WorldWideScience

Sample records for wave energy transducer

  1. Stress wave focusing transducers

    Energy Technology Data Exchange (ETDEWEB)

    Visuri, S.R., LLNL

    1998-05-15

    Conversion of laser radiation to mechanical energy is the fundamental process behind many medical laser procedures, particularly those involving tissue destruction and removal. Stress waves can be generated with laser radiation in several ways: creation of a plasma and subsequent launch of a shock wave, thermoelastic expansion of the target tissue, vapor bubble collapse, and ablation recoil. Thermoelastic generation of stress waves generally requires short laser pulse durations and high energy density. Thermoelastic stress waves can be formed when the laser pulse duration is shorter than the acoustic transit time of the material: {tau}{sub c} = d/c{sub s} where d = absorption depth or spot diameter, whichever is smaller, and c{sub s} = sound speed in the material. The stress wave due to thermoelastic expansion travels at the sound speed (approximately 1500 m/s in tissue) and leaves the site of irradiation well before subsequent thermal events can be initiated. These stress waves, often evolving into shock waves, can be used to disrupt tissue. Shock waves are used in ophthalmology to perform intraocular microsurgery and photodisruptive procedures as well as in lithotripsy to fragment stones. We have explored a variety of transducers that can efficiently convert optical to mechanical energy. One such class of transducers allows a shock wave to be focused within a material such that the stress magnitude can be greatly increased compared to conventional geometries. Some transducer tips could be made to operate regardless of the absorption properties of the ambient media. The size and nature of the devices enable easy delivery, potentially minimally-invasive procedures, and precise tissue- targeting while limiting thermal loading. The transducer tips may have applications in lithotripsy, ophthalmology, drug delivery, and cardiology.

  2. Sensitivity limits of capacitive transducer for gravitational wave resonant antennas

    Energy Technology Data Exchange (ETDEWEB)

    Bassan, M; Pizzella, G [Rome Tor Vergata Univ. (Italy). Dip. di Fisica

    1996-12-01

    It is analyzed the performance of a resonant gravitational wave antenna equipped with a resonant, d.c. biased capacitive transducer, an untuned superconducting matching circuit and a d.c. Squid. It is derived simple relations for the detector energy sensitivity that serve as guidelines for device development and it is shown that, with reasonable improvements in Squid technology, an effective temperature for burst detection of 2miK can be achieved.

  3. High-Temperature Surface-Acoustic-Wave Transducer

    Science.gov (United States)

    Zhao, Xiaoliang; Tittmann, Bernhard R.

    2010-01-01

    Aircraft-engine rotating equipment usually operates at high temperature and stress. Non-invasive inspection of microcracks in those components poses a challenge for the non-destructive evaluation community. A low-profile ultrasonic guided wave sensor can detect cracks in situ. The key feature of the sensor is that it should withstand high temperatures and excite strong surface wave energy to inspect surface/subsurface cracks. As far as the innovators know at the time of this reporting, there is no existing sensor that is mounted to the rotor disks for crack inspection; the most often used technology includes fluorescent penetrant inspection or eddy-current probes for disassembled part inspection. An efficient, high-temperature, low-profile surface acoustic wave transducer design has been identified and tested for nondestructive evaluation of structures or materials. The development is a Sol-Gel bismuth titanate-based surface-acoustic-wave (SAW) sensor that can generate efficient surface acoustic waves for crack inspection. The produced sensor is very thin (submillimeter), and can generate surface waves up to 540 C. Finite element analysis of the SAW transducer design was performed to predict the sensor behavior, and experimental studies confirmed the results. One major uniqueness of the Sol-Gel bismuth titanate SAW sensor is that it is easy to implement to structures of various shapes. With a spray coating process, the sensor can be applied to surfaces of large curvatures. Second, the sensor is very thin (as a coating) and has very minimal effect on airflow or rotating equipment imbalance. Third, it can withstand temperatures up to 530 C, which is very useful for engine applications where high temperature is an issue.

  4. Active Metamaterial Based Ultrasonic Guided Wave Transducer System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — An active and tunable metamaterial phased array transducer for guided wave mode selection with high intensity per driving channel and with dramatically lower modal...

  5. Numerical comparison of patch and sandwich piezoelectric transducers for transmitting ultrasonic waves

    CSIR Research Space (South Africa)

    Loveday, PW

    2006-03-01

    Full Text Available in the waveguide. Piezoelectric patch transducers are frequently employed, by researchers, for exciting waves in beam like structures. Sonar systems frequently make use of resonant transducers, such as sandwich transducers, for acoustic wave generation...

  6. Lamb wave tuning curve calibration for surface-bonded piezoelectric transducers

    International Nuclear Information System (INIS)

    Sohn, Hoon; Lee, Sang Jun

    2010-01-01

    Surface-bonded lead zirconate titanate (PZT) transducers have been widely used for guided wave generation and measurement. For selective actuation and sensing of Lamb wave modes, the sizes of the transducers and the driving frequency of the input waveform should be tuned. For this purpose, a theoretical Lamb wave tuning curve (LWTC) of a specific transducer size is generally obtained. Here, the LWTC plots each Lamb wave mode' amplitude as a function of the driving frequency. However, a discrepancy between experimental and existing theoretical LWTCs has been observed due to little consideration of the bonding layer and the energy distribution between Lamb wave modes. In this study, calibration techniques for theoretical LWTCs are proposed. First, a theoretical LWTC is developed when circular PZT transducers are used for both Lamb wave excitation and sensing. Then, the LWTC is calibrated by estimating the effective PZT size with PZT admittance measurement. Finally, the energy distributions among symmetric and antisymmetric modes are taken into account for better prediction of the relative amplitudes between Lamb wave modes. The effectiveness of the proposed calibration techniques is examined through numerical simulations and experimental estimation of the LWTC using the circular PZT transducers instrumented on an aluminum plate

  7. Universal Quantum Transducers Based on Surface Acoustic Waves

    NARCIS (Netherlands)

    Schuetz, M.J.A.; Kessler, E.M.; Giedke, G.; Vandersypen, L.M.K.; Lukin, M.D.; Cirac, J.I.

    2015-01-01

    We propose a universal, on-chip quantum transducer based on surface acoustic waves in piezoactive materials. Because of the intrinsic piezoelectric (and/or magnetostrictive) properties of the material, our approach provides a universal platform capable of coherently linking a broad array of qubits,

  8. Transducers for the Brazilian gravitational wave detector 'Mario Schenberg'

    International Nuclear Information System (INIS)

    Frajuca, Carlos; Ribeiro, Kilder L; Andrade, Luiz A; Jr, Walter F Velloso; Melo, Jose L; Aguiar, Odylio D; Magalhaes, Nadja S

    2002-01-01

    'Mario Schenberg' is a spherical resonant-mass gravitational wave (GW) detector that will be part of a GW detection array of three detectors. The other two will be built in Italy and the Netherlands. Their resonant frequencies will be around 3.2 kHz with a bandwidth of about 200 Hz. This range of frequencies is new in a field where the typical frequencies lie below 1 kHz, making the transducer development much more complex. In this paper, the design of the mechanical part of the transducer will be shown, as well as the attachment method to the sphere and the expected sensitivity

  9. Development of an SH Wave Magnetostrictive Transducer Module for Guided Wave Testing of Plate Structures

    International Nuclear Information System (INIS)

    Cho, Seung Hyun; Park, Jae Ha; Kwon Hyu Sang; Ahn, Bong Young; Lee, Seung Seok

    2009-01-01

    Recently much attention has been paid to a guided wave due to its effective applicability to long range and fast inspection of structures. In guided wave based NDE, the appropriate selection of wave modes is one of important factors since the test performance is highly dependent on which mode of guided waves is employed. As far as plate-like structures are concerned, so far, SH guided wave has not been frequently applied compared to Lamb waves, which is mostly caused by the lack of proper and convenient transducers to generate and measure the SH waves. In this investigation, a new small-sized SH guided wave transducer based on magnetostriction is proposed. The present transducer was designed to be modular and be used with shear couplant to avoid the inconvenience of the existing magnetostrictive patch transducers, which comprises the ferromagnetic patch tightly bonded to a structure. The wave transduction mechanism and the detailed configuration of the present transducer are presented. Experimental verification is also conducted on test specimens and the results confirm the good performance of the present transducer module

  10. Development of an SH Wave Magnetostrictive Transducer Module for Guided Wave Testing of Plate Structures

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seung Hyun; Park, Jae Ha; Kwon Hyu Sang; Ahn, Bong Young; Lee, Seung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2009-04-15

    Recently much attention has been paid to a guided wave due to its effective applicability to long range and fast inspection of structures. In guided wave based NDE, the appropriate selection of wave modes is one of important factors since the test performance is highly dependent on which mode of guided waves is employed. As far as plate-like structures are concerned, so far, SH guided wave has not been frequently applied compared to Lamb waves, which is mostly caused by the lack of proper and convenient transducers to generate and measure the SH waves. In this investigation, a new small-sized SH guided wave transducer based on magnetostriction is proposed. The present transducer was designed to be modular and be used with shear couplant to avoid the inconvenience of the existing magnetostrictive patch transducers, which comprises the ferromagnetic patch tightly bonded to a structure. The wave transduction mechanism and the detailed configuration of the present transducer are presented. Experimental verification is also conducted on test specimens and the results confirm the good performance of the present transducer module

  11. Design of compact piezoelectric transducers for shock wave applications

    Science.gov (United States)

    Dreyer, Thomas; Liebler, Marko; Riedlinger, Rainer E.; Ginter, Siegfried

    2003-10-01

    The application of focused intense sound pulses to treat several orthopedic diseases has gained in importance during the past years. Self-focusing piezoelectric transducers known from ESWL are not well suited for this purpose due to their size. Therefore compact transducers have to be designed. This implies an increase of the pressure pulse amplitude generated at the radiating surface. A stacked placement of two piezoelectric layers driven by two high-voltage pulses with an adjustable delay accomplishes this. Several designs are presented here representing transducers of different sizes. In principle piezoelectric transducers have the ability to vary the pressure pulse shape to a wider extent than other shock wave sources. Based on FEM simulations of the transducer the influence of some driving parameters, like a variation of the interpulse delay or shape of the driving voltage, on the resulting focal pressure signal is demonstrated. The results show the feasibility to control some parameters of the signal, for example the peak negative pressure amplitude. This possibility could provide new aspects in basic research as well as in clinical applications.

  12. Selective generation of ultrasonic Lamb waves by electromagnetic acoustic transducers

    International Nuclear Information System (INIS)

    Li Ming-Liang; Deng Ming-Xi; Gao Guang-Jian

    2016-01-01

    In this paper, we describe a modal expansion approach for the analysis of the selective generation of ultrasonic Lamb waves by electromagnetic acoustic transducers (EMATs). With the modal expansion approach for waveguide excitation, an analytical expression of the Lamb wave’s mode expansion coefficient is deduced, which is related to the driving frequency and the geometrical parameters of the EMAT’s meander coil, and lays a theoretical foundation for exactly analyzing the selective generation of Lamb waves with EMATs. The influences of the driving frequency on the mode expansion coefficient of ultrasonic Lamb waves are analyzed when the EMAT’s geometrical parameters are given. The numerical simulations and experimental examinations show that the ultrasonic Lamb wave modes can be effectively regulated (strengthened or restrained) by choosing an appropriate driving frequency of EMAT, with the geometrical parameters given. This result provides a theoretical and experimental basis for selectively generating a single and pure Lamb wave mode with EMATs. (special topic)

  13. Wave energy

    Energy Technology Data Exchange (ETDEWEB)

    Whittaker, T.J.T. (Queen' s Univ., Belfast, Northern Ireland (UK)); White, P.R.S. (Lanchester Polytechnic, Coventry (UK)); Baker, A.C.J. (Binnie and Partners, London (UK))

    1988-10-01

    An informal discussion on various wave energy converters is reported. These included a prototype oscillating water column (OWC) device being built on the Isle of Islay in Scotland; the SEA Clam; a tapering channel device (Tapchan) raising incoming waves into a lagoon on a Norwegian island and an OWC device on the same island. The Norwegian devices are delivering electricity at about 5.5p/KWh and 4p/KWh respectively with possibilities for reduction to 2.5-3p/KWh and 3p/KWh under favourable circumstances. The discussion ranged over comparisons with progress in wind power, engineering aspects, differences between inshore and offshore devices, tidal range and energy storage. (UK).

  14. Optical detection of radio waves through a nanomechanical transducer

    DEFF Research Database (Denmark)

    Bagci, T.; Simonsen, A.; Schmid, Silvan

    2014-01-01

    Low-loss transmission and sensitive recovery of weak radio-frequency and microwave signals is a ubiquitous challenge, crucial in radio astronomy, medical imaging, navigation, and classical and quantum communication. Efficient up-conversion of radio-frequency signals to an optical carrier would...... strong coupling between the voltage fluctuations in a radio-frequency resonance circuit and the membrane's displacement, which is simultaneously coupled to light reflected off its surface. The radio-frequency signals are detected as an optical phase shift with quantum-limited sensitivity....... The corresponding half-wave voltage is in the microvolt range, orders of magnitude less than that of standard optical modulators. The noise of the transducer--beyond the measured 800 pV Hz-1/2 Johnson noise of the resonant circuit--consists of the quantum noise of light and thermal fluctuations of the membrane...

  15. Dynamic Mode Tuning of Ultrasonic Guided Wave Using an Array Transducer

    International Nuclear Information System (INIS)

    Kim, Young H.; Song, Sung J.; Park, Joon S.; Kim, Jae H.; Eom, Heung S.

    2005-01-01

    Ultrasonic guided waves have been widely employed for long range inspection of structures such as plates, rods and pipes. There are numerous modes with different wave velocities, and the appropriate mode selection is one of key techniques in the application of guided waves. In the present work, phase tuning by an array transducer was applied to generate ultrasonic guided waves. For this purpose, 8-channel ultrasonic pulser/receiver and their controller which enables sequential activation of each channels with given time delay were developed. Eight transducers were fabricated in order to generate guided waves by using an array transducer. The selective tuning of wave mode can be achieved by changing the interval between elements of an array transducer

  16. Development of a Modular Magnetostrictive Transducer for Torsional Guided Wave Transduction in a Cylindrical Structure

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seung Hyun; Park, Jae Ha; Kwon, Hyu Sang; Ahn, Bong Young; Lee, Seung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2009-10-15

    Cylindrical structures such as pipes and shafts are widely used in various industrial facilities. Recently, researches on magnetostrictive transduction of torsional waves have been actively reported for the nondestructive evaluation of those cylindrical structures. However, the existing magnetostrictive patch transducer has somewhat inconvenient and time. Consuming process like patch bonding to a structure since it should employ a magnetostrictive patch having strong magnetostriction. To overcome these limitations of the existing transducer, in this work, we develop a novel modular magnetostrictive transducer to generate and measure torsional waves to inspect a cylindrical structure. The proposed transducer can be applied as viscous liquid coupling with shear couplant or dry coupling without coupling media instead of patch bonding to a structure. We describe a detailed structure of the modular transducer and conduct some experiments to verify its performance

  17. Development of a Modular Magnetostrictive Transducer for Torsional Guided Wave Transduction in a Cylindrical Structure

    International Nuclear Information System (INIS)

    Cho, Seung Hyun; Park, Jae Ha; Kwon, Hyu Sang; Ahn, Bong Young; Lee, Seung Seok

    2009-01-01

    Cylindrical structures such as pipes and shafts are widely used in various industrial facilities. Recently, researches on magnetostrictive transduction of torsional waves have been actively reported for the nondestructive evaluation of those cylindrical structures. However, the existing magnetostrictive patch transducer has somewhat inconvenient and time. Consuming process like patch bonding to a structure since it should employ a magnetostrictive patch having strong magnetostriction. To overcome these limitations of the existing transducer, in this work, we develop a novel modular magnetostrictive transducer to generate and measure torsional waves to inspect a cylindrical structure. The proposed transducer can be applied as viscous liquid coupling with shear couplant or dry coupling without coupling media instead of patch bonding to a structure. We describe a detailed structure of the modular transducer and conduct some experiments to verify its performance

  18. Thermal energy harvesters with piezoelectric or electrostatic transducer

    Science.gov (United States)

    Prokaryn, Piotr; Domański, Krzysztof; Marchewka, Michał; Tomaszewski, Daniel; Grabiec, Piotr; Puscasu, Onoriu; Monfray, Stéphane; Skotnicki, Thomas

    2014-08-01

    This paper describes the idea of the energy harvester which converts thermal gradient present in environment into electricity. Two kinds of such devices are proposed and their prototypes are shown and discussed. The main parts of harvesters are bimetallic spring, piezoelectric transducer or electrostatic transducer with electret. The applied piezomembrane was commercial available product but electrets was made by authors. In the paper a fabrication procedure of electrets formed by the corona discharge process is described. Devices were compared in terms of generated power, charging current, and the voltage across a storage capacitor.

  19. Piezoelectric transducer parameter selection for exciting a single mode from multiple modes of Lamb waves

    International Nuclear Information System (INIS)

    Zhang Hai-Yan; Yu Jian-Bo

    2011-01-01

    Excitation and propagation of Lamb waves by using rectangular and circular piezoelectric transducers surface-bonded to an isotropic plate are investigated in this work. Analytical stain wave solutions are derived for the two transducer shapes, giving the responses of these transducers in Lamb wave fields. The analytical study is supported by a numerical simulation using the finite element method. Symmetric and antisymmetric components in the wave propagation responses are inspected in detail with respect to test parameters such as the transducer geometry, the length and the excitation frequency. By placing only one piezoelectric transducer on the top or the bottom surface of the plate and weakening the strength of one mode while enhancing the strength of the other modes to find the centre frequency, with which the peak wave amplitude ratio between the S0 and A0 modes is maximum, a single mode excitation from the multiple modes of the Lamb waves can be achieved approximately. Experimental data are presented to show the validity of the analyses. The results are used to optimize the Lamb wave detection system. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  20. Development and research of in-core transducers at IAE (Institute of Atomic Energy)

    International Nuclear Information System (INIS)

    Huang Yucai; Qian Shunfa; Jia Guozhen

    1989-10-01

    The development of in-core transducers at IAE (Institute of Atomic Energy) and their applications in in-pile fuel assembly test are mentioned. These transducers include mainly tubed tungsten-rhenium thermocouple assembly, displacement transducer of linear variable differential transformer, pressure transducer of membrane type, gamma thermometer, turbine flow meter, self-powered neutron detector etc

  1. Multiharmonic Frequency-Chirped Transducers for Surface-Acoustic-Wave Optomechanics

    Science.gov (United States)

    Weiß, Matthias; Hörner, Andreas L.; Zallo, Eugenio; Atkinson, Paola; Rastelli, Armando; Schmidt, Oliver G.; Wixforth, Achim; Krenner, Hubert J.

    2018-01-01

    Wide-passband interdigital transducers are employed to establish a stable phase lock between a train of laser pulses emitted by a mode-locked laser and a surface acoustic wave generated electrically by the transducer. The transducer design is based on a multiharmonic split-finger architecture for the excitation of a fundamental surface acoustic wave and a discrete number of its overtones. Simply by introducing a variation of the transducer's periodicity p , a frequency chirp is added. This combination results in wide frequency bands for each harmonic. The transducer's conversion efficiency from the electrical to the acoustic domain is characterized optomechanically using single quantum dots acting as nanoscale pressure sensors. The ability to generate surface acoustic waves over a wide band of frequencies enables advanced acousto-optic spectroscopy using mode-locked lasers with fixed repetition rate. Stable phase locking between the electrically generated acoustic wave and the train of laser pulses is confirmed by performing stroboscopic spectroscopy on a single quantum dot at a frequency of 320 MHz. Finally, the dynamic spectral modulation of the quantum dot is directly monitored in the time domain combining stable phase-locked optical excitation and time-correlated single-photon counting. The demonstrated scheme will be particularly useful for the experimental implementation of surface-acoustic-wave-driven quantum gates of optically addressable qubits or collective quantum states or for multicomponent Fourier synthesis of tailored nanomechanical waveforms.

  2. Energy harvesting for wireless sensors by using piezoelectric transducers

    Energy Technology Data Exchange (ETDEWEB)

    Duerager, Christian [Empa, Swiss Federal Laboratories for Materials Science and Technology, Duebendorf (Switzerland)

    2012-07-01

    Wireless sensor technology, which integrates transducers, measurement electronics and wireless communication, has become increasingly vital in structural health monitoring (SHM) applications. Compared to traditional wired systems, wireless solutions reduce the installation time and costs and are not subjected to breakage caused by harsh weather conditions or other extreme events. Because of the low installation costs, wireless sensor networks allow the deployment of a big number of wireless sensor nodes on the structures. Moreover, the nodes can be placed on particularly critical components of the structure difficult to reach by wires. In most of the cases the power supply are conventional batteries, which could be a problem because of their finite life span. Furthermore, in the case of wireless sensor nodes located on structures, it is often advantageous to embed them, which makes an access impossible. Therefore, if a method of obtaining the untapped energy surrounding these sensors was implemented, significant life could be added to the power supply. Various approaches to energy harvesting and energy storage are discussed and limitations associated with the current technology are addressed. In this paper we first discuss the research that has been performed in the area of energy harvesting for wireless sensor technologies by using the ambient vibration energy. In many cases the energy produced by the ambient vibrations is far too small to directly power a wireless sensor node. Therefore, in a second step we discuss the development process for an electronic energy harvesting circuit optimized for piezoelectric transducers. In the last part of this paper an experiment with different piezoelectric transducers and their applicability for energy harvesting applications on vibrating structures will be discussed. (orig.)

  3. Three-dimensional temperature effect modelling of piezoceramic transducers used for Lamb wave based damage detection

    International Nuclear Information System (INIS)

    Kijanka, Piotr; Packo, Pawel; Staszewski, Wieslaw J; Zhu, Xuan; Di Scalea, Francesco Lanza

    2015-01-01

    The paper presents a three-dimensional temperature-dependent model of surface-bonded, low-profile piezoceramic transducers (PZT) used for Lamb wave propagation. The effect of temperature on Lamb wave actuation, propagation and sensing is investigated. The major focus is on the study of actuation and sensing properties of PZT for various temperature levels. These properties are investigated through the electric field analysis of transducers. The temperature effect on transducer bond layers is also investigated. Numerically simulated amplitude responses are analysed for various temperatures and excitation frequencies. Numerical simulations are validated experimentally. The results demonstrate that temperature-dependent physical properties of PZT, bond layers and particularly host structures significantly affect the amplitude and phase of Lamb wave responses. (paper)

  4. A new omnidirectional shear horizontal wave transducer using face-shear (d24) piezoelectric ring array.

    Science.gov (United States)

    Miao, Hongchen; Huan, Qiang; Wang, Qiangzhong; Li, Faxin

    2017-02-01

    The non-dispersive fundamental shear horizontal (SH 0 ) wave in plate-like structures is of practical importance in non-destructive testing (NDT) and structural health monitoring (SHM). Theoretically, an omnidirectional SH 0 transducer phased array system can be used to inspect defects in a large plate in the similar manner to the phased array transducers used in medical B-scan ultrasonics. However, very few omnidirectional SH 0 transducers have been proposed so far. In this work, an omnidirectional SH 0 wave piezoelectric transducer (OSH-PT) was proposed, which consists of a ring array of twelve face-shear (d 24 ) trapezoidal PZT elements. Each PZT element can produce face-shear deformation under applied voltage, resulting in circumferential shear deformation in the OSH-PT and omnidirectional SH 0 waves in the hosting plate. Both finite element simulations and experiments were conducted to examine the performance of the proposed OSH-PT. Experimental testing shows that the OSH-PT exhibits good omnidirectional properties, no matter it is used as a SH 0 wave transmitter or a SH 0 wave receiver. This work may greatly promote the applications of SH 0 waves in NDT and SHM. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. The Wave Energy Sector

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter

    2017-01-01

    This Handbook for Ocean Wave Energy aims at providing a guide into the field of ocean wave energy utilization. The handbook offers a concise yet comprehensive overview of the main aspects and disciplines involved in the development of wave energy converters (WECs). The idea for the book has been...... shaped by the development, research, and teaching that we have carried out at the Wave Energy Research Group at Aalborg University over the past decades. It is our belief and experience that it would be useful writing and compiling such a handbook in order to enhance the understanding of the sector...

  6. Phononic Crystal Waveguide Transducers for Nonlinear Elastic Wave Sensing.

    Science.gov (United States)

    Ciampa, Francesco; Mankar, Akash; Marini, Andrea

    2017-11-07

    Second harmonic generation is one of the most sensitive and reliable nonlinear elastic signatures for micro-damage assessment. However, its detection requires powerful amplification systems generating fictitious harmonics that are difficult to discern from pure nonlinear elastic effects. Current state-of-the-art nonlinear ultrasonic methods still involve impractical solutions such as cumbersome signal calibration processes and substantial modifications of the test component in order to create material-based tunable harmonic filters. Here we propose and demonstrate a valid and sensible alternative strategy involving the development of an ultrasonic phononic crystal waveguide transducer that exhibits both single and multiple frequency stop-bands filtering out fictitious second harmonic frequencies. Remarkably, such a sensing device can be easily fabricated and integrated on the surface of the test structure without altering its mechanical and geometrical properties. The design of the phononic crystal structure is supported by a perturbative theoretical model predicting the frequency band-gaps of periodic plates with sinusoidal corrugation. We find our theoretical findings in excellent agreement with experimental testing revealing that the proposed phononic crystal waveguide transducer successfully attenuates second harmonics caused by the ultrasonic equipment, thus demonstrating its wide range of potential applications for acousto/ultrasonic material damage inspection.

  7. A spiral wave front beacon for underwater navigation: transducer prototypes and testing.

    Science.gov (United States)

    Dzikowicz, Benjamin R; Hefner, Brian T

    2012-05-01

    Transducers for acoustic beacons which can produce outgoing signals with wave fronts whose horizontal cross sections are circular or spiral are studied experimentally. A remote hydrophone is used to determine its aspect relative to the transducers by comparing the phase of the circular signal to the phase of the spiral signal. The transducers for a "physical-spiral" beacon are made by forming a strip of 1-3 piezocomposite transducer material around either a circular or spiral backing. A "phased-spiral" beacon is made from an array of transducer elements which can be driven either in phase or staggered out of phase so as to produce signals with either a circular or spiral wave front. Measurements are made to study outgoing signals and their usefulness in determining aspect angle. Vertical beam width is also examined and phase corrections applied when the hydrophone is out of the horizontal plane of the beacon. While numerical simulations indicate that the discontinuity in the physical-spiral beacon introduces errors into the measured phase, damping observed at the ends of the piezocomposite material is a more significant source of error. This damping is also reflected in laser Doppler vibrometer measurements of the transducer's surface velocity.

  8. Selection of Shear Horizontal Wave Transducers for Robotic Nondestructive Inspection in Harsh Environments

    Directory of Open Access Journals (Sweden)

    Sungho Choi

    2016-12-01

    Full Text Available Harsh environments and confined spaces require that nondestructive inspections be conducted with robotic systems. Ultrasonic guided waves are well suited for robotic systems because they can provide efficient volumetric coverage when inspecting for various types of damage, including cracks and corrosion. Shear horizontal guided waves are especially well suited for robotic inspection because they are sensitive to cracks oriented perpendicular or parallel to the wave propagation direction and can be generated with electromagnetic acoustic transducers (EMATs and magnetostrictive transducers (MSTs. Both types of transducers are investigated for crack detection in a stainless steel plate. The MSTs require the robot to apply a compressive normal force that creates frictional force coupling. However, the coupling is observed to be very dependent upon surface roughness and surface debris. The EMATs are coupled through the Lorentz force and are thus noncontact, although they depend on the lift off between transducer and substrate. After comparing advantages and disadvantages of each transducer for robotic inspection the EMATs are selected for application to canisters that store used nuclear fuel.

  9. Applying of the array transducers' technology for surface acoustic waves materials characterization in the transient regime

    International Nuclear Information System (INIS)

    Frenet, D.

    2000-01-01

    In this document we present a theoretical and experimental study which has been led to design a surface acoustic wave device for local characterisation (relatively to the wavelength) of isotropic or anisotropic materials. The device is based on a phased-array transducer of conical shape we have specifically designed for this purpose. It operates in the impulsive mode, in the frequency range of 1-5 MHz. In order to deduce mechanical properties of the material, it is possible to measure the surface wave characteristics (velocity, attenuation,...). Different methods for measuring the wave velocity have been developed taking advantage of from the phased-array technology. The originality of theses methods relies on the fact that the measures are performed without moving the transducer. Consequently, the device requires no additional mechanical system and it is quite compact. In addition, this shortens the characterisation process duration comparatively to the usually available methods (e. g. the V(z) technique). In the theoretical section of this study, a versatile model allowing to simulate in the time harmonic regime as well as in the transient regime, the transmitted field, the field reflected on isotropic or anisotropic planar samples and the output voltage for transducers of arbitrary shapes has been developed. The model has been applied to the phased-array conical transducer as well as to more classical transducers such as planar (rectangular) or focusing (spherically or cylindrically shaped) transducers. It predicts not only the geometrical contributions of the reflected field and signal but also the leaky contributions related to the surface acoustic waves. (author)

  10. A Four-Quadrant PVDF Transducer for Surface Acoustic Wave Detection

    Directory of Open Access Journals (Sweden)

    Zhi Chen

    2012-08-01

    Full Text Available In this paper, a polyvinylidene fluoride (PVDF piezoelectric transducer was developed to detect laser-induced surface acoustic waves in a SiO2-thin film–Si-substrate structure. In order to solve the problems related to, firstly, the position of the probe, and secondly, the fact that signals at different points cannot be detected simultaneously during the detection process, a four-quadrant surface acoustic wave PVDF transducer was designed and constructed for the purpose of detecting surface acoustic waves excited by a pulse laser line source. The experimental results of the four-quadrant piezoelectric detection in comparison with the commercial nanoindentation technology were consistent, the relative error is 0.56%, and the system eliminates the piezoelectric surface wave detection direction deviation errors, improves the accuracy of the testing system by 1.30%, achieving the acquisition at the same time at different testing positions of the sample.

  11. Cycloidal Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  12. SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Vicinanza, Diego; Frigaard, Peter

    2008-01-01

    The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level, in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low...... head hydroturbines are converting the potential energy of the stored water into power. A key to success for the SSG will be the low cost of the structure and its robustness. The construction of the pilot plant is scheduled and this paper aims to describe the concept of the SSG wave energy converter...

  13. Pipe Wall Thinning Evaluation through the Arrival Time Delay of A0 Lamb Wave Using Magnetostrictive Patch Transducers

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Seung Hyun; Kwon, Hyu Sang; Ahn, Bong Young; Lee, Seung Seok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2008-12-15

    Guided wave technology is advantageous for fast inspection of pipe wall thinning since the guided wave propagates long distance. In this investigation, the method to evaluate gradual wall thinning in a pipe based on the arrival time delay with magnetostrictive patch transducers is presented. Low frequency A0 Lamb waves were generated and measured by the present transducer and it was applied to arrival time delay measurement experiments on a test pipe having gradual wall thinnings artificially manufactured. From experiments, consistent results that wall thinning increases the arrival time delay of A0 waves were obtained. Consequently, the feasibility of the magnetostrictive patch transducers to evaluate wall thinning was verified

  14. Pipe Wall Thinning Evaluation through the Arrival Time Delay of A0 Lamb Wave Using Magnetostrictive Patch Transducers

    International Nuclear Information System (INIS)

    Cho, Seung Hyun; Kwon, Hyu Sang; Ahn, Bong Young; Lee, Seung Seok

    2008-01-01

    Guided wave technology is advantageous for fast inspection of pipe wall thinning since the guided wave propagates long distance. In this investigation, the method to evaluate gradual wall thinning in a pipe based on the arrival time delay with magnetostrictive patch transducers is presented. Low frequency A0 Lamb waves were generated and measured by the present transducer and it was applied to arrival time delay measurement experiments on a test pipe having gradual wall thinnings artificially manufactured. From experiments, consistent results that wall thinning increases the arrival time delay of A0 waves were obtained. Consequently, the feasibility of the magnetostrictive patch transducers to evaluate wall thinning was verified

  15. Influence of the Spatial Dimensions of Ultrasonic Transducers on the Frequency Spectrum of Guided Waves.

    Science.gov (United States)

    Samaitis, Vykintas; Mažeika, Liudas

    2017-08-08

    Ultrasonic guided wave (UGW)-based condition monitoring has shown great promise in detecting, localizing, and characterizing damage in complex systems. However, the application of guided waves for damage detection is challenging due to the existence of multiple modes and dispersion. This results in distorted wave packets with limited resolution and the interference of multiple reflected modes. To develop reliable inspection systems, either the transducers have to be optimized to generate a desired single mode of guided waves with known dispersive properties, or the frequency responses of all modes present in the structure must be known to predict wave interaction. Currently, there is a lack of methods to predict the response spectrum of guided wave modes, especially in cases when multiple modes are being excited simultaneously. Such methods are of vital importance for further understanding wave propagation within the structures as well as wave-damage interaction. In this study, a novel method to predict the response spectrum of guided wave modes was proposed based on Fourier analysis of the particle velocity distribution on the excitation area. The method proposed in this study estimates an excitability function based on the spatial dimensions of the transducer, type of vibration, and dispersive properties of the medium. As a result, the response amplitude as a function of frequency for each guided wave mode present in the structure can be separately obtained. The method was validated with numerical simulations on the aluminum and glass fiber composite samples. The key findings showed that it can be applied to estimate the response spectrum of a guided wave mode on any type of material (either isotropic structures, or multi layered anisotropic composites) and under any type of excitation if the phase velocity dispersion curve and the particle velocity distribution of the wave source was known initially. Thus, the proposed method may be a beneficial tool to explain

  16. Ocean wave energy conversion

    CERN Document Server

    McCormick, Michael E

    2007-01-01

    This volume will prove of vital interest to those studying the use of renewable resources. Scientists, engineers, and inventors will find it a valuable review of ocean wave mechanics as well as an introduction to wave energy conversion. It presents physical and mathematical descriptions of the nine generic wave energy conversion techniques, along with their uses and performance characteristics.Author Michael E. McCormick is the Corbin A. McNeill Professor of Naval Engineering at the U.S. Naval Academy. In addition to his timely and significant coverage of possible environmental effects associa

  17. Optical detection of radio waves through a nanomechanical transducer

    DEFF Research Database (Denmark)

    Bagci, Tolga; Simonsen, A; Schmid, Silvan

    2013-01-01

    Low-loss transmission and sensitive recovery of weak radio-frequency (rf) and microwave signals is an ubiquitous technological challenge, crucial in fields as diverse as radio astronomy, medical imaging, navigation and communication, including those of quantum states. Efficient upconversion of rf-signals...... to an optical carrier would allow transmitting them via optical fibers instead of copper wires dramatically reducing losses, and give access to the mature toolbox of quantum optical techniques, routinely enabling quantum-limited signal detection. Research in the field of cavity optomechanics [1, 2] has shown...... reflected off its metallized surface. The circuit acts as an antenna; the voltage signals it induces are detected as an optical phase shift with quantum-limited sensitivity. The corresponding half-wave voltage is in the microvolt range, orders of magnitude below that of standard optical modulators...

  18. Efficient Wave Energy Amplification with Wave Reflectors

    DEFF Research Database (Denmark)

    Kramer, Morten Mejlhede; Frigaard, Peter Bak

    2002-01-01

    Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130......-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benifit...... for different geometries of the wave reflectors and optimal geometrical design parameters are specified. On this basis inventors of WEC's can evaluate whether a specific WEC possible could benefit from wave reflectors....

  19. Measurement of Rayleigh Wave Beams Using Angle Beam Wedge Transducers as the Transmitter and Receiver with Consideration of Beam Spreading.

    Science.gov (United States)

    Zhang, Shuzeng; Li, Xiongbing; Jeong, Hyunjo

    2017-06-20

    A theoretical model, along with experimental verification, is developed to describe the generation, propagation and reception of a Rayleigh wave using angle beam wedge transducers. The Rayleigh wave generation process using an angle beam wedge transducer is analyzed, and the actual Rayleigh wave sound source distributions are evaluated numerically. Based on the reciprocity theorem and considering the actual sound source, the Rayleigh wave beams are modeled using an area integral method. The leaky Rayleigh wave theory is introduced to investigate the reception of the Rayleigh wave using the angle beam wedge transducers, and the effects of the wave spreading in the wedge and transducer size are considered in the reception process. The effects of attenuations of the Rayleigh wave and leaky Rayleigh wave are discussed, and the received wave results with different sizes of receivers are compared. The experiments are conducted using two angle beam wedge transducers to measure the Rayleigh wave, and the measurement results are compared with the predictions using different theoretical models. It is shown that the proposed model which considers the wave spreading in both the sample and wedges can be used to interpret the measurements reasonably.

  20. Actuating mechanism and design of a cylindrical traveling wave ultrasonic motor using cantilever type composite transducer.

    Directory of Open Access Journals (Sweden)

    Yingxiang Liu

    Full Text Available BACKGROUND: Ultrasonic motors (USM are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy. PRINCIPAL FINDINGS: A cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the outside surface of cylinder, four longitudinal PZT ceramics are set between the cantilevers, and four bending PZT ceramics are set on each outside surface of cantilevers. Two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder are excited by the composite transducer. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Thus, elliptical motions are achieved on the teeth. The actuating mechanism of proposed motor was analyzed. The stator was designed with FEM. The two vibration modes of stator were degenerated. Transient analysis was developed to gain the vibration characteristic of stator, and results indicate the motion trajectories of nodes on the teeth are nearly ellipses. CONCLUSIONS: The study results verify the feasibility of the proposed design. The wave excited in the cylinder isn't an ideal traveling wave, and the vibration amplitudes are inconsistent. The distortion of traveling wave is generated by the deformation of bending vibration mode of cylinder, which is caused by the coupling effect between the cylinder and transducer. Analysis results also prove that the objective motions of nodes on the teeth are three-dimensional vibrations. But, the vibration in axial direction is minute compared with the vibrations in circumferential and radial direction. The results of this paper can guide the development of this new type of motor.

  1. Actuating mechanism and design of a cylindrical traveling wave ultrasonic motor using cantilever type composite transducer.

    Science.gov (United States)

    Liu, Yingxiang; Chen, Weishan; Liu, Junkao; Shi, Shengjun

    2010-04-02

    Ultrasonic motors (USM) are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy. A cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the outside surface of cylinder, four longitudinal PZT ceramics are set between the cantilevers, and four bending PZT ceramics are set on each outside surface of cantilevers. Two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder are excited by the composite transducer. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Thus, elliptical motions are achieved on the teeth. The actuating mechanism of proposed motor was analyzed. The stator was designed with FEM. The two vibration modes of stator were degenerated. Transient analysis was developed to gain the vibration characteristic of stator, and results indicate the motion trajectories of nodes on the teeth are nearly ellipses. The study results verify the feasibility of the proposed design. The wave excited in the cylinder isn't an ideal traveling wave, and the vibration amplitudes are inconsistent. The distortion of traveling wave is generated by the deformation of bending vibration mode of cylinder, which is caused by the coupling effect between the cylinder and transducer. Analysis results also prove that the objective motions of nodes on the teeth are three-dimensional vibrations. But, the vibration in axial direction is minute compared with the vibrations in circumferential and radial direction. The results of this paper can guide the development of this new type of motor.

  2. Electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  3. Reflectors to Focus Wave Energy

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    2005-01-01

    Wave Energy Converters (WEC’s) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased by approximately 30......-50%. Clearly longer wave reflectors will focus more wave energy than shorter wave reflectors. Thus the draw back is the increased wave forces for the longer wave reflectors. In the paper a procedure for calculating the energy efficiency and the wave forces on the reflectors are described, this by use of a 3D...... boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benefit for different wave reflector geometries and optimal geometrical design parameters are specified. On this basis inventors of WEC’s can...

  4. Damage detection using piezoelectric transducers and the Lamb wave approach: I. System analysis

    International Nuclear Information System (INIS)

    Wang, X; Lu, Y; Tang, J

    2008-01-01

    Structural damage detection using piezoelectric transducers and the Lamb wave approach has been under intensive investigations. A commonly pursued topic is the selection of system parameters such that the detection performance can be optimized. Previous studies have indicated that the excitation center frequency plays a critical role, and suggested use of the 'sweet spot' frequency to maximize the peak wave amplitude ratio between the S 0 and the A 0 modes. In this paper, the analytical formulation of Lamb wave propagation on a narrow-strip beam excited and sensed by piezoelectric transducers is outlined first. Then, the antisymmetric and symmetric contents of the wave propagation response are analyzed in detail with respect to system parameters. In particular, the parametric influence on the 'sweet spot' frequency is investigated systematically. The complicated interaction of the wave components with respect to damage is illustrated through case studies. The analytical study is supported by numerical analysis using the finite element method and by experimental investigation. This research provides the mechanistic basis for robust damage detection using data processing and statistical analysis tools which is the focus of the second paper of this two-paper series

  5. The Wave Energy Device

    DEFF Research Database (Denmark)

    Frigaard, Peter; Kofoed, Jens Peter; Tedd, James William

    2006-01-01

    's first offshore wave energy converter. During this period an extensive measuring program has established the background for optimal design of the structure and regulation of the power take off system. Planning for full scale deployment of a 7 MW unit within the next 2 years is in progress. The prototype...

  6. The Evolution of Energy-Transducing Systems. Studies with Archaebacteria

    Science.gov (United States)

    Stan-Lotter, Helga

    1996-01-01

    The dicyclohexyl carbodiimide (DCCD)- binding site of the membrane ATPase from Halobacterium saccharovorum was investigated during earlier periods of this Cooperative Agreement and was localized to a cyanogen bromide fragment of subunit 2 from amino acids 379 (Glu) to 442 (Met). Although the exact position of the reactive amino acid (probably a glutamic acid) has not yet been determined, the data, together with recently obtained immuno reactions and sequences of Cyanogen Bromide (CNBr) fragments from E.coli F-ATPase, suggested subunit interactions in the halobacterial ATPase which had not been recognized before. They also provided evidence for the presence of a gamma subunit in the halobacterial ATPase, and for a stretch of a amino acids similar to the 'catch' between beta and gamma in bovine F-ATPase. The evolutionary implications of these findings are twofold: first, halobacterial (or archaebacterial) ATPases appear as complex as those from higher organisms - no simpler versions of these membrane enzymes are known to date; second, a monophyletic origin of the energy-transducing ATPases is becoming more apparent, and - together with other data - the split into V- and F-ATPases may have occurred much later than had been previously thought (i.e., after the split into Archaea and Bacteria). Other work included the characterization of an extremely halophilic isolate (Halococcus salifodinae ) from Permian salt sediments. This organism appeared to be an autotrophic halobacterium; its incorporation of C02 was investigated.

  7. Coupling effect of piezoelectric wafer transducers in distortions of primary Lamb wave modes

    International Nuclear Information System (INIS)

    Bijudas, C R; Mitra, M; Mujumdar, P M

    2013-01-01

    Piezoelectric wafer transducers (PWT) are widely used for Lamb wave based damage detection schemes. The size of the damage that can be detected is dependent on the wavelength of the Lamb wave employed. Thus it is essential to explore the higher frequency range within the (fundamental) bandwidth of S 0 and A 0 modes, however below the cut-off frequencies of A 1 and S 1 . It is observed that the Lamb wave modes S 0 and A 0 generated using PWT undergo distortion within this fundamental bandwidth. This behavior is experimentally observed for different PWT sizes and types. The nature of this observed distortion is very different from the distortion of wave modes due to dispersion. In addition, the distortion, in many cases, tends towards the appearance of new wave modes close to the S 0 and A 0 modes. To understand this experimental observation, a theoretical study is performed. First, finite element (FE) simulations of Lamb waves considering pin-force, thermal analogy, and couple field models of surface mounted PWT are carried out. These simulation studies reveal that the wavepacket distortion can be attributed mostly to electro-mechanical coupling effect of the PWT. Next, the dispersion plot of piezoelectric layer considering electro-mechanical coupling is obtained using spectral finite element (SFE) method. These dispersion characteristics of the PWT are found to be significantly different from the conventional Lamb wave dispersion characteristics and may explain the experimental observation. (paper)

  8. Phased transducer array for acoustic energy harvesting inside an MRI machine

    NARCIS (Netherlands)

    Klymko, V.; Roes, M.G.L.; Duivenbode, van J.; Lomonova, E.

    2013-01-01

    In this study, an array of piezoelectric speakers is used to focus acoustic energy on a single transducer that acts as a harvester. The transmitting transducers are located along a curve that fits inside the magnetic resonance interferometer (MRI) torus interior. The numerical results for the

  9. Energy from the waves

    CERN Document Server

    Ross, D

    2012-01-01

    Revised and substantially expanded to include the latest developments in the field, the second edition of this popular book provides a concise, non-technical account of the historical background and current research and development in the field of wave energy and its planned utilisation. It explains in simple terms the technology involved and describes the new inventions, devices and discoveries which led wave energy to be regarded as a significant future source of alternative power. The author recounts the major events leading up to today's development; the roles played by the principal characters involved, inventors, engineers and politicians and the inevitable struggle which all pioneers must face. The book concludes by discussing the environmental implications, the political conflicts and the problems which lie ahead. Also included, is a useful glossary of terms and a selected bibliography of important technical reports and further sources of information.

  10. Optimization of autonomous magnetic field sensor consisting of giant magnetoimpedance sensor and surface acoustic wave transducer

    KAUST Repository

    Li, Bodong; Morsy, Ahmed Mohamed Aly; Kosel, Jü rgen

    2012-01-01

    This paper presents a novel autonomous thin film magnetic field sensor consisting of a tri-layer giant magnetoimpedance sensor and a surface acoustic wave transponder. Double and single electrode interdigital transducer (IDT) designs are employed and compared. The integrated sensor is fabricated using standard microfabrication technology. The results show the double electrode IDT has an advantage in terms of the sensitivity. In order to optimize the matching component, a simulation based on P-matrix is carried out. A maximum change of 2.4 dB of the reflection amplitude and a sensitivity of 0.34 dB/Oe are obtained experimentally. © 2012 IEEE.

  11. Optimization of autonomous magnetic field sensor consisting of giant magnetoimpedance sensor and surface acoustic wave transducer

    KAUST Repository

    Li, Bodong

    2012-11-01

    This paper presents a novel autonomous thin film magnetic field sensor consisting of a tri-layer giant magnetoimpedance sensor and a surface acoustic wave transponder. Double and single electrode interdigital transducer (IDT) designs are employed and compared. The integrated sensor is fabricated using standard microfabrication technology. The results show the double electrode IDT has an advantage in terms of the sensitivity. In order to optimize the matching component, a simulation based on P-matrix is carried out. A maximum change of 2.4 dB of the reflection amplitude and a sensitivity of 0.34 dB/Oe are obtained experimentally. © 2012 IEEE.

  12. Liquid sodium testing of in-house phased array EMAT transducer for L-wave applications

    Energy Technology Data Exchange (ETDEWEB)

    Le Bourdais, F.; Le Polles, T. [Non Destructive Testing Department at the French Atomic Energy Commission (CEA), Saclay, 91191 Gif sur Yvette CEDEX, (France); Baque, F. [Department of Sodium Technology at the French Atomic Energy Commission (CEA), Cadarache, 13108 St Paul lez Durance CEDEX, (France)

    2015-07-01

    This paper describes the development of an in-house phased array EMAT transducer for longitudinal wave inspection in liquid sodium. The work presented herein is part of an undergoing project aimed at improving in-service inspection techniques for the ASTRID reactor project. The design process of the phased array EMAT probe is briefly explained and followed by a review of experimental test results. We first present test results obtained in the laboratory while the last part of the paper describes the liquid sodium testing and the produced ultrasound images. (authors)

  13. Liquid sodium testing of in-house phased array EMAT transducer for L-wave applications

    International Nuclear Information System (INIS)

    Le Bourdais, F.; Le Polles, T.; Baque, F.

    2015-01-01

    This paper describes the development of an in-house phased array EMAT transducer for longitudinal wave inspection in liquid sodium. The work presented herein is part of an undergoing project aimed at improving in-service inspection techniques for the ASTRID reactor project. The design process of the phased array EMAT probe is briefly explained and followed by a review of experimental test results. We first present test results obtained in the laboratory while the last part of the paper describes the liquid sodium testing and the produced ultrasound images. (authors)

  14. Bulk Shear-Wave Transduction Experiments Using Magnetostrictive Transducers with a Thin Fe-Co Alloy Patch

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Ha; Cho, Seung Hyun; Ahn, Bong Young; Kwon, Hyu Sang [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2010-08-15

    Recently, the results of many studies have clarified the successful performance of magnetostrictive transducers in which a ferromagnetic patch is used for the transduction of guided shear waves; this is because a thin ferromagnetic patch with strong magnetostriction is very useful for generating and detecting shear wave. This investigation deals with bulk shear wave transduction by means of magnetostriction; on the other hand, the existing studies have been focused on guided shear waves. A modular transducer was developed: this transducer comprised a coil, magnets, and a thin ferromagnetic patch that was made of Fe-Co alloy. Some experiments were conducted to verify the performance of the developed transducer. Radiation directivity pattern of the developed transducer was obtained, and a test to detect the damage on a side drill hole of a steel block specimen was carried out. From the results of these tests, the good performance of the transducer for nondestructive testing was verified on the basis of the signal-to-noise ratio and narrow beam directivity.

  15. Bilinear Time-frequency Analysis for Lamb Wave Signal Detected by Electromagnetic Acoustic Transducer

    Science.gov (United States)

    Sun, Wenxiu; Liu, Guoqiang; Xia, Hui; Xia, Zhengwu

    2018-03-01

    Accurate acquisition of the detection signal travel time plays a very important role in cross-hole tomography. The experimental platform of aluminum plate under the perpendicular magnetic field is established and the bilinear time-frequency analysis methods, Wigner-Ville Distribution (WVD) and the pseudo-Wigner-Ville distribution (PWVD), are applied to analyse the Lamb wave signals detected by electromagnetic acoustic transducer (EMAT). By extracting the same frequency component of the time-frequency spectrum as the excitation frequency, the travel time information can be obtained. In comparison with traditional linear time-frequency analysis method such as short-time Fourier transform (STFT), the bilinear time-frequency analysis method PWVD is more appropriate in extracting travel time and recognizing patterns of Lamb wave.

  16. Specimen ferromagnetism and the behaviour of electromagnetic ultrasonic shear-wave transducers below and above the Curie point

    International Nuclear Information System (INIS)

    Robinson, T.S.

    1981-04-01

    Interest in the potentialities of electromagnetic ultrasonic transducers for non-destructive testing was re-awakened about 1968 and since then a goodly number of articles have appeared concerning transducers design, performance and use. The aim of this report is to fill a gap by describing the relations between theoretical and actual performance of shear-wave transducers, used on magnetic and on non-magnetic specimens: in particular to trace the phenomena occuring as the temperature of a magnetic specimen (mild steel) is raised through the Curie point. At the transmitting transducer generation of ultrasonic wave is almost exclusively by Lorentz forces applied to the skin of the specimen; at the receiver transduction is via Faraday induction. Wave attenuation in mild steel above the curie point hampers the use of shear waves, but does not render unusable there. An anomaly in performance with mild steel specimens just above the Curie temperature is discussed, which necessitates a brief consideration of electromagnetic longitudinal wave transducers, where the need to invoke magnetostriction as a dominant phenomenon is expressed. (Auhtor)

  17. A variable-frequency structural health monitoring system based on omnidirectional shear horizontal wave piezoelectric transducers

    Science.gov (United States)

    Huan, Qiang; Miao, Hongchen; Li, Faxin

    2018-02-01

    Structural health monitoring (SHM) is of great importance for engineering structures as it may detect the early degradation and thus avoid life and financial loss. Guided wave based inspection is very useful in SHM due to its capability for long distance and wide range monitoring. The fundamental shear horizontal (SH0) wave based method should be most promising since SH0 is the unique non-dispersive wave mode in plate-like structures. In this work, a sparse array SHM system based on omnidirectional SH wave piezoelectric transducers (OSH-PT) was proposed and the multi data fusion method was used for defect inspection in a 2 mm thick aluminum plate. Firstly, the performances of three types OSH-PTs was comprehensively compared and the thickness-poled d15 mode OSH-PT used in this work was demonstrated obviously superior to the other two. Then, the signal processing method and imaging algorithm for this SHM system was presented. Finally, experiments were carried out to examine the performance of the proposed SHM system in defect localization and imaging. Results indicated that this SHM system can locate a through hole as small as 0.12λ (4 mm) in diameter (where λ is the wavelength corresponding to the central operation frequency) under frequencies from 90 to 150 kHz. It can also locate multiple defects accurately based on the baseline subtraction method. Obviously, this SHM system can detect larger areas with sparse sensors because of the adopted single mode, non-dispersive and low frequency SH0 wave which can propagate long distance with small attenuation. Considering its good performances, simple data processing and sparse array, this SH0 wave-based SHM system is expected to greatly promote the applications of guided wave inspection.

  18. Determination of group velocity of propagation of Lamb waves in aluminium plate using piezoelectric transducers

    Directory of Open Access Journals (Sweden)

    Lašová Z.

    2017-06-01

    Full Text Available A prior knowledge of group velocities of Lamb wave modes is a key for analysis of time signals in guidedwave based structural health monitoring. The identification of multiple wave modes may be complicated due to dependency of group velocity on frequency (dispersion. These dependencies for infinite plate of constant thickness can be calculated by a numerical solution of analytic equation. Two alternative approaches to determine group velocities of zero-order Lamb wave modes in aluminum plate were used in this work: Two-dimensional Fast Fourier Transform (2D-FFT and methods of time-frequency processing. 2D-FFT requires a high number of time signals in equidistant points, therefore it was applied on data from finite element analysis of wave propagation in the plate. Group velocities for chosen frequencies were also determined using wavelet transform (WT of signals as differencies of times of arrival measured by a pair of piezoelectric transducers. The results from 2D-FFT and wavelet transform were compared to the analytic solution.

