bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural network approach to crack identification
Authors: Sikora R. , Chady T. , Sikora J.
Published: December 2018

The eddy current non-destructive testing of conductive materials is a well-known problem. There are a lot of different kinds of transducers. For one of them the mathematical model was built and the Inverse Problem formulated. In order to solve this problem the Artificial Neural Network approach, relatively new, was adopted. The public domain software, developed at Warsaw University of Technology, was used to teach the network. It was proved that a standard feedforward multilayered neural network is sufficient to identify the parameters of the defect with a satisfying accuracy.
Artificial urethral valve using SMA actuators (verification of opening/closing functions and thermo-metallurgical-mechanical model of SMA actuators)
Authors: Chonan Seiji , Jiang Zhong Wei , Tanaka Mami , Tanikawa Jun , Hirano Kentaro , Orikasa Seiichi , Namima Takashige , Uchi Keiichiro
Published: December 2018

This paper is concerned with the development of an artificial urethral valve for treating urinary incontinence, which is driven by shape memory alloy actuators. Two types of valves, one with hand-drum form and the other with cylindrical configuration, are assembled and their opening and closing functions are examined experimentally by using the urethrae of male dogs. It is found that the clyindrical valve is better than the hand-drum form from the point of contact pressure with the urethra. A thermo-metallurgical-mechanical model of the SMA plate is constructed and applied to the analysis of opening/closing functions of valve. It is shown that the presented model well describes the motor functions of the artificial urethral valve.
Computation of eddy current probe response due to a long crack based on a vector potential integral formulation
Authors: Yoshida Y. , Bowler J.R.
Published: December 2018

A volume integral formulation utilizing the vector potential dyadic Green’s function is applied to the computation of eddy current probe response due to a long crack. In addition to the ideal crack model, a thin crack model is proposed which takes into account the effect of crack opening on the measurement signal. To deal with the infinitely long crack, the spatial Fourier transform is applied to the boundary integral equation based on the vector potential integral formulation and then the method of moments is used to discretize the resultant equation. The proposed method is validated through the comparison of the computed results with measurements.
Numerical analysis of impulse electromagnetic fields in soft ferromagnetic materials
Authors: Pantelyat Michael G.
Published: December 2018

Peculiarities of the numerical simulation of impulse electromagnetic field distribution in soft ferromagnetic materials are considered. An efficient algorithm has been proposed in order to cause the iterative process to converge quickly. The proposed algorithm is based on the use of the combination of the reluctivities obtained on two previous iterations. The optimal value of the process parameter has been recommended.
Modeling magnetostrictive generation of elastic waves in steel pipes, II. Comparison to experiment
Authors: Sablik M.J. , Lu Yichi , Burkhardt G.L.
Published: December 2018

This paper describes continued investigation of magnetostrictive generation of elastic waves in steel pipes via alternating current through a coil about the pipe in the presence of a longitudinal static magnetic field. In paper I, electromagnetic theory was used to find solutions for changing electromagnetic fields induced in the pipe. The solutions were used to obtain magnetostrictive forcing terms in an elastic wave equation for solutions appropriate to continuity of normal stresses across cylindrical boundaries. It was found that longitudinal {\rm L}(0,1) and {\rm L}(0,2) elastic wave modes could be propagated for the frequency range considered. The amplitudes of these waves were dependent on the magnetostrictive forcing terms, which were in turn attributable to the alternating electromagnetic fields. In this paper, measurements are reported for the a.c. magnetic permeability of a steel pipe as a function of frequency and static magnetic field. These values are inserted into the model, and after other appropriate substitutions, predictions for wave amplitudes generated in the pipe are compared against experimental measurements.
Active control on the structural vibration under base excitations using a linear oscillatory actuator
Authors: Chung T.Y. , Moon S.J. , Jang S.M.
Published: December 2018

An active control system using a linear oscillatory actuator (LOA) is studied to suppress structural vibration. A voice-coil-type LOA having the moving mass of 23 kg weight is designed and fabricated for good linearity and high-frequency performance. The LOA consists of permanent magnets, a coil-wrapped nonmagnetic hollow rectangular structure, and an iron core for magnetic flux. When the coil is fed with current, changing its polarity, an oscillating force is produced to the moving mass in the magnetic field. Structural vibration is measured by the accelerometer attached to the structure and the level of vibration is reduced by the optimally controlled motion of the moving mass of the LOA giving anti-phase inertia force to the structure. Among the direct output feedback control methods, the suboptimal control method based on the linear quadratic control is adopted to modify the original control gain. Numerical simulations and experimental tests to verify its performance are carried out on the test structure of about 500 kg subjected to sinusoidal or random base excitation. From these tests, it is confirmed that the acceleration level of the structure is drastically reduced near the resonant region.
Feasibility study of an electrostatic actuator by finite element interaction analysis
Authors: Hamamoto Masaki , Hisada Toshiaki , Suzumori Koichi
Published: December 2018

