bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of electric and magnetic fields on liquid crystalline flow
Authors: Tsukiji Tetsuhiro , Yoshida Kousuke , Yokoyama Kazuya
Published: December 2018

We cause a low-molecular-weight liquid crystal in the nematic phase to flow between parallel plate electrodes at a constant rate. Under electric fields (in the range 0–1.0 kV/mm), magnetic fields (in the range 0.0–2.0 T, where 1 T=10000 G), and both magnetic and electric fields, we measured changes in liquid crystal flow resistance and orientation. We also estimated the crystal orientation by measuring the brightness of light through the crystal to investigate the relationship between pressure drop and orientation. As results, the pressure drop increases as electric and magnetic field intensities increase, and remains constant at E > 0.6 kV/mm. Under application of an electric field, the brightness of light through the liquid crystal increases with increasing rates of pressure in the range 0–0.4 kV/mm.
Design and development of a braille display using micro actuators driven by ER suspension
Authors: Tsujita Teppei , Kobayashi Masanori , Nakano Masami
Published: December 2018

ER suspension behaves like a Bingham fluid having yield stress, which can be rapidly changed in a reversible manner by applying electric field. By taking the advantage, Braille display using micro actuators driven by the suspension is developed. The micro actuators are fabricated by photolithography and allocated three dimensionally based on requirement specification which are determined experimentally. The system is integrated in small size and has high reliability since the valves consist of no moving components. In order to evaluate actuation of a micro actuator controlled by the valves, an experiment for displaying six tactile pins is performed.
Three-dimensional lattice Boltzmann method for magnetic fluids in the presence of weak magnetic field
Authors: Ido Yasushi , Sasaki Motoyasu
Published: December 2018

A lattice Boltzmann method for two-phase flows with large density ratios proposed by T. Inamuro, et al. (2004) is extended in order to simulate behavior of magnetic fluids in the presence of steady weak magnetic field. A new additional term corresponding to the Maxwell stress tensor is introduced into the distribution function. The additional term is determined by using the Chapman-Enskog expansion. Surface deformation of a magnetic fluid drop in the presence of magnetic field is simulated by using this method, and the results are qualitatively agree well with the experimental results.
Development of multiple-disk brake element using electro-rheological gel
Authors: Kakunuma Yasuhiro , Tanaka Hidetaka , Aoyama Tojiro , Anzai Hidenobu
Published: December 2018

Electro-rheological gel (ERG) is a functional elastomer, which changes its surface adhesive property according to the intensity of electric field. In this study, ERG is applied to multiple-disk brake element to realize both simplification of structure and wide range of controlled brake torque. First, static performance of ERG multiple-disk brake (ERG-MDB) is evaluated experimentally. It is clear that a generated brake torque depends on an electric field and the number of layer of ERG. ERG-MDB with 6 layers shows 5 times brake torque as high as that with 1 layer. Second, considering the dynamical model of the ERG-MDB, dynamic performance is investigated through the forced vibration test. The result shows that dynamic damping and stiffness coefficients are changed widely according to applied electric field.
Analysis of the effect of collision velocity in electromagnetic welding of aluminum strips
Authors: Desai S.V. , Kumar Satendra , Satyamurthy P. , Chakravartty J.K. , Chakravarthy D.P.
Published: December 2018

Electromagnetic welding (EMW) is a specific application of Electromagnetic Forming (EMF), owing to the fact that the latter very often than not precedes the former, which means that the metallic parts to be welded get deformed before getting welded. This is a new application of electromagnetic field. This being so, there are not much efforts made for the electrical characterization of the equipment to improve it's performance. The electrical parameter of the system are analyzed in detail in this paper for welding of aluminum strips of 1 mm and 2 mm thickness (width=400 mm and length=550 mm). The two bodies (to be welded) have necessarily to be separated from each other so that they acquire sufficient velocity before collision. The collision velocity is the important parameter in this process. The variation in collision velocity is computed for a range of separation distances. The optimum separation distance and minimum energy required for welding is computed and experimentally verified. The paper summarizes the analysis comprising of computational work, substantiated by data for mechanical strength tests and the study of microstructure. The correlation between the quality of weld and collision velocity has been established.
Efficient algorithms for the optimization of shielding devices for eddy currents
Authors: Yahaghia Alireza , Hafner Christian , Fallahi Arya , Smajic Jasmin , Cranganu-Cretu Bogdan , Vahldieck Ruediger
Published: December 2018

Different optimization algorithms are applied to determine the best configuration of a shielding device for eddy currents. The algorithms include seven stochastic binary optimizers, which are based on the concept of genetic algorithms and evolutionary strategies, as well as one quasi-deterministic optimizer based on an algorithm inspired by hill-climbing strategies. The comparison of results obtained from each algorithm shows a very high probability of finding global optima when a special quasi-deterministic algorithm is applied.
Design of current pulse for electromagnetic railguns
Authors: Xu Lizhong , Geng Yanbo
Published: December 2018

