bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phenomena of additional cogging torque components influenced by stator lamination stacking methods in PM motors
Authors: Gašparin Lovrenc , Černigoj Andrej , Fišer Rastko 
Published: May 2009

PurposeThe purpose of this paper is to estimate and evaluate how cogging torque in permanent magnet (PM) motor designs is sensitive to the number of applied interlocks in stator back‐iron, which is a standard method for stator lamination stacking.Design/methodology/approachThe PM motors exhibit inherent cogging torque, which creates torque ripple and prevents smooth rotation of the rotor resulting in undesirable vibration and noise. While cogging torque minimization is necessary to improve PM motor performance, several FEM models have been developed to study and present data demonstrating sensitivity of the cogging torque to the applied interlocks. A procedure that would predict and evaluate cogging torque components relative to chosen number and positions of interlocks was proposed.FindingsOn the basis of theoretical considerations, which were verified by numerous performed simulations using different FEM models, it was found out and proved that interlocks in the stator back‐iron cause the phenomenon of additional cogging torque harmonic components (AHC). Taking into account presented theoretical aspects motor designers can predict, which AHC will comprise the cogging torque. Each motor design has its own optimal value of interlocks, therefore a precise study should be performed during the design process.Practical implicationsBy utilizing presented method and considering recommendations, advanced designers of PM motors will have a reliable tool for predicting the order and the level of AHC in total cogging torque due to the stator lamination stacking methods.Originality/valueThe paper presents theoretical aspects and analytical equations of AHC of PM motors. So far, the authors dealing with the cogging torque of the PM motors did not take into account the influence of the stator lamination stacking method on the level of torque oscillations. The new contribution is also the study of the sensitivity of different motor designs to the number and position of interlocks, which enables the minimization of the AHC in order to fulfil stringent market demands for low‐cogging torque level.
Comparison of a simple and a detailed model of magnetic hysteresis with measurements on electrical steel
Authors: Tavakoli Hanif , Bormann Dierk , Ribbenfjärd David , Engdahl Göran 
Published: May 2009

PurposeFor efficient magnetic field calculations in electrical machines, the hysteresis and losses in laminated electrical steel must be modeled in a simple and reliable way. The purpose of this paper is to investigate and discuss the potential of a simple complex‐permeability model.Design/methodology/approachA frequency dependent complex‐permeability model as well as a more detailed model (describing hysteresis, classical eddy current effects, and excess losses separately) are compared to single‐sheet measurements on laminated electrical steel. It is discussed under which circumstances the simple complex‐μ model is an adequate substitute for the more detailed model.FindingsA satisfactory agreement of the simple complex‐μ model was found with both detailed model and measurements, improving with increasing frequencies. This is true not only for the effective permeability function, but holds also for the detailed H‐B characteristics (hysteresis).Originality/valueIt is demonstrated that the complex‐μ model is a reliable and convenient starting point for the estimation of flux distribution and losses in complicated magnetic core geometries.
The influence of magnetic hysteresis on magnetorheological fluid clutch operation
Authors: Jędryczka Cezary , Sujka Piotr , Szeląg Wojciech 
Published: May 2009

PurposeThe purpose of this paper is to elaborate upon the mathematical model of coupled electromagnetic, fluid dynamic and motion phenomena that will allow for investigation of the magnetic hysteresis influence on the axial symmetry magnetorheological fluid (MRF) clutch operation.Design/methodology/approachTo solve the partial differential equations describing magnetic vector and fluid velocity potential distributions in axial symmetry MRF electromechanical transducers the finite‐element methods have been applied. To solve model equations in the time domain, the time stepping method have been adopted. To introduce magnetic hysteresis phenomenon to presented approach the Jiles‐Atherton model have been applied. The physical properties of MRFs have been modeled by means of the Bingham model. Owing to high nonlinearity of the considered problem to solve obtained matrix equations systems the iterative Newton‐Raphson combined with the block over relaxation method have been applied.FindingsThe proposed model of coupled phenomena and the elaborated algorithm for solving the nonlinear model equations can be successfully applied in the analysis of transients in the MRF transducers taking fluid dynamics and magnetic hysteresis into account. Comparison of the measured and calculated clutch characteristics proves the model accuracy. Moreover, it has been shown that the residual magnetic flux density of the ferromagnetic core has significant impact on both to yield stresses forming in MRFs as well as the torque in disengagement clutch operation.Originality/valueDevelopment of the method for analysis of transients electromagnetic and fluid flow phenomena in MRF transducers taking magnetic hysteresis, electric circuits and motion into account. The presented approach is universal and can be successfully applied in other types of MRF electromechanical transducers such as clutch, brakes, rotary and linear dampers.
Modelling of a car starter with permanent magnet commutator motor
Authors: Ciurys M. , Dudzikowski I. , Gierak D. 
Published: May 2009