A computer simulation program based on a finite element interaction analysis method is developed for the design of electrostatic actuators. The simulation program consists of finite element analysis parts for the hyperelastic structure and electrostatic field, and the interaction analysis part. Because the actuator utilizes structural buckling so as to obtain a larger horizontal stroke, the interaction analysis must take the postbuckling problem into consideration. Therefore, the arc-length method is incorporated into the program. It is demonstrated through a numerical example that satisfactory motion of the actuator can be realized by virtue of structural buckling.
TE_{11}-mode excitation of a circular aperture antenna covered by a layered dielectric hemi-spherical radome
Authors: Leong M.S. , Li L.W. , Kooi P.S. , Yeo T.S. , Ma X.
Published: December 2018

This paper presents a full-wave analysis of the antenna radiation due to an aperture in a ground plane generating a circular waveguide TE _{11} wave, which is covered by a dielectric hemi-spherical radome of multi-layered geometry. Huygen’s equivalence principle and the image theory are utilized to simplify the problem. The dyadic Green’s function technique is applied to analyze the electromagnetic fields due to the circular aperture antenna with TE _{11} field distribution. Following the conventional procedure, the magnetic dyadic Green’s functions for radially three-layered and four-layered geometry are formulated to account for the full-wave contribution due to such an equivalent magnetic surface current. The coefficients of these dyadics are derived by duality substitution and reduction from the authors’ earlier published work. The Fraunhofer electric fields are obtained using the far-zone approximation. In order to show the applicability of the analysis in this work and demonstrate the effects of the dielectric radome on the radiation patterns, computations of the power patterns, beamwidths, and total transmission losses are made and the results obtained here are compared with the existing results in the literature.
An alternative expression of piezoelectric representation and its application in inclusion problem
Authors: Shen Shengping , Kuang Zhen-Bang
Published: December 2018

This paper intends to conform the mathematical correspondence between electric and mechanical variables to the physical correspondence in electroelastic problem when a piezoelectric material is subjected to stress field \sigma_{ij} and electric field E_i or displacement {\bf u} and electric displacement D_i . E_i is expressed with an antisymmetric electric field tensor V_{ij} , and D_i is expressed with an antisymmetric electric displacement tensor P_{ij} which can be expressed with ‘induction potential’ \psi_i . Then stress equilibrium and electric field equations can be described by a second order canonical differential equation system of u_i and \psi_i . As an example, the coupled electroelastic fields in an inclusion or inhomogeneity embedded in an infinite matrix are obtained in a manner directly analogous to Eshelby’s classical elastic solution. The electroelastic fields inside the ellipsoidal inclusion or inhomogeneity and just outside the ellipsoidal inclusion or inhomogeneity are also given. In addition, we analyze the energies of the inclusion. The results in this paper are the backbone in the development of the electric damage theory and ferroelectric constitutive theory.
Induction heating of large steel disks: Coupled electromagnetic, thermal and mechanical simulation
Authors: Zgraja Jerzy , Pantelyat Michael G.
Published: December 2018

The coupled electromagnetic, thermal and mechanical simulation is described for new technological processes of induction heating of large steel disks. Non-uniform temperature distribution of induction heated disks may cause plastic deformations and buckling. The goal of this investigation is to determine the mechanical behaviour of induction heated disks by means of coupled finite element computation in different formulations. The paper contains the detailed description of an applied numerical technique and of obtained results including elastic-plastic stress distribution, plastically deformed state and the most likely modes of the disk buckling.
Equations for a piezoelectric parallelepiped and applications in a gyroscope
Authors: Yang J.S. , Fang H.Y. , Jiang Q.
Published: December 2018

Zero-dimensional equations for motions of a rectangular piezoelectric parallelepiped are derived from the three-dimensional equations of linear piezoelectricity by triple power series expansion in the length, width and thickness directions. The resulting equations are ordinary differential equations with time as the only independent variable. The lowest order equations can describe motions with homogeneous shearing and stretching deformations as well as uniform electric fields. It is a generalization of the zero-dimensional theory of elastic bodies in the sense that electric coupling is included. The equations obtained are employed in the analysis of a ceramic plate thickness–shear piezoelectric gyroscope. Results useful to the understanding and design of the gyroscope are obtained.
The existence of surface shear waves in a finitely conducting magneto-elastic half-space
Authors: Chattopadhyay Manidipa , Chakraborty S.K. , Chakraborty Sarbani
Published: December 2018

The existence of Love-type SH waves in an electrically finitely conducting elastic half-space under the action of a uniform magnetic field has been studied. Damped magneto-elastic SH waves are found to exist under a high magnetic field acting in the direction of propagation of the wave.
Homogenization techniques and application to piezoelectric composite materials
Authors: Agbossou Amen , Nguyen Viet Hung , Pastor Joseph
Published: December 2018

Investigating piezoelectric composites is a recent research domain. Direct measurements on piezoelectric composites are not always easy, making the use of homogenization to determine all its electroelastic characteristics of major interest. This work presents the homogenization for the periodic piezoelectric media by means of the finite element method. The particular details are given for generalized plane strain (GPS) case. As application of the proposed model, numerical developments were presented for three different piezoelectric media: unidirectional piezoelectric fiber composites, 1.3 piezoelectric transducer and muscle materials considered as “semi-piezoelectric” material. The predicted values are in good agreement with the other numerical results in literature and the available experimental data.
Mode transition of electromagnetic wave in slab waveguide subjected to in-plane elastic wave
Authors: Yeh Chau-Shioung , Lin Chun-Bo
Published: December 2018

