bluuebunny/crossref_metadata_2025 huggingface dataset:
Approaches to prove the rotor of the permanent magnet machine must be outside in order to improve the energy conversion process
Authors: El-Kharashi Eyhab
Published: December 2018

Most of the electrical machines designed to have their stators on the outside and their rotors on the inside. However, it was noticed that the shaft fills a relatively high volume inside the machine without producing any torque. That means there is a wasted volume within the machine and this volume does not produce any torque. From this point of view, there are some trends in designing and building electrical machines to have their rotors outside the machine and their stators inside the machine. Here the example used for the machines using those designs is the permanent magnet (PM) machine, which is an electrical machines designed by the two different methods, inner and outer rotors to be used in many applications such as wind turbines and electric vehicle wheel motors. This paper is dedicated to prove that the external rotor permanent magnet machine is preferred for some significant reasons. The paper uses two approaches to demonstrate that. The first approach is using the geometrical volume of each machine to compare the torque capabilities in case of two possible topologies of the PM machines. The second approach is to compare the PM machine with another type of electrical machine, that has the same magnetic circuit topology and the rotor can be inside and outside as well.
Limiting factors of the response time of the magnetorheological damper
Authors: Strecker Z. , Roupec J. , Mazůrek I. , Klapka M.
Published: December 2018

Magnetorheological dampers seem to be suitable for the adaptive car suspension systems. For proper operation of the semi-active algorithms(skyhook, groundhook), the force response of the damper must be fast enough. In this paper, the response time of the Delphi vehicle MR damper is examined and the sources of the overall force time response on the control voltage are discussed. One of the main sources of the response time seems to be electro-magnetic circuit of the MR damper. A principle of an optimal controller for reducing response of the coil's current on the control voltage is designed. However, the measured overall force time response with fast current controller was not reduced as expected. Therefore, a FEM simulation of the magnetic circuit was made. It shows that after an optimization of the current controller, eddy currents in the coil's core cause long time response and therefore they are the limiting factor of the response time of the MR damper. These simulations were verified by the measurements and some recommendations about improving the pistons construction are given at the end.
Compact printed ultra-wideband antenna with two notched stop bands for WiMAX and WLAN
Authors: Sharma M.M. , Deegwal J.K. , Govil M.C. , Kumar Ashok
Published: December 2018

A compact printed ultra-wideband (UWB) antenna with two notched stop bands is analyzed and presented. By introducing a unit complementary split ring resonator (CSRR) in the beveled edges of radiating patch, two sharp notches are achieved at frequencies of 3.5 and 5.8 GHz. The proposed antenna has been fabricated and experimentally tested. A good agreement between simulated and measured results has been observed. Measured impedance bandwidth of the tested antenna is 3.12–12 GHz, which covers bandwidth requirement of UWB frequency band, for VSWR < 2 and also has two notched stop bands of 3.39–3.90 and 5.52–6.44 GHz, for VSWR > 2, for rejecting WiMAX and WLAN band signals, respectively. In addition, the effect of the dimensions of the CSRR on the two stop bands is also analyzed. The radiation pattern and gain characteristics of the proposed configuration are studied and the results are exhibited accordingly.
Characterization of light flash signatures using optical-fiber pyrometer detectors during hypervelocity impact
Authors: Tang Enling , Shi Xiaohan , Zhang Qingming , Wang Meng , Wang Di , Xiang Shenghai , Liu Shuhua , Xia Jin , He Liping , Han Yafei
Published: December 2018

Impact light flash is an intense light flash released when a target is impacted by a hypervelocity projectile. Light flash is caused by emissions from a jet of shocked material which is thrown from the impact site. Impact light flash phenomenology is now being considered for applications where remote diagnostics are required to observe and diagnose impacts on satellites and spacecraft. Additionally, this phenomena and remote diagnostics are under consideration for deep space exploration and missile defense applications. Currently, optical signatures created from hypervelocity impact can be utilized as the basis for detectors (spectrometers, pyrometers), which characterize the material composition and temperature. To establish this capability technically in the laboratory, we have conducted a series of experiments on a two-stage light gas gun at impact velocities ranging from 1.96 to 4.21 km/s. The focus of this work is to develop a flash signatures collected methods for use as a reliable light flash, and late time radiating evolution to characterize material behavior in the shocked and expanding state; ascertain scaling of light flash with impact velocity, and determine the temperature of the impact flash resulting from radiating emissions when photomultiplier tube (PMT) are used in conjunction with narrow band pass filtering at specific wavelengths as a pyrometer. The results of these experiments are discussed in detail using natural dolomite target.
A new spiral frequency reconfigurable antenna with RF-MEMS switches for mobile RF front end
Authors: Chawla Paras , Khanna Rajesh
Published: December 2018

