bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing Managers for the Board
Authors: Mumford Alan
Published: February 2008

The article examines the results of a major survey of the processes of developing effective managers. The questionnaire‐based analysis was conducted by the International Management Centre from Buckingham and involved 144 directors. Individual directors were asked to describe the processes which had influenced their development, and the information attained was compared with organisational objectives.
Global Managers for Global Corporations
Authors: Sanders Patricia
Published: February 2008

The context in which business is conducted worldwide is changing radically and is creating new types of global business enterprises, as well as management attitudes and practices. Consequently, a new style of management has emerged using “geopolitical” concepts as a theoretical foundation for its formulation.
Management Education: Some Troublesome Realities and Possible Remedies
Authors: Schein Edgar H.
Published: February 2008

Developing effective managers requires a reappraisal of the development process — for the educators, as well as the students. It is necessary to make the curricula as exciting and attractive, as well as basically useful, as possible. The method of teaching, as well as the content, must also be stimulating. The use of workshops and seminars is advocated.
Achieving Instructional Excellence: Advice from Some Management Educators
Authors: Heisler W.J.
Published: February 2008

How do successful management educators prepare for, organise, conduct and evaluate their teaching? A dialogue between four management faculty members is presented.
Internationalising the Executive Education Curriculum at General Electric: A Case Study of Trends in the 1980s
Authors: Hayeś H. Michael
Published: February 2008

Some background on General Electric and its executive education operation in the US is provided. The review process and its major findings are described, followed by some of the major recommendations and action taken. Finally, a retrospective evaluation is offered.
Management Development: Competencies, Teams, Learning Contracts and Work Experience Based Learning
Authors: Prideaux S. , Ford James E.
Published: February 2008

In this second of two articles describing a two‐year part‐time management development programme conducted at the Royal Melbourne Institute of Technology, an account of the impact of the programme on the development of the participants as managers is offered from their viewpoint, and the implications for management development offered by the course are assessed.
Management Development in Africa: The Canada‐Kenya Executive Management Programme Experience
Authors: Lane Henry W. , Burgoyne David G.
Published: February 2008

Since 1983, the School of Business Administration, the University of Western Ontario, has been offering an annual two‐week management development programme in Kenya. The programme is described — how it began, why it was done, details of the classes and course contents. The problem of management transferrability is discussed, followed by what has been learned from the experience.
University‐based Executive Education: Impacts and Implications
Authors: Vicere Albert A.
Published: February 2008

University‐based executive education programmes have played a major role in the development of upper‐level managers since the beginning of the Second World War. A summary review of research into their effectiveness is presented, and a challenge issued for further investigation as to their worthiness.
Increasing the Effectiveness of Management Development via the Managerial Problems Survey
Authors: Posner Barry Z. , Kouzes James M. , Roger Manley T.
Published: February 2008

The key design considerations for putting together effective management development activities are briefly reviewed. The Managerial Problems Survey, one mechanism for operationalising these design considerations, is described, followed by a case study of how one organisation used these ideas. Several suggestions are then presented for how organisations and their managers can increase the relevance and benefits of management development efforts.
Developing Entrepreneurs in Developing Countries — The PEG Programme in Peru
Authors: Matilde Schwalb Maria , Grosse Robert , Romero Simpson Eulogio
Published: February 2008

An innovative effort by a Peruvian university suggests that entrepreneurship can be stimulated by a mix of training and hands‐on work in creating new businesses. The recent efforts of the Universidad del Pacifico to deal with problems faced by managers in that country are described.
Strategic Apex Leader Scripts and an Organisational Life Cycle Approach to Leadership and Excellence
Authors: Hunt J.G. , Baliga B.R. , Peterson M.F.
Published: February 2008

This article examines top level management leadership and its impact on organisational excellence. An organisational life cycle model of leadership is developed which posits that top level leadership requirements differ across different stages of an organisation's life cycle. Such requirements are expanded to include not only those with subordinates but those with external stakeholders. We argue that top managers operate from leadership scripts and utilise judgemental heuristics which tend to drive their leader behaviour and make it difficult to change in order to meet the differing life cycle requirements. A number of strategies that can be used to change these scripts and judgemental heuristics as required are discussed.
Trends in Management Development: The Need for Some Hard Based Rules
Authors: Margerison Charles
Published: February 2008

Management development is seen in many organisations as an added luxury. In this article, management development is discussed as a long‐term process which requires a tough business‐like approach. Drawing on observations made over a number of years of working with various organisations, “ten commandments” for effective management development are suggested.
CHARGE TRANSFER IN THE PRESENCE OF POTENTIAL BARRIERS
Authors: Banghart Edmund K. , Lavine James P. , Pimbley Joseph M. , Burkey Bruce C.
Published: February 2008

Numerical and analytical solutions of the carrier continuity equation are found for the problem of charge transfer in charge‐coupled devices in the presence of potential barriers. The analytical solution is for a rectangular potential barrier and is useful for obtaining a qualitative understanding of charge transfer over a potential barrier. Numerical results show that the charge transfer inefficiency is strongly affected when the shape of the potential barrier is varied and the height of the potential barrier remains fixed.
A TRANSPORT MODEL FOR CARRIERS IN SMALL SPATIAL/TEMPORAL SCALE COMPOUND SEMICONDUCTOR DEVICES
Authors: Cheng Ming‐Cheng , Kunhardt E.E.
Published: February 2008

