bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the load reduction for hydro-generator bearing by hybrid magnetic levitation
Authors: Ma Hongzhong , Wang Qingyan , Ju Ping
Published: December 2018

To solve the problem of heat and friction existing in weight bearing of the hydraulic generator, a new type of magnetic levitation devices is proposed. The devices consist of electromagnetic and permanent magnetic levitation, which share together most of the hydraulic generator rotor weight to reduce axial load on thrust bearing. The permanent magnetic levitation is performed by new repulsive ring Halbach arrays. The new Halbach arrays are analyzed by using magnetic potential equations and superposition principle, and the magnetic flux density formulas are obtained. The formula results are verified by FEM. By further study of 3D model simulation analysis, it is confirmed that the new repulsive ring Halbach arrays can reach the design goal on actual working conditions.
Modeling of piezoelectric energy harvester with multi-mode dynamic magnifier with matrix representation
Authors: Vasic Dejan , Costa François
Published: December 2018

A piezoelectric energy harvester with a multi-mode dynamic magnifier is proposed and modeled in this paper. The dynamic magnifier consists of an intermediate beam with a tip mass, which is placed between the fixed end of the energy harvesting beam and the vibrating base structure. The piezoelectric element is bounded to the harvesting beam to harvest the vibration energy. With proper choice of the design parameters of the magnifier, the harvested electric power can be significantly increased due to the bandwidth extension, which enables energy harvesting from the ambient vibration in a larger range of frequency. Theoretical analysis is carried out with 4 × 4 chain matrix representation. Numerical examples are presented to illustrate the merits of the dynamic magnifier in comparison with the conventional piezoelectric energy harvesters. The results show that electric power produced by the harvesting beam is amplified for efficient energy harvesting over a broader frequency range.
Broadband and compact double negative composite metamaterials with low losses
Authors: Amiri N. , Forooraghi K. , Atlasbaf Z.
Published: December 2018

In this paper two novel left-handed composite metamaterials consisting of SRRs, wire and single sided S-shaped resonators are proposed. One of them is a reduced-size resonator which uses superposition hypothesis to achieve adjacent resonances for a much broader negative refraction passband. The other is a modified planar structure with improved electromagnetic coupling and reduced electrical size. Both structures are truly matched to free space in almost whole left-handed frequency band. It will be shown that these metamaterials are robust to the fabrication errors of misalignment printing on both sides of the substrate. The superior performance of these structures are investigated numerically and experimentally and compared with the other split ring resonators. Wedge shape simulation and experimental results confirm the left-handed passband.
Interaction magnetic force calculation of radial passive magnetic bearing using magnetization charges and discretization technique
Authors: Vučković Ana N. , Raičević Nebojša B. , Ilić Saša S. , Aleksić Slavoljub R.
Published: December 2018

Calculation of the interaction magnetic force between two ring permanent magnets with radial magnetization is presented in the paper. Such configuration corresponds to a radial passive magnetic bearing. The simple and fast analytical approach is used for this calculation based on magnetization charges and discretization technique. The results for interaction magnetic force obtained using proposed approach are compared with finite element method(FEM). The advantage of presented approach is its simplicity and time efficiency since only complete elliptic integrals of the second kind are used and other additional integrations are avoided in this calculation.
Optimal shape design of electrostatic microactuators: A multiobjective formulation
Authors: Chereches R. , Di Barba P. , Topa V. , Purcar M. , Wiak S.
Published: December 2018

A procedure of automated optimal design of a class of micro-electromechanical devices is proposed in terms of a multiobjective optimization formulation. A comb-drive electrostatic accelerometer is considered as the case study. By optimizing the shape design of the device, it is desired to extend the actuation range of the comb drive in steady-state conditions, leading to greater gap distances between the electrodes. The design variables control the geometry of fixed and movable electrodes, in terms of width and height. The twofold goal of maximizing the drive force considered as the main criterion, while minimizing the levitation force considered as a parasitic effect, makes it possible to implement a Pareto optimality approach.
Optmization of coils for field map synthesis
Authors: Chiariello Andrea Gaetano , Formisano Alessandro , Martone Raffaele
Published: December 2018

The paper proposes an optimization procedure suited to design the shape and the current feed of active coils. A suitable spline-based basis is used for the coil geometry modeling, based on a rather limited number of optimization parameters. In order to simplify the constraints treatment, a set of knot points are introduced, linked with the design degrees of freedom.
Analysis and realization of improving the patch antenna gain based on metamaterials
Authors: Yang Xiaoqing , Sun Di , Zuo Teng , Chen Xu , Huang Kama
Published: December 2018

To improve the gain of microstrip antenna, it can be realized by artificially introducing metamaterials into microstrip antenna. This paper introduces four kinds of metamaterial structures, such as dendritic-type, cross-type, s-type and h-type. All can improve the antenna performance in varying degrees. Based on the analysis and comparison of the simulated results, we found that the dendritic-type metamaterial microstrip antenna has the most remarkable influence on increasing of the antenna gain with the bandwidth basically unchanged. At last, the simulated results were compared with the measured results. The good agreements can be observed.
Circular cylinder with D'B, DB' and D'B' boundary conditions placed in chiral and chiral nihility media
Authors: Khalid Muhammad , Syed Aqeel A. , Naqvi Qaisar A.
Published: December 2018

Electromagnetic scattering by a circular cylinder, characterized by D'B, DB' and D'B' boundary conditions, is studied. These boundary conditions deal with the normal components of electromagnetic flux densities and their normal derivatives. Electromagnetic behavior of a circular cylinder satisfying a pair of conditions among these different sets of boundary conditions is first investigated in free space. The response of cylinder placed in free space is discussed for both TM- and TE-polarized incident fields, with respect to axis of the cylinder. The results are then extended by placing these boundaries in chiral and chiral nihility mediums. Numerical results for these boundaries placed in free space, chiral and chiral nihility mediums are given and compared with those of DB cylinder placed in similar media.
Virtual metal model for fast computation of shielding effectiveness of blended electromagnetic interference shielding fabric
Authors: Wang Xiuchen , Liu Zhe , Zhou Zhong
Published: December 2018

Blended electromagnetic interference (EMI) shielding fabric has an important application in the EMI shielding fields, but its shielding effectiveness (SE) computation remained unsolved. This study proposes a fast computation method which builds a virtual metal model according to fabric structure parameters to calculate the SE of the EMI shielding fabric. The above analysis involves the calculation of metal fiber content per unit volume of the EMI shielding fabric according to the structure of the fabric, followed by construction of a virtual metal model and computation of its thickness. Then a relation between the SE of the EMI shielding fabric and the SE of the virtual metal model is explored. A conversion coefficient of the SE computation of plain, twill and satin weave fabric is determined by experiments. A fast computation of the SE based on the virtual metal model is built. After a number of experiments, results show that the relative error is low and the computation is fast and is satisfied for the normal blended EMI shielding fabrics.
Coupling effects of a novel integrated electro-hydraulic energy conversion unit
Authors: Wang Tao , Wang Qingfeng
Published: December 2018

Electro-hydraulic power units are key components of hybrid driven mobile machines such as forklifts and excavators. To satisfy the requirement of limited installation space, this paper proposes a compact and reversible electro-hydraulic energy conversion unit which is the integration of an axial piston hydraulic pump/motor and an electrical machine excited by a segmented Halbach permanent magnet array. The magnets are fixed on the surface of a barrel so that the hydraulic rotor and the electrical rotor are integrated together. Analytical and numerical methods are used to investigate the coupling issues including the common rotor's effect on flux density distribution, combined torque ripple, flow and energy losses in the oil gap, and some design criteria are presented to provide further development with references.
Parametric design of mechanical dither with bimorph piezoelectric actuator for ring laser gyroscope
Authors: Yu Xudong , Long Xingwu
Published: December 2018

This paper presents a mathematical model and a finite element model to investigate the model parameters of mechanical dither in a ring laser gyroscope in which the bimorph piezoelectric actuator are employed as driving mechanisms to avoid the problem of so-called lock-in effects. The validity and efficiency of the mathematical model and finite element model are conformed by comparing with the sinusoidal experimental results, and the errors are 3.14% and 1.79% respectively. Moreover, the parametric design for the geometric dimensions of mechanical dither and the bimorph piezoelectric actuators is easily achieved through finite element model. It is shown that careful selection of the structural parameters allows the resonant frequency to be suitable. These results are important for the mechanical dither design and improvement of high accuracy ring laser gyroscopes and inertial navigation system.
Effects of multiple factors on the stress of the electro-hydraulic directional valve used on the hydraulic roof supports
Authors: Liao Yaoyao , Lian Zisheng , Long Risheng , Yuan Hongbing
Published: December 2018

The large flow electro-hydraulic directional valves are the key operating components for automation of the hydraulic roof supports in the coal mine. Cracking is a common failure mode of the valve. Effects of the buffer damp diameter, the valve type and the static pressure on the stress of the valve were researched. The valve dynamic behavior was investigated by AMESim. The transient collision stresses of the inlet valve sleeve of the main control valve under different buffer damp diameters and different valve types were investigated by ANSYS/LS-DYNA. The static stress analysis was conducted in ANSYS too. Results show that the valve failure is due to the fatigue of the inlet valve sleeve when suffered from the collision stress wave in the valve opening process, rather than the lack of component strength. The buffer damp diameter, the key parameter of the valve, has a significant effect on the collision stress of the inlet valve sleeve. The integrated type valve has a better stress state compared to the separated type valve. This paper provides an effective method to solve the fracture problems of hydraulic directional valves. It is also significant for the design and optimization of hydraulic components.
Permanent magnet synchronous motor controlled V-belt continuously variable transmission driven electric scooter using hybrid modified recurrent Legendre NN control system
Authors: Lin Chih-Hong
Published: December 2018

Due to V-belt continuously variable transmission (CVT) driven electric scooter with unknown nonlinear and time-vary characteristics, an accurately dynamic modeling of V-belt CVT driven electric scooter is the time-consuming procedure for the linear controller design. A hybrid modified recurrent Legendre neural network (NN) control system is proposed to control the V-belt CVT driven electric scooter under the occurrence of nonlinear load disturbances with parametric variations in order to acquire good control performance. Firstly, system structure of the V-belt CVT driven electric scooter by using a permanent magnet synchronous motor (PMSM) servo drive system is proposed in this study. Secondly, the hybrid modified recurrent Legendre NN control system, which consists of an inspector control, a modified recurrent Legendre NN control with adaptive law and a recouped control with estimated law, is proposed to control the V-belt CVT driven electric scooter by using PMSM servo drive. Moreover, the on-line parameters tuning methodology of the modified recurrent Legendre NN is derived according to Lyapunov stability theorem and gradient descent method. Furthermore, two optimal learning rates of the parameters in the modified recurrent Legendre NN are developed to speedup convergence. Finally, to show the effectiveness of the proposed control scheme, comparative studies are demonstrated by simulated and experimental results.
Detection of air-gap eccentricity in induction machines using multi-position magnetic field measurement approach
Authors: Wang Hanfeng , Lv Qiang , Fang Yong , He Yigang , Bao Xiaohua
Published: December 2018

This paper presents a multi-position magnetic field measurement approach to detect air-gap eccentricity in induction machines, including static, dynamic and mixed eccentricity. Using this method, the position of minimum air gap of static eccentricity also can be detected. The sideband components around the fundamental frequency of magnetic flux leakage in stator yoke is particularly analyzed based on magnetic circuit. The magnitudes of induced voltage harmonics in search coils are also investigated by finite element method. The algorithm is implemented for a 4-pole three-phase cage induction machine with static, dynamic and mixed eccentricity. It is highlighted that dynamic eccentricity can be detected by any one of the search coils, static eccentricity and the position of minimum air gap can be detected by the magnitudes of induced voltages in all the search coils. The theoretical results have been validated by finite element method.
Electromagnetic scattering from a topological insulator cylinder placed in chiral medium
Authors: Ashraf Faheem , Ahmed Shakeel , Syed A.A. , Naqvi Q.A.
Published: December 2018

We study the scattering of time harmonic electromagnetic plane wave from a topological insulator circular cylinder in chiral medium. Variation of scattering behavior for different values of radii and permittivity of the cylinder is noted when time reversal symmetry is protected and we also studied the scattering behavior when time reversal symmetry is broken. Although scattering behavior of co-polarized component of field is not significantly different from chiral cylinder in chiral medium yet it is found that the same, when time reversal symmetry broken, is similar to scattering from a perfect conductors. Scattering behaviour of cross-polarized field component of topological cylinder in chiral medium is remarkably different from chiral cylinder i.e. it has stronger scattering possibly due to the presence of conducting states near the surface. Moreover, it is noted that the scattering in forward direction for cross-polarized and co-polarized components are not correlated with permittivity but for carefully selected values of permittivity, we can control the scattering behavior of topological insulator circular cylinder.
Design optimization of large gap single axis thrust magnetic bearing actuator
Authors: Dash S.K. , Swarup K.S. , Rajan K.K.
Published: December 2018

Magnetic Bearing, especially Active Magnetic Bearing (AMB) is arguably most preferred bearing for the process dealing with highly reactive environment, high speed operation and where the process required least contamination. They are also being tried for Fly wheels and Wind generators. They continue to be evolved since last several decades. Quite a few processes like application of AMB in high temperature Liquid Sodium high temperature applications call for development of large-working-gap active magnetic bearings(AMB). Smooth operation of AMB depends on hypersensitive position stiffness and Current stiffness, which fluctuates due to differential-thermal-expansion induced air gap variation. So, large gap, necessitates flatter open loop position stiffness than that of contemporary magnetic actuators. In this work, a goal seeking optimization methodology is employed for double acting AMB system where a combination of higher (CRGO electrical steel) and lower saturating magnetic material (Mu metal) is used. A less variant position stiffness across the air gap was arrived at after getting optimized design variables constituting geometry and excitation current parameters. This investigation opens up a new way to attain position stiffness in AMB system which is less sensitive to positional variation of rotor in air gap.

This paper proposes an innovative and first-of-its-kind bi-material core material with goal driven optimized magnetic actuator design which can afford to have air gap variation during operation.
Directivity enhancement of miniaturized microstrip patch antenna using metamaterial cover
Authors: Dwivedi Surabhi , Mishra Vivekanand , Kosta Yogesh P.
Published: December 2018

