摘要:By means of the conformal mapping,the analytic expressions of the electric potential and field distribution within the region of the diode which has a oval pyramid emission cathodare obtained. The relationships of electric field at the emitter tip and current density of the field emission versus the tip curvature are calculated.
摘要:On the basis of modulation-demodulation combined characteristic of system,amplitude-phase frequency characteristics and phase orthogonality of demodulator, the combinationinterference of PM system of multi-subcarrier modulation is analyzed,and the formulas of combination interference are deriverd. The experiment result is given.
摘要:On the basis of the mathematical analysis of analogue noise in acoustic domain,this article puts forward the engineering mathematics model which is used to solve the problems,and successfully designs a new,simple and applicable numerical control output circuit to counterthe special subject of the numerical control output analogue noise. It is also proved from both thetheory and practice that the pioneering work is reasonable and scientific. At the same time,the newcircuit can be used in every sort of D/A conversions. The plan is more valuable for reference andenables you to draw on the good experience of it in similar circuit designs. Thus it can be fur foerpoplarized.
关键词:Analogue noise;Numerical control output;harmonic analysis
摘要:In this paper,a new polynominal is presented as a designing formula, which canadjust the pattern through the feeding phase only. Some examples are also given to verify the formula and the results show that this method is practical.
摘要:Focused on the methods of near-zone to far-zone field transformation in solvingscattering problem by FDTD method,two new approaches are presented in this paper. One is directly obtaining scattered far field by adopting Stratton-Chu integral formula. Another method isapplying Laplace transformation and convolution technique which leads to a unified formula forscattered far field in time domain for both 2-D and 3-D scattering problems,and makes 2-D problem a special case of 3-D problem. Numerical results of simple scatterer are given to show the validation of the both algorithms.
关键词:Transient scattering;FDTD method;Time domain near-zone to far--zone transformation
摘要:The induced charge distributions on two touching metallie spheres,immersed in uniform electric field,are influenced by the mutual interactions between the spheres. This influence depends in a complicated way on their radii and the orientation of the external field. In this paper,the image method is applied to this electrostatic problem. The image charges are determined exactly. The longitudinal and transverse dipole moments of the pair are derived,respectively. Here, thetotal induced charge of the pair is required to be zero. Hence our results have the generality compared with previous discussions.