摘要:

AbstractA novel spectral procedure for the numerical solution of non‐linear boundary value problems is presented. The discrete spectral equations are solved by an iterative algorithm using space‐domain preconditioning. The preconditioning operator is obtained by spatial weighting (or windowing) of the exact differential operator.Convergence behaviour of the iterative solution is investigated using an eigenvalue analysis. Theoretical estimates for the convergence rate and accuracy are compared with that achieved in a numerical application—a non‐linear boundary value problem from semiconductor device modelling.The method combines the infinite‐order exponential accuracy of spectral discretizations with the sparse structure of finite difference equations. This offers numerical advantages in comparison to previously developed Fourier–Galerkin algorithms, particularly important for physically ill‐conditioned and strongly non‐linear problems. The tradeoff of achievable accuracy versus computer time is easily controlled, thus making essential speed‐ups possible for moderate accu

ISSN:0894-3370    

DOI:10.1002/jnm.1660050202

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe permeability tensor of the homogeneous bulk material externally equivalent to a laminated packet of non‐linear, anisotropic, non‐hysteretic sheets is derived by symbolic computation. The composite permeability bears a surprisingly simple algebraic relationship to the local permeabilities of its component materials even in the general case. Several special cases of common interest, where the tensor permeability assumes symmetric or diagonal form, are examined. Results are presented both as algebraic expressions and as brief optimized Fortran subroutines suitable for fitting into field analysis progr

ISSN:0894-3370    

DOI:10.1002/jnm.1660050203

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIn this paper the application of the TLM method to electromagnetic scattering problems is investigated. To achieve the full computational benefits of using a time‐domain numerical method, pulse excitation can be applied together with Fourier transformation of an output impulse response to yield frequency‐domain results over a wide bandwidth. The configuration of the mesh is the same as that used in FD–TD scattering simulations (i.e., separation of the simulation space into total and scattered field regions). To terminate the exterior boundaries of the mesh, absorbing boundary conditions are applied to absorb the outward travelling waves. The effect of the absorbing boundaries on both time‐ and frequency‐domain results is investigated. Frequency‐domain scattered far‐field patterns are presented for perfectly conducting square and circular cylinders illuminated by an incident plane wave (TM case). Forward and back scattering cross‐section results obtained from a single TLM simulation indicate both the accuracy and efficiency of the method for calculating frequency‐domain results over

ISSN:0894-3370    

DOI:10.1002/jnm.1660050204

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIn this paper, the method of transmission‐line modelling is used to determine the transient response of a lossy transmission line. Non‐linearity and frequency‐dependent parameters (RandG) can be included without undue difficulty. Several numerical examples are described and are compared with exact and/or experimental results. In all cases good agreements are obt

ISSN:0894-3370    

DOI:10.1002/jnm.1660050205

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA random flight model of linear transport processes in two spatial dimensions is considered and solved exactly in closed algebraic form. Its one‐dimensional version had been proposed by Taitel as a means to overcome the paradox of infinite speed of propagation within classical heat diffusion theory. The connection with hyperbolic diffusion theory is complemented here by deriving the discrete fluxes and their relaxation term. Moreover, such an approach circumvents the discretization of a continuum model for an intrinsically discrete process, when diffusion processes are to be solved numerically. Finite samples are treated by means of the reflection method. Some applications of these general results are mentione

ISSN:0894-3370    

DOI:10.1002/jnm.1660050206

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper reports the results of a study of an error parameter,m, which has been proposed as a measure for determining the effects on accuracy of the basic assumptions upon which TLM modelling of diffusion and heat flow has been founded. The nature of themparameter is studied in detail by using a two‐dimensional thermal diffusion problem. The use ofmin the implementation of automatic timestepping is discussed in a practical three‐dimensional engineering prob

ISSN:0894-3370    

DOI:10.1002/jnm.1660050207

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0894-3370    

DOI:10.1002/jnm.1660050208

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0894-3370    

DOI:10.1002/jnm.1660050201

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY