Environmental contours for circular‐linear variables based on the direct sampling method

Environmental contours are often used in the design of engineering structures to identify extreme environmental conditions that may give rise to extreme loads and responses. The perhaps most common application of environmental contours is for wave climate variables such as significant wave height and wave period. However, for the design of wind energy installations, the joint distribution of wind speed and wind direction may be equally important. In this case, joint modelling of linear (wind speed) and circular (wind direction) variables are needed, and methods for establishing environmental contours for circular‐linear variables will be required. In this paper, different ways of establishing environmental contours for circular‐linear variables will be presented and applied to a joint distribution model for wind speed and wind direction. In particular, the direct sampling approach to environmental contours will be modified to the case where one of the variables is cyclic. In addition, contours based on exceedance planes in polar coordinates will be established, and circular‐linear contours will also be calculated based on the inverse FORM (I‐FORM) approach.     

盛德大厦改建工程抗震性能研究

针对广州盛德大厦改建设计后的结构进行抗震性能研究。要求改建设计后的结构满足现行结构规范,故对原已建部分承载力复核并采取相应的加强改造措施,以确保其有足够的抗震能力。改建后的结构设计采用基于性能的抗震设计方法,包括小震弹性计算、中震弹性以及中震不屈服构件验算,以及罕遇地震下的弹塑性分析。利用ETABS和PERFORM-3D分析软件进行了整体结构弹性及弹塑性时程分析和推覆分析,并运用多种分析手段验证不同地震作用下结构的抗震性能,最后校核了桩基础在地震作用下的承载力。     

Active contours: Generalization of the snake mode

Abstract— Segmentation is one of the fundamental issues in the field of image processing and computer vision. Various approaches include differentiating an object in the image as a final goal or for further processing (medical diagnosis, surveillance, 3‐D reconstruction and more). Snakes, a model proposed by Kass, Witkin, and Terzopoulos in 1987, provides an efficient method for segmenting an object through the minimization of its energy. The advantage of snakes is in its ability to use high‐level data given by the algorithm operator, as opposed to other methods such as the Laplace technique. The snakes model inherently imposes strong constraints on a given image in order to successfully segment an object. In this paper, the use of adjustment methods is described, which allow us to generalize the snake model to a wider range of applications. Through the use of pre‐processing techniques, the model's constraints were softened. The main theoretical model and its use in facing a real life image is presented.     

基于TTF技术的UG刻字工具开发

在模具设计中,常需在零件上刻编号、铭牌等信息,以便标识和装配,手工处理繁琐费时.通过对TTF字符轮廓描述模型进行分析研究,并利用轮廓并运算处理算法,对字符原始轮廓信息进行加工,获取三维造型所需的封闭并无自相交的曲线.在UG三维设计软件平台上,利用UG/Open API开发出刻字工具,以解决零件刻字的效率问题.该工具支持用户自定义属性、自动生成字符槽特征,对镶块、顶针等有规则的零件具有批量刻字功能.     

关于灌区末级渠系工程改造的思考

末级渠系（包括斗、农渠系）改造是灌区建设的重要组成部分，群管渠系体系的管理水平直接关系着灌区工程效益的正常发挥。文中对灌区末级渠系工程的建设和管理现状进行探讨，结合末级渠系改造试点地区效益分析，提出了灌区末级渠系建设组织形式、工程规划、设计以及工程造价控制等方面的若干建议。     

中子输运方程的源项反演问题

本文讨论了中子输运方程的解的存在性.使用有限元方法求解中子输运方程,并使用Landweber方法求解源项反演问题.给出了算法和数值模拟结果,验证了算法的有效性.     

最速下降线及其自动查找

对坡降线作了深入具体的研究,给出了其微分方程形式及在离散情况下的近似表达;给出了坡降线自动生成的一种算法,并对其中的一系列理论和计算问题进行了探讨。     

A comparison of stochastic process models for definition of design contours

So-called design contour methods are frequently applied for large and complex structures in order to minimize the number of time-consuming structural analyses. These methods are based on first identifying extreme environmental conditions with a given probability of exceedance based on the relevant joint distribution function. These conditions are located along a level surface (i.e. “contour”) in the space of load parameters. As the second step, response analyses are performed for a selection of extreme conditions which are located along this contour. The highest response level which is obtained as a result of these analyses is then applied for design purposes.This approach is based on a representation of the underlying stochastic processes in terms of a sequence of piecewise constant levels. In the present paper, the extreme environmental conditions which are obtained based on such a model are compared to those obtained by instead applying a continuous process model. Furthermore, various alternative and relevant definitions of design contours are compared for the two-component case.In the present analysis, mainly stochastic processes which represent load parameters are considered. However, the approach for identification of level surfaces is of a general nature and can be applied to any types of random vector processes.     

北京某医院住院楼钢结构增层设计

以北京某医院住院楼钢结构增层为背景，对钢筋混凝土结构上加建钢结构楼层的复合结构的计算方法进行了探讨，着重介绍了复合结构阻尼比的确定方法，以保证钠结构的安全性。