应用平行坐标系进行可视化优化设计

应用可视化方法进行化工过程优化设计：应用平行坐标系进行多维矢量可视化,并在此基础上提出了一种在n维空间用于多维矢量线性回归的“扫描线”算法。在优化问题中该算法可以将问题简化到一或二维,从而以二到三维笛卡尔坐标为基础的传统可视化方法可用于优化设计。将这种方法与遗传算法相结合,不仅可以得到较好的优化结果,还可得到一些“额外信息”以使用户理解基于可视化的优化设计过程并接受该结果。     

Survey of parallel approaches to scientific visualization

The paper discusses the use of high performance computers ( and vector) for scientific visualization. Various institutions and companies are investigating how best to utilize supercomputers and massively parallel processors for visualizing scientific data. Approaches which have been taken include the use of visualization servers, the parallelization of existing scientific visualization packages, and custom solutions utilizing various high performance computers. A brief synopsis of some recent approaches is included, and a subjective analysis of the applicability of the various efforts is offered.     

Performance measurement,visualization and modeling of parallel and distributed programs using the AIMS toolkit

Writing large-scale parallel and distributed scientific applications that make optimum use of the multiprocessor is a challenging problem. Typically, computational resources are underused due to performance failures in the application being executed. Performance-tuning tools are essential for exposing these performance failures and for suggesting ways to improve program performance. In this paper, we first address fundamental issues in building useful performance-tuning tools and then describe our experience with the AIMS toolkit for tuning parallel and distributed programs on a variety of platforms. AIMS supports source-code instrumentation, run-time monitoring, graphical execution profiles, performance indices and automated modeling techniques as ways to expose performance problems of programs. Using several examples representing a broad range of scientific applications, we illustrate AIMS' effectiveness in exposing performance problems in parallel and distributed programs.     

基于主成分分析和K-means聚类的平行坐标可视化技术研究

为了解决多维数据的维数过高、数据量过大带来的平行坐标可视化图形线条密集交叠以及数据规律特征不易获取的问题,提出基于主成分分析和K-means聚类的平行坐标（PCAKP,principal component analysis and k-means clustering parallel coordinate）可视化方法。该方法首先对多维数据采用主成分分析方法进行降维处理,其次对降维后的数据采用K-means聚类处理,最后对聚类得到的数据采用平行坐标可视化技术进行可视化展示。以统计局网站发布的数据为测试数据,对PCAKP可视化方法进行测试,与传统平行坐标可视化图形进行对比,验证了PCAKP可视化方法的实用性和有效性。     

Hierarchical bulk synchronous parallel model and performance optimization

Based on the framework of BSP,a Hierarchical Bulk Synchronous Parallel(HBSP)performance model is introduced in this paper to capture the performance optimization problem for various stages in parallel program development and to accurately predict the performance of a parallel program by considering factors causing variance at local computation and global communication.The related methodology has been applied to several real applications and the results show that HBSP is a suitable model for optimizing parallel programs.     

支持多种并行程序设计模式的可移植并行调试器设计与实现

MPDG是为高性能并行巨型机系统设计的调试工具,其设计指导思想是：1．采用Client/Server结构,实现系统的可移植性,具体表现为将用户界面,并行调试管理与调试监控服务分离,调试监控采用目标系统支持的调试器;2．以同一的使用方式支持多种并行程序设计模式应用,针对共享内存的并行目标应用（如OpenMP程序)和基．于水息传递的分布式目标应用（如PVM或MPI程序）,提供风格完全一致的调试手段;3．实现图形用户界面,MPDG的GUI分为3级,即主界面,进程集,单个进程,进程集控制特别适合具有相同执行流和用户视图的并行进程的调试。     

异构平台下的并行程序性能可视化方法

为了便于对异构平台下的并行程序性能进行分析,在对可视化技术和并行计算与控制显示平台研究的基础上设计了一种异构环境下的性能可视化模型.针对该模型的特点利用监测代码插桩技术、性能数据事后分析等方法,给出了并行性能数据获取、转换与绘图的具体方法和实现过程,为跨平台并行性能数据的采集和转换提供了一种简便方法.实验结果表明了在异构环境下该方法对并行性能数据可视化的可行性与有效性.     

