bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization and evaluation of corrosion in a small-bore piping system using a bobbin-type magnetic camera
Authors: Le Minhhuy , Kim Jungmin , Vu Hoanghai , Do Hwa Sik , Lee Jinyi
Published: December 2018

This paper presents a nondestructive evaluation algorithm for locating, discriminating, and evaluating inner and outer diameter (ID and OD) corrosion on a small-bore pipe by means of a bobbin-type magnetic camera that uses arrayed solid-state Hall effect sensor elements for measuring alternating magnetic fields. The proposed magnetic camera system is used to experimentally measure artificial ID and OD hole-type cracks on a small-bore copper alloy pipe over a low-frequency range (2–8 kHz). The measured amplitude signal is analyzed to determine both the position and type of crack. The volumes of the cracks are estimated with standard deviation of 0.77 mm ^{3} to be in the range 1.00–9.01 mm ^{3} .
Fabrication and AC characterization of magneto-impedance microsensors for alternating magnetic field measurement
Authors: Peng Tao , Moulin Johan , Alves Francisco , Bihan Yann Le
Published: December 2018

Multilayered magneto-impedance microsensors (Finemet/Copper/Finemet) were elaborated by microfabrication process using bi-layers lift-off method. A post-annealing step was carried out at 300°C for 1h under magnetic field, which led to induce a longitudinal or transversal anisotropy in the magnetic films. A method based on a double amplitude demodulation was proposed for the sensitivity characterization corresponding to the AC magnetic field measurement capability. According to these alternating magnetic field characterizations, the sensitivity, the linearity and the bandwidth of the microsensor were obtained. The highest sensitivity is around 4200 Ω/T and the measurable sensor bandwidth reaches up to 300 kHz. The sensor presented no hysteresis since a DC bias field larger than anisotropy field is applied.
Development of a high-speed motor at extremely low temperatures with an axial self-bearing motor and a superconducting magnetic bearing
Authors: Matsuoka Akihiro , Sumino Masayuki , Ueno Satoshi , Takeda Tsunehiro
Published: December 2018

Superconducting technology has been significantly improved since the superconductor Y-Ba-Cu-O was discovered. This technology has been applied to many medical image-processing applications such as magnetoencephalogram (MEG) and magnetic resonance imaging (MRI). Because the superconducting phenomenon occurs at extremely low temperatures, liquid helium or liquid hydrogen is essential to obtain a low-temperature environment. In addition, it is well known that the decompression of the liquid helium creates superfluid helium. This phenomenon improves the performance of the superconducting devices. For that reason, a vacuum pump, which can be used at a cryostat, is required.

In this paper, we propose a motor that has a small size and simple structure for use in the cryostat. The proposed motor consists of an axial self-bearing motor, superconducting magnetic bearings, and permanent-magnet repulsive-type passive magnetic bearings. The design of the motor and control method is introduced. The experimental results show that the proposed motor has a high possibility for high-speed rotation at extremely low temperatures.
Microprocessing characteristics of inner surface of tube using magnetic functional fluid
Authors: Nishida Hitoshi , Shimada Kunio , Ido Yasushi
Published: December 2018

We proposed a microprocessing method using a magnetic compound fluid for the inner surface of a tube made of a material that is difficult to cut, and clarified the processing characteristics and magnetic field distribution of the tool. The tool inserted into the tube comprises a stack of ring-shaped permanent magnets with spacers between them. There is an almost proportional relationship between the amount of material removed and the processing time, and the processed surface acquires a mirror finish. Moreover, for tools with shorter permanent magnets, the circularity is improved by processing.
Material aging diagnosis system using magnetic NDE
Authors: Kosaka Daigo , Kojima Fumio , Tanaka Rika
Published: December 2018

This paper discusses material aging diagnosis what uses a non-destructiveness evaluation system. The diagnosis is based on magnetic characteristics of material. It is well known that the magnetism of strong magnetic materials is extremely sensitive with respect to the change of microstructure and to residual-stress variation. For example, coercive force and minor-loop coefficients have shown a linear relationship with rolling reduction. We have proposed a method what is an impedance measurement of a sensor. The method needs a magnetizer with one coil and an impedance meter. The method is simpler than a method what use coercive force. We have compared the method with a method what is a measurement of coercive force. Relationship between strain of carbon steels and experimental results of using coercive force or impedance measurements has measured. Carbon steel sample specimens with some strain loading in the experiment have been used. The experimental results have shown that the method can detect strain of steel just like a method of using a coercive force measurement.
Bouc-Wen modeling to hysteresis nonlinear in Macro Fiber Composite(MFC) actuator
Authors: Xue Xiaomin , Wu Xiaohong , Chen Luqi , Sun Qing
Published: December 2018

