减少IP视频会议中系统网络拥塞影响的方法

本文以本实验室自行研究开发的基于 IP网络的视频会议系统为例 ,讨论了因网络拥塞引起的图像不连贯、时延等问题 ,给出了自己的解决方法 ,即循环缓冲区队列及多线程方法 ,以及缓冲区队列的管理方法     

一种基于子网关联的事件关联机制

故障在网络运行中是不可避免的，一旦故障产生，会在网络中进行传播，产生大量的告警事件，如何能够快速有效地从这些告警事件中准确进行事件关联，从而给故障定位是网络管理的关键会务，在研究故障的传播机制基础上提出了一种基于子网的事件关联机制，把事件的关联范围限定在事件发出者所存在的子网中，同时，还提出了自己的事件操作模型，分为预处理操作，基于操作和位置操作，最后提出了实现该机制的算法，测试了该算法的效率，并进行了性能分析。     

机载海洋激光测深仪实时测控系统实现

介绍了在机载海洋测深仪中，采用串行总线主－从式通信网络结构的测控系统的实现过程，讨论了实时测控系统应用软件设计过程中应该考虑的三个问题：通讯手段、线程观点，同步方法。     

专用安全操作系统

随着Internet的高速发展，安全问题显得日益重要。而计算机操作系统是信息系统的安全基础，但传统的操作系统安全机制已缺乏足够的灵活性，不能提供面向分布式环境的，可根据具体应用系统配置特定安全策略的机制。提出了一种专用安全操作系统的体系结构，用户可使用基于事件的高层定义语言来描述与进程相关的安全策略而无须关心底层细节，因此系统具有良好的适应能力和可扩展性。     

Independence and Possibilistic Conditioning

There is not a unique definition of a conditional possibility distribution since the concept of conditioning is complex and many papers have been conducted to define conditioning in a possibilistic framework. In most cases, independence has been also defined and studied by means of a kind of analogy with the probabilistic case. In [2,4], we introduce conditional possibility as a primitive concept by means of a function whose domain is a set of conditional events. In this paper, we define a concept of independence associated with this form of conditional possibility and we show that classical properties required for independence concepts are satisfied.     

A modified normality condition for decentralized supervisory control of discrete event systems

In this paper, we study nonblocking decentralized supervisory control of discrete event systems. We introduce a modified normality condition defined in terms of a modified natural projection map. The modified normality condition is weaker than the original one and stronger than the co-observability condition. Moreover, it is preserved under union. Given a marked language specification, there exists a nonblocking decentralized supervisor for the supremal sublanguage which satisfies L_m(G)-closure, controllability, and modified normality. Such a decentralized supervisor is more permissive than the one which achieves the supremal L_m(G)-closed, controllable, and normal sublanguage.     

Bundle event structures: A revised cpo approach

Bundle event structures equipped with a partial order ? have been used to give a true concurrency denotational semantics for LOTOS. This model has also been extended by time and stochastic information. Unfortunately it fails to yield a complete partial order (cpo) as we illustrate by an example.We propose a subset of all bundle event structures such that it forms a cpo. This subset is closed under the usual operators on bundle event structures. And as a consequence these operators are continuous. Therefore, this subset can be used to give a denotational semantics of LOTOS.     

Numerical research on the interaction between coronal mass ejection and streamer

By proposing a two-dimensional triggering model with concentrically circular closed magnetic field line structure, numerical research is made on the asymmetric propagation feature of coronal mass ejection (CME) in two cases emerging at the solar northern latitudes 10° and 45° respectively. The numerical results can qualitatively explain some features of CME event observed by the spacecraft SOHO and show that: (i) In these two cases, the triggering model can initiate CME with an asymmetric closed magnetic field structure, (ii) Closed magnetic structure of CME event will keep deflecting to the current sheet when it propagates away from the sun and this deflecting effect mostly happens within tens of solar radii before CME travels finally along the current sheet, (iii) The triggering model emerging at different locations can introduce CME events with different magnetic shapes. This shape happens to be circular and crescent when the triggering model emerges at the northern latitudes 10° and 45°, respecti     

LE-SBCC: Loss-Event Oriented Source-Based Multicast Congestion Control

Congestion control is an important building block of a Quality of Service (QoS) system for multicast-based multimedia services and applications on the World Wide Web. We propose an end-to-end single-rate source-based multicast congestion control scheme (LE-SBCC) for reliable or unreliable multicast transport protocols. It addresses all the pieces of the single-rate multicast congestion control problem including drop-to-zero issues, TCP friendliness and RTT estimation. The scheme design consists of a cascaded set of filters and a rate-based additive-increase multiplicative-decrease (AIMD) module. These filters together transform the multicast tree to appear like a unicast path for the purposes of congestion control. Unlike TCP, the scheme is not self-clocked but acts upon a stream of loss indications (LIs) from receivers. These LIs are filtered to get a stream of loss events (LEs) (S. Floyd et al., in SIGCOMM 2000, Aug. 2000) (at most one per RTT per receiver). This LE stream is further filtered to extract the maximum LEs from any one receiver. Then the scheme effects at most one rate-reduction per round trip time (RTT). A range of results (simulation and experimental) is presented and compared against the mathematical model of the scheme components. Furthermore, we have successfully adapted TFRC (Op. cit) to our scheme, which is important to multimedia services desiring relatively stable rates over short time scales.     

一种用户界面设计方法

本文讨论了用户界面设计的原则，总结了ＣＡＤ／ＣＡＭ系统用户界面的特点，提出一种用户界面模型及其实现方法，在该用户面模型中，选单结构，选单生成机制和命令控制方式是基于开发用户界面实践过程建立起来的，该选单结构与选单生成机制相结合，大大简化了应用程序和界面的装配，只须要修改选单文件即可实现选单的重新布局和调整，该命令控制方法主要研究循环命令的控制，多种方式控制和多层命令控制。