电视台网络化的技术原理和实施方法

本详细阐述了电视台网络化的组网原理和相关的存储、压缩、管理技术，论述了网络化的主要实施环节，分析了媒体资产管理系统的技术精髓，结合深圳电视台的实际状况，给出了实现制作、播出、存储和管理业务于一体的综合网络规划方案。     

Study of electrical and dielectric properties of styrene-acrylonitrile/graphite sheets composites

This paper reports the structural, electrical, dielectric and mechanical properties of the Styrene-acrylonitrile (SAN)/graphite sheets (GS) composites. The composites were prepared by in situ polymerization. The variation of electrical conductivity, dielectric constant and ac conductivity as a function of volume fraction of GS was found to follow the power law model. The dielectric constant and dissipation factor of SAN/GS composites increased significantly near the percolation. The frequency dependence of dielectric constant, dissipation factor and ac conductivity was also analyzed. Nearly ohmic behavior of current density with electric field was observed above the percolation threshold. The composite was found to possess the hardness of pure polymer at the threshold value of GS.     

iSCSI虚拟交换机包转发调度算法FC-WFQ

与传统IP交换机不同,iSCSI虚拟交换机不仅实现IP数据包的转发,还应完成TCP、iSCSI和SCSI的协议处理.短包优先调度算法可保证iSCSI控制及命令PDU(Packet Data Unit)的优先传输,却未对该类数据包的转发带宽作出限制,该方法缺少针对iSCSI数据流特性的定量分析.通过排队理论建立iSCSI虚拟交换机转发iSCSI PDU过程的数学模型,然后提出一种iSCSI虚拟交换机的包调度算法FC-WFQ(Flow Control-WFQ),最后应用网络仿真软件ns-2建立仿真场景对交换系统进行测试.随着命令到达率以及命令中读写比例的变化,FC-WFQ对各数据流的转发带宽权重做相应的实时调整.实验结果显示,该调度算法可明显降低读写任务的平均响应时间,并显著提高iSCSI虚拟交换机的吞吐量.     

Shear Effect on Morphology of Poly(Butylene Terephthalate)/Poly(Styrene‐co‐Acrylonitrile) Blends

Abstract

The shear flow effect on the morphology of poly(butylene terephthalate)(PBT)/poly(styrene‐co‐acrylonitrile)(SAN) was studied by a parallel plate type shear apparatus. In PBT/SAN = 20/80 blend, particle size of dispersed domains was governed by both break‐up and coalescence processes, and it was much affected by shear rate. The minimum particle size was observed at a certain shear rate. This phenomenon can be explained by the shear matching effect of PBT and SAN; that is, the viscosity ratio of PBT to SAN changed with shear rate and the finest morphology was obtained at the appropriate viscosity ratio. Similar behavior was also observed for PBT/SAN = 70/30 (PBT was the matrix), even though the particle size was larger than that of PBT/SAN = 20/80. For PBT/SAN = 10/90 blend, the sample showed a complicated appearance during shearing. A translucent region correlated to the fine morphology was observed more than twice with increasing shear rate. This phenomenon could not be explained by the viscosity matching effect only. It was affected by small changes in the balance of breaking‐up and coalescence effects.     

电信企业信息化建设的几点考虑

本文结合目前电信企业信息化的现状和问题,提出了对于电信企业信息化建设的几点思考,主要关注电信企业信息化建设涉及的规划、技术、管理、人才等方面.     

Phase separation and phase dissolution in poly(ε-caprolactone)/poly(styrene-co-acrylonitrile) blend

A blend of poly(ε-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) containing 27.5 wt% of acrylonitrile having the critical composition (80/20 PCL/SAN) was studied. This PCL/SAN blend having a lower critical solution temperature (LCST) phase boundary at 122 °C offered an excellent opportunity to investigate, firstly the kinetics of phase separation above LCST (125-180 °C), and secondly the kinetics of phase dissolution below LCST (50-115 °C). The blend underwent a temperature-jump above LCST where spinodal decomposition (SD) proceeded, yielding a regularly phase-separated structure (SD structure). Then, it was quenched to the temperatures below LCST when the phase dissolution proceeded. Optical microscopy was used to observe the spinodal decomposition qualitatively while light scattering was used to characterize the phase separation and phase dissolution quantitatively. It was found that during phase dissolution the peak maximum moved towards a smaller angle (wavelength of concentration fluctuations increased) while the peak intensity decreased. This behavior was explained by a model. Also it was found that the fastest phase dissolution kinetics at 80 °C, which was characterized by an apparent diffusion coefficient, was about 10 times slower than the kinetics of phase separation at 180 °C.     

视频监控工程难点及解决方案探讨

主要介绍了目前视频监控的发展情况,以平安工程为例,对视频监控工程中的三个难点问题进行了分析和探讨,并给出了对于这几个问题解决方案。通过这些方案在视频监控工程中的应用可以开阔视频监控工程的建设思路,有助于建立一个具有高可用性、可管理、易维护的监控平台。     

全台网存储架构的选择分析

介绍了FCSAN和IPSAN两种存储架构在全台网环境下构建存储局域网所能发挥的不同优势和特性,结合未来技术的发展方向,提出选择存储架构需考虑的因素,探讨合理构建存储网络的方法。     

iSCSI分析及其Linux驱动实现

iSCSI,是IETF制订的用于将SCSI数据块映射成以太网数据包的一项标准,是实现IP存储的重要技术之一。本文分析了iSCSI协议及其Linux系统中驱动的实现方法。     

企业级数据存储解决方案浅析

介绍了目前企业级数据存储的3种解决方案，并对其中的2种主流方案进行详细对比和分析。