open-loop control would be diastrous ... it would cause instability & collapse of structure ... hence, we need some form of self-correction & self-tuning within the controlled system ... here, we base the active controls only on the responses of the structure ... then apply a corrective control actions back into the structure ... to maintain equilibrium, achieve stability & reach desired responses ... this is the feedback or closed-loop control ... we feedback the controls into the structure to reach minimisation of responses
• Open-Closed-loop control: in the real-world engineering, dynamics of a structure is generally known (M,C,K) in some aspects & uncertain (dynamic variations in M,C,K & non-structural components) in others & totally unknown (EQ hazard analysis, catenary actions, collapse modes & mec1isms) in the rest ... hence, for known or measurable portions, use feedforward (FF) or open-loop controls ... for uncertain or unknown or unmeasurable portions, use feedback (FB) or closed-loop controls ... then, u(t) = FF(t) + FB(t) ... this is the most general form of active controls

• Knowledge: thought i know & have solved, but is based loosely on poor fundamentals
• Methodologies: thought i'm certain of the process & procedure, but is based loosely on some other techniques that in turn based loosely on others + some assumptions that tend to escape scrutiny ... this is similar to legal contracts ... clauses that are presumed & escape scrutiny that are important in some situations ... but not in others

When we look at the health of a tree ... we look at its roots ... When we look at the "wealth" of research ... we look at its fundamentals

2 & 1,

Besides the physical understanding of LQR ... we need more:

• Existence conditions for solution of LQR: s.t. LQR gain exists
• LQR effects
• Dynamic governing equation fundamental: derivation of 2nd-order M,C,K dynamic equation from Newton's 2nd Law

• (A,B) stabilisable: all unstable modes are controllable
• (A, sqrt(Q) ) detectable: all unstables modes are observed

• Optimal desired pole assignment method
• Guarantees infinite gain margin (GM)
• Guarantees at least 60 degrees of phase margin (PM)
• Good disturbance rejection: high GK magnitude at low frequencies
• Good unmodelled dynamics avoidance: low GK magnitude at high frequencies

• Derive from Newton's 2nd Law: review yr 1st yr kinetics (not kinematics) fundamentals
• Derive D'Alembert's Principle
• Principle of Virtual Displacements
• Hamilton's Principle
• Lagrange's equations

if u are not sure of the above ... u'll pass but yr fundamentals are not sound

7/1:

1 & 2,

in the structural vibration due to rigid-base horizontal translation encountered in our project ... using parameters of forced & controlled ... we can split them into the following:

• Free, uncontrolled: pure free vibration response
• Free, controlled: post-EQ vibration response, free from EQ loads, but still under transient vib
• Forced, uncontrolled: uncontrolled EQ random vibration response, w/o actuation
• Forced, controlled: EQ & actuation-induced random vibration

• Periodic forcing: includes sinusoidal excitation ... dynamic response can be solved exactly using trigo. formulations
• Impact forcing: super-strong initial blast wave or impulse ... followed by free vibration ... not encountered in EQ ... though composed of waves
• Random forcing: random non-periodic arbitrary loading ... for SDOF: use Duhamel integral for exact solution ... for MDOF: use mode decomposition into SDOF then use Duhamel integral for each mode ...

• Exact solution: for periodic forcing & SDOF random forcing using Duhamel inetgral
• Approximate solution: (sometimes over & sometimes under-estimate ... ensures u know which side the algorithm used is on)
• Physical formulation by assuming some dynamic characteristics: Mode superposition method, Rayleigh-Ritz method, wave propagation
• Numerical: purely using numbers & digits ... ALL (that i know of) use some truncated form of ... Taylor's series ... summation to infinite terms (if exact) ... Euler method neglects items of 2nd order onwards O(2) ... Runge-Kutta 4th order neglects items of 4th order on O(4) ... which is already quite good approx. ... there are two classes of Numerical approx. algorithms:
• Explicit methods: I.C. (initial condition) assumed/known/given ... but next time step is unknown ... algorithm calculates the next step using present known time step ... effect: faster computations, but less numerical stability (implies errors can be large, if time steps large)
• Implicit methods: I.C. given ... but to solve for the next time step ... need solution of simultaneous equation for each time step ... effect: slower, but more accurate & stable ... Resources: http://www.damtp.cam.ac.uk/user/fdl/people/sd/lectures/nummeth98/odes.htm
• Mixed physical formulations & numerical: actually ... just numerical algorithms to satisfy constraints of physical meanings ... e.g. time-stepping methods like Newmark-beta method (my favourite)

• Wavelets
• ODE: ordinary differential equations ... in only 1 variable ... in our case ... in (time) ... all the above solves for ODE only
• PDE: partial DE ... in >1 variables ... e.g. varying (time), (geometry), (material), (temperature), etc. ... for nonlinearities, composites, interactions, coupling, multi-media complex ... solutions can be derived by adv. tech. ... exact is difficult ... approx. is also by:
• Formulation: using theorems like Fourier series, wavelets etc.
• Numerical: FDM (finite difference method)
• Mixed formulation & numerical: FEM (finite element method: i know pple are wow by this ... but don't be fooled ... u may not need it in the first place ... like our project ... never jump into mud-pool ... come out muddy ... nothing clean) ... BEM (boundary for spatial dynamics) ... DEM (distinct for crash & damage testing & evaluation) ... finally, Meshless method (potential to overcome FEM ... but still infant R&D ... & too computationally intensive ... great for fracture & failure analysis & modelling)

• 1: implicit Runge-Kutta RK4 numerical approx. ... random EQ ... as hysteresis is nonlinear in nature ... it breaks the RK4 algorithm flow ... hence ... customisation is necessary ... for checking purposes ... test using this criterion: controls are LOWER for hysteretic systems ... as effect of hysteresis: additional damping ... as damping is a form of dissipative energy ... implies the system becomes easier to control ... thus, hysteresis is good for control ... unfortunately, in practice ... hysteresis is obstructed by lack of suitable modelling ... though more joints & layering are good
• 2: for periodic ... use exact solution: trigo. formulations ... for random EQ or signals or simulated shake-table response ... for SDOF only ... use exact solution: Duhamel integral ... or approx. like RK4 or Newmark ... i think Labview has some ODE solvers

8/1:

2 & 1,

i recently went back to my cousin's wedding in Muar, Malaysia ... i witness lots of civil development ... new roads ... houses ... oil stations ... many of the new ones are contracted by my cousins ... yet they only have technical training ... little or non-existent theoretical training ... they depend more on experience, contacts, intuition ... i feel quite impacted by this ... what with such high-level knowledge of my Singaporean cousins & me ... yet we still lost our way along Muar new roads ... hence, i put forward this perspective to engineering (in every sense of the word) ... there are the following scenarios:

• Segregated, Theoretical Research: highly theory-based formulations, modelling ... yet largely neglecting the needs & wants of the present industry ... due to the following causes:
• Too futuristic (numerous assumptions) ...
• Too unrealistic (though theoretically feasible) ...
• Too unpractical (not directly applicable in the surroundings ... e.g. hot climate research cold climate stuff ... too costly ... too resource-consuming)
• Too complex: e fact that stds & codes are so prevalent in CE ... is evidence of the complexity & critical importance of CE structures ... there is an urgent need to simplify things ... using step-step methodologies or algorithms or procedures
• Too separated: though R&D is supposed to focused ... yet by the inverted pyramid approach ... we must relate back to the present conditions ... in direct & simple terms ... an Australian professor has commented ... "For the excellent expertise present in design & analysis in Singapore, it is unfortunate that it is limited in its execution. The actual construction capacity lacks far behind that of design" ... hence, our R&D is not being effectively disseminated & fused into the industry ...
• Segregated, Experimental Research: highly-specialised experimentation ... largely out of reach of the industry ... due to the same causes as above ... plus without proper communication (pyramid & inverted pyramid) ... all the sweat, toil & effort ... would exc1ge some virtual grade or paper or certification ... that e bosses would just flip thro' like newpapers ... let it be known that ... to be certificatied does not mean qualified ...
• Segregated, Theory-Experiment Research: a more complete form of R&D ... in that difficulties of both formulations & realisations are encountered & overcome ... yet without consideration of the industry ... would either result in:
• Exploitation by external parties: to strengthen their own fruitful R&D & industry causes ... might even be competitive with our own ... hence, form a vicious cycle ... causing thorough collapse of our own industry
• Admiration without Application: wow's aglore ... but eventually not implemented ... or even catch e attention of the users ... a tragedy ... like e Heros of e Marshes ... super-human efforts with misguided causes
• Integrated, Theory-Experiment-Industry Research: to address the shortcomings of the above segregated R&D ... we need to be aware of our present industry ... what it lacks & trends ... use Chinese saying: know yourself, know your environment ... have a good cause for e industry to guide the development of theory-experiment ... let not all efforts go into some hardbound papers & locked in some air-con rooms ... for integration, pay attention to the following:
• Thorough understanding of the industry: what it lags, needs
• R&D focus: what to target & how to popularise the fruits of R&D ... know e constraints & obstacles ... & work around them

