bluuebunny/crossref_metadata_2025 huggingface dataset:
D.C. ANALYSIS OF PIECEWISE LINEAR NETWORKS USING THE GAUSS‐SEIDEL METHOD
Authors: TADEUSIEWICZ Michal
Published: February 2008

Analysis of piecewise linear resistive networks, described by nodal equations, using the Gauss‐Seidel method is presented in the paper. The conditions which guarantee the existence of a unique solution and convergence of the iterative technique are formulated. An algorithm is described and a numerical example is demonstrated.
THE APPARENT NUMERICAL STABILITY OF UNPHYSICAL SHOCKS
Authors: SEVER Michael
Published: February 2008

Difference schemes for hyperbolic systems of conservation laws occasionally converge to an unphysical weak solution, i.e. a weak solution containing discontinuities for which the entropy condition is violated. These unphysical discontinuities, when they exist as solutions of the difference scheme, tend to exhibit a surprising stability under perturbations. We point out here that this can be explained by an energy inequality, which is valid for the discrete approximation but which is not valid as applied to the differential equation itself. In spite of this difficulty, many simple difference schemes are highly successful at converging to the physically correct weak solution. A mechanism for this is given; we show that for shocks of moderate strength, there are numerous quadratic forms in the dependent variables which can serve effectively as entropy functions, i.e. for which an inequality exists determining the physically correct weak solution. It is shown how the limits of the solutions of a difference scheme will often necessarily satisfy such an inequality; as they are generally weak solutions of the given system, they must thus be the correct weak solutions.
JUSTIFICATION OF THE AVERAGING METHOD FOR A CLASS OF NONLINEAR INTEGRO‐DIFFERENTIAL EQUATIONS WITH IMPULSES
Authors: MILUSHEVA S.D. , BAINOV D.D.
Published: February 2008

The paper justifies the averaging method for nonlinear integro‐differential equations of the type (x ∈ Rn, ε > 0 is a small parameter, ω is a constant), experiencing impulse effect.
NUMERICAL SIMULATION OF BIPOLAR INJECTION AND RECOMBINATION IN MNOS STRUCTURE
Authors: GADIYAK G.V. , OBRECHT M.S. , SINITSA S.P.
Published: February 2008

In this paper we consider the effects of recombination during polarization on passing a current through SiN4 and SiO2. In the literature, some works have been devoted to the problem of the passage of a current through MNOS‐structures. However, these studies related mainly to monopolar injection or bipolar injection but ignored recombination.
BIBO STABILITY OF A CLASS OF LINEAR TIME‐VARIABLE SEMI‐STATE SYSTEMS AND APPLICATION IN THE ANALYSIS OF RLC ELECTRICAL NETWORKS
Authors: BAJIĆ Vladimir B.
Published: February 2008

Sufficient conditions for bounded input‐bounded output (BIBO) stability are established for a class of time‐variable linear semi‐state systems. These conditions are expressed directly in terms of system parameters and reduce to testing of negative semi‐definiteness of a time‐varying matrix. Simple algebraic conditions convenient for the computer applications are derived for this purpose. It is shown how the results obtained can be applied in the analysis of linear time‐variable RLC electrical networks.
ANALYSIS OF A DISCRETIZATION ALGORITHM FOR TIME‐DEPENDENT SEMICONDUCTOR MODELS
Authors: SEVER Michael
Published: February 2008

A new algorithm is presented for the discretization of semiconductor models in one space dimension plus time. A complete error analysis is given, showing that the discretization errors do not depend on any derivatives of ill‐behaved quantities such as carrier densities. In this algorithm, the electrostatic potential is updated from a discretization of the equation of total current continuity, and parabolic equations for the current densities are discretized, rather than those for the carrier densities. Projection methods, e.g. simple finite‐element methods, are used for the space discretization. The equations for the current densities are similar to the familiar Scharfetter‐Gummel expressions in the stationary limit. However, the discrete time‐dependent current densities are required here to be H1 functions of x, obtained in a space with at least second order approximation property in L2. This method is fully compatible with recently developed methods for uncoupling the discrete systems to be solved at each time step, for an individual device or when a given problem involves multiple, coupled devices.
DEVELOPMENTS IN THE THEORY OF DISTRIBUTION SYSTEM RELIABILITY FOR DEVELOPING POWER SYSTEMS
Authors: EKWUE A.O.
Published: February 2008

Previously, a linear model was developed for investigating the optimisation of distribution system reliability for developing power systems. The economics of maintaining this reliability level was established based on cost‐benefit and probability techniques. In this paper, a theoretical formulation is described to evaluate the time frame required to achieve this reliability level employing a nonlinear model.
ELECTROMAGNETIC UNBALANCE OF UNTRANSPOSED AND TRANSPOSED TRANSMISSION LINES WITH “N” OVERHEAD GROUND WIRES
Authors: GÖNEN Turan , HAJ‐MOHAMADI Mohamad S.
Published: February 2008

This paper discusses the electromagnetic unbalances of transmission lines caused by mutual impedances. The unbalance factors of 27 different transmission line configurations have been studied by using a digital computer. The impacts of transposition, phase arrangement, additions of transformer, and capacitors to the lines in terms of circulating currents, sequence impedances, and net through and circulatory unbalance factors have been investigated extensively. Furthermore, the impact of “n” overhead ground wires on the electromagnetic unbalance factors of untransposed single‐ and double‐circuit transmission lines have been studied and the results have been tabulated and plotted.
A NONITERATIVE ALGORITHM FOR DECONVOLUTION‐INVERSE FILTERING USING THE CHEBYSHEV MINIMAX NORM FOR THE APPROXIMATION ERROR
Authors: DYKA Andrzej , UGOWSKI Henryk
Published: February 2008

