bluuebunny/crossref_metadata_2025_split huggingface dataset:
Difference schemes for the class of singularly perturbed boundary value problems
Authors: Rafatov Ismail R. , Sklyar Sergey N. 
Published: March 2004

AbstractThis work deals with the construction of difference schemes for the numerical solution of singularly perturbed boundary value problems, which appear while solving heat transfer equations with spherical symmetry. The projective version of integral interpolation (PVIIM) method is used. Derived schemes allow to approximate the solution of the problem and the derivatives of the solution at the same time. Moreover, they allow to approximate the boundary conditions of general form in the framework of the same method. New schemes are tested in order to compare them with well known difference schemes. Estimates for rates of classical and uniform convergence are carried out. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimally Controlled Dynamics of One Dimensional Harmonic Oscillator: Linear Dipole Function and Quadratic Penalty
Authors: Tunga Burcu , Demiralp Metin 
Published: March 2004

AbstractThis work deals with the optimal control of one dimensional quantum harmonic oscillator under an external field characterized by a linear dipole function. The penalty term is taken as kinetic energy. The objective operator whose expectation value is desired to get a prescribed target value is taken as the square of the position operator. The dipole function hypothesis in the external field is valid only for weak fields otherwise hyperpolarizability terms which contain powers of the field amplitude higher than 1 should be considered. The weak field assumption enables us to develop a first order perturbation approach to get approximate solutions to the wave and costate equations. These solutions contain the field amplitude and another unknown, so‐called deviation constant, through some certain integrals. By inserting these expressions into the connection equation which functionally relates the field amplitude to the wave and costate function it is possible to produce an integral equation. Same manipulations on the objective equation results in an algebraic equation to determine the deviation parameter. The algebraic deviation equation produces incompatibility which can be relaxed by including second order perturbative term of wave function. The integral and algebraic equations mentioned above are asymptotically solved. Their global solutions are left to future works since the main purpose of this work is to obtain the so‐called field and deviation equations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weighted Eigenvalue Problem Approach To The Critical Value Determination Of Screened Coulomb Potential Systems
Authors: Demiralp Metin 
Published: March 2004

AbstractIn this work, the radial time‐independent Schrödinger equation of a screened Coulomb potential system at the zero energy limit is first converted to a weighted eigenvalue problem of an ordinary differential operator. Then, by using an appropriate coordinate transformation, the differential equation is transformed into a form whose first and second order derivative related terms become same as the Extended Jacobi Polynomials' differential equation's corresponding terms. Only difference is the appearance of a multiplicative operator which can be considered as an effective potential. Work focuses on the point whether the solution is obtained easily depending on the structure of this potential. In this direction a screened Coulomb potential with a specific rational screening function is considered. The analytical solutions for the critical values of the screening parameter and the form of the wave function at the threshold of the continous spectrum are obtained. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal Control of One Dimensional Quantum Harmonic Oscillator Under an External Field With Quadratic Dipole Function and Penalty on Momentum: Construction of the Linearised Field Amplitude Integral Equation
Authors: Kurşunlu A. , Yaman İrem , Demiralp Metin 
Published: March 2004

AbstractIn this work, the optimal control of an harmonic oscillator is considered. The external field is assumed to be weak and hence is represented by only dipole interaction. The dipole function is taken as a second degree polynomial in spatial coordinate. The objective term is composed of the expectation value of algebraic position operator. Penalty term related operator is taken as momentum. Some specific structures for spatial dependence is assumed and temporal equations are obtained for unknowns. The equations represent forward and backward evolution. The connection is provided by an algebraic equation coming from field amplitude related equation. The key unknown is the field amplitude since its determination leads us to evaluate all unknowns without remarkable difficulty. The purpose is not to determine field amplitude at the most general case but to construct an equation which involves this unknown only. The equation obtained via the linearisation of the field amplitude dependence is shown to be a linear integral equation. We do not attempt to solve it but discuss how to use appropriate methods for the solution. The equation is analytically solved at the zero interaction time limit. The real comprehensive implementation is left for future work. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High Dimensional Model Representation Approximation of an Evolution Operator with a First Order Partial Differential Operator Argument
Authors: Yaman İrem , Demiralp Metin 
Published: March 2004

AbstractIn this work, a novel approximation scheme based on a recently developed representation, called the High Dimensional Model Representation (HDMR), is proposed to approximate evolution operators. The approximation is not developed at the operator level, instead the effect of the operator on an arbitrary function is approximated. The purpose of the work is to investigate how HDMR can be applied for the approximation of evolution operator and its efficiency. Although the approximation can be constructed for any order of multivariance, only the constant and univariate components of HDMR are considered in this work. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Comparison of the Model Order Reduction Techniques for Linear Systems Arising from VLSI Interconnection Simulation
Authors: Fatih Yetkin E. , DAĞ Hasan 
Published: March 2004