The full-wave analyses and design of a multiband reconfigurable antenna (MRA) using radio frequency microelectromechanical system (RF MEMS) switches is presented for 1.0–10.0 GHz band. Integration of spiral antenna and MEMS switches on a conventional FR4 printed circuit board(ε _r = 4.4 and tanδ=0.002) is designed. This paper also gives the construction and performance of low loss MEMS resistive switches and further describes the important improvements in the construction of the switches. The RF switches used here exhibit very good RF characteristics with typical values of pull-in voltages lies between 3.5 to 20.25 V. The cantilever beam structure of Design-3 switch offers pull-in voltage as low as 3.5 V at air gap g_0= 0.5 μm. Further, Design-1 switch have insertion losses lower than 0.39 dB in ON position, and isolation of"Design-2" switch as high as 79.83 dB in OFF position. As compared to all presented switches the "Design-3" switch has optimized displacement time response i.e. 2 ms. The effect of optimized "Design-3" switch is than study along with spiral antenna. The overall arm length of spiral is changed by activating and deactivating the three "Design-3" switches and consequently its frequency reconfigured. Finally, optimization procedure using quasi Newton method is introduced for characterizing antenna by changing slot length. The wide bandwidth ranging from 200 MHz to 1.65 GHz at different multiband of proposed MRA indicates device contribution in enhancing the mobile TV and internet application speed.
Rotor fault detection algorithm based on a new fault indicator for induction motors fed from an industrial frequency inverter
Authors: Sahraoui Mohamed , Ghoggal Adel , Zouzou Salah Eddine , Guedidi Salim
Published: December 2018

This paper proposes an improved rotor fault detection algorithm. The main objects are: First, ameliorate the reliability of the rotor fault detection task especially under very low load in the presence of industrial frequency inverter. Second, allow even relatively unskilled users to make an automatic, fast and reliable decision on machine health with low requirements. Basing on the concept of multiple signature processing, the proposed algorithm uses Relative Harmonic Indexes (RHI) as a new fault indicator. The RHI are computed starting from many harmonics selected carefully according to their sensitivity to the occurrence of rotor bar faults, this represents its main advantage compared to the classical fault indicators which use only one or two fault signatures leading commonly to erroneous diagnosis especially under low load. The proposed algorithm requires only the stator current signal. For each data acquisition, the algorithm computes, normalises and classifies the RHI then it displays the obtained results in a simple manner. Extensive experimental tests, carried out on a 3 kW squirrel cage induction motor fed from an industrial frequency inverter, confirm the effectiveness of the proposed algorithm in detecting of rotor bar fault under different operation conditions even with very low loads.
Steering law for a cluster of magnetically suspended momentum wheels with vernier gimballing capability
Authors: Peng Cong , Fang Jiancheng , Wang Chun'e
Published: December 2018

This paper focuses on the steering law for a magnetically suspended momentum wheel (MSMW) cluster with vernier gimballing capability. Firstly, the dynamical model of the spacecraft equipped with the MSMW cluster is constructed in a generalized form. Then a new steering law for the MSMW cluster is proposed to switch between two operation modes: the conventional momentum wheel mode for outputting spin torque, and the double gimbaled wheel mode for outputting the gyroscopic torques. Compared with the traditional steering law, the proposed steering law with two modes switch can avoid the small vernier gimbal angles saturation. Finally, simulation results demonstrate the merits of using vernier gimballing capability and the effectiveness of the proposed steering law in providing the command torques and avoiding the saturation of the vernier gimbal angles.
The verification of force exerted on robotic capsule looped by magnet ring
Authors: Yang Wan'an , Zhao Xin , Hu Chao , Qin Fengqing
Published: December 2018

In order to actively maneuver the robotic capsule and make it small to swallow easily, we propose that the capsule incorporating the circuits, batteries, imaging device, etc. is looped by a magnet ring with 1 mm thickness. Another cuboidal or cylindrical permanent magnet attracts or pushes or rotates the robotic capsule to make closer scrutiny for the interesting area. Before designing the control system, the force regarding distance between cuboidal or cylindrical magnet and magnet ring should be known in advance. The mathematic model of magnetic force that the cuboidal or cylindrical permanent magnet exerts on the magnet ring is given for that purpose. The experiments state that the force the robotic capsule requires can be produced by cuboidal or cylindrical magnet when it's moving forward in the pig's small bowel. The experiments also show the relationships between the force and the shape of cuboidal magnet or cylindrical magnet, which can help to choose the magnets with optimal dimensions.
Design of microwave active integrator using Z-transform technique
Authors: Tsai Yi-Hsien , Hsue Ching-Wen , Chen I-Fong
Published: December 2018

In this paper, a discrete-time domain synthesizing method was presented to design and implement the active integrator in the microwave frequency range. The frequency-domain GaAs Filed Effect Transistor (FET) scattering parameters are converted into the Z-domain representations. The transfer functions of the networks are formulated in the Z domain and implemented by using cascade serial line and GaAS FET. There are good agreement between the experimental results and the theoretical values.
Theoretical analysis of a circular cylindrical piezoelectric transformer with attached masses
Authors: Jiang Shunong , Du Jinlong
Published: December 2018