The aim of this paper is to show that in the case of even input signals with sidelobes of equal amplitude and arbitrary sign the D‐algorithm introduced in the first part of this paper subtitled “Theory”, may give a solution which is equal to that with the Chebyshev minimax norm for the approximation error. It is proved that, with some restrictions, in the case of two, four, and six sidelobe even input signals, the algorithm discussed gives exactly the Chebyshev minimax solution—CMS. Also, properties of the algorithm in the case of more general input signal are discussed.
GLOBAL DELAY TIME FOR GENERAL DISTRIBUTED NETWORKS WITH APPLICATIONS TO TIMING ANALYSIS OF DIGITAL MOS INTEGRATED CIRCUITS
Authors: MARINOV C. , NEITTAANMÄKI P.
Published: February 2008

We consider here a general nerwork composed by n‐distributed parameters lines (with telegraph‐equations models) and m‐capacitors, all connected by a resistive multiport. An asymptotic stability property drives us to define and evaluate a global parameter (“λ‐delay time”) which describes the speed of signals propagation through the network. Because of its simplicity of calculation and its tightness, the given upper bound of the λ‐delay time is useful in timing analysis of MOS integrated chips.
COMPUTATION OF PERFORMANCE CHARACTERISTICS OF A TWO‐WAY IMPEDANCE‐TRANSFORMING WILKINSON DIVIDER
Authors: MGOMBELO H.R.
Published: February 2008

Performance characteristics of a two‐way impedance transforming Wilkinson divider are computed using design parameters obtained by imposing the conditions of perfect match at the input port and infinity isolation at the output ports at the center frequency of operation. It is found that, theoretically, infinity bandwidth of match at the input port and split is achieved for an impedance transformation of 2:1 and that similar input VSWR and insertion loss characteristics are achieved for two cases with transformation ratios (R2/R1) whose product is 4:1.
ANALYSIS OF OPTICAL WAVEGUIDES USING AN ANALOGY TO A MECHANICAL VIBRATION PROBLEM
Authors: BAUM E.
Published: February 2008

Many waveguide problems in integrated optics may mathematically be described by a scalar Helmholtz equation. In this paper it will be shown, that the same equation arises in the analysis of a mechanical vibration problem (elastically bedded membrane). One can utilize this analogy for calculating the propagation characteristics and field distribution of optical waveguides by one of the wide spread mechanics Finite‐Element codes, which are available on many computer systems, including personal computers in recent years. As an example this computation by analogy method is employed for the computation of the propagation characteristic of a symmetric film waveguide.
ROTATIONAL‐TRANSLATIONAL ADDITION THEOREMS FOR VECTOR SPHEROIDAL WAVE FUNCTIONS
Authors: COORAY M.F.R. , CIRIC I.R.
Published: February 2008

Rotational‐translational addition theorems for the vector spheroidal wave functions Ma(i)mn(h; ξ, η, φ) and Na(i)mn(h; ξ, η, φ), i = 1,2,3,4, are derived from those for the corresponding scalar spheroidal wave functions ψ(i)mn(h; ξ, η, φ). A vector spheroidal wave function defined in one spheroidal coordinate system (h; ξ, η, φ) is expressed in terms of a series of vector spheroidal wave functions defined in another spheroidal coordinate system (h′; ξ′, η′, φ′), which is rotated and translated with respect to the first one. These theorems allow a rigorous treatment of boundary value problems relative to time‐harmonic vector field waves in the presence of a system of spheroids with arbitrary orientations. As a special case, general rotational‐translational addition theorems for vector spherical wave functions are also presented.
A SENSITIVITY ANALYSIS OF THE STEADY STATE SEMICONDUCTOR DEVICE EQUATIONS
Authors: STEINRÜCK Herbert
Published: February 2008

When considering the one dimensional semiconductor device equations, the condition number turns out to be so large that a numeric solution of the equation is meaningless. Applying singular perturbation methods to the linearized model the solution can be separated into two parts: One, which is very sensitive to perturbations, and one, which is robust against perturbations of the equations.
REMARKS ON THE ASCENT ALGORITHM FOR THE LINEAR MINIMAX PROBLEM
Authors: UGOWSKI Henryk
Published: February 2008

In this note we correct the flow diagram of the ascent algorithm for the linear minimax problem which was shown by Cheney on p. 50.
CHEBYSHEV MINIMAX DECONVOLUTION FILTERING FOR A PAIR OF DISCRETE PULSES
Authors: DYKA Andrzej
Published: February 2008

This paper presents a closed form analytic solution for the impulse response of an optimum FIR deconvolution filter intended for a pair of discrete pulses of arbitrary amplitude and sign, subject to the minimisation of Chebyshev maximum norm for the approximation error. The tradeoff between the approximation error and the degradation of signal‐to‐noise ratio, is examined.
PARTICLE SIMULATION OF BIDIMENSIONAL ELECTRON TRANSPORT PARALLEL TO A HETEROJUNCTION INTERFACE
Authors: DEGOND P. , DELAURENS F. , MUSTIELES F.J. , NIER F.
Published: February 2008

This paper is devoted to the numerical study, using the deterministic particle method, of the parallel transport of a bidimensional electron gas confined in a potential well near a heterojunction interface. The geometry makes it possible to solve independently the transport under the electric field and the well shape. We simulate the electronic transport with a kinetic model and use the deterministic particle method. As for the description of the potential well, we use different models and compare their influence on the thermodynamic equilibrium and on the transport properties of the electron gas.
A COIL OVER A CRACK. (RESULTS FOR BENCHMARK PROBLEM 8 OF TEAM WORKSHOP)
Authors: VERITE J.C.
Published: February 2008

