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Title: 3B-SPLINES IN THE INTEGRAL EQUATION SOLUTION FOR SCATTERING FROM BODIES OF REVOLUTION
Abstract: The use of B-Splines functions is investigated in conjunction with the Method of Moments integral-equation solution to the problem of scattering from conducting bodies of revolution. Its computational performance in terms of relative accuracy and storage/CPU time requirements is evaluated against entire-domain and sampling-like basis functions. Particular attention is given to the description of current near edges. Questions of time (space) and frequency (wavenumber) localization are also addressed. A simple scheme devised to enforce boundary conditions a priori is shown to potentially capable to stgabilize otherwise spurious solutions
Author(s): F.L. Teixeira, J.R. Bergmann
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
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Title: ELECTROMAGNETIC PROPERTIES OF A CHIRAL-PLASMA MEDIUM
Abstract: The theoretical properties of a composite chiral-plasma medium are devel- oped. Using the reaction theorem, we obtain the proof of nonreciprocity based upon the constitutive relationships between the electromagnetic vectors E, B, H, D. Using the Maxwell's equations and the proposed constitutive relations for a chiral- plasma medium, we derive the E, and H, vector equations and from these equations, dispersion relations and E-field polarizations are found. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 14-18] MTRT - A MODIFIED TRANSVERSE RESONANCE TECHNIQUE
Author(s): Hector Torres-Silva, Norma Reggiani, Paulo H. Sakanaka
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
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Title: MTRT - A MODIFIED TRANSVERSE RESONANCE TECHNIQUE
Abstract: In this work a modified formulation of the transverse resonance technique (TRT) is presented. The difference between the usual TRT and the formulation presented here, MTRT, is the equivalent network considered. With the MTRT proposed formulation, mode solution identification requires less arduous work. The complete equation set is described. Numerical results are presented for dispersion characteristics of microstrip lines, coupled microstrip lines and conductor-backed coplanar waveguides (CBCW). When compared to results obtained by other methods, a good agreement is observed. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 19-25]
Author(s): Alfredo Gomes Neto, Creso S. da Rocha, Herve' Aubert Aubert, D. Bajon, H. Baudrand
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
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Title: EFFECT OF THE MAGNETIC ANISOTROPY ON THE CHARACTERISTICS OF MICROSTRIP ANTENNAS WITH SEVERAL LAYERS
Abstract: The main objective of this work is to show how the properties of a ferrimagnetic material change the characteristics of a microstrip patch with several layers. Particularly, it is investigated how the resonant frequency and the radiation pattern are changed by varying the ferrimagnetic layer thickness or the magnitude and/or direction of the external applied magnetic field. The analysis is carried on by using Hertz potentials and Galerkin method. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 26-29]
Author(s): Jose de Ribamar Silva Oliveira, Adaildo Gomes d'Assunc o
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
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Title: DISPERSIVE ANALYSIS OF CIRCULAR CYLINDRICAL MICROSTRIPS AND BACKED SLOTLINES
Abstract: In this work, the full-wave analysis of circular cylindrical microstrips and backed slotlines is performed, by using a combination of Hertz vector potentials and Galerkin method. The analysis is developed in the spectral domain. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 30-33]
Author(s): Laercio Martins de Mendonca, Adaildo Gomes d'Assunc o
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 268 KB

Title: FINITE ELEMENT ANALYSIS AND EVALUATION OF ELECTROMAGNETIC FIELDS GENERATED BY ATMOSPHERIC DISCHARGES
Abstract: A lightning return stroke channel is modeled by a high loss transmission line. The differential equations that represent its dynamic behavior are solved by the application of the one-dimensional finite element method (FEM). By the combination of FEM results with the use of Maxwell equations applied to the dipole method, electric and magnetic (EM) fields are evaluated at various positions in space. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 34-38]
Author(s): E.H.R Coppoli, R.R. Saldanha, A. Konrad
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 318 KB

