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  • Articles  (62)
  • Numerical Methods and Modeling  (62)
  • Wiley-Blackwell  (62)
  • MDPI Publishing
  • Electrical Engineering, Measurement and Control Technology  (62)
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  • Articles  (62)
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  • Wiley-Blackwell  (62)
  • MDPI Publishing
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  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 131-131 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 2
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 123-130 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents the electrode separation method for the boundary condition of a-Si TFT mixed-level simulation. The Poisson equation and the continuity equation are formulated into equivalent circuits. So, a circuit simulator can be used to handle the two-dimensional numerical simulation of a-Si TFT. The boundary condition problem between a semiconductor and an external circuit is solved by the electrode separation method. An electrode is separated into two nodes to fit Kirchhoff's current law and the semiconductor equations, respectively. A simple a-Si TFT/LCD circuit is taken as an example for the electrode separation method. For mixed-level simulation this technique is very useful. © 1998 John Wiley & Sons, Ltd.
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  • 3
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 133-151 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Most traditional theories of speech production are currently based on plane waves. However, it is well known that, for acoustic waveguides, higher acoustical modes start to propagate and can become predominant above cut-on frequencies. This paper thus presents the transmission line matrix method, a numerical method initially designed for electromagnetic waves, and its adaptation to acoustic waveguides. The method, and in particular the representation of boundary conditions, is validated by comparison with known analytical theories. It is then used to show the dramatic effect of higher order modes upon the radiation characteristics of uniform ducts, as well as the importance of source location. Finally, first applications to bent and bifurcating rectangular ducts are presented, and the transfer function of a vowel [a] is shown to display frequency patterns typical of those measured on human subjects and that cannot be explained by one-dimensional propagation only. © 1998 John Wiley & Sons, Ltd.
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  • 4
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 189-205 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The atomic mixing model that forms the basis of the IMPETUS software is described in detail. The model simulates the mixing and particle emission that occurs when a solid is bombarded with energetic particles, such as in SIMS or SNMS. The methods employed for computing the deposition of the bombarding particles and their energies along with the modelling of the particle yield and the surface recession speed are described.The material volume concentrations are governed by a set of partial differential equations. A description of the finite element method that is employed for their solution is given. Results from the application of IMPETUS II to a number of typical structures are given. © 1998 John Wiley & Sons, Ltd.
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  • 5
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 245-264 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper deals with absorbing boundary conditions for the finite difference time domain (FDTD) method applied to homogeneous lossless waveguide structures. A theoretical formulation of the so-called ‘modal absorption’ (MA) is developed. On the basis of this theory different implementations available in the literature have been derived and compared. Then, some techniques to enhance the efficiency of the method have been proposed and tested. It is demonstrated that, with the proposed methods, the high level of accuracy of the original formulations is retained, while the computational cost is strongly reduced. © 1997 John Wiley & Sons, Ltd.
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  • 6
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 285-301 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A new approach for the time-domain simulation of power electronic circuits is developed. The methodology is based on stepwise identification of circuit topology. The simulation process automatically looks for a valid topology in every step. At each simulation instant, the circuit topology is transformed into a resistive network, giving another superior feature of this method: the avoidance of solving complicated s-domain or differential formulas. No small-signal approximation is assumed. Parasitic resistance of the reactive element is included in the circuit model. Several examples illustrating the generality and computational efficiency of this new method are presented. The simulated results are favourably verified with experimental measurements and available literature. © 1997 John Wiley & Sons, Ltd.
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  • 7
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 3-19 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents an efficient space domain integral formulation of planar dielectric structures based on the concepts of multiresolution analysis (MRA) theory. Battle-Lemarie multiresolution expansions are utilized in the moment method solution of a volume integral equation for the unknown electric field. The generation of sparse moment matrices is explained in view of the cancellation property of wavelet basis functions. The formulation is then applied to two- and three-dimensional dielectric structures including waveguides and resonators, and the numerical results and consequences of matrix sparsity are discussed in detail. © 1998 John Wiley & Sons, Ltd.
