bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic characteristics of moving-coil geophone with large damping
Authors: Zhang G.H , Hu S.Y.
Published: December 2018

The advantage of geophone with large damping in receiving and compensating high frequency signals is studied theoretically and experimentally. It is found that, as the damping ratio increases, the frequency characteristic of geophone in domain frequency region approximates to the acceleration characteristic gradually, thus the receiving frequency bandwidth of land seismic acquisition is widened and the record of high frequency signals is enhanced. The adopted micro-electronic technology not only increases the geophone damping largely, but also reduces the output impedance of geophone. The in-situ record data by self-designed geophones with large damping demonstrates higher visual frequency and S/N ratio, and stronger spectrum energy. The proposed method is expected to apply to the moving-coil geophone for high resolution seismic exploration.
Influences of magnetic circuit structure of magnetostrictive guided wave transducer on the homogeneity of bias magnetic field
Authors: Song Xiaochun , Jin Zhisheng , Yu Hao
Published: December 2018

The uniform and steady bias magnetic field is the key to improvement of the transduction efficiency for the magnetostrictive guided-wave transducer. To optimize the magnetic circuit of the magnetostrictive transducer and obtain the best detection effects, the method to measure the homogeneity of magnetic flux density by sample standard deviation was studied. And the effects of such parameters as the thickness of the left and right enclosed magnetic conductor shell, the thickness of the outside round shell of magnetic conductor, the distance between the bias magnetic exciting coil and the pipe's outer wall on the homogeneity of the excited bias magnetic field were analyzed quantitatively, both finite element simulation and experimental analysis were conducted to study the effects of different magnetic circuit design schemes on the excited bias magnetic field's homogeneity. The simulation results indicate that the homogeneity of the magnetic field is obviously improved with the above three parameters increasing, and the relatively uniform magnetic field can be obtained when the above parameters are all taken the maximum value of 20∼mm.
Optimal design of auxiliary poles to minimize detent force of permanent magnet linear synchronous motor
Authors: Jin Sang-Min , Zhu Yu-Wu , Lee Sung-Hyung , Cho Yun-Hyun
Published: December 2018

sThe problem in improving the high positioning precision of permanent magnet linear synchronous motor (PMLSM) is the large detent force that is caused by the attraction between the permanent magnet (PM) and the iron core without input current. This detent force can be divided into two components: the slot effect and the end effect. In this paper we propose a novel method to reduce the detent force by employing the optimal designed auxiliary poles. To investigate the characteristics of the detent force of PMLSM with auxiliary poles, the width, position, and height of auxiliary poles are chosen as the optimal factors and the two dimensional (2-D) finite element method (FEM) is used to predict to the values of detent force with different combinations of these three factors. And then the structure of auxiliary poles is optimized by the response surface method (RSM) through the fractional factorial design (FFD). Finally, the effectiveness of our proposed technique is verified by both the numerical calculations and experimental results.
Design of permanent magnet linear synchronous motor with low force pulsations
Authors: Zhu Yu-Wu
Published: December 2018

This paper proposes a novel technique to reduce the detent force in permanent magnet linear synchronous motor (PMLSM) using auxiliary poles. The detent force that is caused by the attraction between the permanent magnet (PM) and the iron core without input current can be divided into two components: the slot effect and the end effect. To reduce these two effects, we analyze the characteristics of the detent force according to semi-closed slot clearance length and auxiliary poles position by using the two-dimensional (2-D) finite element method (FEM). The numerical calculations and the experimental results prove that this proposed technique has a good effect on the reduction of the detent force.
Theoretical and experimental researches on magnetic fluid acceleration sensor
Authors: Yang Wenrong , Yang Qingxin , Yan Rongge , Liu Suzhen , Yan Weili
Published: December 2018

A kind of magnetic fluid acceleration sensor (MFAS) is presented in the paper, which is using the magnetic and fluid characteristic of magnetic fluid. First, the output characteristics of MFAS and its static sensitivity are analyzed based on minimum potential energy principle, the result indicates the linear relationship between output voltage and acceleration. Then, the experimental research is carried out and compared with piezoelectric acceleration sensor simultaneity based on ZJY-601A experiment platform. The output signal of MFAS is sampled and processed by the signal processing system, the output waveform demonstrate that the experimental results are both in agreement with theoretical analysis and output of piezoelectric acceleration sensor. Finally, system errors and influencing factors on measurement sensitivity are analyzed qualitative.
Evaluation of electrical properties of metal-containing amorphous carbon coatings for strain sensor application
Authors: Ohno Takeshi , Takeno Takanori , Miki Hiroyuki , Takagi Toshiyuki
Published: December 2018

The strain properties of the W-DLC coatings were evaluated. W-DLC coatings with various concentrations were prepared by chemical vapor deposition and DC magnetron co-sputtering of a tungsten metal target. Strain was applied to a sample in a four-point bending configuration. The electrical resistance was proportional to the amount of compression and tensile strain, and the gauge factor varied according to the metal concentration. Transmission electron microscope was employed for structure analyses. It was clarified that the structure of the W-DLC was granular. The variation of the resistance under the strain could be explained by a simplified model related to the distance between the clusters. The W-DLC coatings have the potential for strain sensor application.
A rotor design of a BLDC motor used for reciprocating compressor considering demagnetization
Authors: You Yong-Min , Kim Dae-Kyong , Kwon Byung-Il
Published: December 2018

