Numerical simulation of ductile shear localization: Plastic‐flow network and slip‐line field     

Sheng‐zu Wang  Jun‐xiu Sun  Jie‐yuan Ning 《国际地质力学数值与分析法杂志》2008,32(3):307-324

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热源强迫的非线性惯性重力内波及其应用     

吴俞  李国平 《成都信息工程学院学报》2006,21(Z1):7-11

利用动力学分析中的相平面方法,由z坐标系下的非绝热大气运动方程组导出了与非线性惯性重力内波有关的KdV方程,然后利用直接积分法得到两类有天气意义的孤立波解.初步建立了孤立波解与高原低涡的联系,进一步从理论上论证了高原低涡具有与热带气旋类低涡类似的涡眼和暖心结构的特征.  相似文献   

Spin Axis Direction of Comet 19p/Borrelly Based on Observations from 2000 and 2001     

Samarasinha  Nalin H.  Mueller  Béatrice E. A. 《Earth, Moon, and Planets》2002,90(1-4):473-482

We calculate the direction of the rotational angular momentum vector,M, of comet 19P/Borrelly based on rotational lightcurve data from 2000, groundbased imaging of the coma during the Deep Space 1encounter, and the basic near-nucleus coma morphology as revealed by the Deep Space 1 spacecraft. For the most likely direction, we derivea family of solutions (with center at RA = 221°, Dec = -7°) if the direction of M is towards the sunward hemisphere during the Deep Space 1 encounter, whereas if the rotation is of opposite sense, the diametrically opposite family of solutions (with center at RA = 41°, Dec = 7°) would result. We argue that the coma morphology in September 2001 is consistent with the nucleus being a principal axis rotator or one observationally indistinguishable from it. Therefore, for all practical purposes, the direction of the rotational angular momentum vector coincides with the spin axis. We also discuss why the determination of the spin axis direction based on observations from the last apparition is in disagreement with the current result.  相似文献   

Analysis on monthly-averaged distribution of sea surface wind and wave over the seas southeast of Asia using ERS-2 scatterometer data     

赵喜喜  侯一筠  李明悝  齐鹏 《中国海洋湖沼学报》2006,24(1):97-102

The wind system over the seas southeast of Asia (SSEA) plays an important role in China's climate variation. In this paper, ERS scatterometer winds covering the period from January 2000 to December 2000 and the area of 2-41 °N, 105- 130°E were analyzed with a distance-weighting interpolation method and the monthly mean distribution of the sea surface wind speed were given. The seasonal characteristics of winds in the SSEA were analyzed. Based on WAVEWATCH Ⅲ model, distribution of significant wave height was calculated.  相似文献   

Scattering of elastic wave by a partially sealed cylindrical shell embedded in poroelastic medium     

Liu Gan‐Bin  Xie Kang‐He  Yao Hai‐lin 《国际地质力学数值与分析法杂志》2005,29(11):1109-1126

Scattering of an elastic wave by a cylindrical shell embedded in poroelastic medium is investigated theoretically with the assumption that the shell material is also a porous elastic medium. The porous medium is modellized via Biot's theory and the scattering by cylindrical shell is expressed by the definition of scattering matrix. The normal mode expansion technique is employed for analysing the scattering field, and the asymptotic solutions of displacements, stresses and pore pressure are derived. Two limiting cases‐scattering by a poroelastic cylinder in Biot medium and a elastic cylindrical shell in elastic medium are obtained from the general solutions. The dispersion curves of displacement amplitude at the interface of shell and medium is compared with the case of elastic shell. The scattering amplitude associated with the fast, slow and transverse waves are identified by numerical simulation. Furthermore, the influence of the poroelastic property of shell material on scattering amplitude is analysed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

JXTA安全问题研究     

张莹  徐志根 《成都信息工程学院学报》2004,19(4):496-499

P2P对等网络(Peer-to-Peer network)是近年来引起广泛关注的网络技术,JXTA项目则是构建P2P网络平台的一个典型例子.针对JXTA网络中面临的安全问题及解决方案进行了初步探讨,最后以在JXTA中实现数字签名为例,介绍了目前正在积极开发中的JXTA安全项目.  相似文献   