• Kinesthetic: by action ... more of trail-error engineering ... self-observation & correction ... experienced-based ... analogy: bottom-up approach ... suitable for: complex situations, hence actions are simplified ...
• Logic-Evaluation: by thought ... more of science-based engineering ... knowledge learning & usage ... theoretical-based ... analogy: top-down approach ... suitable for: simplified (theoretical, assumed) situations, hence formulations & experimentations are complex & advanced ... yet what attracts people are not complexity (though society gives lots of praise) ... it is simplicity

i hope to highlight the importance of simplicity in such complex domain as ReSearch ... to ensure that people would be attracted to it ... & use it ... isn't that what research is for?

1 & 2,

With actual, real physical phenomena --> mathematical modelling --> Uncertainties accumulate:

• Inherent uncertainties, errors: due to type of modelling used
• Cumulative uncertainties or errors: due to techniques used within modelling chosen

• Materials: behaviour
• Geometry: spatial
• Interactions: coupling between components
• Variations: dynamics of the above

• Exact: continuum mec1ics ... continuous systems ... highly mathematical ... more science-based ... fundamental, but can be abstract (Lagrange, Hamilton, Newtonian, Galerkin) ... difficult to visualise & describe formulations ... but typically excellent results ... seldom used in stds & codes
• Approximate: some kind of idealisation ... with some assumptions (impt to note these always) ... can be unrealistic ... but still applicable to specific focus applications only ... need to minimise modelling errors to tend towards exact ... typically faster, simpler with varying results ... there are 2 types:
• Realistic formulation & effect: inspired by exact modelling ... but simplifed along e way for some kind of efficiency & simplicity ... like D'Alembert principle, Rayleigh-Ritz, FEM & their cousins
• Unrealistic formulation, but realistic effect: modelling representation not matter ... only ensure that the responses are good enough ... even faster & simpler ... like lumped-mass (non-consistent mass) with Maxwell element (lumped mass M, linear viscous dashpot C, linear spring stiffness K)

Hence, our case ... only uses approximate ... with unrealistic formulation ... but simpler with good enough responses

9/1:

1 & 2,

in the stds & codes ... under limit state design ... vibration is a serviceability limit state ... in that vibration encountered in service conditions ... are not serious ... in that it does not affect the ultimate behaviour of the structure ... namely strength, stiffness & stability (3S by C.G.Koh) ... however ... in severe excitations ... like:

• Hydrodynamics: marine, tsunamis, waves, underwater eruptions
• Aerodynamics: wind gusts, typhoon, tornado, hurricane, flutter (due to structural configuration)
• Contact mec1ics: ground excitations, support (of machineries, substructures) excitations, blast, impact, explosions

• Design mitigation: the first thing to do ... to stop the source of excitations ... in natural hazards ... this is not possible ... by the Doctrine of stepping stones ... is it necessary to locate in this hazardous area? ... if necessary ... to re-design properly ... this needs awareness of the three physical vibration phenomena:
• Excitation hazard analysis: whether EQ, wind, marine, periodics or impacts ... needs insight observation ... classification & categorization ... first, using stats ... then, with more understanding & modelling ... using, pseudo-empirical analysis ... to pick out how likely a region is subj. to how strong & intense of the type of excitation over how 2 a design period ... although highly probabilistic ... has proven to be worthy of R&D & usage ... like gambling ... some just seem to keep winning ... Taiwanese are doing well here ... US/Japan/Australia have codes for these ... notably UBS
• Critical structural design: the type of layout ... geometry ... material ... occupancy ... civil importance ... rules of thumb include ... symmetrical layout, higher rigidity, more supports, more braces, more composites ... able to withstand the critical excitations ... a consultant-type of job
• Interactions: between components ... between structure & excitation ... a much less understood phenomenon ... due to past emphasis on separate component design & analysis ... hence ... nowadays moving towards systems level design ... where the interaction effects are dominant & very significant ... a specialist & R&D vocation
• Isolation mitigation: when the structure & excitation are identified & confirmed ... yet analysis indicates vibration too intensive ... then by the Doctrine of stepping stones ... next by best thing ... eliminate transmission of excitation energy into the structure ... like xiam e fireball in street fighter ... to do this in civil structures ... use isolation measures ... literally cut off structure from excitation ... idea is good ... but practically ... limited by isolator technology ... as well as difficulties in implementation (would u like to stand on ball bearing?) ... & maintenance (how to lift up structure & c1ge its foundations?) ... isolators include LRB (lead-core bearings), reinforced rubber (under Esplanade ... i saw one) ... what these isolators is none other t1 ... hysteresis ... to dissipate the excitation energy before it gets into e structure ... of course ... difficulty in modelling hysteresis oso a limiting factor
• Control mitigation: now that ... both design & isolation ... are taken ... yet still vibration too large ... then lan lan ... bring in the controls:
• Passive control: cheap ... no energy req. in operation ... but only effective in narrow band of exciting frequencies ... outside this band ... accordingly ME notes ... passive controls would instead amplify the vibration ... hence, useful only when the excitation is almost exactly known to be concentrated inside the narrow band
• Active control: our focus ... energy-consuming ... use energy input to cancel excitation energy ... it's like right 1d pushing left ... then left pushing right ... hopfully the palms stay under equilibrium ... danger of instability if design improperly ... expensive ... power high ... it is known that pple switch off these active controls during real EQ ... hence ... what use? ... but highly adaptive & able to tune for almost any interested freq. ... it is most useful in the controller (my focus) ... not in the sensing or actuating mec1isms
• Semi-active control: cheaper ... slightly energy-consuming ... enlarge & add to e energy-dissipation capacity of e structure ... depending on e type of mec1ism ... varying effects ... a few are: ER/MR (not good, slow), piezo (transform mech. energy into electrical en. then dissipated using shunt) & variable orifice (just close & open at e right time, best in my view & most easily popularisable) ... note the controller is still active ... hence, my focus is oso useful
• Hybrid control: combine some passive dampers + other active controls (stacked piezo) ... energy-consuming oso
• Composite control: just another name for hybrid

Also ... note that those partition walls, utilitise, windows, doors, furniture ... have some effects on stiffness & less on inertia ... before they break, structure is slightly stiffer ... after they break, structure suddenly becomes weakened ... this comes as impact ... hence ... need to guard against this

10/1:

1,

a few points to take note:

• EQ: scaled El Centro 1940
• Basis for choosing M,C,K - whether they are physical or from textbook
• Responses comparison: in time domain or frequency domain - must be able to explain both, if presented
• In Bilinear: i think yr K2 stiffness is smaller by around 10-20% - give basis for this: due to stiffness of non-structural components; --> in actual, if the structural elements do yield --> the K2 is around 15% of K1 (from Conf. results) ... if not sure, just say it's under studies
• 2DOF: has coupling between the 2 storeys ... how to acct. for coupling, modal interactions & inherent assumptions
• Hysteresis: u can bring out as a present task to solve ... likely to be some discussions here
• Results: present only when u are confident & sure why they occur ... if sig. reduction ... either by by table data or by figures ... but must explain carefully
• DOF: emphasize lateral DOF only ...