Problem 8 of the TEAM workshop comes from non‐destructive testing. A differential probe moves above a block with a crack. Three experimental and four numerical results are presented and analysed. Some specific difficulties arising in this problem are discussed.
SUMMARY OF RESULTS FOR HOLLOW CONDUCTING SPHERE IN UNIFORM TRANSIENTLY VARYING MAGNETIC FIELD (PROBLEM 11)
Authors: EMSON C.R.I.
Published: February 2008

Problem 11 of the TEAM workshops for eddy current code comparison is a hollow conducting sphere in a uniform magnetic field. The applied field varies with time as a step function, requiring a fully transient solution. A total of 13 sets of results are presented in this paper from various groups employing 12 different computer codes. The numerical results are compared with an analytic solution to the problem.
RESULTS FOR THE CANTILEVER BEAM MOVING IN CROSSED MAGNETIC FIELDS
Authors: TURNER L.R. , HUA T.Q.
Published: February 2008

Problem 12 of the TEAM (Testing Electromagnetic Analysis Methods) Workshops for Eddy Current Code Comparison is a cantilever beam in crossed steady and time‐varying magnetic fields. A total of six solutions to this coupled problem are described and compared with experimental results. Most solutions treated the electromagnetic aspects of the problem numerically, but the mechanical motion aspects analytically with a single degree of freedom. In general, the numerical predictions are in very good agreement with experiments.
HIGH‐RESOLUTION SPECTRUM ESTIMATOR ORTHOGONAL SUM DECOMPOSITION APPROACH
Authors: BZYL Wlodzimierz
Published: February 2008

We present a new approach to spectrum estimation leading to computationally efficient high‐resolution estimator. Our approach is based on the orthogonal sum decomposition, and this could be viewed as weighted periodograms averaging.
ON THE CONVOLUTION INVERSE OF DISCRETE SEQUENCES
Authors: UGOWSKI Henryk , DYKA Andrzej
Published: February 2008

In the first part of this paper subtitled ‘Theory and estimation of the truncation error’ we have examined the existence and unicity of the convolution inverse. In this part of the paper we discuss the application of convolution inverses for determining the solution to the Fredholm equation of the first kind. Particular attention is paid to the errors that arise from both the truncation of the infinite sequence that represents the inverse and the inaccuracy in input data.
A HYBRID FINITE ELEMENT — BOUNDARY ELEMENT METHOD (FEM‐BEM) FOR THERMAL ANALYSIS IN ENERGY INSTALLATIONS
Authors: PICHON L. , RAZEK A.
Published: February 2008

This paper presents a hybrid finite element — boundary element method for the steady state thermal analysis of energy installations. The coupling of the two techniques is presented: finite elements are used in a bounded region containing thermal sources while the complementary domain is treated with boundary elements. With such a combination the number of unknowns is reduced and an accurate prediction of temperature is obtained. As an example, the temperature rise is computed for the case of three power cables laid in a thermal backfill: the finite element method (FEM) is used for the cables and the backfill while the homogeneous soil is taken into account with the boundary element method (BEM).
MULTIOBJECTIVE PLANNING OF THE OPTIMAL VOLTAGE PROFILE IN ELECTRIC POWER DISTRIBUTION SYSTEMS
Authors: RAMIREZ‐ROSADO Ignacio J. , ADAMS R.N.
Published: February 2008

Multiobjective planning models for electric power distribution system planning can include multiple aspects such as community amenity values, geographical conditions of the study area, reliability evaluations (mainly in terms of service continuity), or the optimal voltage profile in the network, as well as the basic planning aspects: power demand requirements, power capacity limits and the minimization of the total system expansion costs. On the other hand, classical single objective planning models have usually considered only the basic aspects. This paper describes a multiobjective model to find the optimal voltage profile and to look for the least cost system expansion simultaneously. Furthermore, two multiobjective techniques for the application of the model to distribution system expansion problems are outlined. The computer results have shown that multiobjective models are able to find solutions which include multiple planning objectives simultaneously, and that these solutions are advantageous compared with the ones from classical single objective models.
NUMERICAL CALCULATIONS OF THERMAL FIELDS IN SUPERCONDUCTING A.C. MAGNET COILS
Authors: SLANINKA P. , POLJOVKA P.
Published: February 2008

This paper deals with a model for the numerical calculations of thermal fields in superconducting a.c. magnet coils. The solution is based on Poisson's partial differential equation solved by the finite difference technique with the Guass‐Seidel (Liebmann) iteration method. The model contains numerical solutions for the magnetic field and calculations of heat losses generated by the coil winding. The computer program is briefly described and some results of calculations are presented.
ELECTRICAL CHARACTERISTICS OF DUCT ELECTROSTATIC PRECIPITATORS AS INFLUENCED BY BUNDLED DISCHARGE ELECTRODES
Authors: ABDEL‐SATTAR S.
Published: February 2008

