Influence of Constant Torque on Equilibria of Satellite in Circular Orbit

We consider the equilibria of a satellite in a circular orbit under the action of gravitational and constant torques. The number of equilibria depending on the parameters of the problem is found by the analysis of an algebraic equation of order 6. The domains with different numbers of equilibria are specified, and the equations of boundary curves are determined in function of values of the components of constant torque. Classification of different distributions of number of equilibria is made for arbitrary values of the parameters.     

Eddy viscosity and tidal cycles in a shallow sea

The very pronounced spring-neap tidal cycle in the South Australian Gulfs leads to an unusually large variation in the magnitude of the tidal currents. Measurements of the currents in these Gulfs show that the non-tidal circulation depends on the strength of the tidal currents and hence on the spring-neap cycle. A simple model is produced in which the vertical eddy viscosity is a function of both wind strength and tidal currents. Results from the model agree with the observations and suggest a means whereby variations in tidal mixing may be accounted for in hydrodynamic modelling of the circulation in shallow seas.     

Effective relaxation time and viscosity of the earth inferred from the postseismic vertical deformations of the 1990 MS=7.0 Gonghe earthquake

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Cosmology of Vacuum

Shortly the vacuum component of the Universe from the geometry point of view and from the point of view of the standard model of physics of elementary particles is discussed. Some arguments are given to the calculated value of the cosmological constant (Zel’dovich’s approximation). A new component of space vacuum (the gravitational vacuum condensate) is involved the production of which has fixed time in our Universe. Also the phenomenon of vacuum selforganization must be included in physical consideration of the Universe evolution.     

A novel analytical solution for constant‐head test in a patchy aquifer

A mathematical model describing the hydraulic head distribution for a constant‐head test performed in a well situated at the centre of a patchy aquifer is presented. The analytical solution for the mathematical model is derived by the Laplace transforms and the Bromwich integral method. The solution for the hydraulic head has been shown to satisfy the governing equations, related boundary conditions, and continuity requirements for the hydraulic head and flow rate at the interface of the patch and outer regions. An efficient numerical approach is proposed to evaluate the solution, which has an integral covering an integration range from zero to infinity and an integrand consisting the product and square of the Bessel functions. This solution can be used to produce the curves of dimensionless hydraulic head against dimensionless time for investigating the effect of the contrast of formation properties on the dimensionless hydraulic head distribution. Define the ratio of outer‐region transmissivity to patch‐region transmissivity as α. The dimensionless hydraulic head for α=0.1 case is about 2.72 times to that for α=10 case at dimensionless large time (e.g. τ?10⁶) when the dimensionless distance (ρ) equals 10. The results indicate that the hydraulic head distribution highly depends on the hydraulic properties of two‐zone formations. Copyright © 2006 John Wiley & Sons, Ltd.     

由三维坐标值计算两点距离的精度分析及应用

本文推导了由三维坐标计算两点距离的精度估算公式,指出仪器和目标的相对位置会影响所求空间距离的精度,并通过全站仪和激光跟踪仪这两种不同精度的三维仪器对标准尺的测量结果进行了验证,最后给出了基于距离测量的“两点法”计算测距加常数的原理。在文献中尚无对这一问题的系统、深入讨论,希望本文能给精密工程测量工作者提供实际操作参考。     

溶液黏度模型的研究进展

黏度的研究对于流体流动的数字模拟、油气藏的开发以及CO_2的地质封存等都有着不可替代的意义,其也是评价油气藏的最终开发效果与反映油气藏经济效益的关键因素,当前关于电解质溶液黏度的理论研究主要存在2大类计算模型,即:(1)基于Erying绝对速率理论、Debye Hückel理论、Einstein方程等相关理论而开发的半经验半理论黏度模型;(2)基于如Jones Dole方程等的经验性黏度模型。     

The westward drift of the lithosphere: A tidal ratchet?

Is the westerly rotation of the lithosphere an ephemeral accidental recent phenomenon or is it a stable process of Earth's geodynamics? The reason why the tidal drag has been questioned as the mechanism determining the lithospheric shift relative to the underlying mantle is the apparent too high viscosity of the asthenosphere. However, plate boundaries asymmetries are a robust indication of the ‘westerly’ decoupling of the entire Earth's outer lithospheric shell and new studies support lower viscosities in the low-velocity layer (LVZ) atop the asthenosphere. Since the solid Earth tide oscillation is longer in one side relative to the other due to the contemporaneous Moon's revolution, we demonstrate that a non-linear rheological behavior is expected in the lithosphere mantle interplay. This may provide a sort of ratchet favoring lowering of the LVZ viscosity under shear, allowing decoupling in the LVZ and triggering the westerly motion of the lithosphere relative to the mantle.     

工业测量全站仪坐标测量精度检定方法

全站仪坐标测量在航空航天、大型设备制造业、特种异形工程和计量检测等领域有广泛应用,其坐标测量误差是最受关注的精度指标。与激光跟踪仪、关节臂等坐标测量技术不同,全站仪的标称精度指标并未直接给出点位坐标误差,而是分别给定测角和测距误差。由于国内外目前还缺乏将测角和测距精度对应到坐标精度的相应规范,这就导致不能直观反映全站仪的实际坐标测量精度,给具体测量工作的坐标精度估算带来一定难度。基于以上现状,提出了基于点对点长度测量和三维坐标测量误差的检定模型;并利用3种不同类型的工业测量全站仪进行了实验测试,验证了该检定模型的可行性。