Recent advances in polymer network liquid crystal spatial light modulators

Polymer network liquid crystal (PNLC) spatial light modulators are attractive for display and photonic applications because they can achieve submillisecond response time while keeping a large phase change. However, their on-state scattering caused by the grain boundary of LC multidomains hinders their applications. In this article, we review recent progress on the development of scattering-free PNLCs extending from short-wavelength infrared to visible region by reducing the domain sizes to ∼200 nm through low temperature curing process. To reduce operation voltage, both transmissive and reflective modes, LC material properties (birefringence and dielectric anisotropy), polymer composition and concentration, and pretilt angle effect are analyzed. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 183–192     

Maximization of Spatial Charge Density: An Approach to Ultrahigh Energy Density of Capacitive Charge Storage

Capacitive energy storage has advantages of high power density, long lifespan, and good safety, but is restricted by low energy density. Inspired by the charge storage mechanism of batteries, a spatial charge density (SCD) maximization strategy is developed to compensate this shortage by densely and neatly packing ionic charges in capacitive materials. A record high SCD (ca. 550 C cm^?3) was achieved by balancing the valance and size of charge‐carrier ions and matching the ion sizes with the pore structure of electrode materials, nearly five times higher than those of conventional ones (ca. 120 C cm^?3). The maximization of SCD was confirmed by Monte Carlo calculations, molecular dynamics simulations, and in situ electrochemical Raman spectroscopy. A full‐cell supercapacitor was further constructed; it delivers an ultrahigh energy density of 165 Wh L^?1 at a power density of 150 WL^?1 and retains 120 Wh L^?1 even at 36 kW L^?1, opening a pathway towards high‐energy‐density capacitive energy storage.     

Influence of nonlinear spatial distribution of stress and strain on solving problems of solid mechanics

Applied Mathematics and Mechanics - The stress and the strain should be defined as statistical variables averaged over the representative volume elements for any real continuum system. It is shown...     

基于并行技术的机载多天线耦合快速算法

分析机载天线间的干扰情况必须首先解决电大尺寸电磁计算问题.首先讨论一种基于空域分解技术及局域网技术的并行数值算法,这种算法将一个电大尺寸散射体表面划分为一系列子域分别进行处理,在求解子域电流的过程中使用了快速多极子技术进行加速运算,然后运用这种算法对机载天线间的耦合进行分析并对算法的性能进行了总结.     

AN EXPLICIT FINITE VOLUME SPATIAL MARCHING METHOD FOR REDUCED NAVIER–STOKES EQUATIONS

This paper develops a spatial marching method for high-speed flows based on a finite volume approach. The method employs the reduced Navier– Stokes equations and a pressure splitting in the streamwise direction based on the Vigneron strategy. For marching from an upstream station to one downstream the modified five-level Runge–Kutta integration scheme due to Jameson and Schmidt is used. In addition, for shock handling and for good convergence properties the method employs a matrix form of the artificial dissipation terms, which has been shown to improve the accuracy of predictions. To achieve a fast rate of convergence, a local time-stepping concept is used. The method retains the time derivative in the governing equations and the solution at every spatial station is obtained in an iterative manner. The developed method is validated against two test cases: (a) supersonic flow past a flat plate; and (b) hypersonic flow past a compression corner involving a strong viscous–inviscid interaction. The computed wall pressure and wall heat transfer coefficients exhibit good general agreement with previous computations by other investigators and with experiments.     

基于TMS320C5402的IP语音通信系统的设计

介绍了基于DSP技术的IP语音通信系统的设计。详细论述了系统结构以及音频接口模块、网络接口模块的设计方法。针对软件结构,给出了G.729语音编码以及UDP传输协议的选择与在TMS320C5402上的实现。     

一种新的移动卫星综合信息网构架

移动卫星综合信息网与现有的移动卫星通信网有着很大的区别。本文提出一种可反映移动卫星综合信息网特点的天基信息综合系统（SI^3）,给出SI^3的网络模型,分析了这种分层网络模型的优缺点,并给出一个具体的参考星座组网例子,最后分析了SI^3建设中面临的技术问题。     

基于固定电话网的中文短信息终端开发

研究了基于固定电话网（PSTN）的采用中文信息终端服务接口通信协议（CTSI）的短消息终（CPE）的软硬件开发。介绍了短信编辑接收系统与信息终端之间数据交换的协议,并以电子订货系统中发送订单为例,描述了信息终端与CTSI服务器之间链路建立、信息交互的整个过程。     

一种基于Zigbee的无线传感器网络教学实验系统

本文首先简要介绍无线传感器网络的体系结构,然后给出一个基于IEEE802．15．4和Zigbee协议的无线传感器网络教学实验系统。该系统中的多个传感器节点可以组成多种不同的拓扑结构,并可以将采集到的数据通过GSM网络发送到用户终端,用户也可以通过GSM网络对远程传感器节点进行控制。该教学实验系统已被许多院校采用,亦可直接应用于其他领域。     

数字指纹及其在视频版权保护中的应用

首先介绍了视频数字的功能和应具有的特征,然后分析了数字指纹的多种编码方案以及指纹协议的演进过程,提出一种数字指纹较实用的系统模型,该模型可用于一些数字作品的版权保护.最后讨论了数字指纹在视频版权保护中的应用.