mw1 research

8/13/2019 Mw1 Research

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HowtodoresearchGiorgioButtazzo

[email protected]

http://retis.sssup.it/~giorgio/h2d.html

AimofthecourseTo provide some

hints on

what to doand

whatnotto dowhen you areinterested in:

doin research

writing papers

presenting your results

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Outline

1. Howtosettleforresearch

2. Howtowritescientificpapers

.

4. Gettingintothepublicationprocess

5. Howtomakepresentations

6. Simulatingasmallconference

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MeaningofresearchResearch = Re - Search

Re again Search examine carefully, try, test, probe

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Detailed study of a subject aimed at inventing new

solutions for specific problems (engineering approach).

Research

Detailed and systematic study aimed at discoveringnew knowledge about our world (scientific approach).

Scientists vs. EngineersScientists

Interested in the world as it is

Goal: understand how it works

Discover laws on what already exists

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Engineers

Interested in changing the

world

Goal: solve practical issues

Invent something that does

not exist

Basic vs. Applied ResearchSome people like to distinguish between:

Basic research

aimed at advancing our knowledge with little concern

for any immediate practical benefits.

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Applied research

aimed at achieving some practical outcomes that are

useful to the society.


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Good vs. BadResearchSome other people prefer to distinguish between:

Good research: rigorous scientific study aimed at

advancing knowledge and producing new results that

(sooner or later) will be useful for the society;

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Bad research: study aimed at producing specific products

without long term objectives or general implications.

According to this view, a research is applied if there exists

someone capable ofusing the results to build practical things.

Theory vs. Practice The believe that a theoretical study is not useful to the

society is completely wrong!

Whats more relevant for the society? The theory of

electro-magnetic field or a practical study to optimize a

screwdriver?

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PasteursQuadrantbyDonaldStokes,1997

Quest for

HighPurebasic

research

Useinspired

research

Niels Bohr Louis Pasteur

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Fun amenta

Understanding

Consideration of use

Low High

Low Pure

applied

research

Bad

research

ThomasEdison

WhatisEngineering?

Cost-effective

Engineering is the development of

cost-effective solutions to practical problems,

through the application of scientific knowledge

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Considering design trade-offs on resource usage

Solutions

Emphasis on building devices, but also methodologies

Practical problems

problems that matter to people and improve human life

Application of scientific knowledge

Systematic use of analytical techniques

ElementsforasuccesfulresearchThe path to success consists of three simple elements:

Find what interests you that you can do well and is

needed by the people. - Lui Sha

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your

talent

your

interest

social

needs

Elementsforasuccesfulresearchyour

talent

your

interest

social

needs

Understading yourself

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What is easier for you, writing a complex

software program or proving a difficult theorem?

What excites you?

What excites the community?

Does it fall into your skills?


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Researchstepbystep0. Find

a

topic 1. Understandthefieldandthe

applicationdomain

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2. T in o

the

problem

3. Forma ize

the

problem

4. Findasolution

totheproblem

Researchstepbystep5. Validate

your

solutioninpractice

6. Compareyoursolutionagainstexisting

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ones

8. Communicatethesolution

totheworld

7. Extendthesolutionto

moregeneralcases

Typicalresearchprocess

idea

start with simple

assumptions

model

use examples

and simulations

conjecture solution

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clean upgeneralize

more realistic

assumptions

1. Understandingthefield Why is it important?

What are the mainapplication areas?

en y e ey componen s an o your

system.

Whatdisciplines areneededtounderstanddetails?

Doyouhavetherequiredexpertise?

Ifnot,whichcoursesdoyouneedtoattend?

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1. Understandingthefield Are there ethical issues involved (e.g., weapons,

animals)? Better to clear these things up before

starting.

a o peop e a a rea y wor e on e op c o

know tricks, shortcuts, and bottlenecks.

Read the documentation related to the main

components (HW and SW).

You must become the Master on that subject.

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Read the literature related to your problem. Search

on the right conference proceedings (ask your

supervisor about the top conferences in the topic).

Conference papers have more recent results.

1. Understandingthefield

Get familiar with thework done before(if any): use

tools, read the source code, run demos, test the

system functionality, discover critical points and take

notes on strange behaviors.

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Commonmistakes Think, plan, read, and never

get into the main game

Reading is important, but it is also

important you start experiments, simulations and analysis.

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.

When reading papers, be critic,

never take everything as a dogma.

The highest impact on research is due to

novel ideas that criticize imprecise thinking.

Read papers as a reviewer!

