Attenuation of multiphase surface waves in the Basin and Range province, part I: Lg and Lg coda   总被引：1，自引：0，他引：1  

J. Xie  B. J. Mitchell 《Geophysical Journal International》1990,102(1):121-137

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粉蕉离体的快速繁殖技术     

吕庆芳 《广东海洋大学学报》2003,23(4):57-61

以粉蕉的吸芽为试材 ,进行了离体快速繁殖研究 ,结果表明 :以改良MS +BA4 .0mg/L(单位下同 ) +AD5.0 +NAA0 .1作诱导培养基 ,外植体褐变率低 ,芽的诱导率高 ,且芽的生长良好 ;以改良MS +BA3- 6 +NAA0 .1为继代培养基 ,可以获得较高的不定芽增殖率 ,在增殖过程中 ,给予一定的低温处理和变化调整BA的用量 ,可以保持较高的增殖率 (2 .6倍以上 ) ,而且芽的长势好 ;生根培养以 1/ 2MS +IBA1.0 +NAA0 .2 +AC1为宜。  相似文献   

Mode I crack propagation in concrete under fatigue: microscopic observations and modelling     

A. Toumi  A. Bascoul 《国际地质力学数值与分析法杂志》2002,26(13):1299-1312

In this study, three‐point bending tests were carried out on notched beams to investigate mode I crack propagation in plain concrete under fatigue. The first part of the study focused on microscopic observations of the crack growth features. Microscopic observations were made using the replica method associated with scanning electron microscopy (SEM). Observations of fatigue crack growth both on the surface and inside the specimens are presented as a comparison between the observed crack lengths and those estimated by the compliance calibration method. In the second part, a finite element model of mode I crack propagation under fatigue is presented. According to the cohesive crack concept, a cohesive force distribution on the crack at various loading stages is assumed, according to both the stress‐crack opening relation worked out by Hordijk (1991; Thesis, Technische Universiteit) and a new proposed relation with hysteresis loop. Finite element computation is used to evaluate the crack extension in the bending beams. Numerical predictions are discussed in comparison with experimental results. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Observations of shear-wave polarizations from rockbursts in a South African gold field: an analysis of acceleration and velocity recordings     

Gerhard Graham  Stuart Crampin  Luis M. Fernandez 《Geophysical Journal International》1991,107(3):661-672

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Solar Energetic Particle Event of 2005 January 20： Release Times and Possible Sources   总被引：1，自引：0，他引：1  

Gui-Ming Le  Yu-Hua Tang  Yan-Ben Han National Astronomical Observatories  Chinese Academy of Sciences  Beijing  Key Laboratory of Radiometric Calibration  Validation for Environmental Satellites  China Meteorological Administration  Beijing Department of Astronomy  Nanjing University  Nanjing National Center for Space Weather  China Meteorological Administration  Beijing 《中国天文和天体物理学报》2006,6(6):751-758

Based on cosmic ray data obtained by neutron monitors at the Earth's surface, and data on near-relativistic electrons measured by the WIND satellite, as well as on solar X-ray and radio burst data, the solar energetic particle (SEP) event of 2005 January 20 is studied. The results show that this event is a mixed event where the flare is dominant in the acceleration of the SEPs, the interplanetary shock accelerates mainly solar protons with energies below 130 MeV, while the relativistic protons are only accelerated by the solar flare. The interplanetary shock had an obvious acceleration effect on relativistic electrons with energies greater than 2 MeV. It was found that the solar release time for the relativistic protons was about 06:41 UT, while that for the near-relativistic electrons was about 06:39 UT. The latter turned out to be about 2 min later than the onset time of the interplanetary type III burst.  相似文献   

On failure criteria for anisotropic cohesive‐frictional materials     

S. Pietruszczak  Z. Mroz 《国际地质力学数值与分析法杂志》2001,25(5):509-524

Anisotropic failure criteria are formulated using two different approaches. The first one employs a spatial distribution of strength parameters and defines the failure condition in terms of traction components acting on the critical plane. The second one incorporates a microstructure tensor and the relevant mixed invariants. Both formulations are illustrated by some numerical examples. In particular, the variation of strength with orientation of the sample is examined for a series of uniaxial compression tests. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

The dipping antiplane crack     

Paul M. Davis  Leon Knopoff 《Geophysical Journal International》1991,106(3):581-585

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On verification of the new criterion of adiabaticity by numerical simulation of acoustic propagation through the polar front     

Y. Y. Wang  E. C. Shang 《中国海洋大学学报(英文版)》2002,1(1):25-28

To assess the adiabaticity of acoustic propagation in the ocean is very important for acoustic field calculation (forward problem) and tomographic retrieving (inverse problem). A new criterion of adiabaticity is proposed recently (Shang et al., 2001). In this paper, numerical simulation has been conducted for acoustic propagation through the Polar Front to verify the new criterion. Numerical results on the f (frequency)-m (mode number) plan demonstrate that the new criterion works very well for this extremely non-gradual ocean structure.  相似文献   

秋季中低纬低频振荡传播与长江中下游的连晴,连阴雨   总被引：1，自引：0，他引：1  

王秀祥  翟小玲 《南京气象学院学报》1997,20(4):534-540

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常州市地表沉降观测与成果分析     

朱微  刘福春 《测绘工程》2007,16(6):54-57

从地面沉降观测的必要性出发,进行水准观测数据的处理,平差基准选定的探讨,并对常州市行政区域内历年来的水准观测数据应用时空分析,形变数字特征值及速率的非线性变化等方法,分析常州市行政区域内地面垂直位移的发展过程及特征,得出常州市区域内沉降漏斗迁移路径的变化规律,为常州市今后的地面沉降分析提供参考。最后讨论了引起地面沉降的原因,提出今后的弥补措施。  相似文献