多控制器集群流媒体缓存代理的研究

为满足用户分散的大规模视频流媒体应用需求,该文提出了一种基于多控制器集群缓存代理结构(Multi- controller based Cluster Streaming Cache Proxy, MCSCP),该体系由一组控制器构成控制子系统,由多个内容存储器构成分布式存储子系统。对控制子系统的关键问题进行了深入研究:采用图论思想给出控制器组的选取算法,设计了一种基于优先级的主控制器选举和在线切换协议(Priority based Master-controller Election and Handover, PMEH)。建立数学模型分析了多控制器体系对系统可靠性的改善程度,讨论了控制器选取算法的性能,研究了协议中报文发送间隔变量与系统开销的关系,并使用仿真实验给出了该参数的最佳取值范围。     

Baggage Transportation and Navigation by a Wheeled Inverted Pendulum Mobile Robot

Our goal is to configure an automatic baggage-transportation system by an inverted pendulum robot and realize a navigation function in a real environment. The system consists of two cooperative subsystems: a balancing-and-traveling control subsystem and a navigation subsystem. Position errors of the inverted pendulum robot are often caused by a drift error in the gyro sensor and a change in the center of gravity by a loaded baggage when applying the linear state feedback control method for balancing and traveling. We have reduced the position errors for navigation by resetting the balance position occasionally while traveling with simple methods without an external observer or alternative sensors. In this paper, we state the method and show the experimental results of navigation in a real environment by the implemented robot system.     

B-ISDN multimedia communication and collaboration platform usingadvanced video workstations to support cooperative work

A distributed real-time computer-supported cooperative work (CSCW) platform called the B-ISDN group teleworking system is described. The system combines the high-speed multimedia communication capability with advanced video integrated workstations. The aim of this system is to support ad hoc meetings and real-time collaborative work between small groups of people who are geographically distributed. The main features of the system are face-to-face communication and the capability for sharing and comanipulating shared multimedia information including video. The concept and architecture of the system are described. A prototype group teleworking system that uses B-ISDN multimedia workstations is also described. A mock remote medical consultation application for the system is presented     

Random access protocols for high-speed interprocessor communicationbased on an optical passive star topology

A multiple-instruction multiple-data (MIMD) distributed memory parallel computer system environment is considered. Media access control protocols that maintain good performance with high capacity optical channels are investigated. Three examples of star-coupled structures are introduced, one of which exhibits optical self-routing. Self-routing single-step optically interconnected communication structures can be designed through the incorporation of agile laser diode sources and wavelength tunable optical filters in a wavelength-division multiple-access environment. Intermediary latencies typical of MIMD distributed memory systems are eliminated. The degree and diameter of the resulting structures are dramatically reduced, and the complexity of the communication subsystem is reduced since intermediate buffering and routing of packets are eliminated     

Distributed coding for cooperative wireless networks: an overview and recent advances - [Topics in ad hoc and sensor networks]

Cooperative communication has been shown to be an effective technique enabling singleantenna users to share their antennas to create a virtual MIMO system, thus providing extra spatial diversity in wireless networks. Distributed coding is a type of channel coding strategy developed for cooperative wireless networks. As opposed to conventional channel coding schemes, distributed coding constructs the whole codeword in a distributed manner among the cooperative users. Properly designed distributed coding can effectively approach the capacity of cooperative wireless networks. The aim of this article is to present an overview of recent development in distributed coding design in cooperative wireless networks.     

面向工程应用的群体DSS分布式问题求解算法及实现

文章在智能Agent协同控制技术基础上，提出面向工程领域分布式问题求解的群体DSS多库协同工作模式．并重点分析了分布式问题求解的群体协同控制策略，实现了工程领域问题的分布式问题求解算法，最后通过某飞行器设计实例进行了验证。     

Impedance specifications for stable DC distributed power systems

In a DC distributed power system, the interaction between individually designed power modules/subsystems may cause the instability of the whole system. In a small-signal sense, system level stability is determined by the impedance ratio Z_o/Z_i. Here, Z _o is the output impedance of the source module/subsystem, and Z_i is the input impedance of the load module/subsystem. As a result, an effective way to prevent system instability is defining impedance specifications for modules/subsystems. This paper briefly summarizes existing works and introduces the authors' contribution in defining impedance specifications. A new forbidden region for impedance ratio Z_o/Z_i on the S-plane is proposed as the system stability margin requirement. Based on this proposed forbidden region, the impedance specifications of individual loads are established. Further, a very practical measurement approach is developed to examine whether or not the system stability margin requirement of the forbidden region is satisfied     