A non‐equilibrium multi‐valley transport model for carriers in compound semiconductor devices has been developed. This macroscopic transport model provides an efficient scheme for device modeling, and can overcome the difficulty in evaluating the relaxation times in multi‐valley conservation equations without a priori assumption of the displaced‐Maxwellian distribution. This model has been successfully applied to electron transport in GaAs subjected to rapidly time‐varying fields. The results have suggested that the macroscopic effective mass of electrons might be strongly dependent on average velocity.
A COMPARISON BETWEEN THE HETEROJUNCTION BIPOLAR TRANSISTOR POWER PERFORMANCE COMPUTED USING LARGE SIGNAL “Y” PARAMETERS AND A FULL TIME DOMAIN SIMULATION
Authors: Teeter Douglas A. , East Jack R. , Mains Richard K. , Haddad George I.
Published: February 2008

This model is intended to simulate the large signal performance of heterojunction bipolar transistors for use in high power, high frequency, oscillators, amplifiers, and mixers. A temperature model which includes velocity overshoot and carrier energy effects has been developed. The model is used to calculate the large signal “Y” parameters of an HBT. A comparison is made between predicted power performance using the “Y” parameters and a fully numerical, time domain computation. Advantages and disadvantages of each approach are given.
2D PROCESS SIMULATION OF DOPANT DIFFUSION IN POLYSILICON
Authors: Jones SK , Gérodolle A
Published: February 2008

A new model to describe dopant diffusion and recrystallisation in polycrystalline silicon during thermal treatment is presented. The full 3D microstructure of the material is considered and a local homogenisation approximation introduced. A parallel diffusion model for diffusion in grain boundaries and grain interior with grain growth and segregation is developed within this approximation. The model is solved in a 2D vertical section using a finite element discretisation. An example of the application of this model to a one micron bipolar transistor is given.
ADVANCED NUMERICAL TECHNIQUES IN SEMICONDUCTOR DEVICE SIMULATION
Authors: Schilders W.H.A.
Published: February 2008

In the past decade, very effective techniques for the solution of the drift‐diffusion equations have been developed. This has enabled the simulation of a large variety of semiconductor devices in a robust and efficient way. However, the rapid development and miniaturization of devices necessitate the use of extended physical models in order to still provide an accurate description of device performance. In order to guarantee a similar degree of robustness and efficiency for these extended models, new algorithms have to be developed. In this paper we will present a number of advanced numerical techniques which have been developed for this purpose.
A NOTE ON CURRENT DISCRETIZATION IN THE HYDROMODEL
Authors: Souissi Kamel , Odeh F. , Gnudi Antonio
Published: February 2008

We propose a modified discretization for the current continuity equation in the hydromodel for semiconductors. It combines ease of implementation within existing codes and robustness, even for extremely short devices. Some computational results for one and two dimensional structures are given.
ITERATION APPROACH FOR SOLVING THE INHOMOGENEOUS BOLTZMANN EQUATION
Authors: VITANOV P. , NEDJALKOV M.
Published: February 2008

The iteration approach consists of applying Numerical Monte Carlo methods for calculation of linear functional of iterated functions to an integral form of the Boltz‐mann Equation. It has been successfully used for the time‐dependent homogeneous case. The same approach, we present in this paper, can be applied for the inhomo‐geneous case, important from practical point of view. Application of the iteration approach in the particular case of obtaining the Ensemble Monte Carlo algorithm is shown.
A NUMERICAL STUDY OF THE DEPENDENCE OF UNITY GAIN BANDWIDTH fT ON POLYSILICON EMITTER IN BIPOLAR TRANSISTORS
Authors: CHOR E.F. , TAN L.S.
Published: February 2008

The effects of polysilicon emitter on the high frequency performance of bipolar transistors have been investigated numerically. The presence of polysilicon grain boundaries was found to slow down the response of the device. This resulted in a lower fT for polysilicon emitter bipolar transistors with a clean polysilicon/ mono‐crystalline silicon interface compared to conventional transistors with an identical emitter‐base junction depth. The interfacial oxide layer that could exist at the polysilicon/mono‐crystalline silicon interface can, depending on the relative thickness of the polysilicon and mono‐crystalline silicon emitter regions, either improve or deteriorate the high frequency performance of the device. For a mono‐crystalline silicon emitter region that is much thinner than the polysilicon emitter region, the lower the tunnelling probability of the interfacial oxide layer the better is the improvement in fT. However, if the thickness of the mono‐crystalline silicon emitter region is made larger with respect to the polysilicon emitter region, the converse can be true.
GaAs CCD CHARGE TRANSFER SIMULATION
Authors: Poore Richard E. , Kosel Peter B.
Published: February 2008

A computer program for the solution of the single carrier semiconductor equations in GaAs has been developed to simulate charge storage and transfer in GaAs charge‐coupled devices. An uncoupled Newton method is used to solve the steady state problem, and a stable, uncoupled method is used for the transient solution. Using transient simulation, the transfer of a charge packet from well to well can be simulated over time. By comparing the size of the charge packet before and after the transfer, information on the charge transfer inefficency can be derived.
COMPUTER OPTIMIZING OF ELECTROMAGNETIC DEVICES
Authors: Trowbridge CW
Published: February 2008

