电网稳定运行中调度自动化的应用

目前,电力网络管理系统的主要通讯方式是微波和光纤,其中,微波由于自身的性质,容易受到干扰。调度自动化系统的应用,极大地提高了电力输送的效率,降低了事故发生的概率,为电力网络的建设作出了巨大的贡献。     

Quality of Service Networking for High Performance Grid Applications

This paper reports on different efforts to provide quality of service (QoS) Networking to Grid applications done in the context of the MB-NG, GRS and DataTAG EU projects. These are leading edge network research projects involving more that 50 researchers in the UK, Europe and North America, concerned with the development and testing of protocols and standards for the next generation of high speed networks. We have implemented and tested the Differentiated Services Architecture (DiffServ) in a multi-domain, 2.5 Gbits/s network (the first such deployment) defining appropriate Service Level Agreements (SLAs) to be used between administrative domains to guarantee end-to-end Quality of Service. We characterised several hardware implementations of DiffServ and concluded on their appropriateness for several network scenarios. Since current and future Grid applications will have to use modified mechanisms of congestion control we have evaluated old and new TCP implementations over a Differentiated Services Networks. These quality of service tests have also included innovative MPLS (Multi-Protocol Label Switching) experiments to establish guaranteed bandwidth connections to Grid applications in a fast and efficient way. We have also developed a software based bandwidth broker architecture for Grids based on IETF standards which allows applications to transparently request dynamic and advanced reservations and implemented it in a real experimental network. We finally report on experiences delivering Quality of Service networking to high performance applications like Particle Physics data transfer and High Performance Computation. This includes quantitative results on the performance improvements that QoS brought to real data transfers in the context of High Performance Computing.     

Towards Efficient Execution of MPI Applications on the Grid: Porting and Optimization Issues

The message passing interface (MPI) is a standard used by many parallel scientific applications. It offers the advantage of a smoother migration path for porting applications from high performance computing systems to the Grid. In this paper Grid-enabled tools and libraries for developing MPI applications are presented. The first is MARMOT, a tool that checks the adherence of an application to the MPI standard. The second is PACX-MPI, an implementation of the MPI standard optimized for Grid environments. Besides the efficient development of the program, an optimal execution is of paramount importance for most scientific applications. We therefore discuss not only performance on the level of the MPI library, but also several application specific optimizations, e.g., for a sparse, parallel equation solver and an RNA folding code, like latency hiding, prefetching, caching and topology-aware algorithms.     

Improving End System Performance for Multimedia Applications over High Bandwidth Networks

Digital video services, scientific visualization and other multimedia applications require delivery of high network throughput to end user applications. In this paper we identify bottlenecks in the data path between high-speed networks and applications. Using performance of multimedia applications as a metric, the effectiveness of solutions to reduce network, operating system, and user bottlenecks is explored experimentally.     

多线程环境的高效内存分配技术

介绍了一种新的多线程内存分配技术（NIXMalloc）的设计和实现,提出了两种高效的分配策略及其自适应调优方法,有效地提高多线程应用程序的内存管理性能;其中Local分配策略对超级块对象Span进行了线程私有化,基于超级块对象为单位的垃圾回收和内存布局调整使多线程性能更优越;Global分配策略采用了自适应调优方法,在动态检测应用程序内存使用情况的基础上进行内存预取和线程缓存限值的动态调整;实验证明NIXMalloc可改善内存管理性能,提高吞吐量,同时降低内存使用量;在多线程应用系统中能获得较好的时空效率。     

一种稀疏波长转换光网络中的波长分配算法

研究了具有波长转换功能的WDM光网络的分类以及已有的几种波长分配算法,分析了波长分配算法的一般流程。文中以波长变换次数最少做为所提出的波长分配算法的主要优化目标,根据WDM光网络中的节点是否具有波长转换的功能,结合等价光路由替换的思想,提出了在稀疏有限波长转换光网络中的一种启发式的波长分配算法。仿真实验表明,当光网络中的连接请求量较大时,该算法的阻塞率低于已有的一些波长分配算法,连接能力有了较大提高。     

Scheduling Task Parallel Applications for Rapid Turnaround on Enterprise Desktop Grids

