Moment tensors of acoustic emissions in shear faulting under plane-strain compression     

Fernanda C. S. Carvalho  Joseph F. Labuz   《Tectonophysics》2002,356(1-3)

The study of localized failure under controlled conditions can be accomplished within a laboratory setting with the University of Minnesota plane-strain compression apparatus. The device provides an opportunity to observe shear faulting and to compare displacements from acoustic emission (AE) sources with global measurements. A biaxial compression test on a sandstone specimen was performed with monitoring of AE. The plane-strain test showed that the shear fault was not formed until after peak load. Compaction of the shear fault was observed from the axial and lateral measurements of displacement and the orientation of the failure plane. The AE events were modeled as displacement discontinuities. The complicated deconvolution process for the transducer transfer function was eliminated by using a simplified calibration procedure. The sources of the postpeak events were characterized as being caused predominantly by slip in the direction of the global failure plane, although components of displacement associated with closing were identified. To provide an order of magnitude estimate of the slip, the field observation of a 10⁻⁴ strain drop over the seismic area was assumed. The tangential displacement from 110 AE events was estimated to be 0.01 mm. During the same period of time, the displacement along the shear fault from global measurements was 0.03 mm.  相似文献   

On saturation of magnesian cordierite with alkanes at high temperatures and pressures     

T. A. Bulbak  G. Yu. Shvedenkov  G. G. Lepezin 《Physics and Chemistry of Minerals》2002,29(2):140-154

 Incorporation of hydrocarbons (CH₄, C₂H₆, C₃H₈, C₄H₁₀) in cordierite channels was experimentally studied at 700 °C and at pressures from 200 to 1000 MPa, (avoiding recrystallization). The maximum concentrations of hydrocarbons determined by gas chromatographic analysis are CH₄=78.3, C₂H₆=134, C₂H₄ + C₂H₆=26, C₃H₈=28, C₄H₁₀=32, C₅H₁₂=23, and C₆H₁₄=7 × 10⁻³ wt%). According to IR spectroscopy data, the channel forms of hydrocarbons differ from the forms on the surface. As a result of interactions with the framework oxygen, normal hydrocarbons are converted to saturated oligomers and their fragments. Small amounts of water molecules of the first and second types (up to 0.3 wt%) are formed in the same way. As pressure grows from 200 to 1000 MPa, the total content of structural hydrocarbons is nearly doubled. Special runs on cordierite saturation in mixtures of hydrocarbons with water showed that low contents of hydrocarbons in natural cordierites correspond to their large concentrations in fluid. Received: 7 May 2001 / Accepted: 17 July 2001  相似文献   

自动车辆定位导航系统中传感器的误差分析   总被引：1，自引：0，他引：1  

徐爱功 《测绘工程》1997,6(1):36-39

对国界定位导航系统中几种常见的辅助传感器所产生的误差进行了分析，导出了不同传感器的误差模型。这些误差模型是估计车辆位置的扩展卡尔曼滤波器的基础，同时也为选择适当的传感器提供了理论根据。  相似文献   

RETRIEVING OVER-OCEAN PRECIPITABLE WATER FROM THE SSM/I MEASUREMENTS WITH SEVERAL REGRESSION ALGORITHMS     

陈洪滨  孙海冰  王普才  吕达仁 《Acta Meteorologica Sinica》1998,(4)

A collocated SSM/I and radiosonde measurement data set provided by the NASDA(Japan)was used to retrieve the total precipitable water(PW)over oceans.The retrieval results obtainedwith several regression algorithms were compared against the radiosonde measurements.It isshown that:(a)the routinely operational algorithm of Alishouse et al.(1990)yields significantunderestimation in high PW regime and overestimation in low PW regime;(b)a cubic correctionby Colton and Poe(1994)is not sufficient and globally improves slightly the retrieval results;and(c)the regression algorithm with the form of brightness temperature(T_b)function In (280-T_b)gives a little largely scattered retrievals in whole PW range but without considerable over-andunderestimates in low and high PW regimes.To improve the estimation of the oceanic precipitablewater from the SSM/I measurements,a composite algorithm with different forms of T_b function inlow.medium and high PW regimes is proposed and tested.  相似文献   