A parallel language and its programming system for heterogeneous networks

The paper presents a new parallel language, mpC, designed specially for programming high‐performance computations on heterogeneous networks of computers, as well as its supportive programming environment. The main idea underlying mpC is that an mpC application explicitly defines an abstract network and distributes data, computations and communications over the network. The mpC programming environment uses, at run time, this information as well as information on any real executing network in order to map the application to the real network in such a way that ensures the efficient execution of the application on this real network. Experience of using mpC for solving both regular and irregular real‐life problems on networks of heterogeneous computers is also presented. Copyright © 2000 John Wiley & Sons, Ltd.     

Simulating the DYNIX operating system parallel programming interface on a UNIX system

This paper presents the implementation of multitasking functions of DYNIX Sequent computers on the UNIX operating system. The Sequent computers are shared memory multiprocessor computers running the DYNIX operating system. These functions support data and function partitioning. They let the user implement subprograms by the processors of a Sequent computer in parallel. The functions can synchronize, lock, and unlock data and program segments. As a result, the simulator allows the users to develop their multitasking programs on a uniprocessor computer such as a SUN workstation, and later port them to a Sequent computer. Further, the simulator adds a level of abstraction on top of UNIX for concurrent programming. The functions of the simulator allow the user to handle the communication and synchronization of the processes in a program at a higher level of abstraction, while concentrating on the design of multitasking algorithms. The simulator is applied to a parallel selection algorithm. © 1998 John Wiley & Sons, Ltd.     

Designing parallel systems: a performance prediction problem

PSEE (Parallel System Evaluation Environment) is a software tool that provides a multiprocessor system for research into alternative architectural decisions and experimentation, with such issues as selection, design, tuning, scheduling, clustering and routing policies. PSEE facilitates simulation and performance evaluation as well as a prediction environment for the design and tuning of parallel systems. These tasks involve cycles through programming, simulation, measurement, visualization and modification of parallel system parameters. PSEE includes a parallel programming tool, a simulator for link oriented parallel systems, BOLAS, and a performance evaluation tool, GRAPH. These PSEE modules are tools oriented to support the above tasks in user-friendly, interactive and animated graphical form. PSEE provides quantitative information in a graphical tailored form. This numerical/graphical output helps the user make decisions about his/her particular development.     

Encoding of parallel program schemata by vector addition systems

A new vector addition system is proposed which represents a possible encoding of a parallel schema. This vector addition system contains fewer vectors and vectors of smaller length than the vector addition systems presented in the literature.     

CONSAT: A parallel constraint satisfaction system

In this paper we describe the parallelization of a medium-size symbolic fixed-point computation, CONSAT. CONSAT is a constraint satisfaction system that computes globally consistent solutions. The parallel version of CONSAT is implemented using abstractions from a parallel programming toolbox we developed. The toolbox is intended for novice parallel programmers, and programs based on abstractions from this toolbox may be executed on both uniprocessors and shared-memory multiprocessors without modifications. We explain how parallelism is introduced, and how concurrent accesses to shared data structures are handled. We will also describe the performance of CONSAT on sample inputs.     

Pipelining parallel image compositing and delivery for efficient remote visualization

Scientific datasets of large volumes generated by next-generation computational sciences need to be transferred and processed for remote visualization and distributed collaboration among a geographically dispersed team of scientists. Parallel visualization using high-performance computing facilities is a typical approach to processing such increasingly large datasets. We propose an optimized image compositing scheme with linear pipeline and adaptive transport to support efficient image delivery to a remote client. The proposed scheme arranges an arbitrary number of parallel processors within a cluster in a linear order and divides the image into a carefully selected number of segments, which flow through the linear in-cluster pipeline and wide-area networks to the remote client consecutively. We analytically determine the segment size that minimizes the final image display time and derive the conditions where the proposed image compositing and delivery scheme outperforms the traditional schemes including the binary swap algorithm. In order to match the transport throughput for image delivery over wide-area networks to the pipelining rate for image compositing within the cluster, we design a class of transport protocols using stochastic approximation methods that are able to stabilize the data flow at a target rate. The experimental results from remote visualization of large-scale scientific datasets justify the correctness of our theoretical analysis and illustrate the superior performances of the proposed method.     

