非子午绕组偏转器磁场的分析与计算

本文给出了鞍形和环形非子午绕组偏转器磁标位和特性函数的解析式.对彩色显象管和电子束曝光机等的偏转线圈设计具有实际意义.理论计算与实测结果符合良好.     

地下水平电偶极子在均匀球形地面产生的侧面波

讨论了位于地下的水平电偶极子在均匀球形地面上产生的侧面波（Lateral wave)。从位于球形地面场的垂直电偶极子和磁偶极子在地面上建立的电磁场出发，利用互易定理，获得了地下水平电偶极子在地面上和地面下产生的既方便于数值计算又具有足够精度的电磁场的解析表达式。计算结果表明，由于地球曲率的影响，沿球形地面传播的侧面波比沿平行地面传播的侧面波衰减的快，当收发地点的距离超过40km后，地球曲率对传播的影响就不能被忽视，对地下通信以及潜艇通信有一定指导意义。     

Simple expressions for the directivity of a circular microstrip antenna

We present two sets of simple, closed-form expressions for accurately computing the directivity of a circular microstrip antenna on thin and thick substrates of any relative permittivity. These expressions are useful for computation by a hand calculator and, therefore, useful to a practical antenna designer.     

Loss Calculations for Coupled Transmission-Line Structures (Correspondence)

Expressions are derived for computing loss in coupled TEM structures in terms of complex even- and odd-mode propagation constants and characteristic impedances of the lines. The attenuation due to conductor (series) and dielectric (shunt) losses in a given structure can be determined utilizing these expressions. The results may be particularly useful for computing conductor loss in microwave circuits with a large number of sections used in traveling-wave devices and as microwave circuit elements. The method is applied to some typical structures for computing conductor loss.     

On the reliability of links in a ring network

This paper analyzes the reliability of links in a computer network which is configured in a ring topology. It will be shown that the expression for reliability of elements connected in series is not adequate for computing the reliability of links in a ring network. Consequently, new expressions for computing such reliability for rings with and without back-up links are proposed. Furthermore, an optimal back-up links assignment which guarantees optimal links reliability is formulated.     

异质结耗尽层基区侧复合对突变HBT重要性分析

基于热场发射.扩散载流子输运模型,在电流连续性方程中包含异质结(BB结)耗尽层基区侧复合电流的前提下,推导出了描述突变HBT电流特性的新解析方程.在此基础上,探讨了对BB结耗尽层基区侧复合电流各不同考虑情况下的HBT电流计算结果的差异程度.结果表明:在较高集电极电流密度处,E-B结耗尽层基区侧的复合电流很重要;此外,在电流连续性方程中包含E-B结耗尽层基区侧的复合电流,这在更高集电极电流密度处也是必要的.     

Machine Interpretation of Facial Expressions

Facial expressions are an important source of information for human interaction. Therefore, it would be desirable if computers were able to use this information to interact more naturally with the user. However, facial expressions are not always unambiguously interpreted even by competent humans. Consequently, soft computing techniques in which interpretations are given some belief value would seem appropriate. This paper describes how the mass assignment approach to constructing fuzzy sets from probability distributions has been applied to the low-level classification of pixels into facial feature classes based on their colour. It will also describe how similar approaches can be used for the analysis of facial expressions themselves.     

Closed‐form solutions to SEP integrals over generalized fading distributions η−μ and κ−μ using approximate computing

The fading channels often involve complex expressions, when it comes to computing the integrals required for performance evaluation of various digital modulation schemes. In this paper, usefulness of exponential‐based approximations to the Gaussian‐Q function in computing these integrals is discussed. We present generic symbol error probability (SEP) expressions over η?μ and κ?μ fading distributions, which can be tailored for any digital modulation technique using different approximations. The resulting expressions thus obtained comprise only elementary mathematical functions thereby avoiding complex evaluations of hypergeometric functions. We explore all the exponential‐based approximations proposed till date and conclude that apart from being mathematically simple, they also lead to accurate expressions for performance analysis of various digital modulation schemes.     

垂直电偶极子在涂敷介质导电平面上激起的场Ⅱ

对垂直电偶极子（VED）在涂敷介质层的非理想导电基底上激起的电磁场进行了讨论,获得了便于计算的解析表达式,并进行了数值计算。     

人眼多线谱及其获取

该文给出了一种描述人眼运动及表情的多线谱表示及其获取的方法。该方法以人眼三维肌肉控制模型(3D-MCE)为基础,用一组归一化肌肉收缩量随时间变化的多线谱曲线来表示人眼运动及表情;给出了由单视频获取人眼多线谱的方法,通过跟踪人眼控制点的位移,计算肌肉收缩量,进而获得其随时间变化的曲线。实验结果表明,所获得曲线能较逼真地模拟人的眼部运动和部分表情。     

Average channel capacity for generalized fading scenarios

Novel expressions for the average channel capacity (ACC) of single-branch receivers operating in generalized fading channels, namely eta-mu and kappa-mu, are derived. The expressions are written in terms of the well-known Meijer's G-functions, which are easily implemented in the most popular computing softwares. In addition, it is shown that, for any given fading condition, the Nakagami-m ACC defines regions of capacity: it lowerbounds the eta-mu ACC and it upperbounds the kappa-mu ACC. In the same way, it lowerbounds the alpha-mu ACC for alpha < 2 and mu > m, and it upperbounds the alpha-mu ACC for alpha > 2 and mu < m.     

