bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of diamagnetically stabilized non-vertical levitation using the magnetic charge equivalence
Authors: Nemoianu Iosif Vasile , Küstler Gerald , Cazacu Emil
Published: December 2018

The present paper proposes an analytical magnetic charges equivalence procedure for computing the magnetic field created by the lifting magnets in a non-vertical levitation structure. The proposed method avoids the repetitive solving of the problem needed by any numerical analyse package in order to reach the balance of forces at the equilibrium point. Demagnetization in open-loop of the used NdFeB magnets is taken into account by determining their operating point on the BH-curve. The equilibrium point location is calculated and its stability is checked through the stability discriminants. Several horizontal and an inclined structures are computed and the results are compared with the ones obtained with the professional field computation package RADIA. Finally, the calculation results are validated in comparison with experimental results.
Analysis and design of a moving-magnet type linear actuator with repulsive magnetic forces
Authors: Olaru R. , Astratini-Enache C. , Petrescu C.
Published: December 2018

The paper describes a newly developed miniature moving-magnet type linear actuator with proportional action that uses repulsive magnetic forces. Out of four possible structures, two with mobile magnets and two with fixed ones, the most simple and cheap prototype was chosen, offering good possibilities to obtain a miniature structure. A comparative numerical analysis for two types of mobile element justifies the adopted constructive solution. A laboratory prototype was analyzed numerically and experimentally in view of a possible optimization, the experimental and numerical results being in good agreement. Finally a prototype actuator was built and tested.
The guided waves in planar waveguide partially filled with strong chiral material
Authors: Ali Muhammad Mahmood , Mughal Muhammad Junaid , Rahim Arbab Abdur , Naqvi Qaiser Abbas
Published: December 2018

The electric and magnetic field expressions of guided waves in three-layer planar waveguide containing strong chiral material have been investigated theoretically. All three layers are parallel to the walls of the waveguide. Middle layer of the waveguide is filled with the air however the other two layers are filled with strong chiral material. The behavior of field intensity in different regions of the waveguide is discussed. It is shown that the location of maximum field intensity is shifted by changing the source frequency and modes of waveguide.
Ultra-wideband bandpass filter with a notch band using multi-mode stub loaded resonator
Authors: Wu Hung-Wei , Chen Yu-Fu
Published: December 2018

New ultra wideband (UWB) bandpass filter (BPF) with a notch band at 5.8 GHz using multi-mode stub-loaded resonator (SLR) is presented. The very sharp roll-off UWB characteristics of the proposed filter can be easily obtained by using the SLR. The multi-mode stub-loaded resonator consists of two propagation paths with λ/4 open-circuited stubs for providing the two transmission zeros at lower and upper passband edge. The notch band at 5.8 GHz can be well determined by tuning the structural parameters of the asymmetric interdigital coupled input/output (I/O) lines. This study mainly provides a simple method to design the high passband selectivity UWB filter with notch band for Federal Communications Commission(FCC-defined) indoor UWB specification. Experimental verification is provided and good agreement has been found between simulation and measurement.
Electromagnetic field in the caustic region of a spherical reflector under oblique incidence using Maslov's method
Authors: Ghaffar Abdul , Ahmed Shakeel , Naqvi Q.A.
Published: December 2018

A theoretical investigation is made for the problem of electromagnetic field focussing by wide angle spherical reflector receiving obliquely incident plane waves of linearly polarized monochromatic radiation. The Maslov's method has been applied to determine the electromagnetic fields in the caustic region of the reflector. High frequency field expression which contains caustic region is converted into caustic free field expression by transforming the situation into hybrid domain. The high-frequency field solution that contains the caustic region is obtained from geometrical optics. The defect in high frequency solution due to geometrical optics is overcome by Maslov's method. Two cases of polarization of the incident wave have been considered, namely, (1) with the field parallel and (2) perpendicular to the meridional plane of incidence. The numerical computations are made to study the behavior of field intensity in caustic region using Maslov's method. The analytical and numerical results obtained from Maslov's method are also compared with method of angular spectrum which are in agreement.
Focusing of electromagnetic field by a circular reflector coated with chiral medium
Authors: Farooqi Abdul Razzaq , Mughal Muhammad Junaid , Mehmood Muhammad Qasim
Published: December 2018

High frequency electromagnetic field expressions are analyzed for the focal region of a circular reflector coated with chiral medium. Maslov's method has been used for the study of focal region fields because geometrical optics is an approximate method and fails at the focal points. The effects of chirality parameter, thickness of chiral coating and permittivity of the medium on the focused fields are observed. It is concluded from the results that focused field strength increases with increase in chirality parameter, relative permittivity and thickness of the chiral coating.
Electromagnetic fields in a circular waveguide with DB-boundary conditions internally coated with chiral-nihility medium
Authors: Hassan Muhammad Haseeb , Mughal Muhammad Junaid , Ali Muhammad Mahmood , Naqvi Qaiser Abbas
Published: December 2018

