Nature and the Singapore resident   总被引：2，自引：0，他引：2  

Belinda Yuen  Lily Kong  Clive Briffett 《GeoJournal》1999,49(3):323-331

Singapore has witnessed rapid urban development in the last thirty years. Its landscape has changed from one of slums and squatters in the immediate post-war years to a city of gardens and high-rise high-density housing. The concept of a `garden city' was introduced to guide the development of a city-state with abundant greenery. In the process, many parks and gardens were created including park connectors which are green linkages between parks and other land uses. This paper presents the findings of an ongoing research into park connectors. It reports on that part of the survey results which examine the views of residents towards nature provision in park connectors and suggest some design options to enhance the planning of park connectors. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

蘑菇湖水库富营养化发生机制和治理途径的探讨   总被引：1，自引：1，他引：0  

赵章元  王正荣  负根潮 《湖泊科学》1992,4(4):77-80

通过对蘑菇湖水库的水质、底质和水生生物等的调查,分析了该水库富营养化的发生机理,并对恢复生态平衡、防治富营养化的途径进行了探讨。  相似文献   

Modal-based ground motion selection procedure for nonlinear response time history analysis of high-rise buildings     

Yang Liu  J.S. Kuang  Terry Y.P. Yuen 《地震工程与结构动力学》2020,49(1):95-110

The selection of representative input ground motions (IGMs) is important for a proper nonlinear response time history analysis (NLRHA) of modern structures. The prevailing IGM selection procedure requires that the response spectra of selected ground motions are matched with the code-specified design spectra, while the effect of the frequency contents combination in the time domain on the multimode interactions is not considered. Ignoring the effect of the frequency contents combination in the time domain of IGMs may cause significant variations in the analysis results for selected IGMs, although they are matched to the same design spectrum. In this paper, a modal-based ground motion selection (MGMS) procedure is proposed as a supplement to spectrum matching-based IGM selection procedures for selecting proper IGMs that can sufficiently induce the multimode interactions. In the proposed procedure, three equivalent single-degree-of-freedom (ESDOF) systems are developed by pushover analysis. NLRHA is then conducted for these ESDOF systems with a set of 20 seed IGMs chosen by the spectrum-matching–based selection procedure. Finally, seven IGMs are selected from the seed IGMs for NLRHA in the full structural model. To verify MGMS, seismic demands of high-rise buildings were computed by NLRHA with seven MGMS-selected IGMs, seven IGMs with closest spectrum matching, and groups of seven randomly selected IGMs derived from three different sets of 20 seed IGMs. The computed seismic demands with MGMS-IGMs show very good agreement with the mean demands determined using the whole set of seed IGMs, while the deviation is much lesser compared with those groups of randomly selected IGMs.  相似文献   

基于深度学习卷积神经网络的地震波形自动分类与识别   总被引：9，自引：0，他引：9       下载免费PDF全文

赵明  陈石  Dave Yuen 《地球物理学报》2019,62(1):374-382

发展高效、高精度、普适性强的自动波形拾取算法在地震大数据时代背景下显得越来越重要.波形自动拾取算法的主要挑战来自如何适应不同区域的不同类型地震事件的分类与筛选.本文针对地震事件-噪音分类这一问题,使用13839个汶川地震余震事件建立数据集,应用深度学习卷积神经网络(CNN)方法进行训练,并用8900个新的汶川余震事件作为检测数据集,其训练和检测准确率均达到95%以上.在对连续波形的检测中,CNN方法在精度和召回率上优于STA/LTA和Fbpicker传统方法,并能找出大量人工挑选极易遗漏的微震事件.最后,我们应用训练好的最优模型对选自全国台网的441个台站8天的连续波形数据进行了识别、到时挑取及与参考地震目录关联,CNN检出7016段波形,用自动挑选算法拾取到1380对P,S到时,并与540个地震目录事件成功关联,对1级以上事件总体识别准确率为54%,二级以上为80%,证明了CNN模型具有泛化能力,初步展示了CNN在发展兼具效率、精度、普适性算法,实时地震监测等应用上具有巨大潜力.  相似文献