Showing posts with label disorder. Show all posts
Showing posts with label disorder. Show all posts

Sunday, November 11, 2018

Congratulations to Dr. Alejandro Martínez!

My doctoral student Alejandro Martínez has now officially finished his D.Phil. (i.e., Ph.D.), with a dissertation called Disordered Granular Crystals.

His thesis work includes several awesome papers, including this one, this one, this one, this one, and this one. (Alejandro also has additional papers from his thesis era that are in collaboration with other people.)

Alejandro is now a postdoctoral scholar in computational biology in Chile.

Tuesday, February 13, 2018

"Direct Measurement of Superdiffusive Energy Transport in Disordered Granular Chains"

Our paper in which we — after many years of effort — showed strongly nonlinear Anderson phenomena in experiments is finally out in published form!

Here are some details.

Title: Direct Measurement of Superdiffusive Energy Transport in Disordered Granular Chains

Authors: Eunho Kim, Alejandro J. Martínez, Sean E. Phenisee, Panayotis G. Kevrekidis, Mason A. Porter, and Jinkyu Yang

Teaser: Wave propagation is often nonlinear in character, yet the interplay between disorder and nonlinearity remains elusive. Kim et al. use experiments and corroborating numerical simulations to investigate this phenomenon and demonstrate superdiffusive energy transport in disordered granular chains.

Abstract: Energy transport properties in heterogeneous materials have attracted scientific interest for more than half of a century, and they continue to offer fundamental and rich questions. One of the outstanding challenges is to extend Anderson theory for uncorrelated and fully disordered lattices in condensed-matter systems to physical settings in which additional effects compete with disorder. Here we present the first systematic experimental study of energy transport and localization properties in simultaneously disordered and nonlinear granular crystals. In line with prior theoretical studies, we observe in our experiments that disorder and nonlinearity—which individually favor energy localization—can effectively cancel each other out, resulting in the destruction of wave localization. We also show that the combined effect of disorder and nonlinearity can enable manipulation of energy transport speed in granular crystals. Specifically, we experimentally demonstrate superdiffusive transport. Furthermore, our numerical computations suggest that subdiffusive transport should be attainable by controlling the strength of the system’s external precompression force.

Tuesday, May 08, 2012

Order and Disorder in Pastry Displays

Perhaps strange dreams beget strange ideas, and here's my idea for the day.

I was at Green's Cafe today, and I noticed that the ordering of the pastries in their display case differs from day to day. And this makes me ask: Is it better strategically to do this (perhaps so people think there is more variety than there actually is?) or is it better to go with regularity and put everything --- when it's in stock --- in basically the same place every day. Also, it might be interesting to come up with a mathematical model of this. Do any of you have any thoughts on whether order or disorder is better in this situation? (Also, I'm guessing that the model would have a phase transition between a region in which the pastries should be ordered and one in which disorder ought to be favorable.)