bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement of torque characteristics of permanent magnet wind generator by FEM and optimization
Authors: Woo Kyungil , Park Hanseok , Cho Yunhyun , Kim Byungtaek , Kim Daekyong
Published: December 2018

This paper focuses on the improvement of the torque characteristics of the outer rotor direct drive permanent magnet wind generator that is a radial flux machine with output power of low speed and high torque, 3[kW] 90[rpm] by FEM and optimization. The optimization technique is used to find out a design solution through the comparison of cogging torques according to the shape variation such as the open slot width and the pole arc ratio. In this technique the problem is to minimize the objective function. The automatic process that includes the automatic ACAD file drawing and mesh generation with regard to the shape variation is also used. The revised generator is obtained from a preliminary model. The cogging torque characteristics of the revised model and the preliminary model and the dynamic characteristics are analyzed. From the simulation results, it is shown that the cogging torque characteristic of the revised model is better than that of the preliminary one. The prototype was manufactured and the simulation result such as induced voltage is agrees with that of the experimental one.
Torque ripple minimization in a BLDC motor using an improved voltage control method
Authors: Jang Jin-Soek , Kim Ho-Hyun , Kim Byung-Taek
Published: December 2018

This paper proposes a method to reduce the torque ripple of a square wave voltage-driven BLDC motor. First of all, this paper reviews a previous voltage control method to reduce torque ripple, and shows that cogging torque component still remains. Then this paper proposes an improved voltage control method to offset cogging torque. To verify the proposed method, FE-analysis is performed for a test BLDC motor and it is shown that torque ripple is considerably reduced comparing with a previous control.
Attractive and repulsive forces of ferromagnetic materials in time-varying electromagnetic fields
Authors: Cao Ronggang , Fang Zhang , Zou Jun , Yuan Jiansheng
Published: December 2018

Electromagnetic forces of ferromagnetic materials consist of attractive and repulsive components, which can be introduced from the Lorentz force formula and the Kelvin force formula. In harmonic fields, the attractive and the repulsive forces both have DC and AC components and they cancel out with each other to reduce the total average force. The contributions or influences of the frequency, magnetic permeability and electric conductivity of the material to attractive and repulsive forces in time-varying fields are analyzed and simulated by the numerical experiments using FEM methods. Results show that the total time average electromagnetic forces can be reduced greatly, even to zero in certain states, which is useful to control the vibration problem.
Research on dynamic characteristics of giant magnetostrictive acceleration sensors
Authors: Yan Rongge , Yang Qingxin , Yang Wenrong , Hou Shuping , Liu Fugui , Yan Weili
Published: December 2018

This paper studies the dynamic response performance of giant magnetostrictive acceleration sensors. A magneto-mechanical strongly coupled dynamic model is presented, which is calculated by means of the finite element method. According to the proposed model, the time characteristic of the induced voltage for the acceleration sensor built with rare earth giant magnetostrictive alloy is calculated. A comparison between the calculated results and measured ones has been carried out to examine the validity of the proposed dynamic model and the FE implementation. It is found that they are in an agreement. This indicates that the proposed FE model can reflect dynamic response performance of giant magnetostrictive acceleration sensors.
Simulation and optimization of six-stage electromagnetic coilgun
Authors: Guo Liuming , Wang Shuhong , Guo Ningning , Qiu Jie , Zhu Jian Guo , Guo Youguang , Wang Yi , Xu Wei
Published: December 2018

This paper presents a method based on Current Hoop Model for the analysis and design of induction coilgun. The cylindrically symmetric armature is subdivided into concentric hoops with diverse rectangular cross-sections, in each of which the current is assumed to be uniformly distributed. An equivalent analytical model considering mutual coupling of coils and armature hoops is constructed for dynamic simulation of the coilgun. Based on this model, the self- and mutual-inductances of exciting winding and hoops are calculated by Neumann method. The circuit equations are solved coupled with the equation of motion of projectile by using the Treanor method to ensure the convergence. Comparison between the experimental results and the numerical results simulated by Finite Element method (FEM) shows the validity of the presented simulation method for coilgun. The optimization of a six-stage coilgun is achieved by employing the genetic algorithm (GA).
An efficient finite element method for modeling ferrite-core eddy current probe
Authors: Zeng Zhiwei , Udpa Lalita , Udpa Satish S.
Published: December 2018

Three-dimensional simulation of eddy current testing (ECT) using finite element method (FEM) has been studied over the past three decades and various methods have been developed. In these methods, the ferrite-core probe is meshed together with the sample. Hence, simulation of probe scanning requires re-meshing, which is not only cumbersome but also a major source of computational noise. In this paper, we propose a novel FEM for the simulation of ECT with ferrite-core probe in which the meshes of ferrite core and sample are generated separately and the coil is not meshed. The new method avoids re-meshing for different probe positions and is simple, flexible, accurate, and efficient.
The optimal design of a 300∼MJ superconducting magnet using HTS tapes
Authors: Luo Ping , Yao Li-Hai , Yang Shi-You , Ni Guang-Zheng
Published: December 2018