This paper presents the design of a reliable rotor shape of a BLDC motor used for reciprocating compressor considering demagnetization. Three types of rotor shape are proposed for BLDC motor and a proper rotor shape is selected by characteristic analysis using the 2D finite element method (FEM). To verify the accuracy of the analysis results, a prototype was built and tested. In order to design a reliable rotor shape against the demagnetization of the ferrite magnet, the demagnetization analysis is performed according to variation of design variables of the ferrite magnet using the 2D FEM. As a result, the BLDC motor with the developed rotor shape showed good performance to resist partial demagnetization.
Modeling and simulation of open electrical impedance tomography
Authors: Zhang Xiao-Ju , Chen Min-You , He Wei , He Chuan-Hong
Published: December 2018

In order to reduce the error in image reconstruction caused by changeable positions of the electrodes in Closed Electrical Impedance Tomography (CEIT), an Open EIT (OEIT) model was proposed using fixed electrode array. The problem is assumed to be a virtual field by defining certain local sensitive area instead of solving the boundary problem in the whole electromagnetic field strictly. Modeling and simulation of OEIT have been conducted to determine reasonable boundary parameters and electrode array structure. The image was reconstructed by iterative Newton-Raphson algorithm with Tikhonov and Variation regularization. The experiment results showed that OEIT achieved good resolution and positioning accuracy, and can be applied to distinguish small difference in conductivity of the biological tissues.
Phase characteristic of superparamagnetic iron oxide particles in magnetic resonance imaging
Authors: Zhu Haitao , Demachi Kazuyuki
Published: December 2018

Iron concentration is an important parameter for clinical usage of superparamagnetic iron oxide particles. Traditional T _{2} mapping for iron concentration measurement requires several images and long scanning time. This work proposes a method using phase characteristic of magnetic resonance imaging to analyze the magnetic field inhomogeneity caused by superparamagnetic iron oxide particles. Phantom experiments are implemented on 4.7T MRI system. Phase dependence on time of echo and iron concentration is discussed. Results validate the feasibility of measuring superparamagnetic iron oxide particle concentration by phase data at one single scanning.
Analytical solution to the three-dimensional head eit forward problem: Calculation and simulation with a 4-layer spherical volume conductor
Authors: Xu Zheng , Luo Haijun , Wang Junfeng , He Wei
Published: December 2018

A 4-layer concentric spherical model of human head was built to simulate the head EIT forward problem. The layers from outside to inside are scalp, skull, CFS (Cerebrospinal fluid) and brain tissue, respectively. A pair of point current sources placed on the outmost layer is regarded as the boundary condition, and an analytical method of separation of variables was employed to solve the problem. The electric potentials of different current injecting angles were calculated and the equipotential lines were drawn. The simulation results revealed that, the increment of the brain tissue conductivity causes decrease of the magnitude of both real and imaginary parts of the electric potential on the scalp. The frequency property of the model was simulated, when the exciting frequency was increased, the imaginary part of the electric potential increased significantly. These analytical solutions could be used to analyze the head EIT problems and check the numerical solutions calculated from FEM or BEM.
Magnetic excitation of oscillation of magnetically levitated liquid column
Authors: Yamane Ryuichiro , Kinoshita Tetsuya , Park Myeong-Kwan
Published: December 2018

Magnetic levitation of molten metal can be simulated even in weak magnetic field by use of magnetic fluid as a surrounding fluid. The levitated liquid column is desirable to be stable, but it can be deformed or displaced from the equilibrium position. In the present research the disturbance is magnetically given to the liquid column and the excited oscillation is studied experimentally and analytically. The liquid column has inherent natural frequencies, and a kind of resonance occurs at these frequencies, which will lead to the instability.
Magnetic circuit design for magneto-rheological damper
Authors: Luo Jinglin , Yang Baokun , Dong Longlei
Published: December 2018

Magneto-rheological (MR) damper is a smart damping device that can vary its damp with the change of magnetic field. Because of MR damper's exceptional characteristic, it has been widely used in many engineering fields, such as vehicle semi-active suspension control, seismic response reduction, weapon system, and so on. It is no doubt that the key to MR damper is magnetic circuit design. In this paper, a magnetic circuit design for a new structure MR damper (also named as parallel-disks MR damper) is proposed, and the selection of materials, the calculation of coil turns and coil current is discussed. Finally, the design is analyzed with finite element method, and its effectiveness is verified.
Metal core piezoelectric ceramic fiber rosettes for acousto-ultrasonic source localization in plate structures
Authors: Liu Jian , Qiu Jinhao , Chang Weijie , Ji Hongli , Zhu Kongjun
Published: December 2018

