http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Thu, 23 May 2013 15:52:10 +0000 http://www.hindawi.com/isrn/cm/2013/602579/ The notion of asymptotically regular mapping in partial metric spaces is introduced, and a fixed point result for the mappings of this class is proved. Examples show that there are cases when new results can be applied, while old ones (in metric space) cannot. Some common fixed point theorems for sequence of mappings in partial metric spaces are also proved which generalize and improve some known results in partial metric spaces. Satish Shukla, Ishak Altun, and Ravindra Sen Copyright © 2013 Satish Shukla et al. All rights reserved. Thu, 28 Mar 2013 09:13:00 +0000 http://www.hindawi.com/isrn/cm/2013/617475/ IRT models are widely used but often rely on distributional assumptions about the latent variable. For a simple class of IRT models, the Rasch models, conditional inference is feasible. This enables consistent estimation of item parameters without reference to the distribution of the latent variable in the population. Traditionally, specialized software has been needed for this, but conditional maximum likelihood estimation can be done using standard software for fitting generalized linear models. This paper describes an SAS macro %rasch_cml that fits polytomous Rasch models. The macro estimates item parameters using conditional maximum likelihood (CML) estimation and person locations using maximum likelihood estimator (MLE) and Warm's weighted likelihood estimation (WLE). Graphical presentations are included: plots of item characteristic curves (ICCs), and a graphical goodness-of-fit-test is also produced. Karl Bang Christensen Copyright © 2013 Karl Bang Christensen. All rights reserved. Thu, 21 Mar 2013 14:01:16 +0000 http://www.hindawi.com/isrn/cm/2013/352806/ We discuss computation of Gröbner bases using approximate arithmetic for coefficients. We show how certain considerations of tolerance, corresponding roughly to absolute and relative error from numeric computation, allow us to obtain good approximate solutions to problems that are overdetermined. We provide examples of solving overdetermined systems of polynomial equations. As a secondary feature we show handling of approximate polynomial GCD computations, using benchmarks from the literature. Daniel Lichtblau Copyright © 2013 Daniel Lichtblau. All rights reserved. Thu, 21 Feb 2013 09:24:24 +0000 http://www.hindawi.com/isrn/cm/2013/262863/ We introduce an effective methodology for solving a class of linear as well as nonlinear singular two-point boundary value problems. This methodology is based on a modification of Adomian decomposition method (ADM) and a new two fold integral operator. We use all the boundary conditions to derive an integral equation before establishing the recursive scheme for the solution components of solution. Thus, we develop modified recursive scheme without any undetermined coefficients while computing the successive solution components. This modification also avoids solving a sequence of nonlinear algebraic or transcendental equations for the undetermined coefficients. However, most of earlier recursive schemes using ADM do require computation of undetermined coefficients. The approximate solution is obtained in the form of series with easily calculable components. Numerical examples are included to demonstrate the accuracy, applicability, and generality of the present technique. The results reveal that the method is very effective, straightforward, and simple. Randhir Singh and Jitendra Kumar Copyright © 2013 Randhir Singh and Jitendra Kumar. All rights reserved. Wed, 20 Feb 2013 11:32:44 +0000 http://www.hindawi.com/isrn/cm/2013/765408/ The present paper is concerned to analyze the influence of the unsteady free convection flow of a viscous incompressible fluid through a porous medium with high porosity bounded by a vertical infinite moving plate in the presence of thermal radiation, heat generation, and chemical reaction. The fluid is considered to be gray, absorbing, and emitting but nonscattering medium, and Rosseland approximation is considered to describe the radiative heat flux in the energy equation. The dimensionless governing equations for this investigation are solved analytically using perturbation technique. The effects of various governing parameters on the velocity, temperature, concentration, skin-friction coefficient, Nusselt number and Sherwood number are shown in figures and tables and analyzed in detail. S. Mohammed Ibrahim Copyright © 2013 S. Mohammed Ibrahim. All rights reserved. Mon, 18 Feb 2013 09:34:18 +0000 http://www.hindawi.com/isrn/cm/2013/435261/ We find some new explicit values of the parameters and of quotients of eta-function by using Ramanujan's class invariants. Nipen Saikia Copyright © 2013 Nipen Saikia. All rights reserved. Thu, 17 Jan 2013 15:46:24 +0000 http://www.hindawi.com/isrn/cm/2013/931019/ Density-based clustering methods are known to be robust against outliers in data; however, they are sensitive to user-specified parameters, the selection of which is not trivial. Moreover, relational data clustering is an area that has received considerably less attention than object data clustering. In this paper, two approaches to robust density-based clustering for relational data using evolutionary computation are investigated. Amit Banerjee Copyright © 2013 Amit Banerjee. All rights reserved. Mon, 31 Dec 2012 17:32:07 +0000 http://www.hindawi.com/isrn/cm/2012/947634/ This paper is an improvement over the previous work on New Sorting Algorithm first proposed by Sundararajan and Chakraborty (2007). Here we have taken the pivot element as the middle element of the array. We call this improved version Middle Pivot Element Algorithm (MPA) and it is found that MPA is much faster than the two algorithms RPA (Random Pivot element Algorithm) and FPA (First Pivot element Algorithm) in which the pivot element was selected either randomly or as the first element, respectively. Anchala Kumari and Soubhik Chakraborty Copyright © 2012 Anchala Kumari and Soubhik Chakraborty. All rights reserved. Wed, 12 Dec 2012 15:40:00 +0000 http://www.hindawi.com/isrn/cm/2012/264040/ Item response theory (IRT) is a popular approach used for addressing statistical problems in psychometrics as well as in other fields. The fully Bayesian approach for estimating IRT models is computationally expensive. This limits the use of the procedure in real applications. In an effort to reduce the execution time, a previous study shows that high performance computing provides a solution by achieving a considerable speedup via the use of multiple processors. Given the high data dependencies in a single Markov chain for IRT models, it is not possible to avoid communication overhead among processors. This study is to reduce communication overhead via the use of a row-wise decomposition scheme. The results suggest that the proposed approach increased the speedup and the efficiency for each implementation while minimizing the cost and the total overhead. This further sheds light on developing high performance Gibbs samplers for more complicated IRT models. Yanyan Sheng and Mona Rahimi Copyright © 2012 Yanyan Sheng and Mona Rahimi. All rights reserved. Wed, 14 Nov 2012 09:23:22 +0000 http://www.hindawi.com/isrn/cm/2012/924839/ A new 5-point ternary interpolating scheme with a shape parameter is introduced. The resulting curve is for a certain range of parameters. The differentiable properties of the proposed scheme to extend its application in the generation of smooth curves are explored. Application of the proposed scheme is given to show its visual smoothness. The scheme is also extended to a 5-point tensor product ternary interpolating scheme, and its numerical examples are also included. Ghulam Mustafa, Jayyada Irum, and Mehwish Bari Copyright © 2012 Ghulam Mustafa et al. All rights reserved. Mon, 05 Nov 2012 09:45:53 +0000 http://www.hindawi.com/isrn/cm/2012/171606/ This paper addresses the problem of global asymptotic stability of a class of uncertain discrete-time state-delayed systems employing generalized overflow nonlinearities. The systems under investigation involve parameter uncertainties that are assumed to be deterministic and norm bounded. A new computationally tractable delay-dependent criterion for global asymptotic stability of such systems is presented. A numerical example is given to illustrate the effectiveness of the proposed method. V. Krishna Rao Kandanvli and Haranath Kar Copyright © 2012 V. Krishna Rao Kandanvli and Haranath Kar. All rights reserved. Sun, 16 Sep 2012 11:45:36 +0000 http://www.hindawi.com/isrn/cm/2012/103509/ Many network monitoring applications and performance analysis tools are based on the study of an aggregate measure of network traffic, for example, number of packets in transit (NPT). The simulation modeling and analysis of this type of performance indicator enables a theoretical investigation of the underlying complex system through different combination of network setups such as routing algorithms, network source loads or network topologies. To detect stationary increase of network source load, we propose a dynamic principal component analysis (PCA) method, first to extract data features and then to detect a stationary load increase. The proposed detection schemes are based on either the major or the minor principal components of network traffic data. To demonstrate the applications of the proposed method, we first applied them to some synthetic data and then to network traffic data simulated from the packet switching network (PSN) model. The proposed detection schemes, based on dynamic PCA, show enhanced performance in detecting an increase of network load for the simulated network traffic data. These results