Accelerating molecular dynamic simulation on the cell processor and Playstation 3

Implementation of molecular dynamics (MD) calculations on novel architectures will vastly increase its power to calculate the physical properties of complex systems. Herein, we detail algorithmic advances developed to accelerate MD simulations on the Cell processor, a commodity processor found in PlayStation 3 (PS3). In particular, we discuss issues regarding memory access versus computation and the types of calculations which are best suited for streaming processors such as the Cell, focusing on implicit solvation models. We conclude with a comparison of improved performance on the PS3's Cell processor over more traditional processors.     

秩为3的Jacobian的性质和它在热力学中的应用

描述了秩为3的Jacobian的性质,探讨了应用Mathematica软件及秩为3的Jacobian来研究单组分、单相系统热力学一阶偏微商和二阶偏微商的方法.     

Coxeter polytopes with a unique pair of non-intersecting facets

We consider compact hyperbolic Coxeter polytopes whose Coxeter diagram contains a unique dotted edge. We prove that such a polytope in d-dimensional hyperbolic space has at most d+3 facets. In view of results by Kaplinskaja [I.M. Kaplinskaya, Discrete groups generated by reflections in the faces of simplicial prisms in Lobachevskian spaces, Math. Notes 15 (1974) 88-91] and the second author [P. Tumarkin, Compact hyperbolic Coxeter n-polytopes with n+3 facets, Electron. J. Combin. 14 (2007), R69, 36 pp.], this implies that compact hyperbolic Coxeter polytopes with a unique pair of non-intersecting facets are completely classified. They do exist only up to dimension 6 and in dimension 8.     

Structural analysis of a fractional matching problem

Mixed Software Programming refers to a novel software development paradigm resulting from efforts to combine two different programming approaches: Solo Programming and Pair Programming. Solo Programming refers to the traditional practice of assigning a single developer to develop a software module and Pair Programming refers to a relatively new approach where two developers work simultaneously on developing a module. In Mixed Programming, given a set of modules to be developed, a chosen subset of modules may be developed using Solo Programming and the remaining modules using Pair Programming.Motivated by applications in Mixed Software Programming, we consider the following generalization of classical fractional 1-matching problem: Given an undirected simple graph G=(V;E), and a positive number F, find values for x_e,e∈E, satisfying the following:

1.

.

2.

, where δ(i)={e∈E:e=(i,j)},i∈V.

3.

Maximize {2∑_e∈Ex_e−F|{i∈V:∑_e∈δ(i)x_e=1}|}.

We show that this problem is solvable in strongly polynomial time. Our primary focus in this paper is on obtaining the structure of the optimal solution for an arbitrary instance of the problem.     

Determining maximal efficient faces in multiobjective linear programming problem

Finding an efficient or weakly efficient solution in a multiobjective linear programming (MOLP) problem is not a difficult task. The difficulty lies in finding all these solutions and representing their structures. Since there are many convenient approaches that obtain all of the (weakly) efficient extreme points and (weakly) efficient extreme rays in an MOLP, this paper develops an algorithm which effectively finds all of the (weakly) efficient maximal faces in an MOLP using all of the (weakly) efficient extreme points and extreme rays. The proposed algorithm avoids the degeneration problem, which is the major problem of the most of previous algorithms and gives an explicit structure for maximal efficient (weak efficient) faces. Consequently, it gives a convenient representation of efficient (weak efficient) set using maximal efficient (weak efficient) faces. The proposed algorithm is based on two facts. Firstly, the efficiency and weak efficiency property of a face is determined using a relative interior point of it. Secondly, the relative interior point is achieved using some affine independent points. Indeed, the affine independent property enable us to obtain an efficient relative interior point rapidly.     

On exposed faces and smoothness

In this paper we study two types of Banach spaces: those whose unit ball exposed faces are pairwise disjoint and those that are smooth. We present original characterizations of both types that easily lead to local and global results on smoothness.      

Gaussian软件在红外光谱学教学中的应用

探讨了Gaussian软件在红外光谱学教学中的具体应用,帮助学生在课堂上对分子的三维空间结构、振动光谱的理解、振动模式的指认与归属等方面有更加感性的认识,从而提高课堂趣味性,使得教学内容更为形象生动。     

Modernization and optimization of a legacy open-source CFD code for high-performance computing architectures

Legacy codes remain a crucial element of today's simulation-based engineering ecosystem due to the extensive validation process and investment in such software. The rapid evolution of high-performance computing architectures necessitates the modernization of these codes. One approach to modernization is a complete overhaul of the code. However, this could require extensive investments, such as rewriting in modern languages, new data constructs, etc., which will necessitate systematic verification and validation to re-establish the credibility of the computational models. The current study advocates using a more incremental approach and is a culmination of several modernization efforts of the legacy code MFIX, which is an open-source computational fluid dynamics code that has evolved over several decades, widely used in multiphase flows and still being developed by the National Energy Technology Laboratory. Two different modernization approaches,‘bottom-up’ and ‘top-down’, are illustrated. Preliminary results show up to 8.5x improvement at the selected kernel level with the first approach, and up to 50% improvement in total simulated time with the latter were achieved for the demonstration cases and target HPC systems employed.     

基于ANSYS Workbench热板电加热与油加热模拟及对比分析

为改善平板硫化机热板表面温度场分布的均匀性, 对规格为75mm×2400mm×2400mm的平板硫化机热板进行了有限元模拟. 利用ANSYS Workbench软件分别模拟热板电加热与导热油加热情况, 并进行对比分析. 结果表明, 针对同一块热板在加热到190℃工作温度左右时, 电加热热板表面温差为12.012℃, 导热油加热热板表面温差为9.2℃. 模拟分析结果表明, 采用导热油加热热板表面温度均匀性更高、升温速率更快; 且入口流速在4m?s-1时, 温度场均匀性得到明显改善.     

基于TD-LTE短信平台的智能排队叫号系统设计

随着经济和社会的快速发展,服务行业的种类和业务量急剧增长,排队等候成为人们经常面临的问题。为了解决排队等候的秩序问题,智能排队叫号系统应运而生。本文设计了一种基于TD-LTE短信平台的智能排队叫号系统,该系统可以通过APP预约软件进行排号,也可以通过服务大厅的固定取号端进行排队取号,方便了人们办理各种业务,节省了排队时间。该系统采用了软硬件协同的方法进行设计,各模块之间使用无线方式进行连接,简化了布线的复杂性。该系统具有安装快捷,使用维护方便,成本低廉,便于扩展等特点。