Science.gov

Sample records for exploit wave energy

  1. Energy for lunar resource exploitation

    NASA Technical Reports Server (NTRS)

    Glaser, Peter E.

    1992-01-01

    Humanity stands at the threshold of exploiting the known lunar resources that have opened up with the access to space. America's role in the future exploitation of space, and specifically of lunar resources, may well determine the level of achievement in technology development and global economic competition. Space activities during the coming decades will significantly influence the events on Earth. The 'shifting of history's tectonic plates' is a process that will be hastened by the increasingly insistent demands for higher living standards of the exponentially growing global population. Key to the achievement of a peaceful world in the 21st century, will be the development of a mix of energy resources at a societally acceptable and affordable cost within a realistic planning horizon. This must be the theme for the globally applicable energy sources that are compatible with the Earth's ecology. It is in this context that lunar resources development should be a primary goal for science missions to the Moon, and for establishing an expanding human presence. The economic viability and commercial business potential of mining, extracting, manufacturing, and transporting lunar resource based materials to Earth, Earth orbits, and to undertake macroengineering projects on the Moon remains to be demonstrated. These extensive activities will be supportive of the realization of the potential of space energy sources for use on Earth. These may include generating electricity for use on Earth based on beaming power from Earth orbits and from the Moon to the Earth, and for the production of helium 3 as a fuel for advanced fusion reactors.

  2. Geothermal energy exploitation in New Zealand

    SciTech Connect

    Elder, J.W.

    1980-01-01

    The essential factors, human and technical, which control the operation of geothermal systems, particularly those which allow prediction of behavior during and after exploitation, are sketched. The strategy and co-ordination involved in using New Zealand's geothermal resources for power production are considered. The broader aspects of the technical matters involved in the design of the parasitic plant reservoir system are described. (MHR)

  3. Cycloidal Wave Energy Converter

    SciTech Connect

    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

  4. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    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.

  5. Offshore wave energy experiment

    SciTech Connect

    Nielsen, K.; Scholten, N.C.; Soerensen, K.A. |

    1995-12-31

    This article describes the second phase of the off-shore wave energy experiment, taking place in the Danish part of the North Sea near Hanstholm. The wave power converter is a scale model consisting of a float 2.5 meter in diameter connected by rope to a seabed mounted piston pump installed on 25 meter deep water 2,5 km offshore. The structure, installation procedure results and experience gained during the test period will be presented and compared to calculations based on a computer model.

  6. Ocean, Wave and Tidal Energy Systems; (USA)

    SciTech Connect

    Raridon, M.H.; Hicks, S.C.

    1991-01-01

    Ocean, Wave, and Tidal Energy Systems (OES) announces on a biomonthly basis the current worldwide information available on all aspects of ocean thermal energy conversion systems based on exploitation of the temperature difference between the surface water and ocean depth. All aspects of salinity gradient power systems based on extracting energy from mixing fresh water with seawater are included, along with information on wave and tidal power. This publication contains the abstracts of DOE reports, journal articles, conference papers, patents, theses, and monographs added to the Energy Science and Technology Database (EDB) during the past two months. Also included are US information obtained through acquisition programs or interagency agreements and international information obtained through the International Energy Agency's Energy Technology Data Exchange or government-to-government agreements.

  7. Wave energy desalinization

    SciTech Connect

    Hopfe, H.H.

    1982-06-22

    A device for producing fresh water from salt sea water by utilizing the hydrodynamic energy of waves, comprising a buoyant platform; means for mooring the platform; a pump connected to the mooring means; a reservoir for pressurized sea water; a desalination system for extracting fresh water from the sea water; hydraulic flow control means for causing the pump to pump sea water into the sea water reservoir, as motion of the buoyant platform is produced due to the passing of waves beneath it; measuring means for measuring parameters of the sea adjacent the buoyant platform; and a control device connected to control the pressure in the sea water reservoir and the flow of sea water from the reservoir through the desalination system in response to the parameters of the sea.

  8. Wave energy: a Pacific perspective.

    PubMed

    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. PMID:22184673

  9. Wave energy and intertidal productivity

    PubMed Central

    Leigh, Egbert G.; Paine, Robert T.; Quinn, James F.; Suchanek, Thomas H.

    1987-01-01

    In the northeastern Pacific, intertidal zones of the most wave-beaten shores receive more energy from breaking waves than from the sun. Despite severe mortality from winter storms, communities at some wave-beaten sites produce an extraordinary quantity of dry matter per unit area of shore per year. At wave-beaten sites of Tatoosh Island, WA, sea palms, Postelsia palmaeformis, can produce > 10 kg of dry matter, or 1.5 × 108 J, per m2 in a good year. Extraordinarily productive organisms such as Postelsia are restricted to wave-beaten sites. Intertidal organisms cannot transform wave energy into chemical energy, as photosynthetic plants transform solar energy, nor can intertidal organisms “harness” wave energy. Nonetheless, wave energy enhances the productivity of intertidal organisms. On exposed shores, waves increase the capacity of resident algae to acquire nutrients and use sunlight, augment the competitive ability of productive organisms, and protect intertidal residents by knocking away their enemies or preventing them from feeding. PMID:16593813

  10. Exploiting node mobility for energy optimization in wireless sensor networks

    NASA Astrophysics Data System (ADS)

    El-Moukaddem, Fatme Mohammad

    Wireless Sensor Networks (WSNs) have become increasingly available for data-intensive applications such as micro-climate monitoring, precision agriculture, and audio/video surveillance. A key challenge faced by data-intensive WSNs is to transmit the sheer amount of data generated within an application's lifetime to the base station despite the fact that sensor nodes have limited power supplies such as batteries or small solar panels. The availability of numerous low-cost robotic units (e.g. Robomote and Khepera) has made it possible to construct sensor networks consisting of mobile sensor nodes. It has been shown that the controlled mobility offered by mobile sensors can be exploited to improve the energy efficiency of a network. In this thesis, we propose schemes that use mobile sensor nodes to reduce the energy consumption of data-intensive WSNs. Our approaches differ from previous work in two main aspects. First, our approaches do not require complex motion planning of mobile nodes, and hence can be implemented on a number of low-cost mobile sensor platforms. Second, we integrate the energy consumption due to both mobility and wireless communications into a holistic optimization framework. We consider three problems arising from the limited energy in the sensor nodes. In the first problem, the network consists of mostly static nodes and contains only a few mobile nodes. In the second and third problems, we assume essentially that all nodes in the WSN are mobile. We first study a new problem called max-data mobile relay configuration (MMRC ) that finds the positions of a set of mobile sensors, referred to as relays, that maximize the total amount of data gathered by the network during its lifetime. We show that the MMRC problem is surprisingly complex even for a trivial network topology due to the joint consideration of the energy consumption of both wireless communication and mechanical locomotion. We present optimal MMRC algorithms and practical distributed

  11. Energy harvesting from human motion: exploiting swing and shock excitations

    NASA Astrophysics Data System (ADS)

    Ylli, K.; Hoffmann, D.; Willmann, A.; Becker, P.; Folkmer, B.; Manoli, Y.

    2015-02-01

    Modern compact and low power sensors and systems are leading towards increasingly integrated wearable systems. One key bottleneck of this technology is the power supply. The use of energy harvesting techniques offers a way of supplying sensor systems without the need for batteries and maintenance. In this work we present the development and characterization of two inductive energy harvesters which exploit different characteristics of the human gait. A multi-coil topology harvester is presented which uses the swing motion of the foot. The second device is a shock-type harvester which is excited into resonance upon heel strike. Both devices were modeled and designed with the key constraint of device height in mind, in order to facilitate the integration into the shoe sole. The devices were characterized under different motion speeds and with two test subjects on a treadmill. An average power output of up to 0.84 mW is achieved with the swing harvester. With a total device volume including the housing of 21 cm3 a power density of 40 μW cm-3 results. The shock harvester generates an average power output of up to 4.13 mW. The power density amounts to 86 μW cm-3 for the total device volume of 48 cm3. Difficulties and potential improvements are discussed briefly.

  12. Wide-area video exploitation (WAVE) joint data management (JDM) for layered sensing

    NASA Astrophysics Data System (ADS)

    Blasch, Erik P.; Seetharaman, Guna; Russell, Stephen

    2011-06-01

    Emerging technologies of high performance computing facilitate increased data collection for wide area sensing; however, joint data management concepts of operations (CONOPs) are important to fully realize system-level performance. Joint data management (JDM) includes the hardware (e.g. sensors/targets), software (e.g. processing/algorithms), entities (e.g. service-based collections), and operations (scenario-based environments) of data exchange that enable persistent surveillance in the context of a layered sensing or data-to-decision (D2D) information fusion enterprise. Key attributes of an information fusion enterprise system require pragmatic assessment of data and information management, distributed communications, knowledge representation as well as a sensor mix, algorithm choice, life-cycle data management, and human-systems interaction. In this paper, we explore the various issues surrounding Wide-Area Video Exploitation (WAVE) in a layered-sensing environment to include improvements in Joint Data Management such as (1) data collection, construction, and transformation, (2) feature generation, extraction and selection, and (3) information evaluation, presentation, and dissemination. Throughout the paper, we seek to describe the current technology, research directions, and metrics that instantiate a realizable JDM product. We develop the methods for joint data management for structured and unstructured WAVE data in the context of decision making. Discerning accurate track and identification target information from WAVE JDM provides a moving intelligence (MOVINT) capability.

  13. A signal processing approach to exploit chirp excitation in Lamb wave defect detection and localization procedures

    NASA Astrophysics Data System (ADS)

    De Marchi, Luca; Perelli, Alessandro; Marzani, Alessandro

    2013-08-01

    A non-linear Lamb wave signal processing strategy aimed at extending the capability of active-passive networks of PZT transducers for defect detection is proposed. In particular, the proposed signal processing allows to use chirp shaped pulses in actuation, instead of classically applied spiky pulses, requiring thus lower input voltages. To such aim, the acquired Lamb waves are processed by means of a two-step procedure: a warped frequency transform (WFT) to compensate for the dispersion due to the traveled distance, followed by a compression procedure to remove from the signals the induced chirp frequency modulation. Next, the resulting signals are exploited to feed an imaging algorithm aimed at providing the position of the defect on the plate. The potential of the procedure is demonstrated and validated by analyzing experimental Lamb waves propagating in an aluminum plate where defects were emulated by posing an added mass on the plate. The proposed automatic procedure is suitable to locate defect-induced reflections and can be easily implemented in real applications for structural health monitoring.

  14. Tunnel effect wave energy detection

    NASA Technical Reports Server (NTRS)

    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.

  15. Hydrodynamic Performance of a Wave Energy Converter

    NASA Astrophysics Data System (ADS)

    Yang, Yingchen

    2010-11-01

    To harvest energy from ocean waves, a new wave energy converter (WEC) was proposed and tested in a wave tank. The WEC freely floats on the water surface and rides waves. It utilizes its wave-driven angular oscillation to convert the mechanical energy of waves into electricity. To gain the maximum possible angular oscillation of the WEC under specified wave conditions, both floatation of the WEC and wave interaction with the WEC play critical roles in a joint fashion. During the experiments, the submersion condition of the WEC and wave condition were varied. The results were analyzed in terms of the oscillation amplitude, stability, auto-orientation capability, and wave frequency dependency.

  16. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    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.

  17. AxiSEM: Exploiting structural complexity for efficient wave propagation across the scales

    NASA Astrophysics Data System (ADS)

    Nissen-Meyer, Tarje; van Driel, Martin; Leng, Kuangdai; Stähler, Simon; Krischer, Lion; Hosseini, Kasra

    2016-04-01

    Our open-source seismic modeling method AxiSEM (www.axisem.info) is presented a backbone for numerous further extensions, including accurate and efficient wave propagation in 3D Earth models, a database mode (www.instaseis.net), local domains, hybrid methods, and waveform sensitivity kernels for tomography. Our general mantra is to enable wave propagation across the observable frequency spectrum in a most efficient manner by adapting the methodology directly to the level of structural complexity, in the vein of Occam's razor. The basic AxiSEM approach relies upon axisymmetric (including spherically symmetric) models, thereby satisfying a large fraction of observable data. The benefit of this method stems from the resultant dimensional collapse to two numerical dimensions, whereby the third azimuthal dimension is tackled analytically. For high-frequency wave propagation, this leads to 3-4 orders of magnitude speedup in computational cost compared to 3D domain discretizations. AxiSEM is highly scalable anywhere between laptops and supercomputers, and includes novel, optimized implementations of viscoelasticity and anisotropy. We present benchmarks, data comparisons, a range of unique applications from inner-core anisotropy to noise modeling and lowermost mantle structures. 1D structures are exploited by instaseis, a methodology to extract full, broadband and accurate waveforms instantaneously from wavefield databases computed with AxiSEM. A webservice built on instaseis ("syngine") has been launched at IRIS (see abstract EGU2016-8190) to generate on-demand synthetics up to 1Hz for prominent Earth models. 3D structures are tackled by our recent extension AxiSEM3D: We expand the wavefield in the azimuthal dimension in Fourier series, leading to a drastic computational cost speedup compared to classic 3D methods (up to a factor of 100), especially in the high-frequency regime. We will show benchmarks for typical global tomographic models and sketch our approach to

  18. Direct Drive Wave Energy Buoy

    SciTech Connect

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

    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.

  19. Energy in a String Wave

    NASA Astrophysics Data System (ADS)

    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 simple harmonic2. They also know elements of the string at the highest and the lowest positions—the crests and the troughs—are momentarily at rest, while those at the centerline (zero displacement) have the greatest speed, as shown in Fig. 1. Irrespective of this, they are less familiar with the energy associated with the wave. They may fail to answer a question such as, "In a traveling string wave, which elements have respectively the greatest kinetic energy (KE) and the greatest potential energy (PE)?" The answer to the former is not difficult; elements at zero position have the fastest speed and hence their KE, being proportional to the square of speed, is the greatest. To the PE, what immediately comes to their mind may be the simple harmonic motion (SHM), in which the PE is the greatest and the KE is zero at the two turning points. It may thus lead them to think elements at crests or troughs have the greatest PE. Unfortunately, this association is wrong. Thinking that the crests or troughs have the greatest PE is a misconception.3

  20. Key features of wave energy.

    PubMed

    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. PMID:22184669

  1. Ocean wave energy converting vessel

    SciTech Connect

    Boyce, P.F.

    1986-08-26

    An ocean wave energy conversion system is described comprised of a four beam quadrapod supported by bouyant members from which is suspended a pendulum. The pendulum contains a vertical generator shaft and a generator, the generator shaft being splined and fitted with two racheted pulleys, the pulleys being looped, one clockwise and one counterclockwise with separate cables. The cables are attached at their ends to the bow and stern of the quadrapod, whereby the generator shaft will pin when the quadrapod rocks over waves and the pendulum tends toward the center of earth.

  2. Wave energy propelling marine ship

    SciTech Connect

    Kitabayashi, S.

    1982-06-29

    A wave energy propelling marine ship comprises a cylindrical ship body having a hollow space therein for transporting fluid material therewithin, a ship body disposed in or on the sea; a propeller attached to the ship body for the purpose of propelling the marine ship for sailing; a rudder for controlling the moving direction of the marine ship; at least one rotary device which includes a plurality of compartments which are each partitioned into a plurality of water chambers by a plurality of radial plates, and a plurality of water charge and/or discharge ports, wherein wave energy is converted into mechanical energy; and device for adjusting buoyancy of the marine ship so that the rotary device is positioned advantageously on the sea surface.

  3. Thermal exploitation of wastes with lignite for energy production.

    PubMed

    Grammelis, Panagiotis; Kakaras, Emmanuel; Skodras, George

    2003-11-01

    The thermal exploitation of wastewood with Greek lignite was investigated by performing tests in a laboratory-scale fluidized bed reactor, a 1-MW(th) semi-industrial circulating fluidized bed combustor, and an industrial boiler. Blends of natural wood, demolition wood, railroad sleepers, medium-density fiberboard residues, and power poles with lignite were used, and the co-combustion efficiency and the effect of wastewood addition on the emitted pollutants were investigated. Carbon monoxide, sulfur dioxide, and oxides of nitrogen emissions were continuously monitored, and, during the industrial-scale tests, the toxic emissions (polychlorinated dibenzodioxins and dibenzofurans and heavy metals) were determined. Ash samples were analyzed for heavy metals in an inductively coupled plasma-atomic emission spectroscopy spectrophotometer. Problems were observed during the preparation of wastewood, because species embedded with different compounds, such as railway sleepers and demolition wood, were not easily treated. All wastewood blends were proven good fuels; co-combustion proceeded smoothly and homogeneous temperature and pressure profiles were obtained. Although some fluctuations were observed, low emissions of gaseous pollutants were obtained for all fuel blends. The metal element emissions (in the flue gases and the solid residues) were lower than the legislative limits. Therefore, wastewood co-combustion with lignite can be realized, provided that the fuel handling and preparation can be practically performed in large-scale installations. PMID:14649749

  4. Exploiting the Properties of Aquaporin to Calculate Free Energy

    NASA Astrophysics Data System (ADS)

    Espejel, Hugo; Chen, Liao

    2010-03-01

    Aquaporins' (AQPs) main purpose is to facilitate the transfer of water molecules through a molecular membrane. We can calculate the free energy of the AQP system when water permeates through it. This is performed using the Visual Molecular Dynamics (VMD) and the Nanoscale Molecular Dynamics (NAMD) programs. In our first set of experiments, AQP is submerged in a body of water, in which case a water molecule near AQP is pulled through the protein. The data is then used to calculate the free energy using two different equations: the Jarzynski equality and the fluctuation-dissipation theorem. The values from both equations are then compared to examine their accuracy. The second set of experiments has the same set up, but now AQP is embedded in a lipid bilayer. We found that both equations give values that are much smaller than kT. This verifies that AQP is a channel for water molecules because the pulling of water gives constant values of free energy. We also found that the water molecules' negative poles were all pointing towards the center of the AQP channel. This means that the process of proton transport in AQP is overwhelmingly difficult.

  5. The Wave Carpet: An Omnidirectional and Broadband Wave Energy Converter

    NASA Astrophysics Data System (ADS)

    Alam, M.-Reza

    2015-11-01

    Inspired by the strong attenuation of ocean surface waves by muddy seafloors, we have designed, theoretically investigated the performance, and experimentally tested the ``Wave Carpet:'' a mud-resembling synthetic seabed-mounted mat composed of vertically-acting linear springs and generators that can be used as an efficient wave energy absorption device. The Wave Carpet is completely under the water surface hence imposes minimal danger to boats and the sea life (i.e. no mammal entanglement). It is survivable against the high momentum of storm surges and in fact can perform even better under very energetic (e.g. stormy) sea conditions when most existing wave energy devices are needed to shelter themselves by going into an idle mode. In this talk I will present an overview of analytical results for the linear problem, direct simulation of highly nonlinear wave fields, and results of the experimental wave tank investigation.

  6. Ocean, Wave, and Tidal Energy Systems: Current abstracts

    NASA Astrophysics Data System (ADS)

    Smith, L.; Lane, D. W.

    1988-01-01

    Ocean, Wave, and Tidal Energy Systems (OES) announces on a bimonthly basis the current worldwide information available on all aspects of ocean thermal energy conversion systems based on exploitation of the temperature difference between the surface water and ocean depth. All aspects of salinity gradient power systems based on extracting energy from mixing fresh water with seawater are included, along with information on wave and tidal power. This publication contains the abstracts of DOE reports, journal articles, conference papers, patents, theses, and monographs added to the Energy Data Base (EDB) during the past two months. Also included are U.S. information obtained through acquisition programs or interagency agreements and international information obtained through the International Energy Agency's Energy Technology Data Exchange or government-to-government agreements.

  7. Exploitation of SAR data for measurement of ocean currents and wave velocities

    NASA Technical Reports Server (NTRS)

    Shuchman, R. A.; Lyzenga, D. R.; Klooster, A., Jr.

    1981-01-01

    Methods of extracting information on ocean currents and wave orbital velocities from SAR data by an analysis of the Doppler frequency content of the data are discussed. The theory and data analysis methods are discussed, and results are presented for both aircraft and satellite (SEASAT) data sets. A method of measuring the phase velocity of a gravity wave field is also described. This method uses the shift in position of the wave crests on two images generated from the same data set using two separate Doppler bands. Results of the current measurements are pesented for 11 aircraft data sets and 4 SEASAT data sets.

  8. Wave Energy Potential in the Latvian EEZ

    NASA Astrophysics Data System (ADS)

    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.

  9. Feasibility of Wave Energy in Hong Kong

    NASA Astrophysics Data System (ADS)

    Lu, M.; Hodgson, P.

    2014-12-01

    Kinetic energy produced by the movement of ocean waves can be harnessed by wave energy converter equipment such as wave turbines to power onshore electricity generators, creating a valuable source of renewable energy. This experiment measures the potential of wave energy in Hoi Ha Wan Marine Park, Hong Kong using a data buoy programmed to send data through wireless internet every five minutes. Wave power (known as 'wave energy flux') is proportional to wave energy periodicity and to the square of wave height, and can be calculated using the equation: P = 0.5 kW/(m3)(s) x Hs2 x Tp P = wave energy flux (wave energy per unit of wave crest length in kW/m) Hs = significant wave height (m) Tp = wave period (seconds) Acoustic Doppler Current Profilers (ADCPs), or ultrasonic sensors, were installed on the seabed at three monitoring locations to measure Significant Wave Heights (Hs), Significant Wave Periods (Tp) and Significant Wave Direction (Wd). Over a twelve month monitoring period, Significant Wave Heights ranged from 0 ~ 8.63m. Yearly averages were 1.051m. Significant Wave Period ranged from 0 ~ 14.9s. Yearly averages were 6.846s. The maximum wave energy amount recorded was 487.824 kW/m. These results implied that electricity sufficient to power a small marine research center could be supplied by a generator running at 30% efficiency or greater. A wave piston driven generator prototype was designed that could meet output objectives without using complex hydraulics, expensive mechanical linkages, or heavy floating buoys that might have an adverse impact on marine life. The result was a design comprising a water piston connected by an air pipe to a rotary turbine powered generator. A specially designed air valve allowed oscillating bidirectional airflow generated in the piston to be converted into unidirectional flow through the turbine, minimizing kinetic energy loss. A 35cm wave with a one second period could generate 139.430W of electricity, with an efficiency of 37.6%.

  10. Controller for a wave energy converter

    SciTech Connect

    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.

  11. Ocean floor mounting of wave energy converters

    SciTech Connect

    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.

  12. Using remote sensing data for exploitation of integrated renewable energy at coastal site in South Italy

    NASA Astrophysics Data System (ADS)

    Calaudi, Rosamaria; Lo Feudo, Teresa; Calidonna, Claudia Roberta; Sempreviva, Anna Maria

    2016-04-01

    Renewable energy sources are major components of the strategy to reduce harmful emissions and to replace depleting fossil energy resources. Data from Remote Sensing can provide detailed information for analysis for sources of renewable energy and to determine the potential energy and socially acceptability of suggested location. Coastal sites of Southern Italy have the advantage of favorable climatic conditions to use renewable energy, such us cloud free days and local breeze phenomena. Many ports are located where they have opportunities for exploitation of renewable energy, by using existing port area and by taking advantage of their coastal locations. Policies of European-Committee and Global-Navigation-PIANC for a better use of energy and an efficient supply from renewable sources are also focused on the construction of port facilities in zero emissions. Using data from Remote Sensing, can reduce the financial resources currently required for finding and assessing suitable areas, we defined an integrated methodology for potential wind and solar energy in harbor areas. In this study we compared the hourly solar power energy using MSG-SEVIRI (Meteosat Second Generation Spinning Enhanced Visible and Infrared) data products DSSF (Down-welling Surface Short-wave-Flux), and PV-Plant measurements with Nominal Power Peak of 19,85 kWp. The PV Plant is situated at a coastal site in Calabrian region, located near Vibo Valentia harbor area. We estimate potential energy by using input solar radiation of Satellite data, with same characteristics of the PV-plant. The RMSE and BIAS for hourly averaged solar electrical reproducibility are estimated including clear and sky conditions. Comparison between energy reproducibility by using DSSF product and PV-plant measurements, made over the period October 2013-June 2014, showed a good agreement in our costal site and generally overestimate (RMSE(35W/m2) and BIAS(4W/m2)) electrical reproducibility from a PV-plant. For wind resource

  13. Standing wave tube electro active polymer wave energy converter

    NASA Astrophysics Data System (ADS)

    Jean, Philippe; Wattez, Ambroise; Ardoise, Guillaume; Melis, C.; Van Kessel, R.; Fourmon, A.; Barrabino, E.; Heemskerk, J.; Queau, J. P.

    2012-04-01

    Over the past 4 years SBM has developed a revolutionary Wave Energy Converter (WEC): the S3. Floating under the ocean surface, the S3 amplifies pressure waves similarly to a Ruben's tube. Only made of elastomers, the system is entirely flexible, environmentally friendly and silent. Thanks to a multimodal resonant behavior, the S3 is capable of efficiently harvesting wave energy from a wide range of wave periods, naturally smoothing the irregularities of ocean wave amplitudes and periods. In the S3 system, Electro Active Polymer (EAP) generators are distributed along an elastomeric tube over several wave lengths, they convert wave induced deformations directly into electricity. The output is high voltage multiphase Direct Current with low ripple. Unlike other conventional WECs, the S3 requires no maintenance of moving parts. The conception and operating principle will eventually lead to a reduction of both CAPEX and OPEX. By integrating EAP generators into a small scale S3, SBM achieved a world first: direct conversion of wave energy in electricity with a moored flexible submerged EAP WEC in a wave tank test. Through an extensive testing program on large scale EAP generators, SBM identified challenges in scaling up to a utility grid device. French Government supports the consortium consisting of SBM, IFREMER and ECN in their efforts to deploy a full scale prototype at the SEMREV test center in France at the horizon 2014-2015. SBM will be seeking strategic as well as financial partners to unleash the true potentials of the S3 Standing Wave Tube Electro Active Polymer WEC.

  14. Energy in a String Wave

    ERIC Educational Resources Information Center

    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…

  15. Multimodal exploitation and sparse reconstruction for guided-wave structural health monitoring

    NASA Astrophysics Data System (ADS)

    Golato, Andrew; Santhanam, Sridhar; Ahmad, Fauzia; Amin, Moeness G.

    2015-05-01

    The presence of multiple modes in guided-wave structural health monitoring has been usually considered a nuisance and a variety of methods have been devised to ensure the presence of a single mode. However, valuable information regarding the nature of defects can be gleaned by including multiple modes in image recovery. In this paper, we propose an effective approach for localizing defects in thin plates, which involves inversion of a multimodal Lamb wave based model by means of sparse reconstruction. We consider not only the direct symmetric and anti-symmetric fundamental propagating Lamb modes, but also the defect-spawned mixed modes arising due to asymmetry of defects. Model-based dictionaries for the direct and spawned modes are created, which take into account the associated dispersion and attenuation through the medium. Reconstruction of the region of interest is performed jointly across the multiple modes by employing a group sparse reconstruction approach. Performance validation of the proposed defect localization scheme is provided using simulated data for an aluminum plate.