In this paper, using the differential equation of the armature motion for the electromagnetic Railguns, influences of the driving current distribution on the velocities of the projectile are investigated. Several kinds of the typical energy losses are considered. The influences of the driving current distribution on the transfer efficiency of the railgun system are analyzed. For a given exit velocity of the projectile and rail length, a proper relative time ratio of the pulse currents is determined which corresponds to the optimum system transfer efficiency. The results can be used to design pulse current distribution of the railgun system.
Fluid-induced frequency shift in a piezoelectric plate driven by lateral electric fields
Authors: Liu Bo , Jiang Qing , Yang Jiashi
Published: December 2018

We study thickness-shear vibration of a piezoelectric crystal plate whose one surface is in contact with a viscous fluid layer of finite thickness. The crystal plate is driven by a lateral electric field. The theory of piezoelectricity and the theory of Newtonian fluids are used. Both free and forced vibration solutions are obtained. An approximate expression for the frequency shift in the crystal plate due to the presence of the fluid is presented. The admittance of the structure is also calculated. The results are useful for acoustic wave fluid sensors.
Design of multi-DOF electromagnetic actuators using distributed multipole models and image method
Authors: Son Hungsun , Bai Kun , Lim Jungyoul , Lee Kok-Meng
Published: December 2018

Design and control of many electromagnetic actuators involve solving three dimensional (3D) magnetic fields of permanent magnets and/or electromagnets in the presence of magnetic conducting surfaces. This paper extends the distributed multipole (DMP) method, which offers compact but precise analysis for three dimensional magnetic fields in closed form, to account for the effects of magnetic conducting boundaries using the image method on the torque generated by electromagnetic actuators. We validate the proposed method referred to here as DMP-Image method by comparing the calculated torques against results computed by a finite element method (FEM). While two methods agree to within 5% in maximum torque, the DMP-image method takes less than 1% of the FEM computation time. Finally, we demonstrate the DMP-Image method to design a spherical motor in a class of multi-DOF actuators. While developed in the context of the multi-DOF actuators, the modeling methods presented in this paper are applicable to design of other PM-based actuators.
Position control of magnetic beads by means of electromagnetic fields with respect to apodal locomotion systems
Authors: Greiser Steffen , Böhm Valter , Zimmermann Klaus
Published: December 2018

Motivated by the technical progress, electromagnetic action principles are more and more used in micro systems. It is well known that the discrete positioning of magnetic beads like ferrofluid droplets can be realised using an array of electromagnets whereat the position of the beads depends on the arrangement of the electromagnets.

This paper refers to the analogous positioning of magnetic beads independent from the arrangement of the electromagnets. Therefore a control strategy was designed to position magnetic beads like ferrofluid droplets, ferrogels or ferroelastomers. The derived control law allows the definition of dynamic properties like time and damping constant. To achieve these properties, the controller is adjusted based on a model of the plant. This model regards the dynamical movement of the mentioned materials in electromagnetic fields and is characterised by simplified, nonlinear, ordinary differential equations.

The theoretical results are verified by means of a basic assembly allowing the positioning of spherical ferroelastomers on macro scale. The measurements illustrate that the theoretically derived position controller meets the requirements of a predefined time and damping constant.
Reconstruction of faulty wiring networks using reflectometry response and genetic algorithms
Authors: Smail Mostafa Kamel , Pichon Lionel , Olivas Marc , Auzanneau Fabrice , Lambert Marc
Published: December 2018

This paper presents an effective technique to reconstruct faulty wiring networks and/or to localize the defects affecting the branches of a wiring network from the reflectometry response. The direct problem (propagation in the cables) is modelled by RLCG circuit parameters and the Finite Difference Time Domain (FDTD) method whereas the inverse problem is solved using Genetic Algorithms (GAs). In a first step the forward problems is validated by comparison with experimental and simulated data. In a second step the proposed reconstruction method is applied on different configurations and the results are discussed.
Influence of operating parameters on energy consumption of electrohydrodynamic drying
Authors: Bai Yaxiang , Hu Yucai , Li Xinjun
Published: December 2018

The influence of operating parameters on the drying rate and energy consumption of Electrohydrodynamic (EHD) has been experimentally evaluated in this study. Tofu contained in the Petri dish was put in EHD system which was made up of a wire pole and a plate pole. By changing the voltage, the electrode spacing and the distance between the two neighboring wires, the factors related to the drying rate and energy consumption were quantitatively studied. The results indicate that when the distance between the wire electrodes and the surface of the plate pole is constant, the drying rate increases linearly while the drying energy consumption increases nonlinearly with the supplied voltage. When the supplied voltage is not changed, the tofu drying rate and energy consumption are changed with the distance between the two neighboring wires. When the distance between the two neighboring wires is not changed, the tofu drying rate and energy consumption are changed with the electrode spacing. When the electrode spacing is 9 cm and the distance between the two neighboring wires is 9 cm, the drying rate is the highest while the energy consumption is relative least, 45 kV is the optimum value for drying voltage.
Resonant frequency of parallel plate type uniaxially anisotropic multilayered cylindrical dielectric resonator
Authors: Seçkin Gürel Çiŭdem , Yenilmez Rumeysa
Published: December 2018