This paper presents an approach for acousto-ultrasonic source(passive damage or impact) localization based on metal core piezoelectric fiber(MPF) rosettes. MPF is a new type piezoelectric ceramic device with small size and has high directivity to sense Lamb waves. The response of surface-bonded MPF sensors to Lamb-wave fields is explored theoretically and experimentally. The good directional properties of MPF are used to determine the direction of propagation of the acoustic waves by mounting three MPF sensors in a rosette configuration. Two suitably spaced rosettes are used to locate the source of the ultrasound by taking the intersection of the direction given by each rosette. The performance of the rosettes for source location is validated on an aluminum plate.
Feedforward control of an Ionic Polymer-Metal Composite actuator
Authors: Sasaki Minoru , Onouchi Yusuke , Ozeki Tomohito , Tamagawa Hirohisa , Ito Satoshi
Published: December 2018

This paper presents methods of end point motion control of an Ionic Polymer-Metal Composite actuator. Feedforward control with the inverse system is used. Through frequency analysis of the IPMC, an inverse transfer function is formulated. Validity of the proposed control methods was verified with numerical simulations and experiments. The results show good control performance without disturbance. Feedforward control based on the low-pass inverse system worked quite effectively without disturbance. When subjected to external disturbance, the feedback control performance remains quite good.
Analysis on flow field of piezoelectric pump with unsymmetrical slopes element
Authors: Cheng Wei , Zhang Jianhui , Hu Xiaoqi , Xia Qixiao
Published: December 2018

Traditional valveless piezoelectric pumps are difficult to be minimized for its special tubes installed outside the chamber. Moreover, the effect of mixing different kinds of liquid is not good. In order to improve the configuration and performance of the pump, a novel valveless piezoelectric pump – valveless piezoelectric pump with unsymmetrical slopes elements (USE) is developed. It is designed aimed at intensing the vortex field in the chamber during pumping. The intense vortex field is helpful to stir and mix different liquids in the chamber to produce solution, homogeneous emulsion or turbid liquid. Firstly, pumping principle of the proposed pump is analyzed. Then, numerical models are established, and simulation and numerical calculation on the flow fields in the chambers are carried out.Finally, experiments are implemented to verify the validity and reliability of numerical analysis.
Damping and response characteristics of passive type MR damper
Authors: Murakami Takahiro , Sakai Michiya , Nakano Masami
Published: December 2018

The characteristics of a passive type MR damper were evaluated experimentally. The damper has variable damping characteristics as well as an existing semi-active damper, although it is fully passive device without any sensor, power supply and power controller. A prototype of the damper was manufactured in order to verify the damping and response characteristics. The excitation tests with sinusoidal displacement demonstrate that the damping force changes in response to the sign of the product of the velocity and displacement, which is analogous to one of semi-active control. The base excitation tests with a single-degree-of-freedom system show that the passive type MR damper has excellent damping effect in a wide range of frequency. In particular, the advantage is noticeable at resonance frequency. It is also shown that the base isolation system with the present damper is quite effective in a reduction of the response to earthquake excitation.
Fabrication of copper-nanoparticle embedded in amorphous carbon films and their electrical conductive properties
Authors: Takeno Takanori , Ohno Takeshi , Miki Hiroyuki , Takagi Toshiyuki
Published: December 2018

Electrical conductive properties of copper-carbon composite coatings were investigated. Films of several hundred nanometers were deposited onto dielectric substrates using acetylene-generated plasma and co-sputtering of copper target. Transmission electron microscope was employed for the analyses of the microstructure of the coatings. Temperature dependence of resistance of the investigated coatings was measured by changing the temperature from 80–400 K in vacuum condition. Electrical conductive properties were discussed in terms of the microstructure of the coatings deposited under the various conditions.
Magneto-rheological driving based numerical simulation on colliery hydraulic support directional valve
Authors: Liu Dandan , Zhao Can , Li Huajun , Tang Chunrui
Published: December 2018

Based on application actuality for colliery hydraulic support directional valve, we put forward a magneto-rheological (MR) driving based directional valve. Firstly, accounting of the MR driving mechanism, the frame model of the electro-hydraulic directional control valve is established based on MR fluid, and the feasibility of this new directional valve is expatiated based on the MR driving. Secondly, a mathematical model of the MR valve is established for the numerical simulation. Finally, the computational fluid dynamics (CFD) technique is adopted for the numerical simulation of the inner flow field of the directional valve to obtain the pressure, velocity, and other parameters. Comparing the new directional valve with the traditional one, it has features of simple structure, less moving parts, fast motion response, and high dependability.
Optimization design and dynamic analysis of giant magnetostrictive transducer based on finite element method
Authors: Huang Wenmei , Zhai Li , Wang Bowen , Yang Qingxin
Published: December 2018

