bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and calibration of a new biaxial extensometer for radial deformation measurement under hydro-compression loading
Authors: Feng Bo , Xu Minglong , Zhang Zhijun , Lu Tianjian , Chen Zhenmao
Published: December 2018

This paper characterizes a newly designed biaxial extensometer which is capable of measuring radial deformation of circular porous materials under simultaneous hydro-compression loading conditions. The biaxial extensometer sensitivity is calculated using finite-element model, and the calculated sensitivity is verified through experimental calibration. Result shows that the biaxial extensometer responses linearly to an extremely large deformation ranging from −10 mm to 10 mm. Furthermore, it can be reliably operated under high hydrostatic pressure environment.
Quasi-minimum time trajectory planning of electromagnetic attraction transfer robot arm using PTP motions
Authors: Mutsuura Yusuke , Kojima Hiroyuki , Nishikawa Masatoshi
Published: December 2018

In this study, the quasi-minimum time trajectory planning method for the electromagnetic attraction transfer control of a magnetic object by use of a two-joint robot arm with an electromagnetic attraction hand is proposed. In the quasi-minimum time trajectory planning, the trajectory polynomial expression is derived by using the boundary and continuous conditions of joint angle, joint angle velocity, and the trajectory is expressed using three genes of genetic algorithm. Then, using three genes and the genetic algorithm and defining the fitness function for the quasi-minimum time trajectory, the quasi-minimum time trajectory planning algorithm is constructed. The fitness function is defined using two constraint conditions for the allowable maximum moment applied to the magnetic object and allowable rated DC motor torque. Furthermore, the numerical calculations and the experiments are demonstrated, and the usefulness of the present quasi-minimum time trajectory planning method is confirmed.
Magneto-rheological damper control system design
Authors: Lei Lei , Dong Longlei , Yan Guirong
Published: December 2018

Magneto-Rheological material has an intelligent property and been applied widely in engineering field, such as the damper used for the vehicle vibration reduction. Using the MR damper as the actuator, a semi-active suspension control system based on the fuzzy control algorithm is developed in the paper. The performance of the proposed system is evaluated in different applications, such as road detection, communication and local control damping. Besides, combining with the suspension system, the proposed control system can be applied on some special vehicles.
Deployment simulation and comparison of inflatable antenna beam with different folded configurations
Authors: Li Bin , Tan Dewei , Yang Zhichun , Wen Jinpeng
Published: December 2018

The deployment simulation of folded inflatable antenna beam is important to understand inflatable deployment behavior in space environment as well as guiding and improving future packaging and deployment concepts. This paper shows a finite element analyzing method of the deployment motion, which is based on a control volume (CV) approach. The ideal gas law and explicit integral method are used to simulate the deployment process. Three folded configurations, namely Z-folded/coiled/ telescopically-folded configurations are investigated. Furthermore, for Z-folded inflatable beam, the effects of inflation rate and membrane thickness on deployment behavior are discussed. The simulation results show that the main factors to affect the deployment stabilization of inflatable structures are the corresponding folded configuration, inflation rate and membrane thickness.
Study on cushioning characteristics of soft landing airbag with elastic fabric
Authors: Wen Jinpeng , Li Bin , Yang Zhichun
Published: December 2018

Based on the energy conservation principle and thermodynamic equations, an analytical model of soft landing considering the elasticity of airbag fabric was presented. The analytical model was verified by comparing the results with those results from a similar simulation using ls-dyna and our design-oriented model is solved with less calculation time than the finite element method. Then this analytical model was used to investigate the deceleration characteristics of a horizontal cylinder airbags. A series of simulations were conducted to find out the influence of fabric elasticity, initial airbag pressure, and vent size on attenuating properties.
Tracking control of piezoelectric actuator system using inverse hysteresis model
Authors: Chen Yuanseng , Qiu Jinhao , Ji Hongli , Zhu Kongjun
Published: December 2018

The intrinsic hysteresis behavior of piezoelectric material limits the tracking control accuracy of the actuators. This paper describes a tracking control method for piezoelectric actuators based on the combination of feedforward and feedback loops. The hysteresis of piezoelectric actuators is linearized in feedforward loop with an inverse hysteresis model based on a neural network. The number of parameters in the neural network based inverse model is relatively small and the parameters are easy to identify. The feedback loop is used to reduce the accumulated error produced by the inverse hysteresis model. The experimental results show that the accuracy is significantly improved in tracking control by using the combination of feedback and feedforward control.
Active control feasibility analysis of flexible circular truss antenna
Authors: Yang Yi , Yan Guirong , Tang Shan
Published: December 2018

Active control is mainly used in geometry linear structure. In the article, we discuss the feasibility of active control for a geometry nonlinear structure, circular truss antenna. The simulation result shows the maximal active force amplitude and attenuation quotient is related with the effect of decreasing vibration closely. Improper parameters cause the "over-counteract" or "under-counteract" phenomenon in the fixed dominated time interval. In addition, we find proper active control doesn't cause the evident local cable mode in the receiving surface stretched by cables when the initial pre-strain of radial cable is enough.
Effects of compressive residual stress on bending propagation behaviour of fatigue crack
Authors: Ma Youli
Published: December 2018