In this paper, two different methods for the determination of resonant frequency of parallel plate type uniaxially anisotropic multilayered cylindrical dielectric resonator are firstly presented for dominant TE _{0ml} and TM _{0ml} modes. The first method called as Effective Permittivity Approach (EPA) mainly depends on the determination of single effective permittivity of the multilayered structure. The second method, Weighted Frequency Approach (WFA), depends on the evaluation of resonant frequency of the multilayered structure by weighting the resonant frequencies of each layer. Obtained results using these two approaches are close to each other indicating resonant frequency of uniaxially anisotropic multilayered resonator can be tuned by adjusting the segment parameters. Therefore, in its multilayered form, cylindrical dielectric resonator designed with uniaxial materials will exhibit some advantages over isotropic single layered resonator providing flexible operational characteristics. According to the presented results, application areas of cylindrical dielectric resonator in its proposed form will increase especially in future microwave and communication systems applications as a promising structure.
New approach for efficient planar multiport using the concept of edge line and the boundary-element method
Authors: Ourabia Malika , Touhami Rachida , Baudrand Henri
Published: December 2018

In this paper, the authors proposed a new approach for efficient planar multiport junction design using the concept of edge line and the boundary-element method. The S-parameters are obtained by a simple identification in a system of equations given by the boundary method. In addition to a reduction in the CPU time, the proposed method can easily handle complicated structures. The method is verified by comparison to previous work on junctions.
Frequency shifts in a quartz plate piezoelectric resonator in contact with a viscous fluid under a separated electrode
Authors: Liu Bo , Jiang Qing , Yang Jiashi
Published: December 2018

We study thickness-shear vibration of a rotated Y-cut quartz crystal plate whose one surface is in contact with a viscous fluid layer of finite thickness. The fluid is under an electrode separated from the crystal plate and the driving electric field is in the plate thickness direction. The theory of piezoelectricity and the theory of Newtonian fluids are used. Both free and forced vibration solutions are obtained. An approximate expression for the frequency shifts in the crystal plate due to the fluid is presented. The admittance of the structure is also calculated. The results are useful for acoustic wave fluid sensors.
Numerical modeling for plasmonics
Authors: Miano Giovanni , Rubinacci Guglielmo , Tamburrino Antonello
Published: December 2018

This contribution is a review paper, concerning mainly the research work made by the authors, about the numerical modeling, in the frequency domain, of both surface and bulk plasmon oscillations induced in metallic nanoparticles with arbitrary shapes by an external electromagnetic field. Surface plasmons are governed by a local constitutive relation, whereas bulk plasmons are governed by a constitutive relation that is expressed by a partial differential equation. The electromagnetic field scattered by the nanoparticles is evaluated using an integral formulation. In nanoparticles with maximum linear dimensions much smaller than the vacuum wavelength the plasmon dynamic may be studied approximately by using the electro quasi-stationary approximation of the Maxwell equations. The paper discusses both a full-wave integral formulation, where the unknown is the induced current density, and an electro quasi-stationary integral formulation, where the unknown is the surface charge density.
Multi-field coupled dynamics for micro plate
Authors: Xu Lizhong , Sun Libo
Published: December 2018

In the vibration system consisting of the micro plate, electric field and fluid film, the electrostatic force and the fluid film pressure play important role. To consider the effects of the electrostatic force and fluid film pressure on the micro plate vibration, an electromechanical-fluidic coupled dynamics model should be developed. It is a multi-field coupled dynamics problem. Here, the nonlinear electromechanical-fluidic coupled dynamic equations of the micro plate subjected to the electrostatic force and the fluid film pressure are derived. Using KBM method, the nonlinear multi-field coupled dynamic equations are resolved. Meanwhile, the equations of the electric field and the fluid pressure fluctuations are presented. Using these equations, the nonlinear multi-field coupled free vibration and the forced responses of the micro-plate are analyzed. Results show that the electrostatic force and the fluid film pressure have obvious effects on the dynamic displacements of the micro-plate, and the dynamic displacements of the micro-plate can cause fluctuations of the electrostatic force and the fluid film pressure. These results are useful in the design and manufacture of such MEMS.
Comparison of particle swarm optimization and asynchronous particle swarm optimization for inverse scattering of a two- dimensional perfectly conducting cylinder
Authors: Chiu Chien-Ching , Sun Chi-Hsien , Chang Wan-Ling
Published: December 2018

