bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of passive microwave devices by using three‐dimensional tangential vector finite elements
Authors: Lee Jin‐Fa 
Published: August 2005

AbstractThere are two major difficulties in applying the finite element method to the analysis of microwave devices in three dimensions. One is to obtain a stable vector finite element which does not generate spurious modes, or non‐physical solutions, in the numerical analysis. The other is to model efficiently the coupling of port regions and the discontinuity region. In this paper, we describe the application of two new finite element techniques, the tangential vector finite element method and the transfinite element method, for modelling three‐dimensional microwave devices. The tangential vector finite element method, unlike the conventional nodal finite element methods, imposes only the tangential continuity of the vector unknown across elements' boundaries. As a result, there would be no spurious modes, and reliable solutions are obtained. The transfinite element method, which combines the modal basis functions and the finite element basis functions through the variational technique, provides an efficient way to model the open boundary nature of the device. To validate the current analysis, a low VSWR waveguide connector and two microstrip low‐pass filters are analysed. Numerical results agree very well with the measurements or those obtained by other methods.
Multiple multipole (MMP) computations of guided waves and waveguide discontinuities
Authors: Hafner Ch. 
Published: August 2005

AbstractThe MMP (multiple multipole) code, that is based on the generalized multipole technique (GMT), offers several features to overcome problems occurring in computations of guided waves and waveguide discontinuities. The most important problems and the corresponding MMP solutions are outlined. The procedure is illustrated with different examples which demonstrate the wide range of applications of the code.
Full‐wave analysis of multiport microstrip discontinuities using a superposition principle and mode‐matching technique
Authors: Bögelsack Frank , Wolff Ingo 
Published: August 2005

AbstractAccurate full‐wave analysis of shielded microstrip discontinuities, based on a mode‐matching technique and employing Kühn's method is presented. Finite thickness of the strip metallization is taken into account. Examples include bends, T‐junctions, and crossings.
Noise analysis of linear microwave circuits
Authors: Russer Peter , Müller Stefan 
Published: August 2005

AbstractThe fundamentals of computer‐aided noise analysis of linear noisy microwave circuits are presented. The method is based on the description of noisy networks by correlation matrices, and allows the noise analysis of linear circuits of general topology exhibiting arbitrary correlations between the noise sources. The description of linear noisy networks by correlation matrices in different representations, the interconnection of noisy networks and the nodal analysis of noisy networks are treated. The correlation matrices of circuits or subcircuits exhibiting thermal noise may be calculated directly from its admittance matrix. The application of the method for the noise analysis of linear microwave amplifiers is discussed.
Concurrent processing applied to the Exodus Monte Carlo technique
Authors: Fusco V. F. 
Published: August 2005

AbstractThis paper illustrates how problems based on the Probabilistic Potential Method can be solved using a parallelized form of the Exodus Monte Carlo technique. The Exodus technique which does not use random number generation is shown to be more efficient for moderately large problems than the conventional fixed random walk method when programmed in both sequential and concurrent forms.The technique is illustrated for an electrostatic field problem by using as an example internal potential evaluation for a rectangular coaxial line. The problem geometry is torn into subsections which are then analysed independently using concurrent programming methods. The resulting algorithm is compared with the same problem executed using a conventional sequential algorithm. Computation is achieved by use of an array of transputers. The design of the concurrent algorithm is described in detail and typical results are compared with the fixed random walk Monte Carlo method and also with the finite difference relaxation method. Parallel Fortran is used throughout as the programming language.
Solving the helmholtz equation using multiply propagated fields
Authors: Miller E. K. , Gilbert M. A. 
Published: August 2005

