bluuebunny/crossref_metadata_2025_split huggingface dataset:
The impact of foreign direct investment on total factor productivity growth
Authors: Tanna Sailesh 
Published: January 2009

PurposeThe purpose of this study is to examine the association between inward foreign direct investment (FDI) and bank level productivity changes.Design/methodology/approachThe paper uses an international sample of 566 publicly quoted commercial banks operating in 75 countries, covering the period 2000‐2004. The empirical analysis is conducted in two stages. First, a non‐parametric Malmquist analysis is employed to decompose total factor productivity (TFP) change of banks into pure efficiency, scale efficiency and technological change. Then, panel regressions are performed to identify the productivity impact of FDI while controlling for relevant bank‐specific and country‐specific characteristics.FindingsThe results indicate that inward FDI has a negative short‐term level effect but a positive long‐term rate effect on TFP change, which is consistent with the evidence from the Malmquist analysis suggesting that banks experience episodes of technical regress and progress.Originality/valueThe paper explores for the first time the link between FDI and bank level total factor productivity, hypothesising that aggregate FDI inflows yield productivity changes in the banking sector as part of the overall environmental effect on the economy, and providing supportive cross‐country evidence.
Development of accuracy‐enhanced time‐domain schemes for bi‐isotropic media and chiral metamaterials
Authors: Bouzianas George , Kantartzis Nikolaos V. , Tsiboukis Theodoros D. 
Published: January 2009

PurposeThe purpose of this paper is to conduct the accurate analysis and systematic characterisation of realistic generalised bi‐isotropic and lossy chiral metamaterial 3D applications at microwave frequencies.Design/methodology/approachAn accuracy‐adjustable time‐domain methodology is developed. The technique uses a convex combination of optimal stencils along with an advanced wavefield decomposition to precisely model the highly dispersive, double negative nature of chirality and constitutive parameters. Furthermore, open‐region radiation or scattering problems are terminated through a pertinently modified perfectly matched layer (PML) of variable depth.FindingsThe paper reveals that the proposed algorithm is versatile in the generation of adaptive stencils that attain a very natural way of manipulating continuity conditions at material interfaces. Thus, when periodic structures with split‐ring resonators are to be modelled, the resulting schemes attain optimal precision and minimised dispersion errors. Numerical validation proves these merits via diverse demanding structures of curved shape and multiple layers.Originality/valueThe new technique introduces a family of piecewise polynomials and spatial discretization criteria which lead to additional degrees of freedom for the discrete vectors of the application. In this manner, grid dual is intrinsically embedded in the physical profile of the problem, without resorting to the simplified conventions of other approaches. Moreover, singularity points or demanding geometric discontinuities are properly manipulated, even via coarse lattice resolutions. Thus, the overall accuracy is significantly improved and the computational requirements remain in very logical and affordable levels.
On the shielding effectiveness of enclosures for transient near‐field sources
Authors: Möller Christian , Klinkenbusch Ludger 
Published: January 2009

PurposeThe purpose of this paper is to introduce and investigate a useful and practicable definition of the shielding effectiveness (SE) of enclosures for transient near‐field sources.Design/methodology/approachThe transient SE is defined as the ratio of electromagnetic energies absorbed by an unshielded and by a shielded vanishingly small load. That ratio can be found analytically by means of a suitable spherical‐multipole approach. The SE can be reduced to easily measurable values of frequency‐domain electric and magnetic fields.FindingsSuitable factors are introduced which depend on the frequency and on the distance between the dipole source and the measurement point inside the shield. The proposed definition has been analytically evaluated and validated for the case of a cylindrical shield.Originality/valueThe paper extends a recently proposed definition of the transient SE for plane‐wave incidence to the case of a dipole near‐field source.
Current displacement in plane rectangular conductor
Authors: Ole Fichte Lars , Clemens Markus 
Published: January 2009

PurposeThe purpose of this paper is to provide an analytical solution to the plane eddy current problem inside conductive bars with rectangular cross‐section.Design/methodology/approachEddy currents inside conductive materials have been investigated for a very long time, using measurements and mathematical modelling. This paper provides an analytical solution to the plane eddy current problem inside conductive bars with rectangular cross‐section.FindingsThe paper's approach solves the given plane eddy current problem with the boundary integral equation method. The Helmholtz' equation for vector potential inside the rectangle is solved by separation. The solution is inserted into the remaining boundary integral equation for the exterior vector potential in the domain surrounding the conductor yielding a system of linear equations. Results match existing solutions.Originality/valueThe method discussed provides a new way to solve the EC problem and is slightly faster than the available commercial codes; yet, it is limited to rectangular bars of cross‐section.
Nonlinear eddy current analysis by line integral equations utilizing integral formulas of electromagnetic fields
Authors: Ishibashi Kazuhisa 
Published: January 2009