CAW600型自动气象站蒸发传感器异常数据分析     

容军 《气象研究与应用》2004,25(4):48-50

对现场校验超声波蒸发传感器所得的异常数据进行分析,并对分析进行验证,找出了数据异常的原因,同时提出避免此类错误的方法。  相似文献   

InSAR可检测的最大最小变形梯度的函数模型研究   总被引：5，自引：4，他引：1       下载免费PDF全文

蒋弥  李志伟  丁晓利  朱建军  冯光财  尹宏杰 《地球物理学报》2009,52(7):1715-1724

InSAR干涉图中的相位噪声是相干性和视数的函数.InSAR能检测的地表最大最小形变梯度,除了受到InSAR硬件的限制外,还直接受到InSAR干涉图中噪声强弱的影响.此外,由于多视处理会改变像元的大小,也会引起可检测的最大最小形变梯度显著变化.本文研究了InSAR可检测的地表最大最小形变梯度与相干性和视数的关系,并建立了视数为1、5和20时（ERS和ENVISAT常采用的多视数）InSAR可检测的最大最小形变梯度的经验函数模型.最后,本文用伊朗Bam地区的Enivsat ASAR数据进行了试验,结果表明该模型能够准确地判别不同视数和相干性情况下地表变形能否被InSAR技术所检测.与Baran只考虑了相干性的模型相比,本文的模型适用范围更广.  相似文献   

用TRMM/LIS资料分析长江三角洲地区的闪电活动   总被引：10，自引：2，他引：10       下载免费PDF全文

戴建华  秦虹郑杰 《应用气象学报》2005,16(6):728-736

统计分析了1998~2004年长江三角洲(长三角)地区由星载闪电成像传感器(LIS)观测的闪电资料，发现了该地区LIS闪电活动的一些时空分布特征:闪电次数的年差异较大，最多年份是最少年份的3倍；7~8月盛夏季节是闪电高发期，闪电次数和日数分别占全年的70%和60%；闪电高发期间的抬升指数(IL)小于-2℃；7~8月闪电主要集中于午后，3~6月则集中在上半夜；上海地区单日LIS闪电次数超过8次时，多伴有强对流天气和短时强降水；长三角地区的闪电活动区主要分布在上海的东部，部分沿江、沿湖地区和浙江的龙门山等山区；水域闪电少于陆地，大城市城区下风方向闪电活动较多，部分雷暴刚入海时有加强的趋势。分析表明:太阳辐射的季节变化和日变化等是造成闪电时间分布的主要原因；地形的动力作用和下垫面的物理特性及其差异是造成气候意义上中小尺度闪电空间分布差异的主要原因。文章对LIS闪电定位资料进行了探测效率订正，根据LIS注视时间计算了闪电密度，并与地基闪电定位资料和多普勒天气雷达资料进行了对比。LIS闪电活动特征的分析，对雷暴预警和防灾减灾有指导意义。  相似文献   

资源三号卫星传感器校正产品的精度评估     

戴海涛  范大昭  雷蓉  刘楚斌  孙晓昱 《测绘与空间地理信息》2014,(5):42-46

分别选取资源三号(ZY-3)卫星平地和山地区域的前后视影像,量测20个GPS点作为控制点和检查点,对卫星传感器校正产品定位精度进行验证。通过区域网平差算法对传感器校正产品(SC)自带的有理函数模型(RPC)进行优化,消除系统误差。实验结果表明:在地形平坦地区ZY-3卫星SC产品的平面定位精度可达3.275 m,高程定位精度可达1.686 m;在地形起伏较大的山区平面定位精度可达4.335 m,高程定位精度可达3.628 m,满足1∶50 000地形图测绘的要求。  相似文献