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Article
Publication date: 30 March 2012

G.A. Gravvanis, P.I. Matskanidis, K.M. Giannoutakis and E.A. Lipitakis

The purpose of this paper is to propose novel parallel computational techniques for the parallelization of explicit finite element generalized approximate inverse methods, based…

346

Abstract

Purpose

The purpose of this paper is to propose novel parallel computational techniques for the parallelization of explicit finite element generalized approximate inverse methods, based on Portable Operating System Interface for UniX (POSIX) threads, for multicore systems.

Design/methodology/approach

The authors' main motive for the derivation of the new Parallel Generalized Approximate Inverse Finite Element Matrix algorithmic techniques is that they can be efficiently used in conjunction with explicit preconditioned conjugate gradient‐type schemes on multicore systems. The proposed parallelization technique of the Optimized Banded Generalized Approximate Inverse Finite Element Matrix (OBGAIFEM) algorithm is achieved based on the concept of the “fish bone” approach with the use of a thread pool pattern. Theoretical estimates on the computational complexity of the parallel generalized approximate inverse finite element matrix algorithmic techniques are also derived.

Findings

Application of the proposed method on a two‐dimensional boundary value problem is discussed and numerical results are given on a multicore system using POSIX threads. These results tend to become optimum and are favorably compared to corresponding results from multiprocessor systems, as presented in recent work by Gravvanis et al.

Originality/value

The proposed parallel explicit finite element generalized approximate inverse preconditioning, using approximate factorization and approximate inverse algorithms, is an efficient computational method that is valuable for computer scientists and for scientists and engineers in engineering computations.

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Article
Publication date: 1 March 2000

George A. Gravvanis

A new class of explicit preconditioning methods based on the concept of sparse approximate factorization procedures and inverse matrix techniques is introduced for solving…

261

Abstract

A new class of explicit preconditioning methods based on the concept of sparse approximate factorization procedures and inverse matrix techniques is introduced for solving biharmonic equations. Isomorphic methods in conunction with explicit preconditioned schemes based on approximate inverse matrix techniques are presented for the efficient solution of biharmonic equations. Application of the proposed method on linear systems is discussed and numerical results are given.

Details

Engineering Computations, vol. 17 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 April 2006

Konstantinos M. Giannoutakis and George A. Gravvanis

To propose novel parallel/distributed normalized explicit finite element (FE) approximate inverse preconditioning for solving sparse FE linear systems.

218

Abstract

Purpose

To propose novel parallel/distributed normalized explicit finite element (FE) approximate inverse preconditioning for solving sparse FE linear systems.

Design/methodology/approach

The design of suitable methods was the main objective for which several families of the normalized approximate inverse, based on sparse normalized approximate factorization, are produced. The main motive for the derivation of the new normalized approximate inverse FE matrix algorithmic techniques is that they can be efficiently used in conjunction with normalized explicit preconditioned conjugate gradient (NEPCG) – type schemes on parallel and distributed systems. Theoretical estimates on the rate of convergence and computational complexity of the NEPCG method are also derived.

Findings

Application of the proposed method on a three‐dimensional boundary value problem is discussed and numerical results for uniprocessor systems along with speed‐ups and efficiency for multicomputer systems are given. These results tend to become optimum, which are in qualitative agreement with the theoretical results presented for uniprocessor and distributed memory systems, using message passing interface (MPI) communication library.

Research limitations/implications

Further parallel algorithmic techniques will be investigated in order to improve the speed‐ups and the computational complexity of the parallel normalized explicit approximate inverse preconditioning.

Originality/value

The proposed parallel/distributed normalized explicit approximate inverse preconditioning, using approximate factorization and approximate inverse algorithms, is an efficient computational method that is valuable for computer scientists and for scientists and engineers in engineering computations.

Details

Engineering Computations, vol. 23 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 25 February 2014

George A. Gravvanis and Christos K. Filelis-Papadopoulos

The purpose of this paper is to propose multigrid methods in conjunction with explicit approximate inverses with various cycles strategies and comparison with the other smoothers…

118

Abstract

Purpose

The purpose of this paper is to propose multigrid methods in conjunction with explicit approximate inverses with various cycles strategies and comparison with the other smoothers.

Design/methodology/approach

The main motive for the derivation of the various multigrid schemes lies in the efficiency of the multigrid methods as well as the explicit approximate inverses. The combination of the various multigrid cycles with the explicit approximate inverses as smoothers in conjunction with the dynamic over/under relaxation (DOUR) algorithm results in efficient schemes for solving large sparse linear systems derived from the discretization of partial differential equations (PDE).