In this paper, on the basis of electromagnetic fields in statistical formulation and the material description for solid medium, the governing equations are decomposed into different states with the necessary approximations. The relevant equations with boundary equations are applied to investigate the phase change of electromagnetic wave and the mode transition of guided electromagnetic wave in a slab waveguide, which is caused by the mechanical disturbance such as strain or elastic wave. The conditions of the mode transition for TE mode are determined and the physical meaning of the results is interpreted.
Angular correlation positron annihilation spectroscopy applied in investigation of neutron irradiated RPV-steels
Authors: Slugeň Vladimír , Haščík Ján , Gröne Rudolf
Published: December 2018

Angular correlation positron annihilation spectroscopy (AC PAS) has been used for the investigation of reactor pressure vessel (RPV) specimens prepared for the ``Extended surveillance specimen program'' in the 3rd and 4th units of NPP Jaslovsk\'e Bohunice (Slovakia). PAS spectra showed that the changes associated with the effects of neutron irradiation can be well detected. The samples from RPV base material (15Kh2MFA) and weld (Sv 10KhMFT) were measured by angular correlation positron annihilation spectrometer before and after irradiation. Samples have been irradiated in VVER-440 reactor (units 3 and 4 in Bohunice) by neutron fluence from 7.8\times 10^{23} m ^{-2} up to 2.5\times 10^{24} m ^{-2} . Results of PAS measurements are presented and discussed in detail.
An analysis of passive magnetic composites for suppressing the vibration of beams
Authors: Oh J. , Ruzzene M. , Baz A.
Published: December 2018

The fundamentals of controlling the structural vibration of beams treated with a new class of Passive Magnetic Composites (PMC) are studied. The PMC is a constrained damping treatment, where a viscoelastic core is sandwiched between two layers of permanent magnets. The interaction forces between the magnets aim at enhancing the damping characteristics of the viscoelastic. The effectiveness of such treatments is demonstrated both numerically and experimentally. In particular, a finite element code is developed to model the interaction between the dynamic behavior of the beam, the viscoelastic layer and magnetic layers.

The model is validated experimentally at various operating conditions and the performance of the treatment is evaluated for different configurations of the magnetic layers. The obtained results suggest the potential of the new class of PMC as an effective and simple mean for controlling structural vibrations.
A FFT integral formulation using edge-elements for Eddy Current Testing
Authors: Tamburrino A. , Ventre S. , Rubinacci G.
Published: December 2018

This paper presents a new approach for reducing the computational cost needed to solve the forward problem, i.e. the prediction of the measurements of a given ECT measurement system. This issue is mandatory in any inversion algorithm which, typically, requires the solution of a large number of direct problems.

Integral formulations are attractive for ECT since they require the discretization of the conductive body only. However they also give rise to a full stiffness matrix whose inversion, typically obtained using direct solvers, has a computational cost that grows as O(n^3) where n is the number of unknowns arising from the discretization. Iterative algorithms achieve a computational cost that is lower than direct solvers when the stiffness matrix is sparse.

The approach proposed in this paper makes it possible to represent the stiffness matrix arising from an edge-elements based integral formulation, by means of the Fast Fourier Transform. This representation is achieved for bounded conductive domains meshed by a regular mesh and incurs a computational cost that grows as O(N \log h) .
Guest-editorial
Authors: Uesaka Mitsuru , Slama Jozsef
Published: December 2018

The five selected papers are presented from the 3rd Japan – Central Europe Joint Workshop held in Bratislava, Slovakia, on 27–30 September 1998.
Magnetoelastic waves in a bicrystalline gap structure under a bias magnetic field
Authors: Nowacki J.P. , Alshits V.I. , Lyubimov V.N.
Published: December 2018

SH acoustic fields in transversely isotropic media with magnetoelastic coupling due to a linearized magnetostriction are considered for a bicristalline structure with a gap. The surface and pseudosurface eigenmodes and the conditions of their existence are described. A study is carried out of the resonant excitation of the surface wave in one crystallite by means of a pumping bulk wave in the other crystallite. The potentialities of a control of wave parameters by means of the bias magnetic field are considered.
Phenomenological theory of structural and magnetic phase transitions in shape memory Ni-Mn-Ga alloys
Authors: Buchelnikov V. , Zayak A. , Vasil'ev A. , Takagi T.
Published: December 2018

In the framework of Landau theory the phase diagram of structural and magnetic phase transitions of cubic ferromagnetic Ni-Mn-Ga alloys is constructed by taking into account the strain, the crystal lattice modulation and the magnetic order parameters.
Ni excess and electronic structures of multi-functional Ni_{2.17}Mn_{0.83}Ga
Authors: Ishida Shoji , Furugen Munemasa , Asano Setsuro
Published: December 2018

