Science.gov

Sample records for exploit wave energy

  1. Energy for lunar resource exploitation

    NASA Astrophysics Data System (ADS)

    Glaser, Peter E.

    1992-02-01

    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. 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.

  3. Waves of energy

    NASA Astrophysics Data System (ADS)

    Smith, F. G. W.; Charlier, R. H.

    1981-06-01

    Possible means for harnessing the energy contained in ocean waves are considered. Problems associated with the low-grade nature of wave energy and the rate at which wave crests approach are pointed out, and simple devices already in use for the supply of energy to bell buoys, whistle buoys and lighted buoys are noted. Attention is then given to wave energy conversion systems based on the focusing of waves onto a narrow ramp leading to a reservoir from which water is released to power a turbine generator; a slightly submerged circular shell which directs waves into its center cavity where waves act to turn a turbine (the Dam-Atoll); a long vertical pipe with an internal valve allowing water to move in an upward direction (the Isaacs wave-energy pump); a turbine located at the bottom of an open-topped pipe (the Masuda buoy); a completely submerged closed air chamber from which runs a large pipe open to the sea; a wave piston which acts by the compression of air to drive a turbine; a massive structure with upper and lower reservoirs (the Russel rectifier); and devices which consist of floating or submerged objects which transfer wave energy to pumps (the Salter duck and Cockerell raft.) It is concluded that although wave-powered generators are not likely to become competitive in the near future or provide more than a small portion of world demand, they may be found useful under special conditions.

  4. 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)

  5. 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

  6. 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.

  7. Exploiting large-scale correlations to detect continuous gravitational waves.

    PubMed

    Pletsch, Holger J; Allen, Bruce

    2009-10-30

    Fully coherent searches (over realistic ranges of parameter space and year-long observation times) for unknown sources of continuous gravitational waves are computationally prohibitive. Less expensive hierarchical searches divide the data into shorter segments which are analyzed coherently, then detection statistics from different segments are combined incoherently. The novel method presented here solves the long-standing problem of how best to do the incoherent combination. The optimal solution exploits large-scale parameter-space correlations in the coherent detection statistic. Application to simulated data shows dramatic sensitivity improvements compared with previously available (ad hoc) methods, increasing the spatial volume probed by more than 2 orders of magnitude at lower computational cost.

  8. Heavy Bearings Exploitation Energy and Reduction Methods

    NASA Astrophysics Data System (ADS)

    Szekely, V. G.; Cioară, R.

    2016-11-01

    The global trend of resource conservation so as “not to compromise the ability of future generation's development” is the fundamental basis of the concept of sustainable development. Concordant with this, the energy efficiency of products is increasingly discussed and frequently taken into account in the design stage. In more cases a product is more appreciated and more attractive as the energy consumption and its associated materials are lower. In the production stage, said consumption advantages primarily the manufacturer, particularly through low consumption thereof. In the operational phase, low energy and materials consumption represents an user advantage and it's a major argument in the decision to purchase and use a particular product. Heavy bearings are frequent products used in wind turbines that are producing non-conventional “clean” energy, as windmills. An enhanced energy efficiency bearing contributes to the enhancement of the overall efficiency of the wind turbines. Based on a suitable mathematical model, this paper identifies and recommends courses of action to reduce the operating energy of heavy bearing through the “cage” - which is the subject of a much larger research - with the highest priority. The identified actions may constitute from a set of requirements for the design stage of the heavy bearing predominantly oriented towards innovation-invention.

  9. Water wave energy transducer

    SciTech Connect

    Lamberti, J.

    1980-01-22

    A water wave energy transducer for converting the motion of a water wave into a controlled mechanical movement such as rotational motion suitable for actuating an electrical generator is disclosed. The transducer comprises a float member floatingly moored in a water body having waves and/or tidal movement, such as a seashore. A power gear is rotatably mounted in a swing block on the float with a power shaft extending from the power gear to laterally spaced drive bevel gears mounted for rotation with the power gear. These drive bevel gears are coupled to a transmission on the float comprising one-way drive clutches transmitting rotational energy to the drive shaft of a generator or the like to provide rotational energy on both up and down movement of the float. A rack is pivotally anchored in the water body, extends up through the float and is slideable with respect to the power gear of the swing block, so that movement of the float with respect to the rack will provide rotation of the power gear.

  10. 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.

  11. Exploiting sparsity in free energy basin-hopping

    NASA Astrophysics Data System (ADS)

    Sutherland-Cash, Kyle H.; Mantell, Rosemary G.; Wales, David J.

    2017-10-01

    We present acceleration of the vibrational frequency calculations required in free energy basin-hopping (FEBH) global optimisation using sparse Cholesky factorisation. We describe an interface with the SuiteSparse software package that facilitates these calculations, and present results detailing the accuracy and speedups obtained for atomic clusters and biomolecules. For the larger systems, exploiting sparsity reduces the computational cost by factors of ten to thirty, with no significant loss in accuracy. This approach will therefore provide access to the vibrational density of states, and hence to local harmonic free energies, for structure prediction and thermodynamic properties of more complex systems.

  12. Wave energy and intertidal productivity.

    PubMed

    Leigh, E G; Paine, R T; Quinn, J F; Suchanek, T H

    1987-03-01

    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 x 10(8) J, per m(2) 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.

  13. Wave energy and intertidal productivity

    SciTech Connect

    Leigh, E.G. Jr.; Paine, R.T.; Quinn, J.F.; Suchanek, T.H.