In this paper, the electrical parameters of the duct electrostatic precipitators with bundle wires, as discharge electrodes, are calculated and reported. Variation of mobility for both ions and particles in the space surrounding the energized subwires is taken into consideration. The method used is based on numerically solving the main set of equations, defining the ionized field surrounding the subwires of the bundle wire‐duct electrostatic precipitators (BWDEP) with the presence of dust particles. This method predicts the electrical performance in the BWDEP irrespective of the number of subwires per bundle. The corona onset voltage around the periphery of each subwire of the bundled discharge electrodes of the duct electrostatic precipitators is determined. It changes from point to point at the subwire surface. The effects of different numbers of subwires per bundled electrode, as well as the subwires arrangement, on the electrical performance of the BWDEP are also reported and discussed in this paper. The present findings are correlated to the physics of the electrical corona discharge.
SUMMARY OF RESULTS FOR BENCHMARK PROBLEM 10 (STEEL PLATES AROUND A COIL)
Authors: NAKATA Takayoshi , TAKAHASHI Norio , FUJIWARA Koji
Published: February 2008

Benchmark problem 10 of the TEAM workshop consists of steel plates around a coil (non‐linear transient eddy current problem). Seven computer codes are applied, and seven solutions are compared with each other and with experimental results.
SUMMARY OF RESULTS FOR THE TEAM WORKSHOP PROBLEM 14
Authors: BIRO O. , NIIKURA S.
Published: February 2008

This paper presents a summary of results for the TEAM workshop problem 14. Thirteen results are given and seven computer codes applied.
THE EFFECT OF A SCREENING OXIDE ON ION IMPLANTATION STUDIED BY MONTE CARLO SIMULATIONS
Authors: Hobler G. , Pötzl H.
Published: February 2008

The effect of a screening oxide layer on 1‐D and 2‐D ion implantation profiles in silicon is investigated using Monte Carlo simulations. Experimental observations of profile broadening by oxide layers are explained by the fact that atoms at lattice positions are less effective in steering ions into channels than atoms at random positions. The influence of the oxide layer on the lateral penetration below a mask is discussed in terms of implantation energy and ion species. A new set of parameters for the electronic stopping of phosphorus and arsenic in silicon is used.
IMPLEMENTATION OF A HYDRODYNAMIC TRANSIENT MODEL FOR SIMULATING HIGH SPEED PHOTODETECTORS
Authors: Li Z.‐M. , Chai K.‐W. , McAlister S.P. , Simmons J.
Published: February 2008

We have implemented a two‐dimensional (2D) time‐dependent hydrodynamic model suitable for studying III‐V heterostructural semiconductor devices. This we apply in simulating a heterojunction metal‐semiconductor‐metal (MSM) photodetector subject to pico‐second optical pulses. The inclusion of the energy balance equation introduces an additional time delay in the response of the detector, which is comparable to the energy relaxation time.
SIMULATION OF INTERFACE COUPLING EFFECTS IN ULTRA—THIN SILICON ON INSULATOR MOSFET's
Authors: Hassein—Bey A. , Cristoloveanu S.
Published: February 2008

Recent progress in silicon—on—insulator (SOI) technologies has made possible the fabrication of high quality ultra—thin film structures. Preliminary research has demonstrated the advantage of fully—depleted SOI MOSFET's in term of speed and improved resistance to hot carrier degradation. The specific dual‐gate configuration of SOI transistors is schematically presented in Fig. 1(a).
Coupled device‐circuit simulation using energy‐momentum device models
Authors: SEVER MICHAEL
Published: February 2008

The use of energy‐momentum models for carrier transport is considered in the context of coupled device‐circuit simulation. We point out that certain computational methods for uncoupling the computations, successfully employed using drift‐diffusion models, can be slightly modified and made compatible with energy‐momentum models, assuming only a known or computable “momentum relaxation time”. By such means one can readily compare the results of transient simulations using energy‐momentum and drift‐diffusion models.
TIME AND FREQUENCY DOMAIN NUMERICAL PHYSICAL MODELLING OF TWO TERMINAL MICROWAVE NON LINEAR CIRCUITS APPLIED TO MILLIMETER‐WAVE AVALANCHE DIODE FREQUENCY MULTIPLIERS
Authors: DALLE C. , FRISCOURT M.R. , ROLLAND P.A.
Published: February 2008

Time and frequency domain complementary numerical models of microwave non‐linear circuits using two‐terminal active semiconductor devices are presented. Their main feature is the use of numerical one‐dimensional macroscopic physical models as semiconductor device models. Their respective capability is illustrated by some results of a study devoted to the optimization of millimeter‐wave avalanche diode frequency multipliers.
Fast models for statistical process/device simulation
Authors: Pfitzner Andrzej , Grygolec Miroslaw
Published: February 2008

A new method for statistical process/device modeling has been developed and applied to determine the impurty profiles and the current‐voltage characteristics of the p‐n junction. This method combines accurate numerical solutions of the transport equations with internally calibrated fast analytical (semi‐empirical) models.
EXISTENCE CONDITIONS FOR CONVOLUTION INVERSES OF REAL FINITE SEQUENCES
Authors: UGOWSKI H.
Published: February 2008

Novel necessary and sufficient existence conditions for convolution inverses of real finite sequences are derived. These conditions are obtained with the aid of well known conditions expressed in terms of the Fourier and z‐transforms. The conditions given in the paper imply suitable algorithms, which are convenient for checking the existence of convolution inverses of any real finite sequences.
A TWO‐DIMENSIONAL ZHU—ZIENKIEWICZ METHOD FOR GRADIENT RECOVERY FROM FINITE‐ELEMENT SOLUTIONS
Authors: SILVESTER P.P. , OMERAGIĆ D.
Published: February 2008