The optimal design of a 300∼MJ superconducting magnet using Bi2223/Ag tapes is studied. The multiple solenoid type is used for the HTS magnet in view of reducing the stray field and structural simplicity. The improved particle swarm optimization algorithm is used to optimize the proposed configuration under constraints such as the fixed storage energy, the volume of the superconductor, the stray field and so on. Finally, finite element method(FEM) is used to validate the storage energy, the magnetic field, the force in a single solenoid and the stress constraint of the optimal structure.
Dependence of equilibrium height of a magnet on initial magnetization process in a high T_c superconducting levitation system
Authors: Zhao Xian-Feng , Zhou You-He
Published: December 2018

The equilibrium height (EH) of a levitated permanent magnet (PM) is investigated in an oscillation system composed of the PM and a high temperature superconductor (HTS). Two kinds of initial quasi-static magnetization processes are performed respectively, and then the EH is achieved after a damped vibration of the PM. A peak value of the EH, associated with a transitional magnetization height (TMH), is found for the first initial process. When the magnetization height (MH) is less than the TMH, the EH increases with the increasing of the MH nonlinearly. Otherwise the EH decreases linearly with the MH. For the second initial magnetization process a minimum value of the EH is also presented. The magnetic energy of the system is believed to be responsible for these two different dependences.
A study of inductance displacement sensor on optical aperture synthesistelescope
Authors: Wang Haitao , Luo Qiufeng , Cai Jiahui , Zhang Yajing , Wan Junwei , Zhu Yongkai , Tian Gui Yun
Published: December 2018

The principle of the inductance displacement sensor on optical aperture synthesis telescope is given with a measurement of mutual inductance to deduce the axial distance. It illustrates an effective modelling and calculation method based on Partial Element Equivalent Circuit (PEEC). PEEC is the method to calculate mutual inductances between coils utilizing partial parameter concept. Simulation for the change of mutual inductances is done which is prepared for the next step work.
Design of high performance line start permanent magnet synchronous motor with high inertia load
Authors: Li Jian , Cho Yunhyun
Published: December 2018

This paper presents the study of a high performance 3-Phase 3.7kW 2-Pole line start permanent magnet synchronous motor for pumping system. A method was proposed to study the starting torque characteristics considering line start with high inertia load. A direct-quadrate model including cage was built to study the synchronization capability. Two-dimensional transient finite element analysis was utilized for accurate calculation of efficiency, starting current speed curve and etc. Structural analysis was also conducted to study the equivalent stress displacement of rotor at rated speed.
Steady state analysis of a new linear actuator with soft magnetic composite material
Authors: Yuan Qi , Ishikawa Takeo , Oono Masafumi
Published: December 2018

In this paper, first the structure and composition of a new linear actuator with Soft Magnetic Composite material is presented. Next we study the simulation model of the linear actuator. By pole-placement design, the state-space model with a full-state feedback control is obtained. The result of simulation is given, and compared with the result of experiment. The results show that the two are basically the same.
The optimum design of a moving PM-type linear motor for resonance operating refrigerant compressor
Authors: Hong Do-Kwan , Woo Byung-Chul , Choi Jae-Hak , Koo Dae-Hyun
Published: December 2018

Moving Permanent Magnet (PM) type Longitudinal Flux Linear Motors(LFLMs) are electromagnetic devices which can develop directly powerful linear motion. This paper deals with an effective analysis of PM-type LFLM by Finite Element Method (FEM) and optimum design for lightweight. This paper presents the statistical optimum design of PM-type LFLM to reduce the weight of a moving PM-type linear actuator with the constraint of avg. thrust force using the penalty method with characteristics function and kriging interpolation method. The contribution and effect of the each design variable on the characteristic function is evaluated by the analysis of means (ANOM) and optimum design set is determined. The generalized reduced gradient (GRG) algorithm is adopted in kriging model. Therefore, it is expected that the proposed optimization procedure using penalty method and kriging interpolation method can be easily utilized to solve the optimization problem with constraint of electric machine.
Periodic vibration analysis of magnetostrictive actuator
Authors: Shang Xinchun , Qin Liping , Wang Fan
Published: December 2018

The periodic vibration of a magnetostrictive actuator is analyzed. The problem is described in mathematical as solving the displacement response of a Terfenol-D rod excited by the input harmonic alternating current. The governing equation and boundary condition include periodically variable coefficient with time. As the magnetoelastic coefficient of Terfenol-D is small, a regular perturbation approach is employed to approximately solve the analytic solution of the problem. The displacement response curves and amplitude-frequency characteristic curves from the presented analytic solution agree well with the numeric solution and the experimental data in reference. The study indicates that the double frequency effect generates in the case of no biasing magnetic field. However for high biasing magnetic field, the output displacement depends in synchronous and linearly on the input current. These features of the solution could provide applicable information for control design of magnetostrictive actuators.
Improvement of capacitor induction motor efficiency by using 3-Dimensional finite element method
Authors: Ishikawa Takeo , Tsuchitani Osamu
Published: December 2018