Title: POINT-MATCHED TIME DOMAIN FINITE ELEMENT METHOD APPLIED TO MULTI-CONDUCTOR ELECTROMAGNETIC TRANSIENTS ANALYSIS.
Abstract: A point-matched time domain finite element method (TDFE) applied to the analysis of electromagnetic transients in multi-conductor transmission line network is presented. The TDFE method solves the partial differential transmission line equations based on a semi-discrete approximation using the finite element method and leap-frog scheme. Some oscillations can occur due to the stability condition of the technique. Using the modal analysis these oscillations can be eliminated. A surge propagation in a simple multi-conductor network is presented and the results are compared with the Electromagnetic Transients Program (EMTP) simulations. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 39-43]
Author(s): Glassio Costa de Miranda
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 319 KB

Title: ERROR ESTIMATORS IN SELF-ADAPTIVE FINITE ELEMENT FIELD CALCULATION
Abstract: The aim of this paper is to present different error estimates to improve accuracy in linear and nonlinear self-adaptive finite element field calculation. The first estimator is based on the polynomial theory, the second one makes an estimation of the flux density divergence, the third one is linked to a magnetomotive force associated to elements sides, and the fourth one is based on the use of the bilinear element. All methods were implemented in our software named LMAG2D developed at "Escola Politecnica da Universitade de S o Paulo", Brazil. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 44-49]
Author(s): L. Lebensztajn, J.R. Cardoso Cardoso
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 386 KB

Title: TRANSIENT VOLTAGE AND ELECTRIC FIELD DISTRIBUTIONS IN AIR CORE REACTORS
Abstract: This work presents a computational model for the evaluation of transient voltage and longitudinal electric field distributions in single layer air core reactors. The influence of a grounded shielding concentric to the reactor is considered. The validity of the model is verified by comparing computed and measured voltage responses at three taps of a test reactor. Analyses showing the influence of the grounded shielding, front time and front wave shape of the applied voltage on the maximum longitudinal electric stresses along the reactor winding are presented. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 50-55]
Author(s): S. L. Varricchio, N. H. C. Santiago
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 324 KB

Title: CALCULATION OF ELECTRIC FIELD CREATED BY TRANSMISSION LINES, BY 3D-FE METHOD USING COMPLEX ELECTRIC SCALAR POTENTIAL
Abstract: This paper presents a methodology for tridimensional analysis of the electric field produced by transmission lines. It utilizes the complex electric scalar potential, which makes it possible to consider variation of module and phase in the voltages of supply lines. The Finite Element Method (FEM) is applied to solve the differential equation that describes the phenomenon in the domain of this study. Finally, a comparison is established between the results obtained applying the proposed methodology and the values reached through the classical method of charge simulation. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 56-60]
Author(s): Ricardo Marcal Matias, Adroaldo Raizer
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
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Title: ADAPTIVE FINITE ELEMENT MESH REFINEMENT AND 'A POSTERIORI' ERROR ESTIMATION PROCEDURES FOR ELECTROMAGNETIC FIELD COMPUTATION
Abstract: Adaptive Finite Element (FE) mesh refinement combined with a robust and functionally reliable error estimate provides nearly optimal solution accuracy. The efficiency of adaptivity depends on the effectiveness of the mesh refinement algorithm and also on the availability of a reliable and computationally inexpensive error estimation strategy. An adaptive mesh refinement algorithm utilizing a hierarchical minimal tree based data structure for 2D and 3D problems is discussed in this paper. Two different 'a posteriori' error estimation schemes, one based on the local element by element method and the other using the gradient of field approach are also presented. The usefulness of the mesh refinement algorithm and the error estimation strategies are demonstrated by adaptively solving a set of 2D and 3D linear boundary value problems. The performance of the error estimates is also verified for adaptive modeling of a nonlinear problem involving the design of a permanent magnet synchronous machine. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 61-68
Author(s): K.C. Chellamuthu, Natan Ida, Q.k. Zhang
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 656 KB

