Flow resistance in concentrated overland flow on rough slope surfaces     

J. M. Roels 《地球表面变化过程与地形》1984,9(6):541-551

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Experimental Study of Mechanical Behaviour of Rock Joints Under Cyclic Loading   总被引：3，自引：5，他引：3  

M. K. Jafari  F. Pellet  M. Boulon  K. Amini Hosseini 《Rock Mechanics and Rock Engineering》2004,37(1):3-23

Summary Evaluation of the effects of small repetitive earthquakes on the strength parameters of rock joints in active seismic zones is of interest of the designers of underground constructions. In order to evaluate these effects, it is necessary to study the behaviour of rock joints under dynamic and cyclic loadings. This paper presents the results of a systematic study on the behaviour of artificial rock joints subjected to cyclic shearing. More than 30 identical replicas have been tested using triaxial compression devices under different conditions of monotonic and cyclic loading. At the first stage a few samples have been tested in monotonic loading modes under various confining pressures and rate of displacement. In the second series of tests, small cyclic loads were applied on the samples for increasing number of cycles, frequency levels and stress amplitudes. These were then followed by monotonic loading again. The variations of maximum and residual shear strengths for each test have been studied. The results show increase of shear strength as a result of the increase in confining pressure and they display decrease of shear strength due to the increase of rate of loading, number of cycles, frequency levels and stress amplitudes.  相似文献   

云室中两种检测冰晶方法的比较   总被引：4，自引：1，他引：4       下载免费PDF全文

酆大雄 《气象》2003,29(1):17-19

通过实验比较了在云室中检测冰晶的两种方法－糖盘法和玻片法，结果表明玻璃片测到的冰晶数比糖盘高数倍，讨论了两种方法检测的上下限，优缺点及应用范围。  相似文献   

测站位移固体潮效应的潮波公式     

张捍卫  郑勇  赵方权 《测绘学报》2003,32(3):213-218

固体潮对测站位移的影响是空间大地测量和天文地球动力学研究的重要组成部分。对目前常用的3种引潮力位展开形式进行了总结，并列出了它们各自的实用公式。不同于IERSl996和IERS2000推荐的固体潮对测站位移影响的理论模型，独立于天体历书而基于精密引潮力位展开，直接给出了在亚毫米精度下的潮波公式，利用新的精密引潮位展开在亚毫米精度上重新计算了永久性潮汐的影响。可为高精度的空间大地测量和天文地球动力学的研究提供理论依据和参考。  相似文献   

框剪结构抗震剪力墙数量的优化准则证明   总被引：10，自引：0，他引：10  

穆翠玲  王文俊  陈存恩 《世界地震工程》2003,19(1):154-157

将框剪结构连续化，按振型组合法证明了同时满足规范允许顶点侧移和层间侧移角的最少抗震剪力墙数量为最优剪力墙量，相应的设计为最优设计。  相似文献   

Seismological study on the crustal structure of Tengchong volcanic-geothermal area     

王椿镛  楼海  吴建平  白志明  皇甫岗  秦嘉政 《地震学报(英文版)》2002,15(3):247-259

Introduction The Tengchong volcanic-geothermal area is located on the northeast edge of the collision zone between Indian and Eurasian plates, and belongs to Eurasian volcanic zone (the MediterraneanHimalayanSoutheast Asia volcanic zone). In Tengchong area, the Quaternary volcanic, geothermal and seismic activities are all intensive. These phenomena have been drawing the attention of many geoscientists in the world. Their studies are concerned with geology, geophysics, geochemistry, and cr…  相似文献   

Microbial production of CO2 in red soil in Stone Forest National Park   总被引：2，自引：0，他引：2  

LIANGFuyuan SONGLinhua TANGTao 《地理学报(英文版)》2003,13(2):250-256

Lunan stone forest is a kind of typical karst in China,Which is mainly developed under red soil.In the winter of 1999,three study sites were chosen in stone forest national park according to vegetation cover,geomporphologic location and soil types,CO2 concentration was measured with Gastec punp at different dephts of soil (20,40,60cm) and at the same time soil samples were gatered and soil properties such as soil moisure,pH,soil organic content were analyzed and the total nmuber of viable microbes were counted in laboratory,In the study,dependent variable was chosen as the mean soil log(PCO2),and soil properties were chosen as the independent variables.Multiple stepwise regression analysis showed that the totla amount of microbes and soil moisture are the best indicators of the CO2 production,With the equation LOG(PCO2)=-0.039(TNM)-0.056 (Mo) 1.215 accounting for 86% of the variation of the soil CO2 concentration,where TNM is the total number of microbes in teh soil and Mo is the moisture of soil sample.  相似文献   

Aerosol concentration measurement with multiple light scattering system and laser aerosol spectrometer     

Wladyslaw Witold Szymanski 《Atmospheric Research》2002,62(3-4)

The performance of two different optical concentration-measuring techniques was investigated over a concentration range starting with about 10² cm⁻³ and extending over more than four decades. Both instruments are capable of real-time counting, however due to their particular design-single particle counter and ensemble particle-measuring system—they operate in overlapping, but different concentration ranges. The upper, coincidence-free counting limit for the single particle counter used in this study was established to be in the order of 10⁴ cm⁻³. The ensemble technique was found to be functional and stable for concentrations of about 10³ cm⁻³ and limited by the onset of multiple scattering at concentrations nearby 2×10⁶ cm⁻³. Within the determined boundaries, both techniques proved to provide reliable aerosol concentration data.  相似文献   

用太阳活动拟合近2000年的温度变化   总被引：5，自引：4，他引：5  

王钟睿  高晓清  汤懋苍 《高原气象》2002,21(6):552-555

利用两个反映太阳活动的指标－太阳黑子相对数及太阳黑子周期长度－来拟合近2000年我国的温度变化，其结果与近2000年，特别是近700年来温度变化的总趋势基本一致。同时拟合了120年来北半球温度的演变，结果表明：太阳活动是引起10^1年以上气温变化的基本因素，近十多年来温室气体的作用似乎不可忽略。  相似文献   

耀斑的短期生物效应   总被引：3，自引：0，他引：3       下载免费PDF全文

聂清香  季国平  黄萍 《地球物理学报》2002,45(4):470-474

为研究太阳耀斑的短期生物效应,统计分析了198-199年中16万婴儿出生日与光学耀斑的关系. 结果表明,婴儿出生数的变化与耀斑辐射的能量,以及能量到达地球的时间有关. 太阳活动较平稳年白天爆发的各级耀斑的当天都对应着一个平均出生数高峰,而且耀斑的亮度和面积越大,对应的出生峰值越大. 2B耀斑当天平均出生数超过前后21d总均值的13.6髎,具有p＜0.001的统计高度显著性水平. 这些出生高峰与耀斑的电磁和高能辐射有关. 2B、2N和1B三类耀斑后的第2-4d还有一个出生峰,它们与耀斑引发的地球物理变化的时间符合.  相似文献