    1987-03-01

    In the northern 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 x 10/sup 8/ J, per m/sup 2/ 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 organism, and protect intertidal residents by knocking away their enemies or preventing them from feeding.

  14. 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

  15. GOCE and Future Gravity Missions for Geothermal Energy Exploitation

    NASA Astrophysics Data System (ADS)

    Pastorutti, Alberto; Braitenberg, Carla; Pivetta, Tommaso; Mariani, Patrizia

    2016-08-01

    Geothermal energy is a valuable renewable energy source the exploitation of which contributes to the worldwide reduction of consumption of fossil fuels oil and gas. The exploitation of geothermal energy is facilitated where the thermal gradient is higher than average leading to increased surface heat flow. Apart from the hydrologic circulation properties which depend on rock fractures and are important due to the heat transportation from the hotter layers to the surface, essential properties that increase the thermal gradient are crustal thinning and radiogenic heat producing rocks. Crustal thickness and rock composition form the link to the exploration with the satellite derived gravity field, because both induce subsurface mass changes that generate observable gravity anomalies. The recognition of gravity as a useful investigation tool for geothermal energy lead to a cooperation with ESA and the International Renewable Energy Agency (IRENA) that included the GOCE derived gravity field in the online geothermal energy investigation tool of the IRENA database. The relation between the gravity field products as the free air gravity anomaly, the Bouguer and isostatic anomalies and the heat flow values is though not straightforward and has not a unique relationship. It is complicated by the fact that it depends on the geodynamical context, on the geologic context and the age of the crustal rocks. Globally the geological context and geodynamical history of an area is known close to everywhere, so that a specific known relationship between gravity and geothermal potential can be applied. In this study we show the results of a systematic analysis of the problem, including some simulations of the key factors. The study relies on the data of GOCE and the resolution and accuracy of this satellite. We also give conclusions on the improved exploration power of a gravity mission with higher spatial resolution and reduced data error, as could be achieved in principle by flying

  16. 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.

  17. The Exploitation of Low-Energy Electrons in Cancer Treatment.

    PubMed

    Rezaee, Mohammad; Hill, Richard P; Jaffray, David A

    2017-08-01

    Given the distinct characteristics of low-energy electrons (LEEs), particularly at energies less than 30 eV, they can be applied to a wide range of therapeutic modalities to improve cancer treatment. LEEs have been shown to efficiently produce complex molecular damage resulting in substantial cellular toxicities. Since LEEs are produced in copious amounts from high-energy radiation beam, including photons, protons and ions; the control of LEE distribution can potentially enhance the therapeutic radio of such beams. LEEs can play a substantial role in the synergistic effect between radiation and chemotherapy, particularly halogenated and platinum-based anticancer drugs. Radiosensitizing entities containing atoms of high atomic number such as gold nanoparticles can be a source of LEE production if high-energy radiation interacts with them. This can provide a high local density of LEEs in a cell and produce cellular toxicity. Auger-electron-emitting radionuclides also create a high number of LEEs in each decay, which can induce lethal damage in a cell. Exploitation of LEEs in cancer treatment, however, faces a few challenges, such as dosimetry of LEEs and selective delivery of radiosensitizing and chemotherapeutic molecules close to cellular targets. This review first discusses the rationale for utilizing LEEs in cancer treatment by explaining their mechanism of action, describes theoretical and experimental studies at the molecular and cellular levels, then discusses strategies for achieving modification of the distribution and effectiveness of LEEs in cancerous tissue and their associated clinical benefit.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Direct Drive Wave Energy Buoy

    SciTech Connect

    Rhinefrank, Kenneth; Lamb, Bradford; Prudell, Joseph; Hammagren, Erik; Lenee-Bluhm, Pukha

    2016-08-22

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

  3. 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.

  4. 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.

  5. 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.

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

    PubMed

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

    2012-01-28

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

  7. Wave energy extraction by coupled resonant absorbers.

    PubMed

    Evans, D V; Porter, R

    2012-01-28

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

  8. Energy and Momentum Transport in String Waves

    ERIC Educational Resources Information Center

    Juenker, D. W.

    1976-01-01

    Formulas are derived for the energy, momentum, and angular momentum transmitted by waves of arbitrary shape in an inextensible string by pure transverse waves in a string using Tait's procedure. (Author/CP)

  9. Energy and Momentum Transport in String Waves

    ERIC Educational Resources Information Center

    Juenker, D. W.

    1976-01-01

    Formulas are derived for the energy, momentum, and angular momentum transmitted by waves of arbitrary shape in an inextensible string by pure transverse waves in a string using Tait's procedure. (Author/CP)

  10. Energy efficient computing exploiting the properties of light

    NASA Astrophysics Data System (ADS)

    Shamir, Joseph

    2013-09-01

    Significant reduction of energy dissipation in computing can be achieved by addressing the theoretical lower limit of energy consumption and replacing arrays of traditional Boolean logic gates by other methods of implementing logic operations. In particular, a slight modification of the concept of computing allows the incorporation of fundamentally lossless optical processes as part of the computing operation. While the introduced new concepts can be implemented electronically or by other means, using optics eliminates also energy dissipation involved in the translation of electric charges. A possible realization of the indicated concepts is based on directed logic networks composed of reversible optical logic gate arrays.

  11. 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.