AbstractComputer models in electromagnetics are based primarily either on integral or on differential equations. The former arise from source integrals using some appropriate Green's function whereas the latter originate from the Maxwell curl equations. Although requiring volume rather than surface sampling even for spatially homogeneous problems, in contrast to integral‐equation (IE) models, differential‐equation (DE) models are geneally a better choice for problems involving spatial inhomogeneities. This is because such problems require volumetric sampling using either approach, but the DE model produces a sparse matrix rather than the full matrix of the IE formulation.In this paper we describe a new approach based on using multiply propagated fields for numerically solving the banded matrix that results from discretizing the Helmholtz equation. A computer‐time savings of N1/2 and N2/3 for two‐dimensional (2‐D) and three‐dimensional (3‐D) problems, respectively, is made possible, where N is the total number of field samples or unknowns. For even moderate‐size problems where 100 samples per linear dimension are used (N2 = 10,000 and N3 = 1,000,000), the time savings can be of the order of 100 and 10,000 respectively. Another advantage of this procedure, which we call Helmholtz equation multiple propagator (HEMP), is that the radiation or closure condition needed to terminate the spatial solution mesh for exterior problems can be enforced rigorously with essentially no additional computational cost.The method is illustrated for a 2‐D problem by application to plane‐wave scattering from an infinite, metal, circular cylinder. Results are presented for the mode amplitudes of the scattered field, the induced surface current, and the bistatic far field as obtained from HEMP, and shown to be in good agreement with the analytical results. Although limited here to the simplest possible application in order to establish its feasibility, the approach's advantage would be its applicability to 2‐D and 3‐D problems involving inhomogeneous, penetrable objects.
Transmission‐line modelling in electromagnetic compatibility studies
Authors: Herring J. L. , Naylor P. , Christopoulos C. 
Published: August 2005

AbstractThe transmission‐line modelling (TLM) method is applied to problems in electromagnetic compatibility (EMC). Simulated results for a field‐to‐wire coupling problem are presented, together with comparisons with experimental results. The comparisons confirm the validity of the model and its accuracy. The effects on resonances and field profiles, of placing a measurement dipole antenna inside a screened room are investigated. The resonant structure inside an unlined screened room and the same room when lined with radiation‐absorbing material are investigated using a TLM model. The results confirm that the model developed can be used for the characterization of the entire EMC test environment.
Time‐domain integral equations for EMP analysis
Authors: Gomez R. , Salinas A. , Bretones A. Rubio , Fornieles J. , Martin M. 
Published: August 2005

AbstractTwo computer programs DOTIG1 and DOTIG2 were developed to calculate, in the time‐domain, the interaction of transient electromagnetic pulses (EMP) with perfect electric conductor structures modelled by thin wires (DOTIG1) or patches (DOTIG2). DOTIG1 uses the electric field integral equation and DOTIG2 the magnetic field integral equation. Briefly described below are the numerical procedures used to develop both programs and some results that show their characteristics.
A companion macromodelling approach for the transient analysis of MOS large‐scale integrated circuits
Authors: Turchetti C. , Conti M. , Masetti G. 
Published: August 2005

AbstractPurpose of this work is to present a new macromodelling approach for the simulation at the device level of large MOS integrated circuits, requiring only marginal modifications to be implemented in the widely used circuit simulator SPICE. This method results in a substantial saving in computing time and guarantees the same accuracy of SPICE. A prototype simulator based on this method has been developed and used to analyse several significant circuits. In addition, since the method is particularly suitable to be implemented in parallel computers, some results obtained with the CRAY‐YMP/432 computer are provided.
Numerical analysis of waveguide apertures radiating into lossy media
Authors: Sibbald C. L. , Stuchly S. S. , Costache G. I. 
Published: August 2005

AbstractThree numerical methods are applied to the analysis of a rectangular waveguide‐fed aperture radiating into a lossy media. A novel approach, the finite element method with an impedance boundary condition, and two established methods, the moment method and the mode‐matching method, are presented. The methods are compared with respect to accuracy, execution time, memory requirement, and versatility. Four aperture geometries are chosen for detailed study: the full aperture of the rectangular waveguide, and three reduced apertures. The reflection coefficient of the aperture in contact with five known dielectrics is calculated in the frequency range 8·5–11·5 GHz. The theoretical results are validated by measurements performed on an HP8510 network analyser.
Simulation of a class of multiprocessor machines
Authors: Diab Hassan B. , Tabbara Hassan S. 
Published: August 2005