An optimization design method of giant magnetostrictive transducer has been proposed based on the circuit theory and system dynamic equation. The method includes three parts. 1) Establishing the equivalent circuit of the transducer's vibration components and educing the dimensions of the transducer components. 2) Based on these dimensions, the distribution of magnetic field in the Terfenol-D was calculated. 3) Using finite element method, the magneto-mechanical coupled dynamic equation was founded and the resonance frequency can be obtained. Calculating and experimental results show that this method can be used to optimise the structure of magnetostrictive transducers in order to transfer the maximal energy.
Analysis on the adhesion of micro-comb structure in MEMS
Authors: Liu Haipeng , Gao Shiqiao , Niu Shaohua , Jin Lei
Published: December 2018

The comb capacitive micromachined gyroscope is a kind of typical MEMS sensor. Electrostatic driving and comb capacitive detection are its typical working mode. Recently, researchers have found that the narrow space between two combs can result in comb adhesion easily because of micro scaling effect. In this paper, some micro forces such as capillary force, Van der Waals force, electrostatic force and Casimir force were analyzed and the relation curves of micro force and its acting distance were obtained. In order to make sure the influences of relative humidity on the micro-combs, a contrast experiment was also carried out. Through analysis on the micro forces, the acting distance curves of micro forces were finally obtained.
A new SVM regression approach for mechanical load identification
Authors: Mao Wentao , Hu Dike , Yan Guirong
Published: December 2018

Most traditional approaches to load identification usually perform not very well because the inverse identification problem in most practical cases is ill-posed. In this paper, a new approach to the identification of dynamic loads based on the solution path algorithm of support vector regression is proposed. A general framework of dynamic load identification using support vector regression is derived and the corresponding identification model using solution path algorithm is established. The results of numerical and experimental tests on cylinder vibration system show that the proposed approach greatly outperforms existing methods, i.e., direct inverse identification method, ε-SVR and LS-SVM, in terms of identification accuracy and numerical stability. As a conclusion, the proposed approach is applicable to a wide variety of mechanical cases.
Identification of sub-surface defect parameters in plates using electromagnetic acoustic interaction
Authors: Nguyen Thanh-Duong , Kojima Fumio
Published: December 2018

This paper proposes a method to identify sub-surface defect parameters in plates, using pulse-echo EMAT modes. First, the proposed method deploys a reduced simulation model to efficiently reduce the computational cost of EMAT forward analysis. Then, an approach of signal processing based on peak values at back-wall echo and POD method applied to extracted feature of EMAT signal are introduced. Finally, inverse analysis based on reduced POD basics is applied for defect parameters identification. Promising experimental results with high accuracy on both simulation and synthetic measurement data demonstrate the capability and effectiveness of the proposed method. The extension of this method can be applied in pipe inspection for defect characterization.
A multi-frequency strategy for reconstruction of deep stress corrosion cracks from ECT signals at multiple liftoffs
Authors: Wang Li , Chen Zhenmao
Published: December 2018

In this paper, a layering analysis scheme for reconstruction of deep Stress Corrosion Cracks (SCC) from ECT signals is proposed based on a strategy of multiple frequency excitation and multiple liftoff in order to improve the sizing accuracy. The shape profiles and conductivity of the crack are reconstructed respectively using a hybrid inversion scheme. The profiles of several cracks are reconstructed from simulated signals of conductive notches and measured signals of an artificial SCC. It is demonstrated that the new strategy is promising for the improvement of the sizing precision of SCC.
Inversion of microwave brightness temperature data for estimating lunar regolith thickness
Authors: Zhou Mingxing , Zhou Jianjiang , Zhang Xiao , Wang Fei
Published: December 2018

The purpose of this paper is to establish a more suitable method for estimating the lunar regolith depth from microwave radiation brightness temperature data of the lunar surface. The physical properties of the lunar surface influencing on the brightness temperature are comprehensively discussed. Considering the variation of these influence factors, an inhomogeneous multi-layer microwave radioactive transfer model is used to inverse the thickness of lunar regolith. By applying fluctuation dissipation theorem, the relationship between the microwave radiation brightness temperature of the lunar regolith and the thickness and temperature of lunar regolith based on this multi-layer model is theoretically deduced. The brightness temperatures of the lunar regolith obtained from Chang'E-1 satellite are simulated on the basis of aforementioned works. An approximate function of inversion is presented. Taking these simulation results with random noise as observation data, an inversion method of the lunar regolith-layer thickness is developed. It indicates that the inverse ability of a certain frequency channel depends on the microwave penetration depth of this frequency channel. The thickness within the penetration depth can be accurately inversed. Using part of the brightness temperature data measured by the microwave radiometer on the Chang'e-1 satellite, the primary result of the lunar regolith thickness distribution is figured out.
Feasibility study of magnetic flux leakage method for condition monitoring of wall thinning on tube
Authors: Kikuchi Hiroaki , Kurisawa Yumi , Ara Katsuyuki , Kamada Yasuhiro , Kobayashi Satoru
Published: December 2018

