Ms2004 Round Table

"Contribution of Models to Research"

Panel: Dr Laurence Cheze (France, Biomechanics), Pr Houcine Chafouk (France, Automatic control), Pr Lionel Collet (France, Physiology), Pr Norbert Dillier (Switzerland, Audiology), Pr Nashaat El-Khameesy (Egypt, Economy), Pr Aladin Zayegh (Australia, Electronics)
Moderator: Pr Christian Berger-Vachon, Dr Emmanuel Perrin (AMSE)

Question 1: "What is, in your field, the contribution of models?"

Dr Cheze: Several subfields are considered: Human movement, car crash… The clinician collects the in vivo data and mechanical engineers build up a model corresponding to that behaviour. Then a quantification is made using numerical analysis. In sport, gestures are studied. Modelling cannot be conceived without a validation.

Pr Dillier: When we try to understand how the human body works, we are thinking in terms of models. In my field, models are used for improving auditory prostheses. For example, they are part of loudness compression and feedback cancelling algorithms in hearing instruments to reduce the "whistling" effect. Simulation techniques for biological phenomena have been widely covered in the keynote address.

Pr Collet: Physiology of the organ of Corti is a true example. The first auditory model built up by Von Bekesy explained the frequency analysis done by the ear and he won the Nobel Prize for this discovery, but it did not explained the amazing ear selectivity.
In 1961 Gold pointed out the fact that Von Bekesy worked on a dead cochlea.. and some life action was likely to occur. If so ears could emit sounds. In 1978, David Kemp recorded otoacoustic emissions and it has been established that they reflected active mechanisms at the level of outer hair cells.
In future, we would like to model the influence of aging on the auditory system and the signal to noise ratio influence.

Pr El-Khameesy: Modelling started with engineers and was extended to business. We had to find adapted tools in our field, such as marketing, and to introduce intelligent agents.
In marketing, multilayers models are well adapted and semantics becomes part of the model.

Pr Chafouk: The example is the automatic control a system following a human behaviour.
Let us take the example of vehicles and pollution. Models of particle emission are established, and simulation of motors is made (from the pollution point of view). Models to reduce the emission of particles are then made and a validation with a motor is done. It is easier (and cheaper) to work on models than to work on motors. Interesting solutions are then tested with real motors. The issue is the planet (environment)… it concerns cars and planes. Although airports are built in open land, pollution in the neighbourhood is rather high.

Pr Zayegh: In engineering and science education, modelling and simulation are vital tools nowadays. They provide students with facilities which can maximise their understanding in many areas in short time and minimum cost. For example, in experimental work, the following steps are necessary:
-The preliminary work based on theoretical analysis can be consolidated and justified by modelling and simulation. The students go to the laboratory with "open eyes".
-In many cases models can be developed, programmed and tested before physical assembly of such system (Feasibility study in many system design)
Theoretical results, simulation results and experimental results are compared to consolidate and justify many design projects,
-modelling is quick and cost effective method in many cases. It is the practical solution in high cost, high risk areas. It is the logical step before physical prototyping.

Many models are components in a library, they can be assembled to develop large systems. There are some areas where modelling and simulation are the only passage for teaching. For example, in microelectronics, millions of transistors and other components are used in integrated circuit design. That cannot be physically implemented in education environment. We start with a simple model of transistor and finish up with sophisticated architecture.

Question 2: Do you use models in education?

Pr Zayegh: Modelling and simulation are educational tools; models are "virtual reality". We must not loose the track and accept modelling to replace mathematical analysis. The proper education process should have the following steps in problem solving:
-hand analysis and calculation, modelling and simulation results, practical results from physical system and comparison for understanding and improvement.

Pr El Khameesy: educational programs for students should contain "model boxes". With model boxes we build up big simulators such as plane pilot simulators or video games.

Pr Dillier: Simple exercises to get used with the methodology are taken first and then students go deeper into the more complex model systems.

Dr Cheze: In mechanics, finite elements models are classically used in teaching sessions.

General remarks from the audience

1) Students try to avoid mathematics and now formula are introduced (and hidden) in the model boxes.

2) Industry does not like models too much, it prefers real behaviour. In models too many assumptions are made, and one can become suspicious.

3) Uncertain models simulate man's behaviour. Fuzzy logic brings bits of human uncertainty into the models (human being cannot always be predicted). This family of non deterministic models should be a new step in modelling.

Finally: Model is not only an efficient tool in Research, t is also a true science in itself, true science which is worth to be taught and used wisely