Title: DESIGN OF ELECTRICAL MACHINES AIDED BY FIELD CALCULATION AND FACTORIAL EXPERIMENTS METHOD
Abstract: An approach for electrical machines design by using magnetic field computation coupled to factorial experiments is presented in this paper. Principles of factorial experiments are briefly reviewed and their application to design optimisation is explained. In this application experiments are replaced by magnetic field calculations. The procedure, which performs automatically all the numerical field calculations required, is described. The whole procedure is applied to a typical problem concerning permanent magnets synchronous motor with polar pieces. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 69-73]
Author(s): C. Pertusa, S.Astier, Y.Lefevre, M.Lajoie-Mazenc
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 317 KB

Title: LIMITATIONS OF THE CONVENTIONAL METHODS OF FORCE AND TORQUE PREDICTION
Abstract: The calculation of forces and torques developed in electromechanical devices, and their variation with changes in position or excitation, is often what the designer is, ultimately, interested in. This paper addresses some of the problems associated with the force and torque calculations based on numerical field solutions for 2-D magnetostatic problems. The problem of calculating the cogging torque characteristic of a neodymium-iron-boron permanent-magnet motor is considered and the technique of torque measurement is described briefly. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 74-79]
Author(s): Antonio Flavio Licari o Nogueira
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 480 KB

Title: COMPARISON OF CONVERGENCE RATES OF EDGE AND NODAL FINITE ELEMENTS FOR MAGNETOSTATIC PROBLEMS
Abstract: Mathematical theory is used to obtain convergence estimations for magnetostatic formulations using nodal and edge elements. Numerical results of two closed boundary problems that confirm the theory are presented. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 80-83]
Author(s): M. L. y Gonzalez, R. C. MesquitaM. L. y GonzalezMesquita, J. P. A. Bastos
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 231 KB

Title: FINITE ELEMENT SIMULATION OF AN OUT-OF-PHASE SYNCHRONIZATION OF A SYNCHRONOUS MACHINE
Abstract: This paper presents the finite element simulations of the out-of-phase synchronization of a synchronous machine with an external electric system. Two cases were analysed regarding to the phase angle: 120 and 180 . Computed results are analysed and compared to analyticalvalues.[Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 84-89]
Author(s): Silvio Ikuyo Nabeta, Albert Foggia, Jean-Louis Coulomb, Gilbert Reyne
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 306 KB

Title: A 3D FINITE-ELEMENT COMPUTATION OF STATOR END-WINDING LEAKAGE INDUCTANCE AND FORCES AT STEADY STATE OPERATING CONDITIONS IN LARGE HYDROGENERATORS
Abstract: The forces acting on the stator end windings of a hydrogenerator at steady state operating conditions, as well as the end-winding leakage inductance, are calculated using a 3D finite element package. A more realistic representation for the geometry of the windings and boundaries is considered. The effects of different representations for the stator core end surface are outlined. The computed values of the inductance from time harmonic and static simulations are presented and compared with classical analytical methods. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 90-96]
Author(s): Viviane Cristine Silva, Albert Foggia
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 520 KB

Title: IMPROVING THE CHARGE SIMULATION METHOD FOR THE COMPUTATION OF HIGH VOLTAGE ELECTRIC FIELDS WITH EFFICIENT LEAST SQUARES TECHNIQUES
Abstract: The well known Charge Simulation Method, which is commonly used for electric field calculations, is shown to be a particular and ill-conditioned case of the Least Squares Charge Simulation Method. By solving a practical problem, it is shown how to efficiently handle a least squares problem, thus obtaining results of higher precision if compared to the traditional Charge Simulation Method For the solution of the resulting linear system, several mathematical methods are analyzed and compared, being stated that the optimum combination of higher precision, lesser error propagation, lesser CPU time and lesser computer RAM are simultaneously reached when applying the Least Squares Charge Simulation Method, solved with the QR decomposition and Householder transformations. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 97-102]
Author(s): J. N. Hoffmann, P. Pulino
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 467 KB