Development and evaluation of an in-house multimedia desktopconference system

An in-house computer-supported desk-to-desk conference system that allows a group of users to conduct a meeting in real time from their telephone-attached personal computers is described. Participants can jointly view and edit relevant multimedia information, including text, graphics, images, and handwritten information distributed through a local area network. Participants can also simultaneously communicate by voice to discuss the information they are sharing. The system's design principle, i.e. the group communication architecture, and the protocol for conference coordination are discussed. The system configuration, service functions, and related control mechanisms are presented. User experiences and the results of feasibility evaluations are examined. The system has proved to be applicable to a wide variety of cooperative work, such as distributed software development, joint authoring, and group decision support     

Cooperative OFDM for semi distributed detection in wireless sensor networks

In this paper, parallel distributed detection in wireless sensor network (WSN) is investigated. Sensors are assumed to be transmitting their local decisions to a fusion center through a wireless fading channel using cooperative transmission. To enable cooperative transmission, sensors are divided into groups where sensors in each group help each other in transmitting their decisions in a way that the fusion center receives each local decision as an orthogonal frequency division multiplexed (OFDM) block. The fusion center detects all OFDM blocks sent by all groups to process them in order to obtain a final (global) decision. Using this cooperative transmission scheme enables the fusion center to apply diversity combining methods in order to reduce the fading effects of the channel. Optimal and sub-optimal fusion rules are derived for such system. Simulation results are provided to show the performance improvement that can be obtained compared to the conventional system where each local decision is transmitted to the fusion center individually and no diversity technique is applied at the fusion center.     

会议电视控制器

介绍了综合业务光纤双总线局域网中，会议电视（CTV）控制子系统的设计、研制方法，该子系统实际上是一分布式多CPU控制系统，也是一数据通信子网。     

微反应槽PCR芯片阵列温度控制系统

设计了内部不含传感元件、加热元件的低成本微反应槽聚合酶链式反应(PCR)芯片,研制了宏观集中控制与微观分散控制有机结合的PCR芯片阵列温度控制系统。宏观集中控制装置以水为媒质通过特制换热器给芯片提供聚合酶链式反应所需的基本温度;在柔性印刷电路板上形成与芯片阵列对应的微型加热器阵列,针对各芯片进行分散的温度补偿。采用串级控制获得微加热器阵列与换热器之间的良好配合,实现各芯片准确、快速的温度控制。     

Model predictive control of bidirectional isolated DC–DC converter for energy conversion system

Model predictive control (MPC) is a powerful and emerging control algorithm in the field of power converters and energy conversion systems. This paper proposes a model predictive algorithm to control the power flow between the high-voltage and low-voltage DC buses of a bidirectional isolated full-bridge DC–DC converter. The predictive control algorithm utilises the discrete nature of the power converters and predicts the future nature of the system, which are compared with the references to calculate the cost function. The switching state that minimises the cost function is selected for firing the converter in the next sampling time period. The proposed MPC bidirectional DC–DC converter is simulated with MATLAB/Simulink and further verified with a 2.5 kW experimental configuration. Both the simulation and experimental results confirm that the proposed MPC algorithm of the DC–DC converter reduces reactive power by avoiding the phase shift between primary and secondary sides of the high-frequency transformer and allow power transfer with unity power factor. Finally, an efficiency comparison is performed between the MPC and dual-phase-shift-based pulse-width modulation controlled DC–DC converter which ensures the effectiveness of the MPC controller.     

动平台分布式雷达系统协同跟踪路径优化算法

本文针对动平台分布式雷达系统协同跟踪目标的路径优化问题,提出了一种新颖的基于费歇尔信息矩阵的动平台分布式雷达系统协同跟踪路径优化算法。首先,本文建立了动平台分布式雷达系统协同跟踪目标模型,进而基于贝叶斯理论导出了闭合形式的费歇尔信息矩阵,然后采用D最优准则建立了动平台分布式雷达系统路径优化代价函数,最后提出了一种基于最速下降的方法来解决该优化问题。另外,本文还研究了有约束的动平台分布式雷达系统路径优化问题,利用惩罚函数来修正代价函数来规避障碍,并应用物理约束来限制动平台的转弯角。数值仿真结果验证了所推导的闭式代价函数的精确性和有效性,且所提出的动平台分布式雷达系统路径优化方法可以快速实时的以较为平滑的路径跟踪静止和移动目标;此外,相比于栅格搜索法,所提方法在计算复杂度上具有明显优势。      

