滇西实验场微震衰减与场地响应   总被引：1，自引：1，他引：1  

叶建庆 《地震研究》1993,16(1):1-12

本文使用滇西实验场区PDR—2数字化台网的77个微震(M_L<3)资料,分析了场区内的下关、洱源、邓川、双廊、乔后和漾濞6个台站的微震振幅谱。采用振幅谱频率比方法,研究区域衰减效应和局部场地响应。在一固定接收器场地条件下对不同距离不同方向的几十个地震,测量5Hz和20Hz谱振幅比,估计场区内地壳上部P波和S波的Q值。6个台站分别属于不同的构造背景,各台Qp和Qs值差异与局部区域构造差异强烈相关,在所研究的小区域范围内衰减机制和场地响应差异可分为三个条带状区域。6个台站的平均Qp为210,Qs为460。Qs≈2.2Qp,与Frankel估计的Qp≈Qs对比,表明地壳上部的衰减机制存在明显的地区性差异。场地响应的另一主要特征是谱的拐角频率,对于浅源微震拐角频率不是震源距和地震位置的函数,统计结果表明,各场地具有明显的优势拐角频率,它与局部场地构造差异相关。  相似文献   

PMOE精密行星历表研究进展     

李广宇  倪维斗  田兰兰 《紫金山天文台台刊》2003,(1)

本文扼要介绍了PMOE行星历表研究当前的进展和工作 ,给出了PMOE2 0 0 2与DE40 5历表的比较。  相似文献   

网型结构对GPS定位精度的影响     

姜晨光  朱佑国  黄奇璧  吴晓峰  汪凯 《现代测绘》2005,28(5):13-14,19

GPS观测实践证明GPS的网型结构对GPS定位精度具有显著的影响,为了弄清网型结构与GPS定位精度间的关系,在鲁西北平原建立了高精度的专用实验网,专用实验网的三维坐标借助精密电子全站仪和精密水准仪获得.在专用试验网上,通过不同的组网形式,对GPS定位精度进行了对比试验,初步摸清了网型结构对GPS定位精度的影响规律.  相似文献   

Assessment of Cyto‐ and Genotoxic Effects of a Variety of Chemicals Using Saccharomyces cerevisiae     

Marcel Schmitt  Georg Gellert  Jost Ludwig  Hella Lichtenberg‐Frat 《洁净——土壤、空气、水》2005,33(1):56-63

Saccharomyces cerevisiae as the most simple eukaryotic organism is broadly accepted as a laboratory model organism. For the detection of potential toxic effects of pure compounds and complex composed samples like wastewater a miniaturised short‐term in vitro cyto‐ and genotoxicity screening assay was developed. The assay based on genetically modified S. cerevisiae cells deleted in the prominent drug efflux transporters Pdr5, Snq2, and Yor1 that facilitate pleiotropic drug resistance. The yeast strain devoid of these proteins that mediate the efflux of structurally diverse hydrophobic compounds exhibited an increased sensitivity to a variety of organic compounds. The DNA damage inducible RAD54 promoter fused to a yeast optimized derivative of the GFP (green fluorescent protein) gene from the jelly fish Aequorea victoria served as an indicator of DNA damage in this strain. Various pure compounds including the direct‐acting genotoxins methyl‐N‐nitro‐N‐nitrosoguanidine (MNNG), 4‐nitroquinoline‐N‐oxide (4‐NQO), methyl methanesulfonate (MMS) and hydroxyurea as well as the heavy metals cadmium and chromium(VI), the insecticide lindane and the central nervous system stimulant caffeine were tested exhibiting dose dependent induction of green fluorescence. All compounds were in parallel examined for chronic toxicity. A bioassay detecting simultaneously geno‐ and cytotoxic effects of potential toxicants in a single assay can be an important tool with a variety of applications in environmental monitoring and aquatic ecotoxicology. By partial automation and miniaturisation to microtitration scale this bioassay enables sensitive and fast biomonitoring for a multitude of samples.  相似文献   

Detection of model voids by identifying reverberation phenomena in GPR records   总被引：2，自引：1，他引：2  

Lev Kofman  Amit Ronen  Sam Frydman   《Journal of Applied Geophysics》2006,59(4):284-299

