bluuebunny/crossref_metadata_2025 huggingface dataset:
Reducing electromagnetic noise in biomedical signals
Authors: Ionita Anca Daniela , Ionita Valentin
Published: December 2018

Biomedical measurements are disturbed by electromagnetic noise that may be modelled as a sum of components with symmetrical distribution of frequencies. Therefore, theoretically, a method working in the high order spectra domain eliminates this noise; practically, simulations prove that it can significantly improve the signal to noise ratio. The paper contains a study for cleaning electromyographic and electroneurographic signals covered by Gaussian noise and periodic electromagnetic interference with low frequencies.
Rapid SAR measurement of mobile phones
Authors: Merckel Olivier , Fleury Gilles
Published: December 2018

Specific Absorption Rate (SAR) designates the electromagnetic power density deposited per unit mass of biological tissues. This paper presents a new approach where SAR calculation for mobile phones is based on a parametric reconstruction of the E-field distribution in the phantom to assess rapid SAR measurements, by means of an ellipsoidal model. The estimation of its parameters is achieved by two ways: using a reduced number of real data points exclusively, and using a combination of real data points and E-field extrapolation with a given expansion model.
Adaptation of the Frequency Dependent Jiles-Atherton Model with B as entry variable
Authors: Benabou Abdelkader , Clénet Stéphane , Piriou Francis
Published: December 2018

In this communication, we propose a dynamical model of hysteresis giving the magnetization M in function of the flux density B. The mathematical development is based on the Jiles approach for frequency dependent hysteresis. The obtained model is simple to carry out and fast. The model is tested through a comparison with experimental results on FeSi steel sheets. Then, the accuracy and the range of application of the model are discussed.
High electromagnetic shielding effectiveness of polyaniline-polyurethane composites in the microwave band
Authors: Wojkiewicz J.L. , Fauveaux S. , Redon N. , Miane J.L.
Published: December 2018

Electromagnetic shielding effectiveness properties of polyaniline – polyurethane nanocomposites at microwave frequencies were studied. The conducting blends showed a very low percolation threshold and their electronic properties can be tuned easily with the mass fraction of polyaniline in the blends or through chemical process. Measurements on composite materials were performed in the 8.2 to 18 GHz band using two sets of waveguides. Shielding effectiveness from 30 to 90 dB were found for mono and three layer samples with a very light weight and good mechanical properties.
Phase unbalance compensation in moving-coil type permanent magnet linear synchronous motor
Authors: Jung Sang-Yong , Choi Ho-Yong , Jung Hyun-Kyo , Hahn Song-Yop
Published: December 2018

The characteristics of the phase unbalance in a moving-coil type Permanent Magnet Linear Synchronous Motor(PMLSM) for travelling the reciprocating trajectory are presented. The phase unbalance caused at end coils, such as deficiency and asymmetry of each phase EMF, is thoroughly investigated. Moreover, a compensating method that can minimize such phase unbalance by adjusting the mechanical air-gap length is proposed, and its effectiveness is verified in a practical application.
A hybrid database approach for simulating signals of Remote Field Eddy Current Testing
Authors: Chen Zhenmao , Takashima Hideyoshi , Miya Kenzo
Published: December 2018

This paper presents a hybrid database approach for simulation of remote field eddy current testing (RFECT) signals due to a local defect. By calculating databases related to the coils with an axisymmetric 2D code and that due to unit sources by a 3 dimensional FEM analysis, 3D simulation of the RFECT signal due to a local defect is successfully realized by using the database approach developed by authors. The validity of the approach is verified by comparing the signal due to a full-length circumferential defect calculated with the proposed hybrid database approach and the axisymmetric 2D code.
The application of soft magnetic composites to the design of tubular linear actuators
Authors: Schofield N. , Canova A. , Gruosso G. , Repetto M. , Ottella M.
Published: December 2018

The paper presents the design synthesis and construction of a tubular linear, permanent magnet actuator for automotive applications. The application of soft magnetic composites in permanent magnet machines is discussed, since conventional lamination techniques are cost prohibitive for the tubular linear topology considered. The linking of analytic and finite element techniques in the design synthesis is presented along with characterisation test data from a prototype actuator constructed to validate the design procedure.
Magnetic force control device of composite laminate of giant magnetostrictive and piezoelectric materials
Authors: Ueno Toshiyuki , Qiu Jinhao , Tani Junji
Published: December 2018

A magnetic force control device with composite laminate of a giant magnetostrictive material (GMM) and a piezoelectric material (PZT) is proposed. This magnetic force control is based on inverse magnetostrictive effect of the GMM, whereby variation of the magnetization in the GMM changed with a applied voltage on PZT is converted to that of magnetic force by the magnetic circuits. Because of the capacitive properties of the PZT, the device requires no electric energy hence generates no heat to maintain constant force. Furthermore compared with conventional electromagnets, the device is simple and easy to assemble. In this paper, the principle of the magnetic force control is presented and the static and dynamic characteristics of the device are examined.
BEM simulation of laser trimmed hybrid IC resistors
Authors: Schimmanz Klaus , Kost Arnulf
Published: December 2018

