Uniform physical theory of diffraction equivalent edge currents fortruncated wedge strips

New uniform closed-form expressions for physical theory of diffraction equivalent edge currents are derived for truncated incremental wedge strips. In contrast to previously reported expressions, the new expressions are well behaved for all directions of incidence and observation and take a finite value for zero strip length. This means that the expressions are well suited for implementation in general computer codes. The new expressions are expressed as the difference between two terms. The first term is obtained by integrating the exact fringe wave current on a wedge along an untruncated incremental strip extending from the leading edge of the structure under consideration. The second term is calculated from an integration of the asymptotic fringe wave (FW) current along another untruncated incremental strip extending from the trailing edge of the structure. The new expressions are tested numerically on a triangular cylinder and the results are compared with those obtained using the method of moments and the previously reported expressions     

关于S—盒的布尔函数表达式

提出一种求S—盒的布尔函数表达式的系统方法,并由此法推出了DES中所有S—盒的布尔函数表达式,根据这些布尔函数表达式又导出了DES中S—盒的几点简单性质。     

Network Reliability Evaluation Using Probability Expressions

The terminal-pair reliability of a graph (network) is evaluated by means of probability expressions. These expressions result from a transformation of Boolean expressions from the Boolean domain into the probabilistic domain. Basic operations on probability expressions are shown, and a data representation is given for automation of the procedure. The performance of this procedure is compared with other published results. Two new measures, PRI and POST, give relationships between a network's terminal-pair reliability and individual element reliabilities, and derive an element ordering for network diagnosis. These measures can be computed easily using probability expressions.     

基于2D几何与纹理信息分离模型的表情分析与合成

本文提出一种用于特定人逼真表情图像合成的新方法，该方法利用二维网格描述部呈现不同表情时的几何变化，并使用一分析方法将该网格序列用参数化模型表示，从而极大地压缩了数据，在重构表地利用参考帧提供了场景纹理信息，结合网格参数模型提供的几何信息，使用图像卷曲与插值技术，生成逼真表情图像，目前使用方法对人脸下部半表情图像分析及合成进行了初步的实验，实验结果表明了该种方法的有效性。     

Expression transfer for facial sketch animation

This paper presents a hierarchical animation method for transferring facial expressions extracted from a performance video to different facial sketches. Without any expression example obtained from target faces, our approach can transfer expressions by motion retargetting to facial sketches. However, in practical applications, the image noise in each frame will reduce the feature extraction accuracy from source faces. And the shape difference between source and target faces will influence the animation quality for representing expressions. To solve these difficulties, we propose a robust neighbor-expression transfer (NET) model, which aims at modeling the spatial relations among sparse facial features. By learning expression behaviors from neighbor face examples, the NET model can reconstruct facial expressions from noisy signals. Based on the NET model, we present a hierarchical method to animate facial sketches. The motion vectors on the source face are adjusted from coarse to fine on the target face. Accordingly, the animation results are generated to replicate source expressions. Experimental results demonstrate that the proposed method can effectively and robustly transfer expressions by noisy animation signals.     

The spatially averaged electric field in the near field and far field of a circular aperture

This paper presents a theoretical and numerical investigation of the spatially averaged electric field in the beam of a circular aperture. The investigation leads to closed-form analytical expressions, based on scalar diffraction theory, which describe the spatially averaged electric field in the Fresnel region of a circular aperture excited by a spatially uniform, harmonic plane wave. The expressions ultimately permit rapid, practical, and efficient prediction of certain routine electromagnetic measurements. Because the expressions are valid in the Fresnel region, they are also valid in the near field, the far field, and the Fraunhofer region of a circular aperture. In fact, it is shown that the closed-form expressions contain, as special cases, classic on-axis and far-field results associated with a circular aperture. The analytical expressions are based on a generalization of Fresnel diffraction originally developed by Lommel in the late 1800s. Hence, a thorough review of the literature on the Lommel diffraction formulation is presented. Finally, it is shown that results obtained from the closed-form expressions compare quite favorably to results obtained from the exact solution computed via the dyadic Green's function approach.     

Effective electromagnetic properties of honeycomb composites, and hollow-pyramidal and alternating-wedge absorbers

Closed-form expressions for the effective electromagnetic material properties of honeycomb composites and electromagnetic absorbers constructed in the shapes of alternating wedges and hollow pyramids are presented. These expressions can be used to efficiently calculate the interaction of electromagnetic fields with periodic structures of said geometries. The effective material properties from these expressions are compared to results obtained from a numerical solution of the actual cross-sectional geometry. Finally, we give guidance on how the expressions presented here and elsewhere can be used for other types of periodic geometries.     

MIMO channel statistics in the presence of non-uniform angle spread

We give analytical expressions for correlation, spectrum, level crossing rate, and average fade duration for the multiple-antenna fading channel in the presence of nonuniform power azimuth spectrum (PAS). Classical expressions for uniform PAS are a special case of these expressions. The expressions are valid for any antenna patterns and for any PAS.     

