bluuebunny/crossref_metadata_2025 huggingface dataset:
Ferroresonance circuit exhibiting chaotic phenomenon: Rule extraction from nonlinear systems
Authors: Endo Hisashi , Marinova Iliana , Hayano Seiji , Saito Yoshifuru
Published: December 2018

This paper investigates a rule of nonlinear systems exhibiting chaotic phenomena. A typical ferroresonant circuit is studied by the Chua-type magnetization model representing magnetodynamics. The nonlinear calculation with state variable equation is carried out to clarify the ferroresonant phenomenon. The characteristic values of the state transition matrix are also calculated in each of iteration steps. It reveals that they have no hysteretic properties even though chaotic behavior is exhibiting.
Multiscale modelling of the magnetostrictive behaviour of electrical steels – demagnetising surface effect and texture gradient
Authors: Daniel Laurent , Hubert Olivier , Billardon René
Published: December 2018

The magnetostriction strain is very sensitive to crystallographic texture, even for quasi-isotropic materials. A multiscale approach has been proposed to model the phenomena, taking into account the usual cubic anisotropy at the grain scale, and the heterogeneous orientation of the grains at macro scale. Experimental and modelled data are in good agreement for uncoupled properties. It is shown that a specific demagnetising surface effect must be taken into account in the description of the anisotropy to improve the modelling of magnetostriction.
Thermal responses of a thermoelectric SMA manipulator
Authors: Luo Yun , Yakuma Kumiko , Takagi Toshiyuki , Maruyama Shigenao
Published: December 2018

This paper investigates the thermal responses of a shape memory alloy (SMA) manipulator driven by thermoelectric modules. We propose the use of heat transfer by thermoelectric modules for fast cooling and thermal control of the SMA manipulator in various temperature ranges. The approaches to enlarge the applicable temperature range of the SMA manipulator have been discussed based on the numerical simulation.
Reconstruction of magnetic charge densities using regularization of bounded variations under noisy observations
Authors: Kojima Fumio , Ito Kazufumi
Published: December 2018

This paper is concerned with computational and regularization techniques for recovering induced magnetic fields due to the existence of cracks. The problem is formulated as an inverse problem with a set of source functions of the distribution type. The regularization of bounded variation is effectively used for solving the severe ill-posed problem. A iterative solver is proposed by a integro-differential equation with time marching scheme. For the practical implementation of the numerical treatment, a finite difference scheme is adopted to the proposed method with the aid of discrete fast Fourier transform. Some successful numerical experiments are demonstrated for the validity of the proposed method.
Eddy current analysis using overlap grid coordinate system
Authors: Watanabe Takashi , Todaka Takashi , Enokizono Masato
Published: December 2018

This paper presents a new finite element formulation using overlap grid coordinate system for eddy current problems. In order to solve eddy current problems that consist of several conductive objects moving in magnetic field in any directions, we have to remesh the region under consideration according to those positions in the step-by-step computation. To reduce the computation time, a composite mesh scheme is introduced into such eddy current problems. The results obtained in the verification show usefulness of this method in eddy current problems consisting several moving conductors.
Design of novel transformer cores using consolidated stacks of electrical steel
Authors: Meydan Turgut , Marketos Philip
Published: December 2018

The construction of stacked transformer cores, typically built by single layers of lamination overlapping each other, is a time consuming procedure adding to their manufacturing cost. This paper presents novel core designs made out of consolidated stacks of electrical steel, which enable the cores to be built much faster, in some cases causing a reduction in power loss compared to conventional core designs.
Newly improved magnetic compound fluid (MCF) for more stability of particle dispersion
Authors: Shimada Kunio , Shuchi Shigemitsu , Fujita Toyohisa , Miyazaki Toshio , Shibayama Atsushi , Kamiyama Shinichi
Published: December 2018

We experimentally investigated the relation of shear stress to shear rate of improved magnetic compound fluid (MCF) in engineering applications such as dampers and micro-polishing. The newly improved MCF is composed of smectite particles in a MCF previously developed by Shimada. In the new MCF, the particle distribution is more stable and the particles do not sediment. In the context micro-polishing, the relation of shear stress to shear rate in the newly improved MCF containing abrasive particles was investigated. The addition of the abrasive or smectite particles makes the shear stress change little in regard to changes in shear rate. Thus, the newly improved MCF can be applied to the micro-polishing of material surfaces at existing shear rates.
Improved modification method of spectral envelopes for the signals polluted with noise
Authors: Akita Masanori , Abe Takanori , Midorikawa Yoichi
Published: December 2018

This paper describes the spectral modification method for signals polluted with noise. In this case, the spectral subtraction method is usually used. Instead of the spectral subtraction method, the spectral features of noisy signals are modified using some rules. However, irregular modifications occur in case the environment is polluted with colored noise. In this paper, improved modification rules for adding valleys to the spectral envelopes of signals under the noise environment is presented. Two types of threshold functions are presented and the stability of the intersection point between threshold functions and original spectral envelopes improved. The improvement of the spectral shape after this modification is shown and experimental results of pattern recognition are also shown.
A new interactive visualization system with force feedback for electromagnetics education
Authors: Noguchi So , Matsubayashi Yutaka , Yamashita Hideo , Cingoski Vlatko
Published: December 2018