Testing for bending fatigue crack propagation under mixed-mode condition was carried out using fatigue and annealed slant pre-cracks with different slant angles, β, defined as the angle between loading and crack directions in a rectangular plate. As a result, bending fatigue crack from the fatigue pre-crack with β=45 deg propagated under mixed-mode condition with mode I and II stress intensity factors K_{I} and K_{II} , while bending fatigue cracks from the fatigue pre-crack of β=60 deg and from the annealed pre-cracks with both slant angles of β=60 deg and β=45 deg propagated under mode I crack behavior. Furthermore, the estimated fracture angles calculated by maximum tangential criterion using the stress intensity factors, K_{I} and K_{II} , are in good agreement with the measurement ones except the fatigue pre-crack of β=45 deg at the initial premium propagation. That is to say fatigue crack propagation behavior was effected by compressive residual stress around pre-crack while the slant angle β is smaller (such asβ=45 deg in this study). But the effect was disappeared if β became bigger (such as β= 60 deg.).
Testing of glass-fiber reinforced composite materials using terahertz technique
Authors: Chady Tomasz , Lopato Przemyslaw
Published: December 2018

Terahertz electromagnetic waves become a very useful tool for nondestructive testing of glass-fiber reinforced composite materials. In this paper we deal with detection abilities of defects which may arise in the mentioned structures. Terahertz time domain measurements enable us to gain an information about interior part of multilayered materials. In order to flaws detectability evaluation finite element method simulations were carried out. Numerical analysis was verified by measurements of multilayered reference structures.
Investigation of polishing for inner capillary walls by MCF flow method
Authors: Nishida Hitoshi , Shimada Kunio , Ido Yasushi
Published: December 2018

We investigated the effect of the flow direction of abrasive particles and magnetic clusters on polishing of an inner capillary wall by magnetic compound fluid (MCF) flow. We used an experimental system for polishing inner capillary walls by controlling the MCF flow rate and the rotational speed of the magnetic field. We clarified the relationship between the traces left in the capillary and the flow direction of the abrasive particles and the magnetic clusters, which influences the polishing.
Computational method for microwave absorbing structures with 2-D Kagome lattice grids
Authors: Chen Mingji , Pei Yongmao , Fang Daining
Published: December 2018

Composite lattice grids reinforced by glass fibers and carbon fibers filled with spongy materials can be designed as lightweight microwave absorbing structures (MASs). In the present paper, a computational method for scattering from 2-Dimensional (2-D) Kagome lattice grids has been developed. Reflectivity calculated by this method is in good agreement with the experiment. Microwave absorbing structures with 2-D Kagome lattice grids are predicted to be more efficient than those with square lattice grids in microwave absorbing as well as load bearing.
Analysis of winding disk in transformer under action of axial electromagnetic forces by Green's function approach
Authors: Bakshi Amit , Kulkarni S. V.
Published: December 2018

Dynamic axial displacement of high voltage (HV) winding disk of a power transformer has been calculated by Green's function approach, when time varying axial electromagnetic forces corresponding to worst case of short circuit condition, are applied. An elaborate analysis of the axial electromagnetic forces and corresponding axial displacement of a top-end disk of HV winding is carried out. Under the action of these time varying forces, the winding moves in the axial direction as a function of time between radially placed insulation spacers. Between the spacer supports the winding sections can be considered as clamped-clamped (C-C) beams. Static Green's function of such a beam structure is determined first, and convolving it with axial electromagnetic force determines the axial displacement (bending) at any point on the beam for the purpose of verification of the methodology. Dynamic Green's function of the same winding sector is subsequently derived, which is used to obtain displacement of the winding section by convolving it with an applied time varying axial electromagnetic force. The results are verified with commercial FEM software.
Resonance analysis of a solid state controlled Tesla transformer
Authors: Taşkin Halit , Gürleyük Sırrı Sunay , Saraç Zehra
Published: December 2018

A Tesla transformer is a source that can generate high voltage with high frequency. It is also known a resonance system becomes two air cored coils. Classic Tesla transformer system consists of a high voltage generator which is usually a Neon Sign Transformer (NST), high voltage capacitor and spark gap electrodes. This paper presents mathematical analysis of the equivalent circuit, measure/calculation of its parameters, reasons of resonance, examine of resonance frequencies and a simple solid state driver with a low voltage in the primary side for a Tesla transformer.
Electrical and temperature characterization of NiZn ferrites
Authors: Stojanović Goran , Lečić Nikola , Damnjanović Mirjana , Živanov Ljiljana
Published: December 2018