The variation in the spacing height of a metamaterial cover over the slotted patch antenna is reported to improve its directivity. HFSS software is used for simulations. An antenna is designed with a metamaterial cover to work in three bands within the frequency range of 1–4 GHz. A comparative result analysis of the effect of varying the spatial height of the metamaterial cover over patch antenna is shown theoretically. The proposed novel slotted patch antenna design has triband operation in the frequency range of 1–4 GHz with the miniaturized overall antenna size of the dimension 52.5 mm × 36.5 mm × 1.56 mm, that is equivalent to miniaturized design reported to our knowledge so far. For the very first time, the concept of Newton's divided difference method is applied for evaluating the performance parameters of the antenna. A global formula is developed to indicate the relationship of the directivity with the spatial height. The designed model has various applications in the field of satellite, aeronautical and optical communications mainly in the frequency range of L and S band.
Finite elements, design optimization, and nondestructive evaluation: A review in magnetics, and future directions in GPU-based, element-by-element coupled optimization and NDE
Authors: Hoole S. Ratnajeevan H. , Karthik Victor U. , Sivasuthan Sivamayam , Rahunanthan Arunasalam , Thyagarajan Ravi S. , Jayakumar Paramsothy
Published: December 2018

This paper reviews mathematical optimization in synthesis and nondestructive evaluation (NDE) by the finite element method in magnetics because background work has been inadequately attributed in the literature. The review identifies the earliest papers and reports new work in nondestructive evaluation and GPU-based matrix solution to save time and memory. Although the genetic algorithm has been applied in optimization, in coupled systems the number of object function evaluations doubles. We therefore examine the use of graphics processing units (GPUs) to handle the immense computational load. GPU memory limits are often not recognized and are critically limiting when parallelizing the several solutions required in optimization. To overcome this limit, element-by-element finite element matrix processing is employed, making coupled problems practicable on GPUs. We overcome the memory limits element-by-element processing, however, and achieve a GPU speedup of 147 by Jacobi conjugate gradients while forming the matrix of coefficients and of 80(and growing indefinitely) by Gauss iterations without forming the matrix for situations where memory is scarce such as genetic algorithm optimization where several copies of the matrix have to be held on threads.
A wideband 1:19 planar radial power divider design applied in circularly polarized array antenna
Authors: Fan Fang-Fang , Yan Ze-Hong , Wang Jin-Hiu
Published: December 2018

A wideband microstrip planar radial 1:19 power divider is developed in this study. The power divider design is simple with conventional impedance-transformation method, and a single substrate is employed, thereby reducing the cost for the antenna. To verify our design, the power divider was fabricated and tested. It can be observed that it achieves an impedance bandwidth of 29.4{\% (1.98 GHz–2.67 GHz) (VSWR ⩽ 2), the transmitted magnitude and phase imbalance for 19 outputs are ± 0.1 dB and ± 1 deg, respectively. The power divider is also integrated into the 19-element circularly polarized (CP) antenna array as the feed network; the simulated results show that the power divider can apply appropriate amplitudes and phases for the antenna array to obtain the good CP performance.
A high gain and simple-structured dielectric resonator antenna array with cylindrical rods and microstrip feeding
Authors: Liu Yufeng , Chen Xing , Xu Guanghui , Liu Changjun , Huang Kama
Published: December 2018

A novel microstrip-fed dielectric rod array antenna with high end-fire gain is proposed. It has simple structure, comprising a group of cylindrical dielectric rods and a microstrip corporate feeding network, and is low in cost. A prototype 4 × 4 array working at 8.0 GHz is designed, fabricated and measured. Simulation and measurement results show the antenna has encouraging performances, e.g. an impedance bandwidth(|S _{11} |←10 dB) of 7.7%, an end-fire gain up to 20.3 dBi, side-lobes 13.5 dB below the main lobe, and linear polarization with the cross-polarization level less than− 21 dB.
Wideband bowtie antenna with inverted L-shaped coupling feed and tuning stubs for indoor base station applications
Authors: Zhang Zhi-Ya , Zuo Shao-Li , Zhao Jia-Yue , Wang Shao-Chuan , Fu Guang
Published: December 2018

The paper proposes a wideband bowtie antenna for indoor base station applications. By using the inverted L-shaped coupling feed structure, the impedance bandwidth of the lower band is improved; while using the four tuning stubs, the upper band is enhanced. Thus, a wide impedance bandwidth of about 77.8% (VSWR les; 2) ranging from 1.38 to 3.14 GHz is obtained. In addition, by connecting two folded elements to the patches of the bowtie dipole, the compact dimensions of the antenna can be achieved. It also provides stable peak gain, unidirectional radiation patterns and low cross-polarization over the whole operating band. Owing to these good performances, the proposed antenna is very suitable for the recent indoor base station wireless communication services such as 3G, WiFi, WiMax, Bluetooth and LTE applications, etc.
Impact identification using a passive imaging method
Authors: Zhang Chao , Ji Hongli , Qiu Jinhao , Wu Yucheng , Hu Ning
Published: December 2018

This study presents a novel imaging method in passive sensing structural health monitoring (SHM), for locating impact damage in real-time on a plate-like structure. So far, many imaging methods have already been applied in active sensing SHM to locate the damages. However, seldom of the imaging methods can be directly used to locate the impact in passive sensing SHM. In order to avoid solving the hyperstatic hyperbolic equations and generate an informative image for locating the impact damage, the proposed method combines the imaging method with probability calculation. Moreover, to demonstrate the feasibility of the proposed method, the experimental results are presented and analyzed. From the results, the proposed method shows an interesting phenomenon that the accuracy of the impact localization depends on the impact position. Finally, a detailed analysis of the method accuracy is discussed.
Effect of electrode finger width on the strain and stress distributions in macro fiber composites
Authors: Lin Xiujuan , Chen Haiyan , Jiang Chao , Zhou Kechao , Zhang Dou
Published: December 2018