PurposeThe purpose of this paper is to present a developed modelling method of a car starter with permanent magnet commutator motor.Design/methodology/approachMathematical model, algorithm and computational program of electrical and mechanical quantities transients in the system: battery – car starter with permanent magnet commutator motor and planetary gear – combustion engine were developed. Circuit‐field method was applied. Magnetic quantities determined using time‐stepped finite‐element method (with the help of Maxwell software) were used as the parameters of mathematical model equations in circuital part. Program was developed in the Matlab environment.FindingsThe developed mathematical model, the algorithm and the program enable the computations of transients of electrical and mechanical quantities at different ambient temperature, by different swept capacity of the combustion engine as well as by different battery capacity and different charge ratio.Research limitations/implicationsThe analysis was carried out on an example of four‐cylinder combustion engine. However, the developed modelling method can be used for analysis of different combustion engines start‐up.Practical implicationsThe proposed modelling method is useful for analysis of car starters at the stage of design.Originality/valueThe originality of the work consist in the fact that in the developed model variation of the car starter load torque as well as the variations of the entire mechanical system moment of inertia were taken into account.
Spectral‐element method for high‐speed rotating cylinders
Authors: De Gersem Herbert 
Published: May 2009

PurposeThe purpose of this paper is to offer a fast and reliable discretisation scheme for computing the electromagnetic fields inside a ferromagnetic cylinder, accounting for motional eddy currents under high velocities and accounting for the severe ferromagnetic saturation of the rotor surface.Design/methodology/approachA nonlinear spectral‐element (SE) formulation is developed and compared to existing analytical and finite‐element approaches.FindingsThe proposed SE method results in a higher accuracy, allows for smaller models, avoids upwinding and needs less computation time. Disadvantages are the dense system matrix and the bad condition number.Research limitations/implicationsThe SE approach is only developed and tested for 2D models with a single cylindrical domain.Practical implicationsThe results of the paper may improve the design and optimisation of solid‐rotor induction machines and magnetic bearings.Originality/valueThe paper offers an appropriate solution for a computational problem, which already has been encountered by a large community of researchers and engineers dealing with high‐speed rotating devices.
Accurate minor loops calculation with a modified Jiles‐Atherton hysteresis model
Authors: Leite Jean V. , Benabou Abdelkader , Sadowski Nelson 
Published: May 2009

PurposeAlthough the original Jiles‐Atherton (J‐A) hysteresis model is able to represent a wide range of major hysteresis loops, in particular those of soft magnetic materials, it can produces non‐physical minor loops with its classical equations. The purpose of this paper is to show a modification in the J‐A hysteresis model in order to improve the minor and inner loops representation. The proposed technique allows the J‐A model representing non‐centred minor loops with accuracy as well as improving the symmetric inner loops representation.Design/methodology/approachOnly the irreversible magnetization component is slightly modified keeping unchanged the other model equations and the model simplicity. The high‐variation rate of the irreversible magnetization, which causes the non‐physical behaviour of minor loops, is limited by introducing a new physical parameter linked to the losses. Contrarily to other modifications of the original model found in the literature, the previously knowledge of the magnetic field waveform is not needed in this case.FindingsThe modified hysteresis model is validated by comparison with experimental results. A good agreement is observed between calculations and measurements. The modified model retains the low‐computational effort and numerical simplicity of the original one.Originality/valueThis paper shows that a classical scalar hysteresis model can be suitably used to take into account the minor loops behaviour and be included in a finite element code. The methodology is useful for the design and analysis of electromagnetic devices under distorted flux patterns.
Analysis of the force ripples of a current loaded PMLSM
Authors: Remy Ghislain , Gomand Julien , Tounzi Abdelmounaïm , Barre Pierre‐Jean 
Published: May 2009

PurposeThe purpose of this paper is to present an analysis of the force ripples of an open slot permanent magnet linear synchronous motor (PMLSM). A calculation procedure using 2D finite elements method (2D‐FEM) is then evaluated with experimentations.Design/methodology/approachFirst, the studied PMLSM and its main features are introduced. Then, the 2D‐FEM model used to study the motor is presented. The methods used to calculate the force and the meshing procedures are also highlighted. The calculated no‐load force is compared to measurements. Lastly, the validated model is used to study the influence of the current magnitude on the force ripples at load.FindingsIn addition to the no‐load case, the influence of the current magnitude on these forces is presented.Originality/valueThe paper is orientated with a sound industrial background. For that reason, the impact of the current saturation on the thrust generation is presented via the evolution of the thrust coefficient, which is the force to the RMS currents ratio.
Electromagnetic modelling of short circuited coreplates
Authors: Roger Jean‐Yves , Vrignaud Emmanuel , Henneron Thomas , Benabou Abdelkader , Ducreux Jean‐Pierre 
Published: May 2009