This paper describes an interactive visualization system with force feedback device in 3D electromagnetics. Previously, we developed the interactive system that can not only visualize some kinds of field distribution, but make a user feel the magnetic force in 2D electromagnetics simultaneously. The aim of the previous system is mainly educational because physical behavior in 2D electromagnetics is simpler than that of 3D. However, the 3D interactive visualization system with force feedback is required for design, education and so on, since the realistic model is necessarily used. Therefore, we have developed the 3D interactive visualization system with force feedback device.
On the torque production capability of a claw pole TFPM
Authors: Mansouri Ali , Njeh Anis , Makni Zaatar , Trabelsi Hafedh , Masmoudi Ahmed , Elantably Ahmed
Published: December 2018

The paper is aimed at a 3D finite element analysis (FEA) based investigation of the effects of the influent design parameters of a claw pole transverse flux permanent magnet motor (TFPM) on its torque production capability. As far as the three axially-arranged phases of the claw pole TFPM are acting independently (there is no rotating field in a chaired air gap), the present study is reduced to the case of a single phase concept. It has been clearly shown that the claw pole TFPM could exhibit a high output torque if its sizing is accurately achieved.
Reconstruction of multiple cracks in an ECT round-robin test
Authors: Rebican Mihai , Yusa Noritaka , Chen Zhenmao , Miya Kenzo , Uchimoto Tetsuya , Takagi Toshiyuki
Published: December 2018

This paper proposes an algorithm for multiple cracks reconstruction from ECT signals by means of a simulated annealing parallelized on a supercomputer. The algorithm takes not only the profiles of cracks but also the number of cracks as unknown, which is a very important feature from the practical point of view. A fast forward code using a database is upgraded for the rapid computation of the ECT signals of a differential mutual induction probe due to multiple cracks. The algorithm is applied to the reconstruction of the multiple cracks of a JSAEM round-robin test geometry. The reconstruction result using a simulated signal proves the validity of the proposed approach.
Brain haemodynamics modelling using electromagnetic systems characteristics
Authors: Čápová Klára , Čáp Ivo , Blazek Vladimir
Published: December 2018

The paper deals with modelling and simulation of a human brain arterial system using analogous electromagnetic systems, especially propagation characteristics of electric transmission lines. Cascade connection of analogous equivalent transmission line elements represents a vessel tree concerning both the electromagnetic parameters and the topology. Electromechanical analogy between physiological and electromagnetic values enables a description and following simulation of a cerebral haemodynamics by means of electric circuits analogous relations. The vascular dynamics modelling and simulation represents an important tool for the non-invasive computer-aided investigation of the brain arteries pathological deformations. The presented simulation results give the information about the blood dynamic characteristics also in the case of cerebral arterial stenoses or aneurysms under various stenosis degrees. The obtained results can provide helpful knowledge for the practical treatment of the basic brain arteries.
Element-free Galerkin method in pulsed eddy currents
Authors: Xuan L. , Shanker B. , Zeng Z. , Udpa L.
Published: December 2018

Compared with the conventional finite element method that relies on an underlying mesh and element-node connectivity to describe the geometry, meshless method shows its advantage in mesh simplification, tight crack representation and re-meshing process. An effective numerical implementation of the meshless method uses the Galerkin technique and is referred to as the element-free Galerkin (EFG) method. In this paper, the EFG method is applied to a field of electromagnetic computation, namely, simulation of pulsed eddy current testing. The model is validated against analytical solutions.
A fast global optimal technique based on combinations of improved radial basis functions and tabu search method
Authors: Luo Ping , Yang Shiyou , Ni Guangzheng , Ni Peihong , Liu Z.J.
Published: December 2018

A fast and efficient global optimal design technique based on the combination of the Response Surface Model (RSM) using improved Radial Basis Functions (RBFs) and the tabu search method is proposed. Computer simulation results on two different design problems are presented to demonstrate the efficiency and robustness as well as the advantage of the proposed algorithm for solving computationally heavy optimal design problems.
Deposit characterization by eddy current nondestructive evaluation
Authors: Bensetti Mohamed , Bihan Yann Le , Marchand Claude , Pavo Jozsef
Published: December 2018

In this paper, the eddy current nondestructive evaluation method is used to determine the electrical conductivity, the thickness and the size of a deposit located on the reverse side of a tested specimen. The eddy current probe consists in a coil. The impedance of the coil is calculated by a boundary integral method. The inverse problem is solved by combining a neural network and an iterative resolution.
Accurate fast modelling for real base station antennas using gain patterns via spherical modes
Authors: Adane Yacine , Wong Man-Faï , Gati Azeddine , Dale Christian , Wiart Joe , Hanna Victor Fouad
Published: December 2018