Title: A HYBRID FINITE DIFFERENCES, AND CHARGE SIMULATION METHOD FOR THE COMPUTATION OF HIGH VOLTAGE ELECTRIC FIELDS
Abstract: A new treatment is proposed to the hybrid method of Finite Differences and Charge Simulation for the computation os electric fields, entirely applicable to the similar hybrid method of Finite Element and Charge Simulation. The resulting system of linear equations is solved by using the fixed point theory, the QR decomposition and the Conjugate Gradients Squared method with a preconditioning technique. New procedures are suggested for the discretization of the boundary conditions, which lead to results with higher precision. Case studies are included. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 103-110]
Author(s): J. N. Hoffmann, P. Pulino
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 593 KB

Title: FINITE ELEMENT MODELING OF ELECTRICAL MACHINES BY SIMULTANEOUS RESOLUTION OF FIELDS AND ELECTRIC CIRCUITS EQUATIONS
Abstract: In this work, we present a methodology for solving simultaneously the equations of magnetic fields and electric circuits of electrical machines. To consider the magnetic phenomena the Finite Element method is used. The machines are voltage fed and, thus, the electric circuit equations are present in the matricial system which takes into account both physical aspects. A time stepping technique is employed to simulate the steady and transient states. As result, we obtain the magnetic vector potential describing the magnetic behavior of the machine and the current established in the exciting coils. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 111-116]
Author(s): N. Sadowski, R. Carlson, J. P. A. Bastos, M. Lajoie-Mazenc
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 443 KB

Title: SHAPE DESIGN OPTIMIZATION OF POWER FREQUENCY ELECTROMAGNETIC DEVICES USING NUMERICAL METHODS
Abstract: This paper presents the mathematical formulation concerning the solution of inverse electromagnetic problems, i.e. the shape optimization of power frequency electromagnetic devices, based on a combination of numerical methods. The optimization problem is solved using deterministic methods in which the electromagnetic field problem is treated as a subproblem of the optimization process. The field problem is calculated using the finite element (FE) method. Three deterministic approaches are studied in detail, the quadratic extended penalty method (QUA), the augmented Lagrange multiplier (ALM) method and the constrained quasi-Newton method (PLBA-CR). The work highlights the advantages and drawbacks of each approach. The search direction for the optimization is found by two distinct methods, the direct differentiation of the FE matrices and the finite difference (FD) method. In total, three problems are discussed in order to show the power and applicability of the theory presented. The PLBA-CR, when combined with the direct differentiation of the FE matrices, appears to offer important advantages over the other methods. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 117-124]
Author(s): Jaime A. Ramirez, Ernest M. Freeman, C. Chat-uthai, Jo o A. Vasconcelos
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 485 KB

Title: DETERMINATION AND ANALYSIS OF CAUSES OF INDUCTION MOTOR MAGNETIC NOISE
Abstract: This paper presents the causes of the acoustic noise magnetically generated by three-phase induction electric motors and some results of tests and calculation are discussed. The influence of the rotor slots skewing on the reduction of the magnetic noise is also analysed through calculated values. The paper gives a general view about how the magnetic noise in induction motors is generated and how much its prevision is important during the design stage. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 125-131]
Author(s): Sebasti o Lauro Nau, Solon Brum Silveira
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 459 KB