In this paper we investigate microstructure and electrical properties of NiZn ferrite ring cores and influence of different temperatures on these properties in the wide frequency range from 10 kHz to 1 GHz. Important electrical parameters are analyzed through measuring inductance, impedance and phase angle using LCZ meter HP4277A for lower frequency range (10 kHz–1 MHz) and RF Impedance analyzer HP4191A for higher frequencies (1 MHz–1 GHz). The complex permeability spectra of two ferrite materials, labeled with F14 and F19, has been calculated by means of these measured parameters. It can be concluded that, up to a certain frequency, permeability increases with temperature increase and above that frequency this behavior is opposite. The normalized temperature characteristics of permeability and impedance are also given for analyzed samples.
A microscopic physical approach of nonlinear constitutive behaviors for BaTiO_3 ferroelectric single crystal
Authors: Liu Feng , Zhang Huihui , Chang Fuqing
Published: December 2018

A lot of experiments have proved that the basic reason of the nonlinear and hysteresis constitutive curve in ferroelectric ceramics is domain switching. The microscopic domain switching behaviors of BaTiO _3 single crystals have been studied detailed. The forward and sideway motion of 180° domain wall has been measured by direct stroboscopic observation. The velocity expressions are given. In order to get the evolution equation of the volume fraction of domain switching, a square domain switching model is developed according to the relationship between the domain wall velocity and applied electric field. The model is compared to available experimental data of BaTiO _3 single crystals. It turns out that the model can represent the typical nonlinear electromechanical coupling phenomena. The evolution equation of the volume fraction of domain switching is reasonably consistent with a previous phenomenological model. Furthermore the evolution equation based on microscopic domain motion can further improve the microscopic phenomenological model.
An improved modeling for Collection Efficiency prediction of electrostatic precipitators under the applied magnetic field
Authors: Zhang Jian-Ping , Hu Dan-Mei , Dai Yong-Xia , Ding Quan-Fei
Published: December 2018

This paper describes a strongly coupled calculation procedure for the particle dynamics in electrostatic precipitators (ESP) subjected to the applied magnetic field with the statistical particle size distribution taken into account. The turbulent gas flow and the particle motion under external forces are modeled by using the commercial computational fluid dynamics (CFD) code FLUENT. Numerical calculations for the gas flow are carried out by solving the Reynolds-averaged Navier-Stokes equations and turbulence is modeled using the k − ε turbulence model. An additional source term, which is obtained by solving a coupled system of the electromagnetic field and charge transport equations, is added to the gas flow equation to capture the effect of electromagnetic field. Discrete Phase Model (DPM) is employed to achieve the simulation of the particle phase. Different kinds of particles which follow Rosin-Rammler distribution were simulated under different conditions, and the influence of magnetic field density on the capture of fine particle was investigated. In order to show the dust removal effect, the collection efficiency and the escaped particle size distribution were discussed in case of different applied magnetic fields. The particles trajectories inside the ESP were also given under the effects of both aerodynamic and electromagnetic forces. Numerical results indicate that the collection efficiency increases with the increase of applied magnetic field, that the particles trajectory are more visible to the direction of dust collection plate, and that the collection efficiency varies smoothly when the applied magnetic field is up to a certain value. Furthermore, the average diameter of escaping particles decreases and the dispersion for dust particles in different size increases with applied magnetic field increasing, and particle sizes is linearly decreasing with magnetic field before the particle reaches a certain size.
Active random noise control using adaptive learning rate neural networks with an immune feedback law
Authors: Sasaki Minoru , Kuribayashi Takumi , Ito Satoshi , Inoue Yoshihiro
Published: December 2018

In this paper an active random noise control using adaptive learning rate neural networks with an immune feedback law is presented. The adaptive learning rate strategy increases the learning rate by a small constant if the current partial derivative of the objective function with respect to the weight and the exponential average of the previous derivatives have the same sign, otherwise the learning rate is decreased in proportion to its value. The use of an adaptive learning rate attempts to keep the learning step size as large as possible without inducing oscillation. In the proposed method, because an immune feedback law is changing the learning rate of the neural networks individually and adaptively, it is expected that the neural cost function will reach its minimum rapidly, resulting in a reduced training time. Numerical simulations and experiments of active random noise control with the transfer function of the error path will be performed to validate the convergence properties of the method. Control results show that the adaptive learning rate neural network control structure can outperform linear controllers and conventional neural network controllers for active random noise control.
GA-based stable intelligent control for a class of underactuated mechanical systems
Authors: Liu Diantong , Guo Weiping
Published: December 2018

The nonlinear dynamic model of a class of underactuated mechanical systems (UMSs) in a potential field is built with the Lagrangian method and some system properties are analyzed such as the system passivity. A genetic algorithm (GA) based stable intelligent control algorithm is proposed for the class of UMSs combining fuzzy control and sliding mode control. The real-valued GA is used to adjust the parameters of stable intelligent controller to improve the system performance. The underactuated double-pendulum-type overhead crane(DPTOC) is used to validate the proposed control algorithm. The system is proved to be stabilized asymptotically to its equilibrium with sliding mode theory. Simulation results illustrate the system's complexity and the validity of proposed control algorithm under different conditions.
Neural network based control of a suspension assembly with self-sensing micro-actuator for dual-stage HDD
Authors: Sasaki Minoru , Yamada Hiroyuki , Nam Yoonsu , Ito Satoshi , Inoue Yoshihiro
Published: December 2018