Finite element analysis was performed on the representative volume element of piezoelectric elements with interdigitated electrodes (IDEs). The variations of piezoelectric material properties during poling were considered in the analysis. The numerical results of models with different piezoelectric polarization states were compared with the result given by the so called uniform field model. Though different optimum electrode finger widths were obtained for different models, narrower electrode finger could enhance the actuation performance. The models indicated the stress concentrated at the edges of the finger electrode. Wider electrode finger would be beneficial for reducing the risk of material failure. The model with two different polarization states could be used to predict the strain and stress of MFCs with wider electrode finger to minimize the computational complexity. The modeling approach developed in this study allowed for a better understanding on the overall effects in piezoelectric materials with IDE structures.
Comparisons of damage-induced magnetizations between austenitic stainless and carbon steel
Authors: Li Hongmei , Chen Hong-En , Yuan Zhensheng , Cai Wenlu , Li Yong , Chen Zhenmao , Uchimoto Tetsuya , Takagi Toshiyuki , Yoshihara Kensuke
Published: December 2018

To explore the mechanism of damage-induced magnetization for paramagnetic austenitic stainless steel, the differences of damage-induced magnetizations between an austenitic stainless steel and a carbon steel are experimentally studied. Various plastic strains are introduced into the test-pieces of the austenitic stainless steel of 304 type and S185 carbon steel material. The residual plastic strains and the damage-induced magnetic fields nearby the test-pieces, the volume fraction of the damage-induced ferromagnetic martensitic phase in austenitic stainless steel test-pieces are measured. The relationships between the residual plastic strain and the damage-induced magnetic field of two materials are investigated and their differences are compared. In addition, by establishing the relationships of the damage-induced magnetic field with the damage-induced martensitic phase, the effect of the phase transformation on the damage-induced magnetization of austenitic stainless steel is analyzed.
An efficiency-improved hybrid implicit-explicit FDTD algorithm for analyzing electromagnetic scattering with fine geometries
Authors: Zhang Qi , Zhou Bihua , Yang Bo , Wang Jianbao
Published: December 2018

By applying the Crank-Nicolson (CN) scheme to the divided two parts of Maxwell's equations, an efficiency-improved hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method is proposed to analyze the electromagnetic problems with fine-scale structure. Numerical formulations of the proposed HIE-FDTD algorithm for a 2D TE wave are analytically derived. The HIE-FDTD method, although conditionally stable, allows for larger time-step size than the conventional FDTD method. Moreover, the numerical performance of the proposed method is verified to be quite good by comparing it against the existing HIE-FDTD method.
Utilizing electromagnetic properties to determine the micro-plastic limit of low-carbon steel CSN 411375
Authors: Gajdoš L'ubomír , Šperl Martin , Kaiser Jaroslav , Mentl Václav
Published: December 2018

It is generally accepted that not all cyclic stresses below the fatigue limit are non-damaging. Particularly in spectrum loading, the inclusion of some cyclic stresses below the fatigue limit can reduce the fatigue life of a component. It is believed that the boundary between damaging and non-damaging stresses is the so-called micro-plastic limit (MPL) defined as a macro-stress at which dislocation pile-up stresses begin to obstruct the magnetic domains in rotation to the direction of the tensile stress. This paper shows that MPL can be determined from changes in magnetic permeability during tensile loading. In our work, changes in magnetic permeability were measured indirectly – by measuring changes in electrical impedance (a.c. resistance and inductance). Measurements were performed on normalized low-C steel CSN 411375, and the microplastic limit was determined by evaluating the ΔR – σ and ΔL – σ records.
Compact dual-band power divider embedded with DMSWPL slow-wave structure
Authors: Peng Chia-Mei , Chen I.-Fong , Chou I.-Tung
Published: December 2018

In this paper, a compact dual-band power divider embedded with defect microstrip with periodic loading (DMSWPL) slow-wave structure is presented. The occupied space is effectively reduced by about 66.89% compared to the conventional dual-band Wilkinson power divider. The structure of this power divider and the formulas used to determine the design parameters have been given. Experimental results show that all the features of a conventional Wilkinson power divider, such as an equal power split, impedance matching at all ports, and a good isolation between the two output ports can be fulfilled at GSM-band (880 MHz ∼ 960 MHz) and DCS-band(1710 MHz ∼ 1880 MHz) simultaneously.
Comparison of particle swarm optimization and self-adaptive dynamic differential evolution for the imaging of a periodic conductor
Authors: Cheng Yu-Ting , Chiu Chien-Ching , Chang Shuo-Peng , Hsu Jung-Chin
Published: December 2018