  16. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    NASA Astrophysics Data System (ADS)

    Milanesio, D.; Maggiora, R.

    2015-12-01

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  17. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    SciTech Connect

    Milanesio, D. Maggiora, R.

    2015-12-10

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  18. Transmission of wave energy in curved ducts

    NASA Technical Reports Server (NTRS)

    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.

  19. Energy analysis of wave and tidal power

    NASA Astrophysics Data System (ADS)

    Harrison, R.; Smith, K. G.; Varley, J. S.

    1980-06-01

    Energy requirements for building wave- and tidal-power systems are estimated and the relationship between energy requirements and extraction efficiency is examined for wavepower systems. It is found that a point of maximum net output is reached, beyond which further increases in extraction efficiency result in decreased net energy. In this manner, the energy analysis identifies a limit on the energy which could, in principle, be extracted by a wave-energy system. Finally, it is noted that although similar limits could be identified for other types of energy sources, the tidal power analysis is confined to a brief comparison of energy inputs and outputs.

  20. Breaking of modulated wave trains: energy and spectra evolution

    NASA Astrophysics Data System (ADS)

    De Vita, Francesco; Verzicco, Roberto; Iafrati, Alessandro

    2016-04-01

    The breaking of free surface waves plays an important role on the gas, heat, momentum and energy exchanges taking place across the air-sea interface. The breaking is also responsible for the dissipation of a large fraction of the wave energy, and it represents the most important dissipation term in wave forecasting approaches. In spite of its relevance, there are many aspects of the phenomenon which are still obscure. For the practical applications the dissipated energy fraction and the changes operated to the pre-breaking spectrum are the most interesting aspects. The progress in the understanding of the breaking was hindered by some inherent technical difficulties featuring its experimental investigation. Even laboratory experiments do not help substantially as most of them exploit the superposition of linear waves and the dispersive focusing to induce breaking and only few studies uses the modulational instability. The two breaking processes display substantial differences. In the dispersive focusing case the breaking occur as a single event and all the energy is dissipated within few wave periods after the onset. In the modulational instability case, the breaking happens in several events, each one lasting short fraction of the wave period Tp, with a recurrence period of about 2 Tp. Furthermore, the results available in litterature display a large scatter in the energy dissipation of each breaking event. In order to achieve a better understanding of the phenomenon the breaking generated by modulational instability is here investigated numerically by the two-fluids approach using the open source Gerris code which solves the Navier-Stokes equations with a Volume of Fluid (VOF) technique to describe the interface dynamics. The solution is initialized as a fundamental wave component with two sideband disturbances and it is left to evolve in a computational domain with periodic boundary conditions. It is shown that several breaking events occur before the breaking

  1. Estimation and Monitoring of Wind/Wave energy potential in the Eastern Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Zodiatis, George; Galanis, George; Galanis, George; Emmanouil, George; Emmanouil, George; Hayes, Dan; Nikolaidis, Andreas; Georgiou, Georgios; Kalogeri, Christina; Kallos, George

    2013-04-01

    Τhe adaptation and use of innovative methodologies for the exploitation of renewable energy marine resources is one of the main issues today for the environmental science community. Within this framework, the exploitation of wind and wave energy potential for coastal and island states seems to be one of the promising solutions and highly interesting from research and technological point of view. In this work, the activities of two projects focusing on the study of wind/wave energy over the area of Eastern Mediterranean Sea are presented. The "Integrated High Resolution System for Monitoring and Quantifying the Wave Energy Potential in the EEZ of Cyprus" (Ewave project) focuses on the estimation, monitoring and forecasting of the wave energy potential over the Levantine Basin with special emphasis to the Exclusive Economical Zone of Cyprus, while the "Development and application of new mathematical and physical models for Monitoring the wind and Sea wave Energy Potential" (MOSEP project) is a platform for developing new mathematical algorithms for the estimation of the wave energy over the Aegean Sea. In both projects, high resolution digital atlases of sea wave/wind climatological characteristics and the distribution of the wind and wave energy potential are developed for the coastal and offshore areas of the East Mediterranean sea . Moreover, new models for the prediction and quantification of wave energy in short and long forecast horizons are proposed. Statistical results concerning the probability density functions of the wind speed, the significant wave height, as well as the energy potential will be presented for selected sea areas in the Eastern Mediterranean Sea, while test case studies in certain regions favor to wind/wave renewable energy will be discussed.

  2. How to fully exploit frequency-dependent S-wave travel times for refining the Earth's mantle imaging?

    NASA Astrophysics Data System (ADS)

    Zaroli, C.; Nolet, G.; Charlety, J.; Debayle, E.; Sambridge, M.

    2011-12-01

    To better constrain the structure of the Earth's interior, new theoretical developments on seismic wave propagation have emerged in recent years, and received increasing attention in global tomography. A recent focus has been to take into account the "Finite-Frequency" (FF) behaviour of seismic waves (e.g. wavefront-healing). We have chosen to use the FF approach by Dahlen et al. (2000) in multiple frequency bands, based on a ray-Born approximation, also known as Multiple-Frequency Tomography (MFT). The principle of MFT is to invert delay times measured in several frequency bands, using 3-D FF sensitivity kernels for modeling single-scattering phenomena undergone by seismic waves. Such FF effects are intrinsically always present in delay times measured by waveform cross-correlation (as opposed to onset measurements in ray theory). In this study, we pose the question how much MFT really contributes to improving the 3-D imaging of the deep Earth structure? We investigate the role of the model parameterization and regularization when using MFT, in our ability/unability to map the structural dispersion present in the data into a tomographic model. Our data consist of 274 066 globally distributed S, ScS and SS time residuals measured at 10, 15, 22 and 34 s period (Zaroli et al., 2010). Two ways of parameterizing the Earth's mantle, and their implications on the model obtained using MFT, are presented. One is based on irregularly spaced spherical triangular prisms, with nodes spacing ranging from 200 to 900 km, i.e. a "coarse" parameterization. The other is based on a "cubed Earth", that consists of cubic cells of 70 km size near the top, down to 35 km near the base of the mantle, i.e. a "fine" parameterization. We also investigate how the model regularization (i.e. choice of the damping parameter in the inversion) may prevent us from fully exploiting the extra information, on the 3-D structure, present in our multi-band dataset. We present a comparison of a multi

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Waves and Wine: Advanced approaches for characterizing and exploiting micro-terroir

    NASA Astrophysics Data System (ADS)

    Hubbard, S. S.; Grote, K. R.; Freese, P.; Peterson, J. E.; Rubin, Y.

    2012-12-01

    Development of viticultural strategies that are focused on promoting uniformly high quality wine grapes requires an understanding of the properties that influence wine grape development. Our objective is to explore the spatial and temporal variability of above and below ground factors that can influence grape variability at the block scale (or micro-terroir) using a combination of conventional point measurements and non-invasive geophysical approaches, and to use that information to guide the development of new vineyards or the management of existing vineyards. Climate clearly plays a dominant role in determining the success of certain viticultural regions or vintages. However, wine grapes of the same variety, which are grown in the same microclimate region and cultivated and made into wine using identical practices, can lead to remarkably different wines when the grapes are grown on different types of soils. The soil texture controls soil water availability, which greatly influences grapevine physiological status, vegetative and reproductive growth, and ultimately red wine grape quality. One aspect of our research has focused on developing surface geophysical methods, particularly ground penetrating radar (GPR), to characterize soil texture variability and to monitor vineyard water content. Through testing the approaches in three California wineries, we find that analysis of GPR groundwave and reflected waves enable mapping of shallow soil water content in high resolution, with acceptable accuracy, and in a non-invasive manner, and that use of multiple GPR methods and frequencies offer the potential to characterize the soil in 3-D space. We use the dense data to explore spatial and temporal correlations in soil water content, soil texture, and vegetation vigor and the associated implications for vineyard management. We also describe a new zonal-based vineyard development strategy that honors the natural variability of the site, or the micro-terrior. The approach

  5. WEC-Sim (Wave Energy Converter - SIMulator)

    Energy Science and Technology Software Center (ESTSC)

    2014-11-26

    WEC-Sim (Wave Energy Converter SIMulator) is a code developed by Sandia National Laboratories and the National Renewable Energy Laboratory to model wave energy converters (WECs) when they are subject to operational waves. The code is a time-domain modeling tool developed in MATLAB/Simulink using the multi-body dynamics solver SimMechanics. In WEC-Sim, WECs are modeled by connecting rigid bodies to one another with joint or constraint blocks from the WEC-Sim library. WEC-Sim is a publicly available, open-sourcemore » code to model WECs.« less

  6. WEC-Sim (Wave Energy Converter - SIMulator)

    SciTech Connect

    2014-11-26

    WEC-Sim (Wave Energy Converter SIMulator) is a code developed by Sandia National Laboratories and the National Renewable Energy Laboratory to model wave energy converters (WECs) when they are subject to operational waves. The code is a time-domain modeling tool developed in MATLAB/Simulink using the multi-body dynamics solver SimMechanics. In WEC-Sim, WECs are modeled by connecting rigid bodies to one another with joint or constraint blocks from the WEC-Sim library. WEC-Sim is a publicly available, open-source code to model WECs.

  7. Energy Extraction from a Slider-Crank Wave Energy under Irregular Wave Conditions: Preprint

    SciTech Connect

    Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun; Zhang, James Z.; Muljadi, Eduard; Yu, Yi-Hsiang

    2015-08-24

    A slider-crank wave energy converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this particular WEC has been done under regular sinusoidal wave conditions, and suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and a rule-based control methodology is introduced to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from that under regular sinusoidal wave conditions, but a reasonable amount of energy can still be extracted.

  8. Energy Extraction from a Slider-Crank Wave Energy Converter under Irregular Wave Conditions

    SciTech Connect

    Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun; Zhang, James Z.; Muljadi, Eduard; Yu, Yi-Hsiang

    2015-10-19

    A slider-crank wave energy converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this particular WEC has been done under regular sinusoidal wave conditions, and suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and a rule-based control methodology is introduced to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from that under regular sinusoidal wave conditions, but a reasonable amount of energy can still be extracted.

  9. Image processing to optimize wave energy converters

    NASA Astrophysics Data System (ADS)

    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.

  10. Clustering of cycloidal wave energy converters

    DOEpatents

    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.

  11. Analysis of the impacts of Wave Energy Converter arrays on the nearshore wave climate in the Pacific Northwest

    NASA Astrophysics Data System (ADS)

    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

  12. Whistler Wave Energy Flow in the Plasmasphere

    NASA Astrophysics Data System (ADS)

    Kletzing, Craig; Santolik, Ondrej; Kurth, William; Hospodarsky, George; Christopher, Ivar; Bounds, Scott

    2016-07-01

    The measured wave properties of plasmaspheric hiss are important to constrain models of the generation of hiss as well as its propagation and amplification. For example, the generation mechanism for plasmaspheric hiss has been suggested to come from one of three possible mechanisms: 1) local generation and amplification, 2) whistlers from lightning, and 3) chorus emissions which have refracted into the plasmasphere. The latter two mechanisms are external sources which produce an incoherent hiss signature as the original waves mix in a stochastic manner, propagating in both directions along the background magnetic field. In contrast, local generation of plasmaspheric hiss within the plasmasphere should produce a signature of waves propagating away from the source region. For all three mechanisms scattering of energetic particles into the loss cone transfers some energy from the particles to the waves. By examining the statistical characteristics of the Poynting flux of plasmaspheric hiss, we can determine the properties of wave energy flow in the plasmasphere. We report on the statistics of observations from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) Waves instrument on the Van Allen Probes for periods when the spacecraft is inside the plasmasphere. We find that the Poynting flux associated with plasmaspheric hiss has distinct and unexpected radial structure which shows that there can be significant energy flow towards the magnetic equator. We show the properties of this electromagnetic energy flow as a function of position and frequency.

  13. HARNESSING OCEAN WAVE ENERGY TO GENERATE ELECTRICITY

    EPA Science Inventory

    A technical challenge to sustainability is finding an energy source that is abundant enough to meet global demands without producing greenhouse gases or radioactive waste. Energy from ocean surface waves can provide the people of this planet a clean, endless power source to me...

  14. Fundamental formulae for wave-energy conversion

    PubMed Central

    Falnes, Johannes; Kurniawan, Adi

    2015-01-01

    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. PMID:26064612

  15. Parametric CFD study of micro-energy harvesting in a flow channel exploiting vortex shedding

    NASA Astrophysics Data System (ADS)

    Koubogiannis, Dimitrios G.

    2016-05-01

    Miniature energy harvesting devices are increasingly used in various fields. For example, Wireless Sensor Networks have recently made great progress in many applications. However, their main drawback, i.e. the limited duration of operation, poses the requirement for an effective way to recharge their batteries. In this context, the presentwork focuses on the study of micro-energy harvesting from flow by exploiting vortex shedding behind bluff bodies, in order to cause oscillations to a piezoelectric film and generate the required electrical power. To this end, a Computational Fluid Dynamics (CFD) tool is validated on a particular miniature device configuration proposed in the literature and implemented for the numerical simulations of flow around bluff micro-bodies in a very small channel. Aiming to enhance vortex shedding, parametric studies corresponding to different bluff body shapes and arrangements for a fixed Reynolds number are performed, the main parameters involved in the phenomenon are highlighted and the potential for vortex shedding exploitation is qualitatively assessed.

  16. Gradient-index phononic crystal lens-based enhancement of elastic wave energy harvesting

    NASA Astrophysics Data System (ADS)

    Tol, S.; Degertekin, F. L.; Erturk, A.

    2016-08-01

    We explore the enhancement of structure-borne elastic wave energy harvesting, both numerically and experimentally, by exploiting a Gradient-Index Phononic Crystal Lens (GRIN-PCL) structure. The proposed GRIN-PCL is formed by an array of blind holes with different diameters on an aluminum plate, where the blind hole distribution is tailored to obtain a hyperbolic secant gradient profile of refractive index guided by finite-element simulations of the lowest asymmetric mode Lamb wave band diagrams. Under plane wave excitation from a line source, experimentally measured wave field validates the numerical simulation of wave focusing within the GRIN-PCL domain. A piezoelectric energy harvester disk located at the first focus of the GRIN-PCL yields an order of magnitude larger power output as compared to the baseline case of energy harvesting without the GRIN-PCL on the uniform plate counterpart.

  17. Electromagnetic wave energy conversion research

    NASA Technical Reports Server (NTRS)

    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.

  18. DEVELOPING AND EXPLOITING A UNIQUE DATASET FROM SOUTH AFRICAN GOLD MINES FOR SOURCE CHARACTERIZATION AND WAVE PROPAGATION

    SciTech Connect

    Julia, J; Nyblade, A; Gok, R; Walter, W; Linzer, L; Durrheim, R

    2009-07-06

    In this project, we are developing and exploiting a unique seismic dataset to address the characteristics of small seismic events and the associated seismic signals observed at local (< 200 km) and regional (< 2000 km) distances. The dataset is being developed using mining-induced events from three deep gold mines in South Africa recorded on in-mine networks (< 1 km) composed of tens of high-frequency sensors, a network of four broadband stations installed as part of this project at the surface around the mines (1-10 km), and a network of existing broadband seismic stations at local/regional distances (50-1000 km) from the mines. Data acquisition has now been completed and includes: (1) {approx}2 years (2007 and 2008) of continuous recording by the surface broadband array, and (2) tens of thousands of mine tremors in the -3.4 < ML < 4.4 local magnitude range. Events with positive magnitudes are generally well recorded by the surface-mine stations, while magnitudes of 3.0 and larger are seen at regional distances (up to {approx} 600 km) in high-pass filtered recordings. We have now completed the quality control of the in-mine data gathered at the three gold mines included in this project. The quality control consisted of: (1) identification and analysis of outliers among the P- and S-wave travel-time picks reported by the in-mine network operator and (2) verification of sensor orientations. The outliers have been identified through a 'Wadati filter' that searches for the largest subset of P- and S-wave travel-time picks consistent with a medium of uniform wave-speed. They have observed that outliers are generally picked at a few select stations. They have also detected that trigger times were mistakenly reported as origin times by the in-mine network operator, and corrections have been obtained from the intercept times in the Wadati diagrams. Sensor orientations have been verified through rotations into the local ray-coordinate system and, when possible, corrected

  19. Direct Drive Wave Energy Buoy

    SciTech Connect

    Rhinefrank, Ken

    2011-11-02

    Presentation from the 2011 Water Peer Review in which principal investigator discusses project progress and results for this project which will be used to inform the utility-scale design process, improve cost estimates, accurately forecast energy production and to observe system operation and survivability.

  20. Estimation and Monitoring of Wind-Wave energy potential over the Greek seas

    NASA Astrophysics Data System (ADS)

    Emmanouil, G.; Galanis, G.; Zodiatis, G.; Kalogeri, C.

    2013-12-01

    The exploitation of renewable energy resources is today on the top of the interest for the environmental and political community. In particular, wind and wave energy seems to be promising solutions with great potential from research and technological point of view. This kind of energy is mostly a matter of coastal and island countries, like Greece. In this work, the first results of a project whose main target is the development of an integrated, high resolution system for quantifying and monitoring the energy potential from wind and sea waves in the region of Eastern Mediterranean Sea, with special emphasis to the Greek area, are presented. More specifically, the models for the estimation of the energy potential, from wind and waves over sea areas, will be discussed. Moreover, atmospheric and sea wave numerical models used for the simulation of the environmental parameters that directly affect the wind-wave energy potential will be evaluated. Based on these tools, high resolution maps for the coastal and offshore areas of Greece will be produced, in which sea wave and wind climatological characteristics as well as the relevant distribution of the wave energy potential will be monitoring.

  1. Experimental creation and characterization of random potential-energy landscapes exploiting speckle patterns

    NASA Astrophysics Data System (ADS)

    Bewerunge, Jörg; Egelhaaf, Stefan U.

    2016-01-01

    The concept of potential-energy landscapes is applied in many areas of science. We experimentally realize a random potential-energy landscape (RPEL) to which colloids are exposed. This is achieved by exploiting the interaction of matter with light. The optical setup is based on a special diffuser, which creates a top-hat beam containing a speckle pattern. This is imposed on colloids. The effect of the speckle pattern on the colloids can be described by a RPEL. The speckle pattern and the RPEL are quantitatively characterized. The distributions of both intensity and potential-energy values can be approximated by Γ distributions. They can be tuned from exponential to approximately Gaussian with variable standard deviation, which determines the contrast of the speckles and the roughness of the RPEL. Moreover, the characteristic length scales, e.g., the speckle size, can be controlled. By rotating the diffuser, furthermore, a flat potential can be created and hence only radiation pressure can be exerted on the particles.

  2. Thermal conditions for geothermal energy exploitation in the Transcarpathian depression and surrounding units

    NASA Astrophysics Data System (ADS)

    Majcin, Dušan; Kutas, Roman; Bilčík, Dušan; Bezák, Vladimír; Korchagin, Ignat

    2016-03-01

    The contribution presents the results acquired both by direct cognitive geothermic methods and by modelling approaches of the lithosphere thermal state in the region of the Transcarpathian depression and surrounding units. The activities were aimed at the determination of the temperature field distribution and heat flow density distribution in the upper parts of the Earth's crust within the studied area. Primary new terrestrial heat flow density map was constructed from values determined for boreholes, from their interpretations and from newest outcomes of geothermal modelling methods based on steady-state and transient approaches, and also from other recently gained geophysical and geological knowledge. Thereafter we constructed the maps of temperature field distribution for selected depth levels of up to 5000 m below the surface. For the construction we have used measured borehole temperature data, the interpolation and extrapolation methods, and the modelling results of the refraction effects and of the influences of source type anomalies. New maps and other geothermic data served for the determination of depths with rock temperatures suitable for energy utilization namely production of electric energy minimally by the binary cycles. Consequently the thermal conditions were used to identify the most perspective areas for geothermal energy exploitation in the region under study.

  3. Devices for extracting energy from waves

    SciTech Connect

    Comyns-Carr, C.A.; Platts, M.J.

    1981-09-15

    The invention relates to a device for extracting energy from waves and having a pump arranged to be operated by relative motion between members of the device in response to waves. The pump according to the invention has a pump body with a flexible portion extending between the members so as to define a pump chamber having a volume which varies as a result of the aforesaid relative motion. In one form of the invention the pump body is provided by a tubular bellows comprising elastomeric material. A plurality of such pumps may be disposed between the members, each pump being activated by said relative motion.

  4. Nonlinear Internal Waves - Evolution and Energy Dissipation

    NASA Astrophysics Data System (ADS)

    Orr, M.; Mignerey, P.

    2003-04-01

    Nonlinear internal waves have been observed propagating up the slope of the South China Sea during the recent ONR Asian Seas International Acoustics Experiment. Energy dissipation rates have been extracted. The location of the initiation of the depression to elevation conversion has been identified. Scaling parameters have been extracted and used to initialize a two-layer evolution equation model simulation. Mode1, 2 linear and nonlinear internal waves and instabilities have been observed near the shelf break of the United States of America New Jersey Shelf. Acoustic flow visualization records will be presented. Work supported by the Office of Naval Research (ONR) Ocean Acoustics Program and ONR's NRL base funding.

  5. Association of Ocean Energy Exploitation of Resources Promotion Sea of Japan

    NASA Astrophysics Data System (ADS)

    Aoyama, C.; Aoyama, S.

    2014-12-01

    Nine prefectures of 1 local government prefecture of the Sea of Japan side established "Association of Ocean Energy Exploitation of Resources Promotion Sea of Japan" (the following, Association of Sea of Japan) in September, 2012. They support methane hydrate exploitation of resources of the government and aim at the local activation and job creation. Niigata and Hyogo that were members of the association of Sea of Japan carried out a prefecture original methane hydrate investigation. They appeal to the government for development promotion of the government by showing the result. On the other hand, Wakayama located on the Pacific side wants to appeal to the government for the reexamination of the development sea area by showing that outer layer type methane hydrate exists to the sea area that is nearer the landside than the sea area that the government develops. The Independent Institute carried out collaborative investigation each with Niigata, Hyogo and Wakayama in 2013. I show the results of research. In the joint investigation with Niigata, plural plumes were observed in Mogami trough east slope (from depth of the water 200m 600m) . In the joint investigation with Hyogo, I carried out observation of a methane plume and the structure and the seafloor topography under the sea bottom in Oki east sea area. Furthermore, I performed a piston core ring and gathered five samples and confirmed plural traces of the methane hydrate. In the joint investigation with Wakayama, plural plumes were observed in Shionomisaki canyon (from depth of the water 1,700m 2,200m). There is hardly the report of the plume on the Pacific side so far. Therefore I want to continue observing it in future.

  6. Wave energy transmission apparatus for high-temperature environments

    NASA Technical Reports Server (NTRS)

    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.

  7. DEVELOPING AND EXPLOITING A UNIQUE SEISMIC DATA SET FROM SOUTH AFRICAN GOLD MINES FOR SOURCE CHARACTERIZATION AND WAVE PROPAGATION

    SciTech Connect

    Julia, J; Nyblade, A A; Gok, R; Walter, W R; Linzer, L; Durrheim, R

    2008-07-08

    In this project, we are developing and exploiting a unique seismic data set to address the characteristics of small seismic events and the associated seismic signals observed at local (< 200 km) and regional (< 2000 km) distances. The dataset is being developed using mining-induced events from 3 deep gold mines in South Africa recorded on inmine networks (< 1 km) comprised of tens of high-frequency sensors, a network of 4 broadband stations installed as part of this project at the surface around the mines (1-10 km), and a network of existing broadband seismic stations at local/regional distances (50-1000 km) from the mines. After 1 year of seismic monitoring of mine activity (2007), over 10,000 events in the range -3.4 < ML < 4.4 have been catalogued and recorded by the in-mine networks. Events with positive magnitudes are generally well recorded by the surface-mine stations, while magnitudes 3.0 and larger are seen at regional distances (up to {approx}600 km) in high-pass filtered recordings. We have analyzed in-mine recordings in detail at one of the South African mines (Savuka) to (i) improve on reported hypocentral locations, (ii) verify sensor orientations, and (iii) determine full moment tensor solutions. Hypocentral relocations on all catalogued events have been obtained from P- and S-wave travel-times reported by the mine network operator through an automated procedure that selects travel-times falling on Wadati lines with slopes in the 0.6-0.7 range; sensor orientations have been verified and, when possible, corrected by correlating P-, SV-, and SH-waveforms obtained from theoretical and empirical (polarization filter) rotation angles; full moment tensor solutions have been obtained by inverting P-, SV-, and SH- spectral amplitudes measured on the theoretically rotated waveforms with visually assigned polarities. The relocation procedure has revealed that origin times often necessitate a negative correction of a few tenths of second and that hypocentral

  8. Shock wave generated by high-energy electric spark discharge

    NASA Astrophysics Data System (ADS)

    Liu, Qingming; Zhang, Yunming

    2014-10-01

    Shock wave generated by electric spark discharge was studied experimentally and the shock wave energy was evaluated in this paper. A pressure measurement system was established to study the pressure field of the electric spark discharge process. A series of electric spark discharge experiments were carried out and the energy of the electric spark used in present study was in the range of 10 J, 100 J, and 1000 J, respectively. The shock wave energy released from the electric spark discharge process was calculated by using the overpressure values at different measurement points near the electric spark discharge center. The good consistency of shock wave energies calculated by pressure histories at different measuring points in the same electric spark discharge experiment illustrates the applicability of the weak shock wave theory in calculating the energy of shock wave induced by electric spark discharge process. The result showed that shock wave formed at the initial stage of electric spark discharge process, and the shock wave energy is only a little part of electric spark energy. From the analysis of the shock wave energy and electric spark energy, a good linear relationship between shock wave energy and electric spark energy was established, which make it possible to calculate shock wave energy by measuring characteristic parameters of electric spark discharge process instead of shock wave. So, the initiation energy of direct initiation of detonation can be determined easily by measuring the parameters of electric spark discharge process.