  19. Wireless guided wave and impedance measurement using laser and piezoelectric transducers

    International Nuclear Information System (INIS)

    Park, Hyun-Jun; Sohn, Hoon; Yun, Chung-Bang; Chung, Joseph; Lee, Michael M S

    2012-01-01

    Guided-wave- and impedance-based structural health monitoring (SHM) techniques have gained much attention due to their high sensitivity to small defects. One of the popular devices commonly used for guided wave and impedance measurements is a lead zirconate titanate (PZT) transducer. This study proposes a new wireless scheme where the power and data required for PZT excitation and sensing are transmitted via laser. First, a modulated laser beam is wirelessly transmitted to the photodiode connected to a PZT on a structure. Then, the photodiode converts the laser light into an electric signal, and it is applied to the PZT for excitation. The corresponding responses, impedance at the same PZT or guided waves at another PZT, are measured, re-converted into laser light, and wirelessly transmitted back to the other photodiode located in the data interrogator for signal processing. The feasibility of the proposed wireless guided wave and impedance measurement schemes has been examined through circuit analyses and experimentally investigated in a laboratory setup. (paper)

  20. Handbook of Ocean Wave Energy

    DEFF Research Database (Denmark)

    This book offers a concise, practice-oriented reference-guide to the field of ocean wave energy. The ten chapters highlight the key rules of thumb, address all the main technical engineering aspects and describe in detail all the key aspects to be considered in the techno-economic assessment...... in the wave energy sector. •Offers a practice-oriented reference guide to the field of ocean wave energy •Presents an overview as well as a deeper insight into wave energy converters •Covers both the economic and engineering aspects related to ocean wave energy conversion...... of wave energy converters. Written in an easy-to-understand style, the book answers questions relevant to readers of different backgrounds, from developers, private and public investors, to students and researchers. It is thereby a valuable resource for both newcomers and experienced practitioners...

  1. Handbook of Ocean Wave Energy

    DEFF Research Database (Denmark)

    This book offers a concise, practice-oriented reference-guide to the field of ocean wave energy. The ten chapters highlight the key rules of thumb, address all the main technical engineering aspects and describe in detail all the key aspects to be considered in the techno-economic assessment...... of wave energy converters. Written in an easy-to-understand style, the book answers questions relevant to readers of different backgrounds, from developers, private and public investors, to students and researchers. It is thereby a valuable resource for both newcomers and experienced practitioners...... in the wave energy sector. •Offers a practice-oriented reference guide to the field of ocean wave energy •Presents an overview as well as a deeper insight into wave energy converters •Covers both the economic and engineering aspects related to ocean wave energy conversion...

  2. Wave energy: a Pacific perspective.

    Science.gov (United States)

    Paasch, Robert; Ruehl, Kelley; Hovland, Justin; Meicke, Stephen

    2012-01-28

    This paper illustrates the status of wave energy development in Pacific rim countries by characterizing the available resource and introducing the region's current and potential future leaders in wave energy converter development. It also describes the existing licensing and permitting process as well as potential environmental concerns. Capabilities of Pacific Ocean testing facilities are described in addition to the region's vision of the future of wave energy.

  3. First test of a BAE transducing scheme on a Resonant Gravitational-Wave Antenna

    International Nuclear Information System (INIS)

    Bonifazi, P.; Vaselli, V.; Visco, M.

    1997-01-01

    The authors present the results obtained with a resonant capacitive transducer, suitable for Back Action Evasion (BAE) measurements, coupled for the first time to a gravitational-wave antenna. This scheme was developed in collaboration with the Group of the University of Rome La Sapienza. The antenna is a 270 kg aluminum 5056 alloy cylinder, with a resonant frequency of 1805 Hz, operating at 4.2 K in the ALTAIR cryostat, located in Frascati (Italy) at the IFSI-CNR laboratory. The apparatus was able to work for periods as long as days, both in up-conversion and BAE configurations, with good stability. The behaviour of the system is in reasonable agreement with a proposed model of a double harmonic oscillator in a BAE readout scheme. The limits on the sensitivity of this set-up are discussed as well as the possible future improvements

  4. Damage detection using piezoelectric transducers and the Lamb wave approach: II. Robust and quantitative decision making

    International Nuclear Information System (INIS)

    Lu, Y; Wang, X; Tang, J; Ding, Y

    2008-01-01

    The propagation of Lamb waves generated by piezoelectric transducers in a one-dimensional structure has been studied comprehensively in part I of this two-paper series. Using the information embedded in the propagating waveforms, we expect to make a decision on whether damage has occurred; however, environmental and operational variances inevitably complicate the problem. To better detect the damage under these variances, we present in this paper a robust and quantitative decision-making methodology involving advanced signal processing and statistical analysis. In order to statistically evaluate the features in Lamb wave propagation in the presence of noise, we collect multiple time series (baseline signals) from the undamaged beam. A combination of the improved adaptive harmonic wavelet transform (AHWT) and the principal component analysis (PCA) is performed on the baseline signals to highlight the critical features of Lamb wave propagation in the undamaged structure. The detection of damage is facilitated by comparing the features of the test signal collected from the test structure (damaged or undamaged) with the features of the baseline signals. In this process, we employ Hotelling's T 2 statistical analysis to first purify the baseline dataset and then to quantify the deviation of the test data vector from the baseline dataset. Through experimental and numerical studies, we systematically investigate the proposed methodology in terms of the detectability (capability of detecting damage), the sensitivity (with respect to damage severity and excitation frequency) and the robustness against noises. The parametric studies also validate, from the signal processing standpoint, the guidelines of Lamb-wave-based damage detection developed in part I

  5. Transducer Placement Option of Lamb Wave SHM System for Hotspot Damage Monitoring

    Directory of Open Access Journals (Sweden)

    Vincentius Ewald

    2018-04-01

    Full Text Available In this paper, we investigated transducer placement strategies for detecting cracks in primary aircraft structures using ultrasonic Structural Health Monitoring (SHM. The approach developed is for an expected damage location based on fracture mechanics, for example fatigue crack growth in a high stress location. To assess the performance of the developed approach, finite-element (FE modelling of a damage-tolerant aluminum fuselage has been performed by introducing an artificial crack at a rivet hole into the structural FE model and assessing its influence on the Lamb wave propagation, compared to a baseline measurement simulation. The efficient practical sensor position was determined from the largest change in area that is covered by reflected and missing wave scatter using an additive color model. Blob detection algorithms were employed to determine the boundaries of this area and to calculate the blob centroid. To demonstrate that the technique can be generalized, the results from different crack lengths and from tilted crack are also presented.

  6. Gating energies and forces of the mammalian hair cell transducer channel and related hair bundle mechanics

    NARCIS (Netherlands)

    van Netten, SM; Kros, CJ

    2000-01-01

    We quantified the molecular energies and forces involved in opening and closing of mechanoelectrical transducer channels in hair cells using a novel generally applicable method. It relies on a thermodynamic description of the free energy of an ion channel in terms of its open probability. The

  7. Excitation of spin waves in BiFeO3 multiferroic film by the slot line transducer

    Science.gov (United States)

    Korneev, V. I.; Popkov, A. F.; Solov'yov, S. V.

    2018-01-01

    Analysis of the efficiency of magnetoelectric excitation of spin-waves in BiFeO3 multiferroic films by a slot line is performed based on the solution of dynamic Ginzburg-Landau equations for the antiferromagnetic vector. The excitation efficiency is determined by the magnitude of the conversion coefficient of the electromagnetic wave to the spin wave by the slot line transducer or in other words, losses on conversion in the slot line. Calculations are made for a homogeneous antiferromagnetic state of the multiferroic in the presence of a sufficiently large magnetic field and for a spatially modulated spin state (SMSS) at zero magnetic field. It is shown that in the case of a homogeneous antiferromagnetic state, the losses on the excitation of spin waves exceed the excitation efficiency in the SMSS state; however, as the frequency approaches the spin excitation gap, it falls and becomes lower than in the SMSS state. Spin wave excitation in the presence of antiferromagnetic cycloid strongly depends on the relation of the slot width of the transducer to the cycloid periodicity and on the magnitude of the shift of the position of the transducer along the cycloid on its period. The usage of multiferroics for delay lines in the considered frequency range from 100 to 600 GHz requires significant reduction in conversion and propagation losses. More promising seems multiferroic usage in phase shifters and switches for this range.

  8. Wave Dissipation on Low- to Super-Energy Coral Reefs

    Science.gov (United States)

    Harris, D. L.

    2016-02-01

    Coral reefs are valuable, complex and bio-diverse ecosystems and are also known to be one of the most effective barriers to swell events in coastal environments. Previous research has found coral reefs to be remarkably efficient in removing most of the wave energy during the initial breaking and transformation on the reef flats. The rate of dissipation is so rapid that coral reefs have been referred to as rougher than any known coastal barrier. The dissipation of wave energy across reef flats is crucial in maintaining the relatively low-energy conditions in the back reef and lagoonal environments providing vital protection to adjacent beach or coastal regions from cyclone and storm events. A shift in the regulation of wave energy by reef flats could have catastrophic consequences ecologically, socially, and economically. This study examined the dissipation of wave energy during two swell events in Tahiti and Moorea, French Polyesia. Field sites were chosen in varying degrees of exposure and geomorphology from low-energy protected sites (Tiahura, Moorea) to super-energy sites (Teahupo'o, Tahiti). Waves were measured during two moderate to large swell events in cross reef transects using short-term high-resolution pressure transducers. Wave conditions were found to be similar in all back reef locations despite the very different wave exposure at each reef site. However, wave conditions on the reef flats were different and mirrored the variation in wave exposure with depth over the reef flat the primary regulator of reef flat wave height. These results indicate that coral reef flats evolve morphodynamically with the wave climate, which creates coral reef geomorphologies capable of dissipating wave energy that results in similar back reef wave conditions regardless of the offshore wave climate.

  9. Adaptive acoustic energy delivery to near and far fields using foldable, tessellated star transducers

    Science.gov (United States)

    Zou, Chengzhe; Harne, Ryan L.

    2017-05-01

    Methods of guiding acoustic energy arbitrarily through space have long relied on digital controls to meet performance needs. Yet, more recent attention to adaptive structures with unique spatial configurations has motivated mechanical signal processing (MSP) concepts that may not be subjected to the same functional and performance limitations as digital acoustic beamforming counterparts. The periodicity of repeatable structural reconfiguration enabled by origami-inspired tessellated architectures turns attention to foldable platforms as frameworks for MSP development. This research harnesses principles of MSP to study a tessellated, star-shaped acoustic transducer constituent that provides on-demand control of acoustic energy guiding via folding-induced shape reconfiguration. An analytical framework is established to probe the roles of mechanical and acoustic geometry on the far field directivity and near field focusing of sound energy. Following validation by experiments and verification by simulations, parametric studies are undertaken to uncover relations between constituent topology and acoustic energy delivery to arbitrary points in the free field. The adaptations enabled by folding of the star-shaped transducer reveal capability for restricting sound energy to angular regions in the far field while also introducing means to modulate sound energy by three orders-of-magnitude to locations near to the transducer surface. In addition, the modeling philosophy devised here provides a valuable approach to solve general sound radiation problems for foldable, tessellated acoustic transducer constituents of arbitrary geometry.

  10. Wave energy absorption by ducks

    OpenAIRE

    Kurniawan, Adi

    2017-01-01

    We study the absorption of wave energy by a single and multiple cam-shaped bodies referred to as ducks. Numerical models are developed under the assumptions of linear theory. We consider wave absorption by a single duck as well as by two lines of ducks meeting at an angle.

  11. Wave energy absorption by ducks

    DEFF Research Database (Denmark)

    Kurniawan, Adi

    2018-01-01

    We study the absorption of wave energy by a single and multiple cam-shaped bodies referred to as ducks. Numerical models are developed under the assumptions of linear theory. We consider wave absorption by a single duck as well as by two lines of ducks meeting at an angle....

  12. Wave Dragon Wave Energy Converters Used as Coastal Protection

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke; Kofoed, Jens Peter

    2011-01-01

    This paper deals with wave energy converters used to reduce the wave height along shorelines. For this study the Wave Dragon wave energy converter is chosen. The wave height reduction from a single device has been evaluated from physical model tests in scale 1:51.8 of the 260 x 150 m, 24 kW/m model...... Spain, to evaluate the potential for reducing wave heights close the shore by means of Wave Dragons....

  13. Tunnel effect wave energy detection

    Science.gov (United States)

    Kaiser, William J. (Inventor); Waltman, Steven B. (Inventor); Kenny, Thomas W. (Inventor)

    1995-01-01

    Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

  14. Waves energy comes to surface

    International Nuclear Information System (INIS)

    Guezel, J.Ch.

    2006-01-01

    The wave- or thalasso-energy, potentially as promising as wind energy, have started to develop in Europe. Great Britain has already a good experience in this domain but France shows also ambitions in this beginning industry with several projects in progress. This article makes an overview of the existing tide-, current- and wave-powered generators: tide mills, underwater hydro-turbines, immersed linear generators, air-compression systems, buoy systems, etc. (J.S.)

  15. Gravitational Waves and Dark Energy

    Directory of Open Access Journals (Sweden)

    Peter L. Biermann

    2014-12-01

    Full Text Available The idea that dark energy is gravitational waves may explain its strength and its time-evolution. A possible concept is that dark energy is the ensemble of coherent bursts (solitons of gravitational waves originally produced when the first generation of super-massive black holes was formed. These solitons get their initial energy as well as keep up their energy density throughout the evolution of the universe by stimulating emission from a background, a process which we model by working out this energy transfer in a Boltzmann equation approach. New Planck data suggest that dark energy has increased in strength over cosmic time, supporting the concept here. The transit of these gravitational wave solitons may be detectable. Key tests include pulsar timing, clock jitter and the radio background.

  16. Development of a Flexible Broadband Rayleigh Waves Comb Transducer with Nonequidistant Comb Interval for Defect Detection of Thick-Walled Pipelines.

    Science.gov (United States)

    Zhao, Huamin; He, Cunfu; Yan, Lyu; Zhang, Haijun

    2018-03-02

    It is necessary to develop a transducer that can quickly detect the inner and outer wall defects of thick-walled pipes, in order to ensure the safety of such pipes. In this paper, a flexible broadband Rayleigh-waves comb transducer based on PZT (lead zirconate titanate) for defect detection of thick-walled pipes is studied. The multiple resonant coupling theory is used to expand the transducer broadband and the FEA (Finite Element Analysis) method is used to optimize transducer array element parameters. Optimization results show that the best array element parameters of the transducer are when the transducer array element length is 30 mm, the thickness is 1.2 mm, the width of one end of is 1.5 mm, and the other end is 3 mm. Based on the optimization results, such a transducer was fabricated and its performance was tested. The test results were consistent with the finite-element simulation results, and the -3 dB bandwidth of the transducer reached 417 kHz. Transducer directivity test results show that the Θ -3dB beam width was equal to 10 °, to meet the defect detection requirements. Finally, defects of thick-walled pipes were detected using the transducer. The results showed that the transducer could detect the inner and outer wall defects of thick-walled pipes within the bandwidth.

  17. Proposed electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  18. Optimization of a Focusable and Rotatable Shear-Wave Periodic Permanent Magnet Electromagnetic Acoustic Transducers for Plates Inspection.

    Science.gov (United States)

    Song, Xiaochun; Qiu, Gongzhe

    2017-11-24

    Due to the symmetry of conventional periodic-permanent-magnet electromagnetic acoustic transducers (PPM EMATs), two shear (SH) waves can be generated and propagated simultaneously in opposite directions, which makes the signal recognition and interpretation complicatedly. Thus, this work presents a new SH wave PPM EMAT design, rotating the parallel line sources to realize the wave beam focusing in a single-direction. The theoretical model of distributed line sources was deduced firstly, and the effects of some parameters, such as the inner coil width, adjacent line sources spacing and the angle between parallel line sources, on SH wave focusing and directivity were studied mainly with the help of 3D FEM. Employing the proposed PPM EMATs, some experiments are carried out to verify the reliability of FEM simulation. The results indicate that rotating the parallel line sources can strength the wave on the closing side of line sources, decreasing the inner coil width and the adjacent line sources spacing can improve the amplitude and directivity of signals excited by transducers. Compared with traditional PPM EMATs, both the capacity of unidirectional excitation and directivity of the proposed PPM EMATs are improved significantly.

  19. Optimization of a Focusable and Rotatable Shear-Wave Periodic Permanent Magnet Electromagnetic Acoustic Transducers for Plates Inspection

    Directory of Open Access Journals (Sweden)

    Xiaochun Song

    2017-11-01

    Full Text Available Due to the symmetry of conventional periodic-permanent-magnet electromagnetic acoustic transducers (PPM EMATs, two shear (SH waves can be generated and propagated simultaneously in opposite directions, which makes the signal recognition and interpretation complicatedly. Thus, this work presents a new SH wave PPM EMAT design, rotating the parallel line sources to realize the wave beam focusing in a single-direction. The theoretical model of distributed line sources was deduced firstly, and the effects of some parameters, such as the inner coil width, adjacent line sources spacing and the angle between parallel line sources, on SH wave focusing and directivity were studied mainly with the help of 3D FEM. Employing the proposed PPM EMATs, some experiments are carried out to verify the reliability of FEM simulation. The results indicate that rotating the parallel line sources can strength the wave on the closing side of line sources, decreasing the inner coil width and the adjacent line sources spacing can improve the amplitude and directivity of signals excited by transducers. Compared with traditional PPM EMATs, both the capacity of unidirectional excitation and directivity of the proposed PPM EMATs are improved significantly.

  20. Direct Drive Wave Energy Buoy

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, Kenneth E. [Columbia Power Technologies, Inc.; Lenee-Bluhm, Pukha [Columbia Power Technologies, Inc.; Prudell, Joseph H. [Columbia Power Technologies, Inc.; Schacher, Alphonse A. [Columbia Power Technologies, Inc.; Hammagren, Erik J. [Columbia Power Technologies, Inc.; Zhang, Zhe [Columbia Power Technologies, Inc.

    2013-07-29

    The most prudent path to a full-scale design, build and deployment of a wave energy conversion (WEC) system involves establishment of validated numerical models using physical experiments in a methodical scaling program. This Project provides essential additional rounds of wave tank testing at 1:33 scale and ocean/bay testing at a 1:7 scale, necessary to validate numerical modeling that is essential to a utility-scale WEC design and associated certification.

  1. CMOS circuits for electromagnetic vibration transducers interfaces for ultra-low voltage energy harvesting

    CERN Document Server

    Maurath, Dominic

    2015-01-01

    Chip-integrated power management solutions are a must for ultra-low power systems. This enables not only the optimization of innovative sensor applications. It is also essential for integration and miniaturization of energy harvesting supply strategies of portable and autonomous monitoring systems. The book particularly addresses interfaces for energy harvesting, which are the key element to connect micro transducers to energy storage elements. Main features of the book are: - A comprehensive technology and application review, basics on transducer mechanics, fundamental circuit and control design, prototyping and testing, up to sensor system supply and applications. - Novel interfacing concepts - including active rectifiers, MPPT methods for efficient tracking of DC as well as AC sources, and a fully-integrated charge pump for efficient maximum AC power tracking at sub-100µW ultra-low power levels. The chips achieve one of widest presented operational voltage range in standard CMOS technology: 0.44V to over...

  2. Fabrication of Cheap Optical Transducers (CHOTs) on film carriers for in-situ application and generation of surface acoustic waves

    International Nuclear Information System (INIS)

    Ageeva, V; Stratoudaki, T; Clark, M; Somekh, M G

    2015-01-01

    Cheap optical transducers (CHOTs) are patterns on the surface of a component activated by lasers to generate and detect ultrasound. Excited optically, with minimal surface impact, and fully customizable, CHOTs provide a simple alternative to conventional piezoelectric transducers, offering wireless, remote operation. Of particular interest is application of CHOTs for in-situ ultrasonic inspection of hard-to reach and complex-geometry components such as those of aero-engines. A suitable fabrication method has been developed to allow in-situ application of CHOTs onto large size and curved components, as well as those already in service, challenging for current laboratory-based micro-patterning methods. This work describes the fabrication of a transferable g-CHOT for generation of ultrasound. The g- CHOT has been made on an SU8 carrier film using a sacrificial polystyrene layer, allowing the transducer to be transferred from the substrate and subsequently delivered and applied to the surface of the sample in-situ. The functionality of the fabricated transducer is demonstrated by detection of the Surface Acoustic Waves (SAW) generated by the g-CHOT transferred onto glass and aluminium samples

  3. PMN-PT single crystal, high-frequency ultrasonic needle transducers for pulsed-wave Doppler application.

    Science.gov (United States)

    Zhou, Qifa; Xu, Xiaochen; Gottlieb, Emanuel J; Sun, Lei; Cannata, Jonathan M; Ameri, Hossein; Humayun, Mark S; Han, Pengdi; Shung, K Kirk

    2007-03-01

    High-frequency needle ultrasound transducers with an aperture size of 0.4 mm were fabricated using lead magnesium niobate-lead titanate (PMN-33% PT) as the active piezoelectric material. The active element was bonded to a conductive silver particle matching layer and a conductive epoxy backing through direct contact curing. An outer matching layer of parylene was formed by vapor deposition. The active element was housed within a polyimide tube and a 20-gauge needle housing. The magnitude and phase of the electrical impedance of the transducer were 47 omega and -38 degrees, respectively. The measured center frequency and -6 dB fractional bandwidth of the PMN-PT needle transducer were 44 MHz and 45%, respectively. The two-way insertion loss was approximately 15 dB. In vivo high-frequency, pulsed-wave Doppler patterns of blood flow in the posterior portion and in vitro ultrasonic backscatter microscope (UBM) images of the rabbit eye were obtained with the 44-MHz needle transducer.

  4. Structural Diagnostics of CFRP Composite Aircraft Components by Ultrasonic Guided Waves and Built-In Piezoelectric Transducers

    Energy Technology Data Exchange (ETDEWEB)

    Matt, Howard M. [Univ. of California, San Diego, CA (United States)

    2006-01-01

    To monitor in-flight damage and reduce life-cycle costs associated with CFRP composite aircraft, an autonomous built-in structural health monitoring (SHM) system is preferred over conventional maintenance routines and schedules. This thesis investigates the use of ultrasonic guided waves and piezoelectric transducers for the identification and localization of damage/defects occurring within critical components of CFRP composite aircraft wings, mainly the wing skin-to-spar joints. The guided wave approach for structural diagnostics was demonstrated by the dual application of active and passive monitoring techniques. For active interrogation, the guided wave propagation problem was initially studied numerically by a semi-analytical finite element method, which accounts for viscoelastic damping, in order to identify ideal mode-frequency combinations sensitive to damage occurring within CFRP bonded joints. Active guided wave tests across three representative wing skin-to-spar joints at ambient temperature were then conducted using attached Macro Fiber Composite (MFC) transducers. Results from these experiments demonstrate the importance of intelligent feature extraction for improving the sensitivity to damage. To address the widely neglected effects of temperature on guided wave base damage identification, analytical and experimental analyses were performed to characterize the influence of temperature on guided wave signal features. In addition, statistically-robust detection of simulated damage in a CFRP bonded joint was successfully achieved under changing temperature conditions through a dimensionally-low, multivariate statistical outlier analysis. The response of piezoceramic patches and MFC transducers to ultrasonic Rayleigh and Lamb wave fields was analytically derived and experimentally validated. This theory is useful for designing sensors which possess optimal sensitivity toward a given mode-frequency combination or for predicting the frequency dependent

  5. Handbook of ocean wave energy

    CERN Document Server

    Kofoed, Jens

    2017-01-01

    This book is open access under a CC BY-NC 2.5 license. This book offers a concise, practice-oriented reference-guide to the field of ocean wave energy. The ten chapters highlight the key rules of thumb, address all the main technical engineering aspects and describe in detail all the key aspects to be considered in the techno-economic assessment of wave energy converters. Written in an easy-to-understand style, the book answers questions relevant to readers of different backgrounds, from developers, private and public investors, to students and researchers. It is thereby a valuable resource for both newcomers and experienced practitioners in the wave energy sector.

  6. Evaluation and performance enhancement of a pressure transducer under flows, waves, and a combination of flows and waves

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desa, J.A.E.; Foden, P.; Taylor, K.; McKeown, J.; Desa, E.

    plate. This enhancement is likely to have been achieved because of the isolation of the pressure inlet from the separated flows and vortices generated by the transducer housing. Flow disturbances, generated by nearby solid structures, deteriorated...

  7. Ocean Wave Energy: Underwater Substation System for Wave Energy Converters

    International Nuclear Information System (INIS)

    Rahm, Magnus

    2010-01-01

    This thesis deals with a system for operation of directly driven offshore wave energy converters. The work that has been carried out includes laboratory testing of a permanent magnet linear generator, wave energy converter mechanical design and offshore testing, and finally design, implementation, and offshore testing of an underwater collector substation. Long-term testing of a single point absorber, which was installed in March 2006, has been performed in real ocean waves in linear and in non-linear damping mode. The two different damping modes were realized by, first, a resistive load, and second, a rectifier with voltage smoothing capacitors and a resistive load in the DC-link. The loads are placed on land about 2 km east of the Lysekil wave energy research site, where the offshore experiments have been conducted. In the spring of 2009, another two wave energy converter prototypes were installed. Records of array operation were taken with two and three devices in the array. With two units, non-linear damping was used, and with three units, linear damping was employed. The point absorbers in the array are connected to the underwater substation, which is based on a 3 m3 pressure vessel standing on the seabed. In the substation, rectification of the frequency and amplitude modulated voltages from the linear generators is made. The DC voltage is smoothened by capacitors and inverted to 50 Hz electrical frequency, transformed and finally transmitted to the on-shore measuring station. Results show that the absorption is heavily dependent on the damping. It has also been shown that by increasing the damping, the standard deviation of electrical power can be reduced. The standard deviation of electrical power is reduced by array operation compared to single unit operation. Ongoing and future work include the construction and installation of a second underwater substation, which will connect the first substation and seven new WECs

  8. Vibration energy harvesting in a small channel fluid flow using piezoelectric transducer

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Md. Mehedi, E-mail: buetmehedi10@gmail.com; Hossain, Md. Yeam, E-mail: yeamhossain@gmail.com; Mazumder, Rakib, E-mail: rakibmazumder46075@gmail.com; Rahman, Roussel, E-mail: roussel.rahman@gmail.com; Rahman, Md. Ashiqur, E-mail: ashiqurrahman@me.buet.ac.bd [Department of Mechanical Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka-1000 (Bangladesh)

    2016-07-12

    This work is aimed at developing a way to harvest energy from a fluid stream with the application of piezoelectric transducers in a small channel. In this COMSOL Multiphysics based simulation study, it is attempted to harvest energy from the abundant renewable source of energy available in the form of kinetic energy of naturally occurring flow of fluids. The strategy involves harnessing energy from a fluid-actuator through generation of couples, eddies and vortices, resulting from the stagnation and separation of flow around a semi-circular bluff-body attached to a cantilever beam containing a piezoceramic layer. Fluctuation of fluidic pressure impulse on the beam due to vortex shedding and varying lift forces causes the flexible cantilever beam to oscillate in the direction normal to the fluid flow in a periodic manner. The periodic application and release of a mechanical strain upon the beam effected a generation of electric potential within the piezoelectric layer, thus enabling extraction of electrical energy from the kinetic energy of the fluid. The piezoelectric material properties and transducer design are kept unchanged throughout the study, whereas the configuration is tested with different fluids and varying flow characteristics. The size and geometry of the obstructing entity are systematically varied to closely inspect the output from different iterations and for finding the optimum design parameters. The intermittent changes in the generated forces and subsequent variation in the strain on the beam are also monitored to find definitive relationship with the electrical energy output.

  9. Direct Drive Wave Energy Buoy

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, Kenneth [Columbia Power Technologies, Inc., Charlottesville, VA (United States); Lamb, Bradford [Columbia Power Technologies, Inc., Charlottesville, VA (United States); Prudell, Joseph [Columbia Power Technologies, Inc., Charlottesville, VA (United States); Hammagren, Erik [Columbia Power Technologies, Inc., Charlottesville, VA (United States); Lenee-Bluhm, Pukha [Columbia Power Technologies, Inc., Charlottesville, VA (United States)

    2016-08-22

    This Project aims to satisfy objectives of the DOE’s Water Power Program by completing a system detailed design (SDD) and other important activities in the first phase of a utility-scale grid-connected ocean wave energy demonstration. In early 2012, Columbia Power (CPwr) had determined that further cost and performance optimization was necessary in order to commercialize its StingRAY wave energy converter (WEC). CPwr’s progress toward commercialization, and the requisite technology development path, were focused on transitioning toward a commercial-scale demonstration. This path required significant investment to be successful, and the justification for this investment required improved annual energy production (AEP) and lower capital costs. Engineering solutions were developed to address these technical and cost challenges, incorporated into a proposal to the US Department of Energy (DOE), and then adapted to form the technical content and statement of project objectives of the resulting Project (DE-EE0005930). Through Project cost-sharing and technical collaboration between DOE and CPwr, and technical collaboration with Oregon State University (OSU), National Renewable Energy Lab (NREL) and other Project partners, we have demonstrated experimentally that these conceptual improvements have merit and made significant progress towards a certified WEC system design at a selected and contracted deployment site at the Wave Energy Test Site (WETS) at the Marine Corps Base in Oahu, HI (MCBH).

  10. A system of two piezoelectric transducers and a storage circuit for wireless energy transmission through a thin metal wall.

    Science.gov (United States)

    Hu, Hongping; Hu, Yuantai; Chen, Chuanyao; Wang, Ji

    2008-10-01

    A system to wirelessly convey electric energy through a thin metal wall is proposed in the paper, where 2 piezoelectric transducers are used to realize energy transformation between electric and mechanical, and a rechargeable battery is employed to store the transmitted energy. To integrate them as a whole, an interface of a modulating circuit is applied between the transducer system and the storage battery. In addition, a synchronized switch harvesting on inductor in parallel with the transducer system is introduced to artificially extend the closed interval of the modulating circuit. The process of transmitting energy is computed, and the performance of the transducer system is optimized in detail for a prescribed external electric source. The results obtained are useful for understanding and designing wireless energy supply systems.

  11. Key features of wave energy.

    Science.gov (United States)

    Rainey, R C T

    2012-01-28

    For a weak point source or dipole, or a small body operating as either, we show that the power from a wave energy converter (WEC) is the product of the particle velocity in the waves, and the wave force (suitably defined). There is a thus a strong analogy with a wind or tidal turbine, where the power is the product of the fluid velocity through the turbine, and the force on it. As a first approximation, the cost of a structure is controlled by the force it has to carry, which governs its strength, and the distance it has to be carried, which governs its size. Thus, WECs are at a disadvantage compared with wind and tidal turbines because the fluid velocities are lower, and hence the forces are higher. On the other hand, the distances involved are lower. As with turbines, the implication is also that a WEC must make the most of its force-carrying ability-ideally, to carry its maximum force all the time, the '100% sweating WEC'. It must be able to limit the wave force on it in larger waves, ultimately becoming near-transparent to them in the survival condition-just like a turbine in extreme conditions, which can stop and feather its blades. A turbine of any force rating can achieve its maximum force in low wind speeds, if its diameter is sufficiently large. This is not possible with a simple monopole or dipole WEC, however, because of the 'nλ/2π' capture width limits. To achieve reasonable 'sweating' in typical wave climates, the force is limited to about 1 MN for a monopole device, or 2 MN for a dipole. The conclusion is that the future of wave energy is in devices that are not simple monopoles or dipoles, but multi-body devices or other shapes equivalent to arrays.

  12. Assessing wave energy effects on biodiversity: the wave hub experience.

    Science.gov (United States)

    Witt, M J; Sheehan, E V; Bearhop, S; Broderick, A C; Conley, D C; Cotterell, S P; Crow, E; Grecian, W J; Halsband, C; Hodgson, D J; Hosegood, P; Inger, R; Miller, P I; Sims, D W; Thompson, R C; Vanstaen, K; Votier, S C; Attrill, M J; Godley, B J

    2012-01-28

    Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal meta-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects-both positive and negative.

  13. Coherent Wave Measurement Buoy Arrays to Support Wave Energy Extraction

    Science.gov (United States)

    Spada, F.; Chang, G.; Jones, C.; Janssen, T. T.; Barney, P.; Roberts, J.

    2016-02-01

    Wave energy is the most abundant form of hydrokinetic energy in the United States and wave energy converters (WECs) are being developed to extract the maximum possible power from the prevailing wave climate. However, maximum wave energy capture is currently limited by the narrow banded frequency response of WECs as well as extended protective shutdown requirements during periods of large waves. These limitations must be overcome in order to maximize energy extraction, thus significantly decreasing the cost of wave energy and making it a viable energy source. Techno-economic studies of several WEC devices have shown significant potential to improve wave energy capture efficiency through operational control strategies that incorporate real-time information about local surface wave motions. Integral Consulting Inc., with ARPA-E support, is partnering with Sandia National Laboratories and Spoondrift LLC to develop a coherent array of wave-measuring devices to relay and enable the prediction of wave-resolved surface dynamics at a WEC location ahead of real time. This capability will provide necessary information to optimize power production of WECs through control strategies, thereby allowing for a single WEC design to perform more effectively across a wide range of wave environments. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000514.

  14. Test rig with active damping control for the simultaneous evaluation of vibration control and energy harvesting via piezoelectric transducers

    OpenAIRE

    Perfetto, Sara; Rohlfing, Jens; Infante, Francesco; Mayer, Dirk; Herold, Sven

    2016-01-01

    Piezoelectric transducers can be used to harvest electrical energy from structural vibrations in order to power continuously operating condition monitoring systems local to where they operate. However, excessive vibrations can compromise the safe operation of mechanical systems. Therefore, absorbers are commonly used to control vibrations. With an integrated device, the mechanical energy that otherwise would be dissipated can be converted via piezoelectric transducers. Vibration absorbers are...

  15. Testing, Analysis and Control of Wave Dragon, Wave Energy Converter

    DEFF Research Database (Denmark)

    Tedd, James

    of the incident waves upon a wave device allows the possibility of accurately tuning the power-take off mechanism (the hydro-turbines for the Wave Dragon) to capture more energy. A digital filter method for performing this prediction in real-time with minimal computational effort is presented. Construction...... of digital filters is well known within signal processing, but their use for this application in Wave Energy is new. The filter must be designed carefully as the frequency components of waves travel at different speeds. Research presented in this thesis has advanced the development of the Wave Dragon device...

  16. Prototype Testing of the Wave Energy Converter Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Friis-Madsen, Erik

    2006-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period...... from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57!27 m wide and 237 tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world’s first offshore wave energy...... converter. The prototype is fully equipped with hydro turbines and automatic control systems, and is instrumented in order to monitor power production, wave climate, forces in mooring lines, stresses in the structure and movements of the Wave Dragon. In the period May 2003 to January 2005 an extensive...

  17. Prototype Testing of the Wave Energy Converter Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter Bak; Friis-Madsen, Erik

    2004-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period...... from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57 x 27 m wide and 237 tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world's first offshore wave energy...... converter. The prototype is fully equipped with hydro turbines and automatic control systems, and is instrumented in order to monitor power production, wave climate, forces in mooring lines, stresses in the structure and movements of the Wave Dragon. During the last months, extensive testing has started...

  18. Key Aspects of Wave Energy

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Nørgaard, Jørgen Harck

    2012-01-01

    Diversification of renewable energy sources is fundamental to ensure sustainability. In this contest, wave energy can provide a substantial contribution as soon as the sector breaks into the market. In order to accelerate shift from a technology to a market focus and reduce technical and non...... versatility into account can improve their overall performance and the value of investments. The way installation of devices can be perceived also by local communities can also benefit from this prospective thus providing and additional tool to overcome the sector´s setbacks....

  19. Development of the Wave Energy Converter -Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, Hans Christian

    2000-01-01

    2Over the years wave energy has gradually been brought into focus, as it has become clear that the fossil energy resources are limited, and cause large environmental problems, e.g. CO2 pollution. On this background a number of different wave energy converters have been proposed. In Denmark the go...

  20. Wave energy : from demonstration to commercialization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The Wave Energy Centre is a non-profit organization dedicated to the development and marketing of ocean wave energy devices through technical and strategic support to companies and research and development institutions. WEC provides access to researchers to associated test infrastructures for testing and demonstration of wave energy structures. This presentation described the current status of wave energy. Public policies that support wave energy were also highlighted. Wave energy technology is currently in the demonstration phase, with several pilot plants and prototypes in service around the world. The first 2 offshore shoreline ocean wave current pilot plants were constructed in 2000. This presentation identified the 12 near or offshore pilot plants that were in operation by 2007. The pilot plants represent 5 basic different concepts with many different designs. The world's first commercial park was launched in 2007 in Portugal. The Pelamis wave farm uses three Pelamis P-750 machines with a capacity of 2.25 megawatts. figs.

  1. Experimental Study on the WavePiston Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Angelelli, E.

    This report presents the results of an experimental study of the power performance of the WavePiston wave energy converter. It focuses mainly on evaluating the power generating capabilities of the device and the effect of the following issues: Scaling ratios PTO loading Wave height and wave period...... dependency Oblique incoming waves Distance between plates During the study, the model supplied by the client, WavePiston, has been rigorously tested as all the anticipated tests have been done thoroughly and during all tests, good quality data has been obtained from all the sensors....

  2. Problems of application of wave energy

    International Nuclear Information System (INIS)

    D'yakov, A.F.; Morozkina, M.V.

    1993-01-01

    Technical solutions of using the energy both sea waves and lake ones are analyzed. Mathematical description of wave processes and phenomena as well as techniques of selection and conversion of the wave energy are given. Wave energy electromechanical converters are considered. Great attention is paid to linear generators of electromechanical converters eddy currents in massive sections of these generators and features of their calculation. Techniques for optimization of the linear generator parameters are shown. 60 refs

  3. Wave Induced Loads on the LEANCON Wave Energy Converter

    DEFF Research Database (Denmark)

    Frigaard, Peter; Kofoed, Jens Peter; Beserra, Eliab Ricarte

    This report is a product of the co-operation agreement between Aalborg University and LEANCON (by Kurt Due Rasmussen) on the evaluation and development of the LEANCON wave energy converter (WEC). The work reported here has focused on evaluation of the wave induced loads on the device, based...... in the laboratory, all under the supervision of the personnel of the Wave Energy Research Group at Department of Civil Engineering, Aalborg University....

  4. Model of a Piezoelectric Transducer

    Science.gov (United States)

    Goodenow, Debra

    2004-01-01

    It's difficult to control liquid and gas in propellant tanks in zero gravity. A possible a design would utilize acoustic liquid manipulation (ALM) technology which uses ultrasonic beams conducted through a liquid and solid media, to push gas bubbles in the liquid to desirable locations. We can propel and control the bubble with acoustic radiation pressure by aiming the acoustic waves on the bubble s surface. This allows us to design a so called smart tank in which the ALM devices transfer the gas to the outer wall of the tank and isolating the liquid in the center. Because the heat transfer rate of a gas is lower of that of the liquid it would substantially decrease boil off and provide of for a longer storage life. The ALM beam is composed of little wavelets which are individual waves that constructively interfere with each other to produce a single, combined acoustic wave front. This is accomplished by using a set of synchronized ultrasound transducers arranged in an array. A slight phase offset of these elements allows us to focus and steer the beam. The device that we are using to produce the acoustic beam is called the piezoelectric transducer. This device converts electrical energy to mechanical energy, which appears in the form of acoustic energy. Therefore the behavior of the device is dependent on both the mechanical characteristics, such as its density, cross-sectional area, and its electrical characteristics, such as, electric flux permittivity and coupling factor. These devices can also be set up in a number of modes which are determined by the way the piezoelectric device is arranged, and the shape of the transducer. For this application we are using the longitudinal or thickness mode for our operation. The transducer also vibrates in the lateral mode, and one of the goals of my project is to decrease the amount of energy lost to the lateral mode. To model the behavior of the transducers I will be using Pspice, electric circuit modeling tool, to

  5. Experiments on the WavePiston, Wave Energy Converter

    DEFF Research Database (Denmark)

    Angelelli, E.; Zanuttigh, B.; Kofoed, Jens Peter

    2011-01-01

    This paper analyses the performance of a new Wave Energy Converter (WEC) of the Oscillating Water Column type (OWC), named WavePiston. This near-shore floating device is composed of plates (i.e. energy collectors) sliding around a cylinder, that is placed perpendicular to the shore. Tests...... in the wave basin at Aalborg University allowed to investigate power production in the North Sea typical wave climate, with varying design parameters such as plate dimensions and their mutual distance. The power produced per meter by each collector is about the 5% of the available wave power. Experimental...... results and survivability considerations suggest that the WavePiston would be particularly suited for installations in milder seas. An example application is therefore presented in the Mediterranean Sea, off-shore the island of Sicily. In this case, each collector harvests the 10% of the available wave...

  6. Possibility of cellulose-based electro-active paper energy scavenging transducer.

    Science.gov (United States)

    Abas, Zafar; Kim, Heung Soo; Zhai, Lindong; Kim, Jaehwan; Kim, Joo Hyung

    2014-10-01

    In this paper, a cellulose-based Electro-Active Paper (EAPap) energy scavenging transducer is presented. Cellulose is proven as a smart material, and exhibits piezoelectric effect. Specimens were prepared by coating gold electrodes on both sides of cellulose film. The fabricated specimens were tested by a base excited aluminum cantilever beam at resonant frequency. Different tests were performed with single and multiple parallel connected electrodes coated on the cellulose film. A maximum of 131 mV output voltage was measured, when three electrodes were connected in parallel. It was observed that voltage output increases significantly with the area of electrodes. From these results, it can be concluded that the piezoelectricity of cellulose-based EAPap can be used in energy transduction application.

  7. Investigation of Wave Transmission from a Floating Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke

    2012-01-01

    This paper focuses on the calibration of the MIKE21BW model against the measured wave height reduction behind a 24 kW/m Wave Dragon (WD) wave energy converter. A numerical model is used to determine the wave transmission through the floating WD in varying wave conditions. The transmission obtained...

  8. Dissipation of Wave Energy by Cohesive Sediments

    National Research Council Canada - National Science Library

    Kaihatu, James M; Sheremet, Alexandru

    2004-01-01

    Wave energy dissipation by bottom muds is studied. A dissipation mechanism which contains explicit expressions of wavenumber modification due to a viscous bottom fluid is incorporated into a nonlinear wave shoaling model...

  9. Sensitivity of wave energy to climate change

    OpenAIRE

    Harrison, Gareth; Wallace, Robin

    2005-01-01

    Wave energy will have a key role in meeting renewable energy targets en route to a low carbon economy. However, in common with other renewables, it may be sensitive to changes in climate resulting from rising carbon emissions. Changes in wind patterns are widely anticipated and this will ultimately alter wave regimes. Indeed, evidence indicates that wave heights have been changing over the last 40 years, although there is no proven link to global warming. Changes in the wave climate will impa...

  10. Pneumatic pressure wave generator provides economical, simple testing of pressure transducers

    Science.gov (United States)

    Gaal, A. E.; Weldon, T. P.

    1967-01-01

    Testing device utilizes the change in pressure about a bias or reference pressure level produced by displacement of a center-driven piston in a closed cylinder. Closely controlled pneumatic pressure waves allow testing under dynamic conditions.

  11. Wave Energy Potential in the Latvian EEZ

    Science.gov (United States)

    Beriņš, J.; Beriņš, J.; Kalnačs, J.; Kalnačs, A.

    2016-06-01

    The present article deals with one of the alternative forms of energy - sea wave energy potential in the Latvian Exclusice Economic Zone (EEZ). Results have been achieved using a new method - VEVPP. Calculations have been performed using the data on wave parameters over the past five years (2010-2014). We have also considered wave energy potential in the Gulf of Riga. The conclusions have been drawn on the recommended methodology for the sea wave potential and power calculations for wave-power plant pre-design stage.

  12. The Crest Wing Wave Energy Device

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Antonishen, Michael Patrick

    to generate power. Model tests have been performed using scale models (length scale 1:30), provided by WaveEnergyFyn, in regular and irregular wave states that can be found in Assessment of Wave Energy Devices. Best Practice as used in Denmark (Frigaard et al., 2008). The tests were carried out at Dept....... of Civil Engineering, Aalborg University (AAU) in the 3D deep water wave tank. The displacement and force applied to a power take off system, provided by WaveEnergyFyn, were measured and used to calculate mechanical power available to the power take off....

  13. Introducing wave energy into the renewable energy marketplace

    International Nuclear Information System (INIS)

    Petroncini, S.; Yemm, R.W.

    2001-01-01

    The energy sector in Europe is going through a dynamic evolution that sees the introduction and development of renewable energy and the re-emergence of a wave energy industry. Although wave energy is currently not economically competitive with mature technologies such as wind energy, the wave energy world-wide resource of 2 TW has a potential contribution in the electricity market of 2000TWh/year. Denmark, Ireland, Portugal, Norway and the UK have been analysed in terms of wave energy resources, renewable energy market structure and political and economic support for the introduction of wave energy into the marketplace. The results have been used together with Ocean Power Delivery Ltd to develop an initial market survey for the wave energy converter Pelamis. (au)

  14. Controller for a wave energy converter

    Science.gov (United States)

    Wilson, David G.; Bull, Diana L.; Robinett, III, Rush D.

    2015-09-22

    A wave energy converter (WEC) is described, the WEC including a power take off (PTO) that converts relative motion of bodies of the WEC into electrical energy. A controller controls operation of the PTO, causing the PTO to act as a motor to widen a wave frequency spectrum that is usable to generate electrical energy.

  15. Ocean floor mounting of wave energy converters

    Science.gov (United States)

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  16. Investigations of DC power supplies with optoelectronic transducers and RF energy converters

    Science.gov (United States)

    Guzowski, B.; Gozdur, R.; Bernacki, L.; Lakomski, M.

    2016-04-01

    Fiber Distribution Cabinets (FDC) monitoring systems are increasingly popular. However it is difficult to realize such system in passive FDC, due to lack of source of power supply. In this paper investigation of four different DC power supplies with optoelectronic transducers is described. Two converters: photovoltaic power converter and PIN photodiode can convert the light transmitted through the optical fiber to electric energy. Solar cell and antenna RF-PCB are also tested. Results presented in this paper clearly demonstrate that it is possible to build monitoring system in passive FDC. During the tests maximum obtained output power was 11 mW. However all converters provided enough power to excite 32-bit microcontroller with ARM-cores and digital thermometer.

  17. Lead-free piezoelectric transducers for vibration-based energy harvesting devices

    Energy Technology Data Exchange (ETDEWEB)

    Roescher, Mark

    2011-11-15

    Future applications like piezoelectric energy harvesters in addition with increasing environmental awareness ultimately demand novel sophisticated material systems in the field of piezoelectrics as an alternative to the long-established system lead-zirconate-titanate. In this publication state-of-the-art microgenerators have been designed to possess nonlinear Duffing oscillator characteristics. It is shown by measurement and simulation that lead-zirconate-titanate may hence no longer be the first choice in material selection for a piezoelectric microgenerator. Polyvinylidene fluoride has been integrated in a piezoelectric microgenerator and identified as an extraordinarily promising material system for transducer applications being highly insusceptible to stretching induced material failure. Finally, a fundamentally new chemical synthesis approach has been developed for the fabrication of potassium-sodium-niobate films that may also be suitable for other complex oxides.

  18. Wave energy input into the Ekman layer

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper is concerned with the wave energy input into the Ekman layer, based on 3 observational facts that surface waves could significantly affect the profile of the Ekman layer. Under the assumption of constant vertical diffusivity, the analytical form of wave energy input into the Ekman layer is derived. Analysis of the energy balance shows that the energy input to the Ekman layer through the wind stress and the interaction of the Stokes-drift with planetary vorticity can be divided into two kinds. One is the wind energy input, and the other is the wave energy input which is dependent on wind speed, wave characteristics and the wind direction relative to the wave direction. Estimates of wave energy input show that wave energy input can be up to 10% in high-latitude and high-wind speed areas and higher than 20% in the Antarctic Circumpolar Current, compared with the wind energy input into the classical Ekman layer. Results of this paper are of significance to the study of wave-induced large scale effects.

  19. Modal content based damage indicators and phased array transducers for structural health monitoring of aircraft structures using ultrasonic guided waves

    Science.gov (United States)

    Ren, Baiyang

    Composite materials, especially carbon fiber reinforced polymers (CFRP), have been widely used in the aircraft industry because of their high specific strength and stiffness, resistance to corrosion and good fatigue life. Due to their highly anisotropic material properties and laminated structures, joining methods like bolting and riveting are no longer appropriate for joining CFRP since they initiate defects during the assembly and severely compromise the integrity of the structure; thus new techniques for joining CFRP are highly demanded. Adhesive bonding is a promising method because it relieves stress concentration, reduces weight and provides smooth surfaces. Additionally, it is a low-cost alternative to the co-cured method which is currently used to manufacture components of aircraft fuselage. Adhesive defects, disbonds at the interface between adherend and adhesive layer, are focused on in this thesis because they can be initialized by either poor surface preparation during the manufacturing or fatigue loads during service. Aircraft need structural health monitoring (SHM) systems to increase safety and reduce loss, and adhesive bonds usually represent the hotspots of the assembled structure. There are many nondestructive evaluation (NDE) methods for bond inspection. However, these methods cannot be readily integrated into an SHM system because of the bulk size and weight of the equipment and requirement of accessibility to one side of the bonded joint. The first objective of this work is to develop instruments, actuators, sensors and a data acquisition system for SHM of bond lines using ultrasonic guided waves which are well known to be able to cover large volume of the structure and inaccessible regions. Different from widely used guided wave sensors like PZT disks, the new actuators, piezoelectric fiber composite (PFC) phased array transducers0 (PAT), can control the modal content of the excited waves and the new sensors, polyvinylidene fluoride (PVDF

  20. Temperature dependence of energy-transducing functions and inhibitor sensitivity in chloroplasts

    Energy Technology Data Exchange (ETDEWEB)

    Schuurmans, J.J.; Veerman, E.C.I.; Francke, J.A.; Torres-Pereira, J.M.G.; Kraayenhof, R.

    1984-01-01

    A comparative analysis of the temperature dependence of energy-transducing reactions in spinach (Spinacia oleracea) chloroplasts and their sensitivity for uncouplers and energy-transfer inhibitors at different temperatures is presented. Arrhenius plots reveal two groups of transitions, around 19/sup 0/C and around 12/sup 0/C. Activities that show transitions around 19/sup 0/C include linear electron flow from water to ferricyanide, its coupled photophosphorylation, the dark-release of the fluorescent probe atebrin, and the slow component of the 515 nm (carotenoid) absorbance decay after a flash. The transitions around 12/sup 0/C are observed with pyocyanine-mediated cyclic photophosphorylation, light- and dithioerythritol-activated ATP hydrolysis, the dark-release of protons, and the fast 515 nm decay component. It is suggested that both groups of temperature transitions are determined by proton displacements in different domains of the exposed thylakoid membranes. The effects of various uncouplers and an energy-transfer inhibitor are temperature dependent. Some uncouplers also show a different relative inhibition of proton uptake and ATP synthesis at lower temperatures. The efficiency of energy transduction (ATP/e/sub 3/) varied with temperature and was optimal around 10/sup 0/C.

  1. Energy in a String Wave

    Science.gov (United States)

    Ng, Chiu-king

    2010-01-01

    When one end of a taut horizontal elastic string is shaken repeatedly up and down, a transverse wave (assume sine waveform) will be produced and travel along it. College students know this type of wave motion well. They know when the wave passes by, each element of the string will perform an oscillating up-down motion, which in mechanics is termed…

  2. Test rig with active damping control for the simultaneous evaluation of vibration control and energy harvesting via piezoelectric transducers

    International Nuclear Information System (INIS)

    Perfetto, S; Rohlfing, J; Infante, F; Mayer, D; Herold, S

    2016-01-01

    Piezoelectric transducers can be used to harvest electrical energy from structural vibrations in order to power continuously operating condition monitoring systems local to where they operate. However, excessive vibrations can compromise the safe operation of mechanical systems. Therefore, absorbers are commonly used to control vibrations. With an integrated device, the mechanical energy that otherwise would be dissipated can be converted via piezoelectric transducers. Vibration absorbers are designed to have high damping factors. Hence, the integration of transducers would lead to a low energy conversion. Efficient energy harvesters usually have low damping capabilities; therefore, they are not effective for vibration suppression. Thus, the design of an integrated device needs to consider the two conflicting requirements on the damping. This study focuses on the development of a laboratory test rig with a host structure and a vibration absorber with tunable damping via an active relative velocity feedback. A voice coil actuator is used for this purpose. To overcome the passive damping effects of the back electromagnetic force a novel voltage feedback control is proposed, which has been validated both in simulation and experimentally. The aim of this study is to have a test rig ready for the introduction of piezo-transducers and available for future experimental evaluations of the damping effect on the effectiveness of vibration reduction and energy harvesting efficiency. (paper)

  3. Test rig with active damping control for the simultaneous evaluation of vibration control and energy harvesting via piezoelectric transducers

    Science.gov (United States)

    Perfetto, S.; Rohlfing, J.; Infante, F.; Mayer, D.; Herold, S.

    2016-09-01

    Piezoelectric transducers can be used to harvest electrical energy from structural vibrations in order to power continuously operating condition monitoring systems local to where they operate. However, excessive vibrations can compromise the safe operation of mechanical systems. Therefore, absorbers are commonly used to control vibrations. With an integrated device, the mechanical energy that otherwise would be dissipated can be converted via piezoelectric transducers. Vibration absorbers are designed to have high damping factors. Hence, the integration of transducers would lead to a low energy conversion. Efficient energy harvesters usually have low damping capabilities; therefore, they are not effective for vibration suppression. Thus, the design of an integrated device needs to consider the two conflicting requirements on the damping. This study focuses on the development of a laboratory test rig with a host structure and a vibration absorber with tunable damping via an active relative velocity feedback. A voice coil actuator is used for this purpose. To overcome the passive damping effects of the back electromagnetic force a novel voltage feedback control is proposed, which has been validated both in simulation and experimentally. The aim of this study is to have a test rig ready for the introduction of piezo-transducers and available for future experimental evaluations of the damping effect on the effectiveness of vibration reduction and energy harvesting efficiency.

  4. Predictability of Wave Energy and Electricity Markets

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez

    2012-01-01

    The articlw addresses an important challenge ahead the integration of the electricity generated by wave energy conversion technologies into the electric grid. Particularly, it looks into the role of wave energy within the day-ahead electricity market. For that the predictability of the theoretical...... power outputs of three wave energy technologies in the Danish North Sea are examined. The simultaneous and co-located forecast and buoy-measured wave parameters at Hanstholm, Denmark, during a non-consecutive autumn and winter 3-month period form the basis of the investigation. The objective...

  5. The Indian wave energy programme- an overview

    International Nuclear Information System (INIS)

    Ravindran, M.; Jayashankar, V.; Jalihal, P.; Pathak, A.G.