The present study deals with the propagation of electromagnetic fields and power in a circular waveguide, with DB-boundary conditions, internally coated with chiral-nihility medium. The two layer circular waveguide defined by DB-boundary conditions, with one layer containing free space while other layer containing chiral-nihility medium, is investigated. DB-boundary conditions require vanishing of normal field components of the D and B vectors, hence termed as DB-boundary conditions. It has been studied that there is non-zero electric and magnetic fields in free space as well as in chiral-nihility medium in a circular waveguide defined by DB-boundary conditions. Hence, there is non-zero power transfer both in nihility as well as non-nihility regions
Modeling and levitation control of a novel M-DOF actuator based on neural network
Authors: Li Zheng , Sun Huiqin , Wu Xueli , Liu Qingrui
Published: December 2018

Modeling and torque characteristics analysis are important for actuators or motors with complicated structures. Based on the presented configuration design, the magnetic field and torque calculation for a multiple degrees-of-freedom (M-DOF) spherical actuator are performed using 3D FEM. To reduce the computation workload, a simplified torque calculation model and non-linear system dynamic model have been proposed, and magnetic levitation mechanism is developed for alleviating the friction and resistance to improve the dynamic performance of this M-DOF actuator. A linear mathematical model of the levitation force is deduced and corresponding control scheme with power drive unit is discussed. Then the diagonal recurrent neural network (DRNN) based control scheme is presented to improve the performance of levitation by adjusting parameters online as identifiers. Simulation and experiment results show that the actuator can effectively implement 3-DOF motion combined with levitation mode, and that the proposed approach can be applied to M-DOF actuators of the same kind effectively.
Diagnosis of electromagnetic properties and light flash characteristics created by hypervelocity impact\m{1}
Authors: Tang Enling , Zhang Qingming , Xiang Shenghai , Yang Minghai , Liu Fusheng , Zhang Mingjian
Published: December 2018

In order to diagnose electromagnetic properties and light flash characteristics generated by hypervelocity impact, the diagnostic systems of sweep Langmuir probe(SLP) and triple Langmuir probe (TLP) for electron temperature and electron density in plasma were established, properties of magnetic field were obtained by using coil measurement system established, and characteristics of light flash were also acquired through optical pyrometer measurement system during the whole physical process in hypervelocity impact, Experimental results showed that the average electron temperature of the triple Langmuir probe was near 0.75 eV on the whole physical process, the average electron density in the experiment was about. However, the electron temperature and electron density of plasma acquired by using t he sweep Langmuir probe were lower than the values by using triple Langmuir probe. The peak value of magnetic induction intensity induced by plasma was 9.8× 10 ^{11} /cm ^3 during the hypervelocity impacts, and light flash intensity peak value was 40–50 mW.cm ^{-2} .nm ^{-1} in the experimental conditions in the paper.
Collinear crack problems in a soft ferromagnetic solid
Authors: Chang Chao , Gao Cun-Fa , Shi Yan
Published: December 2018

The 2D problems of a soft ferromagnetic solid with collinear cracks are studied based on the complex variable method. First, the general solutions for potential functions of magnetic fields and stress fields are derived by using magnetically permeable, impermeable and conducting crack models, respectively. Then, for special cases of one and two cracks, more explicit solutions are given for potential functions and intensity factors of total stresses. Finally, numerical results are presented to discuss the effects of applied magnetic loading on fracture behavior of the ferromagnetic solid. It is found that the total stresses always have the classical singularity of the r^{ - 1/2} type at the crack tips for the considered three crack models, and the applied magnetic loading may either enhance or retard crack growth depending on the adopted crack models.
Numerical study of electrical behaviour in carbon nanotube composites
Authors: Spinelli Giovanni , Giustiniani Alessandro , Lamberti Patrizia , Tucci Vincenzo , Zamboni Walter
Published: December 2018

A structure aimed at modeling a polymeric nanocomposite loaded with carbon nanotubes (CNTs) is simulated by considering, in a three-dimensional space, a random distribution of impenetrable conducting cylinders inside an insulating cubic matrix. The variation of the electrical conductivity of the structure for different volume loadings of the conducting phase is estimated through a 3D resistor network. The tunneling effect between conducting clusters which is deemed responsible of the global conductivity is taken into account. By using a Monte Carlo method, the electrical conductivity and the percolation thresholds of the obtained structures are analyzed as a function of geometrical and physical influencing parameters.
Thermoacoustic generation of airborne ultrasound using carbon materials at the micro- and nanoscale
Authors: Harrer Andrea , Daschewski Maxim , Prager Jens , Kreutzbruck Marc , Guderian Matthias , Meyer-Plath Asmus
Published: December 2018

The generation of airborne ultrasound is presented using the thermoacoustic principle applied to carbon materials at the micro- and nanoscale. Such materials are shown to be capable of emitting ultrasound when being fed by an alternating current. We tested the acoustic performance of carbon fibers, bucky papers and electrospun polyacrylonitrile-derived carbon nanofibers and determined the sound pressure for frequencies up to 350 kHz. A comparison between the experimental results and the theoretical prediction showed remarkable agreement for frequencies up to 150 kHz. Beyond 150 kHz, we found slight deviations from the expected sound pressure dependence on the square root of the frequency.
Adaptive mapping of the plasma operational space of ASDEX Upgrade for disruption prediction
Authors: Aledda Raffaele , Cannas Barbara , Fanni Alessandra , Sias Giuliana , Pautasso Gabriella , ASDEX Upgrade team The
Published: December 2018

