GaAs MMIC中平面Schottky Diode的C－V特性解析模型

本文提出一种采用ＧａＡｓＭＥＳＦＥＴ工艺制造的平面微波变容管Ｃ－Ｖ特性解析模型，该模型着眼于小尺寸、平面化工艺及离子注入工艺，充分考虑了由其产生的栅下沟道串联电阻及侧电容对平面ＳｃｈａｔｔｋｙｄｉｏｄｅＣ－Ｖ特性的影响，这些影响对平面变容管影响较显著而在已有的模型中是被忽略或未作详细讨论的．文中还给出了该模型的算例及与实验结果，已有的几种典型模型算例的比较．结果表明，本文模型中参数易确定，与实验亦附合得很好．     

一种新的空时无线信道模型及其计算机模拟方法

信道模型对分析智能天线系统的性能是非常重要的。针对基于(散射体)几何分布的单反射椭圆模型(GBsBEM)在计算机模拟时参数难以确定的不足,本文结合UMTS-IMT-2000推荐的信道模型,提出了一种新的空时信道模型,并给出了计算机模拟方法:以GBSBEM模型为基础,吸收UMTS-IMT-2000推荐的信道模型的时延和功率方面的参数并考虑GBSBEM模型中DOppler效应对信号幅度的影响,模拟空时Rayleigh信道。在这一方法的基础上,又提出了多用户空时信道简化模型以及模拟方法。计算机仿真结果表明,所提出的信道模型计算机模拟方法是可行的。     

An improved analytical AC large-signal model for the GaAs MESFET

An improved analytical AC large-signal model for a MESFET is presented. The model is an upgrading of a previously presented model. The improvement is basically in the expressions for the conduction current. Simulation results are presented and compared to measured data. The calculated gain and power are slightly greater than the measured values. This is expected, since the matching networks have some loss, which is not included in the calculation. The loss in the input matching network can be appreciable due to the large transformation ratio     

基于椭圆抛物面的近视散光矫正模型的研究

针对人眼角膜地形的多样性,本文采用了椭圆抛物面对近视散光角膜表面建模,以此建立了近视散光矫正的模型,定量地分析了近视散光度数以及术区直径和最大切削深度的关系,对本文的模型与圆环面假设的近视矫正模型比较发现,在相同的近视散光度数度和术区情况下,本模型所需要的矫正量更小,适用于切削量大的高度近视散光的矫正.将该模型应用于小光斑准分子激光眼科治疗机,经过PMMA试验验证,本文给出的治疗模型能有效地矫正近视散光.     

Computational survey of univariate and multivariate learning curvemodels

A computational survey of the various univariate and multivariate learning curve models that have evolved over the past several years is presented. Discussions are presented to show how the models might be used for cost analysis or productivity assessment in engineering management. A computational experiment comparing a univariate model to a bivariate model is presented. While the bivariate model provides only a slightly better fit than the univariate model, it does provide more detailed information about the factor interactions, and better utilization of available data. The results of the computational experiment can be generalized for the appropriateness of multivariate models     

一种有效的系统芯片串扰故障激励检测模型

目前的系统芯片(SOC)制造技术已经进入了深亚微米时代,由于系统芯片内部信号传输线发生串扰而导致系统功能失效的串扰故障问题不容忽视。文中在对系统芯片中信号传输线的串扰产生性质进行深入研究的基础上,提出一种简单有效的系统芯片串扰故障激励检测模型——基于搜索的MAF模型。对使用这种串扰故障激励模型的效率和已有的MAF模型进行了对比。结果显示在串扰较弱时,其所需的检测矢量数和已有的MAF模型相当;而在串扰较严重时,这种新的串扰故障激励检测模型只需较少的激励检测矢量即可以完成对所有串扰故障的激励检测。     

Transmission-Line MNodeling of Shielded Wires for Crosstalk Prediction

The adaptation of a transmission-line model to the prediction of crosstalk in shielded-wire circuits is presented. The incorporation of pigtail sections of the shielded cable into the transmission-line model is discussed, and the presence of the pigtail wires is shown to be important. Experimental results are presented which illustrate the prediction accuracy of the model.     

New distributed model of NPT IGBT dedicated to power circuits design

In this paper, a new one-dimensional (1D) insulated gate bipolar transistor (IGBT) model is presented. The heart of this model is based on the analogical resolution of the ambipolar equation of diffusion. Indeed, carriers transport to broad areas and little doped power components is of a distributed nature. Approximation of the localised constants is no longer a valid solution. By taking into account, in the model, the side current into the P/P+ well, the 2D phenomenon, IGBT latch-up can be reviewed. The complete model developed under SABER as well as the static, dynamic results of simulation and the use in current converter are presented and compared to Hefner’s IGBT model. Simulation results of a inverter will be also presented to show the good behaviour of this IGBT model.     