This paper presents a system identification process and control system design of an artificial neural network based suspension assembly with self-sensing micro-actuator for hard disk drives. Artificial neural networks can be used effectively for the identification and control of nonlinear dynamical systems such as flexible micro-actuators and self-sensing systems. Three neural networks are developed for the self-sensing micro-actuator. The first for system identification, the second for inverse modeling for control using the signal from a laser sensor, and the third for inverse modeling for control using the signal from a self-sensing piezoelectric. We also use a neural network inverse model to control the suspension assembly which includes a micro-actuator pair. Simulation and experimental results show that good control performance can be achieved using artificial neural networks.
New residual stress detector using angle resolved Barkhausen noise
Authors: Yamaguchi Katsuhiko , Imae Kazuhito , Nittono Osamu , Takagi Toshiyuki , Yamada Koji
Published: December 2018

A new possibility of residual stress detector is proposed for iron based materials through measurement of angle resolved Barkhausen noise which is known as phenomena of dynamic magnetic process. It is important for keeping safety of our society to early detect metal fatigue, therefore the convenient residual stress detector will be available especially for machines including any robots given heavy loads
Development of rehabilitation training support system of upper limb motor function for personalized rehabilitation
Authors: Uchida Masaki , Morita Yoshifumi , Magasaki Masaya , Ukai Hiroyuki , Matsui Nobuyuki
Published: December 2018

In this paper we propose a new rehabilitation training support system of upper limbs with a teaching/guided function for personalized rehabilitation. The proposed teaching/guided function enables the therapists to easily make training trajectories of the resistance training to suit the individual needs of the patients. It is shown in this paper that two kinds of training programs requested by therapists can be made by using the teaching/guided function. In the algorithm of the teaching/guided function, the impedance control and modification of training trajectory are used. The availability of the teaching/guided function is verified experimentally.
Stiffness analysis and levitation force control of active magnetic bearing for a partially-self-bearing flywheel system
Authors: Zhang Chi , Tseng King Jet , Nguyen Trong Duy , Zhao Guangzhou
Published: December 2018

A compact flywheel energy storage system assisted by axial-flux partially-self-bearing permanent magnet motor has been proposed by the authors. The proposed machine combines axial magnetic bearing and motoring functionality into a single magnetic actuator, which not only spins the rotor-flywheel but also generates a levitation force to overcome the gravity. The mathematical model of the levitation force and stiffness of the active magnetic bearing are developed. The relationships between the stiffness and the key motor parameters are studied. High stiffness can be achieved for the special motor design. The derived force model is validated by finite element analysis. The control system of the levitation force is designed and experimental setup is built. The test results prove the correctness of the mathematical analysis and feasibility of the designed control system.
Modeling printed monopole antenna with coplanar ground-plane by gaussian filter model analysis
Authors: Peng Chia-Mei , Chen I-Fong
Published: December 2018

Based on the Gaussian Filter Model (GFM), an equivalent circuit model that considers the effect of a finite-sized ground plane is presented to estimate the impedance bandwidth of typical printed monopole antenna geometry. The ground-plane is commonly regarded as a low impedance path for returning currents with constant potential across its area. In fact, the finite-size ground-plane of a PCB (Printed circuit board) is not a perfect-ground, it has significant reactance. Therefore, the result of printed ground-plane versus monopole antenna should be regarded as an additional planar radiator rather than a normal ground-plane. The quantitative values of inductance and capacitance of the printed monopole antenna with coplanar ground-plane are addressed thoroughly in this paper. Measured and Ansoft HFSS simulation results are presented to confirm the results obtained using GFM.
Multiplex models for the optimum design of electrical machines
Authors: Brochet Pascal , Yatchev Ivan
Published: December 2018

One promising way to address the problem of the synthesis of the design of electrical machines is to set it up as an optimization problem in order to benefit from the most effective optimization algorithms to solve it. Some consequences are here derived from this statement concerning the modeling of electrical machines, the formalization of the optimization problem and the required algorithms to solve it. They come from different experiments on the design of electrical machine, each one involving a particular methodology, and already reported. This way, a unified approach of multiplex model is proposed. Coupled with adapted multiobjective optimization algorithms it provides a powerful and promising way of designing electrical machines.
Robust design of NMR magnet through worst case analysis
Authors: Ambrisi Angelo , Formisano Alessandro , Martone Raffaele , Yatchev Ivan
Published: December 2018

