DEVELOPMENT STRATEGIES OF WATER AND LAND RESOURCES IN THE HEXI REGION,CHINA     

肖洪浪  高前兆  李福兴 《中国地理科学(英文版)》1996,(1)

ＤＥＶＥＬＯＰＭＥＮＴＳＴＲＡＴＥＧＩＥＳＯＦＷＡＴＥＲＡＮＤＬＡＮＤＲＥＳＯＵＲＣＥＳＩＮＴＨＥＨＥＸＩＲＥＧＩＯＮ，ＣＨＩＮＡ肖洪浪，高前兆，李福兴ＤＥＶＥＬＯＰＭＥＮＴＳＴＲＡＴＥＧＩＥＳＯＦＷＡＴＥＲＡＮＤＬＡＮＤＲＥＳＯＵＲＣＥＳＩＮＴＨＥ...  相似文献   

Elastic solutions for stresses in a transversely isotropic half‐space subjected to three‐dimensional buried parabolic rectangular loads     

Cheng‐Der Wang  Jyh‐Jong Liao 《国际地质力学数值与分析法杂志》2002,26(14):1449-1476

In many areas of engineering practice, applied loads are not uniformly distributed but often concentrated towards the centre of a foundation. Thus, loads are more realistically depicted as distributed as linearly varying or as parabola of revolution. Solutions for stresses in a transversely isotropic half‐space caused by concave and convex parabolic loads that act on a rectangle have not been derived. This work proposes analytical solutions for stresses in a transversely isotropic half‐space, induced by three‐dimensional, buried, linearly varying/uniform/parabolic rectangular loads. Load types include an upwardly and a downwardly linearly varying load, a uniform load, a concave and a convex parabolic load, all distributed over a rectangular area. These solutions are obtained by integrating the point load solutions in a Cartesian co‐ordinate system for a transversely isotropic half‐space. The buried depth, the dimensions of the loaded area, the type and degree of material anisotropy and the loading type for transversely isotropic half‐spaces influence the proposed solutions. An illustrative example is presented to elucidate the effect of the dimensions of the loaded area, the type and degree of rock anisotropy, and the type of loading on the vertical stress in the isotropic/transversely isotropic rocks subjected to a linearly varying/uniform/parabolic rectangular load. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

The influence of a non‐associated flow rule on the calculation of the factor of safety of soil slopes     

Yu‐Jie Wang  Jian‐Hua Yin  C. F. Lee 《国际地质力学数值与分析法杂志》2001,25(13):1351-1359

This paper presents a method that incorporates a non‐associated flow rule into the limit analysis to investigate the influence of the dilatancy angle on the factor of safety for the slope stability analysis. The proposed method retain's the advantage of the upper bound method, which is simple and has no stress involvement in the calculation of the energy dissipation and the factor of safety. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

专项气象服务经济效益的评价理论与技术     

蔡久忠  徐芬 《成都信息工程学院学报》1997,(4)

当前，由于缺乏对气象服务投入量与产出量准确而完整的统计，要对气象服务的各种经济效益作出总体评价是困难的。然而，在专项气象服务中，却不乏原始、完整而准确的资料。作者从此出发，讨论了专项气象服务经济效益评价的理论。并通过实地调查，以彭州市气象局几项专项气象服务为例探讨了评价技术。  相似文献   

Abundance and isotopic composition of noble gases in metal and graphite of the Bohumilitz IAB iron meteorite     

Teruyuki MARUOKA  Jun‐ichi MATSUDA  Gero KURAT 《Meteoritics & planetary science》2001,36(5):597-609

Abstract— Abundances and isotopic compositions of noble gases in metal and graphite of the Bohumilitz IAB iron meteorite were measured. The abundance ratios of spallogenic components in metal reveal a ³He deficiency which is due to the diffusive loss of parent isotopes, that is, tritium (Tilles, 1963; Schultz, 1967). The diffusive loss likely has been induced by thermal heating by the Sun during cosmic‐ray exposure (～160 Ma; Lavielle et al, 1999). Thermal process such as impact‐induced partial loss may have affected the isotopic composition of spallogenic Ne. The ¹²⁹Xe/¹³¹Xe ratio of cosmogenic components in the metal indicates an enhanced production of epi‐thermal neutrons. The abundance ratios of spallogenic components in the graphite reveal that it contained small amounts of metal and silicates. The isotopic composition of heavy noble gases in graphite itself was obtained from graphite treated with HF/HCl. The isotopic composition of the etched graphite shows that it contains two types of primordial Xe (i.e., Q‐Xe and El Taco Xe). The isotopic heterogeneity preserved in the Bohumilitz graphite indicates that the Bohumilitz graphite did not experience any high‐temperature event and, consequently, must have been emplaced into the metal at subsolidus temperatures. This situation is incompatible with an igneous model as well as the impact melting models for the IAB‐IIICD iron meteorites as proposed by Choi et al. (1995) and Wasson et al (1980).  相似文献   