This paper discusses a feasibility of magnetic flux leakage (MFL) method for estimation of wall thinning on tube in nuclear power plant. A single magnetic yoke is fixed on the specimen, and then a magnetic field sensor scans the leakage field between the yoke legs. The single magnetic yoke with gauss meter fixed at the center of the yoke is also scanned over specimens having a slit. From both FEM analysis and experimental measurement, it is clarified that estimation of the size of slit fabricated in the specimen using profile of leakage field is possible; this indicates monitoring conditions of wall thinning will be possible by MFL method.
An adaptive compression algorithm for pipeline EMAT inspection data
Authors: Huang Songling , Tong Yun , Zhao Wei , Wang Shen
Published: December 2018

Due to the engineering demand of oil and gas pipeline crack inspection, a new ultrasonic method based on non-contact ultrasonic transducer known as EMAT has emerged. Because of the large amount of original waveform data and limited speed and capacity of storing device, research on online data compression is needed. A subsection adaptive compression algorithm based on the features of the inspection data is proposed. The compression precision can be adjusted by altering compression threshold. Compression experiments of 250 kHz EMAT guided wave data are conducted using this algorithm. The results indicate that the algorithm has good quality, and can achieve rather high compression ratio at the same time. A compression ratio around 20:1 can be achieved on sample data. Compression quality evaluation is performed using error sequence and PSNR.
Scaling analysis of magnetic minor hysteresis loops in plastically deformed 304 stainless steel
Authors: Kobayashi Satoru , Kikuchi Nobuhiro , Kikuchi Hiroaki , Kamada Yasuhiro , Echigoya Junichi
Published: December 2018

We have examined scaling rules in magnetic minor hysteresis loops for strain-induced ferromagnetic α'-martensite in 304 stainless steels. The scaling power law between the hysteresis loss and remanence is found to be independent of volume fraction and morphology of martensite. A coefficient of the power law changes depending on size, shape and distribution of martensite. The present method can be a possible technique for integrity assessment of austenitic stainless steels because of the sensitivity and low measurement field.
Material characterization of cast irons with an EMAT/EC dual probe
Authors: Ohtaki Keitaro , Uchimoto Tetsuya , Takagi Toshiyuki
Published: December 2018

Mechanical properties of cast irons strongly depend on the graphite morphology and the matrix structure, thus both of them should be evaluated for their characterization. The former can be evaluated by ultrasonic testing (UT), and the latter can be evaluated by eddy current testing (ECT). Considering the background above, this study proposes a novel method for the material characterization of cast irons with an EMAT/EC dual probe. For this purpose, we conducted UT and ECT for cast irons with different graphite morphology and matrix structures with the present probe. As a result, correlations between the nodularity of graphite and ultrasonic velocity, and between one the pearlite ratio and EC signals were obtained. These results imply that the EMAT/EC dual probe is effective for the material characterization of cast irons.
An experimental research of the effects of stress upon the magnetic domains in magnetic memory testing
Authors: Ren Jilin , Pan Qianghua , Yang Sheng , Chen Chen , Tang Jihong
Published: December 2018

Influenced by the earth magnetic field, indirection of the domain organization and irreversible reorientation will be occurred in internal organization of the loaded ferromagnetic material. The effects of stress on the domains of silicon steel sheet and 0.20% C carbon steel, which had been loaded on the different load, the domains have been observed with the Bitter method. The results show that the silicon steel and 0.20% C carbon steel with the low load or no load, there mainly exist 180 domains, dendritic domains, gladiate domains whose walls are smaller each other in a same crystalline grain, then, with the load enhancing, the domain walls' length and space changed and there exits mazy I domains and mazy II domains, and the number of the mazy domains increase.
3D RFEC simulations for the in-service inspection of steam generator tubes in fast breeder reactors
Authors: Mihalache Ovidiu , Yamaguchi Toshihiko , Ueda Masashi , Miyahara Shinya
Published: December 2018

Three-dimensional numeric simulations, based on the finite element model, are conducted to simulate the In-Service Inspection of magnetic steam generator tubes of a Fast Breeder Reactor using remote field eddy current probes. The influence of sodium in the gap SP-tube and outer defect detectability is computed for a large SP model with multiple SG tubes using the 3D-RFECT code.
Extraction of crack indications from ECT signals using signal phase characteristics of a multi-coil probe
Authors: Yamamoto Toshihiro , Takagi Toshiyuki , Uchimoto Tetsuya
Published: December 2018

This paper proposes a method to reduce noise and extract crack indications from detection signals of a 48-channel ECT system based on its signal phase characteristics. Because this 48-channel ECT system performs two kinds of scanning patterns: U-scan and T-scan, and obtains two sets of signal distributions for one scanning area simultaneously, the proposed method uses a two-stage process that includes so-called main filter and sub filter. Using these two filters imposes more strict conditions on extracting crack indications so as to reduce more noise. The experimental results show that the proposed filtering method is effective to extract only crack indications from detection signals including complicated noises.
Development of contact-type sensor using piezoelectric film for guided wave measurement
Authors: Tanaka Yoshikazu , Tamoto Eiji , Fujimoto Yukio
Published: December 2018