  9. Wave Energy Research, Testing and Demonstration Center

    SciTech Connect

    Batten, Belinda

    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

  10. Exploiting the leaky-wave properties of transmission-line metamaterials for single-microphone direction finding.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Hervé; Mosig, Juan R

    2016-06-01

    A transmission-line acoustic metamaterial is an engineered, periodic arrangement of relatively small unit-cells, the acoustic properties of which can be manipulated to achieve anomalous physical behaviours. These exotic properties open the door to practical applications, such as an acoustic leaky-wave antenna, through the implementation of radiating channels along the metamaterial. In the transmitting mode, such a leaky-wave antenna is capable of steering sound waves in frequency-dependent directions. Used in reverse, the antenna presents a well defined direction-frequency behaviour. In this paper, an acoustic leaky-wave structure is presented in the receiving mode. It is shown that it behaves as a sound source direction-finding device using only one sensor. After a general introduction of the acoustic leaky-wave antenna concept, its radiation pattern and radiation efficiency are expressed in closed form. Then, numerical simulations and experimental assessments of the proposed transmission-line based structure, implementing only one sensor at one termination, are presented. It is shown that such a structure is capable of finding the direction of an incoming sound wave, from backward to forward, based on received sound power spectra. This introduces the concept of sound source localization without resorting to beam-steering techniques based on multiple sensors. PMID:27369150

  11. Internal energy relaxation in shock wave structure

    SciTech Connect

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

    2013-12-15

    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.

  12. New Approaches To Off-Shore Wind Energy Management Exploiting Satellite EO Data

    NASA Astrophysics Data System (ADS)

    Morelli, Marco; Masini, Andrea; Venafra, Sara; Potenza, Marco Alberto Carlo

    2013-12-01

    Wind as an energy resource has been increasingly in focus over the past decades, starting with the global oil crisis in the 1970s. The possibility of expanding wind power production to off-shore locations is attractive, especially in sites where wind levels tend to be higher and more constant. Off-shore high-potential sites for wind energy plants are currently being looked up by means of wind atlases, which are essentially based on NWP (Numerical Weather Prediction) archive data and that supply information with low spatial resolution and very low accuracy. Moreover, real-time monitoring of active off- shore wind plants is being carried out using in-situ installed anemometers, that are not very reliable (especially on long time periods) and that should be periodically substituted when malfunctions or damages occur. These activities could be greatly supported exploiting archived and near real-time satellite imagery, that could provide accurate, global coverage and high spatial resolution information about both averaged and near real-time off-shore windiness. In this work we present new methodologies aimed to support both planning and near-real-time monitoring of off-shore wind energy plants using satellite SAR(Synthetic Aperture Radar) imagery. Such methodologies are currently being developed in the scope of SATENERG, a research project funded by ASI (Italian Space Agency). SAR wind data are derived from radar backscattering using empirical geophysical model functions, thus achieving greater accuracy and greater resolution with respect to other wind measurement methods. In detail, we calculate wind speed from X-band and C- band satellite SAR data, such as Cosmo-SkyMed (XMOD2) and ERS and ENVISAT (CMOD4) respectively. Then, using also detailed models of each part of the wind plant, we are able to calculate the AC power yield expected behavior, which can be used to support either the design of potential plants (using historical series of satellite images) or the

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

    ERIC Educational Resources Information Center

    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…

  14. Estimating Energy Dissipation Due to Wave Breaking in the Surf Zone Using Infrared Imagery

    NASA Astrophysics Data System (ADS)

    Carini, Roxanne J.

    Wave breaking is the largest forcing mechanism in the surf zone. Therefore, quantifying energy dissipation due to wave breaking is important for improving models that seek to predict nearshore circulation, wave-current interactions, air-sea gas exchange, erosion and accretion of sediment, and storm surge. Wave energy dissipation is difficult to measure with in situ instruments, and even the most reliable estimates are limited to point measurements. Using remote sensing technologies, specifically infrared (IR) imagery, the high spatial and temporal variability of wave breaking may be sampled. Duncan (1981) proposed a model (D81) for dissipation on a wave-by-wave basis, based on wave slope and roller length, the crest-perpendicular length of the aerated region of a breaking wave. The wave roller is composed of active foam, which, in thermal IR images, appears brighter than the surrounding water and the residual foam, the foam left behind in the wake of a breaking wave. Using IR imagery taken during the Surf Zone Optics 2010 experiment at Duck, NC, and exploiting the distinct signature of active foam, a retrieval algorithm was developed to identify and extract breaking wave roller length. Roller length was then used to estimate dissipation rate via the D81 formulation. The D81 dissipation rate estimates compare reasonably to in situ dissipation estimates at a point. When the D81 estimates are compared to the bulk energy flux into the surf zone, it is found that wave breaking dissipates approximately 25-36% of the incoming wave energy. The D81 dissipation rate estimates also agree closely with those from a dissipation parameterization proposed by Janssen and Battjes (2007) (JB07) and commonly applied within larger nearshore circulation models. The JB07 formulation, however, requires additional physical parameters (wave height and water depth) that are often sparsely sampled and are difficult to attain from remote sensing alone. The power of the D81 formulation lies in

  15. Exploitation of the Reverberant Propagation of Elastic Waves in Structures: Towards a Concept of Low-resource SHM Sensor Network

    NASA Astrophysics Data System (ADS)

    Moulin, Emmanuel; Benmeddour, Farouk; Achdjian, Hossep; Chehami, Lynda; Assaad, Jamal; de Rosny, Julien; Prada, Claire

    Actual implementation of an efficient SHM system is necessarily hampered by the constraints of power-consumption and intrusive- ness (weight, size, in-service integration) of sensors. In the field of ultrasound-based SHM, conventional methods rely on relatively powerful acoustic sources synchronized with the sensors, and exploit only the first propagated (ballistic) wavepackets. The aim of this paper is to present possible techniques to exploit the whole complexity of reverberation signals, in order to extract the maxi- mum information from limited hardware, software, or power resources. A first aspect is the extraction of statistical properties of the codas of multiply-reflected signals, which can be used to estimate structural properties from a small number of sensors. In this technique, the required signal processing is relatively light and synchronization between the acquisition channels is not necessary. A second aspect is concerned with the possibility of using ambient acoustic sources, naturally present for example in transportation applications, instead of artificial power-consuming ultrasound sources.

  16. 78 FR 40132 - Wave Energy Converter Prize Administration Webinar

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-03

    ... of Energy Efficiency and Renewable Energy Wave Energy Converter Prize Administration Webinar AGENCY: Office of Energy Efficiency and Renewable Energy (EERE), U.S. Department of Energy (DOE). ACTION: Notice... available for public review on the DOE Office of Energy Efficiency and Renewable Energy (EERE) Web site...

  17. Optimisation Of a Magnetostrictive Wave Energy Converter

    NASA Astrophysics Data System (ADS)

    Mundon, T. R.; Nair, B.

    2014-12-01

    Oscilla Power, Inc. (OPI) is developing a patented magnetostrictive wave energy converter aimed at reducing the cost of grid-scale electricity from ocean waves. Designed to operate cost-effectively across a wide range of wave conditions, this will be the first use of reverse magnetostriction for large-scale energy production. The device architecture is a straightforward two-body, point absorbing system that has been studied at length by various researchers. A large surface float is anchored to a submerged heave (reaction) plate by multiple taut tethers that are largely made up of discrete, robust power takeoff modules that house the magnetostrictive generators. The unique generators developed by OPI utilize the phenomenon of reverse magnetostriction, which through the application of load to a specific low cost alloy, can generate significant magnetic flux changes, and thus create power through electromagnetic induction. Unlike traditional generators, the mode of operation is low-displacement, high-force, high damping which in combination with the specific multi-tether configuration creates some unique effects and interesting optimization challenges. Using an empirical approach with a combination of numerical tools, such as ORCAFLEX, and physical models, we investigated the properties and sensitivities of this system arrangement, including various heave plate geometries, with the overall goal of identifying the mass and hydrodynamic parameters required for optimum performance. Furthermore, through a detailed physical model test program at the University of New Hampshire, we were able to study in more detail how the heave plate geometry affects the drag and added mass coefficients. In presenting this work we will discuss how alternate geometries could be used to optimize the hydrodynamic parameters of the heave plate, allowing maximum inertial forces in operational conditions, while simultaneously minimizing the forces generated in extreme waves. This presentation

  18. Wave energy resource assessment based on satellite observations around Indonesia

    NASA Astrophysics Data System (ADS)

    Ribal, Agustinus; Zieger, Stefan

    2016-06-01

    A preliminary assessment of wave energy resource around Indonesian's ocean has been carried out by means of analyzing satellite observations. The wave energy flux or wave power can be approximated using parameterized sea states. Wave power scales with significant wave height, characteristic wave period and water depth. In this approach, the significant wave heights were obtained from ENVISAT (Environmental Satellite) data which have been calibrated. However, as the characteristic wave period is rarely specified and therefore must be estimated from other variables when information about the wave spectra is unknown. Here, the characteristic wave period was calculated with an empirical model that utilizes altimeter estimates of wave height and backscatter coefficient originally proposed. For the Indonesian region, wave power energy is calculated over two periods of one year each and was compared with the results from global hindcast carried out with a recent release of wave model WAVEWATCH III. We found that, the most promising wave power energy regions around the Indonesian archipelago are located in the south of Java island and the south west of Sumatera island. In these locations, about 20 - 30 kW/m (90th percentile: 30-50 kW/m, 99th percentile: 40-60 kW/m) wave power energy on average has been found around south of Java island during 2010. Similar results have been found during 2011 at the same locations. Some small areas which are located around north of Irian Jaya (West Papua) are also very promising and need further investigation to determine its capacity as a wave energy resource.

  19. Real-time Ocean Wave Prediction for Optimal Performance of a Wave Energy Converter

    NASA Astrophysics Data System (ADS)

    Cavaglieri, Daniele; Bewley, Thomas

    2013-11-01

    In recent years, there has been a growing interest in renewable energy. Among all the available possibilities, wave energy conversion, due to the huge availability of energy that the ocean could provide, represents nowadays one of the most promising solutions. However, the efficiency of a wave energy converter for ocean wave energy harvesting is still far from making it competitive with more mature fields of renewable energy, such as solar and wind energy. One of the main problems is related to the inability to accurately predict the profile of oncoming waves approaching the wave energy converter. For this reason, we developed a new hybrid method for state estimation of nonlinear systems, which is based on a variational formulation of an ensemble smoother, combined with the formulation of the ensemble Kalman smoother. This method has been employed for the optimal forecasting of ocean waves via sensors placed on an array of wave energy converters. The coupled simulation of ocean waves and energy devices has been carried out leveraging a nonlinear High Order Spectral code.

  20. Scattered surface wave energy in the seismic coda

    USGS Publications Warehouse

    Zeng, Y.

    2006-01-01

    One of the many important contributions that Aki has made to seismology pertains to the origin of coda waves (Aki, 1969; Aki and Chouet, 1975). In this paper, I revisit Aki's original idea of the role of scattered surface waves in the seismic coda. Based on the radiative transfer theory, I developed a new set of scattered wave energy equations by including scattered surface waves and body wave to surface wave scattering conversions. The work is an extended study of Zeng et al. (1991), Zeng (1993) and Sato (1994a) on multiple isotropic-scattering, and may shed new insight into the seismic coda wave interpretation. The scattering equations are solved numerically by first discretizing the model at regular grids and then solving the linear integral equations iteratively. The results show that scattered wave energy can be well approximated by body-wave to body wave scattering at earlier arrival times and short distances. At long distances from the source, scattered surface waves dominate scattered body waves at surface stations. Since surface waves are 2-D propagating waves, their scattered energies should in theory follow a common decay curve. The observed common decay trends on seismic coda of local earthquake recordings particular at long lapse times suggest that perhaps later seismic codas are dominated by scattered surface waves. When efficient body wave to surface wave conversion mechanisms are present in the shallow crustal layers, such as soft sediment layers, the scattered surface waves dominate the seismic coda at even early arrival times for shallow sources and at later arrival times for deeper events.

  1. Climate change impact on wave energy in the Persian Gulf

    NASA Astrophysics Data System (ADS)

    Kamranzad, Bahareh; Etemad-Shahidi, Amir; Chegini, Vahid; Yeganeh-Bakhtiary, Abbas

    2015-06-01

    Excessive usage of fossil fuels and high emission of greenhouse gases have increased the earth's temperature, and consequently have changed the patterns of natural phenomena such as wind speed, wave height, etc. Renewable energy resources are ideal alternatives to reduce the negative effects of increasing greenhouse gases emission and climate change. However, these energy sources are also sensitive to changing climate. In this study, the effect of climate change on wave energy in the Persian Gulf is investigated. For this purpose, future wind data obtained from CGCM3.1 model were downscaled using a hybrid approach and modification factors were computed based on local wind data (ECMWF) and applied to control and future CGCM3.1 wind data. Downscaled wind data was used to generate the wave characteristics in the future based on A2, B1, and A1B scenarios, while ECMWF wind field was used to generate the wave characteristics in the control period. The results of these two 30-yearly wave modelings using SWAN model showed that the average wave power changes slightly in the future. Assessment of wave power spatial distribution showed that the reduction of the average wave power is more in the middle parts of the Persian Gulf. Investigation of wave power distribution in two coastal stations (Boushehr and Assalouyeh ports) indicated that the annual wave energy will decrease in both stations while the wave power distribution for different intervals of significant wave height and peak period will also change in Assalouyeh according to all scenarios.

  2. Mechanochemistry for Shock Wave Energy Dissipation

    NASA Astrophysics Data System (ADS)

    Shaw, William; Ren, Yi; Su, Zhi; Moore, Jeffrey; Suslick, Kenneth; Dlott, Dana

    2015-06-01

    Using our laser-driven flyer-plate apparatus we have developed a technique for detecting mechanically driven chemical reactions that attenuate shock waves. In these experiments 75 μm laser-driven flyer-plates travel at speeds of up to 2.8 km/s. Photonic Doppler velocimetry is used to monitor both the flight speed and the motions of an embedded mirror behind the sample on the supporting substrate. Since the Hugoniot of the substrate is known, mirror motions can be converted into the transmitted shock wave flux and fluence through a sample. Flux shows the shock profile whereas fluence represents the total energy transferred per unit area, and both are measured as a function of sample thickness. Targets materials are micrograms of carefully engineered organic and inorganic compounds selected for their potential to undergo negative volume, endothermic reactions. In situ fluorescence measurements and a suite of post mortem analytical methods are used to detect molecular chemical reactions that occur due to impact.

  3. Wave energy devices with compressible volumes

    PubMed Central

    Kurniawan, Adi; Greaves, Deborah; Chaplin, John

    2014-01-01

    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 m3 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. PMID:25484609

  4. Diffuse Waves and Energy Densities Near Boundaries

    NASA Astrophysics Data System (ADS)

    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

  5. Spectral wave flow attenuation within submerged canopies: Implications for wave energy dissipation

    NASA Astrophysics Data System (ADS)

    Lowe, Ryan J.; Falter, James L.; Koseff, Jeffrey R.; Monismith, Stephen G.; Atkinson, Marlin J.

    2007-05-01

    Communities of benthic organisms can form very rough surfaces (canopies) on the seafloor. Previous studies have shown that an oscillatory flow induced by monochromatic surface waves will drive more flow inside a canopy than a comparable unidirectional current. This paper builds on these previous studies by investigating how wave energy is attenuated within canopies under spectral wave conditions, or random wave fields defined by many frequencies. A theoretical model is first developed to predict how flow attenuation within a canopy varies among the different wave components and predicts that shorter-period components will generally be more effective at driving flow within a canopy than longer-period components. To investigate the model performance, a field experiment was conducted on a shallow reef flat in which flow was measured both inside and above a model canopy array. Results confirm that longer-period components in the spectrum are significantly more attenuated than shorter-period components, in good agreement with the model prediction. This paper concludes by showing that the rate at which wave energy is dissipated by a canopy is closely linked to the flow structure within the canopy. Under spectral wave conditions, wave energy within a model canopy array is dissipated at a greater rate among the shorter-period wave components. These observations are consistent with previous observations of how wave energy is dissipated by the bottom roughness of a coral reef.

  6. Wave energy dissipation by intertidal sand waves on a mixed-sediment Beach

    USGS Publications Warehouse

    Adams, P.; Ruggiero, P.

    2006-01-01

    Within the surf zone, the energy expended by wave breaking is strongly influenced by nearshore bathymetry, which is often linked to the character and abundance of local sediments. Based upon a continuous, two year record of Argus Beach Monitoring System (ABMS) data on the north shore of Kachemak Bay in southcentral Alaska, we model the enhancement of wave energy dissipation by the presence of intertidal sand waves. Comparison of model results from simulations in the presence and absence of sand waves illustrates that these ephemeral morphological features can offer significant protection to the backing beach and sea cliff through two mechanisms: (1) by moving the locus of wave breaking seaward and (2) by increasing energy expenditure associated with the turbulence of wave breaking. Copyright ASCE 2006.

  7. Wave energy and wave-induced flow reduction by full-scale model Posidonia oceanica seagrass

    NASA Astrophysics Data System (ADS)

    Manca, E.; Cáceres, I.; Alsina, J. M.; Stratigaki, V.; Townend, I.; Amos, C. L.

    2012-12-01

    This paper presents results from experiments in a large flume on wave and flow attenuation by a full-scale artificial Posidonia oceanica seagrass meadow in shallow water. Wave height and in-canopy wave-induced flows were reduced by the meadow under all tested regular and irregular wave conditions, and were affected by seagrass density, submergence and distance from the leading edge. The energy of irregular waves was reduced at all components of the spectra, but reduction was greater at the peak spectral frequency. Energy dissipation factors were largest for waves with small orbital amplitudes and at low wave Reynolds numbers. An empirical model, commonly applied to predict friction factors by rough beds, proved applicable to the P. oceanica bed. However at the lowest Reynolds numbers, under irregular waves, the data deviated significantly from the model. In addition, the wave-induced flow dissipation in the lower canopy increased with increasing wave orbital amplitude and increasing density of the mimics. The analysis of the wave-induced flow spectra confirm this trend: the reduction of flow was greatest at the longer period component of the spectra. Finally, we discuss the implications of these findings for sediment dynamics and the role of P. oceanica beds in protecting the shore from erosion.

  8. Energy and energy flux in axisymmetric slow and fast waves

    NASA Astrophysics Data System (ADS)

    Moreels, M. G.; Van Doorsselaere, T.; Grant, S. D. T.; Jess, D. B.; Goossens, M.

    2015-06-01

    Aims: We aim to calculate the kinetic, magnetic, thermal, and total energy densities and the flux of energy in axisymmetric sausage modes. The resulting equations should contain as few parameters as possible to facilitate applicability for different observations. Methods: The background equilibrium is a one-dimensional cylindrical flux tube model with a piecewise constant radial density profile. This enables us to use linearised magnetohydrodynamic equations to calculate the energy densities and the flux of energy for axisymmetric sausage modes. Results: The equations used to calculate the energy densities and the flux of energy in axisymmetric sausage modes depend on the radius of the flux tube, the equilibrium sound and Alfvén speeds, the density of the plasma, the period and phase speed of the wave, and the radial or longitudinal components of the Lagrangian displacement at the flux tube boundary. Approximate relations for limiting cases of propagating slow and fast sausage modes are also obtained. We also obtained the dispersive first-order correction term to the phase speed for both the fundamental slow body mode under coronal conditions and the slow surface mode under photospheric conditions. Appendix A is available in electronic form at http://www.aanda.org

  9. Wave spectral energy variability in the northeast Pacific

    USGS Publications Warehouse

    Bromirski, P.D.; Cayan, D.R.; Flick, R.E.

    2005-01-01

    The dominant characteristics of wave energy variability in the eastern North Pacific are described from NOAA National Data Buoy Center (NDBC) buoy data collected from 1981 to 2003. Ten buoys at distributed locations were selected for comparison based on record duration and data continuity. Long-period (LP) [T > 12] s, intermediate-period [6 ??? T ??? 12] s, and short-period [T < 6] s wave spectral energy components are considered separately. Empirical orthogonal function (EOF) analyses of monthly wave energy anomalies reveal that all three wave energy components exhibit similar patterns of spatial variability. The dominant mode represents coherent heightened (or diminished) wave energy along the West Coast from Alaska to southern California, as indicated by composites of the 700 hPa height field. The second EOF mode reveals a distinct El Nin??o-Southern Oscillation (ENSO)-associated spatial distribution of wave energy, which occurs when the North Pacific storm track is extended unusually far south or has receded to the north. Monthly means and principal components (PCs) of wave energy levels indicate that the 1997-1998 El Nin??o winter had the highest basin-wide wave energy within this record, substantially higher than the 1982-1983 El Nin??o. An increasing trend in the dominant PC of LP wave energy suggests that storminess has increased in the northeast Pacific since 1980. This trend is emphasized at central eastern North Pacific locations. Patterns of storminess variability are consistent with increasing activity in the central North Pacific as well as the tendency for more extreme waves in the south during El Nin??o episodes and in the north during La Nin??a. Copyright 2005 by the American Geophysical Union.

  10. Numerical modeling of the effects of wave energy converter characteristics on nearshore wave conditions

    DOE PAGESBeta

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

    2015-12-24

    Modeled nearshore wave propagation was investigated downstream of simulated wave energy converters (WECs) to evaluate overall near- and far-field effects of WEC arrays. Model sensitivity to WEC characteristics and WEC array deployment scenarios was evaluated using a modified version of an industry standard wave model, Simulating WAves Nearshore (SWAN), which allows the incorporation of device-specific WEC characteristics to specify obstacle transmission. The sensitivity study illustrated that WEC device type and subsequently its size directly resulted in wave height variations in the lee of the WEC array. Wave heights decreased up to 30% between modeled scenarios with and without WECs formore » large arrays (100 devices) of relatively sizable devices (26 m in diameter) with peak power generation near to the modeled incident wave height. Other WEC types resulted in less than 15% differences in modeled wave height with and without WECs, with lesser influence for WECs less than 10 m in diameter. Wave directions and periods were largely insensitive to changes in parameters. Furthermore, additional model parameterization and analysis are required to fully explore the model sensitivity of peak wave period and mean wave direction to the varying of the parameters.« less

  11. Numerical modeling of the effects of wave energy converter characteristics on nearshore wave conditions

    SciTech Connect

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

    2015-12-24

    Modeled nearshore wave propagation was investigated downstream of simulated wave energy converters (WECs) to evaluate overall near- and far-field effects of WEC arrays. Model sensitivity to WEC characteristics and WEC array deployment scenarios was evaluated using a modified version of an industry standard wave model, Simulating WAves Nearshore (SWAN), which allows the incorporation of device-specific WEC characteristics to specify obstacle transmission. The sensitivity study illustrated that WEC device type and subsequently its size directly resulted in wave height variations in the lee of the WEC array. Wave heights decreased up to 30% between modeled scenarios with and without WECs for large arrays (100 devices) of relatively sizable devices (26 m in diameter) with peak power generation near to the modeled incident wave height. Other WEC types resulted in less than 15% differences in modeled wave height with and without WECs, with lesser influence for WECs less than 10 m in diameter. Wave directions and periods were largely insensitive to changes in parameters. Furthermore, additional model parameterization and analysis are required to fully explore the model sensitivity of peak wave period and mean wave direction to the varying of the parameters.

  12. Extended emission wavelength of random dye lasers by exploiting radiative and non-radiative energy transfer

    NASA Astrophysics Data System (ADS)

    Wan Ismail, Wan Zakiah; Goldys, Ewa M.; Dawes, Judith M.

    2016-02-01

    We demonstrate long-wavelength operation (>700 nm) of random dye lasers (using a methylene blue dye) with the addition of rhodamine 6G and titania, enabled by radiative and non-radiative energy transfer. The pump energy is efficiently absorbed and transferred to the acceptors, to support lasing in random dye lasers in the near infrared. The optimum random laser performance with the highest emission intensity and the lowest lasing threshold was achieved for a concentration of methylene blue as the acceptor equal to 6× the concentration of rhodamine 6G (donor). Excessive levels of methylene blue increased the lasing threshold and broadened the methylene blue emission linewidth due to dye quenching from re-absorption. This is due to competition between the donor emission and energy transfer and between absorption loss and fluorescence quenching. The radiative and non-radiative energy transfer is analyzed as a function of the acceptor concentration and pump energy density, with consideration of the spectral overlap. The dependence of the radiative and non-radiative transfer efficiency on the acceptor concentration is obtained, and the energy transfer parameters, including the radiative and non-radiative energy transfer rate constants ( K R and K NR), are investigated using Stern-Volmer analysis. The analysis indicates that radiative energy transfer is the dominant energy transfer mechanism in this system.

  13. Software augmented buildings: Exploiting existing infrastructure to improve energy efficiency and comfort in commercial buildings

    NASA Astrophysics Data System (ADS)

    Balaji, Bharathan

    Commercial buildings consume 19% of energy in the US as of 2010, and traditionally, their energy use has been optimized through improved equipment efficiency and retrofits. Beyond improved hardware and infrastructure, there exists a tremendous potential in reducing energy use through better monitoring and operation. We present several applications that we developed and deployed to support our thesis that building energy use can be reduced through sensing, monitoring and optimization software that modulates use of building subsystems including HVAC. We focus on HVAC systems as these constitute 48-55% of building energy use. Specifically, in case of sensing, we describe an energy apportionment system that enables us to estimate real-time zonal HVAC power consumption by analyzing existing sensor information. With this energy breakdown, we can measure effectiveness of optimization solutions and identify inefficiencies. Central to energy efficiency improvement is determination of human occupancy in buildings. But this information is often unavailable or expensive to obtain using wide scale sensor deployment. We present our system that infers room level occupancy inexpensively by leveraging existing WiFi infrastructure. Occupancy information can be used not only to directly control HVAC but also to infer state of the building for predictive control. Building energy use is strongly influenced by human behaviors, and timely feedback mechanisms can encourage energy saving behavior. Occupants interact with HVAC using thermostats which has shown to be inadequate for thermal comfort. Building managers are responsible for incorporating energy efficiency measures, but our interviews reveal that they struggle to maintain efficiency due to lack of analytical tools and contextual information. We present our software services that provide energy feedback to occupants and building managers, improves comfort with personalized control and identifies energy wasting faults. For wide

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

    SciTech Connect

    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

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

    PubMed

    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

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

    PubMed Central

    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

  17. Relationship between directions of wave and energy propagation for cold plasma waves

    NASA Technical Reports Server (NTRS)

    Musielak, Zdzislaw E.

    1986-01-01

    The dispersion relation for plasma waves is considered in the 'cold' plasma approximation. General formulas for the dependence of the phase and group velocities on the direction of wave propagation with respect to the local magnetic field are obtained for a cold magnetized plasma. The principal cold plasma resonances and cut-off frequencies are defined for an arbitrary angle and are used to establish basic regimes of frequency where the cold plasma waves can propagate or can be evanescent. The relationship between direction of wave and energy propagation, for cold plasma waves in hydrogen atmosphere, is presented in the form of angle diagrams (angle between group velocity and magnetic field versus angle between phase velocity and magnetic field) and polar diagrams (also referred to as 'Friedrich's diagrams') for different directions of wave propagation. Morphological features of the diagrams as well as some critical angles of propagation are discussed.