The capability of hybrid Integrated Circuits (IC) depends essentially on resistor precision. This is nowadays achieved by laser trimming of film resistors. This process can be highly supported by a robust method of computational electromagnetics. The paper shows how the Boundary Element Method(BEM) is used to simulate important quantities of the process.
Locomotive characteristics of swimming mechanism propelled by alternating magnetic field
Authors: Sudo Seiichi , Orikasa Reiko , Honda Takashi
Published: December 2018

This paper is concerned with the micro swimming mechanism propelled by the alternating magnetic field in a water pipe. Locomotive characteristics of the swimming mechanism are investigated for the purpose of the development of micro robots which work in human blood vessels. The swimming mechanism is composed of a small magnet attached to a polyethyleneterephthalate film. The dynamic behaviour of the mechanism is analyzed by a three-dimensional motion analysis system. It was found that the propelling velocity depends on the excitation frequency and dimension of the polyethyleneterephthalate film.
Three-dimensional FDTD modeling of a ground-penetrating experiment
Authors: Bonnet Pierre , Vernet Raphaël
Published: December 2018

This paper deals with a numerical FDTD approach to solve a particular ground-penetrating problem. Classical Yee FDTD formulation is used to simulate layered media on a perfectly electrically conductive plate (PEC). It is shown that an alternative of the step 3-D PML formulated by Sullivan is well adaptated to surround the computational domain. In particular, the PEC can be easily extended to the PML medium without any extra reflection error.
2-D near-field SAR non-destructive testing of rebars in a concrete wall
Authors: Franchois Ann , Lewyllie Peter , Taerwe Luc
Published: December 2018

A microwave non-destructive testing technique to localize metal reinforcement bars in a concrete wall is presented. The technique is based on a two-dimensional near-field Synthetic Aperture Radar imaging algorithm in a monostatic stepped frequency arrangement. The resulting, qualitative, images of the induced sources give a clear indication on the position of the highly conductive rebars, thanks to their strongly reflective properties. The algorithm takes into account the presence of the concrete, the complex permittivity of which is assumed to be known. The technique has been succesfully tested on simulated and experimental data for a number of concrete wall samples with various reinforcement configurations.
Numerical modelling of volumetric defects
Authors: Rubinacci Guglielmo , Tamburrino Antonello , Ventre Salvatore , Villone Fabio
Published: December 2018

We propose an efficient numerical procedure to iteratively compute the perturbation of the magnetic field (in the magnetoquasistationary limit) due to a volumetric defect of arbitrary shape embedded in a conducting domain. The procedure, which is particularly suitable in view of the solution of the inverse problem, is based on an integral formulation of the eddy current problem in terms of the electric vector potential expanded using edge elements.
Residual vibration reduction control after catching a falling steel sphere by a two-link catching flexible robot arm
Authors: Kojima Hiroyuki , Morito Akihiro , Konno Katsuhiro , Kobayashi Toshio
Published: December 2018

This study deals with the residual vibration reduction control after catching a falling steel sphere by a two-link catching flexible robot arm. The two-link catching flexible robot arm consists of a first rigid link, a second flexible link and a cup mounted to catch the falling steel sphere. The flexibility of the second flexible link is effectively utilized to reduce the shock owing to the contact between the falling steel sphere and the cup. Then, the equation of motion of the two-link catching flexible robot arm is obtained, and the cost function for the residual vibration reduction control after catching the falling steel sphere is defined as a function of the parameters of the second joint angular velocity profile. By making the contour map of the cost function, the optimal parameters of the second joint angular velocity profile is obtained. The residual vibration reduction control is implemented by the feedforward control based on the second joint angle trajectory with the optimal parameters. Furthermore, the numerical calculations and the experiments have been carried out, and it is confirmed that the residual vibrations of the second flexible link after catching the falling steel sphere can be extremely reduced.
Novel elastic magnets as actuators core
Authors: Iannotti Vincenzo , Hison Cornelia , Lanotte Luciano , Luponio Carlo , Ausanio Giovanni , Luponio Cesare , D'Agostino Amleto , Germano Roberto
Published: December 2018

An elastic magnet in bar shape, consisting of permanently magnetized Sm _2 Co _7 micro-particles, was produced. The longitudinal strain and/or force amounts given by this novel material under the action of a longitudinal magnetic field are here investigated in order to evaluate the potential applications in very ductile actuator systems.
Loss of information in electromagnetic-mechanical system as the fault indicator
Authors: Skowronek Konrad , Szymkowiak Piotr , Walczak Piotr
Published: December 2018

The evaluation of loss of information in system of magnetic and mechanic forces field coupling was presented in the paper. The calculation of loss of information was introduced as an example as well as the set of simplifying assumptions in the system model. The application of presented analysis was also mentioned.
Influence of external stress along [001] axis on phase diagram of cubic ferromagnet with shape memory effect
Authors: Taskaev S.V. , Buchelnikov V.D. , Vasil'EV A.N. , Takagi T.
Published: December 2018

In this work the stress-temperature phase diagrams of a cubic ferromagnet with positive constant anisotropy and an external elastic stress along [001] axis are investigated.
Modeling of nonlinear material with linear inhomogeneous medium for loss prediction of transformer cores
Authors: Sebestyén Imre , Pavo József , Gyimóthy Szabolcs , Bíró Oszkár
Published: December 2018

A method for the approximate prediction of the power loss of a nonlinear ferromagnetic laminated iron core is presented. The calculation is made in two subsequent steps. In the first step, the approximate magnetization of the material is predicted assuming a bulk nonlinear material with anisotropic electric conductivity. In the second step the nonlinear materials of the ferromagnetic sheets are replaced with linear ones whose permeability is spatially inhomogeneous. The actual permeability distributions are determined based on the nonlinear B-H curve of the material and the magnetic field values obtained from the first calculation. In this paper the applicability of the method is demonstrated through calculations made by FEM studying a benchmark arrangement.
An optimization method for design of PM motor by using Voltage Driven Finite Element Method and genetic algorithm
Authors: Matsutomo Shinya , Noguchi So , Yamashita Hideo , Tanimoto Shigeya
Published: December 2018

Permanent magnet motors have been widely used. In recent years, from the point of view of energy saving, it is required to improve the efficiency of permanent magnet motors by applying an optimal design method. In this paper, we propose an adjusting technique of the supply voltage of permanent magnet motor when carrying out the optimal design by adopting voltage driven finite element method and genetic algorithm. In calculation for the optimal design, it is difficult to keep a desirable balance of the supply voltage and the induced electromotive force. By using the proposed method, the supply voltage is appropriately decided to generate the rated torque. Owing to adopting this adjusting technique, the computation time for the optimal design can be reduced and the solution can escape from local minima because the needless computations can be drastically reduced.
An iterative procedure for accurate design of Helmholtz coils for studying ELF bioelectromagnetic interaction
Authors: Oliveri Maria E. , Coco Salvatore , Gazzo Daniela S.M. , Giuffrida Cinzia , Laudani Antonino
Published: December 2018

An iterative procedure is presented for the accurate design of the Helmholtz coils generating ELF magnetic fields used for the exposure of biological samples of different sizes. In this procedure, starting from an assigned magnetic field profile, local and global inverse problems are iteratively solved in sequence until a target precision in the obtained magnetic field profile is achieved. At this point the coil geometrical parameters and the associated current source intensities are available for the design.
Ni-Mn-Ga Shape Memory Alloys: Modelling of Magneto-Mechanical Behaviour
Authors: Hirsinger Laurent
Published: December 2018

A predictive model of field-induced strain in Ni-Mn-Ga ferromagnetic shape memory alloys is proposed. In this study, magnetocrystalline anisotropy K _1 is introduced to permit magnetisation rotation in each martensitic platelets. The demagnetisation field induced by the shape of platelet microstructure is investigated. As expected, the strain -induced by magnetic field- in a single crystal is mainly given by the mobility of twin boundaries, by the crystal anisotropy of martensite and by the shape anisotropy of platelet microstructure.
Magnetoelastic behavior of ferromagnetic materials using stress dependent Preisach model based on continuum theory
Authors: Suzuki Takaaki , Matsumoto Eiji
Published: December 2018

The magnetic and the mechanical constitutive equations are proposed on the basis of the continuum theory of magnetoelastic materials. The rate type expression is derived from the moving Preisach model by taking into account the stress dependence as the magnetic constitutive equation. From the symmetry of the constitutive equations, it is shown that the stress magnetization effect can be derived from the stress-dependent magnetization and magnetostriction curves. It is experimentally confirmed that the constitutive equations can describe typical magnetoelastic behaviors of a ferromagnetic material such as the magnetization and the magnetostriction curves under the stress and the stress magnetization curve.
Analytical computation of the RMS current stress on the DC-link capacitor in DC-link PWM converter systems powering N-phase rotating field machines in PWM and square wave mode
Authors: Schulte Stephan , Schlensok Christoph , Henneberger Gerhard
Published: December 2018

This paper describes an easy to handle analytical method for the computation of the rms current stress on the DC-link capacitor of PWM converters. Both the PWM and the square wave mode (SWM) operation powering rotating field machines e.g. induction- or synchronous machines are considered. The rms current stress on the DC-link capacitor mainly affects its working temperature. Therefore it is a significant factor for the estimation of its duty cycle. On the one hand the value of the DC-link capacitor current is determined by the amplitude and the phase angle of the inverter output phase current, deriving from the actual load. On the other hand it is influenced by the modulation depth and the phase number of the arrangement as well. The results achieved with the simple analytical model match very well with results of complex simulation models. The equivalent computing time compared to common simulation tools at reasonable time steps is reduced by more than a factor of thousand.
FEM analysis of thin cracks in metallic plates
Authors: Cardelli Ermanno , Faba Antonio
Published: December 2018

In this work we will present some remarks about the numerical analysis of non destructive testing for thin cracks detection in metallic plates. In particular this paper show the solution of a coupled electrical circuit – magnetic field problem using a finite element approximation scheme. This procedure is used in order to increase the sensibility of detector system. A comparison between experimental and numerical results is also presented.
Development of a 3D electromagnetic model for eddy current tubing inspection: Application to the simulation of probe eccentricity
Authors: Prémel Denis , Pichenot Grégoire , Sollier Thierry
Published: December 2018

A theoretical and numerical model is developed for the computation of Eddy Current (EC) signals provided by a differential type probe used for tubing inspection. The main application of interest is to make simulated experiments for studying the perturbations affecting the EC signal such as the variations of the eccentricity and the probe wobble. 3D flaws are introduced by a variation in the local distribution of the conductivity. The forward problem is handled by using a dyadic Green's function approach. Typical impedance plane trajectories obtained with a differential probe are given.
Improved auto-tuning niching genetic algorithm combined with grouping concept for inverse problem
Authors: Kim Jae-Kwang , Jung Sang-Yong , Jung Hyun-Kyo , Hahn Song-Yop , Cho Dong-Hyeok , Chung Tae-Kyung
Published: December 2018

Niching genetic algorithm has been applied to the optimisation of multimodal function. In this paper, improved niching genetic algorithm using auto-tuning concept and grouping factor is proposed. Population size and niche radii can be determined automatically and similar solutions unified by grouping factor. This method can be applied to the complex function such as inverse problem.
Rating and valuation of human haptic sensation
Authors: Tanaka Mami , Numazawa Yu
Published: December 2018

This paper is a study on development of a sensor system for measurement and valuation of human touch feeling. The objects measured are underwear, knitwear, sample underwear and polo shirts with total 26 sheets. First, the tactile feelings of several fabrics were/touch valued by using the paired comparison semantic differential method handed onto 5 subjects. Next, a soft tactile sensor made of a PVDF (Polyvinylidene Fluoride) file patch and rubber layers is assembled and slid over the same sample fabrics to collect the surface tactile information. The features on the collected data are then extracted by calculating the variance of output signal and the intensity of power spectrum density on medium frequency range. Comparison of the results shows that the PVDF sensor well describes the human touch feeling.
Derivation of simplified hybrid model and speed control for traveling wave ultrasonic motor
Authors: Al-Sabbah Shebel Asad , Mendes Eduardo , Bernard Yves
Published: December 2018

A methodology to design an attractive robust controller for traveling wave ultrasonic motor (TWUSM) is followed on this work. This methodology takes into account several non-linear effects, such as the friction effect, those occur in the ultrasonic motor mechanism. To achieve that, our first objective is to derive a simplified hybrid model (PSHM) that catch the main behavior of the motor during normal operation, including the stator/rotor contact interface, and that can be used to design speed and position control laws. Finally, based on this model, a Fuzzy logic controller (FLC) is designed in order to achieve robustness against several uncertainties (i.e. load torque variations, motor heating, parameters uncertainties…), and a popular Shinsei USR60 is used experimentally to validate the proposed methodology.
Fine particles behavior analysis for magnetic separation process
Authors: Mehasni Rabia , Latreche Medelhadi , Feliachi Mouloud
Published: December 2018

A new form of magnetic separation in flowing liquids using magnetic field open gradient is used. Several improvements concerning the capture efficiency are given by optimizing both the applied magnetic field and liquid flow. Experiments were performed to estimate the reliability of the proposed device and to determine the use limits of this form of magnetic separation.
Hydrogen attack characterisation by magnetic measurements
Authors: Manna Giustino , Pirfo Soraia , Debarberis Luigi , Castello Paolo , Hurst Roger
Published: December 2018

The security of energy supply and sustainable and safe energy production are two main research topics of the Institute for Energy of the Joint Research Center. To lower the risks, for people and the environment, involved in fuel production and petroleum refining, studies and tests are carried out at the Institute on the degradation of low-alloy ferritic steel under petrorefinery service simulated conditions. In this frame, and for industrial purposes, a reliable assessment of damage level by means of non-destructive techniques is a key factor. This paper presents the results of magnetic measurements, in particular the Barkhausen method, on ferritic steels previously exposed to service simulated conditions, and in air. The results show a good potential for this magnetic method to detect changes due to the exposure of the steels to the different environments and, in particular, the degree of damage due to hydrogen attack. A correlation between the results of magnetic and hardness measurements is currently under investigation, but not yet presented in this outline.
Hybrid method based on the inverse wavelet transform and hopfield network to reconstruct the transformed data
Authors: Nouicer Abdelmadjid , Latreche M.E.H. , Feliachi Mouloud
Published: December 2018

Conventional reconstruction of the compressed data based on the inverse wavelet transform (IWT) does not give good results (too much loss of information) because of the neglected detail part especially for the high levels decomposition. To deal with this problem, a new approach for the reconstruction of the compressed data, based on the inverse wavelet transform and the Hopfield neural networks is presented in this paper.
Behavior of a chiral material in terms of a guided wave propagation
Authors: Oussaid Rachid , Haraoubia Brahim
Published: December 2018

In this approach, we study the behavior of a chiral material in terms of the propagation of guided wave. In this study, we are particularly interested by the field distribution in a coplanar structure based on the involved chiral material. This chiral material is supposed to be homogeneous, isotropic and lossless. In this paper, the characteristics of wave guided propagation in chiral medium have been analyzed. Using Maxwell's curl equations for source-free regions together with the set of constitutive relations, the dispersion relation of propagating and evanescent modes for this chirowaveguide have been obtained and analyzed. We show that the existent modes regardless to their nature: propagative or evanescent; are both bifurcated modes. In this paper, the formalism used to describe the chirowaveguide represent a new approach, which is based on calculation of longitudinal and transverse operators. The derivation proposed here is new and different of that used in [4]. The results obtained, using a different method based on a new mathematical approach, are substantially the same as that one published in the literature.
Study in the post-assembly magnetization method of permanent magnet motors
Authors: Lee Chul Kyu , Kwon Byung Il
Published: December 2018

This paper studies two post-assembly magnetization methods for permanent magnet motors. One is stator winding magnetization method (SWMM) for ferrite magnets. The other is magnetizing fixture magnetization method (MFMM) for magnets having large coercive force like NdFeB magnets. They are applied to three types of permanent magnet motors: SPM type of BLDC motor, LSPM type motor and IPM type of BLDC motor. In case of line start permanent magnet motors(LSPM), the eddy current produced in the rotor bars seriously disturbs magnetizing. Therefore, the magnetization processes are analyzed by using the time stepping finite element method. As a result, it is clarified that the SWMM is proper for the SPM type motor using ferrite magnets and the MFMM is proper for the LSPM and IPM type motors using NdFeB magnets.
Finite element analysis of shunt reactors with auxiliary windings
Authors: Cui Xiang , Li Huiqi , Li Lin , Liu Jianxin
Published: December 2018

It is necessary to install three single-phase shunt reactors in the middle of a 500 kV transmission lines with long distance for compensation of capacitive reactive power of the lines. However, unlike traditional shunt reactors installed in substation, except the high voltage reactor windings, as a kind of special single-phase shunt reactor, there are the low voltage auxiliary windings to be placed in its core or yokes in order to supply few lower-voltage loads for some low voltage devices. In this paper, based on the finite element analysis of three-dimensional nonlinear magnetic field, the self and mutual inductances of the shunt reactor with auxiliary windings are calculated. Further, the Volt-Ampere curves of the shunt reactor with and without loads are also numerically analyzed. The numerical results are verified by measurements of a model and two prototype shunt reactors.
Crossover-controlled genetic algorithm and its application to inverse problem in SF_{6} interrupter
Authors: Wang Youhua , Chen Tanggong , Yang Xiaoguang , Yan Weili , Sommer Egon
Published: December 2018

From the application of genetic algorithm (GA) to the optimal design of some electromagnetic devices, it is found that its convergence speed is directly affected by the similarity of crossover codes. Based on the analysis for crossover operation a crossover-controlled genetic algorithm (CCGA) is presented. For increasing the interrupting capability at no load current, a permanent magnetic field is drawn into the arc-rotated interrupter of sulfur hexafluoride circuit breaker. Under the condition of same angular frequency at any point on arc, the desirable flux density is determined. On the basis of finite element analysis the optimal magnetic field distribution is obtained by applying CCGA. As a result 18.6 percent of CPU time taken by GA is saved and the interrupting performances at no load and short circuit currents are improved.
Kinetics and relaxation processes in Ni-Mn-Ga alloys under an external stress and a magnetic field
Authors: Bosko S.I. , Buchelnikov V.D. , Taskaev S.V. , Takagi T. , Vasiliev A.N.
Published: December 2018

The kinetics of magnetic and structural domains and relaxation of magnetization and strain under an external stress and a magnetic field in ferromagnetic Ni-Mn-Ga alloys close to a structural phase transition on the basis of time-depending Ginzburg-Landau equation with a thermal noise were theoretically investigated. The influence of an external magnetic field on the kinetics of structural domains was established to have the same influence as the stress has but not so great. The evolution of structural domain pictures was obtained. One type of structural domains was established to prevail in an alloy under an external stress or a magnetic field with time. The time dependencies of magnetization and strain were calculated.
An effective application of Schwarz-Christoffel transformations to the shape design of permanent-magnet motors
Authors: Costamagna Eugenio , Di Barba Paolo , Savini Antonio
Published: December 2018

Performance analysis and optimal design procedures are presented and discussed for a class of small permanent-magnet motors, with reference to a six-pole device with various tooth geometries. Numerical procedures based on robust algorithms for Schwarz-Christoffel transformations are used to obtain suitable 2D models of the device and to perform its shape optimization. The latter is cast as an inverse-transformation problem considering suitable geometrical features. The paper improves the analysis methodology already developed by the authors and presents a new approach to optimal design leading to a fast computation.
An interface wave in piezoelectromagnetic materials
Authors: Yang J.S. , Zhou H.G.
Published: December 2018

It is shown that the propagation of an interface wave is possible between two ceramic piezoelectric half-spaces as governed by the three-dimensional equations of piezoelectromagnetism with full electromagnetic coupling.
Discrete wavelets analysis of the magnetic vector field
Authors: Matsuyama Sawa
Published: December 2018

A discrete wavelets transform is applied for compressing the image data and extracting the major characteristics from magnetic vector field data which are variable in space and time. Though it always requires a number of target data composed of a power of 2, we propose here a novel approach based on Fourier transform to overcome this difficulty without loosing any original data information. A key idea is simple but effective because it exactly keeps all of the frequency components comprising the target data. We have tried to compress the magnetic vector field data by the multiresolution analysis using three dimensional discrete wavelets transform. The analysis indicates a high recovery ratio between the raw data and compressed data when the number of the data decreases even one sixty-fourth of number of the original data. As a result, several examples demonstrate the usefulness of our new method to work out the visual communication tools.
Magnetic properties of ferromagnetic shape memory alloys Ni_{2-x}Cu_{x}MnGa
Authors: Kanomata Takeshi , Nozawa Takuji , Kikuchi Daisuke , Nishihara Hironori , Koyama Keiichi , Watanabe Kazuo
Published: December 2018

Magnetic measurements on Ni _{2-x} Cu _{x} MnGa with 0 ≦ x≦ 0.8 are made in the temperature range between 4.2 K and 440 K. A phase diagram of Ni _{2-x} Cu _{x} MnGa is determined from the results of the temperature dependence of the initial permeability. The Curie temperature T_{C} increases with the Cu concentration x. The martensitic and reverse martensitic transformation temperatures decrease abruptly with x. It is deduced that the substitution for Ni by Cu in Ni _{2} MnGa promotes to localize the magnetic moment of Mn atom.
Coupled mechanical and conductivity measurements: Damage detection
Authors: Yuse Kaori , Dalmas Florent , Flandin Lionel , Cavaillé Jean-Yves
Published: December 2018

This paper reports in situ measurements of electrical resistivity during mechanical solicitation of insulator-conductor composite. Electrical and mechanical behaviors will be discussed on 3 examples namely (i) unidirectional carbon fiber reinforced polymers (CFRP), (ii) stick-like whiskers reinforced soft thermoplastics and (iii) carbon nanotubes reinforced soft thermoplastics.

Resistivity measurements are described as a useful tool to monitor the damage of these composites. In the case of composite materials consisting in reinforced insulated matrix by electrically conducting fibers or fillers, resistivity (or conductivity) measurements show classically several features such as strong anisotropy in long fiber composites or the existence of continuous direct current (DC) conducting pathway for short fiber or particulate composites. Moreover, and this is the topic discussed here, in terms of mechanical stress/strain properties, the fibers or fillers conducting network may exhibit resistivity changes due to fiber ruptures, delamination, filler-filler debonding within filler network, etc.
Non-linear and hysteretic processing of piezoelement: Application to vibration control, wave control and energy harvesting
Authors: Guyomar Daniel , Richard Claude
Published: December 2018

The proposed processing is applied on the voltage output, image of the vibrating displacement u(t), of a piezoelement (patch) bonded on a vibrating structure. It is based on a non-linear processing which, in the simplest version, short circuit the voltage output for a very brief time duration when the voltage reaches a maximum or a minimum. Right after the switching, the voltage is relaxed and becomes again an image of u(t) at the patch location. Repeating the switching for each max and min of the voltage signal results in a transformed voltage waveform that is magnified and time shifted with respect to the non switched waveform. As a matter of fact, it can be shown that the processed voltage can be spilt in two waveforms: one, V _{1} (t), being the exact image of the displacement u(t) while the second, V _{2} (t), is related to the sign function of the vibration speed. Consequently V _{2} (t) appears to act as a mechanical dry friction force which leads to efficient and frequency independent removal of the energy stored in the piezoelement. Taking advantage of this particular energy removal, several topics (vibration damping, wave control, energy harvesting) have been experimentaly addressed.

For the vibration damping, the experimental results obtained with the proposed semi-active approach are close to the active performances. Acoustic wave reflection reductions of 17∼dB and 34∼dB have been respectively obtained for air and water media and the scavenged energy using the switch process at fixed displacement is almost ten times higher than the harvested energy using a standard processing.
Magnetic mosaics in crystalline tiles: The novel concept of polymagnets (invited)
Authors: Sullivan Matthew R. , Pirotta Steven J. , Chernenko V.A. , Wu G.H. , Balasubramanium G. , Hua Susan Z. , Chopra Harsh Deep
Published: December 2018

This article presents our recent results on magnetic shape memory alloys (SMAs) and reviews some of our relevant past work. By treating the martensite structure as an assembly of microscopic crystalline tiles (twins), the observed micromagnetic structure or 'magnetic mosaic' in these alloys can be explained in terms of a spatially varying axis of the magnetocrystalline anisotropy and magnetostatic interactions across the tiles. A systematic investigation of ferroelastic structural domains of increasing structural complexity leads to a novel concept of 'polymagnets'. Similar to the idea of hierarchical ferroelastic polydomains, polymagnets are hierarchical micromagnetic structures, and parallels the complexity of the underlying ferroelastic polydomains. Preliminary results on the dynamics of the transformation pathways reveal a strong correlation between the underlying microstructure and achievable strain. In addition, reversible shape memory effect has been observed in sputter-deposited Ni-Mn-Ga thin films, and Co-Ni films with controlled composition have been successfully made by electrodeposition.
A Two-dimensional analysis of surface acoustic waves in finite solids with the consideration of electrodes
Authors: Wang Ji , Lin Jingbo , Wan Yongping , Zhong Zheng
Published: December 2018