In this paper, we analyze the steady state characteristics of an experimental capacitor motor by 3-D non-linear FEM coupled with the voltage equation. Next, we propose several methods to improve the motor efficiency by considering the flux density distribution. The motor model where the rotor bars are spread inside can improve the motor efficiency by 4.7%.
Variable magnetic and electric resonances for split-ring resonators as left-handed materials in free space
Authors: Fan Huiqing , Yang Weiwei , Li Chuang
Published: December 2018

Electric and magnetic resonances of split-ring resonators (SRRs) as left-hand materials (LHM) were studied in a free space. Different copper thicknesses were designed to tune the electromagnetic resonance frequencies of SRRs. While the split gap width was varied, double-negative responses in SRRs were investigated in detail. Even both electric and magnetic resonance frequencies became higher as copper thickness was decreased, the electric resonance frequency increased much more higher with the increasing of the split gap width.
A study of magnetic fluid seals for underwater robotic vehicles
Authors: Kim Dae-Young , Bae Hyung-Sub , Park Myeong-Kwan , Yu Son-Cheol , Yun Young-Sool , Cho C. Peter , Yamane Ryuichiro
Published: December 2018

Underwater robotic vehicles (URVs) normally use mechanical seals with o-rings, rubber boots, PTFE or Grafoil wedges, or V-rings. Because mechanical seals can cause an unexpected malfunction, we try to adapt magnetic fluid seal (MFS) for underwater robotic vehicles. For reliable design of the MFS, we use numerical simulation of the flow in the MFS using finite element method. The results obtained from experimental investigations of the operation of the MFS contacting with pressurized water will be compared to numerical simulation results
Design of an SMA embedded clamp for endoscopic surgery
Authors: Zhao Shuang , Luo Yun , Wang Minghui
Published: December 2018

Control of clamping pressure on blood vessel is a commonly concerned issue in minimally invasive surgeries. While complicated sensing-feedback-control systems are developed for clamping in robotic surgeries, a simple mechanism for the pressure control is desired. In this paper, we propose a new structure of endoscopic forceps to solve the problem of nonlinear relation between the clamping pressure and grasping force. A shape memory alloy (SMA) wire embedded endoscopic clamp is proposed to control the clamping pressure within a safe range. A typical configuration of the clamp is designed based on the discussion on the detailed geometric dimension of SMA wires and blood vessels.
A three-axial micro-force sensor based on MEMS technology
Authors: Wang Weizhong , Zhao Yulong , Lin Qijing , Yuan Guoying
Published: December 2018

This paper presents the design, fabrication and characterization of a MEMS three-axial micro-force probe sensor for dimensional metrology of micro object in microcosmic field and micro-force measurement in the field of bio-medical and robot finger. Through analysis of the stress distribution of the sensor by theoretical and ANSYS software, a model of the structure is established and the piezoresistors are doped on the end of the beam to get high sensitivity. The optical fibre probe is design to be ladder structure. The die size of the sensor is 4 × 4 × 5.9 mm ^{3} , and it is fabricated by MEMS technology. Preliminary characterization tests have been performed by means of an experimental test bench, the experiment results indicate that the sensor can test three-axial micro-force in μN scale, and the resolution is up to 3 μN.
A new method of load identification in time domain
Authors: Hu Jie , Zhang Xi-Nong , Xie Shi-Lin
Published: December 2018

The main idea of the paper is to identify the load in time domain through inversely analyzing the Duhamel integral process, a time domain algorithm is developed without tedious theoretical derivation, the simulated results show that the proposed method is effective and of high accuracy.
Inversion approach to predicting the magnetic field distribution based on planar field measurements
Authors: Zhou Guohua , Xiao Changhan , Liu Shengdao , Liu Daming
Published: December 2018

Our goal is to obtain the magnetic field distribution below ferromagnetic hull ships based on planar field measurements. A magnetic inverse model based on equivalent magnetic surface charge was presented to extrapolate the magnetic field at different depths below ferromagnetic hull ships. In order to improve the robustness of the magnetic inverse model, regularization methods were applied to solve the inverse problem. It is shown by a numerical example and a mock-up experiment that the proposed method is satisfying in modeling of ferromagnetic hull magnetism.
Multi-objective design optimization of an inverted-S antenna
Authors: Liu Lei , Lu Junwei , Yang Shiyou , Ni Guangzheng
Published: December 2018

The design of dual-frequency band Inverted-S Antennas (ISA) involves a great deal of tuning works. In this point of view, two optimal methodologies are proposed to synthesis this type of antennas in a more efficient way. The two optimal methodologies, one based on a vector optimizer and the other on scalar optimizer, take advantage of a novel formula to optimize the bandwidths in dual bands. The scalar methodology employs some constraint handling technique to improve its speed of convergence, while the vector methodology without using any preference information strives to accelerate its convergence by means of response surface models. The comparison of numerical results shows the feasibility of the proposed optimal methodology for ISA synthesis. Also, the advantages and limitations of the methodologies are discussed.
Cogging torque reduction of Bldc motor using level set based topology optimization incorporating with triangular finite element
Authors: Meng Xiangjun , Wang Shuhong , Qiu Jie , Zhu Jian Guo , Guo Youguang
Published: December 2018