Also ... i sense that u are not welcoming to my coming to here ... then i'm not coming to watch then

2,

a few pts to note:

• Concept: overview, basis & idea behind active control & experimentation
• Set-up: highlight wat u plan to do, has done & need to be done further
• Explain by parts: Structure, Modelling, Actuator, Labview interfacing & controlling by energy method
• Difficulties: highlight problems faced ... as experiments are littered with problems ... but highly technical like how to make Labview do this & that ... pls avoid ... stress e procedural diffculties & anticipate any resources u req along e way

Also ... i sense that u are not welcoming to my coming to here ... then i'm not coming to watch

• In report, pls mistakes in report:
• Quote inside text --> must include in reference section
• Not quoted or used in text --> never include in reference
• Try flowchart yr process
• Then codify yr procedure --> step-step algorithm easy for future generation

• Theoretical formulations to predict responses & dynamic amplifications using induced excitations with actuators in combinations (one, either side, both)
• Experimentation: test each properly --> set-up --> use some criteria to check correctness --> configura properly --> measurements to see if match predictions --> if not, why
• Since SDOF is steel structure --> can directly apply BS5950 (2000) codes to test & study --> also code criteria for drift & acceptable acc (1.5%g) can be applied
• Codification your entire procedure

12/1:

2 & 1,
in the Way of Fundamentals ... i have discussed both dynamics (modelling & response analysis) ... & control (design, isolation, control overview) ... e last is optimisation ...
In this often-hyped, but useful (in e sense, we r toiling ourselves to help others save a little bit of money, a little bit of time, a little bit of resources & of course, some troubles) technique ... optimisation is e process of optimising a process to best reach a desired result (by Theorem of Least of Work) ... Optimisation involves the 2 aspects below:

• Criteria set: to judge objectively whether e process has been desirably optimised ... subjected to all constraints (One Emeritus Prof said,"if u give an engineer infinite time, infinite resources & infinite contacts, he can solve anything" ... as we engineers know ... e real world is NOT an ideal one ... there are always limitations in time, resources & controls ... optimisation is to find that best path w.r.t. these limitations ... if it exists in e 1st place)
• Technique: principle, methodology & step-step procedure to reach that criteria set

Hence, it follows that ... to start optimising ... we need:

• Performance function or cost index: to represent the criteria ... e.g. if we want to minimise energy transfer ... all e types of energy in dynamic problem must be represented by this function ... else it is incomplete, hence useless in some circumstances ... in control theory ... there are various ways of representing the performance criteria ... J in LQR is one e.g.
• Method: to determine existence ... then solve the unique (or non-unique) solution ... there are very many ways ... but they can be classified (like BS codes) into the following categories:
• Classical vs. Neo-classical: ... classical are those based on:
  Fundamental maths principles
  Lagrange multipliers
  Kuhn-Tucker conditions
  ... if problem fits into formulation ... exact results ... performs very well ... Neo-classical are based on: numerical or mixed formulation-numerical methods ... where computers are essential ... varying results ... depending on problem & understanding of designer
• Linear vs. Nonlinear: linear optimisation or linear programming ... are e simplest ... with linear criteria & linear constraints ... all powers unity ... all are lines, hence convex in mathematical terms ... then optimisation is straight-forward ... includes: Simplex method, Differentiation for stationary points ... Nonlinear method are most general ... linear being special cases ... more difficult to formulate ... & solve of course ... includes: all numerical searches, separable convex & quadratic (& higher-order) programming
• Unconstrained vs. Constrained: Unconstrained ... of course are the simplest without limitations ... like dy/dx=0 for critical stationary points ... but unlikely to encountered ... methods include: Lagrangian method, some numerical methods like greatest ascent gradient, Newton-Raphson (suitable for nonlinear dynamics convergence & FEA), direct search methods ... Constrained are the norm ... criteria under various limitations to be solved ... a powerful way is to transform these into an unconstrained problem ... like the Lagrange or Hamiltonian method used to solve the LQR problem ... very useful, but only when criteria function is continuous ... to derive discontinuous ... requires Z-Tranform for dynamics ...
• Formulations vs. Numerical: formulation-type of optimisation ... of course involve modelling the criteria & problem in maths functions ... normally continuous & differentiable ... normally almost exact results ... good of course, but not many know how do this properly ... Numerical: are derived from the formulation-type ... like dynamic response calculation ... they are step-step, procedural & discrete in nature ... suitable for computers ... but accuracy varies widely depending on e problem & technique ... include: all numerical searches like Genetic Algorithms (GA), neural network, evolutionary algorithms, simulated annealing ... in 2 classes:
• Direct search: specific optimisation target already present ... technique converges towards that goal
• Indirect search: no specific target ... only know somewhere & sometime there ... hence, search all over e place in nonlinear fashion ... convergence is seldom guaranteed ... for those really complex things like ... hazard analysis, quantum dynamics, bioinformatics, geo-environmental synthesis ... stochastic in nature

in our project ... we have narrowed the search domain quite a lot ... problem structure is linear ... lumped discrete ... sensors all over e place ... no problem ... actuator(s) either assumed or located at researched position (Kamada) ... we have also either assume or given that:

• Criteria: minimise structural responses whether by outright regulation (using LQR theory which is actually energy Lagrange method) ... or by concurrent structural energies (Wong)
• Solution existence: in formulation ... LQR as a classical formulation requires existence conditions to be satisfied ... to be both detectable & stabilisable ... but if the ARE can be solved & simulations look right ... existence is satified ... for energy-based approach ... though inherently stable ... distinction between dissipative & non-dissipative energies need emphasis ... also, a specific criteria for structural energy minisation needs to be derived ... then combine with yr energy approach to show that it does reach its intended purpose
• Method: LQR assumes infinite time regulation ... & state-space model is non-unique ... hence, it is not only answer towards control ... it depends on ALL variables inside ARE ... the control gain ... alters both damping & stiffness ... to reach minimisation of J over infinite t ... L in LQR means linear ... in that u=-Kx only ... but criteria J is quadratic (Q) ... so in optimisation terms ... LQR is really quadratic energy Lagrange method ... or in discrete t ... it is quadratic programming ... it represents a new controlled structure as opposed to initial uncontrolled softer, less damped structure ... in energy-based approach ... the methodology should be substantiated by the trilogy of formulation ("No need to get knee-deep in analytical formulation, but just tip-toe enough to get the basic fundamentals right" S.L.Lee), simulation (show by testing in periodic & random excitations with any software like Excel, Matlab or Labview) & experimentation (FRF of simulation matches experimental measurement ... if not, why ... by induced excitation ... & by active control during EQ)

With this ... i have completed the trilogy of Dynamics, Control & Optimisation ... t1k you for kind attention ... & i welcome yr queries

14/1: Interim Oral Presentations

1,

from what i can gather abt Interim:

• Hysteresis: inelastic ... loading path is different from unloading path ... since dissipative, responses reduced compared with non-hysteretic (same loading & unloading paths --> elastic)
• Literature: gd with theory & practical backgrd ... actual applications ... Rainbow bridge - how ia actually implements hybrid control ...
• Bilinear, non-hysteretic : pre-yield & post-yield phases ... actually no real material belongs this ... an idealisation only ... like steel in BS codes ... elastic-perfectly plastic phase ... can say that this idealisation is useful for modelling purposes ... & materials like some steel grades e.g. can satisy this bilinear req. under some assumptions & conditions
• State space: i notice that .... u put inside A ... [...; -K/M -C/M] ... okay for SDOF, since scalar ... this is not correct for MDOF ... since in matrix op ... order is impt ... hence, for all system A ... should use [...; -M\K -M\C] ... or [...; -M^-1K -M^-1C] ...
• Switching: for bilinear ... & hysteretic calculations ... need to be shown in more detailed conceptually ... later in thesis & FYP presentation ... good to highlight switches of 1) stiffness; 2) LQR gains (already calculated)
• Programming: ... Prof Ang's idea of neatness is to write one super-master program ... then customise this to apply to specific applications like SDOF/MDOF ... best to be scalable ... but it's ok for u to separate them for ease of testing ... concentrate on hysteretic for now ... also ... no need to present yr Matlab programs & what they do ... we only need the results & findings ... one way is to use flowcharts ... & show what each phase (not programs) do
• Resuls: should have more results ... like for SDOF, 2DOF, linear/bilinear ... then illustrate yr insights into the responses, controls & structures ... like what Prof Balendra asks ... hysteresis: lower response due to dissipation ... bilinear: more controls needed t1 linear due to lower stiffness ... also ... how difficult to control 2DOF c.f. SDOF under linear/bilinear, elastic/hysteretic conditions ...
• Plots: controlled is a shift in spectrum ... but like to emphasize this ... try not following my style ... whether in report or presentation ... it's best to cultivate yr own style ... e plots in my presentation ... are actually not for pple to see in detail ... in Conf ... pple are like sotong ... u tell what to look, they look ... but here ... pple look everywhere ... so plots must be clear ... Prof Quek say should blow up ... esp. if u want to emphasize things ... but whatever it is ... u must explain each & every plot ... they are yr flesh & blood ... so show them ... each & every one with care ... title --> show what --> each axis & legend --> show pattern --> explain why or why not ...
• Adequacy: a measure ... or set of measures ... to quantify the effectiveness of LQR control ... can be either formulated (one is the discrete-t performance index ... LQR J but in discrete time ... u borrow a Matlab by Ogata ... very good for discrete-t) ... or numerical in nature ... like some least squares method of the responses & controls ... sorry i didn't note this to u