The analysis of surface acoustic wave propagation in finite elastic solids is of essential importance in the study of the propagation nature and practical applications, and tremendous efforts have been made lately in employing both analytical and numerical methods for accurate solutions of the phase velocity and displacements. To overcome current difficulties in the physical model and computational intensity, a two-dimensional theory similar to Mindlin and Lee plate theories has been established for the surface acoustic wave propagating in finite elastic solids. A systematic simplification of the three-dimensional equations resulted in a two-dimensional theory with accuracy and potential to solve surface acoustic wave problems in solids in a more efficient manner. For practical applications, the presence of a thin film over the substrate is studied with the two-dimensional theory with systematic modification, and straight-crested solutions with different film thickness are obtained.
TE Plane wave scattering by a lossy dielectric loaded semi-elliptic channel in a ground plane
Authors: Hamid A.-K. , Bettayeb M.
Published: December 2018

Analytic solution to the problem of scattering of a TE polarized plane electromagnetic wave by a lossy dielectric loaded semi-elliptic channel is investigated. The incident, scattered and transmitted fields in every region are expressed in terms of complex Mathieu functions. Applying the boundary conditions at metal surface and dielectric interface along with the partial orthogonality properties of angular Mathieu functions, the unknown scattered and transmitted field coefficients are obtained and written in matrix form. The presented numerical results show that the semi-circular channel has strong resonances compared with the semi-elliptic channel and the presence of a lossy dielectric material reduces the magnitude of the backscattered field.
Calibration of magnetic field coil standards by means of field profile measurement
Authors: Weyand Kurt , Ketzler Rainer , Kitschke Manfred
Published: December 2018

In order to calibrate field coil standards a new setup has been developed by which the field profile of field coils is recorded. From the profile the centre field strength can be related to the SI units of electrical current and length. The main components of the apparatus are a modified, commercially available fluxgate magnetometer, an optical length measuring device, and a motor driven positioning system which moves the fluxgate sensor along the axis of the coil under test. Depending on size and type of the coil a relative uncertainty of some parts in 10 ^{-5} is achievable. Recording the flux profile provides additional information about the device under test, even if its centre field value has been determined by means of Nuclear Magnetic Resonance using protons in pure water, which must be regarded at present as the most accurate method for magnetic field calibration.
Composition gradients surrounding Ni_4Ti_3 precipitates in a NiTi alloy studied by EELS, EFTEM and EDX
Authors: Yang Zhiqing , Schryvers Dominique
Published: December 2018

Composition gradients surrounding Ni _4 Ti _3 precipitates in a Ni _{51} Ti _{49} B2 austenite matrix are investigated by a combination of analytical TEM techniques, including electron energy loss spectroscopy (EELS), energy filtered TEM (EFTEM) and energy dispersive X-ray spectroscopy (EDX). A Ni depleted zone in the surrounding matrix was detected. The size and concentration change of the depletion zone compensate very well for the excess Ni in the precipitate. Since different precipitates are often formed in nanoscale proximity, depletion zones from different precipitates can enforce one another in certain regions. A new quantification technique of EELS confirmed the 4:3 atomic ratio between Ni and Ti for the precipitate. No Ni-rich zone in the vicinity of grain boundaries was detected in the solution-treated samples.
Ferromagnetic shape memory microscanner system for automotive applications
Authors: Brugger D. , Kohl M. , Hollenbach U. , Kapp A. , Stiller C.
Published: December 2018

A microscanner system for optical sensing of angle and distance is presented, which is controlled by a ferromagnetic shape memory (FSMA) microactuator. The main features of the FSMA microactuator are a large scanning angle up to 60 deg and a large bandwidth of frequencies given by a broad off-resonance regime below the thermal cut-off frequency at about 120 Hz and the resonance regime between 160 and 220 Hz. The small size and low mass of the FSMA microactuator allows the design of a very compact and robust scanner system, which enables new portable and mobile applications. In this paper, the sensing of objects in road traffic is pursued as an application in the automotive field, which requires small moving masses being insensitive to vibrations and shock. The main components of the microscanner system are the FSMA microactuator, a pulsed laser diode, an integrated angle sensor, an avalanche diode and a time-of-flight measurement setup for distance acquisition. The maximum scanning range of the first prototype is about 30 m for cooperative (reflecting) objects. The angular resolution is about 0.5°.
Coupled simulation of the thermo-magneto-mechanical properties of a Ni-Mn-Ga actuator
Authors: Krevet B. , Kohl M. , Brugger D.
Published: December 2018

A combination of different finite element (FEM) programs is used to simulate the coupled thermo-magneto-mechanical properties of a Ni-Mn-Ga double-beam cantilever. First, simulations of the static and dynamic temperature distributions are presented for different electrical heating conditions taking into account the effects of martensitic phase transformation. The results are used for a self-consistent mechanical deflection analysis of the actuator in the inhomogeneous magnetic field of a permanent magnet. The influence of the shape recovery, ferromagnetic and Lorentz force on the actuator performance are discussed.
Effect of quenching on martensitic transformation course in non-stoichiometric NiMnGa alloy
Authors: Goryczka T. , Gigla M. , Morawiec H.
Published: December 2018