AbstractThis paper presents the simulation of a class of MIMD systems using discrete‐event simulation enhanced by graphics‐oriented reporting. MIMD systems can be specified, modelled and simulated using the package and in turn provide estimates of certain performance indices. A multiserver queueing model is constructed to describe the flow of data and instructions through the various elements of the system. The model is composed of P processors sharing M memory modules through a user‐defined interconnection network. Graphical outputs allow the user to view the state of every processor/memory module over the simulation time with performance estimates such as the relative speedup, throughput, and utilization factor. Moreover, system performance graphs as a function of various system parameters are obtained to indicate the expected system behaviour for various loads and system configurations. The results section shows a case study of the influence of the memory modules' access time on the system performance. The purpose of the results is to aid in the analysis, understanding, design, and performance prediction of a class of MIMD systems in a user‐friendly environment.
Boundary element estimation of current density distribution and eddy current loss in bundled multi‐wire cables
Authors: Sakurai A. , Tsuchiya T. , Kagawa Y. 
Published: August 2005

AbstractA numerical approach to the estimation of the current density distribution and the eddy current loss in bundled multi‐wire cables using the boundary element method is proposed. Under the assumption of the gradual twist of the bundled wires, the cables are modelled to be two‐dimensional with respect to their cross‐sections. Three‐phase transmission lines of cyclic symmetrical configuration are considered for which a reduction method is utilized to provide efficient computation. Some numerical demonstrations are made for three types of three‐phase transmission‐line models, consisting of a single wire and three and seven bundled wires. Two cases are considered: one in which the bundled wires are electrically contacted one to another on their surfaces and one in which they are independently insulated. The equivalent resistance is also calculated to examine the skin effect. The skin effect and the effectiveness of the multi‐wire configuration to reduce the skin effect are well demonstrated.
Numerical simulation of current–voltage characteristics of silicon photoconductive circuit elements
Authors: Shakouri H. , Liou J. J. 
Published: August 2005

AbstractPhotoconductive circuit elements (PCEs) are suitable for switching applications: they can be turned on and off rapidly, they can conduct a large current in the ‘on’ state when applying a laser or other optical excitation containing high energy photons exceeding the silicon band gap energy, they have a large resistance in the ‘off’ state when the light is off, and they can be fabricated using a simple process. We report the steady‐ state characteristics of PCEs simulated from a two‐dimensional simulator called PISCES‐2B. The effects of the conducting channel length, the resistivity of the intrinsic silicon, and the type of contact region on the performance of the PCE will be investigated and discussed. Based on the simulation results, optimal PCE device make‐ups will also be suggested.
A variational approach to boundary elements—two‐dimensional Laplace problem
Authors: Sun Y. , Kagawa Y. , Murai T. 
Published: August 2005

AbstractVariational boundary element formulations are developed. Two functionals based on the dual and complementary energy approach are considered, which provide the upper and lower bound of the solution. Calculated examples of electrostatic fields are demonstrated for their field distributions and capacitances. Validity and the solution accuracy are discussed in comparison with the conventional boundary element solution.
Numerical modelling of viscous flow in silicon thermal oxidation with the boundary element method
Authors: Panjukhin A. V. , Kolobov N. A. , Leontjeva N. A. 
Published: August 2005

AbstractThis paper describes the application of the boundary element method to solving two‐dimensional steady slow viscous flow problems (creeping flow) in thermal silicon oxidation. The proposed method used the velocity–pressure formulation. The use of the incompressibility condition as a boundary condition and the application of the second Green's identity to transform the domain integral into a boundary integral result in a system of three boundary integral equations for velocity components and pressure. Solution of this system to be an ill‐posed problem because of the presence of boundary conditions of the first kind. Two methods of regularization are employed. The numerical results for trench oxidation process are presented.
Numerical modelling of the stationary Maxwell–Lorentz system in technical devices
Authors: Westermann Thomas 
Published: August 2005

