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Article
Publication date: 1 July 1998

Ralf Östermark

In the present study we introduce a new recursive matrix inversion (RMI) algorithm for a distributed memory computer. The RMI algorithm was designed to meet the…

Abstract

In the present study we introduce a new recursive matrix inversion (RMI) algorithm for a distributed memory computer. The RMI algorithm was designed to meet the requirements of high performance flexible software for implementing different parallel optimization algorithms. Special consideration has been taken to ensure the usability and portability of the algorithm. The results we present show that a significant improvement in performance is attainable over the LU‐factorization algorithm included in the LAPACK library.

Details

Kybernetes, vol. 27 no. 5
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 1 December 2000

R. Piltner

The use of enhanced strains leads to an improved performance of low order finite elements. A modified Hu‐Washizu variational formulation with orthogonal stress and strain…

Abstract

The use of enhanced strains leads to an improved performance of low order finite elements. A modified Hu‐Washizu variational formulation with orthogonal stress and strain functions is considered. The use of orthogonal functions leads to a formulation with B (overline) ‐strain matrices which avoids numerical inversion of matrices. Depending on the choice of the stress and strain functions in Cartesian or natural element coordinates one can recover, for example, the hybrid stress element P‐S of Pian‐Sumihara or the Trefftz‐type element QE2 of Piltner and Taylor. With the mixed formulation discussed in this paper a simple extension of the high precision elements P‐S and QE2 to general non‐linear problems is possible, since the final computer implementation of the mixed element is very similar to the implementation of a displacement element. Instead of sparse B‐matrices, sparse B (overline) ‐matrices are used and the typical matrix inversions of hybrid and mixed methods can be avoided. The two most efficient four‐node B (overline) ‐elements for plane strain and plane stress in this study are denoted B (overline)(x, y)‐QE4 and B (overline)(ξ, η)‐QE4.

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Engineering Computations, vol. 17 no. 8
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 13 August 2021

Manju V.M. and Ganesh R.S.

Multiple-input multiple-output (MIMO) combined with multi-user massive MIMO has been a well-known approach for high spectral efficiency in wideband systems, and it was…

Abstract

Purpose

Multiple-input multiple-output (MIMO) combined with multi-user massive MIMO has been a well-known approach for high spectral efficiency in wideband systems, and it was targeted to detect the MIMO signals. The increasing data rates with multiple antennas and multiple users that share the communication channel simultaneously lead to higher capacity requirements and increased complexity. Thus, different detection algorithms were developed for the Massive MIMO.

Design/methodology/approach

This paper focuses on the various literature analyzes on various detection algorithms and techniques for MIMO detectors. Here, it reviews several research papers and exhibits the significance of each detection method.

Findings

This paper provides the details of the performance analysis of the MIMO detectors and reveals the best value in the case of each performance measure. Finally, it widens the research issues that can be useful for future researchers to be accomplished in MIMO massive detectors

Originality/value

This paper has presented a detailed review of the detection of massive MIMO on different algorithms and techniques. The survey mainly focuses on different types of channels used in MIMO detections, the number of antennas used in transmitting signals from the source to destination, and vice-versa. The performance measures and the best performance of each of the detectors are described.

Details

International Journal of Pervasive Computing and Communications, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1742-7371

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Article
Publication date: 1 July 2014

Seyed Masoud Fatemi, Mehrdad Abedi, Behrooz Vahidi, Sajjad Abedi and Hassan Rastegar

The purpose of this paper is to pursue two following main goals: first, theorizing a new concept named as equivalent bus load in order to make a promising simplification…

Abstract

Purpose

The purpose of this paper is to pursue two following main goals: first, theorizing a new concept named as equivalent bus load in order to make a promising simplification over power system analysis. Second, proposing an outstanding fast and simple approach based on introduced concept for voltage estimation after multiple component outages while satisfying required accuracy.

Design/methodology/approach

Equivalent load bus theory introduces three transfer matrices that describe power system topology. Mentioned matrices could be calculated simply after system reconfiguration without matrix inversion. Using transfer matrices a large-scale power system can be modeled by a simple two-bus power system from the viewpoint of any desired bus so that load flow calculation leads to same value. The analysis of simplified power system yields to extract a new incremental model based on equivalent bus load theory that will be distinguished as an outstanding fast method for voltage estimation aim.

Findings

A deep study for fast voltage estimation aim is dedicated to evaluate proposed method from the accuracy and quickness point of view and the outcomes are compared to a well-known method as Distribution Factors (DF). Results and computational times unveil that presented approach is more accurate and much faster.

