Simulation of dimensionality effects in thermal transport

The discovery of nanostructures and the development of growth and fabrication techniques of one- and two-dimensional materials provide the possibility to probe experimentally heat transport in low-dimensional systems. Nevertheless measuring the thermal conductivity of these systems is extremely challenging and subject to large uncertainties, thus hindering the chance for a direct comparison between experiments and statistical physics models. Atomistic simulations of realistic nanostructures provide the ideal bridge between abstract models and experiments. After briefly introducing the state of the art of heat transport measurement in nanostructures, and numerical techniques to simulate realistic systems at atomistic level, we review the contribution of lattice dynamics and molecular dynamics simulation to understanding nanoscale thermal transport in systems with reduced dimensionality. We focus on the effect of dimensionality in determining the phononic properties of carbon and semiconducting nanostructures, specifically considering the cases of carbon nanotubes, graphene and of silicon nanowires and ultra-thin membranes, underlying analogies and differences with abstract lattice models.Comment: 30 pages, 21 figures. Review paper, to appear in the Springer Lecture Notes in Physics volume "Thermal transport in low dimensions: from statistical physics to nanoscale heat transfer" (S. Lepri ed.

Viewpoint Co-evolution through Coarse-Grained Changes and Coupled Transformations

Abstract. Multi-viewpoint modeling is an effective technique to deal with the ever-growing complexity of large-scale systems. The evolution of multi-viewpoint system specifications is currently accomplished in terms of fine-grained atomic changes. Apart from being a very low-level and cumbersome strategy, it is also quite unnatural to system modelers, who think of model evolution in terms of coarse-grained high-level changes. In order to bridge this gap, we propose an approach to formally express and manipulate viewpoint changes in a high-level fashion, by structuring atomic changes into coarse-grained composite ones. These can also be used to formally define reconciling operations to adapt dependent views, using coupled transformations. We introduce a modeling language based on graph transformations and Maude for expressing both, the coarse-grained changes and the coupled transformations that propagate them to reestablish global consistency. We demonstrate the applicability of the approach by its application in the context of RM-ODP.

Recent trends in border economics

Greater cross-border integration is reflected in U.S.-Mexico border-related economic research. Some of the areas in which substantial work is being done include population, business cycle transmission, exchange rates, industrial development, labor markets, and natural resources. This paper examines research undertaken in these fields. © 2003 Elsevier Inc. All rights reserved

Simulation of Dimensionality Effects in Thermal Transport

The discovery of nanostructures and the development of growth and fabrication techniques of one- and two-dimensional materials provide the possibility to probe experimentally heat transport in low-dimensional systems. Nevertheless measuring the thermal conductivity of these systems is extremely challenging and subject to large uncertainties, thus hindering the chance for a direct comparison between experiments and statistical physics models. Atomistic simulations of realistic nanostructures provide the ideal bridge between abstract models and experiments. After briefly introducing the state of the art of heat transport measurement in nanostructures, and numerical techniques to simulate realistic systems at atomistic level, we review the contribution of lattice dynamics and molecular dynamics simulation to understanding nanoscale thermal transport in systems with reduced dimensionality. We focus on the effect of dimensionality in determining the phononic properties of carbon and semiconducting nanostructures, specifically considering the cases of carbon nanotubes, graphene and of silicon nanowires and ultra-thin membranes, underlying analogies and differences with abstract lattice models