This paper reports a two dimensional time domain inverse scattering algorithm based upon the finite-difference time domain method for determining the shape of perfectly conducting cylinder. Finite difference time domain method (FDTD) is used to solve the scattering electromagnetic wave of a perfectly conducting cylinder. The inverse problem is resolved by an optimization approach and the global searching scheme asynchronous particle swarm optimization (APSO) is then employed to search the parameter space. By properly processing the scattered field, some EM properties can be reconstructed. One is the location of the conducting cylinder, the others is the shape of the perfectly conducting cylinder. This method is tested by several numerical examples; numerical results indicate that the APSO outperforms the PSO in terms of reconstruction accuracy and convergence speed. Both techniques have been tested in the case of simulated measurements contaminated by additive white Gaussian noise.
Stability enhancement of haptic interaction by frequency-dependent damping and its application to scaled teleoperation
Authors: Lim Yo-An , Kim Jong-Phil , Ryu Jeha
Published: December 2018

This paper presents a frequency-dependent damping element, called an analog input shaper (AIS), to improve the stability of haptic interaction with virtual or real environments. High frequency inputs to a haptic interface, which usually occur in the collision with very stiff objects, can bring limit cycle oscillations and instabilities. In order to reduce these high frequency inputs and thus to improve the stability of haptic interaction, the AIS is added to the haptic system. Moreover, the AIS is applied to a passivity-based haptic stability control algorithm, called an energy-bounding algorithm (EBA), to increase the displayed impedance range by the EBA. Through scaled teleoperation experiments using an atomic force microscope (AFM), we show that the AIS can enhance stability during haptic interaction and consequently increase impedance range that a haptic interface can stably display. Also, we show that the AIS can alleviate conservativeness of the passivity-based haptic control algorithms.
A method of personal positioning for indoor customer tracking utilizing wearable inertial sensors
Authors: Ohtaki Yasuaki , Hu Dan , Hashimoto Koichi , Inooka Hikaru
Published: December 2018

This paper presents a method for indoor personal positioning especially addressing on a simple gait measurement using a body-mounted inertial sensor, a walk path estimation algorithm, and a trajectory identification technique. Considering utility of on-site customer traffic tracking, the method was designed to be autonomous needless of neither external measures nor cumbersome installations to the environment. The inertial sensor combining three-dimensional accelerometer, angular rate sensors, and geomagnetic sensors was used to assess walking dynamics and to obtain changes of heading directions. To avoid an inherent problem of the walk trajectory estimation by conventional dead-reckoning algorithm, an advanced probabilistic map matching method which employs a Particle filter was developed. The experiment with healthy male adults was evaluated to confirm the utility of the method in a condition of small retail store. The result showed that the proposed method demonstrated sufficiently feasible tacking which delineated personal trajectories and positioning while shopping. The method showed possible availability with the portable instrument and improved estimation accuracy by the advanced probabilistic map matching which identifies proper routings on the basis of the maximum likelihood. The method will be useful to enhance ambulatory personal tracking technique in daily indoor environment.
Analysis and prediction of meal motion by EMG signals
Authors: Horihata S. , Iwahara H. , Yano K.
Published: December 2018

The lack of carers for senior citizens and physically handicapped persons in our country has now become a huge issue and has created a great need for carer robots. The usual carer robots (many of which have switches or joysticks for their interfaces), however, are neither easy to use it nor very popular. Therefore, haptic devices have been adopted for a human-machine interface that will enable an intuitive operation. At this point, a method is being tested that seeks to prevent a wrong operation from occurring from the user's signals. This method matches motions with EMG signals.
Study on dynamic characteristics of gyroscopic power generator
Authors: Ishii Tomohiro , Iwasaki Jun , Hosaka Hiroshi
Published: December 2018

To solve energy supply problems for ubiquitous equipment, dynamic analysis of a gyroscopic power generator that uses the kinetic energy developed from human movement is proposed. In the generator, a rotor increases its spinning velocity by precession and friction caused by input vibration. This paper first presents an analytical method of rotor movement. The equations of motion are derived by using Euler's equation and their approximate solution is obtained by assuming the spinning velocity is constant. Then the output power of the prototype generator is estimated by using the solution. The output power of the ideal generator was shown to be 0.11 W and 0.85 W during walking and running, respectively.
Passivity based control for a magnetically levitated flexible beam with rate estimation via the extended Kalman filtering technique
Authors: Shimizu Toshimi , Sasaki Minoru , Okada Tokuji
Published: December 2018

This paper presents a passivity based control method combined with velocity estimation by an extended Kalman filter for a magnetically levitated flexible beam with both ends free by two electromagnets. An energy-based analysis concludes that the system can be decomposed into two passive subsystems: a mechanical subsystem consisting of the flexible beam and an electrical subsystem consisting of the electromagnets. We designed a passivity based controller independently for each subsystem. An output feedback controller for the mechanical subsystem computes the desired force that is required to achieve position convergence and vibration suppression of the flexible beam. A feed forward controller for the electrical subsystem computes the input voltage for the electromagnets to generate the desired force. In a practical point of view, structural and economic considerations restrict simultaneous usage of both position sensors and velocity sensors while the control strategy requires accurate measurements of the position and velocity of the flexible beam. We employ the extended Kalman filtering technique in order to estimate the velocity of the flexible beam from the measured micro-displacement vibration at a high sampling frequency. Effectiveness of the proposed controller and velocity estimator is demonstrated by a numerical simulation.
Parallel controller construction for a multi-DOF hand rehabilitation equipment
Authors: Ito Satoshi , Ueki Satoshi , Ishihara Koji , Miura Masayuki , Kawasaki Haruhisa , Ishigure Yasuhiko , Nishimoto Yutaka
Published: December 2018