Attached masses are utilized in this work to improve the performance of circular cylindrical piezoelectric transformers operating in thickness-shear mode. An exact solution based on the linear theory of piezoelectricity is obtained to verify the concept. The transforming ratio, displacement and stress fields of the transformer are investigated. Numerical results based on the theoretical analysis show the noticeable influences of the attached masses on the behavior of the transformer. The desirable load impedance for a high transforming ratio is also obtained in this study.
Time-step program for the sub-cell FDTD modeling of apertures with finite depth
Authors: Xu Chunhua , Deng Zhengdong , Xiong Run , Deng Feifan
Published: December 2018

When using sub-cell algorithms to model the coupling of apertures with finite depth in the finite-difference time-domain (FDTD) method, time-step size is required to be reduced to avoid instability. In this work, a time-step program is proposed for the stable modeling of apertures with finite depth using sub-cell algorithms. A sub-cell area related time-step reduction coefficient is introduced to ease the steady reduction of the time-step size firstly. Then a modified algorithm is given for sub-cells whose area is extremely distorted. Numerical results demonstrate that the proposed time-step program is an accurate and stable modeling of aperture coupling without resulting in significant time-step reduction.
Recovery analysis of spark gap by anode temperature decay method for different materials
Authors: Reddy C.S. , Sharma A. , Mittal K.C.
Published: December 2018

The recovery in a spark gap for repetitive switching has been a long research interest. The surface temperature variation of the anode during switching plays decisive role in recovery of spark gap. This paper presents a method to estimate the effect of anode temperature rise and decay on repetition rate of spark gap. By using this method, the behavior of copper and stainless steel materials were studied for a current pulse of 30 kA. During the pulse period of 10 μs, the temperature rise for SS is higher than Copper. After current zero, the anode temperature decays to the vaporization temperature of the material and determines the recovery time of the spark gap. This temperature decay is also verified by a heat transient computational model developed in FEM based software. Simulations has been carried out for different materials including Cu and SS. Some simulations are in good agreement with existing experimental data. The decay time for current pulses 5 kA, 10 kA, 15 kA, 20 kA, 25 kA and 30 kA are estimated. The simulation shows higher decay rate for tungsten and lower decay rate for graphite. Similar trend has been observed for silver and copper. Theoretical analysis of recovery times, heat transfer simulation model for different anode materials are presented and the results are discussed.
Investigation on microwave dielectric materials for dielectric resonator antennas
Authors: Kumar Jitendra , Gupta Navneet
Published: December 2018

In this paper, a theoretical and practical investigation on microwave dielectric materials for wideband dielectric resonator antennas(DRAs) is presented. Due to the variety of materials available to antenna designers, a proper technique to select the best possible material is required. In this paper Ashby's material selection methodology is used for dielectric material based antenna systems. Four primary performance indices, impedance bandwidth (BW), the size of the antenna (λ), radiation efficiency (η) and resonance frequency( f_{0} ), are used to obtain the desired performance. The selection chart shows that Roger TMM10, (ε _{r} = 9.8) is the most suitable material followed by "Roger's TMM10i and RO3010" for DRAs to provide the best performance for wideband applications. Performances of antenna are verified with rectangular and hybrid design of DRA in terms of reflection coefficients, radiation pattern, gain and efficiency. Theoretical work is compared with the simulation and the close agreement between the two, confirm the validity of this study.
Optimization analysis of Electromagnetic Linear Actuator's radial array permanent magnets
Authors: Dai Jianguo , Chang Siqin , Liu Liang
Published: December 2018

This paper presents the research on a problem which is difficult to implement in the actual magnetization process of Electromagnetic Linear Actuator (ELA)'s permanent magnets radially magnetized. Given magnetic field symmetry and assembly feasibility, it creatively puts forward four parallel magnetized-permanent magnets joint schemes (PM-PMs Joint Schemes) of the ELA. On the basis of mathematical modeling and simulating calculation, further study on the comparison of magnetic field effects and ELA's performance in different joint schemes is accomplished. Then, through the Analytic Hierarchy Process(AHP), 8 parallel magnetized-permanent magnets joint model (8 PM-PMs Joint Model) is determined as the best choice after optimizing selection. Further, the 8 PM-PMs Joint Scheme is trial-produced and its air gap flux density and electromagnetic force are also tested. Compared with simulating calculation, the maximum error from test result is within 4.3%, verifying the accuracy of mathematic model and simulating calculation.
The wire traction microgripper design and experiments for stereo light microscope
Authors: Wang Yuezong , Ma Guodong , Zhang Chenchen
Published: December 2018

An electromagnetic-driven microgripper is designed for the automatic process of gripping micro-coil wire under the guidance of Stereo Light Microscope (SLM) visual system. The diameter of the wire is about 50–70 μm. Stress analyze with the ANSYS simulation software helps to obtain stress and safety factor contours of the upper and lower clamp arm when the microgripper grips wires. Simulation results show the correctness and reliability of the design. The microgripper clamping force is up to 0.9 N by theoretical calculation. Test results show that this gripper achieves a displacement of 1.1 mm. Functional test for the wire traction microgripper has been done under the guidance of SLM visual system. The wire traction microgripper is placed in three-dimensional platform, and the three-dimensional platform moves microgripper in the SLM object space close to the clamped object. Positioning accuracy error is determined by repeated positioning precision experiments on three-dimensional platform by the laser displacement sensor. Automatic process of gripping the micro-coil wire is observed and recorded in the SLM visual system to verify performance of the microgripper structure design.
An active microfluidic mixer utilizing a hybrid gradient magnetic field
Authors: Cao Quanliang , Han Xiaotao , Li Liang
Published: December 2018