    1997-01-01

    The Indian wave energy plant at Vizhinjam, Kerala has demonstrated that energy from a random source such as waves can be harnessed as electrical energy and exported via the local grid. This plant is based on the oscillating water column (OWC) principle. The research on wave energy in India has achieved a commendable status within a decade. A caisson was constructed in December 1990 at Vizhinjam and two generations of power modules have been tested as of today. The physical processes in the energy conversion are understood to a much greater extent, leading to a threefold increase in absolute power from the plant. Efforts are on to make the technology cost-effective

  6. Transmission of wave energy in curved ducts

    Science.gov (United States)

    Rostafinski, W.

    1973-01-01

    A formation of wave energy flow was developed for motion in curved ducts. A parametric study over a range of frequencies determined the ability of circular bends to transmit energy for the case of perfectly rigid walls.

  7. Energy in one-dimensional linear waves

    International Nuclear Information System (INIS)

    Repetto, C E; Roatta, A; Welti, R J

    2011-01-01

    This work is based on propagation phenomena that conform to the classical wave equation. General expressions of power, the energy conservation equation in continuous media and densities of the kinetic and potential energies are presented. As an example, we study the waves in a string and focused attention on the case of standing waves. The treatment is applicable to introductory science textbooks. (letters and comment)

  8. Condition Assessment of Foundation Piles and Utility Poles Based on Guided Wave Propagation Using a Network of Tactile Transducers and Support Vector Machines

    Directory of Open Access Journals (Sweden)

    Ulrike Dackermann

    2017-12-01

    Full Text Available This paper presents a novel non-destructive testing and health monitoring system using a network of tactile transducers and accelerometers for the condition assessment and damage classification of foundation piles and utility poles. While in traditional pile integrity testing an impact hammer with broadband frequency excitation is typically used, the proposed testing system utilizes an innovative excitation system based on a network of tactile transducers to induce controlled narrow-band frequency stress waves. Thereby, the simultaneous excitation of multiple stress wave types and modes is avoided (or at least reduced, and targeted wave forms can be generated. The new testing system enables the testing and monitoring of foundation piles and utility poles where the top is inaccessible, making the new testing system suitable, for example, for the condition assessment of pile structures with obstructed heads and of poles with live wires. For system validation, the new system was experimentally tested on nine timber and concrete poles that were inflicted with several types of damage. The tactile transducers were excited with continuous sine wave signals of 1 kHz frequency. Support vector machines were employed together with advanced signal processing algorithms to distinguish recorded stress wave signals from pole structures with different types of damage. The results show that using fast Fourier transform signals, combined with principal component analysis as the input feature vector for support vector machine (SVM classifiers with different kernel functions, can achieve damage classification with accuracies of 92.5% ± 7.5%.

  9. Levelized Cost of Energy of the Weptos wave energy converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter

    This report presents the cost of energy calculations of a wave energy array of 90 MW, consisting of 25 x 3.6 MW Weptos wave energy converters. The calculation has been made in analogy with a publically available document presented by the UK government, covering the case of a similar size wind...

  10. Teaching on ocean-wave-energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Falnes, J. [Norges teknisk-naturvitskaplege univ., Inst. for fysikk, Trondheim (Norway)

    2001-07-01

    Ocean-wave energy utilisation has for 27 years been a university research subject, in which the author has been active from the first year. In this paper he presents some information related to his teaching on the subject during many of these years. This includes teaching on the pre-university level and, in particular, development of the wave-energy module for an educational CD-ROM on sustainable technology and renewable energy. Education of the general public is very important. On the other hand teaching of doctor students and other wave-energy researchers is also a subject of the paper. (au)

  11. Hydraulic Response of the Wave Energy Converter Wave Dragon in Nissum Bredning

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter

    This report deals with the hydraulic performance of the wave energy converter Wave Dragon, Nissum Bredning prototype.......This report deals with the hydraulic performance of the wave energy converter Wave Dragon, Nissum Bredning prototype....

  12. Near-Shore Floating Wave Energy Converters

    DEFF Research Database (Denmark)

    Ruol, Piero; Zanuttigh, Barbara; Martinelli, Luca

    2011-01-01

    and transmission characteristics are approximated to functions of wave height, period and obliquity. Their order of magnitude are 20% and 80%, respectively. It is imagined that an array of DEXA is deployed in front of Marina di Ravenna beach (IT), a highly touristic site of the Adriatic Coast. Based on the CERC......Aim of this note is to analyse the possible application of a Wave Energy Converter (WEC) as a combined tool to protect the coast and harvest energy. Physical model tests are used to evaluate wave transmission past a near-shore floating WEC of the wave activated body type, named DEXA. Efficiency...

  13. Resonant Wave Energy Converters: Concept development

    International Nuclear Information System (INIS)

    Arena, Felice; Barbaro, Giuseppe; Fiamma, Vincenzo; Laface, Valentina; Malara, Giovanni; Romolo, Alessandra; Strati, Federica Mara

    2015-01-01

    The Resonant Wave Energy Converter (REWEC) is a device for converting sea wave energy to electrical energy. It belongs to the family of Oscillating Water Columns and is composed by an absorbing chamber connected to the open sea via a vertical duct. The paper gives a holistic view on the concept development of the device, starting from its implementation in the context of submerged breakwaters to the recently developed vertical breakwaters. [it

  14. Wave energy potential in Galicia (NW Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias, G.; Lopez, M.; Carballo, R.; Castro, A. [University of Santiago de Compostela, Hydraulic Engineering, E.P.S., Campus Universitario s/n, 27002 Lugo (Spain); Fraguela, J.A. [University of A Coruna, E.P.S., Campus de Esteiro s/n, Ferrol (Spain); Frigaard, P. [University of Aalborg, Sohngaardsholmsvej 57, DK 9000 (Denmark)

    2009-11-15

    Wave power presents significant advantages with regard to other CO{sub 2}-free energy sources, among which the predictability, high load factor and low visual and environmental impact stand out. Galicia, facing the Atlantic on the north-western corner of the Iberian Peninsula, is subjected to a very harsh wave climate; in this work its potential for energy production is assessed based on three-hourly data from a third generation ocean wave model (WAM) covering the period 1996-2005. Taking into account the results of this assessment along with other relevant considerations such as the location of ports, navigation routes, and fishing and aquaculture zones, an area is selected for wave energy exploitation. The transformation of the offshore wave field as it propagates into this area is computed by means of a nearshore wave model (SWAN) in order to select the optimum locations for a wave farm. Two zones emerge as those with the highest potential for wave energy exploitation. The large modifications in the available wave power resulting from relatively small changes of position are made apparent in the process. (author)

  15. Pitch catch ultrasonic study on unidirectional CFRP composite laminates using rayleigh wave transducers

    International Nuclear Information System (INIS)

    Park, Je Woong; Yang, In Young; Im, Kwang Hee; Hsu, David K.; Jung, Jong An

    2012-01-01

    The importance of carbon fiber reinforced plastics (CFRP) has been generally recognized, and CFRP composite laminates have become widely used. Thus, a nondestructive technique would be very useful for evaluating CF/epoxy composite laminates. A pitch catch UT signal is more sensitive than is a normal incidence backwall echo of a longitudinal wave in composites. The depth of the sampling volume where the pitch catch UT signal came from is relatively shallow, but the depth can be increased by increasing the separation distance of the transmitting and receiving probes. Moreover, a method is utilized to determine the porosity content of a composite lay up by processing micrograph images of the laminate. The porosity content of a composite structure is critical to the overall strength and performance of the structure. The image processing method developed utilizes software to process micrograph images of the test sample. The results from the image processing method are compared with existing data. Beam profile is characterized in unidirectional CFRP using pitch catch Rayleigh probes. The one sided and two sided pitch catch techniques are utilized to produce C scan images with the aid of an automatic scanner. The pitch catch ultrasonic signal corresponds with the simulated results of unidirectional CFRP composites

  16. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into waveenergy has been undertaken for decades, a significant increase in related activities has been seen in the recent years......, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes....... Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. Thisimplicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development...

  17. Probabilistic Design of Wave Energy Devices

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Kofoed, Jens Peter; Ferreira, C.B.

    2011-01-01

    Wave energy has a large potential for contributing significantly to production of renewable energy. However, the wave energy sector is still not able to deliver cost competitive and reliable solutions. But the sector has already demonstrated several proofs of concepts. The design of wave energy...... devices is a new and expanding technical area where there is no tradition for probabilistic design—in fact very little full scale devices has been build to date, so it can be said that no design tradition really exists in this area. For this reason it is considered to be of great importance to develop...... and advocate for a probabilistic design approach, as it is assumed (in other areas this has been demonstrated) that this leads to more economical designs compared to designs based on deterministic methods. In the present paper a general framework for probabilistic design and reliability analysis of wave energy...

  18. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    . Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. This implicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development......, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes...

  19. Energy harvesting with stacked dielectric elastomer transducers: Nonlinear theory, optimization, and linearized scaling law

    Science.gov (United States)

    Tutcuoglu, A.; Majidi, C.

    2014-12-01

    Using principles of damped harmonic oscillation with continuous media, we examine electrostatic energy harvesting with a "soft-matter" array of dielectric elastomer (DE) transducers. The array is composed of infinitely thin and deformable electrodes separated by layers of insulating elastomer. During vibration, it deforms longitudinally, resulting in a change in the capacitance and electrical enthalpy of the charged electrodes. Depending on the phase of electrostatic loading, the DE array can function as either an actuator that amplifies small vibrations or a generator that converts these external excitations into electrical power. Both cases are addressed with a comprehensive theory that accounts for the influence of viscoelasticity, dielectric breakdown, and electromechanical coupling induced by Maxwell stress. In the case of a linearized Kelvin-Voigt model of the dielectric, we obtain a closed-form estimate for the electrical power output and a scaling law for DE generator design. For the complete nonlinear model, we obtain the optimal electrostatic voltage input for maximum electrical power output.

  20. Energy Capture Optimization for an Adaptive Wave Energy Converter

    NARCIS (Netherlands)

    Barradas Berglind, Jose de Jesus; Meijer, Harmen; van Rooij, Marijn; Clemente Pinol, Silvia; Galvan Garcia, Bruno; Prins, Wouter; Vakis, Antonis I.; Jayawardhana, Bayu

    2016-01-01

    Wave energy has great potential as a renewable energy source, and can therefore contribute significantly to the proportion of renewable energy in the global energy mix. This is especially important since energy mixes with high renewable penetration have become a worldwide priority. One solution to

  1. Development of the Wave Energy Converter

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, Hans Christian

    2000-01-01

    The development of the wave energy converter Wave Dragon (WD) is presented. The WD is based on the overtopping principle. Initially a description of the WD is given. Then the development over time in terms of the various research and development projects working with the concept is described. Thi...

  2. Impacts of wave energy conversion devices on local wave climate: observations and modelling from the Perth Wave Energy Project

    Science.gov (United States)

    Hoeke, Ron; Hemer, Mark; Contardo, Stephanie; Symonds, Graham; Mcinnes, Kathy

    2016-04-01

    As demonstrated by the Australian Wave Energy Atlas (AWavEA), the southern and western margins of the country possess considerable wave energy resources. The Australia Government has made notable investments in pre-commercial wave energy developments in these areas, however little is known about how this technology may impact local wave climate and subsequently affect neighbouring coastal environments, e.g. altering sediment transport, causing shoreline erosion or accretion. In this study, a network of in-situ wave measurement devices have been deployed surrounding the 3 wave energy converters of the Carnegie Wave Energy Limited's Perth Wave Energy Project. This data is being used to develop, calibrate and validate numerical simulations of the project site. Early stage results will be presented and potential simulation strategies for scaling-up the findings to larger arrays of wave energy converters will be discussed. The intended project outcomes are to establish zones of impact defined in terms of changes in local wave energy spectra and to initiate best practice guidelines for the establishment of wave energy conversion sites.

  3. A sandwiched piezoelectric transducer with flex end-caps for energy harvesting in large force environments

    International Nuclear Information System (INIS)

    Kuang, Yang; Daniels, Alice; Zhu, Meiling

    2017-01-01

    This paper presents a sandwiched piezoelectric transducer (SPT) for energy harvesting in large force environments with increased load capacity and electric power output. The SPT uses (1) flex end-caps to amplify the applied load force so as to increase its power output and (2) a sandwiched piezoelectric-substrate structure to reduce the stress concentration in the piezoelectric material so as to increase the load capacity. A coupled piezoelectric-circuit finite element model (CPC-FEM) was developed, which is able to directly predict the electric power output of the SPT connected to a load resistor. The CPC-FEM was used to study the effects of various parameters of the SPT on the performance to obtain an optimal design. These parameters included the substrate thickness, the end-cap material and thickness, the electrode length, the joint length, the end-cap internal angle and the PZT thickness. A prototype with optimised parameters was tested on a loading machine, and the experimental results were compared with simulation. A good agreement was observed between simulation and experiment. When subjected to a 1 kN 2 Hz sinusoidal force applied by the loading machine, the SPT produced an average power of 4.68 mW. The application of the SPT as a footwear energy harvester was demonstrated by fitting the SPT into a boot and performing the tests on a treadmill, and the SPT generated an average power of 2.5 mW at a walking speed of 4.8 km h −1 . (paper)

  4. Image processing to optimize wave energy converters

    Science.gov (United States)

    Bailey, Kyle Marc-Anthony

    The world is turning to renewable energies as a means of ensuring the planet's future and well-being. There have been a few attempts in the past to utilize wave power as a means of generating electricity through the use of Wave Energy Converters (WEC), but only recently are they becoming a focal point in the renewable energy field. Over the past few years there has been a global drive to advance the efficiency of WEC. Placing a mechanical device either onshore or offshore that captures the energy within ocean surface waves to drive a mechanical device is how wave power is produced. This paper seeks to provide a novel and innovative way to estimate ocean wave frequency through the use of image processing. This will be achieved by applying a complex modulated lapped orthogonal transform filter bank to satellite images of ocean waves. The complex modulated lapped orthogonal transform filterbank provides an equal subband decomposition of the Nyquist bounded discrete time Fourier Transform spectrum. The maximum energy of the 2D complex modulated lapped transform subband is used to determine the horizontal and vertical frequency, which subsequently can be used to determine the wave frequency in the direction of the WEC by a simple trigonometric scaling. The robustness of the proposed method is provided by the applications to simulated and real satellite images where the frequency is known.

  5. Power Generation Using Mechanical Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Srinivasan Chandrasekaran

    2012-03-01

    Full Text Available Ocean wave energy plays a significant role in meeting the growing demand of electric power. Economic, environmental, and technical advantages of wave energy set it apart from other renewable energy resources. Present study describes a newly proposed Mechanical Wave Energy Converter (MEWC that is employed to harness heave motion of floating buoy to generate power. Focus is on the conceptual development of the device, illustrating details of component level analysis. Employed methodology has many advantages such as i simple and easy fabrication; ii easy to control the operations during rough weather; and iii low failure rate during normal sea conditions. Experimental investigations carried out on the scaled model of MWEC show better performance and its capability to generate power at higher efficiency in regular wave fields. Design Failure Mode and Effect Analysis (FMEA shows rare failure rates for all components except the floating buoy.

  6. State estimation for wave energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Bacelli, Giorgio; Coe, Ryan Geoffrey

    2017-04-01

    This report gives a brief discussion and examples on the topic of state estimation for wave energy converters (WECs). These methods are intended for use to enable real-time closed loop control of WECs.

  7. Wave energy potential in Galicia (NW Spain)

    DEFF Research Database (Denmark)

    Iglesias, Gregorio; López, Mario; Carballo, Rodrigo

    2009-01-01

    Wave power presents significant advantages with regard to other CO2-free energy sources, among which the predictability, high load factor and low visual and environmental impact stand out. Galicia, facing the Atlantic on the north-western corner of the Iberian Peninsula, is subjected to a very...... harsh wave climate; in this work its potential for energy production is assessed based on three-hourly data from a third generation ocean wave model (WAM) covering the period 1996 - 2005. Taking into account the results of this assessment along with other relevant considerations such as the location...

  8. Assessment of wave energy resources in Hawaii

    International Nuclear Information System (INIS)

    Stopa, Justin E.; Cheung, Kwok Fai; Chen, Yi-Leng

    2011-01-01

    Hawaii is subject to direct approach of swells from distant storms as well as seas generated by trade winds passing through the islands. The archipelago creates a localized weather system that modifies the wave energy resources from the far field. We implement a nested computational grid along the major Hawaiian Islands in the global WaveWatch3 (WW3) model and utilize the Weather Research and Forecast (WRF) model to provide high-resolution mesoscale wind forcing over the Hawaii region. Two hindcast case studies representative of the year-round conditions provide a quantitative assessment of the regional wind and wave patterns as well as the wave energy resources along the Hawaiian Island chain. These events of approximately two weeks each have a range of wind speeds, ground swells, and wind waves for validation of the model system with satellite and buoy measurements. The results demonstrate the wave energy potential in Hawaii waters. While the episodic swell events have enormous power reaching 60 kW/m, the wind waves, augmented by the local weather, provide a consistent energy resource of 15-25 kW/m throughout the year. (author)

  9. Clustering of cycloidal wave energy converters

    Science.gov (United States)

    Siegel, Stefan G.

    2016-03-29

    A wave energy conversion system uses a pair of wave energy converters (WECs) on respective active mountings on a floating platform, so that the separation of the WECs from each other or from a central WEC can be actively adjusted according to the wavelength of incident waves. The adjustable separation facilitates operation of the system to cancel reactive forces, which may be generated during wave energy conversion. Modules on which such pairs of WECs are mounted can be assembled with one or more central WECs to form large clusters in which reactive forces and torques can be made to cancel. WECs of different sizes can be employed to facilitate cancelation of reactive forces and torques.

  10. Optimal control of a wave energy converter

    NARCIS (Netherlands)

    Hendrikx, R.W.M.; Leth, J.; Andersen, P; Heemels, W.P.M.H.

    2017-01-01

    The optimal control strategy for a wave energy converter (WEC) with constraints on the control torque is investigated. The goal is to optimize the total energy delivered to the electricity grid. Using Pontryagin's maximum principle, the solution is found to be singular-bang. Using higher order

  11. Wave propagation of spectral energy content in a granular chain

    NARCIS (Netherlands)

    Shrivastava, Rohit Kumar; Luding, Stefan

    2017-01-01

    A mechanical wave is propagation of vibration with transfer of energy and momentum. Understanding the spectral energy characteristics of a propagating wave through disordered granular media can assist in understanding the overall properties of wave propagation through inhomogeneous materials like

  12. Design Specifications for the Hanstholm WEPTOS Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Larsen, Tommy

    2012-01-01

    The WEPTOS wave energy converter (WEC) is a novel device that combines an established and efficient wave energy absorbing mechanism with a smart structure, which can regulate the amount of incoming wave energy and reduce loads in extreme wave conditions. This adjustable A-shaped slack-moored and ......The WEPTOS wave energy converter (WEC) is a novel device that combines an established and efficient wave energy absorbing mechanism with a smart structure, which can regulate the amount of incoming wave energy and reduce loads in extreme wave conditions. This adjustable A-shaped slack...

  13. Air Turbines for Wave Energy Conversion

    Directory of Open Access Journals (Sweden)

    Manabu Takao

    2012-01-01

    Full Text Available This paper describes the present status of the art on air turbines, which could be used for wave energy conversion. The air turbines included in the paper are as follows: Wells type turbines, impulse turbines, radial turbines, cross-flow turbine, and Savonius turbine. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been compared by numerical simulation and sea trial. As a result, under irregular wave conditions it is found that the running and starting characteristics of the impulse type turbines could be superior to those of the Wells turbine. Moreover, as the current challenge on turbine technology, the authors explain a twin-impulse turbine topology for wave energy conversion.

  14. Electromagnetic wave energy conversion research

    Science.gov (United States)

    Bailey, R. L.; Callahan, P. S.

    1975-01-01

    Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.

  15. Fundamental formulae for wave-energy conversion.

    Science.gov (United States)

    Falnes, Johannes; Kurniawan, Adi

    2015-03-01

    The time-average wave power that is absorbed from an incident wave by means of a wave-energy conversion (WEC) unit, or by an array of WEC units-i.e. oscillating immersed bodies and/or oscillating water columns (OWCs)-may be mathematically expressed in terms of the WEC units' complex oscillation amplitudes, or in terms of the generated outgoing (diffracted plus radiated) waves, or alternatively, in terms of the radiated waves alone. Following recent controversy, the corresponding three optional expressions are derived, compared and discussed in this paper. They all provide the correct time-average absorbed power. However, only the first-mentioned expression is applicable to quantify the instantaneous absorbed wave power and the associated reactive power. In this connection, new formulae are derived that relate the 'added-mass' matrix, as well as a couple of additional reactive radiation-parameter matrices, to the difference between kinetic energy and potential energy in the water surrounding the immersed oscillating WEC array. Further, a complex collective oscillation amplitude is introduced, which makes it possible to derive, by a very simple algebraic method, various simple expressions for the maximum time-average wave power that may be absorbed by the WEC array. The real-valued time-average absorbed power is illustrated as an axisymmetric paraboloid defined on the complex collective-amplitude plane. This is a simple illustration of the so-called 'fundamental theorem for wave power'. Finally, the paper also presents a new derivation that extends a recently published result on the direction-average maximum absorbed wave power to cases where the WEC array's radiation damping matrix may be singular and where the WEC array may contain OWCs in addition to oscillating bodies.

  16. Pressure transducers

    International Nuclear Information System (INIS)

    Gomes, A.V.

    1975-01-01

    Strain gauges pressure transducers types are presented. Models, characteristics and calibration procedures were also analysed. Initially, a theoretical study was accomplished to evaluate metallic alloys behavior on sensing elements manufacturing, and diaphragm was used as deflecting elements. Electrical models for potenciometric transducers were proposed at the beginning and subsequently comproved according our experiments. Concerning bridge transducers, existing models confirmed the conditions of linearity and sensitivity related to the electrical signal. All the work done was of help on the calibration field and pressure measurements employing unbounded strain gauge pressure transducers

  17. The Use of Flexible Ultrasound Transducers for the Detection of Laser-Induced Guided Waves on Curved Surfaces at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Tai Chieh Wu

    2017-06-01

    Full Text Available In this study, a flexible ultrasonic transducer (FUT was applied in a laser ultrasonic technique (LUT for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of a PZT/PZT sol-gel composite which has advantages due to its high sensitivity, curved surface adaptability and high temperature durability. By operating a pulsed laser in B-scan mode along with the integration of FUT and LUT, a multi-mode dispersion spectrum of a stainless steel pipe at high temperature can be measured. In addition, dynamic wave propagation behaviors are experimentally visualized with two dimensional scanning. The images directly interpret the reflections from the interior defects and also can locate their positions. This hybrid technique shows great potential for non-destructive evaluation of structures with complex geometry, especially in high temperature environments.

  18. A Low-Power CMOS Piezoelectric Transducer Based Energy Harvesting Circuit for Wearable Sensors for Medical Applications

    Directory of Open Access Journals (Sweden)

    Taeho Oh

    2017-12-01

    Full Text Available Piezoelectric vibration based energy harvesting systems have been widely utilized and researched as powering modules for various types of sensor systems due to their ease of integration and relatively high energy density compared to RF, thermal, and electrostatic based energy harvesting systems. In this paper, a low-power CMOS full-bridge rectifier is presented as a potential solution for an efficient energy harvesting system for piezoelectric transducers. The energy harvesting circuit consists of two n-channel MOSFETs (NMOS and two p-channel MOSFETs (PMOS devices implementing a full-bridge rectifier coupled with a switch control circuit based on a PMOS device driven by a comparator. With a load of 45 kΩ, the output rectifier voltage and the input piezoelectric transducer voltage are 694 mV and 703 mV, respectably, while the VOUT versus VIN conversion ratio is 98.7% with a PCE of 52.2%. The energy harvesting circuit has been designed using 130 nm standard CMOS process.

  19. Parametric pendulum based wave energy converter

    Science.gov (United States)

    Yurchenko, Daniil; Alevras, Panagiotis

    2018-01-01

    The paper investigates the dynamics of a novel wave energy converter based on the parametrically excited pendulum. The herein developed concept of the parametric pendulum allows reducing the influence of the gravity force thereby significantly improving the device performance at a regular sea state, which could not be achieved in the earlier proposed original point-absorber design. The suggested design of a wave energy converter achieves a dominant rotational motion without any additional mechanisms, like a gearbox, or any active control involvement. Presented numerical results of deterministic and stochastic modeling clearly reflect the advantage of the proposed design. A set of experimental results confirms the numerical findings and validates the new design of a parametric pendulum based wave energy converter. Power harvesting potential of the novel device is also presented.

  20. Probabilistic Forecasting of the Wave Energy Flux

    DEFF Research Database (Denmark)

    Pinson, Pierre; Reikard, G.; Bidlot, J.-R.

    2012-01-01

    Wave energy will certainly have a significant role to play in the deployment of renewable energy generation capacities. As with wind and solar, probabilistic forecasts of wave power over horizons of a few hours to a few days are required for power system operation as well as trading in electricit......% and 70% in terms of Continuous Rank Probability Score (CRPS), depending upon the test case and the lead time. It is finally shown that the log-Normal assumption can be seen as acceptable, even though it may be refined in the future....

  1. Systems and methods for wave energy conversion

    Science.gov (United States)

    MacDonald, Daniel G.; Cantara, Justin; Nathan, Craig; Lopes, Amy M.; Green, Brandon E.

    2017-02-28

    Systems for wave energy conversion that have components that can survive the harsh marine environment and that can be attached to fixed structures, such as a pier, and having the ability to naturally adjust for tidal height and methods for their use are presented.

  2. Underwater noise from a wave energy converter

    DEFF Research Database (Denmark)

    Tougaard, Jakob

    A recent addition to the anthropogenic sources of underwater noise is offshore wave energy converters. Underwater noise was recorded from the Wavestar wave energy converter located at Hastholm, Denmark (57°7.73´N, 8°37.23´E). The Wavestar is a full-scale test and demonstration converter...... in full operation and start and stop of the converter. Median broad band (10 Hz – 20 kHz) sound pressure level (Leq) was 123 dB re. 1 Pa, irrespective of status of the wave energy converter (stopped, running or starting/stopping). The most pronounced peak in the third-octave spectrum was in the 160 Hz...... significant noise above ambient could be detected above the 250 Hz band. The absolute increase in noise above ambient was very small. L50 third-octave levels in the four bands with the converter running were thus only 1-2 dB above ambient L50 levels. The noise recorded 25 m from the wave energy converter...

  3. Innovative Breakwaters Design for Wave Energy Conversion

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Stagonas, D.; Müller, G.

    2012-01-01

    the rubble mound breakwaters and seawalls related activity and the energy demand of small human communities. Wave loadings and overtopping on a seawall and rubble mound breakwater with front reservoir are discussed on the basis of physical 2-D model tests carried out at University of Southampton (UK...

  4. Experimental Measurement of Wave Field Variations around Wave Energy Converter Arrays

    OpenAIRE

    O'Boyle, Louise; Elsäßer, Björn; Whittaker, Trevor

    2017-01-01

    Wave energy converters (WECs) inherently extract energy from incident waves. For wave energy to become a significant power provider in the future, large farms of WECs will be required. This scale of energy extraction will increase the potential for changes in the local wave field and coastal environment. Assessment of these effects is necessary to inform decisions on the layout of wave farms for optimum power output and minimum environmental impact, as well as on potential site selection. An ...

  5. Dark Energy and Inflation from Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Leonid Marochnik

    2017-10-01

    Full Text Available In this seven-part paper, we show that gravitational waves (classical and quantum produce the accelerated de Sitter expansion at the start and at the end of the cosmological evolution of the Universe. In these periods, the Universe contains no matter fields but contains classical and quantum metric fluctuations, i.e., it is filled with classical and quantum gravitational waves. In such evolution of the Universe, dominated by gravitational waves, the de Sitter state is the exact solution to the self-consistent equations for classical and quantum gravitational waves and background geometry for the empty space-time with FLRW metric. In both classical and quantum cases, this solution is of the instanton origin since it is obtained in the Euclidean space of imaginary time with the subsequent analytic continuation to real time. The cosmological acceleration from gravitational waves provides a transparent physical explanation to the coincidence, threshold and “old cosmological constant” paradoxes of dark energy avoiding recourse to the anthropic principle. The cosmological acceleration from virtual gravitons at the start of the Universe evolution produces inflation, which is consistent with the observational data on CMB anisotropy. Section 1 is devoted to cosmological acceleration from classical gravitational waves. Section 2 is devoted to the theory of virtual gravitons in the Universe. Section 3 is devoted to cosmological acceleration from virtual gravitons. Section 4 discusses the consistency of the theory with observational data on dark energy and inflation. The discussion of mechanism of acceleration and cosmological scenario are contained in Sections 5 and 6. Appendix contains the theory of stochastic nonlinear gravitational waves of arbitrary wavelength and amplitude in an isotropic Universe.

  6. Benefits of up-wave measurements in linear short-term wave forecasting for wave energy applications

    OpenAIRE

    Paparella, Francesco; Monk, Kieran; Winands, Victor; Lopes, Miguel; Conley, Daniel; Ringwood, John

    2014-01-01

    The real-time control of wave energy converters requires the prediction of the wave elevation at the location of the device in order to maximize the power extracted from the waves. One possibility is to predict the future wave elevation by combining its past history with the spatial information coming from a sensor which measures the free surface elevation upwave of the wave energy converter. As an application example, the paper focuses on the prediction of the wave eleva...

  7. Acoustic transducer

    Science.gov (United States)

    Drumheller, Douglas S.

    2000-01-01

    An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

  8. Coaxial Transducer

    National Research Council Canada - National Science Library

    Ruffa, Anthony A

    2008-01-01

    The invention as disclosed is of a coaxial transducer that uses lead zirconate titanate ceramic or other suitable material as an isolator between the conductors in a coaxial cable to transmit acoustic...

  9. Wave energy and its possibilities in the Danish power supplies

    International Nuclear Information System (INIS)

    Traeholt Madsen, N.; Lorenzen, S.; Haunstrup Christensen, T.

    1997-06-01

    Mathematical theory of wave forces (wave height, spectrua, energy distribution and effect) is summarized. An attempt to estimate the Danish wave power potential on the basis of previous investigations og wave effect in various regions is presented. A brief review of wave energy applications and research constitutes basis for two scenarios of wave power adjustment into the 'Green society'. Power quality, environment, economics and supply reliability are estimated. (EG) 42 refs

  10. Frequency and wavenumber selective excitation of spin waves through coherent energy transfer from elastic waves

    OpenAIRE

    Hashimoto, Yusuke; Bossini, Davide; Johansen, Tom H.; Saitoh, Eiji; Kirilyuk, Andrei; Rasing, Theo

    2017-01-01

    Using spin-wave tomography (SWaT), we have investigated the excitation and the propagation dynamics of optically-excited magnetoelastic waves, i.e. hybridized modes of spin waves and elastic waves, in a garnet film. By using time-resolved SWaT, we reveal the excitation dynamics of magnetoelastic waves through coherent-energy transfer between optically-excited pure-elastic waves and spin waves via magnetoelastic coupling. This process realizes frequency and wavenumber selective excitation of s...

  11. Wave energy transmission apparatus for high-temperature environments

    Science.gov (United States)

    Buckley, John D. (Inventor); Edwards, William C. (Inventor); Kelliher, Warren C. (Inventor); Carlberg, Ingrid A. (Inventor)

    2010-01-01

    A wave energy transmission apparatus has a conduit made from a refractory oxide. A transparent, refractory ceramic window is coupled to the conduit. Wave energy passing through the window enters the conduit.

  12. Proof-of-concept experimental study of damage detection of concrete piles using embedded piezoceramic transducers

    International Nuclear Information System (INIS)

    Wang, R L; Gu, H; Song, G; Mo, Y L

    2013-01-01

    This paper presents a proof-of-concept experimental study of an innovative active-sensing approach for damage detection of concrete piles by using embedded piezoceramic transducers. In the proposed active-sensing approach, one piezoceramic transducer is used as an actuator to generate a stress wave to propagate through the concrete pile and the other distributed piezoceramic transducers are used as sensors to detect the wave response. Cracks or damage inside the concrete structure act as stress relief in the wave propagation path. The amplitude of the wave and the transmission energy will decrease due to the existence of cracks or damage. Experiments were performed on two bored piles instrumented with embedded piezoceramic transducers. The experimental results demonstrate the effectiveness of the proposed approach for pile damage detection. (fast track communication)

  13. Worlds Largest Wave Energy Project 2007 in Wales

    DEFF Research Database (Denmark)

    Christensen, Lars; Friis-Madsen, Erik; Kofoed, Jens Peter

    2006-01-01

    This paper introduces world largest wave energy project being developed in Wales and based on one of the leading wave energy technologies. The background for the development of wave energy, the total resource ands its distribution around the world is described. In contrast to wind energy turbines...... Dragon has to be scaled in accordance with the wave climate at the deployment site, which makes the Welch demonstrator device the worlds largest WEC so far with a total width of 300 meters. The project budget, the construction methods and the deployment site are also given....... a large number of fundamentally different technologies are utilised to harvest wave energy. The Wave Dragon belongs to the wave overtopping class of converters and the paper describes the fundamentals and the technical solutions used in this wave energy converter. An offshore floating WEC like the Wave...

  14. Electrical Systems for Wave Energy Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Bostroem, Cecilia

    2011-07-01

    Wave energy is a renewable energy source with a large potential to contribute to the world's electricity production. There exist several technologies on how to convert the energy in the ocean waves into electric energy. The wave energy converter (WEC) presented in this thesis is based on a linear synchronous generator. The generator is placed on the seabed and driven by a point absorbing buoy on the ocean surface. Instead of having one large unit, several smaller units are interconnected to increase the total installed power. To convert and interconnect the power from the generators, marine substations are used. The marine substations are placed on the seabed and convert the fluctuating AC from the generators into an AC suitable for grid connection. The work presented in the thesis focuses on the first steps in the electric energy conversion, converting the voltage out from the generators into DC, which have an impact on the WEC's ability to absorb and produce power. The purpose has been to investigate how the generator will operate when it is subjected to different load cases and to obtain guidelines on how future systems could be improved. Offshore experiments and simulations have been done on full scale generators connected to four different loads, i.e. one linear resistive load and three different non-linear loads representing different cases for grid connected WECs. The results show that the power can be controlled and optimized by choosing a suitable system for the WEC. It is not obvious which kind of system is the most preferable, since there are many different parameters that have an impact on the system performance, such as the size of the buoy, how the generator is designed, the number of WECs, the highest allowed complexity of the system, costs and so on. Therefore, the design of the electrical system should preferably be carried out in parallel with the design of the WEC in order to achieve an efficient system

  15. The state of development of wave energy

    International Nuclear Information System (INIS)

    Duckers, L.J.

    1991-01-01

    Wave energy converters are being developed and tested in as many as ten countries. The author believes that the shore mounted converters will be economically attractive in many locations around the world. These devices are simple and easily maintained. In order to harvest the greater offshore resource floating devices such as the Clam, Duck and Whale will be needed. Urgent research and development is needed to bring these to the prototype stage. Future deployment of large arrays of these floating systems could be quickly and easily achieved in many parts of the world and they would provide considerable quantities of environmentally benign, reasonably cheap energy. (author) 6 figs., 5 refs

  16. Aquabuoy Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Frigaard, Peter

    The work reported here is part of the contract agreement between the Finavera Renewables Ocean Energy Ltd. and the Department of Civil Engineering Hydraulics and Coastal Engineering Laboratory to instrument a model in scale 1:10 to prototype of the AquaBuOY (AB) wave energy converter and to analyse...... its performances in real sea testing in Nissum Bredning, Denmark. This report is part of Fineveras contribution to ForskEl project no 6435 “AquaBuOY skala 1:10 forsøg I Nissum Bredning”....

  17. Ultra-wideband ladder filters using zero-th shear mode plate wave in ultrathin LiNbO3 plate with apodized interdigital transducers

    Science.gov (United States)

    Kadota, Michio; Tanaka, Shuji

    2016-07-01

    There are two kinds of plate waves propagating in a thin plate, Lamb and shear horizontal (SH) waves. The former has a velocity higher than 15,000 m/s when the plate is very thin. On the contrary, 0th SH (SH0) mode plate wave in an ultrathin LiNbO3 plate has an electro-mechanical coupling factor larger than 50%. Authors fabricated an ultra-wideband T-type ladder filter with a relative bandwidth (BW) of 41% using the SH0 mode plate wave. Although the BW of the filter fully covers the digital TV band in Japan, it does not have sufficient margin at the lower and higher end of BW. Besides, periodic small ripples due to transverse mode in pass-band of the filter were observed. In this study π-type ladder filters were fabricated by changing the pitch ratio of interdigital transducer (IDT) of parallel and series arm resonators (PR(IDT)) to control the BW, and by apodizing IDTs to improve the periodic small ripples due to transverse mode. Ultra-wideband filters without periodic small transverse mode with ultrawide bandwidth from 41 to 49% were fabricated. The BWs fully cover ultrawide digital television bands in Japan and U.S.A. These filters with an ultrawide BW and a steep characteristic show the possibility to be applied to a reported cognitive radio system and other communication systems requiring an ultrawide BW.

  18. Practical performances of MPC for wave energy converters

    DEFF Research Database (Denmark)

    Ferri, Francesco; Tetu, Amelie; Hals, J.

    2016-01-01

    Maximising the efficiency of Wave Energy Converter (WEC) is one of the important tasks toward the exploitation of the wave energy resource. Along with a proper design of the device, an important way to achieve better energy performances is to improve the wave-body interaction by applying an appro...

  19. Fluctuation and thermal energy balance for drift-wave turbulence

    International Nuclear Information System (INIS)

    Kim, Chang-Bae; Horton, W.

    1990-05-01

    Energy conservation for the drift-wave system is shown to be separated into the wave-energy power balance equation and an ambient thermal-energy transport equation containing the anomalous transport fluxes produced by the fluctuations. The wave energy equation relates the wave energy density and wave energy flux to the anomalous transport flux and the dissipation of the fluctuations. The thermal balance equation determines the evolution of the temperature profiles from the divergence of the anomalous heat flux, the collisional heating and cooling mechanisms and the toroidal pumping effect. 16 refs., 1 tab

  20. Fluctuation and thermal energy balance for drift-wave turbulence

    International Nuclear Information System (INIS)

    Changbae Kim; Horton, W.

    1991-01-01

    Energy conservation for the drift-wave system is shown to be separated into the wave-energy power balance equation and an ambient thermal-energy transport equation containing the anomalous transport fluxes produced by the fluctuations. The wave energy equation relates the wave energy density and wave energy flux to the anomalous transport flux and the dissipation of the fluctuations. The thermal balance equation determines the evolution of the temperature profiles from the divergence of the anomalous heat flux, the collisional heating and cooling mechanisms and the toroidal pumping effect. (author)

  1. Wave Energy Research, Testing and Demonstration Center

    Energy Technology Data Exchange (ETDEWEB)

    Batten, Belinda [Oregon State Univ., Corvallis, OR (United States)

    2014-09-30

    The purpose of this project was to build upon the research, development and testing experience of the Northwest National Marine Renewable Energy Center (NNMREC) to establish a non-grid connected open-ocean testing facility for wave energy converters (WECs) off the coast of Newport, Oregon. The test facility would serve as the first facility of its kind in the continental US with a fully energetic wave resource where WEC technologies could be proven for west coast US markets. The test facility would provide the opportunity for self-contained WEC testing or WEC testing connected via an umbilical cable to a mobile ocean test berth (MOTB). The MOTB would act as a “grid surrogate” measuring energy produced by the WEC and the environmental conditions under which the energy was produced. In order to realize this vision, the ocean site would need to be identified through outreach to community stakeholders, and then regulatory and permitting processes would be undertaken. Part of those processes would require environmental baseline studies and site analysis, including benthic, acoustic and wave resource characterization. The MOTB and its myriad systems would need to be designed and constructed.The first WEC test at the facility with the MOTB was completed within this project with the WET-NZ device in summer 2012. In summer 2013, the MOTB was deployed with load cells on its mooring lines to characterize forces on mooring systems in a variety of sea states. Throughout both testing seasons, studies were done to analyze environmental effects during testing operations. Test protocols and best management practices for open ocean operations were developed. As a result of this project, the non-grid connected fully energetic WEC test facility is operational, and the MOTB system developed provides a portable concept for WEC testing. The permitting process used provides a model for other wave energy projects, especially those in the Pacific Northwest that have similar

  2. EB Frond wave energy converter - phase 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    The EB Frond project is a wave energy programme developed by The Engineering Business (EB) from an original idea at Lancaster University. The EB Frond is a wave generator with a collector vane on top of an arm that pivots near the seabed. Phase 1 of the project demonstrated the technical feasibility of the project and provided proof of concept. Phase 2 involved further assesment of the technical and commercial viability of the concept through the development of mathematical and physical modelling methods. The work involved small-scale (1/25th) testing in wave tanks at Newcastle and Lancaster Universities and the development, verification and validation of a time domain mathematical model. The decision by EB to put on hold its renewable generation programme meant that plans to test at an intermediate scale (1/16th), assess different survival strategies in extreme wave conditions, carry out site characterisation for full-scale systems and to produce a robust economic model were not fulfilled. However, the mathematical and physical modelling work was used to develop an economic model for the Frond system. This produced a predicted unit cost of electricity by a pre-commercial 5 MW demonstration farm of about 17 pence/kWh. The report discusses the small-scale testing, test results, mathematical modelling, analysis and interpretation, survivability, the economic model and the development route to full-scale production.

  3. Short-Term Wave Forecasting for Real-Time Control of Wave Energy Converters

    OpenAIRE

    Fusco, Francesco; Ringwood, John

    2010-01-01

    Real-time control of wave energy converters requires knowledge of future incident wave elevation in order to approach optimal efficiency of wave energy extraction. We present an approach where the wave elevation is treated as a time series and it is predicted only from its past history. A comparison of a range of forecasting methodologies on real wave observations from two different locations shows how the relatively simple linear autoregressive model, which implicitly models the cyclical beh...

  4. Monitoring of Soft Deposition Layers in Liquid-Filled Tubes with Guided Acoustic Waves Excited by Clamp-on Transducers.

    Science.gov (United States)

    Tietze, Sabrina; Singer, Ferdinand; Lasota, Sandra; Ebert, Sandra; Landskron, Johannes; Schwuchow, Katrin; Drese, Klaus Stefan; Lindner, Gerhard

    2018-02-09

    The monitoring of liquid-filled tubes with respect to the formation of soft deposition layers such as biofilms on the inner walls calls for non-invasive and long-term stable sensors, which can be attached to existing pipe structures. For this task a method is developed, which uses an ultrasonic clamp-on device. This method is based on the impact of such deposition layers on the propagation of circumferential guided waves on the pipe wall. Such waves are partly converted into longitudinal compressional waves in the liquid, which are back-converted to guided waves in a circular cross section of the pipe. Validating this approach, laboratory experiments with gelatin deposition layers on steel tubes exhibited a distinguishable sensitivity of both wave branches with respect to the thickness of such layers. This allows the monitoring of the layer growth.

  5. Internal energy relaxation in shock wave structure

    International Nuclear Information System (INIS)

    Josyula, Eswar; Suchyta, Casimir J.; Boyd, Iain D.; Vedula, Prakash

    2013-01-01

    The Wang Chang-Uhlenbeck (WCU) equation is numerically integrated to characterize the internal structure of Mach 3 and Mach 5 shock waves in a gas with excitation in the internal energy states for the treatment of inelastic collisions. Elastic collisions are modeled with the hard sphere collision model and the transition rates for the inelastic collisions modified appropriately using probabilities based on relative velocities of the colliding particles. The collision integral is evaluated by the conservative discrete ordinate method [F. Tcheremissine, “Solution of the Boltzmann kinetic equation for high-speed flows,” Comput. Math. Math. Phys. 46, 315–329 (2006); F. Cheremisin, “Solution of the Wang Chang-Uhlenbeck equation,” Dokl. Phys. 47, 487–490 (2002)] developed for the Boltzmann equation. For the treatment of the diatomic molecules, the internal energy modes in the Boltzmann equation are described quantum mechanically given by the WCU equation. As a first step in the treatment of the inelastic collisions by the WCU equation, a two- and three-quantum system is considered to study the effect of the varying of (1) the inelastic cross section and (2) the energy gap between the quantum energy states. An alternative method, the direct simulation Monte Carlo method, is used for the Mach 3 shock wave to ensure the consistency of implementation in the two methods and there is an excellent agreement between the two methods. The results from the WCU implementation showed consistent trends for the Mach 3 and Mach5 standing shock waves simulations. Inelastic contributions change the downstream equilibrium state and allow the flow to transition to the equilibrium state further upstream

  6. Experimental Research of a New Wave Energy Conversion Device

    Science.gov (United States)

    Lu, Zhongyue; Shang, Jianzhong; Luo, Zirong; Sun, Chongfei; Chen, Gewei

    2018-01-01

    With the increasing tension of contemporary social energy, the development and utilization of renewable energy has become an important development direction. As an important part of renewable energy, wave energy has the characteristics of green environmental protection and abundant reserves, attracting more investment and research. For small marine equipment energy supply problem, this paper puts forward a micro wave energy conversion device as the basic of heaving motion of waves in the ocean. This paper designed a new type of power output device can solve the micro wave energy conversion problem.

  7. Design guidelines of triboelectric nanogenerator for water wave energy harvesters

    KAUST Repository

    Ahmed, Abdelsalam

    2017-04-11

    Ocean waves are one of the cleanest and most abundant energy sources on earth, and wave energy has the potential for future power generation. Triboelectric nanogenerator (TENG) technology has recently been proposed as a promising technology to harvest wave energy. In this paper, a theoretical study is performed on a duck-shaped TENG wave harvester recently introduced in our work. To enhance the design of the duck-shaped TENG wave harvester, the mechanical and electrical characteristics of the harvester\\'s overall structure, as well as its inner configuration, are analyzed, respectively, under different wave conditions, to optimize parameters such as duck radius and mass. Furthermore, a comprehensive hybrid 3D model is introduced to quantify the performance of the TENG wave harvester. Finally, the influence of different TENG parameters is validated by comparing the performance of several existing TENG wave harvesters. This study can be applied as a guideline for enhancing the performance of TENG wave energy harvesters.

  8. Design guidelines of triboelectric nanogenerator for water wave energy harvesters

    KAUST Repository

    Ahmed, Abdelsalam; Hassan, Islam; Jiang, Tao; Youssef, Khalid; Liu, Lian; Hedaya, Mohammad; Yazid, Taher Abu; Zu, Jean; Wang, Zhong Lin

    2017-01-01

    Ocean waves are one of the cleanest and most abundant energy sources on earth, and wave energy has the potential for future power generation. Triboelectric nanogenerator (TENG) technology has recently been proposed as a promising technology to harvest wave energy. In this paper, a theoretical study is performed on a duck-shaped TENG wave harvester recently introduced in our work. To enhance the design of the duck-shaped TENG wave harvester, the mechanical and electrical characteristics of the harvester's overall structure, as well as its inner configuration, are analyzed, respectively, under different wave conditions, to optimize parameters such as duck radius and mass. Furthermore, a comprehensive hybrid 3D model is introduced to quantify the performance of the TENG wave harvester. Finally, the influence of different TENG parameters is validated by comparing the performance of several existing TENG wave harvesters. This study can be applied as a guideline for enhancing the performance of TENG wave energy harvesters.

  9. Design guidelines of triboelectric nanogenerator for water wave energy harvesters.

    Science.gov (United States)

    Ahmed, Abdelsalam; Hassan, Islam; Jiang, Tao; Youssef, Khalid; Liu, Lian; Hedaya, Mohammad; Yazid, Taher Abu; Zu, Jean; Wang, Zhong Lin

    2017-05-05

    Ocean waves are one of the cleanest and most abundant energy sources on earth, and wave energy has the potential for future power generation. Triboelectric nanogenerator (TENG) technology has recently been proposed as a promising technology to harvest wave energy. In this paper, a theoretical study is performed on a duck-shaped TENG wave harvester recently introduced in our work. To enhance the design of the duck-shaped TENG wave harvester, the mechanical and electrical characteristics of the harvester's overall structure, as well as its inner configuration, are analyzed, respectively, under different wave conditions, to optimize parameters such as duck radius and mass. Furthermore, a comprehensive hybrid 3D model is introduced to quantify the performance of the TENG wave harvester. Finally, the influence of different TENG parameters is validated by comparing the performance of several existing TENG wave harvesters. This study can be applied as a guideline for enhancing the performance of TENG wave energy harvesters.

  10. Ultrasound acoustic wave energy transfer and harvesting

    Science.gov (United States)

    Shahab, Shima; Leadenham, Stephen; Guillot, François; Sabra, Karim; Erturk, Alper

    2014-04-01

    This paper investigates low-power electricity generation from ultrasound acoustic wave energy transfer combined with piezoelectric energy harvesting for wireless applications ranging from medical implants to naval sensor systems. The focus is placed on an underwater system that consists of a pulsating source for spherical wave generation and a harvester connected to an external resistive load for quantifying the electrical power output. An analytical electro-acoustic model is developed to relate the source strength to the electrical power output of the harvester located at a specific distance from the source. The model couples the energy harvester dynamics (piezoelectric device and electrical load) with the source strength through the acoustic-structure interaction at the harvester-fluid interface. Case studies are given for a detailed understanding of the coupled system dynamics under various conditions. Specifically the relationship between the electrical power output and system parameters, such as the distance of the harvester from the source, dimensions of the harvester, level of source strength, and electrical load resistance are explored. Sensitivity of the electrical power output to the excitation frequency in the neighborhood of the harvester's underwater resonance frequency is also reported.

  11. Damage detection with concentrated configurations of piezoelectric transducers

    International Nuclear Information System (INIS)

    Wandowski, T; Malinowski, P; Ostachowicz, W M

    2011-01-01

    In this paper results of investigation on concentrated piezoelectric networks with different configurations are presented. They were used for elastic wave generation and acquisition. The elastic wave propagation phenomenon was used for damage localization in thin aluminium panels. This approach utilized the fact that any discontinuities existing in structural elements cause local changes of physical material properties which affect elastic wave propagation. Elastic waves were excited and received using piezoelectric transducer networks with different element arrangements. The method of transducer placement and the number of piezoelectric elements used had an influence on the accuracy of the damage localization algorithm. Obviously, the more elements there were, the more data had to be processed. After the acquisition process signal processing was conducted in order to create damage influence maps. These maps presents elastic wave energy connected with reflection from discontinuities. In order to create such a map a computer program was developed that assigns a mesh of points to the panel surface. At each point the energy of elastic wave reflection was calculated. This energy was extracted from the acquired signals. This paper summarizes an extensive experimental investigation that included three damage scenarios and twelve transducer configurations

  12. Hydraulic Evaluation of the Crest Wing Wave Energy Converter

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Antonishen, Michael Patrick

    This report presents the results of an experimental study of the wave energy converting abilities of the Crest Wing wave energy converter (WEC). The Crest Wing is a WEC that uses its movement in matching the shape of an oncoming wave to generate power. Model tests have been performed using a scale...... model (length scale 1:30), provided by WaveEnergyFyn, in regular and irregular wave states that can be found in Assessment of Wave Energy Devices. Best Practice as used in Denmark (Frigaard et al., 2008). The tests were carried out at Dept. of Civil Engineering, Aalborg (Frigaard et al., 2008......). The tests were carried out at Dept. of Civil Engineering, Aalborg University (AAU) in the 3D deep water wave tank. The displacement and force applied to a power take off system, provided by WaveEnergyFyn, were measured and used to calculate total power take off....

  13. Sea wave energy based in nanotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Duque, Carlos

    2010-09-15

    Application on which it turns east document is the recovery of the energy of the sea waves turning it into electricity by means of the combination of nano-piezoelectric and condensing, the system would be seen like a compound floating fabric of million piezoelectric crystals that turn the oscillating movement of the sea into micro-electrical signals that they are added and they left by means cables to the surface where electronics devices classified to the load of condensers, from the electricity is confined and later is invested and synchronize itself with the great national mains.

  14. Layout Optimisation of Wave Energy Converter Arrays

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé; Nava, Vincenzo; Topper, Mathew B. R.

    2017-01-01

    This paper proposes an optimisation strategy for the layout design of wave energy converter (WEC) arrays. Optimal layouts are sought so as to maximise the absorbed power given a minimum q-factor, the minimum distance between WECs, and an area of deployment. To guarantee an efficient optimisation......, a four-parameter layout description is proposed. Three different optimisation algorithms are further compared in terms of performance and computational cost. These are the covariance matrix adaptation evolution strategy (CMA), a genetic algorithm (GA) and the glowworm swarm optimisation (GSO) algorithm...

  15. Communicating Wave Energy: An Active Learning Experience for Students

    Science.gov (United States)

    Huynh, Trongnghia; Hou, Gene; Wang, Jin

    2016-01-01

    We have conducted an education project to communicate the wave energy concept to high school students. A virtual reality system that combines both hardware and software is developed in this project to simulate the buoy-wave interaction. This first-of-its-kind wave energy unit is portable and physics-based, allowing students to conduct a number of…

  16. The energy density of a Landau damped plasma wave

    NARCIS (Netherlands)

    Best, R. W. B.

    1999-01-01

    In this paper some theories about the energy of a Landau damped plasma wave are discussed and new initial conditions are proposed. Analysis of a wave packet, rather than an infinite wave, gives a clear picture of the energy transport from field to particles. Initial conditions are found which excite

  17. Experimental Modelling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Kofoed, Jens Peter

    The Wave Dragon is a floating slack-moored Wave Energy Converter (WEC) of the overtopping type. Oncoming waves are focused by two wing reflectors towards the ramp of the device, surge-up and overtop into a reservoir placed at a higher level than the surface of the sea. The energy production takes...

  18. The Draukie's Tale: Origin Myth for Wave Energy

    DEFF Research Database (Denmark)

    Watts, Laura

    2017-01-01

    Poem based on ethnographic research with people and places around the European Marine Energy Centre, the world's longest running test site for wave and tide energy, Orkney islands, Scotland.......Poem based on ethnographic research with people and places around the European Marine Energy Centre, the world's longest running test site for wave and tide energy, Orkney islands, Scotland....