Findings

Application of the proposed multigrid methods on two-dimensional boundary value problems is discussed and numerical results are given concerning the convergence behavior and the convergence factors. The results are comparatively better than the V-cycle multigrid schemes presented in a recent report (Filelis-Papadopoulos and Gravvanis).

Research limitations/implications

The limitations of the proposed scheme lie in the fact that the explicit finite difference approximate inverse matrix used as smoother in the multigrid method is a preconditioner for specific sparsity pattern. Further research is carried out in order to derive a generic explicit approximate inverse for any type of sparsity pattern.

Originality/value

A novel smoother for the geometric multigrid method is proposed, based on optimized banded approximate inverse matrix preconditioner, the Richardson method in conjunction with the DOUR scheme, for solving large sparse linear systems derived from finite difference discretization of PDEs. Moreover, the applicability and convergence behavior of the proposed scheme is examined based on various cycles and comparative results are given against the damped Jacobi smoother.

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Article
Publication date: 1 May 1999

George A. Gravvanis

A new class of approximate inverse banded matrix techniques based on the concept of LU‐type factorization procedures is introduced for computing explicitly approximate inverses…

852

Abstract

A new class of approximate inverse banded matrix techniques based on the concept of LU‐type factorization procedures is introduced for computing explicitly approximate inverses without inverting the decomposition factors. Explicit preconditioned iterative schemes in conjunction with approximate inverse matrix techniques are presented for the efficient solution of banded linear systems. Applications of the method on a linear system are discussed and numerical results are given.

Details

Engineering Computations, vol. 16 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 7 March 2016

Christos K. Filelis-Papadopoulos and George A. Gravvanis

– The purpose of this paper is to propose novel factored approximate sparse inverse schemes and multi-level methods for the solution of large sparse linear systems.

146

Abstract

Purpose

The purpose of this paper is to propose novel factored approximate sparse inverse schemes and multi-level methods for the solution of large sparse linear systems.

Design/methodology/approach

The main motive for the derivation of the various generic preconditioning schemes lies to the efficiency and effectiveness of factored preconditioning schemes in conjunction with Krylov subspace iterative methods as well as multi-level techniques for solving various model problems. Factored approximate inverses, namely, Generic Factored Approximate Sparse Inverse, require less fill-in and are computed faster due to the reduced number of nonzero elements. A modified column wise approach, namely, Modified Generic Factored Approximate Sparse Inverse, is also proposed to further enhance performance. The multi-level approximate inverse scheme, namely, Multi-level Algebraic Recursive Generic Approximate Inverse Solver, utilizes a multi-level hierarchy formed using Block Independent Set reordering scheme and an approximation of the Schur complement that results in the solution of reduced order linear systems thus enhancing performance and convergence behavior. Moreover, a theoretical estimate for the quality of the multi-level approximate inverse is also provided.

Findings

Application of the proposed schemes to various model problems is discussed and numerical results are given concerning the convergence behavior and the convergence factors. The results are comparatively better than results by other researchers for some of the model problems.

Research limitations/implications

Further enhancements are investigated for the proposed factored approximate inverse schemes as well as the multi-level techniques to improve quality of the schemes. Furthermore, the proposed schemes rely on the definition of multiple parameters that for some problems require thorough testing, thus adaptive techniques to define the values of the various parameters are currently under research. Moreover, parallel schemes will be investigated.

Originality/value

The proposed approximate inverse preconditioning schemes as well as multi-level schemes are efficient computational methods that are valuable for computer scientists and for scientists and engineers in engineering computations.

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Article
Publication date: 23 March 2020

Vicente Prado-Gascó, Nabil Amara and Julia Olmos-Peñuela

The purpose of this paper is to develop and validate a 12-item scale of knowledge spillovers transfer (KST) from scholars in business schools to practitioners outside academia.

551

Abstract

Purpose

The purpose of this paper is to develop and validate a 12-item scale of knowledge spillovers transfer (KST) from scholars in business schools to practitioners outside academia.

Design/methodology/approach

A sample of 807 faculty members from 35 Canadian business schools was used for the psychometric evaluation of the questionnaire. The reliability of the scale was assessed by Cronbach’s alpha. The construct validity was examined through exploratory and confirmatory factor analyses. The nomological validity was assessed by analyzing the prediction of two output indicators by means of KST using structural equation modeling and by testing differences in KST according to other related variables.

