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wave power Focusing due to the Bragg Resonance

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China Ocean Engineering 2017年第4期31卷 458-465页

作者： TAO Ai-feng YAN Jin WANG Yi ZHENG Jin-hai FAN Jun QIN Chuan State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China College of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China College of Energy and Electrical Engineering Hohai University Nanjing 210098 China

wave energy has drawn much attention as an achievable way to exploit the renewable energy. At present, in order to enhance the wave energy extraction, most efforts have been concentrated on optimizing the wave energy convertor and the power take-off system mechanically and electrically. However, focusing the wave power in specific wave field could also be an alternative to improve the wave energy extraction. In this experimental study, the Bragg resonance effect is applied to focus the wave energy. Because the Bragg resonance effect of the rippled bottom largely amplifies the wave reflection, leading to a significant increase of wave focusing. Achieved with an energy conversion system consisting of a point absorber and a permanent magnet single phase linear motor, the wave energy extracted in the wave flume with and without Bragg resonance effect was measured and compared quantitatively in experiment. It shows that energy extraction by a point absorber from a standing wave field resulted from Bragg resonance effect can be remarkably increased compared with that from a propagating wave field （without Bragg resonance effect）.

关键词： wave power experiment Bragg resonance

Terahertz-wave generation by surface-emitted four-wave mixing in optical fiber

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Chinese Optics Letters 2011年第5期9卷 59-62页

作者：周萍范滇元 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

We propose a novel terahertz-wave source through the four-wave mixing effect in a conventional single-mode optical fiber pumped by a dual-wavelength laser whose difference frequency lies in the terahertz range. Surface-emitted geometry is employed to decrease absorption loss. A detailed derivation of the terahertz-wave power expression is presented using the coupled-wave theory. This is a promising way for realizing a reasonable narrow-band terahertz-wave source.

关键词： Four wave mixing Optical fibers Optical pumping wave power

Preliminary Observation on Coordination of Pellet Injection and Ion Bernstein wave on a HT—7 Tokamak

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Chinese Physics Letters 2002年第5期19卷 701-703页

作者：杨愚赵燕平等 InstituteofPlasmaPhysics ChineseAcademyofSciencesHefei230031

A pellet injection (PI) experiment was performed during the application of the ion Bernstein wave on a HT-7 tokamak. A preliminary coordination effect was observed. With a lower wave power, shortly after PI, the coupling of the wave was enhanced, and the particle confinement was improved. With higher power, off-axis heating for 15% at about a/3 in the low field side was observed.

关键词： wave power

Study of Dissipating of wave Energy in the Breakers Zone of the Gulf of Guinea: Case of Autonomous Port of Cotonou in Benin Coastal Zone

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Journal of Modern Physics 2022年第9期13卷 1272-1286页

作者： Oswald G. Acclassato Noukpo Bernard Tokpohozin Christian D. Akowanou Adjimon Mathias Houékpohéha Guy Hervé Houngue Bruno Basile Kounouhéwa Laboratoire de Physique du Rayonnement FAST-UAC Cotonou République du Bénin Département de Physique (FAST) et Formation Doctorale Sciences des Matériaux (FDSM/UAC) Calavi République du Bé-nin Institut National Supérieur des Classes Préparatoires aux Etudes d’Ingénieur (INSPEI/UNSTIM) Abomey République du Bénin Institut de Mathématiques et de Sciences Physiques (IMSP/UAC) Porto-Novo République du Bénin

Rapid population growth and major trends of world economy growth have led to significant energy needs in our country. Benin, Gulf of Guinea country, although with a significant coastal network powered by potential energy from breaking waves, has experienced a deficit and a critical energy instability, marked by recurrent power cuts and disruption of the national economy. To ensure the integration of this source of renewable energy in the Benin energy mix and sustainably reduce the energy deficit in progress, this work has aimed to study the dissipation of wave energy at the bathymetric breaking in the breakers zone of Cotonou coast. Sea conditions and the statistics parameters of the breaking waves under perturbation effect of the seabed were evaluated to predict the beginning of the breaking. The modeling is based on the Navier-Stokes equation in which the viscosity and the interactions between the molecules of the oceanic fluid are neglected. The nonlinear wave dispersion relation is also used. The results obtained for this purpose showed that water particles have an almost parabolic motion during their fall;their velocity is higher than those of the early breaking. In this area, the waves dissipate about 80% of their energy: it generates turbulence which leads to a strong setting in motion of sediments.