A contact-type sensor using a piezoelectric film for the guided wave measurement is presented in this paper. Because the piezoelectric film has a piezoelectric effect and flexibility, it is thought to be useful for the guided wave inspection. Thus, a contact-type sensor using a piezoelectric film is presented and some experiments are performed. The experimental results show that the contact-type sensor can receive the T(0,1) mode of the guided wave.
Analysis on the relationship between EMAT transmitting efficiency and the electrical conductivity of the coating on material surface
Authors: Zhou Zhenggan , Huang Fengying , Lin Junming
Published: December 2018

The conductive or ferromagnetic material with coating layer can be tested by electromagnetic acoustic transducer (EMAT) without pre-treatment. The electro-acoustic converting occurred on the surface of the specimens is mainly concentrated within the skin depth of the eddy current. Thus, the electromagnetic property of the material surface has great influence on the efficiency of EMAT. The eddy current densities induced in the coating of specimens and Lorentz force are calculated with finite element software ANSYS when EMAT is applied to the 20 steel-based specimens coated with different electrical conductivity materials. With shear wave EMAT, the specimens are tested and the relationship between the amplitude of the first echo wave signal and electrical conductivity of the coating is analysed. The theoretical analysis and experimental results show that under the fixed excitation condition, the higher the electrical conductivity of the coating material, the larger the induced eddy current density and Lorentz force are; the increase of the electrical conductivity of the coating is beneficial to the electromagnetic acoustic excitation and the acquisition of higher voltage amplitudes of the echo waves signals.
Rotating field eddy current (RoFEC)-probe for steam generator inspection
Authors: Lei Naiguang , Udpa Lalita , Udpa Satish , Zeng Zhiwei
Published: December 2018

A novel design of eddy current probe based on rotating magnetic fields is presented for the inspection of steam generator tubes in nuclear power plants. A major advantage of the rotating field probe is that it offers the same functionality as that of a rotating probe coil without the need for mechanical rotation, which in turn translates into higher operating speed. The probe design is also sensitive to cracks of all orientations in the tube wall.
Evaluation of susceptibility to stress corrosion cracking based on non-linear eddy current method
Authors: Oikawa Ryota , Uchimoto Tetsuya , Takagi Toshiyuki , Urayama Ryoichi , Nemoto Yoshiyuki , Takaya Shigeru , Keyakida Satoshi
Published: December 2018

This paper discusses the feasibility of non-linear eddy current method to evaluate material degradations of austenitic stainless steels associated with irradiation assisted stress corrosion cracking (IASCC). For the purpose, tensile tests at elevated temperatures are conducted using model alloys simulating radiation-induced segregation (RIS), and magnetization curves of the tensile test specimens are measured by vibrating sample magnetometer(VSM). Microstructure of magnetization of the tensile test specimens is observed by magnetic force microscopy (MFM). Finally, non-linear eddy current method is carried out for the tensile test specimens. It is shown that the 3rd higher harmonic ratio of the pick-up signal is related to the targeted nominal strain.
Applications of network integrated system with eddy current and ultrasonic testing
Authors: Lin Junming , Li Hanlin
Published: December 2018

Integrated Non-Destructive Testing (NDT) is useful for industrial NDT applications. This paper introduces an integration technique of NDT data based on computer network. Integrated NDT technology increases compactness and performance of inspection instruments. The management and processing of NDT data becomes easier with the help of the integrated NDT method. At the same time, remote control of different on-line instruments is also achieved. Finally, a new type integrating testing equipments named EEC-2008net eddy current and ultrasonic network testing system are briefly introduced.
Application of EMAT/EC dual probe to monitoring of wall thinning in high temperature environment
Authors: Urayama Ryoichi , Uchimoto Tetsuya , Takagi Toshiyuki
Published: December 2018

Eddy current testing (ECT) and ultrasonic testing (UT) have been widely used for the non-destructive testing of metal structures. ECT has a high capability of sizing surface breaking cracks and UT is suitable for sizing sub-surface breaking cracks in thick-wall structures. Based on this background, the authors have proposed a novel dual probe with simple structure combining an electromagnetic acoustic transducer (EMAT) and Eddy current probe. The performance of the probe was verified at room temperature. However, the operating temperature of boiling-water nuclear reactors is 300 degrees C. In this paper, the above dual probe is applied to monitoring of piping wall thinning in a high temperature environment. For this purpose, the structure and components of the probe are discussed so that the present probe should withstand 300 degrees C. Finally, the basic performance of the probe at high temperatures is investigated through an experiment using an electric furnace.
Investigation on metal magnetic memory signal during loading
Authors: Shen Gongtian , Hu Bin , Gao Guangxin , Li Yuntao
Published: December 2018

The dynamic variation of amplitude and gratitude of metal magnetic memory (MMM) signals for a crack on a crane crossbeam was investigated during loading from 0 to 80KN. The result shows that the amplitude and gratitude of MMMT signals slowly increase from 0 to 50KN, quickly increase from 50 to 70KN and rapidly decrease from 70 to 80KN. The crack emerged result in the peak to peak value rapidly increasing and the shape of MMM signals change to sharp. The stress released results in decreasing of the peak to peak of the amplitude and gratitude of MMM signals. MMM testing method can be used to monitor the activity of surface crack or damage in steel structure.
Nondestructive evaluation of neutron irradiation damage on type 316 stainless steel by measurement of magnetic properties
Authors: Takaya Shigeru , Yamagata Ichiro , Ichikawa Shoichi , Nagae Yuji , Aoto Kazumi
Published: December 2018

