Search results

1 – 10 of 287
To view the access options for this content please click here
Article
Publication date: 1 September 2001

P. Alotto, P. Molfino and G. Molinari

The common approach to continuous and discrete optimisation problems in electromagnetics does not take into account uncertainties and variations of the design variables…

Abstract

The common approach to continuous and discrete optimisation problems in electromagnetics does not take into account uncertainties and variations of the design variables. Local sensitivity analysis is usually performed only after the optimisation run to study the behaviour of the objective function in the neighbourhood of the optimum. However, this procedure may prove inefficient if the optimum has to be rejected due to sensitivity considerations and a new run has then to be performed. In this paper an alternative approach, which takes into account uncertainties in the design variables and physical data, is presented, and an analytical function is used to highlight the features of the proposed method. The essence of the technique is to couple the optimisation with a series of worst case analyses which are embedded in the optimisation loop. The method is fully general and can be applied to any optimisation method. The additional computational costs associated with the procedure maybe relatively high, but in the authors’ opinion the obtained gains in user confidence in the solution and the computational savings in some cases far offset the possible drawbacks of the method.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 20 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 1 September 1999

Th. Ebner, Ch. Magele, B.R. Brandstätter, M. Luschin and P.G. Alotto

Global optimization in electrical engineering using stochastic methods requires usually a large amount of CPU time to locate the optimum, if the objective function is…

Abstract

Global optimization in electrical engineering using stochastic methods requires usually a large amount of CPU time to locate the optimum, if the objective function is calculated either with the finite element method (FEM) or the boundary element method (BEM). One approach to reduce the number of FEM or BEM calls using neural networks and another one using multiquadric functions have been introduced recently. This paper compares the efficiency of both methods, which are applied to a couple of test problems and the results are discussed.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 18 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 1 June 2000

A. Savini

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic…

Abstract

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community. Observes that computer package implementation theory contributes to clarification. Discusses the areas covered by some of the papers ‐ such as artificial intelligence using fuzzy logic. Includes applications such as permanent magnets and looks at eddy current problems. States the finite element method is currently the most popular method used for field computation. Closes by pointing out the amalgam of topics.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Content available
Book part
Publication date: 20 June 2017

David Shinar

Abstract

Details

Traffic Safety and Human Behavior
Type: Book
ISBN: 978-1-78635-222-4

To view the access options for this content please click here
Article
Publication date: 21 August 2009

Jani Paavilainen, Jukka Tuhkuri and Arttu Polojärvi

The purpose of this paper is to present a 2D combined finite‐discrete element method (FEM‐DEM) to model the multi‐fracture of beam structures and an application of the…

Abstract

Purpose

The purpose of this paper is to present a 2D combined finite‐discrete element method (FEM‐DEM) to model the multi‐fracture of beam structures and an application of the method to an ice‐structure interaction problem.

Design/methodology/approach

In the method, elastic beams and their fracture are modelled according to FEM by using nonlinear Timoshenko beam elements and cohesive crack model. Additionally, the beam elements are used to tie the discrete elements together. The contact forces between the colliding beams are calculated by using the DEM.

Findings

Three numerical examples are given to verify the method. Further, the method is applied to model the failure process of a floating ice beam against an inclined structure. Based on the comparison of the experiments and the simulation, a good agreement between the results is observed.

Originality/value

In the context of combined FEM‐DEM, the two novel features presented in this paper are: the use of Timoshenko finite element beams with damping to calculate internal forces and to combine the discrete elements; and the bending failure by the cohesive crack approach while simultaneously keeping track of the position of the neutral axis of the beam.

Details

Engineering Computations, vol. 26 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 19 June 2007

P. Alotto, A. De Cian, G. Molinari and M. Rossi

To show a possible implementation of surface impedance boundary conditions (SIBCs) in a time domain formulation based on the cell method (CM).

Abstract

Purpose

To show a possible implementation of surface impedance boundary conditions (SIBCs) in a time domain formulation based on the cell method (CM).

Design/methodology/approach

The implementation is based on vector fitting (VF), a technique which allows a time domain representation of a rational approximation of the surface impedance to be found.

Findings

It is shown that very little computational effort is needed to find a very good VF approximation of simple SIBCs and that such approximation is easily fitted into existing CM codes.

Research limitations/implications

The extension to higher order SIBCs has not been taken into account.

Practical implications

The proposed approach avoids the use of convolution integrals, is accurate and easy to implement.

Originality/value

This paper introduces the use of VF for the approximate time domain representation of SIBCs.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 1 October 1998

P. Alotto, P. Molfino, G. Molinari, M. Nervi and R. Orlando

In this paper a code for the solution of nonlinear thermo‐magnetic problems, arising in the transient analysis of thermal and electromagnetic fields in resistive toroidal…

Abstract

In this paper a code for the solution of nonlinear thermo‐magnetic problems, arising in the transient analysis of thermal and electromagnetic fields in resistive toroidal field coils of tokamak devices, is presented. A formulation based on the electric vector potential T and the magnetic total scalar potential Ψ for the analysis of the thermo‐magnetic skin effect phenomenon in the toroidal field coils of proposed tokamaks has been used, and the results obtained are reported, reviewed and discussed.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 17 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 1 September 1999

J.A. Gallardo and D.A. Lowther

The use of niching genetic algorithms can provide a method of a more widespread search of the design space for a device than more conventional methods. It provides, in…

Abstract

The use of niching genetic algorithms can provide a method of a more widespread search of the design space for a device than more conventional methods. It provides, in effect, a breadth first rather than a depth first search. Thus several alternative designs may be evaluated in parallel.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 18 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 10 April 2007

Leandro dos Santos Coelho and Piergiorgio Alotto

This paper aims to show on a widely used benchmark problem that chaotic sequences can improve the search ability of evolution strategies (ES).

Abstract

Purpose

This paper aims to show on a widely used benchmark problem that chaotic sequences can improve the search ability of evolution strategies (ES).

Design/methodology/approach

The Lozi map is used to generate new individuals in the framework of ES algorithms. A quasi‐Newton (QN) method is also used within the iterative loop to improve the solution's quality locally.

Findings

It is shown that the combined use of chaotic sequences and QN methods can provide high‐quality solutions with small standard deviation on the selected benchmark problem.

Research limitations/implications

Although the benchmark is considered to be representative of typical electromagnetic problems, different test cases may give less satisfactory results.

Practical implications

The proposed approach appears to be an efficient general purpose optimizer for electromagnetic design problems.

Originality/value

This paper introduces the use of chaotic sequences in the area of electromagnetic design optimization.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 3 January 2017

Obaid Ur Rehman, Shiyou Yang and Shafi Ullah Khan

The purpose of this paper is to explore the potential of standard quantum-based particle swarm optimization (QPSO) methods for solving electromagnetic inverse problems.

Abstract

Purpose

The purpose of this paper is to explore the potential of standard quantum-based particle swarm optimization (QPSO) methods for solving electromagnetic inverse problems.

Design/methodology/approach

A modified QPSO algorithm is designed.

Findings

The modified QPSO algorithm is an efficient and robust global optimizer for optimizing electromagnetic inverse problems. More specially, the experimental results as reported on different case studies demonstrate that the proposed method can find better final optimal solution at an early stage of the iterating process (uses less iterations) as compared to other tested optimal algorithms.

Originality/value

The modifications include the design of a new position updating formula, the introduction of a new mutation strategy and a dynamic control parameter to intensify the convergence speed of the algorithm.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

1 – 10 of 287