  12. Controller for a wave energy converter

    DOEpatents

    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.

  13. 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%.

  14. Ocean floor mounting of wave energy converters

    DOEpatents

    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.

  15. Exploiting Lipid Permutation Symmetry to Compute Membrane Remodeling Free Energies

    NASA Astrophysics Data System (ADS)

    Bubnis, Greg; Risselada, Herre Jelger; Grubmüller, Helmut

    2016-10-01

    A complete physical description of membrane remodeling processes, such as fusion or fission, requires knowledge of the underlying free energy landscapes, particularly in barrier regions involving collective shape changes, topological transitions, and high curvature, where Canham-Helfrich (CH) continuum descriptions may fail. To calculate these free energies using atomistic simulations, one must address not only the sampling problem due to high free energy barriers, but also an orthogonal sampling problem of combinatorial complexity stemming from the permutation symmetry of identical lipids. Here, we solve the combinatorial problem with a permutation reduction scheme to map a structural ensemble into a compact, nondegenerate subregion of configuration space, thereby permitting straightforward free energy calculations via umbrella sampling. We applied this approach, using a coarse-grained lipid model, to test the CH description of bending and found sharp increases in the bending modulus for curvature radii below 10 nm. These deviations suggest that an anharmonic bending term may be required for CH models to give quantitative energetics of highly curved states.

  16. Exploiting variability for energy optimization of parallel programs

    SciTech Connect

    Lavrijsen, Wim; Iancu, Costin; de Jong, Wibe; Chen, Xin; Schwan, Karsten

    2016-04-18

    Here in this paper we present optimizations that use DVFS mechanisms to reduce the total energy usage in scientific applications. Our main insight is that noise is intrinsic to large scale parallel executions and it appears whenever shared resources are contended. The presence of noise allows us to identify and manipulate any program regions amenable to DVFS. When compared to previous energy optimizations that make per core decisions using predictions of the running time, our scheme uses a qualitative approach to recognize the signature of executions amenable to DVFS. By recognizing the "shape of variability" we can optimize codes with highly dynamic behavior, which pose challenges to all existing DVFS techniques. We validate our approach using offline and online analyses for one-sided and two-sided communication paradigms. We have applied our methods to NWChem, and we show best case improvements in energy use of 12% at no loss in performance when using online optimizations running on 720 Haswell cores with one-sided communication. With NWChem on MPI two-sided and offline analysis, capturing the initialization, we find energy savings of up to 20%, with less than 1% performance cost.

  17. 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…

  18. 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…

  19. Exploitation of binding energy for catalysis and design

    PubMed Central

    Thyme, Summer B.; Jarjour, Jordan; Takeuchi, Ryo; Havranek, James J.; Ashworth, Justin; Scharenberg, Andrew M.; Stoddard, Barry L.; Baker, David

    2009-01-01

    Enzymes utilize substrate binding energy both to promote ground state association and to selectively lower the energy of the reaction transition state.i The monomeric homing endonuclease I-AniI cleaves with high sequence specificity in the center of a 20 base-pair DNA target site, with the N-terminal domain of the enzyme making extensive binding interactions with the left (−) side of the target site and the similarly structured C-terminal domain interacting with the right (+) side.ii Despite the approximate two-fold symmetry of the enzyme-DNA complex, we find that there is almost complete segregation of interactions responsible for substrate binding to the (−) side of the interface and interactions responsible for transition state stabilization to the (+) side. While single base-pair substitutions throughout the entire DNA target site reduce catalytic efficiency, mutations in the (−) DNA half-site almost exclusively increase KD and KM*, and those in the (+) half-site primarily decrease kcat*. The reduction of activity produced by mutations on the (−) side, but not mutations on the (+) side, can be suppressed by tethering the substrate to the endonuclease displayed on the surface of yeast. This dramatic asymmetry in the utilization of enzyme-substrate binding energy for catalysis has direct relevance to the redesign of endonucleases to cleave genomic target sites for gene therapy and other applications. Computationally redesigned enzymes that achieve new specificities on the (−) side do so by modulating KM*, while redesigns with altered specificities on the (+) side modulate kcat*. Our results illustrate how classical enzymology and modern protein design can each inform the other. PMID:19865174

  20. Exploitation of the thermotunnel effect for energy scavenging

    NASA Astrophysics Data System (ADS)

    Despesse, Ghislain; Jager, Thomas

    2004-11-01

    Over the past few years, MEMS and smart material technologies improvements have allowed autonomous sensor devices to become more and more widespread. As batteries are not always appropriate to power these systems, energy scavenging solutions from ambient power are currently being developed. In particular, many researches have been carried out to improve thermal to electrical energy conversion in ambient temperature gradients. Until now, thermoelectric materials are still the most employed for this application. However, the recent developments in nanoscale device structures open different perspectives. In these nanoscale systems, the heat transport is achieved between two electrodes thanks to electron tunneling. The thermotunnel effect is currently widely studied in the cooling configuration where it has already been shown that it is more efficient than the Peltier effect. We have decided to evaluate this effect in the reciprocal way of work with the objective of being able to power a small sensor node. Considering a device with a simplicial geometrical structure, a modeling has been developed in order to evaluate the feasibility of conversion of a thermal flow into an electrical power based on thermotunneling effect. Comparisons with thermoelectric performances at ambient temperature have been performed.

  1. 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.