A parallel program for an urban-traffic analization and its evaluation

In this paper, we describe the traffic simulation system which analyzes a traffic flow in a road network. The system is constructed and operated on the parallel computer AP1000. A database of a road network is implemented with the object-oriented programming technique. Elements of a road network are regarded as objects, and vehicles which move on the lanes are regarded as attributive data. The database is divided into sub-databases and assigned to each processor. The system calculates the behavior of vehicles in parallel. Sending and receiving data among the objects are carried out with message passing on the communication network. Moreover, we show the results of the vehicles behavior, and evaluate the parallel efficiency.     

基于GOS的远程实时可视化系统设计与实现*

提出了一个并行计算程序的远程实时可视化系统.通过实时可视化处理计算程序在计算过程中输出的数据文件,实现了对计算程序计算过程的可视化跟踪和实时分析;同时该系统采用GOS作为网格中间件,屏蔽了复杂的异构环境.     

基于事件的异构平台并行程序性能可视化研究

为了便于用户快速、直观地了解到机群系统中并行应用程序的性能情况,将Linux计算机群与Windows控制显示平台相结合,提出了一种基于事件的异构平台并行程序性能可视化方法.该方法以MPI作为底层编程环境,在高层使用MPE技术,依据动态性能检测方式获取程序执行过程信息;设计C#语言及Jumpshot日志图形化分析集成工具实现并行程序性能可视化.实验结果表明,该方法可准确,直观地反映程序性能信息,有助于程序员简便、有效地对并行程序进行量化分析,对提高机群系统的可用性、改善程序性能及效率等方面具有较高的实用价值.     

Analyzing the performance of a cluster-based architecture for immersive visualization systems

Cluster computing has become an essential issue for designing immersive visualization systems. This paradigm employs scalable clusters of commodity computers with much lower costs than would be possible with the high-end, shared memory computers that have been traditionally used for virtual reality purposes. This change in the design of virtual reality systems has caused some development environments oriented toward shared memory computing to require modifications to their internal architectures in order to support cluster computing. This is the case of VR Juggler, which is considered one of the most important virtual reality application development frameworks based on open source code.     

All‐uses testing of shared memory parallel programs

Parallelism has become a way of life for many scientific programmers. A significant challenge in bringing the power of parallel machines to these programmers is providing them with a suite of software tools similar to the tools that sequential programmers currently utilize. Unfortunately, writing correct parallel programs remains a challenging task.In particular, automatic or semi‐automatic testing tools for parallel programs are lacking. This paper takes a first step in developing an approach to providing all‐uses coverage for parallel programs. A testing framework and theoretical foundations for structural testing are presented, including test data adequacy criteria and hierarchy, formulation and illustration of all‐uses testing problems, classification of all‐uses test cases for parallel programs, and both theoretical and empirical results with regard to what can be achieved with all‐uses coverage for parallel programs. Copyright © 2003 John Wiley & Sons, Ltd.     

Data parallel volume-rendering algorithms for interactive visualization

The increasing availability of parallel computing platforms has led to the development of parallel volume-rendering algorithms. In the present paper we compare two algorithms for volume raytracing in a data-parallel framework: a shearing technique and a line-drawing technique. The two algorithms are primarily distinguished by the level of parallelism they exploit. Both algorithms have been implemented on the Connection Machine CM2 massively parallel computer and execute at speeds suitable for interactive volume-rendering applications. Since considerable floating-point resources are available on the CM2, we have used rendering algorithms based on transport theory. In the second part of the paper we examine some of the tradeoffs involved between image quality and rendering speed when using high-fidelity rendering algorithms.     

多分辨率并行等值面绘制

文中介绍一个多分辨率并行等值面绘制系统的设计与实现。通过显示调度策略实现基于多层次细节的实时等值面绘制。着重讲述并行处理、网格简化和多分辨率显示技术。实验结果表明，该系统能在并行分布式环境下动态生成等值面的多分辨率模型，实现等值面的远程快速绘制。