The Self-Organizing Map is a computational method for the visualization and analysis of high-dimensional data. Self Organizing Maps have been applied to ASDEX Upgrade data to define an ordered mapping of an 8-dimensional plasma parameter space onto a regular, 2-dimensional grid. The map has been used to track the plasma trajectory during the experiments and monitor the disruption risk. In order to face with ever new operational conditions, a periodical updating of the Self Organizing Map is proposed.
Analysis of error field sources in TOKAMAK devices
Authors: Oliva A. Bonito , Formisano A. , Martone R. , Portone A. , Testoni P.
Published: December 2018

Due to unavoidable tolerances in components construction and assembly, the actual magnetic field in Tokamak devices differs from the nominal one. The experimental studies nowadays available indicate a strong impact of the error fields on the plasma stability in next generation, large size, devices. Therefore, a careful preliminary analysis aimed at evaluating the impact of possible error field sources, to define tolerance ranges and assess the effect of current feeders, was envisaged before realization of ITER reactor. The paper discusses the tools used to perform ITER tolerance analysis, from the viewpoints of two possible approaches to tolerancing, which are statistical analysis and worst case analysis. The two methods aim to get different characterizations of devices performance, and a critical comparison of drawbacks and advantages of both methods is reported.
Modelling and control for plasma disruption avoidance and mitigation
Authors: Albanese Raffaele , Ambrosino Giuseppe , Cannas Barbara , Fanni Alessandra , Pironti Alfredo , Rubinacci Guglielmo , Sias Giuliana , Ventre Salvatore , Villone Fabio
Published: December 2018

This paper proposes an approach aimed at avoiding or mitigating the consequences of a plasma disruption in a tokamak. The control strategy is based on a Disruption Predictive Control (DPC) where the use of a set of disruption predictors could allow actively modification of some plasma parameters when a disruption warning is issued. The DPC approach requires the continuous monitoring of various plasma performance indicators, which play the role of disruption precursors. The active control is based on the availability of magnetic and nonmagnetic plasma parameter response models as well as multivariable control algorithms and architectures.
Development of magnetic levitation synchronous motor with high-Tc superconducting bearing
Authors: Murakami Iwanori , Kobayashi Yusuke , Gyoda Masashi , Ando Yoshinori , Yamada Kou
Published: December 2018

In this study, we propose a new magnetic levitation synchronous motor with a high-Tc superconducting bearing. The levitation rotor obtains the levitation force by the magnetic attraction and the restoring force (axially and radially to the shaft) from a superconducting bearing. The levitation rotor to which the magnetic flux concentration method is applied has a large magnetic field outside of the rotor. Because the superconducting bearing constrains this concentrated magnetic flux, the rotor obtains a large restoring force. In addition, a superconducting bearing with a small bulk can be realized. We stabilized the rotor using this method and confirmed that this motor passed the resonance and that its speed increased to approximately 3500 [rpm] without control.
Adaptive estimation strategy for coupled EEG-MEG analysis
Authors: Ferraioli Fabrizio , Formisano Alessandro , Martone Raffaele
Published: December 2018

Human brain electric activity related to important physiological functions can be pictured from bio electric and/or bio magnetic measurements through inverse problems approach. In this paper an iterative strategy is presented. The strategy is optimized to reconstruct brain activity confined in a sub region of the brain volume by jointly processing both bioelectric and biomagnetic signals. The procedure takes advantage from intermediate evaluations to improve the resolution, while limiting the number of unknowns. The advantages of the proposed approach is a higher robustness against noise and uncertainty and better effectiveness.
An improved normal boundary intersection method for multiobjective inverse problems
Authors: An Siguang , Liu Lei , Yang Shiyou
Published: December 2018

An improved normal boundary intersection (NBI) method is proposed. To overcome the deficiency of NBI methods in finding one Pareto solution in a single run, the utopia plane is divided into sub-domains. Dual external archives are proposed to enhance the diversity of the population. A new elite strategy is introduced to keep the balance between global and local searches. Two counter vectors are defined and used to record the mapping rate and selection rate of each sub-domain to act as elites to guide searches. The projection distance is employed to select candidates for next cycle of iterations. The expending of the ideal plane is implemented to sample completely the whole objective space and obtain an even distributed Pareto front. To validate the proposed algorithm, it is used to solve mathematical functions and an inverse problem with promising results.
Efficient robust optimization based on polynomial chaos and tabu search algorithm
Authors: Wu Lie , Yang Shiyou , Bai Yanan , Machado José Márcio
Published: December 2018

The study of robust design methodologies and techniques has become a new topical area in design optimizations in nearly all engineering and applied science disciplines in the last 10 years due to inevitable and unavoidable imprecision or uncertainty which is existed in real word design problems. To develop a fast optimizer for robust designs, a methodology based on polynomial chaos and tabu search algorithm is proposed. In the methodology, the polynomial chaos is employed as a stochastic response surface model of the objective function to efficiently evaluate the robust performance parameter while a mechanism to assign expected fitness only to promising solutions is introduced in tabu search algorithm to minimize the requirement for determining robust metrics of intermediate solutions. The proposed methodology is applied to the robust design of a practical inverse problem with satisfactory results.
Fast, accurate and reliable identification of hidden conductive objects with deterministic and stochastic methods
Authors: Reinbacher-Köstinger Alice , Magele and Christian , Renhart Werner
Published: December 2018

