Leveling the Tilts of a Tenement Building Founded on Loess Soils Prone to Slump-Type Settlement by Regular Wetting

Experience is described for leveling of the tilts of a nine-story tenement building founded on soils prone to slump-type settlement by regular wetting through filtration-weep holes around the building and partially through pits excavated inside the interstitial basement. The leveling was carried out without curtailing the normal service of the building and evacuating its tenants; the building is located in an area classed with an eight-point seismicity.Publicly owned joint-stock company Tsentr Sotsial'noi Ékspertizy     

提升生活排水系统卫生安全性能的关键问题

新冠肺炎确诊患者粪便病毒检测呈阳性,意味着新冠病毒可能会通过气溶胶的方式进行传播,使得生活排水系统的卫生安全问题时隔17年后再次摆在人们面前。以保障人的健康为出发点,从基础研究、排水机理、系统设计、施工监管、维护管理等多方面提出了提升生活排水系统卫生安全性能的关键问题,以期从全生命周期内切断排水系统可能传播病毒的隐形途径,切实保障居民居家健康。     

Local and global searches of approximate optimal designs of regular frames

Methods of local and global searches of approximate optimal designs minimizing total structural volume under stress and displacement constraints are presented for regular frames subjected to static loads. Nonuniqueness of the optimal solution is extensively utilized for local search of approximate optimal solutions, where the search direction is computed from singular value decomposition of the stiffness matrix with respect to the cross‐sectional areas, or the sensitivity matrix of the constraints. The distance between the solutions is then defined, and the approximate optimal solutions are globally and consecutively found so as to maximize the distance from the already found solutions under upper bound constraint on the total structural volume. The effectiveness of the proposed method is demonstrated in application to a plane frame. Copyright © 2005 John Wiley & Sons, Ltd.     

基于分形理论的造型技术

随着分形理论的发展，计算机图形造型技术越来越多地使用到分形技术。介绍了分形的基本概念，以及分形理论在造型技术中的常用模型。     

A Review of the Application of Meta-Heuristic Algorithms to 2D Strip Packing Problems

This paper is a review of the approachesdeveloped to solve 2D packing problems withmeta-heuristic algorithms. As packing tasks arecombinatorial problems with very large searchspaces, the recent literature encourages theuse of meta-heuristic search methods, inparticular genetic algorithms. The objective ofthis paper is to present and categorise thesolution approaches in the literature for 2Dregular and irregular strip packing problems.The focus is hereby on the analysis of themethods involving genetic algorithms. Anoverview of the methods applying othermeta-heuristic algorithms including simulatedannealing, tabu search, and artificial neuralnetworks is also given.     

正弦脉宽调制波通用谐波计算与分析方法

针对采样型正弦脉宽调制(SPWM)技术中几种传统实现方法各有优缺点的问题,特别是在谐波含量这一重要指标上的比较,提出了一种谐波通用计算与分析方法,可作为SPWM新技术研究的辅助工具.基于MATLAB数值计算和傅里叶级数,以不对称规则采样法SPWM波的生成及其谐波计算为例,详细分析了脉宽调制(PWM)波的各次谐波和总谐波...     

SVPWM技术的理论分析及仿真

以电机的基本理论出发，介绍了空间矢量的基本原理。分析了电压型逆变器SVPWM的方法。根据脉宽调制的规则采样法，得出SVPWM隐含调制函数，通过和SPWM调制函数的比较，给出了SVPWM中调制度的计算公式。仿真结果证明了理论分析的正确性。     

一种组合型中点SPWM采样方法的研究

提出一种组合型中点不对称规则采样法,只需在三角载波的波峰(或波谷)进行采样,利用数学中线性组合的原理构造出波谷(或波峰)的“采样点”,再根据二分法的原理求得SPWM波开关点的时刻值。详细阐述了该方法的基本理论,并得出产生SPWM波开关点的运算方程。理论分析与仿真研究表明,与传统的规则采样法相比,该方法的SPWM算法更简单,采样点更少,开关点时刻值的误差和负载电流THD更小,且输出的基波幅值更大。所以,该方法对传统的规则采样法进行了优化,更加逼近了自然采样法的调制效果,易于在DSP上实现,并且运算速度快,具有良好的工程应用价值。     

可编程控制器在工业燃油锅炉控制中的应用

介绍一种用可编程控制器构成的工业燃油锅炉的智能控制器,具体介绍了该控制器的参数分类、报警系统、启燃系统及稳燃系统的功能,硬件构成和这些系统的逻辑设计,以及该智能控制器硬件、软件设计中的几个关键技术问题。图３表１参３