A Distributed System for Real-Time Applications

This versatile network uses multiple microprocessors and a split-bus architecture to collect and process real-time data from a variety of sources and then transfer it to different destinations.     

Sublinear Fully Distributed Partition with Applications

We present new efficient deterministic and randomized distributed algorithms for decomposing a graph with n nodes into a disjoint set of connected clusters with radius at most k−1 and having O(n ^1+1/k ) intercluster edges. We show how to implement our algorithms in the distributed CONGEST\mathcal{CONGEST} model of computation, i.e., limited message size, which improves the time complexity of previous algorithms (Moran and Snir in Theor. Comput. Sci. 243(1–2):217–241, 2000; Awerbuch in J. ACM 32:804–823, 1985; Peleg in Distributed Computing: A Locality-Sensitive Approach, 2000) from O(n) to O(n ^1−1/k ). We apply our algorithms for constructing low stretch graph spanners and network synchronizers in sublinear deterministic time in the CONGEST\mathcal{CONGEST} model.     

一种实时运动控制软件的建模与研究

为满足高速度、高精度的实时运动控制要求,本文针对自主研发的通用多轴运动控制器平台,进行实时运动控制软件的建模和研究.并以绗缝系统应用为实例,使用UML对绗缝实时运动控制软件建模,并设计出该控制软件.通过在绗缝系统中的应用,验证该模型的实用性.     

A Real-Time Performance Evaluation Model for Distributed Software with Reliability Constrains

In this paper, we propose an approach for the real-time performance analysis of distributed software with reliability constraints, called Athena. The approach is based on the real-time and reliability performance analysis of distributed program. In Athena, two important factors, imperfect nodes and the links reliability, are introduced. The algorithms proposed in Athena generates sub-graphs, counts the reliability of each sub-graph, calculates the transmission time for all the transmission paths of each data file, and computes response time of each data file with reliability constraint. In this way, the real-time performance of distributed software with reliability constrains can be evaluated.This paper is supported by National Science Foundation of China under grant 60273076.     

面向模式的分布式软件构架可视化建模

主要阐述了面向模式的分布式软件构架的概念、原理和常用构架模式的特点。重点研究了提出的面向模式的软件构架建模语言、可视化建模工具的设计原理、功能及特点等,并以一个具体应用实例展示了该建模工具的实用性。     

实时应用中软件时统的设计与实现

就实时测控软件的开发与运行环境问题,简单介绍了硬件时统设备在实时测控中的作用和重要地位以及实时操作系统的时间管理方式.针对软件时统设计中的两个关键技术展开分析与讨论,对软件时统的主要功能设计进行了重点描述,并给出便于程序开发的进程关系流图.     

Fundamentals of Implementing Real-Time Control Applications in Distributed Computer Systems

Automatic control applications are real-time systems which pose stringent requirements on precisely time-triggered synchronized actions and constant end-to-end delays in feedback loops which often constitute multi-rate systems. Motivated by the apparent gap between computer science and automatic control theory, a set of requirements for real-time implementation of control applications is given. A real-time behavioral model for control applications is then presented and exemplified. Important sources and characteristics of time-variations in distributed computer systems are investigated. This illuminates key execution strategies to ensure the required timing behavior. Implications on design and implementation and directions for further work are discussed.     

分布式卫星系统仿真支撑框架设计

分布式卫星系统是卫星技术发展的一个重要方向,但分布式卫星系统的复杂性也给传统的仿真技术提出了挑战.为降低仿真开发的难度,为分布式卫星系统仿真从模捌建立、仿真定义到仿真运行设计了支撑软件框架.基于支持实时分布式条件下通信的数据分发服务实现.并定义了进程间和进程内两层仿真支撑框架,使得可以根据仿真成员的特性灵活布置仿真成员.提高分布式仿真的计算效率.分布式卫星系统仿真支撑框架提高了仿真开发的灵活性和效率,并能满足分布式卫星系统仿真在仿真成员互操作性和可重用性方面的需求.     