The gradient recovery method proposed by Zhu and Zienkiewicz for one‐dimensional problems is generalized to two dimensions, using quadrilateral elements. Its performance is compared with that of conventional local smoothing techniques and of direct differentiation of the finite‐element solution, on finite‐element approximations to analytically known polynomial and transcendental functions on a quadrilateral second‐order finite‐element mesh. The new method appears to be reliable and more stable than local smoothing, and to provide better accuracy than direct differentiation, at low computational cost.
NON‐STANDARD FINITE ELEMENTS IN PROBLEMS WITH ROTATIONAL SYMMETRY
Authors: SROKA J. , KORYTKOWSKI J. , STARZYŃSKI J.
Published: February 2008

An extension of the coupling of the generalized multipole technique, adapted to the infinite domain, with the standard finite elements in the examined area, to problems with rotational symmetry is presented. The multipole expansion in the infinite domain is the superposition of three‐dimensional multipoles distributed uniformly at several circles. The circles build multipole rings. The theoretical basis for building the multipole rings and for taking symmetry into account are given. The method is verified by calculating electrostatic and magnetostatic problems for which analytical solutions exist. Verification encompasses potential distribution as well as calculation of equivalent lumped parameters, i.e. capacitance and inductance.
ANALYTICAL MODELLING OF EDDY CURRENTS INDUCED BY A TIME‐VARYING MAGNETIC FIELD IN A CONDUCTIVE PLATE
Authors: SIAKAVELLAS N.J.
Published: February 2008

A simple model is proposed for the analytical calculation of the eddy current induced by a time‐varying magnetic field in a conductive plate. It is assumed that the current is uniformly distributed over the plate thickness and circulates in rectangular paths. The plate is considered as an equivalent LR circuit and its equivalent inductance and resistance are calculated analytically and expressed as a function of the plate dimensions. The analytical solution of the equation, governing the LR circuit, yields the total current circulating in the plate as a function of time. The model is applied to a well known benchmark problem and the results are in good agreement with those obtained by experiment.
DIRECT DETERMINATION OF TWO‐PERIODIC SOLUTIONS FOR NONLINEAR DYNAMIC SYSTEMS
Authors: SOBCZYK T.
Published: February 2008

This paper presents a Newton‐Raphson algorithm for determining the Fourier spectrum of two‐periodic solutions for dynamic systems described by nonlinear ordinary differential equations. Assuming that two basic frequencies are known, the coefficients of a double Fourier series result from this algorithm. An application to the analysis of electromagnetic phenomena in electromechanical converters is described. In an example, of the steady‐state performances of current in a simple converter, the algorithm is tested with very good results.
SIMULATION OF n+−n−n+ DEVICES BY A HYDRODYNAMIC MODEL: SUBSONIC AND SUPERSONIC FLOWS
Authors: ANILE A.M. , MACCORA C. , PIDATELLA R.M.
Published: February 2008

The effects of viscosity, previously neglected in electronic device stimulations, are studied using a non‐standard hydrodynamic model, following Anile and Pennisi. Results are compared with those of Gardner.
THE NEAR FIELD TO FAR FIELD TRANSFORMATION
Authors: MONK P.
Published: February 2008

If a scattering problem is solved by finite element, finite volume or finite difference methods, it is necessary to predict the far field pattern (or radar cross‐section) by using a near field to far field transformation. Usually this is done using the Stratton‐Chu integral relations, which give the far field pattern in terms of a near field surface integral. When volume‐based methods are used this is unnatural, and it may be necessary to employ interpolation procedures to provide the necessary surface data. In this paper an alternative method based on volume integrals is proposed. The main advantage of the new procedure is that it allows the use of discrete quantities that are naturally available from the numerical scheme. However, it is now necessary to perform volume integrals. The error in the new procedure is examined, and a simple numerical example provided.
SUMMARY OF RESULTS FOR PROBLEM 20 (3‐D STATIC FORCE PROBLEM)
Authors: TAKAHASHI N. , NAKATA T. , MORISHIGE H.
Published: February 2008

Thirteen computer codes developed by eleven groups are applied to the benchmark problem 20 (3‐D static force problem) for the TEAM Workshop. The solutions are compared with each other and with experimental results.
SUMMARY OF THE RESULTS FOR MAGNETIC DAMPING IN TORSIONAL MODE (TEAM PROBLEM 16)
Authors: TAKAGI TOSHIYUKI
Published: February 2008

This paper describes the results for magnetic damping in torsional mode (TEAM problem 16). A total of six solutions are presented and compared with experimental results. The problem is treated as a coupled electromagnetomechanical one. In general numerical predictions agree well with experiment.
NUMERICAL COMPUTATION OF ELECTRONIC PROPERTIES OF SEMICONDUCTOR HETEROSTRUCTURES FOR QUANTUM DEVICE APPLICATIONS
Authors: LAZZOUNI M.E. , SHAM L.J.
Published: February 2008

We present a numerical self‐consistent method to solve for the electronic properties within a flexible and accurate theoretical model of selectively‐doped semiconductor heterostructures based on a two‐band k.P effective‐mass‐approximation Hamiltonian that includes non‐parabolicity, stress, piezo‐electric, finite temperature, many‐body, and DX center effects. The method can handle any planar configuration of heterostructures. Self‐consistency is achieved quickly via Broyden's method.
AN ANALYSIS OF THE HYDRODYNAMIC SEMICONDUCTOR DEVICE MODEL — BOUNDARY CONDITIONS AND SIMULATIONS
Authors: ALURU N.R. , LAW K.H. , PINSKY P.M. , DUTTON R.W.
Published: February 2008

