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

Continuum theory for dense gas-solid flow: A state-of-the-art review

In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges.

/pdf/status-and-prospects-of-zno-based-resistive-switching-memory-6hnx73qokk.pdf

Status and Prospects of ZnO-Based Resistive Switching Memory Devices

An improved PSO algorithm for smooth path planning of mobile robots using continuous high-degree Bezier curve

Layout optimization of large-scale oil–gas gathering system based on combined optimization strategy

Investigation on gelation nucleation kinetics of waxy crude oil emulsions by their thermal behavior

Multi-objective optimization of energy consumption in crude oil pipeline transportation system operation based on exergy loss analysis

Thermal decomposition mechanism of some hydrocarbons by ReaxFF-based molecular dynamics and density functional theory study

The waxy crudes gelling and the wax depositing on the inner walls of crude oil pipelines present a costly problem in low-temperature transportation processes. This study focuses on a physical understanding of the gelling deposition during flow of two-phase oil–water in the pipelines. A method for evaluating the gelation characteristic of two-phase oil–water is established, and the effect of emulsified water on gelation is discussed. As the physical properties description, the two-phase diffusion coefficient is found to be a strong function of the water cut. The potential models developed from single-phase flow wax deposition models are proposed spontaneously, and the deposition behavior of two-phase flow in pipelines is predicted under a range of flow conditions in low-temperature transportation. The predictions show that the gelling deposition rate of two-phase oil–water flow is closely related to the pipe flow temperature, external temperature, water cut, and flow rate. The mechanisms of kinetic resista...

Yang Liu

Papers

Investigation on gelation nucleation kinetics of waxy crude oil emulsions by their thermal behavior

Multi-objective optimization of energy consumption in crude oil pipeline transportation system operation based on exergy loss analysis

Thermal decomposition mechanism of some hydrocarbons by ReaxFF-based molecular dynamics and density functional theory study

Study on Two-Phase Oil–Water Gelling Deposition Behavior in Low-Temperature Transportation

Numerical simulation of flow behavior of particles in a liquid-solid stirred vessel with baffles