Desktop Grids are popular platforms for high throughput applications, but due to their inherent resource volatility it is difficult to exploit them for applications that require rapid turnaround. Efficient desktop Grid execution of short-lived applications is an attractive proposition and we claim that it is achievable via intelligent resource selection. We propose three general techniques for resource selection: resource prioritization, resource exclusion, and task duplication. We use these techniques to instantiate several scheduling heuristics. We evaluate these heuristics through trace-driven simulations of four representative desktop Grid configurations. We find that ranking desktop resources according to their clock rates, without taking into account their availability history, is surprisingly effective in practice. Our main result is that a heuristic that uses the appropriate combination of resource prioritization, resource exclusion, and task replication can achieve performance within a factor of 1.7 of optimal in practice.     

Analysis and Provision of QoS for Distributed Grid Applications

Grid computing provides the infrastructure necessary to access and use distributed resources as part of virtual organizations. When used in this way, Grid computing makes it possible for users to participate in collaborative and distributed applications such as tele-immersion, visualization, and computational simulation. Some of these applications operate in a collaborative mode, requiring data to be stored and delivered in a timely manner. This class of applications must adhere to stringent real-time constraints and Quality-of-Service (QoS) requirements. A QoS management approach is therefore required to orchestrate and guarantee the timely interaction between such applications and services. We discuss the design and a prototype implementation of a QoS system, and demonstrate how we enable Grid applications to become QoS compliant. We validate this approach through a case study of an image processing task derived from a nanoscale structures application.     

网格计算中高性能定时器队列的设计

分析了网格计算给实现高性能定时器队列带来的挑战,分析了主流操作系统的定时器机制方面的缺陷,提出了一种高性能的,跨平台的,多线程安全的,近似O(1)效率的定时器队列实现。该实现采用类似L inux内核tim er_list实现机制的“时间滚轮”技术,可以近似达到增O(1),删O(1),改O(1),触发O(1)的效率。经实践证明能够满足性能需求。     

FFT通信模式嵌入环形光网络及其性能分析

在分析互连网络的性能时常常利用一些特殊的通信模式。而快速傅立叶变换(FFT)在数字信号处理、概率论等领域中具有非常广泛的应用。因此,该文针对FFT的Cormen并行迭代算法中的通信模式,提出两种嵌入算法,将其嵌入环形光网络中。并且分析了在这两种嵌入方式下,FFT算法在环形光网络中的拥挤度和时间复杂度。并对这两种算法进行了比较。最后,得到利用上面的嵌入算法将蝶形网络嵌入环形光网络的嵌入方法并分析了其嵌入拥挤度。     

基于BOTDR的光纤网格隧道形变监测系统研究

在分析布里渊散射光时域反射(BOTDR)监测技术应变测量的基本原理、标定方法、信号处理、实际应用及各项优点的基础上,针对隧道工程的形变监测设计了一套网格结构的光纤传感器系统;该套系统利用BOTDR及相关技术可以完成对隧道形变的灵敏探测和实时监控;对其工作原理和监测优势的分析以及仿真实验结果表明,这套光纤网格隧道形变监测系统具有灵敏度高、抗干扰能力强等优点,在实际工程中具有较高的应用价值。     

高性能MCU的FPGA原型验证系统研究与平台实现

本文研究并实现了一种基于Cortex-A7核的高性能MCU在FPGA原型阶段的验证平台。该设计研究可以针对高性能MCU芯片或其FPGA原型验证阶段的软硬件验证环境快速搭建,通过交互式、软硬件协同的方式对MCU芯片各个模块功能进行实时、可靠的功能验证。高效的FPGA原型验证可以提高MCU研发速度、缩短验证时间、提高验证效率、及时发现芯片设计的缺陷、缩短芯片研发周期。     

基于虚拟网格的无线传感器网络高可靠性路由

为了得到能量高效、具有高可靠性的数据通信链路,在比较几种不同通信方案的链路可靠性的基础上,提出了一种基于虚拟网格单元的高可靠性路由算法(grid-based high reliability routing,简称GHRR).算法为每个网格及其簇头节点分配一个虚拟ID,节点根据该ID自主选择其多个下一跳头节点,使数据的多个拷贝在朝向sink方向上交错传播,从而提高数据传输的可靠性.通过分析及仿真进一步表明,算法提高了路由的可靠性,并具有更小的时间延迟.     

