三种探测煤层采空区的方法   总被引：1，自引：0，他引：1  

王立会  潘冬明  张兴岩 《物探与化探》2008,32(3):291-294

采空区的存在对矿山生产和工程建设造成极大的安全隐患,采空区探测已成为重要研究课题。笔者结合参加过的工程项目,具体介绍3种探测煤层采空区的方法:井间地震、探地雷达和浅层地震反射波法,并分析比较了它们的优缺点。  相似文献   

咸阳机场一次阵风锋的探测和自动识别     

涂朝勇  倪长健  白爱娟  王杰  赵志军  朱育雷 《气象科技》2018,46(5):979-987

利用西安多普勒雷达观测资料、NCEP再分析资料和自动气象站资料,对2016年6月4日发生在咸阳机场附近的一次阵风锋天气展开研究。这次过程是由蒙古低涡主导,低涡后部的冷空气南下触发对流引起的,阵风锋过境时咸阳机场产生了2.2mm降水和19.7m·s^(-1)的大风天气,多架次航班受到影响。从雷达回波的分析发现,这次阵风锋的特征表现为,生命史2h左右,回波强度5~25dBz,长度约70km,平均移速达49.7km·h^(-1),伴有明显的窄带回波和辐合线。对雷达基数据进行质量控制后,设计了自动识别软件,在强度场上利用双向梯度算法,以及速度场上使用Shear参量算法,根据窄带回波和辐合线的空间一致性,对该阵风锋的位置和强度进行识别。最后利用临界成功指数对这个软件进行评估,本次阵风锋的识别率达到83.33%,表明该软件能够识别阵风锋,可在业务中使用。  相似文献   

中国大陆社会与文化地理学研究领域综观   总被引：1，自引：0，他引：1  

陈晓亮  朱竑 《地理研究》2018,37(10):2024-2038

中国人文地理学的发展经历了一条充满艰辛而又曲折的道路。改革开放以来,中国人文地理学开始回暖,社会与文化地理研究重焕新生,但学科所占位置相对边缘。在“文化转向”的背景下,近年来社会与文化地理学开始呈现出欣欣向荣之势。从文化区、文化传播与文化整合,民族文化地理,文化景观与文化经济,地方和基于地方的政治,边缘群体研究五个方面对中国大陆社会与文化地理研究现状进行综观性的概述和批判性的反思。建立在西方学术话语霸权之上的社会与文化地理学,需要开展建设性的对话并加以研究。未来的社会与文化地理学研究应更加强调跨学科视角和对当前社会问题的关注。  相似文献   

Development of a System for 3D High-resolution Seismic Reflection Profiling on Lakes   总被引：2，自引：0，他引：2  

M. Scheidhauer  F. Marillier  D. Dupuy 《Marine Geophysical Researches》2005,26(2-4):183-195

A high-resolution three-dimensional (3D) seismic reflection system for small-scale targets in lacustrine settings has been developed. Its main characteristics include navigation and shot-triggering software that fires the seismic source at regular distance intervals (max. error of 0.25 m) with real-time control on navigation using differential GPS (Global Positioning System). Receiver positions are accurately calculated (error<0.20 m) with the aid of GPS antennas attached to the end of each of three 24-channel streamers. Two telescopic booms hold the streamers at a distance of 7.5 m from each other. With a receiver spacing of 2.5 m, the bin dimension is 1.25 m in inline and 3.75 m in crossline direction. To test the system, we conducted a 3D survey of about 1 km² in Lake Geneva, Switzerland, over a complex fault zone. A 5-m shot spacing resulted in a nominal fold of 6. A double-chamber bubble-cancelling 15/15 in³ air gun (40–650 Hz) operated at 80 bars and 1 m depth gave a signal penetration of 300 m below water bottom and a best vertical resolution of 1.1 m. Processing followed a conventional scheme, but had to be adapted to the high sampling rates, and our unconventional navigation data needed conversion to industry standards. The high-quality data enabled us to construct maps of seismic horizons and fault surfaces in three dimensions. The system proves to be well adapted to investigate complex structures by providing non-aliased images of reflectors with dips up to 30°.  相似文献   

Seismic character of gas hydrates on the Southeastern U.S. continental margin   总被引：14，自引：0，他引：14  

M. W. Lee  D. R. Hutchinson  W. F. Agena  W. P. Dillon  J. J. Miller  B. A. Swift 《Marine Geophysical Researches》1994,16(3):163-184

Gas hydrates are stable at relatively low temperature and high pressure conditions; thus large amounts of hydrates can exist in sediments within the upper several hundred meters below the sea floor. The existence of gas hydrates has been recognized and mapped mostly on the basis of high amplitude Bottom Simulating Reflections (BSRs) which indicate only that an acoustic contrast exists at the lower boundary of the region of gas hydrate stability. Other factors such as amplitude blanking and change in reflection characteristics in sediments where a BSR would be expected, which have not been investigated in detail, are also associated with hydrated sediments and potentially disclose more information about the nature of hydratecemented sediments and the amount of hydrate present.Our research effort has focused on a detailed analysis of multichannel seismic profiles in terms of reflection character, inferred distribution of free gas underneath the BSR, estimation of elastic parameters, and spatial variation of blanking. This study indicates that continuous-looking BSRs in seismic profiles are highly segmented in detail and that the free gas underneath the hydrated sediment probably occurs as patches of gas-filled sediment having variable thickness. We also present an elastic model for various types of sediments based on seismic inversion results. The BSR from sediments of high ratio of shear to compressional velocity, estimated as about 0.52, encased in sediments whose ratios are less than 0.35 is consistent with the interpretation of gasfilled sediments underneath hydrated sediments. This model contrasts with recent results in which the BSR is explained by increased concentrations of hydrate near the base of the hydrate stability field and no underlying free gas is required.  相似文献   