A simple active microfluidic mixing system based on magnetic actuation strategy of fluids in the microchannel under a hybrid gradient magnetic field was proposed. The hybrid magnetic field, combined of a static gradient magnetic field and an external AC uniform magnetic field, is specially designed to generate periodic magnetic body forces acting on the mixed fluids. Two-dimensional numerical simulation has been performed to investigate the mixing behavior caused by the interactions of magnetic field, fluid flow and convection-diffusion. Numerical results show that the proposed mixer system achieved up to 97% mixing of the two fluids with a small current flowing in micromagnets.
Bifurcation and chaos analysis of a nonlinear electromechanical coupling transmission system driven by AC asynchronous motor
Authors: Liu Shuang , Li Xue , Zhao Shuangshuang , Li Haibin
Published: December 2018

Considering the torsional vibration in transmission system driven by AC asynchronous motor, this paper proposes a dynamical model of nonlinear electromechanical coupling system by using the energy method. The effect of electromagnetic factors on nonlinear dynamic performance of the electromechanical coupling system is investigated. Firstly, the static bifurcation characteristic under the non-autonomous condition is studied based on the singularity theory of nonlinear system. Secondly, the Hopf bifurcation point and the direction of bifurcation are determined based on the Hopf bifurcation theory. Finally, the bifurcation diagram, Poincare map and the largest Lyapunov exponent are given, which show the influence of electromagnetic stiffness and electromagnetic damping on the chaotic motions of the system.
Use of electromagnetic induced flow fluctuations in a nanofluidic-assisted cooling device
Authors: Su Jen-Pao , Wu Jong-Shinn , Lee Ya-Wei
Published: December 2018

In this study, an electromagnetically controlled cooling device(ECCD) is proposed, employing magnetic nanofluid (MNF) and electromagnetohydrodynamics to ameliorate the waste-heat dissipation of mechatronic systems. The MNF was charged in a condenser chamber as an auxiliary coolant, and was prepared from fine ferromagnetic particles of iron ferrite by using a chemical coprecipitation technique. A radial basis function neural network-based training model was employed for examining the electromagnetic resonance of the ECCD at a wide heating range. Satisfactory agreement between the experimental and predicted results indicated the accuracy of the model in capturing the ECCD dynamics. The nonlinearity of ECCD dynamics were also identified as a feature of frequency resonance by mapping a discrete-time model into generalized frequency response functions (GFRFs). Accordingly, the effect of electromagnetic induction relating to ECCD performance can be further confirmed.
Tunable filter using defect in one-dimensional plasma photonic crystals
Authors: Shi Jia-Ming , Yuan Zhong-Cai
Published: December 2018

The filter properties of the electromagnetic wave in one-dimensional plasma photonic crystals with defects, which consist of unmagnetized plasmas and microwave lossy dielectrics (MLDs), were studied by the Finite Difference Time Domain (FDTD) method in this paper. The results were presented that the thickness, the plasma angular frequency, and the dielectric relative permittivity in the defect layer can influence the filter properties in the plasma photonic crystals. As a possible application, the transmission and filter characteristics of the plasma photonic crystal under incident high power wave were discussed.
An infrasonic vibration energy harvester using pendulum impact
Authors: Cui Xiaobin , Hu Junhui
Published: December 2018

This paper presents experiments and finite element (FE) analyses of an infrasonic vibration energy harvesting device in which a low-frequency pendulum impacts a cantilever beam type energy harvester. The experiments demonstrate that the energy harvester operates in the frequency range of 2∼8 Hz and has output power of several microwatts under 0.1 g excitation acceleration. Moreover, a finite element model with a coupling of impact, vibration, piezoelectricity and circuit is established and used to analyze the output voltage and power. The frequency response characteristics at different pendulum lengths and the distances between the pendulum ball and cantilever beams are measured and calculated, respectively. Useful guidelines for designing the energy harvester are obtained.
Optimal design of short-armature slotted type multi-segment permanent magnet linear synchronous motor for numerically controlled machine tool
Authors: Xi Neng , Yang Jia-Jun
Published: December 2018