2,

some comments:

• Seismic mitigation: hazard in question is EQ only ... no need say wind or what .. tsunamis ... & mitigation ... is actaully the trio of ... structural design ("at source" ... like in ICE, UBC codes) ... isolation (some rollers, rubbers ... some passive some active ... it tempers the excitation energy "transmission" ... but not considered as control) ... control can be defined as reduction or mitigation within the structure ... that means excitation energy has already been transmitted or entered e structure ... control (passive, active, some combinationof both, improvement of one with the other)
• Starting Keywords: i like this ... presentations often doodle around e bush ... a sentence like this seems to clear all bushes with one stroke ... note yr explanation for control ... it is highly controversial ... so define it properly
• Active control overview: ok ... e.g. of actual applications like tendon control & AMD ... ok ... Prof Balendra likes that ... now i know he's not only fundmental ... he's practical also ...
• Concepts: the moment generated ... by a couple (F) separated by length (2*l) ... should be (F*2l) ... not (F*l) ... also ... in Kamada et al 1998 ... the shearing control force due to B.M. controls ... is only directed at the storey directly above ... like actuators on ground ... can only transmit control force at 1st storey slab ... but u show lateral shear forces on all floors ... not correct since slabs are often assumed rigid ... beyond 1st floor ... unlikely to feel shearing control force
• Closed-loop: u show ... measure ... ABSOLUTE (x, xdot) ... base (xb, xbdot) ... if measure base --> open-loop measurement ... shown in the active control overview (Quek notes) ... in LQR, we req RELATIVE, hence (abs-base) ... in energy method (Wong 2002) ... it's part rel., part abs & part grd depending on type of energy ... thus, i believe it should labelled as a open-closed-loop type of control ... in closed-loop control, it is strictly without knowledge of external excitations ... they are completely ignored in formulation
• Piezo: its capability ... limitations ... constraints: F,V,dp relationships ... i never thought it's so simple ... & u make a great comment (though sounds almost like a chat to me) ... "This shows that Piezo is a stiff material" ... Balendra immediately nods his head ... he likes catchy statements ... due to e balance of force & displacement constraint ... u make another great statement to Prof Ang's question (which to emphasize: force or displacement?) ... "I believe it is both Piezo force & displacement" ... it seems to me ... piezo force is not an issue ... it's e displacement ... & it seems that stacking is one solution that is being targeted ... of course, there are others ... is ours a stacked piezo? ... i think Balendra is interested in Piezo ... can u make in-depth calibration & survey of Piezo? ... u know ... for e good of future generation ... like from Goh Kok 5 to u
• Labview: from Balendra comments, u know ... we don't need e implementation details ... just e overview diagrams ... & flowcharts are great ... simplicity reins supreme in presentation environments ...
• Set-up: there are lots of variables ... seems lever arm is of interest to Balendra ... may be extensible lever arm for future? ... a larger mass can also bring e wn down ... anyway ... just vary them to reach a configuration s.t. yr objective statement is reached
• Control mec1ism: ok ... i like how u present Wc ... f(structural response, PZT, K) ... but some disputes over stage(s) to input control energy ... disputes arise due to incomprehension ... use the Chinese saying: Ren Ping Bu Yu, Shui Ping Bu Liu ... people are silent when they are satisifed ... water is stagnant when there is no gradient ... hence, u need to improve this part ... there are many ways ... u may consider this ... the green SDOF mass in 3 positions is incomplete ... replace by two sets of diagrams ... (1) show trajectories (use arrows) for mass movements in 1 cycle ... (2) show control trajectories (when start ... when end) for applying control energy in 1 cycle ... should clarify all doubts
• i sense Belandra likes u to do a complete workout for this experiment ... & a complete investigation into what can or cannot be done with the set-up & actuator ... he's not interested in e tool (Labview) used

17/1:

1 [Lai 5 4] ,

suggestions:

• Control: definitions, obj., aspects (overview in Quek notes, FB & FF), sensors, actuators, controllers (design & implementations)
• Assumptions: sensors, actuators, system form
• System: linear, bilinear, hysteresis (material); lateral; SDOF/2DOF
• Excitation: EQ, lateral
• Control algorithm: design obj., methods
• Control Types: linear/nonlinear, static/time-varying, instantaneous/discrete, FB/FF

Results: define problem (system, EQ, devices, controls) --> diagrams & plots (label properly) --> findings (like % reduction ... ) --> explain (by formulation k1,k2 or comparisons) towards Objectives

1 & 2,

there is much confusion between which comes first ... chicken or egg? ... though this question is inconsequential to us civil engineers ... but we did encounter this dilemma in structural analysis ... which comes first ... force or displacement? ... i discovered that this question has been answered already ...

In structural analysis ...

Given: structural layout, material, geometry + loads (static/dynamic, point/distributed)

Response: 3 forms

• Primary (essential) responses: displacements, strains (& their derivatives: velocity (KE), acc (inertia), etc.)
• Secondary (natural) responses: forces, stresses (& their derivatives)
• Energy responses: various forms (but relative in nature (Einstein et al 1910)

• Strong form: exact, continuum mec1ics (dynamics)
• Weak form: approximate, variational mec1ics (dynamics), convergence towards exact @ infinitum
• Energy form: account for all work (internal + external)

• (1) + (3): virtual force assumed --> compatibility imposed: Force method
• (2) + (3): virtual displacement assumed --> equilibrium imposed: Displacement method (Stiffness method & D'Alembert are special applications)

20/1:

1,

• i think the controlled damping ratio is not arbitrary ... but determined by (structure, weights) disregarding the excitation ... it can be aimed for ... use Wang Shengyin's paper ... to aim for a desired controlled damping ratio ... use his method to get the weights ... for SDOF ... only 1 mode ... for 2DOF ... 2 modes ...
• Shift in frequency: quantify how much the shift due to configuration of (structure, weight) ... then link to weights ... then to desired controlled damping ratio ... & form one unbroken chain ... s.t. all derived by just setting e desired damping
• Hysteresis: combine both algorithm (Runge-Kutta 4th order) & bilinear hysteresis loop (parallel lines & switching method) into a complete algorithm ... then either correct Matlab function ... or use them to modify into a customised one for the bilinear hysteresis

2,

how's the progress now? ... if i'm not wrong, it should be abt the following:

• Set-up configuration: varying each component (piezo precompression, voltage, structure M,C,K, devices: sensor types & link-up)
• Induced excitation: FRF of free response (given I.C.) --> FRF of controlled response & controls (given set-up configuration optimised, I.C.) --> relationship bet. both
• Controller: energy-based --> simulation: periodic, free (I.C.), forced --> expt. verify --> controller itself: either by direct energy balance (Wong) or by EMBC (Lynch)

help me take note of ... time delay ... within (SDOF system) & (from sensed to actuation) ... difference bet. simulation & experiment

1,

in nature ... we can notice certain distinctive patterns that are recurring all e time ... these include seasons, tides, sun/moon, etc. ... specifically, these patterns have a similar overall trend ... .i.e. rise --> climax --> fall --> trough --> repeat again ... this is exactly similar to our vibration oscillations ...

As it is natural for all engineering degree candidates to undergo FYP ... FYP can also be as a natural trend ... it has its ignition (our first meeting) ... its rise (literature review, basic fundamentals & tool-learning) ... its climax (problem solving, focused tool-making, procurement & setting-up) ... its fall (testing, consolidation of results, checking, verifying) ... its end (reporting & presenting)

the project is now into the climax ... yr tool (Matlab programs) is almost complete ... with some customisation needed for specific problems ... yr objective & scope are set ... u have created enough problems to solve ... u are now focused on solving these problems to produce e desired results towards objective ....