2. Thinkingofaproblem What is thenovel contributionyou would like to give

to the field?

Make a wish list, from big dreams to smaller (but

.

Which features would you like to have on your

system?

Go back to the literature to see if some problem has

already been solved.

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Commonmistakes Choosing a wrong direction

Your supervisor may have the

experience to advise on this.

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Too simplistic assumptions

Nobody will be interested in a

solution that is not applicable

to a real situation.

Commonmistakes The problem has already been solved

Carefully look at the literature!!

Dont getdesperate,youmay

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;

Extendtheexistingsolutionto

moregeneral

cases;

Slightlychangetheproblemto

covermorerealisticcases;

Findanotherproblem.

3. Formalizingtheproblem If the problem is too complex, break it into a set of

smaller subproblems.

Build amodelof your system:

C ear y i enti y t e assumptions you nee to simp i y

reality (butnot too much);

Define the metrics for evaluating the outputs of your

system and its performance;

Define the systeminterface.

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3. Formalizingtheproblem Distinguish variables between:

System parameters(variables you dont want to change);

Input variables(primary variables affecting your method)

Design variables (variables you want to change to apply

your control actions);

State variables (variables describing the system state and

behavior);

Output variables (variables you want to measure to

evaluate the performance of your method).

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3. Formalizingtheproblem Find relationsamong the variables: how outputs are

influenced by inputs?

If relations cannot be easily derived by the physics,

make experiments:

Decide asingle input variable;

Decide asingle output variable;

Fix the others as parameters;

Vary the inputvariable in a given range;

Measure the outputfor each value of the input.

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Example1Determine the timing of a traffic lights in a crossroad:

What are the relevant variables?

duration of green (G)

eriod T)

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STOP

STOPS1S2

S1

S2

GT

flow in each road (i)

queue lengths (qi)

average car speed (v)

average delay of a car

Example2Design a communication protocol in a computer network:

What are the relevant variables?

number of nodes n

network to olo

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average load

message size M

message rate T network bandwidth B

end-to-end delay D

error probability p

Example3Design a control algorithm for a robotic device:

Relevant variables

ball position: x

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Ball & Beam a spee : v

beam angle:

servo angle:

sampling period: T

settling time:

overshoot:

ball mass: m

ball radius: r

beam length: L

ball's moment of inertia: J

gravitational acceleration: g

System parameters

4. Findingasolution Experiments can give good hints for finding a

solution.

Even theoretical results can come to your mind by

first looking at experimental data.

Sometime, experimental data can be performed to

find counterexamples. Counterexamples brings

usually bad news, but they are extremely useful to

identify critical situations and countermeasures to

avoid them.

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4. Findingasolution If the solution is an algorithm, evaluate its

computational complexity. If it is too high, simplify

the assumptions or try heuristic approaches.

Write notes and comments every week to

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mon tor t e progress o your researc :

problems encountered (how you solved them);

experiments you carried out;

assumptions you are making;

scenarios you have considered, etc.

Everything will be useful when you write a paper.


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5. Validatingthesolution Implement the solution;

Apply the solution to one or morespecific cases;

Evaluate the performanceaccording to the metrics

previously defined, under several conditions

(different values of the input or state variables).

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5. ValidatingthesolutionOften, evaluating the solution on a simulated system is

more practical and reasonable. In this case:

input or state variables should be generated as

random numbers within given ranges and realistic

distributions.

output variables should be averaged onseveral runs

for each input configuration.

Remember to record both mean and variance for

each set of output values.

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6. Comparingthesolution Search the literature to find different solutions to the

same problem;

Identify all the differences (assumptions, model,

com lexit erformance

Implement the best methods you have found.

Run thesame set of experimentsfor each approach.

If your solution performs worse than the others for

all possible scenarios, then you are in trouble.

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6. Comparingthesolution Before giving up, make sure you compare the

approaches with respect to different metrics:

often its reasonable to sacrifice performance for

a lower complexity or a more realistic model.

Sometime the improvement is observed only within

a certain range of the input variables.

This can still be interesting, since that range can

occur for particular systems, for which your

solution can be more appropriate than the others.

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7. ExtendingthesolutionGo back to the assumptions you made to simplify the

system model:

Are there assumptions that are too artificial or

restrictive?

How the solution and the results would change by

relaxing those assumptions?

How could the model be enriched with more

variables describing more details?

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7. Extendingthesolution Are there other components to be considered?

Is the analysis tight? Is there space for

improvements?

Are experimental results complete?