Magnets for Nuclear Magnetic Resonance applications are designed to provide high level of magnetic flux density in a testing volume with the greatest level of field homogeneity. Anyway, the manufacturing and assembly tolerances cause unavoidable uniformity degradation, that is usually counteracted by correction coils. The measurement of the magnetic field is the final verification of the complex design and fabrication process of a magnetic system, aimed also at defining currents in correction coils to improve uniformity. Anyway, when seeking high accuracy, it is necessary to assess the effect on final uniformity of uncertainties in the measurement technique. In this paper, an approach is presented to assess impact of measurement error bars on final device performance, based on Worst Case Analysis, guaranteeing quick computational time.
Kernel software platform for electrical device optimization: Application to the optimization of a linear actuator performance
Authors: Amdouni Imen , Saadaoui Ramzi , El Amraoui Lilia , Gillon Frédéric , Benrejeb Mohamed , Brochet Pascal , Yatchev Ivan
Published: December 2018

Throughout this paper we are developing a kernel modular extensible platform, allowing new modules addition and optimizing structure's modeled in different design environments with "black box" approach. This platform identifies electrical structure parameters from their design files on which the user define optimizing problem constants and variables. An application is processed; it is an incremental linear actuator where the static force and the overflow of the dynamic response over two successive step displacements are improved by optimizing its design and control parameters.
Nonlinear magnetic method for estimation of wall thinning in carbon steel pipe
Authors: Park Il Han , Chai Jangbom , Kim Young Sun , Baek Myung Ki , Yatchev Ivan
Published: December 2018

This paper proposes a nonlinear magnetic method to estimate the thickness of carbon steel pipe used in the secondary steam cycle of nuclear power plants. The principle of the proposed method is based on utilizing the nonlinear property of magnetic saturation in carbon steel. A magnetic sensor system for the nonlinear magnetic method is designed by the magnetic circuit concept, and is modeled and analyzed with the finite element method and an equivalent electric circuit. The sensor system is built to experimentally test its performance in the estimation of wall thinning. To demonstrate the feasibility and validity of the proposed nonlinear magnetic method, the measured data from the sensor system are used to estimate the wall thinning, and are compared with the analysis results.
Electromagnetic treatment for the inverse reflectance-based shape recovery problem
Authors: Lattarulo Francesco , Amoruso Vitantonio , Yatchev Ivan
Published: December 2018

The value of the time average Poynting vector P _{ave} in resolving some direct and inverse electromagnetic problems at optical frequencies is claimed. The noticed analogy between P _{ave} and electrostatic field on the surface of a rough object, assumed as a perfect conductor, is fruitfully exploited and the usual Lambert law governing diffuse scattering is re-examined. The given theoretical support is especially recommended to unambiguously resolve, in computer graphics, the direct object-rendering problem and to deal appropriately, in computer vision, with the inverse object-recovering problem.
Comparison of axial flux PM synchronous motor and induction motor by mathematical and finite element analysis
Authors: Zhang Chi , Tseng King Jet , Zhao Guangzhou
Published: December 2018

A permanent magnet synchronous motor and an induction motor both having dual air-gap, axial flux configurations have been designed. Both of these two type motors have twin stators and double-side single rotor that is sandwiched between these two stators. On the double surfaces of both disk-type rotors, the permanent magnets are mounted and copper rotor-bars are filled in the slots respectively. The mathematical models of these two type motors have been derived, and the performances of the motors are compared mathematically. Three-dimensional finite element method (FEM) is implemented to analyze the characteristics of these motors and make comparison between them. The analysis results support the feasibility of the motor structures and prove that the PM motor has higher torque density and efficiency when the same dimension is assigned to both motors.
TE scattering by a perfect electromagnetic conducting semi-elliptic-cylindrical boss on a perfectly conducting plane
Authors: Hamid A.K. , Cooray F.R.
Published: December 2018

The problem of scattering of a plane wave from a perfect electromagnetic conducting semi-elliptic-cylindrical boss on an infinite perfectly conducting plane, is solved using the method of separation of variables. The formulation is realized by expressing the incident, reflected, and scattered electromagnetic fields as series expansions in terms of suitable angular and radial Mathieu functions. Imposing boundary conditions at the surface of the boss plus its image on the perfectly conducting plane, allows the unknown scattered field expansion coefficients to be determined in closed form. Results are presented as normalized scattering widths for semi-elliptic-cylindrical bosses of different sizes, shapes, and perfect electromagnetic conducting admittances, to show the effects of these on scattering.
Semi-active vibration suppression by a novel synchronized switch circuit with negative capacitance
Authors: Cheng Jun , Ji Hongli , Qiu Jinhao , Takagi Toshiyuki
Published: December 2018