  2. Inventing a Better Way to Capture the Energy of Waves

    SciTech Connect

    2016-06-01

    NREL's ocean energy research team's efforts to develop more robust and cost-effective wave energy converters have yielded a record of invention titled, 'Wave Energy Conversion Devices with Actuated Geometry.' This innovative wave device features a wave converter with controlled geometry that increases energy capture and prevents large waves from overloading the generator. The invention's control system actuates flaps that open and close depending on wave conditions. Better control of the wave forces acting on wave energy conversion devices provides a solution to one of wave energy's biggest challenges -- and could cut the cost of wave energy in half.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  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. 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.

  9. 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.

  10. Sunspot waves and flare energy release

    NASA Astrophysics Data System (ADS)

    Sych, R.; Karlický, M.; Altyntsev, A.; Dudík, J.; Kashapova, L.

    2015-05-01

    Context. We study the possibility of flare process triggering by waves propagating from the sunspot along a magnetic loop (channel) to a nearby flare site. Aims: We present a relationship between the dynamics of ~3-min slow magnetoacoustic waves in the sunspot and flare emergence process. Waves propagating in the magnetic channel whose one foot is anchored in the umbra represent the disturbing agent responsible for triggering the flare energy release. Methods: We applied time-distance plots and pixel wavelet filtration methods to obtain spatio-temporal distribution of wave power variations in radio and SDO/AIA data. To find the magnetic channel, we used potential magnetic field extrapolation of SDO/HMI magnetograms. The propagation velocity of wave fronts was measured from wave locations at specific times. Results: In the correlation curves of the 17 GHz (NoRH) radio emission, we found a monotonous energy amplification of the 3-min waves in the sunspot umbra before the 2012 June 7 flare. This amplification was associated with an increase in the length of the oscillatory wakes in coronal loops (SDO/AIA, 171 Å) prior to the flare onset. A peculiarity of the flare is the constant level of the flare emission in soft X-rays (RHESSI, 3-25 keV) for ~10 min after the short impulsive phase, which indicates continuing energy release. Throughout this time, we found transverse oscillations of the flare loop with a 30 s period in the radio-frequency range (NoRH, 17 GHz). This period appears to be related to the 3-min waves from the sunspot. The magnetic field extrapolation based on SDO/HMI magnetograms shows the existence of the magnetic channel (waveguide) connecting the sunspot with the energy release region. Conclusions: We analysed the sunspot 3-min wave dynamics and found a correlation between the oscillation power amplification and flare triggering in the region connected to the sunspot through the magnetic channel. We propose that this amplified wave flux triggered the

  11. Exploiting P-S converted waves. Part 1: Modeling the effects of anisotropy and heterogeneities

    SciTech Connect

    Michelena, R.J.; Ata, E.; Sierra, J.

    1994-12-31

    The authors performed extensive modeling studies to evaluate P-S converted waves effectiveness and limitations in the estimation of both cracks orientation and density. The target area is a fractured, carbonate reservoir located in south-west Venezuela. The reservoir depth is on the order of 3000 m, which implies that high quality P-S data are needed to obtain detectable information about the anisotropy at this depth. They focused their analysis on P-S converted waves because only explosives charges were available as energy sources. The modeling was performed prior to and after the data acquisition to help both design of the experiment and interpretation of the data. Synthetic seismograms were generated using 2D, elastic finite difference, along with a 3D-3C, paraxial ray tracing codes. They conducted also a noise-spread test to complement this study and determine the acquisition parameters. A 3D velocity model of the subsurface was built based on previous P-wave seismic sections, well logs (dual-sonic, density, check-shots and FMS), geological maps, and production information. This model was perturbed in a layer stripping fashion until an acceptable match was obtained around the depth of interest between synthetic and multicomponent field data. The anisotropy produced measurable differences in traveltimes and amplitudes between in-line and cross-line components. These differences (which are comparable to those observed on the field data) suggest that it is feasible to map fractures at depths around the reservoir area by using P-S converted waves.

  12. 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.

  13. Energy density and energy flow of magnetoplasmonic waves on graphene

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2017-03-01

    By means the linearized magnetohydrodynamic theory, expressions for energy density and energy flow are derived for the p-polarized surface magnetoplasmon polaritons on graphene in the Voigt configuration, where a static magnetic field is normal to the graphene surface. Numerical results show that the external magnetic field has significant impact on the energy density and energy transport velocity of magnetoplasmon waves in the long-wavelength region, while total power flow vary only weakly with magnetostatic field. The velocity of energy propagation is proved to be identical with group velocity of the surface waves.

  14. 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.

  15. Ocean Wave Energy Harvesting Devices

    DTIC Science & Technology

    2007-04-01

    coupled to a suitable buoy platform. 2. The approach of designing a device which meets the requirements for mounting on dogfish and generating...used on the tail of a marine life such as dogfish to harvest energy as it swims. The output power can be used to trickle charge battery packs to power...to be mounted to a dogfish to harvest energy from its motion. Due to the small fish size (approximate 40-50 inches, 25 pounds), the device was

  16. 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

  17. Fundamental formulae for wave-energy conversion.

    PubMed

    Falnes, Johannes; Kurniawan, Adi

    2015-03-01

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

  18. Exploiting the principle parametric resonance of an electric oscillator for vibratory energy harvesting

    NASA Astrophysics Data System (ADS)

    Caldwell, N. B.; Daqaq, M. F.