Originality/value

A novel and new fast voltage estimation method for assessment of power system component outages is introduced.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 February 1998

K.M. Gawrylczyk

The sensitivity analysis determines the influence of geometrical or physical parameters on some global or local quantities, used as objective function. Two different…

Abstract

The sensitivity analysis determines the influence of geometrical or physical parameters on some global or local quantities, used as objective function. Two different methods for nodal and global sensitivity evaluation are discussed. A very efficient method of direct differentiation is proposed which enables calculation of energy functional perturbation caused by the nodal position movement. Otherwise, the optimal nodal position minimizing the energetic functional can be obtained. The second method, based on stiffness matrix inversion, is well known from circuit theory. It was adapted for computing the sensitivity of nodal potentials in finite elements to perturbations in chosen parameter of analyzed model. After the stiffness matrix has been inverted we obtain the new solution of the FEM problem and the sensitivity values of all nodal potentials of our model. This sensitivity can be easily computed versus many parameters, for example versus electrical conductivity in different elements. Such an approach allows us to identify conductivity variations, e.g. cracks in metals. To identify the crack shape and its conductivity, the iterative process is necessary. The desired data, as magnetic flux density, come from measurement. For the aim of test cases in this work, the measurement was simulated by finite element computation. On the surface of the conducting plate, cracks of different shape and conductivity were inserted. The models with cracks were analyzed with the FEM providing training data for further iterative process. Then the cracks were removed, and the algorithm tried to reconstruct the conductivity distribution based on sensitivity values of the nodes.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 17 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 31 August 2012

A.S. Roknizadeh, A.S. Nobari, M. Mohagheghi and H. Shahverdi

The purpose of this paper is to analyze the stability of aeroelastic systems using aeroelastic frequency response function (FRF).

Abstract

Purpose

The purpose of this paper is to analyze the stability of aeroelastic systems using aeroelastic frequency response function (FRF).

Design/methodology/approach

The proposed technique determines the instability boundary of an aeroelastic system based on condition number (CN) of aeroelastic FRF matrix or directly from FRFs data.

Findings

Stability margins of typical section and hingeless helicopter rotor blade in the subsonic flow regimes (quasi‐steady and unsteady models) are determined using proposed techniques as two case studies.

Originality/value

The paper introduces a technique which is applicable not only when aerodynamic and structure analytical models are available but also when there are experimental models for structure and/or aerodynamics, such as impulse response functions data or FRFs data. In other words, the main advantage of the proposed method, besides its simplicity and low memory requirement, is its ability to utilize experimental data.

Details

Aircraft Engineering and Aerospace Technology, vol. 84 no. 5
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 February 2001

Suvranu De and Klaus‐Jürgen Bathe

Computational efficiency and reliability are clearly the most important requirements for the success of a meshless numerical technique. While the basic ideas of meshless…

Abstract

Computational efficiency and reliability are clearly the most important requirements for the success of a meshless numerical technique. While the basic ideas of meshless techniques are simple and well understood, an effective meshless method is very difficult to develop. The efficiency depends on the proper choice of the interpolation scheme, numerical integration procedures and techniques of imposing the boundary conditions. These issues in the context of the method of finite spheres are discussed.

Details

Engineering Computations, vol. 18 no. 1/2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 8 August 2016

Anas N. Al-Rabadi

The purpose of this paper is to introduce new implementations for parallel processing applications using bijective systolic networks and the corresponding carbon-based…

Abstract

Purpose

The purpose of this paper is to introduce new implementations for parallel processing applications using bijective systolic networks and the corresponding carbon-based field emission controlled switching. The developed implementations are performed in the reversible domain to perform the required bijective parallel computing, where the implementations for parallel computations that utilize the presented field-emission controlled switching and their corresponding m-ary (many-valued) extensions for the use in nano systolic networks are introduced. The first part of the paper presents important fundamentals with regards to systolic computing and carbon-based field emission that will be utilized in the implementations within the second part of the paper.

Design/methodology/approach

The introduced systolic systems utilize recent findings in field emission and nano applications to implement the functionality of the basic bijective systolic network. This includes many-valued systolic computing via field emission techniques using carbon-based nanotubes and nanotips. The realization of bijective logic circuits in current and emerging technologies can be very important for various reasons. The reduction of power consumption is a major requirement for the circuit design in future technologies, and thus, the new nano systolic circuits can play an important role in the design of circuits that consume minimal power for future applications such as in low-power signal processing. In addition, the implemented bijective systems can be utilized to implement massive parallel processing and thus obtaining very high processing performance, where the implementation will also utilize the significant size reduction within the nano domain. The extensions of implementations to field emission-based many-valued systolic networks using the introduced bijective nano systolic architectures are also presented.