Hysteresis is an important nonlinear effect exhibited by the Macro Fiber Composite (MFC) that is testified from experimental study. In order to interpret the characteristic accurately, various models were proposed previously, in which the Bouc-Wen model has gained more interest because of its capability to match a wide class of hysteretic systems. However the model consists of a set of differential equations where multi parameters present need to be estimated simultaneously. In view of this, the present study sets out to propose a more efficient Genetic Algorithm (GA) and a simplified Bouc-Wen model on the one hand, and on the other, the GA is applied to the model to enhance the accuracy and efficiency of the parameter estimation. Finally a large number of experimental data are used to testify the proposed approach more efficient and accurate than the other conventional methods. Also suggested are the implications of the present study on other hysteretic models or other complex mathematical models.
Study on the nonlinear electro-mechanical model of macro fiber composite
Authors: Chen Luqi , Zhang Ping , Wu Xiaohong , Sun Qing
Published: December 2018

This paper presents a modified Preisach model to describe the nonlinear hysteresis property of Macro Fiber Composite (MFC). In order to apply the proposed model, two necessary and sufficient inherent properties which exist in most piezoelectric materials should be met, which are referred to as the wiped-out and the congruency. By using the hysteresis properties and the identified database, the numerical expressions of the proposed modified Preisach model are presented for different inputs in detail. Then several waveforms of input excitation schemes are experimentally realized in order to demonstrate the effectiveness of the modified Preisach model. The good agreement between the measured and predicted results show that the modified Preisach model is an effective mean for predicting the hysteresis of the MFC actuator system.
Normal permeability of grain non-oriented, grain oriented and amorphous electrical steel sheets
Authors: Hihat N. , Lecointe J.-Ph. , Ninet O. , Duchesne S. , Napieralska E. , Wiak S.
Published: December 2018

This paper presents the normal permeabilityμ _z of different grades of electrical sheets (Grain oriented, non oriented and amorphous). A specific test bench allows determining the intrinsic static B(H) cycle. The magnetization in static mode makes it possible to suppress the eddy current influence, contrary to others classical methods. The B–H curves of different materials are provided up to the saturation and the μ _z permeability can be directly implemented in Finite Element software applications.
Electromagnetic model of EV wireless charging systems in view of energy transfer and radiated field control
Authors: Ibrahim Mohammad , Bernard Laurent , Pichon Lionel , Razek Adel
Published: December 2018

A wireless charging system for electric vehicle (EV) is considered. A 3D Finite Element (FE) model of the inductive coupler is developed in order to compute the inductances and the radiated magnetic field around the system. In addition, a circuit model associated to field computation allows determining the electric behavior of the system during charging. Simulation results are then validated by comparison with experimental measurements. The developed model allows the design of the system considering the optimization of the energy transfer and the radiated electromagnetic compatibility (EMC) compliance.
Design of nanocomposite EMC structures via unconditionally-stable nonstandard time-domain schemes and efficient GPU implementation
Authors: Pyrialakos Georgios G. , Kantartzis Nikolaos V. , Tsiboukis Theodoros D.
Published: December 2018

A consistent time-domain methodology for the systematic design and broadband assessment of complicated nanostructured EMC devices is introduced in this paper. The novel technique combines a family of nonstandard locally one-dimensional finite-difference time-domain schemes with the advanced features of contemporary graphics processor units in general curvilinear coordinates which preserve the hyperbolic profile of Maxwell's laws. In this way, the resulting formulation remains completely explicit and generates effective dual meshes free of artificial vector parasites or spurious modes, while the frequency-dependent attributes of every setup are successfully modelled. Numerical results reveal the significant reduction of dispersion errors along with the considerable speedup compared to serialised realisations through various fabric/epoxy devices with nanocomposite media.
Dielectric loss law of asphalt mixture under the condition of microwave heating
Authors: Sun Tongsheng
Published: December 2018

In order to improve energy conversion efficiency of asphalt mixture during microwave heating, key characteristic parameters are researched. Attenuation law of electric field intensity and dielectric loss in asphalt mixture are discussed and conversion model between thermal field and electric field is built. Results show that: (1) electric field intensity attenuates with the increase of the measuring depth of microwave, and the utilization rate of electromagnetic energy increases with attenuation constant; (2) electric field intensity also attenuates with the increase of dielectric permittivity and dielectric loss tangent of asphalt mixture; (3) temperature of asphalt mixture can be significantly improved by enhancing intensity of internal heat source. The findings can provide the theoretical basis for selection of asphalt pavement material, establishment of microwave recycling theory and design of microwave heating equipments.
Thermodynamic permeability and permittivity of polarizable systems
Authors: Zimmels Y.
Published: December 2018