PurposeCoreplates in large generators may suffer from local short circuits. An accurate analysis is required to avoid these failures and detect them when occurring. The purpose of this paper is to develop a lamination stack model compliant with interlamination default analysis.Design/methodology/approachAn electromagnetic model should account for the eddy‐current in the lamination stack. To avoid the modelling of the insulation between the steel sheets, the authors propose to introduce a condition on the fields applied between each sheet. In the case of electric fault between several sheets, the conducting domain, i.e. the sheets, is not simply connected. Then, T‐Ω formulation must be adapted to solve such problem.FindingsThe model allows to account for thin plates, insulating layers and electrical faults in electromagnetic modeling of core plates. This study leads to a first evaluation of eddy current losses in steel laminations with defaults.Research limitations/implicationsThe present study does not take into account thermal effects. The next step will consist in a magneto‐thermal computation. Thus, an electromagnetic finite element software must be coupled with a thermal one. An other improvement will rely on the study of actual situation in order to evaluate the accuracy of industrial sensors and to compare with measurements.Originality/valueThe paper develops a lamination stack model compliant with interlamination default analysis. As far as the authors know, this is the first study on 3D electromagnetic modeling.
Amorphous modular transformers and their 3D magnetic fields calculation with FEM
Authors: Zakrzewski K. , Tomczuk B. , Koteras D. 
Published: May 2009

PurposeThe purpose of this paper is to examine the calculation of magnetic field distribution in the modular amorphous transformers under short‐circuit state including the flux by the voltage supplying. The magnetically asymmetrical transformer (amorphous asymmetrical transformer – AAT) has been compared also with the symmetrical one (amorphous symmetrical transformer – AST).Design/methodology/approach3D field problems were analyzed with total ψ and reduced ϕ potentials within the finite element method (FEM). The calculated fluxes have been verified experimentally.FindingsThe field method which includes voltage excitation is helpful for flux density (B) calculation and winding reactances determination, as well. Calculations and tests yield similar flux distributions in both AST and AAT constructions. One should emphasize that AAT is better for manufacturing and repairing.Research limitations/implicationsOwing to very thin (80 μm) amorphous ribbon, the solid core has been assumed for computer simulations.Originality/valueEmployment of a field method for calculation of the innovative three‐phase amorphous modular transformers. New construction of amorphous transformer, i.e. AAT, has been manufactured at Opole University of Technology.
IM'ing overload: Libraryh3lp to the rescue
Authors: Theiss‐White Danielle , Dale Jenny , Erin Fritch Melia , Bonella Laura , Coleman Jason 
Published: May 2009

PurposeThe purpose of this paper is to describe the new virtual reference system Libraryh3lp, developed to assist librarians with managing multiple instant messaging (IM) patrons at one time.Design/methodology/approachA summary of the main features of the Libraryh3lp system, including setup and reports; and a discussion of how to provide staff training.FindingsThis paper provides an overview of the Libraryh3lp virtual reference platform including what it does, how it works, and its benefits for reference managers.Originality/valueThis paper is useful for information management professionals who are looking for a low‐cost, reliable alternative to current IM software systems.
Promoting collaboration: the physical arrangement of library computers
Authors: Folkestad James E. , Banning James 
Published: May 2009

PurposeThe purpose of this conceptual paper is to highlight the increasing need for libraries to support collaborative learning and to review possible physical arrangements of computer laboratories that are supportive of collaborative learning.Design/methodology/approachA review of the literature was conducted to look at the interface of the concepts of collaborative learning and physical arrangements of computer laboratories.FindingsThe review of the literature surfaced four suggested physical arrangements of computers for collaborative work; kidney‐shaped tables, trapezoid tables and half‐circle tables, and Center for Science, Mathematics and Technology Education sociopetal workstations. After reviewing these arrangements, the paper suggest an additional arrangement with increased potential for face to face collaboration; full‐circle with recessed monitors.Originality/valueAs new libraries are built and others renovated, these five physical arrangements provide for ways that computer laboratories can be designed to meeting the increasing need for user collaboration.
Accounting and the moral economy of illness in Victorian England: the Newcastle Infirmary
Authors: Holden Andy , Funnell Warwick , Oldroyd David 
Published: May 2009

PurposeThis paper aims to examine the Victorian attitude to the poor by focussing on the health care provided at a large provincial hospital, the Newcastle Infirmary.Design/methodology/approachThe archives of the Newcastle Infirmary are reviewed alongside the local trade directories. These primary sources are examined in conjunction with the writings of contemporary social theorists on poverty.FindingsAt a time when poverty was seen as a sin, an act against God, it would be easy to assume that the Victorians faced no moral dilemma in dismissing the poor, particularly what were seen as the “undeserving poor”, out of hand. Yet, the paper observes how accounting was used both to persuade the wealthier citizens to contribute funds and to enable the hospital to exercise compassion in treating paupers despite this being prohibited under the hospital's rules. Such a policy conflicted with the dominant utilitarian view of society, which emphasised the twin pillars of economic expediency and self‐help.Research limitations/implicationsMore case studies are needed of other hospitals to ascertain how typical the Newcastle Infirmary was of the voluntary hospital sector as a whole.Originality/valueAlthough many histories of British hospitals exist and some have examined how accounting was used to manage within these institutions, the concern has not been with accounting as a moral practice.
Stakeholder perspectives on a financial sector legitimation process
Authors: O'Sullivan Niamh , O'Dwyer Brendan 
Published: May 2009