A new approach based on the superposition of sub-antennas radiating characteristics is used to get accurate models of real base station antennas. The sub-antennas are modelled by solving an over determined matrix equation using a least squares procedure. This process allows determining the gain of the sub-antennas while their fields are calculated analytically. The superposition of the fields of the sub-antennas gives the field of the studied base station antenna, which can then be used to assess the human exposure to the electromagnetic fields emitted by the base station antennas of mobile networks.
Unified evaluation of soft magnetic materials of sheets and ribbons for ELF magnetic shielding effectiveness
Authors: Okazaki Yasuo , Yamazaki Kenichi , Ishikawa Noboru
Published: December 2018

Magnetic shielding effectiveness of various kinds of soft magnetic materials from electrical steel sheets to amorphous and nano-crystalline ribbons was examined in the shields of same size and same thickness in the electromagnetic field of extremely low frequency range. The evaluation of material's factors for shielding effectiveness is studied and the practical selection of shielding materials was tried technologically.
A 3D integral method for modelling 3D effects in coils used in inductive processes
Authors: Gagnoud Annie
Published: December 2018

A 3D numerical method has been developed to model the coils used in inductive processes. The method is based on Ohm's law and Biot and Savart's law and can be used to solve eddy current problems at mid-range or high frequencies. The unknowns are the current density and electrical potential. The formulation involves singular integrals and produces a fully linear system, as in the boundary integral method. For these frequencies, only the surface of the conductors needs to be meshed. To obtain a general approach, the interpolation, derivation and integration techniques commonly used in the finite element method are employed. A number of examples show the interest of this method.
A new electromechanical concept for hybrid powertrains
Authors: Tahri Younes , Sahbi Mariem , Masmoudi Ahmed , Elantably Ahmed
Published: December 2018

The paper is devoted to a finite element analysis based design of an electromagnetic system dedicated for hybrid propulsion systems. It consists of two concentric permanent magnet machines, yielding the so-called "single stator dual rotor permanent magnet machine", with an inner rotor, an outer rotor and a stator sandwiched between the two rotors. In order to decouple magnetically both machines, a non magnetic material ring is inserted between the two stators. Giving the small dimensions of the inner machine, special attention is focused upon its sizing.
Eddy current data fusion for the enhancement of defect detection in complex metallic structures
Authors: Joubert Pierre-Yves , Bihan Yann Le
Published: December 2018

The authors consider the detection of cracks appearing close to the rivets in ageing riveted lap joints of aircraft structures, using the eddy current (EC) technique. As the presence of the rivets perturbs the interpretability of the defect EC signatures, the authors propose to fuse the data provided by oriented field EC sensors used in different operating modes. Different fusion rules are considered and the performances of defect detection are then characterized with receiver operating characteristic curves.
Nonparametric identification algorithm of the Preisach distribution based on the First Order Reversal Curves (FORC) diagram
Authors: Stancu Alexandru , Postolache Petronel , Stoleriu Laurentiu
Published: December 2018

In this paper we present an identification algorithm of the Preisach distribution from the FORC diagram. This method does not imply the use of an analytical function for the Preisach distribution which makes it very useful when such an approximation is not available. Test problems based on simulations made with the Generalized Preisach Model are presented and the results are discussed.
Electromagnetic characterization of material degradation due to neutron irradiation
Authors: Dobmann Gerd , Kopp Melanie
Published: December 2018

Most of the materials used in practice show degradation due to fatigue, i.e. cyclic loading. Very often other degradation mechanisms like corrosion and in the high temperature regime also creep are superimposed. In the primary circuit of nuclear power plants the material is additionally exposed to neutron irradiation. According to the licensing conditions the main focus is on the pressure vessel material. The contribution describes measurement results collected at surveillance programme specimen of different nuclear power plants in different European countries. The set of Charpy specimen was measured in the hot cell of the research reactor in Petten in the Netherlands. Electromagnetic non-destructive testing techniques were applied for characterization.
Performance evaluation of Halbach magnetized linear generator for mobile apparatus
Authors: Choi Ho-Yong , Jung Hyun-Kyo , Jung Sang-Yong
Published: December 2018

In this paper, the Halbach magnetized linear generator for charging the battery of a mobile apparatus is proposed and characteristics of the generator are investigated. Magnetic characteristics are analyzed by modified Space Harmonic Method and EMF calculation result is also included.
Improvement of shape memory effect in Fe-Cr-Co-Ni-Si-Mn ferromagnetic alloy with change of Mn contents
Authors: Szprynagcz Mariusz , Enokizono Masato , Todaka Takashi
Published: December 2018

A new ferromagnetic shape memory alloy consisting of Fe-Cr-Co-Ni-Si-Mn has been developed by means of the melt spinning technique. The alloy has both the shape memory effect and the comparatively high-magnetic permeability itself. The shape memory effect can be improved with annealing upon the alloy but at the same time it loses good ferromagnetic properties. This paper discusses shape memory characteristics measured by differential scanning calorimeter (DSC) and thermo-mechanical analyzer (TMA). Improvement of the shape memory effect is observed in samples containing manganese from 5% to 6% (weight percent), after annealing at temperature over 800°C.
In-situ eddy current monitoring under high temperature environment
Authors: Kasuya Takashi , Okuyama Takeshi , Sakurai Nozomu , Huang Haoyu , Uchimoto Tetsuya , Takagi Toshiyuki , Lu Yonggang , Shoji Tetsuo
Published: December 2018