Relative and absolute thermodynamic permeabilities are defined as system variables and supplements to the classical point permeability, which expresses the ratio of \mathbf{B} to \mathbf{H} , at the position where these vectors exist. The thermodynamic permeability gives a measure for the net contribution of a system to the energy stored in the field, and as such it reflects also the effect of constraints that are imposed on this field. If the system is permeable, then a fixed \mathbf{B} field involves a negative absolute thermodynamic permeability, whereas the reverse is true in a fixed \mathbf{H} field. It is shown that weighted average permeabilities of systems that are either connected in parallel, with \mathbf{H} being uniform across them, or in series, with \mathbf{B} being uniform, are a direct consequence of related thermodynamic permeabilities. Derivatives of point permeabilities and thermodynamic permeabilities are used to define sets of field dependent temperature, pressure and chemical potential. Whereas the field dependent temperature, pressure and chemical potential are functions of a derivative of the point permeability, the pressure is a function of such a derivative as well as of the thermodynamic permeability. Examples of thermodynamic permeabilities which are obtained for toroids of different properties and for a sphere in a uniform field are illustrated and discussed. It is shown that in the case of the sphere, the thermodynamic permeability reflects the effect of partition of its own energy within and outside its physical boundaries. Furthermore, the field dependent entropy, temperature, pressure and chemical potential, of the matter enclosed within the sphere depend on properties of its own as well as on those of its surroundings. Finally, the results obtained for magnetic fields apply to electric fields once the relevant magnetic variables are replaced by their electric counterparts.
Modeling magnetostrictive generation of elastic waves in steel pipes, I. Theory
Authors: Sablik M.J. , Rubin S.W.
Published: December 2018

This paper investigates the problem of magnetostrictive generation of elastic waves in steel pipes. The elastic waves are generated by alternating current in a coil about the pipe in a static axial magnetic field. Electromagnetic theory is used to develop solutions for changing electromagnetic fields induced in the pipe, which are needed for coupling magnetostrictively to elastic waves. Elastic wave equations with magnetostrictive driving terms are then solved for the elastic wave solutions. The elastic wave solutions so generated correspond to the L(0,1) and L(0,2) modes for a cylinder, for the frequency range and cylinder geometry considered. Other cylindrical modes do not appear because of the axisymmetric way in which the waves are generated. Comparison with experimental data shows good agreement with the elastic wave dispersion found numerically from the theory. Predictions are made for the wave amplitudes at various frequencies, incorporating both radial and longitudinal displacements into the total amplitude.
Control of flywheel system with high-Tc superconducting bearings
Authors: Nagaya Kosuke , Kanno Kouichi , Hayashi Nobuyuki
Published: December 2018

The high-Tc superconducting levitation system is stable in both radial and axial directions without contacts, so it has been applied as bearings of an energy storage flywheel. To have high efficiency, the rotating speed of the wheel is significantly high, and it is necessary to pass through critical speeds. Rotating tail stocks are often attached at both ends of the shaft, and those are removed after passing through the critical speeds. But the method is complex in practical use. The present article discusses a method for passing through the critical speeds by using magnetic actuators. The analytical results for the system are first obtained, then a control method for the system is presented. Numerical calculations are carried out for a typical problem, and it is ascertained that the present system and control method are applicable to high-Tc superconducting bearings.
Neural network approach to structural optimization: boundary conditions case
Authors: Ratajewicz-Mikolajczak Elzbieta , Sikora Jan
Published: December 2018

An electrical field model governing copper electrodeposition process on printed circuit board (PCB) aided by the presence an ultrasonic field is presented in this paper. The problems associated with plating of copper and the current distribution into through-holes and advantages gained by ultrasonic intensification of the electrodeposition process are well known and are the subject of many investigations. Our experiments indicate that a copper layer in a through-hole grows faster than on their flat surface of PCB in this process.

On the basis of measurements, a numerical (FEM) model has been proposed. The inverse problem has been formulated for coupled (a boundary conditions) fields making it possible to control the current density and the layer thickness. An artificial neural network is applied to solve this problem.
Optimal synthesis methodology of nonhomogeneous structures under the influence of electromagnetic waves
Authors: Gusev Evgeny L.
Published: December 2018

The problem of the optimal synthesis of inhomogeneous structures of a discrete set of materials under wave influence is considered. It is established that in the interdependence between parameters of structures that realize the limiting possibilities some order or inner symmetry may exist under certain conditions. This fact allows to solve the problem of synthesis of layer structures in a straightforward way.
Nondestructive evaluations of iron-based material by magnetic diagnosis tools
Authors: Yamada Koji , Shoji Shin-ichi , Isobe Yosihiro
Published: December 2018

Magnetic properties have been investigated for a diagnosis tool of iron-based material of A533B, SUS304 in an applied stress range up to 640 MPa, by using a leakage magnetic flux sensor of GaAs Hall element, a magnetic noise pickup coil and by observing X-ray diffraction. The magnetic Barkhausen jumps were observed at an optimum field sweeping condition of 140kA/ms at which 2-D fractal dimension was found at 1.6\pm 0.3 . In this condition, averaged magnetic fields for discontinuous magnetizations were evaluated as a monotonic increasing parameter with increasing residual stresses, insensitively to the geometrical configuration between the sensing pick-up coil and the yoke in a wide residual stress range between 0.1 and 8%. stresses in the L\"uders band were found tilted around 35 degrees. The surface leakage flux and the magnetic noise observations in this study were found detectable for the material surface less than about 50 \mu m.
Boundary integral formulation of the plane theory of thermo-magnetoelasticity
Authors: Abou-Dina M.S. , Ghaleb A.F.
Published: December 2018

The purpose of this work is to present a general formulation of the static, linear plane strain problem of uncoupled thermo-magnetoelasticity for isotropic media occupying simply connected regions, based on the combined use of the stress function and of the boundary integral representation technique in terms of real functions.

