利用数字摄影测量进行钢结构挠度的变形监测   总被引：6，自引：0，他引：6  

徐芳  刘友光  于承新  黄桂兰 《武汉大学学报(信息科学版)》2001,26(3):256-260

钢结构的异常变形或局部损坏可通过荷载－挠度曲线以及给轴的挠度曲线反映出来，利用数字摄影测量方法进行结构的变形监测是传统测量方式的变革，可实现半自动的实时监测，本文介绍了相应的测量方法并给出了实验结果。  相似文献   

矿区深部矿体定位预测的有效途径研究——以山东招远界河金矿为例   总被引：6，自引：0，他引：6       下载免费PDF全文

曹新志  高秋斌  徐伯骏 《地质找矿论丛》2001,16(4):243-246

矿床深部矿体煊位预测是成矿预测工作中一项难度较大，失误率较高的较新研究课题。针对不同类型的矿床，选择合理的有效途径与方法是进行正确的矿体定位预测的关键所在。以山东招远界河破碎带蚀变岩型金矿为例，从区域含矿间隔的判定，断裂构造定位控矿研究以及深部矿化信息发掘等方面入手，进行了矿体定位预测有效途径的探索工作，并取得了较好的实效。  相似文献   

The Sirens' voices? Field practices and dialogue in geography   总被引：2，自引：1，他引：2  

Richard C. Powell 《Area》2002,34(3):261-272

This paper responds to recent demands for greater discussion between physical and human geographers over common conceptualizations and entities. I argue that one possible way in which to conduct such a dialogue would be through considerations of reconceptualized modes of fieldwork practice across the discipline of geography and cognate disciplines. In consequence, I examine such concepts of fieldwork, encompassing diverse attempts such as an ethnographic politics of location and new visions of geomorphological practice. In so doing, I indicate some of the broader potentialities available to historians and philosophers of field science.  相似文献   

Improvements in mining induced microseismic source locations at the Lucky Friday mine using an automated whole-waveform analysis system     

Douglas A. Dodge  Kenneth F. Sprenke 《Pure and Applied Geophysics》1992,139(3-4):609-626

For years, severe rockburst problems at the Lucky Friday mine in northern Idaho have been a persistent safety hazard and an impediment to production. An MP250 based microseismic monitoring system, which uses simple voltage threshold picking of first arrivals, has been used in this mine since 1973 to provide source locations and energy estimates of seismic events. Recently, interest has been expressed in developing a whole waveform microseismic monitoring system for the mine to provide more accurate source locations and information about source characteristics. For this study, we have developed a prototype whole-waveform microseismic monitoring system based on a 80386 computer equipped with a 50 kHz analog-digital convertor board. The software developed includes a data collection program, a data analysis program, and an event detection program. Whole-waveform data collected and analyzed using this system during a three-day test have been employed to investigate sources of error in the hypocenter location process and to develop an automatic phase picker appropriate for microseismic events.Comparison of hypocenter estimates produced by the MP250 system to those produced by the whole-waveform system shows that significant timing errors are common in the MP250 system and that these errors caused a large part of the scatter evident in the daily activity plots produced at the mine. Simulations and analysis of blast data show that analytical control over the solutions is strongly influenced by the array geometry. Within the geophone array, large errors in the velocity model or moderate timing errors may result in small changes in the solution, but outside the array, the solution is very sensitive to small changes in the data.Our whole-waveform detection program picks event onset times and determines event durations by analysis of a segmented envelope function (SEF) derived from the microseismic signal. The detection program has been tested by comparing its arrival time picks to those generated by human analysis of the data set. The program picked 87% of the channels that were picked by hand with a standard error of 0.75 milliseconds. Source locations calculated using times provided by our entire waveform detection program were similar to those calculated using hand-picked arrival times. In particular, they show far less scatter than source locations calculated using arrival times based on simple voltage threshold picking of first arrivals.  相似文献   

Identification ofP/S-wave successions for application in microseismicity     

J. -P. Deflandre  M. Dubesset 《Pure and Applied Geophysics》1992,139(3-4):405-420

Interpretation ofP/S-wave successions is used in induced or passive microseismicity. It makes the location of microseismic events possible when the triangulation technique cannot be used. To improve the reliability of the method, we propose a technique that identifies theP/S-wave successions among recorded wave successions. A polarization software is used to verify the orthogonality between theP andS polarization axes. The polarization parameters are computed all along the 3-component acoustic signal. Then the algorithm detects time windows within which the signal polarization axis is perpendicular to the polarization axis of the wave in the reference time window (representative of theP wave). The technique is demonstrated for a synthetic event, and three application cases are presented. The first one corresponds to a calibration shot within which the arrivals of perpendicularly polarized waves are correctly detected in spite of their moderate amplitude. The second example presents a microseismic event recorded during gas withdrawal from an underground gas storage reservoir. The last example is chosen as a counter-example, concerning a microseismic event recorded during a hydraulic fracturing job. The detection algorithm reveals that, in this case, the wave succession does not correspond to aP/S one. This implies that such an event must not be located by the method based on the interpretation of aP/S-wave succession as no such a succession is confirmed.  相似文献   