The severe drawback of slotted permanent magnet linear synchronous motor (PMLSM) is the detent force, particularly when accurate positioning and constant low speed is required for numerically controlled machine tool. In this paper, a novel short-armature slotted type multi-segment permanent magnet linear synchronous motor (MSPMLSM) is proposed and constructed to reduce the detent force. It consists of a proper shift of the multiple segments of iron core relative to the PMs. The detent forces of MSPMLSMs with different number of segment are analyzed and simulated by finite element method (FEM). The proposed structure has been proved to be a very effective approach for the reduction of detent force. Then this paper presents the statistical and mathematical optimum design of a 3-segment PMLSM using response surface methodology (RSM) together with FEM to minimize the detent force. Full factorial design and steepest ascent method, one of the iterative search method, is proposed to establish optimal design area for applying RSM. Finally, the global optimal design is predicted and the optimally designed one is manufactured, and the numerical results and measured results are reported to validate the effectiveness of this proposed method.
LLC resonance power transformers using magnetoplated wire
Authors: Bu Yinggang , Nishiyama Masahiro , Yamamoto Tatsuya , Mizuno Tsutomu , Tsuchiya Shigeaki
Published: December 2018

The use of magneto-plated wire (MPW) allows for reduction of winding loss component from the proximity effect. compared with a copper wire (COW). A MPW is a COW with a circumference that is plated with a magnetic thin film. In this paper, we clarify the basic characteristics and the efficiency characteristics of a transformer using a MPW and a COW. We found that the resistances of a primary coil made of COW and MPW at a frequency f=500 kHz are 1.56 Ω and 1.12 Ω, respectively, and decreased 28%. The short circuit inductances of the COW and the MPW at a frequency f=500 kHz are 26 μH and 29.6 μH, respectively, and increased 13.8%. The efficiencies of an LLC resonant converter using the COW and the MPW at a frequency f=500 kHz are 90.2% and 92.2%, respectively, and increased 2%.
Design and finite element analysis of a new structure brushless wound field synchronous motor
Authors: Hu Kun , He Fengyou
Published: December 2018

Traditional synchronous motor system has complicated structure and is difficult to maintain. In view of the mentioned problem, this paper aims to propose a new structure brushless synchronous motor where AC exciter and synchronous motor using the same core. Two concentric single-phase winding grooves are cut on stator and rotor respectively, with the stator single-phase field winding laying in the stator single-phase winding groove, and the rotor AC induction winding laying in the rotor single-phase winding groove. The AC power from AC exciter is rectified by the rotating rectifier for the DC field winding. The results of the proposed structural design and FEA of the new structure brushless wound field synchronous motor show that the new structure is simple in structure, low in loss, high in efficiency and promising in its future application.
Design of tunable and dual/multi-band metamaterial based perfect microwave absorber
Authors: Dincer Furkan , Karaaslan Muharrem , Unal Emin , Sabah Cumali
Published: December 2018

Tunable and multi-band metamaterial (MTM) based perfect microwave absorber (MA) is designed, implemented, and characterized. Firstly, dual-band MA with has two distinct resonances is investigated both numerically and experimentally which is also tested according the incident angle and polarization independencies. Then, the modified versions of MA are investigated and compared with respect to their absorbance, mechanical tunability, and multi-band characters. As a result, the suggested MAs with perfect absorption(including incident angle and polarization independencies) display good performance among their counterparts and can be used in myriad potential applications such as high frequency and sensor applications which are also presented.
Characteristics of a nonlinear rotating piezoelectric energy harvester under variable rotating speeds
Authors: Guo Bin , Chen Zhongsheng , Cheng Congcong , Yang Yongmin
Published: December 2018

This paper presents a nonlinear rotating vibration energy harvester by employing a piezoelectric cantilever beam and a nonlinear magnetic force due to a pair of magnets. A mathematical model is derived for the nonlinear rotating harvester based on the Lagrange's equation and the assumed-mode method, where piezoelectric coupling behavior is also included. From the model, the potential function of the nonlinear rotating harvester is firstly studied. Then its output characteristics under rotating speeds varying linearly and nonlinearly with time are carefully examined, respectively. The effects of the distance between the two magnets, the sweep rate, the sweep direction and the growth rate of the rotating speed on the output characteristics are investigated numerically. The simulation results reveal that all these parameters have strong influences on characteristics of the rotating harvester. When an optimal distance is achieved, a nonlinear rotating energy harvester is fit for low frequency and variable rotating motion more than a linear one. All conclusions will provide guidelines for designing nonlinear rotating vibration energy harvesters.
Spatial dynamics modeling of the secondary arcs with power transmission lines
Authors: Cong Haoxi , Li Qingmin , Chen Quan , Xing Jinyuan
Published: December 2018

Secondary arc is a complicated and critical physical phenomenon with power transmission lines. An arc chain model was employed with a view to establish the governing velocity equations, in which the multiple forces impacts upon each element were specifically incorporated including electromagnetic force, wind load, air resistance and thermal buoyancy. Based on the proposed model for secondary arc dynamics, simulations were then carried out and further validated through physical experiments on a test platform, which showed good coincidence between the two. The research can provide fundamentals for understanding the physical nature especially the extinction mechanism of secondary arcs, and lays theoretical basis for optimal design of the transmission lines' auto-reclosing strategy.
Semi-active vibration control of an aircraft panel using synchronized switch damping method
Authors: Ji Hongli , Qiu Jinhao , Nie Hong , Cheng Li
Published: December 2018