This paper presents a new synchronized switch circuit for piezoelectric semi-active vibration control. Recently, Synchronized Switching Damping (SSD) controllers have been used to switch piezoelectric materials in order to damp vibration. In contrary to standard active and passive piezoelectric damping, these switching shunt circuits allow a small implementation and require only little power and, moreover, they offer the advantage of self-adaptation with environmental variations and their broadband frequency efficiency. However, the control performance of previous SSD approaches relies on the electrical quality factor of the switch circuit. This paper presents a novel form of the SSD with a negative capacitance, which is to maintain the environmental adaptation and bypass the influence of the quality factor to the damping system. The expression of the vibration attenuation at the resonance frequency is derived, and the effectiveness of this new circuit design is demonstrated by comparing with SSDI and negative capacitance shunt passive control of a resonant cantilever composite beam with embedded piezoelectric patch. Theoretical predictions and experimental results show a remarkable attenuation on the vibration of cantilever beam, which excels the other two techniques.
Transient thickness-shear vibration of a piezoelectric plate of monoclinic crystals
Authors: Liu Nan , Yang Jiashi , Jin Feng
Published: December 2018

We analyze electrically forced, transient thickness-shear vibration of a piezoelectric plate of monoclinic crystals as an acoustic wave resonator. These crystals include the widely used, rotated Y-cut quartz and langasite crystal plate resonators as special cases. A trigonometric series solution is obtained with which a few transient effects in a piezoelectric resonator under a sudden change or fluctuation of the driving voltage amplitude or frequency are calculated and examined. It is found that under a sudden change of the driving voltage amplitude the transition of the resonator vibration takes about 0.1 s for an AT-cut quartz resonator, and that a 10 Hz deviation of the driving frequency from the fundamental resonance causes a significant drop of the vibration amplitude.
Study of fringing effects in multi-cantilever HEMT-based resonant MEMS
Authors: Yamase Ryosuke , Maeda Takao , Khmyrova Irina , Shestakova Elena , Polushkin Evgeny , Kovalchuk Anatoly , Shapoval Sergei
Published: December 2018

An analytical model of a resonant micro-electromechanical system(MEMS) with a high-electron mobility transistor (HEMT)-like structure and an array of resonant cantilevers over its two-dimensional electron gas (2DEG) channel is developed. To account for impact of fringing, spatial distributions of the electric field and sheet electron density at the surface of the HEMT channel are calculated in parametric form. Resistance of the 2DEG channel and frequency-dependent ac amplitude of the source--drain current are derived. The developed model allows evaluation of impact of fringing electric field on output source-drain current for any different number of cantilevers in the array at different spacing between them and can be used for device optimization.
Extraction of parasitic parameter and design of sub-harmonic mixer at 94 GHz
Authors: Zhong Fuqun , Zhang Bo , Fan Yong , Zhao Minghua , Chen Zhe
Published: December 2018

Accompany with the rapid development of millimeter-wave science and technology, sub-harmonically pumped mixers have received more and more attention. One important issue of the mixer is its parasitic parameters of the diode structure play an important role in the conversion loss. Therefore, the influence of parasitic parameter on the performance of the mixer is studied by extraction of parasitic parameter of antiparallel GaAs Schottky diode in this research. Based on the research, a mixer working in the 91–98 GHz band is designed and fabricated based on rogers substrate process. The single side band(SSB) conversion loss is about 8 ∼ 11 dB when pumped with 6mW of local oscillator power and minimum SSB conversion loss of 8 dB is measured at 93 GHz. The measured performance of the proposed mixer is sufficient and robust for the foreseen applications.
Rotor design strategy of interior permanent magnet synchronous motor for fuel cell electric vehicle
Authors: Woo Dong-Kyun , Lim Dong-Kuk , Jung Hyun-Kyo
Published: December 2018

This paper proposes a rotor-design strategy of interior permanent magnet synchronous machine (IPMSM) considering various design constraints for a fuel-cell electric vehicle. The conventional process in the rotor design only considers the magnitude of the iron loss or the magnet loss while neglecting the loss distributions in the rotor core. This approach results in a design where losses are accumulated on a localized region in the rotor core, especially in the case of IPMSM with a fractional number of slots per pole. This can cause significant irreversible demagnetization of the permanent magnets since the rotor core usually suffers from poor heat transfer. The proposed strategy targets this problem by focusing on the loss distributions according to driving condition. In addition, it offers a parallel approach where mechanical stress analysis is combined with the rotor design process in order to guarantee mechanical strength by centrifugal force at maximum speed. The validity of proposed method was verified by comparing simulation result using the finite element method with experimental data.
Quantitative evaluation of information leakage arising from computer
Authors: Zhang Hongxin , Zhang Jinling , Wang Danzhi , Lu Yinghua
Published: December 2018

To quantitatively evaluate the strength of information leakage arising from computer under shielding conditions, a mathematic model is established for information leakage based on near-field measurement results by using the equivalence principle. In order to study the leakage threshold and the shielding performance for information leakage, the notions of Information Identifying Degree, Information Resolution Threshold and Computer Security Defence Distance are formalized respectively. Then, Information Identifying Degree, Information Resolution Threshold and Computer Security Defence Distance are analyzed. So, the strength of information leakage is quantitatively assessed under different shielding levels and distance. The simulation results show that FCC and MIL461C standards are not suitable for the evaluation of information leakage and even strictly standard should be considered. At last, new shielding levels of information leakage are marked off and the shielding effects are assessed by using Information Resolution Threshold. This research aptly provides a quantitative evaluation method for assessing the information leakage strength and presents a means to evaluate information leakage shielding effectiveness of computers.
Probe for detecting weakly interacting magnetic nanoparticles
Authors: Gasparics Antal , Vértesy Gábor , Pávó József , Gyimóthy Szabolcs , Cacciola Matteo
Published: December 2018

