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An Experimental Study on A Trapezoidal Pendulum Wave Energy Converter in Regular Waves

China Ocean Engineering 2015年第4期29卷 623-632页

作者：王冬姣邱守强叶家玮 School of Civil Engineering and Transportation South China University of Technology

Experimental studies were conducted on a trapezoidal pendulum wave energy converter in regular waves. To obtain the incident wave height, the analytical method （AM） was used to separate the incident and reflected waves propagating in a wave flume by analysing wave records measured at two locations. The response amplitude operator （RAO）, primary conversion efficiency and the total conversion efficiency of the wave energy converter were studied; furthermore, the power take-off damping coefficients corresponding to the load resistances in the experiment were also obtained. The findings demonstrate that the natural period for a pendulum wave energy converter is relatively large. A lower load resistance gives rise to a larger damping coefficient. The model shows relatively higher wave energy conversion efficiency in the range of 1.0-1.2 s for the incident wave period. The maximum primary conversion efficiency achieved was 55.5%, and the maximum overall conversion efficiency was 39.4%.

关键词： pendulum wave energy converter load resistance wave energy conversion efficiency

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Optimization of Out-of-Plane Vibration Energy Harvesters Employing Electret

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Journal of Beijing Institute of Technology 2017年第3期26卷 304-310页

作者： Chunhui Gao Shiqiao Gao Haipeng Liu Lei Jin Junhu Lu School of Mechatronical Engineering Beijing Institute of TechnologyBeijing 100081China

This paper investigated the dependence of out-of-plane electret-based vibration energy harvesters’output power,frequency bandwidth,and resonance frequency on surface charge density and load *** the external acceleration amplitude and electret size were held constant,the following results are predicted by the numerical investigation：（1）An optimum value exists in the surface charge density to maximize the output *** the surface charge density is increasing,electrostatic forces are enhanced,which emphasizes that the soft spring effect widens the frequency bandwidth and lowers the resonance frequency.（2）Different surface charge densities correspond to different optimum initial air gaps,resonance frequency,and optimum load resistance.（3）With the attenuation of the surface potential,the output power,frequency drift,and frequency bandwidth decreased.（4）An optimum value exists in the load resistance to maximize the output *** the load resistance is decreasing,electrostatic force is enhanced,which lowers the resonance frequency.（5）A maximum frequency bandwidth exists with further load resistance increasing,and the initial air gap is smaller,the greater the frequency bandwidth.

关键词： electret optimum surface charge density load resistance

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Performance Characteristics of an Irreversible Proton Exchange Membrane (PEM) Fuel Cell

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Journal of Donghua University(English Edition) 2012年第5期29卷 393-398页

作者：韦斐斐黄跃武 College of Environmental Science and Engineering Donghua University

A model of an irreversible proton exchange membrane （PEM） fuel cell working at steady-state was established, in which overpotenfials, internal currents, and crossover losses were taken into account. The expressions of some key parameters of the fuel cell were derived from the point of electrochemistry and thermodynamics. Based on the irreversible model of the PEM fuel ceil, the influence of multi-irreversibilities on fuel cell performance were characterized and compared systematically. The general performance characteristic curves were generated. Moreover, when the electrical circuit was dosed with a load in it, the relations between the load resistance and power output density and efficiency were analyzed. The results provide a theoretical basis for both the operation and optimal design of real PEM fuel cells.

关键词： proton exchange membrane ( PEM) fuel cell irreversible model performance characteristic leakage current load resistance

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External Magnetic Field Effect on Bifacial Silicon Solar Cell’s Electrical Parameters

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Energy and Power Engineering 2016年第3期8卷 146-151页

作者： Issa Zerbo Martial Zoungrana Idrissa Sourabié Adama Ouedraogo Bernard Zouma Dieudonné Joseph Bathiebo Department of Physics Laboratory of Thermal and Renewable Energies Unit of Training and Research in Pure and Applied Sciences University of Ouagadougou Joseph Ki-Zerbo Ouagadougou Burkina Faso

The aim of this work is to present a theoretical study of external magnetic field effect on a bifacial silicon solar cell’s electrical parameters (peak power, fill factor and load resistance) using the J-V and P-V characteristics. After the resolution of the magneto transport equation and continuity equation of excess minority carriers in the base of the bifacial silicon solar cell under multispectral illumination, the photo-current density and the photovoltage are determined and the J-V and P-V curves are plotted. Using simultaneously the J-V and P-V curves, we determine, according to magnetic field intensity, the peak photocurrent density, the peak photovoltage, the peak electric power, the fill factor and the load resistance at the peak power point. The numerical data show that the solar cell’s peak power decreases with magnetic field intensity while the fill factor and the load resistance increase.

关键词： Bifacial Silicon Solar Cell Fill Factor load resistance Magnetic Field Peak Power

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OPTIMIZATION DESIGN OF THE PIEZOELECTRIC CERAMIC COMPOSITE TRANSDUCER

OPTIMIZATION DESIGN OF THE PIEZOELECTRIC CERAMIC COMPOSITE T...

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2016年全国压电和声波理论及器件应用研讨会

作者： Jie XU Yang DOU Shu-yu LIN Shaanxi Key Laboratory of Ultrasonics Institute of Applied Acoustics Shaanxi Normal University

Background, Motivation and Objective Piezoelectric transducer is the key component in the field of acoustic application. The earliest piezoelectric transducer is designed for underwater detection, which is created by Paul Langevin in the 1917. The piezoelectric material is a device which can translate acoustic energy into electric energy, or vice versa. The piezoelectric transducer composited of the quartz crystal as piezoelectric material is clamped by two steel plates. Many scholars have done a great quantity of researches about an influence of the position of the piezoelectric crystal reactor on parameters of transducer. The impact of the impedance, the mechanical quality factor and the displacement of radiation on the position of piezoelectric plates less than 10 k Hz is studied by Lemaster. The experimental relationship between the position of piezoelectric plates and electroacoustic efficiency is researched by Ding Dacheng. The influence of the position of the piezoelectric plates on vibration characteristics is simulated by Xu Long. On the basis of previous studies, it is important that the position of piezoelectric plates affects the properties of the piezoelectric transducer. We study the influence using the method of numerical analysis. Statement of Contribution/Methods Firstly, the method of numerical analysis is used to analyze the equations of resonance frequency and electroacoustic efficiency. Because the equations are transcendental equations, we use Matlab software to obtain the relationships between the positions of the piezoelectric crystals reactors and electromechanical characteristics. Secondly, we make experiments measure the resonance/anti-resonance frequency. Results Based on electromechanical equivalent circuit and considered the mechanical losses and dielectric losses of the piezoelectric transducer, the equations of resonance frequency and electroacoustic efficiency are obtained. Analyzing the equations, we obtain the relationships between

关键词： Resonance frequency Electroacoustic efficiency load resistance Effective electromechanical coupling coefficient

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