The optimization of geometric boundaries and placement of conductors to achieve specific design goals is the principle activity in computational electromagnetics. However the heuristic determination of design variables soon leads to total confusion as the user attempts to wrestle with multiple choices. Even if there are just two states for n parameters there will be, 2n trials. The range of problems posed is vast. One such is the determination of magnet geometries needed to produce an unpolluted uniform field in Magnet Resonance Imaging (MRI) systems, and another application concerns the design of pole shapes in particle accelerators where the higher harmonic distortions must be minimized in dipoles and multipole magnets.
COMPLEMENTARITY IN NONLINEAR MAGNETOSTATICS: BILATERAL BOUNDS ON THE FLUX‐CURRENT CHARACTERISTIC
Authors: Bossavit A.
Published: February 2008

The relation between the flux F in a magnetic circuit and the driving current J, or characteristic of the circuit, is described by a curve in the principal quadrant of the J—F plane. We wish to determine this curve, for a given non‐linear b—h law. Standard numerical analysis only allows one to plot some points of the J—F curve, with an error which depends on the grade of the finite‐element mesh, and on which only asymptotic estimates are known. We show that one can do much better: one can “sandwich” the characteristic, i.e., define a narrow strip in the J—F plane within which the characteristic surely lies.
ON THE USE OF THE IMPEDANCE BOUNDARY CONDITION WITH A ONE‐COMPONENT MAGNETIC FIELD FORMULATION
Authors: Gramz Modest , Ziólkowski Marek
Published: February 2008

The impedance boundary condition is widely used in order to reduce a multiple region electromagnetic field problem to a magnetic field problem analyzed in a nonconducting region only. It is obvious that the solution to the latter problem is much easier to obtain than those for conducting regions. There are several versions of the impedance boundary condition formulation which depend mainly on the choice of a field state variable and the solution technique applied.
INDIRECT INTEGRAL‐BOUNDARY MODEL OF 3‐D MAGNETIC FIELD
Authors: Pawluk K.
Published: February 2008

In the paper the boundary‐integral model of the stationary magnetic field in a 3‐D linear region is presented. The region is bounded from inside or from outside by metallic materials of different permeability. Current sources of the field are represented by the filaments coinciding with axes of the conductors, and the magnetic field is described in terms of a scalar magnetic potential. Surface densities of the magnetic charge in monopole and dipole form are used as the variables in the boundary‐integral equations. The calculation of magnetic field distribution in the end region of an electrical machine may be effectively performed with the use of the proposed approach. Some results of computation of boundary quantities are presented.
3‐D CALCULATION OF MAGNETIC AND ELECTRIC FIELDS BY FDM USING FAST SOLVING SUBROUTINES
Authors: Zakrzewski K. , Lukaniszyn M.
Published: February 2008

The calculation of quasistationary magnetic fields and electrostatic fields of several objects is presented in the paper. In the range of the magnetic fields of coils and transformer systems parallelepiped calculation regions are assumed. In the range of electrostatic fields analysis of the field in tanks of different shape storing inflammable liquids was undertaken. Fast subroutines using finite differences [FDM] to calculate the field were employed. These subroutines are based on the Fast Fourier Transform (FFT).
DEVELOPMENTS IN TRANSMISSION LINE MODELLING AND ITS APPLICATION IN ELECTROMAGNETIC FIELD SIMULATION
Authors: Scaramuzza R.A. , Christopoulos C.
Published: February 2008

Transmission line modelling is a technique that can be applied to the analysis and design of electromagnetic devices. Developments to the method are described which improve its efficiency and flexibility.
CALCULATION OF ADDITIONAL SLOT LEAKAGE PERMEANCE IN ELECTRICAL MACHINES DUE TO RADIAL VENTILATION DUCTS
Authors: Demenko A. , Oberretl K.
Published: February 2008

The 3D magnetic field in the region with ventilation duct of electrical machine has been analyzed. The method of reduced scalar magnetic potential in connection with the FE method has been used to solve the problem. On the basis of field distribution, the slot leakage permeance has been calculated. The problem has also been solved analytically. It has been assumed that the radial component of magnetic field density in ventilation ducts is equal to zero. The comparison of results leads to the conclusion that, in practice, the analytical calculations are satisfactory accurate.
CURRENT SHEETS EQUIVALENT TC END WINDING CURRENTS OF INDUCTION MOTOR ROTOR AND DETERMINATION OF THE MAGNETIC FIELD IN THE END ZONE. Part I Flux densities due to stator end winding
Authors: Tegopoulos J.A. , Yannopoulos‐Lascaratos P.P.
Published: February 2008

The purpose of this paper is to replace the end winding current distribution of the squirrel cage rotor of induction motors with appropriate current sheets of sinusoidal distribution and then determine analytically the flux density at any point on the end zone due to stator end winding currents (Fig.1).
THE PRACTICAL APPLICATION OF FEM TECHNIQUES IN TRANSFORMER DESIGN & DEVELOPMENT
Authors: Darley V
Published: February 2008

Power 4 Distribution Transformers are complex assemblies of metallic and insulating materials which generate equally complex electrostatic and electromagnetic fields.
3D FINITE ELEMENT MODELLING OF ELECTROMAGNETS AND TRANSFORMERS BY USING A PARTICULAR SCALAR POTENTIAL TECHNIQUE
Authors: Kladas A.G. , Tegopoulos J.A.
Published: February 2008