Cogging torque in permanent-magnet brushless DC (BLDC) motor causes torque and speed ripples, as well as acoustic noise and vibration, especially in low speed and direct drive applications. In this paper, the stator core shape is optimized by using a level set based topology optimization to reduce cogging torque. The level set method can represent the precise boundary shape of structure and also deal with complex topology changes during the optimization process. Different from the conventional rectangular meshes, the level set technique based triangular finite element meshes are presented in this paper to deal with irregular domains. The comparison of cogging torque calculated before and after topology optimization verifies the advantages of the level set topology optimization based on triangular meshes.
Method improvement of EMAT signals simulation and its applications in TBC inspection
Authors: Pei Cuixiang , Chen Zhenmao , Wu Wenjing , Mao Ying
Published: December 2018

In this paper, a code of finite element method is developed for numerical simulation of electromagnetic acoustic testing (EMAT) signals. In order to improve the simulation efficiency of ultrasonic field, a new explicit integration algorithm of time domain is introduced in the simulation code. As an extending application of EMAT to the quality control of Thermal Barrier Coating (TBC), the feasibility of an EMAT transducer, which is proposed for detecting delaminating defect in TBC, is investigated by using the new code.
Numerical analysis of an electromagnetic nondestructive evaluation method for rotating machinery
Authors: Huang Haoyu , Kayata Ryo , Perrin Stephane , Yusa Noritaka , Miya Kenzo
Published: December 2018

A novel electromagnetic nondestructive evaluation (NDE) method was proposed by authors recently. Electromagnetic (EM) sensors, by directly measuring the impeller of a rotating machine, offer a powerful way to detect not only defects on the impeller itself but the state of the condition of the rotation, through the measurement of the displacement of the shaft and the impeller. In this paper, a numerical simulation method using magnetic vector potential and edge based finite element was presented. Simulation results of the EM signals showed good agreement with experimental results of a small water pump. A real canned pump with magnetic casing was considered and numerical results showed that the electromagnetic nondestructive evaluation method is possible to detect the impeller covered by magnetic casing in some instances.
An experimental study of EMAT ultrasonic surface waves modes in railhead
Authors: Lu Chao , Men Ping , Li Lianxiu
Published: December 2018

A lab-based laser-EMAT (Electromagnetic acoustic transducers) system has been developed to observe the ultrasonic surface wave propagation and interaction with surface breaking defects on the sample rail head surface. The frequency-wavenumber dispersion curves of the dominant surface wave modes were determined using 2D-FFT method based on the measurements of the out-of-plane displacement of the surface wave. A complete picture of the ultrasonic surface wave on the sample surface over time was reconstructed with exceptionally high spatial and temporal resolution. Despite the curvature of the rail head, the ultrasonic surface guided wave propagating down the rail is found to have similar properties to Rayleigh waves by direct comparison to those observed on flat samples using the same technique.
The stress-magnetic behavior of ferromagnetic material under cyclic load and geomagnetic field
Authors: Zhang Weimin , Yuan Junjie , Mao Xinyan , Fan Zhang
Published: December 2018

Semisinusoidal loads with constant amplitude or increasing amplitude were applied on steel specimens separately in earth magnetic field. The testing results indicated that the variation degree of the magnetic signals was mostly determined by the amplitude of the applied loads. With the load amplitude increasing to plastic loading stage, zero-crossing of the H_{p} (y) distribution curve occurred and stayed at certain position where the curve has large gradient. The zero-crossing position was exactly the necking point and unchangeable after unloading, which suggested that the plastic failures and microdefects can be identified through testing the H_{p} (y) signals.
Non-destructive evaluation for hardened carbon steel by using frequency sweeping excitation and spectrogram method
Authors: Kai Yuichiro , Tsuchida Yuji , Enokizono Masato
Published: December 2018

This paper presents a frequency sweeping excitation and spectrogram(FSES) method to evaluate hardness and hardening depth of carbon steels by using electromagnetic methods. Magnetic properties of carbon steel samples under different hardening temperature condition are examined by using the FSES method. The results show that the magnetic properties of the hardened carbon steels differ depending on the hardening temperature. It can be said that the FSES method is useful to evaluate the hardening depth and the hardness.
Residual stress caused magnetic field abnormal change upon arc welding joints
Authors: Li Luming , Zhong Liqiang , Chen Xing
Published: December 2018

Residual stress concentration of welding joints is an essential factor to structure safety. It was found that the residual stress could generate a change of magnetic field in arc welding. Things became simple because of the methods based on measuring the distribution of the surface fields and analyzing the relation between the fields and the stress. However, we believe the fact that the magnetizing field caused by electrical current in arc welding has effects can not be ignored. Also, the magnetic field of the Earth is sometimes considered as a critical point in the field's change.