The electronic structures of Ni _{2.17} Mn _{0.83} Ga predict that the tetragonal, the orthorhombic and the monoclinic structure can be a martensitic phase and the monoclinic structure is the most stable. The stabilization of the monoclinic structure mainly comes from the difference of the kinetic energy. Then, the Ni excess plays an important role in the stabilization of the crystal structure. The Ni excess atoms make the tetragonal and orthorhombic structures unstable and the monoclinic structure stable. It is also found that the Ni excess atoms prefer the Mn sites and the magnetic moments in the monoclinic structure are smaller than those in the other structures.
High-speed response of SMA actuators
Authors: Qiu Jinhao , Tani Junji , Osanai Daisuke , Urushiyama Yuta , Lewinnek David
Published: December 2018

The main problem with Shape Memory Alloy (SMA) actuators is their slow response speed. Current SMA actuators work in tens of seconds though they can generate large force and displacement outputs. The objective of the research in this paper is to improve the response speed of SMA actuators to 10 milliseconds or less. SMA actuators are driven by thermal energy and their slow response is attributed to the inefficient heat transfer. To improve the response, direct Ohmic heating was used in the experiments. The SMA actuators used in this study are Ti-Ni-Cu columns of \phi 5\times 50 mm with residual strain produced upon unloading after 5.3% displacement response of the SMA actuators without axial constraint and the transient force response of the actuators under axial constraint were measured with direct heating. The shortest response time achieved for unconstrained actuators is 4.6 ms and that for constrained actuators is 6.5 ms. The average value of maximum recovery force is 10.8 kN, which corresponds to 550 MPa of recovery stress. It was also found that constrained actuators need about 50% more energy for heating than unconstrained actuators.
Fracture induced electromagnetic emissions in the mining industry
Authors: O'Keefe Steven G. , Thiel David V. , Davey Neil P.
Published: December 2018

Electromagnetic EM emissions have been received during and after blasting in quarries and mines. These signals show promise for mine safety monitoring and blast analysis. Results indicate smaller fractures may be detected using EM systems compared to seismic systems. Instantaneous blast analysis may also be possible in the future. EM emissions have also been shown to be produced in concrete.
An extension of modular decoupling methodology for EMC to enclosure with aperture and some contents
Authors: Edrisi M. , Chan W.K. , Nafalski A.
Published: December 2018

This paper addresses the modular decoupling methodology (MDM) [1]. It predicts EMC by the simulation of the effects of radiated emissions on an enclosure with a prescribed aperture and some contents. The proposed method could be a tool for preventing some possible EMI problems at the design stage. Computer simulations are developed using the finite element method and the investigation assesses the effectiveness of the shielding and susceptibility predictions. Exploration on an external emission source and its impact to lower stage is also considered.
A benchmark problem in inverse magnetostatics solved by different multi-objective optimisation methods
Authors: Borghi C.A. , Di Barba P. , Fabbri M. , Rudnicki M. , Savini A.
Published: December 2018

The global optimisation of Loney's solenoid, aiming at minimizing the level of inhomogeneity of the main field, was proposed and solved as a first benchmark for single criterion optimisation. Accordingly, the TEST(Testing Electromagnetic Synthesis Techniques) environment has been set up. Based on Loney's solenoid even in the unshielded configuration, a multicriteria optimisation problem has been then formulated: to identify the coil geometry producing a main field with the minimum inhomogeneity within the solenoid and, at the same time, a minimum level of stray field around the solenoid. The scope of this contibution is to compare different methodologies for the solution of the multicriteria design problem.
The Green's functions for an infinite piezoelectric strip with line sources at the surfaces
Authors: Nowacki J.P. , Alshits V.I. , Radowicz A.
Published: December 2018

A series of the Green's functions describing 2D electro-elastic fields excited in an arbitrary infinite piezoelectric strip by the different combinations of line sources at the surfaces are derived. Four types of sources are considered: a line of forces applied to a free surface, a step of displacements on a clamped surface, a line of electric charge or a line of electric potential discontinuity on a surface. In the absence of electrical sources at the surface the latter is supposed to be adjoined to an isotropic dielectric medium with an arbitrary permittivity. The Green's functions are expressed in terms of eigenvectors and eigenvalues of the generalized Stroh problem in the form of convergent Fourier integrals. These integrals are taken for the particular cases when, due to the symmetry of the material of the strip, the eigenvalues of the 8 × 8 Stroh matrix are purely imaginary. The results of integration are presented as sums of residues at the poles determined by some equations. Finding the roots of these equations needs additional computing.
Quantitative profile evaluation of natural cracks in a steam generator tube from eddy current signals
Authors: Yusa Noritaka , Chen Zhenmao , Miya Kenzo
Published: December 2018

This paper reports the progress of studies in eddy current inversion in the authors' group and a novel inversion scheme that can deal with conductive cracks using eddy current signals. The novel scheme is based on artificial neural networks with its accuracy enhanced by using a shifting aperture method and signal processing techniques. A four sensor type probe is used in the eddy current testing. Several reconstruction results are introduced in this paper as validation of the proposed new scheme. The scheme is also applied to profile reconstruction of cracks which occurred in an actual steam generator tube of a pressurized water nuclear power plant. Remarkable agreement between reconstructed profiles and those obtained by destructive testing is observed. It can be concluded that the new inverse scheme is promising and will be a powerful tool for the practical applications.
Instability analysis of the surface of molten metal under high frequency electromagnetic fields
Authors: Yoshida Mitsuhiro , Morita Katsuaki , Kuwada Chie , Tanahashi Takahiko
Published: December 2018