A new representation of the mechanical displacement vector is deduced, which makes it possible to reach a complete solution to the problem within the proposed formulation. It is assumed that the electric current inside the body has constant density. Different thermal and mechanical boundary conditions are considered. A simple application for the circular cylinder carrying a steady axial current is solved and the results are analyzed and compared to those existing in the literature. The obtained formulae for this case allow the determination of two material constants through careful measurements of the radial mechanical displacement and the transversal stress component at the surface of the conductor.
Homogeneous softening and shape memory effect of Zr-Al-Ni-Cu glass applicable to micro-actuators
Authors: Takashina Kentaro , Yabe Hiromasa , Oguri Kazuya , Miyazawa Yasuyuki , Nishi Yoshitake
Published: December 2018

In order to evaluate the adaptability for supporting material for micro-actuator, mechanical properties ( P_c^{\rm mid},\ d_c^{\rm mid} and E_c^{\rm mid} ) were measured by means of Vickers indentation method. The high ductility and high stiffness were observed for the slowly cooled glass sample. In addition, the high deformability was confirmed for the slowly cooling sample above the glass transition temperature. Since the shape memory metallic bi-glass can be applicable to micro-actuator under irradiated conditions, a bimetal constructed by the Zr _{55} Al _{9} Ni _5 Cu _{31} glassy alloy and molybdenum-supporting sheet were also studied. The large shape change was observed near glass transition temperature.
Dilatometric study of Ni_{2+X}Mn_{1-X}Ga under magnetic field
Authors: Vasil'ev A.N. , Estrin E.I. , Khovailo V.V. , Bozhko A.D. , Ischuk R.A. , Matsumoto M. , Takagi T. , Tani J.
Published: December 2018

A study of polycrystalline and single crystalline Ni _{2+X} Mn _{1-X} Ga alloys by means of dilatometric and strain gage techniques shows that large strain can be induced in the temperature range of the martensitic transformation by application of an external magnetic field. The biggest strain induced by magnetic field was observed in the samples of chemical compositions where the structural and magnetic transitions couple, i.e. occur at the same temperature.
Normally-closed shape memory microvalve
Authors: Kohl M. , Göbes J. , Krevet B.
Published: December 2018

A new type of normally-closed gas microvalve is presented. The valve makes use of two micromachined SMA thin sheet devices, an active SMA device displaying the one-way shape memory effect and a passive superelastic SMA device, which maintains a normally-closed position. The outer diameter and height of the valve are 6 mm. Gas flow experiments in stationary equilibrium reveal a maximum flow of 470 standard ccm (sccm) at a pressure difference of 8000 hPa and a power consumption of 260 mW. The dynamics of heat transfer to and from the active microdevice is investigated by infrared microscopy and coupled FEM simulations. At 300 mW heating power, the heating time is about 1.2 s. Typical cooling times vary between 1.8 and 5 s depending on the gas flow.
Crack detection in lossy two-dimensional structures by means of a microwave imaging approach
Authors: Caorsi Salvatore , Massa Andrea , Pastorino Matteo , Righini Fabio
Published: December 2018

The purpose of this paper is to present a microwave imaging approach for the determination of the position, the orientation and dimensions of a crack located inside a lossy dielectric host medium. The inversion procedure is based on a genetic algorithm which allows to iteratively generate a sequence of trial solutions minimizing a suitable cost function. The dependence of the performances of the proposed microwave imaging approach on the conductivity value of the host medium is checked. Moreover, the robustness of the algorithm to operate with noisy data is evaluated. Finally, the reconstruction of an irregular crack is considered.
Polarization conversion in chiral layers with periodically arranged metallic helices
Authors: Raghavendra S.C. , Khan Iqbal Ahmed , Raibagkar R.L. , Kulkarni A.B.
Published: December 2018

The polarization properties of periodically arranged metallic helices are investigated. The chiral layers have been synthesized by embedding right handed or left handed metallic helices arranged periodically in a dielectric matrix of thermocol (polystyrene foam), a low loss dielectric material. The chiral layers are loaded at the aperture of the transmitting rectangular waveguide horn antenna. The polarization pattern of the transmitted signal (TE _{10} mode) indicates rotation of plane of polarization and partial conversion into either right circular polarization(RCP) or left circular polarization (LCP).
Bleustein-gulyaev waves in piezoelectromagnetic materials
Authors: Yang J.S.
Published: December 2018

An exact solution of the three-dimensional equations of piezoelectromagnetism is obtained. The solution represents a generalized version of the well-known Bleustein-Gulyaev surface waves in piezoelectric ceramics.
The influence of initial fields on wave propagation in piezoelectric crystals
Authors: Simionescu-Panait Olivian
Published: December 2018

In the present paper we study the effects of initial deformations and electric fields on the behaviour of the {\it electromechanical coupling coefficients} and on the shape of the {\it slowness curves}, in the case of progressive wave propagation in 6mm-type piezoelectric crystals along the symmetry axis, resp. in the plane normal to the previous axis.
Phenomenological approaches based on an integral formulation for forward and inverse problems in eddy current testing
Authors: Albanese Raffaele , Rubinacci Guglielmo , Tamburrino Antonello , Villone Fabio
Published: December 2018