PurposeThe purpose of this paper is to present an in‐depth, context rich, and stakeholder‐focused perspective on the legitimation dynamics surrounding the initiation and evolution of one of the key financial sector environmental and social responsibility initiatives in recent years, the Equator Principles.Design/methodology/approachThe paper draws on a combination of in‐depth interviews with non‐governmental organization (NGO) leaders, extensive documentary analysis and participant observation in order to understand and explain, from an NGO perspective, the use of the Equator Principles as a central element in an attempt to legitimise financial institutions' project finance activities. Key aspects of legitimacy theory are used to theoretically frame the analysis.FindingsThe paper reveals and analyses the process through which campaigning NGOs conferred a nominal level of legitimacy on financial institutions' project finance activities. It proceeds to unveil how and why this attained legitimacy unravelled. A perceived lack of accountability at an institutional, organisational and individual project level is identified as a central reason for this reduction in legitimacy.Research limitations/implicationsThe paper primarily focuses on one side of the story of the dynamics of the legitimation process underpinning the evolution of the Equator Principles until 2006. Future research could focus on obtaining and theorising financial institution perspectives on the Equator Principles' development, implementation, and progression as well as analysing developments beyond 2006.Originality/valueThe paper advances our understanding of the dynamics of legitimation processes. These dynamics are studied from the perspective of a key “relevant public” thereby prioritising perceptions that are largely absent from corporate social accountability research seeking to empirically inform legitimacy theory.
Initiating sustainable development reporting: evidence from New Zealand
Authors: Bebbington Jan , Higgins Colin , Frame Bob 
Published: May 2009

PurposeThe purpose of this paper is to document organizations' self descriptions of why they initiated sustainable development (SD) reporting and explore these explanations using an institutional theory framework.Design/methodology/approachConstructs organizational narratives from semi‐structured in‐depth interviews with reporting champions who participated in an SD reporting workshop series. The narratives are analysed using institutional theory to explore how regulatory, normative and cognitive institutions combine with organizational dynamics to influence SD reporting activity.FindingsFor these particular organizations, choosing to engage in reporting appears not to be a rational choice. Rather reporting is initiated because it has come to be an accepted part of pursuing a differentiation strategy, it offers some contribution to existing business challenges, and organizations value the rewards it offers. This rationale constitutes a cognitive mechanism within institutional theory.Originality/valueThe paper provides useful information on initiating sustainable development reporting based on organizations' self descriptions.
Currency options trading practices and the construction and governance of operational risk
Authors: Mahama Habib , Yu Ming Chen 
Published: May 2009

PurposeRecent failures and scandals in the banking and financial services industry have served as catalysts for anxiety about operational risk. In particular, the Basel II accord emphasises the need to develop methodologies for assessing and managing this category of risk. However, operational risk is said to be an elusive and problematic concept. This paper aims to examine how certain events in the banking and financial services industry become enframed and constructed as operational risk and how such risk is managed.Design/methodology/approachThe paper draws on the sociology of risk literature to analyse how an “unauthorised trading” event (and associated losses) that occurred in the currency options trading desk of the National Australia Bank (NAB) was enframed and constructed as operational risk. Data are gathered through metadiscourse analysis of textual materials relating to this event.FindingsThe analysis reveals the social and institutional mechanisms underlying the construction of risk and the contested nature of risk knowledge. In particular, it highlights the significant role of media discourse in articulating risk claims and dominating public discourse about risk. It also highlights the moral character of the concept of risk and how the moralising of risk discourse leads to the creation of particular forms of subjectivities and the operationalisation of certain risk management rationalities in NAB.Originality/valueThe paper will be helpful in improving researchers' and practitioners' understanding of how, in a given field of possibilities, particular events become constructed as operational risk.
A question of economics
Authors: Oakman B.N. 
Published: May 2009

PurposeThe purpose of this paper is to reflect on unconsidered ethical implications of an allegedly strictly commercial decision.Design/methodology/approachFictional poem.FindingsMeditation on how we may ignore an ethical issue if profit is enhanced by so doing.Research limitations/implicationsStimulate thought on the implications of unconstrained profit maximisation.Originality/valueAn individual comment and a questioning of deception as a tool of profit maximisation.