  18. Wave Turbulence in Superfluid {sup 4}He: Energy Cascades and Rogue Waves in the Laboratory

    SciTech Connect

    Efimov, V. B.; Ganshin, A. N.; McClintock, P. V. E.; Kolmakov, G. V.; Mezhov-Deglin, L. P.

    2008-11-13

    Recent work on second sound acoustic turbulence in superfluid {sup 4}He is reviewed. Observations of forward and inverse energy cascades are described. The onset of the inverse cascade occurs above a critical driving energy and it is accompanied by giant waves that constitute an acoustic analogue of the rogue waves that occasionally appear on the surface of the ocean. The theory of the phenomenon is outlined and shown to be in good agreement with the experiments.

  19. Non-templated ambient nanoperforation of graphene: a novel scalable process and its exploitation for energy and environmental applications

    NASA Astrophysics Data System (ADS)

    Jhajharia, Suman Kumari; Selvaraj, Kaliaperumal

    2015-11-01

    Nano-perforation of 2D graphene sheets is a recent and strategically significant means to exploit such materials in modern applications such as energy production and storage. However, current options for the synthesis of holey graphene (hG) through nano-perforation of graphene involve industrially undesirable steps viz., usage of expensive/noble metal or silica nanoparticle templates and/or hazardous chemicals. This severely hampers its scope for large scale production and further exploitation. Herein, we report for the first time a scalable non-templated route to produce hG at ambient conditions. Nano-perforation is achieved with tunable pore size via the simple few layer co-assembly of silicate-surfactant admicelles along the surface of graphene oxide. A gentle alkali treatment and a reduction at optimized conditions readily yielded holey graphene with a remarkable capacitance (~250 F g-1) and interesting adsorption abilities for pollutants. Density functional theory based computational studies reveal interesting insights on the template free nano-perforation at a molecular level. This simple rapid process not only excludes the need for expensive templates and harmful chemicals to yield hG at attractively ambient, chemically placid and industrially safer conditions, but also creates no hurdles in terms of scaling up.Nano-perforation of 2D graphene sheets is a recent and strategically significant means to exploit such materials in modern applications such as energy production and storage. However, current options for the synthesis of holey graphene (hG) through nano-perforation of graphene involve industrially undesirable steps viz., usage of expensive/noble metal or silica nanoparticle templates and/or hazardous chemicals. This severely hampers its scope for large scale production and further exploitation. Herein, we report for the first time a scalable non-templated route to produce hG at ambient conditions. Nano-perforation is achieved with tunable pore size

  20. Solar Thermal Energy Exploitation: An Opportunity to Enhance Conceptual Learning in Physics

    NASA Astrophysics Data System (ADS)

    Rodrigues, M. A.; Cravino, J. P.; Liberato, M. L. R.

    2010-05-01

    In a society mainly driven by Science and Technology it is becoming consensual the idea that scientific education should include three components: Education in Science, Education about Science and Education through Science. Some authors suggest that, in education, everyday objects should be used to illustrate scientific issues (e.g. Andrée, 2005). Thus the goal of this study is two-fold: first, to develop a teaching and learning strategy, in the framework of Education for Sustainable Development (ESD), concerning the renewable energy issue, while showing the importance of using everyday situations in the improvement of students' motivation in Physics learning. Energy is the core concept in this study. Energy conservation includes the concepts applied to sustainable balance between environment and the energy availability and use. Dias et al. (2004) stress that education is one of the best ways to transform the human behavior for the rational use of energy, which represents a long-term investment. In this work students become aware and recognize the importance and value of energy in everyday life, they identify energy transfer and transformation processes, confirm energy availability, relating these topics to present human needs and climate change issues. A didactic model of a solar thermal panel has thus been built, using cheap, common materials, by 15-16 year-old Physics students, from a Portuguese secondary school. Students had to plan the experiments, in small groups, to identify and estimate physical magnitudes and to explore how to maximize the solar thermal panel efficiency. The experimental activities took place in the school's playground, in a place where there were no obstacles to capturing solar radiation. Finally, students had to deal with experimental data acquisition and analysis, they had to prepare a report, as well as to answer a survey, to evaluate their learning success. Results show that students appreciated the proposed themes and activities

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

    PubMed

    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. PMID:22184670

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

    NASA Astrophysics Data System (ADS)

    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

  3. Internal wave energy radiated from a turbulent mixed layer

    NASA Astrophysics Data System (ADS)

    Munroe, James R.; Sutherland, Bruce R.

    2014-09-01

    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.

  4. Internal wave energy radiated from a turbulent mixed layer

    SciTech Connect

    Munroe, James R.; Sutherland, Bruce R.

    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.

  5. Experimental study of breaking and energy dissipation in surface waves

    NASA Astrophysics Data System (ADS)

    Ruiz Chavarria, Gerardo; Le Gal, Patrice; Le Bars, Michael

    2014-11-01

    We present an experimental study of the evolution of monochromatic waves produced by a parabolic wave maker. Because of the parabolic shape of the wave front, the waves exhibit spatial focusing and their amplitude dramatically increases over distances of a few wavelengths. Unlike linear waves, the amplitude of the free surface deformation cannot exceed a certain threshold and when this happens the waves break. In order to give a criterion for the appearance of breaking, we calculate the steepness defined as ɛ = H/ λ (where H is the wave height and λ their wavelength) for waves of frequencies in the range 4-10 Hz. We found that wave breaking develops when ɛ attains approximately a value of 0.10. We also evaluate the lost of energy carried by the waves during their breaking by a detailed and accurate measurement of their amplitude using an optical Fourier transform profilometry. G. Ruiz Chavarria acknowledges DGAPA-UNAM by support under Project IN 116312 (Vorticidad y ondas no lineales en fluidos).

  6. Simulation of coastal wave spectra energy from ENVISAT satellite data

    NASA Astrophysics Data System (ADS)

    Marghany, Maged

    2014-06-01

    In the last two decades, scientists have developed several powerful techniques to retrieve energy from natural sources such as a sun radiations, oceans and winds. This study is aimed at stimulating wave energy from large scale synthetic aperture radar (SAR) during different monsoon periods. In doing so, the nonlinear velocity bunching algorithm is used to retrieve the information of ocean wave spectra parameters such as significant wave height, directions, and energy on offshore, midshore, and onshore. Therefore, the maximum peak of the wave energy spectra density of 1.4 m2 s has occurred during northeast monsoon period. It is clear that the mid-shore and onshore has the highest peak of 0.8 and 1.37 m2 s, respectively as compared to offshore. In conclusions, a nonlinear algorithm of velocity bunching can be used to retrieve the significant wave height from synthetic aperture radar (SAR). In addition, SAR can be used to map the distribution of ocean wave spectra energy and determined the potential energy zone in Malaysia coastal waters.

  7. Ocean Wave Energy Regimes of the Circumpolar Coastal Zones

    NASA Astrophysics Data System (ADS)

    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.

  8. Shackleton Energy enabling Space Resources Exploitation on the Moon within a Decade

    NASA Astrophysics Data System (ADS)

    Keravala, J.; Stone, B.; Tietz, D.; Frischauf, N.

    2013-09-01

    Access to in-space natural resources is a key requirement for increasing exploration and expansion of humanity off Earth. In particular, making use of the Moon's resources in the form of lunar polar ice to fuel propellant depots at key locations in near Earth space enables dramatic reductions in the cost of access and operations in space, while simultaneously leveraging reusable in-space transporters essential to opening the newspace highway system. Success of this private venture will provide for a sustained balance of our terrestrial economy and the growth of our civilisation. Establishing the cis-Lunar highway required to access lunar sourced water from the cold traps of the polar craters provides the backbone infrastructure for an exponential growth of a space-based economy. With that core infrastructure in place, space-based solar power generation systems, debris mitigation capabilities and planetary protection systems plus scientific and exploratory missions, among others, can become commercial realities in our lifetime. Shackleton Energy was founded from the space, mining, energy and exploration sectors to meet this challenge as a fully private venture. Following successful robotic precursor missions, our industrial astronauts combined with a robotic mining capability will make first landings at the South Pole of the Moon and begin deliveries of propellant to our depots in within a decade. Customers, partners, technologies and most importantly, the investor classes aligned with the risk profiles involved, have been identified and all the components for a viable business are available. Infrastructure investment in space programs has traditionally been the province of governments, but sustainable expansion requires commercial leadership and this is now the responsibility of a dynamic new industry. The technologies and know-how are ready to be applied. Launch services to LEO are available and the industrial capability exists in the aerospace, mining and energy

  9. Equilibrium shoreline response of a high wave energy beach

    NASA Astrophysics Data System (ADS)

    Yates, M. L.; Guza, R. T.; O'Reilly, W. C.; Hansen, J. E.; Barnard, P. L.

    2011-04-01

    Four years of beach elevation surveys at Ocean Beach, San Francisco, California, are used to extend an existing equilibrium shoreline change model, previously calibrated with fine sand and moderate energy waves, to medium sand and higher-energy waves. The shoreline, characterized as the cross-shore location of the mean high water contour, varied seasonally by between 30 and 60 m, depending on the alongshore location. The equilibrium shoreline change model relates the rate of horizontal shoreline displacement to the hourly wave energy E and the wave energy disequilibrium, the difference between E and the equilibrium wave energy that would cause no change in the present shoreline location. Values for the model shoreline response coefficients are tuned to fit the observations in 500 m alongshore segments and averaged over segments where the model has good skill and the estimated effects of neglected alongshore sediment transport are relatively small. Using these representative response coefficients for 0.3 mm sand from Ocean Beach and driving the model with much lower-energy winter waves observed at San Onofre Beach (also 0.3 mm sand) in southern California, qualitatively reproduces the small seasonal shoreline fluctuations at San Onofre. This consistency suggests that the shoreline model response coefficients depend on grain size and may be constant, and thus transportable, between sites with similar grain size and different wave climates. The calibrated model response coefficients predict that for equal fluctuations in wave energy, changes in shoreline location on a medium-grained (0.3 mm) beach are much smaller than on a previously studied fine-grained (0.2 mm) beach.

  10. Equilibrium shoreline response of a high wave energy beach

    USGS Publications Warehouse

    Yates, M.L.; Guza, R.T.; O'Reilly, W. C.; Hansen, J.E.; Barnard, P.L.

    2011-01-01

    Four years of beach elevation surveys at Ocean Beach, San Francisco, California, are used to extend an existing equilibrium shoreline change model, previously calibrated with fine sand and moderate energy waves, to medium sand and higher-energy waves. The shoreline, characterized as the cross-shore location of the mean high water contour, varied seasonally by between 30 and 60 m, depending on the alongshore location. The equilibrium shoreline change model relates the rate of horizontal shoreline displacement to the hourly wave energy E and the wave energy disequilibrium, the difference between E and the equilibrium wave energy that would cause no change in the present shoreline location. Values for the model shoreline response coefficients are tuned to fit the observations in 500 m alongshore segments and averaged over segments where the model has good skill and the estimated effects of neglected alongshore sediment transport are relatively small. Using these representative response coefficients for 0.3 mm sand from Ocean Beach and driving the model with much lower-energy winter waves observed at San Onofre Beach (also 0.3 mm sand) in southern California, qualitatively reproduces the small seasonal shoreline fluctuations at San Onofre. This consistency suggests that the shoreline model response coefficients depend on grain size and may be constant, and thus transportable, between sites with similar grain size and different wave climates. The calibrated model response coefficients predict that for equal fluctuations in wave energy, changes in shoreline location on a medium-grained (0.3 mm) beach are much smaller than on a previously studied fine-grained (0.2 mm) beach. Copyright ?? 2011 by the American Geophysical Union.

  11. An array effect of wave energy farm buoys

    NASA Astrophysics Data System (ADS)

    Kweon, Hyuck-Min; Lee, Jung-Lyul

    2012-12-01

    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.

  12. Energy Efficient IoT Data Collection in Smart Cities Exploiting D2D Communications.

    PubMed

    Orsino, Antonino; Araniti, Giuseppe; Militano, Leonardo; Alonso-Zarate, Jesus; Molinaro, Antonella; Iera, Antonio

    2016-01-01

    Fifth Generation (5G) wireless systems are expected to connect an avalanche of "smart" objects disseminated from the largest "Smart City" to the smallest "Smart Home". In this vision, Long Term Evolution-Advanced (LTE-A) is deemed to play a fundamental role in the Internet of Things (IoT) arena providing a large coherent infrastructure and a wide wireless connectivity to the devices. However, since LTE-A was originally designed to support high data rates and large data size, novel solutions are required to enable an efficient use of radio resources to convey small data packets typically exchanged by IoT applications in "smart" environments. On the other hand, the typically high energy consumption required by cellular communications is a serious obstacle to large scale IoT deployments under cellular connectivity as in the case of Smart City scenarios. Network-assisted Device-to-Device (D2D) communications are considered as a viable solution to reduce the energy consumption for the devices. The particular approach presented in this paper consists in appointing one of the IoT smart devices as a collector of all data from a cluster of objects using D2D links, thus acting as an aggregator toward the eNodeB. By smartly adapting the Modulation and Coding Scheme (MCS) on the communication links, we will show it is possible to maximize the radio resource utilization as a function of the total amount of data to be sent. A further benefit that we will highlight is the possibility to reduce the transmission power when a more robust MCS is adopted. A comprehensive performance evaluation in a wide set of scenarios will testify the achievable gains in terms of energy efficiency and resource utilization in the envisaged D2D-based IoT data collection. PMID:27338385

  13. Energy Efficient IoT Data Collection in Smart Cities Exploiting D2D Communications

    PubMed Central

    Orsino, Antonino; Araniti, Giuseppe; Militano, Leonardo; Alonso-Zarate, Jesus; Molinaro, Antonella; Iera, Antonio

    2016-01-01

    Fifth Generation (5G) wireless systems are expected to connect an avalanche of “smart” objects disseminated from the largest “Smart City” to the smallest “Smart Home”. In this vision, Long Term Evolution-Advanced (LTE-A) is deemed to play a fundamental role in the Internet of Things (IoT) arena providing a large coherent infrastructure and a wide wireless connectivity to the devices. However, since LTE-A was originally designed to support high data rates and large data size, novel solutions are required to enable an efficient use of radio resources to convey small data packets typically exchanged by IoT applications in “smart” environments. On the other hand, the typically high energy consumption required by cellular communications is a serious obstacle to large scale IoT deployments under cellular connectivity as in the case of Smart City scenarios. Network-assisted Device-to-Device (D2D) communications are considered as a viable solution to reduce the energy consumption for the devices. The particular approach presented in this paper consists in appointing one of the IoT smart devices as a collector of all data from a cluster of objects using D2D links, thus acting as an aggregator toward the eNodeB. By smartly adapting the Modulation and Coding Scheme (MCS) on the communication links, we will show it is possible to maximize the radio resource utilization as a function of the total amount of data to be sent. A further benefit that we will highlight is the possibility to reduce the transmission power when a more robust MCS is adopted. A comprehensive performance evaluation in a wide set of scenarios will testify the achievable gains in terms of energy efficiency and resource utilization in the envisaged D2D-based IoT data collection. PMID:27338385

  14. Fluctuations of energy flux in wave turbulence.

    PubMed

    Falcon, Eric; Aumaître, Sébastien; Falcón, Claudio; Laroche, Claude; Fauve, Stéphan

    2008-02-15

    We report that the power driving gravity and capillary wave turbulence in a statistically stationary regime displays fluctuations much stronger than its mean value. We show that its probability density function (PDF) has a most probable value close to zero and involves two asymmetric roughly exponential tails. We understand the qualitative features of the PDF using a simple Langevin-type model. PMID:18352479

  15. Airfoil-based piezoelectric energy harvesting by exploiting the pseudoelastic hysteresis of shape memory alloy springs

    NASA Astrophysics Data System (ADS)

    de Sousa, Vagner Candido; De Marqui Junior, Carlos

    2015-12-01

    The modeling and analysis of an electromechanically coupled typical aeroelastic section with shape memory alloy springs for wind energy harvesting is addressed in this paper. An airfoil with two-degrees-of-freedom, namely pitch and plunge, is considered and piezoelectric coupling is added to the plunge degree-of-freedom. A load resistance is assumed in the electrical domain of the problem in order to estimate the electrical power output. Shape memory alloy coil springs are modeled in the pitch degree-of-freedom of the typical section. A nickel-titanium alloy that exhibits pseudoelasticity at room temperature is assumed. The constitutive model for the shape memory alloy is based on classical phenomenological models. The unsteady aerodynamic loads are obtained by Jones’ approximation to Wagner’s indicial function. The resulting nonlinear electroaeroelastic model is cast into a state-space representation and solved with a Runge-Kutta method. The effects of preload values of the shape memory springs and resistive power generation on the aeroelastic behavior of the wind energy harvester are investigated at the flutter boundary and in a post-flutter regime. The nonlinear kinetics of the austenite-to-martensite phase transformation changes the typical linear flutter behavior to stable limit-cycle oscillations over a range of airflow speeds. Such nonlinear aeroelastic behavior introduced by the hysteretic behavior of the SMA springs provides an important source of persistent electrical power.

  16. Energy Absorption Structure of Laser Supported Detonation Wave

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Yamaguchi, Toshikazu; Hatai, Keigo; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2010-05-01

    In Repetitive Pulsed (RP) laser propulsion, when the high energy laser beam is focused in the thruster, Laser Supported Detonation (LSD) wave is generated. This LSD wave converts the laser energy to the enthalpy of the blast wave, which will then apply impulse to the wall of the thruster. Therefore, the energy absorption structure and sustaining condition of LSD wave are important to be understood, which was still not clear though some visualized experiments have been conducted by Ushio et al. before. In this paper, 2-wavelength Mach-Zehnder interferometry is brought to investigate the electron density distribution of LSD area. At the same time, the temperature of the laser induced plasma is measured by an emission spectroscopy experiment, and calculated based on the assumption of local thermal equilibrium. The results show that in LSD, the electron density has a peak (as high as 2×1024[m-3]) behind the shock wave. The irradiated laser can be entirely absorbed before reaching the position of this peak. As a result, a new peak is always generating in front of the old one and this propagating has the same velocity as that of the blast wave. In this way, high heating ratio is sustained right after the shock front. However, as the laser pulse energy becomes lower, the propagating peak cannot catch up with the blast wave anymore, which leads to a termination of the LSD wave. From this study, it is found that for sustaining the LSD wave, a sufficiently thin laser absorption layer is necessary.

  17. Broadband energy harvesting by exploiting nonlinear oscillations around the second vibration mode of a rectangular piezoelectric bistable laminate

    NASA Astrophysics Data System (ADS)

    Li, Hao; Dai, Fuhong; Du, Shanyi

    2015-04-01

    Recently bistable composite laminates have been investigated for broadband energy harvesting, by taking advantage of their nonlinear oscillations around the first vibration mode. However, it has been reported that the excitation acceleration needed for the desired large amplitude limit cycle oscillation is too high, if the first vibration mode is elevated to relative higher frequencies (60 Hz e.g.). This study investigates the feasibility of exploiting the nonlinear oscillations around the second vibration mode of a rectangular piezoelectric bistable laminate (RPBL), for broadband vibration energy harvesting at relative higher frequencies, but with relative low excitation acceleration. The proposed RPBL has three oscillation patterns around the second vibration mode, including single-well oscillation, chaotic intermittency oscillation and limit cycle oscillation. The broadband characteristics and the considerable energy conversion efficiency of the RPBL are demonstrated in experiments. The static nonlinearity and the dynamic responses of the RPBL are investigated by finite element method. Finite element analysis (FEA) reveals that the enhanced dynamic responses of the RPBL are due to its softening bending stiffness and the local snap through phenomenon. The FEA results coincide reasonably well with experimental results.

  18. Statistical analysis and modeling of seismicity related to the exploitation of geothermal energy

    NASA Astrophysics Data System (ADS)

    Dinske, Carsten; Langenbruch, Cornelius; Shapiro, Serge

    2016-04-01

    Geothermal energy is an integral and important part of renewables but it is frequently observed that its production induces seismicity. Here we analyse in detail seismicity from two hydrothermal reservoirs in Germany and one hydrothermal field in Italy. We focus on temporal changes of seismicity rates. This study was motivated by the results of numerical simulations. The modeling of stress changes caused by the injection and production of fluids revealed that the seismicity rate should decrease on a long-term perspective which does not match the observed seismicity rates. To understand this mismatch we analyse the waiting time distributions of the seismic events in both time domain (inter event times) and fluid volume domain (inter event volume). We find clear indications that the observed seismicity contains two components: (1) seismicity that is directly triggered by the production and re-injection of fluid, in other words, induced events, and (2) seismicity that is triggered by earthquake interactions also known as aftershock triggering. In order to calibrate and better constrain our numerical simulations using the induced seismicity we apply a catalog declustering the separate the two components and remove the aftershocks from the observed catalogs. We use the magnitude-dependent space-time windowing approach introduced by Gardener and Knopoff (1974) and tested several published algorithms to calculate the windows. We choose the final space-time window for a given catalog based on the waiting time distribution of the events after the declustering. Technically speaking, we suppose that the probability density of waiting times in the fluid volume domain corresponds to a homogeneous Poisson process (HPP, Langenbruch et al., 2011). After catalog declustering, we conclude that the different reservoirs show a comparable response to the production and re-injection of fluids and the additional triggering of seismicity by earthquake interactions. The declustered

  19. Exploiting Free-Energy Minima to Design Novel EphA2 Protein-Protein Antagonists: From Simulation to Experiment and Return.

    PubMed

    Russo, Simonetta; Callegari, Donatella; Incerti, Matteo; Pala, Daniele; Giorgio, Carmine; Brunetti, Jlenia; Bracci, Luisa; Vicini, Paola; Barocelli, Elisabetta; Capoferri, Luigi; Rivara, Silvia; Tognolini, Massimiliano; Mor, Marco; Lodola, Alessio

    2016-06-01

    The free-energy surface (FES) of protein-ligand binding contains information useful for drug design. Here we show how to exploit a free-energy minimum of a protein-ligand complex identified by metadynamics simulations to design a new EphA2 antagonist with improved inhibitory potency. PMID:27139720

  20. Dark energy and normalization of the cosmological wave function

    NASA Astrophysics Data System (ADS)

    Huang, Peng; Huang, Yue; Li, Miao; Li, Nan

    2016-08-01

    Dark energy is investigated from the perspective of quantum cosmology. It is found that, together with an appropriate normal ordering factor q, only when there is dark energy can the cosmological wave function be normalized. This interesting observation may require further attention.

  1. Characterization of energy trapping in a bulk acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    Kokkonen, Kimmo; Meltaus, Johanna; Pensala, Tuomas; Kaivola, Matti

    2010-12-01

    Acoustic wave fields both within the active electrode area of a solidly mounted 1.8 GHz bulk acoustic wave resonator, and around it in the surrounding region, are measured using a heterodyne laser interferometer. Plate-wave dispersion diagrams for both regions are extracted from the measurement data. The experimental dispersion data reveal the cutoff frequencies of the acoustic vibration modes in the region surrounding the resonator, and, therefore, the energy trapping range of the resonator can readily be determined. The measured dispersion properties of the surrounding region, together with the abruptly diminishing amplitude of the dispersion curves in the resonator, signal the onset of acoustic leakage from the resonator. This information is important for verifying and further developing the simulation tools used for the design of the resonators. Experimental wave field images, dispersion diagrams for both regions, and the threshold for energy leakage are discussed.

  2. Optimal geometry of an axisymmetric wave energy converter

    NASA Astrophysics Data System (ADS)

    Edwards, Emma; Yue, Dick K. P.; Vortical Flow Research Laboratory Team

    2015-11-01

    There have been a number of theoretical, experimental and pilot-scale studies on wave energy converters with varying shapes and designs, but due to the complex nature of wave-body hydrodynamics, as yet there is not one single three-dimensional shape that is agreed-upon to be optimal for wave power extraction. Our objective is to determine the optimal geometry to maximize power uptake over a spectrum of incident waves. As an initial investigation, we consider an axisymmetric floating wave power extraction device operating in heave. We assume linear wave conditions. The body geometry is described by smooth polynomial basis functions and is allowed to be completely general, subject to simple constraints. We consider a linear power uptake with a fixed damping coefficient (which could be optimized). For each frequency in the spectrum, hydrodynamic coefficients are calculated using a linear frequency-domain panel method. Then, for a specific incident wave spectrum, maximal extractable power is integrated over the entire spectrum. We will discuss the optimal geometry and associated maximum power for different geometrical constraints and wave conditions.

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

    PubMed

    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. PMID:27294983

  4. The South Carolina Coastal Erosion Study: Wind Wave Energy Dissipation

    NASA Astrophysics Data System (ADS)

    Demir, H.; Work, P. A.; Voulgaris, G.

    2004-12-01

    As part of the South Carolina Coastal Erosion Study (SCCES) wave and current data were collected offshore of Myrtle Beach, SC for 2 months in 2001-02. This field measurement campaign was the second of a three-part experiment series. While the overall objective of the study is to describe the processes governing the circulation, wave propagation and sediment transport along the northern South Carolina coast, this presentation focuses on the wave energy dissipation over a heterogeneous seafloor over a distance of 6 km. The data were collected between November 9, 2001 and January 17, 2002. The instruments were placed along a transect crossing a large sand shoal in an area otherwise largely deprived of sand, at depths of 8 to 12 meters. The four instruments used, in order of decreasing distance from shore, were 600 and1200 KHz RDI ADCP's, a Nortek Aquadopp and a Sontek Argonaut-XR. Bathymetry and bottom characteristics such as depth and thickness of sand layer are available through USGS's coastal relief model and side scan surveys. Wind data are supplied by a large-scale numerical wind model. Its output is compared with wind data collected at Frying Pan Shoals buoy and at an anemometer placed at Spring Maid pier after the experiment. The SWAN wave model (Booij et al. 1999) was used to model the spectral wave transformation from the offshore buoy to the inner stations and to compare the observed wave energy dissipation to the available models. There was no extreme storm event during the deployment period. The maximum significant wave height observed was 1.6 meters at the offshore wave station, and the mean wave height was 0.8 meters. The mean period was between 5 and 7 seconds most of the time. Significant wave energy dissipation (up to 40% decrease in wave energy flux) across 6 km was observed. A shift of the spectral peak and a change in the spectral shape was observed in many events, which were not generally reproduced by the model. Sand and rock bottom

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

    NASA Technical Reports Server (NTRS)

    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. Exploiting sugarcane for energy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Energycane can be described as sugarcane varieties with fiber content that is higher than the level seen in sugarcane varieties used for commercial sugar production. This fiber content is composed of cellulose, hemicellulose, and lignin. Approximately 70 percent of the dry weight of sugarcane is cel...

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

    SciTech Connect

    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.