The feasibility of in-situ Eddy Current Monitoring (ECM) under high temperature environment is discussed. For the purpose, an ECM experiment was conducted at a System Safety Benchmark Facility (SSBF), which was designed and constructed for assessing the crack growth behavior of welded pipes in a Boiling Water Reactor (BWR) environment. The target for the monitoring was a large-scale pipe specimen made of austenitic stainless steels 304, 304L and 316L, connected by weld joints of nickel based alloy 182 within the SSBF. Slits were prepared at the Heat Affected Zones (HAZs) and weld lines from the inner surface of the pipe specimen. Eddy Current Testing (ECT) probes were arranged on the outer surface of the pipe specimen at the positions where the slits had been introduced. After exerting the load, it was observed that the ECM experimental signals changed. Subsequently, the numerical simulation of eddy current signals based on the experimental conditions was carried out. As a result of comparison between experimental and numerical eddy current signals, it is shown that the in-situ ECM system makes it possible to observe crack propagation in a BWR environment.
Crack detection method using electromagnetic waves
Authors: Hashizume H. , Shibata T. , Yuki K.
Published: December 2018

The NDT method using electromagnetic waves has availability for crack detection in large pipes or structures in nuclear power plants. The purpose of this study is then, to develop a new method to determine the crack size and location with high speed and accuracy. Through this study, it has been shown that the transmitted wave carries a lot of information on crack depth and the obtained signals of reflected wave below the cut-off frequency depend on the crack position. Experimental results indicate that there exists attractive possibility in the new NDT method.
Fast and robust localization of brain electrical sources using evolution strategies: Monte-carlo simulation and phantom experiment studies
Authors: Im Chang-Hwan , Jung Hyun-Kyo , Han Jae Yong , Lee Hang Ro , Lee Soo Yeol
Published: December 2018

In this paper, μ + □ evolution strategy (ES) was applied to brain electrical source localization problems using electroencephalography (EEG). The results by the ES were compared to those by simulated annealing (SA) and genetic algorithm (GA), which have been typically used for the brain source localizations. Monte-Carlo simulation and phantom experiment study demonstrated that the use of ES could enhance both accuracy and computational efficiency.
A numerical investigation of the liquid flow velocity over an infinity plate which is taking place in a magnetic field
Authors: Bahadir A.R. , Abbasov T.
Published: December 2018

In this paper the change of the magnetohydrodynamic flow velocity of the infinite plate in the non stationary motion of the incompressible viscous liquid has been studied numerically. Outer magnetic field has been directed perpendicular to the plate and assumed moving with the plate. For the different dynamical motion of the plate, the evolution of the velocity has been investigated numerically. The magnetic field induction and the changing of the parameters of the dynamical system on a large range effect to the velocity has been investigated. At a specific point increasing of the magnetic field induction causes decreasing in the velocity. By the increasing the parameters of the manyetohydrodinamic system, the problem becomes more difficult to solve analytically. Therefore, a numerical solution technique is resorted to solve the problem approximately.
The behavior of two parallel symmetry permeable cracks in magneto-electro-elastic composites under anti-plane shear stress loading
Authors: Zhou Zhen-Gong , Sun Jian-Liang , Wang Biao
Published: December 2018

In this paper, the behavior of two parallel symmetry permeable cracks in magneto-electro-elastic composites under anti-plane shear stress loading is studied by Schmidt method. By using the Fourier transform, the problem can be solved with a pair of dual integral equations in which the unknown variable is the jumps of the displacements across the crack surfaces. In solving the dual integral equations, the jumps of the displacements across the crack surface are expanded in a series of Jacobi polynomials. Numerical examples are provided to show the effect of the length of the crack and the distance between two parallel cracks upon the stress, the electric displacement and the magnetic flux intensity factors of the cracks. The shielding effect of two parallel cracks is also obtained. From the results, it can be also obtained that the singular stress in piezoelectric/piezomagnetic materials carry the same forms as those in a general elastic material for anti-plane shear problem.
Modeling and design of passive electric networks interconnecting piezoelectric transducers for distributed vibration control
Authors: Porfiri M. , dell'Isola F. , Santini E.
Published: December 2018

In the literature collocated or distributed arrays of piezeoelectric patches are employed to actively control structural vibrations. In the present work in order to damp beam vibrations a completely passive electric controller is designed, exploiting distributed piezoelectric transduction. In this way a simultaneous multimodal vibration suppression is obtained. The optimal electric network (interconnecting the piezoelectric transducers) is synthesized as a finite differences approximation of the derived distributed (infinite dimensional) optimal controller. A prototype of the proposed novel smart structure (Piezo-ElectroMechanical beam) is designed, allowing for appreciating its technical feasibility and effectiveness.
Analysis of a thickness-shear piezoelectric transformer
Authors: Yang J.S. , Zhang X.
Published: December 2018