show usefulness of a new feature extraction method based on dynamic PCA that creates additional feature variables for event detection in a univariate time series. Shengkun Xie and Anna T. Lawniczak Copyright © 2012 Shengkun Xie and Anna T. Lawniczak. All rights reserved. Thu, 13 Sep 2012 17:20:55 +0000 http://www.hindawi.com/isrn/cm/2012/671423/ Many optimization problems (from academia or industry) require the use of a local search to find a satisfying solution in a reasonable amount of time, even if the optimality is not guaranteed. Usually, local search algorithms operate in a search space which contains complete solutions (feasible or not) to the problem. In contrast, in Consistent Neighborhood Search (CNS), after each variable assignment, the conflicting variables are deleted to keep the partial solution feasible, and the search can stop when all the variables have a value. In this paper, we formally propose a new heuristic solution method, CNS, which has a search behavior between exhaustive tree search and local search working with complete solutions. We then discuss, with a unified view, the great success of some existing heuristics, which can however be considered within the CNS framework, in various fields: graph coloring, frequency assignment in telecommunication networks, vehicle fleet management with maintenance constraints, and satellite range scheduling. Moreover, some lessons are given in order to have guidelines for the adaptation of CNS to other problems. Michel Vasquez and Nicolas Zufferey Copyright © 2012 Michel Vasquez and Nicolas Zufferey. All rights reserved. Wed, 05 Sep 2012 15:43:52 +0000 http://www.hindawi.com/isrn/cm/2012/704184/ The main objective of this paper is to examine the stability and convergence of the Laplace-Adomian algorithm to approximate solutions of the pantograph-type differential equations with multiple delays. This is done by comparatively investigating it with other methods. Sabir Widatalla Copyright © 2012 Sabir Widatalla. All rights reserved. Tue, 04 Sep 2012 09:40:10 +0000 http://www.hindawi.com/isrn/cm/2012/423469/ Analytical and numerical solutions are obtained for coupled nonlinear partial differential equation by the well-known Laplace decomposition method. We combined Laplace transform and Adomain decomposition method and present a new approach for solving coupled Schrödinger-Korteweg-de Vries (Sch-KdV) equation. The method does not need linearization, weak nonlinearity assumptions, or perturbation theory. We compared the numerical solutions with corresponding analytical solutions. Arun Kumar and Ram Dayal Pankaj Copyright © 2012 Arun Kumar and Ram Dayal Pankaj. All rights reserved. Tue, 14 Aug 2012 09:09:31 +0000 http://www.hindawi.com/isrn/cm/2012/169050/ We define a new parameter 𝐼𝑘,𝑛 involving quotient of Ramanujan's function 𝜒(𝑞) for positive real numbers 𝑘 and 𝑛 and study its several properties. We prove some general theorems for the explicit evaluations of the parameter 𝐼𝑘,𝑛 and find many explicit values. Some values of 𝐼𝑘,𝑛 are then used to find some new and known values of Ramanujan's class invariant 𝐺𝑛. Nipen Saikia Copyright © 2012 Nipen Saikia. All rights reserved. Mon, 13 Aug 2012 09:38:44 +0000 http://www.hindawi.com/isrn/cm/2012/603280/ We introduce a new hybrid of the Laplace transform method and new homotopy perturbation method (LTNHPM) that efficiently solves nonlinear two-dimensional Burgers’ equation. Three examples are given to demonstrate the efficiency of the new method. Hossein Aminikhah Copyright © 2012 Hossein Aminikhah. All rights reserved. Sun, 29 Jul 2012 14:02:32 +0000 http://www.hindawi.com/isrn/cm/2012/197352/ We introduce multiscale wavelet kernels to kernel principal component analysis (KPCA) to narrow down the search of parameters required in the calculation of a kernel matrix. This new methodology incorporates multiscale methods into KPCA for transforming multiscale data. In order to illustrate application of our proposed method and to investigate the robustness of the wavelet kernel in KPCA under different levels of the signal to noise ratio and different types of wavelet kernel, we study a set of two-class clustered simulation data. We show that WKPCA is an effective feature extraction method for transforming a variety of multidimensional clustered data into data with a higher level of linearity among the data attributes. That brings an improvement in the accuracy of simple linear classifiers. Based on the analysis of the simulation data sets, we observe that multiscale translation invariant wavelet kernels for KPCA has an enhanced performance in feature extraction. The application of the proposed method to real data is also addressed. Shengkun Xie, Anna T. Lawniczak, Sridhar Krishnan, and Pietro Lio Copyright © 2012 Shengkun Xie et al. All rights reserved. Mon, 28 May 2012 15:14:24 +0000 http://www.hindawi.com/isrn/cm/2012/340415/ Estimating