  19. Experimental Measurement of Wave Field Variations around Wave Energy Converter Arrays

    Directory of Open Access Journals (Sweden)

    Louise O’Boyle

    2017-01-01

    Full Text Available Wave energy converters (WECs inherently extract energy from incident waves. For wave energy to become a significant power provider in the future, large farms of WECs will be required. This scale of energy extraction will increase the potential for changes in the local wave field and coastal environment. Assessment of these effects is necessary to inform decisions on the layout of wave farms for optimum power output and minimum environmental impact, as well as on potential site selection. An experimental campaign to map, at high resolution, the wave field variation around arrays of 5 oscillating water column WECs and a methodology for extracting scattered and radiated waves is presented. The results highlight the importance of accounting for the full extent of the WEC behavior when assessing impacts on the wave field. The effect of radiated waves on the wave field is not immediately apparent when considering changes to the entire wave spectrum, nor when observing changes in wave climate due to scattered and radiated waves superimposed together. The results show that radiated waves may account for up to 50% of the effects on wave climate in the near field in particular operating conditions.

  20. Applying of the array transducers' technology for surface acoustic waves materials characterization in the transient regime; Application de la technologie multi-elements a la caracterisation des materiaux par ondes acoustiques de surface en regime impulsionnel

    Energy Technology Data Exchange (ETDEWEB)

    Frenet, D

    2000-07-01

    In this document we present a theoretical and experimental study which has been led to design a surface acoustic wave device for local characterisation (relatively to the wavelength) of isotropic or anisotropic materials. The device is based on a phased-array transducer of conical shape we have specifically designed for this purpose. It operates in the impulsive mode, in the frequency range of 1-5 MHz. In order to deduce mechanical properties of the material, it is possible to measure the surface wave characteristics (velocity, attenuation,...). Different methods for measuring the wave velocity have been developed taking advantage of from the phased-array technology. The originality of theses methods relies on the fact that the measures are performed without moving the transducer. Consequently, the device requires no additional mechanical system and it is quite compact. In addition, this shortens the characterisation process duration comparatively to the usually available methods (e. g. the V(z) technique). In the theoretical section of this study, a versatile model allowing to simulate in the time harmonic regime as well as in the transient regime, the transmitted field, the field reflected on isotropic or anisotropic planar samples and the output voltage for transducers of arbitrary shapes has been developed. The model has been applied to the phased-array conical transducer as well as to more classical transducers such as planar (rectangular) or focusing (spherically or cylindrically shaped) transducers. It predicts not only the geometrical contributions of the reflected field and signal but also the leaky contributions related to the surface acoustic waves. (author)

  1. Investigation of Wave Height Reduction behind the Wave Dragon Wave Energy Converters and Application in Santander, Spain

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Quvang Harck; Andersen, Thomas Lykke

    This paper deals with a case study on the wave height reduction behind floating Wave Dragon wave energy converters in Santander Bay, Spain. The study is performed using the MIKE21 Boussinesq model from DHI. The Wave Dragon transmission characteristics in the numerical wave propagation model...... are based on previously performed physical model tests in scale 1:51. Typical winter storm conditions are considered in the case study together with different stiffness in the mooring system of the floating device. From the study it is found that if multiple Wave Dragons are positioned in a farm the wave...

  2. Stress wave communication in concrete: II. Evaluation of low voltage concrete stress wave communications utilizing spectrally efficient modulation schemes with PZT transducers

    International Nuclear Information System (INIS)

    Siu, Sam; Wang, Kun; Ding, Zhi; Qing, Ji; Song, Gangbing

    2014-01-01

    Piezoelectric materials, traditionally used for structural health monitoring, have recently been used to implement stress wave communications. Within a protective encasing we fabricate a smart aggregate which enables transmission and reception of modulated stress waves for digital communication within concrete. Our research focuses on building a high efficiency stress wave communication system and comparing the performance of phase shift keying (PSK) with quadrature amplitude modulation (QAM). Our experiments evaluate the performance of QPSK and 16QAM implemented with our stress wave communication system at a transmit voltage ranging from 32 dBV to 37 dBV. We also demonstrate the increase in spectral efficiency of 16QAM compared to QPSK. (paper)

  3. Dominant wave frequency and amplitude estimation for adaptive control of wave energy converters

    OpenAIRE

    Nguyen , Hoai-Nam; Tona , Paolino; Sabiron , Guillaume

    2017-01-01

    International audience; Adaptive control is of great interest for wave energy converters (WEC) due to the inherent time-varying nature of sea conditions. Robust and accurate estimation algorithms are required to improve the knowledge of the current sea state on a wave-to-wave basis in order to ensure power harvesting as close as possible to optimal behavior. In this paper, we present a simple but innovative approach for estimating the wave force dominant frequency and wave force dominant ampl...

  4. Experimental Study on the Langlee Wave Energy Converter

    DEFF Research Database (Denmark)

    Lavelle, John; Kofoed, Jens Peter

    This report concerns the experimental study of the 1:20 scale model of the Langlee Wave Energy Converter (WEC) carried out at Aalborg University’s wave basin during the summer of 2010.......This report concerns the experimental study of the 1:20 scale model of the Langlee Wave Energy Converter (WEC) carried out at Aalborg University’s wave basin during the summer of 2010....

  5. Experimental Study of the Weptos Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Larsen, Tommy

    2012-01-01

    This paper presents the power performance results of the experimental study of the WEPTOS wave energy converter (WEC). This novel device combines an established and efficient wave energy absorbing mechanism with an adjustable structure that can regulate the amount of incoming wave energy and reduce...... loads in extreme wave conditions. This A-shaped floating structure absorbs the energy in the waves through a multitude of rotors, the shape of which is based on the renowned Salter’s Duck. These rotors pivot around a common axle, one for each leg of the structure, to which the rotors transfer...... the absorbed wave energy and which is connected to a common power take off system (one for each leg). The study investigates the performance of the device in a large range of wave states and estimates the performance in terms of mechanical power available to the power take off system of the WEPTOS WEC for two...

  6. Energy dissipation through wind-generated breaking waves

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shuwen; CAO Ruixue; XIE Lingling

    2012-01-01

    Wave breaking is an important process that controls turbulence properties and fluxes of heat and mass in the upper oceanic layer.A model is described for energy dissipation per unit area at the ocean surface attributed to wind-generated breaking waves,in terms of ratio of energy dissipation to energy input,windgenerated wave spectrum,and wave growth rate.Also advanced is a vertical distribution model of turbulent kinetic energy,based on an exponential distribution method.The result shows that energy dissipation rate depends heavily on wind speed and sea state.Our results agree well with predictions of previous works.

  7. Study of the potential of wave energy in Malaysia

    Science.gov (United States)

    Tan, Wan Ching; Chan, Keng Wai; Ooi, Heivin

    2017-07-01

    Renewable energy is generally defined as energy harnessed from resources which are naturally replenished. It is an alternative to the current conventional energy sources such as natural gas, oil and coal, which are nonrenewable. Besides being nonrenewable, the harnessing of these resources generally produce by-products which could be potentially harmful to the environment. On the contrary, the generation from renewable energy does not pose environmental degradation. Some examples of renewable energy sources are sunlight, wind, tides, waves and geothermal heat. Wave energy is considered as one of the most promising marine renewable resources and is becoming commercially viable quicker than other renewable technologies at an astonishing growth rate. This paper illustrates the working principle of wave energy converter (WEC) and the availability of wave energy in Malaysia oceans. A good understanding of the behaviour of ocean waves is important for designing an efficient WEC as the characteristics of the waves in shallow and deep water are different. Consequently, wave energy converters are categorized into three categories on shore, near shore and offshore. Therefore, the objectives of this study is ought to be carried out by focusing on the formation of waves and wave characteristics in shallow as well as in deep water. The potential sites for implementation of wave energy harvesting technology in Malaysia and the wave energy available in the respective area were analysed. The potential of wave energy in Malaysia were tabulated and presented with theoretical data. The interaction between motion of waves and heave buoys for optimum phase condition by using the mass and diameter as the variables were investigated.

  8. Enhancing Wave Energy Competitiveness through Co-Located Wind and Wave Energy Farms. A Review on the Shadow Effect

    OpenAIRE

    Sharay Astariz; Gregorio Iglesias

    2015-01-01

    Wave energy is one of the most promising alternatives to fossil fuels due to the enormous available resource; however, its development may be slowed as it is often regarded as uneconomical. The largest cost reductions are expected to be obtained through economies of scale and technological progress. In this sense, the incorporation of wave energy systems into offshore wind energy farms is an opportunity to foster the development of wave energy. The synergies between both renewables can be rea...

  9. Wave energy for the 21st century: status and prospects

    International Nuclear Information System (INIS)

    Thorpe, Tom

    2000-01-01

    This article reviews the current technical and commercial status of wave energy, and discusses the design of near shore devices such as the 2MW OSPREY, and offshore devices including the McCabe wave pump, the Ocean Power Technology Wave Energy Converter, the Archimedes Wave Swing, the Pelamis, and wave energy schemes under development by other commercial firms. The predicted generating costs, the potential market, environmental impacts, and institution factors such as planning and consent, grid connection,and safety in design and operation are considered. The operating principles of an oscillating water column, and some promising offshore devices are illustrated

  10. Energy of linear quasineutral electrostatic drift waves

    International Nuclear Information System (INIS)

    Pfirsch, D.; Correa-Restrepo, D.

    1993-01-01

    Certain kinds of nonlinear instabilities are related to the existence of negative-energy perturbations. In this paper, an exact energy expression for linear quasineutral electrostatic perturbations is derived within the framework of dissipationless multifluid theory that is valid for any geometry. Taking the mass formally as a tensor with, in general, different masses parallel and perpendicular to an ambient magnetic field allows one to treat in a convenient way different approximations such as the full dynamics and restriction to parallel dynamics or the completely adiabatic case. Application to slab configurations yields the result that the adiabatic approximation does not allow negative energy for perturbations which are perfectly localized at a mode resonant surface, whereas inclusion of the parallel dynamics does. This is in agreement with a recent numerical study of drift-wave turbulence within the framework of collisional two-fluid theory by B. Scott [Phys. Rev. Lett. 65, 3289 (1990); Phys. Fluids B 4, 2468 (1992)]. A dissipationless theory can be formulated in terms of a Lagrangian, from which the energy is immediately obtained. We start with the nonlinear theory. The theory is formulated via a Lagrangian which is written in terms of displacement vectors ξ ν (x,t) such that all constraints are taken into account. The nonlinear energy is obtained from the Lagrangian by standard methods. The procedure used is the same as that developed in a forthcoming paper by Pfirsch and Sudan [Phys. Fluids B (to be published)] for ideal nonlinear magnetohydrodynamics theory. From the exact Lagrangian one obtains the Lagrangian of the linearized theory by simple expansion to second order in ξ ν . This Lagrangian then yields the energy of the linearized theory

  11. Statistical investigation of expected wave energy and its reliability

    International Nuclear Information System (INIS)

    Ozger, M.; Altunkaynak, A.; Sen, Z.

    2004-01-01

    The statistical behavior of wave energy at a single site is derived by considering simultaneous variations in the period and wave height. In this paper, the general wave power formulation is derived by using the theory of perturbation. This method leads to a general formulation of the wave power expectation and other statistical parameter expressions, such as standard deviation and coefficient of variation. The statistical parameters, namely the mean value and variance of wave energy, are found in terms of the simple statistical parameters of period, significant wave height and zero up-crossing period. The elegance of these parameters is that they are distribution free. These parameters provide a means for defining the wave energy distribution function by employing the Chebyschev's inequality. Subsequently, an approximate probability distribution function of the wave energy is also derived for assessment of risk and reliability associated with wave energy. Necessary simple charts are given for risk and reliability assessments. Two procedures are presented for such assessments in wave energy calculations and the applications of these procedures are provided for wave energy potential assessment in the regions of the Pacific Ocean off the west coast of U.S. (author)

  12. Statistical investigation of expected wave energy and its reliability

    International Nuclear Information System (INIS)

    Oezger, Mehmet; Altunkaynak, Abduesselam; Sen, Zekai

    2004-01-01

    The statistical behavior of wave energy at a single site is derived by considering simultaneous variations in the period and wave height. In this paper, the general wave power formulation is derived by using the theory of perturbation. This method leads to a general formulation of the wave power expectation and other statistical parameter expressions, such as standard deviation and coefficient of variation. The statistical parameters, namely the mean value and variance of wave energy, are found in terms of the simple statistical parameters of period, significant wave height and zero up-crossing period. The elegance of these parameters is that they are distribution free. These parameters provide a means for defining the wave energy distribution function by employing the Chebyschev's inequality. Subsequently, an approximate probability distribution function of the wave energy is also derived for assessment of risk and reliability associated with wave energy. Necessary simple charts are given for risk and reliability assessments. Two procedures are presented for such assessments in wave energy calculations and the applications of these procedures are provided for wave energy potential assessment in the regions of the Pacific Ocean off the west coast of U.S

  13. Experimental Study on the Langlee Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Weisz, A.

    This report presents the results of an experimental study of the wave energy converting abilities of the Langlee wave energy converter (WEC). It focused mainly on evaluating the power generating capabilities of the device, including investigations of the following issues: Scaling ratiosPTO loadingWave...... height and wave period dependencyOblique incoming waves and directional spreading of waves (3D waves)Damping platesMooring forces and fixed structure setupPitch, surge and heave motion During the study the model supplied by the client (Langlee Wave Power AS) has been heavily instrumented - up to 23...... different instruments was deployed to measure and record data. Tests were performed at scales of 1:30 and 1:20 based on the realized reference wave states....

  14. Prospects and applicability of wave energy for South Africa

    Science.gov (United States)

    Lavidas, George; Venugopal, Vengatesan

    2018-03-01

    Renewable energy offers significant opportunities for electricity diversification. South Africa belongs to the group of developing nations and encompasses a lot of potential for renewable energy developments. Currently, the majority of its electricity production originates from fossil fuels; however, incorporation of clean coal technologies will aid in reaching the assigned targets. This study offers a long-term wave power quantification analysis with a numerical wave model. The investigation includes long-term resource assessment in the region, variability, seasonal and monthly wave energy content. Locations with high-energy content but low variability pose an opportunity that can contribute in the alleviation of energy poverty. Application of wave converters depends on the combination of complex terms. The study presents resource levels and the joint distributions, which indicate suitability for converter selection. Depending on the region of interest, these characteristics change. Thus, this resource assessment adds knowledge on wave power and optimal consideration for wave energy applicability.

  15. Survivability Mode and Extreme Loads on the Mooring Lines of the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Kofoed, Jens Peter

    This report is a product of the cooperation agreement between Wave Dragon and Aalborg University regarding phase 2 of the development of the Wave Dragon Wave Energy Converter. The research is carried out by testing the 1:51.8 scale model of the Wave Dragon, aiming at the assessment of the surviva......This report is a product of the cooperation agreement between Wave Dragon and Aalborg University regarding phase 2 of the development of the Wave Dragon Wave Energy Converter. The research is carried out by testing the 1:51.8 scale model of the Wave Dragon, aiming at the assessment...... of the department of Civil Engineering at Aalborg University. The outcome of the research will be used as input for future research work aimed at the design of the mooring system and the certification of the structural design for the full scale Wave Dragon demonstrator....

  16. Wave energy extraction by coupled resonant absorbers.

    Science.gov (United States)

    Evans, D V; Porter, R

    2012-01-28

    In this article, a range of problems and theories will be introduced that will build towards a new wave energy converter (WEC) concept, with the acronym 'ROTA' standing for resonant over-topping absorber. First, classical results for wave power absorption for WECs constrained to operate in a single degree of freedom will be reviewed and the role of resonance in their operation highlighted. Emphasis will then be placed on how the introduction of further resonances can improve power take-off characteristics by extending the range of frequencies over which the efficiency is close to a theoretical maximum. Methods for doing this in different types of WECs will be demonstrated. Coupled resonant absorbers achieve this by connecting a WEC device equipped with its own resonance (determined from a hydrodynamic analysis) to a new system having separate mass/spring/damper characteristics. It is shown that a coupled resonant effect can be realized by inserting a water tank into a WEC, and this idea forms the basis of the ROTA device. In essence, the idea is to exploit the coupling between the natural sloshing frequencies of the water in the internal tank and the natural resonance of a submerged buoyant circular cylinder device that is tethered to the sea floor, allowing a rotary motion about its axis of attachment.

  17. Wave energy devices with compressible volumes.

    Science.gov (United States)

    Kurniawan, Adi; Greaves, Deborah; Chaplin, John

    2014-12-08

    We present an analysis of wave energy devices with air-filled compressible submerged volumes, where variability of volume is achieved by means of a horizontal surface free to move up and down relative to the body. An analysis of bodies without power take-off (PTO) systems is first presented to demonstrate the positive effects a compressible volume could have on the body response. Subsequently, two compressible device variations are analysed. In the first variation, the compressible volume is connected to a fixed volume via an air turbine for PTO. In the second variation, a water column separates the compressible volume from another volume, which is fitted with an air turbine open to the atmosphere. Both floating and bottom-fixed, axisymmetric, configurations are considered, and linear analysis is employed throughout. Advantages and disadvantages of each device are examined in detail. Some configurations with displaced volumes less than 2000 m 3 and with constant turbine coefficients are shown to be capable of achieving 80% of the theoretical maximum absorbed power over a wave period range of about 4 s.

  18. Diffuse Waves and Energy Densities Near Boundaries

    Science.gov (United States)

    Sanchez-Sesma, F. J.; Rodriguez-Castellanos, A.; Campillo, M.; Perton, M.; Luzon, F.; Perez-Ruiz, J. A.

    2007-12-01

    Green function can be retrieved from averaging cross correlations of motions within a diffuse field. In fact, it has been shown that for an elastic inhomogeneous, anisotropic medium under equipartitioned, isotropic illumination, the average cross correlations are proportional to the imaginary part of Green function. For instance coda waves are due to multiple scattering and their intensities follow diffusive regimes. Coda waves and the noise sample the medium and effectively carry information along their paths. In this work we explore the consequences of assuming both source and receiver at the same point. From the observable side, the autocorrelation is proportional to the energy density at a given point. On the other hand, the imaginary part of the Green function at the source itself is finite because the singularity of Green function is restricted to the real part. The energy density at a point is proportional with the trace of the imaginary part of Green function tensor at the source itself. The Green function availability may allow establishing the theoretical energy density of a seismic diffuse field generated by a background equipartitioned excitation. We study an elastic layer with free surface and overlaying a half space and compute the imaginary part of the Green function for various depths. We show that the resulting spectrum is indeed closely related to the layer dynamic response and the corresponding resonant frequencies are revealed. One implication of present findings lies in the fact that spatial variations may be useful in detecting the presence of a target by its signature in the distribution of diffuse energy. These results may be useful in assessing the seismic response of a given site if strong ground motions are scarce. It suffices having a reasonable illumination from micro earthquakes and noise. We consider that the imaginary part of Green function at the source is a spectral signature of the site. The relative importance of the peaks of

  19. Layout Optimisation of Wave Energy Converter Arrays

    Directory of Open Access Journals (Sweden)

    Pau Mercadé Ruiz

    2017-08-01

    Full Text Available This paper proposes an optimisation strategy for the layout design of wave energy converter (WEC arrays. Optimal layouts are sought so as to maximise the absorbed power given a minimum q-factor, the minimum distance between WECs, and an area of deployment. To guarantee an efficient optimisation, a four-parameter layout description is proposed. Three different optimisation algorithms are further compared in terms of performance and computational cost. These are the covariance matrix adaptation evolution strategy (CMA, a genetic algorithm (GA and the glowworm swarm optimisation (GSO algorithm. The results show slightly higher performances for the latter two algorithms; however, the first turns out to be significantly less computationally demanding.

  20. Magnetically coupled flextensional transducer for wideband vibration energy harvesting: Design, modeling and experiments

    Science.gov (United States)

    Zou, Hong-Xiang; Zhang, Wen-Ming; Li, Wen-Bo; Wei, Ke-Xiang; Hu, Kai-Ming; Peng, Zhi-Ke; Meng, Guang

    2018-03-01

    The combination of nonlinear bistable and flextensional mechanisms has the advantages of wide operating frequency and high equivalent piezoelectric constant. In this paper, three magnetically coupled flextensional vibration energy harvesters (MF-VEHs) are designed from three magnetically coupled vibration systems which utilize a magnetic repulsion, two symmetrical magnetic attractions and multi-magnetic repulsions, respectively. The coupled dynamic models are developed to describe the electromechanical transitions. Simulations under harmonic excitation and random excitation are carried out to investigate the performance of the MF-VEHs with different parameters. Experimental validations of the MF-VEHs are performed under different excitation levels. The experimental results verify that the developed mathematical models can be used to accurately characterize the MF-VEHs for various magnetic coupling modes. A comparison of three MF-VEHs is provided and the results illustrate that a reasonable arrangement of multiple magnets can reduce the threshold excitation intensity and increase the harvested energy.

  1. Nano-optomechanical transducer

    Science.gov (United States)

    Rakich, Peter T; El-Kady, Ihab F; Olsson, Roy H; Su, Mehmet Fatih; Reinke, Charles; Camacho, Ryan; Wang, Zheng; Davids, Paul

    2013-12-03

    A nano-optomechanical transducer provides ultrabroadband coherent optomechanical transduction based on Mach-wave emission that uses enhanced photon-phonon coupling efficiencies by low impedance effective phononic medium, both electrostriction and radiation pressure to boost and tailor optomechanical forces, and highly dispersive electromagnetic modes that amplify both electrostriction and radiation pressure. The optomechanical transducer provides a large operating bandwidth and high efficiency while simultaneously having a small size and minimal power consumption, enabling a host of transformative phonon and signal processing capabilities. These capabilities include optomechanical transduction via pulsed phonon emission and up-conversion, broadband stimulated phonon emission and amplification, picosecond pulsed phonon lasers, broadband phononic modulators, and ultrahigh bandwidth true time delay and signal processing technologies.

  2. International Energy Agency Ocean Energy Systems Task 10 Wave Energy Converter Modeling Verification and Validation

    DEFF Research Database (Denmark)

    Wendt, Fabian F.; Yu, Yi-Hsiang; Nielsen, Kim

    2017-01-01

    This is the first joint reference paper for the Ocean Energy Systems (OES) Task 10 Wave Energy Converter modeling verification and validation group. The group is established under the OES Energy Technology Network program under the International Energy Agency. OES was founded in 2001 and Task 10 ...

  3. Stakeholder requirements for commercially successful wave energy converter farms

    Energy Technology Data Exchange (ETDEWEB)

    Babarit, Aurélien; Bull, Diana; Dykes, Katherine; Malins, Robert; Nielsen, Kim; Costello, Ronan; Roberts, Jesse; Bittencourt Ferreira, Claudio; Kennedy, Ben; Weber, Jochem

    2017-12-01

    In this study, systems engineering techniques are applied to wave energy to identify and specify stakeholders' requirements for a commercially successful wave energy farm. The focus is on the continental scale utility market. Lifecycle stages and stakeholders are identified. Stakeholders' needs across the whole lifecycle of the wave energy farm are analyzed. A list of 33 stakeholder requirements are identified and specified. This list of requirements should serve as components of a technology performance level metric that could be used by investors and funding agencies to make informed decisions when allocating resources. It is hoped that the technology performance level metric will accelerate wave energy conversion technology convergence.

  4. Wave Energy Converter Annual Energy Production Uncertainty Using Simulations

    Directory of Open Access Journals (Sweden)

    Clayton E. Hiles

    2016-09-01

    Full Text Available Critical to evaluating the economic viability of a wave energy project is: (1 a robust estimate of the electricity production throughout the project lifetime and (2 an understanding of the uncertainty associated with said estimate. Standardization efforts have established mean annual energy production (MAEP as the metric for quantification of wave energy converter (WEC electricity production and the performance matrix approach as the appropriate method for calculation. General acceptance of a method for calculating the MAEP uncertainty has not yet been achieved. Several authors have proposed methods based on the standard engineering approach to error propagation, however, a lack of available WEC deployment data has restricted testing of these methods. In this work the magnitude and sensitivity of MAEP uncertainty is investigated. The analysis is driven by data from simulated deployments of 2 WECs of different operating principle at 4 different locations. A Monte Carlo simulation approach is proposed for calculating the variability of MAEP estimates and is used to explore the sensitivity of the calculation. The uncertainty of MAEP ranged from 2%–20% of the mean value. Of the contributing uncertainties studied, the variability in the wave climate was found responsible for most of the uncertainty in MAEP. Uncertainty in MAEP differs considerably between WEC types and between deployment locations and is sensitive to the length of the input data-sets. This implies that if a certain maximum level of uncertainty in MAEP is targeted, the minimum required lengths of the input data-sets will be different for every WEC-location combination.

  5. Integrated analysis of energy transfers in elastic-wave turbulence.

    Science.gov (United States)

    Yokoyama, Naoto; Takaoka, Masanori

    2017-08-01

    In elastic-wave turbulence, strong turbulence appears in small wave numbers while weak turbulence does in large wave numbers. Energy transfers in the coexistence of these turbulent states are numerically investigated in both the Fourier space and the real space. An analytical expression of a detailed energy balance reveals from which mode to which mode energy is transferred in the triad interaction. Stretching energy excited by external force is transferred nonlocally and intermittently to large wave numbers as the kinetic energy in the strong turbulence. In the weak turbulence, the resonant interactions according to the weak turbulence theory produce cascading net energy transfer to large wave numbers. Because the system's nonlinearity shows strong temporal intermittency, the energy transfers are investigated at active and moderate phases separately. The nonlocal interactions in the Fourier space are characterized by the intermittent bundles of fibrous structures in the real space.

  6. Wave energy resource assessment and review of the technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wan Nik, W.B.: Sulaiman, O.O. [Maritime Technology Department, Universiti Malaysia Terengganu, 21030, Kuala Terengganu (Malaysia); Rosliza, R. [TATI University College, Teluk Kalong, 24000 Kemaman, Terengganu, (Malaysia); Prawoto, Y. [Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM, Skudai, Johor (Malaysia); Muzathik, A.M. [Institute of Technology, University of Moratuwa (Sri Lanka)

    2011-07-01

    Increase in human population has increased the demand for more energy. Technical improvement in transport and electrical appliances gives a lot of facilities to our life nowadays. Still we need to generate or convert this energy. Energy generation based on conventional technologies is always accompanied by environmental pollution. It gives overheating and greenhouse effects that later result in biosphere degradation. Nowadays sea wave energy is being increasingly regarded in many countries as a major and promising resource. It is renewable and environmentally friendly. In this paper wave parameters related to wave energy is analyzed. Then the paper describes the development of many different types of wave-energy converters. Several topics are addressed; the characterization of the wave energy resource, range of devices and how such devices can be organized into classes.

  7. Acceleration of low energy charged particles by gravitational waves

    Energy Technology Data Exchange (ETDEWEB)

    Voyatzis, G. [University of Thessaloniki, Department of Physics, 54124 Thessaloniki (Greece)]. E-mail: voyatzis@auth.gr; Vlahos, L. [University of Thessaloniki, Department of Physics, 54124 Thessaloniki (Greece); Ichtiaroglou, S. [University of Thessaloniki, Department of Physics, 54124 Thessaloniki (Greece); Papadopoulos, D. [University of Thessaloniki, Department of Physics, 54124 Thessaloniki (Greece)

    2006-04-03

    The acceleration of charged particles in the presence of a magnetic field and gravitational waves is under consideration. It is shown that the weak gravitational waves can cause the acceleration of low energy particles under appropriate conditions. Such conditions may be satisfied close to the source of the gravitational waves if the magnetized plasma is in a turbulent state.

  8. Acceleration of low energy charged particles by gravitational waves

    International Nuclear Information System (INIS)

    Voyatzis, G.; Vlahos, L.; Ichtiaroglou, S.; Papadopoulos, D.

    2006-01-01

    The acceleration of charged particles in the presence of a magnetic field and gravitational waves is under consideration. It is shown that the weak gravitational waves can cause the acceleration of low energy particles under appropriate conditions. Such conditions may be satisfied close to the source of the gravitational waves if the magnetized plasma is in a turbulent state

  9. Experimental Validation of a Wave Energy Converter Array Hydrodynamics Tool

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé; Ferri, Francesco; Kofoed, Jens Peter

    2017-01-01

    This paper uses experimental data to validate a wave energy converter (WEC) array hydrodynamics tool developed within the context of linearized potential flow theory. To this end, wave forces and power absorption by an array of five-point absorber WECs in monochromatic and panchromatic waves were...

  10. Opportunities for shear energy scaling in bulk acoustic wave resonators

    NARCIS (Netherlands)

    Jose, Sumy; Hueting, Raymond Josephus Engelbart

    2014-01-01

    An important energy loss contribution in bulk acoustic wave resonators is formed by so-called shear waves, which are transversal waves that propagate vertically through the devices with a horizontal motion. In this work, we report for the first time scaling of the shear-confined spots, i.e., spots

  11. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2016-06-01

    Full Text Available In this paper, a generic coordinated control method for wave energy converters is proposed, and the constraints on motion amplitudes and the hydrodynamic interaction between converters are considered. The objective of the control problem is to maximize the energy converted from ocean waves, and this is achieved by coordinating the power take-off (PTO damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied. In the solution, motion constraints, including constraints on the amplitudes of displacement and velocity, are included. Twelve months of sea states, based on measured wave data at the Lysekil test site on the Swedish west coast, are used in the simulation to evaluate the performance of the wave energy farm using the new method. Results from the new coordinated control method and traditional control method are compared, indicating that the coordinated control of wave energy converters is an effective way to improve the energy production of wave energy farm in harmonic waves.

  12. Energy convergence of shock waves and its destruction mechanism in cone-roof combustion chambers

    International Nuclear Information System (INIS)

    Xu, Han; Yao, Anren; Yao, Chunde; Gao, Jian

    2016-01-01

    Highlights: • Experiments with simulations are designed to probe into engine severe knock. • Energy convergence at central and edge region is observed in closed-limited space. • Modes with different intensities and mechanism of energy convergence are revealed. • Chamber shape and equivalence ratio can affect the energy convergence. • The destruction effects of energy convergence on pistons are recognized. - Abstract: Energy convergence is considered as an important phenomenon in internal combustion engines under severe knock, in which shock waves caused by violent combustion may aggregate the energy released by fuel burning to damage engine parts like pistons and spark plugs easily. In order to reveal such convergence mechanism and its destruction effects, a novel detonation bomb experiment combined with numerical simulations are conducted. In bomb experiments, a detonation wave is forcibly introduced into a clearance-variable cone-roof combustion chamber by a high energy spark ignition. Four pressure transducers were installed in different positions to monitor the energy convergence. Combined with the experiments, numerical simulations were conducted to reveal the convergence modes and mechanisms. Finally, destruction samples were presented to validate this research. It’s found that the energy convergence of shock waves always occurs in middle and edge region, which are vulnerable to be damaged. Three modes of energy convergence are concluded for middle region while several ways of energy convergence are concluded for edge region, which are all related with the chamber shape and may result in different levels of convergence. It’s also found that though detonation strength (knock intensity) can be changed by both equivalence ratios and initial pressures, only the equivalence ratios can change the convergence modes while the initial pressures cannot.

  13. Turbine Control Strategy using Wave Prediction to Optimise Power Take Off of Overtopping Wave Energy Converters

    OpenAIRE

    Tedd, James; Knapp, Wilfried; Frigaard, Peter; Kofoed, Jens Peter

    2005-01-01

    This paper presents the control strategy used on Wave Dragon overtopping wave energy converter. The nature of overtopping requires that for optimum performance the water level in the reservoir must be controlled by controlling the turbine outflows. A history of the simulations performed is included. The concept of including an element of prediction, based on wave records a short distance in front of the Wave Dragon, is introduced. Initial simulations indicate a possibility to increase product...

  14. An innovative approach for energy generation from waves

    Energy Technology Data Exchange (ETDEWEB)

    Al-Habaibeh, A. [Advanced Design and Manufacturing Engineering Centre, School of Architecture, Design and the Built Environment, Nottingham Trent University (United Kingdom); Su, D. [School of Architecture, Design and the Built Environment, Nottingham Trent University (United Kingdom); McCague, J. [Technical Director, Ocean Navitas Ltd., Lincolnshire (United Kingdom); Knight, A. [Marketing and Communications Manager, Ocean Navitas Ltd., Lincolnshire (United Kingdom)

    2010-08-15

    Sustainable energy generation is becoming increasingly important due to the expected limitations in current energy resources and to reduce pollution. Wave energy generation has seen significant development in recent years. This paper describes an innovative system for generating energy from wave power. A complete description of the system is presented including the general concept, configurations, mechanical design, electrical system, simulation techniques and expected power output of the system. The results from the hydraulic linear wave simulator, using a real wave profiles captured at a location in the UK using an ultrasound system, it was seen that a {+-}0.8 m wave at 10 s time period, produced a conditioned power output of approximately 22 kW at optimum load conditions for the tested 3-phase 44 kW permanent magnet generator type STK500. The results indicate that this new technology could provide an efficient and low cost method of generating electricity from waves. (author)

  15. An innovative approach for energy generation from waves

    International Nuclear Information System (INIS)

    Al-Habaibeh, A.; Su, D.; McCague, J.; Knight, A.

    2010-01-01

    Sustainable energy generation is becoming increasingly important due to the expected limitations in current energy resources and to reduce pollution. Wave energy generation has seen significant development in recent years. This paper describes an innovative system for generating energy from wave power. A complete description of the system is presented including the general concept, configurations, mechanical design, electrical system, simulation techniques and expected power output of the system. The results from the hydraulic linear wave simulator, using a real wave profiles captured at a location in the UK using an ultrasound system, it was seen that a ±0.8 m wave at 10 s time period, produced a conditioned power output of approximately 22 kW at optimum load conditions for the tested 3-phase 44 kW permanent magnet generator type STK500. The results indicate that this new technology could provide an efficient and low cost method of generating electricity from waves.

  16. Preliminary Load Estimations for DEXA Wave Energy Device - Hanstholm, Denmark

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter

    by DEXA Wave Energy ApS, in regular and irregular wave states, as described in Assessment of Wave Energy Devices. Best Practice as used in Denmark (Frigaard et al., 2008). The length scale of the model was 1:20 compared to a full scale device suitable fro the Danish part of the North Sea, according...... to DEXA Wave Energy ApS. The tests were carried out at Dept. of Civil Engineering, Aalborg University (AAU) in the 3D deep water wave tank. The displacement and force applied to a power take off system, provided by DEXA Wave Energy ApS, were measured and used for calculation of power available...... to the power take-off....

  17. IMPORTANCE OF MANGROVE TO REDUCE THE TSUNAMI WAVE ENERGY

    Directory of Open Access Journals (Sweden)

    Anastasia Neni Candra Purnamasari

    2017-09-01

    Full Text Available Mangrove has a very important role to reduce the tsunami wave energy. It is shown that the coastal areas have no vegetation or in this case will have an impact Mangrove forests greater damage due to tsunami waves than the coastal areas of vegetation. The purpose of the Term Paper is proved the importance of Mangrove to reduce the tsunami wave energy by comparing the various methods that have been observed in some case studies on the impact of the tsunami that occurred in several Asian countries in 2004 and case studies on ocean waves on the Gulf coast of south Florida. Based on the research results that could dampen Mangrove Tsunami wave energy. Tsunami wave energy can be reduced by several factors, namely mangrove species, tree size, vast mangrove forest, nature tree structure, and the size limit Mangrove forest (as far as how much of the ocean to the surface.

  18. Measurements of Wave Power in Wave Energy Converter Effectiveness Evaluation

    Directory of Open Access Journals (Sweden)

    Berins J.

    2017-08-01

    Full Text Available The article is devoted to the technical solution of alternative budget measuring equipment of the water surface gravity wave oscillation and the theoretical justification of the calculated oscillation power. This solution combines technologies such as lasers, WEB-camera image digital processing, interpolation of defined function at irregular intervals, volatility of discrete Fourier transformation for calculating the spectrum.

  19. Measurements of Wave Power in Wave Energy Converter Effectiveness Evaluation

    Science.gov (United States)

    Berins, J.; Berins, J.; Kalnacs, A.

    2017-08-01

    The article is devoted to the technical solution of alternative budget measuring equipment of the water surface gravity wave oscillation and the theoretical justification of the calculated oscillation power. This solution combines technologies such as lasers, WEB-camera image digital processing, interpolation of defined function at irregular intervals, volatility of discrete Fourier transformation for calculating the spectrum.

  20. Modeling the Buoyancy System of a Wave Energy Power Plant

    DEFF Research Database (Denmark)

    Pedersen, Tom S.; Nielsen, Kirsten M.

    2009-01-01

    A nonlinear dynamic model of the buoyancy system in a wave energy power plant is presented. The plant ("Wave Dragon") is a floating device using the potential energy in overtopping waves to produce power. A water reservoir is placed on top of the WD, and hydro turbines lead the water to the sea...... producing electrical power. Through air chambers it is possible to control the level of the WD. It is important to control the level in order to maximize the power production in proportion to the wave height, here the amount of overtopping water and the amount of potential energy is conflicting...

  1. Hanstholm phase 2B. Offshore wave energy test 1994 - 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    The wave power converter consists of a float 2.5 meter in diameter, connected by a rope to a seabed-mounted piston pump, installed on 25 meter deep water 2,5 km offshore Hanstholm, Denmark. The converter is designed to absorb an average maximum power of 1 kW. Measured data in real sea conditions are compared to results based on computer simulations and previous tank testing. Losses caused by rope elasticity and hysteresis, friction in the pump and back flow through the valves are assessed. The economic perspectives of a large wave power plant are presented, based on a revised prototype incorporating the results and experience gained during the test period. The wave energy conversion test `Hanstholm phase 2B` has showed, that it it technically possible to exploit the offshore wave energy resource. This source of energy could become attractive for commercial enterprise. The wave power converter demonstrated a reliable performance over a period of nine months. It produced energy under all wave conditions and survived storm waves of 9,6 m. A 300 MW wave power plant in the Danish part of the North sea is estimated to produce electricity at a cost between 2,1 - 2,4 DKK/kWh. The electrical transmission to shore contribute to approximately 20% of the cost. New data predict a potential of 23 kW per meter wave front. The energy plan Energy 21 proposed by the Danish Department of Energy, includes a scenario incorporating wave energy in the energy system year 2030. A strategy for the development of wave energy, has been proposed as part of the project OWEC-1 supported by the European Joule R and D programme. A proposal for future Danish initiatives to develop second generation point absorber systems is outlined. (ARW) 29 refs.

  2. Optimized Latching Control of Floating Point Absorber Wave Energy Converter

    Science.gov (United States)

    Gadodia, Chaitanya; Shandilya, Shubham; Bansal, Hari Om

    2018-03-01

    There is an increasing demand for energy in today’s world. Currently main energy resources are fossil fuels, which will eventually drain out, also the emissions produced from them contribute to global warming. For a sustainable future, these fossil fuels should be replaced with renewable and green energy sources. Sea waves are a gigantic and undiscovered vitality asset. The potential for extricating energy from waves is extensive. To trap this energy, wave energy converters (WEC) are needed. There is a need for increasing the energy output and decreasing the cost requirement of these existing WECs. This paper presents a method which uses prediction as a part of the control scheme to increase the energy efficiency of the floating-point absorber WECs. Kalman Filter is used for estimation, coupled with latching control in regular as well as irregular sea waves. Modelling and Simulation results for the same are also included.

  3. Enhancement of particle-wave energy exchange by resonance sweeping

    International Nuclear Information System (INIS)

    Berk, H.L.; Breizman, B.N.

    1995-10-01

    It is shown that as the resonance condition of the particle-wave interaction is varied adiabatically, that the particles trapped in the wave will form phase space holes or clumps that can enhance the particle-wave energy exchange. This mechanism can cause much larger saturation levels of instabilities, and even allow the free energy associated with instability, to be tapped in a system that is linearly stable due to background dissipation

  4. Wave energy budget analysis in the Earth's radiation belts uncovers a missing energy.

    Science.gov (United States)

    Artemyev, A V; Agapitov, O V; Mourenas, D; Krasnoselskikh, V V; Mozer, F S

    2015-05-15

    Whistler-mode emissions are important electromagnetic waves pervasive in the Earth's magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth's magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave-particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth's radiation belts, controlled by solar activity.

  5. An Appraisal of the DEXA Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter

    This report has been requested by VækstFonden and aims at giving an overview of the experimental tests and a general appraisal of the DEXA wave energy converter (WEC). The reported results and findings were obtained during previously performed experimental tests by the Wave Energy Research Group...

  6. Methodology for reliability, economic and environmental assessment of wave energy

    International Nuclear Information System (INIS)

    Thorpe, T.W.; Muirhead, S.

    1994-01-01

    As part of the Preliminary Actions in Wave Energy R and D for DG XII's Joule programme, methodologies were developed to facilitate assessment of the reliability, economics and environmental impact of wave energy. This paper outlines these methodologies, their limitations and areas requiring further R and D. (author)

  7. On Mooring Solutions for Large Wave Energy Converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Kofoed, Jens Peter; Ferri, Francesco

    2017-01-01

    The present paper describes the work carried out in the project ’Mooring Solutions for Large Wave Energy Converters’, which is a Danish research project carried out in a period of three years from September 2014, with the aim of reducing cost of the moorings for four wave energy converters...

  8. Circuit for Driving Piezoelectric Transducers

    Science.gov (United States)

    Randall, David P.; Chapsky, Jacob

    2009-01-01

    The figure schematically depicts an oscillator circuit for driving a piezoelectric transducer to excite vibrations in a mechanical structure. The circuit was designed and built to satisfy application-specific requirements to drive a selected one of 16 such transducers at a regulated amplitude and frequency chosen to optimize the amount of work performed by the transducer and to compensate for both (1) temporal variations of the resonance frequency and damping time of each transducer and (2) initially unknown differences among the resonance frequencies and damping times of different transducers. In other words, the circuit is designed to adjust itself to optimize the performance of whichever transducer is selected at any given time. The basic design concept may be adaptable to other applications that involve the use of piezoelectric transducers in ultrasonic cleaners and other apparatuses in which high-frequency mechanical drives are utilized. This circuit includes three resistor-capacitor networks that, together with the selected piezoelectric transducer, constitute a band-pass filter having a peak response at a frequency of about 2 kHz, which is approximately the resonance frequency of the piezoelectric transducers. Gain for generating oscillations is provided by a power hybrid operational amplifier (U1). A junction field-effect transistor (Q1) in combination with a resistor (R4) is used as a voltage-variable resistor to control the magnitude of the oscillation. The voltage-variable resistor is part of a feedback control loop: Part of the output of the oscillator is rectified and filtered for use as a slow negative feedback to the gate of Q1 to keep the output amplitude constant. The response of this control loop is much slower than 2 kHz and, therefore, does not introduce significant distortion of the oscillator output, which is a fairly clean sine wave. The positive AC feedback needed to sustain oscillations is derived from sampling the current through the

  9. Numerical Transducer Modeling

    DEFF Research Database (Denmark)

    Henriquez, Vicente Cutanda

    This thesis describes the development of a numerical model of the propagation of sound waves in fluids with viscous and thermal losses, with application to the simulation of acoustic transducers, in particular condenser microphones for measurement. The theoretical basis is presented, numerical...... manipulations are developed to satisfy the more complicated boundary conditions, and a model of a condenser microphone with a coupled membrane is developed. The model is tested against measurements of ¼ inch condenser microphones and analytical calculations. A detailed discussion of the results is given....

  10. Deployment Effects of Marine Renewable Energy Technologies: Wave Energy Scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Mirko Previsic

    2010-06-17

    Given proper care in siting, design, deployment, operation and maintenance, wave energy conversion could become one of the more environmentally benign sources of electricity generation. In order to accelerate the adoption of these emerging hydrokinetic and marine energy technologies, navigational and environmental concerns must be identified and addressed. All developing hydrokinetic projects involve a wide variety of stakeholders. One of the key issues that site developers face as they engage with this range of stakeholders is that, due to a lack of technical certainty, many of the possible conflicts (e.g., shipping and fishing) and environmental issues are not well-understood,. In September 2008, re vision consulting, LLC was selected by the Department of Energy (DoE) to apply a scenario-based assessment to the emerging hydrokinetic technology sector in order to evaluate the potential impact of these technologies on the marine environment and navigation constraints. The project’s scope of work includes the establishment of baseline scenarios for wave and tidal power conversion at potential future deployment sites. The scenarios capture variations in technical approaches and deployment scales to properly identify and characterize environmental effects and navigational effects. The goal of the project is to provide all stakeholders with an improved understanding of the potential range of technical attributes and potential effects of these emerging technologies and focus all stakeholders on the critical issues that need to be addressed. By identifying and addressing navigational and environmental concerns in the early stages of the industry’s development, serious mistakes that could potentially derail industry-wide development can be avoided. This groundwork will also help in streamlining siting and associated permitting processes, which are considered key hurdles for the industry’s development in the U.S. today. Re vision is coordinating its efforts with two

  11. Investigation of ultra-high sensitivity Klystron cavity transducers for broadband resonant-mass gravitational wave detectors

    International Nuclear Information System (INIS)

    Pimentel, Guilherme Leite

    2008-01-01

    We show that, with a suitable choice of the parameters of the gravitational wave detector Mario Schoenberg, with technological accessible parameters (using state-of-art electronics), its sensitivity curve can be improved over the current project curve to become competitive with interferometric detectors in a frequency band of 1500 Hz, in the region from 1000 to 10000 Hz (these competitive bands are centered at the sphere's quadrupole modes). The sensitivity curve of an array of 100 identical spheres identical to the Schoenberg one is also analyzed, and is competitive against advanced LIGO in the entire band. A detailed study of the project's viability is conducted, with an emphasis on the project of the klystron resonant cavity, which will have a center post with a 1 nm gap, which represents a great technological challenge. This challenge is analyzed in terms of the cavity project as well as with a focus on the Casimir effect on the cavity. This could open an opportunity for precise measurements of this effect on a new distance scale compared to current measurements (in the μm scale). (author)

  12. Mechanical to electrical energy conversion by shock wave effect in a ferro-electric material

    International Nuclear Information System (INIS)

    David, Jean

    1977-01-01

    The shock wave propagation through a polarized ferroelectric ceramic changes or destroys remanent polarization and this way allows to get, in adequate electrical circuit, a volume energy of about 2 J/ cm 3 , during a time of the order of 0,4 μs; which corresponds to a peak - power of 5 MW/cm 3 . The present report has for objective to specify the optimum working conditions of this mechanical to electrical conversion from ceramic characteristics, load circuit connected to its electrodes and from the characteristics of the pressure wave which travels through the materials which constitute the converter. After a few lines about the ferroelectric materials and about the shock waves, the shock generator, the used setting and measures are described. A mathematical model which exhibits the transducer operation and a computation of the allowable electrical energy are given. For ending, the released electrical energies by industrial and laboratory ceramics are compared to the estimated computations and a thermodynamical balance is carried out. (author) [fr

  13. Power from the seas - Wave energy has a big future

    International Nuclear Information System (INIS)

    Schenler, W.

    2008-01-01

    This article takes a look at how the energy of the oceans' waves can become an important source of energy. The generation of the energy contained in waves as an indirect form of solar energy is described. The energy potential offered is quoted as being high in the Atlantic near England and Scotland. The article goes on the discuss the technical potential of this form of renewable energy and provides a map showing this. Financial aspects and economic potentials are discussed. Effects on the environment are also discussed. The on-shore and off-shore technologies that can be used to capture wave energy are described and discussed, as is the combination of power production from wind and waves

  14. Micromachined capacitive ultrasonic immersion transducer array

    Science.gov (United States)

    Jin, Xuecheng

    Capacitive micromachined ultrasonic transducers (cMUTs) have emerged as an attractive alternative to conventional piezoelectric ultrasonic transducers. They offer performance advantages of wide bandwidth and sensitivity that have heretofore been attainable. In addition, micromachining technology, which has benefited from the fast-growing microelectronics industry, enables cMUT array fabrication and electronics integration. This thesis describes the design and fabrication of micromachined capacitive ultrasonic immersion transducer arrays. The basic transducer electrical equivalent circuit is derived from Mason's theory. The effects of Lamb waves and Stoneley waves on cross coupling and acoustic losses are discussed. Electrical parasitics such as series resistance and shunt capacitance are also included in the model of the transducer. Transducer fabrication technology is systematically studied. Device dimension control in both vertical and horizontal directions, process alternatives and variations in membrane formation, via etch and cavity sealing, and metalization as well as their impact on transducer performance are summarized. Both 64 and 128 element 1-D array transducers are fabricated. Transducers are characterized in terms of electrical input impedance, bandwidth, sensitivity, dynamic range, impulse response and angular response, and their performance is compared with theoretical simulation. Various schemes for cross coupling reduction is analyzed, implemented, and verified with both experiments and theory. Preliminary results of immersion imaging are presented using 64 elements 1-D array transducers for active source imaging.

  15. A wave model test bed study for wave energy resource characterization

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Neary, Vincent S.; Wang, Taiping; Gunawan, Budi; Dallman, Annie R.; Wu, Wei-Cheng

    2017-12-01

    This paper presents a test bed study conducted to evaluate best practices in wave modeling to characterize energy resources. The model test bed off the central Oregon Coast was selected because of the high wave energy and available measured data at the site. Two third-generation spectral wave models, SWAN and WWIII, were evaluated. A four-level nested-grid approach—from global to test bed scale—was employed. Model skills were assessed using a set of model performance metrics based on comparing six simulated wave resource parameters to observations from a wave buoy inside the test bed. Both WWIII and SWAN performed well at the test bed site and exhibited similar modeling skills. The ST4 package with WWIII, which represents better physics for wave growth and dissipation, out-performed ST2 physics and improved wave power density and significant wave height predictions. However, ST4 physics tended to overpredict the wave energy period. The newly developed ST6 physics did not improve the overall model skill for predicting the six wave resource parameters. Sensitivity analysis using different wave frequencies and direction resolutions indicated the model results were not sensitive to spectral resolutions at the test bed site, likely due to the absence of complex bathymetric and geometric features.

  16. Reliability Study of Energy Harvesting from Sea Waves by Piezoelectric Patches Consideraing Random JONSWAP Wave Theory

    Directory of Open Access Journals (Sweden)

    M. Ettefagh

    2018-03-01

    Full Text Available One of the new methods for powering low-power electronic devices employed in the sea, is using of mechanical energies of sea waves. In this method, piezoelectric material is employed to convert the mechanical energy of sea waves into electrical energy. The advantage of this method is based on not implementing the battery charging system. Although, many studies have been done about energy harvesting from sea waves, energy harvesting with considering random JONWSAP wave theory is not fully studied up to now. The random JONSWAP wave model is a more realistic approximation of sea waves in comparison of Airy wave model. Therefore, in this paper a vertical beam with the piezoelectric patches, which is fixed to the seabed, is considered as energy harvester system. The energy harvesting system is simulated by MATLAB software, and then the vibration response of the beam and consequently the generated power is obtained considering the JONWSAP wave theory. In addition, the reliability of the system and the effect of piezoelectric patches uncertainties on the generated power are studied by statistical method. Furthermore, the failure possibility of harvester based on violation criteria is investigated.  

  17. Preliminary Analysis of a Submerged Wave Energy Device

    Science.gov (United States)

    Wagner, J. R.; Wagner, J. J.; Hayatdavoodi, M.; Ertekin, R. C.

    2016-02-01

    Preliminary analysis of a submerged wave energy harvesting device is presented. The device is composed of a thin, horizontally submerged plate that is restricted to heave oscillations under the influence of surface waves. The submerged plate is oscillating, and it can be attached to a fixed rotor, or a piston, to harvest the wave energy. A fully submerged wave energy converter is preferred over a surface energy convertor due to its durability and less visual and physical distractions it presents. In this study, the device is subject to nonlinear shallow-water waves. Wave loads on the submerged oscillating plate are obtained via the Level I Green-Naghdi equations. The unsteady motion of the plate is obtained by solving the nonlinear equations of motion. The results are obtained for a range of waves with varying heights and periods. The amplitude and period of plate oscillations are analyzed as functions of the wave parameters and plate width. Particular attention is given to the selection of the site of desired wave field. Initial estimation on the amount of energy extraction from the device, located near shore at a given site, is provided.

  18. Energy Relations for Plane Waves Reflected from Moving Media

    DEFF Research Database (Denmark)

    Daly, P.; Gruenberg, Harry

    1967-01-01

    When a plane wave is obliquely incident from vacuum on a semi-infinite moving medium, the energy flow carried by the incident wave, is in general, not carried away by the reflected and transmitted waves. This is only the case when the medium velocity is parallel to its vacuum interface. Otherwise...... there is a net inflow or outflow of electromagnetic energy, which can be accounted for by the change of stored energy in the system, and the work done by the mechanical forces acting on the medium. A detailed energy balance is drawn up for two different media moving normal to their vacuum interfaces: (a...

  19. Enhancing Wave Energy Competitiveness through Co-Located Wind and Wave Energy Farms. A Review on the Shadow Effect

    Directory of Open Access Journals (Sweden)

    Sharay Astariz

    2015-07-01

    Full Text Available Wave energy is one of the most promising alternatives to fossil fuels due to the enormous available resource; however, its development may be slowed as it is often regarded as uneconomical. The largest cost reductions are expected to be obtained through economies of scale and technological progress. In this sense, the incorporation of wave energy systems into offshore wind energy farms is an opportunity to foster the development of wave energy. The synergies between both renewables can be realised through these co-located energy farms and, thus, some challenges of offshore wind energy can be met. Among them, this paper focuses on the longer non-operational periods of offshore wind turbines—relative to their onshore counterparts—typically caused by delays in maintenance due to the harsh marine conditions. Co-located wave energy converters would act as a barrier extracting energy from the waves and resulting in a shielding effect over the wind farm. On this basis, the aim of this paper is to analyse wave energy economics in a holistic way, as well as the synergies between wave and offshore wind energy, focusing on the shadow effect and the associated increase in the accessibility to the wind turbines.

  20. Wave-packet revivals for quantum systems with nondegenerate energies

    International Nuclear Information System (INIS)

    Bluhm, R.; Tudose, B.

    1996-01-01

    The revival structure of wave packets is examined for quantum systems having energies that depend on two nondegenerate quantum numbers. For such systems, the evolution of the wave packet is controlled by two classical periods and three revival times. These wave packets exhibit quantum beats in the initial motion as well as new types of long-term revivals. The issue of whether fractional revivals can form is addressed. We present an analytical proof showing that at certain times equal to rational fractions of the revival times the wave packet can reform as a sum of subsidiary waves and that both conventional and new types of fractional revivals can occur. (orig.)

  1. Wave Loadings Acting on an Innovative Breakwater for Energy Production

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Ciardulli, F.; Buccino, M.