    2017-02-01

    Vibratory energy harvesters typically exploit ordinary direct resonances to mechanically amplify environmental inputs before channeling a portion of their energy into an electric load using an electromechanical transduction mechanism. Nonetheless, parametric resonance which has also been recently exploited, but to a lesser extent, holds a key advantage over direct excitations in that, when the level of input excitation exceeds a certain threshold, the amplitude of growth associated with parametric pumping is not limited by the total linear damping present in the system. While all of the previous research studies using parametric resonances for energy harvesting focused on utilizing it as a means of mechanical amplification, this letter demonstrates that vibratory excitations can also be used effectively to induce parametric resonances in the harvesting circuit itself, thereby providing a direct and simple means of electric amplification. A vibratory energy harvester exploiting this phenomenon is proposed in this letter and is shown to produce a maximum of 18 mW root-mean-square power per 1 g of input acceleration.

  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. Revisiting the energy in gravitational waves

    NASA Astrophysics Data System (ADS)

    Qadir, Asghar

    Five years ago, at the Third Joint Italian-Pakistani Workshop on Relativistic Astrophysics, I put forward an argument why gravitational waves would be much more difficult to detect than was supposed. In view of the observation of gravitational waves in 2015, and an earlier claim that they were missing, it is worth looking again at the arguments. Here, I review the basic physical argument and then re-consider the earlier prediction. Following Weber and Wheeler, who had demonstrated the reality of gravitational waves by obtaining the momentum of test particles along their path, there had been more work done in this direction. It is also worthwhile to compare the results from that work with the proposal for the energy in the waves and that will also be mentioned.

  1. Systems and methods for wave energy conversion

    DOEpatents

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

    2017-02-28

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

  2. Discrete control of resonant wave energy devices.

    PubMed

    Clément, A H; Babarit, A

    2012-01-28

    Aiming at amplifying the energy productive motion of wave energy converters (WECs) in response to irregular sea waves, the strategies of discrete control presented here feature some major advantages over continuous control, which is known to require, for optimal operation, a bidirectional power take-off able to re-inject energy into the WEC system during parts of the oscillation cycles. Three different discrete control strategies are described: latching control, declutching control and the combination of both, which we term latched-operating-declutched control. It is shown that any of these methods can be applied with great benefit, not only to mono-resonant WEC oscillators, but also to bi-resonant and multi-resonant systems. For some of these applications, it is shown how these three discrete control strategies can be optimally defined, either by analytical solution for regular waves, or numerically, by applying the optimal command theory in irregular waves. Applied to a model of a seven degree-of-freedom system (the SEAREV WEC) to estimate its annual production on several production sites, the most efficient of these discrete control strategies was shown to double the energy production, regardless of the resource level of the site, which may be considered as a real breakthrough, rather than a marginal improvement.

  3. 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.

  4. Technically exploitable geothermal energy by using Borehole Heat Exchangers: A revisit of the Cologne case

    NASA Astrophysics Data System (ADS)

    Shao, Haibing; Hein, Philipp; Bucher, Anke; Kolditz, Olaf

    2017-04-01

    In previous studies, the amount of shallow geothermal energy was estimated by assuming a uniform temperature drop of at least 2 °C in the aquifer. In this work, a more comprehensive numerical model has been employed to evaluate the technically exploitable geothermal energy by using Borehole Heat Exchanger coupled Ground Source Heat Pump systems. A case study on the city of Cologne was revisited, adopting the same hydrogeological conditions and simulating the long-term evolution of the subsurface temperature field subject to the operation of borehole heat exchangers. It is found that the cities' heating demand could potentially be fully covered by BHE-coupled GSHP systems. The resulting equivalent uniform temperature drop is then around 1.6 °C . It was also found that utilising geothermal energy will lead to at least 50% reduction of CO2 equivalent emission in comparison to conventional district heating, depending on the source of electricity used for heat pump operation.

  5. 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.

  6. Wecpos - Wave Energy Coastal Protection Oscillating System: A Numerical Assessment

    NASA Astrophysics Data System (ADS)

    Dentale, Fabio; Pugliese Carratelli, Eugenio; Rzzo, Gianfranco; Arsie, Ivan; Davide Russo, Salvatore

    2010-05-01

    In recent years, the interest in developing new technologies to produce energy with low environmental impact by using renewable sources has grown exponentially all over the world. In this context, the experiences made to derive electricity from the sea (currents, waves, etc.) are of particular interest. At the moment, due to the many existing experiments completed or still in progress, it is quite impossible explain what has been obtained but it is worth mentioning the EMEC, which summarizes the major projects in the world. Another important environmental aspect, also related to the maritime field, is the coastal protection from the sea waves. Even in this field, since many years, the structural and non-structural solutions which can counteract this phenomenon are analyzed, in order to cause the least possible damage to the environment. The studies in development by the researchers of the University of Salerno are based on these two aspect previously presented. Considering the technologies currently available, a submerged system has been designed, WECPOS (Wave Energy Coastal Protection Oscillating System), to be located on relatively shallow depths, to can be used simultaneously for both electricity generation and for the coastal protection using the oscillating motion of the water particles. The single element constituting the system is realized by a fixed base and three movable panels that can fluctuate in a fixed angle. The waves interact with the panels generating an alternative motion which can be exploited to produce electricity. At the same time, the constraint movement imposed for the rotation of the panels is a barrier to the wave propagation phenomena, triggering the breaking in the downstream part of the device. So the wave energy will be dissipated obtaining a positive effect for the coastal protection. Currently, the efficiency and effectiveness of the system (WECPOS single module) has been studied by using numerical models. Using the FLOW-3D

