Parallelization and performance tuning of molecular dynamics code with OpenMP

An OpenMP approach was proposed to parallelize the sequential molecular dynamics（MD） code on shared memory machines. When a code is converted from the sequential form to the parallel form, data dependence is a main problem. A traditional sequential molecular dynamics code is anatomized to find the data dependence segments in it, and the two different methods, i. e. , recover method and backward mapping method were used to eliminate those data dependencies in order to realize the parallelization of this sequential MD code. The performance of the parallelized MD code was analyzed by using some performance analysis tools. The results of the test show that the computing size of this code increases sharply form 1 million atoms before parallelization to 20 million atoms after parallelization, and the wall clock during computing is reduced largely. Some hot-spots in this code are found and optimized by improved algorithm. The efficiency of parallel computing is 30% higher than that of before, and the calculation time is saved and larger scale calculation problems are solved.     

Single Ended Fault Location Estimation for EHV Transmission Systems

A novel numerical algorithm for fault location estimation of single-phase-to-earth fault on EHV transmission lines is presented in this paper. The method is based on one-terminal voltage and current data and is used in a procedure that provides the automatic determination of faulted types and phases, rather than requires engineer to specify them. The loop and nodal equations comparing the faulted phase to non-faulted phases of multi-parallel lines are introduced in the fault location estimation models, in which source impedance of remote end is not involved. Precise algorithms of locating fault are derived. The effect of load flow and fault resistance,on the location accuracy, are effectively eliminated. The algorithms are demonstrated by digital computer simulations.     

Clustering based segmentation of text in complex color images

We propose a novel scheme based on clustering analysis in color space to solve text segmentation in complex color images. Text segmentation includes automatic clustering of color space and foreground image generation. Two methods are also proposed for automatic clustering: The first one is to determine the optimal number of clusters and the second one is the fuzzy competitively clustering method based on competitively learning techniques. Essential foreground images obtained from any of the color clusters are combined into foreground images. Further performance analysis reveals the advantages of the proposed methods.     

A frequency and amplitude dependent model of rail pads for the dynamic analysis of train-track interaction

A frequency and amplitude dependent model is used to describe the complex behavior of rail pads.It is implemented into the dynamic analysis of three dimensional coupled vehicle-slab track(3D-CVST)systems.The vehicle is treated as a 35-degreeof-freedom multi-body system,and the slab track is represented by two continuous Bernoulli-Euler beams supported by a series of elastic rectangle plates on a viscoelastic foundation.The rail pad model takes into account the influences of the excitation frequency and of the displacement amplitude through a fractional derivative element,and a nonlinear friction element,respectively.The Grünwald representation of the fractional derivatives is employed to numerically solve the fractional and nonlinear equations of motion of the 3D-CVST system by means of an explicit integration algorithm.A dynamic analysis of the3D-CVST system exposed to excitations of rail harmonic irregularities is primarily carried out,which reveals the dependence of stiffness and damping on excitation frequency and displacement amplitude.Subsequently,sensitive analyses of the model parameters are investigated by conducting the dynamic analysis of the 3D-CVST system subjected to excitations of welded rail joint irregularities.Following this,parameters of the rail pad model are optimized with respect to experimental values.For elucidation,the 3D-CVST dynamic model incorporated with the rail pads model is used to calculate the wheel/rail forces induced by excitations of measured random track irregularities.Further,the numerical results are compared with experimental data,demonstrating the reliability of the proposed model.     

Application of Bayesian Dynamic Forecast in Anomaly Detection

A macroscopical anomaly detection method based on intrusion statistic and Bayesian dynamic forecast is presented. A large number of alert data that cannot be dealt with in time are always aggregated in control centers of large-scale intrusion detection systems. In order to improve the efficiency and veracity of intrusion analysis, the intrusion intensity values are picked from alert data and Bayesian dynamic forecast method is used to detect anomaly. The experiments show that the new method is effective on detecting macroscopical anomaly in largescale intrusion detection systems.     

