General Seismic Load Distribution for Optimum Performance-Based Design of Shear-Buildings

An optimization method based on uniform damage distribution is used to find optimum design load distribution for seismic design of regular and irregular shear-buildings to achieve minimum structural damage. By using 75 synthetic spectrum-compatible earthquakes, optimum design load distributions are obtained for different performance targets, dynamic characteristics, and site soil classifications. For the same structural weight, optimum designed buildings experience up to 40% less global damage compared to code-based designed buildings. A new general load distribution equation is presented for optimum performance-based seismic design of structures which leads to a more efficient use of structural materials and better seismic performance.     

蛋白酶与表面活性剂对丝织文物上血渍协同清洗条件的优化

丝织文物是研究我国古代刺绣技术和文化艺术发展史的珍贵实物资料,因此丝织文物的保护对中国文物事业具有重要的地位和意义.由于尸体腐烂和墓葬埋藏环境等因素的作用,有些丝织文物表面会被血渍污染,这种污染物紧密黏附在丝织文物的表面且具难溶性不易清洗去除.如何选择合适的清洗方法低机械强度地去除这些血渍成为丝织文物修复的关键.为此,本实验考察了蛋白酶和表面活性剂对丝织文物上血渍进行协同清洗的效果.首先对蛋白酶和表面活性剂进行筛选,然后对蛋白酶和表面活性剂的使用浓度、清洗时间和浸泡温度等参数进行了优化.试验结果表明:最适蛋白酶和表面活性剂分别为Savinase和APG,其最适浓度分别为1%和5%;最适浸泡温度和时间分别为50℃和30min.拉力强度检测和扫描电镜分析表明,此条件清洗后对丝织品的抗拉强度和蚕丝微观形态影响不大.在此基础上,对元代丝织文物残片进行了清洗,效果良好.本研究为丝织文物上血渍的清洗提供了一种新的较温和的清洗方法.     

Multi-Objective Evolutionary Seismic Design with Passive Energy Dissipation Systems

The problem of multi-objective seismic design optimization is examined within the context of passive energy dissipation systems. In particular, a genetic algorithm approach is developed to enable the evaluation of the Pareto front, where maximum inter-story drifts and maximum total accelerations, both important measures for damage, serve as objectives. Here the cost of the passive system is considered as a constraint, although it could be included instead as a third objective. Hysteretic, viscoelastic and viscous dampers are all considered as possible design strategies, as well as the weakening plus damping concept. Since different types of passive systems are included, diversity of the Pareto front becomes a key issue, which is addressed successfully through an innovative definition of fitness. The multi-objective framework enables the evaluation of trade-offs between the two objectives and, consequently, provides vital information for the decision maker. Furthermore, the results presented offer valuable insight into the characteristics of optimal passive designs for the different objectives. Some of these characteristics confirm results reported elsewhere, while others are presented here for the first time.     

An Improved Algorithm for Selecting Ground Motions to Match a Conditional Spectrum

This paper describes an algorithm to efficiently select ground motions from a database while matching a target mean, variance, and correlations of response spectral values at a range of periods. The approach improves an earlier algorithm by Jayaram et al. [2011]. Key steps in the process are to screen a ground motion database for suitable motions, statistically simulate response spectra from a target distribution, find motions whose spectra match each statistically simulated response spectrum, and then perform an optimization to further improve the consistency of the selected motions with the target distribution. These steps are discussed in detail, and the computational expense of the algorithm is evaluated. A brief example selection exercise is performed, to illustrate the type of results that can be obtained. Source code for the algorithm has been provided, along with metadata for several popular databases of recorded and simulated ground motions, which should facilitate a variety of exploratory and research studies.     

三峡库区工业空间组织结构的调整与优化

本文认为三峡库区工业空间组织结构的调整与优化是库区整个工业结构调整的重要组成部分。三峡库区工业的空间组织结构调整必须与长江产业带建设、三峡经济区生产力总体布局以及库区的城镇体系建设相协调,在优化库区工业经济空间布局过程中应该以库区工业企业迁建为契机,把工业布局优化同城镇搬迁、基础设施建设相结合。库区工业组织结构调整与优化整体思路可以概括为:"两头牵动、中间布点、形成三区、主轴衔接、由线而面、双向拓展"。最后提出了相应的保障措施。