The identification of a conductive object known in shape but hidden by low- or non-conductive material is a special application of non-destructive eddy current testing. To find the positioning and orientation parameters of an object from the magnetic flux densities measured in a distance of several centimeters, a non-linear inverse problem has to be solved. This can be done by deterministic as well as stochastic optimization methods in principle. In order to fulfill all demands on the identification process, that are high accuracy, reliability and low computation time, a combination of a deterministic and a stochastic method is useful and was therefore applied to the problem at hand. It is shown that the computation time can be decreased enormously applying a hybrid method while the required accuracy and reliability hold.
A novel magnetic testing method for the loss of metallic cross-sectional area of bridge cables
Authors: Wu Xinjun , Yuan Jianming , Ben Anran
Published: December 2018

It is important to inspect bridge cables to insure the safety of the bridge, especially to test its loss of metallic cross-sectional area (LMA). A novel magnetic testing method for the LMA that the magnetic energy directly imposes on the bridge cable is proposed, which has advantages over the magnetic flux measurement used by traditional main-flux and return-flux methods. Its equivalent magnetic circuit is obtained, too. Furthermore, according to the magnetic Kirchhoff's Law and Taylor expansion series, the theoretic model is obtained by ignoring the higher order and used to analyse the proposed magnetic testing method. Finally, it is verified experimentally and shown good resolution.
An inversion scheme for sizing of wall thinning defects from pulsed eddy current testing signals
Authors: Xie Shejuan , Chen Zhenmao , Wang Li , Takagi Toshiyuki , Uchimoto Tetsuya
Published: December 2018

In this paper, an inversion algorithm has been proposed and validated, based on a fast simulator of pulsed eddy current testing (PECT) signals and a deterministic optimization strategy, for the profile reconstruction of wall thinning in pipes of nuclear power plants. Local wall thinning is modelled as a group of planar defects with different length and depth, reconstructed from two-dimensional PECT signals. Through inverse analysis of simulated signals and signals with random noise, the efficiency and the robustness of the proposed algorithm have been demonstrated.
Analysis of excitation current parameters in pulsed eddy current testing for ferromagnetic metallic materials
Authors: Xu Zhiyuan , Wu Xinjun , Huang Chen , Ke Hai
Published: December 2018

In pulsed eddy current (PEC) testing, excitation signal parameters are of great importance for the probe detectability. Square-wave current excitation with linear ramp edges used in measuring steel-plate thickness is studied in this work. Based on spectrum analysis, simulation and experimental study, the influences of the duty cycle and edge transition time on response signals are analyzed. Results show that for thin specimens the duty cycle can be decreased properly but the edge time should be as small as possible, and for thick specimens the duty cycle should be close to 50% while the edge time can be increased properly. This study can provide a reference for PEC signal interpretation and optimization of excitation parameters.
Detection of subharmonics in ultrasonic inspection of contact surfaces under compression
Authors: Kurihara Kenji , Naitou Keiichi , Sugiura Toshihiko
Published: December 2018

Detection and sizing of a closed crack in structures are difficult by conventional ultrasonic testing. One of promising alternative methods is nonlinear ultrasonic testing which detects subharmonic responses from a closed crack. This study investigates generation of subharmonics at contact surfaces of two specimens, modeling a closed crack, under ultrasonic radiation. Experiments of ultrasonic inspection were carried out by preparing different kinds of surface roughness of the specimens and also by changing compression force acting on the two contacting specimens. Our experimental results show some subharmonic responses from the contact surfaces, which can be influenced by the contact pressure and the contact surface roughness.
Numerical analysis of correlation between fibre orientation and eddy current testing signals of carbon-fibre reinforced polymer composites
Authors: Cheng Jun , Qiu Jinhao , Takagi Toshiyuki , Uchimoto Tetsuya , Hu Ning
Published: December 2018

This paper deals with eddy current testing simulation for carbon-fibre reinforced polymer composites (CFRPs) using an edge – element FEM code. The FEM code is based on the A formulation and it uses the coupled analysis with external fields. The coil impedance variations due to the fibre orientation and cracks in CFRP plates with unidirectional plies are computed. The conductivity of CFRP is characterized as low value and high anisotropy, which cause the distinct difference between CFRP and isotropic metal ECT signals. The correlation of the fibre orientation with coil impedance variations is obtained, but the exact fibre arrangement in a composite plate can't be ascertained because of signal symmetry. Another method for determining the fibre orientation via the edge effect is presented in this study. According to the numerical results, the shape of cracks in a CFRP plate is not easily evaluated from the detection signal curves unless the fibre orientation is perpendicular to the crack path.
FEM comparisons between RF-ECT signals in quasi-static or transient and linear or nonlinear regimes: ECT probe speed effect for in-service inspection of magnetic SG tubes in FBR
Authors: Garcia-Rodriguez Daniel , Mihalache Ovidiu , Ueda Masashi
Published: December 2018