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8. CommunicatingthesolutionAs soon as you have got an interesting result, write a

technical report, do not wait until the whole project is

finished.

Remember toregisterthe technical report and put it

on your we page.

If the work is done together with your supervisor, ask

him/her torevise it and put it on his/her web page,

which has much more visibility to the external world.

This ensures you the paternity of the result, in the case

somebody should publish a similar work.37

8. Communicatingthesolution Then, select a conference with your supervisor and

write a paper for that conference. This is important

for receiving a quick feedback (normally after 23

months) from a number of reviewers.

In the meantime, you can keep working to extend

your work.

If the paper is accepted, you have to make a

presentation at the conference. This is a ver y

constructive experience, which is important for a

number of reasons.38

8. CommunicatingthesolutionWhy presenting a paper at a conference is important?

You have the unique possibility to join a community

of experts andexchange interesting ideas;

After your presentation, some people can give you a

feedback to improve your work;

You have the possibility to attract the interest of big

gurus in the field and to make contactswith a lot of

interesting people.

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8. Communicatingthesolution With the feedback you received from the reviewers

and from people at the conference, you can think of

writing astronger paperfor a journal.

The issue on how to write a research paper will be

covered in detail later on.

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Generaladvices If you have a hard deadline,dont rely on someone else.

Most students underestimate the importance of

physical aspects, such as:

Using asensorto acquire data into your program;

Making an actuator to move and build a function

that controls it as desired;

Orderingdevices and have them on your desk;

Makinga new printed circuit from scratch;

Solderingcomponents and testing them.

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Generaladvices Write down an idea when you have it, because you

may easily forget it by the time you get to the office.

Some ideas come early in the morning, so keep

paper and pencil on your bedside table. Some ideas

, .

Do not be afraid to admit your ignorance. In academic

research one is continually venturing into new areas.

Perfectionism and attention to detail is a virtue.

Taken to excess, it is a vice.

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Howtogetideas

Make aselective reading: quickly go through the paper

Read widely, but remember, reading is not what

research is about. Too much reading could be a major

danger that could prevent new ideas to flourish.

,

specific points. Questions to always have in mind:

What is the main problem to be solved?

What are the main assumptions.

If you dont understand the math, make a step back to

learn and then return to study the approach.

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Howtogetideas What to read?

conference papers are the most up to date, but

often details are available in technical reports.

Most of the time theke ideais not in the details

but in the methodology.

When details are important and you cannot find

them, contact the authors directly by Email:

Often they feel honored to be considered and will be

happy to provide additional information on their work.

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Howtogetideas Reading approach

Some degree of skepticism is appropriate when

approaching most papers.

Dont trust anythingyou read.

Verify the theoretical results and judge theassumptions trying to imagine them applied to

your system.

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Howtogetideas? Thinkofsomepracticalissue

Startfromproblemsthatreallybotheryou:

Dissatisfaction isthemajorsourceofinspiration

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Howtogetideas? Bedrivenbypassions

PassionisoneofthestrongestforcesinNature

Searchthewebusing

combinedkeywords,like:

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music&statistics

painting&algorithms

biking&sensors

soccer&measurement

Youwillfindinteresting

unexpectedresults.

Howtogetideas? ObserveNature(Animals,plants,phenomena)

AllsolutionsfoundbyNaturearecharacterizedby

HighEfficiency

Beautyandelegance

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Howtogetideas? Lookintootherfields

Getknowledgefromotherfields:

differentproblemsmayhavesimilarsolutions

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At the beginning,

documents were

written using a

single font: Courier

Many different fonts

are available today

much nicer to read!

An example:

Howtogetideas?An interesting story

Simply out ofcuriosity, Steve Jobs decided to attend a

calligraphy course, where he learned all about

typefaces, fonts, letter spacing, and what is needed to

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.

The course had no practical value that he could

imagine, and he took itjust for pleasure.

Ten years later, his experience was crucial for the

design of the Macintosh user interface, which set a

standard for all word processors.

Howtogetideas?What do we learn?

Curiosity means pursuing something that

does not necessarily have an obvious

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.

We examine something merely because it

seemsinteresting. Later, we may discover unexpected

connectionswith what we are doing that can

form the basis for new ideas.

Somehints Its very usefulmaking lists, and thenorganizing them.

Examples are lists of questions, possible experiments,

possible surveys, sources of data, etc.

Imagine the results of experiments before making

them: if the results were to be ..., then we would

conclude .... otherwise our conclusion would be ....

Think of an experiment that nobody else has done,

and do it. The emphasis here is on doing something

because it can be done, not because you actually

understand the implications.