Fluxset magnetic sensor based probes with single and double exciting coils have been developed for detecting weakly interacting, low mass and small size magnetic particles. Test measurements were performed on capsules containing 0.15–13.53 mg magnetic iron oxide particles. It was shown that even 0.7 mg of magnetic nanoparticle of size 30 nm could be detected from a distance of 3.5 mm with reliable signal to noise ratio.
Analysis of aircraft magnetic interference
Authors: Wołoszyn Mirosław
Published: December 2018

The magnetometric method is used among other things on mobile platforms (planes, helicopters) in military systems and in geological research. Optically-pumped and SQUID magnetometers are used in magnetic systems on airplanes. To be able to attain the sensitivity of modern magnetometers in flight, it is important that maneuver-related magnetic interference effects be minimized. The mathematical model of an aircraft as a source of magnetic interferences has been known since the early 1950's. Modern computer programs analyzing electromagnetic fields allow us to carry out the analysis of individual sources of aircraft interference. The results of numerical analysis of magnetic interferences of an aircraft model caused by permanent and induced magnetization and by eddy currents, are presented in this paper. The possibility of a significant reduction in an aircraft's magnetic interference by collecting data from more than four cardinal magnetic directions while in flight, is the most important conclusion of these computer simulations.
Applications of multi-frequency inversion algorithm to quantitative NDE of cracks in welding joints of a metallic lattice sandwich plate
Authors: Zhang Dongli , Li Hongmei , Chen Zhenmao , Wang Zhaoba
Published: December 2018

Lattice sandwich metallic plate (LSMP), a new multifunctional material with special advanced mechanical behaviours, has potentials to be applied to many important industries. Defects in welding joints of the LSMP may significantly reduce the material strength. Eddy Current Testing (ECT) is considered as a powerful NDT tool for the detection and sizing of defects in LSMP. The welding zone noises in ECT signals swarm the crack signals and may reduce the reliability of the quantitative defect evaluation. To overcome this difficulty, an inversion algorithm based on the strategy of multi-frequency ECT is proposed in this paper for sizing of welding zone crack. Good consistency of the reconstruction results is obtained for both simulated and measured ECT signals, which proves the validity of the proposed scheme.
Identification of the position of objects in three dimensions using an extended radiography system
Authors: Chlewicki Wojciech , Baniukiewicz Piotr , Chady Tomasz , Brykalski Andrzej
Published: December 2018

Digital radiography is a very useful tool in nondestructive evaluation. However, single radiographic projection contains information about the potential defect only in two dimensions. Thus, the defects may be overlapped or placed parallel to the X-ray beam. We present how a simple, low-cost extension of an existing radiographic system may increase its capability so that it is possible to localize objects in three dimensions. The presented methodology is based on approximate three-dimensional reconstruction from few projections and depth identification procedure. The proposed method also increases detectability of the potential defect.
Reconstruction of damage-induced magnetization with leakage magnetic field signals
Authors: Li Hongmei , Wang Li , Li Yong , Zhang Dongli , Chen Zhenmao
Published: December 2018

The phenomenon of damage-induced magnetization possesses good application prospects in nondestructive testing and material evaluation purpose, once the relationship between the mechanical damage and the induced magnetization can be quantitatively established. As the magnetization can not be measured directly, it is vital to reconstruct the distribution of the magnetization within the materials from the measured magnetic field signals in order to find the correlation. In this paper, an approach has been studied to realize the reconstruction of damage-induced magnetization in a flat plate from the magnetic field signals measured nearby the plate. A deterministic optimization scheme of the steepest descent method has been developed for the inversion in addition with a strategy dealing with the border-effect. Reconstructions with both simulated and measured signals verified the validity and efficiency of the proposed approach.
Finite element model for the characterization of deleterious phases by eddy current technique
Authors: Areiza Maria C.L. , Sacramento Rodrigo , Rebello Joao M.A , Sommer Rubem L. , Gonzalez Diego
Published: December 2018

Avoiding accidents caused by equipment failure and ensuring structure quality are some of the challenges of the petroleum industry. Petroleum exploitation in salt-water has required the use of special materials, such as duplex stainless steels (DSS), that support highly aggressive corrosion conditions and, at the same time, are ductile facilitating equipment manufacture. But DSS can be embrittled when exposed to some heat treatments, such as welding (T > 800 deg). Deleterious phases might precipitated in this material, especially sigma phase(σ), which appears in higher volumetric fraction. This paper presents a proposal of a characterization procedure of deleterious phases in DSS using Eddy Current Technique (EC). A calculus model was elaborated using finite elements. The model was able to reproduce the behavior of this type of steel, and it will help to correctly recognize the signals generated by the material's internal defects.
Frequency sweeping excitation and spectrogram method to evaluate hardened carbon steel
Authors: Matsuda Taisuke , Tsuchida Yuji , Enokizono Masato
Published: December 2018