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  • 8
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 21-40 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: An efficient wavelet-packet-based time-frequency technique is proposed in this paper. This technique has found applications in inverse synthetic aperture radar (ISAR). It combines the Wigner-Ville distribution (WVD) of each sub-band signal partitioned from an input signal by the wavelet-packet transform (WPT). These distributions are used to estimate the parameters in Doppler processing. Similar parametric compensation is carried out in range processing so that a specific scatterer is focused in both range and cross-range. The end result uses the Fourier imaging method to obtain a high-resolution radar image. This technique is primarily based on estimation and compensation of the Doppler scattering parameters of the dominant scatterers for improved focus. It can be of great value to the scattering-oriented ISAR imaging. © 1998 John Wiley & Sons, Ltd.
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  • 9
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 273-274 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 10
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 255-257 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: We re-examine the potential drop method to give a direct estimation of the absolute error in transmission-line matrix (TLM) diffusion modelling. In particular, the open-circuit boundary is taken into account. Promising results are presented with a structure relevant to thermal analysis of semiconductor devices. © 1998 John Wiley & Sons, Ltd.
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  • 11
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 259-271 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: There is a class of material processing simulators which require solution of the diffusion equation over a surface which is evolving due to some physical or chemical process related to the concentration of the diffusing species. Because of its explicit and unconditionally stable nature, the transmission line matrix (TLM) method is well suited to efficiently solve the diffusion equation in these instances. However, the methodology for using TLM on a dynamic problem space is not well established.This paper describes the development of algorithms to handle the insertion, deletion and motion of TLM nodes along the one-dimensional surface of a two-dimensional thin film process simulator called GROFILMS. These routines are completely compatible with concurrent time scaling to increase computational efficiency. Central to this development is the use of an asymmetric TLM cell which provides more flexibility for representation and minimizes the disturbance effects of these nodal operations. The scaling routines apply conservation of charge and continuity of current into the affected region to recompute the scattered or the incident pulses as a result of the evolving network. Verification of these results through comparison with known analytic solutions is achieved where possible. © 1998 John Wiley & Sons, Ltd.
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  • 12
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 205-207 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A hybrid representation formulation approach is presented. It avoids some numerical inconveniences and was successfully used as an intermediate step to obtain the differential algebraic equations of PWL modelled VLSI circuits. © 1997 John Wiley & Sons, Ltd.
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  • 13
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 193-204 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: An analysis of arbitrary thin-wire loop antennas and scatterers using periodic orthogonal wavelets is presented. The periodic orthogonal wavelet expansion is applied to solve the thin-wire version of the electric-field integral equation (EFIE). The curved solution domains are mapped into the definition domain [0, 1] of the periodic wavelets. The unknown current over each loop wire is expanded in terms of a basis derived from a periodic orthogonal wavelet through the maps between the curved integration domains and the interval [0,1]. The integral equation under study is converted into a sparse matrix equation by this technique. Numerical examples are provided for a variety of thin-wire loop antennas and scatterers. © 1997 John Wiley & Sons, Ltd.
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  • 14
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 47-56 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: In this paper, a finite element method for solving ionized fields is developed based on a novel solution philosophy. Employing the Galerkin finite element method, the solution problem of an ionized field has been formulated as an optimization problem, i.e. as a problem of minimizing an objective function whose minimum gives the solution. The effect of wind is taken into account by introducing a scalar potential of its velocity. © 1997 by John Wiley & Sons, Ltd.
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  • 15
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 35-46 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The circuit and coupling properties of a dipole grid array placed inside a rectangular cross-section waveguide are analysed when also a rectangular aperture is used to couple the resonator energy into a semi-infinite waveguide. A Green function approach is employed to determine the current distribution on the dipole elements by solving an integral equation and taking into account the boundary conditions on the rectangular cavity walls. Both mutual and self-impedance terms are calculated for the dipole grid array, and the effects of the rectangular coupling aperture are also examined. © 1997 by John Wiley & Sons, Ltd.
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  • 16
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 1-2 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 17
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 101-105 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Recurrence relations are developed to determine the weighting coefficients used in the simulation of random signals and rough surfaces with given statistical characteristics. These results can provide (in real time) straightforward, accurate solutions to the system of non-linear, algebraic equations associated with the method of moving summations. Three possible numerical methods have been reported to obtain approximate solutions to the system of non-linear, algebraic equations. However, none of them is straightforward, and they all require a large amount of computing time. This work can be applied to the numerical solution of the generalized telegraphist's equations used to analyze vertically and horizontally polarized radio wave scattering problems from permeable media with random rough interfaces. © 1997 by John Wiley & Sons, Ltd.