Radar observations of Itokawa in 2004 and improved shape estimation     

Steven J. Ostro  Lance A. M. Benner  Christopher Magri  Jon D. Giorgini  Randy Rose  Raymond F. Jurgens  Donald K. Yeomans  Alice A. Hine  Michael C. Nolan  Daniel J. Scheeres  Stephen B. Broschart  Mikko Kaasalainen  Jean‐Luc Margot 《Meteoritics & planetary science》2005,40(11):1563-1574

Abstract— We present June 2004 radar images of asteroid 25143 Itokawa (1998 SF36) that improve upon the longitude‐latitude coverage of images obtained in 2001 by Ostro et al. (2004) and use the 2001–2004 data to refine that paper's constraints on Itokawa's shape. The 2004 images, the first of the asteroid's southern side, look distinctly different from the 2001 images, revealing leading edges that are much more curved and rugged than the nearly convex leading edges seen at northern latitudes in 2001. Itokawa is shaped like a slightly asymmetrical, bent, lumpy ellipsoid with dimensions along the principal axes within 10% of 594 times 320 times 288 m. To illustrate the uncertainty space associated with shape reconstruction from images with suboptimal orientational coverage, we present two alternative three‐dimensional models of the object.  相似文献   

Depositional and post‐depositional history of warm stage deposits at Knocknacran,Co. Monaghan,Ireland: implications for preservation of Irish last interglacial deposits     

A. P. M. Vaughan  L. A. Dowling  F. J. G. Mitchell  S.‐E. Lauritzen  A. M. McCabe  P. Coxon 《第四纪科学杂志》2004,19(6):577-590

Organic‐rich deposits, uncovered during overburden removal from mantled gypsum karst at Knocknacran opencast gypsum mine, Co. Monaghan, are the best candidate to date for a last interglacial record in Ireland. The two till and organic‐rich deposits (preserved at different quarry elevations) were emplaced on to a Tertiary dolerite surface during high‐energy flood events and subsequently folded and faulted by movement towards sinkholes in underlying gypsum. Uranium–thorium disequilibrium dating suggests that the organic‐rich deposits in the upper section were hydrologically isolated at ca. 41 ka and those in the lower section at ca. 86 ka. Interpretation of the pollen content, although tentative because of the depositional and post‐depositional history of the material, suggests that the organic material originated in a warm stage possibly warmer than the post‐Eemian interstadials. The unusual setting of preservation may indicate that in situ, last interglacial deposits have generally been removed by erosion in Ireland. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

概论机场能见度的准确预报     

张晓晖 《成都信息工程学院学报》2002,17(3):166-169

通过对影响能见度的因素的分析，提出了一种能见度预报方法－综合分析法，极大地提高了能见度的预报准确率。  相似文献   

伪随机码调制的CW半导体激光雷达试制报告     

肖弟权  何建新  邱万智 《成都信息工程学院学报》1993,(4)

本文报告一种用半导体激光器作光源,用子脉冲宽度100ns,长度为511的周期伪随机码对半导体激光器的输出作幅度调制;APD作光电检测器,高速数字信号处理器TMS320C25作信号处理的激光雷达组成方案和试作样机的实验结果。  相似文献   

Researches in China on the Effects of Tides on the Earth Rotation     

Naiyuan Xiao  Yifei Xia 《Celestial Mechanics and Dynamical Astronomy》2003,87(1-2):3-12

In this paper the tidal phenomena on the Earth are concisely specified, including solid tides, ocean tides and atmospheric tides due to the luni-solar tide-generating force, and the Earth pole tide due to the motion of the Earth's rotation axis (polar motion); as well as their effects on the Earth rotation. The outcomes of scientific researches of Chinese astronomers on these topics are described in some detail. These researches deal with the mechanisms responsible for tidal effects on the earth rotation, and on the measurements of the Earth rotation parameters. Finally, the effects discovered by Chinese researchers on the measurements of the period and change in period of pulsars are discussed. These effects are very small in magnitude but not negligible.  相似文献