A mathematical analysis of the time‐dependent multi‐dimensional Hydrodynamic model is performed to determine the well‐posed boundary conditions for semiconductor device simulation. The number of independent boundary conditions that need to be specified at electrical contacts of a semi‐conductor device are derived. Using the classical energy method, a mathematical relation among the physical parameters is established to define the well‐posed boundary conditions for the problem. Several possible sets of boundary conditions are given to illustrate the proper boundary conditions. Natural boundary conditions that can be specified are obtained from the boundary integrals of the weak‐form finite element formulations. An example is included to illustrate the importance of well‐posedness of the boundary conditions for device simulation.
ANALYTICAL MODELS OF MAGNETIC SATURATION AND HYSTERESIS IN A NONLINEAR INDUCTANCE FOR APPLICATION IN SIMULATION STUDIES
Authors: LIPOWSKI JANUSZ S.
Published: February 2008

This paper presents new general mathematical models of normalized hysteresis curves, which define major‐hysteresis‐loop and minor‐hysteresis‐loop trajectories with several degrees of freedom. These mathematical models may be integrated into models of circuits containing nonlinear inductances for application in simulation studies. Also, the models presented can be applied to the description of hysteresis of different physical nature in other areas of science where the hysteresis phenomenon is encountered, for example: dielectric hysteresis, mechanical hysteresis, adsorption hysteresis, optical hysteresis, and so forth.
A NEW MODEL FOR THE DETERMINATION OF POINT DEFECT EQUILIBRIUM CONCENTRATIONS IN SILICON
Authors: BUDIL M. , GUERRERO E. , BRABEC T. , SELBERHERR S. , POETZL H.
Published: February 2008

In this paper the boundary conditions for point defect distributions in monocrystalline silicon are investigated. These boundary conditions are established by simple thermodynamic considerations. A circle process is used including vacancy, interstitial and Frenkel pair generation which yields a simple relationship between the vacancy and interstitial equilibrium concentrations at the surface. A new OED model is also presented which explains the t−1/4 behaviour of the interstitial supersaturation. This model is used to simulate experiments of Mizuo and Higuchi. In this way values for the equilibrium concentrations and the diffusion coefficients of vacancies and interstitials are obtained.
SELF‐CONSISTENT I‐V CHARACTERISTICS OF ULTRA‐SMALL DEVICES
Authors: CAHAY M. , McLENNAN M. , DATTA S. , LUNDSTROM M.S.
Published: February 2008

A method is presented for the incorporation of space‐charge effects into the analysis of one‐dimensional devices. At each bias, solutions of Schrödinger's and Poisson's equations are performed iteratively, until the solutions converge. Some difficulties in the calculation of electron density are noted, and an algorithm is described to insure an accurate computation. Finally, the current‐voltage characteristic of a recently fabricated resonant tunneling device is presented, to stress the importance of space‐charge effects.
DYNAMICS OF ELECTRON TRANSFER BETWEEN TWO ADJACENT CHANNELS AS CALCULATED BY AN ENSEMBLE MONTE CARLO METHOD
Authors: KIZILYALLI I.C. , HESS K. , IAFRATE G.J. , SMITH D.
Published: February 2008

The dynamical characteristics of electron transfer between two channels are elucidated by using a many‐particle Monte Carlo model with self‐consistent electric fields. The study has been performed to assess switching speeds associated with various novel devices such as velocity modulation transistors and dual channel high electron mobility transistors. Typical time constants for a one micrometer device (0.4 µm gate length) are 3.5 psec for the longitudinal (source‐to‐drain) and 0.2 psec for the transport perpendicular to the interfaces between the two channels.
THE MOMENTS OF THE BOLTZMANN TRANSPORT EQUATION AS APPLIED TO THE GALLIUM ARSENIDE PERMEABLE BASE TRANSISTOR
Authors: KRESKOVSKY J.P. , MEYYAPPAN M. , GRUBIN H.L.
Published: February 2008

Solutions to the first three moments of the Boltzmann transport equation and Poisson's equation are obtained for a permeable base transistor (PBT) using linearized, block implicit (LBI) and ADI techniques. Two level electron transfer is considered. The results of the simulations are compared to results obtained from the drift and diffusion equations. The comparison indicates that nonequilibrium transport and velocity overshoot are important in the PBT. The predicted I‐V characteristics of the device show substantially higher current levels and a higher cutoff frequency are obtained with the moment equations.
SOLUTION OF ION‐ACOUSTIC WAVE PROPAGATION IN PLASMA—THE ONE DIMENSIONAL CASE
Authors: LU Junwei , KAGAWA Yukio
Published: February 2008

Ion‐acoustic wave propagation in plasma is discussed. Analytical and numerical solutions are given for one‐dimensional plane waves. The similarity of the ion‐acoustic waves to the waves associated with an electrical transmission line is pointed out and the solved examples are compared with experimental observations.
AN EFFICIENT SEMI‐ANALYTICAL INTEGRATION PROCEDURE IN THREE DIMENSIONAL BOUNDARY INTEGRAL METHOD
Authors: REN Z. , BOUILLAULT F. , RAZEK A. , VERITE J.C.
Published: February 2008

A semi‐analytical integration technique to evaluate the singular integration in 3‐D boundary element method for electromagnetic field computation is reported. The technique has been applied in a hybrid finite element—boundary integral model to evaluate the singular integral terms when constructing the “outside stiffness matrix” in the case of small air‐gaps, and it has also been used to calculate the exterior magnetic field in the proximity of the boundaries. The comparison with the conventional Gaussian quadrature has been carried out by modelling a 3‐D magnetostatic problem with a small air‐gap.
BOOK REVIEW
Authors: Axelsson O.
Published: February 2008

