Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Emerging challenges and materials for thermal management of electronics

A recent increase in the use of ecofriendly, natural fibers as reinforcement for the fabrication of lightweight, low cost polymer composites can be seen globally. One such material of interest currently being extensively used is basalt fiber, which is cost-effective and offers exceptional properties over glass fibers. The prominent advantages of these composites include high specific mechano-physico-chemical properties, biodegradability, and non-abrasive qualities to name a few. This article presents a short review on basalt fibers used as a reinforcement material for composites and discusses them as an alternative to the use of glass fibers. The paper also discusses the basics of basalt chemistry and its classification. Apart from this, an attempt to showcase the increasing trend in research publications and activity in the area of basalt fibers is also covered. Further sections discuss the improvement in mechanical, thermal and chemical resistant properties achieved for applications in specific industries.

A short review on basalt fiber reinforced polymer composites

Shape-stabilized phase change materials based on porous supports for thermal energy storage applications

https://nottingham-repository.worktribe.com/preview/938493/Literature%20review%20PCM-first%20revision%20Jack%20Edited%20%281%29.pdf

A review of the applications of phase change materials in cooling, heating and power generation in different temperature ranges

The effect of pore size and porosity on thermal management performance of phase change material infiltrated microcellular metal foams

Many theoretical and empirical models exist to predict the effective thermal conductivity of polymer foams. However, most of the models only consider the effect of porosity, while the pore size effect is ignored. The objective of this study is to understand the effect of pore size on the thermal conductivity of polymer foams, especially when it reduces to the micro and nanometer scales. A wide range of pore sizes from 1 nm to 1 mm were studied in conjunction with the porosity effect using finite element analysis and molecular dynamics simulation methods. Experimental data was used to validate the modeling result. It is shown that the pore size has significant effect on thermal conductivity, even for microcellular and conventional foams. The contribution of heat conduction through air is negligible when pore size is reduced to the micrometer scale. The extremely low thermal conductivity of nanofoams is attributed to extensive diffusive scattering of heat carriers in the solid phase of polymer matrix, instead of air. This study provides quantitative understanding of the pore size effect on thermal conductivity of polymer foams. It is also shown that polyetherimide (PEI) nanofoams could have a thermal conductivity as low as 0.015 W/m-K. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers

On thermal conductivity of micro- and nanocellular polymer foams

Polymer nanofoams have recently attracted significant interest in both industry and academia. The unique nanoscaled porous structure could bring unprecedented material properties that have not been seen in conventional or microcellular polymer foams. It has been hypothesized that nanofoams could have a much higher specific strength and toughness as well as significantly improved thermal resistivity. In this research, we study the fabrication and characterization of polyetherimide nanofoams using a supercritical carbon dioxide foaming process. A process map indicating the conditions to obtain various polyetherimide foam structures, including micro-, micro/nano transition, and nanofoams has been established. Two types of nanofoams were observed, one made with high gas concentrations and the other with high foaming temperatures. The one with high gas concentrations exhibited a higher specific modulus than that of unfoamed polyetherimide. Nanofoams generally showed a higher thermal resistivity than microfoams...

Fabrication and characterization of polyetherimide nanofoams using supercritical CO2

A foamed polymer nanocomposite system is developed as an ablative for thermal protection applications. Polymer nanocomposite foams exhibit better thermal properties with the inherent benefit of being lightweight. In this study, Polyetherimide (PEI) was compounded with nanoclay to enhance the flame retardant property. A thermoplastic elastomer, Kraton, was added to improve the mechanical strain. Samples with various compositions of nanoclay and Kraton were foamed using a batch solid-state foaming process. The thermal protection performance of the material system was characterized with an oxy-acetylene flame ablation test. It is shown that foaming helped reduce the mass loss of the samples during the ablation test. The loadings of nanoclay and Kraton and the foam density can be used to optimize the thermal protection performance. The foams obtained in this study had a graded structure with an overall porosity of 20–60%.

Sriharsha S. Sundarram

Papers

The effect of pore size and porosity on thermal management performance of phase change material infiltrated microcellular metal foams

On thermal conductivity of micro- and nanocellular polymer foams

Fabrication and characterization of polyetherimide nanofoams using supercritical CO2

Polyetherimide nanocomposite foams as an ablative for thermal protection applications

Fabrication of Small Pore-Size Nickel Foams Using Electroless Plating of Solid-State Foamed Immiscible Polymer Blends