PurposeThe purpose of this paper is to supply a numerical analysis tool to solve eddy currents induced in nonlinear materials such as steel by boundary element method (BEM), and then apply it to design and analysis of power devices.Design/methodology/approachUtilizing integral formulas derived on the basis of rapid attenuation of the electromagnetic fields, the paper formulates eddy currents in steel. In the formulation, nonlinear terms are regarded as virtual sources, which are improved iteratively with the electromagnetic fields on the surface. The periodic electromagnetic fields are expanded in Fourier series and each harmonic is analyzed by BEM. The surface and internal electromagnetic fields are obtained numerically one after the other until convergence by the Newton‐Raphson method.FindingsIt is confirmed that this approach gives accurate solutions with meshes much larger than the skin depth and therefore is adequate to apply to a large‐scale application.Research limitations/implicationsThe eddy current is formulated by utilizing the impedance boundary condition in order to meet a large‐scale application, and so solutions near the edge are poor. In the case of better solutions being required, some modifications are necessary.Originality/valueTo lessen computer memory consumption, the parallel component of the currents to the steel surface is analyzed as a 2D problem and the normal component is obtained from the parallel component. One 2D equation for one analyzing region is discretized by dividing the region into layers adaptively and then solved. Next, another is solved sequentially. This method gives a compatible numerical analysis tool with finite element method.
Reduction of eddy current loss in magnetoplated wire
Authors: Mizuno Tsutomu , Enoki Shigemi , Suzuki Takayuki , Asahina Takashi , Noda Masahiro , Shinagawa Hiroki 
Published: January 2009

PurposeThe purpose of this paper is to reduce eddy current loss in a wire that is affected by an alternating field passing through it. This allows the efficiency of transformers to be upgraded and the quality factor in coils to be increased.Design/methodology/approachThe use of a magnetoplated wire (MPW) is proposed to reduce eddy current loss in a wire. An MPW is a copper wire (COW) whose circumference is plated with a magnetic thin film. In additional, the theoretical equation for eddy current loss in an MPW is derived for ease of analysis.FindingsThe eddy current loss in an MPW is calculated as a function of the relative permeability and resistivity of its magnetic thin film to reduce the resistance due to the proximity effect of a coil. The eddy current loss in an MPW whose magnetic thin film has a relative permeability of 500 and a resistivity of 0.12 μΩm can be reduced to 4 percent that of COW at a frequency of 1 MHz.Originality/valueThe use of MPW can be expected to upgrade the efficiency of transformers and to increase the quality factor in coils.
Eddy current brake with two pole pairs
Authors: Baum Eckhard , Eberhardt Stefan 
Published: January 2009

PurposeThe purpose of this paper is to derive a force‐velocity characteristic for an eddy current brake with minor computational effort.Design/methodology/approachThe speed range is split into two domains. While in the low‐speed domain it is possible to achieve a closed form expression for the force‐velocity characteristic in the high‐speed region approximations have to be introduced.FindingsThe derived relation for the force‐velocity characteristic has been compared with measurement results. The comparison shows that the approach yields good results for not too large air gaps.Originality/valueA combination of analytical and approximative methods has been used for the determination of the force‐velocity characteristic of an eddy current brake with two pole pairs.
3D movement simulation technique in FVM method application to eddy current non destructive testing
Authors: Cheriet Ahmed , Feliachi Mouloud , Mohamed Mimoune Souri 
Published: January 2009

PurposeThe purpose of this paper is to propose modelling 3D eddy current non destructive testing (EC NDT) problems by the finite volume method (FVM). Furthermore, the movement of the probe coil is taken into account.Design/methodology/approachThe nonconforming mesh technique is used to handle the displacement of the probe coil. Thus, the whole problem is divided into two parts; moving part (probe coil) and fixed part (specimen with crack), and then each part meshes independently. A computer code is built under Matlab program to generate 3D nonconforming mesh, to calculate magnetic and electric potentials and to evaluate the impedance change of the coil due to the presence of the crack.FindingsThe JSAEM No. 6 problem is used to test the proposed method. The calculated values of the impedance change of the probe coil due to the presence of crack, shows the efficiency of the developed software. A small difference is obtained between calculated values and measured values.Originality/valueThe paper introduces the FVM in solving EC NDT problems where the probe displacement is taken into account.
Magnetic field analysis under complex approximation taking account of two‐dimensional magnetic properties
Authors: Todaka Takashi , Nakanoue Kenji , Enokizono Masato 
Published: January 2009