The design of several electromagnetic devices, such as magnets and transformers, leads to a 3D magnetostatic field analysis. Although such problems can be solved by using vector potential formulations, scalar potential techniques seem to be more efficient because of the reduced number of unknowns they introduce. Even these methods, however, present certain drawbacks, depending on the way the scalar potential is defined: considerable cancellation errors in iron parts, difficulties to simulate multiply connected iron cores, a complicated way to compute a source field distribution.
TRANSFORMER WINDING LEAKAGE FIELD EFFECTS AND THEIR CALCULATION
Authors: Thompson David , Wang Qunjing
Published: February 2008

This contribution describes for one particular 45/90 MVA transformer design the results of finite element calculations of its leakage field and winding forces. The results show that the forces on the end turns and the leakage flux vary significantly with position. On the basis of these results the computation is extended to consider the calculation of the a.c. losses and their distribution. The calculated and measured values are 437 kW and 407 kW.
SIMULATION OF THE INDUCTION HEATER SUPPLIED FROM THYRISTOR INVERTER
Authors: Skoczkowski T.
Published: February 2008

The classical methods of designing induction heaters, usually supplied from the network or machine medium frequency generators, require the following assumption to be made: the voltage at the terminals of the coil is sinusoidal; the frequency of the voltage, the power surface density or the density of the heating flux, the material properties of the charge are constant and the electromagnetic and the temperature fields are considered to be uncoupled.
SOLUTION OF MAGNETIC HEAD FIELD PROBLEMS USING THE BEM
Authors: Jahnke H.‐G. , Schmidt G. , Strese H.
Published: February 2008

At ISEF'89 we spoke about our work concerning two dimensional (2D) modelling of magnetic heads. Starting with the magnetostatic transmission problem for a magnetic domain with finite permeability ? we derived an integral formulation for the scalar potential which was treated using the Boundary Element Method (BEM). By discretising the boundary only, one can get the potential and the magnetic field in each point of the plane. Further calculations yield the efficiency and the response of the head. These investigations resulted in our system BEA86 which can be used on a PC interactively for designing integrated magnetic heads. Next step was to realise the method described above in the 3D case. But of course this was not possible on a PC. Even on a Micro VAX it took more than one hour to solve a head problem including field and efficiency calculation with our system BOASPM. So our idea was to simulate the 3D‐behaviour of a magnetic head in a more simple way (see Fig. 1 to compare the three models).
FEM AIDED OPTIMIZATION OF PERMANENT MAGNET DIMENSIONS IN A DC MOTOR WITH HYBRID EXCITATION
Authors: Zoodzinski Tamasz
Published: February 2008

In the paper the optimization procedure of a direct current motor with a hybrid excitation has been presented. The excitation system consists of a shunt field winding disposed around field pole and permanent magnet, both acting in parallel. The field distribution in motor for various magnet and field pole dimensions has been determined using finite element method. The flux linkage with the armature winding has been computed. Demagnetizing effect of armature current was taken into account. The optimal permanent magnet and the field pole dimensions, ensuring minimum total cost of purchase and work during assumed period of time were calculated. Motor characteristics e.g. rated torque, rated current, speed regulation limit were used as constraints. In worked up algorithm and computer program Carroll internal penalty function method was used. Some basic suggestions tor design of optimal hybrid excited dc motors with parallel permanent magnet and electromagnetic excitation are given.
THE ESTIMATION OF METROLOGICAL CHARACTERISTICS OF INSTRUMENT TRASFORMERS IN RATED AND OVERCURRENT CONDITIONS BASED ON THE ANALYSIS OF ELECTROMAGNETIC FIELD
Authors: Leśniewska Elźbieta
Published: February 2008

Problems of correct estimation of metrological characteristics of current transformers based on constructional data and working conditions are of great importance. Applying the commonly known equivalent circuit of the current transformer requires its parameters to be determined correctly. A method for determining the equivalent circuit parameters of a current transformer, based on its field models, is shown in this paper. The results obtained using field computation and real‐life model tests are compared.
INTERNAL BEHAVIOUR OF LARGE COILS SUBJECT TO TRANSIENT VOLTAGE
Authors: Campostrini P.P. , Chitarin G. , Stella A. , Zollino G.
Published: February 2008

This paper deals with the problem of internal overvoltages within large coils due to fast‐rising surges. Numerical simulations are performed on a lumped‐parameter equivalent circuit, representing a coil of the magnetic system of a thermo‐nuclear fusion experiment. Inductances and capacitances are computed through numerical methods which ensure a good precision even with complex geometries. The effect of the conductive painting on the outer surface of the coil is also taken into account. The simulation results are compared with a number of measurements on a full‐size prototype coil. Turn‐to‐earth, as well as inter‐turn overvoltages, are both computed and measured in many grounding conditions. The experimental results fit well with computation and theoretical prediction.
ELECTRIC STRESS DISTRIBUTION IN POLYMERIC INSULATION CONTAINING DEFECT SITES AND SPACE CHARGE
Authors: Davies AE , Chen G
Published: February 2008

Polymeric insulation is progressively replacing traditional materials in cables, switchgear and machines. The fundamental electricl properties of polymer dielectrics such as conduction and breakdown are strongly influenced by the presence of defect centres (voids and inclusions) and trapped charge. A thorough understanding of the role of trapped charge in the breakdown process is essential if the full potential of these new materials is to be realised.
ADAPTIVE ALGORITHMS IN EDDY‐CURRENT NONDESTRUCTIVE TESTING
Authors: Gawrylczyk K.M.
Published: February 2008