关键词： wave Breaker Zone wave power Energy Dissipation Seabed

A review of the technologies for wave energy extraction

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Clean Energy 2018年第1期2卷 10-19页

作者： Eugen Rusu Florin Onea Department of Mechanical Engineering “Dunarea de Jos”University of GalatiDomneasca Street47Galati 800008Romania

The main objective of this article is to provide a comprehensive picture of existing wave technologies being used for wave energy *** overview will explain their potential and also the challenges wave technologies *** article will also briefly discuss the benefits of combined offshore wind-wave projects,also known as *** factors and impacts on relevant existing wave technologies will be outlined,including capacity factor and capture *** the levelized cost of energy(LCOE)targets for the most promising technologies will be discussed.

关键词： wave power wave energy converters capacity factor capture width hybrid solutions

Study on BDFG Control Strategy with Unbalanced loads

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Study on BDFG Control Strategy with Unbalanced loads

Time Series-, Time-Frequency- and Spectral Analyses of Sensor Measurements in an Offshore wave Energy Converter Based on Linear Generator Technology

第26届中国控制与决策会议

作者： ZHANG Shuai LIU Huikang Wuhan University of Science and Technology

ISBN: (纸本)9781479937066

When wave power system using BDFG operated in islanded mode,the unbalanced loads condition should be taken into consideration in the control system,otherwise it will cause active,reactive power and electromagnetic torque fluctuations because of civil *** this paper,the model of BDFG with unbalanced loads is deduced based on symmetrical component theory,the impact of negative sequence voltage on the BDFG vector control theory based on PI regulator is *** then current control strategy based on IM regulator of BDFG is *** analysis and simulation results show that introdduced theory and control strategy is correct and effective.

关键词： BDFG wave power unbalanced loads IMC MATLAB

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Energy and power Engineering 2013年第1期5卷 70-91页

作者： Erland Stromstedt Andrej Savin Olle Svensson Mats Leijon The Swedish Centre for Renewable Electric Energy Conversion Division for ElectricityDepartment of Engineering SciencesUppsala UniversityUppsalaSweden

Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performance of the WEC and its mechanical subsystems. One of the measurement systems was a set-up of 7 laser triangulation sensors for measuring relative displacement of the piston rod mechanical lead-through transmission in the direct drive. Two measurement periods, separated by 2.5 month, are presented in this paper. One measurement is made two weeks after launch and another 3 months after launch. Comparisons and correlations are made between different sensors measuring simultaneously. Noise levels are investigated. Filtering is discussed for further refinement of the laser triangulation sensor signals in order to separate noise from actual physical displacement and vibration. Measurements are presented from the relative displacement of the piston rod mechanical lead-through, from magnetic flux in the air gap, mechanical strain in the WEC structure, translator position and piston rod axial displacement and active AC power. Investigation into the measurements in the time domain with close-ups, in the frequency domain with Fast Fourier transform (FFT) and with time-frequency analysis with short time Fourier transform (STFT) is carried out to map the spectral content in the measurements. End stop impact is clearly visible in the time-frequency analysis. The FFT magnitude spectra are investigated for identifying the cogging bandwidth among other vibrations. Generator cogging, fluctuations in the damping force and in the Lorenz forces in the stator are distinguished and varies depending on translator speed. Vibrations from cogging seem to be present in the early measurement period while not so prominent in the late measurement period. Vibration frequencies due to wear are recognized by comparing with the noise at generator standstill and the vibration sources in th

关键词： wave power wave Energy Converter Linear Generator Sensor Measurements Spectral Analysis Cogging Filtering Laser Triangulation Sensor Draw-Wire Sensor Force Transducer Strain Gauges Search Coil power Generation

Prediction of the Inductance in a Synchronous Linear Permanent Magnet Generator

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Journal of Electromagnetic Analysis and Applications 2011年第5期3卷 155-159页

作者： Boel Ekergard Rafael Waters Mats Leijon The Division for Electricity Uppsala UniversityUppsalaSweden The wave Energy Converter Department The Wave Energy Company Seabased Industry ABUppsalaSweden

This paper presents calculations of the varying inductances profile for a synchronous linear surface mounted permanent magnet generator in an ABC reference system. Calculations are performed by utilizing the reluctance term, known from analytic calculations and finite element method simulations. With the inductance term identified, the voltage difference between the generator’s no load and load voltage can be calculated and an external circuit can be designed for optimal use of the generator. Two different operation intervals of the linear generator are considered and the results are discussed. The result indicates that time costly finite element simulations can be replaced with simple analytical calculations for a surface mounted permanent magnet linear generator.

关键词： wave power Synchronous Linear Permanent Magnet Generator Varying Inductance ABC of Frame Reference