The relationships between neutron irradiation damage parameters, dose and He content, and the magnetic properties evaluated from the magnetic curves measured by a new developed vibrating sample magnetometer were investigated on type 316 stainless steel. A fast neutron reactor, JOYO, and a thermal neutron reactor, JRR-3, were used for irradiation. In addition to irradiation in each of the reactors, irradiations using the both of them, the coupling irradiation, were also conducted in this study. Irradiation in different reactor and especially the coupling irradiation enabled us to evaluate the effects of dose and He content to the magnetic properties individually in a wide irradiation damage range hardly obtained by irradiation in only one reactor. As the result, it was revealed that the magnetic parameters, especially magnetization at 0.5/μ _{0} A/m and coercive force, have close relationships with dose. Furthermore, the comparison with the result of tensile test showed that these magnetic properties are related to irradiation hardening. On the other hand, any magnetic properties investigated in this study are not dependent on He content. These results show the possibility of nondestructive evaluation of dose and irradiation hardening based on the magnetic properties.
Study on the influencing factors of magnetic memory method
Authors: Hu Bin , Li Luming , Chen Xing , Zhong Liqiang
Published: December 2018

The environmental magnetic field, the stress distribution and the materials are the influencing factors of Magnetic Memory Method (MMM). In order to discover the influencing rule of environmental magnetic field, different even magnetic field is offered during the period of Magnetic Memory (MM) signals occurred. It was found that the environmental magnetic field can change the MM signals magnitude, can not change the curve's profile ordinarily. If the certain magnetic field offered, the curve will be reversed. So, if the environmental magnetic field was changed suitably, the best MM signals will be obtained. Three kinds of materials had been used in experiments to investigate the difference and influencing rule. The result reveals that material is an important role which determines the value of MM signals on condition that the stress and environmental al magnetic field are the same.It was derived from the experimental data that the percent of C influences MM signals in a certain rule but not linear. Those results are different with the existing MMM and improve the MMM evaluation system. The environmental magnetic field function mechanism can be explained by the phenomena of these experiments.
Nonlinear principal resonance of a soft ferromagnetic rectangular plate under a transverse magnetic field
Authors: Xue Chunxia , Zhang Shanyuan , Shu Xuefeng
Published: December 2018

In this paper, a model is presented for a soft ferromagnetic rectangular thin plate which is coupled with a transverse magnetic field and is further under a transverse uniformly distributed load. The four edges of the plate are simply supported. Using the multiple scale method, the amplitude-frequency response equation in steady state is obtained. The amplitude-frequency response curves and the relevant time history curves are given by Matlab programs. Furthermore, the influence of the plate thickness, magnetic field and magnetize coefficient on the vibration behaviour of the system is analyzed.
Influence of excitation voltage waveform on dielectric barrier discharge plasma aerodynamic actuation characteristics
Authors: Jia Min , Song Hui-Min , Li Yinghong , Wu Yun , Liang Hua , Wang Bin
Published: December 2018

Plasma flow control, based on the plasma aerodynamic actuation generated by air discharge, is an active field in aerodynamics due to its potential application in performance improvement of future aircraft. In order to better understand the underlying physical mechanism of plasma flow control, it is important to investigate the relationship between the operating parameters and the plasma aerodynamic actuation characteristics. This paper reports the electrical, optical and mechanical characteristics of surface dielectric barrier discharge plasma aerodynamic actuation excited by microsecond and nanosecond high voltage waveforms. The nanosecond discharge is more diffuser than the microsecond discharge and the discharge current is much larger at the same applied voltage amplitude. The optical emission intensity of the nanosecond discharge plasma is stronger than that of the microsecond discharge plasma, while the rotational and vibrational temperatures of N _{2} in the nanosecond discharge plasma are less. In addition, the relative intensity of the first negative system of N_2^+ (B ^2 Σ _u^+ → X^2 Σ _g^+ ) and the second positive system of N_2 ( C^3 Π _u → B^3 Π _g ) is much less in the nanosecond discharge plasma. The velocity measurements indicate that the air flow induced by the nanosecond discharge plasma aerodynamic actuation is vertical to the dielectric surface, while that induced by the microsecond discharge actuation is parallel to the dielectric surface.
Vibration analysis and motion control of stand-up robot consisting of body link, arm link and leg link
Authors: Kojima Hiroyuki , Hayakawa Tomohisa , Tanaka Takahiro , Kamiyama Ayano
Published: December 2018