AbstractThe particle‐in‐cell method is coupled with boundary‐fitted co‐ordinates in order to model the stationary Maxwell–Lorentz problem in technical devices. New numerical algorithms describing the transition between the grid model and the mesh‐free model are developed and the existing techniques of finite difference schemes for equidistant grids are extended to non‐equidistant, arbitrarily shaped, convex four‐point meshes. The modelling process is described, and both the numerical approximation and the algorithms are discussed. Applications in different technical devices show the flexibility of the method.
The parallel computation of solutions to electrostatic problems using multigrid techniques
Authors: Waring L. C. , Rooney N. , Stewart A. , Fusco V. F. 
Published: August 2005

AbstractThe application of multigrid techniques to the computation of the static solutions of electromagnetic field problems governed by Laplace's equation is described. This technique is compared with the conventional successive over‐relaxation (SOR) method for solving finite difference problems. In contrast to SOR, the number of iterations of multigrid needed to achieve convergence is largely independent of the grid size. It is shown that the relative performance of multigrid is excellent on large grids where the number of iterations of SOR needed to achieve convergence becomes prohibitively large. The technique is illustrated by applying a parallel implementation of multigrid to find a quasistatic solution of a boxed microstrip problem.
Solving eigenvalue and steady‐state problems using time‐domain models
Authors: Nitsche Gunnar 
Published: August 2005

AbstractA new approach to efficiently compute the low‐frequency eigenmodes of a time‐domain model approximating a linear physical system is proposed. The method is based on principles known from digital signal processing, in particular from parametic spectrum estimation, so it is not surprising that the achievable accuracy is much higher than the accuracy of the usual non‐parametric discrete Fourier transform approach. The algorithm works in the general lossy case even for a very large number of unknowns and can easily be extended to calculate steady‐state solutions under sinusoidal excitations for several different frequencies simultaneously.
Recent developments in numerical integration of differential equations
Authors: Mathis Wolfgang 
Published: August 2005

AbstractIn this paper we demonstrate the use of differential equations by means of an example from network analysis and show that differential/algebraic equations (DAE), rather than explicit ordinary differential equations (ODE), are more suitable for the description of electrical systems and networks. The main ideas of numerical integration of ODEs are presented. We consider this material from the point of view of replacing the ODE by a difference equation (DE). In particular, the relationship between the ODE and the associated DE is discussed. In the last Section the application of integration methods for OEDs upon DAEs and its difficulties are discussed. The paper is intended as a review; but a few new results are also included.
Transmission‐line equivalent curcuit model of minority carrier transient current in quasi‐neutral silicon layers including effects
Authors: Karamakković J. P. , Janković N. D. , Glozić D. B. 
Published: August 2005

AbstractA novel transmission‐line model for the minority carrier transport through quasi‐neutral arbitrarily doped layers is proposed. Based on detailed drift‐diffusion equations, the novel TLEC includes the inductance that represents the influence of the relaxation‐time term. Coupled with a object‐orientated hybrid circuit simulator, the novel transmission‐line model is implemented for the transient analysis of minority carrier transport. A substantial longer storage time of the minority carrier transient current at the collector end of ultra‐narrow base is predicted owing to inclusion of the relaxation‐time term.
Transmission‐line modelling of the class E amplifier with an analytical method
Authors: Yam Yu‐on , Cheung Chi‐wai , Li Chi‐hung 
Published: August 2005

AbstractThe Transmission line modelling (TLM) technique was used to simulate the class E power amplifier. An analytical method is also used to fix the required component values to ensure the desired output performance of the amplifier. An experiment was carried out to verify the simulation result of the combined method.
Three‐dimensional simulation for negative resistance characteristics of parasitic bipolar transistor in a small‐sized mosfet structure
Authors: Ju Chiping , Zemanian Armen H. 
Published: August 2005

