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In this paper, the hybrid implicit–explicit finite-difference time-domain (HIE-FDTD) algorithm for a two-dimensional (2D) TE wave is extended to a full three-dimensional (3D) wave. The weakly conditional stability is verified by numerical simulation results. Numerical formulations of the 3D HIE-FDTD method are presented and simulation results are compared to those using the conventional 3D finite-difference time-domain method. High computation efficiency is obtained by introducing an unequal space increment in different dimensions in the HIE-FDTD method. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2291–2294, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21898 [ABSTRACT FROM AUTHOR]

The potential for developing higher-order finite-difference time-domain (FDTD) schemes with reduced phase errors is investigated in the present paper. Using the classic (2,4) FDTD method as the basis of this study, electromagnetic wave propagation is accurately reproduced in the discretized space by replacing isotropic materials with modified, anisotropic in general, ones. The use of such artificial materials improves the simulation's precision significantly around a specific frequency, yet the overall error remains small at a considerably wide bandwidth; therefore, this algorithm can be useful for wideband problems as well. Additionally, it is shown that an even better single-frequency performance can be attained, when the modified materials are combined with systematically calculated spatial operators. Pursuing a more wideband enhancement of the (2,4) technique, a version realizing more accurate results at almost all frequencies that can be coupled in a staggered grid is derived. Furthermore, novel spatial operators are introduced, with the distinct feature of using extended stencils in more than one directions. It turns out that when such operators are incorporated, a scheme that combines the aforementioned features can be obtained. The theoretical findings of this investigation are verified in a sequence of numerical tests, involving free-space and guided-wave propagation, as well as the determination of a cavity's resonant frequencies. Copyright © 2004 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper shows the ability of a domain decomposition method with a Neumann-Neumann preconditioner to solve industrial and biomechanical problems. For a mid-size biomedical simulation involving soft tissues the results obtained by using this algorithm are comapred to those obtained by more classical methods. The present algorithm thus appears to be more reliable than standard iterative methods and more efficient than a direct method. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the analysis of nonpersistent CSMA-CD protocol by Tobagi [1] et al., matrix computation is required. Hence, the computation time and required memory size increase with the number of stations and, moreover, under heavy load, the results become inaccurate. This paper presents an analysis of a nonpersistent CSMA-CD in which the matrix computations are not used and the slot size can be chosen arbitrarily small. The proposed analysis method requires less computational time and memory size. The analytical result for the performance under heavy load agrees well with the simulation result. [ABSTRACT FROM AUTHOR]

The use of micromechanically based constitutive equations for contact interfaces leads to technically relevant parameters to ill-conditioned finite-element equations. In the paper an augmented Lagrangian technique is employed to overcome this difficulty and to provide a good converging algorithm. [ABSTRACT FROM AUTHOR]

In this paper, three-dimensional optical computerized tomography in the case of severely incomplete projection data is discussed theoretically and experimentally. An orthogonal projection method has been proposed for optical tomography in the case of severely incomplete data. Some comparative numerical simulations and experimental results of traditional sampling method and the new method are given. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 57–59, 2001. [ABSTRACT FROM AUTHOR]

Co-simulation is a simulation technique for time dependent coupled problems in engineering that restricts the data exchange between subsystems to discrete communication points in time. In the present paper we follow the block-oriented framework in the recently established industrial interface standard FMI for Model Exchange and Co-Simulation v2.0 and study local and global error of co-simulation algorithms for systems with force-displacement coupling. A rather general convergence result for the co-simulation of coupled systems without algebraic loops shows zero-stability of co-simulation algorithms with force-displacement coupling and proves that order reduction of local errors does not affect the order of global errors. The theoretical investigations are illustrated by numerical tests in the novel FMI-compatible co-simulation environment SNiMoWrapper. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]