In this paper, experiments were carried out to study the role of arc current by comparing the methods of arc welding and laser welding. The magnetic field was measured upon the welding sites. By controlling the input energy, the residual stress was almost the same. The results obtained from these two welding methods varied. Magnetic fields testing from arc welding specimens were changed more sharply than the laser ones. This means that the magnetic change caused by electrical arc current is important to the surface field. Therefore, by analyzing the status of arc current, electro-magnetic methods can be used as non-destructive testing tool of the arc welding joints merely by testing the surface magnetic field without specific magnetization.
Simulation of an improved operating method for vacuum circuit breakers with permanent magnetic actuators
Authors: Wang Zhenxing , Yan Peng , Geng Yingsan , Yu Li
Published: December 2018

One disadvantage of traditional permanent magnetic actuators (PMA) in vacuum circuit breakers (VCB) is that it is difficult to improve the velocity characteristics so that the interruption capacity of VCBs will be constrained. The objective of this paper is to propose a method for controlling PMAs to enhance the velocity characteristics. In contrast to the traditional control method that adopts only one coil in an opening or closing operation, the new method adopts both coils in the PMA simultaneously and controls the direction of the current in coils. Then a simulation model that involves coupled physical fields is constructed according to the new method. Moreover, the simulation results indicate that the initial velocity can be increased in the opening operation and the velocity characteristics in the closing operation can be optimized. In addition, the operating current can be reduced so that it is easy to control. Finally, experimental results validate the simulation results.
An effect of vertical sloshing on a fluid pressure and a surface displacement in a tuned magnetic fluid damper
Authors: Ohno Ken-ichi , Sawada Tatsuo
Published: December 2018

A tuned fluid damper (TLD) is a dynamic absorber which uses hydrodynamic force of sloshing in a container to dampen oscillations of structures. The TLD using a magnetic fluid as working fluid is called a tuned magnetic fluid damper (TMFD). Sloshing of the magnetic fluid is controlled by the magnetic field on the TMFD. It is important to get the state of the sloshing, thus the change of the fluid level and the fluid pressure of the magnetic fluid is studied in several magnetic fields. The change of them is affected by the resonant sloshing of vertical component and not by the resonance of the main (horizontal) sloshing.
Experimental study for the magnetic intensity distribution and the electronic thrust of APGD plasma
Authors: Shen Jinming , Huang Yinyang , Pan Bo , Lin Qi
Published: December 2018

This paper presents the measurement of the magnetic field distribution and electronic thrust of atmospheric pressure glow discharge(APGD) plasma at flat panel. The characteristics of APGD plasma and its some mechanism problems have been investigated from a new point of view. The distribution of the magnetic intensity around the APGD low-temperature plasma and its electronic thrust were measured respectively. The results show that the directional airflow induced by APGD plasma is related to the distribution of the magnetic field, and the electronic thrust of APGD plasma is influenced by the structure of the APGD plasma actuators. The experimental study is significant for the further study about the characteristics of APGD low-temperature plasma.
Damper based on electromagnetic shunt damping method
Authors: Wang Pengpeng , Zhang Xinong
Published: December 2018

This paper investigates vibration control via electromagnetic shunt damping. A new damper based on electromagnetic shunt damping is designed, and mathematical model of the damper is developed to obtain the equivalent damping coefficient. Simulation of the vibration control of a SDOF system is conducted. Results of the simulation reveal that the new electromagnetic shunt damper can greatly attenuate vibration transmitted to structures.
An application of the parametrization of all multi-period repetitive controllers for reduction of rotational unevenness in motors
Authors: Yamada Kou , Hagiwara Takaaki , Ando Yoshinori , Murakami Iwanori , Nakazawa Nobuaki , Liu Jia Wei , Sakanushi Tatsuya
Published: December 2018

Multi-period repetitive controllers were proposed by Gotou et al., in order to improve the disturbance attenuation characteristic of modified repetitive control systems. Recently, the parametrization of all stabilizing multi-period repetitive controllers was obtained. Since the parametrization of all stabilizing multi-period repetitive controllers was obtained, we can express previous studies of multi-period repetitive controllers in a uniform manner. In addition, a multi-period repetitive controller can be designed systematically. However, an application of control system using the parametrization of all stabilizing multi-period repetitive controllers has not examined yet. In this paper, we show the effectiveness of the control system using the parametrization of all stabilizing multi-period repetitive controllers for reduction of rotational unevenness in motors.
A project aiming at the enhancement of NDT{\&}E of stress corrosion cracking
Authors: Yusa Noritaka , Miya Kenzo , Komura Ichiro , Chen Zhenmao
Published: December 2018

