基于客户/服务器结构的分布式问题求解系统

基于客户／服务器结构的分布式问题求解系统鲁东明何志均（浙江大学人工智能研究所杭州３１００２７）关键词智能问题求解，分布式系统，客户服务器模型，集成化知识推理．１）国家自然科学基金资助项目．收稿日期１９９４－０７－２２１引言客户／服务器技术使问题求解的...     

人工神经网络的并行分布处理

神经元的映射分配是人工神经网络虚拟实现中的重要研究课题。本文系统地分析了人工神经网络的重要性质－并行分布处理，并对映射分配问题中的两个关键性概念－负载均衡和通信开销进行了深入讨论。以此为基础，提出了一系列映射算法，并对算法性能进行了分析。其中，吸收算法最大程度地开发了人工神经网络固有的并行性，是一个实时的算法。     

Building Large,Complex, Distributed Safety-Critical Operating Systems

Safety-critical systems typically operate in unpredictable environments. Requirements for safety and reliability are in conflict with those for real-time responsiveness. Due to unpredictable environmental needs there is no static trade-off between measures to accommodate the conflicting objectives. Instead every feature or operating system service has to be adaptive. Finally, for any design problem, there cannot be any closed-form (formal) approach taking care at the same time of (external) time constraints or deadlines, and synchronization requirements in distributed design. The reason is that these two aspects are causally independent. - In this situation we worked out a heuristic experimental, performance-driven and performance-based methodology that allows in an educated way to start with a coarse system model, with accurate logical expectations regarding its behavior. Through experiments these expectations are validated. If they are found to successfully stand the tests extended expectations and model features are generated for refining the previous design as well as its performance criteria. The refinement is done in such a way that the previous experimental configurations are extreme model cases or data profiles which both logically and experimentally are to reproduce the behavior of the previous modeling step. Thus the novel performance aspects or tendencies could then unambiguously be attributed to the influences of the refined model features. We termed this methodology Incremental Experimentation. As a general methodology it relies on a principle of comparative performance studies rather than on realistic data for narrow application ranges. The paper describes how we applied a 5-step design and refinement procedure for developing, analyzing, and evaluating our distributed operating system MELODY that exhibits novel services for supporting real-time and safety-critical applications in unpredictable environments. Experimental set-ups and theme-related findings are discussed in particular.     

On Using Real-Time Static Locking Protocols for Distributed Real-Time Databases

The use of Static Two Phase Locking Protocols (S2PL) for concurrency control in real-time database systems (RTDBS) has received little attention in the past. Actually, real-time S2PL (RT-S2PL) protocols do possess some desirable features making them suitable for RTDBS, especially for distributed real-time database systems (DRTDBS) in which remote locking is required and distributed deadlock is possible. In this paper, different RT-S2PL protocols are proposed. They differ in their methods of reducing the blocking time of higher priority transactions. Their performance is studied and compared with a real-time dynamic two phase locking protocol (RT-D2PL), called Hybrid Two Phase Locking (Hb2PL). The impact of different system and workload parameters, such as mean inter-arrival time of transactions, number of remote lock requests of a transaction, communication overhead for sending messages, and database size on their performance have been examined. The performance results indicate that the RT-S2PL protocols are suitable for DRTDBS in which the proportion of local locks of a transaction is small and the communication overhead for locking is high.     

Dawning-1000 PROOS Distributed Operating System

PROOS is a distributed operating system running on the computing nodes of massively parallel processing computer Dawning-1000.It is an efficient and easily extendible micro kernel operating system.It supports the Intel NX message passing interface for communication.     

非线性分布参数系统的块脉冲函数辨识法及截断项数的最佳选取

本文介绍了利用二维块脉冲函数辨识一类非线性分布参数系统的方法，强调并进行了这种近似处理下的误差分析，通过构建一非线性数规划模型讨论了截断项数的最佳选取问题，给出了两个实例以分别说明有关的概念和方法。     

多机容错操作系统DFTOS的设计与实现

本文介绍了一个适于三模冗余容错计算机系统的系统管理软件ＤＦＴＯＳ，它是一个多机容错操作系统，具有分布处理和容错计算功能，并且与用户具有良好的接口关系，方便用户对系统的使用和开发。     

滞后抛物型控制系统的变结构控制

讨论了滞后抛物型控制系统的变结构控制问题。通过对系统进行直接分析,给出了仅由状态函数描述的变结构控制器的设计方法。所得结果削弱了文献[7,10]中对系统的某些要求,减化了变结构控制器的设计步骤,并且给出了整个切换面为滑动模态区的条件以及轨线到达滑动模态区上的时间估计。     

Formal methods integration for the specification of dependable distributed systems

This paper describes a real-world case study in the specification and analysis of dependable distributed systems. The case study is an automated transport system with safety requirements. In order to manage the complexity of the problem of specifying the dynamic behavior of the whole system, a compositional approach is used, based on the integration of the trace logic of the Communicating Sequential Processes (CSP) theory, and stochastic Petri nets (SPNs). It is argued that the integration of different formal methods is a useful approach in the definition of practical engineering methodologies for the specification, design and analysis of complex dependable distributed systems.     

Compression Domain Volume Rendering for Distributed Environments

This paper describes a method for volume data compression and rendering which bases on wavelet splats. The underlying concept is especially designed for distributed and networked applications, where we assume a remote server to maintain large scale volume data sets, being inspected, browsed through and rendered interactively by a local client. Therefore, we encode the server’s volume data using a newly designed wavelet based volume compression method. A local client can render the volumes immediately from the compression domain by using wavelet footprints, a method proposed earlier. In addition, our setup features full progression, where the rendered image is refined progressively as data comes in. Furthermore, framerate constraints are considered by controlling the quality of the image both locally and globally depending on the current network bandwidth or computational capabilities of the client. As a very important aspect of our setup, the client does not need to provide storage for the volume data and can be implemented in terms of a network application. The underlying framework enables to exploit all advantageous properties of the wavelet transform and forms a basis for both sophisticated lossy compression and rendering. Although coming along with simple illumination and constant exponential decay, the rendering method is especially suited for fast interactive inspection of large data sets and can be supported easily by graphics hardware.