Polycrystalline 51.2at%N 27.6at%Mn and 21,1at% Ga bulk samples were quenched after annealing at 700°C, 800°C and 900°C for one hour. The parent phase, in sample quenched from 900°C, reveals the B2 structure whereas in the sample quenched from 700°C – the Heusler's structure L2 _{1} . The ordering transformation was confirmed by the results obtained from high temperature DSC measurement. On a heating curve broad thermal peak appeared in the range between 700°C and 800°C. Increasing of the quenching temperature results in lowering temperatures of the martensitic transformation and simultaneously broadens its thermal range. Independently on the quenching temperature and the ordering of the parent phase the martensite shows the 10M structure type. However, in electron diffraction pattern, taken for the sample quenched from 800°C, additional effects of the diffusion electron scattering have been observed as a result of a short-range ordering caused by the Ni exceeding atoms.
DMA characterization of a Ni50.5at%Ti shape memory alloys
Authors: Besseghini Stefano , Villa Elena , Portman Jenni
Published: December 2018

It is well-known that the special properties of NiTi shape memory alloys strongly depend on their microstructure and their thermomechanical state. DSC and mechanical tests (stress-strain vs temperature) do provide extensive information on the transformation temperatures and on the pseudoelastic effect: a Dynamic Mechanical Analyzer (DMA) is further able to investigate even more transition effects, because it makes it possible to study the transition temperatures in both stressed and unstressed conditions over a wide temperature range (−150°C; 600°C). Moreover, through dynamic experiments one can to analyse the linear mechanical response and the viscoelastic properties in different ranges of strains and frequency. In this work we measure the response of NiTi in the austenitic and rhombohedral phase. We test the material both in isothermal condition over a frequency range and at a constant frequency over a temperature ramp. The NiTi samples used were Ni50.5at%Ti wires, 80 μm in diameter, thermally treated at 450°C for 1.8 Ks.
Modelling of rearrangement yield surface under biaxial magnetic field in Ni-Mn-Ga shape memory alloys
Authors: Creton Nicolas , Hirsinger Laurent
Published: December 2018

A predictive model of field-induced strain in Ni-Mn-Ga ferromagnetic shape memory alloys is proposed. The action of both biaxial magnetic field and mechanical stress on the martensitic rearrangement in a Ni-Mn-Ga single crystal are modelled. Yield surfaces of starting rearrangement are simulated. They show how applied mechanical stress helps or opposes to the applied magnetic field to make the rearrangement easier or harder. The results are fully compatible with the experiments of Müllner et al. [8] describing the action of a rotating magnetic field.
High field X-ray diffraction studies on magnetic refrigerants
Authors: Koyama Keiichi , Ishikawa Fumihiro , Watanabe Kazuo
Published: December 2018

In this paper, we review our recent results on magnetic refrigerants MnAs _{1-x} Sb _{x} and MnFeAs _{0.5} P _{0.5} by powder X-ray diffraction measurements in fields up to 5 T and in the temperature range from 8 to 320 K. MnAs shows a first-ordered structural transition with the volume expansion of 2.1% accompanied by a metamagnetic transition, but MnAs _{0.9} Sb _{0.1} exhibits an isostructural transition with the volume expansion of 1.1%. The cell volume of MnFeAs _{0.5} P _{0.5} slightly (−0.4%) and continuously decreases with increasing a magnetic field through the metamagnetic transition.
Measurement and valuation of tactile warmth using a PVDF sensor
Authors: Tanaka Yoshihiro , Tanaka Mami , Chonan Seiji
Published: December 2018

The purpose of this study is the development of a sensor system using the pyroelectric effect of a PVDF (Polyvinylidene Fluoride) film for measuring tactile warmth. Tactile warmth on fabrics is compared with PVDF sensor output. At first, warmth on each sample is collected through the questionnaire based on the paired comparison semantic differential method. Furthermore, human motion for the evaluation of tactile warmth and contact pressure applied to an object are investigated. Next, a sensor using a PVDF film as the sensory receptor is fabricated. The surface of the sensor is heated through temperature control. Then, the sensor is moved and contacted with a measurement object in order to collect pyroelectric output voltage. For the means of driving the sensor system, trajectory control of the contact pressure is introduced on the basis of the results of the examination of human motion. Finally, the measurement using the sensor system is carried out on the samples. Comparison with the results shows that the PVDF sensor system is applicable for the evaluation of tactile warmth.
Influence of hydrogenation on magnetic phase transition in Er_{2}Fe_{14}B: Fundamentals and potentialities
Authors: Tereshina E.A.
Published: December 2018

In this work the results of the systematic study of the hydrogen effect on Curie temperature (T _{C} ) and spin-reorientation temperature (T _{SR} ) in Er _{2} Fe _{14} B were reported. It was established that the hydrogenation leads to an increase of T _{ C} and T _{SR} . The magnetization of Er _{2} Fe _{14} BH _{x} (0⩽ x ⩽ 2.5) compounds measured in the magnetic field of 0.05 T applied along the c-axis has been shown to rise substantially with temperature growth near the magnetic phase transition region. The longitudinal magnetostriction of Er _{2} Fe _{14} BH _{x} also increases at the spin-reorientation temperature. Er _{2} Fe _{14} B compound and its hydrides were potential candidates for application as working elements of various thermomagnetic sensors.