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Alternative Implementation (alternative + implementation)
Selected AbstractsOptimal stress recovery points for higher-order bar elements by Prathap's best-fit methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 8 2009S. Rajendran Abstract Barlow was the first to propose a method to predict optimal stress recovery points in finite elements (FEs). Prathap proposed an alternative method that is based on the variational principle. The optimal points predicted by Prathap, called Prathap points in this paper, have been reported in the literature for linear, quadratic and cubic elements. Prathap points turn out to be the same as Barlow points for linear and quadratic bar elements but different for cubic bar element. Nevertheless, for all the three elements, Prathap points coincide with the reduced Gaussian integration points. In this paper, an alternative implementation of Prathap's best-fit method is used to compute Prathap points for higher-order (viz., 4,10th order) bar elements. The effectiveness of Prathap points as points of accurate stress recovery is verified by actual FE analysis for typical bar problems. Copyright © 2008 John Wiley & Sons, Ltd. [source] Tightest constraint first: An efficient delay sensitive multicast routing algorithmINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2005Gang FengArticle first published online: 1 APR 200 Abstract As a key issue in multicast routing with quality of service (QoS) support, constrained minimum Steiner tree (CMST) problem has been a research focus for more than a decade, and tens of heuristics have been developed to solve this NP-complete problem. Among all the previously proposed algorithms, the bounded shortest path algorithm (BSMA) (IEEE INFOCOM'95 1995; 1:377,385) have been proved to be capable of producing a multicast tree that has on average the lowest cost. However, such an excellent cost performance is accompanied with an extremely high time complexity. Recently, Feng et al. presented an alternative implementation of BSMA, which makes use of the latest research results on the delay-constrained least cost (DCLC) routing problem. Simulations indicate that, in comparison with the original implementation, the alternative implementation has a much lower time complexity with virtually identical cost performance, and it also runs much faster than many renowned heuristics such as KPP (IEEE/ACM Trans. Networking 1993; 1(3):286,292) and CAO (The design and evaluation of routing algorithms for real-time channels. Technical Report ICSI TR-94-024, International Computer Science Institute, University of California at Berkeley, June 1994). In this paper, we propose a brand new heuristic TCF, which is based on an idea called ,tightest constraint first.' TCF runs a DCLC heuristic only once for each destination and therefore has a provably low time complexity. We further propose an iterative heuristic ITCF, which uses TCF to obtain an initial tree and then gradually refines it. Extensive simulations demonstrate that, in the average sense, TCF can achieve a cost performance comparable to or better than that of BSMA, the cost performance of ITCF is even better than that of TCF, TCF runs approximately twice as fast as ITCF, and ITCF runs 2,4 times as fast as the best implementation of BSMA. Copyright © 2005 John Wiley & Sons, Ltd. [source] On the applicability of multireference second-order perturbation theory to study weak magnetic coupling in molecular complexes,JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 6 2008Núria Queralt Abstract The performance of multiconfigurational second-order perturbation techniques is established for the calculation of small magnetic couplings in heterobinuclear complexes. Whereas CASPT2 gives satisfactory results for relatively strong magnetic couplings, the method shows important deviations from the expected Heisenberg spectrum for couplings smaller than 15,20 cm,1. The standard choice of the zeroth-order CASPT2 Hamiltonian is compared to alternative definitions published in the literature and the stability of the results is tested against increasing level shifts. Furthermore, we compare CASPT2 with an alternative implementation of multiconfigurational perturbation theory, namely NEVPT2 and with variational calculations based on the difference dedicated CI technique. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] A Version of the EM Algorithm for Proportional Hazard Model with Random EffectsBIOMETRICAL JOURNAL, Issue 6 2005José Cortiñas Abrahantes Abstract Proportional hazard models with multivariate random effects (frailties) acting multiplicatively on the baseline hazard have recently become a topic of an intensive research. One of the main practical problems related to the models is the estimation of parameters. To this aim, several approaches based on the EM algorithm have been proposed. The major difference between these approaches is the method of the computation of conditional expectations required at the E-step. In this paper an alternative implementation of the EM algorithm is proposed, in which the expected values are computed with the use of the Laplace approximation. The method is computationally less demanding than the approaches developed previously. Its performance is assessed based on a simulation study and compared to a non-EM based estimation approach proposed by Ripatti and Palmgren (2000). (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||