Nonstationary frequency effect of the ground motion upon the strength levels of the shear type RC structures     

Z. Hasgü  r 《Soil Dynamics and Earthquake Engineering》1995,14(6):453-461

In order to investigate the influence of nonstationary frequency content variations, nonlinear response analysis for origin-oriented type hysteretic model is carried out and results are presented by applying two different S_I and S_II ensembles with varied frequency contents. The theoretical background of strong motion simulation is explained briefly depending on frequency parameters of stiff soil data. Based on models and applying Monte-Carlo's simulation mean values and standard deviations of displacement ductility demands for both ensembles are calculated. Required strength levels are investigated in probabilistic sense adopting light and heavy (but controlled) damage criteria. It is concluded that the nonlinear behaviour of the structure is greatly influenced by the nonstationary frequency content deviations as being shown that larger strength requirements for the S_I type strong ground motion ensemble than the S_II, although both ensembles have almost the same acceleration response spectra.  相似文献   

Pathways to seismic hazard evaluation: Extreme and characteristic earthquakes in areas of low and high seismicity   总被引：4，自引：0，他引：4  

Paul W. Burton 《Natural Hazards》1990,3(3):275-291

The general philosophy of seismic hazard evaluation described here is appropriate for selection of seismic input to regional earthquake engineering codes prior to detailed on-site inspections and geotechnical assessments. Some probabilistic seismic hazard methodologies which can be applied in areas of low and high seismicity, are briefly described to emphasise the main equations with specimen results. Three aspects of hazard assessment are explored by different pathways. These include the analysis of regional earthquake catalogues to obtain magnitude recurrence, particularly using Gumbel extreme value statistics. This is extended to assess ground shaking hazard which is usually sought by earthquake engineers. Thirdly, the concept of earthquake perceptibility is developed, leading to the identification of an earthquake magnitude or type which is characteristic of a region. This most perceptible earthquake is most likely to be felt at any site in a region and provides an earthquake selection criterion which can be used in aseismic design of noncritical structures. Because there are several methods of seismic hazard evaluation, the view is expressed that it is sensible for practical purposes to seek results from different methods or different pathways to the hazard evaluation.Paper presented at the Commission of the European Communities' School on Earthquake Hazard Evaluation, Athens, and at the 21st General Assembly of the European Seismological Commission, held in Sofia, 1988.Now at School of Environmental Sciences, University of East Anglia, University Plain, Norwich NR4 7TJ, U.K.  相似文献   

Three-dimensional Fusion of Spaceborne and Ground Radar Reflectivity Data Using a Neural Network–Based Approach   总被引：1，自引：0，他引：1  

Leilei KOU  Zhuihui WANG  Fen XU 《大气科学进展》2018,35(3):346-359

The spaceborne precipitation radar onboard the Tropical Rainfall Measuring Mission satellite(TRMM PR) can provide good measurement of the vertical structure of reflectivity, while ground radar(GR) has a relatively high horizontal resolution and greater sensitivity. Fusion of TRMM PR and GR reflectivity data may maximize the advantages from both instruments.In this paper, TRMM PR and GR reflectivity data are fused using a neural network(NN)–based approach. The main steps included are: quality control of TRMM PR and GR reflectivity data; spatiotemporal matchup; GR calibration bias correction;conversion of TRMM PR data from Ku to S band; fusion of TRMM PR and GR reflectivity data with an NN method;interpolation of reflectivity data that are below PR's sensitivity; blind areas compensation with a distance weighting–based merging approach; combination of three types of data: data with the NN method, data below PR's sensitivity and data within compensated blind areas. During the NN fusion step, the TRMM PR data are taken as targets of the training NNs, and gridded GR data after horizontal downsampling at different heights are used as the input. The trained NNs are then used to obtain 3D high-resolution reflectivity from the original GR gridded data. After 3 D fusion of the TRMM PR and GR reflectivity data, a more complete and finer-scale 3D radar reflectivity dataset incorporating characteristics from both the TRMM PR and GR observations can be obtained. The fused reflectivity data are evaluated based on a convective precipitation event through comparison with the high resolution TRMM PR and GR data with an interpolation algorithm.  相似文献   

四川盆地一次强降水过程水汽特征     

宋雯雯  李国平  王皓 《气象科技》2018,46(1):129-138

利用WRF模式、地基GPS资料以及常规气象观测资料,结合模式输出资料的高空间分辨率(10km)和GPS大气可降水量(GPS-PWV)资料的高时间分辨率(30min)的优点,对2008年7月20—22日四川盆地一次暴雨过程的水汽变化特征及各物理量与大气可降水量的关系进行综合分析。结果表明:此次降雨过程是由高原涡和西南涡共同作用引起,WRF模式能够较好地模拟出降雨落区和强度。GPS-PWV反映的大气可降水量增减趋势与WRF模拟的较为一致。水汽密度垂直分布反映了大气可降水量分布,水汽密度随高度增加而递减,降雨初期,水汽密度随高度减小迅速,降雨强盛时期,水汽密度随高度减小的速度减慢。水汽辐合使得水汽密度和大气可降水量增大,风的散度项与水汽通量散度的变化一致,而水汽平流项对水汽辐合贡献较小,水汽的辐合主要由风场辐合造成。  相似文献   