A theoretical analysis is performed on a high voltage piezoelectric transformer operating with thickness-shear modes using the zero-dimensional equations of a piezoelectric parallelepiped. Analytical solutions for the transforming ratio and efficiency of the transformer are obtained. Their dependence on the driving frequency, load impedance and geometric parameters are examined.
Ferromagnetic shape memory compounds with a Heusler structure
Authors: Becker S. , Brown P.J. , Dennis B. , Fröhlich K. , Kanomata T. , Matsumoto M. , Neumann K.-U. , Ouladdiaf B. , Rasch J. , Steinke N. , Stephens T. , Unverdi O. , Ziebeck K.R.A.
Published: December 2018

The martensitic phase transition in Ni _2 MnGa related alloys is investigated. The stability of the low temperature phase is assessed by a structural investigation of a cold worked sample. The stability of the low temperature martensitic phase with respect to internal strains is determined. It is argued that the experimental observations are consistent with an electronic mechanism being responsible for causing the martensitic phase transition. Alloying experiments with partial substitution of Ga by either In or Sn show a stronger dependence of the martensitic phase transition on the number of conduction electrons than on the size of atoms or variations of their distances. These experimental findings are consistent with band structure calculations and changes brought about by atomic disorder.
Rearrangement of martensite variants under magnetic field applied along [001], [011] and [111] directions in Fe-31.2mol%Pd
Authors: Sakamoto Tatsuaki , Fukuda Takashi , Kakeshita Tomoyuki , Kishio Kohji
Published: December 2018

Rearrangement of variants of an Fe-31.2mol%Pd single crystal in the field-cooling process under the magnetic fields applied along [001] _{P} , [011] _{P} and [111] _{P} (P: parent phase) has been investigated by strain measurement and optical microscope observation. The fraction of the variant, which lowers the magnetocrystalline anisotropy energy most, becomes almost 100% by the rearrangement of variants under the magnetic field applied along [001] _{P} , but does not reach 100% under the magnetic field applied along [011] _{P} . On the other hand, the rearrangement of variants hardly occurs under the magnetic field applied along [111] _{P} . Influence of the field direction on rearrangement of variants described above can be evaluated quantitatively by using the magnetic shear stress τ _{mag} and the shear stress required for rearrangement of variants τ _{req} .
Fabrication of a lead-free BNT piezoelectric material using a hybrid sintering process
Authors: Qiu Jinhao , Tani Junji , Orikasa Kazuyuki , Takahashi Hirofumi
Published: December 2018

In this study, a hybrid sintering process, which is a combination of microwave heating and hot-press, was applied to the fabrication of lead-free piezoelectric materials for the purpose of improving their performance, since the hybrid sintering process was found to be able to improve the density and consequently the piezoelectric properties of PZT and PNN-PZT materials in the former study. The lead-free piezoelectric material used in this study is BNT [(Bi _{1/2} Na _{1/2} ) TiO _3 +0.1wt%MnO _2 ]. The BNT was sintered with the hybrid process, the conventional process, the microwave process and a hot-press process and their piezoelectric properties were investigated and compared.
Novel electro-optic devices
Authors: Huang Lidu
Published: December 2018

Three novel optic components utilizing linear electro-optic effect are described for applications in voice and data communication. These active components are a tunable micro lens, variable optical attenuator, and optical switches. They are essential building blocks of planar integrated lightwave circuits and can be fabricated using mature semiconductor processing technologies. Numerical results obtained by BPM (Beam Propagation Method) show that switching and tuneablity can be realized by using commercially available electro-optic materials and semiconductor fabrication technologies.
Small-strain dynamic mechanical behavior of magnetorheological fluids entrained in foams
Authors: Maranville C.W. , Ginder J.M.
Published: December 2018

An oscillatory double-lap-shear configuration was used to study the dynamic mechanical properties in shear of magnetorheological (MR) fluids entrained in open-cell polyurethane foams. The dynamic viscoelastic mechanical properties of the fluid were studied by varying strain amplitude, frequency, and magnetic field strength. We find that these samples exhibit linear viscoelastic behavior below a threshold level of strain and only in zero applied magnetic field. Above the critical strain, and in applied magnetic fields, they behave as nonlinear viscoelastic materials with significant damping capacity that is strongly dependent on the field applied perpendicular to the direction of strain. For example, the energy dissipated by the material increases by over an order of magnitude when the flux density is increased from 0 to 0.6 Tesla. In addition, the magnitude of the complex modulus increases from 170 kPa in 0 Tesla to over 2 MPa with an applied flux density of 0.6 Tesla. We also found that the overall dynamic mechanical material properties changed very little with applied mechanical frequency in the range studied, 0.1 to 10 Hz.
Dynamic response of the piezoelectric polymer PVDF
Authors: Vinogradov Aleksandra M. , Schumacher Shane C. , Rassi Erik M.
Published: December 2018

