基于单自由度振动模型的IIR数字滤波器设计

无限冲击响应(IIR)数字滤波器设计通常需要先设计S域滤波器,再变换到Z域。为简化IIR数字滤波器的设计过程,本文提出利用单自由度系统(SDOF)模型直接设计IIR数字滤波器的方法,包括低通、带通、高通、带阻等。仿真结果表明设计过程直接、简单,滤波器参数不需要随采样频率而变,具有良好特性,是一种设计IIR数字滤波器的简便易用的新方法。     

Offshore wind turbine blades measurement using Coherent Laser Radar

To maximize aerodynamic efficiency, large-scale offshore wind turbine blades require inspection during the production stage to ensure strict tolerance requirements are met. During production, the blade is fixed at the root, restricting movement in the Z direction. X, Y, Rx, Ry and Rz remain unconstrained causing blade flex due to gravity. This deforms the blade away from the theoretical CAD blade location, causing measurement results that do not accurately represent the blade profile. Measurement error can be minimized using rigorous B-spline data alignment. Such alignment compensates for blade flex by varying the constrained Degrees of Freedom (DoF), and provides manufacturers with confidence in the design process. This paper used Coherent Laser Radar and Spatial Analyzer to establish the optimal constrained DoF variation, giving the most accurate data alignment solution. Of the constraints investigated, the optimal data transformation solution was found with a double B-spline alignment method, whilst constraining movement in Y, Z and Ry.     

Mathew & Ghosh Architects

The work of Mathew & Ghosh Architects (Nisha Mathew-Ghosh and Soumitro Ghosh) boldly extends an abstract Modernist language and at the same time draws from the vitality of places. While the firm's early works were small in scale, mostly residential in nature and based on a reappraisal of the early Corbusian idiom, recent projects include large-scale urban and landscape interventions with diverse conceptual and metaphorical imperatives. They have moved from a more reticent stance to the urban exuberance of their more recent projects (for example, their own office building), something akin to a ‘savage architecture’ as posited by Kazuo Shinohara in the context of the unsynchronised nature of the modern city. The architects' object of contemplation is the urban ‘box’, whether a private residence, office or part of a church. The box is first fractured and reconstructed as a bricolage of tectonic fragments, memories and events, all tenuously related as if unity in a contemporary culture is for ever denied. Like the Japanese notion of ‘ma’, the moment between fragments - a slit or an emptiness between two hovering planes - is telling. Mathew & Ghosh participate in the continuity of a historical narrative yet mark out the fissures and disjunctions; sometimes negotiations with the continuity emerge from unintended interstices. While these configurations of the contemporary urban ‘box’ are both contextual and abstract, they are also phenomenologically rich. There is a sustained dialect to the architecture of Mathew & Ghosh that includes consummate materiality and fine crafting, light as a medium, and always, as Nisha Mathew-Ghosh states, ‘good spatial possibilities’. Copyright © 2007 John Wiley & Sons, Ltd.     

Exit Ltd

For London-based editor, author and curator Shumon Basar , The Temple of Janus Revisited by Exit Ltd is an effective critique of post-9/11 politics and culture. A virtual re-enactment of the Roman Temple of Janus in Washington DC, it evokes the imminent collapse of the American Empire. Copyright © 2009 John Wiley & Sons, Ltd.     

物流仓库取送货工业机器人教学设备设计

介绍物流仓库取送货工业机器人教学设备的总体方案、结构设计及液压传动设计等内容 ,为实训教学提供条件 ,给学生创新思维创造良好的环境 ,培养学生正确设计PLC控制系统和液压传动系统的调整、故障排除等技能。     

3-RRR球面并联机构的工作空间分析及结构优化

根据Kutzbach-Grübler修正公式分析了球面3-RRR并联机构的自由度个数以及性质,采用哈密顿"四元数"对关节矢量进行描述并建立了逆运动学数学模型,找出了动平台运动时连杆之间、连杆与电机主轴相互之间的碰撞干涉条件。根据运动学逆解以及碰撞干涉条件,基于Mathematica软件完成了可达工作空间的分析,绘制了球面并联机构的工作空间形状,给出了工作空间的极限位置。以工作空间的最大化为目标对并联机构进行了结构优化设计,使动平台实现了完整的球面工作空间。     

基于MATLAB多自由度单向串联振动系统的计算分析

在工程振动问题中,固有特性(固有频率和主振型)是描述振动系统的主要参数。根据矩阵迭代法,利用MATLAB/GUI界面设计平台,提出了针对多自由度单向串联振动系统固有特性的计算方法,并通过算例求解和误差分析,完成了合理性验证,为复杂振动系统响应的初步解耦奠定了基础。     

自由球冲击接触下管形体失效特征仿真分析

基于冲头与自由圆管碰撞过程的高度非线性,采用非线性显式有限元分析法对其进行了仿真计算.分析了圆管所受冲击力的时间历程曲线和圆管的变形情况;探讨了在不同速度下,冲头质量、管径厚比对圆管变形的影响.同时也分析了冲头对圆管碰撞时,导致圆管由弹性变形向塑性变形转化学的临界速度值.     

邻接矩阵在平面机构分析中的应用

研究了邻接矩阵在平面机构自由度计算、同构识别和速度瞬心求解中的应用。揭示了邻接矩阵与机构自由度的关系。给出了同构运动链邻接矩阵的特征向量及特征值关系的充要条件 ,据此提出了识别机构运动链同构的方法。最后 ,提出了应用邻接矩阵自乘求解机构全部瞬心及求解给定瞬心最短路经的方法     

消逝的过程：“时间维度”视角下的建造技术培训与工艺创新

本文以近代建造学教科书及其所反映的相关建造技术培训为切入点,关注19世纪末20世纪初中英比较视野下的中国建造与思想的转变。分析中英近代建造学学科的教学法特征,讨论建造技术培训中关于模具、拱顶支架、脚手架、建造流程等施工过程的呈现与隐藏,进而管窥中国近代建筑史中"消逝的过程"以及其历时性与共时性的现象。在此基础上,探讨“儒与匠”“思想与建造”两组相关词的含义区别,分析中国近代建造技术教育转型中的技术工人的工艺自由及其利弊,并进一步探索"实现目的"与"创造目的"两种层面的工艺创新及其意义。