The classical finite difference method suffers from some disadvantages, namely (i) rigidity of the networks, (ii) natural boundary conditions are explicitly approximated by difference quotients, (iii) there can occur a loss of symmetry after discretizing selfadjoint problems, (iv) classical solutions, which do not exist near singular points, are required for the error analysis.
SEMI‐DEFINITENESS OF FUNCTIONAL MATRICES AND APPLICATION IN THE ANALYSIS OF SINGULAR RC CIRCUITS
Authors: BAJIĆ Vladimir B.
Published: February 2008

A simple algebraic test applied to a specially constructed constant matrix is developed to test the semi‐definiteness property of symmetric functional matrices. The simplicity of the algebraic test makes it very suitable for computer implementation. The results are applied in the analysis of a class of nonlinear time‐varying singular RC networks. Robustness of the boundedness property of network response with respect to resistive elements is shown.
STEADY‐STATE HEAT TRANSFER PERFORMANCE IN A HIGH VOLTAGE POWER CABLE
Authors: PINTO Jose A.D. , COIMBRA Paulo B. , ANTUNES Carlos F.L.
Published: February 2008

Empirical rules and experimental evidence are not capable of dealing with both geometric complexity and nonlinearities to design a sufficient accurate, reliable and affordable electrical device. To minimize this gap and to achieve an high performance level in the industry design of an electromagnetic device two CAD packages (electromagnetic CAD package and thermal CAD package) working in parallel processing should be used. In this paper these two packages have been used separately. The finite element technique is used to solve the heat conduction problem in complex devices of arbitrary shape with imposed boundary conditions. As an application example, the steady‐state temperature distribution will be produced for an high voltage cross‐linked polyethylene insulated power cable. The results are discussed and the importance of such a study as an aid to improve the life expectancy of high voltage power cables is pointed out. Finally, several conclusions are suggested to increase the power cable current transmission capacity.
MODELLING AND ANALYSIS OF THE ELECTRIC FIELD FOR A CANONICAL PROBLEM IN EDM
Authors: GAN H. , LEVIN P.L. , BROWN C.A.
Published: February 2008

We present two models of the electric field for a canonical problem in electric discharge machining. In particular, an analytical solution based on optimal parameter estimation is discussed, followed by a comparison with numerical solutions based on finite elements and Galerkin boundary elements. The problem is interesting because the structure of the field near the sharp asperity is a critical parameter in realistic models of the electric discharge machining process.
COMPARISON OF DIRECT DIFFERENTIATION AND ADJOINT VARIABLE METHOD FOR ELECTRICAL IMPEDANCE IMAGING
Authors: HAHN S.‐Y. , PARK I.‐H. , JUNG H.‐K. , SIKORA J.
Published: February 2008

In the shadow of X‐ray tomography and nuclear magnetic resonance tomography a new tomographic technique based on low‐frequency electric currents has been successfully developed in the past decade. Impedance computed tomography (ICT), although it gives poor spatial resolution images, is unmatched in certain cases. Two different approaches to the sensitivity analysis are presented in this paper. The direct differentiation method has been applied, but the adjoint variable method has not been used in ICT reconstruction algorithms until now. Some problems associated with the adjoint variable method of sensitivity analysis are discussed. The new algorithm is compared with the direct differentiation approach.
FAIR TRADING
Authors: Jones David
Published: February 2008

Retailers may be forgiven if they have filed away the Government's Fair Trading Bill for future reference, and got on with the business of boosting turnover this Christmas.
A ROGUE RETAILER
Authors: Moir Christine
Published: February 2008

A retailing company in Cornwall, which was established seven years ago with a working capital of £2,000, now brings in a pre‐tax profit of 16% on a turnover of £3½m. At the same time it advertises on its goods ‘an all round discount on average retail prices of something above 30%’. If one adds that two out of its three branches are operated withoutplanning permission and despite enforcement notices; that its staff is self‐employed (a situation which was instigated at the same time as SET was introduced) and that the owner takes independence to the length of generating his own electricity, one begins to understand that this is a rogue organisation.
PLANNING FOR RETAILING IN LONDON & PARIS
Authors: Moor Nigel
Published: February 2008

Two metropolitan cities of similar size and less than 400 Kilometres apart, yet London and Paris display vastly contrasting patterns of retailing. Retailing, unlike manufacturing industry, has yet to go truly multi‐national in its organisation; but the trends in this direction are clear. Retail organisations in England and France, however, will have to contend with very different patterns of retailing in the two metropolitan cities should they decide to set up in them. The reasons for these differences are partly historical and partly administrative. Since 1945 the outward growth of London has been limited by an extremely powerful system of land‐use planning. This has had the effect of stopping London at the point that its outward growth had reached prior to the outbreak of World War II. By 1938, aided by the development of suburban electric railways in the two decades since 1918, the suburbs of London had sprawled out 19 to 24 Km from the centre. In that year, an Act of Parliament created the Green Belt, which provided a means of restraining further development. The area within the Green Belt is now the province of the Greater London Council, the strategic planning authority for London set up in 1964. Beyond the Green Belt, in the Outer Metropolitan Area, some 40 to 50 Km from Central London, a series of new towns has been built. While Greater London has lost population and jobs since the war, this area beyond the Green Belt has witnessed a major growth of population and jobs in the same period. (Milton Keynes, for instance, is planned to accommodate 500,000 people and by 1977 a covered shopping centre of 84,000 m2 will be open, rising to 172,000 m2 of shopping space by 1991 with 28,000 car parking spaces).
THE NAME OF THE GAME IS FRANCHISING
Authors: Davey Ray
Published: February 2008

