Algorithmically imposed thermodynamic compliance for material models in mechanical simulations using the AIM method

Thermodynamic irreversibility can be imposed on empirical material behaviour by using an appropriate algorithm which takes the path‐dependence of the degradation process into account. This new algorithm, Algorithmically Imposed Mechanics (AIM), for algorithmically irreversible mechanics, is described, and the convergence and unicity of the solutions obtained are proven. AIM is applicable to a range of mechanical behaviour and is demonstrated to work in conjunction with non‐local damage with rotating cracks as well as a mixed plastic and damage behaviour. Copyright © 2015 John Wiley & Sons, Ltd.     

Constrained pseudo‐transient continuation

This paper addresses the problem of finding a stationary point of a nonlinear dynamical system whose state variables are under inequality constraints. Systems of this type often arise from the discretization of PDEs that model physical phenomena (e.g., fluid dynamics) in which the state variables are under realizability constraints (e.g., positive pressure and density). We start from the popular pseudo‐transient continuation method and augment it with nonlinear inequality constraints. The constraint handling technique does not help in situations where no steady‐state solution exists, for example, because of an under‐resolved discretization of PDEs. However, an often overlooked situation is one in which the steady‐state solution exists but cannot be reached by the solver, which typically fails because of the violation of constraints, that is, a non‐physical state error during state iterations. This is the shortcoming that we address by incorporating physical realizability constraints into the solution path from the initial condition to steady state. Although we focus on the DG method applied to fluid dynamics, our technique relies only on implicit time marching and hence can be extended to other spatial discretizations and other physics problems. We analyze the sensitivity of the method to a range of input parameters and present results for compressible turbulent flows that show that the constrained method is significantly more robust than a standard unconstrained method while on par in terms of cost. Copyright © 2015 John Wiley & Sons, Ltd.     

激光陀螺捷联惯导尺寸效应误差分析与补偿

在高动态条件下,加速度计尺寸效应已成为影响激光陀螺捷联惯导系统精度的重要误差源.文中从理论上分析了尺寸效应的产生机理,认为尺寸效应的产生是由于加速度计测量点不一致而引起,分析了激光陀螺机械抖动引起的尺寸效应误差.对加速度计组件在一般安装关系下的尺寸效应误差模型进行了推导.对于加速度计非正交安装情形,在常规静态标定模型基础上,推导了考虑尺寸效应后的动态标定模型.以导航速度为观测量,建立了加计组件尺寸效应误差补偿的一般模型方程.一系列的试验证明,尺寸效应补偿有效地提高了导航精度.     

曲线光顺在惯导平台自标定中的应用

提出了一种新的惯导平台自标定数据处理方法——曲线光顺法。根据自标定数据特点给出了适于自标定数据的曲线光顺准则。分析了野值对曲线二阶差商的影响规律,提出了一种野值剔除算法。通过将最小二乘与B样条结合得出二阶差商参考值,并使实际差商与参考差商距离达到最小从而得到野值修改值。实验结果表明,该文的算法能很好地解决惯导平台自标定数据的野值剔除问题,可通过调节参数来控制光顺精度,并具有算法简便、易于操作的优点。     

特种物品储运记录仪的设计与研究

特殊物品储运记录仪是能够对车辆行驶速度、路线进行记录存储,并通过惯性器件自主导航的智能装置。以往的储运设备只能粗略记录物品受冲击力的状况,针对这一问题,提出一种基于惯性导航系统的储运记录仪。实验结果表明,设计的基于MEMS器件的捷联式惯性导航系统能够输出满足要求的载体瞬时速度、加速度、姿态、位置等,可以明显加强危险品、敏感材料的运输监控力度。     

Generative methods in urban design: a progress assessment

The year 2007 marked the 20‐year anniversary of A New Theory of Urban Design (1987), a slender volume by Christopher Alexander and colleagues that serves as a notable milepost within the half‐century old “design methods movement” in which Alexander himself played a seminal role. The “generative” design method of A New Theory focused less upon the specification of a final form through schematic planning, and more on the stepwise process by which a form might emerge from the evolutionary actions of a group of collaborators. In so doing, it challenged the notion of “design” as a progressive expression of schematic intentions, and argued for a conception of design as a stepwise, non‐linear evolution in response to a series of contextual urban factors. In the 20 years since, significant progress has been made to develop the insights of generativity in urban design, as in other fields. Some of Alexander’s ideas have been incorporated – notably by practitioners of The New Urbanism – and some have been challenged and dismissed, including, notably, by Alexander himself. The author assesses progress since this milepost volume – substantial, he argues – as well as setbacks and shortcomings, and significant opportunities still remaining.     

考虑随机风压场非高斯特性的大跨度膜屋盖风振响应

作用于大跨度膜屋盖结构上的随机风压场在统计意义上由高斯和非高斯区域构成。基于零记忆非线性转化法理论,提出了这种混合随机风压场的模拟方法,算例表明,生成的随机风压场样本能准确描述实验数据的各项统计特性。将生成的样本和利用传统方法生成的高斯随机风压样本作用于某膜屋盖结构,经风振时域分析后发现,高斯随机风压激励下结构部分构件的响应值比非高斯随机风压激励下的响应值低,这表明,随机风压荷载的非高斯特性不容忽视。文章还给出了结构不同构件的整体风振响应系数。     

Kernel regression for real-time building energy analysis

This study proposes a new technique for real-time building energy modelling and event detection using kernel regression. We show that this technique can exceed the performance of conventional neural network algorithms, and do so by a large margin when the available training dataset is small. Furthermore, unlike the synapse weights in a neural network, the parameters of our kernel regression models are amenable to human interpretation and can give useful information about the building being studied. We extensively test our proposed algorithms using a new dataset consisting of 1.5 years of power and environmental measurements for four buildings, in addition to benchmarking against the ASHRAE Predictor Shootout dataset. On the new dataset, our kernel regression algorithm gave the best prediction performance in three of four cases and significantly outperformed neural networks (the nearest competitor) with training sets of 1/2 a year or less.     

宜兴大酒店装修改造“设计施工一体化”应用与研究分析

本文以宜兴大酒店装修改造为例,探析了＂设计施工一体化＂如何让酒店改造重新装修旧貌换新颜,如何把原来中规中矩、缺少格局变化的旧商务大楼规划成为配套设施完善,环境宜人的宾馆区。这对设计者来说是很大的挑战,也是十分值得探索的课题。     

建筑外墙体保温技术及质量控制研究

建筑的外墙体保温技术作为新世纪建筑水平的新标志,不仅关系到建筑工艺的发展问题,同时也与节约能耗、增加住房使用面积等民生问题息息相关。本文就对建筑外墙体的保温技术问题及质量控制方面给出了一些建议和看法。