With the rapid development of the aerospace industry, the control of aircraft structural vibration becomes increasingly important. Semi-active vibration control method based on synchronized switch damping have been attracted more attention due to its robustness compared with passive approaches and simplicity compared with active approaches. In this paper, three SSD semi-active control methods combined with a modal observer were applied to multimodal vibration suppression of an aircraft panel with stiffeners, and their effectiveness was verified by experimental results. A state observer was built based on the experimentally identified state-space model of the panel. Modal displacement of the panel was identified on line using the state observer and used in switch control of different piezoelectric actuators. Since the vibration characteristics of the panel with stiffeners was very complicated and its natural frequencies were distributed densely, use of the identified modal displacement as the reference signal for voltage switching in SSDI, SSDV and SSDNC improved the control effect for some specific modes and simplified the system. Good performances of vibration suppression were achieved in both single-mode control and multimodal control.
Experimental study and finite element analysis for piezoelectric impact energy harvesting using a bent metal beam
Authors: Chen Song-Mao , Zhou Jin-Juan , Hu Jun-Hui
Published: December 2018

Linear uniform beams have been extensively investigated as a typical piezoelectric vibration energy harvesting mechanism in both conventional cantilever-beam-based harvester and a novel internal impact type energy harvester, the latter is of broad bandwidth and frequency up-converting capability and therefore quite suitable to low frequency ambient vibrations. To sufficiently utilize the space of the existing internal impact type energy harvester, a bent metal beam with distributed piezoelectric patches is proposed and investigated as the vibration energy harvesting module. A prototype harvester has been built and performances including the voltage and output power have been tested by experiments and analyzed by the finite element analysis. Both experiment and finite element analysis show that the proposed structure can effectively harvest vibration energy. And the optimal position for energy harvesting in this structure is also found. This work indicates that the frame of the existing internal impact type energy harvester may be used to harvest vibration energy, if it is bonded with distributed piezoelectric patches, which gives a way to increase its power density.
A piezohydraulic generator for vibration energy harvesting
Authors: Wang Shuyun , Liu Dianlong , Kan Junwu , Zhang Zhonghua , Yu Li , Xu Hailong
Published: December 2018

To improve energy generating capability and reliability/strength, a novel piezohydraulic generator for low frequency vibration was presented. The piezohydraulic generator consisted mainly of a double-rod hydraulic cylinder for conversion of vibration energy to fluid energy and piezodiscs for conversion of the fluidic energy to electric energy. A vibration function and energy-conversion model of the generator was established based on theory of vibration analysis and simulated to obtain the influence of backpressure on energy generation as well as optimal frequency. The analysis results show that both the energy generation and optimal frequency increases with the rising of backpressure under given other parameters. A piezohydraulic harvester was fabricated and tested at different backpressure. Both the optimal frequency and the relative peak voltage/power increase with the rising of backpressure. At 0.2 MPa and 0.8 MPa, the peak-voltage and the relative optimal-frequency are 9 V/11 Hz and 112 V/17.5 Hz respectively. Similarly, the peak-power and the relative optimal-frequency are 0.58 mW/13 Hz and 11.63 mW/17 Hz respectively. The research results indicate that a piezohydraulic generator can be used to harvest energy from a low-frequency and high-level vibration source.
Vibration control of cylindrical shells with a hybrid photovoltaic/piezoelectric actuation mechanism
Authors: Jiang Jing , Wang Lei , Yue Honghao , Deng Zongquan , Tzou Hornsen
Published: December 2018

Photovoltaic materials, which can directly turn light energy into electric energy, can offer the advantage of generating large voltages without external power supplies. When a near ultraviolet light illuminates on polarized PbLaZrTi (PLZT) materials, an electrical field can be generated along the spontaneous polarization direction due to the phovoltaic effect. This voltage generation mechanism exhibits many advantages, such as (1) high electrical output voltage, (2) wireless energy generation, (3) immune from electric/magnetic disturbances, (4) remote or non-contact control. In this study, Distributed vibration control of cylindrical shells using a hybrid photovoltaic/piezoelectric actuation mechanism is investigated. The light-driven photovoltaic generator induced voltage is used to drive a skew-quad piezoelectric actuator which can induce non-uniform control froces and control moments. Based on theoretical analysis and experimental validation, the constitutive equations defining the piezoelectric actuator induced actuation strain under the actuation mechanism are presented. Each region of the actuator system can induce both positive and negative control forces and moments using logical switches to shift the sign of control voltage of actuator system. Control effectiveness with constant light intensity control algorithm is evaluated and the time history analysis is presented.
On research of time reversal imaging method and structural health monitoring system
Authors: Qiu Lei , Yuan Shenfang , Yang Weibo
Published: December 2018