  7. Exploiting the symmetries of P and S wave for B → K ∗ μ + μ -

    NASA Astrophysics Data System (ADS)

    Hofer, Lars; Matias, Joaquim

    2015-09-01

    After summarizing the current theoretical status of the four-body decay B → K ∗(→ Kπ) μ + μ -, we apply the formalism of spin-symmetries to the full angular distribution, including the S-wave part involving a broad scalar resonance K 0 ∗ . While we recover in the P-wave sector the known relation between the angular observables P i (') , we find in the S-wave sector two new relations connecting the coefficients of the S-wave angular distribution and reducing the number of independent S-wave observables from six to four. Included in the experimental data analysis, these relations can help to reduce the background from S-wave pollution. We further point out the discriminative power of the maximum of the angular observable P 2 as a charm-loop insensitive probe of right-handed currents. Moreover, we show that in absence of right-handed currents the angular observables P 4 ' and P 5 ' fulfill the relation P 4 ' = βP 5 ' at the position where P 2 reaches its maximum.

  8. 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.

  9. 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.

  10. The Central Control of Energy Expenditure: Exploiting Torpor for Medical Applications.

    PubMed

    Cerri, Matteo

    2017-02-10

    Autonomic thermoregulation is a recently acquired function, as it appears for the first time in mammals and provides the brain with the ability to control energy expenditure. The importance of such control can easily be highlighted by the ability of a heterogeneous group of mammals to actively reduce metabolic rate and enter a condition of regulated hypometabolism known as torpor. The central neural circuits of thermoregulatory cold defense have been recently unraveled and could in theory be exploited to reduce energy expenditure in species that do not normally use torpor, inducing a state called synthetic torpor. This approach may represent the first steps toward the development of a technology to induce a safe and reversible state of hypometabolism in humans, unlocking many applications ranging from new medical procedures to deep space travel.

  11. 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

  12. Exploiting evanescent-wave amplification for subwavelength low-contrast particle detection

    NASA Astrophysics Data System (ADS)

    Roy, S.; Pereira, S. F.; Urbach, H. P.; Wei, Xukang; El Gawhary, O.

    2017-07-01

    The classical problem of subwavelength particle detection on a flat surface is especially challenging when the refractive index of the particle is close to that of the substrate. We demonstrate a method to improve the detection ability several times for such a situation, by enhancing the "forbidden" evanescent waves in the substrate using the principle of super-resolution with evanescent waves amplification. The working mechanism of the system and experimental validation from a design with a thin single dielectric layer is presented. The resulting system is a simple but complete example of evanescent-wave generation, amplification, and the consequent modulation of the far field. This principle can have far reaching impact in the field of particle detection in several applications ranging from contamination control to interferometric scattering microscopy for biological samples.

  13. Enhancement of elastic wave energy harvesting using adaptive piezo-lens

    NASA Astrophysics Data System (ADS)

    Yi, K.; Collet, M.; Chesne, S.; Monteil, M.

    2017-09-01

    This paper exploits an adaptive piezo-lens to improve the harvested power (energy) from traveling waves. The piezo-lens comprises a host plate and piezoelectric patches bonded on the plate surfaces. The piezoelectric patches are shunted with negative capacitance (NC) circuits. The spatial variation of the refractive index inside the piezo-lens domain is designed to fulfill a hyperbolic secant function by tuning the NC values. This design allows the piezo-lens to continuously bend the incident waves toward a designed focal point, resulting in an energy concentration zone with a high level of energy density. This energy concentration effect may be exploited to improve the harvested power from waves. In addition, the piezo-lens is tunable - the waves can be focused at different locations by designing the NC values. This tunability may make the harvesting systems incorporating a piezo-lens be adaptable to environment changes. The above expected practical interests of the piezo-lens for wave energy harvesting are discussed and verified in the paper. Fully coupled numerical models are developed to predict the dynamical responses of the piezoelectric systems.

  14. 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.

  15. Exploitation of transverse spatial modes in spontaneous four wave mixing photon-pair sources

    NASA Astrophysics Data System (ADS)

    Cruz-Ramirez, Hector; Ramirez-Alarcon, Roberto; Cruz-Delgado, Daniel; Monroy-Ruz, Jorge; Ortiz-Ricardo, Erasto; Dominguez-Serna, Francisco; Garay-Palmett, Karina; U'Ren, Alfred B.

    2016-09-01

    We present a source for which multiple spontaneous four-wave mixing (SFWM) processes are supported in a few mode birefringent fiber, each process associated with a particular combination of transverse modes for the four participating waves. Within the weakly guiding regime, for which the propagation modes may be well approximated by linearly polarized (LP) modes, the departure from circular symmetry due to the fiber birefringence translates into orbital angular momentum (OAM) and parity conservation rules, i.e. reflecting elements from both azimuthal and rectangular symmetries. In our source: i) each process is group-velocity-matched so that it is, by design, nearly-factorable, and ii) the spectral separation between neighboring processes is greater than the marginal spectral width of each process. Consequently, there is a direct correspondence between the joint amplitude of each process and each of the Schmidt mode pairs of the overall two-photon state. The present paper covers work presented in Refs.1 and.2

  16. Numerical analysis of multiwavelength erbium-doped fiber ring laser exploiting four-wave mixing.

    PubMed

    Xu, Xiaochuan; Yao, Yong; Chen, Deying

    2008-08-04

    In this paper, a model is proposed to study the behavior of four-wave mixing assisted multiwavelength erbium doped fiber ring laser based on the theoretical model of the multiple FWM processes and Gile's theory of erbium-doped fiber. It is demonstrated that the mode competition can be effectively suppressed through FWM. The effect of phase matching, the nonlinear coefficient, the power in the cavity and the length of the nonlinear medium on output spectrum uniformity are also investigated.