    2011-01-01

    The paper reports on 2D small scale experiments conducted to investigate wave loadings acting on a pilot project of device for the conversion of wave energy into electricity. The conversion concept is based on the overtopping principle and the structure is worldwide known with the acronym SSG....... The hydraulic model tests have been carried out at the LInC laboratory of the University of Naples Federico II using random waves. Results indicate wave overtopping is able to cause a sudden inversion of vertical force under wave crest, so that it is alternatively upward and downward directed over a short time...

  2. Electricity from wave and tide an introduction to marine energy

    CERN Document Server

    Lynn, Paul A

    2014-01-01

    This is a concise yet technically authoritative overview of modern marine energy devices with the goal of sustainable electricity generation. With 165 full-colour illustrations and photographs of devices at an advanced stage, the book provides inspiring case studies of today's most promising marine energy devices and developments, including full-scale grid-connected prototypes tested in sea conditions. It also covers the European Marine Energy Centre (EMEC) in Orkney, Scotland, where many of the devices are assessed. Topics discussed: global resources - drawing energy from the World's waves and tides history of wave and tidal stream systems theoretical background to modern developments conversion of marine energy into grid electricity modern wave energy converters and tidal stream energy converters. This book is aimed at a wide readership including professionals, policy makers and employees in the energy sector needing an introduction to marine energy. Its descriptive style and technical level will also appea...

  3. Second generation wave energy device - the clam concept

    Energy Technology Data Exchange (ETDEWEB)

    Bellamy, N.W.

    1981-01-01

    A device concept is presented which has arisen from a system approach adopted by a research group with considerable experience in the discipline of wave energy. The Clam, which can be classified as a spine-based pneumatic terminator, is deemed to be a second generation wave energy device in that it tries to utilize system components already identified as attractive, while at the same time avoiding known problem areas. A working model of this wave power device at an engineering scale is discussed for trials in real waves. 3 refs.

  4. Recent Developments of Wave Energy Utilization in Denmark

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Kramer, Morten

    2006-01-01

    by a more thorough description of three ongoing projects. These are Wave Dragon, Wave Star and Seawave Slot-cone Generator. Common for these projects are that they are being, or will soon be, tested in real sea and have benefited from the Danish Wave Energy Program. The work by the department......This paper aims at giving an overview of the developments researchers at the Department of Civil Engineering, Aalborg University, Denmark (DCE), have been involved in within the field of wave energy utilization in Denmark over the past decade. At first a general introduction is given followed...... on these projects involves substantial laboratory testing, numerical simulations and real sea prototype testing....

  5. Life cycle assessment of the wave energy converter: Wave Dragon

    DEFF Research Database (Denmark)

    Hans Chr., Sørensen; Stefan, Naef; Stefan, Anderberg

    Any power production technology should be able to demonstrate that it's able to comply with current and future environmental regulation and that it demonstrates a considerable surplus in the energy balance being a part of the entire power system. This means that the energy used throughout all the...

  6. Modelling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Pecher, Arthur; Kofoed, Jens Peter

    2010-01-01

    The Wave Dragon is a floating slack-moored Wave Energy Converter of the overtopping type, which is facing now the last phase of development before the commercial exploitation: the deployment of a full-scale demonstrator. In this phase a modelling tool allowing for accurate predictions of the perf......The Wave Dragon is a floating slack-moored Wave Energy Converter of the overtopping type, which is facing now the last phase of development before the commercial exploitation: the deployment of a full-scale demonstrator. In this phase a modelling tool allowing for accurate predictions...

  7. Analytical and computational modelling for wave energy systems: the example of oscillating wave surge converters

    Science.gov (United States)

    Dias, Frédéric; Renzi, Emiliano; Gallagher, Sarah; Sarkar, Dripta; Wei, Yanji; Abadie, Thomas; Cummins, Cathal; Rafiee, Ashkan

    2017-08-01

    The development of new wave energy converters has shed light on a number of unanswered questions in fluid mechanics, but has also identified a number of new issues of importance for their future deployment. The main concerns relevant to the practical use of wave energy converters are sustainability, survivability, and maintainability. Of course, it is also necessary to maximize the capture per unit area of the structure as well as to minimize the cost. In this review, we consider some of the questions related to the topics of sustainability, survivability, and maintenance access, with respect to sea conditions, for generic wave energy converters with an emphasis on the oscillating wave surge converter. New analytical models that have been developed are a topic of particular discussion. It is also shown how existing numerical models have been pushed to their limits to provide answers to open questions relating to the operation and characteristics of wave energy converters.

  8. Analytical and computational modelling for wave energy systems: the example of oscillating wave surge converters.

    Science.gov (United States)

    Dias, Frédéric; Renzi, Emiliano; Gallagher, Sarah; Sarkar, Dripta; Wei, Yanji; Abadie, Thomas; Cummins, Cathal; Rafiee, Ashkan

    2017-01-01

    The development of new wave energy converters has shed light on a number of unanswered questions in fluid mechanics, but has also identified a number of new issues of importance for their future deployment. The main concerns relevant to the practical use of wave energy converters are sustainability, survivability, and maintainability. Of course, it is also necessary to maximize the capture per unit area of the structure as well as to minimize the cost. In this review, we consider some of the questions related to the topics of sustainability, survivability, and maintenance access, with respect to sea conditions, for generic wave energy converters with an emphasis on the oscillating wave surge converter. New analytical models that have been developed are a topic of particular discussion. It is also shown how existing numerical models have been pushed to their limits to provide answers to open questions relating to the operation and characteristics of wave energy converters.

  9. Numerical Modeling of a Wave Energy Point Absorber

    DEFF Research Database (Denmark)

    Hernandez, Lorenzo Banos; Frigaard, Peter; Kirkegaard, Poul Henning

    2009-01-01

    The present study deals with numerical modelling of the Wave Star Energy WSE device. Hereby, linear potential theory is applied via a BEM code on the wave hydrodynamics exciting the floaters. Time and frequency domain solutions of the floater response are determined for regular and irregular seas....... Furthermore, these results are used to estimate the power and the energy absorbed by a single oscillating floater. Finally, a latching control strategy is analysed in open-loop configuration for energy maximization....

  10. Wave Energy Resource along the Coast of Santa Catarina (Brazil

    Directory of Open Access Journals (Sweden)

    Pasquale Contestabile

    2015-12-01

    Full Text Available Brazil has one of the largest electricity markets in South America, which needs to add 6000 MW of capacity every year in order to satisfy growing the demand from an increasing and more prosperous population. Apart from biomass, no other renewable energy sources, besides hydroelectricity, play a relevant role in the energy mix. The potential for wind and wave energy is very large. Brazil's Santa Catarina state government is starting a clean energy program in the state, which is expected to bring more than 1 GW of capacity. Assessment of wave energy resources is needed along the coastline. This work studied the potential wave energy along the north-central coasts of Santa Catarina, in Southern Brazil, by analysis of the hindcast data from the European Centre for Medium-Range Weather Forecasts (ECMWF. The annual offshore wave power was found to be equal to 15.25 kW/m, the bulk of which is provided by southeastern waves. The nearshore energetic patterns were studied by means of a numerical coastal propagation model (Mike21 SW. The mean wave power of 20 m isobaths is 11.43 kW/m. Supplementary considerations are drawn on realistic perspectives for wave energy converters installations.

  11. ENERGY CONTENT AND PROPAGATION IN TRANSVERSE SOLAR ATMOSPHERIC WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, M.; Van Doorsselaere, T. [Centre for mathematical Plasma Astrophysics, Mathematics Department, Celestijnenlaan 200B bus 2400, B-3001 Heverlee (Belgium); Soler, R. [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Verth, G., E-mail: tom.vandoorsselaere@wis.kuleuven.be [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield S3 7RH (United Kingdom)

    2013-05-10

    Recently, a significant amount of transverse wave energy has been estimated propagating along solar atmospheric magnetic fields. However, these estimates have been made with the classic bulk Alfven wave model which assumes a homogeneous plasma. In this paper, the kinetic, magnetic, and total energy densities and the flux of energy are computed for transverse MHD waves in one-dimensional cylindrical flux tube models with a piecewise constant or continuous radial density profile. There are fundamental deviations from the properties for classic bulk Alfven waves. (1) There is no local equipartition between kinetic and magnetic energy. (2) The flux of energy and the velocity of energy transfer have, in addition to a component parallel to the magnetic field, components in the planes normal to the magnetic field. (3) The energy densities and the flux of energy vary spatially, contrary to the case of classic bulk Alfven waves. This last property has the important consequence that the energy flux computed with the well known expression for bulk Alfven waves could overestimate the real flux by a factor in the range 10-50, depending on the flux tube equilibrium properties.

  12. Steerable Doppler transducer probes

    International Nuclear Information System (INIS)

    Fidel, H.F.; Greenwood, D.L.

    1986-01-01

    An ultrasonic diagnostic probe is described which is capable of performing ultrasonic imaging and Doppler measurement consisting of: a hollow case having an acoustic window which passes ultrasonic energy and including chamber means for containing fluid located within the hollow case and adjacent to a portion of the acoustic window; imaging transducer means, located in the hollow case and outside the fluid chamber means, and oriented to direct ultrasonic energy through the acoustic window toward an area which is to be imaged; Doppler transducer means, located in the hollow case within the fluid chamber means, and movably oriented to direct Doppler signals through the acoustic window toward the imaged area; means located within the fluid chamber means and externally controlled for controllably moving the Doppler transducer means to select one of a plurality of axes in the imaged area along which the Doppler signals are to be directed; and means, located external to the fluid chamber means and responsive to the means for moving, for providing an indication signal for identifying the selected axis

  13. Transducers and microprocessors in oceanographic applications

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, R.G.P.; Desa, E.

    Transducers used for the sensing of the ten most measured marine parameters have been described in this paper. The ten parameters have been classed under 5 sensor types, namely temperature, pressure, salinity, currents and waves. For each sensor...

  14. Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave.

    Science.gov (United States)

    Gershman, Daniel J; F-Viñas, Adolfo; Dorelli, John C; Boardsen, Scott A; Avanov, Levon A; Bellan, Paul M; Schwartz, Steven J; Lavraud, Benoit; Coffey, Victoria N; Chandler, Michael O; Saito, Yoshifumi; Paterson, William R; Fuselier, Stephen A; Ergun, Robert E; Strangeway, Robert J; Russell, Christopher T; Giles, Barbara L; Pollock, Craig J; Torbert, Roy B; Burch, James L

    2017-03-31

    Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.

  15. Wave-Particle Energy Exchange Directly Observed in a Kinetic Alfven-Branch Wave

    Science.gov (United States)

    Gershman, Daniel J.; F-Vinas, Adolfo; Dorelli, John C.; Boardsen, Scott A. (Inventor); Avanov, Levon A.; Bellan, Paul M.; Schwartz, Steven J.; Lavraud, Benoit; Coffey, Victoria N.; Chandler, Michael O.; hide

    2017-01-01

    Alfven waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres, and astrophysical systems, but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASAs Magnetospheric Multiscale (MMS) mission, we utilize Earths magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfven wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via non-linear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.

  16. Specification of Instrumentation of Multi MW Wave Dragon Offshore Wave Energy Converter

    DEFF Research Database (Denmark)

    Gilling, Lasse; Kofoed, Jens Peter

    Wave Dragon is a wave energy converter of the overtopping type and is described e.g. in Tedd et. al. (2006). The device has been thoroughly tested on a 1:51.8 scale model in wave laboratories and a 1:4.5 scale model deployed in Nissum Bredning, a large inland waterway in Denmark. Based on the exp......Wave Dragon is a wave energy converter of the overtopping type and is described e.g. in Tedd et. al. (2006). The device has been thoroughly tested on a 1:51.8 scale model in wave laboratories and a 1:4.5 scale model deployed in Nissum Bredning, a large inland waterway in Denmark. Based...

  17. Wave energy potential: A forecasting system for the Mediterranean basin

    International Nuclear Information System (INIS)

    Carillo, Adriana; Sannino, Gianmaria; Lombardi, Emanuele

    2015-01-01

    ENEA is performing ocean wave modeling activities with the aim of both characterizing the Italian sea energy resource and providing the information necessary for the experimental at sea and operational phases of energy converters. Therefore a forecast system of sea waves and of the associated energy available has been developed and has been operatively running since June 2013. The forecasts are performed over the entire Mediterranean basin and, at a higher resolution, over ten sub-basins around the Italian coasts. The forecast system is here described along with the validation of the wave heights, performed by comparing them with the measurements from satellite sensors. [it

  18. FEATURES OF ELECTROMECHANICAL ACOUSTIC ENERGY CONVERSION BY CYLINDRICAL PIEZOCERAMIC TRANSDUCERS WITH INTERNAL SCREENS IN COMPOSITION OF FLAT SYSTEMS

    Directory of Open Access Journals (Sweden)

    A. G. Leiko

    2018-01-01

    Full Text Available The problem of sound emission is considered by a system formed from cylindrical piezoceramic radiators with internal acoustically soft screens. Longitudinal axis of emitters lie in one plane. This system is characterized by the interaction of electric, mechanical and acoustic fields in the process of conversion electrical energy to acoustical energy and acoustic fields in the process of forming them in the environments. The purpose of the work is to determine the peculiarities of the electromechanical acoustic transformation of energy by cylindrical piezoceramic radiators with internal screens in the composition of flat systems, taking into account all types of interaction.The research was carried out by the method of bound fields in multiply connected domains with the use of addition theorems for the cylindrical wave functions. The physical fields arising from the emission of sound by such a system are determined by the joint solution of the system of differential equations: the wave equation; equations of motion of thin piezoceramic shells with circular polarization in displacements; the equations of forced electrostatics for piezoceramics at given boundary conditions, the conditions of conjugation of fields at the boundaries of the division of domains and electric conditions.The solution of the problem is reduced to the solution of an infinite system of linear algebraic equations with respect to unknown coefficients of field expansions.An analysis of the results of numerical calculations, performed on the basis of the obtained analytical relations, called to establish a number of features in the electromechanical acoustic transformation of energy by emitters in the composition of flat systems. They include: the role of acoustic interaction in the process of energy conversion; determination of the mechanism of quantitative assessment of the influence of interaction on these processes; the dependence of the degree of violation of the radial

  19. Nonlinear Passive Control of a Wave Energy Converter Subject to Constraints in Irregular Waves

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2015-06-01

    Full Text Available This paper investigates a passive control method of a point absorbing wave energy converter by considering the displacement and velocity constraints under irregular waves in the time domain. A linear generator is used as a power take-off unit, and the equivalent damping force is optimized to improve the power production of the wave energy converter. The results from nonlinear and linear passive control methods are compared, and indicate that the nonlinear passive control method leads to the excitation force in phase with the velocity of the converter that can significantly improve the energy production of the converter.

  20. Transmission of wave energy through an offshore wind turbine farm

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Johnson, Martin; Sørensen, Ole Rene

    2013-01-01

    condition at infinity. From airborne and Satellite SAR (Synthetic Aperture Radar) a model has been derived for the change of the water surface friction C) inside and on the lee side of the offshore wind farm. The effects have been implemented in a spectral wind wave model,MIKE21 SW, and a parametric study......The transmission of wave energy passing an offshore wind farm is studied. Three effects that can change the wave field are analysed, which is the A) energy dissipation due to drag resistance, B) wave reflection/diffraction from structures, and C) the effect of a modified wind field inside...... and on the lee side of the wind farm. The drag dissipation, A), is quantified by a quadratic resistance law. The effect of B) is parameterised based on 1st order potential theory. A method to find the amount of reflected and transmitted wave energy is developed based on the panel method WAMIT™ and a radiation...

  1. Experimental investigation of rubble mound breakwaters for wave energy conversion

    DEFF Research Database (Denmark)

    Luppa, C.; Contestabile, P.; Cavallaro, L.

    2015-01-01

    The paper describes recent laboratory investigation on the breakwater integrated device named “OBREC” (Overtopping BReakwater for Energy Conversion). This technology recently appeared on the wave energy converter scene as an executive outcome of improving composite seawalls by including overtoppi......-by-wave measurement of couples of hydraulic head-flow rate acting on a virtual turbine inlet. Finally, the influence of draft length on overtopping discharge has been identified....... type wave energy converters [1]. Two complementary experimental campaigns were carried out, in 2012 and in 2014. Several geometries and wave conditions were examined. Preliminary comparison of hydraulic behaviour has been summarized, focusing on reflection analysis and overtopping flow rate....... Preliminary design formulae are presented to predict overtopping at the rear side of the structure and in to the front reservoir based on both datasets. Moreover, some important results have been presented on hydraulic behaviour of OBREC with saturated reservoir. Particularly attention is paid to wave...

  2. Interaction of two walkers: wave-mediated energy and force.

    Science.gov (United States)

    Borghesi, Christian; Moukhtar, Julien; Labousse, Matthieu; Eddi, Antonin; Fort, Emmanuel; Couder, Yves

    2014-12-01

    A bouncing droplet, self-propelled by its interaction with the waves it generates, forms a classical wave-particle association called a "walker." Previous works have demonstrated that the dynamics of a single walker is driven by its global surface wave field that retains information on its past trajectory. Here we investigate the energy stored in this wave field for two coupled walkers and how it conveys an interaction between them. For this purpose, we characterize experimentally the "promenade modes" where two walkers are bound and propagate together. Their possible binding distances take discrete values, and the velocity of the pair depends on their mutual binding. The mean parallel motion can be either rectilinear or oscillating. The experimental results are recovered analytically with a simple theoretical framework. A relation between the kinetic energy of the droplets and the total energy of the standing waves is established.

  3. Quantifying the Benefits of Combining Offshore Wind and Wave Energy

    Science.gov (United States)

    Stoutenburg, E.; Jacobson, M. Z.

    2009-12-01

    For many locations the offshore wind resource and the wave energy resource are collocated, which suggests a natural synergy if both technologies are combined into one offshore marine renewable energy plant. Initial meteorological assessments of the western coast of the United States suggest only a weak correlation in power levels of wind and wave energy at any given hour associated with the large ocean basin wave dynamics and storm systems of the North Pacific. This finding indicates that combining the two power sources could reduce the variability in electric power output from a combined wind and wave offshore plant. A combined plant is modeled with offshore wind turbines and Pelamis wave energy converters with wind and wave data from meteorological buoys operated by the US National Buoy Data Center off the coast of California, Oregon, and Washington. This study will present results of quantifying the benefits of combining wind and wave energy for the electrical power system to facilitate increased renewable energy penetration to support reductions in greenhouse gas emissions, and air and water pollution associated with conventional fossil fuel power plants.

  4. Quasi-static analysis of wave loadings on spine-based wave energy devices

    Energy Technology Data Exchange (ETDEWEB)

    Lockett, F.P.; Peatfield, A.M.; West, M.J.

    1980-02-01

    A report is given on the Wave Energy Research Programme at Lanchester Polytechnic. Results are presented for both theoretical and experimental scale models for wave loadings on circular and rectangular spines of various lengths. The results are in good agreement over the operational wave range for the 1/50 scale model and for the more limited data on the 1/10 scale model.

  5. What can wave energy learn from offshore oil and gas?

    Science.gov (United States)

    Jefferys, E R

    2012-01-28

    This title may appear rather presumptuous in the light of the progress made by the leading wave energy devices. However, there may still be some useful lessons to be learnt from current 'offshore' practice, and there are certainly some awful warnings from the past. Wave energy devices and the marine structures used in oil and gas exploration as well as production share a common environment and both are subject to wave, wind and current loads, which may be evaluated with well-validated, albeit imperfect, tools. Both types of structure can be designed, analysed and fabricated using similar tools and technologies. They fulfil very different missions and are subject to different economic and performance requirements; hence 'offshore' design tools must be used appropriately in wave energy project and system design, and 'offshore' cost data should be adapted for 'wave' applications. This article reviews the similarities and differences between the fields and highlights the differing economic environments; offshore structures are typically a small to moderate component of field development cost, while wave power devices will dominate overall system cost. The typical 'offshore' design process is summarized and issues such as reliability-based design and design of not normally manned structures are addressed. Lessons learned from poor design in the past are discussed to highlight areas where care is needed, and wave energy-specific design areas are reviewed. Opportunities for innovation and optimization in wave energy project and device design are discussed; wave energy projects must ultimately compete on a level playing field with other routes to low CO₂ energy and/or energy efficiency. This article is a personal viewpoint and not an expression of a ConocoPhillips position.

  6. Energy cascading in the beat-wave accelerator

    International Nuclear Information System (INIS)

    McKinstrie, C.J.; Batha, S.H.

    1987-01-01

    A review is given of energy cascading in the beat-wave accelerator. The properties of the electromagnetic cascade and the corresponding plasma-wave evolution are well understood within the framework of an approximate analytic model. Based on this model, idealized laser-plasma coupling efficiencies of the order of 10% do not seem unreasonable. 28 refs

  7. Wave energy absorption by a floating air bag

    DEFF Research Database (Denmark)

    Kurniawan, Adi; Chaplin, John; Greaves, Deborah

    2017-01-01

    A floating air bag, ballasted in water, expands and contracts as it heaves under wave action. Connecting the bag to a secondary volume via a turbine transforms the bag into a device capable of generating useful energy from the waves. Small-scale measurements of the device reveal some interesting...

  8. Simplified Design Procedures for Moorings of Wave-Energy Converters

    DEFF Research Database (Denmark)

    Bergdahl, Lars; Kofoed, Jens Peter

    The goal of the report is that the reader shall be able to self-dependently make a first, preliminary analysis of wave-induced horizontal loads, motions and mooring forces for a moored floating wave energy device. Necessary prerequisites to attain that goal are the understanding of the physical p...

  9. Hydrodynamic Modelling and Layout Optimisation of Wave Energy Converter Arrays

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé

    2017-01-01

    in various positions and orientations are finally investigated. This thesis intends in this way to offer a practical approach to the analysis of wave energy converters when they operate together as an array and the optimal design of array layouts. The topics covered by the text include propagation of waves...

  10. Determination of wave energy potential of black sea

    NARCIS (Netherlands)

    Bingölbali, Bilal; Akpınar, Adem; van Vledder, G.P.; Lynett, P.

    2016-01-01

    This study aims to assess wave energy potential and its long-term spatial and temporal characteristics in the Black Sea within the TUBITAK research project (Akpınar et al., 2015). With this purpose, a wave model (SWAN model version 41.01 driven by the CFSR winds) over the entire Black Sea was

  11. Turbine Control Strategy using Wave Prediction to Optimise Power Take Off of Overtopping Wave Energy Converters

    DEFF Research Database (Denmark)

    Tedd, James; Knapp, Wilfried; Frigaard, Peter

    2005-01-01

    This paper presents the control strategy used on Wave Dragon overtopping wave energy converter. The nature of overtopping requires that for optimum performance the water level in the reservoir must be controlled by controlling the turbine outflows. A history of the simulations performed is included...

  12. Energy balance of plasma with wave taking the nonpotential nature of the waves into consideration

    International Nuclear Information System (INIS)

    Gel'berg, M.G.; Volosevich, A.V.

    1986-01-01

    It is shown that in the ionospheric plasma the potential electric field of low-frequency plasma waves is shifted in phase with respect to fluctuations of current by approximately -π/2 and the rotational field is almost in phase with the current. Therefore, the energy transfer between the plasma and the wave occurs mainly with the participation of rotational field

  13. Plan for the Brent Spar. Wind and wave energy converter

    International Nuclear Information System (INIS)

    De Vries, E.

    1996-01-01

    In a competition on the future of the much discussed oil platform Brent Spar of Shell the idea to retrofit the platform into a combined wind/wave energy converter appears to be an attractive option for Shell

  14. Further development of the SEA-Clam wave energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Bellamy, N.W.; Peatfield, A.M.

    1984-04-01

    The final design of the SEA-Clam as a unit for a large 2 GW scheme has been described. This is the leading wave energy device arising out of the UK National Wave Energy Program and is seen as having the greatest potential for further development particularly for smaller scale applications. The small scale market for wave energy is examined and the design and cost parameters evaluated for the 250 kW to 1000 kW range of SEA-Clam units. Building a demonstration prototype rated at 650 kW and producing an annual average output of 250 kW is identified as the next step towards the commercial exploitation of wave energy.

  15. Internal wave energy radiated from a turbulent mixed layer

    Energy Technology Data Exchange (ETDEWEB)

    Munroe, James R., E-mail: jmunroe@mun.ca [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada); Sutherland, Bruce R., E-mail: bsuther@ualberta.ca [Departments of Physics and Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada)

    2014-09-15

    We examine mixed-layer deepening and the generation of internal waves in stratified fluid resulting from turbulence that develops in response to an applied surface stress. In laboratory experiments the stress is applied over the breadth of a finite-length tank by a moving roughened conveyor belt. The turbulence in the shear layer is characterized using particle image velocimetry to measure the kinetic energy density. The internal waves are measured using synthetic schlieren to determine their amplitudes, frequencies, and energy density. We also perform fully nonlinear numerical simulations restricted to two dimensions but in a horizontally periodic domain. These clearly demonstrate that internal waves are generated by transient eddies at the integral length scale of turbulence and which translate with the background shear along the base of the mixed layer. In both experiments and simulations we find that the energy density of the generated waves is 1%–3% of the turbulent kinetic energy density of the turbulent layer.

  16. Concept Study of Foundation Systems for Wave Energy Converters

    DEFF Research Database (Denmark)

    Molina, Salvador Devant; Vaitkunaite, Evelina; Ibsen, Lars Bo

    Analysis of possible foundation solution for Wave Energy Converters (WEC) is presented by investigating and optimizing novel foundation systems recently developed for offshore wind turbines. Gravity based, pile and bucket foundations are innovative foundation systems that are analyzed. Concept...

  17. Wave Resource Characterization at US Wave Energy Converter (WEC) Test Sites

    Science.gov (United States)

    Dallman, A.; Neary, V. S.

    2016-02-01

    The US Department of Energy's (DOE) Marine and Hydrokinetic energy (MHK) Program is supporting a diverse research and development portfolio intended to accelerate commercialization of the marine renewable industry by improving technology performance, reducing market barriers, and lowering the cost of energy. Wave resource characterization at potential and existing wave energy converter (WEC) test sites and deployment locations contributes to this DOE goal by providing a catalogue of wave energy resource characteristics, met-ocean data, and site infrastructure information, developed utilizing a consistent methodology. The purpose of the catalogue is to enable the comparison of resource characteristics among sites to facilitate the selection of test sites that are most suitable for a developer's device and that best meet their testing needs and objectives. It also provides inputs for the design of WEC test devices and planning WEC tests, including the planning of deployment and operations and maintenance. The first edition included three sites: the Pacific Marine Energy Center (PMEC) North Energy Test Site (NETS) offshore of Newport, Oregon, the Kaneohe Bay Naval Wave Energy Test Site (WETS) offshore of Oahu, HI, and a potential site offshore of Humboldt Bay, CA (Eureka, CA). The second edition was recently finished, which includes five additional sites: the Jennette's Pier Wave Energy Converter Test Site in North Carolina, the US Army Corps of Engineers (USACE) Field Research Facility (FRF), the PMEC Lake Washington site, the proposed PMEC South Energy Test Site (SETS), and the proposed CalWave Central Coast WEC Test Site. The operational sea states are included according to the IEC Technical Specification on wave energy resource assessment and characterization, with additional information on extreme sea states, weather windows, and representative spectra. The methodology and a summary of results will be discussed.

  18. The environmental interactions of tidal and wave energy generation devices

    OpenAIRE

    Frid, C.; Andonegi, E.; Depestele, J.; Judd, A.; Rihan, D.; Rogers, S.I.; Kenchington, E.

    2012-01-01

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other...

  19. Energy conversion of orbital motions in gravitational waves: Simulation and test of the Seaspoon wave energy converter

    International Nuclear Information System (INIS)

    Di Fresco, L.; Traverso, A.

    2014-01-01

    Highlights: • We investigate an innovative wave energy converter. • We study a robust technology derived from wind power sector. • We increased the performance of a drag type rotor exploiting the motion of ocean waves and a simple flat plate component. • We proved the working principle with a numerical model first and with experimental test in wave flume later. • We aim to obtain a robust large energy harvester able to operate in mild energy sea and with an extended operating range. - Abstract: The conversion of ocean wave power into sustainable electrical power represents a major opportunity to Nations endowed with such a kind of resource. At the present time the most of the technological innovations aiming at converting such resources are at early stage of development, with only a handful of devices close to be at the commercial demonstration stage. The Seaspoon device, thought as a large energy harvester, catches the kinetic energy of ocean waves with promising conversion efficiency, and robust technology, according to specific “wave-motion climate”. University of Genoa aims to develop a prototype to be deployed in medium average energy content seas (i.e. Mediterranean or Eastern Asia seas). This paper presents the first simulation and experimental results carried out on a reduced scale proof-of-concept model tested in the laboratory wave flume

  20. Transducer-Mounting Fixture

    Science.gov (United States)

    Spiegel, Kirk W.

    1990-01-01

    Transducer-mounting fixture holds transducer securely against stud. Projects only slightly beyond stud after installation. Flanged transducer fits into fixture when hinged halves open. When halves reclosed, fixture tightened onto threaded stud until stud makes contact with transducer. Knurled area on fixture aids in tightening fixture on stud.

  1. Model Predictive Control of a Wave Energy Converter

    DEFF Research Database (Denmark)

    Andersen, Palle; Pedersen, Tom Søndergård; Nielsen, Kirsten Mølgaard

    2015-01-01

    In this paper reactive control and Model Predictive Control (MPC) for a Wave Energy Converter (WEC) are compared. The analysis is based on a WEC from Wave Star A/S designed as a point absorber. The model predictive controller uses wave models based on the dominating sea states combined with a model...... connecting undisturbed wave sequences to sequences of torque. Losses in the conversion from mechanical to electrical power are taken into account in two ways. Conventional reactive controllers are tuned for each sea state with the assumption that the converter has the same efficiency back and forth. MPC...

  2. Toward Best Practices for Public Acceptability in Wave Energy

    DEFF Research Database (Denmark)

    Stefanovichu, M. A.; Chozas, Julia Fernandez

    2010-01-01

    At this initial stage of development, opinion toward wave energy is mainly positive. Interviews with developers, presentations about wave energy at local community meetings, and the literature show that there are four main types of issues developers need to address when discussing their projects ...... Ocean illustrate that despite similarities in the types of issues developers typically address at each site, the way of approaching the issues and the priorities given vary....

  3. Energy in one-dimensional linear waves in a string

    International Nuclear Information System (INIS)

    Burko, Lior M

    2010-01-01

    We consider the energy density and energy transfer in small amplitude, one-dimensional waves on a string and find that the common expressions used in textbooks for the introductory physics with calculus course give wrong results for some cases, including standing waves. We discuss the origin of the problem, and how it can be corrected in a way appropriate for the introductory calculus-based physics course. (letters and comments)

  4. Wave Energy and Actor-Network Theory: The Irish Case

    OpenAIRE

    Cunningham, William

    2013-01-01

    This paper examines the role of the wave energy sector in Ireland using theories from the field of Science and Technology Studies (STS). Theoretical divisions within the field of STS are examined, particularly the Sociology of Scientific Knowledge (SSK) and Actor-Network Theory (ANT). Any conflicts which these two theories present to each other are examined through the empirical findings of the Irish wave energy sector. In particular, ANT s rejection of macro and micro distinctions when analy...

  5. Experimental Modeling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Kofoed, Jens Peter; Friis-Madsen, Erik

    2011-01-01

    The Wave Dragon Wave Energy Converter is currently facing a precommercial phase. At this stage of development a reliable overtopping model is highly required, in order to predict the performance of the device at possible deployment locations. A model formulation derived for an overtopping device...... with general geometry has been used so far. The paper presents an updated formulation drawn through the tank testing of a scaled model the Wave Dragon. The sensitivity analysis of the main features influencing the overtopping flow led to an updated model formulation which can be specifically suited...... for the Wave Dragon....

  6. The Potential for Wave Energy in the North Sea

    DEFF Research Database (Denmark)

    Sørensen, H. C.; Chozas, Julia Fernandez

    2010-01-01

    The North Sea has not yet been regarded as prime area for wave energy development in Europe except in Denmark, Benelux and Germany. The reason is the relatively low intensity of waves (12-17kW/m) compared to the Atlantic with a wave climate of 24-48kW/m. Further on the design wave load is almost ...... is resulting in a prediction of a yearly production of 23TWh; the latter is estimating a yearly production of 77TWh. This equals to 6% of the electricity demand around the North Sea, where the annual electricity consumption is about 1,300TWh.......The North Sea has not yet been regarded as prime area for wave energy development in Europe except in Denmark, Benelux and Germany. The reason is the relatively low intensity of waves (12-17kW/m) compared to the Atlantic with a wave climate of 24-48kW/m. Further on the design wave load is almost...... as in the Atlantic and the distance to shore relatively long compared to sites with good wave climate like Ireland, Portugal, Spain and the west coast of UK. The increasing activities within offshore wind in the North Sea and the attempt to build a super grid connecting the wind sites with the major consumers around...

  7. Double system wave energy converter for the breaker zone

    International Nuclear Information System (INIS)

    Malavasi, Stefano; Negri; Marco

    2015-01-01

    In this paper a particular type of wave energy converter, namely EDS (Energy Double System) is presented. It is a two-body point absorber composed by a heaving float and a surging paddle, mounted on the same structure and aligned along the wave propagation direction. The system is designed for working in the breaker zone, where waves close to breaking can generate a considerable surging force on the paddle. A scale EDS model has been built and tested in the wave flume of the Hydraulics Laboratory of the 'Politecnico' of Milan. The power absorbed by the system, varying its configuration, position and wave, has been measured, and interesting efficiencies have been found.

  8. Stochastic control applied to the ISWEC Wave Energy System

    International Nuclear Information System (INIS)

    Bracco, Giovanni; Casassa, Maria; Giorcelli, Ermanno; Mattiazzo, Giuliana; Passione, Biagio; Raffero, Mattia; Vissio, Giacomo; Martini, Michele

    2015-01-01

    ISWEC (Inertial Sea Wave Energy Converter) is a floating marine device able to harvest sea waves energy by the interaction between the pitching motion of a floater and a spinning flywheel which can drive an electric PTO. In the ISWEC the hull dynamics is governed and controlled by the gyroscopic torque. The optimal control logic results in tuning the floater dynamics to the incoming waves in order to maximize the power transfer from the waves to the floater. In this paper the control problems of the ISWEC are stated and a control scheme based on the sub-optimal stochastic control logic is presented. The control scheme here presented has been tested using real wave records acquired at the deployment location in Pantelleria Island, which is one of the most energetic sites of the Mediterranean Sea.

  9. Catching the right wave: evaluating wave energy resources and potential compatibility with existing marine and coastal uses.

    Science.gov (United States)

    Kim, Choong-Ki; Toft, Jodie E; Papenfus, Michael; Verutes, Gregory; Guerry, Anne D; Ruckelshaus, Marry H; Arkema, Katie K; Guannel, Gregory; Wood, Spencer A; Bernhardt, Joanna R; Tallis, Heather; Plummer, Mark L; Halpern, Benjamin S; Pinsky, Malin L; Beck, Michael W; Chan, Francis; Chan, Kai M A; Levin, Phil S; Polasky, Stephen

    2012-01-01

    Many hope that ocean waves will be a source for clean, safe, reliable and affordable energy, yet wave energy conversion facilities may affect marine ecosystems through a variety of mechanisms, including competition with other human uses. We developed a decision-support tool to assist siting wave energy facilities, which allows the user to balance the need for profitability of the facilities with the need to minimize conflicts with other ocean uses. Our wave energy model quantifies harvestable wave energy and evaluates the net present value (NPV) of a wave energy facility based on a capital investment analysis. The model has a flexible framework and can be easily applied to wave energy projects at local, regional, and global scales. We applied the model and compatibility analysis on the west coast of Vancouver Island, British Columbia, Canada to provide information for ongoing marine spatial planning, including potential wave energy projects. In particular, we conducted a spatial overlap analysis with a variety of existing uses and ecological characteristics, and a quantitative compatibility analysis with commercial fisheries data. We found that wave power and harvestable wave energy gradually increase offshore as wave conditions intensify. However, areas with high economic potential for wave energy facilities were closer to cable landing points because of the cost of bringing energy ashore and thus in nearshore areas that support a number of different human uses. We show that the maximum combined economic benefit from wave energy and other uses is likely to be realized if wave energy facilities are sited in areas that maximize wave energy NPV and minimize conflict with existing ocean uses. Our tools will help decision-makers explore alternative locations for wave energy facilities by mapping expected wave energy NPV and helping to identify sites that provide maximal returns yet avoid spatial competition with existing ocean uses.

  10. Catching the Right Wave: Evaluating Wave Energy Resources and Potential Compatibility with Existing Marine and Coastal Uses

    Science.gov (United States)

    Kim, Choong-Ki; Toft, Jodie E.; Papenfus, Michael; Verutes, Gregory; Guerry, Anne D.; Ruckelshaus, Marry H.; Arkema, Katie K.; Guannel, Gregory; Wood, Spencer A.; Bernhardt, Joanna R.; Tallis, Heather; Plummer, Mark L.; Halpern, Benjamin S.; Pinsky, Malin L.; Beck, Michael W.; Chan, Francis; Chan, Kai M. A.; Levin, Phil S.; Polasky, Stephen

    2012-01-01

    Many hope that ocean waves will be a source for clean, safe, reliable and affordable energy, yet wave energy conversion facilities may affect marine ecosystems through a variety of mechanisms, including competition with other human uses. We developed a decision-support tool to assist siting wave energy facilities, which allows the user to balance the need for profitability of the facilities with the need to minimize conflicts with other ocean uses. Our wave energy model quantifies harvestable wave energy and evaluates the net present value (NPV) of a wave energy facility based on a capital investment analysis. The model has a flexible framework and can be easily applied to wave energy projects at local, regional, and global scales. We applied the model and compatibility analysis on the west coast of Vancouver Island, British Columbia, Canada to provide information for ongoing marine spatial planning, including potential wave energy projects. In particular, we conducted a spatial overlap analysis with a variety of existing uses and ecological characteristics, and a quantitative compatibility analysis with commercial fisheries data. We found that wave power and harvestable wave energy gradually increase offshore as wave conditions intensify. However, areas with high economic potential for wave energy facilities were closer to cable landing points because of the cost of bringing energy ashore and thus in nearshore areas that support a number of different human uses. We show that the maximum combined economic benefit from wave energy and other uses is likely to be realized if wave energy facilities are sited in areas that maximize wave energy NPV and minimize conflict with existing ocean uses. Our tools will help decision-makers explore alternative locations for wave energy facilities by mapping expected wave energy NPV and helping to identify sites that provide maximal returns yet avoid spatial competition with existing ocean uses. PMID:23144824

  11. Design and Control of Full Scale Wave Energy Simulator System

    DEFF Research Database (Denmark)

    Pedersen, Henrik C.; Hansen, Anders Hedegaard; Hansen, Rico Hjerm

    2012-01-01

    For wave energy to become feasible it is a requirement that the efficiency and reliability of the power take-off (PTO) systems are significantly improved. The cost of installing and testing PTO-systems at sea are however very high, and the focus of the current paper is therefore on the design...... of a full scale wave simulator for testing PTO-systems for point absorbers. The main challenge is here to design a system, which mimics the behavior of a wave when interacting with a given PTO-system. The paper includes a description of the developed system, located at Aalborg University......, and the considerations behind the design. Based on the description a model of the system is presented, which, along with a description of the wave theory applied, makes the foundation for the control strategy. The objective of the control strategy is to emulate not only the wave behavior, but also the dynamic wave...

  12. Experimental Testing of the Langlee Wave Energy Converter

    DEFF Research Database (Denmark)

    Lavelle, John; Kofoed, Jens Peter

    2011-01-01

    Aalborg University carried out wave tank testing a 1:20 scale model of Langlee, an oscillating wave-surge type of Wave Energy Converter (WEC). Langlee is designed to operate in deep water, with the hinged flaps attached to a, moored, semi-submerged reference frame. Langlee has a novel flap...... arrangement, with the flaps placed symmetrically opposing each other on a floating reference structure. This minimises the net force on the reference frame and increases the stability of the reference frame under optimal wave conditions. This paper presents the results and analysis from the wave tanks, which...... addressed the following: The Power Take Offs (PTOs) were simulated using a motor to resist the motion of the wings, according to the damping profile. Torque and velocity measurements were used to predict the wave- to mechanical-power conversion efficiency of the device. A number of wing types...

  13. Opportunities for shear energy scaling in bulk acoustic wave resonators.

    Science.gov (United States)

    Jose, Sumy; Hueting, Raymond J E

    2014-10-01

    An important energy loss contribution in bulk acoustic wave resonators is formed by so-called shear waves, which are transversal waves that propagate vertically through the devices with a horizontal motion. In this work, we report for the first time scaling of the shear-confined spots, i.e., spots containing a high concentration of shear wave displacement, controlled by the frame region width at the edge of the resonator. We also demonstrate a novel methodology to arrive at an optimum frame region width for spurious mode suppression and shear wave confinement. This methodology makes use of dispersion curves obtained from finite-element method (FEM) eigenfrequency simulations for arriving at an optimum frame region width. The frame region optimization is demonstrated for solidly mounted resonators employing several shear wave optimized reflector stacks. Finally, the FEM simulation results are compared with measurements for resonators with Ta2O5/ SiO2 stacks showing suppression of the spurious modes.

  14. Resonant wave energy harvester based on dielectric elastomer generator

    Science.gov (United States)

    Moretti, Giacomo; Pietro Rosati Papini, Gastone; Righi, Michele; Forehand, David; Ingram, David; Vertechy, Rocco; Fontana, Marco

    2018-03-01

    Dielectric elastomer generators (DEGs) are a class of capacitive solid-state devices that employ highly stretchable dielectrics and conductors to convert mechanical energy into high-voltage direct-current electricity. Their promising performance in terms of convertible energy and power density has been mostly proven in quasi-static experimental tests with prescribed deformation. However, the assessment of their ability in harvesting energy from a dynamic oscillating source of mechanical energy is crucial to demonstrate their effectiveness in practical applications. This paper reports a first demonstration of a DEG system that is able to convert the oscillating energy carried by water waves into electricity. A DEG prototype is built using a commercial polyacrylate film (VHB 4905 by 3M) and an experimental campaign is conducted in a wave-flume facility, i.e. an artificial basin that makes it possible to generate programmed small-scale waves at different frequencies and amplitudes. In resonant conditions, the designed system demonstrates the delivery of a maximum of 0.87 W of electrical power output and 0.64 J energy generated per cycle, with corresponding densities per unit mass of dielectric elastomer of 197 W kg-1 and 145 J kg-1. Additionally, a notable maximum fraction of 18% of the input wave energy is converted into electricity. The presented results provide a promising demonstration of the operation and effectiveness of ocean wave energy converters based on elastic capacitive generators.

  15. Numerical study on design for wave energy generation of a floater for energy absorption

    International Nuclear Information System (INIS)

    Li, Kui Ming; Parthasarathy, Nanjundan; Choi, Yoon Hwan; Lee, Yeon Won

    2012-01-01

    In order to design a wave energy generating system of a floater type, a 6 DOF motion technique was applied to the three Dimensional CFD analysis on a floating body and the behavior was interpreted according to the nature of the incoming waves. Waves in a tank model were generated using a single floater comparing with that of a Pelamis wave energy converter. In this paper, we focus on four variables, namely the wave height, angular velocity, diameter and length of the floater. The process was carried out in three stages and it was found that there are energy absorption differences in different parameters of wave height, length and the diameter of a floater during simulation, thus leading for the necessity of an optimal design for wave energy generation

  16. Ocean Wave Energy Regimes of the Circumpolar Coastal Zones

    Science.gov (United States)

    Atkinson, D. E.

    2004-12-01

    Ocean wave activity is a major enviromental forcing agent of the ice-rich sediments that comprise large sections of the arctic coastal margins. While it is instructive to possess information about the wind regimes in these regions, direct application to geomorphological and engineering needs requires knowledge of the resultant wave-energy regimes. Wave energy information has been calculated at the regional scale using adjusted reanalysis model windfield data. Calculations at this scale are not designed to account for local-scale coastline/bathymetric irregularities and variability. Results will be presented for the circumpolar zones specified by the Arctic Coastal Dynamics Project.

  17. Shock waves in water at low energy pulsed electric discharges

    International Nuclear Information System (INIS)

    Pinchuk, M E; Kolikov, V A; Rutberg, Ph G; Leks, A G; Dolinovskaya, R V; Snetov, V N; Stogov, A Yu

    2012-01-01

    Experimental results of shock wave formation and propagation in water at low energy pulsed electric discharges are presented. To study the hydrodynamic structure of the shock waves, the direct shadow optical diagnostic device with time resolution of 5 ns and spatial resolution of 0.1 mm was designed and developed. Synchronization of the diagnostic and electrodischarge units by the fast optocouplers was carried out. The dependences of shock wave velocities after breakdown of interelectrode gap for various energy inputs (at range of ≤1 J) into discharge were obtained. Based on the experimental results the recommendations for the adjustment parameters of the power supply and load were suggested.

  18. On gravitational wave energy in Einstein gravitational theory

    International Nuclear Information System (INIS)

    Folomeshkin, V.N.; Vlasov, A.A.

    1978-01-01

    By the example of precise wave solutions for the Einstein equations it is shown that a standard commonly adopted formulation of energy-momentum problem with pseudotensors provides us either with a zero or sign-variable values for the energy of gravitational waves. It is shown that if in the Einstein gravitational theory a strict transition to the limits of weak fields is realised then the theory gives us an unambiguous zero result for weak gravitational waves. The well-known non-zero result arises due to incorrect transition to weak field approximation in the Einstein gravitation theory

  19. A capacitive ultrasonic transducer based on parametric resonance.

    Science.gov (United States)

    Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F

    2017-07-24

    A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of f o . When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2f o with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at f o frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

  20. A capacitive ultrasonic transducer based on parametric resonance

    Science.gov (United States)

    Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F.

    2017-07-01

    A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of fo. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2fo with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at fo frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

  1. Measurements of Overtopping Flow Time Series on the Wave Dragon, Wave Energy Converter

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter

    2009-01-01

    A study of overtopping flow series on the Wave Dragon prototype, a low crested device designed to maximise flow, in a real sea, is presented. This study aims to fill the gap in the literature on time series of flow overtopping low crested structures. By comparing to a simulated flow the character......A study of overtopping flow series on the Wave Dragon prototype, a low crested device designed to maximise flow, in a real sea, is presented. This study aims to fill the gap in the literature on time series of flow overtopping low crested structures. By comparing to a simulated flow...... the characteristics of the overtopping flow are discussed and the simulation algorithm is tested. Measured data is shown from a storm build up in October 2006, from theWave Dragon prototype situated in an inland sea in Northern Denmark. This wave energy converter extracts energy from the waves, by funnelling them...

  2. Forecasting ocean wave energy: A Comparison of the ECMWF wave model with time series methods

    DEFF Research Database (Denmark)

    Reikard, Gordon; Pinson, Pierre; Bidlot, Jean

    2011-01-01

    Recently, the technology has been developed to make wave farms commercially viable. Since electricity is perishable, utilities will be interested in forecasting ocean wave energy. The horizons involved in short-term management of power grids range from as little as a few hours to as long as several...... days. In selecting a method, the forecaster has a choice between physics-based models and statistical techniques. A further idea is to combine both types of models. This paper analyzes the forecasting properties of a well-known physics-based model, the European Center for Medium-Range Weather Forecasts...... (ECMWF) Wave Model, and two statistical techniques, time-varying parameter regressions and neural networks. Thirteen data sets at locations in the Atlantic and Pacific Oceans and the Gulf of Mexico are tested. The quantities to be predicted are the significant wave height, the wave period, and the wave...

  3. Short term wave forecasting, using digital filters, for improved control of Wave Energy Converters

    DEFF Research Database (Denmark)

    Tedd, James; Frigaard, Peter

    2007-01-01

    This paper presents a Digital Filter method for real time prediction of waves incident upon a Wave Energy device. The method transforms waves measured at a point ahead of the device, to expected waves incident on the device. The relationship between these incident waves and power capture is derived...... experimentally. Results are shown form measurements taken on the Wave Dragon prototype device, a floating overtopping device situated in Northern Denmark. In this case the method is able to accurately predict the surface elevation at the device 11.2 seconds before the measurement is made. This is sufficient...... to allow advanced control systems to be developed using this knowledge to significantly improve power capture....

  4. Short term wave forecasting, using digital filters, for improved control of Wave Energy Converters

    Energy Technology Data Exchange (ETDEWEB)

    Tedd, J.; Frigaard, P. [Department of Civil Engineering, Aalborg University, Aalborg (Denmark)

    2007-07-01

    This paper presents a Digital Filter method for real time prediction of waves incident upon a Wave Energy device. The method transforms waves measured at a point ahead of the device, to expected waves incident on the device. The relationship between these incident waves and power capture is derived experimentally. Results are shown form measurements taken on the Wave Dragon prototype device, a floating overtopping device situated in Northern Denmark. In this case the method is able to accurately predict the surface elevation at the device 11.2 seconds before the measurement is made. This is sufficient to allow advanced control systems to be developed using this knowledge to significantly improve power capture.

  5. An array effect of wave energy farm buoys

    Directory of Open Access Journals (Sweden)

    Hyuck-Min Kweon

    2012-12-01

    Full Text Available An ocean buoy energy farm is considered for Green energy generation and delivery to small towns along the Korean coast. The present studypresents that the floating buoy-type energy farm appears to be sufficiently feasible fortrapping more energy compared to afixed cylinder duck array. It is also seen from the numerical resultsthat the resonated waves between spaced buoys are further trapped by floating buoy motion. Our numerical study is analyzed by a plane-wave approximation, in which evanescent mode effects are included in a modified mild-slope equation based on the scattering characteristics for a single buoy.

  6. Wave Tank Testing and Model Validation of an Autonomous Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Bret Bosma

    2015-08-01

    Full Text Available A key component in bringing ocean wave energy converters from concept to commercialization is the building and testing of scaled prototypes to provide model validation. A one quarter scale prototype of an autonomous two body heaving point absorber was modeled, built, and tested for this work. Wave tank testing results are compared with two hydrodynamic and system models—implemented in both ANSYS AQWA and MATLAB/Simulink—and show model validation over certain regions of operation. This work will serve as a guide for future developers of wave energy converter devices, providing insight in taking their design from concept to prototype stage.

  7. The selection of ultrasonic transducers for inspection of pipeline girth welds. Vol. 2. Evaluation of a unique creeping wave probe for examination of the cap region in pipeline girth welds

    Energy Technology Data Exchange (ETDEWEB)

    Fingerhut, M P; Glover, A G; Dorling, D V

    1988-10-01

    This work is part of a program aimed at developing an ultrasonic inspection design for the nondestructive evaluation of pipeline girth welds made by the mechanized gas metal arc (GMA) welding process for onshore and offshore pipeline construction. The feasibility of using creeping waves for examination of the cap region was investigated and, as a result, a specification for an experimental creeping wave transducer developed and a probe was designed to provide a beam oriented nearly perpendicular to expected defects in the cap region of the weld. The performance of this experimental creeping wave transducer was evaluated with respect to its ability to detect simulated and real weld defects in the cap region of mechanized GMA welds in 9.5 mm material. The probe was successful in detecting planar lack of sidewall fusion welding defects with a signal-to-noise ratio of greater than 12 dB, at depths of up to 4.2 mm from the plate surface. This indicates maximum pipe wall thicknesses of 10.9 mm may be satisfactorily examined before additional probes are required, assuming complete coverage in the root region is provided by other probes. The creeping wave probe not only performed well in the detection of real weld defects in the cap region for which it was intended, but also showed potential for detecting and discriminating some planar defects in the root region. 9 refs., 23 figs., 3 tabs.

  8. Physical measurements of breaking wave impact on a floating wave energy converter

    Science.gov (United States)

    Hann, Martyn R.; Greaves, Deborah M.; Raby, Alison

    2013-04-01

    Marine energy converter must both efficiently extract energy in small to moderate seas and also successfully survive storms and potential collisions. Extreme loads on devices are therefore an important consideration in their design process. X-MED is a SuperGen UKCMER project and is a collaboration between the Universities of Manchester, Edinburgh and Plymouth and the Scottish Association for Marine Sciences. Its objective is to extend the knowledge of extreme loads due to waves, currents, flotsam and mammal impacts. Plymouth Universities contribution to the X-MED project involves measuring the loading and response of a taut moored floating body due to steep and breaking wave impacts, in both long crested and directional sea states. These measurements are then to be reproduced in STAR-CCM+, a commercial volume of fluid CFD solver, so as to develop techniques to predict the wave loading on wave energy converters. The measurements presented here were conducted in Plymouth Universities newly opened COAST laboratories 35m long, 15.5m wide and 3m deep ocean basin. A 0.5m diameter taut moored hemispherical buoy was used to represent a floating wave energy device or support structure. The changes in the buoys 6 degree of freedom motion and mooring loads are presented due to focused breaking wave impacts, with the breaking point of the wave changed relative to the buoy.

  9. The environmental interactions of tidal and wave energy generation devices

    International Nuclear Information System (INIS)

    Frid, Chris; Andonegi, Eider; Depestele, Jochen; Judd, Adrian; Rihan, Dominic; Rogers, Stuart I.; Kenchington, Ellen

    2012-01-01

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other offshore energy developments is lacking. Tidal barrages have the potential to cause significant ecological impacts particularly on bird feeding areas when they are constructed at coastal estuaries or bays. Offshore tidal stream energy and wave energy collectors offer the scope for developments at varying scales. They also have the potential to alter habitats. A diversity of designs exist, including floating, mid-water column and seabed mounted devices, with a variety of moving-part configurations resulting in a unique complex of potential environmental effects for each device type, which are discussed to the extent possible. - Highlights: ► We review the environmental impacts of tidal barrages and fences, tidal stream farms and wave energy capture devices. ► Impacts on habitats, species and the water column, and effects of noise and electromagnetic fields are considered. ► Tidal barrages can cause significant impacts on bird feeding areas when constructed at coastal estuaries or bays. ► Wave energy collectors can alter water column and sea bed habitats locally and over large distances.

