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1 – 10 of 112
Article
Publication date: 5 September 2016

F.E. Benmohamed, I.K. Bousserhane, A. Kechich, B. Bessaih and A. Boucheta

The end-effects is a well-recognized phenomenon occurring in the linear induction motor (LIM) which makes the analysis and control of the LIM with good performance very difficult…

Abstract

Purpose

The end-effects is a well-recognized phenomenon occurring in the linear induction motor (LIM) which makes the analysis and control of the LIM with good performance very difficult and can cause additional significant non-linearities in the model. So, the compensation of parameters uncertainties due to these effects in the control system is very necessary to get a robust speed control. The purpose of this paper is to propose a new technique of LIM end-effects estimation using the inverse rotor time constant tuning in order to compensate the flux orientation error in the indirect field-oriented control (IFOC) control law.

Design/methodology/approach

First, the dynamic model of the LIM taking into consideration the end-effects based on Duncan model is derived. Then, the IFOC for LIM speed control with end-effects compensation is derived. Finally, a new technique of LIM end-effects estimation is proposed based on the model reference adaptive system (MRAS) theory using the instantaneous active power and the estimated stator currents vector. These estimated currents are obtained through the solution of LIM state equations.

Findings

Simulations were carried out in MATLAB/SIMULINK to demonstrate the effectiveness and robustness of LIM speed control with the proposed MRAS inverse rotor time constant tuning to estimate end-effects value. The numerical validation results show that the proposed scheme permits the drive to achieve good dynamic performance, satisfactory for the estimated end-effects of the LIM model and robustness to uncertainties.

Originality/value

The end-effects causes a drop in the magnetizing, primary and the secondary inductance, requiring a more complex LIM control scheme. This paper presents a new approach of LIM end-effect estimation based on the online adaptation and tuning of the LIM inductances. The proposed scheme use the inverse rotor time constant tuning for end-effects correction in LIM vector control block.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 35 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 January 2012

Jinhua Du, Deliang Liang and Qingfu Li

The purpose of this paper is to propose a method to estimate the magnetic saturation and end effect of linear switched reluctance machines (LSRMs) with fully pitched winding…

Abstract

Purpose

The purpose of this paper is to propose a method to estimate the magnetic saturation and end effect of linear switched reluctance machines (LSRMs) with fully pitched winding configuration used in the wave energy conversion.

Design/methodology/approach

The magnetic saturation and strong coupling make it very difficult to derive a comprehensive mathematical model for the behavior of the LSRMs. Meanwhile, the various end effects could not be comprehensively considered in the two‐dimensional model which is widely studied. Therefore, the magnetic equivalent circuit model including the three‐dimensional (3‐D) effects is presented in this paper and 3‐D finite element analysis (FEA) is used to validate the mathematical model.

Findings

The results from 3‐D FEA are in good agreement with the numerical simulation, which validates the accuracy of the magnetic equivalent circuit modeling method.

Practical implications

This technique helps one to know the influence exerted by the magnet saturation and end effect of LSRMs and provides a powerful computer‐aided analysis tool. Meanwhile, this modeling method supplies accurate values for the following study of reliable control algorithm.

Originality/value

The paper presents a magnetic equivalent method to estimate the magnetic saturation and end effect of LSRMs with fully pitched winding configuration used in the wave energy conversion.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 June 2011

Dov Shirtz and Yuval Elovici

This paper proposes a new framework for optimizing investment decisions when deciding about information security remedies.

1315

Abstract

Purpose

This paper proposes a new framework for optimizing investment decisions when deciding about information security remedies.

Design/methodology/approach

The framework assumes that the organization is aware of a set of remedies that can be employed to address end‐effects that have been identified. The framework also assumes that the organization defines its information security policy by setting a minimum level of protection for each end‐effect. Given the two sets of costs, that of the end‐effect and the potential damage it can cause and that of the remedy and the required level of protection from each end‐effect, this framework can be used to identify the optimal set of remedies for a given budget that complies with the organization's information security policy. The framework is illustrated using a practical example concerning investment decision optimization in a financial organization.

Findings

The paper shows that exhausting the information security budget does not assure a higher level of security required by the organisation.

Practical implications

Concentrating on end‐effects and on the organizational requirements eases the process of remedy selection. The proposed methodology circumvents the common process of assuming probabilities of information security events.

Originality/value

This research proposes a practical and an easily implementable framework, enabling the information security manager to align the information security remedies and best practice methodological requirements with organizational budget constraints and business requirements while maintaining a required level of security.

Details

Information Management & Computer Security, vol. 19 no. 2
Type: Research Article
ISSN: 0968-5227

Keywords

Article
Publication date: 14 April 2014

Alexander C. Larson, Rita L. Reicher and David William Johnsen

– The purpose of this research is to test for price threshold effects in the demand for high-involvement services for small businesses.

1101

Abstract

Purpose

The purpose of this research is to test for price threshold effects in the demand for high-involvement services for small businesses.

Design/methodology/approach

The authors use a stated preference choice-based conjoint study of small business telecommunications demand. Using survey data, individual-level parameter estimates for a demand model are achieved via the Hierarchical Bayes method of estimation.

Findings

For demand for small business telecommunications services, the authors find very strong positive impacts of nine-ending and zero-ending prices on the demand for a common bundle of telecommunications services (wired telephone service, broadband internet, and cellular telephone service), even at prices so high a shift in the left-most digit does not occur.

Practical implications

The advertising, brand, or product manager or statistician who assumes threshold effects are not extant in high-involvement service demand may find conventional demand estimation methods lead to erroneous conclusions and less effective pricing strategies.