The paper concerns the dynamic response of polyvinylidene fluoride(PVDF), a commercially available piezoelectric polymer currently used in numerous applications. The paper consists of two parts. The first part presents a summary review of recent experimental results regarding the time-dependent behavior of PVDF tested under combined static and cyclic loading conditions. It has been observed that the polymer has demonstrated accelerated creep rates due to cyclic loading effects. Cyclic creep acceleration in PVDF has been significant even in the range of stresses well below the viscoelastic linearity limit. This phenomenon, defined as "vibrocreep", appears to be essentially nonlinear, since the material response under combined static and cyclic loads did not represent a simple superposition of the responses to static and fully reversed cyclic loads applied separately. The second part of the paper provides a formulation of a nonlinear constitutive model, which describes the synergistic interaction between creep and cyclic damage evolution. The proposed constitutive model combines the concepts of linear hereditary viscoelasticity with damage characterization through a cyclic damage function. The latter is formulated using the basic principles of continuum damage mechanics. The potentials and limitations of the proposed constitutive model are discussed, and experimental results providing model validation are presented.
Wave propagation in a piezoelectric ceramic plate sandwiched between two semiconductor layers
Authors: Yang J.S. , Zhou H.G.
Published: December 2018

We study propagation of anti-plane (SH) waves in a piezoelectric ceramic plate carrying a thin layer of a semiconducting material on each of its major surfaces. Wave attenuation and dispersion caused by semiconduction as well as wave amplification by a biasing electric field are examined.
Attenuated wave propagation on a face of a cubic crystal subject to initial electro-mechanical fields
Authors: Simionescu-Panait Olivian
Published: December 2018

This paper deals with the study of the conditions of propagation of attenuated waves in cubic crystals subject to initial deformation and electric fields. The analysis is extended to all symmetry classes belonging to the cubic system, exhibiting, or not, the piezoelectric effect. We show the influence of the electrostrictive and piezoelectric effects on attenuated wave propagation in such media. We derive the velocities of propagation and the attenuation coefficients in closed-form, and we analyze the influence of the initial fields on the wave polarization in the case of propagation on a cube face. For a particular choice of the initial electric field, we obtain and analyze the generalized anisotropy factor.
Efficient method for eddy current analysis in permanent magnets of electric motors
Authors: Waszak Michal-Wolfgang
Published: December 2018

This paper presents an efficient method for eddy current analysis in permanent magnets (PM) used in electric machines. Due to appreciable electric conductivity of sintered PM the energy losses related to induced eddy currents cannot be neglected. Since the resulting increase of temperature may weaken the magnetomotive force or even demagnetize the PM material. Two numerical approaches for eddy current calculations in massive materials are commonly applied: 2d model (assuming infinite axial length) and 3d model (usually suffering from numerical inefficiency). In this paper we discuss numerically efficient method for eddy current computation taking actual axial length into account. We propose to extend the 2d field-circuit-motion time-stepping model to 3d model of induced electric field in the area of massive conducting elements, for instance, the PM of electric motor. Design study of a brushless dc motor is presented. During numerical experiments two contributions to the PM losses are characterized: idle run losses due to stator slotting, and armature reaction losses due to high frequency current switching. The influence of the PM segmentation on the eddy current losses is studied.
Dynamic model for electromechanical integrating toroidal drive
Authors: Xu Lizhong , Hao Xiuhong
Published: December 2018

In this paper, the operating principle and basic structure of the drive are introduced. An electromechanical coupled dynamic model of the drive is presented by means of electromagnetic theory and mechanical principle. The electromechanical coupled dynamic equations of the drive system are given. The concept of the electromagnetic mesh stiffness is presented and their calculating equations are obtained. Then, the natural frequencies and mode shapes of the electromechanical coupled dynamic system are analyzed. Finally, Changes of the natural frequencies of the electromechanical system along with the mechanical and electric parameters of the drive are analyzed, respectively.
Induced currents on vibrating perfect surfaces under the illumination of electromagnetic waves: One-dimensional simulation
Authors: Ho Mingtsu
Published: December 2018

One-dimensional numerical results of the induced currents on traveling and/or vibrating perfect conductor surfaces are presented in this report. The computational data are obtained using the method of characteristics with the application of the characteristic variable boundary conditions and the relativistic boundary conditions. The perfect plane may travel at a constant speed and/or vibrate sinusoidally or in zigzag with a constant frequency and a constant amplitude. The Doppler effects on both magnitude and frequency of induced currents were investigated by comparing computational results with the theoretical double-Doppler shift values. Good agreements were found. It is also found that when conductor travels and vibrates simultaneously, modulation on the magnitude of induced current is dependent on the combined instantaneous velocity while that on frequency is on the translational velocity.
Investigation of the field-induced strain of shape memory alloy in a pulsed magnetic field
Authors: Sakon T. , Takaha A. , Motokawa M. , Fukuda T. , Kakeshita T.
Published: December 2018

A system for the simultaneous measurement of magnetization and magnetic strain, which is designed to be used in a pulsed magnetic field, has been developed. In this system, a capacitor on a sample is used and its capacitance changes with the displacement of a sample due to the strain on the sample in a magnetic field. Using this system, we have studied the magnetization and magnetic field-induced strain (MFIS) of the martensitic metallic compound Fe-31.2%Pd (at. %) at temperatures down to 80 K in martensite phase, which is much lower than the martensitic transformation temperature T_{M} =230 K. A substantial MFIS has been measured under a pulsed magnetic field with the time constant 6 ms, which corresponds to 80 Hz in frequency.
Magnetocaloric effect in Ni_{2.19}Mn_{0.81}Ga Heusler alloys
Authors: Buchelnikov V.D. , Taskaev S.V. , Aliev A.M. , Batdalov A.B. , Gamzatov A.M. , Korolyov A.V. , Kourov N.I. , Pushin V.G. , Koledov V.V. , Khovailo V.V. , Shavrov V.G. , Grechishkin R.M.
Published: December 2018