Emergency Response Applications: Dynamic Plume Modeling and Real-Time Routing

In a crisis situation, toxic gas can be released into the air, blocking routes for emergency responders. Rescue workers must be able to compute the shortest and safest paths in the presence of toxic gas dispersions that move dynamically with changing wind speed and direction. To model this, the authors developed weather retriever software, which fetches weather details about a particular location from the Internet and acts as the station for atmospheric measurements for the Aloha plume-modeling software. The authors also explored options for displaying this dynamic plume on a geographic map.     

分布式虚拟环境中区域重叠划分研究

分布式虚拟环境在划分区域后,区域边界附近的化身不能实时交换动态信息。针对这一情况,提出了区域重叠划分方法,通过增加一定的网络负载和多播组数目,来最大限度地保证相邻化身之间实时交换数据。详细分析了区域重叠划分方法,以及实现中的具体问题。     

Software Reliability Growth Modeling: Models and Applications

This paper summarizes existing software reliability growth models (SRGM's) described by nonhomogeneous Poisson processes. The SRGM's are classified in terms of the software reliability growth index of the error detection rate per error. The maximum-likelihood estimations based on the SRGM's are discussed for software reliability data analysis and software reliability evaluation. Using actual software error data observed by software testing, application examples of the existing SRGM's are illustrated.     

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.     

An Experimental Study of Software Metrics for Real-Time Software

The rising costs of software development and maintenance have naturally aroused intere5t in tools and measures to quantify and analyze software complexity. Many software metrics have been studied widely because of the potential usefulness in predicting the complexity and quality of software. Most of the work reported in this area has been related to nonreal-time software. In this paper we report and discuss the results of an experimental investigation of some important metrics and their relationship for a class of 202 Pascal programs used in a real-time distributed processing environment. While some of our observations confirm independent studies, we have noted significant differences. For instance the correlations between McCabe's control complexity measure and Halstead's metrics are low in comparison to a previous study. Studies of the type reported here are important for understanding the relationship between software metrics.     

A Distributed System for Real-Time Transaction Processing

An experimental system designed as part of INRIA's Project Sirius, Delta implements a distributed executive for real-time transactional systems.     

分布式关联规则挖掘中的聚类分区算法

在分布式关联规则挖掘中首先需要解决分布武环境下的聚类分区问题,该文基于CURE的工作原理,提出了D-CURE算法。实验证明,D-CURE算法可以很好地解决分布式环境下聚类分区问题。     

分布式关联规则挖掘中的聚类分区算法

在分布式关联规则挖掘中,首先需要解决分布式环境下的聚类分区问题。该文基于CURE的工作原理,提出了D-CURE算法。实验证明,D-CURE算法可以很好地解决在分布式环境下的聚类分区问题。     

Automated Meta-Control for Adaptable Real-Time Software

The software meta-controller is an online agent responsible for dynamically adapting an application's software configuration, e.g. altering operational modes and migrating tasks, to best accommodate varying runtime circumstances. In distributed real-time applications such adaptations must be carried out in a manner which maintains the schedulability of all critical tasks while maximizing some notion of system value for all other tasks. For large-scale real-time applications, considering all possible adaptations at the task-level is computationally intractable. This paper presents an automated aggregate approach to software meta-control, appropriate for large-scale distributed real-time systems. The aggregate automated meta-control problem is still NP-hard, but it has very practical approximate solutions. Introduced, here, are two very-effective approximation algorithms, QDP and GG, with very reasonable polynomial time complexity. Both algorithms also provide us with upper bounds for optimum system values, useful for deriving absolute, albeit somewhat pessimistic, measures of actual performance. Extensive Monte Carlo analysis is used to illustrate that expected performance for both algorithms is generally suboptimal by no more than a few percent. Our flexible software meta-control model is also shown to be readily applied to a wide range of time-sensitive applications.