小型远程办公网络设计与实施

本文针对小型远程办公网络的连接与集成提出了两种设计方案,并对其进行了比较分析,有效地利用成熟网络技术来提高通讯效率并且降低了运营成本,同时涉及了对网络安全性的考虑,本文利用宇翔科技有限公司的网络设计为实例进行了探讨.     

基于图论的无线传感器网络自组织性能研究

无线传感器网络自组织问题越来越受到人们的关注,控制方法也大量涌现,但在对自组织性能的评价上,现在大多仍停留在定性分析阶段。本文针对无线传感器网络自组织中连接和覆盖两个重要指标,利用Delaunay三角剖分评价节点实体和他们的关系以及结点之间的信息传递和融合;利用Voronoi图进行评价节点覆盖的区域;同时,对整个自组织过程,引用自组织度的概念对其分布效果进行定量分析。仿真结果表明,我们提出的性能分析方法能够很好地评价无线传感器网络自组织算法的优劣。     

浅谈Windows Media在远程教学中的应用

本文就远程教学中出现的流媒体技术做了简要说明,并对Windows Media软件中包含的3个组件进行了重点说明。对利用该组件进行课件采集、制作,Media服务器配置,Media Player功能等做了详细介绍,同时也描述了Windows Media的发展前景。     

On Controllability of Switched Linear Systems

This paper investigates the number of switchings and design of switching sequences for controllability of switched linear systems. Two related results are established. One is a new constructive approach to designing switching sequences. The controllable state set of each switching sequence designed via the approach coincides with the controllable subspace of switched linear systems. The other is a well-estimated value for the minimum number of switchings required for controllability. Each state in the controllable subspace can be steered to origin within this value of switching times.     

An application of MODIS data to snow cover monitoring in a pastoral area: A case study in Northern Xinjiang, China

Snow is an important land cover on the earth's surface. It is characterized by its changing nature. Monitoring snow cover extent plays a significant role in dynamic studies and prevention of snow-caused disasters in pastoral areas. Using NASA EOS Terra/MODIS snow cover products and in situ observation data during the four snow seasons from November 1 to March 31 of year 2001 to 2005 in northern Xinjiang area, the accuracy of MODIS snow cover mapping algorithm under varied snow depth and land cover types was analyzed. The overall accuracy of MODIS daily snow cover mapping algorithm in clear sky condition is high at 98.5%; snow agreement reaches 98.2%, and ranges from 77.8% to 100% over the 4-year period for individual sites. Snow depth (SD) is one of the major factors affecting the accuracy of MODIS snow cover maps. MODIS does not identify any snow for SD less than 0.5 cm. The overall accuracy increases with snow depth if SD is equal to or greater than 3 cm, and decreases for SD below 3 cm. Land cover has an important influence in the accuracy of MODIS snow cover maps. The use of MOD10A1 snow cover products is severely affected by cloud cover. The 8-day composite products of MOD10A2 can effectively minimize the effect of cloud cover in most cases. Cloud cover in excess of 10% occurs on 99% of the MOD10A1 products and 14.7% of the MOD10A2 products analyzed during the four snow seasons. User-defined multiple day composite images based on MOD10A1, with flexibilities of selecting composite period, starting and ending date and composite sequence of MOD10A1 products, have an advantage in effectively monitoring snow cover extent for regional snow-caused disasters in pastoral areas.     

GPU-based rendering for deformable translucent objects

In this paper we introduce an approximate image-space approach for real-time rendering of deformable translucent models by flattening the geometry and lighting information of objects into textures to calculate multi-scattering in texture spaces. We decompose the process into two stages, called the gathering and scattering corresponding to the computations for incident and exident irradiance respectively. We derive a simplified illumination model for the gathering of the incident irradiance, which is amenable for deformable models using two auxiliary textures. In the scattering stage, we adopt two modes for efficient accomplishment of the view-dependent scattering. Our approach is implemented by fully exploiting the capabilities of graphics processing units (GPUs). It achieves visually plausible results and real-time frame rates for deformable models on commodity desktop PCs.     

Controllability of multi-agent systems based on agreement protocols

This paper investigates the controllability of multi-agent systems based on agreement protocols. First, for a group of single-integrator agents, the controllability is studied in a unified framework for both networks with leader-following structure and networks with undirected graph. Some new necessary/sufficient conditions for the controllability of networks of single-integrator agents are established. Second, we prove that, under the same topology and same prescribed leaders, a network of high-order dynamic agents is completely controllable if and only if so is a network of single-integrator agents. Third, how the selection of leaders and the coupling weights of graphs affect the controllability is analyzed. Finally, some numerical simulations are presented to demonstrate the effectiveness of the theoretical results.     

基于FPGA的二维提升小波变换IP核设计

提出了一种高效并行的二维离散提升小波(DWT)变换结构,该结构只需要7行教据缓存,即可实现行和列方向同时进行滤波变换.采用一种基于CSD编码和优化的移位加操作实现常系数乘法器,整个小波变换插入多级流水线寄存器,加快了处理速度.用VHDL设计可自动验证的testbench,通过matlab+modelsim联合仿真能方便有效地对IP核进行验证.此IP核具有3个可配置参数,分别为图像尺寸、位宽、小波变换的级数,可方便重用.该IP核已经在XC2VP20 FPGA上实现,并能稳定工作在60MHz时钟频率下,其处理512512 8bil图像的速度可达240帧/s,完全能满足高速图像实时处理要求.     

基于MVC的振动噪声数据库系统的设计与实现

预期的研究成果是拥有自主知识产权的振动噪声数据库.通过建立这样一个数据信息规模较大、可用性强、开放式的振动噪声数据库,为振动噪声试验工作提供坚实的基础.对系统进行了概要的介绍,提出了一套基于J2EE框架平台的系统解决方案.整个系统采用了MVC设计模式,还采用了Struts、Spring、Hibernate等多种技术,使得系统成为以网络为系统平台,基于B/S结构、具有结构清晰,具有良好的可扩展性、可维护性以及重用性的主题数据库应用系统.     

鲁棒区间类型2可能性C均值聚类

提出了一种鲁棒区间类型2可能性C均值(IT2PCM)聚类规则,其实质是采用交替迭代结构进行聚类的交替类估计,但隶属度函数通过区间类型2模糊集合来选择.在提出的方法中,类原型的更新方程通过将降型与解模糊相结合的形式来计算.在鲁棒统计的框架下,通过φ函数的分析指出这种更新方程对类内不确定的模式以及野点具有鲁棒性.最后,与现有的鲁棒聚类规则进行比较.仿真结果说明了IT2PCM良好的鲁棒性.