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

One-dimensional carbon nanotubes and two-dimensional graphene nanosheets with unique electrical, mechanical and thermal properties are attractive reinforcements for fabricating light weight, high strength and high performance metal-matrix composites. Rapid advances of nanotechnology in recent years enable the development of advanced metal matrix nanocomposites for structural engineering and functional device applications. This review focuses on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets. These include processing strategies of carbonaceous nanomaterials and their composites, mechanical and tribological responses, corrosion, electrical and thermal properties as well as hydrogen storage and electrocatalytic behaviors. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure–property relationships of such novel nanocomposites.

Recent progress in the development and properties of novel metal matrix nanocomposites reinforced with carbon nanotubes and graphene nanosheets

Introduction to Electromagnetic Compatibility

The residual defects and groups in chemically reduced graphene oxide cannot only improve the impedance match characteristic and prompt energy transition from contiguous states to Fermi level, but also introduce defect polarization relaxation and groups’ electronic dipole relaxation, which are all in favor of electromagnetic wave penetration and absorption The chemically reduced graphene oxide shows enhanced microwave absorption compared with graphite and carbon nanotubes, and can be expected to display better absorption than high quality graphene, exhibiting a promising prospect as microwave absorbing material

The electromagnetic property of chemically reduced graphene oxide and its application as microwave absorbing material

Catalysis is at the core of almost every established and emerging chemical process and also plays a central role in the quest for novel technologies for the sustainable production and conversion of energy. Particularly since the early 2000s, a great surge of interest exists in the design and application of micro- and nanometer-sized materials with hollow interiors as solid catalysts. This review provides an updated and critical survey of the ever-expanding material architectures and applications of hollow structures in all branches of catalysis, including bio-, electro-, and photocatalysis. First, the main synthesis strategies toward hollow materials are succinctly summarized, with emphasis on the (regioselective) incorporation of various types of catalytic functionalities within their different subunits. The principles underlying the scientific and technological interest in hollow materials as solid catalysts, or catalyst carriers, are then comprehensively reviewed. Aspects covered include the stabilizat...

Hollow Nano- and Microstructures as Catalysts

The effect of deposition parameters on the morphology of micron diamond powders synthesized by HFCVD method

An amorphous SiC (a-SiC) thin film is deposited on the WC–Co insert from dimethyldiethoxysilane/hydrogen gas mixture using hot filament chemical vapour deposition (HFCVD) technique. Energy dispersive X-ray spectroscopy, scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and transmission electron microscope are used to characterise the as fabricated a-SiC thin film. Subsequently, the a-SiC film is used as an intermediate film, and an adherent top layer of CVD diamond with well faceted crystallites is synthesised on the a-SiC interlayer. Rockwell indentation tests indicate that the CVD diamond film with a-SiC interlayer results in less delamination in comparison with that directly deposited on WC–Co substrate. The multilayer (a-SiC+diamond) film coated insert exhibits better cutting performance and longer lifetime than the CVD diamond coated insert with no interlayer in dry turning of Al–Si alloy. By introducing the a-SiC interlayer, the adhesion an...

Diamond deposition on WC–Co substrate with amorphous SiC interlayer

Microemulsion template synthesis of copper sulfide hollow spheres at room temperature

The present invention method of hollow or coating type nickel alloy spherical powder includes the following steps: dissolving nickel salt, adding alkali liquor and reducing agent, utilizing alkaline colloidal kernel generated by self-body reaction as core, using the colloidal kernel surface as active center, self-catalyzing reducing agent and nickel iron reaction to form nickel alloy shell body on colloidal kernel surface, make after-treatment so as to obtain the hollow or coated type nickel alloy spherical powder. Said invention can be used in the fields of high-effective catalyst, adsorbing agent, photoelectric and electromagnetic device, microwave absorption material and bio-pharmaceutical industry, etc.

Bin Shen

Papers

The effect of deposition parameters on the morphology of micron diamond powders synthesized by HFCVD method

Diamond deposition on WC–Co substrate with amorphous SiC interlayer

Microemulsion template synthesis of copper sulfide hollow spheres at room temperature

Method for preparing hollow or clad nickel alloy spherical powder

Influence of Stone-Wales Defect on Graphene Friction: Pinning Effect and Wrinkle Modification