A parabolic equation extended to account for rapidly varying topography   总被引：1，自引：0，他引：1  

Tai-Wen Hsu  Chih-Chung Wen 《Ocean Engineering》2001,28(11)

In this paper, following the procedure outlined by Li (1994. An evolution equation for water waves. Coastal Engineering, 23, 227-242) and Hsu and Wen (2000. A study of using parabolic model to describe wave breaking and wide-angle wave incidence. Journal of the Chinese Institute of Engineers, 23(4), 515–527) and Hsu and Wen (2000) the extended refraction–diffraction equation is recasted into a time-dependent parabolic equation. This model, which includes higher-order bottom effect terms, is extended to account for a rapidly varying topography and wave energy dissipation in the surf zone. The importance of the higher-order bottom effect terms is examined in terms of the relative water depth. The present model was tested for wave reflection in a number of different environments, namely from a plane slope with different inclinations, from a patch of periodic ripples. The model was also tested for wave height distribution around a circular shoal and wave breaking on a barred beach. The comparison of predictions with other numerical models and experimental data show that the validity of the present model for describing wave propagation over a rapidly varying seabed is satisfactory.  相似文献   

Wave reflection and transmission by curtainwall–pile breakwaters using circular piles     

Kyung-Duck Suh  Hoo Young Jung  Chong Kun Pyun   《Ocean Engineering》2007,34(14-15):2100-2106

This paper presents a mathematical model which computes the hydrodynamic characteristics of a curtainwall–pile breakwater (CPB) using circular piles, by modifying the model developed for rectangular piles by Suh et al. [2006. Hydrodynamic characteristics of pile-supported vertical wall breakwaters. Journal of Waterway, Port, Coastal and Ocean Engineering 132(2), 83–96]. To examine the validity of the model, laboratory experiments have been conducted for CPB with various values of draft of curtain wall, spacing between piles, and wave height and period. Comparisons between measurement and prediction show that the mathematical model adequately reproduces most of the important features of the experimental results. The mathematical model based on linear wave theory tends to over-predict the reflection coefficient as the wave height increases. As the draft of the curtain wall increases and the porosity between piles decreases, the reflection and transmission coefficient increases and decreases, respectively, as expected. As the relative water depth increases, however, the effect of porosity disappears because the wave motion is minimal in the lower part of a water column for short waves.  相似文献   

天然气水合物研究中的AVA方法分析   总被引：1，自引：0，他引：1  

阮爱国  李湘云 《海洋学研究》2006,24(4):1-11

运用多相介质弹性模量理论并补充了不同情况下的密度计算公式,选取适当的参数,模拟了含水合物沉积物和含游离气体沉积物的地震波速度和泊松比随孔隙度和饱和度的变化规律,并进行了深入分析。通过与完整公式的对比,对AVA常用的反射系数近似计算式的精度进行了讨论,同时分析了地震波速度、泊松比、密度等参数对于BSR反射系数的不同贡献。  相似文献   

Reflection of regular and irregular waves from a partially perforated caisson breakwater with a rock-filled core     

LIU Yong  LI Yucheng  TENG Bin  MA Baolian 《海洋学报(英文版)》2007,26(3):129-141

The reflection of regular and irregular waves from a partially perforated caisson breakwater with a rock-filled core is examined. The present mathematical model is developed by means of the matched eigenfunction method. Numerical results of the present model are compared with the experimental data of different researchers. Numerical examples are given to examine the effect of rock fill on the reflection coefficient. The differences between regular and irregular waves are also investigated by means of theoretical and experimental results. It is found that the minimum reflection coefficient of irregular waves is larger than that of corresponding regular waves, but the contrary is the case for the maximum reflection coefficient.  相似文献   

海洋地震勘探中地震波、鬼波综合效应分析与应用   总被引：1，自引：0，他引：1  

陆敬安  伍忠良  曾宪军 《海洋技术学报》2006,25(4):76-78,98

鬼波是影响海洋地震资料采集质量的重要因素之一,经过海水表面反射的鬼波与海底反射波相互叠加。“地震波、鬼波的综合效应”受很多因素的影响,文中从传播路径、传播时间等方面讨论了地震波与鬼波的综合效应。通过计算机模拟了二者的综合效应,与实测资料进行了对比,其幅频特性中陷波点、幅度等特性非常接近。结合水合物勘探的目的,文章探讨了基于识别BSR的勘探频率要求震源和电缆的最佳沉放深度,并通过实际应用验证了理论推算的正确性。  相似文献