Structural health monitoring (SHM) technology is a reliable, efficient and economical approach to increase the safety and reduce the maintenance cost of high performance structures. Among the existing SHM methods, piezoelectric transducers (PZTs) array and Lamb wave based SHM methods are sensitive to small damage and studied by many researchers. In this paper, aiming at developing a practical method for on-line localization of damage and impact on aircraft composite structure which can take advantage of time reversal focusing and does not rely on the transfer function, a phase synthesis based time reversal focusing method is proposed and a twin-PZTs array arrangement based damage imaging method is discussed first. In this method, damage and impact images are given out directly through time reversal focusing and the other imaging processes such as the delay-and-sum imaging method adopted in many researches of time reversal focusing are not needed. And then, a kind of PZTs smart layer (PSL) with electromagnetic shielding is developed. For real application of SHM, an integrated multi-channel scanning system (ISS) with impact and damage monitoring function is developed thirdly. The ISS can scan large numbers of actuator-sensor channels and estimate impact and damage automatically. Finally, A SHM demonstration system is built on a carbon fiber composite panel with many bolt holes and stiffeners of an aircraft wing box based on the damage and impact imaging method, the PSL and the ISS. The demonstrating results show good performance of the whole SHM system.
A study on the optical diaphragm using magnetic fluid and a permanent magnet
Authors: Sudo Seiichi , Shinozaki Michihiro , Nishiyama Hideya
Published: December 2018

This paper is concerned with a novel optical diaphragm using magnetic fluid and a permanent magnet. The optical diaphragm consisting of a kerosene-based magnetic fluid and a small ring-shaped Nd _{2} Fe _{14} B permanent magnet was designed. The magnetic fluid diaphragm was driven by the external magnetic field. The experimental apparatus consists of the test magnetic fluid diaphragm system and the optical measurement system. Frequency characteristics of the magnetic fluid diaphragm in the alternating magnetic field were studied experimentally. The alternating magnetic field was generated by applying alternating current voltage to a Helmholtz coil. The alternating current signal was supplied from the frequency synthesizer. The dynamic responses of magnetic fluid diaphragm were analyzed with a high-speed video camera system. It was revealed that the amplitude of magnetic fluid hole oscillation depended on the frequency of magnetic field. The effect of the applied voltage on the amplitude of hole oscillation was also revealed.
Energy harvesting from large force vibrations using a piezoelectric wafer-stack harvester
Authors: Jiang Xuezheng , Gu Xiaoyu , Wang Jiong
Published: December 2018

This paper presents a novel piezoelectric harvester to convert ambient vibrations into usable electrical energy. Unlike the normal cantilever beam structure, the piezoelectric harvester developed in this paper is based on the wafer-stack configuration, which is appropriated for large force vibrations. Firstly, two electromechanical models (without and with a rectifier circuit), considering both the mechanical and electrical factors of the harvester, were built to characterize the harvested electrical power across the external load. Exact closed-form expressions of the electromechanical models have been given to analyze the maximum harvested power and the optimal resistance. It was shown that the harvested electrical power depends on the external vibration characteristics, the natural frequency, the mechanical damping factor, the normalized electrical load, the stiffness of the harvester and the overall electromechanical coupling coefficient of the harvester. Finally, a shake table experimental testing was conducted to evaluate the feasibility of the proposed piezoelectric wafer-stack harvester under standard sinusoidal loadings. Experimental results show that the harvester can generate a maximum 16 mW DC electrical power for sinusoidal loading with 3040 N amplitude and 2 Hz frequency, and the harvested electrical power is proportional to the strength of the exciting vibration.
Non-contact transient high-voltage measurement with self-integrating D-dot probe
Authors: Wang Jingang , Yang Jie , Luo Ruixi
Published: December 2018

Online transformer monitoring and protective relaying require voltage sensors with fast response and high precision. Traditional devices, such as resistive and capacitive dividers, have disadvantages in measuring transient voltage, e.g., oscillation, narrow bandwidth, and large size. This paper introduces a new D-dot probe for transient measurement. The difference input circuit structure is presented on the basis of the operating principle of the D-dot probe. Paralleled multiple electrodes are applied to gain the mutual capacitance value of the probe to achieve a large divide ratio and make the probe work in a self-integrating mode. Pspice simulation is conducted to find a way to minimize probe error. The probe is manufactured into printed circuit boards (PCB). The steady state linearity and transient response of the probe are tested. Results show that the probe has fast response and broad bandwidth.
Investigation on the magnetic bias current and electromagnetic force of power transformer in multi-layer soil area
Authors: Yang Fan , Dai Feng , Liu Xinghua , Yang Yongming , He Wei
Published: December 2018

When HVDC transmission lines operate in the monopole ground return mode or asymmetric bipolar mode, DC current flows in the earth and DC magnetic bias will arise in neutral point grounding (NPG) transformers.