  17. Ultrasound acoustic wave energy transfer and harvesting

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

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

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

    PubMed

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

    2017-05-05

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

  20. Exploiting Structured Environments for Efficient Energy Transfer: The Phonon Antenna Mechanism.

    PubMed

    Rey, Marco Del; Chin, Alex W; Huelga, Susana F; Plenio, Martin B

    2013-03-21

    A nontrivial interplay between quantum coherence and dissipative environment-driven dynamics is becoming increasingly recognized as the key for efficient energy transport in photosynthetic pigment-protein complexes, and converting these biologically inspired insights into a set of design principles that can be implemented in artificial light-harvesting systems has become an active research field. Here we identify a specific design principle, the phonon antenna, by which interpigment coherence is able to modify and optimize the way that excitations spectrally sample their local environmental fluctuations. We provide numerical simulations that suggest that the Fenna-Matthews-Olson complex of green sulfur bacteria has an excitonic structure that is close to such an optimal operating point, and place the phonon antenna concept into a broader context that leads us to conjecture that this general design principle might well be exploited in other biomolecular systems.

  1. Innovative wave energy device applied to coastal observatory systems

    NASA Astrophysics Data System (ADS)

    Marcelli, Marco; Bonamano, Simone; Piermattei, Viviana; Scanu, Sergio; Paladini de Mendoza, Francesco; Martellucci, Riccardo; Maximo, Peviani

    2017-04-01

    Marine environment is one of the most promising sources of renewable energy, whose exploitation could have an effect on several application fields. This work presents the design of an innovative device based on the Oscillating Water Column (OWC), that allows to convert wave energy into electricity, suitable for the typical Mediterranean wave climate. The flexibility of the device permits its installation either in deep or shallow waters, with reduced costs of deployment, maintenance and connection to the grid. Furthermore, the replicability of the design allows the device to be installed in array of several number of similar units. The technical concept is to convey the sea water within a vertical pipe, in which the water movements activate a rotor connected to a generator that transforms the energy of the water motion into electricity. The hydrodynamic design of the pipe is built to minimize the losses due to friction and turbulence and to exploit the maximum possible energy from wave motion. The wave energy is directly absorbed by the rotational movement of the turbine blades located in the water itself allowing a further reduction of the energy losses associated with the transformation of the linear water motion into electrical generation in the air phase (typical configuration of the OWC devices). In this work the device components are described considering two possible configurations that use a Wells turbine or a Bulb type turbine. The system can be realized at a low cost, because of the modularity of the device project, which allows large freedom of sizes and placements, being able to be installed both individually and in arrays. The modularity, associated with the fact that the main elements of the system are available on the market, makes the device particularly attractive from the economic point of view. Finally, it is realized with a high constructive flexibility: the proposed system can be transported floating and moored to existing coastal structures or

  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. 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…

  4. 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.

  5. Exploiting P-S converted waves. Part 2: Application to a fractured reservoir

    SciTech Connect

    Ata, E.; Michelena, R.J.; Gonzales, M.; Cerquone, H.; Carry, M.

    1994-12-31

    A P-S data set, with nearby well data for analysis constraint, was collected in southwest Venezuela to map the strike, density, and extent of fractures in the hydrocarbon bearing formation of a reservoir. Three 10 km multicomponent lines were centered over the reservoir along three different azimuths. The survey design was geared to maximize the data quality with respect to resolution, signal-to-noise ratio, sufficient spatial and temporal sampling, correct near and far offsets, maximum dip, and elimination of any variation in amplitude or traveltime that can be confused with lithological effects. Well information indicates that the hydrocarbon bearing formation is a fractured limestone with a depth of approximately 3,000 m, and gently dipping in a NE-SW direction. Based on previous seismic P-wave data, subtle lithological structures and small normal faults dominate the reflection horizons of the target zone. These structures appear to dominate the production history of the existing wells in the field, which implies the necessity of high resolution data for better definition of the seismic events. Results from the collected data suggest presence of azimuthal anisotropy that effects P-S converted-wave amplitude and traveltime. Observations appear to be consistent with the geological setup in the area of study. However, accurate quantification of anisotropic parameters must be done after appropriate processing of the data and careful confirmation of results with borehole measurements.

  6. 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.

  7. 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.

  8. The radiation of surface wave energy: Implications for volcanic tremor

    NASA Astrophysics Data System (ADS)

    Haney, M. M.; Denolle, M.; Lyons, J. J.; Nakahara, H.