城市军事地理系统与空间结构     

刘晓静 《测绘学院学报》1992,(1)

本文在讨论现代城市军事作用的基础上,运用系统论和区位论的方法探讨建立城市军事地理系统和城市军事地理空间结构的有关理论。  相似文献   

An algorithm for the optimum distribution of a regional seismic network—I   总被引：1，自引：0，他引：1  

Andrzej Kijko 《Pure and Applied Geophysics》1977,115(4):999-1009

Summary An algorithm for the optimum distribution of any number of regional seismic stations is formulated. The information needed from a given region is the relative distribution of seismic intensity and the travel times of seismic waves used in earthquake location procedure. To define the optimum distribution of a regional network, some generalization of D-planning (minimization of the ellipsoid volume of earthquake location errors) was applied. The D-optimum criterion is generalized for a case where equations describing the process are nonlinear and when the most probable values of the sought parameters (origin time and earthquake focus coordinates) are not known.As an example of the algorithm application, the optimum distribution of seismic stations in the central district of the Lublin Coal Basin in Poland is given.  相似文献   

RELOCATION AND FOCAL MECHANISMS OF YUNNAN TONGHAI EARTHQUAKE SEQUENCE OF AUGUST 2018          下载免费PDF全文

LI Tong  GUO Zhi  GAO Xing 《地震地质》1979,42(4):881-892

The August 2018 Tonghai earthquake sequence and focal mechanisms of the two main shocks about M_S5.0 were investigated through relocation of catalog data and inversion of event waveform recordings downloaded from the China National Seismic Network. The epicenter of 2018 Tonghai earthquake locates in the southern edge of Chuandian block, where the Xiaojiang Fault separates the Chuandian block from South China block in the east, and the Red River Fault separates the Chuandian block from the Indo-China in the southwest. These two faults blocked and absorbed the continuous southward movement of Chuandian block, significant tectonic stress has been built up in the southern tip of Chuandian block. As a seismicity active zone, Tonghai has been struck by a M7.0 strong earthquake in 1970. The August 2018 Tonghai earthquake is the major earthquake occurring in Tonghai and surrounding areas since the 1970 strong earthquake. Therefore, detailed focal mechanism study for 2018 Tonghai earthquake sequence is crucial for the earthquake relief effect for the Tonghai and surrounding area. In this study, we first relocate the epicenter of earthquake sequence by using the double difference relocation method, then we inverted focal mechanism for two main earthquakes with magnitude of ~5.0 by using the W-phase method. The relocated epicentral locations of Tonghai earthquake sequence show a NE-SW trend narrow band, predominant depth range of 5~10km and near vertical seismogenic fault. The focal parameters for the August 13 earthquake are: strike of 298.2°, a dip of 45.2°, a rake of -172.9° and strike of 203.2°, a dip of 84.9°, a rake of -45.0°, respectively, and magnitude of M_W=5.07; Focal parameters for the August 14 earthquake are: strike of 297.0°, a dip of 63.6°, a rake of -161.5° and strike of 198.5°, a dip of 73.5°, a rake of -27.7°, respectively, and magnitude of M_W=4.89. Combined analysis of the relocated epicentral locations and obtained focal mechanisms suggest that the seismogenic fault of the August 2018 Tonghai earthquake sequences could be related to the NE-striking Mingxing-Erjie Fault, and the temporal and spatial distribution characteristics of the earthquake sequence is consistent with the regional seismotectonic background.  相似文献   

基于一次机场雷击事件评估ADTD地闪定位性能     

包坤  赖晋科  李庆申  庞文静 《气象科技》2020,48(4):459-464

地闪定位系统性能评估可通过理论模拟,也可以基于人工触发闪电或者自然闪电直接观测事实。自然闪电由于发生的随机性和瞬时性,其直接观测事实很少,因此至今基于真实自然闪电回击的地闪定位系统性能评估还很欠缺。本研究基于2016年5月30日发生在广东潮汕机场的雷击事件展开调查,通过本次位置明确的机场雷击事件评估了该区域的ADTD地闪定位性能,并计算了不同站数定位时的定位误差情况。结果表明,ADTD闪电定位系统实时准确地记录了潮汕机场雷击事件,表明其实用性和准确性。通过重定位计算,发现在多站定位时可去除较大误差的站,保证定位结果的准确性,但定位结果并不一定是最优结果。  相似文献   

GPS测站所处构造位置的统计检验   总被引：4，自引：1，他引：3  

黄立人  马青 《大地测量与地球动力学》1999,19(4):27-31

运用方差分析理论,基于有约束和无约束平差所得到的方差的统计特征,给出了一种根据复测结果判别一组测站是否位于同一构造块体上的假设检验方法。该方法实质上是通过方差比,检验某组测站位于同一构造块体的约束是否正确,从而达到判别的目的。这一方法已实际应用于华北地区ＧＰＳ复测资料的分析［７］,取得了较好的效果。  相似文献