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陈梦竹  程雄  张新利  高晖 《大地测量与地球动力学》2013,33(4):83-87

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Residual drift demands in moment‐resisting steel frames subjected to narrow‐band earthquake ground motions     

Edén Bojórquez  Jorge Ruiz‐García 《地震工程与结构动力学》2013,42(11):1583-1598

This paper presents the main results of the evaluation of residual inter‐story drift demands in typical moment‐resisting steel buildings designed accordingly to the Mexican design practice when subjected to narrow‐band earthquake ground motions. Analytical 2D‐framed models representative of the study‐case buildings were subjected to a set of 30 narrow‐band earthquake ground motions recorded on stations placed in soft‐soil sites of Mexico City, where most significant structural damage was found in buildings as a consequence of the 1985 Michoacan earthquake, and scaled to reach several levels of intensity to perform incremental dynamic analyses. Thus, results were statistically processed to obtain hazard curves of peak (maximum) and residual drift demands for each frame model. It is shown that the study‐case frames might exhibit maximum residual inter‐story drift demands in excess of 0.5%, which is perceptible for building's occupants and could cause human discomfort, for a mean annual rate of exceedance associated to peak inter‐story drift demands of about 3%, which is the limiting drift to avoid collapse prescribed in the 2004 Mexico City Seismic Design Provisions. The influence of a member's post‐yield stiffness ratio and material overstrength in the evaluation of maximum residual inter‐story drift demands is also discussed. Finally, this study introduces response transformation factors, T_p, that allow establishing residual drift limits compatible with the same mean annual rate of exceedance of peak inter‐story drift limits for future seismic design/evaluation criteria that take into account both drift demands for assessing a building's seismic performance. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

狭窄巷道小定向钻机及配套泥浆泵车的研制          下载免费PDF全文

姚克  方鹏  邵俊杰  李栋  张占强 《探矿工程》2016,43(10):165-169

针对现有定向长钻孔钻机在煤矿井下狭窄巷道及复杂地层条件应用存在的诸如结构体积偏大、功能结构与施工工艺匹配需改善、附属设备配套及操控性差等实际问题,研制了窄体型小定向钻机成套装备,通过现场工业性试验和长期推广应用验证了产品的性能与可靠性。阐明了该套设备的研制思路和必要性,以及解决的关键技术问题。  相似文献   

边界层辐合线在局地强风暴临近预警中的应用   总被引：4，自引：2，他引：2  

刁秀广  车军辉  李静  朱君鉴 《气象》2009,35(2):29-33

利用济南CINRAD/SA雷达探测到的边界层辐合信息,结合地面实况和探空资料及NCEP资料,对近年发生在山东中部的典型局地强风暴的生成及对流参数进行了分析.结果表明:高时空分辨率的雷达能获得近地层辐合线信息,对流风暴强的出流和近地层环境风的辐合在一定条件下可产生窄带回波;远离风暴主体的出流边界和顺地面风移动的风速辐合线在热力条件较弱的情况下一般不会产生对流天气;出流边界的叠加或出流边界与环境风辐合线的叠加在有利的环境条件下可产生局地强风暴,单纯的近地层辐合线在有利的环境条件下可产生较为孤立的局地风暴,可作为强对流天气临近预警的关键参考依据;风暴初始位置、初始时间和风暴类型具有不确定性,是强对流天气临近预警的难点.  相似文献   

基于Radon变换的星载SAR图像窄V尾迹检测     

张晓燕  尤红建  付琨 《测绘科学》2009,34(2)

在Radon变换的基础上,提出了一种在Radon变换域附加检测规则对星载SAR图像中窄V尾迹进行检测的方法。附加的规则由去除短线规则和去除孤立点规则组成,将该方法应用于星载SAR图像中不同表现形式下的窄V尾迹,实验表明,该方法具有一定的普遍适用性。  相似文献   