  8. Maximum gravitational-wave energy emissible in magnetar flares

    SciTech Connect

    Corsi, Alessandra; Owen, Benjamin J.

    2011-05-15

    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 ({approx}10{sup 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{sup 48}-10{sup 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.

  9. Solar energy converter using surface plasma waves

    NASA Technical Reports Server (NTRS)

    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.

  10. General theory for apparent energy distribution of sea waves

    NASA Astrophysics Data System (ADS)

    Wu, Ke-Jian; Sun, Fu

    1997-12-01

    This paper presents a general theory for the apparent energy distribution of sea waves. Using the joint distribution of wave periods and heights proposed earlier by the second author, the authors define the generalized apparent energy distribution and derive the analytical form of the so called generalized outer frequency spectrum or nth-order frequency spectrum. Some possible relationships between it and the Fourier frequency spectrum are discussed. It is shown that the widely used Bretschneider spectrum can be easily obtained from the above definition and that generalized outer frequency spectrum has equilibrium range with exponent -( n+3) whose upper limit is -3.

  11. On the use of nonlinear solitary waves for energy harvesting

    NASA Astrophysics Data System (ADS)

    Li, Kaiyuan; Rizzo, Piervincenzo

    2015-04-01

    In the last decade there has been an increasing attention on the use of highly- and weakly- nonlinear solitary waves in engineering and physics. These waves can form and travel in nonlinear systems such as one-dimensional chains of spherical particles. One engineering application of solitary waves is the fabrication of acoustic lenses, which are employed in a variety of fields ranging from biomedical imaging and surgery to defense systems and damage detection. In this paper we propose to couple an acoustic lens to a wafer-type lead zirconate titanate transducer (PZT) to harvest energy from the vibration of an object tapping the lens. The lens is composed of a circle array made of chains of particles in contact with a polycarbonate material where the nonlinear waves coalesce into linear waves. The PZT located at the designed focal point converts the mechanical energy carried by the stress wave into electricity to power a load resistor. The performance of the designed harvester is compared to a conventional cantilever beam, and the experimental results show that the power generated with the nonlinear lens has the same order of magnitude of the beam.

  12. Wave energy estimation by using a statistical analysis and wave buoy data near the southern Caspian Sea

    NASA Astrophysics Data System (ADS)

    Zamani, A. R.; Badri, M. A.

    2015-04-01

    Statistical analysis was done on simultaneous wave and wind using data recorded by discus-shape wave buoy. The area is located in the southern Caspian Sea near the Anzali Port. Recorded wave data were obtained through directional spectrum wave analysis. Recorded wind direction and wind speed were obtained through the related time series as well. For 12-month measurements (May 25 2007-2008), statistical calculations were done to specify the value of nonlinear auto-correlation of wave and wind using the probability distribution function of wave characteristics and statistical analysis in various time periods. The paper also presents and analyzes the amount of wave energy for the area mentioned on the basis of available database. Analyses showed a suitable comparison between the amounts of wave energy in different seasons. As a result, the best period for the largest amount of wave energy was known. Results showed that in the research period, the mean wave and wind auto correlation were about three hours. Among the probability distribution functions, i.e Weibull, Normal, Lognormal and Rayleigh, "Weibull" had the best consistency with experimental distribution function shown in different diagrams for each season. Results also showed that the mean wave energy in the research period was about 49.88 kW/m and the maximum density of wave energy was found in February and March, 2010.

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

    SciTech Connect

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

    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.

  14. Protocol to Exploit Waiting Resources for UASNs.

    PubMed

    Hung, Li-Ling; Luo, Yung-Jeng

    2016-01-01

    The transmission speed of acoustic waves in water is much slower than that of radio waves in terrestrial wireless sensor networks. Thus, the propagation delay in underwater acoustic sensor networks (UASN) is much greater. Longer propagation delay leads to complicated communication and collision problems. To solve collision problems, some studies have proposed waiting mechanisms; however, long waiting mechanisms result in low bandwidth utilization. To improve throughput, this study proposes a slotted medium access control protocol to enhance bandwidth utilization in UASNs. The proposed mechanism increases communication by exploiting temporal and spatial resources that are typically idle in order to protect communication against interference. By reducing wait time, network performance and energy consumption can be improved. A performance evaluation demonstrates that when the data packets are large or sensor deployment is dense, the energy consumption of proposed protocol is less than that of existing protocols as well as the throughput is higher than that of existing protocols. PMID:27005624

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

    PubMed

    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

  16. Neural rotational speed control for wave energy converters

    NASA Astrophysics Data System (ADS)

    Amundarain, M.; Alberdi, M.; Garrido, A. J.; Garrido, I.

    2011-02-01

    Among the benefits arising from an increasing use of renewable energy are: enhanced security of energy supply, stimulation of economic growth, job creation and protection of the environment. In this context, this study analyses the performance of an oscillating water column device for wave energy conversion in function of the stalling behaviour in Wells turbines, one of the most widely used turbines in wave energy plants. For this purpose, a model of neural rotational speed control system is presented, simulated and implemented. This scheme is employed to appropriately adapt the speed of the doubly-fed induction generator coupled to the turbine according to the pressure drop entry, so as to avoid the undesired stalling behaviour. It is demonstrated that the proposed neural rotational speed control design adequately matches the desired relationship between the slip of the doubly-fed induction generator and the pressure drop input, improving the power generated by the turbine generator module.

  17. Dynamic Theory: some shock wave and energy implications

    SciTech Connect

    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.

  18. Aiding Design of Wave Energy Converters via Computational Simulations

    NASA Astrophysics Data System (ADS)

    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.

  19. Global ULF Wave Energy Transport in the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Rae, I. J.; Mann, I. R.; Donovan, E. F.; Fenrich, F. R.; Watt, C. E. J.; Milling, D. K.; Lester, M.; Singer, H. J.; Reme, H.; Balogh, A.

    Transport of ULF wave energy via large-scale wave modes is extremely important in terms of solar wind-magnetosphere-ionosphere coupling In this paper we present a study in which we fully characterise and diagnose large-scale ULF wave dynamics on a near-global scale We present a study using a favourable radial alignment of the Cluster Polar and geosynchronous satellites in the dusk sector during a high solar wind speed interval We infer that magnetopause undulations observed by Cluster drove compressional waves perhaps in the form of Kelvin-Helmholtz unstable magnetospheric waveguide modes that propagate inward from the magnetopause These compressional waves couple to resonant field lines close to location of Polar and geosynchronous orbit and are observed as a field line resonance on the ground Further we analyse the magnetopause boundary oscillations on both large- and small-scales using the minimum variance technique to identify the planar nature of the boundary layer magnetopause This has important implications for both the DoubleStar and THEMIS missions together with measurements from other satellites such as Cluster Geotail and the geosynchronous satellite fleet flank and dayside conjunctions of these satellites will be able to characterise the full radial and multi-scale nature of Global ULF wave events This technique is valuable for the investigation of tail phenomena excited via the same K-H activity at the flanks for example in the boundary layer model for magnetospheric substorms

  20. An atlas of the wave energy resource in Europe

    SciTech Connect

    Pontes, M.T.; Athanassoulis, G.A.; Barstow, S.; Cavaleri, L.; Holmes, B.; Mollison, D.; Oliveira-Pires, H.

    1995-12-31

    This paper presents an Atlas of the European offshore wave energy resource that is being developed within the scope of an European project. It will be mainly based on wave estimates produced by the numerical wind-wave model WAM that is in routine operation at the European Centre for Medium-Range Weather Forecasts, Reading, UK. This model was chosen after a preliminary verification of two models again buoy data for a one-year period. Wave measurements will be used for the Norwegian Sea and the North Sea. The Atlas will be produced as a user-friendly software package for MS-DOS microcomputers permitting fast retrieval of information as well as saving and printing of statistics and maps. The Atlas will include annual and seasonal statistics of significant wave height, mean and peak period, mean direction and wave power levels (global values as well as directional distributions). These data will be both presented as tables, graphs and as geographic maps.

  1. Investigation of Wave Energy Converter Effects on Near-shore Wave Fields: Model Generation Validation and Evaluation - Kaneohe Bay HI.

    SciTech Connect

    Roberts, Jesse D.; Chang, Grace; Jones, Craig

    2014-09-01

    The numerical model, SWAN (Simulating WAves Nearshore) , was used to simulate wave conditions in Kaneohe Bay, HI in order to determine the effects of wave energy converter ( WEC ) devices on the propagation of waves into shore. A nested SWAN model was validated then used to evaluate a range of initial wave conditions: significant wave heights (H s ) , peak periods (T p ) , and mean wave directions ( MWD) . Differences between wave height s in the presence and absence of WEC device s were assessed at locations in shore of the WEC array. The maximum decrease in wave height due to the WEC s was predicted to be approximately 6% at 5 m and 10 m water depths. Th is occurred for model initiation parameters of H s = 3 m (for 5 m water depth) or 4 m (10 m water depth) , T p = 10 s, and MWD = 330deg . Subsequently, bottom orbital velocities were found to decrease by about 6%.

  2. Structural Optimization of Triboelectric Nanogenerator for Harvesting Water Wave Energy.

    PubMed

    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. PMID:26567754

  3. Calculations of the heights, periods, profile parameters, and energy spectra of wind waves

    NASA Technical Reports Server (NTRS)

    Korneva, L. A.

    1975-01-01

    Sea wave behavior calculations require the precalculation of wave elements as well as consideration of the spectral functions of ocean wave formation. The spectrum of the random wave process is largely determined by the distribution of energy in the actual wind waves observed on the surface of the sea as expressed in statistical and spectral characteristics of the sea swell.

  4. Experimental Wave Tank Test for Reference Model 3 Floating-Point Absorber Wave Energy Converter Project

    SciTech Connect

    Yu, Y. H.; Lawson, M.; Li, Y.; Previsic, M.; Epler, J.; Lou, J.

    2015-01-01

    The U.S. Department of Energy established a reference model project to benchmark a set of marine and hydrokinetic technologies including current (tidal, open-ocean, and river) turbines and wave energy converters. The objectives of the project were to first evaluate the status of these technologies and their readiness for commercial applications. Second, to evaluate the potential cost of energy and identify cost-reduction pathways and areas where additional research could be best applied to accelerate technology development to market readiness.

  5. System for harvesting water wave energy

    DOEpatents

    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.

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

    PubMed Central

    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

  7. Effects of Wave Energy Converter (WEC) Arrays on Wave, Current, and Sediment Circulation

    NASA Astrophysics Data System (ADS)

    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

  8. Stochastic Control of Inertial Sea Wave Energy Converter

    PubMed Central

    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

  9. A Skin-attachable Flexible Piezoelectric Pulse Wave Energy Harvester

    NASA Astrophysics Data System (ADS)

    Yoon, Sunghyun; Cho, Young-Ho

    2014-11-01

    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 3.71cm2. 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.

  10. Radiation of inertial kinetic energy as near-inertial waves forced by tropical Pacific Easterly waves

    NASA Astrophysics Data System (ADS)

    Soares, S. M.; Richards, K. J.

    2013-05-01

    Easterly waves (EW) are low level tropical atmospheric disturbances able to resonantly force strong mixed layer inertial currents. Using data from two Tropical Atmosphere Ocean/Eastern Pacific Investigation of Climate Processes (TAO/EPIC) buoys located along 95°W and a multiparameterization one-dimensional turbulence model, we examine how the EW-forced surface inertial kinetic energy (IKE) loss is partitioned between turbulent dissipation and near-inertial wave (NIW) radiation. Several EW-forcing events are individually simulated with a version of the General Ocean Turbulence Model modified to include a linear damping coefficient to account for the NIW radiation energy sink. The kinetic energy budget of these simulations shows that NIW radiation accounted for typically 50-60% of the IKE loss and in some cases up to 80%. These empirically derived estimates of the contribution of the radiated NIWs to the loss of wind-induced surface IKE are substantially higher than recently published numerical estimates. Furthermore, the results indicate that the vertical NIW energy flux increases linearly with the wind input of IKE, an easily obtained quantity. The NIW vertical energy flux estimated for a single near-resonant event is comparable to extreme north Pacific wintertime-averaged fluxes, indicating the existence of important episodic sources of near-inertial energy available for mixing within and below the thermocline in the tropical region.

  11. Direct Drive Wave Energy Buoy – 33rd scale experiment

    SciTech Connect

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

    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.

  12. Power inversion design for ocean wave energy harvesting

    NASA Astrophysics Data System (ADS)

    Talebani, Anwar N.

    The needs for energy sources are increasing day by day because of several factors, such as oil depletion, and global climate change due to the higher level of CO2, so the exploration of various renewable energy sources is very promising area of study. The available ocean waves can be utilized as free source of energy as the water covers 70% of the earth surface. This thesis presents the ocean wave energy as a source of renewable energy. By addressing the problem of designing efficient power electronics system to deliver 5 KW from the induction generator to the grid with less possible losses and harmonics as possible and to control current fed to the grid to successfully harvest ocean wave energy. We design an AC-DC full bridge rectifier converter, and a DC-DC boost converter to harvest wave energy from AC to regulated DC. In order to increase the design efficiency, we need to increase the power factor from (0.5-0.6) to 1. This is accomplished by designing the boost converter with power factor correction in continues mode with RC circuit as an input to the boost converter power factor correction. This design results in a phase shift between the input current and voltage of the full bridge rectifier to generate a small reactive power. The reactive power is injected to the induction generator to maintain its functionality by generating a magnetic field in its stator. Next, we design a single-phase pulse width modulator full bridge voltage source DC-AC grid-tied mode inverter to harvest regulated DC wave energy to AC. The designed inverter is modulated by inner current loop, to control current injected to the grid with minimal filter component to maintain power quality at the grid. The simulation results show that our design successfully control the current level fed to the grid. It is noteworthy that the simulated efficiency is higher than the calculated one since we used an ideal switch in the simulated circuit.

  13. Estimation of Radiated Seismic Energy from Teleseismic P Waves

    NASA Astrophysics Data System (ADS)

    Kiuchi, R.; Mori, J. J.

    2013-12-01

    Earthquake radiated energy is a fundamental parameter for understanding source physics. Using teleseismic waveforms, we can estimate the radiated energy for a wide range of focal mechanisms and tectonic setting. We are especially interested in studying the apparent stress (rigidity multiplied by the ratio of radiated energy to seismic moment) of strike-slip earthquakes in the oceanic lithosphere, for which there are often high reported values (Choy and McGarr, 2002). Estimates of radiated energy from teleseismic P waves can be unstable, because take-off angles from the source are often close to nodes in the focal mechanisms, which can cause large variations in the estimated values of the apparent stress. In this study, we use only P waves for the teleseismic waveform, because of the strong attenuation of teleseismic S waves and interference with other phases. We use data recorded by teleseismic stations (epicentral distances of 30 to 90deg) recorded on the GSN network and focal mechanisms published by USGS and Global CMT Project. For the teleseismic waveforms, we need to account for the radiation pattern of the direct P and depth phase, pP and sP (Boatwright and Choy, 1986). For strike-slip events with where many data are close to nodes in the focal mechanisms, this is a large and often unstable correction. We use an improved method which takes into account a range of values for the strike, dip and rake angles. Also, we use station corrections determined from a selected set of well determined events. We show the result of estimated radiated seismic energy for 188 recent earthquakes (>Mw 7.0, since 2000 ). We discuss the differences of the radiated energy as a function of focal mechanisms, and oceanic/continental sources. Fig. Radiated seismic energy and correction for radiation pattern calculated using a range of focal mechanisms.

  14. System-reliability studies for wave-energy generation

    NASA Astrophysics Data System (ADS)

    Dawson, J. M.; Din, S.; Mytton, M. G.; Shore, N. L.; Stansfield, H. B.

    1980-06-01

    A study is reported that is being undertaken in the United Kingdom to determine means of developing the potential of the large wave-energy resource around the coast, in particular, that to the west facing the Atlantic. It is shown that derivation of the mean annual energy to be expected involved knowledge, not only of the wave climates, conversion efficiency characteristics of the proposed devices and of the power transmission system, but also of factors reflecting the availability overall. Attention is given to a simplified approach to the quantifying of reliability for each stage of the process. An appropriate method of analysis is established and a summary of the results obtained is given.

  15. Multicriteria analysis to evaluate wave energy converters based on their environmental impact: an Italian case study

    NASA Astrophysics Data System (ADS)

    Azzellino, Arianna; Contestabile, Pasquale; Lanfredi, Caterina; Vicinanza, Diego

    2010-05-01

    The exploitation of renewable energy resources is fast becoming a key objective in many countries. Countries with coastlines have particularly valuable renewable energy resources in the form of tides, currents, waves and offshore wind. Due to the visual impact of siting large numbers of energy generating devices (eg. wind turbines) in terrestrial landscapes, considerable attention is now being directed towards coastal waters. Due to their environmental sensitivity, the selection of the most adequate location for these systems is a critical factor. Multi-criteria analysis allows to consider a wide variety of key characteristics (e.g. water depth, distance to shore, distance to the electric grid in land, geology, environmental impact) that may be converted into a numerical index of suitability for different WEC devices to different locations. So identifying the best alternative between an offshore or a onshore device may be specifically treated as a multicriteria problem. Special enphasisi should be given in the multicriteria analysis to the environmental impact issues. The wave energy prospective in the Italian seas is relatively low if compared to the other European countries faced to the ocean. Based on the wave climate, the Alghero site, (NW Sardinia, Italy) is one of the most interesting sites for the wave energy perspective (about 10 kW/m). Alghero site is characterized by a high level of marine biodiversity. In 2002 the area northern to Alghero harbour (Capo Caccia-Isola Piana) was established a Marine Protected Area (MPA). It could be discussed for this site how to choose between the onshore/offshore WEC alternative. An offshore device like Wave Dragon (http://www.wavedragon.net/) installed at -65m depth (width=300m and length=170 m) may approximately produce about 3.6 GWh/y with a total cost of about 9,000,000 €. On the other hand, an onshore device like SSG (http://waveenergy.no/), employed as crown wall for a vertical breakwater to enlarge the present

  16. A permanent magnet tubular linear generator for wave energy conversion

    NASA Astrophysics Data System (ADS)

    Yu, Haitao; Liu, Chunyuan; Yuan, Bang; Hu, Minqiang; Huang, Lei; Zhou, Shigui

    2012-04-01

    A novel three-phase permanent magnet tubular linear generator (PMTLG) with Halbach array is proposed for the sea wave energy conversion. Non-linear axi-symmetrical finite element method (FEM) is implemented to calculate the magnetic fields along air-gap for different Halbach arrays of PMTLGs. The PMTLG characteristics are analyzed and the simulation results are validated by the experiment. An assistant tooth is implemented to greatly minimize the end and cogging effects which cause the oscillatory detent force.

  17. Energy space entanglement spectrum of pairing models with s-wave and p-wave symmetry

    NASA Astrophysics Data System (ADS)

    Rodríguez-Laguna, Javier; Berganza, Miguel Ibáñez; Sierra, Germán

    2014-07-01

    We study the entanglement between blocks of energy levels in 1D models for s-wave and p-wave superconductivity. The ground state entanglement entropy and entanglement spectrum (ES) of a block of ℓ levels around the Fermi point is obtained and related to its physical properties. In the superconducting phase at large coupling, the maximal entropy grows with the number of levels L as 1/2ln(L). The number of levels presenting maximal entanglement is shown to estimate the number of Cooper pairs involved in pairing correlations. Moreover, the properties of the ES signal the presence of the Read-Green quantum phase transition in the p +ip model, and of the Moore-Read line, which is difficult to characterize. This work establishes a link between physical properties of superconducting phases and quantum entanglement.

  18. Wave-driven Rotation in Supersonically Rotating Mirrors

    SciTech Connect

    A. Fetterman and N.J. Fisch

    2010-02-15

    Supersonic rotation in mirrors may be produced by radio frequency waves. The waves produce coupled diffusion in ion kinetic and potential energy. A population inversion along the diffusion path then produces rotation. Waves may be designed to exploit a natural kinetic energy source or may provide the rotation energy on their own. Centrifugal traps for fusion and isotope separation may benefit from this wave-driven rotation.

  19. Equatorially Trapped Waves at the 200 mb Level and Their Association with Meridional Convergence of Wave Energy Flux.

    NASA Astrophysics Data System (ADS)

    Yanai, Michio; Lu, Mong-Ming

    1983-12-01

    Equatorially trapped planetary-scale waves at the 200 mb level are isolated and their characteristics are examined using space-time spectral analyses of wind data in the latitude belt from 20°S to 40°N during the two contrasting northern summers of 1967 and 1972. With the aid of the theoretically known properties of equatorial waves such as the dispersion relation and the symmetry or antisymmetry of wind components with respect to the equator, Kelvin waves with s (zonal wavenumber) = 1 and 2, a mixed Rossby-gravity wave with s = 4, and an equatorially trapped Rossby wave with s = 2 can be clearly identified among the major spectral peaks observed in 1967. However, in 1972 the mixed Rossby-gravity wave is absent and only weak signals of the Kelvin waves with s = 1 and 2 and the equatorially trapped Rossby wave with s = 2 are found. In addition, westward moving waves with s = 1, which are identified as the gravest symmetric free Rossby waves, are observed in both years. All the westward-moving equatorially trapped waves are accompanied by meridional convergence of wave energy flux, suggesting their possible excitation by lateral forcing due to midlatitude disturbances.

  20. Internal wave pressure, velocity, and energy flux from density perturbations

    NASA Astrophysics Data System (ADS)

    Allshouse, Michael R.; Lee, Frank M.; Morrison, Philip J.; Swinney, Harry L.

    2016-05-01

    Determination of energy transport is crucial for understanding the energy budget and fluid circulation in density varying fluids such as the ocean and the atmosphere. However, it is rarely possible to determine the energy flux field J =p u , which requires simultaneous measurements of the pressure and velocity perturbation fields p and u , respectively. We present a method for obtaining the instantaneous J (x ,z ,t ) from density perturbations alone: A Green's function-based calculation yields p ; u is obtained by integrating the continuity equation and the incompressibility condition. We validate our method with results from Navier-Stokes simulations: The Green's function method is applied to the density perturbation field from the simulations and the result for J is found to agree typically to within 1% with J computed directly using p and u from the Navier-Stokes simulation. We also apply the Green's function method to density perturbation data from laboratory schlieren measurements of internal waves in a stratified fluid and the result for J agrees to within 6 % with results from Navier-Stokes simulations. Our method for determining the instantaneous velocity, pressure, and energy flux fields applies to any system described by a linear approximation of the density perturbation field, e.g., to small-amplitude lee waves and propagating vertical modes. The method can be applied using our matlab graphical user interface EnergyFlux.

  1. Artificial ocean upwelling utilizing the energy of surface waves

    NASA Astrophysics Data System (ADS)

    Soloviev, Alexander

    2016-04-01

    Artificial upwelling can bring cold water from below the thermocline to the sea surface. Vershinsky, Pshenichnyy, and Soloviev (1987) developed a prototype device, utilizing the energy of surface waves to create an upward flow of water in the tube. This is a wave-inertia pump consisting of a vertical tube, a valve, and a buoy to keep the device afloat. An outlet valve at the top of the unit synchronizes the operation of the device with surface waves and prevents back-splashing. A single device with a 100 m long and 1.2 m diameter tube is able to produce up to 1 m3s‑1 flow of deep water to the surface. With a 10 oC temperature difference over 100 m depth, the negative heat supply rate to the sea surface is 42 MW, which is equivalent to a 42 Wm‑2 heat flux, if distributed over 1 km2 area. Such flux is comparable to the average net air-sea flux. A system of artificial upwelling devices can cool down the sea surface, modify climate on a regional scale and possibly help mitigate hurricanes. The cold water brought from a deeper layer, however, has a larger density than the surface water and therefore has a tendency to sink back down. In this work, the efficiency of wave-inertia pumps and climatic consequences are estimated for different environmental conditions using a computational fluid dynamics model.

  2. Searching for dark energy with matter wave interferometry

    NASA Astrophysics Data System (ADS)

    Hamilton, Paul

    2016-05-01

    The nature of dark energy, which makes up 70% of the mass-energy of the universe, remains completely unknown. Chameleons are a simple scalar model for dark energy that mediate a force which is screened by bulk matter. However we can now probe these scalar fields using atoms as nearly ideal test masses in the vacuum of our cavity-based matter wave interferometer. Our first measurements ruled out a range of chameleons that would reproduce the observed cosmic acceleration. Since then we have improved sensitivity by a factor of 100. With a similar future improvement, we will be sensitive to any possible chameleon field and other exotic models for dark energy and dark matter, such as symmetrons or f(R) gravity.

  3. On the Crest of a Wave: A Review of Wave Power Technology

    ERIC Educational Resources Information Center

    Harris, Fank

    2014-01-01

    The energy potentially available from waves around the coast of the UK far exceeds our domestic and industrial demands and yet, despite much research, numerous patent applications and several pilot schemes, the exploitation of waves for their energy largely remains in transition between development and commercialisation. This article examines the…

  4. Equilibrium distribution of the wave energy in a carbyne chain

    NASA Astrophysics Data System (ADS)

    Kovriguine, D. A.; Nikitenkova, S. P.

    2016-03-01

    The steady-state energy distribution of thermal vibrations at a given ambient temperature has been investigated based on a simple mathematical model that takes into account central and noncentral interactions between carbon atoms in a one-dimensional carbyne chain. The investigation has been performed using standard asymptotic methods of nonlinear dynamics in terms of the classical mechanics. In the first-order nonlinear approximation, there have been revealed resonant wave triads that are formed at a typical nonlinearity of the system under phase matching conditions. Each resonant triad consists of one longitudinal and two transverse vibration modes. In the general case, the chain is characterized by a superposition of similar resonant triplets of different spectral scales. It has been found that the energy equipartition of nonlinear stationary waves in the carbyne chain at a given temperature completely obeys the standard Rayleigh-Jeans law due to the proportional amplitude dispersion. The possibility of spontaneous formation of three-frequency envelope solitons in carbyne has been demonstrated. Heat in the form of such solitons can propagate in a chain of carbon atoms without diffusion, like localized waves.

  5. Holocene reef development where wave energy reduces accommodation

    USGS Publications Warehouse

    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.

  6. Wind, Wave, and Tidal Energy Without Power Conditioning

    NASA Technical Reports Server (NTRS)

    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

  7. Reference Model 6 (RM6): Oscillating Wave Energy Converter.

    SciTech Connect

    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.

  8. A low-cost float method of harnessing wave energy

    SciTech Connect

    George, M.P.

