Current Research on Fiber Processes

Many materials from "cornboard" to living plants have structures that can be described a fiber networks. Stochastic processes such as L-systems can generate representative plants from idealized fibers by means of algorithms. The inverse process, measuring the plant fiber structure and converting it to an algorithm, is an exciting intellectual challenge. Matching the fiber structure of living plants to their norms may help diagnose plant disease. Understanding structure-property relationships for plants may help with such tasks as making plants more efficient at scrubbing excess carbon dioxide out of the air. After all, plants are the most energy efficient systems for removing excess carbon dioxide.

While microscopy and conventional stereology are well-developed tools for analyzing the fiber structures of dead plants, they are destructuve and therefore inapplicable to living ones. Microwaves and millimeter waves have polarized interactions with plant fibers that allow determination of the rose of fiber directions among other geometric properties. Unlike light optical methods, these longer wavelength radiations can penetrate to deeper layers without disturbing the surface. However both the theoretical and experimental apparatus for quantitative evaluation of size, spacing and orientation distributions are undeveloped.

While the general theory for the scattering of electromagnetic radiation by fibers has been fully realized through the extension of the Mie theory for dielectric spheres, these results are too cumbersome to incorporate into a framework of stochastic geometry sufficiently detailed to permit calculation of the distribution properties just mentioned. The Rayleigh-Gans theory of thin fibers is sufficiently simple, but yields wrong results because plant fibers usually contain water and therefore do not meet the Rayleigh-Gans criteria requiring negligible phase shift. Common sense reminds us that you can only see the scratches on the car when the light points perpendicular to them. Since this is an analogous scattering problem, the desired simplification of the extended Mie theory must exist given the right conditions and assumptions.

The expermiental work at this time proceeds along two lines. One is to find a test geometry that is practical. The other is to develop better primitives to build the a test geometry from. This includes receivers, signal processors, microwave plumbing, absorbing materials and optical components.