Two-dimensional axis-symmetric finite element method (FEM) simulations are conducted to study remote field eddy current testing (RF-ECT) in ferromagnetic steam generator (SG) tubes for fast breeder reactors (FBR). The present work investigates a combination of quasi-static and transient analysis with both linear and non-linear material properties. Two FEM codes are employed: a commercial one based on COMSOL and a 2D-FEM code developed in-house. Both codes are used to evaluate the influence of the speed of the ECT probe during in-service inspection of SG tubes at a low excitation frequency. As a result, the maximum error in SG tube defect detection when using the classical linear and quasi-static approximations is obtained.
Flaw detection in three-dimensional shape portion using uniform eddy current multiprobe
Authors: Fukuoka Katsuhiro , Hashimoto Mitsuo
Published: December 2018

We designed exciting coils of uniform eddy current multiprobes with considering the shape of structures in order to obtain a uniform eddy current flow. A probe for a flat plate could obtain clear signals for an electrical discharge machining (EDM) slit of depth 0.5 mm and distinguish EDM slits arranged at 2 mm intervals. We confirmed that stress corrosion cracking (SCC) is detectable with sufficient sensitivity using the developed multiprobe. The probe for a curved portion obtained clear signals for the EDM slits on a curved surface of radius 25 mm. Moreover, we examined the technique for estimating crack shape from detection signals.
Multi-frequencies ECT algorithms for ISI of ferromagnetic SG tubes of FBR using FEM simulations
Authors: Mihalache Ovidiu , Yamaguchi Toshihiko , Ueda Masashi
Published: December 2018

The paper presents analyses and numerical validations of eddy current testing (ECT) algorithms used during In-Service Inspection (ISI) of ferromagnetic steam generator (SG) tubes of Fast Breeder Reactors (FBR). The purpose of such algorithms is to remove from ECT signal the electromagnetic noise resulting from sodium accumulated outside of SG tubes after SG vessel draining. Finite element method (FEM) simulations are used to analyse different sodium build-up scenarios observed experimentally, and to determine optimal multi-frequency ECT algorithms to suppress the most efficiently sodium noise. A novel "window multi-frequency" algorithm is applied and validated using 3-dimensional FEM simulations of SP and sodium forms.
Non-destructive sizing method for ball bearing flaking
Authors: Tsunokai Manabu , Takase Kentaro , Kayata Ryo , Nakano Kenzo
Published: December 2018

This paper proposes a new non-destructive method for evaluating the size of the flaking in ball bearing with an electromagnetic sensor. This method focuses on the variation of the magnitude of the characteristic frequency of a defect on the outer race. Through the presence of local maximums and minimums, the length of the flaking is evaluated while the bearing is in operation. The applicability and accuracy of this method is confirmed through several accelerated aging tests. It is shown that the growth of the length of the flaking in ball bearings is linear.
Non-destructive method for evaluation of deterioration of austenitic stainless steel using initial magnetic phase
Authors: Kinoshita Katsuyuki , Hasegawa Yu , Matsumoto Eiji
Published: December 2018

We report a novel non-destructive evaluation method (NDE) that relies on the magnetic properties of the inherent ferromagnetic phase in austenitic stainless steel (SUS) parts to assess the state of damage. The effects of the volume fraction, internal stress, and shape anisotropy of the ferromagnetic phase on the electromagnetic impedance signal used in the NDE are discussed on the basis of experimental results for cold-rolled SUS 304 steel plates of different thicknesses with and without stress relief annealing. In particular, the influence of shape anisotropy is clarified on the basis of measurements conducted on 0.5-mm-thick samples both parallel and perpendicular to the rolling direction. The results of the measurements show that the parameters obtained by the proposed method are indicative of damage.
Pre-processing methods for eddy current data analysis using Hilbert-Huang Transform
Authors: Yang Guang , Khan Tariq , Zhang Lu , Dib Gerges , Xin Junjun , Udpa Lalita , Majumdar Shantanu , Udpa Satish , Kim Jaejoon
Published: December 2018

An advanced nonlinear, non-stationary signal processing algorithm using Hilbert-Huang Transform is presented for automatic analysis of eddy current data collected during the inspection of steam generator tubes in nuclear power plants. The proposed algorithm reduces noise and enhances defect indication in the signal, thereby yielding increased detection probability as well as reduced false calls. Results of applying the algorithm on field data from SG tube inspection are presented and compared with those of current practice in industry.
Numerical modelling of eddy-current testing taking into account the effect of the measuring circuit
Authors: Skarlatos Anastassios , Reboud Christophe , Decitre Jean-Marc , Mahaut Steve
Published: December 2018

The volume integral method is combined with a circuit solver for the modelling of eddy-current inspection applications by taking into account the effect of the measuring circuit. It is demonstrated that the latter may result in noticeable deformations of the acquisition signals for specific inspection situations, thus it cannot be eliminated by simple calibration; this effect becomes increasingly important when the measuring frequency approaches the probe resonance. Comparisons of the simulation results with experimental data demonstrate the necessity of accounting for the circuit effect for inspection in driver pickup mode and verify the validity of the approach.
Study of flaws inspection in ceramics materials using UT and X-Ray methods
Authors: Nishimura Yoshihiro , Suzuki Takayuki , Kondo Naoki , Kita Hideki , Hirao Kiyoshi
Published: December 2018

