bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eddy current losses of segmented Nd‐Fe‐B sintered magnets without insulation under various conditions
Authors: Takahashi Norio , Shinagawa Hirofumi , Miyagi Daisuke , Doi Yuhito 
Published: December 2011

PurposeThe purpose of this paper is to examine the mechanism of the increase or decrease of eddy current loss of the segmented Nd‐Fe‐B sintered magnets without insulation, and the effects of parameters on such a phenomenon are discussed.Design/methodology/approachThe measured contact resistance is used in the finite element analysis.FindingsIt is shown that the eddy current loss in a magnet shows the peak value when the number of segments are increased at 40 kHz, but this property is changed at low frequency (10 kHz). Its tendency is changed by the contact resistance and the permeance (surrounding iron core).Originality/valueThe reason of a curious property of eddy current loss of segmented magnets is clearly explained by examining the eddy current distribution at various contact resistances.
Measurements and simulations of the heat transfer on end windings of an induction machine
Authors: Hettegger Martin , Streibl Bernhard , Bíró Oszkár , Neudorfer Harald 
Published: December 2011

PurposeFor an accurate simulation of the temperature distribution inside an electrical machine a method for deriving the convective heat transfer coefficient numerically would be desirable. The purpose of this paper is to present a reliable simulation setup, which is able to reproduce the measured convective heat transfer coefficient at certain spots on the end windings of an electric machine.Design/methodology/approachThe heat flux density on certain spots on the end windings of an induction motor have been measured with heat flux sensors, in order to find out the convective heat transfer coefficient. To identify the air mass flow inside a cooling duct of an encapsulated cooling circuit during the operation of the motor, the pressure loss inside the duct has been measured. The measured data for temperature and air mass flow have been used as boundary conditions for the identification of the convective heat transfer coefficient with a commercial software for computational fluid dynamics (CFD).FindingsThe measured data for the local convective heat transfer coefficients have been compared to the results of the numerical simulation for various rotational velocities. The quality of the simulated convective heat transfer coefficient depending on the rotational velocity meets the measured values. Owing to the used simplified model, the quantity of the measured values differ strongly around the simulated coefficient for the convective heat transfer.Originality/valueThe derivation of the convective heat transfer is a challenging subject in CFD but has become more reliable with the invention of the SST and the SAS‐SST turbulence model. In the present work, measurements on the end windings have been compared to simulation results derived with the SAS‐SST turbulence model.
Computation of the noise radiation of an induction machine using 3D FEM/BEM
Authors: Weilharter Bernhard , Bíró Oszkár , Lang Hermann , Rainer Siegfried 
Published: December 2011

PurposeThe purpose of this paper is to set up a comprehensive numerical approach to estimate the 3D structural vibration and noise radiation of an induction machine.Design/methodology/approachThe rotating force waves, acting in the air gap of an induction machine and obtained by an electromagnetic finite element multi‐slice simulation, are applied to the 3D structural finite element model and a structural harmonic simulation is performed. The sound emission due to the vibration of the surface of the machine is computed with a 3D boundary element model.FindingsThe paper outlays problematic issues when setting up the numerical models, i.e. the structural finite element model. The material properties strongly affect the structural behaviour and therefore the radiated noise.Originality/valueThe 3D force distribution in the air gap and the resulting vibrations are computed. The structural behaviour, i.e. the different vibrational behaviour of stator and surface is discussed. The correlation of the structural vibrations and the noise radiation is investigated.
Acceleration of moment method using CUDA
Authors: Kiss Imre , Pávó József , Gyimóthy Szabolcs 
Published: December 2011

PurposeThe purpose of this paper is to accelerate the time‐consuming task of assembling the impedance matrix resulting from the discretization of integral equations by the moment method, accelerated using massively parallel processing scheme.Design/methodology/approachThis paper provides several approaches for the implementation of moment method on compute unified device architecture (CUDA) capable general purpose video cards, as well as giving general implementation design patterns and a good overview on the topic.FindingsThe proposed method seems to be efficient in the light of the presented numerical results.Originality/valueThe subject of the paper is an evolving, considerably new aspect among computation techniques which could be of high interest for the scientific community.
Meshless local Petrov‐Galerkin (MLPG) methods in quantum mechanics
Authors: Nicomedes Williams L. , Mesquita Renato C. , Moreira Fernando J.S. 
Published: December 2011