    1983-12-01

    The author proposes in this paper a low-cost and simple method of harnessing wave energy that should enable coastal regions to be self-sufficient in electric power. The method is eminently applicable to India and such developing countries, being simple and involving a small capital investment. The method was evolved after study of the Indian West Coast fronting the Arabian Sea, and can harness about 50% of the wave energy. A log of wood about 5 metres long and 50 cm. in diameter, having a specific gravity of 0.8 to 0.9, is made to float parallel to the beach and about 50 metres away from it. Its movement is restricted to the vertical plane by means of poles. Two roller chains are attached to the ends of the log which pass over two sprocket free-wheels. When the log is lifted with the crest of the wave, the roller chain moves over the free-wheel. When the trough of the wave reaches the log, its weight is applied to the sprocket wheels through the roller chains. Each sprocket wheel rotates and the rotation is multiplied with a gear wheel. The torque from the high speed spindle of the gear is applied to a small alternating current generator. The AC output from the generator is rectified and used either for charging a battery bank, or connected to the lighting system, or supplied to electrolytic tank for producing hydrogen and other chemicals at the site. A chain of such systems along the coast can supply enough power to light the fishermen's hamlets stretching along the coast.

  9. Rossby wave energy dispersion from tropical cyclone in zonal basic flows

    NASA Astrophysics Data System (ADS)

    Shi, Wenli; Fei, Jianfang; Huang, Xiaogang; Liu, Yudi; Ma, Zhanhong; Yang, Lu

    2016-04-01

    This study investigates tropical cyclone energy dispersion under horizontally sheared flows using a nonlinear barotropic model. In addition to common patterns, unusual features of Rossby wave trains are also found in flows with constant vorticity and vorticity gradients. In terms of the direction of the energy dispersion, the wave train can rotate clockwise and elongate southwestward under anticyclonic circulation (ASH), which contributes to the reenhancement of the tropical cyclone (TC). The wave train even splits into two obvious wavelike trains in flows with a southward vorticity gradient (WSH). Energy dispersed from TCs varies over time, and variations in the intensity of the wave train components typically occur in two stages. Wave-activity flux diagnosis and ray tracing calculations are extended to the frame that moves along with the TC to reveal the concrete progress of wave propagation. The direction of the wave-activity flux is primarily determined by the combination of the basic flow and the TC velocity. Along the flux, the distribution of pseudomomentum effectively illustrates the development of wave trains, particularly the rotation and split of wave propagation. Ray tracing involves the quantitative tracing of wave features along rays, which effectively coincide with the wave train regimes. Flows of a constant shear (parabolic meridional variation) produce linear (nonlinear) wave number variations. For the split wave trains, the real and complex wave number waves move along divergent trajectories and are responsible for different energy dispersion ducts.

  10. The Indian Athlete: Exploiting or Exploited?

    ERIC Educational Resources Information Center

    Salter, Michael A.

    It is the purpose of this paper to examine the nineteenth century Canadian Indian lacrosse player to determine whether or not he was exploited by his European counterparts, and if so, the manner in which this exploitation occurred. Caucasian lacrosse enthusiasts sought to promote "their" game by arranging for Indian demonstrations to be staged…

  11. Energy scaling of terahertz-wave parametric sources.

    PubMed

    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. PMID:25836452

  12. Beyond the Horizon Distance: LIGO-Virgo can Boost Gravitational-Wave Detection Rates by Exploiting the Mass Distribution of Neutron Star and Black Hole Binaries

    NASA Astrophysics Data System (ADS)

    Marka, Zsuzsa; Bartos, Imre; Marka, Szabolcs; LIGO Collaboration; Virgo Collaboration

    2016-03-01

    We explore the advantage of focusing on regions of the parameter space in gravitational-wave searches for the binary mergers of neutron stars and black holes. For neutron star binaries, we show that taking advantage of their narrow observed mass distribution could improve detection rates, in some cases by more than 50%. A reduced template bank can also represent significant improvement in technical cost. We present a detailed search method using binary mass distribution to incorporate information on the mass distribution.

  13. Advanced, High Power, Next Scale, Wave Energy Conversion Device

    SciTech Connect

    Mekhiche, Mike; Dufera, Hiz; Montagna, Deb

    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.

  14. Guided wave energy trapping to detect hidden multilayer delamination damage

    NASA Astrophysics Data System (ADS)

    Leckey, Cara A. C.; Seebo, Jeffrey P.

    2015-03-01

    Nondestructive Evaluation (NDE) and Structural Health Monitoring (SHM) simulation tools capable of modeling three-dimensional (3D) realistic energy-damage interactions are needed for aerospace composites. Current practice in NDE/SHM simulation for composites commonly involves over-simplification of the material parameters and/or a simplified two-dimensional (2D) approach. The unique damage types that occur in composite materials (delamination, microcracking, etc) develop as complex 3D geometry features. This paper discusses the application of 3D custom ultrasonic simulation tools to study wave interaction with multilayer delamination damage in carbon-fiber reinforced polymer (CFRP) composites. In particular, simulation based studies of ultrasonic guided wave energy trapping due to multilayer delamination damage were performed. The simulation results show changes in energy trapping at the composite surface as additional delaminations are added through the composite thickness. The results demonstrate a potential approach for identifying the presence of hidden multilayer delamination damage in applications where only single-sided access to a component is available. The paper also describes recent advancements in optimizing the custom ultrasonic simulation code for increases in computation speed.

  15. Multimessenger astrophysics: When gravitational waves meet high energy neutrinos

    NASA Astrophysics Data System (ADS)

    Di Palma, Irene

    2014-04-01

    With recent development of experimental techniques that have opened new windows of observation of the cosmic radiation in all its components, multi-messenger astronomy is entering an exciting era. Many astrophysical sources and cataclysmic cosmic events with burst activity can be plausible sources of concomitant gravitational waves (GWs) and high-energy neutrinos (HENs). Such messengers could reveal hidden and new sources that are not observed by conventional photon astronomy, in particular at high energy. Requiring consistency between GW and HEN detection channels enables new searches and a detection would yield significant additional information about the common source. We present the results of the first search for gravitational wave bursts associated with high energy neutrino triggers, detected by the underwater neutrino telescope ANTARES in its 5 line configuration, during the fifth LIGO science run and first Virgo science run. No evidence for coincident events was found. We place a lower limit on the distance to GW sources associated with every HEN trigger. We are able to rule out the existence of coalescing binary neutron star systems and black hole-neutron star systems up to distances that are typically 5 Mpc and 10 Mpc respectively.

  16. Wave Energy Converter Effects on Wave Fields: Evaluation of SNL-SWAN and Sensitivity Studies in Monterey Bay CA.

    SciTech Connect

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

    2014-09-01

    A modified version of an indust ry standard wave modeling tool was evaluated, optimized, and utilized to investigate model sensitivity to input parameters a nd wave energy converter ( WEC ) array deployment 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 wave direction and WEC device type we r e most sensitive to the variation in the model parameters examined in this study . Generally, the changes in wave height we re the primary alteration caused by the presence of a WEC array. Specifically, W EC device type and subsequently their size directly re sult ed in wave height variations; however, it is important to utilize ongoing laboratory studies and future field tests to determine the most appropriate power matrix values for a particular WEC device and configuration in order to improve modeling results .

  17. Investigation of Wave Energy Converter Effects on Wave Fields: A Modeling Sensitivity Study in Monterey Bay CA.

    SciTech Connect

    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 .

  18. Magnetic field induced spin-wave energy focusing

    NASA Astrophysics Data System (ADS)

    Perez, Noel; Lopez-Diaz, Luis

    2015-07-01

    Local temperature variations induced by spin-wave propagation are studied using a model that couples nonuniform magnetization dynamics and heat flow. We show that the remote heating at the sample edge reported recently [T. An et al., Nat. Mater. 12, 549 (2013)], 10.1038/nmat3628 is due to the geometry-induced gradual reduction of the effective field. We demonstrate that the same effect can be achieved by a reduction in the external field instead of a constriction at the edge and, furthermore, that both the location and the amount of energy to be delivered to the lattice can be controlled accurately this way.

  19. Relationship between wave energy and free energy from pickup ions in the Comet Halley environment

    NASA Technical Reports Server (NTRS)

    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.

  20. Reference Model 5 (RM5): Oscillating Surge Wave Energy Converter

    SciTech Connect

    Yu, Y. H.; Jenne, D. S.; Thresher, R.; Copping, A.; Geerlofs, S.; Hanna, L. A.

    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.

  1. Energy harvesting from sea waves with consideration of airy and JONSWAP theory and optimization of energy harvester parameters

    NASA Astrophysics Data System (ADS)

    Mirab, Hadi; Fathi, Reza; Jahangiri, Vahid; Ettefagh, Mir Mohammad; Hassannejad, Reza

    2015-12-01

    One of the new methods for powering low-power electronic devices at sea is a wave energy harvesting system. 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 avoiding a battery charging system. Studies have been done on energy harvesting from sea waves, however, considering energy harvesting with random JONSWAP wave theory, then determining the optimum values of energy harvested is new. This paper does that by implementing the JONSWAP wave model, calculating produced power, and realistically showing that output power is decreased in comparison with the more simple airy wave model. In addition, parameters of the energy harvester system are optimized using a simulated annealing algorithm, yielding increased produced power.

  2. Beyond the Horizon Distance: LIGO-Virgo can Boost Gravitational-Wave Detection Rates by Exploiting the Mass Distribution of Neutron Stars.

    PubMed

    Bartos, I; Márka, S

    2015-12-01

    The masses of neutron stars in neutron star binaries are observed to fall in a narrow mass range around ∼1.33M_{⊙}. We explore the advantage of focusing on this region of the parameter space in gravitational-wave searches. We find that an all-sky (externally triggered) search with an optimally reduced template bank is expected to detect 14% (61%) more binary mergers than without the reduction. A reduced template bank can also represent significant improvement in technical cost. We also develop a more detailed search method using binary mass distribution, and find a sensitivity increase similar to that due to the reduced template bank. PMID:26684105

  3. Beyond the Horizon Distance: LIGO-Virgo can Boost Gravitational-Wave Detection Rates by Exploiting the Mass Distribution of Neutron Stars

    NASA Astrophysics Data System (ADS)

    Bartos, I.; Márka, S.

    2015-12-01

    The masses of neutron stars in neutron star binaries are observed to fall in a narrow mass range around ˜1.33 M⊙. We explore the advantage of focusing on this region of the parameter space in gravitational-wave searches. We find that an all-sky (externally triggered) search with an optimally reduced template bank is expected to detect 14% (61%) more binary mergers than without the reduction. A reduced template bank can also represent significant improvement in technical cost. We also develop a more detailed search method using binary mass distribution, and find a sensitivity increase similar to that due to the reduced template bank.

  4. Irregular Wave Energy Extraction Analysis for a Slider Crank WEC Power Take-Off System

    SciTech Connect

    Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun; Zhang, James Z.; Muljadi, Eduard

    2015-09-02

    Slider crank Wave Energy Converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this WEC has been done under regular sinusoidal wave conditions, and a suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and the control methodology is modified to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from that under regular sinusoidal wave conditions, but still a reasonable amount of energy can be extracted.

  5. Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

    SciTech Connect

    Rhinefrank, Kenneth E; Haller, Merrick C; Ozkan-Haller, H Tuba

    2013-01-26

    This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array of newly developed Buoys' that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate high

  6. Momentum and energy transport by waves in the solar atmosphere and solar wind

    NASA Technical Reports Server (NTRS)

    Jacques, S. A.

    1977-01-01

    The fluid equations for the solar wind are presented in a form which includes the momentum and energy flux of waves in a general and consistent way. The concept of conservation of wave action is introduced and is used to derive expressions for the wave energy density as a function of heliocentric distance. The explicit form of the terms due to waves in both the momentum and energy equations are given for radially propagating acoustic, Alfven, and fast mode waves. The effect of waves as a source of momentum is explored by examining the critical points of the momentum equation for isothermal spherically symmetric flow. We find that the principal effect of waves on the solutions is to bring the critical point closer to the sun's surface and to increase the Mach number at the critical point. When a simple model of dissipation is included for acoustic waves, in some cases there are multiple critical points.

  7. Wave energies and wave-induced longshore currents in an unstructured-grid model - circulation in front of barrier islands

    NASA Astrophysics Data System (ADS)

    Jörg-Olaf Wolff, , Prof. _., Dr.; Grashorn, Sebastian, , Dr.; Lettmann, Karsten A., , Dr.; Badewien, Thomas H., , Dr.; Stanev, Emil V., Prof. _., Dr.

    2015-04-01

    An unstructured-grid model (FVCOM) coupled to a wave model (FVCOM-SWAVE) is used to investigate the hydrodynamic and wave energy conditions during a moderate and a storm situation in the southern North Sea. Two different setups are presented. One setup covers the whole North Sea with moderately increased grid resolution at the coast, whereas the other comprises a very high resolution East Frisian Wadden Sea setup, one-way coupled to the coarser North Sea model. The results of both model setups are validated, compared to each other and analysed with a focus on longshore currents and wave energy. The results show that during storm conditions strong wave-induced longshore currents occur in front of the barrier islands of the East Frisian Wadden Sea, resulting in total current speeds up to 2 m/s. This effect is especially pronounced in the high-resolution setup. The wave-current interaction also influences the sea surface elevation by raising the water level in the tidal basins. Calculated wave energies show large differences between moderate wind and storm conditions with time-averaged values up to 200 kW/m. The numerical results indicate that wave-current coupling, albeit numerically expensive, cannot be ignored because it plays an important role in almost all near coastal transport phenomena (sediments, contaminants, bacteria, etc.).

  8. Networks of triboelectric nanogenerators for harvesting water wave energy: a potential approach toward blue energy.

    PubMed

    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. PMID:25719956

  9. Dielectric elastomer energy harvesting: maximal converted energy, viscoelastic dissipation and a wave power generator

    NASA Astrophysics Data System (ADS)

    Lv, Xiongfei; Liu, Liwu; Liu, Yanju; Leng, Jinsong

    2015-11-01

    Dielectric elastomer (DE) is a smart soft material. It is able to produce large deformation under mechanical force and electric field, so that it can achieve mutual conversion between mechanical energy and electrical energy. Based on this property, dielectric elastomer can be used in energy harvesting field. In this paper, firstly, we analyzed the constitutive relation under different hyperelastic models (Gent and neo-Hookean model) based on both theoretical and experimental study. Secondly, we depicted the allowable areas in force-displacement and voltage-charge plane according to different failure modes, and then calculated the maximal energy density in one energy harvesting period. Thirdly, we studied the viscoelastic energy dissipation which can lose the input mechanical energy in the energy harvesting process. Finally, we designed and fabricated a wave power generator, and tested its performance. This paper is of deep significance to the future applications of DE generators.

  10. On the nature of cross-isobath energy fluxes in topographically modified barotropic semidiurnal Kelvin waves

    NASA Astrophysics Data System (ADS)

    Zhang, Tianyi; Yankovsky, Alexander E.

    2016-05-01

    Continental shelf topography modifies a Kelvin wave into a hybrid Kelvin-edge wave with a nonzero across-isobath velocity and a phase speed that decreases with increasing wave number while the group velocity reaches a minimum at intermediate wave numbers. We model the modified semidiurnal Kelvin wave adjustment to alongshore changes in the shelf width. The model domain consists of two alongshore-uniform continental shelves of different widths adjoined through a 150 km long transition zone. The continental shelf and slope are adjacent to an ocean of a constant depth, allowing radiation of Poincaré waves. We consider three shelf widths of 150, 250, and 300 km, where properties of a zero mode at semidiurnal frequency change from Kelvin wave like to edge wave like. For each shelf width, a zero wave mode has its distinctive alongshore energy flux structure on the shelf. As the incident wave encounters a variable shelf width, the alongshore energy flux converges (diverges) on the shelf resulting in an offshore (onshore) energy flux over the continental slope. Furthermore, for a strongly convergent alongshore energy flux, the incident wave mode scatters into radiating Poincaré waves. On sufficiently wide shelves, a strong across-isobath energy flux comparable with the incident wave energy flux can be triggered even by relatively modest changes of shelf width. An energy flux divergence parameter De is defined, which scales with magnitude and direction of the energy flux across the continental slope. More than 50% of the incident energy flux scatters into modes radiating offshore when De is -1 or less.

  11. The energy balance of wind waves and the remote sensing problem

    NASA Technical Reports Server (NTRS)

    Hasselmann, K.

    1972-01-01

    Measurements of wave growth indicate an energy balance of the wave spectrum governed primarily by input from the atmosphere, nonlinear transfer to shorter and longer waves, and advection. The pronounced spectral peak and sharp low frequency cut-off characteristic of fetch-limited spectra are explained as a self-stabilizing feature of the nonlinear wave-wave interactions. The momentum transferred from the atmosphere to the wind waves accounts for a large part of the wind drag. These findings are relevant for remote microwave sensing of the sea surface by backscatter and passive radiometry methods.

  12. Experimental investigation of change of energy of infragavity waves in dependence on spectral characteristics of an irregular wind waves in coastal zone

    NASA Astrophysics Data System (ADS)

    Saprykina, Yana; Divinskii, Boris

    2013-04-01

    An infragravity waves are long waves with periods of 20 - 300 s. Most essential influence of infragarvity waves on dynamic processes is in a coastal zone, where its energy can exceed the energy of wind waves. From practical point of view, the infragravity waves are important, firstly, due to their influence on sand transport processes in a coastal zone. For example, interacting with group structure of wind waves the infragravity waves can define position of underwater bars on sandy coast. Secondly, they are responsible on formation of long waves in harbors. Main source of infragravity waves is wave group structure defined by sub-nonlinear interactions of wind waves (Longuet-Higgins, Stewart, 1962). These infragravity waves are bound with groups of wind waves and propagate with wave group velocity. Another type of infragravity waves are formed in a surf zone as a result of migration a wave breaking point (Symonds, et al., 1982). What from described above mechanisms of formation of infragravity waves prevails, till now it is unknown. It is also unknown how energy of infragravity waves depends on energy of input wind waves and how it changes during nonlinear wave transformation in coastal zone. In our work on the basis of the analysis of data of field experiment and numerical simulation a contribution of infragravity waves in total wave energy in depending on integral characteristics of an irregular wave field in the conditions of a real bathymetry was investigated. For analysis the data of field experiment "Shkorpilovtsy-2007" (Black sea) and data of numerical modeling of Boussinesq type equation with extended dispersion characteristics (Madsen et al., 1997) were used. It was revealed that infragravity waves in a coastal zone are defined mainly by local group structure of waves, which permanently changes due to nonlinearity, shoaling and breaking processes. Free infragravity waves appearing after wave breaking exist together with bound infragravity waves. There are

  13. Boring and Sealing Rock with Directed Energy Millimeter-Waves

    NASA Astrophysics Data System (ADS)

    Woskov, P.; Einstein, H. H.; Oglesby, K.

    2015-12-01

    Millimeter-wave directed energy is being investigated to penetrate into deep crystalline basement rock formations to lower well costs and to melt rocks, metals, and other additives to seal wells for applications that include nuclear waste storage and geothermal energy. Laboratory tests have established that intense millimeter-wave (MMW) beams > 1 kW/cm2 can melt and/ or vaporize hard crystalline rocks. In principle this will make it possible to create open boreholes and a method to seal them with a glass/ceramic liner and plug formed from the original rock or with other materials. A 10 kW, 28 GHz commercial (CPI) gyrotron system with a launched beam diameter of about 32 mm was used to heat basalt, granite, limestone, and sandstone specimens to temperatures over 2500 °C to create melts and holes. A calibrated 137 GHz radiometer view, collinear with the heating beam, monitored real time peak rock temperature. A water load surrounding the rock test specimen primarily monitored unabsorbed power at 28 GHz. Power balance analysis of the laboratory observations shows that the temperature rise is limited by radiative heat loss, which would be expected to be trapped in a borehole. The analysis also indicates that the emissivity (absorption efficiency) in the radiated infrared range is lower than the emissivity at 28 GHz, giving the MMW frequency range an important advantage for rock melting. Strength tests on one granite type indicated that heating the rock initially weakens it, but with exposure to higher temperatures the resolidified black glassy product regains strength. Basalt was the easiest to melt and penetrate, if a melt leak path was provided, because of its low viscosity. Full beam holes up to about 50 mm diameter (diffraction increased beam size) were achieved through 30 mm thick basalt and granite specimens. Laboratory experiments to form a seal in an existing hole have also been carried out by melting rock and a simulated steel casing.

  14. Adiabatic corrections to density functional theory energies and wave functions.

    PubMed

    Mohallem, José R; Coura, Thiago de O; Diniz, Leonardo G; de Castro, Gustavo; Assafrão, Denise; Heine, Thomas

    2008-09-25

    The adiabatic finite-nuclear-mass-correction (FNMC) to the electronic energies and wave functions of atoms and molecules is formulated for density-functional theory and implemented in the deMon code. The approach is tested for a series of local and gradient corrected density functionals, using MP2 results and diagonal-Born-Oppenheimer corrections from the literature for comparison. In the evaluation of absolute energy corrections of nonorganic molecules the LDA PZ81 functional works surprisingly better than the others. For organic molecules the GGA BLYP functional has the best performance. FNMC with GGA functionals, mainly BLYP, show a good performance in the evaluation of relative corrections, except for nonorganic molecules containing H atoms. The PW86 functional stands out with the best evaluation of the barrier of linearity of H2O and the isotopic dipole moment of HDO. In general, DFT functionals display an accuracy superior than the common belief and because the corrections are based on a change of the electronic kinetic energy they are here ranked in a new appropriate way. The approach is applied to obtain the adiabatic correction for full atomization of alcanes C(n)H(2n+2), n = 4-10. The barrier of 1 mHartree is approached for adiabatic corrections, justifying its insertion into DFT. PMID:18537228

  15. Energy in elastic fiber embedded in elastic matrix containing incident SH wave

    NASA Technical Reports Server (NTRS)

    Williams, James H., Jr.; Nagem, Raymond J.

    1989-01-01

    A single elastic fiber embedded in an infinite elastic matrix is considered. An incident plane SH wave is assumed in the infinite matrix, and an expression is derived for the total energy in the fiber due to the incident SH wave. A nondimensional form of the fiber energy is plotted as a function of the nondimensional wavenumber of the SH wave. It is shown that the fiber energy attains maximum values at specific values of the wavenumber of the incident wave. The results obtained here are interpreted in the context of phenomena observed in acousto-ultrasonic experiments on fiber reinforced composite materials.

  16. Comparison of magnetosonic wave and water group ion energy densities at Comet Giacobini-Zinner

    NASA Technical Reports Server (NTRS)

    Staines, K.; Balogh, A.; Cowley, S. W. H.; Forster, P. M. De F.; Hynds, R. J.; Yates, T. S.; Sanderson, T. R.; Wenzel, K.-P.; Tsurutani, B. T.

    1991-01-01

    Measurements of the Comet Giacobini-Zinner (GZ) are presented to determine to what extent wave-particle scattering redistributed the initial pick-up energy of the ion population. Also examined is the difference between the ion thermal energy and the energy in the magnetic fields of the waves. In spite of uncertainty of about a factor of 2 noted in the pick-up and mass-loaded regions, it is shown that less than approximately 50 percent of the pick-up energy is converted into wave magnetic energy in the inbound pick-up region.

  17. Absolute instability from linear conversion of counter-propagating positive and negative energy waves

    SciTech Connect

    Kaufman, A.N.; Brizard, A.J.; Morehead, J.J.; Tracy, E.R.

    1997-12-31

    The resonant interaction of a negative-energy wave with a positive-energy wave gives rise to a linear instability. Whereas a single crossing of rays in a nonuniform medium leads to a convectively saturated instability, we show that a double crossing can yield an absolute instability.

  18. Internal swells in the tropics: Near-inertial wave energy fluxes and dissipation during CINDY

    NASA Astrophysics Data System (ADS)

    Soares, S. M.; Natarov, A.; Richards, K. J.

    2016-05-01

    A developing MJO event in the tropical Indian Ocean triggered wind disturbances that generated inertial oscillations in the surface mixed layer. Subsequent radiation of near-inertial waves below the mixed layer produced strong turbulence in the pycnocline. Linear plane wave dynamics and spectral analysis are used to explain these observations, with the ultimate goal of estimating the wave energy flux in relation to both the energy input by the wind and the dissipation by turbulence. The results indicate that the wave packets carry approximately 30-40% of the wind input of inertial kinetic energy, and propagate in an environment conducive to the occurrence of a critical level set up by a combination of vertical gradients in background relative vorticity and Doppler shifting of wave frequency. Turbulent kinetic energy dissipation measurements demonstrate that the waves lose energy as they propagate in the transition layer as well as in the pycnocline, where approaching this critical level may have dissipated approximately 20% of the wave packet energy in a single event. Our analysis, therefore, supports the notion that appreciable amounts of wind-induced inertial kinetic energy escape the surface boundary layer into the interior. However, a large fraction of wave energy is dissipated within the pycnocline, limiting its penetration into the abyssal ocean.

  19. The synoptic setting and possible energy sources for mesoscale wave disturbances

    NASA Technical Reports Server (NTRS)

    Uccellini, Louis W.; Koch, Steven E.

    1987-01-01

    Published data on 13 cases of mesoscale wave disturbances and their environment were examined to isolate common features for these cases and to determine possible energy sources for the waves. These events are characterized by either a singular wave of depression or wave packets with periods of 1-4 h, horizontal wavelengths of 50-500 km, and surface-pressure perturbation amplitudes of 0.2-7.0 mb. These wave events are shown to be associated with a distinct synoptic pattern (including the existence of a strong inversion in the lower troposphere and the propagation of a jet streak toward a ridge axis in the upper troposphere) while displaying little correlation with the presence of convective storm cells. The observed development of the waves is consistent with the hypothesis that the energy source needed to initiate and sustain the wave disturbances may be related to a geostrophic adjustment process associated with upper-tropospheric jet streaks.

  20. Estimating wave energy dissipation in the surf zone using thermal infrared imagery

    NASA Astrophysics Data System (ADS)

    Carini, Roxanne J.; Chickadel, C. Chris; Jessup, Andrew T.; Thomson, Jim

    2015-06-01

    Thermal infrared (IR) imagery is used to quantify the high spatial and temporal variability of dissipation due to wave breaking in the surf zone. The foam produced in an actively breaking crest, or wave roller, has a distinct signature in IR imagery. A retrieval algorithm is developed to detect breaking waves and extract wave roller length using measurements taken during the Surf Zone Optics 2010 experiment at Duck, NC. The remotely derived roller length and an in situ estimate of wave slope are used to estimate dissipation due to wave breaking by means of the wave-resolving model by Duncan (1981). The wave energy dissipation rate estimates show a pattern of increased breaking during low tide over a sand bar, consistent with in situ turbulent kinetic energy dissipation rate estimates from fixed and drifting instruments over the bar. When integrated over the surf zone width, these dissipation rate estimates account for 40-69% of the incoming wave energy flux. The Duncan (1981) estimates agree with those from a dissipation parameterization by Janssen and Battjes (2007), a wave energy dissipation model commonly applied within nearshore circulation models.