Low frequency eddy current technique is being widely used for the nondestructive testing of metal objects. Computer simulation for eddy current nondestructive testing of metal objects is described in this paper.
A‐POSTERIORI ADAPTIVE MESH REFINEMENT IN THE FINITE ELEMENT EDDY CURRENT COMPUTATION
Authors: Golias N.A. , Tsiboukis T.D.
Published: February 2008

Two a‐posteriori error estimators are presented for adaptive mesh generation in eddy current finite element computation : the discontinuity of the magnetic flux density on the interface between neighboring elements and the energy perturbation between 1st and 2nd order finite element meshes. Validation of the results is being accomplished by application of the adaptive refinement in the case of a T‐shaped slot embedded conductor, a problem several times approached in the literature.
A COMPARISON OF ENERGY BALANCE AND SIMPLIFIED HYDRODYNAMIC MODELS FOR GaAs SIMULATION
Authors: Apanovich Y. , Lyumkis E. , Polsky B. , Shur A. , Blakey P.
Published: February 2008

The use of energy balance and simplified hydrodynamic models for simulating GaAs devices is investigated. The simplified hydrodynamic model predicts velocity spikes that are not present in more detailed Monte Carlo simulation results. These velocity spikes are associated with overestimation of thermal diffusion. The simplified hydrodynamic model can predict terminal currents that are significantly lower than those predicted by the energy balance model. The differences between the models are significantly greater than those observed previously for silicon devices. The main conclusion of this study is that the energy balance model is preferable to the simplified hydrodynamic model as the basis for GaAs device simulation, but the energy balance model still needs refinement to improve the agreement with more general simulation and experimental results.
A STUDY OF THE INFLUENCE OF HYDRODYNAMIC MODEL EFFECTS ON CHARACTERISTICS OF SILICON BIPOLAR TRANSISTORS
Authors: Sadovnikov A.D. , Roulston D.J.
Published: February 2008

With decreasing vertical dimensions of the bipolar transistor (BJT), non‐local effects of nonuniform electron temperature should have a significant effect on the BJT characteristics. These effects can be simulated using a hydrodynamic (HD) model of the BJT, in which the equation of energy balance is added to the set of Poisson's and continuity equations.
USING GREEN'S FUNCTIONS TO IMPROVE CONJUGATE GRADIENT CONVERGENCE FOR THE SEMI‐CONDUCTOR EQUATIONS
Authors: Chandler Stephen
Published: February 2008

The aim of this paper is to present two independent ways in which a simple approximation to a Green's function for a differential equation can be used to improve the performance of well‐known iterative methods for linear equations.
SPEEDING‐UP OF CONVERGENCE OF GUMMEL ITERATIONS FOR TRANSIENT SIMULATION
Authors: OBRECHT M.S. , ELMASRY M.I.
Published: February 2008

Enhanced efficiency of the proposed modification of the Gummel decoupled method enables significant reduction of memory requirements in comparison to the conventionally used Newton‐like methods with approximately equal CPU time expense. For 10,000 mesh nodes it only requires 4.4 Mbytes of virtual memory (compare to 62 Mbytes for PISCES‐2B). The method exhibits good stability and convergence rate and has significant advantages compared to the other often used half‐implicit scheme. Low memory requirements and efficiency make the method attractive for future 3‐D applications.
A COMPOUND EMITTER HETEROJUNCTION BIPOLAR TRANSISTOR
Authors: Chor E.F. , Peng C.J.
Published: February 2008

A compound emitter heterojunction bipolar transistor (HBT) structure that incorporates an additional heterojunction within the emitter for minority carrier confinement has been proposed. In this new device configuration, the single wide band‐gap emitter layer in a conventional HBT is replaced by two sub‐layers of wide band‐gap material, with the sub‐layer nearer the base having a narrower band‐gap. By means of numerical simulations, the compound emitter HBT was found to perform better than comparable conventional HBTs. With the AlGaAs(n) / GaAs heterostructure system, the optimum compound emitter HBT structure was found to be Al0.3Ga0.7As(n) ‐ Al0. 2Ga0.8As(n) / GaAs with grading at the two hetero‐interfaces. It has a low turn‐on voltage that is almost identical to that of a homojunction GaAs bipolar transistor with similar doping conditions. Compared with a conventional single emitter layer Al0.3Ga0.7As/GaAs HBT, the optimum compound emitter HBT has an enhancement in the current gain by approximately 2 folds, an improvement in the uniform current gain region from 2 to 4 decades of collector current density, and a slight increase in the unity‐gain cut‐off frequency fT by about 7 %.
METHOD FOR ORDERING INTEGRATED CIRCUIT EQUATIONS IN SPECTRAL ANALYSIS OF THEIR TRANSIENT BEHAVIOR
Authors: Palusinski O.A. , Abdennadher M.
Published: February 2008

The transient simulation of integrated circuit has become very expensive in terms of computer time due to increase in the number of transistors in typical simulation. Spectral technique and Chebyshev polynomials offers an efficient alternative algorithm for simulation of integrated circuits. In this paper an automatic formulation of circuit elements and transistor models, built in MOS technology, for analysis using spectral technique is presented. The algorithm is implemented and the simulation is proven to require less computer time than in the case of SPICE or ASTAP
THE DEVELOPMENT OF THE RADIATION ENHANCED DIFFUSION MODEL OF BORON IN SILICON
Authors: Gadiyak G.V. , Blaghinin D.E.
Published: February 2008