In order to improve the reliability of the ground penetrating radar (GPR) method in identifying subsurface sinkholes and karst cavities, laboratory investigations have been performed. The main objective of this work was to examine the relationship between horizontal/vertical voids dimensions and wavelengths of various antennas, and the corresponding GPR responses. Emphasis was given to the investigation of the factors that cause the appearance of reverberation phenomena in the signal pattern.The tests were conducted in 5 m × 10 m area by 2-m-deep trench filled with homogenous, dry sand. The voids models (empty fiberglass cylinders in diameters of 0.6 m, 1.0 m, 1.5 m and 2.4 m, with various heights) were buried vertically with their tops at depths of between 0.7 and 1.5 m. Investigations were performed for the various model conditions by towing 500, 300 and 100 MHz antennas along a pre-established grid, for the various model conditions.The GPR data collected using the 500 MHz bistatic antenna above the 1.0-m- and the 1.5-m-diameter cylinders, and using the 300 MHz bistatic antenna above the 1.5-m-diameter cylinder, confirmed the presence of a reverberation phenomenon, i.e. a strong convex signal pattern, containing a series of high amplitude extending oscillations with reduced frequency.Based on past practical GPR experience of void detection and presently obtained experimental data, two rules of thumbs may be adopted for the prediction of the appearance of resonant radar pictures:

1. The void diameter larger than the wavelength in air of the antenna used.

2. The vertical size of the empty void not significantly smaller than its horizontal dimension.

The strong reverberations generated by the inner surface of the void targets were found to approximate standing waves generated in cylindrical waveguides and waveguide resonators. The theoretical, experimental and practical results obtained concur.  相似文献   

抽水对地下水位、汞、氡的影响——以古城试验为例          下载免费PDF全文

高立新  车用太  纪建国  闫海滨  王海义  刘成龙  王翠萍  于红梅 《地震工程学报》2006,28(2):144-148

介绍了在内蒙古古城进行的同层抽水对水位、水温(地热)、气氡、气汞、水氡与水汞影响的观测试验及其结果。结果表明,抽水对井水位影响最大,影响距离可达近1 km;对水温影响较为明显;对气氡、气汞的影响不明显;水氡与水汞的动态可能有一定影响,但影响幅度不大。  相似文献   

新疆下坂地水库坝基防渗墙试验研究   总被引：1，自引：0，他引：1  

覃新闻  龚木金  刘建发  王根龙 《工程地质学报》2006,14(4):570-575

新疆下坂地水利枢纽工程地处高寒、高海拔的山区,坝基覆盖层厚度达147.95m,透水性强,易坍塌和漏浆,块石坚硬,坝基防渗处理难度罕见。针对这一工程问题进行了坝基防渗墙试验研究,结果表明,以大深度混凝土防渗墙为主墙,下接帷幕灌浆的墙幕结合方案。本文针对新疆下坂地深厚覆盖层坝基防渗墙进行了试验研究,找出了防渗墙有效的施工深度及合理的施工方法,从而为坝基防渗墙设计施工提供了可靠的依据。  相似文献   

变刚度半主动结构振动控制的试验研究   总被引：8，自引：0，他引：8  

李敏霞  刘季 《地震工程与工程振动》1998,18(4):90-95

本文成功地完成了五层框架的变刚度半主动结构振动控制的模拟地震振动试验,这不仅是我国的第一个变刚度半主动结构振动控制的试验,在国际上也是少数几例之一。本文介绍了试验系统的构成,试验内容,试验结果的分析及试验结论等。  相似文献   

Ionospheric signature of surface mine blasts from Global Positioning System measurements     

Eric Calais  J. Bernard Minster  Michelle Hofton  & Michael Hedlin 《Geophysical Journal International》1998,132(1):191-202

  相似文献   

结构抗震性能评估的动测方法研究   总被引：1，自引：0，他引：1  

姚志强 《高原地震》1996,(1)

本文通过对工程结构，特别是高层建筑的动力特性参数的现场实测，结合已有的室内、室外强度、抗震承载力实验结果，为工程结构抗震性能及使用安全性的判定提供一套简便实用的方法，继而为震害预测、抗震设计、抗震加固、房屋安全鉴定等提供较客观的依据。  相似文献