This paper presents a frequency sweeping excitation and spectrogram method (FSES method) by magnetic sensor for non-destructive testing of hardened carbon steel. High frequency induction heating can make changes in the microstructure and residual stress. As a result, the magnetic properties such as magnetic permeability, magnetic coercivity and remanent magnetization in materials are changed. This makes it possible to evaluate the hardening conditions by using the FSES method. We tried to examine the degree of yield strength which varies with hardened conditions. Controlling and evaluating of yield strength are very important for actual industrial products.
Magnetic field gradient imaging for material classification by magnetic resonance imaging
Authors: Pei Cuixiang , Zhu Haitao , Demachi Kazuyuki , Sekino Masaki , Uesaka Mitsuru
Published: December 2018

In a uniform magnetic field, objects with different magnetic susceptibility may cause magnetic field distortion that can be detected by magnetic resonance imaging (MRI). Conventional MRI techniques focus on magnitude image that shows dark signals at non-uniform magnetic field. However, it is difficult to obtain the magnetic susceptibility information just from the magnitude of signal. A post-processing method is proposed to measure the magnetic field gradient induced by the sample object. Both the polarity and strength of magnetic field gradient can be calculated by this method. The method is proved by MRI experiments with paramagnetic material iron oxide particles at different concentrations, copper, and diamagnetic material graphite.
NDT of polymer nanocomposite for structural applications using electromagnetic techniques
Authors: Bonavolontà C. , Valentino M. , Meola C. , Carlomagno G.M.
Published: December 2018

The CNTs properties have inspired interest in using CNTs as a filler in polymer composite systems to obtain ultra-light structural materials with enhanced electrical, thermal and optical characteristics. In particular, industry recognizes many potential applications such as electrostatically dissipative materials, nano-sensors and aerospace structural materials. In this paper the eddy current based SQUID and the thermographic techniques have been used to study electromagnetic properties of nano-composite materials.
Non-destructive evaluation of pipe wall thinning utilizing long-pulsed magnetic field
Authors: Tsuchida Yuji , Kai Yuichiro , Enokizono Masato
Published: December 2018

In the conventional eddy current testing (ECT), it is difficult to estimate wall thinning from outside of pipes without removing the covered materials due to the large lift-off between a pipe surface and a sensor. In order to overcome this difficulty, a long-pulsed excitation system has been developed with a magnetic sensor, by which the magnetic flux can be penetrated deeply inside pipes because of low frequency and small induced eddy current. In this paper, the numerical results and measured results of the newly developed long-pulsed excitation system are shown. The results show the effectiveness of the proposed long-pulsed method for a large lift-off evaluation to wall thinning.
Time reversal pulsed terahertz inspection of dielectric structures
Authors: Lopato Przemyslaw , Chady Tomasz
Published: December 2018

Nondestructive testing using terahertz frequency electromagnetic waves is becoming increasingly popular method of inspection. Similar operating principle allows the use of inverse algorithms derived from the ultrasonic technique. In this paper algorithm and results of time reversal processing applied to pulsed terahertz inspection of dielectric objects are presented. Time reversal is implemented using finite difference time domain method. New criteria of optimal focusing time are proposed in order to estimate defects positions. Finally the algorithm is verified using the results of simulations and measurements.
Evaluation of contact stimuli by diapers for infants: Relationship between contact stimuli and walking motion
Authors: Nomata Takuya , Okuyama Takeshi , Tanaka Mami
Published: December 2018

This paper describes the investigation of a relationship between contact stimulus and walking movements. Until now, a sensor system for measurement of contact stimulus applied to infants by diapers has been developed. The sensor comprises a polyvinylidene fluoride (PVDF) film and a strain gauge. A dummy infant fitted with the sensor has been designed and built for measuring the contact stimuli during walking movement. Using this system, contact force and diaper friction against the skin are measured as the contact stimuli. The features of obtained data are extracted by performing signal processing in order to investigate the feature of the contact stimuli during the walking movements. From the results of signal processing, time variation of the contact stimuli was obtained. The experimental results show that the feature of contact stimulus in relation to the walking movements can be evaluated.
High speed rotation handpieces applied in dentistry
Authors: Brasil L.M. , Silva J.F. , Rodrigues T.J.M. , Damião K.S.
Published: December 2018

One of the most common elements of the workplace is noise pollution. One of the work environments considered among the nosiest is the dentists' office, since a great variety of the equipment used generates noise. The focus of the present study is the high speed hand-pieces, where it was found that noise from these was responsible for discomfort to professionals in the area of dentistry, and, also, their patients. Thus, the aim of this article is to develop innovations in high speed hand-pieces, so that the level of noise would be reduced, which had satisfactory results.