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

Recent developments of zinc oxide based photocatalyst in water treatment technology: A review

Responding to the latest developments in rock physics research, this popular reference book has been thoroughly updated while retaining its comprehensive coverage of the fundamental theory, concepts, and laboratory results. It brings together the vast literature from the field to address the relationships between geophysical observations and the underlying physical properties of Earth materials - including water, hydrocarbons, gases, minerals, rocks, ice, magma and methane hydrates. This third edition includes expanded coverage of topics such as effective medium models, viscoelasticity, attenuation, anisotropy, electrical-elastic cross relations, and highlights applications in unconventional reservoirs. Appendices have been enhanced with new materials and properties, while worked examples (supplemented by online datasets and MATLAB® codes) enable readers to implement the workflows and models in practice. This significantly revised edition will continue to be the go-to reference for students and researchers interested in rock physics, near-surface geophysics, seismology, and professionals in the oil and gas industries.

The Rock Physics Handbook

A power semiconductor device includes trenches disposed in a first base layer of a first conductivity type at intervals to partition main and dummy cells, at a position remote from a collector layer of a second conductivity type. In the main cell, a second base layer of the second conductivity type, and an emitter layer of the first conductivity type are disposed. In the dummy cell, a buffer layer of the second conductivity type is disposed. A gate electrode is disposed, through a gate insulating film, in a trench adjacent to the main cell. A buffer resistor having an infinitely large resistance value is inserted between the buffer layer and emitter electrode. The dummy cell is provided with an inhibiting structure to reduce carriers of the second conductivity type to flow to and accumulate in the buffer layer from the collector layer.

Power semiconductor device

Reliability challenges in 3D IC packaging technology

Experimental studies of board-level reliability of chip-scale packages subjected to JEDEC drop test condition

We have used composite flip chip solder joints to study thermomigration. The composite solder joint has 97Pb3Sn on the Si side and eutectic 37Pb63Sn on the substrate side. Redistribution of Sn and Pb occurs in thermomigration, and we found that Sn has moved to the Si side (the hot end) and Pb to the substrate side (the cold end). We estimate the driving force that a temperature gradient of 1000°C∕cm or a temperature difference of 10°C across a solder joint of 100μm in diameter is sufficient to induce the thermomigration.

Thermomigration in SnPb composite flip chip solder joints

We report in this paper Young's moduli and hardness of Cu 6 Sn 5 , Cu 3 Sn, and Ni 3 Sn 4 intermetallic compounds (IMCs) measured by nanoindentation. The samples were prepared by annealing Sn–Cu and Sn–Ni diffusion couples. Indentations performed along the directions lateral and perpendicular to the IMC layers show statistically indistinguishable Young's moduli and hardness for each of the three IMCs, implying that these polycrystalline IMC aggregates are rather isotropic. Nanomechanical responses of the IMCs were shown to depend greatly on the strain rate during loading while independent of the strain rate during unloading. Multiple pop-in events were observed for Cu 6 Sn 5 during loading at a strain rate lower than about 0.1–0.5 s −1 . Topographies of the residual impressions were quantitatively measured and the pile-up features were apparent for the three IMCs.

Yi-Shao Lai

Papers

Experimental studies of board-level reliability of chip-scale packages subjected to JEDEC drop test condition

Thermomigration in SnPb composite flip chip solder joints

Nanoindentation identifications of mechanical properties of Cu6Sn5, Cu3Sn, and Ni3Sn4 intermetallic compounds derived by diffusion couples

Support excitation scheme for transient analysis of JEDEC board-level drop test

Advanced Flip Chip Packaging