As a reminder ... i want to put this forward to u ... i want yr answer by this Friday ... on e expectation of this project ... i propose two choices (MCQ) ... i want u to choose only one:

• Consolidating: focused on solving present problems ... write & debug all needed programs up until hysteresis only ... then carried out results & analysis ... then explain them properly ... all targeted for future FYP to use or pick up rapidly ... not going through from scraps
• Progressive: present problems aside ... u want to go for bigger problems with much complexity in order to resolve complexities ... hence, this needs focus both on formulations & simulations ... that are supported by a suite of scalable programs for rapid testing ... a super-master program ... pick up more intensive problems to solve ... for example the hysteresis problem (Yang et al 1995) &/or benchmark problems ... an contender for publication

Give me yr answer on Friday

2,

in nature ... we can notice certain distinctive patterns that are recurring all e time ... these include seasons, tides, sun/moon, etc. ... specifically, these patterns have a similar overall trend ... .i.e. rise --> climax --> fall --> trough --> repeat again ... this is exactly similar to our vibration oscillations ...

As it is natural for all engineering degree candidates to undergo FYP ... FYP can also be as a natural trend ... it has its ignition (our first meeting) ... its rise (literature review, basic fundamentals & tool-learning) ... its climax (problem solving, focused tool-making, procurement & setting-up) ... its fall (testing, consolidation of results, checking, verifying) ... its end (reporting & presenting)

the project is now into the climax ... yr tool (piezo calibrated, structure made, Labview near completed, equipment linked) is almost complete ... with some customisation needed for specific problems ... yr objective & scope are set ... we have created enough problems to solve ... u are now focused on solving these problems to produce e desired results towards objective ....

As a reminder ... i want to put this forward to u ... i want yr answer by this Friday ... on e expectation of this project ... i propose two choices (MCQ) ... i want u to choose only one:

• Consolidating: focused on tuning e configuration of set-up to magnify control actuation ... justify the use of piezo actuation by formulation & expt. results ... then consolidate all results together with formulations & methodology ... compile, report & present properly to pass to next FYP
• Progressive: present problems aside ... u want to go for bigger problems with much complexity in order to resolve complexities ... hence, progressive in nature ... all the past efforts is to realise & exhibit the completeness of this piezo actuation by column base control ... this needs focus both on formulations & testing ... a complete investigation of piezo calibration, set-up control magnification & vibration suppression ... together with Labview realisation of controller & interfacing ... an contender for publication ... in addition to yr thesis & presentation & courses u taking

Give me yr answer on Friday

21/1:

1,

no need worry abt damping ratio ... the magnitude of controlled response (whether displ. or acc.) ... depends on the magnitude envelope ... exp(-dr*wc*t) ... dr: damping ratio ... wc: controlled natural freq. ... in 2nd mode ... wc higher t1 mode 1 ... then dr2 need not be too large ...

as a reminder ... i find that if i work too hard now ... & not able to carry on my enthusiasm & quality over ... not only e week ... e next month ... e next yr ... e next decade ... but to e end of my engineering career ... be it decades ... & every minute of it ... i'm expected to be a "Master" that is shown on my degree ... frankly, if i don't feel capable of doing it for life ... i should not aim for it now ... hence ... when there is a worry that progressive choice is shaky & not firmly achievable ... it's always ok to consolidate ... emotions aside ... let e facts & comparison judge ... view yr work objectively ... & see if e fundamentals are enough to carry thro ... i have learnt martial arts before ... i have cleanly forgotten all but one stroke ... i.e. the horse-stand ... easy pple say ... but not for "2" ... sustainability is as impt as that short-burst of super-achievement ... being 2-lasting is an often-neglected quality to survival ... look at Prof Ang ... hence, from now on ... i would concentrate on consolidating yr fundamentals ... always pointing to the back ... as a form of reminder

2, to lcarify ... i just learnt that ... alkali-silica reaction (ASR) is bet. alkaline cement & reactive silica only ... reactive silica includes:

Amorphous silica = most chemically reactive

Common reactive rocks:

opal

obsidian

cristobalite

tridymite

chelcedony

cherts

cryptocrystalline volcanic rocks

strained quartz

... avoid these ... else crack seriously ...

to avoid ASR … reduce alkali content … by replacing with pozzolans (with proper curing) as follows:

fly ash

blast furnace slag

silica fumesilica fume

natural fibre (e.g. rice husk ash)

& use non-reactive silica (e.g. sands) & aggregate

24/1:

2,

actually Quek is engaged with me ... u should have come in ... oso thought that time u show me was just probing it ... for actual piezo testing ... u need appropriate pre-compression (measurement of piezo deformation) ... last time we only agah agah tighten e bolts ...

oso ... in programming ... i advise u to be absolutely thorough with each & every component ... & their interactions together ... i uncover mang 2-lasting mistakes with thorough investigation ... i believe that if e problem is complex ... it can be broken down into simpler parts ... which u are super-sure works ... tried & tested ... perhaps u may like to try these:

• Simulate in Labview: forget yr step-controls for a while ... use continuous controls first ... i.e. whatever direction of abs vel. ... just apply control to oppose it ... if works ... then continuous control no problem ... ok
• Signal processing: interface properly all components ... excitation (if used) ... responses (displ, vel, acc) ... make sure u know all sampling properties ... & that they are measured at all discrete time that u want ... note avoid aliasing: sampling rate must be many times the highest freq. of the excitation/response signal ... if works ... then sampling no problem ... ok
• Switching mec1ism: now that ... control works all e time without switching on/off accordingly vel. ... & all signals are readily available at all discrete t ... then decision-making loop for switching needed ... ok ... test the switching meac1ism properly to ensure (direction) of abs. vel. can be detected ... then use it to toggle the control on/off ... in step-function manner ... ok ...Labview done
• Set-up: link-up all components to structure ... pre-compress piezo properly ... sensors set-up ... interface checks ... test: uncontrolled vs. controlled ... under non-zero I.C. ... periodic excitations ... random excitations

4/2:

2 & 1,

I c1ged my computer name on the network … take note (no more 'y2h7x2')

New network:

Start à Search à For Files or Folders à Computers à 'laiweeleong' à FYP2002

Use my name now … so easier to remember

2! … must return Dynamics book (Clough, red colour) Now … I can't renew … it has +2 holds already … as they say - the faster, the better

I'm on seminar this Friday - HDB reclamation … as now is really quite late in the FYP … from now on, u must show us yr progress & discuss yr problems sharply … time is lacking … in addition, take note that thesis writing is never ordinary report writing … if u have read the thesis writing website I email u … typing it is already quite taxing (u must follow the layout required by CE Office) … let's revise u of e following thesis points:

• Meaning of "Thesis": the word thesis means … the point that you are making … it's not no point or some blur corner in the bush … don't beat about the bush … in thesis, just go straight to the point … thesis writing is all about making that point (yr objective) only … in other words … yr niche
• Writing: report writing to us is quite common … but the difference is report is only for one particular tutorial scenario or one formula or one general topic … through yr Education … u must have met various forms of reports … some overview / survey: Literature review … some theoretical: Methodology … some testing/simulation/experiment: Results & Findings … even though a thesis has only one point … but its scope is larger … so thesis is like combining all the above types of reports … into one coherent, reasonable & logically-flowing argument … towards the point … writing then consists of 2 aspects: quality + quantity
• Quality aspect: the necessary condition … you pick out the main point … or theme & expand on it … essentially from thin-thick-thin … eventually, ensure that the reader gets what he wants … what u intend to do … what & how u did it … how it is applicable to him
• Quantitative aspect: the sufficient condition … length is strictly not a criteria … I have seen winning thesis of abt 60 pages only … & it is on wavelets in CE … I find that there are three types of scenarios here:

1. Brute force: settle down the thesis point & scope … expand freely regardless of length … unconstrained writing … normally very 2 … & very troublesome drafting & editing later on

2. Component-based: from objective & scope … divide-&-conquer … into smaller, simpler sub-objectives … write for each of these like a report, regardless of other sub-objectives … then combine them … then do overall editing to "tie the strings" so to speak

3. Coherent unity: write the thesis like single report … from the start to the finish … the writing & editing occur 1d-in-1d … write one section … edit this section together with all previous ones … hence, write a little … edit the whole lot (to ensure coherence) … the writing part is not like brute force (without regards) or component-based (only for the sub-objective) … you are writing (as in every single word or symbol or character) for this current section … in order to reach the eventual objective (niche) … this takes practice … but if you try it now … the next time you do so would be easier

Component-based would be balanced between e two extremes … I would recommend this … but I must emphasize … eventually all of us would tend towards coherent unity

6/1:

1 & 2,

I'm now writing my own thesis introduction … as with the pyramid approach … start with the very broad-based general idea … narrow down to active control only … I just realise Prof Quek's notes has very good L.R. on structural control … but it might slightly out-dated … try adding some later references … beyond this … we split into our respective focus:

• 1: focus on LQR, structure & feedback effects … formulations & simulation realisation
• 2: focus on piezo actuator, energy-based controller & experimental realisation
• Lai: focus on layered decentralised controller … formulations & simulation realisation

Also … I realise to quantify & compare our results objectively … we need appropriate criteria or effectiveness parameter(s) to illustrate & bring out the comparison more clearly … I like to suggest the following criteria for u:

• 1: in addition to damping ratio … if necessary … u can simulate more tests using the criteria set (found in the benchmark problem)
• 2: also consider same benchmark criteria … just pick one or two … also I have a thesis here on TLD control with successful experimentation … must tell to give u, I will forget
• I myself would using those same benchmark criteria

9/2:

1 & 2,

attached is my introduction that is relevant to u ... this is only a draft ... u may edit it for yr use ... plus additional literature of yr own ... beyond e intro ... we need to work closely together ... here i like to point out 3 impt aspects:

• Equations: each equation line is preceded & postceded by a single spacing line ... equation itself is centred ... right margin has numbering sequence (Insert --> Field --> Numbering, Sequence)
• Tables: i recommend 1 page to have 2-3 tables max. ... each table abt 3 inches vertically (to fit into 9 inch page) ... each table must have a Caption (Insert Caption), centred & above the table
• Figures: i recommend 1 page to have 2 figures max ... each fig. abt 4-4.5 inches vertically ... each fig. must have a Caption (Insert Caption), centred & below fig.

Only when u mention any formula, table or diagram ... then u put it in ... never put it in without discussing it ... this goes for references also ... pls quote properly ... never use [1], [2] etc. ... use the name e.g. (Kamada et al 1998)

also text is double-spacing ... essentially, they r telling us to write as short as possible ... so we should not write too 2-winded ... it saves paper, money, time & no wasted efforts (Theorem of Least Work) ...

oso ... never copy directly from others ... though an exception may be made for my drafts to u ... but they are only drafts ... use yr engineering judgement to write ... take it as a precious practice ... i don't believe we may get another such intense writing practice ever ... let's all treasure this most valuable experience

11/2:

t1ks for everything:)

hihi

just to update u on my progress....i have a talk witht the prof last week and they have just gave me new insights to the hysteresis model and so currently im very busy tring to comeup with the algorithm for it. So i thinki i will probably not be meeting up with the prof until i have come up with something concrete to show or if i have inquires to ask...till now im trying every effort to use all methiods i know to come up with it so that i dun dissapoint all of u.

Anyway t1ks again for the thesis sdample u send me:)

actually i have done some of the thesis already and still on the process of c1ging it:)

 but i think iwill be doing all i can for the hysteresis at least until march before i can touch ,my thesis again ...

i only hope i wont fail because i didnt manage to come up with the hysteresios portuion:(

i am trying all my best here too!!:P

also i havent met u since new year...so HAPPY CHINESE NEW YEAR TO U :)

2 & 1,

Engineering … whether physical or chemical or biological etc. … is essentially abt. E struggle between … capacity (good) … loads (bad) … there are then 2 scenarios:

• Capacity in equilibrium with loads: balanced thus no resultant forces/stresses … deformations/strains … energies (mec1ical or chemical or otherwise) …
• Mismatch between Capacity & Loads: non-equilibrium … no balance yet … thus resultant exists … the effect of the existence of this resultant … is that disturbances & c1ges would occur … in search of balance … possible c1ges include c1ges in structure, load distributions & subsequent capacities … this induced c1ge would always occur until the resultant is removed … i.e. balance is reached

Hence … engineering is our 1d in … reaching & maintaining this balance of capacity & loads … N.B. it is best to have the highest capacity/loads ratio … but loads would always be there … the challenge to us is … the HOW we go about engineering this equilibrium or balance … yet … aiming equilibrium by itself is naïve … the reason: balance may be unstable … implication: need to understand stability concept … there are three equilibrium states:

• Unstable equilibrium: a false balanced state or state of balance … like an inverted pendulum … the exact point where the mass tip is exactly vertical is equilibrium … however, given just a slight perturbation laterally … the pendulum swings & leaves that equilibrium point permanently … hence unstable in that point
• Neutral equilibrium: a moving state of balance … like a ball … u roll it … it stops … that's the new balanced state … the equilibrium c1ges with each perturbation … but not really unstable in that it might come back to its original position … hence neutral
• Stable equilibrium: a true state of balance … like pendulum with mass tip at the bottom … like grandfather clock … push the mass … it swings … under damping … it stops eventually at the same downward position … hence, remains permanently in balanced position … thus, stable

In structural engineering … structures are supposed to be stable & not collapse (ULS)… in that they satisfy the 3S: stability, strength, stiffness … hence, an unstable structure would have the following:

• K<=0: no (neutral, critical stability) or negative (unstable) stiffness … in other words … instead of resistance to loads … it magnifies or provides zero resistance
• Internal structure: the internal organisation of the elements & members … & connections & braces etc. … are not able to transfer the loads to the supports … hence, they are either broken, hinged, missing or not arranged properly
• Supports yielding, failed, insufficient restraints: supports provides the anchors … the members are able to have induced forces/strains … is due to restraints … hence no restraints or insufficient ones … would violate stability … e.g. in-plane structure: 3 DOF supported
• Strain energy criterion: by COE … E=constant>0 … hence dE/dx=0 … but if E increases without bound i.e. endlessly increasing … & dE/dx>0 … then energy keeps adding up & little or no dissipation … with corresponding magnification of transmitted energy … then the structure would rock itself to death … essentially no internal structure without K & poor supports

In structural control … passive damping takes away inherent structure energy transmitted due to seismic loads … passive control shifts the fundamental freq. of structure away from EQ main peaks … semi-active control takes or dissipates structural energy by using ext. power to operate the dampers only … hence, it does not inject mec1ical energy into the structure, it just takes away …

In active control … & composite or hybrid control … ext, power is used both for operating the active actuators … & also injecting mec1ical energy into the structure … as evident from the energy balance equation … as active control is using (control) energy to reduce or cancel out (seismic structural) energy … remember energy is actually waves … & waves can be superimposed … irrespective of whether it is linear or nonlinear … thus waves can be cancelled … so can structural energy …

The problem … is that under arbitrary excitation like EQ … & unmodelled dynamics of the structure … & assumptions (all not true):

• Instantaneous with no time delay: from ground into structure, from sensor into D/A, from D/A to controller, from controller to D/A, from D/A to amplifier, from amplifier to actuator & from actuator back into structure
• Linear systems: no material (inelastic, hysteretic) nonlinearity or no geometric (2nd-order P-delta effects, induced M from out-of-plane bending) nonlinearities
• No corruptions: in measurements, perfect instant sensing & actuation

As engineers … we know that the no. 1 concept is that things would NEVER be perfect & would ALWAYS be imperfect … hence, our active control must be insensitive to all the above problems … one way is … to ensure that:

• Current E do not add up: i.e. they do not accumulate … i.e. E=const. & dE/dx=0
• Effective control: E is reduced or eliminated … i.e. E is dissipated or cancelled out by injecting stabilising mec1ical energy … Et+1 << Et & dE/dt<<0 … best!