A polarimetric spectral imager using acousto-optic tunable filters     

WM. Hayden Smith  K. M. Smith 《Experimental Astronomy》1990,1(5):329-343

We report laboratory and telescopic observations with a polarimetric spectral imager based on an acousto-optic tunable filter (AOTF) where we demonstrate simultaneous acquisition of orthogonally polarized images at a spectral resolving power on the order of 103 and at a Rayleigh criterion spatial resolution of 100 line pairs per mm. This matches the spatial resolution of most digital arrays. An AOTF is shown to be usable as a fast shutter with a contrast of over 10⁴ on a sub-millisecond time scale while providing an high transmittance of about 75% (both polarizations summed) when illuminated by white light. The polarization contrast between the orthogonally polarized images exceeds 10⁴ across the field of view, permitting accurate measurement of the polarization parameters of incident light. These characteristics are now being used in a program of high spatial resolution imaging in narrow spectral bands. Some peculiarities and limitations of AOTFs are indicated.This research was supported by NASA under Grant NAGW-122 and under contract with the Jet Propulsion Laboratory under NASA grant NAS 7-918.Visiting Astronomer, Mauna Kea Observatory.  相似文献   

卫星导航系统地面监控站站间通信抗干扰研究     

任小伟  梁思远 《全球定位系统》2014,(3):49-52

全球卫星导航系统中,地面监测站和主控站通信传输容易受到宽带和窄带干扰的影响,导致卫星导航系统精确性和完好性降低。分析研究利用扩频增益抑制宽带干扰和利用陷波滤波器抑制窄带干扰,解决地面监测站和主控站站间通信抗宽带和窄带干扰问题,为增强卫星导航系统精确性和完好性提供了保障。  相似文献   

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徐君毅  李金龙  何海波  郭海荣  王爱兵 《大地测量与地球动力学》2014,34(4):123-126

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井底恒压式与微流量式控压钻井系统控制机理差异分析          下载免费PDF全文

姜英健  周英操  杨甘生  刘伟 《探矿工程》2014,41(5):6-9

随着我国能源需求的不断增加,大量深层和复杂油气藏需要进行开采,伴随而来的各种钻井复杂问题也越来越多,其中钻井安全密度窗口窄的问题就是最为突出的问题之一。控压钻井技术目前是解决该问题最有效的办法。控压钻井技术按照其控制原理又可分为井底恒压式控压系统与微流量控压钻井系统。通过对这2种控压钻井方式的基本工艺流程及装备进行分析,比较2种控压钻井系统区别,为进一步推广控压钻井技术提供建议。  相似文献   

从地震信息看新生代郯庐断裂带的展布与活动          下载免费PDF全文

杨克绳胡平  党晓春 《地学前缘》2009,16(4):240-251

郯庐前新近纪断裂带为中国东部滨太平洋地区一条巨型张扭走滑构造带。利用地震信息分析地质结构,可将其分为南、中、北三大段和七亚段。按其影响范围的规模可划分为广义和狭义两类:广义郯庐前新近纪断裂带地质结构是“两凹夹一隆”,狭义郯庐前新近纪断裂带则指高垒带与两侧(邻)的断层组合。断裂带内外都发育有反转、花状构造。狭义郯庐前新近纪断裂带走向为NNE,仅在嘉山以南为NE向,其两侧的前新近纪断层大体上都为EW、NE和NEE走向,与狭义郯庐断裂呈锐角相切。古近纪构造层中,由南到北郯庐断层两侧箕状断陷边界都由生长断层所组成,说明郯庐断裂两侧的古近纪断陷应属拉张盆地,并非拉分盆地,郯庐古近纪断裂动力学是拉张而非拉分构造应力场。古近纪构造层在拉张翘倾运动中叠加了右旋走滑地质应力,这种右旋走滑应力是太平洋板块向西俯冲至欧亚板块之下的结果。中生代郯庐断裂的动力学表现为库拉板块向北俯冲至欧亚板块之下形成的左旋平移现象。郯庐断裂NE向平移走滑与北西向隐蔽断裂的相交处是发生破坏性地震的构造部位,因此,应特别重视对高丽营北东向生长断层与渤中-孙河-南口北西向隐蔽断层相交处地震动向的监控。  相似文献