EM field prediction inside lossy multilayer elliptic cylinders for biological-body modeling and numerical-procedure testing

In this paper, a biological model made up of a multilayer elliptic cylinder is considered. This canonical scattering problem is solved by a recursive procedure, which has been generalized to the case of lossy materials by using the analytical properties of Mathieu functions. Although it is a simplified model, this stratified configuration may simulate better than circular cylinders the local behavior of biological subsystems. In addition, it represents an effective tool for producing analytical data for testing direct-scattering numerical codes in biomedical applications and for the evaluation of reconstruction procedures in medical imaging.     

A multilayer complex neural network training algorithm and its application in adaptive equalization

In this paper, the layer-by-layer optimizing algorithm for training multilayer neural network is extended for the case of a multilayer neural network whose inputs, weights, and activation functions are all complex. The updating of the weights of each layer in the network is based on the recursive least squares method. The performance of the proposed algorithm is demonstrated with application in adaptive complex communication channel equalization.     

Electromagnetic scattering by weakly lossy multilayer ellipticcylinders

The analytic solution to the electromagnetic scattering due to a multilayer elliptic cylinder is generalized to the case of weakly lossy materials by using a first-order truncation of the Taylor expansion of each Mathieu function     

Electromagnetic scattering by a multilayer elliptic cylinder undertransverse-magnetic illumination: series solution in terms of Mathieufunctions

An exact solution to the electromagnetic scattering by a dielectric multilayer infinite cylinder of elliptic cross section is proposed. The interfaces between different media, which are assumed to be lossless and nonmagnetic, are confocal elliptic cylinders. Starting from the series expansions in terms of Mathieu functions, an efficient recursive procedure for the computation of fields and radar cross sections per unit length under a transverse-magnetic illumination is developed. The mathematical formulation is detailed and some numerical results are provided     

An Alternative Algorithm for Both Narrowband and Wideband Lorentzian Dispersive Materials Modeling in the Finite-Difference Time-Domain Method

In this study, an alternative algorithm is proposed for modeling narrowband and wideband Lorentzian dispersive materials using the finite-difference time-domain (FDTD) method. Previous algorithms for modeling narrowband and wideband Lorentzian dispersive materials using the FDTD method have been based on a recursive convolution technique. They present two different and independent algorithms for the modeling of the narrowband and wideband Lorentzian dispersive materials, known as the narrowband and wideband Lorentzian recursive convolution algorithms, respectively. The proposed alternative algorithm may be used as a general algorithm for both narrowband and wideband Lorentzian dispersive materials modeling with the FDTD method. The second-order motion equation for the Lorentzian materials is employed as an auxilary differential equation. The proposed auxiliary differential-equation-based algorithm can also be applied to solve the borderline case dispersive electromagnetic problems in the FDTD method. In contrast, the narrowband and wideband Lorentzian recursive convolution algorithms cannot be used for the borderline case. A rectangular cavity, which is partially filled with narrowband and wideband Lorentzian dispersive materials, is presented as a numerical example. The time response of the electric field z component is used to validate and compare the results     

高效处理基于递归层次的上翻操作

上翻(Rollup)作为OLAP的核心操作,将多维数据按维层次聚集,使用户能够在不同粒度上对数据进行观察。尽管基于常规层次的上翻操作,可被数据仓库高效地处理。然而,对于递归层次而言,由于SQL递归对于聚集函数分层的限制,如果将上翻操作表示为SQL递归查询,则会导致效率低下。为解决这一效率问题,文中专门针对OLAP的特点,提出了一个基于迭代的上翻操作计算策略,并利用对象关系技术,将这一策略无缝地嵌入到数据仓库之中。实验表明,其效率远远高于SQL递归计算策略。     

多层手征介质填充圆波导的分析

本文利用递推本征函数法分析了多层手征介质填充圆波导的传播特性.文中给出了不同介质层中电磁场的递推关系,推导了N层手征介质填充圆波导色散特性的一般性计算公式.作为示例,文中还给出了对几种结构传播特性的计算结果.     

