Fat-tree routing and node ordering providing contention free traffic for MPI global collectives

As the size of High Performance Computing clusters grows, so does the probability of interconnect hot spots that degrade the latency and effective bandwidth the network provides. This paper presents a solution to this scalability problem for real life constant bisectional-bandwidth fat-tree topologies. It is shown that maximal bandwidth and cut-through latency can be achieved for MPI global collective traffic. To form such a congestion-free configuration, MPI programs should utilize collective communication, MPI-node-order should be topology aware, and the packet routing should match the MPI communication patterns. First, we show that MPI collectives can be classified into unidirectional and bidirectional shifts. Using this property, we propose a scheme for congestion-free routing of the global collectives in fully and partially populated fat trees running a single job. The no-contention result is then obtained for multiple jobs running on the same fat-tree by applying some job size and placement restrictions. Simulation results of the proposed routing, MPI-node-order and communication patterns show no contention which provides a 40% throughput improvement over previously published results for all-to-all collectives.     

基于人工神经网络的原油触变特性参数计算

基于Levenberg-Marquardt算法的前馈BP网络的原油触变特性参数计算方法,计算触变特性参数精度高,不依赖于具体的函数形式,能有效克服传统计算方法的不足。     

3G网络基站电磁环境影响分析

通过资料收集、理论预测、数据监测与分析,讨论了辽宁某市3G网络基站中典型基站的电磁环境。结果表明,理论预测与实际监测结果差距不大,各典型基站的电磁辐射功率密度均低于国家标准限值8μW/cm2,对该地区的电磁环境影响不大。对保护环境提出了相应的对策措施.     

利用ACL在校园网内实现安全管理

阐述了ACL(Access Control List)基本原理、分类及简单配置方法,并结合实际案例进行了分析并配置,说明如何在校园网中使用ACL进行网络层访问权限控制,提高网络整体性能和安全.     

混合模式的入侵检测技术研究

针对传统入侵检测所采用模式匹配技术存在的弊端,介绍了协议分析技术在入侵检测中的应用,提出了一种混合模式的入侵检测技术,即混合使用特征匹配模式和协议分析技术,充分发挥两者的长处。研究表明,该模型提高了检测效率,减少了误报和漏报。     

Mean waiting time evaluation of packet switches for centrally controlled PBX''s

The performance analysis of packet switched networks usually does not account for the loss of transmission bandwidth caused by the switch processing time. In wide area networks, where transmission channels are of the order of 64 kbps or less, this is a valid approach since switch processing time is negligible compared to average transmission times for packets. However, in Local Area Networks (LANs), the transmission channels are usually of the order of 1 mbps or greater and thus when evaluating the performance of a LAN that is based on a packet switch, it is necessary to consider the effect of the switch processing time which is now comparable to that of the average packet's transmission time. This paper investigates the effect of this processing time on network performance, and an exhaustive cyclic queueing algorithm to minimise this effect on overall network performance is discussed. An approximate analytical technique for evaluating the performance of such a LAN is derived. This technique makes it possible to do interactive calculations which can be used in the provisioning and configuring of such networks.     

水源热泵中央空调控制与网络监控系统

水源热泵中央空调控制与网络监控系统主要是针对现代使用的一种新型高效、节能、环保的空调进行的原理分析、系统设计和控制设计,实现空调系统的智能化控制,同时该系统运用现代高科技、高速度的网络技术对系统进行网络监控,打破了原有的工业远程监控的模式,在工业自动化领域和计算机网络领域均是一种创新和突破。该系统具有环保、节能、可靠性高、自动化程度高等特点,具有很高的经济效益和社会效益,应用前景广阔。     

基于内容的图像检索系统

文章介绍了基于内容的图像检索技术及其优势，并举了几个例子。     

Win2003 Server中用户的批量建立和管理

使用一种简单有效的批处理文件方法解决大量用户建立的问题,简化了管理任务繁重,重复性工作多,出错几率增大的网络管理工作,极大的提高了个人和单位的工作效率,减少了错误发生,对于在网络出现不可恢复故障后及时重新构建用户方面具有重要的意义。     

基于网上开放虚拟实验室的研究与设计

首先对网上开放虚拟实验室的基本概念、体系结构和管理模式进行介绍,分析了设计网上开放虚拟实验室的关键技术。最后设计和实现了网上开放虚拟实验室。