This paper describes the development of a hand rehabilitation system for stroke patients. Our objective is to provide fine motion assistance in exercises for a hand and fingers. Thus, a hand rehabilitation device that assists patient's finger movements was developed. Because this device has 18 degrees of freedom, it is difficult for disabled patients to use it by themselves. Therefore, an appropriate control strategy and a control system are required to allow it to be used safely and effectively. In light of this requirement, a control system was developed that comprises four separate controllers. This paper presents the structure of the control system and introduces the control protocols used in the hand rehabilitation system.
Two-degree-of-freedom control of a self-sensing micro-actuator for HDD
Authors: Sasaki Minoru , Fujihara Koji , Nam Yoonsu , Ito Satoshi , Inoue Yoshihiro
Published: December 2018

The present paper describes a two-degree-of-freedom control of a self-sensing micro-actuator for a dual-stage hard disk drive. The two-degree-of-freedom control system is comprised of a feedforward controller and a feedback controller. Two controllers are designed for the two-degree-of-freedom control system, one using the inverse dynamic model for the feedforward controller and one for the feedback controller using a self-sensing signal from the actuator itself. The micro-actuator uses a PZT actuator pair, installed on the assembly of the suspension. The self-sensing micro-actuator can be used to form a combined actuation and sensing mechanism. Experimental results show that the two-degree-of-freedom control approach can be used effectively for the control of the self-sensing micro-actuator system.
Standing and sitting motion of an inverted pendulum type assist robot using whole-body motion with force control
Authors: Jeong Seonghee , Takahashi Takayuki
Published: December 2018

This paper describes quick and stable standing and sitting motion of an inverted pendulum type robot by whole-body motion including force control. The whole-body motion is achieved by controlling composite center of gravity of the robot, and damping force control of a wrist-roller is employed to assure the stability of inverted pendulum control on a contact situation with the ground. Motion planning of standing and sitting based on the proposed control method is also proposed. Standing and sitting motion using the proposed motion control and motion planning is simulated with a dynamic simulator, ODE (Open Dynamics Engine). From the simulation results, it was confirmed that the robot successively realized the standing and sitting motion quickly and stably.
Meal assistance robot with ultrasonic motors
Authors: Tanaka K. , Kodani Y. , Oka M. , Nishimura Y. , Farida F.A. , Mu S.
Published: December 2018

In this paper, we develop a meal assistance robot for people with disabilities of upper limbs and pacemakers in the body. In the robot, ultrasonic motors are used because the motors do not generate an electromagnetic field. The robot is handled using acts of user's eyes so that the people can use it. Moreover, the vibration is small because the arms of our robot move independently of each other. In this paper, we introduce structure of our robot and show the advantage with experiment results.
Prototyping of a motion base for a desktop interaction system, consisting of a combination of a wheel drive and a parallel mechanism
Authors: Tarao Susumu , Koiwa Toshihiko
Published: December 2018

A new kind of motion base is proposed for the purpose of setting up a user-friendly interaction system on a desktop. It aims at generating motion in various situations with a large range of movement using a simple mechanism, and generating motion adequate for an interaction with a man and for computer application. In this paper, a prototype of the motion base is developed. Its mechanism consists of a combination of a wheel drive locomotion mechanism and a 3-degrees of freedom (DOF) parallel link mechanism in parallel. It is aimed at generating 3 DOF translational motion on a desktop with a simple mechanism as a whole and with a large range of movement, especially in the horizontal direction. In consideration of application for man-computer interaction, the prototype is controlled by a microprocessor, a microcontroller and FPGA. This paper presents a description of the concept of the motion base for a desktop interaction system, the prototype mechanism, the control system and the preliminary experiment which demonstrates typical translational motions.
Speed control and magnetic analysis of crawling robot with magnetic binder
Authors: Lee Sung-Whan , Yoo Jeonghoon , Rhim Sungsoo
Published: December 2018

A crawling robot with a magnetic binder called CROMAB is developed and the finite element magnetic analysis and the speed control system of the robot are studied. CROMAB is designed to be used on the slopped surface and to perform pipe-cutting, welding, or similar process onto the work-surface. The robot binds itself to the magnetic-permeable surface using magnetic force and autonomously travels along the work-path. In the current research, the particular application of pipe-cutting process is considered. A repetitive learning controller is designed and implemented to maintain a constant velocity and consistent cutting performance by compensating the varying gravitational effect caused by the position change of the robot and the nonlinear disturbances caused by mechanical defects of the robot. An accelerometer-based angular displacement estimation system is developed and implemented for the improved control performance.The magnetic binding system is analyzed by using an finite element analysis tool. The numerical analysis of the magnetic system and the experimental results of the control system verify the effectiveness of CROMAB.
Compressive and tensile stresses of magnetorheological fluids in squeeze mode
Authors: Mazlan Saiful A. , Ismail Izwan , Zamzuri Hairi , Abd Fatah A. Yasser
Published: December 2018

Magnetorheological (MR) fluid exhibits a perceptible change of rheological properties in reaction to external magnetic field. The MR fluids are currently enjoying renewed interest within the technical community in terms of the fundamental and applied research. MR fluids behaviour in squeeze mode is one of the areas that remain unknown as compared to valve and shear modes. Therefore, this paper presents stress-strain relationships of MR fluids under compression and tension tests. The results demonstrated that MR fluid corresponded to the changes in compressive and tensile stresses due to the changes in magnetic field strength. The compressive stresses were found to be much higher than the tensile stresses for the same experimental parameters. The behaviour of the MR fluids were dependent on the types of the carrier fluid and magnetic field strength. Furthermore, combinations of the stress-strain curves under quasi-static compression and tension modes were matched with the curves under dynamic loading.
Research on strain characteristics and power generation mechanism of electroactive acrylic elastomer
Authors: E Shi-Ju , Cao Jian-Bo
Published: December 2018

The strain characteristics and power generation mechanism of electroactive acrylic elastomer (EAE) was studied by experiments based on theoretical analysis. The strain characteristics and generator mode theory fundamentals of EAE were discussed and studied. The mathematical model of EAE was established. A power conversion control system for EAE was designed. Electroactive strain values were measured for different pre-strain and driving voltages. The power generation process of EAE was tested under different influencing factors. The experimental results show that the inflexion of electroactive strain was found for different pre-strain values, and the electroactive strain value increased with the augmentation of the driving voltage when the pre-strain level was below the inflexion, otherwise, the electroactive strain value decreased with the augmentation of the driving voltage. The hysteresis loop due to the viscoelasticity charateristic of EAE was measured. The energy generated as nearly incompressible elastomer layers increase in area and decrease in thickness when EAE stretched, and power generated when EAE relaxed. The voltage of power generation increased with the augmentation of the bias voltage, pre-strain level and compression speed. The experimental results accorded with analytical model and lay the foundation for actuators, generator and sensors of EAE.
Domain of influence theorem and uniqueness results in magneto-thermoelasticity
Authors: Awad Emad
Published: December 2018

In this paper, some energy inequalities are developed for an unbounded perfect electrically conducting generalized thermoelastic region moving in a variable magnetic field. Sufficient restrictions on the magneto-thermoelastic moduli and solutions are given in order that the perturbations initially generated in a bounded domain of the body cannot invade the whole body. Some uniqueness results are readily proved provided that such restrictions are met.
An analytical complementary FEA tool for optimizing of axial-flux permanent-magnet machines
Authors: Mahmoudi Amin , Rahim N.A. , Hew W.P.
Published: December 2018

This paper presents an analytical approach to calculate the magnetic field in a slotted axial-flux permanent-magnet machine. The method is modeled on a simple nonlinear magnetic analysis of an equivalent magnetic circuit with a saturation-possible magnetic-reluctance core in a slotted axial-flux permanent-magnet machine. It calculates flux distribution and torque characteristic in various operating conditions. Its accuracy and validity are verified by results that match those of a Finite Element Analysis model. This method serves as a complementary design tool to FEA especially in expediting design optimization of an electrical machine. The method is as accurate as FEA but betters FEA with its shorter computation time, making it the better alternative in initial estimations. After verification of the analysis, sensitivity to design variables by using the proposed model is presented. The sensitivity analysis through the proposed magnetic circuit of the AFPM machine provides an effective way for selection of design parameters. These parameters are iteratively adjusted through multi-objective optimal design in order to obtain maximum output torque and efficiency. Simulation results show AFPM machine efficiency to be affected the most by its diameter, followed by magnet fraction, and the least by back-iron thickness.
Magnetic material identification of a switched reluctance motor
Authors: Abdallh Ahmed Abou-Elyazied , Crevecoeur Guillaume , Sergeant Peter , Dupré Luc
Published: December 2018

The identification of the magnetic material characteristics for the switched reluctance motor by solving an inverse problem is presented. The inverse problem aims at identifying the magnetic material parameter values of the magnetic circuit, starting from measured torque profiles. The computational time of the inverse problem is appreciably reduced by implementing a space mapping-based inverse approach. Using the space mapping technique, we combine the computationally intensive finite element model with a much faster magnetic network model. The proposed approach is very helpful for the material identification problem on the electrical machine, and the obtained results reveal the success and the reliability of the proposed scheme.
Automated optimal design of a hts coreless winding
Authors: Di Barba Paolo , Mognaschi Maria Evelina , Palka Ryszard , Savini Antonio , Yatchev Ivan
Published: December 2018