A transfer length model for contact resistance of two-layer systemswith arbitrary interlayer coupling under the contacts

An improved analytical solution to the two-layer transmission line model for determining contact resistances to semiconductor layers is presented. In contrast to previously published two-layered analyses, the present solution is valid for arbitrary strength linear coupling between the two conducting layers in the region under the contact. A comparison of limiting cases and a physical interpretation of the differences between predictions of this model and previous models are presented. The predicted resistance versus pad separation behaviour obtained from the present model and from a two-layer model which assumed weak interlayer coupling beneath the contacts are compared for identical physical structures. Experimental data for contact resistance measurements on a double-barrier resonant tunneling diode structure are presented. The measured data exhibit the nonlinear resistance versus pad spacing predicted by the model and show a dependence on current level which can be modelled as a variation of the interlayer coupling strength. The values of the contact resistance, interlayer coupling resistance and sheet resistance extracted from the measured data using the present model and the weakly coupled model are presented and compared with independently measured and calculated parameters     

An accurate model for power DMOSFETs including interelectrodecapacitances

A SPICE-compatible circuit model for power MOSFETs is presented. It is based on device physics and uses a subcircuit representation. The interelectrode capacitances are modeled accurately as nonlinear functions of the applied biases. Various second-order effects relating to the gate capacitance model are discussed, and strategies are presented to include them in the model. The model parameters can be obtained from device measurements. The model is verified by comparing measured and simulated waveforms from a gate charge test circuit     

Antenna coupling model for radar electromagnetic compatibilityanalysis

A statistically based antenna coupling model is presented. The model predicts the probability of interference based on the antenna coupling statistics. In addition, a modification to the model that takes into account sidelobe blanking on the victim antenna is presented. This model has advantages over an existing model because in addition to considering sidelobe blanking it makes no assumption about the antenna pattern statistics and readily incorporates the main beam region     

Modeling and simulation of mobile satellite propagation

Mobile satellite systems are subject to severe fading due to blockage of the line-of-sight (LOS) path by roadside vegetation. A thorough understanding of the fading effects is necessary for the design of a reliable land-mobile satellite system. Analytical and empirical models are presented for predicting fade statistics for vegetative shadowing of mobile satellite terminals. A software simulator for generating simulated fade data is also presented. A physical model relating physical path parameters to propagation model parameters is presented, and results using the model are shown     

On the use of fractional Brownian motion in the theory ofconnectionless networks

An abstract model for aggregated connectionless traffic, based on the fractional Brownian motion, is presented. Insight into the parameters is obtained by relating the model to an equivalent burst model. Results on a corresponding storage process are presented. The buffer occupancy distribution is approximated by a Weibull distribution. The model is compared with publicly available samples of real Ethernet traffic. The degree of the short-term predictability of the traffic model is studied through an exact formula for the conditional variance of a future value given the past. The applicability and interpretation of the self-similar model are discussed extensively, and the notion of ideal free traffic is introduced     

一种新的跳频信号检测模型

 对基于信道化处理的跳频信号检测模型进行了研究.在介绍并推导了该检测结构的基础上,分析了该模型运算复杂度过高的原因,设计了一种基于分层处理的跳频信号检测模型.该模型通过对信号进行分层处理,减少了监控无用信道的面积,较大幅度降低了模型的运算量,提高了模型对资源的利用率,提升了模型的实用价值.仿真结果表明,改进后模型的运算量得到了大幅降低,验证了模型的有效性.     

基于移动Agent的智能电子商务模型的设计与实现

基于移动Agent技术的智能电子商务模型是一个新的研究课题.在分析现有电子商务模型存在问题的基础上,构建了一个建立在Internet开放采购模型OBI之上、支持B2B模式的智能电子商务模型IECMMA,提出了一个针对该模型的改进的电子商务安全方案.设计了一个基于时间策略的智能购物算法,并利用IBM公司的移动A-gent开发工具ASDK实现了该模型的主要功能.实验结果表明,该模型是切实可行的.     

某雷达数字化调平平台建模及算法

建立一种雷达数字化调平平台的数学模型,并提出了相应的算法。传统的坐标旋转变换的算法复杂、实现困难、运算量大,因此提出一种全新的算法,该算法针对三维的数学模型进行等价拆解为二维模型,进行平面几何解析,通过分析,总结出几个简单的公式,使得算法简单,便于理解。该模型可应用于相控阵雷达和火炮射击等未进行机械调平的多个领域。     

GaAs MESFET/PHEMT大信号建模

大信号精确模型的建立是微波单片集成电路设计和研制的基础,在分析传统建模方法的基础上,对传统的Cold FET测量技术和寄生元件参数提取提出了改进方法,大栅宽器件引入了脉冲I-V曲线的测试方法,改进了EEFET/EEHEMT模型的I-V模型和Q-V模型.利用在片测试技术与建模软件相结合,建立了新的二维电荷模型,给出了建模实例和验证结果.     

Simple RLCG model for category-5 cables

A simple RLCG channel model for category-5 cables is presented. Using this presented RLCG model, both frequency- and time-domain characteristics of a category-5 cable plant can be obtained by software     

A numerical weather prediction model—Computational aspects on the CRAY-1

This paper presents a case study in the design and implementation of a numerical weather prediction model on a supercomputer (CRAY-1). Following a historical introduction to the evolution of the model, the governing equations of the model are presented and the numerical solution of these forecast equations is described. A brief tutorial on the architecture of the CRAY-1 is presented with a discussion of how it affects the choice of algorithms and code design of the model. A summary of the advantages gained by use of the vector aspects of the CRAY-1 is included.     

分布式自适应安全策略在Mobile IP中的应用

简要介绍Mobile IP网络安全基本原理,分析集中式静态配置安全策略给MobileIP网络性能和灵活性造成的缺陷,提出动态自适应安全策略调整模型,并在该模型的基础上提出分布式动态自适应防火墙安全策略。最后讲述该安全策略在Mobile IP网络环境中的实现,论证该策略模型能很好满足当前网络环境对网络安全性能和灵活性的需求。