In this study, first, the forced vibration response of a three-link stand-up robot is investigated theoretically. The stand-up robot consists of an arm link, a body link and a leg link. Considering the vibration analysis results, the trajectory planning algorithm for the stand-up motion control by using a touch sensor attached to the body link is devised. In the stand-up motion control, initially, the vibrational swing motion control of the arm link starts. Then, immediately after the time when the touch sensor signal is on for the first time, the swing motion control of the leg link starts, and after a brief interval, the vibrational swing motion control of the arm link finishes. Furthermore, the stand-up motion control system consisting of the trajectory planning and the joint angle tracking controller is constructed. Moreover, the experiments of the stand-up motion control have been carried out, and it is confirmed that the stand-up motion control could be well executed.
Advanced control strategy using a compensation of prestressing force in contactors
Authors: Gandanegara Grace , Gualino David , Ladas Dimitrios
Published: December 2018

In order to avoid the noise during the closure of contactors and to improve their electrical performances, we regulate the speed of the contactor mobile part movement. The prestressing force of the pole spring generates a perturbation on the speed when the moving contact touches the fixed contacts. By simulations, we see that a simple speed control is not sufficient. In this paper, we propose a feed-forward control included in the control strategy to compensate the prestressing force.
Establish of the prediction system of chest skin motion with SSA method
Authors: Mizuguchi Akira , Demachi Kazuyuki , Uesaka Mitsuru
Published: December 2018

This paper proposes the method to establish of the prediction system of chest skin motion with SSA method. The Singular Spectrum Analysis (SSA) was applied for the prediction of time series data. A simulation system was developed to predict the location of some points of chest skin during breathing. CCD camera motion capture system (KEYENCE, CV-035C) was used to get the time series data. The prediction results showed good agreement with the measured data and they showed hopeful possibility to realize the chasing radiotherapy technique.
Numerical analyses on influence of damage configuration on vibration parameters for lattice sandwich plate
Authors: Tian Shuxia , Chen Zhenmao , Chen Lingli , Zhang Dongli
Published: December 2018

Though many methods exist for detecting damage in a structure, few of them can be used to identify the debonding defect between the surface and inner layer of a lattice truss sandwich plate. In this paper, a vibration signal based nondestructive testing method using Uniform Load Surface (ULS) curvature is applied to detect the delamination defects of the lattice sandwich plate. The feasibility of the approach is investigated through numerical simulation by using commercial software for different damage configurations. The numerical results show that there is a good possibility to detect delamination defects in the lattice sandwich plate from vibration signals by using the ULS curvature strategy.
Creditability analysis of grounding grid corrosion diagnosis
Authors: Liu Liqiang , Luo Xianjue , Niu Tao
Published: December 2018

In China, the serious accidents due to severe corrosion of substation's grounding grid often take place. To better analyze results of corrosion diagnosis for grounding grids, a novel approach to creditability analysis by means of testability matrix factorization was presented. A new testability matrix was derived, which has only to do with topological structure and test information without any partial derivative operation, and then nonlinear diagnostic equations were established. The branch ambiguity groups and the set of surely testable branches were obtained through the testability matrix by Gauss-Jordan elimination method. The example of simulation shows that the results of the surely testable components are changeless in different diagnosis under fully tested conditions. It points out that misdiagnosis is inevitably due to the existence of ambiguity groups.
A time-variant reliability analysis of steel structures at high temperature
Authors: Wang Zhenqing , Qiao Mu , Han Yulai , Zhu Dalei
Published: December 2018

For the large deterioration of the mechanical properties of steel under high temperature, the resistance of steel members will be largely discounted. The calculations of yield strength and Young's modulus of steel under high temperature recommended by ECCS have been employed in this paper. A simple and feasible time-variant model of the resistance of steel members and a reliability index analysis method of steel structure under fire has been given. An example, which illustrates the action of ISO834 temperature rising curve on the time-variant reliability index of a steel beam have presented. The results showed that the reliability index of a steel beam decreased with the increasing of the fire action time. When the time of fire action exceeds 138 minutes, the reliability index of a steel beam is less than the minimum value stipulated by the norm.
Detection of casting defects on radiogram pictures supported by approximation algorithms
Authors: Chady Tomasz , Napierala Lech , Baniukiewicz Piotr , Sikora Ryszard
Published: December 2018

In this paper a dedicated approach to detection of casting abnormalities on radiogram images is discussed. The case was studied on a specific example of impeller blades and it was shown, that certain features of those blades make approximation approach a natural choice. A method of computation acceleration was also discussed.
Development of partly polished polycrystalline diamond films on steel substrates for slider applications
Authors: Tsutsui Atsushi , Miki Hiroyuki , Takeno Takanori , Takagi Toshiyuki
Published: December 2018

CVD diamond films are expected to become maintenance-free solid lubricant coatings. However, substrates on which diamond film can be deposited have been limited to materials such as silicon and tungsten carbides. If diamond films can be deposited onto steel substrates, it will increase the number of possible applications. Diamond film was deposited on a steel substrate with an interlayer and was partly polished. Tungsten and titanium were selected as materials for the interlayer between diamond film and AISI 440C steel substrate. Low and stable friction coefficients were obtained between diamond film and AISI D2 pin, with friction coefficient 0.1 in the steady-state regime.