Effect of hysteretic smoothness on inelastic response spectra with constant‐ductility

This paper presents an efficient methodology for computing constant‐ductility inelastic response spectra. The computation of constant‐ductility spectra involves numerical root‐finding algorithms to find the strongest structure providing a desired ductility response. Smooth inelastic structural behavior is modeled using a first‐order nonlinear differential equation and the transient structural response is solved using an implicit algorithm requiring Newton iterations at each time step. For structural models with smooth hysteretic behavior (not piece‐wise linear), a simple root‐finding method involving a combination of hyperbolic fits, linear interpolation, and Newton's method converges upon the highest strength (conservative) solution with a small number of iterations. The effect of the hysteretic smoothness on the occurrence of multiple roots is examined for two near‐fault and two far‐fault earthquake records, and for two measures of ductility and for normalized hysteretic energy. The results indicate how the smoothness of the hysteretic behavior affects ductility demand and constant‐ductility response spectra. Copyright © 2010 John Wiley & Sons, Ltd.     

基于Harris兴趣值的影像线特征高精度提取方法

针对影像高精度线特征提取问题,本文提出一种基于Harris兴趣值的直线提取方法:利用EDISON算法提取影像的初始边缘,并将其细化到单像素,对提取的每一边缘点在其法线方向进行基于Harris兴趣值的子像素定位,并将精确定位后的点拟合成直线.通过采用两幅真实影像进行试验,证实了本文所提方法的有效性.     

城市多灾种早期联合预警GIS系统的设计与应用

阐述了城市或区域范围内早期预警协作和预警联合发布的必要性,以及系统的具体设计思路,包括当前城市灾害预警应用现状分析,城市预警数据管理、系统应用设计,系统应用创新三个方面,最终通过城市预警信息融合和共享,来应对解决宽泛而又错综复杂的各类城市灾害问题,拓展应急协作工作的信息广度,提升公众防范的精细化服务水平。     

数字矿山与煤矿瓦斯监测及预警

围绕煤矿瓦斯监测监控系统的开发与运用,介绍了基于数字矿山技术体系进行煤矿瓦斯监测、分析、显示、智能预警及救灾等方面的主要思路、关键技术、系统功能及应用效果。实践表明,瓦斯涌出量及突出动力现象的发生,受地质、地应力和开采条件等多种因素的影响,瓦斯突出预测所涉及的数据具有多源性、时空性、强变化等特征,GIS技术、虚拟现实技术等空间信息技术在煤矿瓦斯监测与预警中具有很大的应用潜力,能对煤矿瓦斯监测与智能预警研究产生重大变革,构建数字矿山对煤矿安全生产具有巨大的推动作用,效益十分显著。     

Addressing administrative units in international tsunami early warning systems: shortcomings in international geocode standards

Abstract

Administrative units reflect the territorial hierarchies established within all countries of the world. The units are addressable with geocodes that provide a bijective mapping between territories and unique identification codes. Early warning systems for natural or man-made hazards often map affected or threatened areas to administrative units to establish a spatial reference that is comprehensible to all parts of the population. Addressing these territories in an international context has several requirements, such as worldwide coverage, completeness and topicality, which must be met by geocode standards. In this paper, the practicability and suitability of international geocode standards are examined in the context of the requirements of large-scale early warning systems. This paper exposes the insufficiencies and limitations of existing geocode standards International Organization for Standardization (ISO)-3166, Second Administrative Level Boundaries data set project (SALB) and Nomenclature of the Territorial Units for Statistics (NUTS) and emphasises the suitability of the non-official hierarchical administrative subdivision codes (HASC). The analysis is framed in the context of addressing affected areas for an Indian Ocean tsunami early warning system. This system was developed within the Distant Early Warning Systems project according to the requirements of the United Nations Educational, Scientific and Cultural Organization (UNESCO) Intergovernmental Oceanic Commission for Regional Tsunami Watch Providers (RTWPs).     

基于GIS的海底电缆运行环境在线监控系统研究

由于海底电缆敷设环境复杂,水文气象条件多变,海缆运行安全受环境影响较大。本文运用地理信息技术,解析了海底电缆保护中多源环境监控数据。通过对海底电缆运行环境的可视化表达、船舶动态监控及风险评估,实现了海底电缆运行环境监测的自动化和智能化,有效提高了航行船舶对海底电缆破坏风险预警的可靠性及效率。     

GIS技术在无线电波场强分析中的应用研究

无线电波场强分析在广播电视台站规划中是一项重要的工作,采用传统的电波传播模型进行场强预测时,相关的计算大多依据纸质地图用手工进行,工作强度高,结果精确性低。本文结合地理信息系统(GIS)的空间数据管理、数字地形分析等技术,构建台站与发射机实体对象,基于地理空间信息环境实现了典型电波传播场强分析模型,提高了场强计算的效率和空间位置精度,同时将人口分布信息应用到模型中,增强了台站规划的科学性;最后讨论了GIS技术在电波传播模型中进一步应用的前景。     

SAR影像与光学影像的高斯伽玛型边缘强度特征匹配法

提出了一种基于影像边缘强度图描述的SAR影像与光学影像匹配方法。首先对影像进行粗纠正,消除影像之间的尺度和旋转变化;其次,改进相位一致性特征检测方法,提取对影像相干斑噪声稳健的特征点;然后基于高斯伽玛型双边窗口比值算子计算影像边缘强度图,在此基础上构造不变特征描述符;最后联合几何约束条件,实现SAR影像与光学影像匹配。试验结果证明,与现有方法相比,本文方法能够大幅提高SAR影像与光学影像匹配结果中的正确匹配特征数量以及影像配准精度。     

齿轮弯曲强度的有限元分析法

论述了齿轮弯曲强度的有限元分析方法，同传统的方法相比能准确地获得齿轮的真实应力场，为齿轮强度计算提供可靠的依据。