Linear and nonlinear numerical formulations for an efficient solution of forward and inverse problems are summarized. The simulation tool is based on an integral formulation in terms of a two-component current density vector potential expanded over edge-elements. The methods are applied to the numerical simulation of a magnetic field sensor as well as to the crack simulation and detection via eddy current testing (ECT), comparing the results to the experimental measurements. The class of problems treated includes both thin and thick cracks in metallic plates, taking into account the possible presence of leakage in the crack as well as magnetic materials. The inversion of ECT data is carried out by means of genetic algorithms or methods, based on algorithms developed for digital communications, that allow to reduce the computational cost for the solution of the inverse problem.
Process integration -- A challenge for eddy current and micro-magnetic NDT
Authors: Dobmann Gerd
Published: December 2018

Non-destructive characterization (NDC) of materials is a technology of increasing application by industrial users for process monitoring and control. The main reason for this fact in materials processing is the need for a better process understanding and mastering in order to produce quality according to a zero-defect-principle and the objective to reduce non-conformities compared with a given quality specification. This means, integration of NDC by use of intelligent sensors into monitoring and control systems to predict mechanic properties and to detect and document their discontinuities (hardness, hardness depth, yield strength, deep drawability, residual stresses, etc.).

NDC-technology, which in the last two decades was mainly pushed by research and development in different national and international program [1] now, is matured for a wider range of applications. The special emphasis of the contribution is to give characteristic examples, which illuminate mainly the gain in economical benefit.

Eddy current and micro-magnetic techniques have a special advantage to be applied for the mentioned objectives, because electrical and micro-magnetic intrinsic properties and mechanic properties are influenced by the same microstructure parameters and their changes during material processing and material degradation. Furthermore they are sensitive for load-induced and residual stresses. However, their application is restricted to ferromagnetic materials and material phases.
Noncubic cell time-domain method in 3-D coordinates using prism cells applied PML absorbing boundary conditions
Authors: Harada Norihiko , Hano Mitsuo
Published: December 2018

We propose an application of the PML absorbing boundary condition to a noncubic cell time-domain method using prism cells for 3-D full-wave analysis. To verify that the noncubic cell time-domain method can accurately simulate pulse propagation on microstrip waveguide terminated by applying the PML absorbing boundary conditions, we extracted S-parameter from a simulation of pulse propagation on a right-angled bend discontinuity. The performance of the noncubic cell time-domain method is shown and it exhibits superior accuracy in a large chamfer degree as compared with FD-TD results.
A global optimization approach for the synchronous motors design by finite element analysis
Authors: Cirio Luigi , Lucidi Stefano , Parasiliti Francesco , Villani Marco
Published: December 2018

The aim of this paper is to propose a global minimization algorithm belonging to the class of Controlled Random Search algorithms, to interface with the Finite Element analysis procedure for optimizing the design of Buried Permanent Magnet Synchronous motors and Synchronous Reluctance motors.

The behavior of the proposed algorithm has been compared, in terms of attainable optimum and computation time, with the one of a minimization procedure available at commercial software. This comparison has shown a significant more efficiency of the considered algorithm especially in the more complex designing of a Synchronous Reluctance motor.

The goodness of the results achieved with the proposed algorithm shows that combining the FE analysis with a suitable strategy is an effective and powerful tool for the design optimization of electric motors.
Extensional vibration of a nonuniform piezoceramic rod and high voltage generation
Authors: Yang J.S. , Zhang X.
Published: December 2018

A one-dimensional analytical model is developed from the three-dimensional equations of linear piezoelectricity for Rosen piezoelectric transformers operating with extensional vibration modes of non-uniform piezoelectric ceramic rods for generating high electric voltages. Free and forced vibration analyses are performed. Vibration frequencies and mode shapes are obtained showing the mechanism of Rosen transformers. Nodal point of the operating mode is determined for the purpose of mounting. The transforming ratio, input impedance, and the efficiency of Rosen transformers and their dependence on various parameters are examined. In particular, it is shown that the slenderness of Rosen transformers implies high voltage generation. The results are useful in the understanding and design of Rosen piezoelectric transformers.
Stress concentration in an inhomogeneous piezoelectric slab with crack under constant longitudinal shear
Authors: Ayad M.M.
Published: December 2018

We investigate the singular stress and electric fields in an orthotropic, nonhomogeneous piezoelectric ceramic strip containing a Griffith crack under longitudinal shear. The crack is situated symmetrically and oriented in a direction parallel to the edges of the strip a non-homogeneity is taken along a direction normal to the edges and is assumed to follow an exponential law. This allows to model a variety of media with material constants that vary monotonically along a certain direction.