一种分布式喷泉码在协作通信中的应用

为了减少基于数字喷泉码的协作传输系统中的计算复杂度和传输延迟,提出了一种基于分布式喷泉码的协作通信传输方案,给出了两层数字喷泉编码的度分布函数的设计过程;以各链路的丢包率为参量分析了系统传输时延,并与其他数字喷泉码传输方案进行了比较.理论分析和仿真结果表明,在各链路丢包率较大时采用这种分布式喷泉码的协作传输机制能在传输时延上显著改善系统性能,而且各链路删除概率越大时优势越明显.     

面向分布式环境的信号驱动任务调度算法

为优化IaaS服务的执行效率,提出面向IaaS的信号驱动任务调度算法,该算法根据IaaS模型的结构特征建立控制子系统和节点子系统,根据任务的结构特征建立任务的DAG(directed acyclic graph)调度模型,并建立各任务分片的状态转化机制及控制子系统和节点子系统间的信号通信机制。以系统间信号交互的方式驱动任务分片的状态改变,并在每一调度时刻来临时利用并行优化选择策略分配任务分片。由于本算法采用了模拟IaaS模型的双系统控制方式,使本算法与IaaS模型的分布式体系相兼容且复杂度较低。最后通过实验验证了所提算法的有效性和实用性。     

基于代理的Web协同出版体系

超级站点的负载过重是 Ｗ Ｗ Ｗ （简称 Ｗ ｅｂ ）出版的一个焦点问题,而当前的解决方案又存在资源浪费等缺陷。因此,我们提出了一个 Ｗ ｅｂ 协同出版体系,它的核心要素是协同工作的 Ｗ ｅｂ 服务器群子系统和 Ｗ ｅｂ 浏览器群子系统。由于我们在该系统中应用了 Ｃ Ｓ Ｃ Ｗ 和代理等关键技术以及信任、主动和对等的协同机制,所以它具有传统的 Ｗ ｅｂ 出版所不具备的优点。     

MPC在大功率交流牵引中的应用

目前由交-直-交电压型功率变换器和异步牵引电动机所构成的交流传动系统，已成为世界电力机车、电动车组和城轨车辆电传动技术的主流，而交流传动的核心单元是牵引变换器。本文对原ADtranz公司所设计的模块化功率变换器-MPC的技术特征进行了归纳和分析，最后指出随着电力电子技术和微处理器技术的发展，模块化及分布式控制系统已经成为功率变换器的发展趋势。     

MPC在大功率交流牵引中的应用

目前由交-直-交电压型功率变换器和异步牵引电动机所构成的交流传动系统，已成为世界电力机车、电动车组和城轨车辆电传动技术的主流，而交流传动的核心单元是牵引变换器。本文对原ADtranz公司所设计的模块化功率变换器-MPC的技术特征进行了归纳和分析，最后指出随着电力电子技术和微处理器技术的发展，模块化及分布式控制系统已经成为功率变换器的发展趋势。     

8mm战场侦察雷达信号处理系统的实现

论述了８ｍｍ战场侦察雷达信号处理系统的距离估算、参数计算、硬件结构等问题。在距离估算中提出了综合相参积累和非相参积累的雷达距离公式。信号处理算法采用流水线结构,根据这一特点,整个硬件系统采用６片ＡＤＳＰ２１０６０数字信号处理芯片,通过巧妙的连接组合实现了系统所要求完成的算法。通过扩展的串口和并口实现了和天控、计算机有效连接。     

医用回旋加速器控制系统设计

医用回旋加速器目前广泛应用于国防基础科学研究、同位素生产以及诊断、治疗等应用领域,然而都无一例外地要求其稳定性、安全性。本文从医用回旋加速器的应用需求出发,概述了控制系统的组成、各子系统的作用,详细阐述了以RX3i可编程控制器为前端控制器的系统集成、高频系统的低电平控制的控制策略以及不同工作模式下各系统间的安全联锁。连续的运行结果表明：控制系统保证了整个系统的平稳运行,满足了加速器运行及其调试要求。