This paper introduces a research project the authors have proposed. The project aims to gather non-destructive testing data of stress corrosion cracking specimens and present them as benchmark data freely available to researchers in the field. Round-robin test using seven austenitic stainless steel plate specimens with artificial stress corrosion cracking is carried out, and they are measured using various non-destructive testing methods. The data measured are made available together with the results of destructive tests to confirm the true profile of the cracking.
Robotic earthworm using electro-conjugate fluid
Authors: Tokida Kenichiro , Takemura Kenjiro , Yokota Shinichi , Edamura Kazuya
Published: December 2018

This study develops a novel robotic earthworm using electro-conjugate fluid (ECF), which generates a jet flow with high DC voltage. The robot, inside of which is filled up with ECF, has two ECF jet generators sandwiched with three flexible silicone rubber tubes (all components are located in series). When applying an appropriate electrical input to each jet generator, the robot generates a peristaltic motion, which may push the body forward. The robot is 60 mm long with the diameter of 6 mm. The experimental results confirm the robot moves in a � 6.5 mm acrylic resin pipe with 0.13 mm/s.
Efficiency measurement of linear oscillation motor with gas load
Authors: Zou Huiming , Zhang Liqin , Peng Guohong , Tian Changqing
Published: December 2018

Linear oscillation motor (LOM) is the key assembly for a linear compressor, and its efficiency has great impact on the integral compressor performance. This paper presents a novel gas load method to measure the efficiency of LOM, analyses the effects of some main factors on the LOM efficiency in theory, and shows the efficiency test results. Different load conditions can be simulated by adjusting the discharge pressure of the gas and the load force presents nonlinear periodical curve. In the experiment, we changed the syntonic springs of the tested LOM to measure the LOM efficiency on different work conditions. The results of both theoretical analysis and experiment show that the LOM efficiency is the highest when the phase angle between current and displacement is 90°. While the springs stiffness coefficient is 54.44N/mm, the highest efficiency of the tested LOM is 85.97% on the condition that the discharge pressure is 0.25MPa. While the springs stiffness coefficient is 44.64N/mm the highest efficiency of the tested LOM is 84.67% on the condition that the discharge pressure is 0.4MPa. While the springs stiffness coefficient is 38.4N/mm the highest efficiency of the tested LOM is 78.35% on the condition that the discharge pressure is 0.5MPa.
Closed form solution for a line inclusion in magnetoelectroelastic media
Authors: Wang B.L. , Hoffman M.
Published: December 2018

This paper studies the problem of a line inclusion in a medium possessing coupled piezoelectric, piezomagnetic and magnetoelectric effects. Based on the extended Stroh formalism, the general two-dimensional solutions to the magnetoelectroelastic problem are obtained, involving five analytic functions of different variables. The magnetic, electric and elastic fields around the inclusion are given. Expressions of the stresses, electric field and magnetic field in the vicinity of the inclusion tip are derived and the field intensity factors are provided. The energy release rate is written in terms of those field intensity factors. Solutions for some special cases, including the electrically and/or magnetically insulated/conductive inclusions/cracks, are also established. Explicit algebraic results are given for a special case of an anti-plane crack in a magnetoelectroelastic medium.
Diffraction of electromagnetic plane wave from a PEMC strip
Authors: Imran Amjad , Naqvi Q.A. , Hongo K.
Published: December 2018

In this paper, diffracting behavior of a perfectly electromagnetic conductor (PEMC) strip has been studied. Both the E- and H-polarization are considered. The method of analysis is Kobayashi Potential (KP). Imposition of boundary conditions results into dual integral equations (DIEs). These DIEs are solved by using the discontinuous properties of Weber-Schafheitlin's integral. The resulting expressions, finally, reduce to matrix equations with infinite number of unknowns whose elements are expressed in terms of infinite integrals. These integrals are hard to solve analytically so numerical simulation is done. Illustrative computations are presented for different parameters of interest especially the dependence of co-polarized and cross-polarized components on the admittance parameter.
Performance of a constant-stress piezoelectric generator for battery-less remote control/switch
Authors: Kan Junwu , Wang Shuyun , Wen Jianming , Cheng Guangming , Zeng Ping , Fu Xiaoqing
Published: December 2018

This paper introduced a novel constant-stress piezoelectric cantilever generator (CSPCG) for human-powered battery-less remote controls(switches). The CSPCG consists of a piezoelectric monomorph cantilever and a deflection-limiting device (DLD). The DLD was designed to be a circular arc to shape the bended cantilever and yield constant strain through length. Considering the energy converting ability and reliability, the DLD's radius was figured out as a function of working stress and thickness of the piezoelectric plate and substrate plate. Contrasted with a deflection-free piezoelectric cantilever generator (DFPCG), the energy performance of the CSPCG was evaluated. Research results show that the two generators share the same optimal thickness ratio for them to achieve the maximal electric energy output. When the same stress and end-deflection were provided, the electric-energy generation of the CSPCG is above 4 and 1.5 times that of the DFPCG, respectively. While, the stress and end-deflection of the CSPCG is only 0.49 and 0.77 times that of the DFCPG when equal electric energy is generated. This suggests that a CSPCG with a DLD can enhance energy-generating capability and reliability, or decrease end-displacement of piezoelectric cantilever. A CSPCG was fabricated and used to power a low-power remote-control circuit at one-push excitation.
A theoretical analysis of FGM doubly curved shallow thin shell based on physical neutral surface
Authors: Zhang Da-Guang , Zhou You-He
Published: December 2018