AbstractThe behaviours of parasitic bipolar transistors are investigated by exploring the physical mechanisms of negative resistance characteristics generated in a small‐sized MOSFET structure. Physical experiments and three‐dimensional simulations verify the expected negative resistance characteristics. The effects of variations of device parameters such as injected substrate current levels, doping concentrations, channel widths, and physical device sizes are investigated by simulation. According to simulation results, the operation of a parasitic bipolar transistor is initiated by the injected substrate current; this explains the negative resistance characteristics occurring at low operating voltages.
Maslovian Lagrangian surfaces of constant curvature in complex projective or complex hyperbolic planes
Authors: Chen Bang‐Yen 
Published: August 2005

AbstractA Lagrangian submanifold is called Maslovian if its mean curvature vector H is nowhere zero and its Maslov vector field JH is a principal direction of AH . In this article we classify Maslovian Lagrangian surfaces of constant curvature in complex projective plane CP 2 as well as in complex hyperbolic plane CH 2. We prove that there exist 14 families of Maslovian Lagrangian surfaces of constant curvature in CP 2 and 41 families in CH 2. All of the Lagrangian surfaces of constant curvature obtained from these families admit a unit length Killing vector field whose integral curves are geodesics of the Lagrangian surfaces. Conversely, locally (in a neighborhood of each point belonging to an open dense subset) every Maslovian Lagrangian surface of constant curvature in CP 2 or in CH 2 is a surface obtained from these 55 families. As an immediate by‐product, we provide new methods to construct explicitly many new examples of Lagrangian surfaces of constant curvature in complex projective and complex hyperbolic planes which admit a unit length Killing vector field. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evolution operators generated by non‐densely defined operators
Authors: Oka Hirokazu , Tanaka Naoki 
Published: August 2005

AbstractIn this paper it is shown that an evolution operator is generated by a family of closed linear operators whose common domain is not necessarily dense in the underlying Banach space, under the stability condition proposed by the second author from the viewpoint of finite difference approximations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the geometric form of Bernoulli configurations
Authors: Acker Andrew 
Published: August 2005

AbstractIn References 4 and 5, the author studied the geometric form of the free boundary Γ of an annular domain Ω, characterized by the Bernoulli condition that |∇U|=1 on Γ, where U is the capacity potential in Ω. It was shown, for example, that Γ has at most as many ν‐extrema (for a given direction ν) or inflection points as the other boundary component Γ* of Ω, which is assumed given. Our purpose here is to extend the results in References 4 and 5 (wherever possible) to multiply connected regions for which some boundary components are given and others are free boundaries characterized by the Bernoulli condition. We present both positive results and counterexamples.
Non‐linear boundary value problems for the annular membrane: New results on existence of positive solutions
Authors: Grabmüller Hans , Novak Erich 
Published: August 2005

AbstractThe Föppl‐Hencky theory of small finite deflections has been applied to the study of axisymmetric deformations of annular membranes by various authors. The mathematical problem of uniqueness of tensile solutions for the corresponding non‐linear boundary value problems in the full range of physically meaningful boundary data was solved only recently.3, 4 In this paper, a new integral equation technique of solution is developed which yields the existence of tensile solutions for a parameter range of the boundary data where previous investigations on this matter had not been successful. It is shown that tensile solutions no longer exist, when sufficiently large positive radial displacements are prescribed at the inner edge of the annulus.
Radially symmetric solutions of the Poisson–Boltzmann equation
Authors: Krzywicki A. , Nadzieja T. , Meister E. 
Published: August 2005

AbstractThe electrostatic potential u outside of a charged cylinder contained in an infinitely large container of electrolyte satisfies the Poisson–Boltzmann equation Δu = shu and boundary condition ∂u/∂n = − σ on the cylinder and u(∞) = 0. We show that there exists a unique radially symmetric solution of the problem and consider its properties.