Some scientific problems facing research on hydrological processes in an inland river basin     

Ersi Kang  Rensheng Chen  Zhihui Zhang  Xibin Ji  Bowen Jin 《Frontiers of Earth Science》2008,2(4):384-392

The challenge is put forward to scientific hydrology by the advancement of water sciences; that is, how should we carry out a multidisciplinary, integrated and cooperative research on hydrological processes in the basin, regional and global scales, in order to better understand the role water plays in the changes of the natural resources and environment of the earth, and to understand the hydrosphere and its interactions with the atmosphere, lithosphere and biosphere. How the changes and transformation of the components of the water cycle and water balance occur in an inland river basin has yet to be understood. We also need to understand what the interactions of water cycle, ecosystems and environment are, and what the responses and feedback of the changes to global change and to human activities are. The water cycle in an inland river basin characterizes the runoff generation region of the mountains upstream, the artificial oases region of water resources exploitation and utilization midstream and the natural desert oases region of runoff dissipating downstream. The mountain hydrological processes are discussed from water cycle, energy balance, water balance and ecological processes. The interactions of water and vegetation are discussed in relation to ecohydrology, and the hydrological processes in the ground water-soil-vegetation layer are discussed from the concept of the critical zone newly put forward abroad. The basic frame is put forward to carry out the field measurement, experiment and studies of hydrological processes in a typical inland river basin. __________ Translated from Advances in Earth Science, 2007, 22(9): 940–953 [译自: 地球科学进展]  相似文献   

井地磁测资料联合反演及应用     

刘双  张大莲  刘天佑  杨坤彪  范志雄 《地质与勘探》2008,44(6):69-72

井中磁测离深部场源近,能避开浅部干扰,是一种有效的找矿手段,但其控制范围有限;地面磁测采集方便且控制范围大,但老矿区干扰因素多,深部矿体信号弱,不容易解释.文章充分利用地面和井中磁测资料的优点,以二度板状体模型为例,进行井地磁测资料联合反演.通过数值模拟说明了井地联合反演方法的优越性,同时还比较了马奎特法,广义逆法和遗传算法三种不同算法的优缺点,最后将其应用于大冶铁矿实际资料的处理解释,为危机矿山的深部找矿提供了一种有效的方法.  相似文献   

无人机三维空气质量监测研究   总被引：1，自引：0，他引：1  

彭艳  叶金伟  张利勇  聂晨晖  倪慧珠  张傲敏 《测绘科学》2017,42(11)

针对现有空气监测缺乏污染垂直分布特征的观测及数据采集覆盖范围有限的问题,该文提出了用无人驾驶飞机搭载微型空气质量检测器监测大气污染的方法,首先分析了传统地面监测站的缺点,并阐述了监测设备的构成;然后从无人驾驶飞机大气污染空间采样方案、污染物数据的准确性及可靠性校正、大气污染时空规律几个方面做了研究;最后选择浙江省临安市青山湖街道、上海奉贤区等地区进行了试验。研究结果能有效补充地面监测站的数据缺失,揭示PM2.5、O3等大气污染物的垂直分布、垂直扩散及区域性输送特征,为空气污染预警和防控对策机制的制定提供重要技术依据。  相似文献   

时间序列InSAR监测地表形变   总被引：1，自引：0，他引：1  

郭颖平  杨进生  赵学亮 《测绘科学》2017,42(5)

针对相干点目标的时间序列,提出了地表形变InSAR技术监测方法,该方法适用于小数据集分析。并采用郑州地区2007年1月到2010年4月期间的8景ALOS PALSAR数据进行验证分析。研究表明,识别的相干点目标具有大的干涉相干值和小的振幅离差,在时间序列中具有可靠的相位。从误差分析和与ENVISAT PSInSAR结果对比分析表明,该文求得的形变速率标准差在0.34mm/a和5.56mm/a之间,表明提出方法是可靠的。  相似文献   

TM图像的SOMP几何纠正法   总被引：10，自引：0，他引：10  

任留成  朱重光  郑柯  曹兆丰  郭军  赵清 《遥感学报》2001,5(4):295-299

针对缺少地面控制点（GCP）的遥感影，探讨一种几何精纠正的新方法，就是把空间投影理论应用于遥感图像的几何精纠正中，利用空间斜墨卡托投影（SOMP）和少量地面控制点对遥感影像实施几何精纠正，该方法理论严密，算法速度快捷，适用性强，通过对广州地区的TM影像进行的几何精纠正实验，该方法十分有效，几何精纠正精度在一个像素左右。  相似文献   

地震动加速度过程的小波模拟   总被引：3，自引：0，他引：3  

谢异同  张同亿  吴敏哲 《地震工程与工程振动》2001,21(2):19-23

本文应用基数B－样条小波模拟地震动加速度过程，将小波分析引入地震动加速度过程的研究，实现了地震动加速度的模拟，并可给出其解析表达式，便于设计地震动的调整及地震反应的求解。  相似文献