In this paper, a new theory about functionally gradient materials(FGM) is constructed from the concept of physical neutral surface and classical double curved shallow thin shell theory (CDSST). In this theory, there is no stretching-bending coupling effect in constitutive equations, governing equations and boundary conditions have the simple forms as those of CDSST about homogeneous isotropic materials, so the solution procedure is as easy as homogeneous isotropic shell. Using this new theory, linear bending and vibration solutions are presented using analytical method and a nonlinear bending approximate solution is given out using Galerkin variational method. This new theory about FGM has more merits in engineering applications, because it is easier and simpler than any of geometric middle surface FGM double curved shallow shell theories.
Improvement of performance of Electromagnetic welding process by use of driver materials
Authors: Desai S.V. , Kumar Satendra , Satyamurthy P. , Chakravartty J.K. , Chakravarthy D.P.
Published: December 2018

In Electromagnetic Welding process, the electromagnetic parameters govern the welding process. The collision velocity is the crucial parameter that decides the quality of the weld joint. The EMW process is comparatively less efficient for low electrical conductivity metals. However, the efficiency of the process can be improved by using high electrical conductivity metals, such as copper, aluminum (named as `drivers') which are placed adjacent to the job piece. In this paper, the performance of different driver materials is analyzed. This exercise is important from the point of view of minimization of input energy. The computation of the collision velocity is carried out by commercial software's. The results are verified with experimental observations. The job pieces chosen are flat strips of aluminum, copper and S.S. Needless to say, the conclusions drawn are applicable to any other geometry. Since the EM forming process precedes the EMW process, the conclusions are also applicable in the case of the former process.
Dynamic admittance matrix of metal core piezoelectric fiber
Authors: Yixiang Bian , Jinhao Qiu
Published: December 2018

The metal core piezoelectric fiber (MPF) is one of the new type piezoelectric devices for sensors and actuators. To investigate the dynamic characteristics of a cantilever MPF, the dynamic admittance matrix is established. It can describe the response of a cantilever MPF subjected to driving parameters, a harmonically varying axial force F at the tip and a harmonically varying voltage V on the electrodes. The responses parameters of a cantilever MPF, including a dynamic tip elongation δ and a dynamic electric charge Q, can be obtained using the vibration theory and the average distributed electrical charge method. The response parameters are related to the driving parameters by a 2 × 2 matrix. The dynamic models for measuring piezoelectric parameters of a MPF are given in order to illustrate the applications of the previous dynamic admittance matrix. The piezoelectric parameters, the elastic coefficient s_{11}^E , the piezoelectric coefficient d_{31} and the dielectric constantε _{33}^T of MPF were measured experimentally.
Design and analysis of 5 kw class tubular type linear generator for free-piston engine
Authors: Lim Jaewon , Hong Sun-Ki , Jung Hyun-Kyo
Published: December 2018

This paper presents the development of a 5kw class tubular type linear generator. The two main characteristics of the generator, the back EMF and the cogging force, are calculated using the finite element method. To reduce the cogging force, the pole pitch modulation method and dummy teeth are adopted. The designed machine is simulated and manufactured for verification.
Thrust and normal force characteristics analysis of linear synchronous motor for direct drive conveyer
Authors: Zhu Yu-wu , Lee Sang-geon , Cho Yun-hyun
Published: December 2018

The problem in improving the high positioning precision of permanent magnet linear synchronous motor (PMLSM) for direct drive conveyer is the large detent force, which contains two components: one is the cogging force caused by the interaction between the permanent magnet (PM) and the iron core, the other is the end effect caused by the finite mover length. In this paper a force compensator in the field oriented control (FOC) algorithm is employed to reduce this detent force, thus the thrust and the normal force characteristics analyses of PMLSM are of the most importance. First the characteristics of the thrust and the normal force are simulated by finite element method (FEM), and the relation of the thrust and the normal force to the q-axis current is analyzed. Then the components of detent force are defined by Fourier series using the curve fitting method, and compensated by injecting the instantaneous currents using the FOC method. Finally the dynamic characteristics of this PMLSM for direct drive conveyer are investigated, and the numerical results are reported to validate the effectiveness of this proposed method.
Analysis of human arm characteristics in cooperative motion using the eddy current sensor based on musculoskeletal model
Authors: Wang Yuanxin , Ikeura Ryojun , Zhang Nan , Sawai Hideki , Hayakawa Soichiro
Published: December 2018