PurposeThe purpose of this paper is to reduce computation time of magnetic characteristic analysis considering 2D vector magnetic properties.Design/methodology/approachThe paper proposes a complex E&S modelling with assumption that both flux density and field strength waveforms are sinusoidal. The computation time of the complex E&S modeling becomes 1/10 in comparison with one of the conventional E&S modeling. This modeling is applicable up to 1.4 T of the local magnetic flux density condition in the case of non‐oriented magnetic materials.FindingsIn the results of the magnetic field analyses of a linear‐induction motor model core by means of the finite element method taking account of the complex E&S modeling, the distributions of the flux density and the field strength were able to be approximately analyzed and their phase differences in space were represented. The results of the magnetic characteristic analysis of the linear‐induction motor showed that the teeth‐end shape had large influences on the thrust and cogging.Practical implicationsThis technique helps to know approximately local vector magnetic properties in core materials. This modeling is very useful for magnetic core design taking account of the simplified 2D vector magnetic properties.Originality/valueThe method presented in this paper enables expression of the simplified 2D vector magnetic properties in magnetic field analyses. The computation time can be considerably reduced in comparison with the conventional method.
Numerical modelling of electrostatic force microscopes considering charge and dielectric constant
Authors: Binit Bala Uzzal , Greiff Michael , Preisner Thomas , Mathis Wolfgang 
Published: January 2009

PurposeThe purpose of this paper is to present a hybrid numerical simulation approach for the calculation of potential and electric field distribution considering charge and dielectric constant.Design/methodology/approachEach numerical method has its own advantages and disadvantages. The idea is to overcome the disadvantages of the corresponding numerical method by coupling with other numerical methods. An augmented finite element method (FEM), linear FEM and boundary element method are used with an efficient coupling.FindingsThe simulation model of microstructured devices is not so simple. During the simulation various types of problems will occur. It is found that by using several numerical methods these problems can be overcome and the calculation can be performed efficiently.Research limitations/implicationsThe present approach can be applied in 2D cases. But, in 3D cases the calculation of augmented FEM in a spherical coordinate becomes quite elaborate.Practical implicationsThe proposed hybrid numerical simulation approach can be applied for the simulation of the electrostatic force microscope (EFM) which is a very high‐resolution measuring tool in nanotechnology. This approach can be applied also to other micro‐electro‐mechanical systems.Originality/valueSince the scanning process of the EFM is dynamic, it requires the updating of the FEM mesh in each calculation time step. In the present paper, the mesh updating is achieved by an arbitrary Lagrangian‐Eulerian (ALE) method. The proposed numerical approach can be applied for the simulation of the EFM including this remeshing algorithm ALE.
Numerical computation of magnetic fields applied to magnetic force microscopy
Authors: Preisner Thomas , Greiff Michael , Binit Bala Uzzal , Mathis Wolfgang 
Published: January 2009

PurposeThe purpose of this paper is to introduce a method which allows the calculation of the interactions of tip and sample of a magnetic force microscope as a first step to increase the accuracy of this technique.Design/methodology/approachThe emerging magnetic interactions between the cantilever tip and an arbitrary magnetized sample can be evaluated by the use of several numerical methods. For modelling this magnetically and mechanically coupled multiscale problem the finite element method is implemented.FindingsThe evaluated magnetic fields interact in such a manner that a constructive overlap at the tip apex occurs. This leads to attractive forces acting on the cantilever.Research limitations/implicationsIn order to include the magneto‐mechanical coupling, the implementation of a detailed force calculation is necessary. Furthermore, a hysteresis model is not yet considered.Practical implicationsMagnetic force microscopy is a very sensitive technique. For instance, ideally the end of the tip consists of only one atom, but this is not realizable. Measurement errors cannot be avoided. This approach is the first step in developing an opportunity to soften them.Originality/valueOne opportunity to verify real‐time magnetic force microscope measurements is the comparison with theoretical considerations and calculations of the occurring magnetic distribution by using this technique. For this reason this paper deals with a new micromagnetic model to simulate the interactions between tip and sample of a scanning process of a magnetic force microscope.
Stationary multi‐species models of the electric corona discharge in oxygen
Authors: Zhang Jiacheng , Adamiak Kazimierz 
Published: January 2009