Findings

The psychometric properties obtained indicate that the instrument is reliable and valid, which invites to its use as a diagnostic tool of KST from scholars in business schools to users outside academia.

Research limitations/implications

The KST questionnaire developed and validated in this study can be considered as a useful practical tool enabling the assessment of business scholars’ KST activities.

Practical implications

The KST questionnaire developed may enlighten business schools’ administrators and policy-makers to identify and implement actions to improve the transfer of knowledge between research and practice.

Originality/value

To the best of the authors’ knowledge, despite the wide range of quantitative measures proposed in the literature, this is the first study that aims to present a comprehensive, accurate and validated scale to measure KST from scholars in business schools to practitioners outside academia.

Details

Journal of Knowledge Management, vol. 24 no. 3
Type: Research Article
ISSN: 1367-3270

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Article
Publication date: 1 August 1999

Gh. Juncu

The paper analyses the preconditioning of non‐linear nonsymmetric equations with approximations of the discrete Laplace operator. The test problems are non‐linear 2‐D elliptic…

167

Abstract

The paper analyses the preconditioning of non‐linear nonsymmetric equations with approximations of the discrete Laplace operator. The test problems are non‐linear 2‐D elliptic equations that describe natural convection, Darcy flow, in a porous medium. The standard second order accurate finite difference scheme is used to discretize the models’ equations. The discrete approximations are solved with a double iterative process using the Newton method as outer iteration and the preconditioned generalised conjugate gradient (PGCG) methods as inner iteration. Three PGCG algorithms, CGN, CGS and GMRES, are tested. The preconditioning with discrete Laplace operator approximations consists of replacing the solving of the equation with the preconditioner by a few iterations of an appropriate iterative scheme. Two iterative algorithms are tested: incomplete Cholesky (IC) and multigrid (MG). The numerical results show that MG preconditioning leads to mesh independence. CGS is the most robust algorithm but its efficiency is lower than that of GMRES.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 9 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 8 June 2015

S. Michelle Driedger and Jade Weimer

Scholars rely on electronic databases to conduct searches and locate relevant citations. The purpose of this paper is to compare the retrieval results on the same topic (multiple…

851

Abstract

Purpose

Scholars rely on electronic databases to conduct searches and locate relevant citations. The purpose of this paper is to compare the retrieval results on the same topic (multiple sclerosis and liberation therapy) of two commonly used databases for searching print news media: ProQuest’s Canadian Newsstand Major Dailies and Dow Jones’ Factiva.

Design/methodology/approach

A case study comparing two electronic searchable databases using the same keywords, date range, and newspaper-specific search parameters across three Canadian university institutions.

Findings

Considerable differences were found between institutional searches using Factiva. Factiva allows all individual users the capacity to establish systems-wide “administrator” privileges, thereby controlling the output for subsequent users if these preferences are not changed. The capacity for individual users to tailor searches within Canadian Newsstand Major Dailies was more in line with standard protocols for institutions paying for single user accounts with access to multiple sessions within that same institution: any user-specific searching/retrieval preferences are individually contained within a search and do not influence the searches of a different user.

Research limitations/implications

What began as a comparative analysis of two commonly used databases for searching print news media turned into an examination of larger systemic problems. The findings call into question several factors: the integrity of a researcher-generated data set; the quality of results published in peer-reviewed journals based on researcher-generated data sets derived from established e-resource databases; the reliability of the same e-resource database across multiple institutions; and the quality of e-resource databases for scholarly research when developed to serve primarily non-academic clients.

Originality/value

No comparison of this kind for these particular e-resource databases has been documented in the literature. In fact, the scholarly publications that address questions of functionality and reliability of either Factiva or Proquest have not brought this issue into the discussion. Therefore, this study furthers academic discourse on the nature and reliability of database use at any academic institution and illustrates that researchers, in a variety of academic fields, cannot depend on the reliability of their search results without thoroughly consulting the various settings of their database.

Details

Online Information Review, vol. 39 no. 3
Type: Research Article
ISSN: 1468-4527

Keywords

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Article
Publication date: 1 February 1996

Jaroslav Mackerle

Presents a review on implementing finite element methods on supercomputers, workstations and PCs and gives main trends in hardware and software developments. An appendix included…

677

Abstract

Presents a review on implementing finite element methods on supercomputers, workstations and PCs and gives main trends in hardware and software developments. An appendix included at the end of the paper presents a bibliography on the subjects retrospectively to 1985 and approximately 1,100 references are listed.

Details

Engineering Computations, vol. 13 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

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