住宅浸水监视自动报警系统的研制

介绍一种用于家庭住宅发生浸水灾情时的自动报警装置．该报警装置可在住宅发生浸水灾情时，自动通过电话线拨打灾情报警电话．从而避免由于浸水给家庭造成的巨大经济损失．文中给出了相应的水浸探测器、单片机与调制解调器硬件电路及电话报警程序。     

Cost-based cache replacement and server selection for multimedia proxy across wireless Internet

Multimedia proxy plays an important role in multimedia streaming over wireless Internet. Since wireless network exhibits different characteristics from the Internet, multimedia proxy caching over wireless Internet faces additional challenges. In this paper, we present a study of cache replacement for a single server and server selection for multiple servers across wireless Internet. By considering multiple objectives of multimedia proxy, we design a unified cost metric to measure proxy performance in wireless Internet. Based on the defined unified cost metric, we propose a novel replacement algorithm for single-server and a new server-selection policy for multiple servers to improve the end-to-end performance such as throughput, media quality, and start-up latency. To effectively handle errors occurred on wireless link, channel-adaptive unequal error protection is deployed according to distinct quality of service requirements of layered or scalable media. Simulation results demonstrate that our approaches achieve significantly better performance than the known cache-replacement algorithms and sever selection schemes, respectively.     

Keeping smart, omnidirectional eyes on you [adaptive panoramic stereovision]

An adaptive panoramic stereo approach for two cooperative mobile platform is presented. There are four key features in the approach: 1) omnidirectional stereovision with an appropriate vertical FOV, and a simple camera calibration method; 2) cooperative mobile platforms for mutual dynamic calibration and best view planning; 3) 3D matching after meaningful object (human subject) extraction; and 4) real-time performance. The integration of omnidirectional vision with mutual awareness and dynamic calibration strategies allows intelligent cooperation between visual agents. This provides an effective way to solve the problems of limited resources, view planning, occlusion, and motion detection of movable robotic platforms. Experiments have shown that this approach is quite promising.     

Analysis,simulation and verification of a bipolar current source power resonant inverter

A high‐frequency bipolar current source resonant inverter introduced in this paper has dramatic zero‐voltage‐switching (ZVS) characteristic. The analytic expressions of the resonant voltage and current are given. It indicates that the resonant waveform is composed of two parts, i.e. the oscillatory component and the stationary component. In special cases, the resonant waveform degenerates into the mono‐frequency component, as presents the graceful sinusoidal wave with very low total harmonic distortion (THD) value. Based on the closed‐form voltage and current, the component stresses on reactive elements are obtained. The impact of different component values and operating frequencies on ZVS feature is also discussed. It should be noted that the ZVS merit may be lost if the components are carelessly selected. The validity of the theoretical analysis has been proven with Pspice simulations and experimental results. Copyright © 2004 John Wiley Sons, Ltd.     

电影数字化发展的多维性研究

数字技术发展日新月异 ,传统电影的制作、传播方式正在经历自它诞生以来迄今未遇的全方位挑战。现今 ,技术和艺术、传统和时尚的对立与统一等诸多审美特性 ,在一种看似彼此缺少逻辑联系的过程中 ,正奇特地交织于电影实践中。电影数字化发展改变了传统电影的观念、理论 ,带来了市场变化 ,推动了电影制作的变革。电影数字化发展的多维性将随着数字技术进步而不断显现出来。     

数字技术对好莱坞电影视觉效果的影响(一)

20世纪 70年代以来 ,信息技术飞速发展 ,其中 ,数字图像处理技术逐渐成为影视特技、电子游戏、互联网视频信息处理技术中的一个重要的组成部分 ,其应用领域不断拓宽 ,改变了电影行业的整个制作和传播流程。数字电影制作技术由于其高效、丰富、快捷、无损、廉价的特点 ,在国际上得到了空前高速的发展。好莱坞作为世界电影制作的最前沿 ,也是展示美国高科技力量的舞台 ,其电影产品对数字影像技术应用的能力以及所诞生出来的优秀作品的艺术成就在世界上名列前茅。正是因为数字技术具有传统技术所不可能达到的能力和优势 ,现在它已经发展成为发…     

Effect of AlP master alloy on grain refinement of primary silicon in eutectic Al-Si alloys

To obtain the finer primary silicon crystals, the proprietary Al-P master alloy was adopted to modify the eutectic Al-Si alloys and the most suitable modification process was made in the experiments. The SEM (Scanning Electron Microscope) and DSC (Differential Scanning Calorimeter) analysis indicate that the Al-P modifier has more advantages over Cu-P and Fe-P modifier in easily addition, no elemental alteration and less undercooling of primary silicon′s solidification, which suggests the Al-P master alloy is an effective modifier of eutectic Al-Si alloys.     

电磁轴承失效后转子在坠落过程中的动力学特性

用有限元法建立了由滚动轴承组成的备用轴承-电磁轴承-转子系统在电磁轴承失效前后的动力学方程,分析了电磁轴承失效后转子在坠落过程中的动力特性,讨论了备用轴承的支撑阻尼对转子在坠落过程中动力特性的影响.     

高强配筋砼砌块剪力墙非线性动力分析

本提出了配筋砼砌块剪力墙非线性动力分析有限元模型。采用Newmark和Newton-Raphson相结合的方法，利用编制的程序对配筋砌快剪力墙的非线性地震反应进行了分析。分析中考虑了不同地震波、不同填芯率和不同高宽比等因素的影响。研究发现，不同地震波引起地震反应不同；当其它参数一定时，适当提高填芯率将对结构抗震有利。