The results of direct measurements of the magnetic field induced entropy change in the Ni _{2.19} Mn _{0.81} Ga alloy are presented. It is shown that the largest entropy change in the magnetic field 2.6 T is equal to 11 J/kgK. The experimental data are compared with the theoretical results, obtained with the help of the statistical and molecular field theory.
Neutron study of the martensitic transformation in Ni-Fe-Ga alloys
Authors: Gutierrez J. , Lázpita P. , Siruguri V. , Barandiarán J.M. , Henry P. , Chernenko V.A. , Kanomata T.
Published: December 2018

We present results of an extensive neutron diffraction study of the martensitic transformation in Shape Memory Alloys of nominal composition Ni _{55-x} Fe _{19+x} Ga _{26} (x=0, 1, 2) at. % transforming close to room temperature. The x=0 sample shows a martensitic transformation temperature T_{M} ≈ 250 K and Curie temperature T_{C} ≈ 289 K. Neutron measurements for this alloy were performed between 300 K (austenite phase) and 150 K (martensitic phase). At temperatures T>T _{C} we have found the coexistence of two phases: an L2 _{1} phase with space group Fm3m and cell parameter a=5.730Å and a γ-fcc with cubic symmetry and with cell parameter a=3.586Å This second phase was also detected by magnetic measurements, giving rise to a second Curie temperature of about 363 K.
Design and control of multi-step SMA actuator
Authors: Lee Yun-Jung , Son Hyung-min , Gu Jun-bum , Nam Tae-hyun
Published: December 2018

To balance the control complexity and number of controlled positions, a novel multi-step SMA actuator is proposed that has multiple controlled positions and can be actuated by sensor-less and open-loop control. The proposed multi-step SMA actuator is constructed so that several electrical taps are connected to one SMA wire and the sections between the taps are all the same length. The controlled positions then vary stepwise according to the number of actuated sections. To control the multi-step SMA actuator, a PWM(pulse width modulated) voltage with an appropriate duty ratio is applied to designated sections while considering the resistance value of the sections, as well as the recommended current for the given SMA wire. To verify the effectiveness of the proposed multi-step SMA actuator, experiments were performed using a single nitinol wire actuator with a bias spring mechanism and electronic control system.
Shape memory effect in Ti-Ta-Zr alloys
Authors: Peradze T. , Stamateli I. , Cederstrom J. , Berikashvili T. , Razov A. , Gorgadze K.
Published: December 2018

The degree of recoverable strain, reactive stress and pseudoelasticity of some Ti-Ta-Zr alloys were investigated. The measurement technique involved differential calorimetry, estimation of friction and evaluation of recoverable torsion strain. The alloys were quenched from different temperatures of the β-phase area and subjected to additional thermal and mechanical treatment required for subsequent examination. The degree of recoverable strain was measured on custom-made unit. The samples have been heated by electrical current and using a furnace. Initial deformation of the specimens was achieved by torsion. For all of the alloys the shape recovery was not less than 90–98% for initial strain up to 7–9%. M _{s} and A _{s} values for the alloys range in 298–433 K and 523–673 K interval. These allowed to conventionally consider the shape memory effect in these alloys as a "high temperature" (respectively to TiNi) phenomenon. The values of the reactive stress induced by reverse martensite transformation in the alloys was measured to be 300–550 MPa. After 3–4 cycles the pseudoelasticity of the alloys (strain-stress cycled at room temperature), for the initial strain– 3.5–4%, comes up to 100%.
Characteristics of smart composite wing with SMA actuators and optical fiber sensors
Authors: Yang Seung-Man , Han Jae-Hung , Lee In
Published: December 2018

Recently, morphing concepts for UAV or MAV have been significant issues in aerospace engineering. Morphing wing concept, a biomimetic technology in aerospace engineering, has been realized by various methods including changes of wing's cross-section, plan form, and spar position. This paper investigates a morphing wing with variable camber using SMA actuators. The test model is a symmetric wing structure composed of two tapered graphite/epoxy composite plates and a steel body. Shape memory alloy (SMA) is attracting much attention as actuators for controlling the shape of structures because of high recovery force and large deformation. Four pairs of the SMA wire actuators are attached on the bottom surfaces of the wings in the chord-wise direction. SMA actuators produce enough deformation to cause significant improvement the static and dynamic characteristics of the wing model. Lift and drag forces, most important static aerodynamic characteristics, were measured at various angles of attack. Lift of the wing was increased without increasing drag forces when electric current was applied to the SMA actuators. Dynamic vibration signals were measured by FBG sensor at the root of the wing. The FBG sensor was successfully applied to the monitoring of the aeroelastic unstable phenomena at various angles of attack. At flutter speed, limit cycle oscillation with constant frequency occurred. It was also observed that the vibration energy is concentrated on the flutter mode and increased with the increase of the airflow speed. The effects of the angle of attack on aeroelastic characteristics of the wing were investigated. The amplitude of the limit cycle oscillation was significantly reduced at the flutter velocity when SMA actuators were activated.
Wearable tactile sensor system for reading braille
Authors: Miyata Kaoru , Tanaka Mami , Nishizawa Tatsuo , Chonan Seiji
Published: December 2018

