The response of an elastic half‐space under a momentary shear line impulse

The response of an ideal elastic half‐space to a line‐concentrated impulsive vector shear force applied momentarily is obtained by an analytical–numerical computational method based on the theory of characteristics in conjunction with kinematical relations derived across surfaces of strong discontinuities. The shear force is concentrated along an infinite line, drawn on the surface of the half‐space, while being normal to that line as well as to the axis of symmetry of the half‐space. An exact loading model is introduced and built into the computational method for this shear force. With this model, a compatibility exists among the prescribed applied force, the geometric decay of the shear stress component at the precursor shear wave, and the boundary conditions of the half‐space; in this sense, the source configuration is exact. For the transient boundary‐value problem described above, a wave characteristics formulation is presented, where its differential equations are extended to allow for strong discontinuities which occur in the material motion of the half‐space. A numerical integration of these extended differential equations is then carried out in a three‐dimensional spatiotemporal wavegrid formed by the Cartesian bicharacteristic curves of the wave characteristics formulation. This work is devoted to the construction of the computational method and to the concepts involved therein, whereas the interpretation of the resultant transient deformation of the half‐space is presented in a subsequent paper. Copyright © 2003 John Wiley & Sons, Ltd.     

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

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.     

云南会泽超大型铅锌矿床成因研究中的几个问题

位于川-滇-黔铅锌多金属成矿域中南部云南会泽超大型铅锌矿床可能是一种新的铅锌矿床类型，该类铅锌矿床明显特征是规模大、品位富、伴生有用元素多，暗示其成矿环境较为特殊。从成矿时代、成矿物质来源、成矿流体来源与演化，以及峨眉山玄武岩与成矿的关系等方面分析了会泽超大型铅锌矿床的研究进展及国内外研究现状，认为矿床成矿时代与西南大面积峨眉山玄武岩成矿时代相近，成矿物质和成矿流体具有“多源性”，成矿流体存在均一化过程，区域大规模流体运移在该区铅锌成矿过程中具有重要意义，峨眉山玄武岩岩浆活动与铅锌成矿具有密切的成因联系，矿床可能为“均一化成矿流体贯入成矿”的产物。     

由空间直角坐标计算大地坐标的简便公式

对大地测量教科书中给出的空间三维直角坐标与大地坐标的转换公式进行了大量的计算与分析，总结得出一组由空间直角坐标计算大地坐标的简便公式。     

差分VLBI测量的一种实现方案

差分VLBI通过交替观测目标天体和参考天体,将共同的误差因素从观测量中扣除,能够实现高精度的相对定位,因而在深空探测中有重要作用。然而,差分VLBI高精度的实现要求目标天体和参考天体的角距很近,这大大限制了其应用。讨论设计了差分VLBI测量的一种实现方案,利用多颗参考源的观测内插出目标源的非几何时延修正,放宽了对目标源和参考源的角距限制。该方案在S波段对目标源非几何时延的修正精度可以达到1 ns水平。     

考虑土-结构相互作用的振动台实时子结构试验仿真分析

本文基于状态空间方程进行了实时子结构试验的初步探索,提出了一种新的实时子结构试验方法。通过simulink仿真发现,这种方法能很好地再现整体分析的结构反应。最后,对考虑土-结构相互作用的振动台实时子结构试验进行了仿真分析。     

SUSTAINABLE DEVELOPMENT FACING CHALLENGESIN 21ST CENTURY

ISUSTAINABLE DEVELOPMENT IS UNDER UN－guiding human forward．he author pointed out manyCEASINGCHALLENGES times that sustainable developmentwas a correctstrategic selectlonforhumanfuture and It representedaThe Zlst Century has come，people have many newdevelopmentoutlook，strategic vie呷olntandvalueforecasts and long for a wonde山lprospect．The 21st（CHEN，1997；200a；200b）．Century lsa bio－sclentmc era，an economic global－The authoralso pointed out th…     

川东地区碳酸盐岩超压与天然气富集关系研究

地层流体超压的形成、演化及分布与油气成藏的主要石油地质过程有着千丝万缕地联系。由于碳酸盐岩本身的复杂性，其超压的成因及研究方法不能简单地借用“欠压实”的原理。本文从对比砂泥岩和碳酸盐岩在成压机理上的差异性入手，详细探讨了川东地区碳酸盐岩成压的各种机理，指出成烃作用是造成区域性超压的最主要因素；并结合该区超压平面上的分区性及纵向上的分带性，论述了各区、带超压与气藏分布的内在联系，总结出该区超压与天然气富集的关系。     

Measuring proton energies and fluxes using EIT (SOHO) CCD areas outside the solar disk images

An indirect proton flux measuring tool based on discrimination of the energy deposited by protons in 128 × 128 pixel EIT CCD areas outside the solar disk images is presented. Single pixel intensity events are converted into proton incident energy flux using modeled energy deposition curves for angles of incidence ±60° in four EIT spatial areas with different proton stopping power. The extracted proton flux is corrected for both the loss of one‐pixel events in the range of angles of incidence as well as for the contribution to the single pixel events resulting from scattered middle‐energy protons (low‐energy or high‐energy particles are stopped by the EIT components or pass through them, accordingly). A simple geometrical approach was found and applied to correct for a non‐unique relation between the proton‐associated CCD output signal and the incident proton energy. With this geometrical approximation four unique proton incident energy ranges were determined as 45–49, 145–154, 297–335, and 390–440 MeV. The indirect proton flux measuring tool has been tested by comparing Solar Energetic Particles (SEP) flux temporal profiles extracted from the EIT CCD frames and downloaded from the GOES database for the Bastille Day (BD) of 2000 July 14 and the more recent 2005 January 20 events. The SEP flux temporal profiles and proton spectra extracted from the EIT in the relatively narrow energy ranges between 45 and 440 MeV reported here are consistent with the related GOES profiles. The four additional EIT extracted ranges provide higher energy resolution of the SEP data. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)