Characterization of best Chebychev approximation using the frequency response of IIR digital filters with convex stability

This paper deals with the application of Chebychevʼs approximation theory to IIR digital filter frequency response (FR) approximation. It explores the properties of the frequency response of IIR digital filters as a nonlinear complex approximating function; IIR digital filter frequency response is used to approximate a prescribed magnitude and phase responses. The approximation problem is closely related to optimization. If the set of approximating functions is non-convex, the optimization problem is difficult and may converge to a local minimum. The main results presented in the paper are proposing a convex stability domain by introducing a condition termed “sign condition” and characterization of the best approximation by the Global Kolmogorovʼs Criterion (GKC). The Global Kolmogorovʼs Criteria is shown to be also a necessary condition for the approximation problem. Finally, it is proved that the best approximation is a global minimum. The sign condition can be incorporated as a constraint in an optimization algorithm.     

基于SMP强度准则的预应力混凝土管桩的挤土效应分析

预应力混凝土管桩在沉桩过程中,将发生挤土效应和土塞效应,二者是有机统一的。基于SMP强度准则,考虑土塞效应,分析了预应力混凝土管桩的挤土效应及土塞效应,并推导了预应力混凝土管桩的应力场及位移场的计算公式。通过实例表明,基于考虑中间主应力的SMP强度准则推导得到的预应力混凝土管桩的应力状态及位移场的计算公式,在实际工程中具有一定的现实指导意义。     

规划·规范·规则:深圳开发控制三大体系的互动关系

规划、规范和规则是建设项目审批依据的三个基本来源,三者共同构成开发控制管理制度的三大核心体系。研究结合深圳实践,阐述三大体系的特征、构成和分类,分析三者在静态条件下的优先关系和在动态条件下的互动关系,尝试揭示三大体系之间相互替代、补充、促进、转化和融合的演化规律。     

基于应变余能的J积分

本文提出基于应变余能的j积分,证明了j积分回路定义的守恒性,论述了j积分作为弹塑性断裂判据的有效性,同时还提出j积分形变功率定义的表达式。     

电力与环境的协调发展趋势

从电力与环境的关系人手,分析电力生产的环境影响问题及其改善途径。简介日趋严格的国际性环保条约、规定和有关排放标准,以及由此而导致的电力工业生产技术改进与发展趋势。最后展望了我国未来电力与环境协调发展的规划和前景。     

国际信息安全标准热点问题与发展趋势——2006年JTC1/SC27会议追踪

介绍了2006年在西班牙召开的ISO／IECJTC1／SC27T作组会议上重点讨论的ISMS标准族、密码技术标准、信息安全产品测评认证等热点问题，分析了国际信息安全标准的发展趋势，并结合我国信息安全标准化工作，提出了一些工作建议。     

极大熵功率谱估值器的设计和测试

采用极大熵谱估计理论设计估值器，提出了一种基于ＦＰＥ准则改进的估值器定阶方法──加权ＦＰＥ准则。测试结果表明：估值器的频率分辨率和幅值稳定性较高，能满足工程计算的要求。     

Flash Method for the Remote Sensing of the Thermal Diffusivity and the Absorption Coefficient at the Excitation Wavelength of Thin Film Materials

A novel front-face flash-monitoring algorithm for remote sensing of the thermal diffusivity and the absorption coefficient at the excitation wavelength of thin film materials is presented. The method relies on the surface transient temperature vs. time curve initiated by a short-duration heating pulse that is followed by time intervals during which the temperature response depends sensitively on the absorption coefficient and thermal diffusivity. An analytical solution of the problem has been derived to solve the inverse heat-transfer problem and, by comparison with a numerical experiment, to check the accuracy of the proposed algorithm for obtaining the absorption coefficient at the excitation wavelength and thermal diffusivity. The uncertainty of the proposed method is better than 0.1%. Paper presented at the 17th European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

归纳概率解释的研究述评

随着概率论的日趋完善，概率演算已经为人们所熟知，尽管科尔莫哥洛夫（Kolmogorov）公理的经济性可以使我们对概率做出多种解释，但对它的解释却漏洞百出。正因如此，人们主要围绕着概率解释的标准、如何对概率进行合理解释以及概率解释未来的发展的方向3个方面，对这个问题进行了广泛的研究。于是主要从这3个方面分别对这些研究成果进行了述评，借此厘清概率解释理论研究发展的总脉络。     

基于Neyman-Pearson信号消噪方法的改进

本文介绍了运用小波变换进行信号消噪的原理，阐述了基于阈值的正交小波变换消噪法，对运用Neyman-Pearson准则进行阈值选定的方法作了改进，使其适合多尺度分解的小波变换，并将电子测量中的38准则用于对噪声强度的估计运算中，实验证明该种方法取得了较好的实用性。