This paper is a study on the development of a wearable sensor system for reading Braille. The study is intended to develop a compact tactile sensor system which uses a PVDF (Polyvinylidene Fluoride) film as the sensory receptor. The sensor is mounted onto a fingertip and moved over Braille manually to obtain the sensor output. Since the unsteady movements yield variations in the waveforms, a robust recognition system is required. The recognition system consists of three components as follows. First, the signal inputted to the system is divided into individual signals regardless of the variations in the waveforms. Next, those signals are transformed into effective feature vectors in order to suppress the variations. Finally, those vectors are classified and the results are obtained. In the process, minimum-distance classifiers and neural classifiers are used. For the investigation of experimental verification, test signals are inputted to the recognition system and the performance of the system is evaluated. The obtained results show that the wearable sensor with the recognition system is effective to recognize Braille.
Cubic-spline expansion for a two-dimensional periodic conductor in free space
Authors: Chien Wei , Huang Chung-Hsin , Chiu Chien-Ching
Published: December 2018

This paper presents a computational approach to the imaging of a two-dimensional periodic conductor. Both cubic-spline method and trigonometric series for shape description are used and compared. A periodic conducting cylinder with unknown shape in free space and the scattered field is recorded outside. Based on the boundary condition and the recorded scattered field, a set of nonlinear integral equations is derived and the imaging problem is reformulated into an optimization problem. The genetic algorithm is employed to find out the global extreme solution of the object function. It is found that the shape described by cubic-spline can be reconstructed. In such a case, Fourier series expansion will fail. Even when the initial guess is far away from the exact one, the cubic-spline expansion and genetic algorithm can avoid the local extreme and converge to a global extreme solution. Numerical results are given to show that the shape description by using cubic-spline method is much better than that by the Fourier series. In addition, the effect of Gaussian noise on the reconstruction is investigated.
Study on horizontal power assisted system for overhead crane
Authors: Miyoshi Takanori , Terashima Kazuhiko
Published: December 2018

In this paper, a power assisted system for an overhead crane is presented. This system is realized by measuring the swing angle of a crane and moving the trolley and girder in the desired direction. Therefore, operators can move a heavy object freely using only slight force. In this paper, two kinds of controllers are proposed. One is a PD controller that emulates the dynamics of object with damping and it moves the object in proportional velocity to the operating force in steady-state. Another is a PID controller that maintains the velocity of object continuously after operators cease the application of their force. Its dynamics, damping characteristics, steady-state and admissible condition of controller gain are discussed in regard to the respective controllers. This system is applied to an experimental overhead crane in the laboratory, and the effect of energy saved by the power assist is shown by measuring the heart rate of operator.
Low-frequency magnetic field detection for metal sensing
Authors: Kiwa Toshihiko , Kawata Tomoaki , Tsukada Keiji
Published: December 2018

A new type of magnetic field detection system, which can operate at a frequency below 1 kHz, is proposed and developed. The system consists of a 40-turn-coil to generate the magnetic field and a magneto resistive sensor to detect both the amplitude and the phase signal of the magnetic field induced by eddy-current and magnetization of the samples. The magnetic field detection of ferro- and non-magnetic samples using the system is demonstrated and discussed.
Magneto-impedance sensor for biomedical applications
Authors: Chiriac Horia , Herea Dumitru-Daniel
Published: December 2018

A giant-magnetoimpedance-based biosensor prototype was designed and tested by using simple glass-coated amorphous microwires and copolymer-functionalized glass-coated amorphous microwires as sensing elements, as well as two different types of magnetic microparticles as perturbating agents for the external d.c. magnetic field. The influence of the two types of microparticles and the geometry of the d.c. excitation external magnetic field on the magneto-impedance (MI) of the amorphous microwire have been studied. This type of magnetic biosensor prototype will be useful in biomolecule detection techniques.
Design of safe surgical forceps using superelastic SMAs
Authors: Luo Yun , Higa Masaru , Okuyama Takeshi , Takagi Toshiyuki
Published: December 2018

The authors propose a novel concept for less invasive hemostatic forceps. The proposed hemostatic forceps employ superelastic shape memory alloys that enable one to maintain the clamping pressure within a safe range. In this paper, the basic design of these hemostatic forceps is described. The validity of the concept is demonstrated by experimental results using a prototype.
Transaction on relax-type fluxgate magnetometers
Authors: Praslička Dušan , Mikita Ivan
Published: December 2018

Relax-type magnetometer is a simple variety of fluxgate family magnetometers, comprising high permeability non-linear core of sensing coil gathering and gating ambient magnetic field. This is to be a report on basic theory of operation and some novel research on metrological qualities.