The application of two techniques to reconstruct the shape of a two-dimensional periodic perfect conductor from mimic the measurement data is presented. A periodic conducting cylinder of unknown periodic length and shape scatters the incident wave in half-space and the scattered field is recorded outside. After an integral formulation, the microwave imaging is recast as a nonlinear optimization problem; a cost functional is defined by the norm of a difference between the measured scattered electric fields and the calculated scattered fields for an estimated shape of a conductor. Thus, the shape of conductor can be obtained by minimizing the cost function. In order to solve this inverse scattering problem, transverse magnetic (TM) waves are incident upon the objects and two techniques are employed to solve these problems. The first is based on an particle swarm optimization (PSO) and the second is a self-adaptive dynamic differential evolution (SADDE). Both techniques have been tested in the case of simulated mimic the measurement data contaminated by additive white Gaussian noise. Numerical results indicate that the SADDE algorithm is better than the PSO in reconstructed accuracy and convergence speed.
Experimental investigation on the electromagnetically controlled buoyancy-induced flow in a model of a Czochralski puller
Authors: Pal J. , Cramer A. , Gerbeth G.
Published: December 2018

A great deal of work with respect to both physical and numerical modelling of Czochralski crystal growth has been conducted in the generic Rayleigh-Bénard system. In order to come closer to the conditions in a real Czochralski puller, specific effects such as the influence of a rounded crucible bottom, deviations of the thermal boundary conditions from the generic case, crucible and/or crystal rotation, and the influence of magnetic fields are often studied separately. Within this paper we present a model experiment focusing on investigations of the impact of magnetic fields on the flow in a Czochralski puller. To achieve similar thermal boundary conditions as in an industrial growth facility, a double-walled rounded bottom glass crucible was chosen to hold the fluid. Similarity of the heat transfer conditions was guaranteed by selecting the ternary alloy GaInSn as the model fluid. Measurements of the fluid flow have been conducted by means of the ultrasound Doppler velocimetry. The results reveal the complex flow structure of natural convection in a Czochralski crucible. Because the growth of high quality mono-crystalline crystals is impeded by such a non-axisymmetric flow, rotating magnetic fields (RMF) are often proposed to render the flow more axisymmetric. To study the effect of an RMF on the natural convection in a Czochralski system the experimental apparatus was mounted inside the home-made MULTIpurpose MAGnetic field facility (MULTIMAG). In the present contribution the three-dimensional convective patterns as well as the resulting temperature fluctuations will be discussed both for the pure buoyant case and for the application of an RMF.
A penny-shaped crack in a magneto- electroelastic cylinder surrounded by a rigid body and subjected to magnetoelectro- mechanical loads
Authors: Liu L.L. , Feng W.J. , Ma P.
Published: December 2018

The fracture behavior of a penny-shaped crack in a constrained magnetoelectroelastic cylinder of finite radius under magnetoelectromechanical loads is investigated. The crack surfaces are assumed to be magnetoelectrically permeable. Eight kinds of possible boundary conditions at infinity are considered. The potential function theory and Hankel transform method are used to obtain a system of dual integral equations, the solution of which is further given by solving a Fredholm integral equation of the second kind. The field intensity factors are obtained and analyzed. The effects of both the ratio of crack radius to cylinder radius and the applied magnetoelectrical loads at infinity on the stress intensity factor are evaluated. The obtained results and/or conclusions could be of particular interest to the analysis and design of smart sensors/actuators constructed from magnetoelectroelastic composite laminates.
A frequency domain approach for computing the Lorentz force in electromagnetic metal forming
Authors: Otin Ruben , Mendez Roger , Fruitos Oscar
Published: December 2018

In this paper we present a finite element model in frequency domain which computes the Lorentz force that drives an electromagnetic forming (EMF) process. The only input data required are the electrical parameters of the capacitor bank, the coil and the work piece. The main advantage of this approach is that it provides an explicit relation between the parameters of the EMF process and the frequency of the discharge, which is a key parameter in the design of an optimum EMF system. The method is computationally efficient because it only requires to solve time-harmonic Maxwell's equations for a few frequencies and it can be very useful for coil design and for testing modeling conditions on complex three-dimensional geometries.
Design and modelling of a novel linear electromagnetic vibration energy harvester
Authors: Jiang Xuezheng , Wang Jiong , Li Yancheng , Li Jianchun
Published: December 2018

This paper presents the design and evaluation of a novel permanent magnet (PM) energy harvesting system for scavenging electrical energy from ambient vibrations. A two-phase tubular linear PM vibration energy harvester consisting of a mover attached with permanent magnets and a slotted stator with built-in two-phase electromagnetic coils is proposed to convert vibrational kinetic energy into electrical energy. Aiming at maximizing the efficiency of vibration-to-electrical energy conversion under designated vibration and limited space requirement, a systematic research, including innovative device design, theoretical modelling and analysis, and finite element evaluation on the PM vibration energy harvester will be presented in this paper. In addition, the methodology of winding the two-phase coils in slotted stator is explicated in order to fully utilize the harvested electrical energy. A two-phase rectifier circuit is developed to convert the alternative voltage generated by the PM harvester into DC voltage that can be used directly by the external resistive load. Simulation results indicate that the proposed linear PM vibration energy harvesting system is able to generate about 100 watt DC electrical power under the vibration with the velocity of 0.4 m/s and the output electrical power is proportional to the levels of vibration excitations.
Modeling and simulation of MEMS-based PZT beam array vibration energy harvester for high voltage output
Authors: Deng Licheng , Wen Zhiyu , Zhao Xingqiang
Published: December 2018