A high frequency electromagnetic field (HFEMF) that is applied to the surface of a molten metal is able to generate a Lorentz force on the surface of the molten metal. This force can be used to seal the molten metal leakage without contact, which makes the quality of metal products purer and the seal system used perform longer. To make this technique possible, it is required to analyze the surface shape and the surface instability when HFEMF is applied to the molten metal surface. It is known from experiment with various kinds of molten metal that the fluctuation of the surface occurs under the applied HFEMF. This fluctuation becomes stronger as the HFEMF is increased. The fluctuation is strongly connected to the instability criteria of the surface.

This research has been carried out to make it clear how the HFEMF causes the surface fluctuation of the molten metal, and how it determines the surface shape and stability region. Also, the effects of gradient of HFEMF and DC magnetic field have been investigated.
Calculation of EEG anisotropic forward problems by the FVM-BEM coupled approach
Authors: Xie Yaoqin , Ma Xinshan
Published: December 2018

The forward problem of a realistic head model is simulated by the finite volume method (FVM)-boundary element method (BEM) coupled approach. A new mesh discretization method for the FVM is presented to simulate the realistic head model. The simulations show that this approach is convenient to calculate the forward problem of EEG with anisotropic conductivity.
Classical and IT based magnetization dynamics modeling
Authors: Endo Hisashi , Saito Yoshifuru , Hayano Seiji , Miya Kenzo
Published: December 2018

This paper reviews the classical magneitization models for computation use, and also proposes information/intelligence technology (IT, in short) based model for the magnetodynamics in ferromagnetic materials. At first, Fourier model of the hysteretic magnetization is derived. Second, assuming the bar-like domain walls derives a domain-based model. This model is verified by a simple example. Third, a composite model by combining the Preisach with domain-based models is derived, and then, Rayleigh's law is derived. Finally, IT based model for magnetodynamics in ferromagnetic materials is introduced.
Vector magnetic hysteretic modeling and practical magnetic field analysis
Authors: Enokizono Masato
Published: December 2018

This paper describes the up-to-date problem and some suggestions for the numerical magnetic field analysis. Especially, what is the practical method is emphasized. Furthermore, I want to propose the development to solving the materials from solving the equation. It is the most important to analyze the magnetic field by using the measurable data. Then we must construct the fundamental equation due to the magnetic materials making the some engineering models.
Theoretical investigation of change of magnetic property due to creep damage using Jiles-Atherton magnetization model
Authors: Chen Gangzhu , Shiwa Mitsuharu , Yoneyama Hiroshi
Published: December 2018

Magnetic testing of creep damage shows that there is a correlation between the testing signals and the creep. It is observed that the hysteresis loss and the third harmonic of the testing signals change obviously with the progress of the creep. To explain the experimental phenomena theoretically, Jiles-Atherton magnetization model is tried to predicate the change of the magnetic property. The magnetization curves in presence of the creep are simulated by introducing the microstructure changes due to the creep into the Jiles-Atherton model. By comparison of the theoretical and experimental results, it is shown that the trend of the change of the magnetic property predicated by the simulation agrees with that observed by the magnetic testing.
A tabu based algorithm for multiobjective optimizations of electromagnetic devices
Authors: Yang Shiyou , Xiong Suming , Ni Peihong , Ni Guangzheng , Ho S.L.
Published: December 2018

This paper proposes a tabu based algorithm to find the Pareto solutions of multiobjective optimizations of electromagnetic devices. An intensification phase by using the evolution algorithm is introduced to ensure the power and efficiency of the proposed method to find the Pareto optimal; and the ranking selecting approach, together with the new neighborhood generation scheme, is proposed to guarantee the diversity of the algorithm, i.e., to have the ability of uniformly sampling the Pareto front. Two numerical examples are reported to demonstrate the abilities of the proposed algorithm for both obtaining and uniformly sampling the Pareto optimal front of the multiobjective design problems.
Speech recognition using the extraction of particular feature by the discrete wavelet transform
Authors: Midorikawa Yoichi , Akita Masanori
Published: December 2018

We have proposed the method for recognition of the signals polluted with noise using modification of spectral envelopes shape. However, these spectral envelopes have wrong valleys. For that reason recognition rate is not improved. There is plenty of scope for improvement. In this paper, we propose that method for extracting particular feature by the discrete wavelet transform. (Wavelet transform is widely used for the extraction of particular feature from data.) Pattern recognition rate is improved by the new method. It was shown that the wavelet analysis was one of the promising methodologies for the pattern recognition noisy signal.
Design of switchable transformer control system employing the micro-controller 80C552
Authors: Dharmawan H.A. , Ali S.A.M.
Published: December 2018