Originality/value

In the statistical literature on price-ending effects on product demand, most products for which demand is modelled are low-involvement consumer products priced at less than ten monetary units per unit of product. There is a lacuna in this price-ending effects literature regarding small businesses and high-involvement services offered at three-digit prices via monthly subscription. This research indicates that testing for threshold effects should be de rigeur in the methodology of demand estimation for telecommunications or other high-involvement services.

Details

Journal of Product & Brand Management, vol. 23 no. 2
Type: Research Article
ISSN: 1061-0421

Keywords

Article
Publication date: 12 June 2017

Hussain Altammar, Sudhir Kaul and Anoop K. Dhingra

Wavelets are being increasingly used for damage diagnostics. The purpose of this paper is to present an algorithm that uses the wavelet transform for detecting mixed-mode, also…

Abstract

Purpose

Wavelets are being increasingly used for damage diagnostics. The purpose of this paper is to present an algorithm that uses the wavelet transform for detecting mixed-mode, also known as combined mode, cracks in large truss structures.

Design/methodology/approach

The mixed-mode crack is modeled by superposing two damage modes, and this model is combined with a finite element model of the truss. The natural modes of the truss are processed through the wavelet transform and then used to determine the damage location. The influence of multiple parameters such as truss geometry, crack geometry, number of truss members, orientation of truss members, etc. is investigated as part of the study.

Findings

The proposed damage detection algorithm is found to be successful in detecting single mode as well as mixed-mode cracks even in the presence of significant end effects, and even when a relatively coarse sampling of natural modes is used. Results from multiple simulations that involve three commonly used truss structures are presented. A correlation between damage severity and the magnitude of wavelet coefficients is observed.

Originality/value

The proposed algorithm is found to be successful in accurately detecting damage, but direct determination of damage severity is found to be challenging.

Details

International Journal of Structural Integrity, vol. 8 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 11 May 2010

A. Boucheta, I.K. Bousserhane, A. Hazzab, B. Mazari and M.K. Fellah

The purpose of this paper is to propose mover position control of linear induction motor (LIM) using an adaptive backstepping approach based on field orientation.

Abstract

Purpose

The purpose of this paper is to propose mover position control of linear induction motor (LIM) using an adaptive backstepping approach based on field orientation.

Design/methodology/approach

First, the indirect field‐oriented control LIM is derived. Then, an adaptive backstepping approach based on field‐oriented control of LIM is proposed to compensate the uncertainties which occur in the control. Mover position amplitude tracking objective is formulated, under the assumption of unknown total mass of the moving element, viscous friction, and load force, so that the position regulation is achieved.

Findings

The effectiveness and robustness of the proposed control scheme are verified by numerical simulation using Matlab/Simulink model. The numerical validation results of the proposed scheme have presented good transient control performances and robustness to uncertainties compared to the conventional backstepping control design.

Originality/value

The paper presents an adaptive backstepping approach for LIM control that achieves mover position amplitude tracking objective under mechanical parameter variation.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 June 1997

N. Harid, D.M. German and R.T. Waters

Self‐inductance calculations are presented for coils of modular construction. Individual modules have a fixed winding density, so that a complete multi‐module coil will be…

397

Abstract

Self‐inductance calculations are presented for coils of modular construction. Individual modules have a fixed winding density, so that a complete multi‐module coil will be characterized by larger inter‐turn spacing at its extremities to provide suitable insulation strength under impulse voltage conditions. Gives inductance computations using finite‐element analysis, so that empirical correction factors to take account of end‐effects and inter‐turn spacing are unnecessary. Comparison where possible with established empirical methods shows consistency. Gives an example of oscillatory high‐voltage tests.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 16 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 21 September 2015

Hongyu Zhao, Zhelong Wang, Qin Gao, Mohammad Mehedi Hassan and Abdulhameed Alelaiwi

The purpose of this paper is to develop an online smoothing zero-velocity-update (ZUPT) method that helps achieve smooth estimation of human foot motion for the ZUPT-aided…

Abstract

Purpose

The purpose of this paper is to develop an online smoothing zero-velocity-update (ZUPT) method that helps achieve smooth estimation of human foot motion for the ZUPT-aided inertial pedestrian navigation system.

Design/methodology/approach

The smoothing ZUPT is based on a Rauch–Tung–Striebel (RTS) smoother, using a six-state Kalman filter (KF) as the forward filter. The KF acts as an indirect filter, which allows the sensor measurement error and position error to be excluded from the error state vector, so as to reduce the modeling error and computational cost. A threshold-based strategy is exploited to verify the detected ZUPT periods, with the threshold parameter determined by a clustering algorithm. A quantitative index is proposed to give a smoothness estimate of the position data.

Findings

Experimental results show that the proposed method can improve the smoothness, robustness, efficiency and accuracy of pedestrian navigation.

Research limitations/implications

Because of the chosen smoothing algorithm, a delay no longer than one gait cycle is introduced. Therefore, the proposed method is suitable for applications with soft real-time constraints.

Practical implications

The paper includes implications for the smooth estimation of most types of pedal locomotion that are achieved by legged motion, by using a sole foot-mounted commercial-grade inertial sensor.

Originality/value

This paper helps realize smooth transitions between swing and stance phases, helps enable continuous correction of navigation errors during the whole gait cycle, helps achieve robust detection of gait phases and, more importantly, requires lower computational cost.

Details

Sensor Review, vol. 35 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 June 2000

K. Wiak

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines;…

Abstract

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines; reluctance motors; PM motors; transformers and reactors; and special problems and applications. Debates all of these in great detail and itemizes each with greater in‐depth discussion of the various technical applications and areas. Concludes that the recommendations made should be adhered to.

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

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 community…

1129

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

1 – 10 of 112