Here, E is the structural energy = SE + KE … only, so using the above criteria … CE must be able to achieve them … this concept is the Lyapunov 1st & 2nd methods … all energy-based methods that are equivalent in importance to Newton's Laws in mec1ics

2, below is a paper on active control

… it also uses energy c1ges as stability analysis … get e concept of using energy c1ges as stability criterion (focus on paper Section 4) … eq (4.1) is similar to ours: SE+KE = IE-CE =E … by tracking this E … together with the proposed energy-based control (to oppose destabilising velocity only) … show that the controlled structure is stable … with criterion: dE<0 always … this can be done by … similarly splitting one oscillation cycle into stages … like e way u explain to me how it works:

• Each stage: show trajectory of tip mass … show whether control … control direction & magnitude
• dE at each stage: show that dE for every stage is … dE<0 always
• Inter-c1ge of two adjacent stages: from one stage to another … e.g. from uncontrolled to controlled (due to destabilising velocity present) … also show that dE<0 …

Then … with this … infer that since the active control works in this way for every cycle … & that every cycle’s stages are all stable: dE<0 … therefore … dE<0 for all cycles … thus control stability is guaranteed … proved … then realise experimentally

http://ojps.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JCCOF2000007000001000073000001&idtype=cvips&gifs=Yes

18/2:

1 & 2,

As engineers … we are often always called to tricky & sticky situations to resolve … & we are expected to resolve them completely … that's why the social sciences people label us as problem-solvers … pple problems … we solve … supposedly & completely … situations can be:

• Tricky: there are 2 aspects - obvious & hidden aspects … the obvious aspects are that can be immediately or almost immediately … observed & detected … the causes derived … the remedies must address both the problems & causes of those problems … the hidden aspects are the tricky parts … they are like time-bombs that await the ignorant engineer who thinks he has solved the obvious portions … which might be master-minded by the hidden aspects …
• Sticky: there are limits to the resources - tools, labour, expertise, time, etc. … that can be used … some problems are just too extensive, 2-term & haphazard … sometimes here, other times there … there seems no apparent patterns or behaviour & no models & fundamental understanding to the phenomenon … these problems stick like mud … & the ignorant engineer who keeps the same techniques & methodologies against such problems … would find no progress in solution … due to resource constraints

Hence, we need to generalise our engineering approach towards tricky & sticky problems such that it can applied with confidence … independent of the problem domain …. Basically, this involves:

• Problem awareness: fundamental understanding of the problem … qualitative aspect: be able to conceptualise, simplify & reform into familiar & confident analogous problems … quantitative aspect: able to observe, detect & even model to support the qualitative aspect …
• Methodology: understand that e world system … as e problem system … is a dynamic & flexible one … in that … it can be altered & modified in such ways that can maximise the following … (Remedy effect) / (Constraints) ratio … the method must:

1. Amplify remedy effect: in our case … stabilise controlled structure … then, magnify active control efficiency & performance

2. Reduce constraints or restraints: reduce complexities, unknowns … by simplifications, verifications & re-configuring systems

Take the example of experiment set-up:

• What is the problem? Any hidden aspects?
• What are the resources (structure components, connections, sensors, controller, actuators & time left)? Have we utilised them all & to the maximum in the correct way?
• Have we amplified the control effects?
• Have we reduced the restraints that are confining our control effects?

Theory of Generalised Problem-Solving:

• Criteria: set a set of criteria or what we want to achieve by doing all these
• Problem understanding: awareness
• Selected solution: methodology to increase ratio of (remedy effects)/(constraints)

21/2:

2 & 1,

ReSearch is fundamentally a process of discovery … in the Spirit of Research … one of it is the spirit of an adventurer … I'm sure that there is an animal inside every one of us … it is both brutal yet can be tamed … the criteria is HOW we approach it such that it helps us … I discover that as an adventurer … it is the treasure or what we are aiming for … that provides much of the motivation & drive (or pple like to call Passion) … this treasure is like a carrot dangling on a rod in front of a rabbit, yet out of its reach … so near yet so far … the effect: we are set into constant motion, always trying to reach, but not getting … the implication: the process of reaching has far more impacts on us t1 the treasure … Hence, the "meaning of the drunkard is not in the beer" ???????… I realise by now that this is always true … we have studied so hard all these years … yet we cannot be guaranteed a carefree professional life … we are in fact obliged to work just as hard if not harder … in our future work … whereas for the FYP … supervisors have set a 2-term aim for each of us … it is near enough s.t. we can smell it coming as we progress … yet far enough s.t. we do not seem to be able to get it through … that is precisely the carrot or treasure …

Yet when we look carefully back on what we have done all this while … it seems that we are more influenced by the PROCESS rather t1 the objective … hence, if we are able to generalise & internalise this process of discovery within our hearts … I believe that there are few things in the future that can deter us from doing …

Process of Discovery:

The quadruple process of discovery involves:

• Curiosity leads to need to think & implement
• Development of thinking & discovery skills
• Personalised structural discovery skills: innovate your very own unique (niche) tingling with the unknowns
• Expert insights into discovery process

Rare is one who is able to master each & every one of the above 4 stages of discovery process … for he is unfazed by the treachery, torture & torment as he moves steadily, sometimes haphazardly, but always mindfully towards his niche … & yet when he really gets his niche … he said to himself the following words:

"What use do I have for this that I have not gained along the way?"

With that … he threw away his 2-loved treasure & walks off fulfilled

3/3:

10/3:

2 & 1,

In the niche perspective … each & every engineer has his own unique niche … or role to participant in … this niche has the following attributes:

• Uniqueness
• Individuality: specific to the individual engineer
• Dynamic: although unique, but not static … there is continuous variation of the niche … over time, space, context & circumstances (internal & external) depending on the system in question
• Fitness: to determine whether a niche fits an engineer … the engineer must try it … to see if it fits himself

To see fitness … focus on the interactions of the following:

• goods and bads
• up's & down's
• understand what we wish to do
• we can do
• we are willing to do
• the c1ces to do: opportunities … there are two aspects here … ????, ????

1. ???? Self-created: for situations that the engineer is comfortable, confident & experienced in … active sourcing for c1ces
2. ???? Open-hearted: the engineer understands the infinite complexity & uncontrollability of the reality … under the lack of infinite time & resources … with sometimes overwhelming constraints … that being active would only mean running 400m, come back sweating & absolutely nothing useful done … being active means being exhaustive … hence … the engineer settles down snugly into his routine niche … seemingly passive & retarded from the exterior … but … internally, the engineer is waiting … eagerly … the engineer knows circumstances are now greater t1 own capacity … hence, he waits … he goes into semi-active mode … being open-minded to all & every thing, man & methodology … he does not reject them due to past experiences … nor accepts them due to past knowledge … he attempts to reverse himself … to see the other sides of the problem … with open-hearted perspective

Our potential is measured by our fitness level … to reach our potential is good as reaching our niche … determined by the fitness … hence … our niche realization is equivalent to fitness … this consists of 2 chained processes:

1. Current niche: source for yr current engineering niche … focus on this niche, but maintain general relationships with peripheral issues … Jack of All, Master of One … & maintain this niche state … for as 2 as it is open for u
2. Niche transition: with the world affairs now … we can see clearly that the world is a crudely c1ging one … the only constant is c1ge … people always hope some dream state to happen … but an engineer does not work with any unrealistic situation … hoping that a niche found would always statically be there for a person … is the worst engineering disaster … the ignorant engineer of course would choose to defend … but a true engineer would give up … & quietly move on … the transition of niche is equivalent to the hydraulics:

• Turbulent layer transition: an abrupt shift & c1ge … where there are lots of c1ges, pains & agony … resulting large energy dissipation … what has been painstakingly built up over the previous niche … is now being eroded right in front of the eyes of the engineer … the engineer realises that he is not the king of his niche … but a lowly pawn of circumstances … the engineer needs to quickly internalise this state of affairs
• Laminar layer transition: a gradual shifting & c1ging … with internalisation of the current state … the engineer goes into niche-finding mode again … & flows along with the current … but not blindly passively following … only semi-actively waiting or creating for his new niche
• Wake transition: once bitten, twice shy … having encountered all this … & internalise it permanently … the engineer engages in his new niche with open-heart

Hence … what I like to conclude from this niche study are:

• Potential realisation theory: Niche-finding & fitness determination to reach our potential
• Niche transition: turbulent, laminar & wake layer transition phases … similar to what substances go through during processing
• Jack of All, Master of One: focus on yr current niche, but also cultivate various hobbies, likes & past-times … one day, they might come in 1dy … but never get distracted by them
• ????, ????: the engineer internalises this analogy … Subsystem à System à Suprasystem … for any one system that the engineer is currently focusing on … there is always a smaller, simpler & more fundamental subsystem below it … as well as … there is always a bigger, interactive & more complicated suprasystem above it … there are thus 3 states for any engineer:

1. System-level: maintain & train focus on the niche here
2. Subsystem-level: system too complicated … too many unknowns & assumptions … reduce to a more fundamental, simplified level … in energy terms … the engineer goes into a lower trophic level … from research … the lower trophic level, the more stable & comfortable it is … but people at higher trophic levels might despise u … choose to suit problem
3. Suprasystem-level: system does not provide sufficient insight … it is ok for some things … but is seriously lacking in others that the engineer is now interested in … hence the engineer groups, classifies, re-perceives & re-constructs from all other angles (Zeroth Law of ReSearch) … to uncover to discover the hidden interactions or misconceptions or illusions

There are two extreme levels to the potential realisation theory:

• Individual: to realise one's own niche potential, that is continuously varying with circumstances
• Macro-level: encompasses more t1 one individual … the aim is to realise the potentials of its members … e.g. our society … the authorities would shape & influence in such a way as to uncover sufficient niches of quality & depth … to ensure that its members (people & engineers) can find their way towards their niches … currently this level is too far-fetched for us students … but cultivate this as a part of Jack …

13/3:

1 & 2,

Below are a check of all necessary thesis components:

• Title: for thesis … as well as a shorter one to print along the stem of the thesis book during binding

• Abstract: the most important … the first to be inspected … all yr findings towards e niche thesis must be summarised here … if this is not written well … the rest would be ignored

• TOC: table of contents … nomenclature … tables … figures captions

• Introduction: general background … literature review (narrowing) … objective … scope (expand on objective, exactly what things to research on the objective) … layout (chap 2 what … chap 3 what)

• Body: summary sentence … problem definition / formulation … theory (equations) … methodology … verification/validation … tests … results (tables, figures) … findings: results with discussions back to the objective

• Conclusions: conclusions … back into objective … exactly what u find abt each scope component … successful, why & implications … fails, why & implications … suggestions for future studies (what u always to do but cannot)

• References

• Appendix: things like … program codes

Keep clear

Keep simple

Keep short

21/3:

2 & 1,

In the potential realisation theory … we need to be aware of our niche … as determined by fitness … w.r.t. 謀事在人, 成事在天 … at any one time … we can be only in either of the 2 mutually exclusive scenarios … (1) within our niche … (2) niche transition: turbulent à laminar à wake … resulting in the rule-of-thumb: Jack-of-All, Master-of-One … this however is too loosely formed to be useful … hence an urgent need to reformulate this into a engineering niche for all ReSearch

With the presence of:

1st Law of ReSearch: feedforward open-loop generic technique … inherent in all operations

Zeroth Law of ReSearch: feedback closed-loop fundamental technique … inherent in all rectifications, awareness & understanding

Yet … all research tasks & events do not only involve the doing (operations, implementations) … & the corrections (realisations, fundamentals) … the events would ultimately involve concepts … yet no one can clearly define concept … as it is a virtual idea with actual realisation or implementation … the concept influences the operations & understanding … the operations & understanding shapes the concept … hence there is always a closed-loop relationship between conception (virtual form) & concretion (actual form) … this is analogous to dreams & reality … how many realise our dreams, yet who can live without dreams? … to concrete is to cut off aspects of concept … to concept is to modify concrete … is there a dilemma or in engineering, a compromise/tradeoff between conception & concretion? … the solution or resolution is in the … interface … interaction … or architecture … of both elements of concept & concrete … yet interaction is still as undefinable as itself … to inter-act is to act in related fashion … with influences both within & without … both internally & externally … in other words, in dual mutually-exclusive extremes … the extremes in turn have their own respective extremes … forming infinitely-chained processes

hence, with this understanding (from Zeroth Law of ReSearch) of the influence of interaction on the balance between conception & concretion … the following 2nd Law of ReSearch is derived:

2nd Law of ReSearch states that all processes involve arbitrary chaining of the basic configuration of subsystem-system-suprasystem, with the system as the event-of-interest, where for any system, there would always exist a more fundamental, smaller, simpler, more rigid, less flexible, less powerful;, more stable & less interactive system – subsystem; and there would always exist a more complex, larger, less rigid, more flexible, more powerful, less stable but more interactive system – suprasystem.

Thus … with the subsystem-system-suprasystem basic form … any process can be potentially understood … if it is too complicated or illusionary … there can always be a simpler way to perceive, model & understand it … hence, when the engineer encounters a problem that is just overwhelming … the engineer does not dive into the concretion … the engineer falls back onto conception … with conception, the engineer interacts the relationship at levels that the engineer is fundamentally sound … & because there is always such a subsystem … the engineer can be assured of preventing progressive conceptual collapse, hence preventing actual concrete engineering disasters … potentially this means that all disasters can be avoided … if the 2nd Law of ReSearch can be internalised within the engineer … if only lay engineers can take tasks at their strides & capacities (know yourself)

Yet … there can be the opposite … now that the system is firmly supporting the engineer … the engineer engages in internalising the system to become routine … the act of routine is an act of future complacency … hence, the engineer moves into the suprasystem … to understand things that baffles him, that he has assumed, ignored, neglected, modified or given in the past … he needs new & extended insights into the process … hence, suprasystem is derived from Zeroth-Law of ReSearch … this can be from linear à nonlinear … from statics à dynamics … from elastic à inelastic etc. … because a suprasystem always exists … potentially this means that all & everything can be known & engineered … that there is always hope & inert confidence for engineering events … if the 2nd Law of ReSearch can be internalised within the engineer … if only lay engineers can internalise open-hearted spirit towards the surroundings (know adversary)

In summary … the 2nd Law of ReSearch is formed by the basic configuration of subsystem-system-suprasystem … where focusing on the system is the niche … focusing on the subsystem is the careful, pre-emptive protective stabilising approach … focusing on the suprasystem is the hopeful energising exciting vigilant approach… hence, a rule-of-thumb is:

If it is too difficult, go easy

If it is too easy, go difficult

Eventually … provided inherent damping exists … the mutually cyclic shifting between the extremes would settle at hopefully a stable equilibrium position … but life (not to say engineering) is an unstable phenomenon … hence the following trends:

• Simple things would always complicate over time & circumstances

• Complicated things would always simplify over time & circumstances

• Oscillations always exist between the shifting extremes of simplicity & complexity

I’m not sure where this would lead to … but neither does the engineer … hence, the engineer does not argument or debate or probe into issues of such nature … as the engineer knows that he should only focus & focus only on his niche … & little else … hence, with this … I like to end this prolonged annual research into the basics of research with u … t1k you for yr attention …

May the Engineer be with You

25/3:

1 & 2,

Like to remind more thesis comments:

• First things that people would read: abstract (summary), Objective & Scope, conclusions

• If these are not well-written …….

• What to do: objective

• Which aspects of the objective to concentrate on: scope

• Methodology: how to reach the scope to get to the objective

• Findings: what exactly you discover … works, why & implications … fails, why & implications

• Conclusions: must contain objective … scope: what you set out to do & what exactly you find out about the particular scope … take this analogy … start from one end of a string (as objective) … then tie back the other end of this same string to its head (conclude all yr findings into the objective)

• Abstract: the summary of conclusions … the essence of yr thesis (the point you are making) … remember the chicken essence analogy

• Tables: title above

• Figures: title below … if discussed directly in text, must include in text … never in appendix (especially those not even mentioned or used)

26/3:

On the other 1d … the objective of doing things … is realistic & useful to others … hence the engineer would reserve his engineering spirit to the focusing & targeting straight into the objective & the scope … not some rojak corner in the Bush? … the engineer knows that when it comes to the crunch … when things comes to the finale … it is not the adventurer with his virtual unrealistic philosophy of 醉翁之意不在酒 that the engineer should even look at … for he knows that if he did … he would truly become a 醉翁

4/4:

1:

• Switching of the stiffness path in the bilinear hysteresis loop: catch point of c1ge (1^st linear or 2^nd linear path; loading or unloading path) à alter stiffness
• Jerks or spikes of acceleration frequencies: occur only for bilinear hysteresis only, none for bilinear à hysteresis implies c1ges in stiffness from loading to unloading phases à jerks in acceleration: little impacts à no physical, not experimentally proven

3/5:

• Preparation for Presentation
• Presentation and FAQ by both examiner (Balendra) & supervisors (Ang & Quek)
• Thesis refinements, if needed
• Thesis printing & binding: I advise u to hard-bind all à it’s worth it after a year’s efforts
• Thesis pass-up

• Questioning & examining: from all angles à concepts, fundamentals, development, overall scheme, detailed implementation, tests (why & why not), results, conclusions (towards O&S)
• Scrutiny: based on both yr soft-copy drafts & presentation

• Clarity (Ang): O&S (problem to do) à methodology (what & how you did) à conclusions (towards O&S)
• Fundamentals (Quek): the basis for problem-methodology à assumptions à derivations à implementations
• Applications (Balendra): how mec1ism actually works (or not) à what limiting factors or aspects à how you overcome them or what you did à to reach the O&S à how it may be expanded: possible uses
• Use thin-thick-thin approach: start simply (e.g. O&S, overview: must be correct, keep checking) à expand (parameter, devices, methodology, results) à summary (findings & conclusions towards O&S): critical