linear-by-linear association has long been an important topic in the analysis of contingency tables. For ordinal variables, log-linear models may be used to detect the strength and magnitude of the association between such variables, and iterative procedures are traditionally used. Recently, studies have shown, by way of example, three non-iterative techniques can be used to quickly and accurately estimate the parameter. This paper provides a computational study of these procedures, and the results show that they are extremely accurate when compared with estimates obtained using Newton’s unidimensional method. Eric J. Beh and Thomas B. Farver Copyright © 2012 Eric J. Beh and Thomas B. Farver. All rights reserved. Thu, 26 Apr 2012 13:52:14 +0000 http://www.hindawi.com/isrn/cm/2012/396831/ For ordinal log-linear models, the estimation of the parameter reflecting the linear-by-linear measure of association has long been a topic for the analysis of dependence for contingency tables. Typically, iterative procedures (including Newton’s method) are used to determine the maximum likelihood estimate of the parameter. Recently Beh and Farver (2009, ANZJS, 51, 335–352) show by way of example three reliable and accurate noniterative techniques that can be used to estimate the parameter and extended this study by examining their reliability computationally. This paper further investigates the reliability of the non-iterative procedures when compared with Newton’s method for estimating this association parameter and considers the impact of the sample size on the estimate. Eric J. Beh and Thomas B. Farver Copyright © 2012 Eric J. Beh and Thomas B. Farver. All rights reserved. Thu, 29 Mar 2012 14:57:09 +0000 http://www.hindawi.com/isrn/cm/2012/138718/ An analytic approximation to the solution of wave equation is studied. Wave equation is in radial form with indicated initial and boundary conditions, by variational iteration method it has been used to derive this approximation and some examples are presented to show the simplicity and efficiency of the method. Hossein Aminikhah Copyright © 2012 Hossein Aminikhah. All rights reserved. Thu, 15 Mar 2012 16:27:11 +0000 http://www.hindawi.com/isrn/cm/2012/172687/ The performance of the multigrid method and the effect of different grid levels on the convergence rate are evaluated. The two-, three-, and four-level V-cycle multigrid methods with the Gauss-Seidel iterative solver are employed for this purpose. The numerical solution of the one-dimensional Laplace equation with the Dirichlet boundary conditions is obtained using these methods. For the Laplace equation, a two-frequency function involving high- and low-frequency components is defined. It is observed that, however, the GS method can smooth out the high-frequency error components properly, but because the difference scheme for Laplace equation is remarkably concise, in the fine grids, a very large number of iterations are needed for extending the boundary conditions into the domain. Furthermore, the obtained results reveal that the number of necessary iterations for convergence is reduced considerably by employing the two-level multigrid algorithm. But increasing the number of levels of algorithm does not have any significant effect on the convergence rate in this study. Iman Harimi and Mohsen Saghafian Copyright © 2012 Iman Harimi and Mohsen Saghafian. All rights reserved. Thu, 15 Mar 2012 09:17:14 +0000 http://www.hindawi.com/isrn/cm/2012/341069/ This paper considers the nonlinear boundary value problem (BVP) for the electrohydrodynamic flow of a fluid in an ion drag configuration in a circular cylindrical conduit. The velocity field was solved using the new homotopy perturbation method (NHPM), considering the electrical field and strength of the nonlinearity. The approximate analytical procedure depends only on two components and polynomial initial condition. The analytical solution is obtained and the numerical results presented graphically. The effects of the Hartmann electric number ℋ𝑎 and the strength of nonlinearity 𝛼 are discussed and presented graphically. We also compare this method with numerical solution (N.S) and show that the present approach is less computational and is applicable for solving nonlinear boundary value problem (BVP). Najeeb Alam Khan, Muhammad Jamil, Amir Mahmood, and Asmat Ara Copyright © 2012 Najeeb Alam Khan et al. All rights reserved. Wed, 14 Mar 2012 08:53:46 +0000 http://www.hindawi.com/isrn/cm/2012/847178/ This paper proposes a novel antiwindup controller for 2D discrete linear systems with saturating controls in Fornasini-Marchesini second local state space (FMSLSS) setting. A Lyapunov-based method to design an antiwindup gain of 2D discrete systems with saturating controls is established. Stability conditions allowing the design of antiwindup loops, in both local and global contexts have been derived. Numerical