通过对描述沙粒垂向运动速度脉动分量的随机微分方程的直接求解，获得了风沙流中沙粒运动的随机轨迹。
Stochastic sand trajectories in wind-blown sand were obtained by solving the differential equation which describes the vertical fluctuating velocity of sand grains.
本文通过求解灾变磁场作用下刚性直圆管脉动流的运动方程，得到了它的分析解。
In this paper, the analytic solution of the dynamical equation of the pulsatile flow in a rigid round tube under the low-frequency varying magnetic field is obtained.
当脉动幅度与平均磁场强度之比为有限值时，在一般情况下，控制方程中的非线性项不能略去，因而不能用WKB解来描述有限振幅脉动幅度的径向变化。
When the amplitude of the fluctuation is finite with respect to the average magnetic field intensity, the nonlinear terms in the garvening equations can not be droped and the WKB aproxima-tion fails.
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