改进的非线性最小二乘算法训练多层前馈神经网络

本文通过在普通非线性最小二乘算法的准则函数中加一个正则项，推导出一种改进的非线性最小二乘算法，包括地的批处理形式和递推形式，使用该算法的递推形式训练多层前馈神经网络能克服病态，减少计算量和内存占用量，文中给出的仿真结果说明该算法具有比常的ＢＰ算法更好的收敛性能。     

Scattering by a multilayer chiral cylinder

An efficient recursive eigenfunction solution for the problem of scattering by a multilayer chiral circular cylinder, with or without a surface impedance center cylinder, is presented. For an M layer cylinder, the solution requires the multiplication of M4×4 matrices, versus the solution of a 4M×4M matrix equation in a standard approach. The problem of a transverse electric (TE) incident plane wave differs from that of a transverse magnetic (TM) wave only by a plus/minus sign at one step in the solution. The addition of the surface impedance center cylinder requires only one additional matrix multiplication. Numerical results, including echo width and internal fields, are presented for several sample cylinders     

多层神经网络同伦连续BP算法的递归实现

本文提出了一种递归实现的同伦连续ＢＰ算法，该算法可有效地解决ＢＰ网络的全局收敛性问题，同时使网络具有很快的收敛速度。     

Dielectric materials, devices, and circuits

Dielectric materials are continuing to play a very important role in the microwave communication systems. These materials are key in realization of low-loss temperature-stable resonators and filters for satellite and broadcasting equipment, and in many other microwave devices. High dielectric-constant materials are critical to the miniaturization of wireless systems, both for the terminals and base-stations, as well as for handsets. In this paper, a sequential evolution of the dielectric materials applications in microwave devices will be reviewed. This includes dielectric waveguides, low-loss temperature-stable ceramic materials, dielectric resonators, and filters. The recent advances in the multilayer circuit modules, dielectric antennas, and ferroelectrics are also described     

A multilayer solution for path provisioning in new-generation optical/MPLS networks

This paper proposes an offline solution for global path provisioning in new-generation optical networks based on the generalized multiprotocol label switching (GMPLS) paradigm. This solution is based on a multilayer approach, which involves both the optical and the electrical layers and optimizes the network configuration and traffic routing. The proposed global provisioning solution can be easily combined with dynamic routing solutions, providing the network with the possibility of reacting promptly to traffic changes. Data flows are assumed to be structured into label switched paths (LSPs), which represent the connection in a GMPLS-based network, at any hierarchical level. The global provisioning issue is a difficult optimization problem. As a solution, we propose a new heuristic algorithm based on the shortest path computation and a mathematical programming approach, which makes use of the optimization solver CPLEX. A large computational study shows the effectiveness of the former, in terms of quality of the solutions. The advantages of the multilayer provisioning strategy are analyzed in a relevant case study by evaluating the network congestion.     

Transient temperature fields with general nonlinear boundary conditions in electronic systems

Green's function representations of the solution of the heat conduction equation for general boundary conditions are generalized for the nonlinear, i.e., temperature dependent case. Temperature dependent heat transfer coefficients lead to additional terms in the Green's function representation of the temperature field. For a rectangular structure with averaged homogeneous material parameters several types of Green's functions can be chosen especially simple, because of the new representation with the possibility of differing types of boundary conditions for the temperature field and the Green's function. Exact finite closed form expressions for three-dimensional-Green's functions in the time domain using elliptic theta functions are presented. The temperature field is a solution of a nonlinear integral equation which is solved numerically by iteration. The resulting algorithm is very robust, stable and accurate with reliable convergence properties and avoids matrix inversions completely. The algorithm can deal with all sizes of volume heat sources without additional grid generation. Large and small size volume heat sources are treated simultaneously in the calculations that will be presented. Heat transfer coefficients are chosen representing radiative and convective boundary conditions. An extension of the solution algorithm to composed multilayer systems of arbitrary geometry is outlined.     

Frequency dispersive materials for 3-D hybrid solvers in time domain

The recursive convolution method to treat linear dispersive materials in the finite difference time domain (FDTD) is here generalized to an explicit finite volume solver and an implicit finite element solver. Both solvers are interfaced to FDTD resulting in two hybrid solvers. The stability of the solvers is analyzed and the accuracy is demonstrated in several scattering cases, where a plane wave illuminates a sphere with complex permittivity. Excellent agreement with the analytical Mie series solution is obtained for materials of Debye and Lorentz type as well as for a material consisting of two Lorentz poles.     