AbstractIn recent years, model order reduction scheme for reducing the dimension of linear systems has become very popular for computer aided design of the systems. In this paper, we analyze the existent methods of the model order reduction techniques used in Very Large Scale Integrated (VLSI) circuit interconnection modelling in terms of numerical stability, computational speed and accuracy. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spline Based Electronic Modelling
Authors: Senthilbalaji Girimurugan L. 
Published: March 2004

Abstract“Without Mathematics almost everything is zilch”, a scientific maxim, is the kernel for this mathematical piece of research. The basic notion is to formulate mathematical models for devices and circuits deployed in state of the art electronic gadgets. The article searches for a tool to perform the aforementioned operation and finally accouters its models with well known mathematical approximation tools called Interpolators. The analysis of these models is carried out using MATLAB and the simulations are obtained for both frequency dependent and independent device characteristics. The scheme could result in some predicted merits when it allies with Very Large Scale and Ultra Large Scale Integration [VLSI,ULSI] techniques employed in the Electronic chip design industry and Artificial Intelligence. The quondam alliance could result in device miniaturization and the latter may result in the design of robots enabled in the control of electronic environments. However, the latter could be an application [for Robots] or an alliance where the principles of neural networks could be applied for the purpose of mathematical modelling. Thus, the article reveals a solution for how mathematics be applied to engineering and science. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability conditions for the Leapfrog‐Euler scheme with central spatial discretization of any order
Authors: Shishkina Olga , Wagner Claus 
Published: March 2004

AbstractIn this paper a sufficient condition (Theorem 2.3) for the von Neumann stability of the Leapfrog‐Euler scheme, which uses central spatial discretization of any order for 3D convection‐diffusion equation, is derived in terms of the Courant and the diffusion numbers and the coefficients of approximation schemes. In the case of the second order differencing this condition becomes the necessary condition for the stability. Some particular sufficient conditions for the stability of the second and the fourth order schemes are also derived. A comparison of the results, which were obtained applying the derived stability conditions to compute the time step in the direct numerical simulations (DNS) of turbulent pipe flow with the help of the second and the fourth order schemes, is presented. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improving Rates of Convergence of Iterative Schemes for Implicit Runge‐Kutta Methods
Authors: Vigneswaran R. 
Published: March 2004

AbstractVarious iterative schemes have been proposed to solve the non‐linear equations arising in the implementation of implicit Runge‐Kutta methods. In one scheme, when applied to an s‐stage Runge‐Kutta method, each step of the iteration still requires s function evaluations but consists of r(>s) sub‐steps. Improved convergence rate was obtained for the case r = s + 1 only. This scheme is investigated here for the case r = ks, k = 2, 3, …, and superlinear convergence is obtained in the limit k→∞. Some results are obtained for Gauss methods and numerical results are given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A compensation method based on recursive processing of nonlinear distortion for OFDM
Authors: Hosono Hiroyuki , Hosokawa Taisuke , Maeda Tsuyoshi , Maehara Fumiaki , Takahata Fumio 
Published: March 2004

AbstractOFDM (orthogonal frequency division multiplexing) signal generates a very large signal amplitude. Consequently, distortion due to nonlinearity is produced when the signal is amplified through a nonlinear amplifier, which greatly degrades BER (bit‐error rate) performance. As a method of handling this problem, this paper proposes highly accurate compensation processing of nonlinear distortion by constructing a replica of the OFDM signal in the receiver. The proposed method is based on the hard decision result of demodulated received symbols containing nonlinear distortion, and the nonlinear distortion component is recursively estimated and compensated. The performance of the proposed method is evaluated by computer simulation assuming a thermal noise environment, and it is shown that the proposed method is better in both BER and the number of constructed replicas. The performance of the proposed method is also evaluated assuming a fading environment when the method is applied to land mobile communications. The problems of fading compensation when the distortion caused by nonlinear amplification is superposed are pointed out. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(7): 55–65, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10051
A dynamic server selection method using QoS statistics
Authors: Mase Kenichi , Kuribayashi Takayuki , Tsuno Akihiko 
Published: March 2004