The radiation enhanced diffusion of implanted boron was modeled by considering the kinetic reaction between point defects, dislocations and boron atoms. The diffusion model utilizes Monte‐Carlo generated point defect profile, generated dislocation profile for high doze hydrogen implantation. Excellent simulation results has been achieved by using a single set of diffusion and kinetic parameters to model the radiation enhanced diffusion of boron for a wide range of hydrogen implanted doses.
A THEORETICAL STUDY OF SURFACE KINETIC PROCESSES IN THE MBE GROWTH OF GaAs (100)
Authors: Venkatasubramanian R. , Bendi Shridhar
Published: February 2008

Interfacial roughness in heterostructures critically degrade the optical and electrical properties of the devices fabricated with III‐V semiconductor compounds. Experimental work on the surface roughening processes during MBE growth by monitoring the reflection high energy electron diffraction (RHEED) intensity concluded that the surface roughening is a result of competition between surface roughening processes such as adsorption and evaporation and the surface smoothening process such as surface migration to stable sites. In this work, the stochastic model of MBE growth is employed to study the surface roughening kinetics in GaAs (100). The growth condition was chosen similar to that of experiments: temperature range of study: 773 – 873°K; cation to anion flux ratio in the range: 1 : 10 to 1 : 20. Diatomic arsenic molecular specie is employed for the study was As2. The time averaged RHEED intensity was obtained from the growth data and with the experimental results. The agreement between the results was excellent. A transition temperature at which the time averaged RHEED intensity is a maximum was observed for flux ratios 1 : 10 and 1 : 20. The RHEED intensity increases with temperature till the transition temperature due to surface smoothening resulting from the surface migration of Ga and As to energetically favorable sites. The RHEED intensity decreases beyond the transition temperature due to the evaporation of As from the surface. The transition temperature is observed to be a function of the flux ratio and can be explained by the difference in time for the formation of energetically stable surface adatom clusters resulting from the difference in the effective surface migration rates for various flux ratios.
NON‐EQUILIBRIUM MULTI‐VALLEY ELECTRON DISTRIBUTION FUNCTIONS IN GaAs
Authors: Cheng Ming‐C. , Chennupati Rambabu
Published: February 2008

The concept of the evolution of the distribution function is used to derive an energy‐scale distribution that is able to describe transport phenomena, including inter‐valley transfer effect, in the scale as small as the energy relaxation time. The energy‐scale distribution is used to study the evolution of electrons in n‐type GaAs under the influence of rapid change in field. Results indicate that, near the peak of strong velocity overshoot or the bottom of pronounced undershoot in the Γ valley caused by the rapid change in field, the energy‐scale distribution can not respond as fast as the distribution function calculated from the Monte Carlo method. The average velocity resulting from the energy‐scale distribution therefore leads to less pronounced overshoot and undershoot than those obtained from the Monte Carlo method. However, since velocity overshoot and undershoot are not pronounced in the L‐valleys, the L‐valley energy‐scale distribution is in excellent agreement with that determined by the Monte carlo simulation.
BOUNDSTATES OF TWO‐ELECTRON SYSTEMS IN QUANTUM CONFINED GEOMETRIES
Authors: Singh T. , Engle C. , Cahay M.
Published: February 2008

With the advent of sophisticated growth techniques such as Molecular Beam Epitaxy and Metal Organic Chemical Vapor Deposition, the calculation of the energy boundstates and electron wave‐functions of the one‐electron Schrödinger equation has received a lot of attention over the last decade. With the more recent fabrication of quantum wires and dots, it seems now imperative to extend the boundstates calculation to systems containing only a few electrons. Hereafter, we investigate the effect of electron exchange and Coulomb interactions on the boundstates of a two‐electron system in a square quantum well. The technique is based on a general Alternating Direction Implicit algorithm ( T. Singh and M. Cahay, SPIE Vol. 1675, Quantum Wells and Superlattice Physics IV (1992), p.11) combined with a Fourier spectrum analysis of the two‐particle wavefunction correlation , <ψ(χ1,χ2;0)/ψ(χ1,χ2;τ)> , where χ1, χ2 are the coordinates of the two electrons. The precise location of the energy eigenvalues requires the appropriate use of window functions before calculating the Fourier transform of the correlation function. We also compare our results for the boundstate energies with those obtained using a first order time‐independent perturbation theory.
DYNA — A HYDRODYNAMIC SIMULATOR FOR TWO‐VALLEY SEMICONDUCTOR DEVICES
Authors: Zhang Yaxi , El Nokali M.
Published: February 2008

A hydrodynamic semiconductor device simulator, DYNA, is introduced. A new relaxation time evaluation scheme for two‐valley semiconductors is proposed to account for the dependence of the electron mobility on the impurity scattering. Some robust solution methods are used in the simulator for treating the highly nonlinear system of equations. The simulation results for a nonuniformly‐doped GaAs MESFET are also shown.
VOLTAGE CONTROLLED JOSEPHSON JUNCTION ARRAYS
Authors: Qian G. , Cahay M. , Mast D.B. , Lee H.C.
Published: February 2008