  10. Wave-current interactions at the FloWave Ocean Energy Research Facility

    Science.gov (United States)

    Noble, Donald; Davey, Thomas; Steynor, Jeffrey; Bruce, Tom; Smith, Helen; Kaklis, Panagiotis

    2015-04-01

    Physical scale model testing is an important part of the marine renewable energy development process, allowing the study of forces and device behaviour in a controlled environment prior to deployment at sea. FloWave is a new state-of-the-art ocean energy research facility, designed to provide large scale physical modelling services to the tidal and wave sector. It has the unique ability to provide complex multi-directional waves that can be combined with currents from any direction in the 25m diameter circular tank. The facility is optimised for waves around 2s period and 0.4m height, and is capable of generating currents upwards of 1.6m/s. This offers the ability to model metocean conditions suitable for most renewable energy devices at a typical scale of between 1:10 and 1:40. The test section is 2m deep, which can be classed as intermediate-depth for most waves of interest, thus the full dispersion equation must be solved as the asymptotic simplifications do not apply. The interaction between waves and currents has been studied in the tank. This has involved producing in the tank sets of regular waves, focussed wave groups, and random sea spectra including multi-directional sea states. These waves have been both inline-with and opposing the current, as well as investigating waves at arbitrary angles to the current. Changes in wave height and wavelength have been measured, and compared with theoretical results. Using theoretical wave-current interaction models, methods have been explored to "correct" the wave height in the central test area of the tank when combined with a steady current. This allows the wave height with current to be set equal to that without a current. Thus permitting, for example, direct comparison of device motion response between tests with and without current. Alternatively, this would also permit a specific wave height and current combination to be produced in the tank, reproducing recorded conditions at a particular site of interest. The

  11. On the dynamics of a novel ocean wave energy converter

    KAUST Repository

    Orazov, B.

    2010-11-01

    Buoy-type ocean wave energy converters are designed to exhibit resonant responses when subject to excitation by ocean waves. A novel excitation scheme is proposed which has the potential to improve the energy harvesting capabilities of these converters. The scheme uses the incident waves to modulate the mass of the device in a manner which amplifies its resonant response. To illustrate the novel excitation scheme, a simple one-degree of freedom model is developed for the wave energy converter. This model has the form of a switched linear system. After the stability regime of this system has been established, the model is then used to show that the excitation scheme improves the power harvesting capabilities by 2565 percent even when amplitude restrictions are present. It is also demonstrated that the sensitivity of the device\\'s power harvesting capabilities to changes in damping becomes much smaller when the novel excitation scheme is used. © 2010 Elsevier Ltd. All rights reserved.

  12. Design Specifications for the Hanstholm WEPTOS Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Tommy Larsen

    2012-04-01

    Full Text Available The WEPTOS wave energy converter (WEC is a novel device that combines an established and efficient wave energy absorbing mechanism with a smart structure, which can regulate the amount of incoming wave energy and reduce loads in extreme wave conditions. This adjustable A-shaped slack-moored and floating structure absorbs the energy of the waves through a multitude of rotors. The shape of the rotors is based on the renowned Salter’s Duck. On each leg, the rotors pivot around a common axle, through which the rotors transfer the absorbed power to a common power take off system. The study investigates the required capacity of the power take off (PTO system and the structural forces on a WEPTOS WEC prototype, intended for installation at Hanstholm (Denmark, based on large scale experimental tests using a highly realistic laboratory model of the complete device. The results hereof includes the rotational speed and transmitted torque (and hereby power to the PTO system using different PTO control strategies, the impact of fluctuations of the available mechanical power and the effect of limiting the PTO capacity on the annual energy production. Acquisition of structural forces includes mooring forces and structural bending moments in both production and extreme wave conditions, illustrating that the regulation of the angle in the A shape ensures that extreme forces on the structure can be kept in the same order of magnitude as in production conditions.

  13. A device for using wave energy

    Energy Technology Data Exchange (ETDEWEB)

    Prokopov, O.I.

    1984-01-01

    An offshore floating platform is used to support an electrical generator and two pontoons fastened on the edges. A horizontal tube located in a housing for two turbine blades rotating in opposite directions is connected to the generator by a shaft housed in a casing. The conical transmission connects the horizontal shafts of the turbine blades to the vertical shaft. When the waves pass near this platform, the pontoons rise up, the platform leans over to one side, and the turbine blades describe an arc, and cause the transmission and generator shaft to turn via the internal shafts. When the wave passes under the support, the raised pontoon drops and the other rises, and the platform leans over in the opposite direction; the blades then rotate in the opposite direction.

  14. Wave propagation of spectral energy content in a granular chain

    Directory of Open Access Journals (Sweden)

    Shrivastava Rohit Kumar

    2017-01-01

    Full Text Available A mechanical wave is propagation of vibration with transfer of energy and momentum. Understanding the spectral energy characteristics of a propagating wave through disordered granular media can assist in understanding the overall properties of wave propagation through inhomogeneous materials like soil. The study of these properties is aimed at modeling wave propagation for oil, mineral or gas exploration (seismic prospecting or non-destructive testing of the internal structure of solids. The focus is on the total energy content of a pulse propagating through an idealized one-dimensional discrete particle system like a mass disordered granular chain, which allows understanding the energy attenuation due to disorder since it isolates the longitudinal P-wave from shear or rotational modes. It is observed from the signal that stronger disorder leads to faster attenuation of the signal. An ordered granular chain exhibits ballistic propagation of energy whereas, a disordered granular chain exhibits more diffusive like propagation, which eventually becomes localized at long time periods. For obtaining mean-field macroscopic/continuum properties, ensemble averaging has been used, however, such an ensemble averaged spectral energy response does not resolve multiple scattering, leading to loss of information, indicating the need for a different framework for micro-macro averaging.

  15. The influence of waves on the tidal kinetic energy resource at a tidal stream energy site

    International Nuclear Information System (INIS)

    Guillou, Nicolas; Chapalain, Georges; Neill, Simon P.

    2016-01-01

    Highlights: • We model the influence of waves on tidal kinetic energy in the Fromveur Strait. • Numerical results are compared with field data of waves and currents. • The introduction of waves improve predictions of tidal stream power during storm. • Mean spring tidal stream potential is reduced by 12% during extreme wave conditions. • Potential is reduced by 7.8% with waves forces and 5.3% with enhanced friction. - Abstract: Successful deployment of tidal energy converters relies on access to accurate and high resolution numerical assessments of available tidal stream power. However, since suitable tidal stream sites are located in relatively shallow waters of the continental shelf where tidal currents are enhanced, tidal energy converters may experience effects of wind-generated surface-gravity waves. Waves may thus influence tidal currents, and associated kinetic energy, through two non-linear processes: the interaction of wave and current bottom boundary layers, and the generation of wave-induced currents. Here, we develop a three-dimensional tidal circulation model coupled with a phase-averaged wave model to quantify the impact of the waves on the tidal kinetic energy resource of the Fromveur Strait (western Brittany) - a region that has been identified with strong potential for tidal array development. Numerical results are compared with in situ observations of wave parameters (significant wave height, peak period and mean wave direction) and current amplitude and direction 10 m above the seabed (the assumed technology hub height for this region). The introduction of waves is found to improve predictions of tidal stream power at 10 m above the seabed at the measurement site in the Strait, reducing kinetic energy by up to 9% during storm conditions. Synoptic effects of wave radiation stresses and enhanced bottom friction are more specifically identified at the scale of the Strait. Waves contribute to a slight increase in the spatial gradient of

  16. Short-Term Wave Forecasting with AR models in Real-Time Optimal Control of Wave Energy Converters

    OpenAIRE

    Fusco, Francesco; Ringwood, John

    2010-01-01

    Time domain control of wave energy converters requires knowledge of future incident wave elevation in order to approach conditions for optimal energy extraction. Autoregressive models revealed to be a promising approach to the prediction of future values of the wave elevation only from its past history. Results on real wave observations from different ocean locations show that AR models allow to achieve very good predictions for more than one wave period in the future if ...

  17. User guide – COE Calculation Tool for Wave Energy Converters

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez; Kofoed, Jens Peter; Jensen, Niels Ejner Helstrup

    Aalborg University together with Energinet.dk and Julia F. Chozas Consulting Engineer, have released a freely available online spreadsheet to evaluate the Levelised Cost of Energy (LCOE) for wave energy projects. The open-access tool calculates the LCOE based on the power production of a Wave...... Energy Converter (WEC) at a particular location. Production data may derive from laboratory testing, numerical modelling or from sea trials. The tool has been developed as a transparent and simple model that evaluates WEC’s economic feasibility in a range of locations, while scaling WEC’s features...

  18. Research on a new wave energy absorption device

    Science.gov (United States)

    Lu, Zhongyue; Shang, Jianzhong; Luo, Zirong; Sun, Chongfei; Zhu, Yiming

    2018-01-01

    To reduce impact of global warming and the energy crisis problems caused by pollution of energy combustion, the research on renewable and clean energies becomes more and more important. This paper designed a new wave absorption device, and also gave an introduction on its mechanical structure. The flow tube model is analyzed, and presented the formulation of the proposed method. To verify the principle of wave absorbing device, an experiment was carried out in a laboratory environment, and the results of the experiment can be applied for optimizing the structure design of output power.

  19. Wave energy converter effects on wave propagation: A sensitivity study in Monterey Bay, CA

    Science.gov (United States)

    Chang, G.; Jones, C. A.; Roberts, J.; Magalen, J.; Ruehl, K.; Chartrand, C.

    2014-12-01

    The development of renewable offshore energy in the United States is growing rapidly and wave energy is one of the largest resources currently being evaluated. The deployment of wave energy converter (WEC) arrays required to harness this resource could feasibly number in the hundreds of individual devices. The WEC arrays have the potential to alter nearshore wave propagation and circulation patterns and ecosystem processes. As the industry progresses from pilot- to commercial-scale it is important to understand and quantify the effects of WECs on the natural nearshore processes that support a local, healthy ecosystem. To help accelerate the realization of commercial-scale wave power, predictive modeling tools have been developed and utilized to evaluate the likelihood of environmental impact. At present, direct measurements of the effects of different types of WEC arrays on nearshore wave propagation are not available; therefore wave model simulations provide the groundwork for investigations of the sensitivity of model results to prescribed WEC characteristics over a range of anticipated wave conditions. The present study incorporates a modified version of an industry standard wave modeling tool, SWAN (Simulating WAves Nearshore), to simulate wave propagation through a hypothetical WEC array deployment site on the California coast. The modified SWAN, referred to as SNL-SWAN, incorporates device-specific WEC power take-off characteristics to more accurately evaluate a WEC device's effects on wave propagation. The primary objectives were to investigate the effects of a range of WEC devices and device and array characteristics (e.g., device spacing, number of WECs in an array) on nearshore wave propagation using SNL-SWAN model simulations. Results showed that significant wave height was most sensitive to variations in WEC device type and size and the number of WEC devices in an array. Locations in the lee centerline of the arrays in each modeled scenario showed the

  20. Selection of Design Power of Wave Energy Converters Based on Wave Basin Experiments

    DEFF Research Database (Denmark)

    Martinelli, L.; Zanuttigh, B.; Kofoed, Jens Peter

    2011-01-01

    of the measured efficiency; description of the energy production by means of a function of the design capacity; application of a simple formula for cost benefit analysis. The analyses here proposed are based on the experimental results of 3D tests on two floating wave energy devices, named LEANCON and DEXA......Aim of this paper is to develop a method for selecting the optimal power generation capacity for which a wave energy converter (WEC) should be rated. This method is suitable for the earliest stages of development, when several studies are missing, including design of the Power Take Off (PTO) system...

  1. Experimental Study of the WEPTOS Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Marchalot, Tanguy

    This report presents the results of an experimental study on the power conversion capabilities and structural loads of the WEPTOS wave energy converter. The investigation focuses mainly at identifying the performance of the WEPTOS prototype in a wide range of production wave states...... and at the mooring forces and structural bending moments in extreme wave conditions, in order to estimate the performance and structural loads of larger WEPTOS machines being located at various offshore locations of interest. The following aspects were the main subjects of investigation: Performance of the prototype...... under a constant and linear PTO loading, the opening angle of the device, the effect of alterations to the wave conditions, and mooring forces and structural bending moments in production and extreme wave states. During the study, a highly realistic scale model was supplied by the client, WEPTOS, which...

  2. A Detailed Assessment of the Wave Energy Resource at the Atlantic Marine Energy Test Site

    Directory of Open Access Journals (Sweden)

    Reduan Atan

    2016-11-01

    Full Text Available Wave characteristic assessments of wave energy test sites provide a greater understanding of prevailing wave conditions and are therefore extremely important to both wave energy test site operators and clients as they can inform wave energy converter design, optimisation, deployment, operation and maintenance. This research presents an assessment of the wave resource at the Atlantic Marine Energy Test Site (AMETS on the west coast of Ireland based on 12-years of modelled data from January 2004 to December 2015. The primary aim is to provide an assessment of annual and seasonal wave characteristics and resource variability at the two deployment berths which comprise the site. A nested model has been developed using Simulating WAves Nearshore (SWAN to replicate wave propagations from regional to local scale with a 0.05° resolution model covering the northeast Atlantic and a 0.0027° resolution model covering AMETS. The coarse and fine models have been extensively validated against available measured data within Irish waters. 12-year model outputs from the high resolution model were analysed to determine mean and maximum conditions and operational, high and extreme event conditions for significant wave height, energy period and power. Annual and seasonal analyses are presented. The 12-year annual mean P were 68 kW/m at Berth A (BA and 57 kW/m at Berth B (BB. The resource shows strong seasonal and annual variations and the winter mean power levels were found to be strongly correlated with the North Atlantic Oscillation (NAO.

  3. Local energy decay for linear wave equations with variable coefficients

    Science.gov (United States)

    Ikehata, Ryo

    2005-06-01

    A uniform local energy decay result is derived to the linear wave equation with spatial variable coefficients. We deal with this equation in an exterior domain with a star-shaped complement. Our advantage is that we do not assume any compactness of the support on the initial data, and its proof is quite simple. This generalizes a previous famous result due to Morawetz [The decay of solutions of the exterior initial-boundary value problem for the wave equation, Comm. Pure Appl. Math. 14 (1961) 561-568]. In order to prove local energy decay, we mainly apply two types of ideas due to Ikehata-Matsuyama [L2-behaviour of solutions to the linear heat and wave equations in exterior domains, Sci. Math. Japon. 55 (2002) 33-42] and Todorova-Yordanov [Critical exponent for a nonlinear wave equation with damping, J. Differential Equations 174 (2001) 464-489].

  4. Buoy and Generator Interaction with Ocean Waves: Studies of a Wave Energy Conversion System

    Energy Technology Data Exchange (ETDEWEB)

    Lindroth, Simon

    2011-07-01

    On March 13th, 2006, the Div. of Electricity at Uppsala Univ. deployed its first wave energy converter, L1, in the ocean southwest of Lysekil. L1 consisted of a buoy at the surface, connected through a line to a linear generator on the seabed. Since the deployment, continuous investigations of how L1 works in the waves have been conducted, and several additional wave energy converters have been deployed. This thesis is based on ten publications, which focus on different aspects of the interaction between wave, buoy, and generator. In order to evaluate different measurement systems, the motion of the buoy was measured optically and using accelerometers, and compared to measurements of the motion of the movable part of the generator - the translator. These measurements were found to correlate well. Simulations of buoy and translator motion were found to match the measured values. The variation of performance of L1 with changing water levels, wave heights, and spectral shapes was also investigated. Performance is here defined as the ratio of absorbed power to incoming power. It was found that the performance decreases for large wave heights. This is in accordance with the theoretical predictions, since the area for which the stator and the translator overlap decreases for large translator motions. Shifting water levels were predicted to have the same effect, but this could not be seen as clearly. The width of the wave energy spectrum has been proposed by some as a factor that also affects the performance of a wave energy converter, for a set wave height and period. Therefore the relation between performance and several different parameters for spectral width was investigated. It was found that some of the parameters were in fact correlated to performance, but that the correlation was not very strong. As a background on ocean measurements in wave energy, a thorough literature review was conducted. It turns out that the Lysekil project is one of quite few projects that

  5. Are Wave and Tidal Energy Plants New Green Technologies?

    Science.gov (United States)

    Douziech, Mélanie; Hellweg, Stefanie; Verones, Francesca

    2016-07-19

    Wave and tidal energy plants are upcoming, potentially green technologies. This study aims at quantifying their various potential environmental impacts. Three tidal stream devices, one tidal range plant and one wave energy harnessing device are analyzed over their entire life cycles, using the ReCiPe 2008 methodology at midpoint level. The impacts of the tidal range plant were on average 1.6 times higher than the ones of hydro-power plants (without considering natural land transformation). A similar ratio was found when comparing the results of the three tidal stream devices to offshore wind power plants (without considering water depletion). The wave energy harnessing device had on average 3.5 times higher impacts than offshore wind power. On the contrary, the considered plants have on average 8 (wave energy) to 20 (tidal stream), or even 115 times (tidal range) lower impact than electricity generated from coal power. Further, testing the sensitivity of the results highlighted the advantage of long lifetimes and small material requirements. Overall, this study supports the potential of wave and tidal energy plants as alternative green technologies. However, potential unknown effects, such as the impact of turbulence or noise on marine ecosystems, should be further explored in future research.

  6. Low energy consumption vortex wave flow membrane bioreactor.

    Science.gov (United States)

    Wang, Zhiqiang; Dong, Weilong; Hu, Xiaohong; Sun, Tianyu; Wang, Tao; Sun, Youshan

    2017-11-01

    In order to reduce the energy consumption and membrane fouling of the conventional membrane bioreactor (MBR), a kind of low energy consumption vortex wave flow MBR was exploited based on the combination of biofilm process and membrane filtration process, as well as the vortex wave flow technique. The experimental results showed that the vortex wave flow state in the membrane module could be formed when the Reynolds number (Re) of liquid was adjusted between 450 and 1,050, and the membrane flux declined more slowly in the vortex wave flow state than those in the laminar flow state and turbulent flow state. The MBR system was used to treat domestic wastewater under the condition of vortex wave flow state for 30 days. The results showed that the removal efficiency for CODcr and NH 3 -N was 82% and 98% respectively, and the permeate quality met the requirement of 'Water quality standard for urban miscellaneous water consumption (GB/T 18920-2002)'. Analysis of the energy consumption of the MBR showed that the average energy consumption was 1.90 ± 0.55 kWh/m 3 (permeate), which was only two thirds of conventional MBR energy consumption.

  7. Optimization of bottom-hinged flap-type wave energy converter for a specific wave rose

    Science.gov (United States)

    Behzad, Hamed; Panahi, Roozbeh

    2017-06-01

    In this paper, we conducted a numerical analysis on the bottom-hinged flap-type Wave Energy Convertor (WEC). The basic model, implemented through the study using ANSYS-AQWA, has been validated by a three-dimensional physical model of a pitching vertical cylinder. Then, a systematic parametric assessment has been performed on stiffness, damping, and WEC direction against an incoming wave rose, resulting in an optimized flap-type WEC for a specific spot in the Persian Gulf. Here, stiffness is tuned to have a near-resonance condition considering the wave rose, while damping is modified to capture the highest energy for each device direction. Moreover, such sets of specifications have been checked at different directions to present the best combination of stiffness, damping, and device heading. It has been shown that for a real condition, including different wave heights, periods, and directions, it is very important to implement the methodology introduced here to guarantee device performance.

  8. Solar energy converter using surface plasma waves

    Science.gov (United States)

    Anderson, L. M. (Inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  9. Wave Energy, Lever Operated Pivoting Float LOPF Study

    DEFF Research Database (Denmark)

    Margheritini, Lucia

    The fully instrumented Resen Waves Lever Operated Pivoting Float LOPF wave energy buoy model has gone through the first stage of testing in regular waves in scale 1:25 of the North Sea wave conditions, in the 3D deep wave basin at the Hydraulic and Coastal Engineering Laboratory of Aalborg...... University in Denmark. The model size was 60cm W x 90cm L x 21cm H. The 60 cm width pointed towards the wave front. The LOPF buoy is characterized by a simple mechanical design with few moving parts and direct electrical output and it is taut moored to the sea bed, so all forces are referenced to the seabed...... for maximum energy output in regular as well as irregular waves. During storms the buoy pivots and streamlines itself to minimize loads on the mooring line. A conservative estimate shows that a full scale system for North Sea conditions has a float size width of 15 m that will, with 60% generator efficiency...

  10. The SSG Wave Energy Converter: Performance, Status and Recent Developments

    Directory of Open Access Journals (Sweden)

    Mariano Buccino

    2012-01-01

    Full Text Available The Sea-wave Slot-cone Generator (SSG is a Wave Energy Converter based on the wave overtopping principle; it employs several reservoirs placed on top of each other, in which the energy of incoming waves is stored as potential energy. Then, the captured water runs through turbines for electricity production. The system works under a wide spectrum of different wave conditions, giving a high overall efficiency. It can be suitable for shoreline and breakwater applications and presents particular advantages, such as sharing structure costs, availability of grid connection and recirculation of water inside the harbor, as the outlet of the turbines is on the rear part of the system. Recently, plans for the SSG pilot installations are in progress at the Svaaheia site (Norway, the port of Hanstholm (Denmark and the port of Garibaldi (Oregon, USA. In the last-mentioned two projects, the Sea-wave Slot-cone Generator technology is integrated into the outer harbor breakwater and jetty reconstruction projects. In the last years extensive studies have been performed on the hydraulic and the structural response of this converter, with the aim of optimizing the design process. The investigations have been conducted by physical model tests and numerical simulations and many results have been published on both conference proceedings and journals. The main scope of this paper is reviewing the most significant findings, to provide the reader with an organic overview on the present status of knowledge.

  11. Control of runaway electron energy using externally injected whistler waves

    Science.gov (United States)

    Guo, Zehua; McDevitt, Christopher J.; Tang, Xian-Zhu

    2018-03-01

    One way of mitigating runaway damage of the plasma-facing components in a tokamak fusion reactor is by limiting the runaway electron energy under a few MeV, while not necessarily reducing the runaway current appreciably. Here, we describe a physics mechanism by which such momentum space engineering of the runaway distribution can be facilitated by externally injected high-frequency electromagnetic waves such as whistler waves. The drastic impact that wave-induced scattering can have on the runaway energy distribution is fundamentally the result of its ability to control the runaway vortex in the momentum space. The runaway vortex, which is a local circulation of runaways in momentum space, is the outcome of the competition between Coulomb collisions, synchrotron radiation damping, and runaway acceleration by the parallel electric field. By introducing a wave that resonantly interacts with runaways in a particular range of energies which is mildly relativistic, the enhanced scattering would reshape the vortex by cutting off the part that is highly relativistic. The efficiency of resonant scattering accentuates the requirement that the wave amplitude can be small so the power requirement from external wave injection is practical for the mitigation scheme.

  12. Designing and Testing Composite Energy Storage Systems for Regulating the Outputs of Linear Wave Energy Converters

    Directory of Open Access Journals (Sweden)

    Zanxiang Nie

    2017-01-01

    Full Text Available Linear wave energy converters generate intrinsically intermittent power with variable frequency and amplitude. A composite energy storage system consisting of batteries and super capacitors has been developed and controlled by buck-boost converters. The purpose of the composite energy storage system is to handle the fluctuations and intermittent characteristics of the renewable source, and hence provide a steady output power. Linear wave energy converters working in conjunction with a system composed of various energy storage devices, is considered as a microsystem, which can function in a stand-alone or a grid connected mode. Simulation results have shown that by applying a boost H-bridge and a composite energy storage system more power could be extracted from linear wave energy converters. Simulation results have shown that the super capacitors charge and discharge often to handle the frequent power fluctuations, and the batteries charge and discharge slowly for handling the intermittent power of wave energy converters. Hardware systems have been constructed to control the linear wave energy converter and the composite energy storage system. The performance of the composite energy storage system has been verified in experiments by using electronics-based wave energy emulators.

  13. R&D Towards Commercialization of Sea Wave Slot Cone Generator (SSG) Overtopping Wave Energy Converter

    DEFF Research Database (Denmark)

    Margheritini, Lucia

    between ventures and private investors, and to promote an accelerated shift from a technology to a market focus. This Thesis is presented as a collection of works published by the author on her research on the Sea wave Slot cone Generator wave energy converter. These include 1 accepted and 2 submitted......Global energy needs are likely to continue to grow steadily for the next two and a half decades (International Energy Agency, 2006). If governments continue with current policies the world’s energy needs would be more than 50% higher in 2030 than today. Over 60% of that increase would be covered...... in the form of oil and natural gas. Climate destabilizing carbon-dioxide emissions would continue to rise, calling into question the long-term sustainability of the global energy system. More vigorous government policies in consuming countries are steering the world onto an energy path oriented to reduce...

  14. Comparative analysis of winch-based wave energy converters

    OpenAIRE

    Nachev, Aleksandar

    2017-01-01

    Renewable energy sources are probably the future of the mankind. The main points advocating wave energy in particular include its huge potential, low environmental impact and availability around the globe. In order to harvest that energy, however, engineers have to overcome, among others, the corrosive sea environment and the unpredictable storms as well as secure funding for research and development. A lot of effort has been put into building and testing WECs after the oil crisis in the 1970...

  15. Microhydraulic transducer technology for actuation and power generation

    Science.gov (United States)

    Hagood, Nesbitt W.; Roberts, David C.; Saggere, Laxminarayana; Breuer, Kenneth S.; Chen, Kuo-Shen; Carretero, Jorge A.; Li, Hanqing; Mlcak, Richard; Pulitzer, Seward W.; Schmidt, Martin A.; Spearing, S. Mark; Su, Yu-Hsuan

    2000-06-01

    The paper introduces a novel transducer technology, called the solid-state micro-hydraulic transducer, currently under development at MIT. The new technology is enabled through integration of micromachining technology, piezoelectrics, and microhydraulic concepts. These micro-hydraulic transducers are capable of bi-directional electromechanical energy conversion, i.e., they can operate as both an actuator that supplies high mechanical force in response to electrical input and an energy generator that transduces electrical energy from mechanical energy in the environment. These transducers are capable of transducing energy at very high specific power output in the order of 1 kW/kg, and thus, they have the potential to enable many novel applications. The concept, the design, and the potential applications of the transducers are presented. Present efforts towards the development of these transducers, and the challenges involved therein, are also discussed.

  16. Coalgebraising subsequential transducers

    NARCIS (Netherlands)

    H.H. Hansen (Helle); J. Adamek; C.A. Kupke (Clemens)

    2008-01-01

    htmlabstractSubsequential transducers generalise both classic deterministic automata and Mealy/Moore type state machines by combining (input) language recognition with transduction. In this paper we show that normalisation and taking differentials of subsequential transducers and their underlying

  17. Coalgebraising Subsequential Transducers

    NARCIS (Netherlands)

    Hansen, H.H.

    2008-01-01

    Subsequential transducers generalise both classic deterministic automata and Mealy/Moore type state machines by combining (input) language recognition with transduction. In this paper we show that normalisation and taking differentials of subsequential transducers and their underlying structures can

  18. Maximum gravitational-wave energy emissible in magnetar flares

    Science.gov (United States)

    Corsi, Alessandra; Owen, Benjamin J.

    2011-05-01

    Recent searches of gravitational-wave data raise the question of what maximum gravitational-wave energies could be emitted during gamma-ray flares of highly magnetized neutron stars (magnetars). The highest energies (˜1049erg) predicted so far come from a model [K. Ioka, Mon. Not. R. Astron. Soc.MNRAA40035-8711 327, 639 (2001), http://adsabs.harvard.edu/abs/2001MNRAS.327..639I] in which the internal magnetic field of a magnetar experiences a global reconfiguration, changing the hydromagnetic equilibrium structure of the star and tapping the gravitational potential energy without changing the magnetic potential energy. The largest energies in this model assume very special conditions, including a large change in moment of inertia (which was observed in at most one flare), a very high internal magnetic field, and a very soft equation of state. Here we show that energies of 1048-1049erg are possible under more generic conditions by tapping the magnetic energy, and we note that similar energies may also be available through cracking of exotic solid cores. Current observational limits on gravitational waves from magnetar fundamental modes are just reaching these energies and will beat them in the era of advanced interferometers.

  19. Maximum gravitational-wave energy emissible in magnetar flares

    International Nuclear Information System (INIS)

    Corsi, Alessandra; Owen, Benjamin J.

    2011-01-01

    Recent searches of gravitational-wave data raise the question of what maximum gravitational-wave energies could be emitted during gamma-ray flares of highly magnetized neutron stars (magnetars). The highest energies (∼10 49 erg) predicted so far come from a model [K. Ioka, Mon. Not. R. Astron. Soc. 327, 639 (2001), http://adsabs.harvard.edu/abs/2001MNRAS.327..639I] in which the internal magnetic field of a magnetar experiences a global reconfiguration, changing the hydromagnetic equilibrium structure of the star and tapping the gravitational potential energy without changing the magnetic potential energy. The largest energies in this model assume very special conditions, including a large change in moment of inertia (which was observed in at most one flare), a very high internal magnetic field, and a very soft equation of state. Here we show that energies of 10 48 -10 49 erg are possible under more generic conditions by tapping the magnetic energy, and we note that similar energies may also be available through cracking of exotic solid cores. Current observational limits on gravitational waves from magnetar fundamental modes are just reaching these energies and will beat them in the era of advanced interferometers.

  20. On the asymptotic evolution of finite energy Airy wave functions.

    Science.gov (United States)

    Chamorro-Posada, P; Sánchez-Curto, J; Aceves, A B; McDonald, G S

    2015-06-15

    In general, there is an inverse relation between the degree of localization of a wave function of a certain class and its transform representation dictated by the scaling property of the Fourier transform. We report that in the case of finite energy Airy wave packets a simultaneous increase in their localization in the direct and transform domains can be obtained as the apodization parameter is varied. One consequence of this is that the far-field diffraction rate of a finite energy Airy beam decreases as the beam localization at the launch plane increases. We analyze the asymptotic properties of finite energy Airy wave functions using the stationary phase method. We obtain one dominant contribution to the long-term evolution that admits a Gaussian-like approximation, which displays the expected reduction of its broadening rate as the input localization is increased.

  1. Hydrodynamic Investigation of a Concentric Cylindrical OWC Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Yu Zhou

    2018-04-01

    Full Text Available A fixed, concentric, cylindrical oscillating water column (OWC wave energy converter (WEC is proposed for shallow offshore sites. Compared with the existing shoreline OWC device, this wave energy device is not restricted by the wave directions and coastline geography conditions. Analytical solutions are derived based on the linear potential-flow theory and eigen-function expansion technique to investigate hydrodynamic properties of the device. Three typical free-surface oscillation modes in the chamber are discussed, of which the piston-type mode makes the main contribution to the energy conversion. The effects of the geometrical parameters on the hydrodynamic properties are further investigated. The resonance frequency of the chamber, the power extraction efficiency, and the effective frequency bandwidth of the device is discussed, amongst other topics. It is found that the proposed OWC-WEC device with a lower draft and wider chamber breadth has better power extraction ability.

  2. Energy flow characteristics of vector X-Waves

    KAUST Repository

    Salem, Mohamed; Bagci, Hakan

    2011-01-01

    The vector form of X-Waves is obtained as a superposition of transverse electric and transverse magnetic polarized field components. It is shown that the signs of all components of the Poynting vector can be locally changed using carefully chosen complex amplitudes of the transverse electric and transverse magnetic polarization components. Negative energy flux density in the longitudinal direction can be observed in a bounded region around the centroid; in this region the local behavior of the wave field is similar to that of wave field with negative energy flow. This peculiar energy flux phenomenon is of essential importance for electromagnetic and optical traps and tweezers, where the location and momenta of microand nanoparticles are manipulated by changing the Poynting vector, and in detection of invisibility cloaks. © 2011 Optical Society of America.

  3. Driving electrostatic transducers

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Knott, Arnold; Andersen, Michael A. E.

    2013-01-01

    Electrostatic transducers represent a very interesting alternative to the traditional inefficient electrodynamic transducers. In order to establish the full potential of these transducers, power amplifiers which fulfill the strict requirements imposed by such loads (high impedance, frequency...... depended, nonlinear and high bias voltage for linearization) must be developed. This paper analyzes power stages and bias configurations suitable for driving an electrostatic transducer. Measurement results of a 300 V prototype amplifier are shown. Measuring THD across a high impedance source is discussed...

  4. Silicone-Based Triboelectric Nanogenerator for Water Wave Energy Harvesting.

    Science.gov (United States)

    Xiao, Tian Xiao; Jiang, Tao; Zhu, Jian Xiong; Liang, Xi; Xu, Liang; Shao, Jia Jia; Zhang, Chun Lei; Wang, Jie; Wang, Zhong Lin

    2018-01-31

    Triboelectric nanogenerator (TENG) has been proven to be efficient for harvesting water wave energy, which is one of the most promising renewable energy sources. In this work, a TENG with a silicone rubber/carbon black composite electrode was designed for converting the water wave energy into electricity. The silicone-based electrode with a soft texture provides a better contact with the dielectric film. Furthermore, a spring structure is introduced to transform low-frequency water wave motions into high-frequency vibrations. They together improve the output performance and efficiency of TENG. The output performances of TENGs are further enhanced by optimizing the triboelectric material pair and tribo-surface area. A spring-assisted TENG device with the segmented silicone rubber-based electrode structure was sealed into a waterproof box, which delivers a maximum power density of 2.40 W m -3 , as triggered by the water waves. The present work provides a new strategy for fabricating high-performance TENG devices by coupling flexible electrodes and spring structure for harvesting water wave energy.

  5. Measurements of radiated elastic wave energy from dynamic tensile cracks

    Science.gov (United States)

    Boler, Frances M.

    1990-01-01

    The role of fracture-velocity, microstructure, and fracture-energy barriers in elastic wave radiation during a dynamic fracture was investigated in experiments in which dynamic tensile cracks of two fracture cofigurations of double cantilever beam geometry were propagating in glass samples. The first, referred to as primary fracture, consisted of fractures of intact glass specimens; the second configuration, referred to as secondary fracture, consisted of a refracture of primary fracture specimens which were rebonded with an intermittent pattern of adhesive to produce variations in fracture surface energy along the crack path. For primary fracture cases, measurable elastic waves were generated in 31 percent of the 16 fracture events observed; the condition for radiation of measurable waves appears to be a local abrupt change in the fracture path direction, such as occurs when the fracture intersects a surface flaw. For secondary fractures, 100 percent of events showed measurable elastic waves; in these fractures, the ratio of radiated elastic wave energy in the measured component to fracture surface energy was 10 times greater than for primary fracture.

  6. Advanced computational simulations of water waves interacting with wave energy converters

    Science.gov (United States)

    Pathak, Ashish; Freniere, Cole; Raessi, Mehdi

    2017-03-01

    Wave energy converter (WEC) devices harness the renewable ocean wave energy and convert it into useful forms of energy, e.g. mechanical or electrical. This paper presents an advanced 3D computational framework to study the interaction between water waves and WEC devices. The computational tool solves the full Navier-Stokes equations and considers all important effects impacting the device performance. To enable large-scale simulations in fast turnaround times, the computational solver was developed in an MPI parallel framework. A fast multigrid preconditioned solver is introduced to solve the computationally expensive pressure Poisson equation. The computational solver was applied to two surface-piercing WEC geometries: bottom-hinged cylinder and flap. Their numerically simulated response was validated against experimental data. Additional simulations were conducted to investigate the applicability of Froude scaling in predicting full-scale WEC response from the model experiments.

  7. Wave Runup on a Frozen Beach Under High Energy Conditions

    Science.gov (United States)

    Didier, D.; Bernatchez, P.; Dumont, D.; Corriveau, M.

    2017-12-01

    High and mid-latitude beaches have typical morphological characteristics influenced by nearshore processes prevailing under ice conditions during cold season. Nearshore ice complexes (NIC) offer a natural coastal protection by covering beach sediments, while offshore ice-infested waters dissipate incoming waves. Climate change contributes to sea ice shrinking therefore reducing its protection against erosion and flooding. In the Estuary and Gulf of the St. Lawrence (ESL, GSL) (eastern Canada), sea ice cover undergoes an overall shrinking and simulated future projections tend toward a negligible effect on wave climate by 2100. Quantifying the effect of nearshore dynamics on frozen beaches is therefore imperative for coastal management as more wave energy at the coast is expected in the future. To measure the effect of a frozen beach on wave runup elevations, this study employs a continuous video recording of the swash motion at 4Hz. Video-derived wave runup statistics have been extracted during a tidal cycle on a frozen beach, using the Pointe-Lebel beach (ESL) as a test case. Timestack analysis was combined with offshore water levels and wave measurements. A comparison of runup under icy conditions (Dec. 30 2016) with a runup distribution during summer was made under similar high energy wave conditions. Results indicate high runup excursions potentially caused by lowered sediment permeability due to high pore-ice saturation in the swash zone, accentuating the overwash of the eroding coastline and thus the risk of flooding. With projected reduction in coastal sea ice cover and thus higher wave energy, this study suggests that episodes of degradation and weakening could influence the coastal flood risk in mid- and high-latitude cold environments.

  8. Wave energy extraction using decommisioned ships

    DEFF Research Database (Denmark)

    Mansour, A.E.; Pedersen, Preben Terndrup; Paik, J.K.

    2013-01-01

    is to tune the ship to have rigid body resonance, or close to it, and resist that motion to absorb power. A hydraulic ramp connected to an accumulator feeding a hydraulic motor that generates power is one possibility. Several other energy extraction mechanisms such as turbines connected to oscillating water...

  9. Hydraulic Evaluation of the LEANCON Wave Energy Converter

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter

    This report is a product of the co-operation agreement between Aalborg University and LEANCON (by Kurt Due Rasmussen) on the evaluation and development of the LEANCON wave energy converter (WEC). The work reported here has focused on evaluation of the power production of the device, based...... on laboratory testing of a model of the WEC provided by LEANCON. LEANCON, represented by Kurt Due Rasmussen, has been heavily involved in the testing of the device, including the instrumentation, model setup and execution of the tests in the laboratory, all under the supervision of the personnel of the Wave...... Energy Research Group at Department of Civil Engineering, Aalborg University....

  10. Reliability-Based Structural Optimization of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten; Sørensen, John Dalsgaard

    2014-01-01

    More and more wave energy converter (WEC) concepts are reaching prototype level. Once the prototype level is reached, the next step in order to further decrease the levelized cost of energy (LCOE) is optimizing the overall system with a focus on structural and maintenance (inspection) costs......, as well as on the harvested power from the waves. The target of a fully-developed WEC technology is not maximizing its power output, but minimizing the resulting LCOE. This paper presents a methodology to optimize the structural design of WECs based on a reliability-based optimization problem...

  11. A parametric costing model for wave energy technology

    International Nuclear Information System (INIS)

    1992-01-01

    This document describes the philosophy and technical approach to a parametric cost model for offshore wave energy systems. Consideration is given both to existing known devices and other devices yet to be conceptualised. The report is complementary to a spreadsheet based cost estimating model. The latter permits users to derive capital cost estimates using either inherent default data or user provided data, if a particular scheme provides sufficient design definition for more accurate estimation. The model relies on design default data obtained from wave energy device designs and a set of specifically collected cost data. (author)

  12. The environmental interactions of tidal and wave energy generation devices

    Energy Technology Data Exchange (ETDEWEB)

    Frid, Chris, E-mail: c.l.j.frid@liv.ac.uk [School of Environmental Sciences, University of Liverpool, Crown Street, Liverpool, L69 7ZB (United Kingdom); Andonegi, Eider, E-mail: eandonegi@azti.es [AZTI-Tecnalia, Txatxarramendi ugartea, z/g E-48395 Sukarrieta (Bizkaia) (Spain); Depestele, Jochen, E-mail: jochen.depestele@ilvo.vlaanderen.be [Institute for Agricultural and Fisheries Research, Ankerstraat 1, B-8400 Oostende (Belgium); Judd, Adrian, E-mail: Adrian.Judd@cefas.co.uk [Centre for Environment, Fisheries and Aquaculture Science , Lowestoft Laboratory, Pakefield Road, Lowestoft NR33 0HT United Kingdom (United Kingdom); Rihan, Dominic, E-mail: Dominic.RIHAN@ec.europa.eu [Irish Sea Fisheries Board, P.O. Box 12 Dun Laoghaire, Co. Dublin (Ireland); Rogers, Stuart I., E-mail: stuart.rogers@cefas.co.uk [Centre for Environment, Fisheries and Aquaculture Science , Lowestoft Laboratory, Pakefield Road, Lowestoft NR33 0HT United Kingdom (United Kingdom); Kenchington, Ellen, E-mail: Ellen.Kenchington@dfo-mpo.gc.ca [Fisheries and Oceans Canada, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth Canada, NS B2Y 4A2 (Canada)

    2012-01-15

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other offshore energy developments is lacking. Tidal barrages have the potential to cause significant ecological impacts particularly on bird feeding areas when they are constructed at coastal estuaries or bays. Offshore tidal stream energy and wave energy collectors offer the scope for developments at varying scales. They also have the potential to alter habitats. A diversity of designs exist, including floating, mid-water column and seabed mounted devices, with a variety of moving-part configurations resulting in a unique complex of potential environmental effects for each device type, which are discussed to the extent possible. - Highlights: Black-Right-Pointing-Pointer We review the environmental impacts of tidal barrages and fences, tidal stream farms and wave energy capture devices. Black-Right-Pointing-Pointer Impacts on habitats, species and the water column, and effects of noise and electromagnetic fields are considered. Black-Right-Pointing-Pointer Tidal barrages can cause significant impacts on bird feeding areas when constructed at coastal estuaries or bays. Black-Right-Pointing-Pointer Wave energy collectors can alter water column and sea bed habitats locally and over large distances.

  13. International Energy Agency Ocean Energy Systems Task 10 Wave Energy Converter Modeling Verification and Validation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, Fabian F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nielsen, Kim [Ramboll, Copenhagen (Denmark); Ruehl, Kelley [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bunnik, Tim [MARIN (Netherlands); Touzon, Imanol [Tecnalia (Spain); Nam, Bo Woo [KRISO (Korea, Rep. of); Kim, Jeong Seok [KRISO (Korea, Rep. of); Janson, Carl Erik [Chalmers University (Sweden); Jakobsen, Ken-Robert [EDRMedeso (Norway); Crowley, Sarah [WavEC (Portugal); Vega, Luis [Hawaii Natural Energy Institute (United States); Rajagopalan, Krishnakimar [Hawaii Natural Energy Institute (United States); Mathai, Thomas [Glosten (United States); Greaves, Deborah [Plymouth University (United Kingdom); Ransley, Edward [Plymouth University (United Kingdom); Lamont-Kane, Paul [Queen' s University Belfast (United Kingdom); Sheng, Wanan [University College Cork (Ireland); Costello, Ronan [Wave Venture (United Kingdom); Kennedy, Ben [Wave Venture (United Kingdom); Thomas, Sarah [Floating Power Plant (Denmark); Heras, Pilar [Floating Power Plant (Denmark); Bingham, Harry [Technical University of Denmark (Denmark); Kurniawan, Adi [Aalborg University (Denmark); Kramer, Morten Mejlhede [Aalborg University (Denmark); Ogden, David [INNOSEA (France); Girardin, Samuel [INNOSEA (France); Babarit, Aurelien [EC Nantes (France); Wuillaume, Pierre-Yves [EC Nantes (France); Steinke, Dean [Dynamic Systems Analysis (Canada); Roy, Andre [Dynamic Systems Analysis (Canada); Beatty, Scott [Cascadia Coast Research (Canada); Schofield, Paul [ANSYS (United States); Kim, Kyong-Hwan [KRISO (Korea, Rep. of); Jansson, Johan [KTH Royal Inst. of Technology, Stockholm (Sweden); BCAM (Spain); Hoffman, Johan [KTH Royal Inst. of Technology, Stockholm (Sweden)

    2017-10-16

    This is the first joint reference paper for the Ocean Energy Systems (OES) Task 10 Wave Energy Converter modeling verification and validation group. The group is established under the OES Energy Technology Network program under the International Energy Agency. OES was founded in 2001 and Task 10 was proposed by Bob Thresher (National Renewable Energy Laboratory) in 2015 and approved by the OES Executive Committee EXCO in 2016. The kickoff workshop took place in September 2016, wherein the initial baseline task was defined. Experience from similar offshore wind validation/verification projects (OC3-OC5 conducted within the International Energy Agency Wind Task 30) [1], [2] showed that a simple test case would help the initial cooperation to present results in a comparable way. A heaving sphere was chosen as the first test case. The team of project participants simulated different numerical experiments, such as heave decay tests and regular and irregular wave cases. The simulation results are presented and discussed in this paper.

  14. Development of a wave-induced forcing threshold for nearshore impact of Wave Energy Converter arrays

    Science.gov (United States)

    O'Dea, A.; Haller, M. C.; Ozkan-Haller, H. T.

    2016-02-01

    Wave-induced forcing is a function of spatial gradients in the wave radiation stresses and is the main driver of alongshore currents, rip currents, and nearshore sediment transport. The installation of nearshore Wave Energy Converter (WEC) arrays may cause significant changes in the surf zone radiation stresses and could therefore impact nearshore littoral processes. In the first part of this study, a new threshold for nearshore hydrodynamic impact due to the presence of WEC devices is established based on changes in the alongshore radiation stress gradients shoreward of WEC arrays. The threshold is defined based on the relationship between nearshore radiation stresses and alongshore currents as observed in field data. Next, we perform a parametric study of the nearshore impact of WEC arrays using the SWAN wave model. Trials are conducted on an idealized, alongshore-uniform beach with a range of WEC array configurations, locations, and incident wave conditions, and conditions that generate radiation stress gradients above the impact threshold are identified. Finally, the same methodology is applied to two wave energy test sites off the coast of Newport, OR with more complicated bathymetries. Although the trends at the field sites are similar to those seen in the parametric study, the location and extent of the changes in the alongshore radiation stress gradients appear to be heavily influenced by the local bathymetry.

  15. Comparison of heaving buoy and oscillating flap wave energy converters

    Science.gov (United States)

    Abu Bakar, Mohd Aftar; Green, David A.; Metcalfe, Andrew V.; Najafian, G.

    2013-04-01

    Waves offer an attractive source of renewable energy, with relatively low environmental impact, for communities reasonably close to the sea. Two types of simple wave energy converters (WEC), the heaving buoy WEC and the oscillating flap WEC, are studied. Both WECs are considered as simple energy converters because they can be modelled, to a first approximation, as single degree of freedom linear dynamic systems. In this study, we estimate the response of both WECs to typical wave inputs; wave height for the buoy and corresponding wave surge for the flap, using spectral methods. A nonlinear model of the oscillating flap WEC that includes the drag force, modelled by the Morison equation is also considered. The response to a surge input is estimated by discrete time simulation (DTS), using central difference approximations to derivatives. This is compared with the response of the linear model obtained by DTS and also validated using the spectral method. Bendat's nonlinear system identification (BNLSI) technique was used to analyze the nonlinear dynamic system since the spectral analysis was only suitable for linear dynamic system. The effects of including the nonlinear term are quantified.

  16. Wave energy, lever operated pivoting float LOPF study

    Energy Technology Data Exchange (ETDEWEB)

    Margheritini, L.

    2012-11-01

    The fully instrumented Resen Waves Lever Operated Pivoting Float LOPF wave energy buoy model has gone through the first stage of testing in regular waves in scale 1:25 of the North Sea wave conditions, in the 3D deep wave basin at the Hydraulic and Coastal Engineering Laboratory of Aalborg University in Denmark. The model size was 60cm W x 90cm L x 21cm H. The 60 cm width pointed towards the wave front. The LOPF buoy is characterized by a simple mechanical design with few moving parts and direct electrical output and it is taut moored to the sea bed, so all forces are referenced to the seabed for maximum energy output in regular as well as irregular waves. During storms the buoy pivots and streamlines itself to minimize loads on the mooring line. A conservative estimate shows that a full scale system for North Sea conditions has a float size width of 15 m that will, with 60% generator efficiency, produce 610 MWh/y (609.497 kWh/y) with an average power output of 69.6 kW, which requires a generator capacity of 700 kW. It is expected the generator efficiency can be increased to 90% in the future. More specific calculations (from EnergiNet) show that with one generator of 695 kW the expected power production is 585 MWh/y; with a generator of 250 kW and 100 kW, the expected power production is 481 MWh/y and 182 MWh/y respectively. In addition there are several areas for future improvements for increased power production. (Author)

  17. System for harvesting water wave energy

    Science.gov (United States)

    Wang, Zhong Lin; Su, Yanjie; Zhu, Guang; Chen, Jun

    2016-07-19

    A generator for harvesting energy from water in motion includes a sheet of a hydrophobic material, having a first side and an opposite second side, that is triboelectrically more negative than water. A first electrode sheet is disposed on the second side of the sheet of a hydrophobic material. A second electrode sheet is disposed on the second side of the sheet of a hydrophobic material and is spaced apart from the first electrode sheet. Movement of the water across the first side induces an electrical potential imbalance between the first electrode sheet and the second electrode sheet.

  18. Wave energy budget analysis in the Earth’s radiation belts uncovers a missing energy

    Science.gov (United States)

    Artemyev, A.V.; Agapitov, O.V.; Mourenas, D.; Krasnoselskikh, V.V.; Mozer, F.S.

    2015-01-01

    Whistler-mode emissions are important electromagnetic waves pervasive in the Earth’s magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth’s magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave–particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth’s radiation belts, controlled by solar activity. PMID:25975615

  19. Wave energy fluxes and multi-decadal shoreline changes

    DEFF Research Database (Denmark)

    Kabuth, Alina Kristin; Kroon, Aart

    2014-01-01

    Spatial patterns of multidecadal shoreline changes in two microtidal, low-energetic embayments of southern Zealand, Denmark, were investigated by using the directional distribution of wave energy fluxes. The sites include a barrier island system attached to moraine bluffs, and a recurved spit...... variability of directional distributions of wave energy fluxes furthermore outlined potential sediment sources and sinks for the evolution of the barrier island system and for the evolution of the recurved spit....... adjacent to a cliff coast. The barrier island system is characterized by cross-shore translation and by an alignment of the barrier alongshore alternating directions of barrier-spit progradation in a bidirectional wave field. The recurved spit adjacent to the cliff coast experienced shoreline rotation...

  20. Wave loadings acting on Overtopping Breakwater for Energy Conversion

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Nørgaard, Jørgen Harck; Contestabile, Pasquale

    2013-01-01

    distributions. Load measurements were compared with the most used prediction method for traditional breakwaters, available in the Coastal Engineering Manual (U.S. Army Corps of Engineers, 2002). These results suggest to use the experimental data as design loadings since the design criteria for the innovative......Any kind of Wave Energy Converter (WEC) requires information on reliability of technology and on time required for the return of the investment (reasonable payback). The structural response is one of the most important parameters to take in to account for a consistent assessment on innovative...... devices. This paper presents results on wave loading acting on an hybrid WEC named Overtopping BReakwater for Energy Conversion (OBREC). The new design is based on the concept of an integration between a traditional rubble mound breakwater and a front reservoir designed to store the wave overtopping from...

  1. Transducer handbook user's directory of electrical transducers

    CERN Document Server

    Boyle, H B

    2013-01-01

    When selecting or using a particular type of transducer or sensor, there are a number of factors which must be considered. The question is not only for what kind of measurement, but under what physical conditions, constraints of accuracy, and to meet which service requirements, is a transducer needed? This handbook is designed to meet the selection needs of anyone specifying or using transducers with an electrical output. Each transducer is described in an easy-to-use tabular format, giving all of the necessary data including operating principles, applications, range limits, errors, over-range protection, supply voltage requirements, sensitivities, cross sensitivities, temperature ranges and sensitivities and signal conditioning needs. The author has added notes that reflect his broad practical experience. Added to this is an extensive worldwide suppliers directory.

  2. Prediction of the Individual Wave Overtopping Volumes of a Wave Energy Converter using Experimental Testing and First Numerical Model Results

    DEFF Research Database (Denmark)

    Victor, L.; Troch, P.; Kofoed, Jens Peter

    2009-01-01

    For overtopping wave energy converters (WECs) a more efficient energy conversion can be achieved when the volumes of water, wave by wave, that enter their reservoir are known and can be predicted. A numerical tool is being developed using a commercial CFD-solver to study and optimize...... nearshore 2Dstructure. First numerical model results are given for a specific test with regular waves, and are compared with the corresponding experimental results in this paper....

  3. Life Cycle Assessment of a Wave Energy Converter

    OpenAIRE

    Gastelum Zepeda, Leonardo

    2017-01-01

    Renewable energies had accomplish to become part of a new era in the energy development area, making people able to stop relying on fossil fuels. Nevertheless the environmental impacts of these new energy sources also require to be quantified in order to review how many benefits these new technologies have for the environment. In this project the use of a Life Cycle Assessment (LCA) will be implemented in order to quantify the environmental impact of wave energy, an LCA is a technique for ass...

  4. Wave Energy Converter (WEC) Array Effects on Wave Current and Sediment Circulation: Monterey Bay CA.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Jones, Craig; Magalen, Jason

    2014-09-01

    The goal s of this study were to develop tools to quantitatively characterize environments where wave energy converter ( WEC ) devices may be installed and to assess e ffects on hydrodynamics and lo cal sediment transport. A large hypothetical WEC array was investigated using wave, hydrodynamic, and sediment transport models and site - specific average and storm conditions as input. The results indicated that there were significant changes in sediment s izes adjacent to and in the lee of the WEC array due to reduced wave energy. The circulation in the lee of the array was also altered; more intense onshore currents were generated in the lee of the WECs . In general, the storm case and the average case show ed the same qualitative patterns suggesting that these trends would be maintained throughout the year. The framework developed here can be used to design more efficient arrays while minimizing impacts on nearshore environmen ts.

  5. Conversion of the energy of a high-current REB into electromagnetic wave energy

    International Nuclear Information System (INIS)

    Kurilko, V.I.; Kharchenko, I.F.

    2000-01-01

    Results are presented from a theoretical investigation and quantitative analysis of the physical processes that govern the efficiency of a coaxial device aimed at converting the energy of a relativistic electron beam into the energy of a TEM wave (a wave in a circular cylindrical coaxial waveguide). The key diffractional problem is solved exactly using a simplified theoretical model, which makes it possible to understand the mechanisms for the formation of a TEM wave and determine how the beam parameters and the design parameters of the converter affect the relative fractions of the kinetic energy of a relativistic electron beam and the energy of its own magnetic and electric fields that are transferred into the energy of the TEM wave field. The results obtained are analyzed quantitatively, and prospects for further theoretical and experimental research in this area are outlined

  6. Experimental Study on a Rotor for WEPTOS Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Marchalot, Tanguy

    This report presents the results of an experimental study of the power conversion capabilities of one single rotor of the WEPTOS wave energy converter. The investigation focuses mainly on defining the optimal weight distribution in the rotor in order to improve the hydraulic performance through...

