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   

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   

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   

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   

Inbank and overbank velocity conditions in an arid zone anastomosing river     

A. David Knighton  Gerald C. Nanson 《水文研究》2002,16(9):1771-1791

Relative to those at sub‐bankfull flow, hydraulic conditions at overbank flow, whether in the channel or on the floodplain, are poorly understood. Here, velocity conditions are analysed over an unusually wide range of flows in the arid zone river of Cooper Creek with its complex system of anastomosing channels and large fluctuations in floodplain width. At‐a‐station hydraulic geometry relationships reveal sharp discontinuities in velocity at the inbank–overbank transition, the nature of the discontinuity varying with the degree of flow confinement and the level of channel–floodplain interaction. However, despite inter‐sectional differences, velocities remain modest throughout the flow range in this low‐gradient river, and the large increases in at‐a‐station discharge are principally accommodated by changes in cross‐sectional area. Velocity distribution plots suggest that within‐channel conditions during overbank flow are characterized by a central band of high velocity which penetrates far toward the bed, helping to maintain already deep cross‐sections. Floodplain resistance along Cooper Creek is concentrated at channel bank tops where vegetation density is highest, and the subsequent flow retardation is transmitted across the surface of the channels over distances as large as 50–70 m. The rough floodplain surface affects flood wave transmission, producing significant decreases in wave speeds downstream. The character of the wave‐speed–discharge relationship also changes longitudinally, from log–linear in the upper reaches to nonlinear where the floodplain broadens appreciably. The nonlinear form is similar in several respects to relationships proposed for more humid rivers, with flood wave speed reaching an intermediate maximum at about four‐fifths bankfull discharge before decreasing to a minimum at approximately Q_2·33. It does not regain the value at the intermediate maximum until the 10 year flood, by which time floodplain depths have become relatively large and broad floodways more active. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

A Large Scale Energy Source For Feeding: ISM Turbulence in Spiral Galaxies     

Xiaolei Zhang 《Astrophysics and Space Science》2002,281(1-2):281-284

One of the important consequences of a newly discovered secular dynamical evolution process of spiral galaxies (Zhang, 1996, 1998, 1999) is that the orbiting disk matter receives energy injection each time it crosses the spiral density wave crest. This energy injection has been shown to be able to quantitatively explain the observed age-velocity-dispersion relation of the solar neighborhood stars. We demostrate in this paper that similar energy injection into the interstellar medium could serve as the large-scale energy source to continuously power the observed interstellar turbulence and to offset its downward cascade tendency. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

Kinematic wave solutions for pollutant transport over an infiltrating plane with finite‐period mixing and mixing zone     

V. P. Singh 《水文研究》2002,16(12):2441-2477

Kinematic wave solutions are derived for transport of a conservative non‐point‐source pollutant during a rainfall‐runoff event over an infiltrating plane for two cases: (i) finite‐period mixing and (ii) soil‐mixing zone. Rainfall is assumed to be steady, uniform and finite in duration, and it is assumed to have zero concentration of pollutants. Infiltration is assumed constant in time and space. Prior to the start of rainfall, the pollutant is distributed uniformly over the plane. In the first case, when rainfall occurs, the mixing of pollutant in the runoff water occurs in a finite period of time. In the second case, the chemical concentration is assumed to be a linearly decreasing function of rainfall intensity and overland flow. The solute concentration and discharge are found to depend on the flow characteristics as well as the solute concentration parameters. The characteristics of solute concentration and discharge graphs seem to be similar to those reported in the literature and observed in laboratory experiments. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

非饱和土地基中复合多层波阻板对S波的隔离效应     

舒进辉  马强  常立君 《岩土力学》2023,44(1):217-231

基于弹性波在非饱和多孔介质与单相弹性介质中的传播理论,考虑在非饱和土地基中设置一定厚度的复合多层波阻板（复合多层波阻板以3层为例）,利用Helmholtz矢量分解定理,推导了非饱和土地基中S波通过复合多层波阻板的透射、反射振幅比的解析解。通过数值算例,分析了层间波阻板剪切模量和密度等物理力学参数对非饱和土地基中S波通过复合多层波阻板时传播特性的影响规律。结果表明：复合多层波阻板中层间波阻板材料的剪切模量和密度对透反射系数影响显著。复合多层波阻板是一种有效的隔振屏障,严格控制层间波阻板的剪切模量和密度可以获得最佳隔振效果,这为复合多层波阻板在地基振动控制领域中的应用提供理论指导。  相似文献   

砂岩单轴压缩试验P波速度层析成像及声发射特性研究     

张光  吴顺川  张诗淮  郭沛 《岩土力学》2023,(2):483-496

深部矿井开采极易诱发矿柱型岩爆,矿柱型岩爆严重威胁着矿山的安全高效开采,为探究矿柱型岩爆破坏机制和前兆信息,选用自贡红砂岩进行单轴压缩试验,并采用主动超声和被动声发射对破裂过程进行监测,联合主动超声与被动声发射监测数据对波速进行层析成像反演,分析试样破裂过程中波速演化规律。研究结果表明：砂岩试样在加载过程中速度模型呈现高度非均质性,在加载过程中会出现低速区,且声发射事件集中出现在低速区内部;P波速度离散度可反映全局波速变化特征,在峰值附近变化剧烈,随荷载增加P波速度离散度持续增大;声发射事件在峰前、峰后定位结果相差较大,峰前阶段声发射事件随机分布,峰后阶段声发射事件定位结果集中。此外,研究发现选用均质速度模型进行声发射事件定位会增大定位误差,试样最终失稳前b值的降低表明试样大尺度裂纹活动加剧,导致岩石非均质性增大,也间接证明了采用非均质速度模型进行声发射震源定位的必要性。该研究结果可用于现场矿柱稳定性监测,定期反演获得矿柱波速变化为矿柱型岩爆提供先兆预警信息。  相似文献