The possibility of inspecting flaws in ceramic materials using Ultrasonic Testing (UT) and X-Ray methods was studied to investigate the reliability of ceramic material joints. First, Scanning Electron Microscope(SEM) images of two grades of ceramics were compared to those acquired by a scanning acoustic microscope (SAM) with respect to the number, and size of flaws. Second, ceramic sample with a known size of internal voids was evaluated by X-Ray-CT. Third, two jointed ceramic specimens were evaluated by X-Ray methods, SAM, and other UT methods. X-Ray methods and UT methods effectively established the safety of ceramic materials for structural uses.
Thickness evaluation of thermal spraying on boiler tubes by eddy current testing
Authors: Takahashi Yohei , Urayama Ryoichi , Uchimoto Tetsuya , Takagi Toshiyuki , Naganuma Hiroshi , Sugawara Kazufumi , Sasaki Yoriaki
Published: December 2018

This paper discusses the feasibility of thickness evaluation of Ni-based alloy coating sprayed on type 304 austenitic stainless steels by swept frequency eddy current testing which measures the impedance spectra of coil. Comparing the experimental signals with the numerical ones, the electromagnetic models of coating are developed. Using these models, the inverse analyses are conducted. The coating thicknesses are estimated within the maximum error of 22 μm.
Online detection of inter-turn short circuit faults in dry-type air-core reactor
Authors: Zhao Yanzhen , Ma Xikui , Yang Jichao
Published: December 2018

Inter-turn short circuit faults are among the common faults occurring in dry-type air-core reactor. This paper presents an online detection method of inter-turn short circuit faults for dry-type air-core reactors by using search coils. Since this type of fault creates shorted turns in which there are high induced currents that can produce intense reversed magnetic field, the magnetic field distribution is no longer symmetrical. The variety of magnetic field from the normal condition to the fault condition can be monitored by search coils. Based on coupled field circuit method, the magnetic field distribution of the reactor and the induction voltage of the search coils are computed in different conditions. The proper mounted positions of search coils are suggested. The proposed method has been verified to be effective and easy for implementation by experimentation.
3D anatomical atlas applied to breast
Authors: Leite Alysson , Brasil Lourdes , Gasparini Marina , Parente Marina , Lamas Janice
Published: December 2018

The creation of an entire system with a significant quantity of details that gets as closer as possible to reality is the point of the project 3D anatomical atlas applied to breast. For this, a series of tools and techniques were analyzed, discarded and chosen along the process of conception, considering studies and thesis' about biomedical modelling. Methontology was chosen as the methodology for this study. Protégé is being used for the ontology and Autodesk Maya allowed the creation of the 3D model.
Analysis of the similarity between residual magnetic field distribution and the stress and strain state for 7CrMoVTiB10-10 (T/P24) steel
Authors: Roskosz Maciej , Bieniek Michał
Published: December 2018

Distributions of the residual magnetic field (RMF) were compared to the results of the calculations of plastic strain and residual stress for samples made of 7CrMoVTiB10-10 (T/P24) steel. The RMF was measured on the surface of samples with a various degree of strain. The calculations of the stress and strain state were conducted by means of the finite elements method with the use of a bilinear model of the material. Qualitative and quantitative relationships were found between plastic strain and the RMF components, as well as between residual stress and the RMF component derivatives. On the basis of the found relationships, the algorithm for the evaluation of residual stress was developed and preliminarily verified using the measurements of the RMF components. The trends of further research aiming to confirm the practical suitability of the developed algorithm for the evaluation of the stress and strain state were formulated.
Comparison of real-time control strategies with hysteresis compensation for magnetostrictive actuators
Authors: Davino Daniele , Giustiniani Alessandro , Iannelli Luigi , Visone Ciro
Published: December 2018

Magnetostrictive actuators are employed for several purposes but, often, the control strategy is strongly affected by their hysteretic behavior. Such issue becomes crucial if dynamic mechanical stress conditions apply. Indeed, the stress must be considered as an additional input. Nevertheless, a compensation scheme with two-input variables can be defined and fruitfully utilized in a suitable invertibility region. In this paper, different control strategies, based on a compensation algorithm able to take into account the applied mechanical stress, are proposed and compared with simpler linear controllers in a real-time setup. Experimental data measured over a magnetostrictive actuator are presented and commented.
Damping force of a semiactive damper utilizing magnetic particles under applied magnetic field
Authors: Ido Yasushi , Hayashi Koichi , Kawai Takuma
Published: December 2018

Damping properties of a damper utilizing magnetic particles are investigated experimentally. A group of magnetic particles is treated as the working fluid in a damper instead of oil. In the presence of magnetic field, the damping force of the particles damper drastically increases. The maximum damping force appears near the dead center of vibration and higher frequency produces stronger maximum damping force, when the vibration frequency is in the range of low frequency below 5 Hz.
Effects of strip thickness and silicon content on Magnetic Barkhausen Noise of non-oriented electrical steel at 50∼Hz
Authors: Chukwuchekwa Nkwachukwu , Moses Anthony , Anderson Phil
Published: December 2018

