震后废墟中Wi-Fi信号场强传输模型研究     

何志学  钟晓玲  宋庆艳  陈会丽  李龙 《震灾防御技术》2017,12(4):997-1004

针对震后废墟中无法精确检测出电磁波的传输特性问题,本文提出了一种在震后废墟中Wi-Fi信号场强的检测方法。首先是对Wi-Fi信号场强在组成震后废墟主要介质中的传输特性进行检测推导。然后通过测量在废墟不同距离下场强的大小,即可推导出废墟下电磁波的场强与传输距离的关系,最后得出场强在震后废墟中的传输模型。实验表明,该传输模型的计算结果准确度高,对震后废墟中电磁波传输特性的检测具有重要意义。  相似文献   

海上消防系统风险分析探讨     

韩圣章  郭海涛  阎宏生 《海洋技术学报》2004,23(4):85-89

平台消防系统可靠与否直接影响到平台及平台操作人员的安全。文章在采用故障树方法对平台消防系统发生失效的路径及可能性进行分析。针对有些事件的发生频率极小但危险性极大的问题,引入危险度的概念,对可靠性进行量化,即计算产生概率,同时提出了计算模糊事件概率期望值的方法。为有效评估油气生产系统的安全性,以及建立起稳定可靠的功能服务系统提供了理论依据。  相似文献   

Surface morphology of soil cracks in Yuanmou Dry-hot Valley Region, Southwest China   总被引：3，自引：0，他引：3  

Donghong Xiong  Yi Long  Dongchun Yan  Xiaoning Lu  Zhonghua Ji  Haidong Fang 《山地科学学报》2009,6(4):373-379

Surface morphology of soil cracks is one of the important factors influencing the water evaporation rate in cracked soil in Yuanmou Dry-hot Valley Region, Southwest China. Quantitative study of the complicated surface morphology of soil cracks is a prerequisite for further studies of soil-cracking mechanisms. The present paper establishes a quantitative indicator system by application of concepts and methods originating from Fractal Geometry and Network Analysis. These indicators can effectively express the complicated features of soilcrack network structure. Furthermore, a series of values related to soil-crack morphology was obtained by image processing on field photos of soil-crack quads, and gradation criteria for the degree of development of soil cracks were determined. Finally, the changes in values of the morphological indicators under different degrees of development were analyzed in detail. Our results indicate that （1） the degree of development of soil cracks can be divided into five grades, i.e., feeble development, slight development, medium development, intensive development and extremely intensive development; （2） the values of the indicators change predictably with increasing degree of development of soil cracks. The area density （Dc） increases, and both the area-weighted mean ratio of crack area to perimeter （AWMARP）, which reflects the intensity of cracking, and the index r, which is related to the connectivity of a soil crack, grow uniformly （albeit with different forms）. AWMRAP increases at a geometric rate while r shows logarithmmic growth, indicating a gradual increase in the connectivity of a soil crack. Nevertheless, the areaweighted mean of soil-crack fractal dimension （AWMFRAC） shows a decreasing trend, indicating a gradual decline in the complexity of cracks as area density increases.  相似文献   

黏弹各向异性介质中波的反射与透射问题分析   总被引：6，自引：1，他引：5       下载免费PDF全文

刘财  郭智奇  杨宝俊  王晓欢  冯晅 《地球物理学报》2007,50(4):1216-1224

黏弹各向异性介质中传播不均匀波,其反射、透射模式不仅与介质分界面两侧速度对比有关,还与品质因子Q的对比有关. 用伪谱技术模拟黏弹各向异性介质分界面上波的反射、透射,并与弹性各向异性介质、黏弹各向同性介质和弹性各向同性介质的模拟结果做比较. 计算平面波的反射、透射系数,分析介质的黏弹性和各向异性对反射、透射系数的影响. 数值模拟了一个三层介质模型中的波场,分析两个分界面上产生的反射波的特征. 黏弹各向异性介质中,qS波比qP波衰减程度大.  相似文献