  1. The physical basis for estimating wave-energy spectra with the radar ocean-wave spectrometer

    NASA Technical Reports Server (NTRS)

    Jackson, Frederick C.

    1987-01-01

    The derivation of the reflectivity modulation spectrum of the sea surface for near-nadir-viewing microwave radars using geometrical optics is described. The equations required for the derivation are presented. The derived reflectivity modulation spectrum provides data on the physical basis of the radar ocean-wave spectrometer measurements of ocean-wave directional spectra.

  2. Effect of Stress on Energy Flux Deviation of Ultrasonic Waves in Ultrasonic Waves in GR/EP Composites

    NASA Technical Reports Server (NTRS)

    Prosser, William H.; Kriz, R. D.; Fitting, Dale W.

    1990-01-01

    Ultrasonic waves suffer energy flux deviation in graphite/epoxy because of the large anisotropy. The angle of deviation is a function of the elastic coefficients. For nonlinear solids, these coefficients and thus the angle of deviation is a function of stress. Acoustoelastic theory was used to model the effect of stress on flux deviation for unidirectional T300/5208 using previously measured elastic coefficients. Computations were made for uniaxial stress along the x3 axis fiber axis) and the x1 axis for waves propagating in the x1x3 plane. These results predict a shift as large as three degrees for the quasi-transverse wave. The shift in energy flux offers new nondestructive technique of evaluating stress in composites.

  3. Magnetic helicity conservation and inverse energy cascade in electron magnetohydrodynamic wave packets.

    PubMed

    Cho, Jungyeon

    2011-05-13

    Electron magnetohydrodynamics (EMHD) provides a fluidlike description of small-scale magnetized plasmas. An EMHD wave propagates along magnetic field lines. The direction of propagation can be either parallel or antiparallel to the magnetic field lines. We numerically study propagation of three-dimensional (3D) EMHD wave packets moving in one direction. We obtain two major results. (1) Unlike its magnetohydrodynamic (MHD) counterpart, an EMHD wave packet is dispersive. Because of this, EMHD wave packets traveling in one direction create opposite-traveling wave packets via self-interaction and cascade energy to smaller scales. (2) EMHD wave packets traveling in one direction clearly exhibit inverse energy cascade. We find that the latter is due to conservation of magnetic helicity. We compare inverse energy cascade in 3D EMHD turbulence and two-dimensional (2D) hydrodynamic turbulence. PMID:21668138

  4. Magnetic Helicity Conservation and Inverse Energy Cascade in Electron Magnetohydrodynamic Wave Packets

    SciTech Connect

    Cho, Jungyeon

    2011-05-13

    Electron magnetohydrodynamics (EMHD) provides a fluidlike description of small-scale magnetized plasmas. An EMHD wave propagates along magnetic field lines. The direction of propagation can be either parallel or antiparallel to the magnetic field lines. We numerically study propagation of three-dimensional (3D) EMHD wave packets moving in one direction. We obtain two major results. (1) Unlike its magnetohydrodynamic (MHD) counterpart, an EMHD wave packet is dispersive. Because of this, EMHD wave packets traveling in one direction create opposite-traveling wave packets via self-interaction and cascade energy to smaller scales. (2) EMHD wave packets traveling in one direction clearly exhibit inverse energy cascade. We find that the latter is due to conservation of magnetic helicity. We compare inverse energy cascade in 3D EMHD turbulence and two-dimensional (2D) hydrodynamic turbulence.

  5. Quantified Energy Dissipation Rates in the Terrestrial Bow Shock. 2; Waves and Dissipation

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Sibeck, D. G.; Breneman, A. W.; Le Contel, O.; Cully, C.; Turner, D. L.; Angelopoulos, V.; Malaspina, D. M.

    2014-01-01

    We present the first quantified measure of the energy dissipation rates, due to wave-particle interactions, in the transition region of the Earth's collision-less bow shock using data from the Time History of Events and Macro-Scale Interactions during Sub-Storms spacecraft. Our results show that wave-particle interactions can regulate the global structure and dominate the energy dissipation of collision-less shocks. In every bow shock crossing examined, we observed both low-frequency (less than 10 hertz) and high-frequency (approximately or greater than10 hertz) electromagnetic waves throughout the entire transition region and into the magnetosheath. The low-frequency waves were consistent with magnetosonic-whistler waves. The high-frequency waves were combinations of ion-acoustic waves, electron cyclotron drift instability driven waves, electrostatic solitary waves, and whistler mode waves. The high-frequency waves had the following: (1) peak amplitudes exceeding delta B approximately equal to 10 nanoteslas and delta E approximately equal to 300 millivolts per meter, though more typical values were delta B approximately equal to 0.1-1.0 nanoteslas and delta E approximately equal to 10-50 millivolts per meter (2) Poynting fluxes in excess of 2000 microWm(sup -2) (micro-waves per square meter) (typical values were approximately 1-10 microWm(sup -2) (micro-waves per square meter); (3) resistivities greater than 9000 omega meters; and (4) associated energy dissipation rates greater than 10 microWm(sup -3) (micro-waves per cubic meter). The dissipation rates due to wave-particle interactions exceeded rates necessary to explain the increase in entropy across the shock ramps for approximately 90 percent of the wave burst durations. For approximately 22 percent of these times, the wave-particle interactions needed to only be less than or equal to 0.1 percent efficient to balance the nonlinear wave steepening that produced the shock waves. These results show that wave

  6. Protocol to Exploit Waiting Resources for UASNs †

    PubMed Central

    Hung, Li-Ling; Luo, Yung-Jeng

    2016-01-01

    The transmission speed of acoustic waves in water is much slower than that of radio waves in terrestrial wireless sensor networks. Thus, the propagation delay in underwater acoustic sensor networks (UASN) is much greater. Longer propagation delay leads to complicated communication and collision problems. To solve collision problems, some studies have proposed waiting mechanisms; however, long waiting mechanisms result in low bandwidth utilization. To improve throughput, this study proposes a slotted medium access control protocol to enhance bandwidth utilization in UASNs. The proposed mechanism increases communication by exploiting temporal and spatial resources that are typically idle in order to protect communication against interference. By reducing wait time, network performance and energy consumption can be improved. A performance evaluation demonstrates that when the data packets are large or sensor deployment is dense, the energy consumption of proposed protocol is less than that of existing protocols as well as the throughput is higher than that of existing protocols. PMID:27005624

  7. Energy transfer by inertial waves during the buildup of turbulence in a rotating system.

    PubMed

    Kolvin, Itamar; Cohen, Kobi; Vardi, Yuval; Sharon, Eran

    2009-01-01

    We study the transition from fluid at rest to turbulence in a rotating tank. The energy is transported by inertial wave packets through the fluid volume. These high amplitude waves propagate at velocities consistent with those calculated from linearized theory [H. P. Greenspan, (Cambridge University Press, Cambridge, England, 1968)]. A "front" in the temporal evolution of the energy power spectrum indicates a time scale for energy transport at the linear wave speed. Nonlinear energy transfer between modes is governed by a different, longer, time scale. The observed mechanisms can lead to significant differences between rotating and two-dimensional turbulent flows. PMID:19257200

  8. A geospatial assessment of the relationship between reef flat community calcium carbonate production and wave energy

    NASA Astrophysics Data System (ADS)

    Hamylton, S. M.; Pescud, A.; Leon, J. X.; Callaghan, D. P.

    2013-12-01

    The ability of benthic communities inhabiting coral reefs to produce calcium carbonate underpins the development of reef platforms and associated sedimentary landforms, as well as the fixation of inorganic carbon and buffering of diurnal pH fluctuations in ocean surface waters. Quantification of the relationship between reef flat community calcium carbonate production and wave energy provides an empirical basis for understanding and managing this functionally important process. This study employs geospatial techniques across the reef platform at Lizard Island, Great Barrier Reef, to (1) map the distribution and estimate the total magnitude of reef community carbonate production and (2) empirically ascertain the influence of wave energy on community carbonate production. A World-View-2 satellite image and a field data set of 364 ground referencing points are employed, along with data on physical reef characteristics (e.g. bathymetry, rugosity) to map and validate the spatial distribution of the four major community carbonate producers (live coral, carbonate sand, green calcareous macroalgae and encrusting calcified algae) across the reef platform. Carbonate production is estimated for the complete reef platform from the composition of these community components. A synoptic model of wave energy is developed using the Simulating WAves Nearshore (SWAN) two-dimensional model for the entire reef platform. The relationship between locally derived measures of carbonate production and wave energy is evaluated at both the global scale and local scale along spatial gradients of wave energy traversing the reef platform. A wave energy threshold is identified, below which carbonate production levels appear to increase with wave energy and above which mechanical forcing reduces community production. This implies an optimal set of hydrodynamic conditions characterized by wave energy levels of approximately 300 J m-2, providing an empirical basis for management of potential changes

  9. Small amplitude transverse waves on taut strings: exploring the significant effects of longitudinal motion on wave energy location and propagation

    NASA Astrophysics Data System (ADS)

    Rowland, David R.

    2013-03-01

    Introductory discussions of energy transport due to transverse waves on taut strings universally assume that the effects of longitudinal motion can be neglected, but this assumption is not even approximately valid unless the string is idealized to have a zero relaxed length, a requirement approximately met by the slinky spring. While making this additional idealization is probably the best approach to take when discussing waves on strings at the introductory level, for intermediate to advanced undergraduate classes in continuum mechanics and general wave phenomena where somewhat more realistic models of strings can be investigated, this paper makes the following contributions. First, various approaches to deriving the general energy continuity equation are critiqued and it is argued that the standard continuum mechanics approach to deriving such equations is the best because it leads to a conceptually clear, relatively simple derivation which provides a unique answer of greatest generality. In addition, a straightforward algorithm for calculating the transverse and longitudinal waves generated when a string is driven at one end is presented and used to investigate a cos2 transverse pulse. This example illustrates much important physics regarding energy transport in strings and allows the ‘attack waves’ observed when strings in musical instruments are struck or plucked to be approximately modelled and analysed algebraically. Regarding the ongoing debate as to whether the potential energy density in a string can be uniquely defined, it is shown by coupling an external energy source to a string that a suggested alternative formula for potential energy density requires an unphysical potential energy to be ascribed to the source for overall energy to be conserved and so cannot be considered to be physically valid.

  10. Dissipation of modified entropic gravitational energy through gravitational waves

    NASA Astrophysics Data System (ADS)

    de Matos, Clovis Jacinto

    2012-01-01

    The phenomenological nature of a new gravitational type interaction between two different bodies derived from Verlinde's entropic approach to gravitation in combination with Sorkin's definition of Universe's quantum information content, is investigated. Assuming that the energy stored in this entropic gravitational field is dissipated under the form of gravitational waves and that the Heisenberg principle holds for this system, one calculates a possible value for an absolute minimum time scale in nature tau=15/16 Λ^{1/2}hbar G/c4˜9.27×10^{-105} seconds, which is much smaller than the Planck time t P =( ħG/ c 5)1/2˜5.38×10-44 seconds. This appears together with an absolute possible maximum value for Newtonian gravitational forces generated by matter Fg=32/30c7/Λ hbar G2˜ 3.84× 10^{165} Newtons, which is much higher than the gravitational field between two Planck masses separated by the Planck length F gP = c 4/ G˜1.21×1044 Newtons.

  11. Design of the dual-buoy wave energy converter based on actual wave data of East Sea

    NASA Astrophysics Data System (ADS)

    Kim, Jeongrok; Kweon, Hyuck-Min; Jeong, Weon-Mu; Cho, Il-Hyoung; Cho, Hong-Yeon

    2015-07-01

    A new conceptual dual-buoy Wave Energy Converter (WEC) for the enhancement of energy extraction efficiency is suggested. Based on actual wave data, the design process for the suggested WEC is conducted in such a way as to ensure that it is suitable in real sea. Actual wave data measured in Korea's East Sea (position: 36.404 N° and 129.274 E°) from May 1, 2002 to March 29, 2005 were used as the input wave spectrum for the performance estimation of the dual-buoy WEC. The suggested WEC, a point absorber type, consists of two concentric floating circular cylinders (an inner and a hollow outer buoy). Multiple resonant frequencies in proposed WEC affect the Power Ttake-off (PTO) performance of the WEC. Based on the numerical results, several design strategies are proposed to further enhance the extraction efficiency, including intentional mismatching among the heave natural frequencies of dual buoys, the natural frequency of the internal fluid, and the peak frequency of the input wave spectrum.

  12. Dissipation of wave energy and turbulence in a shallow coral reef lagoon

    NASA Astrophysics Data System (ADS)

    Huang, Zhi-Cheng; Lenain, Luc; Melville, W. Kendall; Middleton, Jason H.; Reineman, Benjamin; Statom, Nicholas; McCabe, Ryan M.

    2012-03-01

    Simultaneous in situ measurements of waves, currents and turbulence are presented to describe dissipation rates of wave energy and turbulent kinetic energy in the windward coral reef-lagoon system at Lady Elliot Island (LEI), Australia. The dissipation of wave energy in the lagoon is tidally modulated and strongly correlates with frictional dissipation due to the presence of the extremely rough bottom boundary. The observed turbulent kinetic energy (TKE) dissipation rate, ɛ, in this wave-dominated lagoon is much larger than recently reported values for unidirectional flows over natural fringing coral reefs. The correlation between the wave dissipation and ɛ is examined. The average rate of dissipation induced by the rough turbulent flow was estimated directly from the observed ɛ coupled with both a depth-integrated approach and with a bottom boundary layer scaling. Rates of TKE dissipation estimated using the two approaches approximate well, within a factor of 1.5 to 2.4, to the surface-wave energy dissipation rate. The wave dissipation and friction factor in the lagoon can be described by a spectral wave-frictional model with a bottom roughness length scale that is approximately constant across the lagoon. We also present estimates of dissipation induced by the canopy drag force of the coral heads. The dissipation in this case is enhanced and becomes more significant for the total energy dissipation when the water depth in the lagoon is comparable to the height of the coral heads.

  13. Wave energy level and geographic setting correlate with Florida beach water quality.

    PubMed

    Feng, Zhixuan; Reniers, Ad; Haus, Brian K; Solo-Gabriele, Helena M; Kelly, Elizabeth A

    2016-03-15

    Many recreational beaches suffer from elevated levels of microorganisms, resulting in beach advisories and closures due to lack of compliance with Environmental Protection Agency guidelines. We conducted the first statewide beach water quality assessment by analyzing decadal records of fecal indicator bacteria (enterococci and fecal coliform) levels at 262 Florida beaches. The objectives were to depict synoptic patterns of beach water quality exceedance along the entire Florida shoreline and to evaluate their relationships with wave condition and geographic location. Percent exceedances based on enterococci and fecal coliform were negatively correlated with both long-term mean wave energy and beach slope. Also, Gulf of Mexico beaches exceeded the thresholds significantly more than Atlantic Ocean ones, perhaps partially due to the lower wave energy. A possible linkage between wave energy level and water quality is beach sand, a pervasive nonpoint source that tends to harbor more bacteria in the low-wave-energy environment. PMID:26892203

  14. Gravitational waves, energy and Feynman’s “sticky bead”

    NASA Astrophysics Data System (ADS)

    Cooperstock, F. I.

    2015-07-01

    It is noted that in the broader sense, gravitational waves viewed as spacetime curvature which necessarily accompanies electromagnetic waves at the speed of light, are the routine perception of our everyday experience. We focus on the energy issue and Feynman’s “sticky bead” argument which has been regarded as central in supporting the conclusion that gravitational waves carry energy through the vacuum in general relativity. We discuss the essential neglected aspects of his approach which leads to the conclusion that gravitational waves would not cause Feynman’s bead to heat the stick on which it would supposedly rub. This opens the way to an examination of the entire issue of energy in general relativity. We briefly discuss our naturally-defined totally invariant spacetime energy expression for general relativity incorporating the contribution from gravity. When the cosmological term is included in the field equations, our energy expression includes the vacuum energy as required.

  15. Wave energy saturation on a natural beach of variable slope.

    USGS Publications Warehouse

    Sallenger, A.H., Jr.; Holman, R.A.

    1985-01-01

    Time series of flow were measured across the inner surf zone during a storm. These data were used to quantify the dependence of wave height (transformed from measured flow) and velocity on local slope and depth. Local depth increased with local slope and was independent of deepwater wave steepness.-from Authors

  16. Energy propagation by transverse waves in multiple flux tube systems using filling factors

    SciTech Connect

    Van Doorsselaere, T.; Gijsen, S. E.; Andries, J.; Verth, G. E-mail: stief.gijsen@wis.kuleuven.be E-mail: g.verth@sheffield.ac.uk

    2014-11-01

    In the last few years, it has been found that transverse waves are present at all times in coronal loops or spicules. Their energy has been estimated with an expression derived for bulk Alfvén waves in homogeneous media, with correspondingly uniform wave energy density and flux. The kink mode, however, is localized in space with the energy density and flux dependent on the position in the cross-sectional plane. The more relevant quantities for the kink mode are the integrals of the energy density and flux over the cross-sectional plane. The present paper provides an approximation to the energy propagated by kink modes in an ensemble of flux tubes by means of combining the analysis of single flux tube kink oscillations with a filling factor for the tube cross-sectional area. This finally allows one to compare the expressions for energy flux of Alfvén waves with an ensemble of kink waves. We find that the correction factor for the energy in kink waves, compared to the bulk Alfvén waves, is between f and 2f, where f is the density filling factor of the ensemble of flux tubes.

  17. Investigation on the possibility of extracting wave energy from the Texas coast

    NASA Astrophysics Data System (ADS)

    Haces-Fernandez, Francisco

    Due to the great and growing demand of energy consumption in the Texas Coast area, the generation of electricity from ocean waves is considered very important. The combination of the wave energy with offshore wind power is explored as a way to increase power output, obtain synergies, maximize the utilization of assigned marine zones and reduce variability. Previously literature has assessed the wave energy generation, combined with wind in different geographic locations such as California, Ireland and the Azores Island. In this research project, the electric power generation from ocean waves on the Texas Coast was investigated, assessing its potential from the meteorological data provided by five buoys from National Data Buoy Center of the National Oceanic and Atmospheric Administration, considering the Pelamis 750 kW Wave Energy Converter (WEC) and the Vesta V90 3 MW Wind Turbine. The power output from wave energy was calculated for the year 2006 using Matlab, and the results in several locations were considered acceptable in terms of total power output, but with a high temporal variability. To reduce its variability, wave energy was combined with wind energy, obtaining a significant reduction on the coefficient of variation on the power output. A Matlab based interface was created to calculate power output and its variability considering data from longer periods of time.

  18. The role of coral reef rugosity in dissipating wave energy and coastal protection

    NASA Astrophysics Data System (ADS)

    Harris, Daniel; Rovere, Alessio; Parravicini, Valeriano; Casella, Elisa

    2016-04-01

    Coral reefs are the most effective natural barrier in dissipating wave energy through breaking and bed friction. The attenuation of wave energy by coral reef flats is essential in the protection and stability of coral reef aligned coasts and reef islands. However, the effectiveness of wave energy dissipation by coral reefs may be diminished under future climate change scenarios with a potential reduction of coral reef rugosity due to increased stress environmental stress on corals. The physical roughness or rugosity of coral reefs is directly related to ecological diversity, reef health, and hydrodynamic roughness. However, the relationship between physical roughness and hydrodynamic roughness is not well understood despite the crucial role of bed friction in dissipating wave energy in coral reef aligned coasts. We examine the relationship between wave energy dissipation across a fringing reef in relation to the cross-reef ecological zonation and the benthic hydrodynamic roughness. Waves were measured by pressure transducers in a cross-reef transect on the reefs flats and post processed on a wave by wave basis to determine wave statistics such as significant wave height and wave period. Results from direct wave measurement were then used to calibrate a 1D wave dissipation model that incorporates dissipation functions due to bed friction and wave breaking. This model was used to assess the bed roughness required to produce the observed wave height dissipation during propagation from deep water and across the coral reef flats. Changes in wave dissipation was also examined under future scenarios of sea level rise and reduced bed roughness. Three dimensional models of the benthic reef structure were produced through structure-from-motion photogrammetry surveys. Reef rugosity was then determined from these surveys and related to the roughness results from the calibrated model. The results indicate that applying varying roughness coefficients as the benthic ecological

  19. Three-dimensional sound signals and their relevance to wave energy quantities and sound interference products

    NASA Astrophysics Data System (ADS)

    Vassilakis, Pantelis

    2003-10-01

    Signals are graphic representations of vibrations/waves and, like every representation, capture only selected attributes of the phenomenon they are meant to represent. The often assumed equivalence between signals and sound waves obscures the fact that two-dimensional signals are not fit to (a) represent wave-energy quantities consistently across frequencies, (b) account for the alternating positive/negative amplitude values of modulated waves with AM-depth>100%, and (c) represent the energy content of interference. An alternative sound-signal representation is proposed, based on the complex equation of motion describing a wave. It results in spiral sine signals and twisted-spiral complex signals, similar to complex analytic signals. Spiral sine signals offer a consistent measure of sine-wave energy across frequencies, while twisted spiral complex signals account for the negative amplitudes observed in modulated signals and map the modulation parameters onto the twisting parameters. In terms of interference, 3-D signals illustrate that amplitude fluctuations and the signal envelopes that describe them are not just boundary curves but waves that trace changes in the total instantaneous energy of a signal over time, representing the oscillation between potential and kinetic energies within a wave. Examples of 3-D animations illustrating the proposed signals are presented. a)Work completed while at the Department of Ethnomusicology, University of California, Los Angeles.

  20. Wave energy gradients across a Maldivian atoll: Implications for island geomorphology

    NASA Astrophysics Data System (ADS)

    Kench, Paul S.; Brander, Robert W.; Parnell, Kevin E.; McLean, Roger F.

    2006-11-01

    Exposure to wave energy has been used to account for a range of ecological, geological and geomorphic processes in coral reef systems, but few attempts have been made to quantify spatial variations in energy at the atoll scale. This study presents results of measurements of wave energy on reef platforms across South Maalhosmadulu Atoll, Maldives and their implications for island geomorphology. The atoll has a perforated rim (37% effective aperture) and experiences predictable shifts in monsoon winds from the west (8 months) and northeast (4 months). Results show that wave energy affecting the atoll is considerably greater during the westerly monsoon. Atoll structure promotes significant changes in wave energy and wave characteristics across the atoll. Short period (3-8 s) monsoon-driven wave energy, which is significant on windward reefs, is dissipated on the peripheral reef network and the density of lagoonal patch reefs limits development of locally generated wind-wave energy across the lagoon. However, longer period swell (8-20 s) propagates through the lagoon to leeward reefs. A windward to leeward decay in wave energy is evident in the westerly monsoon, but not in the northeast monsoon, when long period swell (from the southwest) remains significant on western reefs. Net energy calculations that account for seasonal changes in wave energy across the atoll identify a steep west-east gradient that has geomorphic significance for island building. Western reefs are dominated by westerly flowing energy that is 4.5-7 times the total energy input elsewhere in the atoll. Wave energy on central reefs is balanced, whereas net energy on eastern reef platforms is dominated by eastward propagating waves. This steep energy gradient provides a physical explanation for the presence and distribution of islands on reef platforms across the atoll and provides quantitative support for the theory of Gardiner [Gardiner, J.S., 1903. The Fauna and Geography of the Maldives and

  1. 75 FR 21289 - Oregon Wave Energy Partners I, LLC; Notice of Preliminary Permit Application Accepted for Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-23

    ... Energy Regulatory Commission Oregon Wave Energy Partners I, LLC; Notice of Preliminary Permit Application..., 2010. On March 2, 2010, Oregon Wave Energy Partners I, LLC filed an application for a subsequent... the Coos Bay OPT Wave Park Project. The requested project boundary comprises approximately 7.36...

  2. Direct and inverse cascades of energy, momentum and wave action in spectra of wind-driven waves

    NASA Astrophysics Data System (ADS)

    Badulin, S. I.; Pushkarev, A. N.; Resio, D.; Zakharov, V. E.

    2003-04-01

    The time-dependent, spatially uniform Hasselmann's kinetic equation for surface gravity waves in presence of wind forcing and white-capping dissipation is studied numerically. We use conventional parameterizations of wind wave input (Snyder et al. 1981; Plant 1982; Hsiao &Shemdin 1983; Donelan, Pierson 1987) that are consistent with weakly nonlinear scaling. We assume that strong dissipation due to white-capping is essential for short waves only (with frequencies above 1Hz) belonging to the spectral tail and can be neglected near the spectral peak. We compare our numerical results with the predictions of the theory of weak turbulence and found a very good coincidence. It is shown that asymptotic behavior of wave spectra is in perfect agreement with stationary solutions of the Hasselmann equation -- Kolmogorov's solutions for direct (Zakharov & Filonenko 1966) and inverse (Zakharov &Zaslavskii 1982) cascades. This asymptotic behavior appears at rather early stages of wind wave evolution (physical time of order of few hours in our experiments); A strong tendency of solutions to self-similar behavior of duration limited solutions is found for rather wide range of initial conditions and external forcing; Good quantitative coincidence with recapitulative experimental data for duration limited wind wave growth (Young 1999, p.111) and for fetch-limited (JONSWAP) spectra parameterized by wave age C_p/Uwind is found. The findings here are quite robust and hopefully will be applied to the practical problems. Present wave prediction models are based on fairly crude parameterizations of the nonlinear energy transfers. In large part due to inaccuracies in these parameterizations, these models have had to rely on empirical fitting of general growth equation as a basis for constraining additional source-sink terms in the detailed balance equations. Results from this study could be used to reformulate a complete energy balance equation for wave generation, propagation and decay

  3. The impact energy of a moored tanker under the action of regular waves

    SciTech Connect

    Yu-Cheng Li

    1982-09-01

    The influence that factors such as mooring line conditions, fender arrangements, dolphin arrangements, degree of ship loading, waves of long period, wave direction, and wind on the impact energy of a moored tanker were studied. Based on systematic test data, a semi-empirical formula was developed to calculate the impact energy of the moored ship on the berthing facilities under the action of regular waves. It was shown by experiment that this method is suitable for calculating the impact energy of moored ships of capacities as great as 200 X 10/sup 3/ t.

  4. Exploiting Co-solubilization of Warfarin, Curcumin, and Rhodamine B for Modulation of Energy Transfer: A Micelle FRET On/Off Switch.