Findings

Novel bijective systolic architectures using nano-based field emission implementations are introduced in this paper, and the implementation using the general scheme of many-valued computing is presented. The carbon-based field emission implementation of nano systolic networks is also introduced. This is accomplished using the introduced field emission carbon-based devices, where field emission from carbon nanotubes and nano-apex carbon fibers is utilized. The implementations of the many-valued bijective systolic networks utilizing the introduced nano-based architectures are also presented.

Originality/value

The introduced bijective systolic implementations form new important directions in the systolic realizations using the newly emerging nano-based technologies. The 2-to-1 multiplexer is a basic building block in “switch logic,” where in switch logic, a logic circuit is realized as a combination of switches rather than a combination of logic gates as in the gate logic, which proves to be less costly in synthesizing multiplexer-based wide variety of modern circuits and systems since nano implementations exist in very compact space where carbon-based devices switch reliably using much less power than silicon-based devices. The introduced implementations for nano systolic computation are new and interesting for the design in future nanotechnologies that require optimal design specifications of minimum power consumption and minimum size layout such as in low-power control of autonomous robots and in the adiabatic low-power very-large-scale-integration circuit design for signal processing applications.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 9 no. 3
Type: Research Article
ISSN: 1756-378X

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Article
Publication date: 14 November 2008

Giovanni Aiello, Salvatore Alfonzetti, Giuseppe Borzì, Emanuele Dilettoso and Nunzio Salerno

This paper aims to extend an efficient method to solve the global system of linear algebraic equations in the hybrid finite element method – boundary element method…

Abstract

Purpose

This paper aims to extend an efficient method to solve the global system of linear algebraic equations in the hybrid finite element method – boundary element method (FEM‐BEM) solution of open‐boundary skin effect problems. The extension covers the cases in which the skin effect problem is set in a truncated domain in which no homogeneous Dirichlet conditions are imposed.

Design/methodology/approach

The extended method is based on use of the generalized minimal residual (GMRES) solver, which is applied virtually to the reduced system of equations in which the unknowns are the nodal values of the normal derivative of the magnetic vector potential on the fictitious truncation boundary. In each step of the GMRES algorithm the FEM equations are solved by means of the standard complex conjugate gradient solver, whereas the BEM equations are not solved but used to perform fast matrix‐by‐vector multiplications. The BEM equations are written in a non‐conventional way, by making the nodes for the potential non‐coinciding with the nodes for its normal derivative.

Findings

The paper shows that the method proposed is very competitive with respect to other methods to solve open‐boundary skin effect problems.

Originality/value

The paper illustrates a new method to solve efficiently skin effect problems in open boundary domains by means of the hybrid FEM‐BEM method.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 20 December 2018

Mi Zhao, Huifang Li, Shengtao Cao and Xiuli Du

The purpose of this paper is to propose a new explicit time integration algorithm for solution to the linear and non-linear finite element equations of structural dynamic…

Abstract

Purpose

The purpose of this paper is to propose a new explicit time integration algorithm for solution to the linear and non-linear finite element equations of structural dynamic and wave propagation problems.

Design/methodology/approach

The algorithm is completely explicit so that no linear equation system requires solving, if the mass matrix of the finite element equation is diagonal and whether the damping matrix does or not. The algorithm is a single-step method that has the simple starting and is applicable to the analysis with the variable time step size. The algorithm is second-order accurate and conditionally stable. Its numerical stability, dissipation and dispersion are analyzed for the dynamic single-degree-of-freedom equation. The stability of the multi-degrees-of-freedom non-proportional damping system can be evaluated directly by the stability theory on ordinary differential equation.

Findings

The performance of the proposed algorithm is demonstrated by several numerical examples including the linear single-degree-of-freedom problem, non-linear two-degree-of-freedom problem, wave propagation problem in two-dimensional layer and seismic elastoplastic analysis of high-rise structure.

Originality/value

A new single-step second-order accurate explicit time integration algorithm is proposed to solve the linear and non-linear dynamic finite element equations. The algorithm has advantages on the numerical stability and accuracy over the existing modified central difference method and Chung-Lee method though the theory and numerical analyses.

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