Research on a switchable transformer has proven that series and parallel configurations used in the primary and secondary windings can decrease the amounts of total losses which are made up of core losses and winding losses. Both configurations are integrated through some Solid State Relays(SSRs). When utilising this transformer however, some complications arise. The main concern is timings of switching from one configuration to another, and timings of triggers which should be applied to the SSRs. This paper proposes the use of the micro-controller 80C552 as the main control system to overcome the problems. The timings are controlled through the combination use of timer T0, T2, capture and compare interrupts.
Application of topology optimization to electromagnetic system
Authors: Byun Jin-Kyu , Hahn Song-Yop
Published: December 2018

In this paper, the theories and general concept of the topology optimization in the electromagnetic system are explained, and the applications to the optimal design of electromagnetic devices and the inverse problems are shown. As a way of defining the relationship between the design variables and material properties, homogenization method or density method can be used. The mutual energy method is also explained for the design sensitivity analysis in the topology optimization.
Efficiency analysis of induction motor considering rotor and stator surface loss caused by rotor movement
Authors: Yamazaki Katsumi
Published: December 2018

This paper presents a method to calculate efficiency of induction motors considering stray losses caused by stator and rotor slot ripple. The harmonic electromagnetic fields are calculated by the combined 3D-2D nonlinear time-stepping finite element analysis considering movement of the rotor to estimate the harmonic copper and iron losses. The calculated losses and efficiency is compared with the experimental results. It is clarified that the losses concentrate at the surface of the stator and the rotor core and that the consideration of the time-harmonics caused by the rotor movement is indispensable to estimate the losses and the efficiency of the motor.
Modeling the complex permeability spectra of Ni-Zn ferrite
Authors: Caltun Ovidiu Florin , Spinu Leonard , Stancu Alexandru , Sava Anca
Published: December 2018

Ferrites properties depend very strongly on the chemical composition and on the microstructure. The complex permeability spectra of Cu substituted Ni-Zn ferrites produced by conventional ceramic process for high frequency were studied. The experimental and theoretical curves of real and complex permeability were compared. Is discussed the contribution of the domain wall and of the spin rotational motion on the complex permeability in the MHz region. A small amount of Cu ions can provide high performances to the Ni-Zn ferrite.
Lines of zero magnetization and domain wall inclinations in yttrium orthoferrite
Authors: Didosyan Yuri S. , Hauser Hans , Reider Georg A.
Published: December 2018

Otherthoferrites are canted ferromagnets which exhibit extremely high domain wall (DW) velocities. The change of handedness in the DWs does not occur in Bloch lines but in lines of zero magnetization. Observations of the lines and of the DW inclinations in plates of yttrium orthoferrite are reported. The inclinations occur towards the direction of the crystallographic a axis and reach tens of degrees.
Magnetic levitation of a metal orb
Authors: Matlák Zsuzsanna , Barbarics Tamás
Published: December 2018

This paper presents the analysis of the force determination that exerts an influence in the levitation-melting method model. The goal of the present study is a numerical investigation of the problem results concerning the alternation of the magnetic field modified by the sphere, which melts during the levitation-melting method. The numerical investigation is realised by global variational method, completed with the R-functions.
Extraction of B-H relation based on the inverse magnetostatic problem
Authors: Ioan Daniel , Rebican Mihai
Published: December 2018

The paper describes a magnetic field inverse problem and an efficient numerical method to solve it. Starting from the experimental flux-current Φ-I data obtained using a non-uniform magnetic field device with known geometry, the B-H nonlinear characteristic of the homogeneous magnetic core is extracted. Both functions B-H andΦ-I are piecewise linear approximated with the same number of breakpoints. The correct formulation (solution uniqueness) of this particular inverse problem is discussed. The method was successfully applied to characterize the ribbon core material of a FLUXSET magnetic field sensor used in Eddy Current Testing. In this case, the hysteresis loop and the equivalent lumped magnetic nonlinear circuit were extracted. Comparison with experimental results validates the proposed method.
Modeling of liquid walls in APEX study
Authors: Smolentsev S. , Abdou M. , Kunugi T. , Morley N. , Satake S. , Ying A.
Published: December 2018

Liquid wall concept has a significant place in the Advanced Power Extraction (APEX) study as a part of the US program on Nuclear Fusion. In the present paper, different approaches currently developed for modeling liquid wall magnetohydrodynamics and heat transfer in APEX have been presented. Turbulent flows of low-conductivity liquids, such as molten salts (Flibe), are analyzed using a two-equation turbulence model and Direct Numerical Simulation. The analysis of liquid metal flows under a strong reactor magnetic field is based on the magnetohydrodynamic equations for laminar flows.
Necessity of electromagnetic field computation for the magnetic current limiter
Authors: Mukhopadhyay S.C. , Iwahara M. , Yamada S.
Published: December 2018

For the last few years the authors have been involved in the design and development of different topologies of magnetic current limiter (MCL). The small scale laboratory models have been fabricated and experiments were conducted. The simulated performance obtained from the tableau approach based on lumped parameter model shows discrepancy with the experiment. This paper describes the necessity of electromagnetic field computation which clearly shows the discrepancy between the observed and the simulation results, which can be attributed to a non uniform flux distribution in the core.
Finite element analysis of deflection yoke using a novel technique for analyzing current density distribution
Authors: Im Chang-Hwan , Jung Hyun-Kyo
Published: December 2018