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  • 18
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 121-136 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents a multigrid method for numerically solving the coupled Poisson-Schrödinger equations in one dimension for a multilayered HEMT device structure. It is shown that this method produces a good speed-up factor over the non-multigrid approach. This should make it suitable for incorporating into the two-dimensional HEMT model involving coupled Poisson, Schrödinger, current continuity and energy transport equations, with the Schrödinger equation being solved in slices perpendicular to the layer structure. The time taken to produce a multigrid solution depends on the size of the coarse grid and on the number of grids used. A method of predicting the time taken for any combination of these values is presented. The method is demonstrated for a 4-layer device. © 1997 by John Wiley & Sons, Ltd.
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  • 19
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 169-176 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a modelling strategy and a software tool for simulating the dynamical behaviour of an active antenna array. The array consists of active radiating elements placed in a chain, i.e. a collinear array arrangement. To assist modelling of the active antenna array a macro model has been used to represent each of the radiating elements in the array. This simplifies analysis and allows dynamical performance to be efficiently computed, the resulting dynamical behaviour of the array being presented as an animated visualization. A computer program is presented which can simulate the active array in the time domain so that various characteristics, such as mode formation and spacial coupling effects, can be observed. Experimental validation is given in order to justify the mode formation predictions of the simulator. © 1997 John Wiley & Sons, Ltd.
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  • 20
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 265-265 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 21
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 313-313 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 22
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 209-216 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: In this paper, a generalized approach for the analysis of multistrip multidielectric layer transmission line structures based on the Method of Lines (MoL) is presented. The proposed algorithm is not limited either by the number of dielectric layers or by the number of metallic strips that can be positioned at different interfaces. The program we have written has been successfully tested on various structures and the obtained results are compared with those published by other authors. © 1997 John Wiley & Sons, Ltd.
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  • 23
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 41-54 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The local support and vanishing moment property of wavelet bases have been recently used to obtain a sparse matrix representation of integral equations in the spatial domain. In this paper, an application of the cubic spline and the corresponding semi-orthogonal wavelets in the spectral domain is proposed for the evaluation of the reflection coefficient for open/short transmission lines. Because of the nearly optimal time (space)-frequency (wavenumber)-window product of the cubic spline and wavelet, the double spectral integrals appearing in the formulation can be computed more efficiently than with the commonly used piecewise sinusoidal (PWS) or triangular basis functions. It is shown that the time-frequency-window product of the triangular and PWS function are close to each other, whereas those of the cubic spline/wavelet are close to 0·5, the lowest possible value corresponding to functions of Gaussian class. Both the PWS and wavelet bases are applied to microstrip and coplanar waveguides with isotropic and anisotropic substrates, and the results are compared with published theoretical and experimental data. It is observed that even though the number of splines/wavelets required for an accurate representation of the current distribution in the transmission line is almost twice as high as the number of PWS functions, the overall computation time decreases significantly in the former case. © 1998 John Wiley & Sons, Ltd.
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  • 24
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 69-84 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The use of wavelet expansions in numerical solutions of electromagnetic frequency-domain integral equation formulations is steadily growing. In this paper we review the recently suggested impedance matrix compression (IMC) method for a more effective integration of wavelet-based transforms into existing numerical solvers. The difference between the IMC method and the previous approaches to applying wavelets in computational electromagnetics is twofold. Firstly, the transformation is effected by means of a digital filtering approach. This approach renders the transform algorithm adaptive and facilitates the derivation of a basis which best suits the problem at hand. Secondly, the conventional thresholding procedure applied to the impedance matrix is substituted for by a compression process in which only the significant terms in the expansion of the (yet-unknown) current are retained and hence a substantially smaller number of coefficients has to be determined. A few numerical results are included to demonstrate the advantages of the presented method over the currently used ones. The feasibility of ensuring a slow growth in the number of unknowns even when there is a rapid increase in the problem complexity is shown by an illustrative example. © 1998 John Wiley & Sons, Ltd.