Monitoring actual performance of ground source heat pump system using GPRS-based data transmission: A case analysis in Tangshan

The energy efficiency monitoring is an essential precondition for ground source heat pump system’s controlling and energy saving operation. Based on the data monitoring applied in the school building, this work is focused on the parameters acquisition and operation analysis of the GSHP system in Tangshan. Results show the average COPs(coefficient of performance) are2.85 and 2.70 in summer and winter, respectively, and heat(cold) unbalance underground existed after whole year operation. The analysis of data also indicates that the direct borehole air-conditioning saved some power consumption obviously in the early stage of summer and energy saving of the GSHP system depended remarkably on its operation and management level. Besides the observation points of ground temperature are laid for a large-scale GSHP system, and the hydraulic balance of the pipes group needs to be concerned specially in safeguarding better reliability.     

Random Time Dependent Resistance Analysis on Reinforced Concrete Structures

The analysis method on radom time depedence of reinforced concrete mateial is introduced,the effect mechanism on reinforecd concrete are discussed,and the radom time dependence resistance of reinforced concrete is studied ,Furthermore,the corrosion of steel bar in reinforced concete structures is analyzed,A practical statistical methol of evaluating the random time dependent resistance,which includes material ,structural size and calculation infuence,is also esabisled,In addiniton,and example of rediction radom time depentent rsistamce of reinforced concrete strucral element is giver.     

A version management model of PDM system and its realization

Based on the key function of version management in PDM system,this paper discusses the function and the realization of version management and the transitions of version states with a workflow.A directed acyclic graph is used to describe a version model.Three storage modes of the directed acyclic graph version model in the database,the bumping block and the PDM working memory are presented and the conversion principle of these three modes is given.The study indicates that building a dynamic product structure configuration model based on versions is the key to resolve the problem.Thus a version model of single product object is built.Then the version management model in product structure configuration is built and the application of version management of PDM system is presented as a case.     

Holographic Deformation Measurement by a Spatial Carrier Fringe Technique

A carrier fringe techrtique for measuring surface deformation is described and verified by experiments. In contrast to conventional holography and fringe analysis, this holographic system is based on fibre optics and automatic spatial carrier fringe pattem analysis techniques Single-mode optic fibres are used to transfer both the object and reference beams. Carrier fringes are generated by simply translating the object beam between two exposures The Fourier transform is applied to the carrier fringe pattern to convert it to the spatial frequency domain, where it is processed The results are given for a centrally loaded disk, including a 3-D perspective plot of the out of plane deformation field, phase map, grey level map and contour map.     

Research on traffic flow forecasting model based on cusp catastrophe theory

This paper intends to describe the relationship between traffic parameters by using cusp catastrophe theory and to deduce highway capacity and corresponding speed forecasting value through suitable transformation of catastrophe model. The five properties of a catastrophe system are outlined briefly, and then the data collected on freeways of Zhujiang River Delta, Guangdong province, China are examined to ascertain whether they exhibit qualitative properties and attributes of the catastrophe model. The forecasting value of speed and capacity for freeway segments are given based on the catastrophe model. Furthermore, speed-flow curve on freeway is drawn by plotting out congested and uncongestcd traffic flow and the capacity value for the same freeway segment is also obtained from speed-flow curve to test the feasibility of the application of cusp catastrophe theory in traffic flow analysis, The calculating results of catastrophe model coincide with those of traditional traffic flow models regressed from field observed data, which indicates that the deficiency of traditional analysis of relationship between speed, flow and occupancy in two-dimension can be compensated by analysis of the relationship among speed, flow and occupancy based on catastrophe model in three-dimension, Finally, the prospects and problems of its application in traffic flow research in China are discussed.     