PurposeThe purpose of this paper is to solve both eigenvalue and boundary value problems coming from the field of quantum mechanics through the application of meshless methods, particularly the one known as meshless local Petrov‐Galerkin (MLPG).Design/methodology/approachRegarding eigenvalue problems, the authors show how to apply MLPG to the time‐independent Schrödinger equation stated in three dimensions. Through a special procedure, the numerical integration of weak forms is carried out only for internal nodes. The boundary conditions are enforced through a collocation method. The final result is a generalized eigenvalue problem, which is readily solved for the energy levels. An example of boundary value problem is described by the time‐dependent nonlinear Schrödinger equation. The weak forms are again stated only for internal nodes, whereas the same collocation scheme is employed to enforce the boundary conditions. The nonlinearity is dealt with by a predictor‐corrector scheme.FindingsResults show that the combination of MLPG and a collocation scheme works very well. The numerical results are compared to those provided by analytical solutions, exhibiting good agreement.Originality/valueThe flexibility of MLPG is made explicit. There are different ways to obtain the weak forms, and the boundary conditions can be enforced through a number of ways, the collocation scheme being just one of them. The shape functions used to approximate the solution can incorporate modifications that reflect some feature of the problem, like periodic boundary conditions. The value of this work resides in the fact that problems from other areas of electromagnetism can be attacked by the very same ideas herein described.
Regularized inversion of a distributed point source model for the reconstruction of defects in eddy current imaging
Authors: Bausson S. , Thomas V. , Joubert P.‐Y. , Blanc‐Féraud L. , Darbon J. , Aubert G. 
Published: December 2011

PurposeThe inverse problem in the eddy current (EC) imaging of metallic parts is an ill‐posed problem. The purpose of the paper is to compare the performances of regularized algorithms to estimate the 3D geometry of a surface breaking defect.Design/methodology/approachThe forward problem is solved using a mesh‐free semi‐analytical model, the distributed point source method, which allows EC data to be simulated according to the shape of the considered defect. The inverse problem is solved using two regularization methods, namely the Tikhonov (l2) and the 3D total variation (tv) methods, implemented with first‐ and second‐order algorithms. The inversion performances were evaluated in terms of both mean square error (MSE) and computation time, while considering additive white and colored noise, respectively, standing for acquisition errors and model errors.FindingsIn presence of colored noise, the authors found out that first‐ and second‐order methods provide approximately the same result according to the SEs obtained while estimating the defect voxels. Nevertheless, in comparison with (l2), the (tv) regularization was proved to decrease the MSE by 10 voxels, at the cost of less than twice the computational effort.Originality/valueIn this paper, an easy to implement mesh‐free model, based on virtual defect current sources, was used to generated EC data relative to a defect positioned at the surface of a metallic part. A 3D total variation regularization approach was used in combination with the proposed model, which appears to be well suited to the reconstruction of volumic defects.
Virtual power principle and Maxwell's tensor: which comes first?
Authors: Bossavit Alain 
Published: December 2011

PurposeThe purpose of this paper is to clarify the status of Maxwell's tensor with respect to the virtual power principle (VPP).Design/methodology/approachMathematical analysis is employed.FindingsThe VPP, logically stronger, is more fundamental. Maxwell's tensor derives from it, under further restrictive assumptions, and hence, its range of applicability is limited. In particular, it fails to deal with some aspects of magnetostriction.Originality/valueThe paper shows that when magnetic constitutive laws depend, locally, on strain, the body force is not, as a rule, the divergence of the Maxwell tensor. People who intend to compute forces this way should be wary of that.
A hybrid multiobjective differential evolution method for electromagnetic device optimization
Authors: Alotto Piergiorgio 
Published: December 2011

PurposeThe purpose of this paper is to show that the performance of differential evolution (DE) can be substantially improved by a combination of techniques. These enhancements are applicable to both single and multiobjective problems. Their combined use allows the optimization of complex 3D electromagnetic devices.Design/methodology/approachDE is improved by a combination of techniques which are applied in a cascade way and their single and combined effect is tested on well‐known benchmarks and domain‐specific applications.FindingsIt is shown that the combined use of enhancement techniques provides substantial improvements in the speed of convergence for both single and multiobjective problems.Research limitations/implicationsThe increased speed of convergence may come at the price of a somewhat decreased robustness. However, such behavior is justified by the CPU time constraints under which the optimization has to be performed.Practical implicationsThe proposed approach appears to be an efficient general purpose stochastic optimizer for electromagnetic design problems.Originality/valueThis paper explorers the combined use of many of the most recent and successful algorithmic improvements to DE and applies them to both single and multiobjective problems.
A robust objective function for topology optimization
Authors: Li Min , Lowther David A. 
Published: December 2011