The catering industry forms the subject of our first market analysis report. It is an industry which has been much criticised for its indifferent marketing and its inefficient use of labour. Ray Davey argues here that only franchising will help the independent caterer to survive.
ENTER THE ELECTRONIC CASH REGISTER
Authors: Towsey Ralph
Published: February 2008

The electronic cash register has arrived on the scene, and is starting to take over operations formerly performed mechanically. By treating it as an integral part of an information reporting system, it can collect detailed data about the sales it records, thus providing a speedy and accurate stock control system. This article describes various experiments being carried out in this area.
DO‐IT‐YOURSELF: A rapidly expanding market
Authors: Cox Roger
Published: February 2008

Changes in social conditions and the enterprise of manufacturers in developing new lines in paints and wallpapers are factors which have led to the rapid expansion of the DIY market. In addition the distribution pattern has recently evolved into a somewhat complex one — it includes discount stores, voluntary group shops, and supermarkets. Some of these DIY retail outlets are discussed in this market analysis report.
CTNs˜a voluntary group solution?
Authors: Davey Ray
Published: February 2008

The failure of independents in non‐food sectors to adapt themselves to the voluntary group structure has been one of the features of the recent retail scene. But now there are signs of interesting activity in the confectionery/tobacco/news field. Independent CTNs are subject to pressures from both ends of the spectrum — not only from supermarkets but from the well‐organised CTN multiples; some of them are responding to these pressures by adopting improved selling methods and by forming a voluntary group.
DESIGN CONSULTANCY
Authors: Topalian Alan
Published: February 2008

The idea of the design consultant as somebody who comes into the board room and makes bright suggestions about the colour of the vehicles and the typeface on the stationery is more than a little outdated — if indeed it was ever valid. Today's design consultant must have a knowledge of his client's business in order to be able to advise on design as an integral part of marketing policy.
LANDAIR'S HI‐FI DEPARTMENT STORE
Authors: Linden Bennie
Published: February 2008

An unusual and ambitious retail development recently opened in London's Tottenham Court Road. Described as Britain's first department store devoted to hi‐fi, audio and video equipment, Lindair House plans to take advantage of anticipated dramatic growth in the audio industry. This new development is discussed here by our financial correspondent.
TALKING SHOP
Authors: Wright Donald
Published: February 2008

This is the first of a new occasional feature which will offer comment on topical aspects of the distributive scene. The pseudonym adopted by the author cloaks the anonymity of an executive concerned with the planning function in a major national retail organisation. This month Donald Wright discusses statistics, consumerism, and food multiples.
VISIBLE RECORD COMPUTERS
Authors: Smythe Clare
Published: February 2008

The complexity and the wide range of electronic data processing machines on the market is bewildering; at the one end are the relatively simple machines such as invoicing calculators, at the other the complex and powerful computer systems. For many organisations neither of these is the answer. Visible Record Computers however, occuping an intermediate position, are flexible, fully supported with software and systems, and relatively inexpensive. How VRCs function and how they may be applied to the distributive trades form the subject of this feature.
Measurement and problems of low pay in retail distribution
Authors: Robinson Olive , Wallace John
Published: February 2008

In the third article of this series dealing with aspects of wage payments and employment in retail distribution the authors look at the problems of low pay in this sector. Despite increases this remains well below average, in 1972, for example, only the median weekly earnings of kitchen‐hands, hairdressers and barmaids were lower than that of saleswomen. This research has been funded by the Social Science Research Council.
Overcoming the enemy of inflation The gathering strength of discounting
Authors: Wright Donald
Published: February 2008

Trying to be responsible It's early days yet, with Phase 2 of the Prices and Incomes Policy being (as I write) hardly three months old. Already, however, several colleagues have advanced the view that the effects of Phase 2 are beginning to be felt.
THE CITY'S VIEW OF THE GROCERY TRADE
Authors: Clarke Peter W.
Published: February 2008

In this paper taken from the proceedings of the recent Institute of Grocery Distribution annual convention, Peter Clarke gives his view on the performance of grocery manufacturers and distributors, particularly the larger retailers. He notes that other types of organization are again presenting competition to the multiples, notably the department stores, whose performance he examines in some detail.
EQUAL PAY IN RETAILING
Authors: Robinson Olive , Wallace John
Published: February 2008

In the final article of their series dealing with the aspects of wage payments and employment in retail distribution, the authors examine the implications of the 1970 Equal Pay Act on retail distribution and, in particular, how the Government's counter‐inflation policy has affected the situation. They warn that when the full terms of the Act are implemented retail employers may find an unanticipated burden added to their wage bills. This research has been funded by the Social Science Research Council.
THE BOOTS/FRASER MERGER
Authors: Jones David
Published: February 2008

The proposed merger between two massive retailing groups, Boots and the House of Fraser, has been referred to the Monopolies Commission. The Commission's decision will be important not only for the City but for retailers in general. They will want to know whether approval would mean other attempts to form new groupings; and of course they will also be somewhat apprehensive as to whether or not a new retail group with sales of £600m is likely to emerge. But the case also throws light on the way in which the Government is now conducting its competition policy.
The Decline and Fall of the Smaller Retail Outlet
Authors: Kirby David A.
Published: February 2008

That the total number of retail outlets in the UK is declining is not news. But what sort of retailers are disappearing? And in which parts of the country? David Kirby indicates that, surprisingly, not only the number of independents has declined, but also the number of multiple outlets, though naturally this is offset by a concentration of trade in larger multiple stores. The greatest contraction occurred amongst co‐operative shops.