Yu Jihui

A new numerical technique for calculating current distributions on curved wire antennas - parametric B-spline finite element method

A new numerical technique is presented for calculating the current distributions on wire antennas with a high degree of curvature. The geometry of the wire antenna is expressed by a parametric equation and the current is directly expanded into a series of quadratic B-spline basis functions of the parameter, so that the truncation error in modeling the curved wire structure is avoided. This algorithm is used to analyze a circular loop antenna, a conical equiangular-spiral antenna, and a four-arm Archimedian spiral antenna to demonstrate its validity and practical value.

B-spline finite-element method in polar coordinates

A numerical solution method for two-dimensional electromagnetic field problems is presented using the B-spline finite-element expression based on polar coordinates. The technique has two main advantages: (1) to avoid the truncation errors at some curved boundaries and (2) to improve the accuracy of singular boundary-value problems with a sharp corner. The B-spline finite-element formulation in polar coordinates is derived and its numerical applications are illustrated by an eddy current problem and several waveguide eigenvalue problems.

The Simulation and Research on Electromagnetic Character and Coupling Degree of Vehicle Whip Antennas

Antennas have become a frequently used component in modern vehicles. It is very important to research the electromagnetic character of antenna affected by vehicle body and the interference among the antennas. In this paper, a lifelike vehicle model was construct. Then the electromagnetic character of whip antenna at different position on model and the coupling degree between antennas is simulated used CST based FIT technology. The best antenna position was obtained by simulation results at last. The analysis process and simulation results can be ways and means for vehicle electromagnetic compatibility research and vehicle antennas design.

Numerical Simulation on EMI of Wire

Wire plays an important role in the EMC of electronic/electric device; wire with excitation not only brings crosstalk on near wires, but also brings radiation. MIL (multi conductor transmission lines) method was implemented in computing the crosstalk of multi lines and MTL/FDTD (finite difference time domain) hybrid methods was used in the analysis of radiation of wire above the ground plane, radiation of wire when different terminal were considered was also discussed The results show that method is effective; all presented conclusions are valuable in practical applications.

Noise Spark Current Level Caused by Capacitive Discharge in an Automotive Secondary Ignition System

This paper simulates the noise spark current level in an automotive ignition system caused by capacitive discharge when the plug gap is breakdown. The noise spark current level is analyzed by making use of Rompe-Weizel formula for the spark resistance. From this paper, ignition noise spark current level could be examined analytically with respect to the plug dimensions and the gap breakdown voltage, and effects of the resistor on the noise current is studied here. This work done here is useful to research the automotive electromagnetic compatibility.

Simulation and research of the coupling characteristic of a cavity with Thin-Slot

Analysis of coupling characteristic of cavity with Thin-Slot has the theoretical value and applied value in design of electron product and estimate of EMC. In this paper we used the finite-difference time-domain (FDTD) method, analyze coupling characteristic of cavity. In order to reduce time of calculation and resource of CPU and memory, so the size of space is small than thin-slot, we used the Enhanced Thin-Slot Formalism (ETSF) to resolve the problem. Finally, educe the result and analyze the result.

A hybrid method based on FDTD for simulation of far field from opening in shielding enclosure

This paper presents a hybrid method for the calculation of the electric far field outside the enclosure. The method computes electric near fields on the opening by finite-difference time-domain (FDTD) to determine the equivalent magnetic current. Then the far fields are calculated using this equivalent current. Simulation results show that the proposed method significantly reduces the computational effort and still maintains satisfactory results in comparison to a full FDTD simulation and the traditional hybrid method

A discrete algorithm for complex frequency-domain convolutions

A discrete algorithm suitable for the computation of complex frequency-domain convolution on computers was derived. The Durbins numerical inversion of Laplace transforms can be used to figure out the time-domain digital solution of the result of complex frequency-domain convolutions. Compared with the digital solutions and corresponding analytical solutions, it is shown that the digital solutions have high precision.

A novel finite element method for analyzing viscoelastic dynamics in biological tissues

A novel finite-element method for analyzing viscoelastic dynamics in biological tissues through using two important conclusions of linear viscoelastic models and applying electrical-network theory and filtering techniques is successfully derived. The complexity of viscoelastic materials can be either as simple as isotropic or more and more complex up to extremely anisotropic. The linear viscoelastic models describing mechanical behaviors of biological tissues can be an arbitrary combination of two-kind elements and three-type fundamental models. It is confirmed that a general, systematic, and highly precise finite-element fast analysis method, that is suitable for analyzing the dynamic responses of biological tissues and engineering materials with linear viscoelastic models, can be derived.

The modification and discretization for H/spl I.oarr/-/spl psi/ functional in three dimensional eddy current field

The error resulting from the existent H/spl I.oarr/-/spl psi/ method (magnetic field intensity vector-scalar magnetic potential) of three dimensional eddy-current field was discovered by practical computation. The corresponding modified method was given. The modified H/spl I.oarr/-/spl psi/ was discretized. A correct result was obtained by calculating a practical three dimensional eddy-current problem.