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TakeadvantageofbeinginaLab Talk to peopleto know what they are doing.

Ask successful researchers in your department if

the have articular methods for ettin ideas.

Whattodoifyoudonthaveideas?

Attend seminars: you can find interest topics and

you learn how to present (or not to present).

Brainstorm with your colleagues about problems

they have.

Collaborate with someone on a common problem.53

Whattodoifyoudonthaveideas? Criticizeapaperbysomeoneelse:

Are there assumptions that are too artificial or

restrictive?

How could the model be enriched with more

variables, describing more details?

Are there other components to be considered?

Is the analysis tight? Is there space for

improvements?

Are experimental results complete?54


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Whattodoifyoudonthaveideas? Buildontopofexistingwork:

Can I improve the experiments?

Can I improve the theory?

From deterministic to statistical analysis.

From fixed priorities to dynamic priorities.

From uniprocessor to multiprocessor or distributed.

From single goal to multiple goals (feasibility + energy)

Can I build a tool that does it automatically?

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Whattodoifyoudonthaveideas? Reducecomplexity

System are becoming more and more complex

Sometime too complex to be properly used or

Simplification is a very promising process in the

future at many levels:

Less computational complexity

Smaller program size

Simpler interfaces

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SeekforsimplicityAchievingsimplicityisverydifficult,because

Simplicityimplies:

deepunderstanding

distilling

beautyandelegance

Itneedstime,

Goodideasneedincubationanddeepthinking

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ExamplesinscienceE=mc2

F=maF=kx

V = R I

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f actori al (n) {

i f ( n == 0) r eturn 1;return ( n * f actori al ( n- 1) ) ;

}

AchievingsimplicityStrategies to handle complexity:

Partitioning

so a on

Abstraction

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Partitioning

It is the process of dividing a system into independent

parts that can be studied in isolation.

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Isolation

It is the process of focusing on a specific component, to

understand its behavior in relation with the others:

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Abstraction

An Abstraction is a concept that connects a set of

items as agrouporcategory.

Abstractionsreducethe information content, retaining

what is relevant for aparticular purpose.

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ball

Abstraction

InComputer Science, abstractions allow program designers

to separate methods from implementation mechanisms,

so that they do not depend on software or hardware:

Examples

A queue

A resource manager

A virtual processor

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AchievingsimplicityTechniques to simplify a process:

Reducefunctionality

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Hideextra functions

Organizeyour knowledge

Reduce

Today, new functions are included just because it is

possible, not because they are needed.

Reduce functionality

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Reduce

Balance betweenessentialandfancy

Crucial issue to be addressed

What to remove?

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set mode

c lock alarm

downup

date temp


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Reduce

Simplicity saves you time. And time is value.

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UP DOWN

clock alarm

Hide

If you cannot reduce any further, hide nonessential functions.

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Crucial issues to be addressed

What to hide?

Where to put?

Hide

Extra functions can be revealed only when

needed

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Hide

Hiding can be hierarchical

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Organize

Group similar items into categories

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Organize

Making a taxonomyis crucial for grasping the key

features of a set of similar items:

State of the art papers

Scheduling algorithms

Control schemes

Poweraware strategies

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Organize

When I started working onNeural Networks:Back propagation

Kohonen networks

Q-learning

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Self-organizing maps

Reward-Based Functions

Recurrent networks

Associative networks

Competitive learning

Hopfield networks

Reinforcement Learning

Organize

Slowly some order emerged from the chaos

Learning paradigms

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supervised competitive reinforcement

Hopfield Back-Prop. Kohonen. ASE-ACE Q-learining.SOM.

Organize

Rate-Monotonic

Deadline Monotonic

EDF

The same thing happened onRealTime Systems:

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Sporadic Server

Priority Inheritance

Priority Ceiling

Slack Stealer

Least Laxity First

Fixed Priority Scheduling

Polling Server

Organize

The same thing happened on RealTime Systems

Scheduling algorithms

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Fixed-priorities

RM DM EDF LLF CBSPS

Dynamic priorities

periodic aperiodic periodic aperiodic

DS TBS

Organize

Strategies useful for achieving organization:

List all the features

Sort

Group into categories

Integrate (reduce to fewer groups)

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Organize

The key of software organization:

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VERY IMPORTANT

a TAB character is not equivalent to N spaces


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Organize

void sort(int *v, int n)

{

int i, j; // array indexesint min, k; // value and index of minimum element

int temp; // temporary variable

for (i=0; i

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