基于中国科技网的网络流畅度分析

在互联网时代,伴随着网络传输数据量的激增,流量给网络带宽带来越来越大的压力,用户越来越关注自己的网络体验情况,并对高带宽网络的需求越来越迫切.但如何反映并且度量用户体验仍是一个难题.本文对网络带宽使用现状(是否流畅)进行合理分析,利用网络流畅度反映用户体验,从宏观和微观两个层面分别建立网络流畅度模型,并利用上述模型对中国科技网进行评价,对其现状和产生此现状的原因进行了深入的分析.本文的方法能够为现有网络是否进行带宽扩容及如何合理地配置带宽提供一定的参考.     

我国大型科学仪器设备使用状态分析及政策含义

Recently, how to improve the utilization efficiency of large scientific instruments and equipment (LSIE) has been the focus in scientific field. The “open sharing” of LSIE has nearly become the standard solution to this problem. However, there is no linear relationship between the extent of sharing and the utilization rate of LSIE. Based on the “survey on the conditions of national science and tehcnology infrastructure (2009)” which was sponsored by National Science and Technology Infrastructure Center with the Ministry of Science and Technology, the authors adopt the state-space analysis method and analyses the utilizing and sharing state of large scientific instruments from various aspects. And the authors present that only by implementing different measures to different LSIE can we achieve the goal of raising the utilization efficiency.     

中国深空网VLBI相关处理器开发与应用

以中国深空网干涉测量信号处理中心建设为背景,论述了VLBI软相关处理系统的设计及初步实现。依据数据处理流程对软件模块化划分,一方面采用时间并行处理策略,将数据流按子积分周期分配给多个计算节点;一方面在相关计算节点内部应用多线程处理最大化提升效能。依托高性能集群系统,采用两级并行处理策略,实现了软件的设计开发,并在"嫦娥3号"(CE-3)任务中得到了首次应用。与事后精密轨道的比对分析表明,?DOR测量精度在1 ns量级,相当于90 nrad的角位置精度,等价于地月距离上37 m的位置误差。深空干涉测量信号处理中心VLBI软相关处理器有效支撑了CE-3的精密轨道测定。     

Construction Projects of River Crossings and Bay Bridges in China: Achievement,Innovation and Management Practice

Bridges are built to stride over natural obstacles. They are “Key Links” in roadway network. In recent 30 years, with the reform and opening policy, many huge projects of National Expressway Network and river crossings and bay bridges have been built in mainland China, which remark great historic significance and strategic decisions. More than one hundred bridges connecting north and south of China along the Yangtze River, are making the economy and society more integrated than ever. The construction of river crossings and bay bridges is a system integration of both engineering and non-engineering achievements. Through the self-construction practices and along with the "inheritance, development and innovation", Chinese bridge engineering technology has been stepped into the world's advanced levels. Moreover, with the support of the nation's technical strength and application of modern project management method, continues efforts have been made to seek for systematic and integrated management practices, which is more fitted with the specific Chinese conditions. Many valuable experience and lessons has accumulated through the world's largest-scale bridge construction projects. In this paper, the construction achievements of long-span bridges in the Yangtze River Delta Zone have been summarized and reviewed, using methodology of engineering philosophy.