PurposeRobust design is very important for manufacturers to ensure the quality of the finished product. Therefore, a robustness measure is needed for the topological design of electromagnetic problems which may be sensitive to parameter variations. The purpose of this paper is to propose a robust objective function for topological design problems.Design/methodology/approachIn this paper, a robust objective function for topology optimization is defined on an uncertainty set using the worst case analysis. The robustness of a topological design is defined as the worst response due to the variations of the location of the topology change. The approach is based on the definition of a topological gradient.FindingsThe robust topology optimization (RTO) was applied to eddy current crack reconstruction problems. The numerical applications showed that this method can provide more reliable results for the reconstruction in the presence of significant noise in the measured signal.Research limitations/implicationsThe RTO may be applied to some more complicated design problems; however large computational costs may result.Originality/valueThis paper has defined a robustness metric for topology design and a robust design model is proposed for topology optimization problems.
Nonlinear magnetostatic BEM formulation using one unknown double layer charge
Authors: Ishibashi Kazuhisa , Andjelic Zoran 
Published: December 2011

PurposeThe purpose of this paper is to solve generic magnetostatic problems by BEM, by studying how to use a boundary integral equation (BIE) with the double layer charge as unknown derived from the scalar potential.Design/methodology/approachSince the double layer charge produces only the potential gap without disturbing the normal magnetic flux density, the field is accurately formulated even by one BIE with one unknown. Once the double layer charge is determined, Biot‐Savart's law gives easily the magnetic flux density.FindingsThe BIE using double layer charge is capable of treating robustly geometrical singularities at edges and corners. It is also capable of solving the problems with extremely high magnetic permeability.Originality/valueThe proposed BIE contains only the double layer charge while the conventional equations derived from the scalar potential contain the single and double layer charges as unknowns. In the multiply connected problems, the excitation potential in the material is derived from the magnetomotive force to represent the circulating fields due to multiply connected exciting currents.
Electromechanical analysis of end windings in turbo generators
Authors: Albanese Raffaele , Calvano Flavio , DalMut Giorgio , Ferraioli Fabrizio , Formisano Alessandro , Marignetti Fabrizio , Martone Raffaele , Rubinacci Guglielmo , Tamburrino Antonelle , Ventre Salvatore 
Published: December 2011

PurposeThe purpose of this paper is to present a numerical approach for the computation of 3D magnetic fields in rotating electrical machines. The technique is suitable for the computation of flux densities and forces in the end windings of large synchronous turbo generators (TG).Design/methodology/approachThe magnetostatic FEM model of the generator end windings is carried out for different displacements of the rotor axis to the stator magnetomotive force (MMF) axis. The method is based on a parallel integral formulation allowing to substantially reduce the computational effort.FindingsThe computational model requires only the discretization of magnetic materials and conductors and is fast enough for carrying out 3D analyses on a time scale fast enough for the needs of the designer. As far as the present application is concerned, the analysis of a synchronous generator in the class of 300‐400 MVA has shown that the most stressed elements of the armature conductors are those closer to the stator ends. The study demonstrates that the maximum stress component on the end windings is axial and is achieved when the MMF is aligned to the direct axis.Originality/valueThe present approach combining an efficient integral formulation, the sparsification of the relevant matrices and the parallel implementation of the related algorithms gives rise to an original computational tool that allows a more accurate description of the machine in comparison to other numerical simulations that can be found in the literature.
Hidden metallic object localization by using giant magnetic resistor sensors
Authors: Renhart Werner , Bellina Mario , Magele Christian , Köstinger Alice 
Published: December 2011

PurposeThe purpose of this paper is to achieve a very accurate localization of hidden metallic objects in human medicine applications.Design/methodology/approachThe proposed methodology takes advantage of the eddy current effect within a metallic object. Its magnetic reaction field will be measured, e.g. with giant magnetic resistor (GMR) sensors.FindingsA comparison of measurements and numerical results obtained by finite element computations demonstrate the reliability and positively gives a clue about the feasibility of the suggested method.Research limitations/implicationsWhile measuring noisy signals, the use of a lock‐in amplifier is rather expensive; especially, in applications with a high number of GMR sensors the use of channel multiplexer must be considered, which again may generate noise.Originality/valueThe paper shows how appropriate shielding of external fields in the measurement setup ensures results of satisfying quality.
Crimea 2011 International Conference: Libraries and Information Resources in the Modern World of Science, Culture, Education and Business
Authors: Kesselman Martin 
Published: December 2011

PurposeThe purpose of this paper is to provide a conference report of Crimea 2011 that the author attended in June 2011. The conference is held in Sudak, Crimea, Ukraine, each year and is organized by the Russian National Public Library of Science and Technology.Design/methodology/approachThe author attended the conference and compiled a report.FindingsThe Crimea Conference has a special relationship with IFLA and highlights library developments in Russia and the former Soviet Union countries.Originality/valueThis is an original review of the conference, which is the premiere annual library conference for Russian and Ukrainian librarians, as well as librarians from the former Soviet Union countries. For librarians with a focus on Russian area studies and Eastern Europe, the Crimea is an event not to be missed.
BookExpo America 2011
Authors: Cassell Kay 
Published: December 2011