Magnetic Barkhausen Noise (MBN) can be used for non-destructive evaluation of structural properties of ferromagnetic materials. An EMF due to Barkhausen noise is induced in a coil near the surface or encircling a ferromagnetic material which is subjected to an alternating external magnetic field. MBN measurements were carried out on samples of Non Grain-Oriented (NG0) steel to determine the variation with thickness and silicon content. The results show that the rms value of Barkhausen Noise (BN) amplitude increases with decreasing sample thickness and increasing silicon content. This is explained in terms of eddy current effects which increase with increasing sample thickness and reduce with increasing silicon content. Moving domain walls induce eddy currents in the sample which give rise to effective retarding pressures on the walls which in turn leads to reduced magnetic Barkhausen noise amplitude.
Cluster formation in two-dimensional channel flow of a magnetic fluid under uniform magnetic field
Authors: Nakamura Akihiro , Suzuoka Satoshi , Sawada Tatsuo
Published: December 2018

The two-dimensional channel flow of a magnetic fluid was experimentally investigated. When a magnetic field is applied to a magnetic fluid, ferromagnetic particles aggregate along the direction of the magnetic field and form clusters. The pressure drop of the magnetic fluid flow changes according to cluster formations. The effect of the applied magnetic field on the pressure drop was determined. The ultrasonic propagation velocity was also measured to clarify the effect of cluster formations.
Effect of a uniform magnetic field on magnetorheological fluid under an impact load
Authors: Moroka Yoshitaka , Isnikurniawan Ahmad , Ohba Hiromichi , Sawada Tatsuo
Published: December 2018

We carried out an impact experiment in order to investigate the influence of magnetic field intensity and inner diameter of the orifice on MR fluid motion under an impact load. The experiment was conducted by measuring the piston displacement. From the piston displacement, its velocity and acceleration were calculated.
Study on liquid crystalline flow induced by direct current electric field
Authors: Tsukiji Tetsuhiro , Kodama Kenta , Nishimura Shun
Published: December 2018

A functional fluid flows by itself when electric fields are applied to the functional fluid. This phenomenon is called EHD (electrohydrodynamics) phenomenon, and research and developments are conducted to design motors and pumps using this phenomenon. We use a liquid crystal as a functional fluid and observe the behavior of the liquid crystal as well as flow at the flow channel when steady electric fields are generated through a direct current by two electrodes at the bottom of the flow channel. Moreover, we investigate the influence of the shape and the position of the electrodes on the liquid crystalline flow under the application of the fields. Furthermore, we research the possibility of designing motors using the EHD phenomenon.
Characteristics of Barkhausen noise and permeability on neutron irradiated pure Fe and Fe-Cu alloy
Authors: Kikuchi Hiroaki , Kamada Yasuhiro , Kobayashi Satoru , Echigoya Jyunichi , Watanabe Hideo
Published: December 2018

This paper describes the characteristics of magnetic Barkhausen noise (MBN) and permeability on neutron irradiated Fe and Fe-Cu alloys. The plates made of pure Fe and Fe-1 wt.% Cu alloys were prepared with and without cold-rolling. Those plates were irradiated by neutron with a total fluence of 1× 10 ^{24} n/m ^{2} . Then MBN properties and impedance were measured using magnetic-yokes, a MBN sensor and a pick-up coil. The MBN rms voltage decreases with neutron irradiation, and the impedance increases after irradiation for cold-rolled specimen. On the other hand, the MBN properties and the impedance at lower frequency have no significant changes after irradiation for undeformed specimen. Contrary, the impedance at higher frequency for undeformed Fe-Cu alloy decreases after irradiation. The relations between those magnetic properties and the microstructure of irradiated materials were also discussed. Those results show the potential of nondestructive evaluation for neutron irradiation embrittlement in reactor pressure vessels.
Small size quasi-fractal microstrip antenna M1 EBG-GP
Authors: de Oliveira Elder Eldervitch Carneiro , D'Assunção Adaildo Gomes , Oliviera João Bosco L. , Cabral Alciney Miranda
Published: December 2018

A new patch antenna using the Minkowski fractal curve and Electromagnetic Bandgap structure on plane ground is proposed. The design was based on HFSS and a prototype was built and measured in order to validate the numerical results. A better impedance matching for the device was obtained using the inset-fed technique. The measured return loss for the proposed antenna at the resonant frequency is lower than −15 dB. The M1 EBG-GP antenna resonant frequency is lower than that of a corresponding rectangular inset-fed patch antenna. This results in a reduction of 35.6% for this antenna resonating at 2.45 GHz (ISM band).
Combined electro-thermal analysis of Li-ion batteries applying the finite element method
Authors: Renhart Werner , Magele Christian , Brandstätter H. , Koplenig M. , Scharrer G. , Heubrandtner T. , Prochazka W.
Published: December 2018

The performance of Li-ion batteries under variant operating conditions requires a highly developed battery management. In attaining this a very accurate knowledge of the temperature profile within the cells is of great importance. This contribution deals with the numerical approximation of the temperature behaviour as well as of the heat sources caused by the current flow inside the battery. Thereby a coupled electro-thermal finite element based computation scheme will be applied.
Double antennas for passive long range UHF-band RFID
Authors: Watanabe Kota , Watanabe Yuta , Igarashi Hajime , Waki Hiroshi
Published: December 2018