Human characteristics are supposed to be applied to the control systems of the human-friendly robots. Therefore, it is important to know the human characteristics in human-robot cooperative tasks. In this study, we considered a single rotational degree of freedom experimental system as well as a mass-spring-damper-friction dynamic model for the human arm, measured the torque acting on the armload from subject's forearm and the angular displacement of subject's forearm using the force sensor and the eddy current sensor, analyzed their mutual relation, and attained the characteristics of the human arm with the effect of the gravity load. We compared this cooperative motion to that studied without the gravity load and found that the damping and friction characteristics remained unchanged and the spring characteristics disappeared. In this case, the characteristics of the follower's arm had no relationship with the weight of the load.
Finite element modelling and robust control of fast trilayer polypyrrole bending actuators
Authors: Moghadam Amir Ali Amiri , Torabi Keivan , Moavenian Majid
Published: December 2018

Conjugated polymer actuators can be employed to achieve micro scale precision positioning, having a wide range of application including biomimetic robots, and biomedical devices. They can operate with low voltage while producing large displacement, in comparison to robotic joints, they do not have friction or backlash, but on the other hand, they have complicated electro-chemo-mechanical dynamics, which makes accurate and robust control of the actuator difficult. There has been extensive research on modeling the electrochemical dynamics of polypyrrole bending actuators. However the mechanical dynamics modeling of actuator remains to be unexplored. In this paper finite element modeling and robust control of fast trilayer polypyrrole bending actuators is proposed. In the modeling part the infinite-dimensional admittance model of actuator will be replaced with a family of linear uncertain transfer functions based on Golubev Method. Further model development will take into account the proper mechanical dynamics, which is essential, when using fast conducting polymer actuators. The purposed modeling approach will be validated based on the existing experimental data. In the controlling part the robust control QFT will be applied to control the highly uncertain dynamics of the conjugated polymer actuators while the actuator carrying variable tip loadings. Finally the analysis of design shows that QFT controller has consistent and robust tracking performance.
Frequency domain analysis of tesla transformer as a coupled second order system
Authors: Gürleyük Sırrı Sunay , Öztürk Ertan , Taşkın Halit
Published: December 2018

This paper presents the frequency domain analysis of a Tesla transformer system to obtain relationship between the frequency of an input square wave and the induced output voltage. This system has two coils coupled to each other via air. Resistances, inductances and parasitic capacitances make the coils a coupled second order dynamical system when the primary is fed by a square wave. Mathematical analysis bases on the transfer function written in frequency domain. The solution aims to determine the frequencies in which the Tesla Transformer generates high output voltage. A comparison between the calculated and measured results shows the validity of the proposed approach.
Misalignment fault analysis and diagnosis in switched reluctance motor
Authors: Torkaman H. , Afjei E. , Ravaud R. , Lemarquand G.
Published: December 2018

The magnetic characteristics of a Switched Reluctance Motor (SRM) in normal and abnormal conditions are important in performance prediction and verification of the motor. In this paper, a novel view of air gap magnetic field analysis of SRM under rotor misalignment is presented. This analysis is based on a three-dimensional finite element method (FEM) to provide the precise fault diagnosis. This method is used to simulate reliable and precise model by considering the end effects as well as axial fringing effects. The FE analysis are performed to obtain the static magnetic characteristics of SRM including flux linkages, terminal inductance and static torque profile under different rotor positions for varying degree of misalignments. To do so, Fourier analysis is carried out to study the variations of diagnosis index. Inductance waveforms were analyzed by FFT, and the concept of relative spectral coefficient from the FFT analysis is given as a fault diagnosis index, and its sensitivity to SRM misalignment fault is shown under different conditions. The obtained results present useful information with regard to the detection as well as the amount of misalignment fault. To the best knowledge of the authors, such an analysis has not been carried out previously.
Optimization procedure for high homogeneity field systems design
Authors: Cvetković Zlata , Perić Mirjana , Vučković Ana Mladenović , Yatchev Ivan
Published: December 2018

Two different approaches for homogeneous electrical field generation are presented in this paper. For this generation a primary cell which consists of toroidal electrodes is used. Potential distribution along the system axis is expanded into Taylor and Chebyshev series in the first approach. System dimensions are chosen by setting corresponding terms to zero value so that only linear term remains. In the second approach the synthesis of systems with axial potential linear distribution is performed. Optimization of the electrodes parameters was carried out using gradient method. A deviation of electric field intensity is used as a criterion of the level of obtained homogeneity.
Fast defect parameter estimation based on magnetic flux leakage measurements with GMR sensors
Authors: Reimund Verena , Blome Mark , Pelkner Matthias , Kreutzbruck Marc , Yatchev Ivan
Published: December 2018

We present a fast inverse scheme that is capable of simultaneously estimating the parameters depth, opening and length for rectangular 3D geometries of surface-breaking defects. The parameter estimation is realized by an iterative least-squares minimization using the trust-region reflective algorithm. A semi-analytic magnetic dipole model that allows the sensor characteristics to be incorporated is used for predicting the stray magnetic fields. Giant magneto-resistance (GMR) measurements were carried out on a test specimen that includes a series of artificial defects. For the estimation of the defect depths relative errors between 0.6% and 15.9% have been obtained. Due to its very low computational costs, the inverse scheme can suitably be employed in automated production environments.