Piezoelectric vibration energy harvester as an autonomous power source for various types of sensors, actuators and MEMS devices has been investigated over the last decade. Traditional MEMS-based PZT single beam vibration energy harvester has low voltage output (usually less than 1∼V) which cause rectifier circuit to consume most of power or turn off in practical applications. In this paper, to improve the voltage output as well as ensure high power output of the MEMS-based PZT vibration energy harvester, a PZT beam array configuration is proposed. Based on Hamilton's principle and Euler-Bernoulli beam theory, mathematical model for the proposed vibration energy harvester is established, and then the model is verified through finite element model implemented by program ANSYS. Both mathematical model and ANSYS simulation show that the voltage output of the proposed vibration energy harvester is 5 times of the traditional vibration energy harvester and the mathematical model also show that the power output of the proposed vibration energy harvester is the same as the traditional vibration energy harvester. From the mathematical model, the voltage output of the proposed vibration energy harvester increase linearly with the total number of the beams.
Magnetic spring characteristic of an oscillatory actuator with silicone rubber torsion springs for optical scanner applications
Authors: Bu Yinggang , Kinjo Hideyuki , Oyaizu Kazuaki , Inoue Kaname , Mizuno Tsutom , Duan Zhihui
Published: December 2018

A compact electro-magnetic oscillatory actuator was proposed based on a pair of torsion springs for optical scanners operating at low oscillating frequencies, such as 50 Hz for a portable barcode scanner. Each torsion spring in the actuator is made of silicone rubber and is dually supported at both ends. A yoke is coupled with the driven coil to enhance the driving torque of the actuator. In this study, we analyzed the effect of the yoke on the resonant frequency of the actuator, as well as the torsion moment. We also experimentally determined the relationship between the resonant frequency and the magnetic gap of the yoke. Compared with the mechanical resonant frequency in the experiments, which was designed to be 50 Hz, the frequency was modified to 57.4 Hz, 54.7 Hz and 52.9 Hz when the gap between the yoke and the permanent magnet was 1.5 mm, 1.7 mm and 1.9 mm, respectively. The proposed actuator, which combines a yoke with flexible torsion springs, is potentially useful as a compact optical scanner, taking advantages of both low power consumption and high reliability.
Effects of compressive stress normal to the surface of non-oriented electrical steel sheets
Authors: Yamamoto Ken-ichi , Yanase Shunji
Published: December 2018

Changes in permeability and magnetic losses in non-oriented electrical steel sheets resulting from compressive stress have been investigated using a single-sheet tester. A compressive stress of up to 20 MPa is uniformly applied normal to the sheet surface. It is demonstrated that a stress beyond 5 MPa can decrease magnetic losses, including both hysteresis loss and eddy current loss.
Can rotational magnetization be theoretically assessed?
Authors: Appino C. , Ragusa C. , Fiorillo F.
Published: December 2018

We review state-of-the-art modeling of two-dimensional (2D) magnetization process in soft magnets. Emphasis is placed on the phenomenological assessment of the energy losses in steel sheets under rotational field. It is stressed that a general physically based theoretical framework, exploitable for applications in practical materials and machine cores, is not available at present. However, a rational approach to the 2D magnetic losses and their frequency dependence can be pursued. This is based on the separation between quasi-static (hysteresis) and dynamic magnetization processes and the connection with their unidirectional (scalar) counterpart. A number of vector models of the 2D quasi-static hysteresis behavior, typically residing on assessed scalar models, are discussed. They have prevalent formal-mathematical character, and, while being often helpful in numerical calculations, they leave unanswered the quest for solid physical interpretation. The dynamic magnetization process can, on the other hand, rely on a 2D phenomenological extension of the firmly established physical approach to the unidirectional scalar case provided by the statistical theory of losses. This is especially true for isotropic (i.e. nonoriented) magnetic laminations, where both rotational and elliptical flux loci can be conveniently handled. It permits one to achieve general appraisal of the experiments and flexible formulation, useful for numerical applications in machine cores.
Directional properties of loss components in electrical steel sheets
Authors: Pluta Wojciech
Published: December 2018

The efficiency of electrical machines depends among other things on the specific total loss of electrical steel the core is made of. Hence, a better understanding of the loss mechanism can improve the efficiency of machines. In order to analyze the specific total loss of electrical steel grades, they were separated into three components: the hysteresis loss component and both the classical and additional eddy current loss components. The relationship between loss components and direction of magnetization was analyzed. The aim of this paper is to provide a contribution to a better understanding of magnetic specific total loss in electrical steel sheets.
Vector magnetic properties and two-dimensional magnetostriction of various soft magnetic materials
Authors: Yamagashira Masayuki , Ueno Shohei , Wakabayashi Daisuke , Enokizono Masato
Published: December 2018