examples are provided to illustrate the applicability of the proposed method. Richa Negi, Haranath Kar, and Shubhi Purwar Copyright © 2012 Richa Negi et al. All rights reserved. Tue, 13 Mar 2012 10:18:55 +0000 http://www.hindawi.com/isrn/cm/2012/435495/ We propose a conjugate gradient method which is based on the study of the Dai-Liao conjugate gradient method. An important property of our proposed method is that it ensures sufficient descent independent of the accuracy of the line search. Moreover, it achieves a high-order accuracy in approximating the second-order curvature information of the objective function by utilizing the modified secant condition proposed by Babaie-Kafaki et al. (2010). Under mild conditions, we establish that the proposed method is globally convergent for general functions provided that the line search satisfies the Wolfe conditions. Numerical experiments are also presented. Ioannis E. Livieris and Panagiotis Pintelas Copyright © 2012 Ioannis E. Livieris and Panagiotis Pintelas. All rights reserved. Mon, 05 Mar 2012 11:57:34 +0000 http://www.hindawi.com/isrn/cm/2012/321372/ Computational complexity is examined using the principle of increasing entropy. To consider computation as a physical process from an initial instance to the final acceptance is motivated because information requires physical representations and because many natural processes complete in nondeterministic polynomial time (NP). The irreversible process with three or more degrees of freedom is found intractable when, in terms of physics, flows of energy are inseparable from their driving forces. In computational terms, when solving a problem in the class NP, decisions among alternatives will affect subsequently available sets of decisions. Thus the state space of a nondeterministic finite automaton is evolving due to the computation itself, hence it cannot be efficiently contracted using a deterministic finite automaton. Conversely when solving problems in the class P, the set of states does not depend on computational history, hence it can be efficiently contracted to the accepting state by a deterministic sequence of dissipative transformations. Thus it is concluded that the state set of class P is inherently smaller than the state set of class NP. Since the computational time needed to contract a given set is proportional to dissipation, the computational complexity class P is a proper (strict) subset of NP. Arto Annila Copyright © 2012 Arto Annila. All rights reserved. Wed, 29 Feb 2012 11:54:12 +0000 http://www.hindawi.com/isrn/cm/2012/402037/ A theoretical study of free convective three-dimensional heat and mass transfer flow of a viscoelastic fluid along a steadily moving porous vertical plate in presence of transverse sinusoidal suction velocity distribution, and uniform free stream velocity has been considered. The flow becomes three dimensional due to this suction velocity. The governing equations of the flow field are solved by using series expansion method, and the expressions for velocity field, temperature field, skin friction, heat flux in terms of Nusselt number, and mass flux in terms of Sherwood number are obtained. The effects of the viscoelastic parameter on velocity profiles and shear stress with the combination of the other flow parameters are discussed graphically. Rita Choudhury and Utpal Jyoti Das Copyright © 2012 Rita Choudhury and Utpal Jyoti Das. All rights reserved. Thu, 26 Jan 2012 13:44:23 +0000 http://www.hindawi.com/isrn/cm/2012/843256/ We show that Brouwer’s fixed point theorem with isolated fixed points is equivalent to Brouwer’s fan theorem. Yasuhito Tanaka Copyright © 2012 Yasuhito Tanaka. All rights reserved. Tue, 24 Jan 2012 14:41:37 +0000 http://www.hindawi.com/isrn/cm/2012/139514/ We present a new approach based on the formulation of the integrodifferential quadrature method (hereafter called IDQ) to handle Volterra's and Fredholm's equations. This approach is constructed and tested with some realistic numerical examples using the basic computational aspects. Abdelwahab Zerarka, Abdesselam Soukeur, and Hanane Saidi Copyright © 2012 Abdelwahab Zerarka et al. All rights reserved. Thu, 08 Dec 2011 11:48:19 +0000 http://www.hindawi.com/isrn/cm/2012/126908/ Based on the alternating projection algorithm, which was proposed by Von Neumann to treat the problem of finding the projection of a given point onto the intersection of two closed subspaces, we propose a new iterative algorithm to solve the matrix nearness problem associated with the matrix equations 𝐴𝑋𝐵=𝐸, 𝐶𝑋𝐷=𝐹, which arises frequently in experimental design. If we choose the initial iterative matrix 𝑋0=0, the least Frobenius norm solution of these matrix equations is obtained. Numerical examples show that the new algorithm is feasible and effective. Xuefeng Duan and Chunmei Li Copyright © 2012 Xuefeng Duan and Chunmei Li. All rights reserved.