面向分布式系统的串行程序的并行分解与运行

本文的内容是软件系统“面向分布式系统的串行程序的并行分解与运行”的一部分,该系统分两篇文章介绍。本篇以Kuck的数据相关理论为基础,结合分布式系统的特点,介绍系统中采用的新的数据相关分析方法以及并行成分的识别方法-程序分割法,并给出算法。     

PLD逆向分析中并行数据采集技术研究

现有的数据采集算法很难适用于较大规模的加密PLD解析。文章研究数据采集中状态加全的并行性和CPU与采集平台之间的并行性,提出了一种并行数据采集模型,通过将状态加全和搜索状态转移路径分散到多个采集设备上执行,充分利用设备资源,解决了构建状态转移图时内存不足的问题,有效降低了数据采集时间。     

基于推理多线程技术的一种改进模型

为了解决多线程处理器不同线程之间并行性低、相互之间数据依赖性高的问题，在推理多线程技术基础上提出了一种新的多线程技术模型(分级多线程Hierarchical Multithreading HMT).该模型采用两种等级处理元的方法，低等级使用指令级并行和细粒度线程级并行；高等级更多地使用间隔并行机制.通过详细的模拟研究，证明分级多线程技术通过对线程的不同粒度采用并行机制能够切实可行地提高线程之间的并行性.     

DPHL程序赋值语句中并行性的开发

DPHL语言是一种数据并行高层建模语言,用于在算法层次上描述应用问题求解步骤。在DPHL程序中,作用在域上的赋值语句以及复杂赋值语句中蕴含着并行性,本文讨论这两种并行性的开发。     

英汉"排偶"的对比及使用

本文就英语和汉语修辞格中的排偶结构进行了分析对比。笔者认为对于修词的学习研 究,有助于对原文的理解,有助于对英语文化的了解和对英语知识的巩固。     

可重构媒体处理器任务编译器的前端设计

为了解决算法程序自动映射到可重构媒体处理器的问题,有效提高程序并行执行的效率,提出一种具有自动并行化的任务编译前端. 该任务编译前端通过展开核心循环可提高并行执行度,在数据依赖分析确保运算正确执行的基础上,对循环体内的数组访问进行标量替换,以优化数据传输开销. 实验结果表明,该任务编译前端能有效提高代码并行性和优化数据传输能力,与Garp C编译器的编译前端相比,该任务编译前端设计的性能可提升约2~4倍.     

基于高性能云的分布式数据并行处理机制

描述了一个基于高性能云的分布式数据并行处理机制,该机制简化了数据并行处理操作,且能实现数据尽可能在同一个地点处理而无需移动;重点对相关的存储云和计算云基本的框架结构设计思想进行了简要的介绍;实验结果表明,该数据并行处理机制能用于高性能广域网络连接的计算机集群所产生的大型分布式数据集的数据并行处理,实验数据显示,其性能较其它系统（如Hadoop）有显著的提高。     

高效的宽带数字信道化接收机设计

短时傅里叶变换(STFT)算法是实现数字信道化接收的一种简单而有效的方法,但其运算速度受到数字信号处理(DSP)器件性能的限制．为此,提出了一种STFT的高速实现方法．采用扩展资源多路并行流水的结构,实现了数据的低速率传输和硬件的高效利用,同时实现了对信号的实时检测和参数估计,适合高速实时处理应用．     

用数学形态学方法处理地图中间断线型符号

以数学形态学变换为基础,针对地图提出了一种新的地图跟踪方法．该方法通过原始图像与形态学结构元素相运算,并行给出了构成线型地物的各点或线的位置信息．实验表明,该方法对于间断线型符号的跟踪是很有效的     

基于 Improved-Hash方法的多维数据划分

针对并行数据库系统的数据分布不合理而引起的操作并行化程度不高的问题,依据均匀的数据划分有利于提高查询效率的思想,提出了以Improved-Hash方法为基础的多维数据划分。此方法在优化并行数据库系统的查询操作,提高系统资源利用率方面有一定的指导作用。