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Quasi-static Analysis (quasi-static + analysis)

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Engineering100%

Selected Abstracts

Quasi-static analysis of microstrip lines with variation of substrate thickness in transverse direction

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2003
S. Khoulji
Abstract This article is devoted to the analysis of microstrip lines printed on dielectric substrates with transversely varying thickness using the quasi-static approximation and the method of lines. Discretization lines of varying length, according to the layer thickness, are used and only the Laplace wave equation has to be solved. The numerical results presented herein permit the illustration of the effect of arbitrarily curved substrate interfaces along the transverse direction on the characteristics of the microstrip structures under consideration. The behavior of the per unit length parameters of these structures as a function of the shape of these substrates' cross section is studied in depth. Furthermore, the effects of the finite metallization thickness and losses are also investigated in detail. The results that are obtained are consistent with those published in the literature. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 194,205, 2003. [source]

Volume-dependent pressure loading and its influence on the stability of structures

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2003
T. Rumpel
Abstract Deformation-dependent pressure loading on solid structures is created by the interaction of gas with the deformable surface of a structure. Such fairly simple load models are valid for static and quasi-static analyses and they are a very efficient tool to represent the influence of gas on the behaviour of structures. Completing previous studies on the deformation dependence of the loading with the assumption of infinite gas volumes, the current contribution is focusing on the influence of modifications of the size and shape of a finite volume containing the gas in particular on the stability of structures. The linearization of the corresponding virtual work expression necessary for a Newton-type solution leads to additional terms for the volume dependence. Investigating these terms the conservativeness of the problem can be proven by the symmetry of the linearized form. The discretization with finite elements leads to standard stiffness matrix forms plus the so-called load stiffness matrices and a rank-one update for each enclosed volume part, if the loaded surface segments are identical with element surfaces. Some numerical examples show first the effectiveness of the approach and the necessity to take the corresponding terms in the variational expression and in the following linearization into account, and second the particular influence of this term on the stability of structures is shown with some specific examples. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Accurate and simple synthesis formulas for coplanar waveguides

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2008
Ali Akdagli
Abstract Simple and accurate closed-form formulas obtained by using a differential evolution algorithm are presented for the synthesis of coplanar waveguides (CPW). The results of the synthesis formulas proposed in this article are compared with those of the quasi-static analysis, the synthesis formulas reported by the other researchers and also the experimental works available in the literature. The accuracy of the proposed synthesis formulas is found to be better than 0.75% for 9256 CPWs samples. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008. [source]

Adaptive neuro-fuzzy models for the quasi-static analysis of microstrip line

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2008
Celal Yildiz
Abstract This article presents a new method based on adaptive neuro-fuzzy inference system (ANFIS) to calculate the effective permittivities and characteristic impedances of microstrip lines. The ANFIS is a fuzzy inference system (FIS) implemented in the framework of an adaptive fuzzy neural network. It has the advantages of expert knowledge of FISs and learning capability of artificial neural networks. A hybrid learning algorithm, which combines the least square method and the back propagation algorithm, is used to identify the parameters of ANFIS. The results of ANFIS are compared with the results of the experimental works, quasi-static methods, and a commercial electromagnetic simulator IE3D. There is very good agreement among the results of ANFIS models and quasi-static methods, IE3D, and experimental works. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1191,1196, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23322 [source]

A double-spiral resonator structure to realize left-handed material with lower resonant frequency

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2006
Hui Zhao
Abstract A double-spiral resonator (DSR) structure causing negative permeability is proposed in this paper, which combines the characteristics of split-ring resonator (SRR) and spiral to reduce the resonant frequency. Hence, such a DSR structure has a small unit-to-wavelength ratio in realizing the left-handed property, which behaves more like a material. A quasi-static analysis is given to make an equivalence of the DSR structure to a left-handed material (LHM). Simulation results show that such an LHM possesses a small loss. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 923,926, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21520 [source]