The mathematical problem is reduced to the solution a pair of dual integral equations which are transformed, in turn, into an infinite system of linear algebraic equations solved by Gauss's elimination method. Numerical values for the stress intensity factor a energy release rate are obtained and the results are graphically represented to display the influence of the considered nonhomogeneity.
Vibration control of milling machine by using auto-tuning magnetic damper and auto-tuning vibration absorber
Authors: Nagaya Kosuke , Kobayasi Jyoji , Imai Katuhito
Published: December 2018

This paper presents a method of micro-vibration control of milling machine heads by use of a vibration absorber. The principle used in this paper is different from that of usual absorbers. An auto-tuning vibration absorber is presented in which the absorber creates anti-resonance state. When the anti-resonance is used, the damping has to be significantly small, so it is difficult to suppress higher modal vibrations. In order to suppress higher modes, an auto-tuning magnetic damper is used. It damps higher modal vibrations, but it also increases the principal vibration. Then a method of optimal auto-tuning control is presented in which both principal and higher modal vibrations are suppressed. Experimental tests are carried out for an actual milling machine, and cutting tests are also performed.
Computation of levitation force in a highly magnetized HTS bulk magnet system
Authors: Hahn Seung-yong , Hahn Sungchin , Hahn Song-yop
Published: December 2018

Levitation force between a highly magnetized superconducting bulk magnet (SBM) and a permanent magnet (PM) was numerically calculated considering non-linear J-E relation of a SBM and demagnetization of a PM. The variation of the levitation force was found according to operating temperatures, maximum trapped flux densities of a SBM, and gap distances between a SBM and a PM. Saturation of the levitation force was found. The results of this research could be applied to achieve an optimal design of a real levitation system using SBMs and PMs.
Maximum power control for a photovoltaic power generator not requiring detailed system information
Authors: Takahara Kenji , Yamanouchi Youichi , Kawaguchi Hideki
Published: December 2018

The purpose of the present study is to construct a system to maintain the output power of the photovoltaic power generation system (PV system) at its maximum power levels. The switch duty ratio of the DC-DC converter of the PV system and its output power are selected as the input and output values, respectively. The characteristics of the PV system, which are described by the characteristic curves, are changed according to changes in external environmental conditions, such as atmosphere, loads and so on. In this study, the characteristic curves are considered to be approximated by quadratic functions and their gradients by linear functions. The change in the switch duty ratio is determined by the fuzzy controller, based on the characteristic curves and their gradients estimated by an adaptive algorithm.
Fractal antenna application to satellite communications
Authors: Verringer Joseph , Nafalski Andrew
Published: December 2018

Recent developments in antenna design have led to fractal arrays -- recursively generated objects where successive dimensions are fractional. These arrays can provide frequency independent, multi-band characteristics that can be used to electromagnetically design an antenna that exhibits good properties over two widely separated frequencies for the purpose of satellite communications. The fractional design results are compared in the paper to simulation results in order to analyse the performance at the required frequencies.
A study of a magnetic damper using rare-earth magnets and a pinned displacement magnifying mechanism
Authors: Matsuoka Taichi , Ohmata Kenichiro
Published: December 2018

A new type of magnetic damper using rare-earth magnets and a pinned displacement magnifying mechanism has been developed. The magnifying ratio and the resisting force characteristics of the damper and its effects of vibration suppression for a piping system were discussed experimentally, theoretically and numerically.
Stress effect on hysteretic magnetization curve of nickel
Authors: Suzuki Takaaki , Baba Hidehiro , Matsumoto Eiji
Published: December 2018

In this paper, the magnetic constitutive equation of the magnetoelastic material with hysteresis is presented. The proposed equation exhibits both the hysteresis and the stress dependence of the magnetization curve. To verify the constitutive equation, the magnetization under the stress is measured. In this test pure nickel is used, which has especially large stress dependence of magnetic properties. Theoretical results are found to be in very good agreement with the experimental data.
Modeling the temperature dependence of magnetization processes in soft ferrite cores
Authors: Caltun Ovidiu Florin , Andrei Petru , Stancu Alexandru
Published: December 2018

The shape of the hysteresis loop of MnZn ferrites depends on temperature. By increasing the temperature, the squareness of the loop increases. Consequently, the magnetic properties change the power losses and the performances of the ferrites. In this paper, a comparison is made between the calculated hysteresis loops in Jiles-Atherton model and the experimental loops. The influence of temperature and of the microstructure (size of the grains, pores and segregation) on the model's parameters is discussed.
Monte Carlo simulations of interaction effects on magnetic viscosity in ferromagnetic granular media
Authors: Verdes C.G. , Diaz B.R. , Chantrell R.W. , Thompson S. , Stancu Al.
Published: December 2018

A Monte Carlo time and temperature dependent model was developed to simulate magnetization processes in fine ferromagnetic particle media. The model uses a combination between a time dependent Stoner-Wohlfarth model and a standard Metropolis algorithm to find the magnetization of single-domain particle systems. Both magnetostatic and exchange interactions are introduced explicitly.