    PubMed

    Bhat, Parvaiz Ahmad; Chat, Oyais Ahmad; Dar, Aijaz Ahmad

    2016-08-01

    Two new FRET pairs, warfarin (WF)-curcumin (CUR) and curcumin-rhodamine B (RhB), are explored by using surfactant-based self-assembled soft systems as scaffolds. The study is extended to design a two-step concurrent FRET system based on these three fluorophores, which is an important mechanism to devise artificial light-harvesting/antenna systems. Surfactant systems of varying nature (cationic, anionic, nonionic, and zwitterionic) are exploited to modulate the energy transfer in different FRET systems. Interestingly, micelle/water interfacial-charge-responsive FRET is observed owing to selective solubilization of the fluorophores during co-solubilization. The step-one FRET (WF→CUR) is switched on in cationic and zwitterionic media but switched off in anionic/nonionic media, whereas the step-two FRET from CUR to RhB is switched on in anionic/nonionic and zwitterionic media. However, both the FRET steps (WF→CUR→RhB) are observed to be active only in zwitterionic medium. Co-solubilized, appropriately mixed fluorophores having multistep FRET possibilities can be switched on/off selectively as and when required and energy efficiency can be tuned to an optimal level by varying the nature and geometry of the micellar scaffold. Thus, the two FRET pairs selectively acknowledge all types of media for their anticipated applications in biological systems, as structural tools, and for the development of artificial light-harvesting/antenna systems and lasers. PMID:27123553

  5. Mechanisms of Surface Wave Energy Dissipation over a Fluid Mud Sediment Suspension

    NASA Astrophysics Data System (ADS)

    Traykovski, P.; Trowbridge, J. H.; Kineke, G. C.

    2014-12-01

    Field observations from the spring of 2008 on the Louisiana shelf were used to elucidate the mechanisms of wave energy dissipation over a muddy seafloor. After a period of high discharge from the Atchafalaya River acoustic measurements showed the presence of 20 cm thick mobile fluid mud layers during and after wave events. While total wave energy dissipation (D) was greatest during the high energy periods, these periods had relatively low normalized attenuation rates (Κ = Dissipation/Energy Flux). During declining wave energy conditions, as the fluid mud layer settled, the attenuation process became more efficient with high Κ and low D. The transition from high D and low Κ to high Κ and low D was caused by a transition from turbulent to laminar flow in the fluid mud layer as measured by a Pulse-coherent Doppler profiler. Measurements of the oscillatory boundary layer velocity profile in the fluid mud layer during laminar flow reveal a very thick wave boundary layer with curvature filling the entire fluid mud layer, suggesting a kinematic viscosity two to three orders of magnitude greater than clear water. This high viscosity is also consistent with a high wave attenuation rates measured by across shelf energy flux differences. The transition to turbulence was forced by instabilities on the lutocline, with wavelengths consistent with the dispersion relation for this two layer system. The measurements also provide new insight into the dynamics of wave supported turbidity flows during the transition from a laminar to turbulent fluid mud layer.

  6. EFFECTS OF CONTINUOUS-WAVE, PULSED, AND SINUSOIDAL-AMPLITUDE-MODULATED MICROWAVES ON BRAIN ENERGY METABOLISM

    EPA Science Inventory

    A comparison of the effects of continuous wave, sinusoidal-amplitude modulated, and pulsed square-wave-modulated 591-MHz microwave exposures on brain energy metabolism was made in male Sprague Dawley rats (175-225g). Brain NADH fluorescence, adensine triphosphate (ATP) concentrat...

  7. Threshold Energy Density of Lower Hybrid Waves in the Freja Experiment

    SciTech Connect

    Popel, S. I.

    2001-05-15

    Data from the Freja satellite experiment on the lower hybrid turbulence in the Earth's magnetosphere are analyzed. It is shown that the observed threshold energy density of lower hybrid waves required for the excitation of localized wave packets is in good agreement with theoretical predictions.

  8. Evaluation of Environmental Effects of Wave Energy Convertor Arrays

    NASA Astrophysics Data System (ADS)

    Jones, C. A.

    2015-12-01

    Stakeholders and regulators in the U.S. are generally uncertain as to the potential environmental impacts posed by deployments of marine and hydrokinetic (MHK) devices, and in particular wave energy conversion (WEC) devices, in coastal waters. The first pilot-scale WEC deployments in the U.S. have had to absorb unsustainable costs and delays associated with permitting to get devices in the water. As such, there is an urgent industry need to streamline the technical activities and processes used to assess potential environmental impacts. To enable regulators and stakeholders to become more comfortable and confident with developing effective MHK environmental assessments, a better understanding of the potential environmental effects induced by arrays of WEC devices is needed. A key challenge in developing this understanding is that the assessment of the WEC effects must come prior to deployment. A typical approach in similar environmental assessments is to use numerical models to simulate the WEC devices and array layouts so that the appropriate environmental stressors and receptors can be identified and assessed. Sandia National Laboratories (SNL) and the U.S. Department of Energy are fulfilling the industry-wide need to develop "WEC-friendly" open-source numerical modeling tools capable of assessing potential changes to the physical environment caused by the operation of WEC arrays. Studies using these tools will advance the nation's general knowledge of the interrelationships among the number, size, efficiency, and configuration of MHK arrays and the subsequent effects these relationships may have on the deployment environment. By better understanding these relationships, industry, stakeholders, and regulators will be able to work together to optimize WEC deployments such that environmental impacts are minimized while power output is maximized. The present work outlines the initial effort in coupling the SNL WEC-friendly tools with the environmental assessment

  9. Coupling of ICRF waves and axial transport of high-energy ions owing to spontaneously excited waves in the GAMMA 10 tandem mirror

    NASA Astrophysics Data System (ADS)

    Ikezoe, R.; Ichimura, M.; Hirata, M.; Iwai, T.; Yokoyama, T.; Ugajin, Y.; Sato, T.; Iimura, T.; Saito, Y.; Yoshikawa, M.; Kohagura, J.; Shima, Y.; Imai, T.

    2013-07-01

    Plasmas with high ion temperature of several kiloelectronvolts and a strong temperature anisotropy of greater than 10 were produced by ion cyclotron range of frequency (ICRF) heating in the GAMMA 10 tandem mirror. In such high-performance plasmas with strong anisotropy, high-frequency fluctuations, so-called Alfvén-ion-cyclotron (AIC) waves, are excited spontaneously. These AIC waves have several discrete peaks in the frequency spectrum. Coupling of the ICRF heating waves and the excited AIC waves was clearly observed in the density fluctuations measured with a newly developed reflectometer. Parametric decay from the heating ICRF waves to the AIC waves and low-frequency waves was also indicated. Alfvén waves with difference frequencies between the discrete peaks of the AIC waves were detected in a signal that measured the number of axially transported high-energy ions (over 6 keV) at the machine end, indicating pitch-angle scattering caused by the low-frequency waves. Energy transport along the magnetic field line is an important consideration when ICRF power is injected in the perpendicular direction to a magnetic field line. The importance of the spontaneously excited AIC waves for axial confinement of a tandem mirror through wave-wave couplings was demonstrated.

  10. Energy extraction from ocean currents and waves: Mapping the most promising locations

    NASA Astrophysics Data System (ADS)

    Ordonez, A.; Hamlington, P.; Fox-Kemper, B.

    2012-12-01

    Concerns about fossil fuel supplies and an ever-increasing demand for energy have prompted the search for alternative power sources. One option is the ocean, a power-dense and renewable source of energy, but its capacity to meet human energy demands is poorly understood. Although raw wave energy resources have been investigated at many scales, there is still substantial uncertainty regarding how much useful power can be extracted. Even less is known about the energy available in ocean currents, especially on a global scale. Moreover, no studies have attempted to examine wave and current energy simultaneously while at the same time taking into account geographical, environmental, and technical factors that can substantially limit the amount of extractable energy. In this study, we use high fidelity oceanographic model data to assess the availability, recoverability, and value of energy in ocean wind waves and currents. Global wave energy transport, coastal wave energy flux, and current energy are calculated and mapped using the model data. These maps are then incorporated into a geographic information system (GIS) in order to assess the U.S. recoverable ocean energy resource. In the GIS, the amount of recoverable energy is estimated by combining the power output from realistic wave and current energy farms with physical and ecological data such as bathymetry and environmentally protected areas. This holistic approach is then used to examine the distribution and value of extractable wave and current energy along the U.S. coast. The results support previous studies that show that the U.S. West Coast has large potential for wave energy extraction and that the Florida Strait has high potential for current energy extraction. We also show that, at any particular location, the amount of available ocean energy is only one factor of many that determines the ultimate feasibility and value of the energy. We outline ways in which the GIS framework used in this assessment can be

  11. Energy spectrum analysis of blast waves based on an improved Hilbert-Huang transform

    NASA Astrophysics Data System (ADS)

    Li, L.; Wang, F.; Shang, F.; Jia, Y.; Zhao, C.; Kong, D.

    2016-07-01

    Using the improved Hilbert-Huang transform (HHT), this paper investigates the problems of analysis and interpretation of the energy spectrum of a blast wave. It has been previously established that the energy spectrum is an effective feature by which to characterize a blast wave. In fact, the higher the energy spectra in a frequency band of a blast wave, the greater the damage to a target in the same frequency band. However, most current research focuses on analyzing wave signals in the time domain or frequency domain rather than considering the energy spectrum. We propose here an improved HHT method combined with a wavelet packet to extract the energy spectrum feature of a blast wave. When applying the HHT, the signal is first roughly decomposed into a series of intrinsic mode functions (IMFs) by empirical mode decomposition. The wavelet packet method is then performed on each IMF to eliminate noise on the energy spectrum. Second, a coefficient is introduced to remove unrelated IMFs. The energy of each instantaneous frequency can be derived through the Hilbert transform. The energy spectrum can then be obtained by adding up all the components after the wavelet packet filters and screens them through a coefficient to obtain the effective IMFs. The effectiveness of the proposed method is demonstrated by 12 groups of experimental data, and an energy attenuation model is established based on the experimental data. The improved HHT is a precise method for blast wave signal analysis. For other shock wave signals from blasting experiments, an energy frequency time distribution and energy spectrum can also be obtained through this method, allowing for more practical applications.

  12. PC-5 Waves and Low Energy Plasma in the Outer Magnetosphere

    NASA Technical Reports Server (NTRS)

    Gallanger, Dennis L.; Vaisberg, Oleg L.; Coffey, Victoria N.

    1999-01-01

    The Interball Tail Probe crosses the dayside magnetopause at low latitudes where it frequently measures low energy ion plasma (<100 eV) in the outer magnetosphere. We present the wave characteristics associated with this cold component.

  13. High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration.

    PubMed

    Yang, Zhen; Wang, Yuye; Xu, Degang; Xu, Wentao; Duan, Pan; Yan, Chao; Tang, Longhuang; Yao, Jianquan

    2016-05-15

    A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning in a wide frequency range. Through the special optical design with a galvano-optical scanner and four-mirror ring-cavity structure, the maximum THz wave output energy of 12.9 μJ/pulse is achieved at 1.359 THz under the pump energy of 172.8 mJ. The fast THz frequency tuning in the range of 0.7-2.8 THz can be accessed with the step response of 600 μs. Moreover, the maximum THz wave output energy from this configuration is 3.29 times as large as that obtained from the conventional surface-emitted THz wave parametric oscillator with the same experimental conditions. PMID:27176978

  14. On the interpretation of energy and energy fluxes of nonlinear internal waves: An example from Massachusetts Bay

    USGS Publications Warehouse

    Scotti, A.; Beardsley, R.; Butman, B.

    2006-01-01

    A self-consistent formalism to estimate baroclinic energy densities and fluxes resulting from the propagation of internal waves of arbitrary amplitude is derived using the concept of available potential energy. The method can be applied to numerical, laboratory or field data. The total energy flux is shown to be the sum of the linear energy flux ??? u??? p??? dz (primes denote baroclinic quantities), plus contributions from the non-hydrostatic pressure anomaly and the self-advection of kinetic and available potential energy. Using highly resolved observations in Massachusetts Bay, it is shown that due to the presence of nonlinear internal waves periodically propagating in the area, ??? u??? p??? dz accounts for only half of the total flux. The same data show that equipartition of available potential and kinetic energy can be violated, especially when the nonlinear waves begin to interact with the bottom. ?? 2006 Cambridge University Press.

  15. Tail effects in the third post-Newtonian gravitational wave energy flux of compact binaries in quasi-elliptical orbits

    SciTech Connect

    Arun, K. G.; Iyer, Bala R.; Qusailah, Moh'd S. S.

    2008-03-15

    The far-zone flux of energy contains hereditary (tail) contributions that depend on the entire past history of the source. Using the multipolar post-Minkowskian wave generation formalism, we propose and implement a semianalytical method in the frequency domain to compute these contributions from the inspiral phase of a binary system of compact objects moving in quasi-elliptical orbits up to third post-Newtonian (3PN) order. The method explicitly uses the quasi-Keplerian representation of elliptical orbits at 1PN order and exploits the doubly periodic nature of the motion to average the 3PN fluxes over the binary's orbit. Together with the instantaneous (nontail) contributions evaluated in a companion paper, it provides crucial inputs for the construction of ready-to-use templates for compact binaries moving on quasi-elliptic orbits, an interesting class of sources for the ground-based gravitational-wave detectors such as LIGO and Virgo, as well as space-based detectors like LISA.

  16. Electron energy transport in ion waves and its relevance to laser-produced plasmas

    SciTech Connect

    Bell, A.R.

    1983-01-01

    Electron energy transport in plasmas is examined in the context of ion waves which are intermediate between collisionless isothermal ion acoustic waves and collisional adiabatic sound waves. The conductivity is found to be much less than the Spitzer-Haerm result for wavelengths less than 1000 electron mean free paths. This is expected to be relevant to laser-produced ablating plasmas in which the temperature can vary considerably over a distance of 10 to 100 mean free paths. The reduction in conductivity is independent of the wave amplitude thus differing from the reduction due to saturation found recently by numerical solution of the Fokker--Planck equation. At short wavelengths the heat flow approaches an upper limit which depends on the phase velocity of the wave. Diffusive ion wave damping is strong over a large range of wavelengths.

  17. A framework for assessing the uncertainty in wave energy delivery to targeted subsurface formations

    NASA Astrophysics Data System (ADS)

    Karve, Pranav M.; Kallivokas, Loukas F.; Manuel, Lance

    2016-02-01

    Stress wave stimulation of geological formations has potential applications in petroleum engineering, hydro-geology, and environmental engineering. The stimulation can be applied using wave sources whose spatio-temporal characteristics are designed to focus the emitted wave energy into the target region. Typically, the design process involves numerical simulations of the underlying wave physics, and assumes a perfect knowledge of the material properties and the overall geometry of the geostructure. In practice, however, precise knowledge of the properties of the geological formations is elusive, and quantification of the reliability of a deterministic approach is crucial for evaluating the technical and economical feasibility of the design. In this article, we discuss a methodology that could be used to quantify the uncertainty in the wave energy delivery. We formulate the wave propagation problem for a two-dimensional, layered, isotropic, elastic solid truncated using hybrid perfectly-matched-layers (PMLs), and containing a target elastic or poroelastic inclusion. We define a wave motion metric to quantify the amount of the delivered wave energy. We, then, treat the material properties of the layers as random variables, and perform a first-order uncertainty analysis of the formation to compute the probabilities of failure to achieve threshold values of the motion metric. We illustrate the uncertainty quantification procedure using synthetic data.

  18. Dynamics of a mechanical frequency up-converted device for wave energy harvesting

    NASA Astrophysics Data System (ADS)

    Lin, Zheng; Zhang, Yongliang

    2016-04-01

    This paper proposes a novel mechanical impact-driven frequency up-converted device for wave energy harvesting, which could bridge a gap between waves of frequency 0.03-1 Hz and electrical generators of operation frequency hundreds hertz. The device mainly consists of a cylindrical buoy, beams and teeth. A mathematical model for the dynamics of such a device is presented, which incorporates the fluid-structure interaction between the wave and the buoy, and the structural interactions between the beams and the teeth. The momentum balance method and the coefficient of restitution are employed, which give rise to piecewise nonlinear equations governing the motions of the buoy and the beams. Experimental tests carried out in a wave flume validate the model and prove the effectiveness of frequency up-converted method in wave energy harvesting. The characteristics of frequency up-converted transformation from buoy motion to beams oscillation for wave energy harvesting are probed, and the effects of beam Young's modulus, beam number, wave period and wave height on strain power of the beams are explored.

  19. Fundamental Studies On Development Of MHD (Magnetohydrodynamic) Generator Implement On Wave Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Majid, M. F. M. A.; Apandi, Muhamad Al-Hakim Md; Sabri, M.; Shahril, K.

    2016-02-01

    As increasing of agricultural and industrial activities each year has led to an increasing in demand for energy. Possibility in the future, the country was not able to offer a lot of energy and power demand. This means that we need to focus on renewable energy to supply the demand for energy. Energy harvesting is among a method that can contribute on the renewable energy. MHD power generator is a new way to harvest the energy especially Ocean wave energy. An experimental investigation was conducted to explore performance of MHD generator. The effect of intensity of NaCl Solution (Sea Water), flow rate of NaCl solution, magnetic strength and magnet position to the current produce was analyzed. The result shows that each factor is give a significant effect to the current produce, because of that each factor need to consider on develop of MHD generator to harvest the wave energy as an alternative way to support the demand for energy.

  20. Transmission of wave energy in curved ducts. [acoustic propagation within rigid walls

    NASA Technical Reports Server (NTRS)

    Rostafinski, W.

    1974-01-01

    Investigation of the ability of circular bends to transmit acoustic energy flux. A formulation of wave-energy flow is developed for motion in curved ducts. A parametric study over a range of frequencies shows the ability of circular bends to transmit energy in the case of perfectly rigid walls.

  1. Driving ionospheric outflows and magnetospheric O+ energy density with Alfvén waves

    NASA Astrophysics Data System (ADS)

    Chaston, C. C.; Bonnell, J. W.; Reeves, G. D.; Skoug, R. M.

    2016-05-01

    We show how dispersive Alfvén waves observed in the inner magnetosphere during geomagnetic storms can extract O+ ions from the topside ionosphere and accelerate these ions to energies exceeding 50 keV in the equatorial plane. This occurs through wave trapping, a variant of "shock" surfing, and stochastic ion acceleration. These processes in combination with the mirror force drive field-aligned beams of outflowing ionospheric ions into the equatorial plane that evolve to provide energetic O+ distributions trapped near the equator. These waves also accelerate preexisting/injected ion populations on the same field lines. We show that the action of dispersive Alfvén waves over several minutes may drive order of magnitude increases in O+ ion pressure to make substantial contributions to magnetospheric ion energy density. These wave accelerated ions will enhance the ring current and play a role in the storm time evolution of the magnetosphere.

  2. An optimal control method for maximizing the efficiency of direct drive ocean wave energy extraction system.

    PubMed

    Chen, Zhongxian; Yu, Haitao; Wen, Cheng

    2014-01-01

    The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability. PMID:25152913

  3. An Optimal Control Method for Maximizing the Efficiency of Direct Drive Ocean Wave Energy Extraction System

    PubMed Central

    Chen, Zhongxian; Yu, Haitao; Wen, Cheng

    2014-01-01

    The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability. PMID:25152913

  4. Non-linear control of the ''clam'' wave energy device. Final report

    SciTech Connect

    Not Available

    1983-09-01

    A promising wave energy device being currently investigated is the ''clam'' device. The clam extracts energy by pumping air through a specially designed (Wells) turbine. Although operation of the Wells turbine does not require a rectified air flow, some additional control will be necessary to optimize the phase of the clam motion for good efficiencies. An examination of the equation of motion in the time domain suggests the possibility of non-linear phase control by mechanical, power take-off, or pneumatic latching. Latching can be shown to increase the efficiency of the device in the longer wavelengths of the wave spectrum, i.e. those of high incident wave power.

  5. Ulysses observations of magnetic waves due to newborn interstellar pickup ions. II. Application of turbulence concepts to limiting wave energy and observability

    SciTech Connect

    Cannon, Bradford E.; Smith, Charles W.; Isenberg, Philip A.; Vasquez, Bernard J.; Joyce, Colin J.; Murphy, Neil; Nuno, Raquel G. E-mail: Charles.Smith@unh.edu E-mail: Bernie.Vasquez@unh.edu E-mail: Neil.Murphy@jpl.nasa.gov

    2014-06-01

    The low-frequency magnetic waves that arise from the isotropization of newborn interstellar pickup ions (PUIs) are reasonably well described by linear and quasi-linear kinetic theory in so far as those theories predict the wave frequency and polarization in the spacecraft frame. Those theories fail to describe the scarce observability of the waves. Quasilinear theory predicts that the wave power should accumulate over long periods of time as the relatively weak kinetic instability slowly adds power to the observed spectrum. At the same time it has been argued that the same wave energy must serve as a secondary source of thermal ion heating in the outer heliosphere once the initial turbulence is depleted. To the extent that turbulent transport of the wave energy acts against the spectrally confined accumulation of wave energy, turbulence should be a limiting factor in observability. We argue that turbulence does limit the observability of the waves and we use turbulence theory to predict the observed wave energy. We compare this prediction against a database of 502 wave observations attributed to newborn interstellar PUIs observed by the Ulysses spacecraft.

  6. Mapping and Assessment of the United States Ocean Wave Energy Resource

    SciTech Connect

    Jacobson, Paul T; Hagerman, George; Scott, George

    2011-12-01

    This project estimates the naturally available and technically recoverable U.S. wave energy resources, using a 51-month Wavewatch III hindcast database developed especially for this study by National Oceanographic and Atmospheric Administration's (NOAA's) National Centers for Environmental Prediction. For total resource estimation, wave power density in terms of kilowatts per meter is aggregated across a unit diameter circle. This approach is fully consistent with accepted global practice and includes the resource made available by the lateral transfer of wave energy along wave crests, which enables wave diffraction to substantially reestablish wave power densities within a few kilometers of a linear array, even for fixed terminator devices. The total available wave energy resource along the U.S. continental shelf edge, based on accumulating unit circle wave power densities, is estimated to be 2,640 TWh/yr, broken down as follows: 590 TWh/yr for the West Coast, 240 TWh/yr for the East Coast, 80 TWh/yr for the Gulf of Mexico, 1570 TWh/yr for Alaska, 130 TWh/yr for Hawaii, and 30 TWh/yr for Puerto Rico. The total recoverable wave energy resource, as constrained by an array capacity packing density of 15 megawatts per kilometer of coastline, with a 100-fold operating range between threshold and maximum operating conditions in terms of input wave power density available to such arrays, yields a total recoverable resource along the U.S. continental shelf edge of 1,170 TWh/yr, broken down as follows: 250 TWh/yr for the West Coast, 160 TWh/yr for the East Coast, 60 TWh/yr for the Gulf of Mexico, 620 TWh/yr for Alaska, 80 TWh/yr for Hawaii, and 20 TWh/yr for Puerto Rico.

  7. Finite element modeling of acoustic wave propagation and energy deposition in bone during extracorporeal shock wave treatment

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofeng; Matula, Thomas J.; Ma, Yong; Liu, Zheng; Tu, Juan; Guo, Xiasheng; Zhang, Dong

    2013-06-01

    It is well known that extracorporeal shock wave treatment is capable of providing a non-surgical and relatively pain free alternative treatment modality for patients suffering from musculoskeletal disorders but do not respond well to conservative treatments. The major objective of current work is to investigate how the shock wave (SW) field would change if a bony structure exists in the path of the acoustic wave. Here, a model of finite element method (FEM) was developed based on linear elasticity and acoustic propagation equations to examine SW propagation and deflection near a mimic musculoskeletal bone. High-speed photography experiments were performed to record cavitation bubbles generated in SW field with the presence of mimic bone. By comparing experimental and simulated results, the effectiveness of FEM model could be verified and strain energy distributions in the bone were also predicted according to numerical simulations. The results show that (1) the SW field will be deflected with the presence of bony structure and varying deflection angles can be observed as the bone shifted up in the z-direction relative to SW geometric focus (F2 focus); (2) SW deflection angels predicted by the FEM model agree well with experimental results obtained from high-speed photographs; and (3) temporal evolutions of strain energy distribution in the bone can also be evaluated based on FEM model, with varied vertical distance between F2 focus and intended target point on the bone surface. The present studies indicate that, by combining MRI/CT scans and FEM modeling work, it is possible to better understand SW propagation characteristics and energy deposition in musculoskeletal structure during extracorporeal shock wave treatment, which is important for standardizing the treatment dosage, optimizing treatment protocols, and even providing patient-specific treatment guidance in clinic.

  8. Shock Formation and Energy Dissipation of Slow Magnetosonic Waves in Coronal Plumes

    NASA Technical Reports Server (NTRS)

    Cuntz, M.; Suess, S. T.

    2003-01-01

    We study the shock formation and energy dissipation of slow magnetosonic waves in coronal plumes. The wave parameters and the spreading function of the plumes as well as the base magnetic field strength are given by empirical constraints mostly from SOHO/UVCS. Our models show that shock formation occurs at low coronal heights, i.e., within 1.3 bun, depending on the model parameters. In addition, following analytical estimates, we show that scale height of energy dissipation by the shocks ranges between 0.15 and 0.45 Rsun. This implies that shock heating by slow magnetosonic waves is relevant at most heights, even though this type of waves is apparently not a solely operating energy supply mechanism.

  9. Potential to kinetic energy conversion in wave number domain for the Southern Hemisphere

    NASA Technical Reports Server (NTRS)

    Huang, H.-J.; Vincent, D. G.

    1984-01-01

    Preliminary results of a wave number study conducted for the South Pacific Convergence Zone (SPCZ) using FGGE data for the period January 10-27, 1979 are reported. In particular, three variables (geomagnetic height, z, vertical p-velocity, omega, and temperature, T) and one energy conversion quantity, omega-alpha (where alpha is the specific volume), are shown. It is demonstrated that wave number 4 plays an important role in the conversion from available potential energy to kinetic energy in the Southern Hemisphere tropics, particularly in the vicinity of the SPCZ. It is therefore suggested that the development and movement of wave number 4 waves be carefully monitored in making forecasts for the South Pacific region.

  10. Interplay of Waves and Eddies and Energy Exchange in Rotating Stratified Geophysical Flows

    NASA Astrophysics Data System (ADS)

    Pouquet, A.; Marino, R.; Rosenberg, D. L.; Herbert, C.

    2015-12-01

    We investigate the distribution of energy between wave and vortical modes as a function of scale in high resolution direct numerical simulations of rotating stratified Boussinesq flows with a unit aspect ratio, varying the dimensionless parameters in regimes in which wave turbulence prevails. The shift in scale from a vortex-dominated to a wave-dominated dynamics, characterized each by their Fourier spectra, is quantified by the wavenumber KR at which they cross. We examine the dependency of KR with parameters characteristics of the intrinsic dynamics of the flow such as Reynolds, Froude and Rossby numbers, and their combinations. Features of the energy exchange between potential and kinetic energy related to the interplay of wave modes and vortical modes are also explored and results recast in the context of geophysical flows.