PurposeThe purpose of this paper is to present a novel numerical algorithm, which can be used to simulate the stationary electric corona discharge in oxygen including some number of ionic species and ionic reactions.Design/methodology/approachDifferential equations governing distribution of the electric field and space charge density for all ionic species have been solved using different numerical techniques: finite element method, method of characteristics (MoC) and donor‐cell method (DCM). Triangular discretization with linear interpolation of solution has been used.FindingsThickness of the ionisation layer in oxygen under normal conditions is in the order of a few hundred micrometers. Most electrons are attached to the neutral oxygen molecules forming negative ions in the drift zone. The current density on the ground plate basically follows the Warburg curve, but the DCM predicts a smooth current density distribution, while in the MoC the current density abruptly drops to zero at some radial distance.Originality/valueThis is the first attempt to solve this problem in the 2D point‐plane configuration. The results can lead to better understanding of all processes occurring in the corona discharge and provide information about density and distribution of different ionic species and current densities.
Modelling of Seebeck effect in electron beam deep welding of dissimilar metals
Authors: Ziolkowski Marek , Brauer Hartmut 
Published: January 2009

PurposeThe purpose of this paper is to present a 3D model of deep welding of dissimilar metals and to show how to model the electron beam deflection due to thermoelectric fields caused by temperature gradients in some dissimilar metals (Seebeck effect).Design/methodology/approachA 3D thermoelectric and heat conduction model is used to estimate the deflection of the electron beam used during welding of dissimilar metals. A weak coupling between analysed fields is assembled. Additionally, the influence of the deflection on the calculated fields was not taken into account. The problem is solved using a finite element method.FindingsIt is possible to model Seebeck effect in a relative simple way using the finite element approach.Originality/valueThe paper presents a detailed description of modelling procedure of a complex coupled field problem.
Multilevel, one‐phase inverter with unequal voltage distribution
Authors: Hołub Marcin , Kalisiak Stanisław , Ruchała Krzysztof 
Published: January 2009

PurposeThe purpose of this paper is to introduce a unique multilevel, one‐phase inverter (in the multiplied full‐bridge configuration, cascaded‐type) with unequal voltage distribution among the voltage levels.Design/methodology/approachNumerical and experimental results are discussed and the topology thereafter evaluated.FindingsUnequal voltage distribution among voltage stages of the converter leads to increase of the output voltage resolution while simplifying the converter construction and minimizing the power switch losses. Simplorer numerical analyses as well as test stand measurements were led in order to verify properties of the system. Using the voltage distribution in the proportion of 6/2/1 leads to improved utilisation of power switches used in the means of voltage, current and switching frequency. FFT analysis was implemented in order to explore the frequency domain properties of the control apparatus.Practical implicationsThe results allow improvement of power switch utilisation and output voltage resolution of cascaded, three‐stage multilevel converter topologies and voltage output filter optimisation for multilevel power electronic converters.Originality/valueA new concept of voltage distribution is provided and described, a dedicated DSP‐based control system was developed as well as a small‐scale converter prototype, test stand measurement results are provided.
Modeling and parametrization of DC motor winding inductances
Authors: Benecke Jens , Dickmann Stefan 
Published: January 2009

PurposeThe purpose of this paper is to compare several methods to calculate solenoid inductances regarding their applicability to model the inductance of DC motor armature windings. Special attention is given to the influence of wiring insulation and current distribution and the axial length of the solenoid.Design/methodology/approachExpressions for the self‐ and mutual‐inductance of current filament and wire combinations are derived from basic inductance formulas. Combining these expressions allows expressing the inductance of arbitrary shaped solenoids (e.g. polygons).FindingsAccurately describing self‐ and mutual‐inductances is a very complex topic. However, in the case of motor armature windings, several simplifications can be applied to lower the calculation cost significantly. Plus, differences in inductances between regular polygonial solenoids and similar circular shapes were found to be rather small. Thus, many windings' inductances can well be approximated by using expressions for circular solenoids.Originality/valueA new way to calculate the inductance of arbitrary polygonial shapes is presented, and an example is given for hexagonal shapes.
Torque characteristics of a BLDC motor with multipolar excitation
Authors: Łukaniszyn Marian , Młot Adrian 
Published: January 2009

PurposeThis paper deals with magnetic field calculations and model‐based prediction of electromagnetic torque pulsations in a brushless DC (BLDC) motor.Design/methodology/approachThe impact of a Halbach‐like magnetization and a multipolar excitation of permanent magnets are analysed. The measurement results from the prototype motors are well‐compared with those obtained from the model calculations. It is shown that the cogging torque in the motor with the multipolar excitation of permanent magnets is reduced six times as compared with the conventional BLDC motor.FindingsThe proposed method provides high accuracy of the analysis of coupled electromagnetic phenomena. The comparison between measured and calculated values of electromagnetic torque, cogging torque and EMF shows a very good agreement.Practical implicationsReduction of the machine cogging torque is essential for practical applications of DC motors, in particular in the robotics industry.Originality/valueThis paper shows that multipolar excitation contributes to essential reduction of the cogging torque in a BLDC motor. This is confirmed by high‐quality numerical models of the motor, positively verified in experiments with motor prototypes.