Defining and controlling the heterogeneity of a cluster: The Wrekavoc tool

The experimental validation and the testing of solutions that are designed for heterogeneous environments are challenging. We introduce Wrekavoc as an accurate tool for this purpose: it runs unmodified applications on emulated multi-site heterogeneous platforms. Its principal technique consists in downgrading the performance of the platform characteristics in a prescribed way. The platform characteristics include the compute nodes themselves (CPU and memory) and the interconnection network for which a controlled overlay network above the homogeneous cluster is built. In this article we describe the tool, its performance, its accuracy and its scalability. Results show that Wrekavoc is a very versatile tool that is useful to perform high-quality experiments (in terms of reproducibility, realism, control, etc.).     

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根据天然气管网的系统特征，阐述了天然气管网中的基本关系式和在天然气管网仿真中的应用方法；讨论了天然气管网静态仿真节点压力法和动态仿真特征线法的原理和仿真系统模型的建立方法。根据这些方法和长期的科研实践，研制了天然气管网静动态仿真软件ＧＡＳ－ＦＬＯＷ。该对管网结构不作，达用于由管道，调压阀，压缩机，气田及众多气源和用户组成的任意环状和枝状管网，实现天然气集，输，配管网的静动态仿真。还介绍了ＧＡＳＦＬ     

基于TerraGate的分布式三维仿真系统设计与实现

基于网络的分布式三维仿真系统是当前城市三维仿真系统的一个重要发展方向。如何有效利用现有的城市三维仿真系统建设成果,快速构建面向网络用户的分布式系统,是行业需要解决的一个关键问题。本文尝试结合Ter-raGate网络组件和Web服务器两种模式,分别提供不同类型的数据,设计一个可操作的面向网络应用的系统框架,并实现其原型。     

Evaluation of the control performance of hydronic radiant heating systems based on the emulation using hardware-in-the-loop simulation

This study presents an emulation method to evaluate the control performance of a hydronic radiant heating system. Since heat output in the system is dependent on the pressure loss and flow rate in the hydronic network, the interaction between thermal and hydronic models needs to be considered in the evaluation of the control performance. For this reason, many studies apply an integrated simulation to the evaluation; however, the analysis of the hydronic network sometimes leads to unreliable results due to the improper initial values for algebraic loops or the lack of modeling information on the hydronic components. In order to deal with this problem, this study suggests an emulation method, where the hydronic network is replaced by real hardware and the building physics is analyzed by a simulation. In the emulation, the pressure loss and flow rate in the hydronic network were represented by replacing the real pipe with equivalent hydraulic resistance. In addition, by using real control systems that connect the hydronic network and building simulation, the interaction between building physics and hydronic network could be considered in the evaluation. Based on the proposed emulation method, the performance of several control strategies was evaluated in terms of the accuracy and the rise time. The result shows that the individual control needs to be combined with hydronic balancing for more accurate control. Hydronic control devices such as a flow limit valve and a pressure differential control valve also proved to be helpful to the improvement of the control performance.     

一种竞赛用机器人的设计与实现

为提高机器人在准确分拣前提下快速完成搬运任务的能力,对传统自动分拣搬运机器人从策略选择、硬件组成和外观结构进行了全新的设计,提出了一种竞赛用自动分拣搬运机器人的设计与实现方法。针对竞赛要求采用全新设计的非航行推测算法;硬件模块化设计,核心控制器采用了国内少见的双核形式,并采用多种传感器来满足竞赛要求;通过避障与路径选择的仿真调试,确定了机器人的外观结构及竞赛路径。实践检验了设计的有效性和先进性,研究结果对于提高竞赛用机器人的性能具有一定的参考价值。     

非固定连接卫星星座路径选择算法稳定性分析

与传统的相对固定的卫星网络拓扑不同,基于非固定方式连接的卫星网络,由于具有更加灵活的网络组织方式,以及卓越的抗毁性等优点,正在被越来越多地研究.针对这种网络,首先进行了抽象化的表述:通过最短路径算法递归搜索整个问题空间从而得到全状态空间,并且对链路切换这一概念给出了严格的数学定义.基于此种抽象化的过程,对问题空间赋予3种不同的权值,分析比较了各种权值在最短路径算法下的稳定性,用计算机仿真结果进行比较,论证了理论分析的正确性,为探索非固定方式连接的卫星网络算法移植的可能性进行了尝试.     

ATM局域网仿真的实现

ATM局域网技术是当前网络界的热点,它是ATM网络与以太网互连的关键技术,本文论述了ATM论坛的局域网仿赵（LAN Emulation）技术的原理及其实现技术。     

管网可视化调度技术在川西气田的应用

管道仿真技术是日常天然气集输管理中，提高天然气集输调度科学水平、提高管网运行的经济性和安全性的关键。文章介绍的管道仿真调度是根据川西气田管网特点建立的一套服务于管网设计、改造以及运行分析和调度管理等方面的实用技术。它与地理信息可视化技术相结合，形成了具有管网分析功能特征的管道可视化调度技术，使管网规划、管理和运营变得科学、直观和高效。该技术在川西气田天然气集输配调度、管道系统的维护改造、增压方案优化以及新井投产路线规划等方面都发挥了重要作用，保证了该地区集输管网的安全营运。     

Compiled instruction set simulation

An efficient method for simulating instruction sets is described. The method allows for compiled instruction set simulation using the macro expansion capabilities found in many languages. Additionally, we show how the semantics of the C case statement allows instruction branching to be incorporated in an efficient manner. The method is compared with conventional interpreted techniques and is shown to offer considerable performance benefits.