A recently developed method for the accurate calculation of current density distribution is firstly applied to a practical case with the 3-D finite element analysis. The deflection yoke (DY) for the CRT system is adopted for the simulation. The simulated results are verified by comparing with an experimental data.
Application of a rational quartic triangular Bézier patch to field calculation by a boundary subdivision method
Authors: Hamada Shoji , Takuma Tadasu
Published: December 2018

A rational quartic triangular Bézier patch enables us to numerically represent an octant of a sphere with neither shape errors nor degeneration of nodes, when it adopts the control points and weights derived by Farin. This patch allows us to avoid undesirable influences caused by the misrepresentation of a spherical shape, if the objects to be treated involve an octant of a sphere in the field analysis by a boundary subdivision method. We have carried out a static field calculation for a spherical dielectric placed in a homogeneous applied field with a surface charge method by introducing a simple method that constructs arbitrary mesh patterns on this patch.
Modeling of single pole write head and double-layered medium for 3-D eddy current analysis
Authors: Kanai Yasushi , Matsubara Ryo , Muraoka Hiroaki , Nakamura Yoshihisa
Published: December 2018

Finite-element modeling of single pole (SPT) write head with double-layered medium for perpendicular magnetic recording is investigated. In carrying out 3-D eddy current transient finite-element analysis, reducing the medium area is one key factor for computation time reduction while maintaining sufficient solution accuracy. It is also investigated the number of layer divisions for thin metallic under-layer. The results validate the modeling of SPT head with double-layered medium.
3-D MHD calculation in consideration of free surface, heat transfer and solidification
Authors: Fujisaki Keisuke
Published: December 2018

3-D magnetohydrodynamic calculation model taking into consideration of heat transfer and solidification as well as free surface is developed in order to evaluate the characteristics of molten metal using electromagnetic stirring (EMS). A shadow method that calculates electromagnetic force in consideration of free surface transition is proposed to reduce computing time and keep sufficient accuracy. A calculated free surface of Mercury under 200 Hz magnetic field shows an adequate agreement with experimental one. Calculation results applied to continuous casting process taking into consideration of heat transfer and solidification are in good agreement with operation data. This model introduces that EMS makes the solidified shell uniform and dynamic deviation of temperature stable.
Magnetic loss measurement and calculation of a DC/DC converter
Authors: Hauser Hans , Himmelstoss Felix A. , Wurm Peter H.
Published: December 2018

The use of a tapped inductor in the classical sepic converter leads to a high step-down ratio thus avoiding the extreme duty cycles of the active switch and the high peak currents in the active and passive switches. The function and some stress data of such a converter are summarized and the flux density and the current through the inductor during start-up are measured and simulated by the energetic model of ferromagnetic hysteresis and the magnetic losses of the inductors are calculated.
Magnetic shielding on low-frequency
Authors: Barbarics Tamás , Kis Péter
Published: December 2018

This paper deals with the examination of low frequency magnetic shielding. In the designe of magnetic shielding, plate can play a significant role in emphasizing the importance of shielding. The magnetic field was examined including the shielding sheets with various magnetic properties. The field of the linear magnetic sheet was calculated first, and the non-linear properties of shielding plate were taken into account with a non-linear H -- M characteristic in the second case.
Minimizing winding losses under trapezoidal current waveforms
Authors: Vasiliu M. , Moraru A. , Hantila F.
Published: December 2018

Time-periodic non-sinusoidal solutions of the magnetic diffusion equation are expressible either in the form of time-harmonic series or as space eigenfunction series. Based on the latter, eddy-current losses in a multilayer winding carrying a trapezoidal current are evaluated. Optimum layer thickness is obtained by minimizing the resistance factor of the multilayer winding. Formulae for square and symmetrical triangular waveforms are also included.
Development of a RIMS-based FFDL system at the experimental fast reactor JOYO
Authors: Harano Hideki , Ito Chikara , Watanabe Kenichi , Iguchi Tetsuo
Published: December 2018

A series of experiments has been examined the applicability of RIMS to the trace xenon isotopic analysis needed for the tagging gas FFDL. The measurement of the JOYO cover gas equivalent clarified the existence of non-resonantly produced argon ions which could disturb the trace analysis. We proposed to apply the mass gating and solved the problem, which enabled us to succeed in demonstrating that RIMS satisfies the requirement for the FFDL at the MONJU.
Simulation in applying genetic algorithm for non-destructive measurement of electron beam transverse profile
Authors: Tomioka Satoshi , Nisiyama Shusuke , Enoto Takeaki
Published: December 2018

For the purpose of non-destructive measurement of the cross-sectional shape of an electron beam, we have studied a detection system that is composed of both a number of antennas and a current monitor. The antenna detects an electric field, and the current monitor detects an integral of beam currents.

The signals acquired from these detectors are applied as the input of an inverse problem. We adopt the genetic algorithm to simulate the profile measurement as an inverse problem analysis.