Open Signaling for ATM Networks: A Vexed Question of Performance

Based on a clear separation between switching hardware and control software, the concept of open signaling creates an open programmable networking environment in which network entities can be realized as high level software objects with well-defined interfaces. This underlying architecture facilitates the creation of multiple mechanisms of network control, supporting applications for connection management. The feasibility of a connection management framework however depends mainly on the performance of CORBA because of binding overheads associated with remote invocations. It has been proposed that an implementation with reasonable performance may require certain criteria to be integrated into the design, including caching of network states, aggregation of access to the switch server object, and parallel processing of a single call request. This paper considers the effectiveness of these design criteria and the associated performance issues of a connection management system for ATM networks.     

Metadata for Managing Grid Resources in Data Mining Applications

The Grid is an infrastructure for resource sharing and coordinated use of those resources in dynamic heterogeneous distributed environments. The effective use of a Grid requires the definition of metadata for managing the heterogeneity of involved resources that include computers, data, network facilities, and software tools provided by different organizations. Metadata management becomes a key issue when complex applications, such as data-intensive simulations and data mining applications, are executed on a Grid. This paper discusses metadata models for heterogeneous resource management in Grid-based data mining applications. In particular, it discusses how resources are represented and managed in the Knowledge Grid, a framework for Grid-enabled distributed data mining. The paper illustrates how XML-based metadata is used to describe data mining tools, data sources, mining models, and execution plans, and how metadata is used for the design and execution of distributed knowledge discovery applications on Grids.     

高速率光纤网开发情况评述

本文简述了高速光纤网络在实现B-ISDN中的作用及实用化存在的主要问题和解决这些问题的途径。着重介绍了国外对光时分多路复用接入(OTDMA)网络和波分多路复用接入(WDMA)网络的研究情况及实现方法。     

Simultaneous Scheduling of Replication and Computation for Data-Intensive Applications on the Grid

Managing large datasets has become one major application of Grids. Life science applications usually manage large databases that should be replicated to scale applications. The growing number of users and the simple access to Internet-based application has stressed Grid middleware. Such environment are thus asked to manage data and schedule computation tasks at the same time. These two important operations have to be tightly coupled. This paper presents an algorithm (Scheduling and Replication Algorithm, SRA) that combines data management and scheduling using a steady-state approach. Using a model of the platform, the number of requests as well as their distribution, the number and size of databases, we define a linear program to satisfy all the constraints at every level of the platform in steady-state. The solution of this linear program will give us a placement for the databases on the servers as well as providing, for each kind of job, the server on which they should be executed. Our theoretical results are validated using simulation and logs from a large life science application. This work was supported in part by the ACI GRID and Grid5000 projects of the French Department of Research.     

High Performance Interconnect Network for Tianhe System

In this paper, we present the Tianhe-2 interconnect network and message passing services. We describe the architecture of the router and network interface chips, and highlight a set of hardware and sof...     

高性能声纳数据采集处理系统

开发了一组高性能的数据采集和处理模块，叙述了这种采集处理模块如何有效地用于主动声纳接收机中。由于Ｓｉｇｍａ－Ｄｅｌｔａ结构的基本采样特性和完善性能，这种基于Σ－Δ结构的采集处理模块十分适合于声纳和其它音频的实时应用。     

Management Architecture for ATM Over ADSL-Based Access Networks

ADSL (Asymmetric Digital Subscriber Line) is a new key technology for offering broadband services to home users and small businesses. ADSL technology is ready to take off. Management discussions aim at achieving an ADSL broadband service architecture are still taking place, however. In order to support multiple services over widely spread networks incorporating various transmission techniques, a cost-effective network operation requires an end-to-end network management architecture. We describe here how to integrate ADSL equipment into the existing telecommunications management network. Alternative protocols and information models are also discussed. The overall network management architecture gives the motivation for the management concept applied to our Digital Subscriber Line Access Multiplexer (DSLAM). The design of such a network element covers all management functionality that is required to multiplex ATM connections being transferred over the ADSL system and to integrate the network element into any telecommunications network. We have chosen a flexible approach to adapt the DSLAM management to different usage environments.