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The problem of selffield regularization (necessary for removing the divergent selffield of point particles) is dealt with in two separate steps.


The elastic displacement field of point defects in cubic crystals is calculated for weak anisotropy by second order perturbation theory and by a variational procedure.


Elastic displacement field of point defects in anisotropic cubic crystals


The electric field of point defects is found to be screened by charge distribution even at distances small enough to affect the groundstate energy of electrons trapped by the defect positive charges.


The harmonically varying field of point electric and magnetic dipoles in an anisotropic medium with an anisotropic axis is found for the first time.

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 Usually the assumption of secondary sourses lying on the sea bed and possessing definite directional character is taken for the calculation of bottom reverberation.But in cases when transmitter and receiver are located at different depths,the results of such calculation may contradict with principle of reciprocity.In this paper the sea bottom is treated as a plane boundary with random impedance,and the rever beration field of point source is given by wave theory and satisfies the principle of reciprocity.Concrete... Usually the assumption of secondary sourses lying on the sea bed and possessing definite directional character is taken for the calculation of bottom reverberation.But in cases when transmitter and receiver are located at different depths,the results of such calculation may contradict with principle of reciprocity.In this paper the sea bottom is treated as a plane boundary with random impedance,and the rever beration field of point source is given by wave theory and satisfies the principle of reciprocity.Concrete result for case of shallow water with negative gradient is discussed.  通常在计算海底混响时,假设在海床上分布具有一定方向特性的次声源。但当发射器和接收器位于不同深度时,这样获得的结果可能不符合互易原理。文中将海底作为具有随机阻抗的平面边界,由波动理论给出满足互易原理的点声源混响场。并讨论了负梯度浅海情况下的具体结果。  Using Fourier transformation, the threedimensional boundary value problemof electric field of point source on twodimensional geoelectric section is convertedinto twodimensional boundary value problem.Solving the twodimensional boundaryvalue problem by means of Green formula and boundary element method, and usingFourier inverse transformation, we can obtain electric potential in threedimensionalspace.Compared with finite element method,the method proposed in this paper requires less memory, less original... Using Fourier transformation, the threedimensional boundary value problemof electric field of point source on twodimensional geoelectric section is convertedinto twodimensional boundary value problem.Solving the twodimensional boundaryvalue problem by means of Green formula and boundary element method, and usingFourier inverse transformation, we can obtain electric potential in threedimensionalspace.Compared with finite element method,the method proposed in this paper requires less memory, less original data needed for computer input, and has higher calculating accuracy.This method can be executed on small even microcomputer.  用付氏变换将点源二维地电断面的三维边值问题,变换成二维边值问题。再用格林公式和边界单元法解二维边值问题,并由付氏反变换,获得三维空间中的位。与有限单元法比较,本方法所需的计算机内存少,原始数据的输入简单,且有较高的计算精度,可在小型甚至微型机上运算。  First, the 2D boundary value problem o electric field of point source on a layered model with linear change of conductivity is given in cylindrical coordinate system. Then, the boundary value problem is converted into a variational equation by the variation method. We solve the variation equation by means of the finite element method. Dividing the entire region into many rectangular elements and interpolating with a bilinear function in each element. The variation equation is converted into a linear algebric... First, the 2D boundary value problem o electric field of point source on a layered model with linear change of conductivity is given in cylindrical coordinate system. Then, the boundary value problem is converted into a variational equation by the variation method. We solve the variation equation by means of the finite element method. Dividing the entire region into many rectangular elements and interpolating with a bilinear function in each element. The variation equation is converted into a linear algebric equation system. Solving the equation system, we can obtain the electric potential value on nodes. According to these value, the apparent resistivity on ground surface can be calculated.The calculation example shows that the result calculated by this method is in agreement with the analytic solution. In addition, this paper gives an example of quantitative analysis of the annual variation of apparent resistivity.The capacity of memory needed for this method is about 100 K. The runtime for calculating a sounding curve on super smallcomputer MV/6000 is about several tens of seconds.  首先给出柱坐标系中电导率分段线性变化的水平层的点源电场的二维边值问题,然后用变分法将边值问题转变为变分问题。用有限单元法解变分问题,将区域剖分成矩形单元,在单元中进行双线性函数插值,将变分方程化为线性代数方程组。解方程组,得各节点的电位值,由此可计算地表的视电阻率。 算例表明,本方法计算结果与精确解十分符合。本文还举了一个定量分析视电阻率年变化的例子。 本方法占用计算机内存约100K数量级。在MV/6000超小型计算机上计算一条电测深曲线的时间为几十秒钟。   << 更多相关文摘 
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