  7. Optimization of Overtopping Wave Energy Converters by Geometry Control

    DEFF Research Database (Denmark)

    Victor, L.; Troch, P.; Kofoed, Jens Peter

    2011-01-01

    In this paper, the results of a study on the effects of geometry control on the performance of overtopping wave energy converters with a simple geometry built in coastal structures (simple OWECs) are presented. Empirical formulae, derived based on experimental tests on simple OWECs with varying...

  8. Different Reliability Assessment Approaches for Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten Mejlhede; Sørensen, John Dalsgaard

    2015-01-01

    Reliability assessments are of importance for wave energy converters (WECs) due to the fact that accessibility might be limited in case of failure and maintenance. These failure rates can be adapted by reliability considerations. There are two different approaches to how reliability can...

  9. Experimental testing of moorings for large floating wave energy converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Ferri, Francesco; Kofoed, Jens Peter

    2016-01-01

    This paper presents the outcome of a test campaign, which investigates the behaviour of a synthetic mooring system applied to the Floating Power Plant wave energy converter. The study investigates the motion and tension response under operational and extreme sea states expected at the deployment ...

  10. Electromagnetic Lead Screw for Potential Wave Energy Application

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Wu, Weimin

    2014-01-01

    This paper presents a new type electromagnetic lead screw (EMLS) intended for wave energy application. Similar to the mechanical lead screw, this electromagnetic version can transfer slow linear motion to high-rotational motion, offering gearing effects. Compared with the existing pure magnetic...

  11. Aiding Design of Wave Energy Converters via Computational Simulations

    Science.gov (United States)

    Jebeli Aqdam, Hejar; Ahmadi, Babak; Raessi, Mehdi; Tootkaboni, Mazdak

    2015-11-01

    With the increasing interest in renewable energy sources, wave energy converters will continue to gain attention as a viable alternative to current electricity production methods. It is therefore crucial to develop computational tools for the design and analysis of wave energy converters. A successful design requires balance between the design performance and cost. Here an analytical solution is used for the approximate analysis of interactions between a flap-type wave energy converter (WEC) and waves. The method is verified using other flow solvers and experimental test cases. Then the model is used in conjunction with a powerful heuristic optimization engine, Charged System Search (CSS) to explore the WEC design space. CSS is inspired by charged particles behavior. It searches the design space by considering candidate answers as charged particles and moving them based on the Coulomb's laws of electrostatics and Newton's laws of motion to find the global optimum. Finally the impacts of changes in different design parameters on the power takeout of the superior WEC designs are investigated. National Science Foundation, CBET-1236462.

  12. Initial Assessment of Mooring Solutions for Floating Wave Energy Converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Kofoed, Jens Peter; Delaney, Martin

    2016-01-01

    The present study investigates three different types of mooring systems in order to establish potential cost reductions and applicability to wave energy converters (WECs). Proposed mooring systems for three existing WECs create the basis for this study, and the study highlights areas of interest ...

  13. Helicity and evanescent waves. [Energy transport velocity, helicity, Lorentz transformation

    Energy Technology Data Exchange (ETDEWEB)

    Agudin, J L; Platzeck, A M [La Plata Univ. Nacional (Argentina); Albano, J R [Instituto de Astronomia y Fisica del Espacio, Buenos Aires, Argentina

    1978-02-20

    It is shown that the projection of the angular momentum of a circularly polarized electromagnetic evanescent wave along the mean velocity of energy transport (=helicity) can be reverted by a Lorentz transformation, in spite of the fact that this velocity is c.

  14. Dynamic Theory: some shock wave and energy implications

    International Nuclear Information System (INIS)

    Williams, P.E.

    1981-02-01

    The Dynamic Theory, a unifying five-dimensional theory of space, time, and matter, is examined. The theory predicts an observed discrepancy between shock wave viscosity measurements at low and high pressures in aluminum, a limiting mass-to-energy conversion rate consistent with the available data, and reduced pressures in electromagneticaly contained controlled-fusion plasmas

  15. Wave loadings acting on innovative rubble mound breakwater for overtopping wave energy conversion

    DEFF Research Database (Denmark)

    Contestabile, Pasquale; Iuppa, Claudio; Lauro, Enrico Di

    2017-01-01

    Highlights •An innovative breakwater for overtopping wave energy conversion has been studied. •Physical model tests have been carried out and analysed. •Breakwater design information on loadings acting on various parts of the structure has been presented. •Design formulae and validation of some t...

  16. Preliminary Results from Second Phase Sea Testing of the Wave Dragon Prototype Wave Energy Converter

    DEFF Research Database (Denmark)

    Soerensen, Hans Chr.; Tedd, James; Friis-Madsen, Erik

    2006-01-01

    In March 2006 the prototype Wave Dragon has been redeployed to a more energetic site in Nissum Bredning an inland sea in Western Denmark. This has followed a period of renovation of many aspects of the device which have resulted in 20% higher energy output. This paper describes the preliminary...

  17. Structural Optimization of Triboelectric Nanogenerator for Harvesting Water Wave Energy.

    Science.gov (United States)

    Jiang, Tao; Zhang, Li Min; Chen, Xiangyu; Han, Chang Bao; Tang, Wei; Zhang, Chi; Xu, Liang; Wang, Zhong Lin

    2015-12-22

    Ocean waves are one of the most abundant energy sources on earth, but harvesting such energy is rather challenging due to various limitations of current technologies. Recently, networks formed by triboelectric nanogenerator (TENG) have been proposed as a promising technology for harvesting water wave energy. In this work, a basic unit for the TENG network was studied and optimized, which has a box structure composed of walls made of TENG composed of a wavy-structured Cu-Kapton-Cu film and two FEP thin films, with a metal ball enclosed inside. By combination of the theoretical calculations and experimental studies, the output performances of the TENG unit were investigated for various structural parameters, such as the size, mass, or number of the metal balls. From the viewpoint of theory, the output characteristics of TENG during its collision with the ball were numerically calculated by the finite element method and interpolation method, and there exists an optimum ball size or mass to reach maximized output power and electric energy. Moreover, the theoretical results were well verified by the experimental tests. The present work could provide guidance for structural optimization of wavy-structured TENGs for effectively harvesting water wave energy toward the dream of large-scale blue energy.

  18. Optimum Operating Conditions of (PbxX1−x(ZryTizY1−y−z Piezoelectric Transducer for Vibrational Energy Harvesting Applications

    Directory of Open Access Journals (Sweden)

    Funda Demir

    2016-01-01

    Full Text Available The electrical energy production capability of bimorph (PbxX1-x(ZryTizY1-y-z fiber composite piezoelectric transducer has been investigated for energy harvesting applications. The material has been analyzed under different frequencies, bending amounts, and temperatures. The operating conditions for maximum electrical energy outcome have been determined. The natural frequencies of oscillations in the macro dimensions have been found to be inversely proportional to the length of the material. On the other hand, the voltage output with respect to the oscillation frequency exhibits an interesting behavior such that the characteristic curve shifts to higher frequencies as the bending radius is decreased. This behavior has been interpreted as a result of possible overtone transitions of the oscillations to a stiffer mode. The increasing temperature has been observed to have a negative effect on the piezoelectric energy harvesting property. When the determined optimum conditions were utilized, the amount of electrical energy stored in 6300 s by an energy harvester circuitry has been found to be 0.8 J.

  19. Passive Mode Carbon Nanotube Underwater Acoustic Transducer

    Science.gov (United States)

    2016-09-20

    Acoustical transducer arrays can reflect a sound signal in reverse to the sender which can be used for echo location devices. [0008] In Jiang...States Patent No. 8,494,187) a sound wave generator is disclosed which includes a carbon nanotube structure and an insulating reinforcement structure... acoustic device that includes an electrode layer and a sound wave generator. The sound wave generator is disposed on a surface of the electrode

  20. Technological and Economic Aspects of Wave Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Rahul Basu

    2018-01-01

    Full Text Available The geographical regions contiguous to the Indian Ocean, Bay of Bengal and the Arabian Sea are prone to natural disasters and poor electric supply especially in rural and hard to reach coastal regions. Utilization of ocean resources for power generation such as tidal, thermal solar and wind for energy need to be incorporated in a broad framework for the region. Development of ocean-based energy systems can be integrated with early warning networks linked by satellite which can give a few hours to days warning to help mitigate the severity of natural disasters on human life. Ocean-based electricity extraction has; however, remained elusive for various reasons. Interest in these systems resumed after the oil crisis of the 1970’s, but was uncoordinated. Extraction of ocean energy from the kinetic energy of waves and ocean currents depends on various mechanical devices with variable efficiencies. Apart from the efficiency, one must match the output phase of the feeder waveforms with that of the electrical grid. Also, the wavelengths of the typical wave are of the order of a few meters, the interception of which requires large devices. The mechanical efficiency of the turbine extraction system is further limited by the flow momentum considerations. Some applications and their implementation are looked at, specifically with reference to the difficulties of implementation in the region, and other factors like economic efficiency (rate of returns in place of mechanical efficiency. Individual wave energy harvesters are thus bound to suffer from inefficiencies and it may be beneficial to use wave farm configurations from the point of view of the randomness of wave motion, the large wavelengths, and the added advantage of averaging fluctuations from large numbers of generators.

  1. Consequences of wave function orthogonality for medium energy nuclear reactions

    International Nuclear Information System (INIS)

    Noble, J.V.

    1978-01-01

    In the usual models of high-energy bound-state to continuum transitions no account is taken of the orthogonality of the bound and continuum wave functions. This orthogonality induces considerable cancellations in the overlap integrals expressing the transition amplitudes for reactions such as (e,e'p), (γ,p), and (π,N), which are simply not included in the distorted-wave Born-approximation calculations which to date remain the only computationally feasible heirarchy of approximations. The object of this paper is to present a new formulation of the bound-state to continuum transition problem, based upon flux conservation, in which the orthogonality of wave functions is taken into account ab initio. The new formulation, while exact if exact wave functions are used, offers the possibility of using approximate wave functions for the continuum states without doing violence to the cancellations induced by orthogonality. The method is applied to single-particle states obeying the Schroedinger and Dirac equations, as well as to a coupled-channel model in which absorptive processes can be described in a fully consistent manner. Several types of absorption vertex are considered, and in the (π,N) case the equivalence of pseudoscalar and pseudovector πNN coupling is seen to follow directly from wave function orthogonality

  2. DANWEC - Empirical Analysis of the Wave Climate at the Danish Wave Energy Centre

    DEFF Research Database (Denmark)

    Tetu, Amelie; Nielsen, Kim; Kofoed, Jens Peter

    information on the DanWEC wave and current climate. In this paper an analysis of the wave climate of the DanWEC test site will be presented. This includes a description of the data quality control and filtration for analysis and the observations and data analysis. Relevant characteristics of the test site...... site for several Danish WECs. In 2013 DanWEC has received Greenlab funding from the EUDP programme to establish the site including more detailed information on its wave climate and bathymetry and seabed conditions. The project “Resource Assessment, Forecasts and WECs O&M strategies at DanWEC and beyond......, as for example scatter diagram (Hm0, Tz) will be analysed and wave power distribution given. Based on the data gathered so far a preliminary analysis of extreme events at the DanWEC test site will be presented. Deployment, control strategies and O&M strategies of wave energy converters are sensitive to the wave...

  3. Report on feasibility study of the Clam Wave Energy Device

    Energy Technology Data Exchange (ETDEWEB)

    1979-04-01

    The main emphasis of the feasibility study has been towards producing an acceptable spine design for the Clam wave energy converter. Concrete and steel designs based on a mathematical model of the waveloading have been produced. Progress is also reported in the design of a bellows for a low-pressure air power transmission system. A narrow wave tank and scale model have been constructed in order to carry out a test programme on various aspects of the device's construction and performance.

  4. Floating attenuator wave energy device. Wavegen HYDRA project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The Wavegen Project which set out to develop a floating externally tensioned articulated wave-energy generator based on work carried out at RMCS Shrivenham in the 1980s has been abandoned until further notice. The computer modelling carried out in the early days indicated much promise, but the promise turned to disappointment when difficulties cropped-up in attempting to put the design into practice. A particular problem arose in matching the external tension to an equivalent beam stiffness to tune the natural bending frequency of the raft to that of the driving waves. A further eleven practical problems encountered are discussed.

  5. Assessment of tidal and wave energy conversion technologies in Canada

    International Nuclear Information System (INIS)

    2009-01-01

    This paper presented an attractive option to help meet Canada's future energy needs, notably the vast and energetic Atlantic, Pacific and Arctic coastal waters which make ocean renewable energy, particularly tidal in-stream energy conversion (TISEC) and wave energy conversion (WEC). There is much uncertainty regarding the possible environmental impacts associated with their deployment and operation. In support of commercial development of the industry, a review of scientific knowledge was needed for the development of policy and regulations consistent with Canada's conservation and sustainability priorities. In April 2009, Fisheries and Oceans Canada (DFO) hosted a two-day national science advisory process meeting in order to determine the current state of knowledge on the environmental impacts of tidal and wave energy conversion technologies and their application in the Canadian context based on published reports. Potential mitigation measures were identified and the feasibility of developing a relevant Canadian statement of practice was determined. This report presented an assessment and analysis of wave power, including the impacts on physical processes; impacts on habitat characteristics; impacts on water quality; impacts of noise and vibrations; impacts of electromagnetic fields; impacts of physical encounters; cumulative impacts; and mitigation measures. It was concluded that there is a recognized need to develop and maintain national and regional georeferenced, interoperable, standards-based databases that enable access by governments, developers, academics, non-governmental organizations and the general public. 1 ref., 1 fig.

  6. A Skin-attachable Flexible Piezoelectric Pulse Wave Energy Harvester

    International Nuclear Information System (INIS)

    Yoon, Sunghyun; Cho, Young-Ho

    2014-01-01

    We present a flexible piezoelectric generator, capable to harvest energy from human arterial pulse wave on the human wrist. Special features and advantages of the flexible piezoelectric generator include the multi-layer device design with contact windows and the simple fabrication process for the higher flexibility with the better energy harvesting efficiency. We have demonstrated the design effectiveness and the process simplicity of our skin- attachable flexible piezoelectric pulse wave energy harvester, composed of the sensitive P(VDF-TrFE) piezoelectric layer on the flexible polyimide support layer with windows. We experimentally characterize and demonstrate the energy harvesting capability of 0.2∼1.0μW in the Human heart rate range on the skin contact area of 3.71cm 2 . Additional physiological and/or vital signal monitoring devices can be fabricated and integrated on the skin attachable flexible generator, covered by an insulation layer; thus demonstrating the potentials and advantages of the present device for such applications to the flexible multi-functional selfpowered artificial skins, capable to detect physiological and/or vital signals on Human skin using the energy harvested from arterial pulse waves

  7. Stochastic control of inertial sea wave energy converter.

    Science.gov (United States)

    Raffero, Mattia; Martini, Michele; Passione, Biagio; Mattiazzo, Giuliana; Giorcelli, Ermanno; Bracco, Giovanni

    2015-01-01

    The ISWEC (inertial sea wave energy converter) is presented, its control problems are stated, and an optimal control strategy is introduced. As the aim of the device is energy conversion, the mean absorbed power by ISWEC is calculated for a plane 2D irregular sea state. The response of the WEC (wave energy converter) is driven by the sea-surface elevation, which is modeled by a stationary and homogeneous zero mean Gaussian stochastic process. System equations are linearized thus simplifying the numerical model of the device. The resulting response is obtained as the output of the coupled mechanic-hydrodynamic model of the device. A stochastic suboptimal controller, derived from optimal control theory, is defined and applied to ISWEC. Results of this approach have been compared with the ones obtained with a linear spring-damper controller, highlighting the capability to obtain a higher value of mean extracted power despite higher power peaks.

  8. Innovative rubble mound breakwaters for wave energy conversion

    International Nuclear Information System (INIS)

    Contestabile, Pasquale; Vicinanza, Diego; Iuppa, Claudio; Cavallaro, Luca; Foti, Enrico

    2015-01-01

    This paper presents a new Wave Energy Converter named Overtopping BReakwater for Energy Conversion (OBREC) which consists of a rubble mound breakwater with a front reservoir designed with the aim of capturing the wave overtopping in order to produce electricity. The energy is extracted via low head turbines, using the difference in water levels between the reservoir and the mean sea water level. The new design should be capable of adding a revenue generation function to a breakwater while adding cost sharing benefits due to integration. The design can be applied to harbour expansions, existing breakwater maintenance or upgrades due to climate change for a relatively low cost, considering the breakwater would be built regardless of the inclusion of a WEC [it

  9. Operation and maintenance strategies for wave energy converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Marquis, Laurent; Kofoed, Jens Peter

    2015-01-01

    costs including costs due to lost electricity production are minimized. The risk-based approach is compared with an approach where only boats are used and another approach where the target is to minimize the downtime of the device. This article presents a dynamic approach for total operation......Inspection and maintenance costs are a significant contributor to the cost of energy for wave energy converters. There are different operation and maintenance strategies for wave energy converters. Maintenance can be performed after failure (corrective) or before a breakdown (preventive) occurs....... Furthermore, a helicopter and boats can be used to transport equipment and personnel to the device, or the whole device can be towed to a harbour for operation and maintenance actions. This article describes, among others, a risk-based inspection and maintenance planning approach where the overall repair...

  10. Stochastic Control of Inertial Sea Wave Energy Converter

    Science.gov (United States)

    Mattiazzo, Giuliana; Giorcelli, Ermanno

    2015-01-01

    The ISWEC (inertial sea wave energy converter) is presented, its control problems are stated, and an optimal control strategy is introduced. As the aim of the device is energy conversion, the mean absorbed power by ISWEC is calculated for a plane 2D irregular sea state. The response of the WEC (wave energy converter) is driven by the sea-surface elevation, which is modeled by a stationary and homogeneous zero mean Gaussian stochastic process. System equations are linearized thus simplifying the numerical model of the device. The resulting response is obtained as the output of the coupled mechanic-hydrodynamic model of the device. A stochastic suboptimal controller, derived from optimal control theory, is defined and applied to ISWEC. Results of this approach have been compared with the ones obtained with a linear spring-damper controller, highlighting the capability to obtain a higher value of mean extracted power despite higher power peaks. PMID:25874267

  11. Coupled Triboelectric Nanogenerator Networks for Efficient Water Wave Energy Harvesting.

    Science.gov (United States)

    Xu, Liang; Jiang, Tao; Lin, Pei; Shao, Jia Jia; He, Chuan; Zhong, Wei; Chen, Xiang Yu; Wang, Zhong Lin

    2018-02-27

    Water wave energy is a promising clean energy source, which is abundant but hard to scavenge economically. Triboelectric nanogenerator (TENG) networks provide an effective approach toward massive harvesting of water wave energy in oceans. In this work, a coupling design in TENG networks for such purposes is reported. The charge output of the rationally linked units is over 10 times of that without linkage. TENG networks of three different connecting methods are fabricated and show better performance for the ones with flexible connections. The network is based on an optimized ball-shell structured TENG unit with high responsivity to small agitations. The dynamic behavior of single and multiple TENG units is also investigated comprehensively to fully understand their performance in water. The study shows that a rational design on the linkage among the units could be an effective strategy for TENG clusters to operate collaboratively for reaching a higher performance.

  12. WEC3: Wave Energy Converter Code Comparison Project: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Combourieu, Adrien; Lawson, Michael; Babarit, Aurelien; Ruehl, Kelley; Roy, Andre; Costello, Ronan; Laporte Weywada, Pauline; Bailey, Helen

    2017-01-01

    This paper describes the recently launched Wave Energy Converter Code Comparison (WEC3) project and present preliminary results from this effort. The objectives of WEC3 are to verify and validate numerical modelling tools that have been developed specifically to simulate wave energy conversion devices and to inform the upcoming IEA OES Annex VI Ocean Energy Modelling Verification and Validation project. WEC3 is divided into two phases. Phase 1 consists of a code-to-code verification and Phase II entails code-to-experiment validation. WEC3 focuses on mid-fidelity codes that simulate WECs using time-domain multibody dynamics methods to model device motions and hydrodynamic coefficients to model hydrodynamic forces. Consequently, high-fidelity numerical modelling tools, such as Navier-Stokes computational fluid dynamics simulation, and simple frequency domain modelling tools were not included in the WEC3 project.

  13. Stochastic Control of Inertial Sea Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Mattia Raffero

    2015-01-01

    Full Text Available The ISWEC (inertial sea wave energy converter is presented, its control problems are stated, and an optimal control strategy is introduced. As the aim of the device is energy conversion, the mean absorbed power by ISWEC is calculated for a plane 2D irregular sea state. The response of the WEC (wave energy converter is driven by the sea-surface elevation, which is modeled by a stationary and homogeneous zero mean Gaussian stochastic process. System equations are linearized thus simplifying the numerical model of the device. The resulting response is obtained as the output of the coupled mechanic-hydrodynamic model of the device. A stochastic suboptimal controller, derived from optimal control theory, is defined and applied to ISWEC. Results of this approach have been compared with the ones obtained with a linear spring-damper controller, highlighting the capability to obtain a higher value of mean extracted power despite higher power peaks.

  14. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  15. Modeling of the attenuation of stress waves in concrete based on the Rayleigh damping model using time-reversal and PZT transducers

    Science.gov (United States)

    Tian, Zhen; Huo, Linsheng; Gao, Weihang; Li, Hongnan; Song, Gangbing

    2017-10-01

    Wave-based concrete structural health monitoring has attracted much attention. A stress wave experiences significant attenuation in concrete, however there is a lack of a unified method for predicting the attenuation coefficient of the stress wave. In this paper, a simple and effective absorption attenuation model of stress waves in concrete is developed based on the Rayleigh damping model, which indicates that the absorption attenuation coefficient of stress waves in concrete is directly proportional to the square of the stress wave frequency when the damping ratio is small. In order to verify the theoretical model, related experiments were carried out. During the experiments, a concrete beam was designed in which the d33-model piezoelectric smart aggregates were embedded to detect the propagation of stress waves. It is difficult to distinguish direct stress waves due to the complex propagation paths and the reflection and scattering of stress waves in concrete. Hence, as another innovation of this paper, a new method for computing the absorption attenuation coefficient based on the time-reversal method is developed. Due to the self-adaptive focusing properties of the time-reversal method, the time-reversed stress wave focuses and generates a peak value. The time-reversal method eliminates the adverse effects of multipaths, reflection, and scattering. The absorption attenuation coefficient is computed by analyzing the peak value changes of the time-reversal focused signal. Finally, the experimental results are found to be in good agreement with the theoretical model.

  16. Performance Assessment of the Wave Dragon Wave Energy Converter Based on the EquiMar Methodology

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Chozas, Julia Fernandez; Pecher, Arthur

    2011-01-01

    At the present pre-commercial phase of the wave energy sector, device developers are called to provide reliable estimates on power performance and production at possible deployment locations. The EU EquiMar project has proposed a novel approach, where the performance assessment is based mainly...... on experimental data deriving from sea trials rather than solely on numerical predictions. The study applies this methodology to evaluate the performance of Wave Dragon at two locations in the North Sea, based on the data acquired during the sea trials of a 1:4.5 scale prototype. Indications about power...

  17. Impact of Tidal Level Variations on Wave Energy Absorption at Wave Hub

    Directory of Open Access Journals (Sweden)

    Valeria Castellucci

    2016-10-01

    Full Text Available The energy absorption of the wave energy converters (WEC characterized by a limited stroke length —like the point absorbers developed at Uppsala University—depends on the sea level variation at the deployment site. In coastal areas characterized by high tidal ranges, the daily energy production of the generators is not optimal. The study presented in this paper quantifies the effects of the changing sea level at the Wave Hub test site, located at the south-west coast of England. This area is strongly affected by tides: the tidal height calculated as the difference between the Mean High Water Spring and the Mean Low Water Spring in 2014 was about 6.6 m. The results are obtained from a hydro-mechanic model that analyzes the behaviour of the point absorber at the Wave Hub, taking into account the sea state occurrence scatter diagram and the tidal time series at the site. It turns out that the impact of the tide decreases the energy absorption by 53%. For this reason, the need for a tidal compensation system to be included in the design of the WEC becomes compelling. The economic advantages are evaluated for different scenarios: the economic analysis proposed within the paper allows an educated guess to be made on the profits. The alternative of extending the stroke length of the WEC is investigated, and the gain in energy absorption is estimated.

  18. Modeling and Simulation of a Wave Energy Converter INWAVE

    Directory of Open Access Journals (Sweden)

    Seung Kwan Song

    2017-01-01

    Full Text Available INGINE Inc. developed its own wave energy converter (WEC named INWAVE and has currently installed three prototype modules in Jeju Island, Korea. This device is an on-shore-type WEC that consists of a buoy, pulleys fixed to the sea-floor and a power take off module (PTO. Three ropes are moored tightly on the bottom of the buoy and connected to the PTO via the pulleys, which are moving back and forth according to the motion of the buoy. Since the device can harness wave energy from all six degrees of movement of the buoy, it is possible to extract energy efficiently even under low energy density conditions provided in the coastal areas. In the PTO module, the ratchet gears convert the reciprocating movement of the rope drum into a uni-directional rotation and determine the transmission of power from the relation of the angular velocities between the rope drum and the generator. In this process, the discontinuity of the power transmission occurs and causes the modeling divergence. Therefore, we introduce the concept of the virtual torsion spring in order to prevent the impact error in the ratchet gear module, thereby completing the PTO modeling. In this paper, we deal with dynamic analysis in the time domain, based on Newtonian mechanics and linear wave theory. We derive the combined dynamics of the buoy and PTO modules via geometric relation between the buoy and mooring ropes, then suggest the ratchet gear mechanism with the virtual torsion spring element to reduce the dynamic errors during the phase transitions. Time domain simulation is carried out under irregular waves that reflect the actual wave states of the installation area, and we evaluate the theoretical performance using the capture width ratio.

  19. Further Development of SNL‐Swan, a Validated Wave Energy Converter

    OpenAIRE

    Porter, Aaron; Ruehl, Kelley; Chartrand, Chris

    2014-01-01

    Commercialization of wave energy will lead to the necessary deployment of Wave Energy Converters (WECs) in arrays, or wave farms. In order for projects in the United States to be approved, regulatory agencies must perform an Environmental Assessment proving little to no environmental impact. However, little is known about the environmental impacts of such wave farms. As a result, the environmental impacts of wave farms are largely determined by numerical wave models capable of modeling large ...

  20. Analysis of Energy Overshoot of High Frequency Waves with Wavelet Transform

    Institute of Scientific and Technical Information of China (English)

    WEN Fan

    2000-01-01

    A study is made on the overshoot phenomena in wind-generated waves. The surface displace ments of time-growing waves are measured at four fetches in a wind wave channel. The evolution of high frequency waves is displayed with wavelet transform. The results are compared with Sutherland's. It is found that high frequency wave components experience much stronger energy overshoot in the evolution.The energy of high frequency waves decreases greatly after overshoot

  1. On the energy-momentum density of gravitational plane waves

    International Nuclear Information System (INIS)

    Dereli, T; Tucker, R W

    2004-01-01

    By embedding Einstein's original formulation of general relativity into a broader context, we show that a dynamic covariant description of gravitational stress-energy emerges naturally from a variational principle. A tensor T G is constructed from a contraction of the Bel tensor with a symmetric covariant second degree tensor field Φ and has a form analogous to the stress-energy tensor of the Maxwell field in an arbitrary spacetime. For plane-fronted gravitational waves helicity-2 polarized (graviton) states can be identified carrying non-zero energy and momentum

  2. Handbook of force transducers

    CERN Document Server

    Stefanescu, Dan Mihai

    2011-01-01

    Part I introduces the basic ""Principles and Methods of Force Measurement"" acording to a classification into a dozen of force transducers types: resistive, inductive, capacitive, piezoelectric, electromagnetic, electrodynamic, magnetoelastic, galvanomagnetic (Hall-effect), vibrating wires, (micro)resonators, acoustic and gyroscopic. Two special chapters refer to force balance techniques and to combined methods in force measurement. Part II discusses the ""(Strain Gauge) Force Transducers Components"", evolving from the classical force transducer to the digital / intelligent one, with the inco

  3. Dynamics and control of the GyroPTO wave energy point absorber under sea waves

    DEFF Research Database (Denmark)

    Zhang, Zili; Nielsen, Søren R.K.; Basu, Biswajit

    2017-01-01

    The Gyroscopic Power Take-Off (GyroPTO) wave energy point absorber has the operational principle somewhat similar to the so-called gyroscopic hand wrist exerciser. Inside the float of GyroPTO, there is a mechanical system made up of a spinning flywheel with its spin axis in rolling contact...... to a ring. At certain conditions, the ring starts to rotate at a frequency equal to the excitation angular frequency. In this synchronized state, the generator is running at almost constant speed and the generated power becomes constant. In this paper, theoretical modeling of the GyroPTO device is carried...... out based on analytical rigid body dynamics, and a 3-DOF nonlinear model is established. Simulation results show that synchronization of the device is maintained under harmonic sea wave, but is lost easily under non-harmonic sea waves.To overcome this problem, a magnetic coupling mechanism is added...

  4. Study of a Novel Oscillating Surge Wave Energy Converter: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Choiniere, Michael [University of Maine; Thiagarajan, Krish P. [University of Maine

    2017-08-01

    This study investigates the performance of an oscillating surge wave energy converter (OSWEC) that utilizes adjustable geometry as a means of controlling the hydrodynamic coefficients, a concept originally proposed by [1]. The body of the device consists of a bottom-hinged solid rectangular frame with five horizontal flaps spanning the interior of the frame. The flaps can rotate independently about their center of rotation within the frame like a large window shutter. Changing the orientation of the flaps alters the hydrodynamic coefficients and natural frequency of the device as well as the ability to shed or absorb structural loads accordingly. This ability may allow the device to operate in a wider range of sea states than other current wave energy converter designs. This paper presents and compares the results of numerical simulations and experimental testing of the OSWEC's response to regular waves with all five of the horizontal fin configurations sharing the same orientation of 0 degrees (fully closed interior) and 90 degrees (fully open). The numerical simulations were performed using WAMIT, which calculates hydrodynamic coefficients using a boundary element method code to solve the linear potential flow problem, and WEC-Sim, a MATLAB-based tool that simulates multibody devices in the time domain by solving the governing equations of motion. A 1:14 scale model of the device was built for experimental evaluation in an 8-m-long, 1-m wide wave tank, which supports a water depth of 0.7 m. The OSWEC motion in different wave conditions was measured with displacement sensors while nonlinear wave-structure interaction effects like slamming and overtopping were captured using a high-speed camera and used to understand differences between the simulation and experiments.

  5. Wecpos - Wave Energy Coastal Protection Oscillating System: A Numerical Assessment

    Science.gov (United States)

    Dentale, Fabio; Pugliese Carratelli, Eugenio; Rzzo, Gianfranco; Arsie, Ivan; Davide Russo, Salvatore

    2010-05-01

    In recent years, the interest in developing new technologies to produce energy with low environmental impact by using renewable sources has grown exponentially all over the world. In this context, the experiences made to derive electricity from the sea (currents, waves, etc.) are of particular interest. At the moment, due to the many existing experiments completed or still in progress, it is quite impossible explain what has been obtained but it is worth mentioning the EMEC, which summarizes the major projects in the world. Another important environmental aspect, also related to the maritime field, is the coastal protection from the sea waves. Even in this field, since many years, the structural and non-structural solutions which can counteract this phenomenon are analyzed, in order to cause the least possible damage to the environment. The studies in development by the researchers of the University of Salerno are based on these two aspect previously presented. Considering the technologies currently available, a submerged system has been designed, WECPOS (Wave Energy Coastal Protection Oscillating System), to be located on relatively shallow depths, to can be used simultaneously for both electricity generation and for the coastal protection using the oscillating motion of the water particles. The single element constituting the system is realized by a fixed base and three movable panels that can fluctuate in a fixed angle. The waves interact with the panels generating an alternative motion which can be exploited to produce electricity. At the same time, the constraint movement imposed for the rotation of the panels is a barrier to the wave propagation phenomena, triggering the breaking in the downstream part of the device. So the wave energy will be dissipated obtaining a positive effect for the coastal protection. Currently, the efficiency and effectiveness of the system (WECPOS single module) has been studied by using numerical models. Using the FLOW-3D

  6. Hydroelectromechanical modelling of a piezoelectric wave energy converter

    Science.gov (United States)

    Renzi, E.

    2016-11-01

    We investigate the hydroelectromechanical-coupled dynamics of a piezoelectric wave energy converter. The converter is made of a flexible bimorph plate, clamped at its ends and forced to motion by incident ocean surface waves. The piezoceramic layers are connected in series and transform the elastic motion of the plate into useful electricity by means of the piezoelectric effect. By using a distributed-parameter analytical approach, we couple the linear piezoelectric constitutive equations for the plate with the potential-flow equations for the surface water waves. The resulting system of governing partial differential equations yields a new hydroelectromechanical dispersion relation, whose complex roots are determined with a numerical approach. The effect of the piezoelectric coupling in the hydroelastic domain generates a system of short- and long-crested weakly damped progressive waves travelling along the plate. We show that the short-crested flexural wave component gives a dominant contribution to the generated power. We determine the hydroelectromechanical resonant periods of the device, at which the power output is significant.

  7. Direct Drive Wave Energy Buoy – 33rd scale experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, Kenneth E. [Columbia Power Technologies, Inc.; Lenee-Bluhm, Pukha [Columbia Power Technologies, Inc.; Prudell, Joseph H. [Columbia Power Technologies, Inc.; Schacher, Alphonse A.; Hammagren, Erik J.; Zhang, Zhe [Columbia Power Technologies, Inc.

    2013-07-29

    Columbia Power Technologies (ColPwr) and Oregon State University (OSU) jointly conducted a series of tests in the Tsunami Wave Basin (TWB) at the O.H. Hinsdale Wave Research Laboratory (HWRL). These tests were run between November 2010 and February 2011. Models at 33rd scale representing Columbia Power’s Manta series Wave Energy Converter (WEC) were moored in configurations of one, three and five WEC arrays, with both regular waves and irregular seas generated. The primary research interest of ColPwr is the characterization of WEC response. The WEC response will be investigated with respect to power performance, range of motion and generator torque/speed statistics. The experimental results will be used to validate a numerical model. The primary research interests of OSU include an investigation into the effects of the WEC arrays on the near- and far-field wave propagation. This report focuses on the characterization of the response of a single WEC in isolation. To facilitate understanding of the commercial scale WEC, results will be presented as full scale equivalents.

  8. Investigation and Optimisation of a Discrete Fluid Power PTO-system for Wave Energy Converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard

    Patents on ocean wave energy dates back to 1799, however no wave energy converter (WEC) concept have a commercialised device. The cost of energy produced with wave energy converters is very high compared to traditional energy sources. Even when compared to energy from wind turbines wave energy...... investigation show how the wave climate naturally influence the optimal system configuration yielding maximal energy output, and how one may choose the system configuration based on the installation site. The switching manifold is the control element of the secondary controlled force system. The force...... needs cost reductions. Hence, next to political will, the main obstacle for a commercial break through of wave energy technology is the high cost of energy. Initiatives to lower costs are made in areas of minimising structural costs and increasing the energy production per device. Wave Star A/S has...

  9. Effects of Wave Energy Converter (WEC) Arrays on Wave, Current, and Sediment Circulation

    Science.gov (United States)

    Ruehl, K.; Roberts, J. D.; Jones, C.; Magalen, J.; James, S. C.

    2012-12-01

    The characterization of the physical environment and commensurate alteration of that environment due to Wave Energy Conversion (WEC) devices, or arrays of devices, must be understood to make informed device-performance predictions, specifications of hydrodynamic loads, and environmental evaluations of eco-system responses (e.g., changes to circulation patterns, sediment dynamics, and water quality). Hydrodynamic and sediment issues associated with performance of wave-energy devices will primarily be nearshore where WEC infrastructure (e.g., anchors, piles) are exposed to large forces from the surface-wave action and currents. Wave-energy devices will be subject to additional corrosion, fouling, and wear of moving parts caused by suspended sediments in the water column. The alteration of the circulation and sediment transport patterns may also alter local ecosystems through changes in benthic habitat, circulation patterns, or other environmental parameters. Sandia National Laboratories is developing tools and performing studies to quantitatively characterize the environments where WEC devices may be installed and to assess potential affects to hydrodynamics and local sediment transport. The primary tools are wave, hydrodynamic, and sediment transport models. To ensure confidence in the resulting evaluation of system-wide effects, the models are appropriately constrained and validated with measured data where available. An extension of the US EPA's EFDC code, SNL-EFDC, provides a suitable platform for modeling the necessary hydrodynamics;it has been modified to directly incorporate output from a SWAN wave model of the region. Model development and results are presented. In this work, a model is exercised for Monterey Bay, near Santa Cruz where a WEC array could be deployed. Santa Cruz is located on the northern coast of Monterey Bay, in Central California, USA. This site was selected for preliminary research due to the readily available historical hydrodynamic data

  10. Negative-energy waves in a magnetized, homogeneous plasma

    International Nuclear Information System (INIS)

    Correa-Restrepo, D.; Pfirsch, D.

    1991-09-01

    The general expression for the second wave energy of a Vlasov-Maxwell system derived by Morrison and Pfirsch is evaluated here for the case of a magnetized, homogeneous plasma. It is again shown that negative-energy waves (which could become nonlinearly unstable and cause anomalous transport) exist for any deviation from monotonicity and/or any (however small) anisotropy in the equilibrium distribution function of any of the particle species. The partly unexpected and particularly interesting feature of the results is that, contrary to the proof of Morrison and Pfirsch, no restricting condition has to be imposed on the perpendicular wave number k perpendicular to of the perturbation (i.e. large k perpendicular to is not required). Finite-gyroradius effects are therefore not expected to improve the situation. Anisotropy alone would, however, impose a restriction on k z , the parallel wave number, relating it to the gyroradius. As far as distribution functions with v z δf v (0) /δv z > 0 in some region of v-space are concerned, however, this result agrees with a result found by Pfirsch and Morrison within the framework of drift-kinetic theory. (orig.)

  11. CFD Simulations of Floating Point Absorber Wave Energy Converter Arrays Subjected to Regular Waves

    Directory of Open Access Journals (Sweden)

    Brecht Devolder

    2018-03-01

    Full Text Available In this paper we use the Computational Fluid Dynamics (CFD toolbox OpenFOAM to perform numerical simulations of multiple floating point absorber wave energy converters (WECs arranged in a geometrical array configuration inside a numerical wave tank (NWT. The two-phase Navier-Stokes fluid solver is coupled with a motion solver to simulate the hydrodynamic flow field around the WECs and the wave-induced rigid body heave motion of each WEC within the array. In this study, the numerical simulations of a single WEC unit are extended to multiple WECs and the complexity of modelling individual floating objects close to each other in an array layout is tackled. The NWT is validated for fluid-structure interaction (FSI simulations by using experimental measurements for an array of two, five and up to nine heaving WECs subjected to regular waves. The validation is achieved by using mathematical models to include frictional forces observed during the experimental tests. For all the simulations presented, a good agreement is found between the numerical and the experimental results for the WECs’ heave motions, the surge forces on the WECs and the perturbed wave field around the WECs. As a result, our coupled CFD–motion solver proves to be a suitable and accurate toolbox for the study of fluid-structure interaction problems of WEC arrays.

  12. Licensing and Environmental Issues of Wave Energy Projects

    DEFF Research Database (Denmark)

    Neumann, Frank; Tedd, James; Prado, Miguel

    2006-01-01

    a special standing or facilitated access to operating licenses due to their experimental character, the move of wave energy projects towards commercial applications implies complex procedures for obtaining licenses both with respect to the construction and deployment and operation phases, as well......The major non-technical barrier for large-scale wave energy implementation is the wide range of licensing issues and potential environmental concerns, in addition to significant National/regional differences in licensing procedures and permit requirements. Whereas some pilot plants have had...... as concerning ocean space use and environmental concerns. Despite recent efforts to streamline European EIA (Environmental Impact Assessment) in general, potential project developers are far from having a clear view of present and future requirements concerning these barriers on a trans-national level...

  13. Hydraulic power take-off for wave energy systems

    DEFF Research Database (Denmark)

    Christensen, Georg Kronborg

    2001-01-01

    Investigation and laboratory experiments with a hydraulic power conversion system for converting forces from a 2.5m diamter float to extract energy from seawaves. The test rig consists of a hydraulic wave simulator and a hydraulic point absorber. The absorber converts the incomming forces to a co...... to a continous rotation of an electric generator. The experiments document efficiencies and losses for the conversion process. The experiments are used for verification and update of a computer model.......Investigation and laboratory experiments with a hydraulic power conversion system for converting forces from a 2.5m diamter float to extract energy from seawaves. The test rig consists of a hydraulic wave simulator and a hydraulic point absorber. The absorber converts the incomming forces...

  14. Irradiation Testing of Ultrasonic Transducers

    International Nuclear Information System (INIS)

    Daw, J.; Rempe, J.; Palmer, J.; Tittmann, B.; Reinhardt, B.; Kohse, G.; Ramuhalli, P.; Montgomery, R.; Chien, H.T.; Villard, J.F.

    2013-06-01

    Ultrasonic technologies offer the potential for high accuracy and resolution in-pile measurement of numerous parameters, including geometry changes, temperature, crack initiation and growth, gas pressure and composition, and microstructural changes. Many Department of Energy-Office of Nuclear Energy (DOE-NE) programs are exploring the use of ultrasonic technologies to provide enhanced sensors for in-pile instrumentation during irradiation testing. For example, the ability of single, small diameter ultrasonic thermometers (UTs) to provide a temperature profile in candidate metallic and oxide fuel would provide much needed data for validating new fuel performance models. Other efforts include an ultrasonic technique to detect morphology changes (such as crack initiation and growth) and acoustic techniques to evaluate fission gas composition and pressure. These efforts are limited by the lack of existing knowledge of ultrasonic transducer material survivability under irradiation conditions. To address this need, the Pennsylvania State University (PSU) was awarded an Advanced Test Reactor National Scientific User Facility (ATR NSUF) project to evaluate promising magnetostrictive and piezoelectric transducer performance in the Massachusetts Institute of Technology Research Reactor (MITR) up to a fast fluence of at least 10 21 n/cm 2 (E> 0.1 MeV). This test will be an instrumented lead test; and real-time transducer performance data will be collected along with temperature and neutron and gamma flux data. By characterizing magnetostrictive and piezoelectric transducer survivability during irradiation, test results will enable the development of novel radiation tolerant ultrasonic sensors for use in Material and Test Reactors (MTRs). The current work bridges the gap between proven out-of-pile ultrasonic techniques and in-pile deployment of ultrasonic sensors by acquiring the data necessary to demonstrate the performance of ultrasonic transducers. (authors)

  15. Production of high energy neutrinos in relativistic supernova shock waves

    International Nuclear Information System (INIS)

    Weaver, T.A.

    1979-01-01

    The possibility of producing high-energy neutrinos (> approx. 10 GeV) in relativistic supernova shock waves is considered. It is shown that, even if the dissipation in such shocks is due to hard hadron--hadron collisions, the resulting flux of neutrinos is too small to be observed by currently envisioned detectors. The associated burst of hard γ-rays, however, may be detectable. 3 tables

  16. Energy from sea wave thrust and flow of water

    International Nuclear Information System (INIS)

    Sarkar, S.R.

    1996-01-01

    The area adjacent to the tidal rivers, irrigational canal, drain and also the seashore may be energized harnessing the energy from the flow/wave thrust by simply converting it into unidirectional rotating force to drive the generator for power generation. The existing plants are big in size and also fixed in place. A plant which will be a small/portable type is described. 7 refs., figs

  17. Control Strategies for Arrays of Wave Energy Devices

    OpenAIRE

    Westphalen, J; Bacelli, G; Balitsky, P; Ringwood, John

    2011-01-01

    In this paper, we investigate the differences between two control strategies for a two-device linear array of wave energy converters (WEC) for device spacings of 4 to 80 times the device diameter. The WECs operate in heave only and are controlled in real time. The control strategies, called the independent device and global array control, estimate the excitation forces and calculate the optimum vertical velocity trajectory and reactive power take off force to achieve the ...

  18. Predicting Output Power for Nearshore Wave Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Henock Mamo Deberneh

    2018-04-01

    Full Text Available Energy harvested from a Wave Energy Converter (WEC varies greatly with the location of its installation. Determining an optimal location that can result in maximum output power is therefore critical. In this paper, we present a novel approach to predicting the output power of a nearshore WEC by characterizing ocean waves using floating buoys. We monitored the movement of the buoys using an Arduino-based data collection module, including a gyro-accelerometer sensor and a wireless transceiver. The collected data were utilized to train and test prediction models. The models were developed using machine learning algorithms: SVM, RF and ANN. The results of the experiments showed that measurements from the data collection module can yield a reliable predictor of output power. Furthermore, we found that the predictors work better when the regressors are combined with a classifier. The accuracy of the proposed prediction model suggests that it could be extremely useful in both locating optimal placement for wave energy harvesting plants and designing the shape of the buoys used by them.

  19. Real-time Cure Monitoring of Composites Using a Guided wave-based System with High Temperature Piezoelectric Transducers, Fiber Bragg Gratings, and Phase-shifted Fiber Bragg Gratings

    Science.gov (United States)

    Hudson, Tyler Blake

    An in-process, in-situ cure monitoring technique utilizing a guided wave-based concept for carbon fiber reinforced polymer (CFRP) composites was investigated. Two automated cure monitoring systems using guided-wave ultrasonics were developed for characterizing the state of the cure. In the first system, surface mounted high-temperature piezoelectric transducer arrays were employed for actuation and sensing. The second system motivated by the success of the first system includes a single piezoelectric disc, bonded onto the surface of the composite for excitation; fiber Bragg gratings (FBGs) and/or phase-shifted fiber Bragg gratings (PSFBGs) were embedded in the composite for distributed cure sensing. Composite material properties (viscosity and degree of cure) evolved during cure of the panels fabricated from HexcelRTM IM7/8552 prepreg correlated well to the amplitude, time of arrival, and group velocity of the guided wave-based measurements during the cure cycle. In addition, key phase transitions (gelation and vitrification) were clearly identified from the experimental data during the same cure cycle. The material properties and phase transitions were validated using cure process modeling software (e.g., RAVENRTM). The high-temperature piezoelectric transducer array system demonstrated the feasibility of a guided wave-based, in-process, cure monitoring and provided the framework for defect detection during cure. Ultimately, this system could provide a traceable data stream for non-compliance investigations during serial production and perform closed-loop process control to maximize composite panel quality and consistency. In addition, this system could be deployed as a "smart" caul/tool plate to existing production lines without changing the design of the aircraft/structure. With the second system, strain in low frequency (quasi-static) and the guided wavebased signals in several hundred kilohertz range were measured almost simultaneously using the same FBG or PS

  20. Energy supply technologies. Hydro, ocean, wave and tidal

    Energy Technology Data Exchange (ETDEWEB)

    Fenhann, J.; Larsen, Hans [Risoe National Lab. - DTU (Denmark)

    2007-11-15

    This chapter presents an overview of current hydro, ocean, wave and tidal initiatives. Large hydro remains one of the lowest-cost generating technologies, although environmental constraints, resettlement impacts and the limited availability of sites have restricted further growth in many countries. Large hydro supplied 16 % of global electricity in 2004, down from 19 % a decade ago. Large hydro capacity totalled about 720 GW worldwide in 2004 and has grown historically at slightly more than 2 % annually. China installed nearly 8 GW of large hydro in 2004, taking the country to number one in terms of installed capacity (74 GW). With the completion of the Three Gorges Dam, China will add some 18.2 GW of hydro capacity in 2009. The socio-economic benefits of hydro include improved flood control and water supply. The socio-economic benefits of hydro include improved flood control and water supply. The socio-economic cost of hydro includes displacements and submergence. Further hydro can improve peak-capacity management. Ocean currents, some of which runs close to European coasts, carry a lot of kinetic energy. Part of this energy can be captured by sub-marine windmills and converted into electricity. These are more compact than the wind turbines used on land, simply because water is much denser than air. The main European countries with useful current power potential are France and the UK. Ocean tides are driven by the gravitational pull of the moon. With one high tide every 12 hours, a tidal power plant can operate for only four or five hours per cycle, so power from a single plant is intermittent. A suitably-designed tidal plant can, however, operate as a pimped storage system, using electricity during periods of low demand to store energy that can be recovered later. The only large, modern example of a tidal power plant is the 240 MW La Rance plant, built in France in the 1960s, which represents 91 % of the world tidal power capacity. Wave energy can be seen as

  1. Performance of a Tethered Point Wave-Energy Absorber in Regular and Irregular Waves

    KAUST Repository

    Bachynski, Erin E.; Young, Yin Lu; Yeung, Ronald W.

    2010-01-01

    The importance of the mooring system on the dynamic response of a point-absorber type ocean-wave energy converter (WEC) is investigated using a frequency-domain approach. In order to ensure the safety of WECs, careful consideration of the response and resonance frequencies in all motions must be evaluated, including the effects of the mooring system. In this study, a WEC floater with a closed, flat bottom is modeled as a rigid vertical cylinder tethered by elastic mooring lines. The WEC hydrodynamic added mass and damping are obtained using established potential-flow methods, with additional damping provided by the energy-extraction system. The results show that the response of the WEC, and the corresponding power takeoff, varies with the diameter-to-draft (D=T) ratio, mooring system stiffness, and mass distribution. For a given wave climate in Northern California, near San Francisco, the heave energy extraction is found to be best for a shallow WEC with a soft mooring system, compared to other systems that were examined. This result assumes a physical limit (cap) on the motion which is related to the significant wave height to draft ratio. Shallow draft designs, however, may experience excessive pitch motions and relatively larger viscous damping. In order to mitigate the pitch response, the pitch radius of gyration should be small and the center of mass should be low. Copyright © 2010 by ASME.

  2. Programming macro tree transducers

    DEFF Research Database (Denmark)

    Bahr, Patrick; Day, Laurence E.

    2013-01-01

    transducers can be concisely represented in Haskell, and demonstrate the benefits of utilising such an approach with a number of examples. In particular, tree transducers afford a modular programming style as they can be easily composed and manipulated. Our Haskell representation generalises the original...

  3. Crossflow force transducer

    International Nuclear Information System (INIS)

    Mulcahy, T.M.

    1982-05-01

    A force transducer for measuring lift and drag coefficients for a circular cylinder in turbulent water flow is presented. In addition to describing the actual design and construction of the strain-gauged force- ring based transducer, requirements for obtained valid fluid force test data are discussed, and pertinent flow test experience is related

  4. Hydraulic evaluation of the Crest Wing wave energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Kofoed, J.P.; Antonishen, M.

    2008-09-15

    The Crest Wing Wave Energy Converter is currently being developed by Henning Pilgaard, of WaveEnergyFyn, Denmark. It is meant to act like a carpet on the water, conforming to the shape of each wave and using that movement to generate power. The thought of making a WEC that acts like a carpet on top of the waves is not new; ongoing or past projects such as the Pelamis and Cockerel Raft were designed with this thought in mind. The real difference with the Crest Wing is that it has skirt drafts, that extend down into the water and create suction; this increases the effective mass of the WEC while minimizing the material use. Special attention was given to the design of the first and last floaters as they are meant to act as a smooth transition between wave and machine. Their purpose is to make sure that no air gets under the two middle floaters so that suction is not broken and the device continues to function well. In summary the Crest Wing functions and is able to produce power with a good overall efficiency. The configuration with relative reference PTO (Power Take Off) is superior. It has not been proven that the idea of mounting skirts on the floaters is leading to a better performance. Thus, the study leads to the conclusion that the idea of making a simple hinged raft type device is good, and it is likely that the construction cost for a device of this type can be kept down. However, the study also leaves the chance that some limited draft of skirts in combination with inlet/outlet devices, could prove beneficial. In case of further testing on this device, an effort should be made to design and construct a more easily and accurately controlled PTO model in the test setup. This could greatly improve the quality of the output of such tests. (ln)

  5. Wave-to-wire Modelling of Wave Energy Converters : Critical Assessment, Developments and Applicability for Economical Optimisation

    DEFF Research Database (Denmark)

    Ferri, Francesco

    The idea to use the motion of a wavy sea surface to produce electricity was investigate in the seventies, in a time when the earliest wave energy converters were conceived and developed. But nowadays still none of the patented devices reached a commercial stage. Wave energy is a large, mostly unt...

  6. Modeling of ultrasound transducers

    DEFF Research Database (Denmark)

    Bæk, David

    This Ph.D. dissertation addresses ultrasound transducer modeling for medical ultrasound imaging and combines the modeling with the ultrasound simulation program Field II. The project firstly presents two new models for spatial impulse responses (SIR)s to a rectangular elevation focused transducer...... (REFT) and to a convex rectangular elevation focused transducer (CREFT). These models are solvable on an analog time scale and give exact smooth solutions to the Rayleigh integral. The REFT model exhibits a root mean square (RMS) error relative to Field II predictions of 0.41 % at 3400 MHz, and 1.......37 % at 100MHz. The CREFT model exhibits a RMS deviation of 0.01 % relative to the exact numerical solution on a CREFT transducer. A convex non-elevation focused, a REFT, and a linear flat transducer are shown to be covered with the CREFT model as well. Pressure pulses calculated with a one...

  7. Efficiency of a gyroscopic device for conversion of mechanical wave energy to electrical energy

    DEFF Research Database (Denmark)

    Carlsen, Martin; Darula, Radoslav; Gravesen, Jens

    2011-01-01

    We consider a recently proposed gyroscopic device for conversion of mechanical ocean wave energy to electrical energy. Two models of the device derived from standard engineering mechanics from the literature are analysed, and a model is derived from analytical mechanics considerations. From...... these models, estimates of the power production, eciency, forces and moments are made. We nd that it is possible to extract a signicant amount of energy from an ocean wave using the described device. Further studies are required for a full treatment of the device....

  8. Influence of the α-, β- and γ-subunits of the energy-transducing adenosine triphosphatase from Micrococcus lysodeikticus in the immunochemical properties of the protein and in their reconstitution studied by a radioimmunoassay method

    International Nuclear Information System (INIS)

    Larraga, V.; Mollinedo, F.; Rubio, N.; Munoz, E.

