基于局部模糊逻辑系统合成的一类非线性不确定系统自适应控制

通过使用从属于系统状态区域上开覆盖的单位分解,首先将若干个局部生成的模糊逻辑系统合成而产生一种函数逼近器,与通常的模糊逻辑系统相比较,这种逼近器不仅具有万能逼近性质,而且由于局部模糊逻辑系统具有较少规则而能够保持语言可解释性;然后,通过将适当的参数植入这种函数逼近器中,能够为某些非线性不确定系统设计自适应镇定控制器;最后,通过仿真例子验证了所提出方法的有效性.     

改进的无网格伽辽金方法及其在三维金属体积成形中的应用研究

针对传统无网格伽辽金方法(EFGM)在构造形函数时,矩阵A容易出现不可逆的弊端,采用带权正交基函数构造形函数,在积分方案上采用单位分解积分方法,从而实现了真正的"无网格"。将改进的EFGM与刚(粘)塑性流动理论相结合,建立了改进的刚(粘)塑性无网格伽辽金方法,自主开发了金属体积成形过程无网格伽辽金方法分析程序。通过对三维金属体积成形工艺算例的数值模拟分析,及与有限元软件分析结果的比较,验证了所建立方法的正确性。     

太阳能热水器与建筑的有机结合

介绍了太阳能热水器与建筑设计的结合及其在未来建筑中的重要性。     

基于激光扫描的隧道超欠挖量检测方法

隧道超欠挖检测是爆破成型质量评估的重要内容,对保障施工安全极为重要.针对施工过程的爆破隧道截面特点,提出了基于激光扫描的隧道超欠挖量检测方法.以二维激光扫描仪和车载云台为主搭建三维扫描装置,利用该装置通过多点设站采集整个隧道的三维点云数据并将其转换到同一大地坐标系下,计算隧道中轴线并提取隧道截面,检测隧道截面的超挖区域...     

齿轮泵马达一体机理论研究

齿轮泵马达一体机是将齿轮泵和马达做成一体的一种新的液压系统,在泵和马达之间安装调速阀或者将马达设计成变量马达来控制马达的转速和旋转方向。通过改变中间壳体的形状改变输入轴和输出轴角度的变化。简要介绍了其工作原理并证明了其理论上的可行性,为泵马达一体机的设计和选用提供了理论依据。     

仿古也应有个性——藉大唐贡茶院设计而论

仿古有独创个性,加倍难。但可能:一是个性源于内涵,外化为形式。二是古今一体,恰因其难倒添个性。三是乡土化,不抄袭他处同时代先例。四为民间野趣中又含皇家礼仪。五是亟需提高社会对设计创新的尊重,不改变为一般化。     

Evolving Patterns: Correlated Systems of Interaction

Over the last four decades, the onset of computation has enabled architects and designers to employ generative patterns in their exploration of emergent social, material and spatial systems. Theodore Spyropoulos provides an overview of the field and discusses how it has been developed by the Design Research Lab (DRL) at the Architectural Association into an ‘Adaptive Ecologies’ agenda. In the context of parametric urbanism, the DRL has explored models of living through behavioural patterns found in nature, examining the role of the singular and the collective. Copyright © 2009 John Wiley & Sons, Ltd.     

A partition of unity‐based ‘FE–Meshfree’ QUAD4 element for geometric non‐linear analysis

The recently published ‘FE–Meshfree’ QUAD4 element is extended to geometrical non‐linear analysis. The shape functions for this element are obtained by combining meshfree and finite element shape functions. The concept of partition of unity (PU) is employed for the purpose. The new shape functions inherit their higher order completeness properties from the meshfree shape functions and the mesh‐distortion tolerant compatibility properties from the finite element (FE) shape functions. Updated Lagrangian formulation is adopted for the non‐linear solution. Several numerical example problems are solved and the performance of the element is compared with that of the well‐known Q4, QM6 and Q8 elements. The results show that, for regular meshes, the performance of the element is comparable to that of QM6 and Q8 elements, and superior to that of Q4 element. For distorted meshes, the present element has better mesh‐distortion tolerance than Q4, QM6 and Q8 elements. Copyright © 2009 John Wiley & Sons, Ltd.     

The extended/generalized finite element method: An overview of the method and its applications

An overview of the extended/generalized finite element method (GEFM/XFEM) with emphasis on methodological issues is presented. This method enables the accurate approximation of solutions that involve jumps, kinks, singularities, and other locally non‐smooth features within elements. This is achieved by enriching the polynomial approximation space of the classical finite element method. The GEFM/XFEM has shown its potential in a variety of applications that involve non‐smooth solutions near interfaces: Among them are the simulation of cracks, shear bands, dislocations, solidification, and multi‐field problems. Copyright © 2010 John Wiley & Sons, Ltd.     

A partition of unity FEM for time‐dependent diffusion problems using multiple enrichment functions

An enriched partition of unity FEM is developed to solve time‐dependent diffusion problems. In the present formulation, multiple exponential functions describing the spatial and temporal diffusion decay are embedded in the finite element approximation space. The resulting enrichment is in the form of a local asymptotic expansion. Unlike previous works in this area where the enrichment must be updated at each time step, here, the temporal decay in the solution is embedded in the asymptotic expansion. Thus, the system matrix that is evaluated at the first time step may be decomposed and retained for every next time step by just updating the right‐hand side of the linear system of equations. The advantage is a significant saving in the computational effort where, previously, the linear system must be reevaluated and resolved at every time step. In comparison with the traditional finite element analysis with p‐version refinements, the present approach is much simpler, more efficient, and yields more accurate solutions for a prescribed number of DoFs. Numerical results are presented for a transient diffusion equation with known analytical solution. The performance of the method is analyzed on two applications: the transient heat equation with a single source and the transient heat equation with multiple sources. The aim of such a method compared with the classical FEM is to solve time‐dependent diffusion applications efficiently and with an appropriate level of accuracy. Copyright © 2012 John Wiley & Sons, Ltd.