In the process of propagation of electromagnetic waves,ridged waveguide has the energy loss.In order to study the attenuation characteristics for dielectric loaded ridge waveguide, the TE mode's attenuation and power handling of dielectric loaded inverted trapezoid symmetric double-ridge waveguide are calculated by the finite-element method and Matlab software.It analyzes the relationship of attenuation and power handling with the change in ridge waveguide size,frequency and the relative dielectric constant,draws the graph of relation.The results obtained in this paper will enrich the existing data of dielectric loaded ridge waveguide,and provide a valuable basis in design and optimization.

In view of various deformations of ridge waveguide devices in use,secondary programming was conducted by using the finite element PDE toolbox in the Matlab environment to research into the characteristics of the trapezoidal single-ridge waveguide in displacement deformation and other deformations under stress;and then the relation curve of characteristic attenuation,power-handing capability and impedance of ridge waveguide was given out.The numerical results indicated that the deformations made the characteristic attenuation of ridge waveguide increase and the power-handing capability and impedance decrease,that it had the biggest influence in use and that lateral deformation on ridge waveguide should be avoided as much as possible.

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A control method using neural network to improve the traditional PID controller for PWM rectifier with unity power factor is presented.In this paper,the space-vector PWM is used to control the rectifiers,and an adaptive compound single-neuron PI controller based on neural network is used in the voltage loop to adjust the parameters.Simulation results show that the controller built in the paper is able to adjust the PI parameters online,trace the changing process of the rectifier quickly,improve the stability of system effectively when the structure and parameters of the system is changed,and can meet the conditions of frequent start and stop,which is necessary for subway.

本文运用差分方法并结合高考题研究求解数列通项问题,发现利用差分方法求解数列的通项简便、明晰,并且对不同的数列,差分方法适用范围更广,并且不需要掌握一些特殊的技巧或进行复杂的计算过程.

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