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。     

二维弹塑性流体力学LSPIC并行程序研究

针对二维弹塑性流体力学非结构网格拉氏应用程序(LSPIC),应用双线性插值、点排序和网格排序三种方法对计算区域进行分解。基于格式所需邻区网格的个数实现区与区之间的消息传递,建立一种非结构网格拉氏程序并行化方法,实现二维弹塑性流体力学拉氏应用程序(LSPIC)程序的并行化。同时进行程序测试和并行效率分析。     

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。     

MACROMOLECULAR STRUCTURE OF COALS. I. THE ORGANIC PHASE OF BITUMINOUS COALS AS A MACROMOLECULAR NETWORK†

The organic phase of bituminous coals may be represented as a three-dimensional macromolecular network, with chains consisting of aromatic or heterocyclic clusters and smaller connecting bonds, usually of etheric, sulfidicor methylenic nature. The crosslinks are covalently bonded bridges or hydrogen-bonded structures. The molecular weight between crosslinks, [Mbar]_C, and other parameters of the crosslinked structure can be calculated using the results of various experiments and applying theories widely used for the analysis of polymeric networks, albeit with significant modifications.     

Network structure and compositional effects on tensile mechanical properties of hydrophobic association hydrogels with high mechanical strength

Hydrophobic association hydrogels (HA-gels) were successfully prepared through micellar copolymerization of acrylamide (AM) and a small amount of octylphenol polyoxyethylene acrylate (OP-4-AC) in an aqueous solution containing sodium dodecyl sulfate (SDS). HA-gels exhibited excellent mechanical properties and transparency. Especially, HA-gels possessed the capability of re-forming, such as self-healing and molding. From Fourier transform infrared, swelling behavior and re-forming capability of HA-gels, the network structure was established. On the basis of the micellar copolymerization theory, the statistical molecular theory of rubber elastic, and using uniaxial stretching data, the length of the hydrophobic microblocks, the effective network chain density and the molecular weight of the chain length between cross-linking points were evaluated for all HA-gels; furthermore, they were also evaluated for the region of medium deformation by the Mooney-Rivlin theory. For HA-gels, we investigated in detail the effects of the content of compositions in the initial solution, OP-4-AC, SDS and AM, on their tensile mechanical properties on the basis of the proposed network structure. The results clearly indicate their tensile strength, fracture energy, elastic modulus, and elongation strongly depended on their composition content.     

公路联网收费系统网络故障诊断与解决措施探讨

随着社会经济的蓬勃发展,我国的公路系统也越来越发达。网络给公路收费系统带来便利的同时,也带来了危机。本文对公路联网收费系统常见网络故障进行了分析,并提出了相关解决措施。     

OMRON PLC网络与通信

可编程控制器与上位计算机组成的集散控制系统越来越广泛应用于生产过程自动化领域。本文介绍了OM—RONPLC的网络硬件组成及特点；通信模式；通信程序。     

人工神经网络与失效评定图在压力容器安全评定中的应用

采用人工神经网络与失效评定图相结合的方法对压力容器进行安全评定,样本评定结果和Ｒ６ 失效评定图方法的评定结果一致,并对评定结果进行了参数敏感性分析,分析结果令人满意。人工神经网络为压力容器安全评定智能化提供了一个有效的手段。