The optimal shape design of a coreless High-Temperature Superconductor (HTS) winding has been defined in terms of finding the position and length of a set of flux diverters, in such a way to minimize an appropriate objective function. Results for both direct and inverse problems are presented. Additionally, the minimization of the objective function has been pursued by solving a material synthesis problem, in which the geometry of the diverters is given, and their permeability is unknown.
Comparison between efficient global optimization and output space mapping technique
Authors: Ayed R. Ben , Berbecea A.C. , Brisset S. , Gillon F. , Brochet P. , Yatchev Ivan
Published: December 2018

The optimization of electromagnetic devices by direct use of finite element models is computationally expensive. This paper presents two effective surrogate-assisted optimization algorithms: Output Space Mapping and Efficient Global Optimization which are employed with regard to a minimum number of finite element model evaluations. A parallel between the two algorithms is made through a single phase safety isolating transformer optimization problem using 3D finite element models.
Coupling electromagnectic and thermo-hydrodynamic simulations to optimize a vitrification furnace heated by direct induction
Authors: Dessus V. , Platas J. , Brun P. , Sauvage E. , Cauffet G. , Dedulle J.M. , Yatchev Ivan
Published: December 2018

This study deals with the optimization of a cold crucible melter where electric currents are directly induced in a glass charge. Designs of experiments are used to determine the factors of the crucible design which have an impact on the efficiency, and result in an optimized configuration. Numerical tools are used to lead the experiments: a finite volume software, used to solve hydrodynamics and thermal equations, is coupled to a finite element software which computes the Maxwell equations. The innovation is the use to couple directly areas treated with surface impedance and volume formulations, in electromagnetic simulation. The optimized configuration is then studied comparing numerical simulations and experiments in an industrial unit.
Live tissue electromagnetic properties characterization
Authors: Mateev Valentin , Marinova Iliana , Yatchev Ivan
Published: December 2018

In this paper a method for characterization of live tissue electromagnetic properties is proposed. The method combines data, acquired by experimental computer system for bio-impedance measurements, and image data obtained by infrared camera. The data from impedance analyzer and from infrared camera are collected simultaneously for a given time period. The impedance data are associated with infrared image data for electromagnetic properties determination. The method developed is applied to evaluate the electromagnetic properties of biological tissues. The proposed method is applicable for local electric properties determination in inhomogeneous samples with random form.
TEM analysis of vertical broadside symmetrically coupled strip lines with anisotropic substrate
Authors: Ilić Saša S. , Aleksič Slavoljub R. , Raičević Nebojša B. , Yatchev Ivan
Published: December 2018

Theoretical analysis of a vertical broadside symmetrically coupled strip line assuming TEM propagation mode is presented in the paper. The effective dielectric permittivity and characteristic impedance of the analysed strip line is determined applying the Equivalent Electrodes Method (EEM), and the results are compared with the ones obtained using the Finite Element Method(FEM). The paper shows determination of the closed-form Green's function of uniform charge per unit line length placed in an anisotropic medium between two parallel infinite grounded plates. Additionally, dielectric permittivity tensor has a diagonal form, and both, even and odd, modes are considered.
Numerical modelling of microwave heating in landmines detection
Authors: Szymanik Barbara , Gratkowski Stanisław , Yatchev Ivan
Published: December 2018

Landmines, which affect numerous of territories in the whole world, pose a serious threat mostly to civilians. Therefore there's no doubt that the work on improving the methods of landmines' detection and liquidation should be considered important. Nowadays most effort should be focused on detecting the most common, nonmetallic landmines. In present study we introduce the new method of landmines' detection: active infrared thermography with microwave excitation, which may be considered complementary to popular metal detector. In this paper we present numerical models (created using TDFEM method) of microwave heating of chosen systems. The comparison between the numerical and experimental results will be presented as well.
The use of magnetic field annealing on nodular cast iron for speaker cores
Authors: Mozetic Halston , Fonseca Eduardo , Schneider Eduardo L. , Kindlein, Jr. Wilson , Schaeffer Lírio
Published: December 2018

This work presents the application of induced magnetic field during the heat treatment of Nodular Cast Iron to improve the magnetic permeability of this material in order to use it in speakers, as a lower cost alternative to the forged low carbon steel. Magnetic field annealing was carried out observing the performance of the initial magnetic permeability of the samples, and subsequently measured with field saturation equipment. The results were correlated with the data obtained from the use of the SAE 1020 steel, with the same conditions of use and laboratory tests. Metallographic and chemical composition analyses were carried out on the samples, and the correlation of these data with the magnetic properties. Results of this study show the possibility of using magnetic field annealing as a way to increase the permeability of a material with high carbon content as the nodular cast iron.
Numerical expressions in time domain for electromagnetic fields due to lightning channels
Authors: Izadi M. , Kadir M.Z.A. Ab , Gomes C. , Ahmad W.F. Wan
Published: December 2018