Efficient procedure for computing fields created by current modes

An efficient method for computing the fields of large scatterers is presented. The current is expanded in terms of modes defined as complex exponential functions. The modes are represented efficiently by means of spline functions. Analytical expressions have been obtained to compute efficiently the fields due to the current modes.     

An Efficient Formula for Estimating the Generalized Moments of the Power Spectral Density (PSD) Without Computing the Fourier Transform

Estimates of the moments of the power spectral density (PSD) are derived from a rapidly converging series of weighted samples of the autocorrelation function (ACF). As a result of the rapid convergence of the weighting coefficients of this series, accurate PSD moment estimates are obtained from a small number of ACF samples without computing the Fourier transform of the time series, thereby greatly reducing the computational requirements for generatiing the generalized moments of the PSD. The general expression for the moment generating series is presented along with explicit expressions for computing the first four moments from which mean, variance, skewness, and kurtosis of the PSD are obtained.     

On modeling coverage and rate of random cellular networks under generic channel fading

In this paper we provide an analytic framework for computing the expected downlink coverage probability, and the associated rate of cellular networks, where base stations are distributed in a random manner. The provided expressions are in computable integral forms that accommodate generic channel fading conditions. We develop these expressions by modeling the cellular interference using stochastic geometry analysis, then we employ them for comparing the coverage resulting from various channel fading conditions namely Rayleigh and Rician fading, in addition to the fading-less channel. Furthermore, we expand the work to accommodate the effects of random frequency reuse on the cellular coverage and rate. Monte-Carlo simulations are conducted to validate the theoretical analysis, where the results show a very close match.     

Exact evaluation of maximal-ratio and equal-gain diversityreceivers for M-ary QAM on Nakagami fading channels

Exact integral expressions are derived for calculating the symbol-error rate (SER) of multilevel quadrature amplitude modulation (MQAM) in conjunction with L-fold antenna diversity on arbitrary Nakagami fading channel. Both maximal-ratio combining (MRC) (in independent and correlated fading) and equal-gain combining (EGC) predetection (in independent fading) diversity techniques have been considered. Exact closed-form SER expressions for two restricted Nakagami fading cases (MRC reception) are also derived. An exact analysis of EGC for MQAM has not been reported previously, despite its practical interest. Remarkably, the exact SER integrals can also be replaced by a finite-series approximation formula. A useful procedure for computing the confluent hypergeometric series is also presented     

矩形涂层板的电磁散射

本文讨论了涂覆有耗介质的矩形平板的电磁散射。涂层介质的参数可以任意。表达式中涉及的Maliuzhinets函数的计算,由于采用了多项式近似,避免了复平面内的积分,从而使计算时间大为减少。最后将理论计算结果与实验值相比较,两者吻合得很好。     

Modeling and analysis of standby redundant computing systems

In this paper, we have developed performance models to represent the fault-tolerant characteristics of standby redundant computing systems. These models have the advantage of being quite general and are useful to study the performance characteristics under any arbitrary life time distribution for the components of the system. For the proposed models, we have derived expressions for three performance metrics for these systems.     

Fast computation of the exact FIM for deterministic signals incolored noise

A fast algorithm for computing the exact finite-sample Fisher information matrix (FIM) for the parameters of a deterministic signal observed in Gaussian AR noise is derived. In the case of a harmonic signal with random phases, closed-form expressions for the finite-sample posterior Cramer-Rao bound (PCRB) are established. It is shown that the fast algorithm is also useful for computing the conditional CRB when the additive noise is a non-Gaussian AR process. It is seen that the asymptotic CRB may deviate significantly from the exact CRB even when the data length is moderate, whereas the PCRB, which is easy to compute, provides a better approximation. Theoretical results are illustrated via numerical evaluation of the different lower bounds     

Analysis of M-ary phase-shift keying with diversity reception forland-mobile satellite channels

An analytical technique well suited to numerical analysis is presented for computing the average bit-error rate (BER) and outage probability of M-ary phase-shift keying (PSK) in the land-mobile satellite channel (LMSC) with microdiversity reception. Closed-form expressions are found for L-branch microdiversity using both selection diversity combining (SDC) and maximal ratio combining (MRC). These expressions are extended to include both M-ary coherent PSK (M-PSK) and differential PSK [M-differential PSK (DPSK)]. Following previous empirical studies, the LMSC is modeled as a weighted sum of Rice and Suzuki distributions. Numerical results are provided illustrating the achievable performance of both M-PSK and M-DPSK with diversity reception. Using measured channel parameters, the performance in various mobile environments for various satellite elevation angles is also found     

Walsh Series Expansions of Probability Distributions

This paper discusses the representation of probability distribution functions by Walsh series expansions. Generally, such expansions may be employed for the representation of multivariate distributions. However, we confine attention here to univariate and bivariate distributions. The resulting expansions are consequently utilized in the derivation of useful expressions for the moments of corresponding probability distributions. Applications of Walsh expansions of probability distributions are further illustrated by computing output moments for some general classes of nonlinear systems.