AbstractIn this paper, we study server selection methods from the perspective of selecting the server having the shortest download time when a file is downloaded from a mirror Web site. Specifically, we focus on server selection methods on the client side and propose a dynamic server selection method based on Quality of Service (QoS) statistical data. This method features using past stored data in a more advanced manner than a conventional server selection method by collecting past QoS data according to the day of the week and the time period. We also study and evaluate the method based on experimental results using the Internet. First, we study the optimum values for the parameters of the proposed server selection method. Then we compare and evaluate this server selection method and an existing server selection method. As the evaluation metrics, in addition to objective evaluation indices such as the mean and maximum download time, we use the download give‐up rate and the stress level which reflect the user's feelings. Based on these results, we demonstrate the superiority of this server selection method. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(7): 43–54, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10168
Frequency efficiency by introducing adaptive array antenna in W‐CDMA system
Authors: Mikami Manabu , Fujii Teruya 
Published: March 2004

AbstractThe adaptive array antenna is an effective means of improving frequency efficiency in cellular mobile communication systems. In these systems, the frequency efficiency is generally improved by improving the CIR characteristic. This paper considers W‐CDMA systems from such a viewpoint, assuming that an adaptive array antenna is used in the wireless base station. The relation between the array antenna structure (the number and directivity of antenna elements) and the frequency efficiency is analyzed by examining the improvement of the CIR characteristic in a cellular environment containing multiple cells. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(7): 31–42, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10176
Planar array antenna using both‐sided MIC's feeder circuits
Authors: Egashira Kozo , Nishiyama Eisuke , Aikawa Masayoshi 
Published: March 2004

AbstractIn this paper, it is proposed that the “both‐sided” circuit technique, which consists of placing several types of transmission lines on both sides of the dielectric substrate, be used for array antenna feed systems. Microstrip lines are used on the front surface of the dielectric substrate, and slot lines are placed on the back side. By means of electromagnetic coupling, a new feed system is constructed. Further, trial fabrication and testing of a four‐element array antenna using this feed system were carried out. The measured radiation patterns indicate complementary effects caused by feeding of the radiating elements with mirror symmetry. Excellent characteristics substantially reducing unwanted cross‐polarization are confirmed. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(7): 23–30, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10179
FDTD analysis of the transmission/radiation characteristics of 90° bent transmission lines
Authors: Shiokawa Takayasu 
Published: March 2004

AbstractRecently, with the advent of personal high‐performance electronic devices such as computers and with proliferation of mobile communications such as cellular phones, reduction of the size and weight of the systems, enhancement of processing speed, and voltage reduction of the electronic devices have been pursued. As a result, the problems of interference by unwanted electromagnetic waves between various devices and within individual devices have appeared. Various approaches are conceivable. The author has been performing research on these problems from the standpoint that the electromagnetic elucidation of the generation and propagation mechanisms of the unwanted waves is essential. In the present paper, the voltage and current distributions on a parallel two‐wire line with a bend, representing the basic configuration of a transmission line, are analyzed by the FDTD method. By using this analysis, the complex power near the bend is derived and the transmission/radiation characteristics at the bend are quantitatively elucidated. Next, the transmission/radiation characteristics of a microstrip line with a 90°bend are analyzed by the FDTD method in the case where an adjacent line exists. In this way, the effect of the adjacent line is elucidated. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(7): 11–22, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10190
Output equivalent circuit model of digital IC for estimating emissions radiated from signal trace
Authors: Miyazaki Chiharu , Oka Naoto , Uchida Takeshi , Tokuda Masamitsu , Nitta Shuichi 
Published: March 2004

AbstractThe output model of a digital IC for calculating normal‐mode emissions radiated from a signal trace was studied. It is confirmed that the difference of kinds and manufacturers of various digital ICs can be found by measuring normal‐mode radiations from a signal trace driven by a digital IC such as TTL or CMOS. In order to calculate the difference of normal‐mode emissions, it is proposed that the output equivalent circuit of the digital IC be modeled as a circuit consisting of a voltage source and an output resistor, and a method of obtaining them is presented. The validity of the output model of the digital IC is confirmed by the fact that the results of calculation using the output model of a digital IC agree very well with measured data. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(7): 1–10, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10199
Evaluation for a multicast extension of a label switching technology
Authors: Nagami Kenichi , Mitsuzawa Shigeo , Mogi Akiyoshi , Ise Kotaro , Katsube Yasuhiro , Esaki Hiroshi 
Published: March 2004

