Analytical study of magnetohydrodynamic propulsion stability

In this paper an analytical solution for the stability of the fully developed flow drive in a magneto-hydro-dynamic pump with pulsating transverse Eletro-magnetic fields is presented. To do this, a theoretical model of the flow is developed and the analytical results are obtained for both the cylindrical and Cartesian configurations that are proper to use in the propulsion of marine vessels. The governing parabolic momentum PDEs are transformed into an ordinary differential equation using approximate velocity distribution. The numerical results are obtained and asymptotic analyses are built to discover the mathematical behavior of the solutions. The maximum velocity in a magneto-hydro-dynamic pump versus time for various values of the Stuart number, electro-magnetic interaction number, Reynolds number, aspect ratio, as well as the magnetic and electrical angular frequency and the shift of the phase angle is presented. Results show that for a high Stuart number there is a frequency limit for stability of the fluid flow in a certain direction of the flow. This stability frequency is dependent on the geometric parameters of a channel.     

编织屏蔽层对称型应急电缆的设计与计算

本文叙述了编织屏蔽层对称应急电缆的结构及其衰减系数增大的原因。作者还确定了有关电气性能参数的各项修正系数，并提出了在给定标称频率下的波阻抗及衰减系数的新的设计算式，这些为今后设计相同结构类型的柔软对称电缆提供了条件。