On the Delay Analysis of a TDMA Channel with Finite Buffer Capacity

The throughput performance of a TDMA channel with finite buffer capacity for transmitting data messages is considered. Each station has limited message buffer capacity and has Poisson message arrivals. Message arrivals will be blocked if the buffers are congested. Using the embedded Markov chain model, the solution procedure for the limiting system-size probabilities is presented in a recursive fashion. Numerical examples are given to demonstrate the tradeoffs between the blocking probabilities and the buffer sizing strategy.     

Analysis of a Mobile Radio Communication System with Two Types of Customers and Priority

In this paper an analytical method is developed to determine the performance of a system with two types of customers and "cutoff" priority. A completely recursive solution and a solution involving matrix inversion are provided. Some examples from the mobile radio communication system are considered to illustrate applications of the method. This paper is an extension of the case for equal service rate for the two classes.     

Electron beam enhanced multilayering and planarization inpreimidized polyimides

High-density packaging and interconnection applications frequently involve the use of polyimide-based materials as interlevel dielectrics for multilevel interconnection schemes. Surface planarity after each polymer layer is very important to the fabrication of multilayer structures. Highly nonplanar surfaces were observed in a multilayer test structure, fabricated using a thermally cured polyimide (Ultradel 7501). In this study, the effect of a novel cure technique involving electron beam (e-beam) exposure on multilayering and planarization behavior in Ultradel 7501 is investigated. Planarization measurements were conducted on different feature sizes and at various locations on the wafer in order to investigate the effect of solvent exposure, time and area of contact between multiple layers. The degree of planarization was found to improve from -206% for a thermally cured case to +15% for an e-beam cured sample. Analysis of the solvent induced polymer swelling and its effect on multilayer planarization of Ultradel 7501 is presented     

One-sided recursive filters for two-dimensional random fields (Corresp.)

The one-sided (or line-by-line) recursive filtering problem for a two-parameter Gaussian random signal in additive white Gaussian noise is considered. For a reasonably large class of models for the signal dynamics, both the filtering equation and the generalized Riccati equation explicitly obtained. As an example, the Riccati equation is solved to give the filter gain in a time-in-variant case and is compared with the infinite-time limiting solution to the Wiener filter solution obtained by spectral factorization techniques.     

Polynomial perceptrons and their applications to fading channelequalization and co-channel interference suppression

This paper investigates the behaviors of polynomial perceptrons and introduces a fractionally spaced recursive polynomial perceptron with low complexity and fast convergence rate. The nonlinear mapping ability of the polynomial perceptron is analyzed. It is shown that a polynomial perceptron with degree L(⩾4) satisfies the Stone-Weierstrass theorem and can approximate any continuous function to within a specified accuracy. Moreover, the nonlinear mapping ability of a polynomial perceptron with degree L is similar to that of the three-layer perceptron with one hidden layer for time same number of neurons in the input layer. The nonlinear mapping ability of the fractionally spaced recursive polynomial perceptron is also presented. Applications of polynomial perceptrons for fading channel equalization and co-channel interference suppression in a 16-level quadrature amplitude modulation receiver system are considered. Computer simulations are used to evaluate and compare the performance of polynomial perceptron (PP) and fractionally spaced bilinear perceptron (FSBLP) with that of the synchronous decision feedback multilayer perceptron (SDFMLP), fractionally spaced decision feedback multilayer perceptron (FSDFMLP), and the conventional decision feedback equalizer (DFE). The results show that the performance of the fractionally spaced bilinear perceptron is clearly superior to that of the other structures     

Refractive index approximations from linear perturbation theory forplanar MQW waveguides

The mode powers and propagation constants for planar multilayer waveguides formed with multiple quantum well (MQW) materials and with the MQW layers replaced by a single uniform layer are compared. By considering linear perturbations of the solutions of the wave equation, the optimal choice of average for the dielectric constant of the substituted single layer is determined. For the case of TE modes, minimal error in the propagation constant is predicted if a weighted average of the dielectric constants of the MQW materials is used. For the case of TM modes, using a weighted average of the reciprocal of the dielectric constants is predicted to yield the minimum error. Numerical results confirm these predictions