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  • 25
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 87-103 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: An efficient novel algorithm is introduced for ground wave propagation problems. First, ground wave propagation characteristics for a vertically polarized short electric dipole over a smooth spherical earth are reviewed, reducing the vector electromagnetic problem for the three-dimensional spherical geometry to an equivalent two-dimensional rectilinear scalar potential problem which is solved by spectral analysis and synthesis. Alternative evaluations of the spectral integral yield ray optical and normal mode solutions, which are conventionally referred to as the Norton and Wait formulations, respectively. Combining these formulations in an efficient manner yields a hybrid algorithm which is constructed so as to account adaptively for the characteristics of ground wave propagation in interference, intermediate and diffraction regions (including mixed paths) for various source and/or receiver heights. Numerical comparisons are made with reference results obtained via the parabolic equation (PE) method, in parametric ranges where PE is reliable; this permits assessment of the effectiveness of the hybrid approach. © 1998 John Wiley & Sons, Ltd.
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  • 26
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 183-184 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 27
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 153-166 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Most methods for the numerical calculation of inverse Laplace transformations f(t) = L-1[F(s)] have serious limitations concerning the class of functions F(s) that can be inverted or the achievable accuracy. The procedures described in the paper can be used to invert rational as well as irrational or transcendental functions of the complex variable s. The required accuracy of the results can be enhanced without changing the algorithm, only at the cost of a longer computation time. The described methods were verified with many examples including transients in lumped/distributed systems with sections of lossy multiconductor transmission lines or with distributed RC elements. © 1998 John Wiley & Sons, Ltd.
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  • 28
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 29
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 167-181 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: In this study, a software package is described which has been developed for the simulation of detection and tracking in surface wave high frequency (SW-HF) radars. The aim is to investigate the problems related to detection and tracking of surface targets at beyond the horizon ranges. In SW-HF radars target detection and tracking involves stochastic features such as target RCS fluctuations, atmospheric, galactic and/or man-made ambient interference components, and the sea clutter with the dominant resonant Bragg returns which affect target detection are all incorporated in the package. In the model, first, terrain data are fed into the simulator by means of a specially designed graphical user interface. Then, a scenario is prepared where the radar's location, coverage and operational parameters can be defined, together with different targets and their sailing routes. The radial propagation paths for angular resolution cells are extracted from the terrain data with the lengths of (possible) sea-island transitions. The surface wave path losses are calculated over the smooth spherical earth's surface with finite conductivity. Surface roughness and mixed-path propagation effects are also included in these calculations. The target detection is performed in the frequency domain after calculation of the noise floor, signal to noise (SNR) and clutter to noise (CNR) ratios. Since SW-HF radars yield coarse range and azimuth but accurate velocity measurements, different Kalman filter techniques are applied for the target tracking, and algorithms are added to improve the track-measurement data correlation. Various simulation tests are performed and the results are presented. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 187-187 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 31
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 277-287 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The solution of Maxwell's equations is considered using the finite difference time domain (FDTD) method and the client-server software paradigm on a heterogeneous network of distributed computers. The performance of compilers is evaluated and the PVM 3.3 message-passing harness, in both its conventional and TCP mode of operation, is compared with direct calls to the lesser known TCP/IP routines on the operating system. An example is given showing the impact of using different floating-point representations, in each subdomain, when computing field updates. As far as we are aware to date, there has been no discussion of the actual content of the communication between concurrent FDTD processes; accordingly we have defined one such protocol. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 307-316 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents an FE modelling approach for the calculation of transient eddy currents in thin conductive layers, where the complexity of the geometry prohibits both a detailed FE modelling and the use of analytical tools. The method allows an estimation of the maximum values of eddy currents at a highly reduced modelling effort and the use of a commercial FE software package. A prerequisite is a slowly varying magnetic field that can be assumed to be unaffected by the eddy currents. It is shown that neither the source of the magnetic field nor the insulating environment has to be modelled. The model is built up exclusively from 2D elements and is excited via the magnetic vector potential. The spatial distribution of the latter is calculated separately in a magnetostatic calculation based on Biot-Savart's law. It is then applied in time-varying form as a dynamic boundary condition at every node of the model. The method was applied to a simple problem for which the results of a detailed FE calculation were available, to document its validity. Further numerical results are presented for the plasma vessel and the heat radiation shield of the Wendelstein 7-X fusion experiment in the case of an emergency discharge. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 231-243 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The suitability of the transmission line modelling method for studying field-particle interaction devices is assessed through an example of a simple two-cavity klystron amplifier. Two separate numerical studies are presented, covering both beam bunching in the buncher cavity and field generation in the catcher cavity. Also addressed are the possibility of modelling the effect of the finite thickness of the cavity wall and beam coupling. The modelling of these practical aspects has not only resulted in some important insights into the field-particle interaction problem, but also demonstrated that the computer code developed is a powerful and versatile design tool. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 217-229 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: We present an analysis of thin microstrip superconducting structures in which the effects of the superconducting material, of finite complex conductivity and finite thickness, are taken into account through the concept of sheet impedance coupled with an extension of the Spectral Domain Immittance Approach. The effect of the magnetic field on the penetration depth in the superconductor is included by solving the Ginzburg-Landau equations within the thin-film approximation (t/λ0 ≪ 1). The state of the material is determined self-consistently in such a way that when the critical field is exceeded, the material systematically shifts from the superconducting to the normal state. Special attention is paid to the behaviour of the system in the neighbourhood of the critical temperature, T/Tc ≃ 1. We report that, in some cases, the propagation constant of a superconducting microstrip line attains a maximum when the real and imaginary parts of the conductivity are approximately equal. Numerical results for a microstrip line and a patch resonator are presented and compared with available data to document the validity of the approach. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 371-371 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 303-312 
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    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Monte Carlo methods are generally known for solving field problems one point at a time, unlike other numerical methods such as the finite difference and finite element methods which provide the solution at all the grid nodes simultaneously. This paper provides a Monte Carlo technique for obtaining the solution everywhere at once. The technique uses absorbing Markov chains to obtain the transition probabilities for all of the grid nodes at once. The procedure is illustrated with some examples for homogeneous and inhomogeneous, rectangular and axisymmetric solution regions, and is found to be accurate. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 315-328 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A strategy is proposed to enhance the performance of some numerical methods used in the solution of electromagnetic problems. The strategy can be extended to any numerical method based on the partitioning of the spatial domain into elementary cells. Two different implementations of the strategy are compared: modified-reversed Cuthill-McKee and tabu search. While the former is well known, the latter is here applied for the first time to such problems. Their application is shown in conjunction with three different numerical methods: mode matching of complex MW circuits, finite difference solution of PDE and FEM analysis of microstrip lines. The efficiency and versatility of the approach is proved for each of the three numerical methods, reaching a reduction in the working times of up to 20 times. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 269-284 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A simple, approximate, but very rapid and accurate image method is proposed for the analysis of arbitrary wire antennas above a lossy half-space. The reflected field from vertical and horizontal Hertzian dipoles is approximated by the field of a few ‘optimally’ positioned simple elementary sources. The field of images is incorported into the Hallén-type equations for the current distribution, resulting in equations of essentially the same form as those for an isolated antenna. The equations are solved by the point-matching method and polynomial approximation of current along the antenna segments. The results for the impedance and admittance of antennas assembled of vertical, horizontal and/or oblique segments are in excellent agreement with the exact results (obtained from the Sommerfeld theory). The proposed method is conceptually very simple and on average 25 times faster than the exact method, although in some cases it was found to be faster for even two orders of magnitude. This makes it particularly suitable for numerical optimization and CAD of relatively complicated antennas and other wire structures above a lossy half-space. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 343-353 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: When we solve the wave equation by the finite element method, the order of convergence and the accuracy of the solution are reduced by the presence of sharp edges. The employment of singular elements improves the solution and allows us to reduce the cost of computation.In this paper, three types of scalar singular finite elements with the capacity to handle singularities in the derivative, and which have previously been applied to mechanical problems, are examined, together with standard elements, in the context of homogeneous waveguide analysis.We solve two examples of homogeneous waveguides showing the different behaviour of the singular elements and obtaining information on the order of convergence and the approximation of the gradient of the unknown function. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 329-341 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The dynamic analysis of discontinuities in printed circuits has been performed using the mode matching technique. This study concerns the open end of microstrip lines and suspended microstrip lines. The fields on either side of the discontinuity are described by means of the continuous (radiated and evanescent) and guided modes of the structure.The conditions of continuity of the electromagnetic fields are then applied in the plane of the discontinuity. By taking into account the relations of orthogonality of the modes of the same region, a system of coupled Fredholm integral equations is obtained and solved by the iterative method of Neumann's series.The study calls for the use of the continuous spectrum of microstrip lines, which can be obtained analytically only after a great amount of calculation and CPU time. Thus, the first approach consists in neglecting this continuous spectrum. This gives accurate results for the reflection coefficient but it is not sufficient for the derivation of the radiation pattern. So, two simple models for the continuous spectrum, both based on the physical behaviour of such discontinuities, are considered and discussed. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 55-68 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Multiresolution time domain (MRTD) analysis is applied directly to Maxwell's equations to model inhomogeneous dielectric material. In our approach, scaling and wavelet functions are used as a complete basis for the method of moments. The MRTD scheme is used to analyze different types of resonant cavity structures with varying dielectric perturbations in one, two and three dimensions. The results presented here agree very well with those obtained by FDTD, FEM and integral equation methods. MRTD allows for considerable savings in memory and computation time in comparison to FDTD, while maintaining the same accuracy of the results. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 1-1 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 105-121 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a computationally efficient diakoptic algorithm for the solution of closed-mesh electrical network equations. The algorithm is designed for use with time-varying and/or discontinuous equations describing limited size power supply systems, allowing them to be torn into smaller subdivisions in a manner that is independent of their structure. The efficiency of the algorithm is demonstrated by comparing its performance with that obtained when using a more conventional sparse matrix technique, on the basis of the number of floating point operations required for the solution of a range of typical network problems. Mention is made of the parallel processes inherent in the resultant equation structure. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 207-219 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The IMPETUS II code simulates the atomic mixing and particle emission that occurs when a solid is bombarded by energetic particles (as in SIMS or SNMS). The underlying model consists of a system of partial differential equations that are solved by a finite difference method (FDM). Special techniques are also employed to model thin layers and sharp interfaces, to deal efficiently with wide homogeneous layers (when the solution is tending to a steady state), to model linear diffusion in order to smooth the sharp interfaces before they enter to domain of the FDM.In this paper the special techniques are described in detail. Results from test problems, demonstrating these techniques, are shown. An algorithm that describes the way the IMPETUS II code is structured is given. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 221-229 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents a physical-mathematical model for abrupt heterojunction transistors and its solution using numerical methods with application to InP/InGaAs HBTs. The physical model is based on the combination of the drift-diffusion transport model in the bulk with thermionic emission and tunnelling transmission through the emitter-base interface. Fermi-Dirac statistics and bandgap narrowing distribution between the valence and conduction bands are considered in the model. A compact formulation is used that makes it easy to take into account other effects such as the non-parabolic nature of the bands or the presence of various subbands in the conduction process. The simulator has been implemented for distributed memory multicomputers, making use of the MPI message-passing standard library. In order to accelerate the solution process of the linear system, iterative methods with parallel incomplete factorization-based preconditioners have been used. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 273-273 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 233-242 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The propagation factors of buried microstrip lines are considered. The associated eigenvalue problems are solved by the edge-based vectorial finite element method (VFEM). To improve the higher-order VFEM solutions, the problem infinite domain is truncated by second-order absorbing boundary conditions (ABCs). This reduces the number of unknowns and, consequently, the numerical effort. Owing to the many advantages of both the edge-based VFEM and the second-order ABCs, this full-wave method is implemented by a general computer program for solving unbounded domain problems involving complex geometries and inhomogeneous media. The examples presented show the validity of this technique. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 243-254 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Various local absorbing boundary conditions are implemented in the TLM method and their corresponding reflections are compared as a waveguide termination. The instability in different ABCs is discussed and reflections from the terminating walls are computed. An improvement for the matched termination wall is proposed and reflection of this absorbing condition is compared with ordinary matched termination. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 317-318 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 289-298 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Oscillatory flow present in the melt during InSb single crystal growth using an RF-heating Czochralski method has been numerically investigated by means of the finite difference method using the HSMAC algorithm. The thermal boundary conditions required for the numerical simulation model were obtained experimentally by measuring the temperature profile along the crucible of a Czochralski system by means of thermocouples mounted in the crucible. Results of numerical simulations showed that the use of a third-order upwind discretization scheme was necessary to catch the oscillatory behaviour of the fluid flow in the melt. It was shown that this oscillatory behaviour strongly depends on the crystal rotation rate. Indeed, the oscillation period increases when the crystal rotation rate is above a critical rotation rate. In order to avoid such oscillations, crystal rotation rates lower than this critical value of crystal rotation rate must be selected for the growth of high quality crystals free of striations. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 11 (1998), S. 299-306 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The application of the FDTD algorithm on generalized non-orthogonal meshes, following the basic ideas of Holland (1983), has been investigated by many authors for several years now, and detailed dispersion analysis as well as convergence studies have been published. Already in 1992 also a general stability criterion was given for the time integration using the standard leap-frog scheme (Lee et al.). Many authors, however, still propose some damped time stepping algorithms to work around unexpected instabilities in the discretization method. In this paper the origin of this type of instability is revealed, and a technique to obtain a stable discretization of Maxwell's equations on non-orthogonal grids is proposed. To obtain more insight into the stability properties of the method, it is reformulated according to the matrix-vector notation of the Finite Integration Technique. © 1998 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 13-34 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Specifying electromagnetic compatibility (EMC) is a crucial step in the performance evaluation of electrical and electronic systems. This paper describes a circuit formulation for the EMC assessment of large and complex systems.The proposed method is based on breaking the actual structure down into an aggregation of multiport devices: lumped-parameter circuits and distributed-parameter multiports. The multiconductor transmission line (MTL) model is used for the description of signal propagation along system interconnects: uniform, twisted and shielded lines are considered. Accurate prediction models (including line losses and dispersion) are utilized for the quantitative evaluation of both intrasystem compatibility and susceptibility to radiated interference.The description of the network topology makes use of the concept of an incidence matrix which is widely used in lumped-circuit theory. It is extended here to the more general case of distributed networks. The entire analysis is carried out in the frequency domain and a transient response is obtained by using inverse Fourier and Laplace transforms.Noteworthy characteristics of the method can be seen in the simplicity and effectiveness of the prediction models and in the minimal effort required for system description. The proposed method is especially significant for complex systems, where the number of connecting structures can be quite large. © 1997 by John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 57-69 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The modified Gaussian algorithm is introduced for solving the ionized fields of unipolar HVDC lines including the effect of wind. Specific techniques of incorporating in the algorithm the special structure of the optimization problem of the ionized field have been developed to economize the requirements for the computer memory and CPU time. Numerical tests are carried out on a coaxial cylindrical geometry and on a line-plane geometry both in the absence and in the presence of wind. Comparison with available experimental data shows good agreement. © 1997 by John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 107-119 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A self-consistent numerical transport model based on the hydrodynamic equations obtained from Boltzmann's transport equation (BTE) is presented. The model includes both the temporal and spatial variation in electron velocity. A parallel implementation of the solution method, using FDTD techniques, is illustrated. Numerical results for a GaAs MESFET device are generated using this complete hydrodynamic model (CHM) and compared with results obtained from the more commonly used energy or simplified hydrodynamic model (SHM). The results indicate that for short gate-lengths (less than 0⋅5 μm) the two models lead to different DC steady-state results which in turn lead to different microwave small-signal models for the device. © 1997 by John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 139-151 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The response of a p-i-n photodetector made from gallium arsenide to both steady-state and transient illumination has been modelled. Both an ensemble Monte-Carlo model and a drift-diffusion model were used, the latter with the choice of two different mobility models. The effects of high intensity steady-state illumination on the field and carrier distributions in the photodetector were calculated, and a comparative study of the models made. The transient response to pulsed illumination has also been calculated and the different results obtained from the models explained. The effect of high illumination on the response speed of the detector has been demonstrated. In addition, an expression for obtaining the photocurrent from the Monte-Carlo simulation, with much reduced statistical noise over the conventional estimate, has been derived and successfully tested. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 177-192 