In this paper, by considering the factors that influence the charge height variation along the lightning channel and using Maxwell's equations, general expressions in time domain for the evaluation of electromagnetic fields at an observation point are proposed. The lightning channel is assumed to be perpendicular to the ground surface and the ground conductivity is considered to be perfect. Our results showed that the proposed method has good agreement with the measured values, as we validated the outcome using fields measured at close and intermediate distances from the lightning channel. A set of general equations, which has the ability of evaluating any given channel base current function and current model in time domain is also derived.
Optimal design of direct-driven PM wind generator using adaptive univariate dynamic encoding algorithm for searches (uDEAS)
Authors: Jung Sang-Yong , Lee Dongsu , Choi Min-Goo , Kim Jong-Wook
Published: December 2018

In this paper, optimal design of the direct-driven PM wind generator, combined with uDEAS (univariate Dynamic Encoding Algorithm for Searches) and FEA (Finite Element Analysis), has been performed to maximize the Annual Energy Production (AEP) over the whole operating wind speed. In particular, an adaptive scheme of arranging search variable sequence in uDEAS is newly proposed according to variable's measured gradient to cost function. The proposed adaptive scheme is embedded in uDEAS and validated through two test functions, and the modified uDEAS is applied to optimal design of the direct-driven PM wind generator. With the comparable quality of the attained solution, uDEAS enormously reduces computation time when compared with Genetic Algorithm (GA) implemented by the parallel computing method.
Dependence of deformation-induced magnetic field on plastic deformation for SUS304 stainless steel
Authors: Li Hongmei , Chen Zhenmao , Li Yong , Takagi Toshiyuki , Uchimoto Tetsuya , Chigusa Naoki , Yoshida Yasuhiko
Published: December 2018

In this paper, the correlation between plastic deformation and the deformation-induced magnetic field was experimentally investigated for the SUS304 austenitic stainless steel. Test-pieces with different shapes were fabricated to produce different strain distribution. Various plastic tensile loads were imposed into the specimens to introduce plastic deformations of different levels. The residual strain distributions at the surfaces of the specimens were measured by an optical 2D strain measurement system during loading process while the distributions of the deformation-induced magnetic fields above the specimens were measured by using a fluxgate magnetometer after each loading cycle. The experimental results show that the amplitudes of the magnetic field have a clear and repeatable relationship with the maximum residual strains for all the specimens, and the relationship is independent of the strain distribution. Based on the experimental results, the mechanism of the deformation-induced magnetic field was discussed, and a NonDestructive Evaluation (NDE) method was proposed for the quantitative evaluation of plastic deformation in the SUS304 stainless steel.
Analysis of caustic region fields of a cassegrain system having PEMC reflectors embedded in homogeneous chiral medium
Authors: Qasim Mehmood Muhammad , Junaid Mughal Muhammad , Rahim Tarim
Published: December 2018

Analysis of high frequency field expressions for the Cassegrain system having perfect electromagnetic conducting (PEMC) boundaries are studied. Both the reflectors of Cassegrain system are PEMC and are embedded in chiral medium. Two different cases have been analyzed depending upon the values of chirality parameter (kβ). In the first case, chiral medium supports positive phase velocity (PPV) for both the left circularly polarized (LCP) and right circularly polarized (RCP) modes. In the second case, chiral medium supporting PPV for one mode and negative phase velocity (NPV) for the other mode is taken into account. Mathematical recipe proposed by the Maslov is used to obtain the field expressions in the focal region because geometrical optics (GO) causes non-realistic singularity in this region. Field patterns of focal plane are given in the paper for different values of admittance (M) of the PEMC boundary and the chirality parameter (kβ).
Inspection of rebars in concrete blocks
Authors: Perin Deniz , Göktepe Mustafa
Published: December 2018

Inspection of rebars in concrete blocks is most important issue for civil engineering applications, such as reinforcing the damaged buildings, bridges, power stations and nuclear plants. This study is concerned the research and development of a nondestructive rapid inspection technique for rebars in concrete blocks. The rebar is magnetized near to saturation by using a soft iron U-core and two magnetization coils. An inductive scanner is designed and tested to generate dimensionally accurate images of steel reinforcing components that embedded within reinforced and pre-stressed concrete for condition assessment and structural integrity monitoring. The system was locally magnetized by a U-core and then 500 turns search coil sensor with an iron core was used to capture flux leakage from surface of the concrete block at certain currents and magnetization frequencies.
Numerical optimization of the magnet system for the Lorentz Force Velocimetry of electrolytes
Authors: Alferenok Artem , Werner Michael , Gramss Michael , Luedtke Ulrich , Halbedel Bernd
Published: December 2018

Lorentz Force Velocimetry is a contactless method for the flow rate measurement of electrically conducting fluids. This method is based on the interaction of the fluid flow with the transversal permanent magnetic field. The equal electromagnetic force acts on the fluid and on the magnet system. The flow rate can be determined by measuring of this electromagnetic force. The magnet system has been optimized to achieve maximal sensitivity at a given magnet system weight. The sensitivity was defined as the ratio between the Lorentz force and the magnet system weight. The numerical model was developed using COMSOL Multiphysics. Validation and verification of the numerical model has been performed. The magnet system was optimized using the optimization toolbox in MATLAB.