This paper proposes double antennas which consist of receiver and backscatter antennas for passive long range UHF-band IC (Integrated Circuit) tags. The passive IC tags reply to reader's queries by using backscatter modulation. For this purpose, variable impedance elements are inserted between the antenna and a voltage multiplier which generate dc power. This decreases the efficiency of received power in the voltage multiplier and reduces the communication range. To solve this problem, we propose to use an independent antenna for backscatter modulation. Experimental results and numerical simulation results show that the double antennas successfully reply data from IC tag to the reader.
Magnetostatic analysis by BEM with magnetic double layer as unknown utilizing volume magnetic charge
Authors: Ishibashi Kazuhisa , Andjelic Zoran , Takahashi Yasuhito , Takamatsu Tomoaki , Tsuzaki Kenta , Wakao Shinji , Fujiwara Koji , Ishihara Yoshiyuki
Published: December 2018

The volume integral equation approach replaces magnetic materials with the magnetization in magnetostatic analysis. The concept of magnetic shell relates the magnetization with loop currents. The loop current is equivalent to the magnetic double layer, which gives an integral form of the scalar potential. The nonlinear magnetic field is formulated by regarding the nonlinear magnetization as volume magnetic charges. This paper presents how to utilize the volume charge to solve nonlinear problems. In the case of constant volume element we replace the volume charges with the surface loop currents to derive the nonlinear boundary integral equations having the line and surface loop currents as unknowns. The boundary integral equation is solved iteratively while improving alternately the loop and surface currents.
Multi optimization of high efficiency induction motor considering cost effect
Authors: Han Pil-Wan , Chun Yon-Do , Choi Jae-Hak , Seo Un-Jae , Koo Dae-Yun , Lee Ju , Lee Won-Goo
Published: December 2018

The characteristics of an induction motor vary depending upon the number of parameters and the performance relationship between the parameters is also implicit. In the case of the induction motor design, we should generally estimate the many objective physical quantities in the optimization procedure. In this article, the multi objective design optimization based on a genetic algorithm is applied for a three phase induction motor. The efficiency, starting torque, and material cost are selected as the objectives. The validity of the design results is also clarified by comparison between the calculated results and the measured ones.
Vibration control simulation of an electrodynamic shaker based on an electromagnetic finite element model
Authors: Li Hao , Yang Baokun , Yan Guirong , Hu Junwen
Published: December 2018

A new approach to vibration control simulation for electrodynamic shakers was developed using an electromagnetic finite element method (FEM) model. This approach consisted of two parts. First, the electromagnetic coupling FEM model of the shaker was developed using vibration theory and electromagnetic theory. The electromagnetic force was described using the Maxwell stress tensor, and the electromagnetic field distribution and the dynamic response of the shaker were calculated numerically using FEM. Second, the vibration control simulation system was established: the shaker was described using an electromagnetic FEM model, and the controller was described with an adaptive inverse algorithm. As an example, control simulation of a 1-ton electrodynamic shaker was conducted. The results demonstrate the validity of this approach and provide a basis for the controller design of electrodynamic shakers.
Online magnetic calibration of a cutting edge 9-axis wireless Inertial Measurement Unit
Authors: Bartolomeo Luca , Lin Zhuohua , Sessa Salvatore , Zecca Massimiliano , Ishii Hiroyuki , Takanishi Atsuo
Published: December 2018

In the last years there has been increasing interest on Inertial Measurement Units (IMUs) in several fields, because they can provide a measurement of the orientation, velocity, and acceleration at low cost with high performance. The main reason of the low cost is the possibility to find inertial sensors, as accelerometers, gyroscopes and magnetometers, based on Micro-Electro-Mechanical Systems (MEMS) made by silicon, with further advantages of small dimensions and mass production from the main semiconductor suppliers. In this paper, we present the development of the ultra miniaturized wireless IMU, WB-4 (Waseda Bioinstrumentation number 4), with a 3-axis accelerometer, 3-axis gyroscope and 3-axis magnetometer. Additionally, we illustrate, together with results, the algorithms used for the data filtering and calibration, with particular emphasis on a new methodology for the online calibration of the digital magnetometer.
A comparative study of synchronous reluctance and switched reluctance motors for high-performance fault-tolerant applications
Authors: Bouchareb Ilhem , Bentounsi Amar , Lebaroud Abdesselam
Published: December 2018

In this paper, a new power converter with redundant topology is proposed to compare the fault tolerance capability in terms of the torque density of a 6/4 conventional switched reluctance motor (SRM) and a synchronous reluctance motor (SynRM) that uses an axially laminated rotor. The simulation of the converter is achieved through an equivalent electrical circuit built into the circuit editor, CIRFLU, coupled to the finite elements model (FEM) of the machine using FLUX 2D software package. A numerical approach by FEM allows a finer analysis of the phenomena in transient and non-linear mode. Simulations of various defects were used to compare the performance of two machines for fault-tolerant applications. The theoretical results compared with the experimental ones existing in the literature prove the effectiveness of this study.