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Transform Domain (transform + domain)

Distribution by Scientific Domains

Engineering	66%

Selected Abstracts

The one-level functional equation of multi-rate loss systems

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 2 2003
Harro L. Hartmann
Motivated by the discrete multi-rate Kaufmann,Roberts recurrence relations, we derive a functional equation (FE), which covers nonintegral states. This FE implies a unique effective step parameter d, which defines an equivalent one-level recurrence depth, or bit-rate, at each state under progress. This state-dependent depth results from the equality requirement of the multi-rate and the one-level model in the moment-generating function transform domain. By this method it is possible to model d by a few moments of the original multi-rate statistic. In this case we obtain an explicit FE solution covering the entire (global) state space. Next we verify that the resulting state probability density incorporates iteratively enumerated discrete state probabilities, including the state-dependent depth. With a system capacity C the iterations then need time complexities between O(C) and O(C2). In contrast to this each FE state, is performed at a time complexity O(1). By the efficient coverage of the whole state space, fast optimizations of multi-rate networks and multi-resource systems can be improved. Copyright © 2003 AEI. [source]

The fundamental solution of poroelastic plate saturated by fluid and its applications

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2010
P. H. Wen
Abstract In this paper, the numerical model of the transverse vibrations of a thin poroelastic plate saturated by a fluid was proposed. Two coupled dynamic equations of equilibrium related to the plate deflection and the equivalent moment were established for an isotropic porous medium with uniform porosity. The fundamental solutions for a porous plate were derived both in the Laplace transform domain and in the time domain. A meshless method was developed and demonstrated in the Laplace transform domain for solving two coupled dynamic equations. Numerical examples demonstrated the accuracy of the method of the fundamental solutions and comparisons were made with analytical solutions. The proposed meshless method was shown to be simple to implement and gave satisfactory results for a poroelastic plate dynamic analysis. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Vector Hankel transform analysis of a tunable circular microstrip patch

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 5 2005
T. Fortaki
Abstract In this paper, a rigorous analysis of the tunable circular microstrip patch is performed using a dyadic Green's function formulation. To make the theoretical formulation more general and hence valid for various antennas structures (not only limited to tunable microstrip patch); the dyadic Green's function is derived when the patch is assumed to be embedded in a multilayered dielectric substrate. A very efficient technique to derive the dyadic Green's function in the vector Hankel transform domain is proposed. Using the vector Hankel transform, the mixed boundary value problem is reduced to a set of vector dual integral equations. Galerkin's method is then applied to solve the integral equation where two sets of disk current expansions are used. One set is based on the complete set of orthogonal modes of the magnetic cavity, and the other consists of combinations of Chebyshev polynomials with weighting factors to incorporate the edge condition. Convergent results for these two sets of disk current expansions are obtained with a small number of basis functions. The calculated resonant frequencies and quality factors are compared with experimental data and shown to be in good agreement. Finally, numerical results for the air gap tuning effect on the resonant frequency and half-power bandwidth are also presented. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Steady/unsteady aerodynamic analysis of wings at subsonic, sonic and supersonic Mach numbers using a 3D panel method

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10 2003
Jeonghyun Cho
Abstract This paper treats the kernel function of an integral equation that relates a known or prescribed upwash distribution to an unknown lift distribution for a finite wing. The pressure kernel functions of the singular integral equation are summarized for all speed range in the Laplace transform domain. The sonic kernel function has been reduced to a form, which can be conveniently evaluated as a finite limit from both the subsonic and supersonic sides when the Mach number tends to one. Several examples are solved including rectangular wings, swept wings, a supersonic transport wing and a harmonically oscillating wing. Present results are given with other numerical data, showing continuous results through the unit Mach number. Computed results are in good agreement with other numerical results. Copyright © 2003 John Wiley & Sons, Ltd. [source]

On holographic transform compression of images

INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 5 2000
Alfred M. Bruckstein
Abstract Lossy transform compression of images is successful and widespread. The JPEG standard uses the discrete cosine transform on blocks of the image and a bit allocation process that takes advantage of the uneven energy distribution in the transform domain. For most images, 10:1 compression ratios can be achieved with no visible degradations. However, suppose that multiple versions of the compressed image exist in a distributed environment such as the internet, and several of them could be made available upon request. The classical approach would provide no improvement in the image quality if more than one version of the compressed image became available. In this paper, we propose a method, based on multiple description scalar quantization, that yields decompressed image quality that improves with the number of compressed versions available. © 2001 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 11, 292,314, 2000 [source]

z -Transform and adaptive signal processing in analysis of tracer data

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2002
Leszek Furman
Abstract In the field of data processing, the common practice is to interpret tracer-determined residence time distributions (RTDs) of particles through different arrangements of elementary flow models. However, such analysis needs an a priori chosen arrangement of these models, and some information carried by the RTD curve may be lost. This paper presents a competitive method based on adaptive filtering in a z -transform domain, and it may give better insight into flow patterns in a steady-state flow system. A physical interpretation of the transfer function was developed. The application of this modelling to the interpretation of radiotracer data from recent studies in different industry sectors is presented. Dans le domaine du traitement des données, la pratique courante consiste à interpréter les distributions de temps de séjour (DTS) déterminées par traceur de particules à travers différents arrangements de modèles d'écoulements élémentaires. Toutefois, une telle analyse implique de choisir a priori l'arrangement de ces modèles. Ainsi, certaines informations données par la courbe de DTS peuvent se perdre. On présente dans cet article une méthode compétitive basée sur le filtrage adaptatif dans le domaine de la transformée en z, qui peut permettre une meilleure compréhension des schémas d'écoulement pour un système en écoulement permanent. Une interprétation physique de la fonction de transfert a été développée. On présente l'application de cette modélisation de l'interprétation des données de traceurs radioactifs provenant d'études récentes dans différents secteurs industriels. [source]