Title: GROUND-3D LINKED TO LINE PARAMETERS: A METHOD TO FAULT CURRENT DISTRIBUTION AND EARTH POTENTIAL DETERMINATION
Abstract: In previous work [1,2] the author presents a methodology, based on finite elements method (FEM), to calculate the potential distribution influence on the grounding area. At that time the input of the solver admits as known the split of the system. The aim of this article is to demonstrate the advantages of finite element method (FEM) associated with power systems equations with lumped parameters to intrinsically obtain the distribution of fault current in several offered conductor ways and the potential distribution on the ground, simultaneously. To solve the complex equations system, the methodology adopted was that described by Mesquita [3]. . [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 132-135]
Author(s): H. O. Brodskyn, M. C. Costa, J. R.Cardoso, N. M. Abe, A. Passaro
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 307 KB

Title: AN INVESTIGATION OF THE SCATTERING OF SURFACE WAVES AT DIELECTRIC SLAB WAVEGUIDE WITH AXIAL DISCONTINUITY
Abstract: This paper introduces a technique for studying the radiation due to an abrupt axial discontinuity in the geometry of a planar dielectric waveguide (Slab waveguide) when an even TM surface wave strikes the discontinuity. The mode matching technique is applied at the discontinu- ity giving rise to formally exact integral equations which are solved by the Method of Moments. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 136-141]
Author(s): Creso S. Da Rocha
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 394 KB

Title: ADAPTIVE MESHING IN TWO-VARIABLE STATIC PROBLEMS WITH FIELD BASED ERROR ESTIMATORS USING EDGE AND FACET ELEMENTS
Abstract: In this paper a family of field-based error estimators for Finite Element analysis of electrostatic and magnetostatic problems in plane and axisymmetric geometries is presented. For the error estimation in magnetostatics, each element is divided in three sub-elements using an edge element approach, whereas for electrostatic problems a subdivision using facet elements is used. The methods and the numerical techniques are described, comparisons with known solutions are performed, some examples of application in cases of practical interest are reported and the obtained results are briefly discussed. . [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 142- 147]
Author(s): P. Girdinio, P. Molfino, G. Molinari, M. Nervi
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
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Title: FINITE ELEMENT MODELLING SCHEMES FOR THE DESIGN AND ANALYSIS OF ELECTRICAL MACHINES
Abstract: Electrical machines are complex objects. We have found that a variety of numerical techniques are required in order to model them using finite elements. We concentrate here on the different formulations which are useful in modelling such devices. Examples of modelling some of these machines using the MEGA package are described. . [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 148- 152]
Author(s): D.Rodger, P.J. Leonard, H.C. Lai, N. Allen
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
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Title: THREE DIMENSIONAL MAGNETOSTATICS USING THE MAGNETIC VECTOR POTENTIAL WITH NODAL AND EDGE FINITE ELEMENTS
Abstract: In this paper, the three dimensional vector potential magnetostatic problem is solved using nodal and edge finite elements. The influence of the gauge condition A.w=0 in the characteristics of the edge-element generated matrix is analyzed. Three gauge conditions are studied: no gauge, the complete A.w=0 gauge and the incomplete A.w=0 gauge condition. [Vol. 12, No. 1 (1997), Special Issue on International Computational Electromagnetics, pp 153-156]
Author(s): E. J. Silva, R. C. Mesquita Mesquita
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
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Title: A NEW ITERATIVE MOMENT METHOD SOLUTION FOR CONDUCTING BODIES OF REVOLUTION
Abstract: An iterative solution of the combined field integral equation (CFIE) has been obtained for perfectly conducting bodies. The proposed technique avoids the inversion of the moment method (MoM) matrix by using an iterative algorithm which shows fast convergence properties, mainly for large bodies. The algorithm is applied to several 3D problems involving bodies of revolution (BOR). Accurate currents are computed with important speedups over direct MoM solutions. [Vol. 12, No. 2 (1997), Special Issue on Numerical Field Calculations in Electrical Engineering, pp 6-10]
Author(s): F. Obelleiro, J. L. Rodriguez, A. G. Pino
File Type: Journal Paper
Issue:Volume: 12      Number: 1      Year: 1997
Download Link:Click here to download PDF     File Size: 319 KB