    1981-01-01

    A sensitive radioimmunoassay was developed for the energy-transducing adenosine triphosphatase (F 1 -ATPase, EC 3.6.1.3) of Micrococcus lysodeikticus and the assay was extended to the α-, β- and γ-subunits of the enzyme. These subunits were isolated and cross-reactions studied. (author)

  9. Influence of the. cap alpha. -,. beta. -, and. gamma. -subunits of the energy-transducing adenosine triphosphatase from Micrococcus lysodeikticus in the immunochemical properties of the protein and in their reconstitution studied by a radioimmunoassay method

    Energy Technology Data Exchange (ETDEWEB)

    Larraga, V; Mollinedo, F; Rubio, N; Munoz, E [Unidad de Biomembranas, Instituto de Inmunologia y Biologia Microbiana, Madrid (Spain)

    1981-03-01

    A sensitive radioimmunoassay was developed for the energy-transducing adenosine triphosphatase (F/sub 1/-ATPase, EC 3.6.1.3) of Micrococcus lysodeikticus and the assay was extended to the ..cap alpha..-, ..beta..-, and ..gamma..-subunits of the enzyme. These subunits were isolated and cross-reactions studied.

  10. Guided acoustic wave inspection system

    Science.gov (United States)

    Chinn, Diane J.

    2004-10-05

    A system for inspecting a conduit for undesirable characteristics. A transducer system induces guided acoustic waves onto said conduit. The transducer system detects the undesirable characteristics of the conduit by receiving guided acoustic waves that contain information about the undesirable characteristics. The conduit has at least two sides and the transducer system utilizes flexural modes of propagation to provide inspection using access from only the one side of the conduit. Cracking is detected with pulse-echo testing using one transducer to both send and receive the guided acoustic waves. Thinning is detected in through-transmission testing where one transducer sends and another transducer receives the guided acoustic waves.

  11. Oscillatory Energy Exchange Between Waves Coupled by a Dynamic Artificial Crystal

    OpenAIRE

    Karenowska, Alexy D.; Tiberkevich, Vasil S.; Chumak, Andrii V.; Serga, Alexander A.; Gregg, John F.; Slavin, Andrei N.; Hillebrands, Burkard

    2011-01-01

    We describe a general mechanism of controllable energy exchange between waves propagating in a dynamic artificial crystal. We show that if a spatial periodicity is temporarily imposed on the transmission properties of a wave-carrying medium whilst a wave is inside, this wave is coupled to a secondary counter-propagating wave and energy oscillates between the two. The oscillation frequency is determined by the width of the spectral band gap created by the periodicity and the frequency differen...

  12. Energy scavenging system by acoustic wave and integrated wireless communication

    Science.gov (United States)

    Kim, Albert

    The purpose of the project was developing an energy-scavenging device for other bio implantable devices. Researchers and scientist have studied energy scavenging method because of the limitation of traditional power source, especially for bio-implantable devices. In this research, piezoelectric power generator that activates by acoustic wave, or music was developed. Follow by power generator, a wireless communication also integrated with the device for monitoring the power generation. The Lead Zirconate Titanate (PZT) bimorph cantilever with a proof mass at the free end tip was studied to convert acoustic wave to power. The music or acoustic wave played through a speaker to vibrate piezoelectric power generator. The LC circuit integrated with the piezoelectric material for purpose of wireless monitoring power generation. However, wireless monitoring can be used as wireless power transmission, which means the signal received via wireless communication also can be used for power for other devices. Size of 74 by 7 by 7cm device could generate and transmit 100mVp from 70 mm distance away with electrical resonant frequency at 420.2 kHz..

  13. Pulse energy evolution for high-resolution Lamb wave inspection

    International Nuclear Information System (INIS)

    Hua, Jiadong; Zeng, Liang; Gao, Fei; Lin, Jing

    2015-01-01

    Generally, tone burst excitation methods are used to reduce the effect of dispersion in Lamb wave inspection. In addition, algorithms for dispersion compensation are required to simplify responses, especially in long-range inspection. However, the resolution is always limited by the time duration of tone burst excitation. A pulse energy evolution method is established to overcome this limitation. In this method, a broadband signal with a long time (e.g. a chirp, white noise signal, or a pseudo-random sequence) is used as excitation to actuate Lamb waves. First of all, pulse compression is employed to estimate system impulse response with a high signal-to-noise ratio. Then, dispersion compensation is applied repeatedly with systemically varied compensation distances, obtaining a series of compensated signals. In these signals, amplitude (or energy) evolution associated with the change of compensation distance is utilized to estimate the actual propagation distance of the interested wave packet. Finally, the defect position is detected by an imaging algorithm. Several experiments are given to validate the proposed method. (paper)

  14. Floating attenuator wave energy device: Wavegen HYDRA project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This report describes research funded by the Department of Trade and Industry (DTI) into the feasibility of developing and constructing a floating attenuator wave energy device known as HYDRA following initial studies by Wavegen. HYDRA is a floating externally tensioned articulated raft wave energy generator based on work by Professor FJM Farley and colleagues during the 1980s. The project's first four work tasks confirmed the theoretical potential of the device but also highlighted significant practical problems in translating that potential into a viable design. It was therefore decided not to proceed further, i.e. not to construct and test a prototype device. The report provides a general description of the device and describes the results of the initial analysis and the first series of model tests. It then discusses device design and component testing and explains the methodology for determining device performance at a particular site and mathematical modelling of a one-third scale device. To help future research and development programmes, the report emphasises the generic problems associated with the development of wave devices.

  15. Relationship between wave energy and free energy from pickup ions in the Comet Halley environment

    Science.gov (United States)

    Huddleston, D. E.; Johnstone, A. D.

    1992-01-01

    The free energy available from the implanted heavy ion population at Comet Halley is calculated by assuming that the initial unstable velocity space ring distribution of the ions evolves toward a bispherical shell. Ultimately this free energy adds to the turbulence in the solar wind. Upstream and downstream free energies are obtained separately for the conditions observed along the Giotto spacecraft trajectory. The results indicate that the waves are mostly upstream propagating in the solar wind frame. The total free energy density always exceeds the measured wave energy density because, as expected in the nonlinear process of ion scattering, the available energy is not all immediately released. An estimate of the amount which has been released can be obtained from the measured oxygen ion distributions and again it exceeds that observed. The theoretical analysis is extended to calculate the k spectrum of the cometary-ion-generated turbulence.

  16. Wind, Wave, and Tidal Energy Without Power Conditioning

    Science.gov (United States)

    Jones, Jack A.

    2013-01-01

    Most present wind, wave, and tidal energy systems require expensive power conditioning systems that reduce overall efficiency. This new design eliminates power conditioning all, or nearly all, of the time. Wind, wave, and tidal energy systems can transmit their energy to pumps that send high-pressure fluid to a central power production area. The central power production area can consist of a series of hydraulic generators. The hydraulic generators can be variable displacement generators such that the RPM, and thus the voltage, remains constant, eliminating the need for further power conditioning. A series of wind blades is attached to a series of radial piston pumps, which pump fluid to a series of axial piston motors attached to generators. As the wind is reduced, the amount of energy is reduced, and the number of active hydraulic generators can be reduced to maintain a nearly constant RPM. If the axial piston motors have variable displacement, an exact RPM can be maintained for all, or nearly all, wind speeds. Analyses have been performed that show over 20% performance improvements with this technique over conventional wind turbines

  17. Resonant acoustic transducer system for a well drilling string

    Science.gov (United States)

    Nardi, Anthony P.

    1981-01-01

    For use in transmitting acoustic waves propated along a well drilling string, a piezoelectric transducer is provided operating in the relatively low loss acoustic propagation range of the well drilling string. The efficiently coupled transmitting transducer incorporates a mass-spring-piezoelectric transmitter combination permitting a resonant operation in the desired low frequency range.

  18. Resonant transducers for solid-state plasma density modulation

    Energy Technology Data Exchange (ETDEWEB)

    Hallock, Gary A., E-mail: hallock@ece.utexas.edu [The University of Texas at Austin, Austin, Texas 78701 (United States); Meier, Mark A., E-mail: mark.a.meier@exxonmobil.com [ExxonMobil Upstream Research Company, Houston, Texas 77389 (United States)

    2016-04-15

    We have developed transducers capable of modulating the plasma density and plasma density gradients in indium antimonide. These transducers make use of piezoelectric drivers to excite acoustic pressure resonance at 3λ/2, generating large amplitude standing waves and plasma density modulations. The plasma density has been directly measured using a laser diagnostic. A layered media model shows good agreement with the experimental measurements.

  19. Reference Model 6 (RM6): Oscillating Wave Energy Converter.

    Energy Technology Data Exchange (ETDEWEB)

    Bull, Diana L; Smith, Chris; Jenne, Dale Scott; Jacob, Paul; Copping, Andrea; Willits, Steve; Fontaine, Arnold; Brefort, Dorian; Gordon, Margaret Ellen; Copeland, Robert; Jepsen, Richard Alan

    2014-10-01

    This report is an addendum to SAND2013-9040: Methodology for Design and Economic Analysis of Marine Energy Conversion (MEC) Technologies. This report describes an Oscillating Water Column Wave Energy Converter reference model design in a complementary manner to Reference Models 1-4 contained in the above report. In this report, a conceptual design for an Oscillating Water Column Wave Energy Converter (WEC) device appropriate for the modeled reference resource site was identified, and a detailed backward bent duct buoy (BBDB) device design was developed using a combination of numerical modeling tools and scaled physical models. Our team used the methodology in SAND2013-9040 for the economic analysis that included costs for designing, manufacturing, deploying, and operating commercial-scale MEC arrays, up to 100 devices. The methodology was applied to identify key cost drivers and to estimate levelized cost of energy (LCOE) for this RM6 Oscillating Water Column device in dollars per kilowatt-hour ($/kWh). Although many costs were difficult to estimate at this time due to the lack of operational experience, the main contribution of this work was to disseminate a detailed set of methodologies and models that allow for an initial cost analysis of this emerging technology. This project is sponsored by the U.S. Department of Energy's (DOE) Wind and Water Power Technologies Program Office (WWPTO), within the Office of Energy Efficiency & Renewable Energy (EERE). Sandia National Laboratories, the lead in this effort, collaborated with partners from National Laboratories, industry, and universities to design and test this reference model.

  20. Assessment of the Joint Development Potential of Wave and Wind Energy in the South China Sea

    Directory of Open Access Journals (Sweden)

    Yong Wan

    2018-02-01

    Full Text Available The South China Sea is a major shipping hub between the West Pacific and Indian Oceans. In this region, the demand for energy is enormous, both for residents’ daily lives and for economic development. Wave energy and wind energy are two major clean and low-cost ocean sources of renewable energy. The reasonable development and utilization of these energy sources can provide a stable energy supply for coastal cities and remote islands of China. Before wave energy and wind energy development, however, we must assess the potential of each of these sources. Based on high-resolution and high-accuracy wave field data and wind field data obtained by ERA-Interim reanalysis for the recent 38-year period from 1979–2016, the joint development potential of wave energy and wind energy was assessed in detail for offshore and nearshore areas in the South China Sea. Based on potential installed capacity, the results revealed three promising areas for the joint development of nearshore wave energy and wind energy, including the Taiwan Strait, Luzon Strait and the sea southeast of the Indo-China Peninsula. For these three dominant areas (key stations, the directionality of wave energy and wind energy propagation were good in various seasons; the dominant wave conditions and the dominant wind conditions were the same, which is advantageous for the joint development of wave and wind energy. Existing well-known wave energy converters (WECs are not suitable for wave energy development in the areas of interest. Therefore, we must consider the distributions of wave conditions and develop more suitable WECs for these areas. The economic and environmental benefits of the joint development of wave and wind energy are high in these promising areas. The results described in this paper can provide references for the joint development of wave and wind energy in the South China Sea.

  1. Wave energy: technology transfer and generic R and D recommendations

    Energy Technology Data Exchange (ETDEWEB)

    Scarr, D.; Kollek, R.; Collier, D.

    2001-07-01

    Arup have reviewed the status of the industry by way of individual interviews with all teams currently active in the UK as well as by research of international activities in the area. A preliminary technology workshop was organised to identify and discuss key issues with the teams and other industries. The following technology areas were discussed: (1) Regulatory Environment, HSE, Design Codes and Verification; (2) Construction Methods and Project Cost Estimation; (3) Marine Operations; (4) Mooring Systems; (5) Operations and Maintenance; (6) Materials; (7) Hydraulic Systems; (8) Pneumatic Systems; (9) Subsea Cables and Connectors; (10) Control Systems; (11) Power Quality and Grid Connection. The recommendations were made bearing in mind the proposed programme of Wave Energy Converter (WEC) prototype and power station development and the perceived need for further cost reductions. The major conclusions of the study were: The Wave Energy Industry is poorly co-ordinated. At present, all teams are working independently and commercial considerations force them to keep their ideas secret. There remains a lack of investor confidence and hence industrial support for the industry. Teams tend to be relatively small working out of University Departments or SMEs with some industrial backing. No major technological barriers to the development of Wave Energy Prototypes have been identified. All the issues raised under design, construction, deployment and operation can be addressed by transfer of technology from other industries, especially the offshore industry. However, costs, risks and approvals will need to be addressed. However, some technology gaps have been identified, notably in the areas of mooring and cable connections detailing, hydraulic machines and grid connection and energy storage. (author)

  2. Technical Submission Form: Technical Specification of a Wave Energy Farm.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Kim Nielsen; Ben Kennedy; Bull, Diana L; Costello, Ronan Patrick; Jochem Weber

    2017-04-01

    The Wave - SPARC project developed the Technology Performance Level (TPL) assessment procedure based on a rigorous Systems Engineering exercise. The TPL assessment allows a whole system evaluation of Wave Energy Conversion Technology by measuring it against the requirements determined through the Systems Engineering exercise. The TPL assessment is intended to be useful in technology evaluation; in technology innovation; in allocation of public or priva te investment, and; in making equipment purchasing decisions. This Technical Submission Form (TSF) serves the purpose of collecting relevant and complete information, in a technology agnostic way, to allow TPL assessment s to be made by third party assessor s. The intended usage of this document is that the organization or people that are performing the role of developers or promoters of a particular technology will use this form to provide the information necessary for the organization or people who are perf orming the assessor role to use the TPL assessment.

  3. Holocene reef development where wave energy reduces accommodation

    Science.gov (United States)

    Grossman, Eric E.; Fletcher, Charles H.

    2004-01-01

    Analyses of 32 drill cores obtained from the windward reef of Kailua Bay, Oahu, Hawaii, indicate that high wave energy significantly reduced accommodation space for reef development in the Holocene and produced variable architecture because of the combined influence of sea-level history and wave exposure over a complex antecedent topography. A paleostream valley within the late Pleistocene insular limestone shelf provided accommodation space for more than 11 m of vertical accretion since sea level flooded the bay 8000 yr BP. Virtually no net accretion (pile-up of fore-reef-derived rubble (rudstone) and sparse bindstone, and (3) a final stage of catch-up bindstone accretion in depths > 6 m. Coral framestone accreted at rates of 2.5-6.0 mm/yr in water depths > 11 m during the early Holocene; it abruptly terminated at ~4500 yr BP because of wave scour as sea level stabilized. More than 4 m of rudstone derived from the upper fore reef accreted at depths of 6 to 13 m below sea level between 4000 and 1500 yr BP coincident with late Holocene relative sea-level fall. Variations in the thickness, composition, and age of these reef facies across spatial scales of 10-1000 m within Kailua Bay illustrate the importance of antecedent topography and wave-related stress in reducing accommodation space for reef development set by sea level. Although accommodation space of 6 to 17 m has existed through most of the Holocene, the Kailua reef has been unable to catch up to sea level because of persistent high wave stress.

  4. Modelling and Testing of Wave Dragon Wave Energy Converter Towards Full Scale Deployment

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano

    -commercial stage in which it has proven difficult to secure the necessary funding for the deployment of a full-scale demonstrator unit. The work presented aims at easing this process, by increasing public and scientific knowledge of the device, as well as by showing the latest progress in its development. Research....... This is mainly due to the development of an updated overtopping model specifically suited to Wave Dragon, which allows greater quality to predictions of the primary energy absorption of the device compared to previous versions. At the same time an equitable approach has been described and used in the performance......, the research has also provided a deeper insight into the physics of the overtopping process by individually assessing the influence of related device configuration and wave features, which goes beyond the present application and may be used for other overtopping WECs as well. Comprehensive analysis...

  5. Transformation of Elastic Wave Energy to the Energy of Motion of Bodies

    Science.gov (United States)

    Vesnitskiĭ, A. I.; Lisenkova, E. E.

    2002-01-01

    The motion of a body along an elastic guide under the effect of an incident wave is considered. An equation describing the longitudinal motion of a body along an arbitrary guide is derived from the laws governing the energy and momentum variations for the case when the incident wave generates a single reflected wave. The equations that describe the motion of a body along a string and along a beam corresponding to the Bernoulli-Euler model are considered as examples. The process of the body acceleration along a beam of the aforementioned type is investigated. For the subcritical velocities, the law governing the motion of the body and the ratio of the kinetic energy variation to the energy supplied to the body are determined.

  6. Wave energy resource assessment for the Indian shelf seas

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Anoop, T.R.

    of the southeastern USA. Renewable Energy 2009; 34: 2197-205. [21] Lenee-Bluhm P, Paasch R, Özkan-Haller HT. Characterizing the wave energy resource of the US Pacific Northwest, Renewable Energy 2011; 36; 2106–2119. [22] Gunn K, Stock-Williams C. Quantifying... 17 18 19 0 1 2 3 4 M on th ly v ar ia bi lit y in de x (a) (b) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Location 2 3 4 5 R at io o f m ax im um to m ea n w av e he ig ht Figure 7. Variation of (a) monthly variability index and (b...

  7. Energy scaling of terahertz-wave parametric sources.

    Science.gov (United States)

    Tang, Guanqi; Cong, Zhenhua; Qin, Zengguang; Zhang, Xingyu; Wang, Weitao; Wu, Dong; Li, Ning; Fu, Qiang; Lu, Qingming; Zhang, Shaojun

    2015-02-23

    Terahertz-wave parametric oscillators (TPOs) have advantages of room temperature operation, wide tunable range, narrow line-width, good coherence. They have also disadvantage of small pulse energy. In this paper, several factors preventing TPOs from generating high-energy THz pulses and the corresponding solutions are analyzed. A scheme to generate high-energy THz pulses by using the combination of a TPO and a Stokes-pulse-injected terahertz-wave parametric generator (spi-TPG) is proposed and demonstrated. A TPO is used as a source to generate a seed pulse for the surface-emitted spi-TPG. The time delay between the pump and Stokes pulses is adjusted to guarantee they have good temporal overlap. The pump pulses have a large pulse energy and a large beam size. The Stokes beam is enlarged to make its size be larger than the pump beam size to have a large effective interaction volume. The experimental results show that the generated THz pulse energy from the spi-TPG is 1.8 times as large as that obtained from the TPO for the same pumping pulse energy density of 0.90 J/cm(2) and the same pumping beam size of 3.0 mm. When the pumping beam sizes are 5.0 and 7.0 mm, the enhancement times are 3.7 and 7.5, respectively. The spi-TPG here is similar to a difference frequency generator; it can also be used as a Stokes pulse amplifier.

  8. From Bunsen Burners to Fuel Cells: Invoking Energy Transducers to Exemplify "Paths" and Unify the Energy-Related Concepts of Thermochemistry and Thermodynamics

    Science.gov (United States)

    Hladky, Paul W.

    2009-01-01

    The conversion of chemical energy entirely into thermal energy by Bunsen burners and into thermal energy and electrical energy by fuel cells of varying efficiencies illustrates different paths by which a chemical reaction can occur. Using the efficiency of producing electrical energy as a path label allows all of the energy-related quantities to…

  9. Advanced, High Power, Next Scale, Wave Energy Conversion Device

    Energy Technology Data Exchange (ETDEWEB)

    Mekhiche, Mike [Principal Investigator; Dufera, Hiz [Project Manager; Montagna, Deb [Business Point of Contact

    2012-10-29

    The project conducted under DOE contract DE‐EE0002649 is defined as the Advanced, High Power, Next Scale, Wave Energy Converter. The overall project is split into a seven‐stage, gated development program. The work conducted under the DOE contract is OPT Stage Gate III work and a portion of Stage Gate IV work of the seven stage product development process. The project effort includes Full Concept Design & Prototype Assembly Testing building on our existing PowerBuoy technology to deliver a device with much increased power delivery. Scaling‐up from 150kW to 500kW power generating capacity required changes in the PowerBuoy design that addressed cost reduction and mass manufacturing by implementing a Design for Manufacturing (DFM) approach. The design changes also focused on reducing PowerBuoy Installation, Operation and Maintenance (IO&M) costs which are essential to reducing the overall cost of energy. In this design, changes to the core PowerBuoy technology were implemented to increase capability and reduce both CAPEX and OPEX costs. OPT conceptually envisaged moving from a floating structure to a seabed structure. The design change from a floating structure to seabed structure would provide the implementation of stroke‐ unlimited Power Take‐Off (PTO) which has a potential to provide significant power delivery improvement and transform the wave energy industry if proven feasible.

  10. Analysis of the impacts of Wave Energy Converter arrays on the nearshore wave climate in the Pacific Northwest

    Science.gov (United States)

    O'Dea, A.; Haller, M. C.

    2013-12-01

    As concerns over the use of fossil fuels increase, more and more effort is being put into the search for renewable and reliable sources of energy. Developments in ocean technologies have made the extraction of wave energy a promising alternative. Commercial exploitation of wave energy would require the deployment of arrays of Wave Energy Converters (WECs) that include several to hundreds of individual devices. Interactions between WECs and ocean waves result in both near-field and far-field changes in the incident wave field, including a significant decrease in wave height and a redirection of waves in the lee of the array, referred to as the wave shadow. Nearshore wave height and direction are directly related to the wave radiation stresses that drive longshore currents, rip currents and nearshore sediment transport, which suggests that significant far-field changes in the wave field due to WEC arrays could have an impact on littoral processes. The goal of this study is to investigate the changes in nearshore wave conditions and radiation stress forcing as a result of an offshore array of point-absorber type WECs using a nested SWAN model, and to determine how array size, configuration, spacing and distance from shore influence these changes. The two sites of interest are the Northwest National Marine Renewable Energy Center (NNMREC) test sites off the coast of Newport Oregon, the North Energy Test Site (NETS) and the South Energy Test Site (SETS). NETS and SETS are permitted wave energy test sites located approximately 4 km and 10 km offshore, respectively. Twenty array configurations are simulated, including 5, 10, 25, 50 and 100 devices in two and three staggered rows in both closely spaced (three times the WEC diameter) and widely spaced (ten times the WEC diameter) arrays. Daily offshore wave spectra are obtained from a regional WAVEWATCH III hindcast for 2011, which are then propagated across the continental shelf using SWAN. Arrays are represented in SWAN

  11. Model Predictive Control of Buoy Type Wave Energy Converter

    DEFF Research Database (Denmark)

    Soltani, Mohsen N.; Sichani, Mahdi T.; Mirzaei, Mahmood

    2014-01-01

    by forcing this condition. In the paper the theoretical framework for this principal is shown. The optimal controller requires information of the sea state for infinite horizon which is not applicable. Model Predictive Controllers (MPC) can have finite horizon which crosses out this requirement....... This approach is then taken into account and an MPC controller is designed for a model wave energy converter and implemented on a numerical example. Further, the power outtake of this controller is compared to the optimal controller as an indicator of the performance of the designed controller....

  12. An analytic distorted wave approximation for intermediate energy proton scattering

    International Nuclear Information System (INIS)

    Di Marzio, F.; Amos, K.

    1982-01-01

    An analytic Distorted Wave approximation has been developed for use in analyses of intermediate energy proton inelastic scattering from nuclei. Applications are made to analyse 402 and 800 MeV data from the isoscalar and isovector 1 + and 2 + states in 12 C and to the 800 MeV data from the excitation of the 2 - (8.88MeV) state in 16 O. Comparisons of predictions made using different model two-nucleon t-matrices and different models of nuclear structure are given

  13. Smart transducer with radiomodem

    Science.gov (United States)

    Pugach, V. N.; Voronin, E. L.

    2018-04-01

    Systems for measuring different parameters enabling metering and wireless data transmission are an urgent problem in the industry. One of the most promising solutions is the developments of metering instruments enabling radio-link and GSM data transmission. The article describes a transducer operating with temperature sensors of different types as well as with the sensors of other physical values with the output signal represented as current or voltage with subsequent measurement data transmission from the transducer to the computer via radio-link. The article provides transducer measurement accuracy check. The work confirmed the claimed temperature measurement accuracy, noted a stable data transmission via radio link and convenience of work with the transducer and software.

  14. Marine Hydrokinetic Energy Site Identification and Ranking Methodology Part I: Wave Energy

    Energy Technology Data Exchange (ETDEWEB)

    Kilcher, Levi [National Renewable Energy Lab. (NREL), Golden, CO (United States); Thresher, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-10-01

    Marine hydrokinetic energy is a promising and growing piece of the renewable energy sector that offers high predictability and additional energy sources for a diversified energy economy. This report investigates the market opportunities for wave energy along the U.S. coastlines. It is part one of a two-part investigation into the United State's two largest marine hydrokinetic resources (wave and tidal). Wave energy technology is still an emerging form of renewable energy for which large-scale, grid-connected project costs are currently poorly defined. Ideally, device designers would like to know the resource conditions at economical project sites so they can optimize device designs. On the other hand, project developers need detailed device cost data to identify sites where projects are economical. That is, device design and siting are, to some extent, a coupled problem. This work describes a methodology for identifying likely deployment locations based on a set of criteria that wave energy experts in industry, academia, and national laboratories agree are likely to be important factors for all technology types. This work groups the data for the six criteria into 'locales' that are defined as the smaller of either the local transmission grid or a state boundary. The former applies to U.S. islands (e.g., Hawaii, American Samoa) and rural villages (e.g., in Alaska); the latter applies to states in the contiguous United States. These data are then scored from 0 to 10 according to scoring functions that were developed with input from wave energy industry and academic experts. The scores are aggregated using a simple product method that includes a weighting factor for each criterion. This work presents two weighting scenarios: a long-term scenario that does not include energy price (weighted zero) and a near term scenario that includes energy price. The aggregated scores are then used to produce ranked lists of likely deployment locales. In both scenarios

  15. Impact of Generator Stroke Length on Energy Production for a Direct Drive Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Yue Hong

    2016-09-01

    Full Text Available The Lysekil wave energy converter (WEC, developed by the wave energy research group of Uppsala University, has evolved through a variety of mechanical designs since the first prototype was installed in 2006. The hundreds of engineering decisions made throughout the design processes have been based on a combination of theory, know-how from previous experiments, and educated guesses. One key parameter in the design of the WECs linear generator is the stroke length. A long stroke requires a taller WEC with associated economical and mechanical challenges, but a short stroke limits the power production. The 2-m stroke of the current WECs has been an educated guess for the Swedish wave climate, though the consequences of this choice on energy absorption have not been studied. When the WEC technology is considered for international waters, with larger waves and challenges of energy absorption and survivability, the subject of stroke length becomes even more relevant. This paper studies the impact of generator stroke length on energy absorption for three sites off the coasts of Sweden, Chile and Scotland. 2-m, 4-m, and unlimited stroke are considered. Power matrices for the studied WEC prototype are presented for each of the studied stroke lengths. Presented results quantify the losses incurred by a limited stroke. The results indicate that a 2-m stroke length is likely to be a good choice for Sweden, but 4-m is likely to be necessary in more energetic international waters.

  16. Reference Model 5 (RM5): Oscillating Surge Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y. H. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Jenne, D. S. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Thresher, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Copping, A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Geerlofs, S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hanna, L. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-01-01

    This report is an addendum to SAND2013-9040: Methodology for Design and Economic Analysis of Marine Energy Conversion (MEC) Technologies. This report describes an Oscillating Water Column Wave Energy Converter (OSWEC) reference model design in a complementary manner to Reference Models 1-4 contained in the above report. A conceptual design for a taut moored oscillating surge wave energy converter was developed. The design had an annual electrical power of 108 kilowatts (kW), rated power of 360 kW, and intended deployment at water depths between 50 m and 100 m. The study includes structural analysis, power output estimation, a hydraulic power conversion chain system, and mooring designs. The results were used to estimate device capital cost and annual operation and maintenance costs. The device performance and costs were used for the economic analysis, following the methodology presented in SAND2013-9040 that included costs for designing, manufacturing, deploying, and operating commercial-scale MEC arrays up to 100 devices. The levelized cost of energy estimated for the Reference Model 5 OSWEC, presented in this report, was for a single device and arrays of 10, 50, and 100 units, and it enabled the economic analysis to account for cost reductions associated with economies of scale. The baseline commercial levelized cost of energy estimate for the Reference Model 5 device in an array comprised of 10 units is $1.44/kilowatt-hour (kWh), and the value drops to approximately $0.69/kWh for an array of 100 units.

  17. A method for determining losses in magnetostrictive transducers

    Science.gov (United States)

    Krysin, V. N.; Ketlerov, A. S.

    A method for estimating energy losses in magnetostrictive transducers is described. It is shown that domain remagnetization is responsible for the greatest energy loss in magnetostrictive transducers. Energy losses associated with Foucault currents and Joule heat are an order of magnitude less.

  18. Numerical Forecasting Experiment of the Wave Energy Resource in the China Sea

    Directory of Open Access Journals (Sweden)

    Chong Wei Zheng

    2016-01-01

    Full Text Available The short-term forecasting of wave energy is important to provide guidance for the electric power operation and power transmission system and to enhance the efficiency of energy capture and conversion. This study produced a numerical forecasting experiment of the China Sea wave energy using WAVEWATCH-III (WW3, the latest version 4.18 wave model driven by T213 (WW3-T213 and T639 (WW3-T639 wind data separately. Then the WW3-T213 and WW3-T639 were verified and compared to build a short-term wave energy forecasting structure suited for the China Sea. Considering the value of wave power density (WPD, “wave energy rose,” daily and weekly total storage and effective storage of wave energy, this study also designed a series of short-term wave energy forecasting productions. Results show that both the WW3-T213 and WW3-T639 exhibit a good skill on the numerical forecasting of the China Sea WPD, while the result of WW3-T639 is much better. Judging from WPD and daily and weekly total storage and effective storage of wave energy, great wave energy caused by cold airs was found. As there are relatively frequent cold airs in winter, early spring, and later autumn in the China Sea and the surrounding waters, abundant wave energy ensues.

  19. Networks of triboelectric nanogenerators for harvesting water wave energy: a potential approach toward blue energy.

    Science.gov (United States)

    Chen, Jun; Yang, Jin; Li, Zhaoling; Fan, Xing; Zi, Yunlong; Jing, Qingshen; Guo, Hengyu; Wen, Zhen; Pradel, Ken C; Niu, Simiao; Wang, Zhong Lin

    2015-03-24

    With 70% of the earth's surface covered with water, wave energy is abundant and has the potential to be one of the most environmentally benign forms of electric energy. However, owing to lack of effective technology, water wave energy harvesting is almost unexplored as an energy source. Here, we report a network design made of triboelectric nanogenerators (TENGs) for large-scale harvesting of kinetic water energy. Relying on surface charging effect between the conventional polymers and very thin layer of metal as electrodes for each TENG, the TENG networks (TENG-NW) that naturally float on the water surface convert the slow, random, and high-force oscillatory wave energy into electricity. On the basis of the measured output of a single TENG, the TENG-NW is expected to give an average power output of 1.15 MW from 1 km(2) surface area. Given the compelling features, such as being lightweight, extremely cost-effective, environmentally friendly, easily implemented, and capable of floating on the water surface, the TENG-NW renders an innovative and effective approach toward large-scale blue energy harvesting from the ocean.

  20. Improvements in the electromechanical conversion of energy using shock waves

    International Nuclear Information System (INIS)

    Landure, Yves

    1971-01-01

    This report concerns the electrical mechanical conversion. In this study it was obtained by the depolarization of a ferroelectric ceramic. We are particularly interested by the high electrical horse-power. Shock wave which produces depolarization is created by a gun powder. The speed of the projectile is measured and the pressures generated in the ceramic is determined graphically. The energy freed is released on a linear resistive load. We were able to prove by different parameters how to obtain the maximum electrical energy. On a resistive load of 26 ohms, it was freed 0,91 J/cm 3 in less than 0,5 μs corresponding to an electrical horse-power superior to 2 MW/cm 3 . (author) [fr

  1. Wave power - Sustainable energy or environmentally costly? A review with special emphasis on linear wave energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Langhamer, Olivia [Dept. of Animal Ecology, UU, Norbyvaegen 18D, S-75236 Uppsala (Sweden); Swedish Centre for Renewable Electric Energy Conversion, Division for Electricity, Aangstroem Laboratory, Uppsala University, Box 534, S-75121 Uppsala (Sweden); Haikonen, Kalle; Sundberg, Jan [Swedish Centre for Renewable Electric Energy Conversion, Division for Electricity, Aangstroem Laboratory, Uppsala University, Box 534, S-75121 Uppsala (Sweden)

    2010-05-15

    Generating electricity from waves is predicted to be a new source of renewable energy conversion expanding significantly, with a global potential in the range of wind and hydropower. Several wave power techniques are on the merge of commercialisation, and thus evoke questions of environmental concern. Conservation matters are to some extent valid independent of technique but we mainly focus on point absorbing linear generators. By giving examples from the Lysekil project, run by Uppsala University and situated on the Swedish west coast, we demonstrate ongoing and future environmental studies to be performed along with technical research and development. We describe general environmental aspects generated by wave power projects; issues also likely to appear in Environmental Impact Assessment studies. Colonisation patterns and biofouling are discussed with particular reference to changes of the seabed and alterations due to new substrates. A purposeful artificial reef design to specially cater for economically important or threatened species is also discussed. Questions related to fish, fishery and marine mammals are other examples of topics where, e.g. no-take zones, marine bioacoustics and electromagnetic fields are important areas. In this review we point out areas in which studies likely will be needed, as ventures out in the oceans also will give ample opportunities for marine environmental research in general and in areas not previously studied. Marine environmental and ecological aspects appear to be unavoidable for application processes and in post-deployment studies concerning renewable energy extraction. Still, all large-scale renewable energy conversion will cause some impact mainly by being area demanding. An early incorporation of multidisciplinary and high quality research might be a key for new ocean-based techniques. (author)

  2. Energy of linear quasi-neutral electrostatic drift waves

    International Nuclear Information System (INIS)

    Pfirsch, D.; Correa-Restrepo, D.

    1992-01-01

    An exact energy expression for linear quasi-neutral electrostatic perturbations is derived within the framework of dissipationless multi-fluid theory, valid for any geometry. Taking the mass as a tensor with, in general, different masses parallel and perpendicular to an ambient magnetic field allows one to treat the full dynamics and also to restrict consideration to parallel dynamics or to the completely adiabatic case. Application to slab configurations yields the result that in plane geometry the adiabatic approximation does not allow negative-energy perturbations, whereas inclusion of the parallel dynamics does. This is in agreement with a numerical study of drift-wave turbulence within the framework of collisional two-fluid theory by B. Scott. Unlike Scott, we consider a dissipationless theory. Whereas the nonlinear energy is just kinetic plus potential plus thermal energy, the energy of perturbations depends on constraints. In a multi-fluid quasi-neutral electrostatic theory, from which we start, such constraints are mass conservation and entropy conservation. The latter is violated if heat conduction, heat sources (e.g. Joule heating) and heat sinks play a role. Hence, the energy expressions obtained are, valid only when situations where this is not the case or where these phenomena do not influence the entropy constraint. The latter is the case if the heat conduction is infinitely large such that the equilibrium temperature profiles T ν (x) of the various particle species ν are independent of x and δT ν =0. A vanishing temperature perturbation results in an entropy-conserving theory if one takes the adiabatic coefficients γ ν =1. This is possible, however, only for the perturbations; the equilibrium energy would diverge. When we consider this case, we do it in the way that the γs are put equal to 1 only after having obtained the perturbed energy for general γs. (author) 7 refs

  3. Reliability-Based Structural Optimization of Wave Energy Converters

    Directory of Open Access Journals (Sweden)

    Simon Ambühl

    2014-12-01

    Full Text Available More and more wave energy converter (WEC concepts are reaching prototypelevel. Once the prototype level is reached, the next step in order to further decrease thelevelized cost of energy (LCOE is optimizing the overall system with a focus on structuraland maintenance (inspection costs, as well as on the harvested power from the waves.The target of a fully-developed WEC technology is not maximizing its power output,but minimizing the resulting LCOE. This paper presents a methodology to optimize thestructural design of WECs based on a reliability-based optimization problem and the intentto maximize the investor’s benefits by maximizing the difference between income (e.g., fromselling electricity and the expected expenses (e.g., structural building costs or failure costs.Furthermore, different development levels, like prototype or commercial devices, may havedifferent main objectives and will be located at different locations, as well as receive varioussubsidies. These points should be accounted for when performing structural optimizationsof WECs. An illustrative example on the gravity-based foundation of the Wavestar deviceis performed showing how structural design can be optimized taking target reliability levelsand different structural failure modes due to extreme loads into account.

  4. Design and Experiment Analysis of a Direct-Drive Wave Energy Converter with a Linear Generator

    OpenAIRE

    Jing Zhang; Haitao Yu; Zhenchuan Shi

    2018-01-01

    Coastal waves are an abundant nonpolluting and renewable energy source. A wave energy converter (WEC) must be designed for efficient and steady operation in highly energetic ocean environments. A direct-drive wave energy conversion (D-DWEC) system with a tubular permanent magnet linear generator (TPMLG) on a wind and solar photovoltaic complementary energy generation platform is proposed to improve the conversion efficiency and reduce the complexity and device volume of WECs. The operating pr...

  5. Initial Characterization of the Wave Resource at Several High Energy U.S. Sites

    OpenAIRE

    Dallman, Ann; Neary, Vincent S.

    2014-01-01

    Wave energy resource characterization efforts are critical for developing knowledge of the physical conditions experienced by wave energy converter (WEC) devices and arrays. Developers are lacking a consistent characterization of possible wave energy test sites, and therefore Sandia National Laboratories (SNL) has been tasked with developing a catalogue characterizing three high energy U.S. test sites. The initial results and framework for the catalogue are discussed in this paper. U.S. De...

  6. Preliminary Evaluation of Critical Wave Energy Thresholds at Natural and Created Coastal Wetlands

    National Research Council Canada - National Science Library

    Shafer, Deborah

    2003-01-01

    This technical note presents an evaluation of the wave climate at eight natural and created coastal wetland sites in an effort to identify the existence of critical wave energy thresholds for long-term marsh stability...

  7. Multi-relaxation-time lattice Boltzmann modeling of the acoustic field generated by focused transducer

    Science.gov (United States)

    Shan, Feng; Guo, Xiasheng; Tu, Juan; Cheng, Jianchun; Zhang, Dong

    The high-intensity focused ultrasound (HIFU) has become an attractive therapeutic tool for the noninvasive tumor treatment. The ultrasonic transducer is the key component in HIFU treatment to generate the HIFU energy. The dimension of focal region generated by the transducer is closely relevant to the safety of HIFU treatment. Therefore, it is essential to numerically investigate the focal region of the transducer. Although the conventional acoustic wave equations have been used successfully to describe the acoustic field, there still exist some inherent drawbacks. In this work, we presented an axisymmetric isothermal multi-relaxation-time lattice Boltzmann method (MRT-LBM) model with the Bouzidi-Firdaouss-Lallemand (BFL) boundary condition in cylindrical coordinate system. With this model, some preliminary simulations were firstly conducted to determine a reasonable value of the relaxation parameter. Then, the validity of the model was examined by comparing the results obtained with the LBM results with the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation and the Spheroidal beam equation (SBE) for the focused transducers with different aperture angles, respectively. In addition, the influences of the aperture angle on the focal region were investigated. The proposed model in this work will provide significant references for the parameter optimization of the focused transducer for applications in the HIFU treatment or other fields, and provide new insights into the conventional acoustic numerical simulations.

  8. Innovative wave energy device applied to coastal observatory systems

    Science.gov (United States)

    Marcelli, Marco; Bonamano, Simone; Piermattei, Viviana; Scanu, Sergio; Paladini de Mendoza, Francesco; Martellucci, Riccardo; Maximo, Peviani

    2017-04-01

    Marine environment is one of the most promising sources of renewable energy, whose exploitation could have an effect on several application fields. This work presents the design of an innovative device based on the Oscillating Water Column (OWC), that allows to convert wave energy into electricity, suitable for the typical Mediterranean wave climate. The flexibility of the device permits its installation either in deep or shallow waters, with reduced costs of deployment, maintenance and connection to the grid. Furthermore, the replicability of the design allows the device to be installed in array of several number of similar units. The technical concept is to convey the sea water within a vertical pipe, in which the water movements activate a rotor connected to a generator that transforms the energy of the water motion into electricity. The hydrodynamic design of the pipe is built to minimize the losses due to friction and turbulence and to exploit the maximum possible energy from wave motion. The wave energy is directly absorbed by the rotational movement of the turbine blades located in the water itself allowing a further reduction of the energy losses associated with the transformation of the linear water motion into electrical generation in the air phase (typical configuration of the OWC devices). In this work the device components are described considering two possible configurations that use a Wells turbine or a Bulb type turbine. The system can be realized at a low cost, because of the modularity of the device project, which allows large freedom of sizes and placements, being able to be installed both individually and in arrays. The modularity, associated with the fact that the main elements of the system are available on the market, makes the device particularly attractive from the economic point of view. Finally, it is realized with a high constructive flexibility: the proposed system can be transported floating and moored to existing coastal structures or

  9. Energy and Information Transfer Via Coherent Exciton Wave Packets

    Science.gov (United States)

    Zang, Xiaoning

    Electronic excitons are bound electron-hole states that are generated when light interacts with matter. Such excitations typically entangle with phonons and rapidly decohere; the resulting electronic state dynamics become diffusive as a result. However, if the exciton-phonon coupling can be reduced, it may be possible to construct excitonic wave packets that offer a means of efficiently transmitting information and energy. This thesis is a combined theory/computation investigation to design condensed matter systems which support the requisite coherent transport. Under the idealizing assumption that exciton-phonon entanglement could be completely suppressed, the majority of this thesis focuses on the creation and manipulation of exciton wave packets in quasi-one-dimensional systems. While each site could be a silicon quantum dot, the actual implementation focused on organic molecular assemblies for the sake of computational simplicity, ease of experimental implementation, potential for coherent transport, and promise because of reduced structural uncertainty. A laser design was derived to create exciton wave packets with tunable shape and speed. Quantum interference was then exploited to manipulate these packets to block, pass, and even dissociate excitons based on their energies. These developments allow exciton packets to be considered within the arena of quantum information science. The concept of controllable excitonic wave packets was subsequently extended to consider molecular designs that allow photons with orbital angular momentum to be absorbed to create excitons with a quasi-angular momentum of their own. It was shown that a well-defined measure of topological charge is conserved in such light-matter interactions. Significantly, it was also discovered that such molecules allow photon angular momenta to be combined and later emitted. This amounts to a new way of up/down converting photonic angular momentum without relying on nonlinear optical materials. The

  10. Validation of Hydrodynamic Numerical Model of a Pitching Wave Energy Converter

    DEFF Research Database (Denmark)

    López, Maria del Pilar Heras; Thomas, Sarah; Kramer, Morten Mejlhede

    2017-01-01

    Validation of numerical model is essential in the development of new technologies. Commercial software and codes available simulating wave energy converters (WECs) have not been proved to work for all the available and upcoming technologies yet. The present paper presents the first stages...... of the validation process of a hydrodynamic numerical model for a pitching wave energy converter. The development of dry tests, wave flume and wave basin experiments are going to be explained, lessons learned shared and results presented....

  11. Simulation of breaking waves using the high-order spectral method with laboratory experiments: wave-breaking energy dissipation

    Science.gov (United States)

    Seiffert, Betsy R.; Ducrozet, Guillaume

    2018-01-01

    We examine the implementation of a wave-breaking mechanism into a nonlinear potential flow solver. The success of the mechanism will be studied by implementing it into the numerical model HOS-NWT, which is a computationally efficient, open source code that solves for the free surface in a numerical wave tank using the high-order spectral (HOS) method. Once the breaking mechanism is validated, it can be implemented into other nonlinear potential flow models. To solve for wave-breaking, first a wave-breaking onset parameter is identified, and then a method for computing wave-breaking associated energy loss is determined. Wave-breaking onset is calculated using a breaking criteria introduced by Barthelemy et al. (J Fluid Mech https://arxiv.org/pdf/1508.06002.pdf, submitted) and validated with the experiments of Saket et al. (J Fluid Mech 811:642-658, 2017). Wave-breaking energy dissipation is calculated by adding a viscous diffusion term computed using an eddy viscosity parameter introduced by Tian et al. (Phys Fluids 20(6): 066,604, 2008, Phys Fluids 24(3), 2012), which is estimated based on the pre-breaking wave geometry. A set of two-dimensional experiments is conducted to validate the implemented wave breaking mechanism at a large scale. Breaking waves are generated by using traditional methods of evolution of focused waves and modulational instability, as well as irregular breaking waves with a range of primary frequencies, providing a wide range of breaking conditions to validate the solver. Furthermore, adjustments are made to the method of application and coefficient of the viscous diffusion term with negligible difference, supporting the robustness of the eddy viscosity parameter. The model is able to accurately predict surface elevation and corresponding frequency/amplitude spectrum, as well as energy dissipation when compared with the experimental measurements. This suggests the model is capable of calculating wave-breaking onset and energy dissipation

  12. Creaming enhancement in a liter scale ultrasonic reactor at selected transducer configurations and frequencies.

    Science.gov (United States)

    Juliano, Pablo; Temmel, Sandra; Rout, Manoj; Swiergon, Piotr; Mawson, Raymond; Knoerzer, Kai

    2013-01-01

    Recent research has shown that high frequency ultrasound (0.4-3 MHz), can enhance milkfat separation in small scale systems able to treat only a few milliliters of sample. In this work, the effect of ultrasonic standing waves on milkfat creaming was studied in a 6L reactor and the influence of different frequencies and transducer configurations in direct contact with the fluid was investigated. A recombined coarse milk emulsion with fat globules stained with oil-red-O dye was selected for the separation trials. Runs were performed with one or two transducers placed in vertical (parallel or perpendicular) and horizontal positions (at the reactor base) at 0.4, 1 and/or 2 MHz (specific energy 8.5 ± 0.6 kJ/kg per transducer). Creaming behavior was assessed by measuring the thickness of the separated cream layer. Other methods supporting this assessment included the measurement of fat content, backscattering, particle size distribution, and microscopy of samples taken at the bottom and top of the reactor. Most efficient creaming was found after treatment at 0.4 MHz in single and double vertical transducer configurations. Among these configurations, a higher separation rate was obtained when sonicating at 0.4 MHz in a vertical perpendicular double transducer setup. The horizontal transducer configuration promoted creaming at 2 MHz only. Fat globule size increase was observed when creaming occurred. This research highlights the potential for enhanced separation of milkfat in larger scale systems from selected transducer configurations in contact with a dairy emulsion, or emulsion splitting in general. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Calibration of acoustic emission transducers

    International Nuclear Information System (INIS)

    Leschek, W.C.

    1976-01-01

    A method is described for calibrating an acoustic emission transducer to be used in a pre-set frequency range. The absolute reception sensitivity of a reference transducer is determined at frequencies selected within the frequency range. The reference transducer and the acoustic emission transducer are put into acoustic communication with the surface of a limited acoustic medium representing an equivalent acoustic load appreciably identical to that of the medium in which the use of the acoustic emission transducer is intended. A blank random acoustic noise is emitted in the acoustic medium in order to establish a diffuse and reverberating sound field, after which the output responses of the reference transducer and of the acoustic emission transducer are obtained with respect to the diffuse and reverberating field, for selected frequencies. The output response of the acoustic emission transducer is compared with that of the reference transducer for the selected frequencies, so as to determine the reception sensitivity of the acoustic emission transducer [fr

  14. Does the source energy change when gravitaion waves are emitted in the einstein's gravitation theory

    International Nuclear Information System (INIS)

    Logunov, A.A.; Folomeshkin, V.N.

    1977-01-01

    It is shown that in the Einstein's gravitation theory the total ''energy'' of a plane gravitational wave calculated with any pseudotensor is equal to zero. The known Einstein's result, according to which the energy of a sourceis decreased when plane weak gravitational waves are emitted, have no place in the Einstein's gravitational theory. The examples are given of exact wave solutions for which the pseudotensor is strictly equal to zero. The energy-momentum of any weak gravitational waves is always equal to zero in the Einstein's gravitation theory. When such waves are emitted the energy of the source cannot change, although these waves are real curvature waves. By the means in the Einstein's gravitation theory the energy, e, is in essenc generated from nothing

  15. Internal wave energy flux from density perturbations in nonlinear stratifications

    Science.gov (United States)

    Lee, Frank M.; Allshouse, Michael R.; Swinney, Harry L.; Morrison, P. J.

    2017-11-01

    Tidal flow over the topography at the bottom of the ocean, whose density varies with depth, generates internal gravity waves that have a significant impact on the energy budget of the ocean. Thus, understanding the energy flux (J = p v) is important, but it is difficult to measure simultaneously the pressure and velocity perturbation fields, p and v . In a previous work, a Green's-function-based method was developed to calculate the instantaneous p, v , and thus J , given a density perturbation field for a constant buoyancy frequency N. Here we extend the previous analytic Green's function work to include nonuniform N profiles, namely the tanh-shaped and linear cases, because background density stratifications that occur in the ocean and some experiments are nonlinear. In addition, we present a finite-difference method for the general case where N has an arbitrary profile. Each method is validated against numerical simulations. The methods we present can be applied to measured density perturbation data by using our MATLAB graphical user interface EnergyFlux. PJM was supported by the U.S. Department of Energy Contract DE-FG05-80ET-53088. HLS and MRA were supported by ONR Grant No. N000141110701.

  16. Assessment of wave energy potential along the south coast of Java Island

    Science.gov (United States)

    Song, Qingyang; Mayerle, Roberto

    2018-04-01

    The south coast of Java Island has a great potential for wave energy. A long-term analysis of a 10-year wave dataset obtained from the ERA-Interim database is performed for preliminary wave energy assessment in this area, and it was seen that the annual median power is expected to exceed 20kW/m along the coast. A coastal wave model with an unstructured grid was run to reveal the wave conditions and to assess the wave energy potential along the coast in detail. The effect of swells and local wind on the wave conditions is investigated. Annual median wave power, water depth and distance from the coast are selected as criteria for the identification of suitable locations for wave energy conversion. Two zones within the study area emerge to be suitable for wave energy extraction. Swells from the southwest turned out to be the major source of wave energy and highest monthly median wave power reached about 33kW/m.

  17. Optimization of sources for focusing wave energy in targeted formations

    KAUST Repository

    Jeong, C

    2010-06-08

    We discuss a numerical approach for identifying the surface excitation that is necessary to maximize the response of a targeted subsurface formation. The motivation stems from observations in the aftermath of earthquakes, and from limited field experiments, whereby increased oil production rates were recorded and were solely attributable to the induced reservoir shaking. The observations suggest that focusing wave energy to the reservoir could serve as an effective low-cost enhanced oil recovery method. In this paper, we report on a general method that allows the determination of the source excitation, when provided with a desired maximization outcome at the targeted formation. We discuss, for example, how to construct the excitation that will maximize the kinetic energy in the target zone, while keeping silent the neighbouring zones. To this end, we cast the problem as an inverse-source problem, and use a partial-differential- equation-constrained optimization approach to arrive at an optimized source signal. We seek to satisfy stationarity of an augmented functional, which formally leads to a triplet of state, adjoint and control problems. We use finite elements to resolve the state and adjoint problems, and an iterative scheme to satisfy the control problem to converge to the sought source signal. We report on one-dimensional numerical experiments in the time domain involving a layered medium of semi-infinite extent. The numerical results show that the targeted formation\\'s kinetic energy resulting from an optimized wave source could be several times greater than the one resulting from a blind source choice, and could overcome the mobility threshold of entrapped reservoir oil. © 2010 Nanjing Geophysical Research Institute.

  18. Optimization of sources for focusing wave energy in targeted formations

    International Nuclear Information System (INIS)

    Jeong, C; Kallivokas, L F; Huh, C; Lake, L W

    2010-01-01

    We discuss a numerical approach for identifying the surface excitation that is necessary to maximize the response of a targeted subsurface formation. The motivation stems from observations in the aftermath of earthquakes, and from limited field experiments, whereby increased oil production rates were recorded and were solely attributable to the induced reservoir shaking. The observations suggest that focusing wave energy to the reservoir could serve as an effective low-cost enhanced oil recovery method. In this paper, we report on a general method that allows the determination of the source excitation, when provided with a desired maximization outcome at the targeted formation. We discuss, for example, how to construct the excitation that will maximize the kinetic energy in the target zone, while keeping silent the neighbouring zones. To this end, we cast the problem as an inverse-source problem, and use a partial-differential-equation-constrained optimization approach to arrive at an optimized source signal. We seek to satisfy stationarity of an augmented functional, which formally leads to a triplet of state, adjoint and control problems. We use finite elements to resolve the state and adjoint problems, and an iterative scheme to satisfy the control problem to converge to the sought source signal. We report on one-dimensional numerical experiments in the time domain involving a layered medium of semi-infinite extent. The numerical results show that the targeted formation's kinetic energy resulting from an optimized wave source could be several times greater than the one resulting from a blind source choice, and could overcome the mobility threshold of entrapped reservoir oil

  19. Marine Waves Energy: A spatio-temporal DSS-WebGIS to support the wave-energy potential assessment in the Mediterranean Sea

    International Nuclear Information System (INIS)

    Pollino, Maurizio; La Porta, Luigi; Caiaffa, Emanuela

    2015-01-01

    GIS technologies are able to provide a useful tool for estimating the energy resource from the sea waves, assessing whether this energy flux is exploitable and evaluating the social and environmental impacts in deep water and/or in the seaboard. The DDS-WebGIS 'Energy Waves' represents a tool for displaying and sharing geo spatial data and maps, as well as a valuable support for new installations planning, forecasting system and existing infrastructure management. [it

  20. Investigation of Wave Energy Converter Effects on Wave Fields: A Modeling Sensitivity Study in Monterey Bay CA.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Grace Chang; Jason Magalen; Craig Jones

    2014-08-01

    A n indust ry standard wave modeling tool was utilized to investigate model sensitivity to input parameters and wave energy converter ( WEC ) array deploym ent scenarios. Wave propagation was investigated d ownstream of the WECs to evaluate overall near - and far - field effects of WEC arrays. The sensitivity study illustrate d that b oth wave height and near - bottom orbital velocity we re subject to the largest pote ntial variations, each decreas ed in sensitivity as transmission coefficient increase d , as number and spacing of WEC devices decrease d , and as the deployment location move d offshore. Wave direction wa s affected consistently for all parameters and wave perio d was not affected (or negligibly affected) by varying model parameters or WEC configuration .