In this work, the model to calculate the potential distribution for multi-layer soil structure is set up, then the magnetic bias current (MBC) is calculated. The magnetic field distribution in the NPG transformer is obtained according to MBC, and electromagnetic energy and force in the transformer are calculated. Finally, the influence on MBC, electromagnetic energy and force caused by soil parameters are investigated. Results indicate that thickness of the first layer and resistivity of the second layer have a greater contribution to MBC, electromagnetic energy and force. To avoid excessive vibration of the NPG transformer, the soil at grounding electrode with a greater thickness in the first layer and lower resistivity in the second layer is preferred.
Research of selection phase angle and dynamic control for closing process of intelligent AC contactors
Authors: Ye Peng , Shu Liang , Wu Guichu , Zhou Liang
Published: December 2018

The closing process of intelligent AC contactor can be affected by selection phase angle and the dynamic control strategy. A control strategy is proposed to compensate the influence of closing process at different phase angles. The mathematical model of the closing process is established by analyzing the dynamic characteristics of the contactor. Simulation and experimental comparisons show that the proposed model can predict the dynamic response of the closing process effectively. The relationship between the closing phase angle and the end speed is analyzed by using the experimental measurements. The selection phase angle and dynamic control is implemented by combining voltage zero crossing and PWM section control technology. The input voltage and the zero-crossing signal are taken as the control input while the PWM duty cycles and the strong excitation time are taken as the control output. The control strategy is implemented by using the lookup table. Experimental results show that by using the proposed strategy, the contactors can be closed with the same phase angle. Therefore the consistency of the dynamic closing process of the intelligent contactors can be guaranteed. Also, the movable armature end speed of the closing is reduced 31.5% and the closing time is decreased 15.6%. The mechanical life of the contactor has been increased about 4 times in the durability test.
Fractional dual fields for a slab placed in unbounded dielectric magnetic medium
Authors: Gulistan Samina , Abbas M. , Syed A.A.
Published: December 2018

Fractional dual solutions to the Maxwell equations for a dielectric slab placed in an unbounded dielectric magnetic medium are determined using the fractional curl operator. For extreme values of the intrinsic impedance of the host dielectric magnetic medium, the geometry becomes equivalent to that of a PEC or a PMC waveguide. In this way, the fractional dual fields for the PEC and PMC waveguide are also easily obtained.
Study on effect of material property on thermal power in induction cooker system with finite element method
Authors: Qiu Li , Wen Xibo , Li Hongsheng , Li Tiegang
Published: December 2018

The relative permeability and electrical conductivity of the pan material, both of which vary with temperature, play an important role in thermal power of induction cooker system. A series of finite element models, including a variable relative permeability electromagnetic model, a variable electrical conductivity electromagnetic model, and an electromagnetic and thermal coupling model, have been built by ANSYS software to analyze the variation of the thermal power with relative permeability and electrical conductivity in this paper. It is indicated that thermal power increases with the relative permeability increasing, but its growth rate decreases. When the electrical conductivity increases, thermal power increases, reaches a peak value, and then decreases. Considering the variation of the relative permeability and electrical conductivity with pan temperature, the simulation results show that thermal power decreases a lot when the temperature of the material exceeds a definite value due to the low relative permeability in this case. Finally, the induction heating mechanism is clearly understood and the simulation results provide useful guidance for induction cooker design.
Analytical and experimental approach of the high density transverse flux linear stepper motor
Authors: Zare Mohammad Reza , Misron Norhisam , Aris Ishak , Wakiwaka Hiroyuki
Published: December 2018

Detailed analytical and experimental approaches were performed to calculating the ratio of the pull-in thrust to the input power of High Density Transverse Flux linear Stepper Motor (HDTFLSM) with considerations of the electrical time constant, the mechanical time constant and the friction. The analytical approach involves the use of Fourier series analysis to derive the equation for the pull-in thrust to input power ratio. The experimentation was performed under different load conditions until the motor come to the standstill value. A chopped voltage was applied to motor at different speeds and the obtained results were compared with those for normal voltage.

Comparison between analytical and experimental results shows good agreement, for instance at 0.22 m/s the difference percentage on normal voltage and chopped voltage are 6.1% and 6.7%, respectively. The chopped voltage has higher ratio of the pull-in thrust to the input power compare to normal voltage so that the machine performance can be improvised to a greater extent. The maximum improvement percentage of 18.8% on pull-in thrust to input power ratio for motor with chopped voltage was obtained at 0.22 m/s.
High speed permanent magnet machine design with minimized stack-length under electromagnetic and mechanical constraints
Authors: Fernando W.U. Nuwantha , Gerada Christopher
Published: December 2018

Certain aircraft and military applications require high speed machines with low stack-length and the lowest possible weight. Hence, the accommodation of the highest bore diameter may seem the natural option. However, a rotor design with high diameter results in significant increase in mechanical stresses in the employed magnet retention. In a sleeved magnet retention mechanism, the sleeve thickness can be increased in order to accommodate the stresses. However, this will result in significant drop in air-gap flux-density and will not yield the high power density expected by the machine. This paper presents an analytical technique that combines the sleeve stress model and the air-gap flux density model to calculate the optimal rotor diameter to achieve the maximum power of the machine design for a minimum stack-length. The technique is applied to both a Carbon Fibre sleeve version and a metallic sleeve version. The analytical calculation of the stresses is validated with mechanical finite-element simulations. The machine design with the analytical calculations is validated with electromagnetic finite element simulations. The results confirm the rotor design strategy and the design technique.