Various experimental groups have reported observation of both integer and fractional giant Shapiro steps in the I‐V curves of N×M arrays of superconducting‐normal metal‐superconducting (SNS) Josephson junctions. The size of these steps have been investigated both experimentally and theoretically as a function of temperature, external magnetic field, and rf current. In this report, we investigate the possibility of controlling the size of these giant Shapiro steps by an external gate voltage by considering arrays of superconductor‐semiconductor‐superconductor junctions. We show that giant Shapiro steps of different orders can be quenched over different gate voltage ranges in these arrays.
SIMULATION OF FIELD EMISSION FROM SILICON: SELF‐CONSISTENT CORRECTIONS USING THE WIGNER DISTRIBUTION FUNCTION
Authors: Jensen K.L. , Ganguly A.K.
Published: February 2008

In this work we outline the methodology by which the Wigner Distribution Function (WDF) may be applied to the simulation of field emission from silicon into the vacuum so that the effects of self‐consistently calculated band bending and scattering on the current‐field characteristics may be assessed. For the first time, current saturation‐like effects are simulated. We analyze this in light of the behavior of the self‐consistent potential and density profiles at high applied fields.
EVANESCENT MODES AND SCATTERING EFFECTS ON RESONANT TUNNELING IN ZERO DIMENSIONAL NANOSTRUCTURES: A SCATTERING MATRIX APPROACH
Authors: Lee Chomsik , Weichold Mark H.
Published: February 2008

Theoretical calculations of tunneling characteristics of the Gated Resonant Tunneling Diode (GRTD) aie obtained in low dimensionality using a scattering transfer matrix approach. In the bias conditions whereby the GRTD reaches zero‐dimension in the well region, we consider attractive and repulsive perturbation potential (Vsc) of impurity or defect scattering in emitter and well regions. We describe the scattering matrices using the presence of evanescent, or nonpropagating, modes in different lateral confinement structure. Numerical solutions to the two‐dimensional Poisson equation and the continuity equation are used to calculate the lateral depletion region and carrier concentrations by the finite difference method. Electron transport in double‐barrier structure is calculated by a self‐consistent approach.
THE INFLUENCE OF LATTICE HEATING ON SEMICONDUCTOR DEVICE CHARACTERISTICS
Authors: Apanovich Y. , Cottle R. , Freydin B. , Lyumkis E. , Polsky B. , Tchernaiev A. , Blakey P.
Published: February 2008

Self‐consistent electrothermal simulation of modern semiconductor devices is required for the accurate and efficient design and optimization of many semiconductor devices. The need to perform this type analysis in order to predict the behavior of power devices was realized many years ago. It is now clear that nonisothermal analysis can be very important for VLSI devices as well.
EDDY CURRENT IMAGING — A THEORETICAL APPROACH
Authors: Gramz M.
Published: February 2008

Eddy current imaging is a relatively new technique of electromagnetic nondestructive testing that makes possible an accurate geometrical characterization of flaws. On contrary to the traditional approach to eddy current testing, spatially correlated information, that can be extracted from two‐dimensional eddy current images, is used to infer about flaw shape and dimensions. In general the problem of flaw reconstruction from the eddy current images belongs to the class of three‐dimensional nonlinear inverse problems. These problems can not be solved without properly chosen simplifications. In recent literature most of the authors tried to take advantage from the problem linearization. They used the eddy current image of a small diameter hole as a point spread function (two‐dimensional impulse response) and applied the classical linear filtering to deblur the image. Although this approach results in the restoration of the top view of the flaw it seems to be inadequate for full flaw reconstruction.
EDDY CURRENTS MODELING BY USING ANALYTIC ELEMENTS
Authors: Kladas A.G. , Tegopoulos J.A.
Published: February 2008

Some problems involve eddy currents developed in thin skin effect depths and a numerical analysis, based on the classical finite element method, is extremely laborious and expensive. Although such situations lead to operations concerning the linear part of the material characteristics, the related geometries are not, usually, simple enough to permit an analytical solution. The present work is based on a new type of element enabling efficient modeling in such cases. It combines the increased accuracy and speed of analytical solutions for large subdomains, a reduced number of unknowns and the advantages of functional minimization procedures.
CONTRIBUTION TO THE ELECTROMAGNETIC FIELD ANALYSIS IN A THIN CONDUCTING PLATE
Authors: Apanasewicz Stanislaw , Kaźmierski Marceli , Kersz Igor
Published: February 2008

In the paper, basing on the electromagnetic field analysis in a system with a thin conducting plate, infinitely extended, a set of equations approximately representing the boundary conditions on the plate is presented as well as the scope of their validity is estimated. Developing the idea announced in the eddy current problem is examined in a system with a thin plate having finite surface dimensions and with an external source of any configuration. The problem has been reduced to the Fredholm's equation of the second kind which, for regular‐shaped plates, can be solved in an explicite form Results of calculations are verified by experiment.
MAGNETIC FIELD COMPUTATIONS IN THE INTERIOR AND EXTERIOR REGIONS BY USING INFINITE ELEMENTS
Authors: Gratkowski Stanislaw , Ziółkowski Marek
Published: February 2008

This paper describes numerical tests for a three dimensional infinite element suitable for finite element modelling of open boundary field problems. The infinite element has four nodes and is compatible with conventional cuboids. The effectiveness of the infinite element in the interior — finite element region is shown by comparing the accuracy and the CPU time when various boundary conditions are applied. The possibility of computing the external fields is also illustrated.
THE INTEGRATION OF FUNCTIONS WITH SINGULARITIES IN BOUNDARY ELEMENT METHOD FOR POISSON'S EQUATION
Authors: Yu Ming , Kuffel E.
Published: February 2008

In boundary element method, we almost always have to integrate functions with singularities. The treatment of singularity is not particularly difficult for a line integration. Therefore we will focus on area integrations.
A NEW APPROACH TO NUMERICAL FIELD AND POTENTIAL CALCULATIONS
Authors: Nussbaum Allen
Published: February 2008

A. Conformal Transformation Methods A standard analytic method for the determination of field and potential distributions uses the Schwarz‐Christoffel (SC) conformal transformation integral. When applied to configurations such as the capacitor with fringing accounted for or a metal stripe separated by a dielectric from a ground plane, it leads to complicated expressions containing elliptic integrals, and when applied to a metal disc separated from a ground plane, Hankel transforms are also involved. Since elliptic integrals must be evaluated numerically in practice, it is desirable to replace these complicated analytic processes with one that is numerical from the start. Such a method has been published by Foster, Anderson, and Warner. It is based on the standardization of a two‐step conformal transform; Step 1 takes the original geometry and lays it out along the real axis and Step 2 converts this arrangement—using a reverse Schwarz‐Christoffel transform—into a rectangular structure from which the field lines and equipotentials can be determined by inspection. Step 1 is different for each problem but Step 2 is common to all problems, and represents one of several advantages of this procedure. The simplest example given by the originators is the tri‐plate strip line of Figure 1, which—by symmetry—can be reduced to the quadrant of Figure 2. The SC
NUMERICAL CALCULATION OF THE ELECTROMAGNETIC FIELD IN STRATIFIED MEDIA OF PLANAR OR CYLINDRICAL GEOMETRY
Authors: Antonopoulos C.S. , Kriezis E.E.
Published: February 2008

A boundary element technique is applied to an integral formulation of the electromagnetic field quantities, of the electric vector and magnetic scalar potentials for the evaluation of the propagation phenomenon in stratified media, of planar or cylindrical geometry, due to electric dipole sources. The use of the above described potentials simplify the solution procedure, because of the degrees of freedom, which can de introduced in choosing relations between the field quantities. The main goal of these relations is to make the numerical solution easier, while the Maxwell equations and the boundary conditions remain unaffected. Besides a three‐dimensional problem is treated as a two dimensional one. Results and plots of the field, are given for both cases of the geometry. The method can be used for determining the field inside the earth in geological studies, propagation in stratified media, cable technology, shielding problems e.t.c.
SOLUTION OF TEAM WORKSHOP PROBLEM 7 BY RELUCTANCE NETWORK METHOD (ASYMMETRICAL CONDUCTOR WITH A HOLE)
Authors: Wiak S. , Pelikant A. , Turowski J.
Published: February 2008

This paper presents the numerical solution of the TEAM Workshop Problem 7 obtained by Reluctance Network Method (RNM). The problem represents a three‐dimensional multiply connected eddy current problem with a time — harmonic excitation. The numerical results obtained by RNM in reasonable computing time, agree extremely well with experimental data and other methods results.
NUMERICAL METHODS FOR CALCULATING THE MECHANICAL BEHAVIOR OF ELECTROMAGNETIC DEVICES
Authors: Kahnert Andreas
Published: February 2008

A method for calculating the displacement of a moving armature and additional masses in an electromagnetic device is presented. The transient magnetic field is calculated numerically, considering the velocity and the nonlinearity of iron. The resulting force drives a mechanical system described by the equation of motion, which is solved by a Runge‐Kutta‐algorithm If more than one part of the device is moving, the conservation of momentum is taken into account to determine the movement. Four methods to shorten the calculation time and keep or improve the accuracy in determination of displacement and velocity are investigated. One of these methods leads, in spite of a shortened calculation time, to better results.
ELECTROMAGNETIC FIELD CALCULATION OF A LEAKAGE TRANSFORMER BY MEANS OF FINITE ELEMENT METHOD WITH HERMITIAN ELEMENTS
Authors: Komeza K. , Wiak S.
Published: February 2008

This paper deals with the field and leakage reactance calculations in the model leakage transformer. The approximate solution for 3‐D problem, made by composing 2‐D solutions for 3‐D solution, is applied. Hermitian hierarchical finite elements have been successfully applied to the field and reactance computation of the transformer. The computational results have been reported and compared with measurement giving the error not greater than 10%.
ADDITIONAL LOSSES IN OVERLAPPING AREA OF TRANSFORMER CORE
Authors: Rezic Ante , Valkovic Zvonomir
Published: February 2008

The influence of overlap length and overlapping design on core loss and magnetizing current of single‐phase two‐leg transformer core has been investigated The investigation was performed experimentally, on scaled models, and numerically, using 2D finite element method Two types of overlapping, mitred and staggered one, were investigated. It has been observed that the influence of overlap length on core magnetic characteristic is much higher in the case of the mitred overlap than that of the staggered one. This difference has been explained by the reduction of core cross section due to the triangle cutout in the mitred overlap.
3‐D HYBRID ANALYTICALLY‐NUMERICAL COMPUTATION OF TANK LOSSES IN 3‐PHASE POWER TRANSFORMERS
Authors: Turowski J. , Kopeć M.
Published: February 2008

3‐D Reluctance Network Method has proved as an effective, experimentally verified method of an evaluation of leakage fields and interactive design of screens. Though relative loss distribution is also easy to obtain the evaluation of absolute value — due to higher order of nonlinearity is much more difficult. In the paper analysis of this problem and simplified method of total loss calculation in tank wall, with semiempirical correction is given.