On the interior resonance problem when applying a hybrid FEM/MoMapproach to model printed circuit boards

A hybrid finite element method/method of moments (FEM/MoM) technique is used to analyze a printed circuit board power bus structure where the source and observation points are in the near field. The FEM is used to model the lossy region between the planes of the board including the source. The MoM is used to model the region outside the planes and provide a radiation boundary condition to terminate the FEM mesh. Numerical results for a bridged power bus structure are compared with measurements. A nonphysical interior resonance of the electric field integral equation is observed. The problem can be avoided by using a hybrid technique based on a combined field integral equation     

Changes in the kurtosis parameter of super-Gaussian beams passing through a spherically aberrated lens

Based on the Collins formula and irradiance moments definition, the propagation of the kurtosis parameter of super-Gaussian beams through a spherically aberrated lens is studied. Detailed numerical results are given. It is shown that, as compared with aberration-free super-Gaussian beams, the profile of spherically aberrated super-Gaussian beams can be leptokurtic, mesokurtic or platykurtic, depending on the aberration and propagation distance. The results for the spherically aberrated Gaussian beams can be dealt with as a special case treated in this paper. Finally, the advantage of our method is pointed out.     

[Na(18-C-6)]2[Cu(i-mnt)2]的合成与结构分析

研究了18-冠-6与Na2[Cu(i-mnt)2][i-mnt=异丁二腈烯二硫醇阴离子,S2CC(CN)2-2]的反应,得到的配合物[Na(18-C-6)]2[Cu(i-mnt)2](1)通过元素分析、红外光谱、X射线单晶衍射进行了结构分析.配合物为单斜晶系,空间群P2(1)/c.晶体学结构数据a=1.2819(11),b=1.1793(10),c=1.4928(13)nm,β=99.121(16)°,V=2.228(3)nm3,Z=2,Dcaled.=1.369g/cm3,F(000)=958,R1=0.0521,wR2=0.1003.1中的[Cu(i-mnt)2]基团通过配体i-mnt的氮原子与两个[Na(18-C-6)]基团中的钠原子成键,形成稳定的中性配合物.     

An iterative ADI-FDTD with reduced splitting error

We present a new iterative alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method. By recognizing the ADI-FDTD method as a special case of a more general iterative approach to solve the Crank-Nicolson (CN) FDTD scheme, the splitting error in ADI-FDTD can be reduced systematically. Numerical examples are used to illustrate the improved accuracy of this method.     

Asymptotic Analysis of the Current-Voltage Curve of a pnpn Semiconductor Device

We consider the one-dimensional steady-state semiconductor deviceequations modelling a pnpn device. There are two relevant scalingsof the equations corresponding to small and large applied voltages.In both scalings, the semiconductor equations can be consideredas singularly perturbed. It turns out that the small-voltagescaling breaks down for current values between two saturationcurrents. In that interval, the large-voltage scaling has tobe employed. For both scalings, we derive the first-order termsof an asymptotic expansion and show that the reduced problemhas a solution. An example verifies that the current-voltagecurves obtained have the expected qualitative structure.     

Estimating functionals of one-dimensional Gibbs states

Summary Some estimators of maximum likelihood type are constructed for estimating functionals of one-dimensional Gibbs states. We also show that those estimators are strongly consistent, asymptotically normal and asymptotically efficient.     

X射线衍射研究N2+注入Si

本文首先给出了180keV的N₂⁺注入Si的X射线衍射(XRD)分布,然后用Levenberg-Marquardt最优化方法模拟实验曲线。根据XRD运动学理论,在我们给出的试探胁变函数和多层模型的基础上,用自编程序计算给出了晶格胁变随注入深度、剂量和退火温度的变化。最后我们对实验和计算结果进行了初步的分析讨论。 关键词：     

基于地理信息系统的天津房地产管理数据库

从地理信息系统CIS的组成开始．提出该类系统的组织与管理方法，同时重点介绍了在现阶段开发该类系统时所使用的高端技术，最后对GIS系统的发展趋势作出分析与顶测。     

软件无线电中采样率转换技术的实现及在3G中的应用

目前移动通信标准繁多,且新旧体制混杂,很难做到统一.为了实现互连互通,目前比较可行的方法是采用软件无线电.采样率转换技术是实现互连互通的关键.文中针对第三代移动通信系统(3G)中不同通信体制的带宽、速率要求,根据分级变换的思想,对3G中的CDMA2000和TDSCDMA的采样率转换方案进行了设计,并对3G中的5种制式的采样率转换方案进行了分析比较.实验表明,这一方案可以在采样率变换的高效网络结构基础上进一步降低滤波运算量和存储量.     

Mobile tele-echography: user interface design.

Ultrasound imaging allows the evaluation of the degree of emergency of a patient. However, in some instances, a well-trained sonographer is unavailable to perform such echography. To cope with this issue, the Mobile Tele-Echography Using an Ultralight Robot (OTELO) project aims to develop a fully integrated end-to-end mobile tele-echography system using an ultralight remote-controlled robot for population groups that are not served locally by medical experts. This paper focuses on the user interface of the OTELO system, consisting of the following parts: an ultrasound video transmission system providing real-time images of the scanned area, an audio/video conference to communicate with the paramedical assistant and with the patient, and a virtual-reality environment, providing visual and haptic feedback to the expert, while capturing the expert's hand movements. These movements are reproduced by the robot at the patient site while holding the ultrasound probe against the patient skin. In addition, the user interface includes an image processing facility for enhancing the received images and the possibility to include them into a database.