Variation of magnetic viscosity with interactions and temperature is studied. Results show that viscosity exhibits a maximum around coercive field. The value of this maximum is closely related to the strength and the origin of interactions as well as to temperature. Dipolar interactions decrease the viscosity and broaden the viscosity vs. field curve, while exchange interactions lead to an increase in viscosity around coercive field. An increase in temperature up to the critical temperature for the superparamagnetic behavior leads to an increase in viscosity. Further increase of temperature produces a decrease in viscosity.
Effective design of extended grounding systems
Authors: Lorentzou M.I. , Hatziargyriou N.D.
Published: December 2018

Grounding systems have to be effectively designed in order to prevent electrical installation from excessive overvoltages and potential gradients when lightning occurs or in case of short circuit. Effective design of extended grounding systems as in case of windfarms grounding is investigated in terms of combining good performance in high and in low frequencies.
Effects of magnetism on the electronic structure and pairing mechanism in oxide superconductors
Authors: Gavrichkov V.A. , Kuz'min E.V. , Ovchinnikov S.G. , Mamalis A.G.
Published: December 2018

Generalized tight-binding method is developed to strongly correlated electron systems. Evolution of the band structure of CuO _2 layer with hole doping from the undoped charge transfer antiferromagnetic insulator to the optimally doped paramagnetic metal is obtained. Effective low energy Hamiltonian is given by a t-J-I model that allows to compare magnetic mechanism and symmetry of pairing in cuprates and ruthenates on equal footing.
Design analysis on the magnetic field control system in compact ITER
Authors: Senda Ikuo , Shoji Teruaki , Araki Masanori , ITER Japan Home Team Group: , ITER Joint Central Team Group:
Published: December 2018

The system analyses of the magnetic field control system in the International Thermonuclear Experimental Reactor (ITER) are described. The analyses are performed by using a model of the closed loop system, which consists of the data analysis of diagnostics, the controller, the power supply of coils and the tokamak plant. The characteristics of the magnetic field control system in ITER are discussed and it is shown that the control system designed during the ITER engineering design activities satisfies its requirements. The important roles of eddy currents in optimizing the magnetic field control system in ITER are also discussed.
Electromagnetic retarder design using finite element analysis
Authors: Enokizono Masato , Todaka Takashi , Takahashi Hideki
Published: December 2018

The electromagnetic retarders are widespread in heavy vehicle and train industry. The electromagnet type and permanent magnet type retarders are developed at a variety of operating forces to reduce speeds. This paper describes the use of the finite element method with an upwind interpolation function in designing the permanent magnet type retarder. The equation of motion was solved for the analysis of the deceleration process of the conductive plate. The suitable permanent magnet anangements and the yoke constructions are made clear in the obtained numerical results.
Performance characteristics improvement of a PM disk motor by using soft magnetic composite material
Authors: Cvetkovski Goga , Petkovska Lidija , Cundev Milan , Gair Sinclair
Published: December 2018

The paper presents a comparison of the magnetic field and magnetic characteristics of a PM disk motor with laminated magnetic stator open slot core, laminated magnetic stator closed slot core with soft magnetic composite and soft magnetic composite stator core. The data for this analysis is provided by a 2D FEM calculation of the magnetic field. After the proper modelling of the motor a calculation of the magnetic field for no load and current load is performed, for the three models. The results of the magnetic field distribution, air gap flux density distribution and the values of the magnetic and electric parameters for the three models are also presented.
Properties of second-order edge elements
Authors: Igarashi Hajime , Honma Toshihisa
Published: December 2018

This paper discusses properties of the second-order edge elements for the finite element analysis. It is shown that the condition number, which dominates the convergence of the ICCG method, can be different even for the equivalent second-order elements which have common basis vectors. Moreover the computed eigenvalues and condition numbers of the local and global stiffness matrices are shown to be consistent with the reported convergence of the ICCG method. It is suggested that the spectrum of the local stiffness matrix is useful for prediction of the ICCG convergence.
The JAERI superconducting free-electron laser: Recent progress and future plans
Authors: Hajima Ryoichi , Nishimori Nobuyuki , Nagai Ryoji , Shizuma Toshiyuki , Sawamura Masaru , Kikuzawa Nobuhiro , Minehara Eisuke J.
Published: December 2018

We present recent results and future plans of the JAERI free-electron laser driven by a superconducting linac. These are experimental results of high-power IR lasing, third harmonic lasing, design and construction of energy-recovery system, and future extension to shorter wavelength.
CW microtron with a 500 MHz RF cavity for industrial applications
Authors: Tanaka Hirofumi , Pu Yuehu , Kim Tae Hyun , Makita Yo , Tsukishima Chihiro , Nakanishi Tetsuya , Nakamura Shiro
Published: December 2018

A CW microtron with a 500∼MHz RF cavity is proposed for industrial applications. The machine is of a racetrack type. The acceleration energy and the beam power of a prototype machine are 5 MeV and 30 kW, respectively. The RF cavity is a conventional normal-conducting 2-cell cavity with coupling slots. The injection energy is 80 keV, and a 500 MHz CW gun is used. The bending magnets are divided into two subsections to adjust the acceleration phases of every turn. Beam tracking studies show that the longitudinal phase stable region is more than 20 degrees and the transverse beam stability can be obtained with fringe fields of the bending magnets and two QMs near the RF cavity.
Electron cooling of ion beam with large momentum spread
Authors: Fadil H. , Shirai T. , Iwashita Y. , Noda A. , Noda K. , Beutelspacher M.
Published: December 2018