The results showed that this detection system is partially effective, even though this system is an "ill-posed problem" (i.e. the number of input data parameters is less than the number of parameters to be estimated). We also found that the current monitor, which cannot acquire position-dependent information, is nevertheless useful to accelerate the convergence of sub-optimal beam profiles.
Scattered field FD-TD analysis for wake-fields computation
Authors: Nisiyama Shusuke , Tomioka Satoshi , Enoto Takeaki
Published: December 2018

In this paper, a scattered field Finite-Difference Time-Domain(FD-TD) method is applied to wake-fields computation. In the ordinary FD-TD method or other methods based on the finite difference scheme, the trajectory of a traveling charged particle beam should be along the spatial grid. In the presented method, an arbitrary beam trajectory can be treated since the beam current is not placed on the spatial grid but is considered as an incident field source. Wake potentials of a simple system with a slightly angled beam trajectory are calculated for a demonstration.
Edge radiation -- a new source of infrared synchrotron radiation with very special characteristics
Authors: Marquardt Niels
Published: December 2018

Electron storage rings have become very powerful sources of electromagnetic radiation covering a wide spectral range. In particular, the high-flux, long-wavelength infrared (IR) radiation from synchrotron light sources is increasingly used for spectroscopy in basic and applied research. Besides ordinary IR synchrotron radiation emitted from homogeneous magnetic dipole fields (i.e. dipole radiation DR), another high-brilliant source of IR radiation has been discovered recently, which is emitted by relativistic electrons traversing the inhomogeneous edge fields of bending magnets (i.e. edge radiation ER). In this paper a comparison is made between the very different radiation characteristics of DR and ER. Plans for the construction of a high-brilliant IR beamline at the storage ring DELTA, dedicated to an investigation of ER and to its use as a sensitive tool for electron-beam diagnostics, are presented. Moreover, various experiments for ellipsometry, FT-IR micro-spectroscopy and photothermal IR radiometry, exploiting the well-focussed, broadband IR-photon flux of high intensities are discussed.
Generation of submili-joule picosecond square shaped pulses for low emittance electron generation in photocathode RF-GUN
Authors: Takasago Kazuya , Yada Akira , Miura Taisuke , Washio Masakazu , Kannari Fumihiko , Torizuka Kenji , Endo Akira
Published: December 2018

Arbitrary shaping of a sub-milli joule femtosecond pulses has been demonstrated by manipulation of optical frequency phase components on the Fourier plane. The shaped pulses were pulse trains and picosecond square pulses for low emittance electron generation in a RF photocathode. Since the pulse shaping apparatus was placed between an oscillator and a pulse stretcher in order to avoid damage to the liquid crystal spatial light modulator, phase-only modulation was used for shaping to avoid damage to optical elements in a regenerative amplifier. The phase modulation was designed by simulated annealing optimization method.
Studies on back-streaming electrons onto a thermionic cathode in an RF gun
Authors: Masuda Kai , Kii Toshiteru , Yamaguchi Tomohiko , Toku Hisayuki , Yoshikawa Kiyoshi , Yamazaki Tetsuo
Published: December 2018

Aiming at production of high brightness electron beams with longer pulses than several μsec for applications to free electron lasers by use of an RF gun with a thermionic cathode, the adverse effect of back-streaming electrons onto the cathode surface were studied both experimentally and numerically. Temperature rises of the thermionic cathode surface due to the back-streaming electrons were observed directly by use of an infrared thermometer. From the measured temperature rises, powers of the back-streaming electron beams were, then, evaluated by use of a 0-dimensional model taking into account heat transfer through thermal radiation and thermal contact to the gun body, and comparisons were made with numerical results by use of a 2-dimensional particle-in-cell simulation code we have developed. Both by the experimental evaluation and by the particle-in-cell simulation, the beam power onto the cathode surface was found to increase with the increasing RF input to the RF gun cavities, and reach a considerable power compared to the cathode heater power supply.
Laser-plasma electron linear accelerator
Authors: Hafz Nasr A.M. , Hemker R. , Zhidkov A. , Okuda H. , Ghaly W. , Kinoshita K. , Hosokai T. , Yoshii K. , Ueda T. , Watanabe T. , Uesaka M.
Published: December 2018

The generation of an ultrashort relativistic electron bunch from a strong laser-plasma interaction have been studied by particle-in-cell simulations and observed experimentally. The electron beam was generated from the plasma created by focusing 12 TW (tera watt) laser pulse at the edge of helium gas jet expanded into the vacuum from a pulsed supersonic nozzle. The laser pulse duration was 50∼fs (femtosecond). In the interaction of 50 fs, 12 TW laser pulse with plasma of density of 5 × 10^{19} cm ^{-3} , the electron generation was observed in the simulation at the very beginning of the interaction region. The plasma electrons were gaining higher energies by the huge longitudinal electric fields (created by the laser pulse) as they move through the rest of the plasma following the laser pulse. In the experiment, the electron beam transverse profile and its total charge have been measured in the forward direction (the same direction of the laser pulse) by using imaging plate and Faraday-cup, respectively.