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    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: When compared with commonly used subdomain moment-method analysis, entire-domain analysis of 3D dielectric scatterers results in a greatly reduced number of unknowns. Unfortunately, the expressions for matrix elements tend to be quite complicated and their calculation extremely time-consuming if evaluated directly. It is shown in the paper that, in a Galerkin-type solution with large trilinear hexahedral basic volume elements and three-dimensional polynomial approximation of volume current inside them, these expressions can be manipulated analytically for optimized rapid non-redundant integration. Consequently, a method for the analysis of 3D dielectric scatterers is obtained that is efficient, rapidly converging with increasing degree of approximation for current, remarkably accurate and very moderate in computer memory requirements. The applicability of the method of moments is thereby extended to bodies of electrical sizes greatly exceeding those that can be dealt with by subdomain methods. © 1997 John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 1-1 
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    Keywords: Engineering ; Numerical Methods and Modeling
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 71-82 
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    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: In this paper we present an efficient method for numerical solution of the transport equation of photogenerated carriers in MSM photodetectors. The method is based on conformal mapping of both the MSM photodetector structure and the system of transport equations into a new space. The mapping enables analytical calculation of the electric field, allowing one to take one of the co-ordinates as a parameter and thus reducing the problem to quasi-one-dimensional. In addition, the method of conformal mapping enables calculation of the normalized current response of a photodetector in the new space. © 1997 by John Wiley & Sons, Ltd.
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 83-99 
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    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A numerical method is used to solve the integro-differential generalized telegraphists' equations for the total (single and multiple) diffusely scattered radiation wave amplitudes. These equations were derived using a full wave approach. The singularities of the scattering coefficients are removed on integrating by parts. A stationary phase approximation is used to obtain the far fields. The numerical solutions are obtained for one-dimensional deterministic surfaces. The numerical results for the total (single and multiple) diffusely scattered fields are in good agreement with the earlier single scatter analytical results when the maximum surface slope is less than 30 degrees. The earlier single scatter analytical solutions are based on the assumption that the total field impressed upon a rough surface is associated with the incident field only. This assumption is not made for the evaluation of the numerical results presented here. The earlier analytical results are in total agreement with the small perturbation results when the rough surface height and slopes are of the same order of smallness. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 15 Ill.
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  • 60
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 153-167 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A generalized modal scattering matrix formulation is presented for the calculation of discontinuity-distorted waveguide multiport junctions. Unlike common approaches based on three-plane mode-matching techniques, and modifications thereof, which calculate only the fundamental-mode scattering matrix, this algorithm computes the generalized modal scattering matrix of the junction. Therefore, the method allows the computation of components in which other structures are connected as closely as possible to the discontinuity-distorted junction as follows directly from the rigorous incorporation of all higher-order mode interactions. The method is demonstrated at three selected examples: the waveguide corner, the T-junction power divider and the orthomode transducer. Comparison with results obtained by other numerical techniques or measurements available from the literature are found to be in good agreement. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
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  • 61
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 355-370 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents a highly stable relaxation iterative algorithm for solving the ionized fields of unipolar HVDC transmission lines in the absence or in the presence of wind. The finite element method is employed to solve Poisson's equation, and the upwind finite volume method is applied to solve the current continuity equation. The algorithm has been tested up to a wind velocity of 45 m/s. Results obtained for a unipolar HVDC transmission line model show that the application of the upwind method increases the stability and convergence of the iterative algorithm when wind is stronger, while the implementation of a relaxation technique makes it possible for the iterative algorithm to cover a wide range of wind velocities, geometric parameters and ratios of the applied voltage to the corona onset value. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 21 Ill.
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  • 62
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 10 (1997), S. 3-11 
    ISSN: 0894-3370
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents an adapted Gummel method (AGM) used in the two-dimensional device simulation of an amorphous-silicon (a-Si) thin-film transistor (TFT). Firstly, the AGM for amorphous silicon is developed by modifying the Gummel method (GM) for crystalline silicon. Secondly, the AGM is implemented into a two-dimensional device simulator for the simulation of a-Si TFTs. The simulation results show that the AGM converges well while the GM fails to converge for the simulation of a-Si TFTs. Hence, the AGM is a useful technique for the simulation and analysis of a-Si TFTs. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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