We investigate a scheme for electron cooling of ion beams with large momentum spread of ± (1%) accelerator (IndAcc) is utilized to accelerate or decelerate the stored ion beam in order to shift its momentum distribution toward the sensitive region of the electron cooling force. This method will be applied for further cooling of phase rotated hot ion beams produced by a high-power short pulse laser, to be used as an injection beam for synchrotron. Also, an induction accelerator has been designed for construction at the HIMAC ring, which will be used to test the feasibility of the present sweep scheme experimentally.
Phase rotation scheme of the ions accelerated by an intense femtosecond Laser
Authors: Nakamura S. , Morita A. , Iwashita Y. , Shirai T. , Noda A. , Daido H. , Kato Y.
Published: December 2018

A phase rotation scheme is investigated for the ion beam that is emitted from foil target irradiated by a high power (100 TW) short-pulse (20 fs) laser. By application of an RF electric field synchronized with the laser pulse, the ion beams in the energy range of ± 5% our goal. Assumed parameters are 144 MHz for RF frequency and 280 kV RF amplitude for C ^{6+} with center energy of 2 MeV/u using ±π/4 RF phase range. We think that a quarter wave resonator with double-gaps is a good candidate for the RF-cavity. The gap length is 2 cm.
Impedance analysis of bunch length measurements at the ATF damping ring
Authors: Bane K.L.F. , Naito T. , Okugi T. , Qin Q. , Urakawa J.
Published: December 2018

We present energy spread and bunch length measurements at the Accelerator Test Facility (ATF) at KEK, as functions of current, for different ring rf voltages, and with the beam both on and off the coupling resonance. We fit the on-coupling bunch shapes to those of an impedance model consisting of a resistor and an inductor connected in series. We find that the fits are reasonably good, but that the resulting impedance is unexpectedly large.
AC susceptibility in high-temperature superconductors
Authors: Mahel Michal
Published: December 2018

We present the experimental results of the AC susceptibility of YBaCuO. Presence of magnetic hysteretic features is analyzed and ascribed to granular nature of YBaCuO. We discuss the necessity of treating the high-temperature superconductor as a granular-like system with grains embedded in a weakly superconducting host.
Trapped magnetic field of mini-bulkmagnet with different arrangements of bulk superconductors
Authors: Kamijo Hiroki , Fujimoto Hiroyuki
Published: December 2018

We have fabricated a 198 mm × 99 mm bulkmagnet consisting of arrayed melt-processed Y-Ba-Cu-O bulk superconductors that are 33 mm × 33 mm in size and 10 mm in thickness, and magnetized it by the field-cooling method. The magnetic field distribution of the bulkmagnet may be controlled by changing the bulk superconductor arrangement, because a number of bulk superconductors are arrayed in rows and columns. In this study, we performed flux-trapping experiments of the mini-bulkmagnet for three different bulk superconductor arrangements. As a result, it was proved that the magnetic field distribution could be controlled by changing the bulk superconductor arrangement.
New model for two-dimensional analysis of electromagnetic field in high critical temperature superconducting filament
Authors: Hashizume Hidetoshi , Suzuki Manabu , Toda Saburo
Published: December 2018

A new two-dimensional model for electromagnetic field analysis is proposed to evaluate the current distributions in high critical temperature superconducting filament. The model is based on the results calculated by exact three-dimensional analysis. By using the new model, quench propagation is evaluated, which shows more robustness against the quench propagation.
Net-shape manufacturing of high temperature superconductors for application in electricity and transportation
Authors: Mamalis A.G.
Published: December 2018

High-energy rate powder compaction techniques, like explosive and electromagnetic compaction, may be considered as a tool to produce superconductive ceramics with unique properties. A very great novelty is indicated from the subsequent mechanical processing of the densified high-Tc superconducting ceramics, employed to produce a sound final product. Wires, rods, plates, strips and forged parts with superconducting core and metal sheath can be produced by various techniques, like wire-drawing, extrusion, rolling and forging and subsequent metal removal processing, e.g. machining and grinding. High temperature superconducting materials possess electrical/electronic and magnetic properties of utmost importance, one of which is the high-current carrying capability of superconductors with small cross sections. Thus, they can be used as power transmission cables or other functional elements in synchronous generators, levitated bearings, flywheels, fault current limiters and electrical switchgears for energy storage. An account of the above mentioned deformation processing of bulk superconductors and its applications is given in this report.
Simulation of magnetic fields in the vicinity of electrical power lines
Authors: Nafalski Andrew , Roy Nirmal , Göl Özdemir
Published: December 2018

Modelling and prediction of magnetic fields in the vicinity of electrical power lines is an important contribution of electrical engineering to the clarification of uncertainty of the effects of low intensity magnetic fields on the living environment. The paper reports on investigations that use neural networks for the prediction of magnetic fields from power lines. Additional consideration is given to the lateral profile of magnetic fields as a result of asymmetry of the load in transmission and distribution lines. Results of both assessments can be used in epidemiological and other studies.