PurposeThe purpose of this paper is to report on e‐book readers and e‐book technology at the BookExpo America conference held in New York City, May 2011.Design/methodology/approachThe author attended the conference and compiled a report.FindingsInterest in e‐books is growing and the many companies offering e‐book readers, enhanced e‐books and technology to produce e‐books is increasing.Originality/valueThis is an up‐to‐date report on what is happening in the e‐book industry.
What are universities doing here? Migrating traditional dissertations into ETDs in Iran
Authors: Ardalan Reza , Feyzbaksh Omolbanin 
Published: December 2011

PurposeMany universities and libraries throughout the world are now making digitized versions of traditional (print) dissertations available online. Some of these institutions have even gone so far as to completely eliminate printed copies. The purpose of this paper is to examine the extent of Electronic Theses and Dissertations (ETDs) in Iran and elsewhere.Design/methodology/approachThe paper notes that many theses and dissertations are now sitting on shelves, unread, in our libraries. Electronic publication can make these works accessible to students, researchers, and others who perhaps lack time, search capabilities, or finances. The paper looks at what universities are doing about the problem, and summarizes the current position in Iran university libraries.FindingsA growing realization has emerged among those working on ETDs in Iran that it is critically important that libraries remain not just involved, but centrally positioned in the development of the national information infrastructure.Practical implicationsThe paper shows that the future of E‐theses and of archiving and searching in general depends on institutions being able to deliver top quality services, with a high degree of interoperability. This means, among other things, that systems must continue to be developed and they must be able to handle many different types of digital objects.Originality/valueThe paper claims that as we prepare students for scholarship in the twenty‐first century, Iran 1400, for example, it is imperative that librarians consider how to manage these important new forms of writing.
Publishing in international journals
Authors: Wagner Beverly A. 
Published: December 2011

PurposeThe purpose of this paper is to set out guidelines to de‐mystify the publication process and increase opportunities for successful publication.Design/methodology/approachAn introspective method is employed based upon the author's experience as a reviewer and editor.FindingsFindings highlight some of the challenges facing researchers when writing research papers, pitfalls on the path to publication and possible remedial actions.Practical implicationsInformation gained may go some way to improve writing and increase the possibly of publication in international journals.Originality/valueThis paper is based on personal experience. The more information available to researchers regarding requirements for successful publication as well as greater transparency of the review process will improve writing quality and ultimately progress debate within academic disciplines.
Challenges in collaborative writing: addressing authorship attribution
Authors: Zutshi Ambika , McDonald Gael , Kalejs Linda 
Published: December 2011

PurposeIncreasing pressure to enhance research coupled with a desire for a broadening of academic input, are prompting greater levels of collaboration. Research collaboration can generate notable benefits but can also pose a variety of challenges. The purpose of this paper is to explore the reasons, facilitators, benefits and challenges of academic collaboration. It also provides suggestions to manage identifiable risks and enhance team dynamics.Design/methodology/approachThis is a conceptual paper exploring prior literature in relation to the contentious points of research collaboration, particularly in regard to authorship attribution.FindingsThe authors present two checklists that researchers can utilise to ensure the successful completion of collaborative projects. The checklists incorporate the main factors required for effective collaborative work and research, and form a foundation for discussion among team members.Originality/valueThe paper draws upon experiences, observations, academic literature and protocols, and provides strategies and recommendations to enhance collaboration and authorship attribution. The two checklists presented in the paper are value‐adding for team members.
Research process, report structure and journal outlets in scholarly studies
Authors: Svensson Göran 
Published: December 2011

PurposeThe purpose of this paper is to describe the interconnection between the research process, the report structure and journal outlets in scholarly studies.Design/methodology/approachConceptual frameworks to link the research process with the report structure, and in turn with journal outlets, are presented.FindingsThese indicate that the research process and the awareness of the components of the report structure as well as potential journal outlets may at an early stage uncover any pitfalls and flaws in one's scholarly studies in academia.Research limitations/implicationsA transparent understanding and foresight of what is ahead in, and interconnected between, the elements of the research process, the components of the report structure and the potential journal outlets are crucial to enhance the ultimate scholarly performance. The discussion is in part limited to the commonly applied “deductive” research process in academia, though most parts also are applicable to the “inductive” research process.Practical implicationsIt is important that the elements of the scholarly research process and the components of the report structure are thoroughly thought out in detail before too much investment in time and resources, as well as intellectual effort, have been made in order to avoid frustration and discontent. In addition, the potential journal outlets also need to be considered at an early stage of research.Originality/valueTransparent understanding and foresight of research processes, report structures and journal outlets provide essential and valuable insights for scholars. The author has striven to show that realizing the link between the scholarly research process, the scholarly report structure and the potential journal outlets available will assist in efforts to perform and communicate the outcome of scholarly studies.