First some background: I am an electrical engineering student working on the electromechanics of granular materials. I am *not* an expert in CA or any of the related areas---I just know enough to get by. The research atmosphere here is: "Huh, cellular automata? That sounds interesting." That is, almost everyone involved with my thesis is basically a beginner.

My experience has been an uphill battle all the way. At first, my advisor was somewhat hostile towards my intended research. He has been involved with particle electromechanics for many years, and my proposal to study the electromechanics of many (~ 10,000) particles using a CA-like method was too alien for him to accept. However, I, being a stubborn person, kept pushing him in that direction by various devious ploys. Finally, my persistence paid off, and he started to understand why I chose to employ ideas rooted in complex systems and CA. The bottom line is that I'm defending my proposal in two weeks, and the reaction of my committee has been surprisingly positive. The concepts and elegance of CA and related subjects appealed to them. My thesis advisor is even looking for students to continue my work after I graduate!

Just in case anyone is interested, I'll describe some of the more interesting aspect of my problem:

- I deal with chargeless, finite volume, mono-sized, polarizable,
spherical particles driven by a time and spatially varying

electromagnetic field on a square lattice. - The particles are not treated as test particles so they affect the
local field and thus have mutual influence upon each other (many-body
problem.)
- I have free surfaces which separate the phases (coastline between
"holes" and particles). I am interested in the formation of field
induced microstructures with self-similar features at different
scales.
- Because I work with finite volume spherical particles, collisions
can almost instantaneous propagate momentum out of a local

neighborhood if a path of connected particles exists. Consequently, during any time-step, a particle's state at a given site of the lattice can be affected by particles outside of a local region. - I used a probabilistic approach to define "velocities" of particles
on a lattice. For each time-step, the probability of a particle
moving is proportional to its "velocity" vector. As a result, the
system is reminiscent of the flow of probability densities in a
limited form of phase space (a point in configuration space X a
distribution in velocity space.) Also, I had to come up with some
guidelines to interpret the occurance of physical events (something
like making an observation in quantum mechanics.) This aspect of my
thesis makes me very uneasy. My friends in the physics department
didn't laugh at my ideas too much so I guess my guidelines are not too
unreasonable. One of them even suggested that my probabilistic
approach effectively increased the symmetry group of the underlying
lattice space.
- From preliminary results, I came to the conclusion that a square
lattice is not adequate. By the way, I know of the results from
Lattice Gas Automata, although I don't understand the group theory
behind it. My problem is the limited particle-to-particle orientation
allowed in my current limitation. Therefore, a future version will
have a higher resolution square lattice where the particles have a
diameter of two lattice constants. A key consequence is the allowance
of dislocations.
- I am in the process of incorporating my C code into _Python_, an object oriented, user extendable (at the interpreter level), dynamic language. The end product should be something like Basic with specialized data structures and methods for simulating the dynamics of granular materials using a CA-like approach.

Chak Tan