This paper presents measured vector magnetic properties and two-dimensional magnetostriction of a non-oriented electrical steel sheet(including a 6.5% SiFe sheet), a grain-oriented electrical steel sheet, an Fe-based amorphous sheet, and a permendur sheet. These electrical steel sheets have been widely used as a core material of electrical equipment. Because it is difficult to reduce a building factor of a practical machine made of stress sensitive materials, it is therefore important to understand detailed magnetic properties and magnetostriction characteristics. In order to grasp the basic magnetic properties, vector magnetic properties and two-dimensional magnetostriction were measured in the alternating magnetic flux conditions in the arbitrary direction. In this paper, the relationship among the magnetic flux density vector, the magnetic field strength vector, and the two-dimensional magnetostriction in the various electrical steel sheets under alternating flux condition is clarified.
Numerical and experimental study of electromagnetic-thermal coupling for electromagnetic shaker
Authors: Wu Yongxiang , Yang Baokun , Liu Zhen , Wang Cheng , Dong Longlei
Published: December 2018

In combining infrared (IR) thermography and the finite element method (FEM), a method is proposed for electromagnetic-thermal coupling analysis of an electromagnetic shaker armature assembly. IR thermography is used to obtain the temperature field of the armature assembly. Based on the lumped capacitance principle, this temperature field is then used to determine local convective heat transfer coefficients. FEM analysis of electromagnetic-thermal coupling is then performed using the obtained coefficients. The validity of this method is demonstrated by comparing measured and calculated transient temperature fields.
Contactless power and signal transmission system applied to a hydrostatic loading device
Authors: Zhang Shuwen , Xu Minglong , Jing Zijian , Feng Bo
Published: December 2018

In this paper, a system for supplying electric power and signal transmission wirelessly for the hydrostatic loading device is put forward. The electric power supplying and signal sending module of the system adopt contactless transmission method, which is commonly called CPT (contactless power transmission). Energy, with the form of a certain frequency of magnetic field, gets through the austenitic stainless steel. Being used as the chamber of the system, the austenitic stainless steel has the same relative magnetic permeability as the vacuum. After travelling through the chamber wall, energy is captured by the coil inside the chamber. Then it is converted into DC power and sent to the loads inside the chamber [1]. Signal processing and sending module converts the analog signals into digital ones and restore them. Data consisting of signals is sent out from the chamber with the form of magnetic wave. Devices outside the chamber receive the data and recover it.
Electrochemically synthesized PANI-MnO_2 coatings and their effect on interface properties of neural microelectrode
Authors: Zhang Wenguang , Wu Dongdong , Li Zhengwei , Luo Yun
Published: December 2018

In this paper, a simple and low-cost method for improving the performance of the neural microelectrodes is reported. The electrochemical polymerization of conducting polymer PANI and MnO _2 (manganese dioxide) were performed to modify the surface of the microelectrode

sites, then the morphology and electrical properties of the coated microelectrodes were investigated to analysize the influence of MnO _2

doping on the PANI coating. Results show that, the surface morphology of PANI coating was improved by MnO _2 doping. Compared to the electrode with PANI, the charge injection capacity of the electrode with PANI-MnO _2 increased by about 7-fold and the impedance decreased

to the original 1/6 (@ 1 KHz). The electrical properties were more stable and excellent with PANI-MnO _2 coating.
An improved longitudinal wave EMAT based on the shielding effect
Authors: Wu Xinjun , Ding Xu , Wang Li
Published: December 2018

Electromagnetic acoustic transducer (EMAT) has been used in many industrial areas due to its non-contact nature. However, the longitudinal wave EMAT is rarely employed because it is difficult to be generated. An improved longitudinal wave EMAT is proposed in this paper. By inserting the copper sheet between the coil and the test specimen, the eddy currents induced in the test specimen are changed and the components of the eddy currents for generating the shear wave are effectively suppressed. The performance of the EMAT is tested by the experiment.
Compact coplanar interferometer for a 5–6 GHz IFM system
Authors: de Oliveira B.G.M. , de Melo M.T. , Machado G.G. , Llamas-Garro I.
Published: December 2018

The authors present a new compact coplanar interferometer for application in an IFM system with 4 bits that operates in a frequency band from 5 to 6 GHz. This interferometer consists of a couple of coplanar two-way Wilkinson power dividers connected to two CPS lines with different signal delays. This interferometer presents smaller dimensions when compared to other designs. Details of this compact coplanar interferometer are provided along with a comparison between theoretical, simulated and measured results.
A smart antenna system for remote supervision
Authors: Santos M.R. , de Oliveira B.G.M. , de Melo M.T. , de Oliveira A.J.B. , Santos E.A.B. , Freitas R.D. , Serra R. , Santos M.M.L.
Published: December 2018

This paper presents a switched smart antenna system, designed to provide a reliable communication between a Center for Integrated Operation of a distributor of electric power and automation devices such as electrical switches remotely controlled. The smart antenna system is controlled by an electronic device which sets de direction of the main lobe of an antenna array to the automation device.