AbstractThe LSR (label switch router), which uses label switching technology, performs packet transmission by a label transmission module that uses fixed‐length labels, in addition to by an ordinary network transmission module. It realizes high‐speed and high‐performance packet transmission by making correspondence with IP packets and fixed‐length labels, and by transmitting them using the label transmission module. The basic part of unicast label distribution protocol used by LSR has been specified by IETF (Internet Engineering Task Force). As for multicast label switching technology, various protocols (FANP [5], TAG [7], IPSOFACT [11]) have been proposed, and they have been compared by Ooms and colleagues [13]. However, there has been no study that evaluated the effectiveness of multicast label switching technology by comparing two cases, one that uses label switching technology for multicast packet transmission and another that does not. In this article, we evaluate the effectiveness of multicast label switching technology by designing and implementing FANP, a protocol for multicast label switching, by measuring LSP setup time, which is overhead of LSR compared with ordinary routers, and by measuring throughput for the case with label switching technology and for the case without it. LSP setup time was about 40 ms per LSR, which shows that overhead of label switching technology is small. Also, we verified that the throughput is higher when we used the label switching technology than when we did not use it, and it is effective in routers that reproduce multicast packets, such as backbone routers with many multicast receivers. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(7): 66–74, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1189
A systematic comparison of coupled and distributive smoothing in multigrid for the poroelasticity system
Authors: Gaspar F. J. , Lisbona F. J. , Oosterlee C. W. , Wienands R. 
Published: March 2004

AbstractIn this paper, we present efficient multigrid methods for the system of poroelasticity equations discretized on a staggered grid. In particular, we compare two different smoothing approaches with respect to efficiency and robustness. One approach is based on the coupled relaxation philosophy. We introduce ‘cell‐wise’ and ‘line‐wise’ versions of the coupled smoothers. They are compared with a distributive relaxation, that gives us a decoupled system of equations. It can be smoothed equation‐wise with basic iterative methods. All smoothing methods are evaluated for the same poroelasticity test problems in which parameters, like the time step, or the Lamé coefficients are varied. Some highly efficient methods result, as is confirmed by the numerical experiments. Copyright © 2004 John Wiley & Sons, Ltd.
A robust multilevel approach for minimizing H(div)‐dominated functionals in an H1‐conforming finite element space
Authors: Austin Travis M. , Manteuffel Thomas A. , McCormick Steve 
Published: March 2004

AbstractThe standard multigrid algorithm is widely known to yield optimal convergence whenever all high‐frequency error components correspond to large relative eigenvalues. This property guarantees that smoothers like Gauss–Seidel and Jacobi will significantly dampen all the high‐frequency error components, and thus, produce a smooth error. This has been established for matrices generated from standard discretizations of most elliptic equations. In this paper, we address a system of equations that is generated from a perturbation of the non‐elliptic operator I‐grad div by a negative ε Δ. For εnear to one, this operator is elliptic, but as εapproaches zero, the operator becomes non‐elliptic as it is dominated by its non‐elliptic part. Previous research on the non‐elliptic part has revealed that discretizing I‐grad div with the proper finite element space allows one to define a robust geometric multigrid algorithm. The robustness of the multigrid algorithm depends on a relaxation operator that yields a smooth error. We use this research to assist in developing a robust discretization and solution method for the perturbed problem. To this end, we introduce a new finite element space for tensor product meshes that is used in the discretization, and a relaxation operator that succeeds in dampening all high‐frequency error components. The success of the corresponding multigrid algorithm is first demonstrated by numerical results that quantitatively imply convergence for any εis bounded by the convergence for εequal to zero. Then we prove that convergence of this multigrid algorithm for the case of ε equal to zero is independent of mesh size. Copyright © 2004 John Wiley & Sons, Ltd.
Algebraic multigrid methods for constrained linear systems with applications to contact problems in solid mechanics
Authors: Adams Mark F. 
Published: March 2004

AbstractThis paper develops a general framework for applying algebraic multigrid techniques to constrained systems of linear algebraic equations that arise in applications with discretized PDEs. We discuss constraint coarsening strategies for constructing multigrid coarse grid spaces and several classes of multigrid smoothers for these systems. The potential of these methods is investigated with their application to contact problems in solid mechanics. Published in 2004 by John Wiley & Sons, Ltd.
Cache aware multigrid for variable coefficient elliptic problems on adaptive mesh refinement hierarchies
Authors: Douglas C. C. , Hu J. , Ray J. , Thorne D. T. , Tuminaro R. S. 
Published: March 2004

AbstractWe derive a multilevel algorithm to solve variable coefficient elliptic boundary value problems on adaptively refined structured meshes, and we design a cache optimized version of this algorithm.The operations are optimized to exploit the cache memory subsystem. We present numerical results demonstrating the efficiency of the cache optimization. Copyright © 2004 John Wiley & Sons, Ltd.