CDMA系统中切换性能的界限和变动范围

该文提出了CDMA系统中切换性能的3个界限的数学表达式,以及建立在界限基础上的硬切换性能差异、软切换性能差异和软切换增益的变动范围的表达式,并通过这些公式对切换的性能空间做了划分和限定。作为上述分析的数学基础,该文推导了硬切换和软切换中断概率的表达式。最后,通过对WCDMA(FDD)系统的仿真,证明了切换的界限、变动范围和中断概率的公式的正确性,并且指出,使用它们刻划实际切换算法的性能将比Viterbi的估计更为准确和恰当。     

锯齿调频连续波建模与数值仿真

锯齿调频连续波由于测距精度高,在测距系统中有着广泛的应用.为了描述锯齿调频连续波多个调频周期中的频率和相位变化及跨越调频周期时的不连续性,结合具有一定周期性和不连续性的模数函数,推导了锯齿调频连续波的频率和相位的数学表达式,并进行建模及仿真.通过对频率与相位的微积分关系的推导解析地验证了数学表达式的正确性.数值仿真结果也表明:频率和相位的数学表达式满足微积分的关系,是频率与相位的正确的表达式,能够描述锯齿波调频在跨越调频周期时的不连续性.提出的锯齿调频连续波的多调频周期频率与相位表达式可为进一步研究锯齿调频连续波测距过程提供基础.     

Advances in the performance of Reed-Solomon codes

This paper presents generalized expressions for the probabilities of correct decoding and decoder error for Reed-Solomon (RS) codes. In these expressions, the symbol error and erasure probabilities are different in each coordinate in a codeword. The above expressions are used to derive the expressions for reliability and delay for Type-I hybrid ARQ (HARQ-I) systems when each symbol in a packet (multiple codewords per packet) has unique symbol error and erasure probabilities. Applications of the above results are demonstrated by analyzing a bursty-correlative channel in which the symbols and codewords within the packet are correlated     

Availability of a Renewable, Checked System

Recurrent expressions are given for point and interval unavailability of a renewable system subjected to periodic checking/repair. The expressions are generalizations of the basic relations in the theory of discrete renewal processes. The asymptotic limits for long times follow simply from a general theorem of this theory. The connection to previous expressions is established.     

Harmonic and intermodulation performance of Josephson junctions

In this paper a simple mathematical model is presented for the inherent resistive nonlinearity of a Josephson junction. By incorporating this model in the RSJ model of the Josephson junction, series expressions are obtained for the harmonic and intermodulation performance of Josephson junctions irradiated by multisinusoidal signals. Special cases are considered where the series expressions can be reduced to simple analytical expressions.     

Electromagnetic field of a rectangular patch of uniform and lineardistributions of current

Closed-form expressions for a class of indefinite double integrals are presented. Using these formulas, exact analytical expressions for the magnetic vector potential and the electric and magnetic fields of a rectangular patch of uniform and linear distributions of electric current in an unbounded homogeneous medium are derived. The field expressions obtained are valid everywhere, in particular in the source region. Computed results verifying the correctness and accuracy of these expressions are presented     

On uniform asymptotic Green's functions for the perfectly conducting cylinder tipped wedge

Uniform asymptotic expressions are derived for the Green's functions describing scattering of electric or magnetic type plane waves by a perfectly conducting cylinder tipped wedge (CTW). These expressions are found to agree analytically with heuristic expressions available using the geometrical theory of diffraction (GTD). Numerical comparison of these expressions with results obtained from eigenfunction expansions show good agreement for cylinder diameters >1.5 lambda.     

On Crossbar Switching Networks

For networks that exhibit neither concentration nor expansion, the well-known probabilistic model of C. Y. Lee is refined so as to take account of the dependence of events in different stages. For series-parallel networks, the refined model yields exact expressions for the point-to-point blocking probability. These expressions bear the same relationship to the refined model as the KittredgeMolina expressions do to Lee's model. Comparison between the two sets of expressions shows that Lee's model tends to overestimate the blocking probability. Asymptotic analysis of the new expressions leads to improved upper bounds on the cost: it is shown that a network that carriesNerlangs with a blocking probability at mostepsilon > 0can be built with6N log_{2} N + O(N log log 1/epsilon)contacts.     

多晶硅发射极晶体管h_(FE)、G_e、和K的普遍表达式及其分类

本文综合考虑了影响多晶硅发射极晶体管(PET)电流增益的多种因素,针对最全面的器件结构推导出PET的共发射极直流电流增益h_FE发射极Gummel数G_e,和电流增益的增强因子k解析形式的普遍表达式,覆盖了PET的多种结构。并以此对PET从器件结构上进行了科学地分类。此普遍表达式也包含了Ning和Graaff的理论结果。     

Closed-form expressions for uniform currents on a wedge illuminatedby TM plane wave

Closed-form expressions for nonuniform currents on a perfectly conducting, infinite wedge illuminated by a transverse magnetic plane wave are presented. The expressions are derived by requiring that they agree with the current predicted by the eigenfunction solution close to the edge and J.B. Keller's geometrical theory of diffraction (1962) far from the edge. The angle of incidence is arbitrary and the expressions remain uniformly valid even for glancing angles of incidence when the geometrical optics boundaries are in the vicinity of the wedge faces. The formulas presented are simple, involving Fresnel functions with complex arguments. These functions can be expressed in terms of complimentary error functions which may be computed using standard subroutine packages. Exact expressions for nonuniform currents are available for the two special cases of half-planes and infinite planes. Closed-form expressions for the axial electric field, and hence all the field components in the vicinity of the wedge axes, are also obtained. Currents computed using expressions obtained are compared with currents computed from the eigenfunction solution of the wedge, with good agreement throughout