A local control system for the test masses of the Virgo gravitational wave detector     

《Astroparticle Physics》2004,20(6):617-628

The mirrors of interferometric detectors of gravitational waves (GW) are suspended in order to be isolated from external disturbances. A local control system able to keep them correctly aligned and to damp the angular modes of the suspension is necessary. In this paper we present the solution adopted for Virgo based on a CCD camera sensor and on digital controls. With this solution the mirrors are kept aligned at the level of less than 1 μrad rms, enough to lock the interferometer and start the automatic alignment system.  相似文献   

Gigamasers: the key to the dust-obscured star formation history of the Universe?     

R.H.D. Townsend  R.J. Ivison  Ian Smail  A.W. Blain  D.T. Frayer 《Monthly notices of the Royal Astronomical Society》2001,328(2):L19-L22

A numerical model of the Leonid stream is developed, based on an earlier model which has been applied to the Perseid stream. The results for this model are applied to the 2001 Leonid return. By examining the full three-dimensional dispersion of individual 'streamlets' released from the Leonid parent comet, 55P/Tempel–Tuttle, we have derived an estimate for the temporal change in spatial density of each trail. Using this result along with an estimate for the location of the centres for individual streamlets and fits to previous Leonid storm profiles, we estimate that the activity from the shower will be broad and relatively strong (zenithal hourly rates perhaps in excess of 1000). In particular, streamlets from the 1766 and 1799 ejections contribute to activity peaking near 10 and 12 ut on 2001 November 18, respectively. Additional older material from 1633, 1666 and 1699, as well as more recent ejections from 1866 and 1833, contributes to a much broader secondary maximum near 17.5 ut on November 18. Comparison with other published models of predicted Leonid activity in 2001 shows general agreement in terms of timing, but the models differ significantly in terms of the relative magnitude of the activity (which other models suggest will be larger). Significant anisotropy in the impact hazard exists for satellites in the geostationary belt, with those over western longitudes most likely to be affected. Integrated fluences for the 2001 Leonid return suggest a hazard of order one magnitude greater than occurred for the 1999 Leonid storm.  相似文献   

Effect of the duration and direction of storm movement on infiltrating planar flow with full areal coverage     

V. P. Singh 《水文研究》2002,16(7):1479-1511

Using kinematic wave equations, analytical solutions are derived for flow due to a storm moving up or down an infiltrating plane and covering it completely. The storm duration is assumed in two ways. First, the plane is covered everywhere for the same duration by the storm. Second, the plane is covered in a linearly decreasing manner from the beginning of its coverage of the plane to the other end of the plane. By comparing the flow due to this storm with that due to a stationary storm of the same duration, the influence of storm duration, direction and velocity on flow hydrograph is investigated. It is found that storm movement has a pronounced effect on runoff hydrograph. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

THE ULTRASTRUCTURE OF SEPARATED AND CULTURED CELL OF PORPHYRA YEZOENSIS     

梅俊学  费修绠 《中国海洋湖沼学报》2001,19(1):35-39

There are many reports that cells (protoplasts) separated from the thallus of Porphyra by enzyme can develop to normal leafy thalli in the same way as monopores. But there are few investigations on the subcellular structure of the isolated vegetative cell for ccmparison with the subcellular structure of monospores. To clarify whether the separated and cultured cells undergo the same or similar ultrastructure changes during culture and germination as monospores undergo in their formation and germination, we observed their ultrastructure, ccxnpared them with those of the monospore and found that the ultrastructure of separated and cultured cells did not have the characteristic feature as that of monospore formarion, such as production of small and large fibrous vesicles, but was acccxnpanied by vacuolation andstarch mobilization like that in monospore germination. The paper also discusses the relations between monospores and separated and cultured cells.  相似文献