    2015-12-01

    The seismic energy radiated by active volcanism is one common measurement of eruption size. For example, the magnitudes of individual earthquakes in volcano-tectonic (VT) swarms can be summed and expressed in terms of cumulative magnitude, energy, or moment release. However, discrepancies exist in current practice when treating the radiated energy of volcano seismicity dominated by surface waves. This has implications for volcanic tremor, since eruption tremor typically originates at shallow depth and is made up of surface waves. In the absence of a method to compute surface wave energy, estimates of eruption energy partitioning between acoustic and seismic waves typically assume seismic energy is composed of body waves. Furthermore, without the proper treatment of surface wave energy, it is unclear how much volcanic tremor contributes to the overall seismic energy budget during volcanic unrest. To address this issue, we derive, from first principles, the expression of surface wave radiated energy. In contrast with body waves, the surface wave energy equation is naturally expressed in the frequency domain instead of the time domain. We validate our result by reproducing an analytical solution for the radiated power of a vertical force source acting on a free surface. We further show that the surface wave energy equation leads to an explicit relationship between energy and the imaginary part of the surface wave Green's tensor at the source location, a fundamental property recognized within the field of seismic interferometry. With the new surface wave energy equation, we make clear connections to reduced displacement and propose an improved formula for the calculation of surface wave reduced displacement involving integration over the frequency band of tremor. As an alternative to reduced displacement, we show that reduced particle velocity squared is also a valid physical measure of tremor size, one based on seismic energy rate instead of seismic moment rate. These

  9. 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.

  10. 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

  11. Study of the potential of wave energy in Malaysia

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

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

  12. 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

  13. On the exploitation of mode localization in surface acoustic wave MEMS

    NASA Astrophysics Data System (ADS)

    Hanley, T. H.; Gallacher, B. J.; Grigg, H. T. D.

    2017-05-01

    Mode localization sensing has been recently introduced as an alternative resonant sensing protocol. It has been shown to exhibit several advantages over other resonant methods, in particular a potential for higher sensitivity and rejection of common mode noise. This paper expounds the principles of utilising surface acoustic waves (SAW) to create a mode localization sensor. A generalised geometry consisting of a pair of coupled resonant cavities is introduced and an analytical solution found for the displacement fields within the cavities. The solution is achieved by coupling the internal cavity solutions using a ray tracing method. The results of the analytical solution are compared to a numerical solution found using commercial finite element method (FEM) software; exact agreement is found between the two solutions. The insight gained from the analytical model enables the determination of critical design parameters. A brief analysis is presented showing analogous operation to previous examples of mode localization sensors. The sensitivity of the device is shown to depend nonlinearly on the number of periods in the array coupling the two cavities.

  14. 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

  15. Wave energy devices with compressible volumes.

    PubMed

    Kurniawan, Adi; Greaves, Deborah; Chaplin, John

    2014-12-08

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

  16. 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

  17. 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.

  18. Mechanochemistry for shock wave energy dissipation

    NASA Astrophysics Data System (ADS)

    Shaw, William L.; Ren, Yi; Moore, Jeffrey S.; Dlott, Dana D.

    2017-01-01

    Using a laser-driven flyer-plate apparatus to launch 75 μm thick Al flyers up to 2.8 km/s, we developed a technique for detecting the attenuation of shock waves by mechanically-driven chemical reactions. The attenuating sample was spread on an ultrathin Au mirror deposited onto a glass window having a known Hugoniot. As shock energy exited the sample and passed through the mirror, into the glass, photonic Doppler velocimetry monitored the velocity profile of the ultrathin mirror. Knowing the window Hugoniot, the velocity profile could be quantitatively converted into a shock energy flux or fluence. The flux gave the temporal profile of the shock front, and showed how the shock front was reshaped by passing through the dissipative medium. The fluence, the time-integrated flux, showed how much shock energy was transmitted through the sample. Samples consisted of microgram quantities of carefully engineered organic compounds selected for their potential to undergo negative-volume chemistry. Post mortem analytical methods were used to confirm that shock dissipation was associated with shock-induced chemical reactions.

  19. 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

  20. Energy balance of a plasma with a wave, taking the wave nonpotentiality into account

    NASA Astrophysics Data System (ADS)

    Gelberg, M. G.; Volosevich, A. V.

    It is shown that the potential electric field of low-frequency plasma waves in the ionosphere is phase-shifted by approximately -pi/2 with respect to current fluctuations, while the vortex field is nearly cophase with the current. Thus, the work of energy transfer between the plasma and the wave occurs primarily with the participation of the vortex field. The wave nonpotentiality is shown to have a substantial effect on the energy balance of the wave-plasma system.

  1. Chorus Wave Energy Budget Analysis in the Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Blancarte, J.; Agapitov, O. V.; Mozer, F.

    2016-12-01

    Whistler-mode chorus emissions are important electromagnetic waves in the Earth's magnetosphere, where they continuously scatter and accelerate electrons of the outer radiation belt, controlling radiation hazards to satellites and astronauts. Here, we present an analysis of Van Allen Probes electric and magnetic field VLF waveform data, evaluating the wave energy budget, and show that a significant fraction of the energy corresponds to very oblique waves. Such waves, with a generally much smaller (up to 10 times) magnetic power than parallel waves, typically have comparable or even larger total energy. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth's radiation belts and also provide nonlinear effects due to wave-particle interaction through the Landau resonance due to the significant electric field component parallel to the background magnetic field.

  2. 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.

  3. 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

  4. Energy exchange and wave action conservation for magnetohydrodynamic (MHD) waves in a general, slowly varying medium

    NASA Astrophysics Data System (ADS)

    Walker, A. D. M.

    2014-12-01

    Magnetohydrodynamic (MHD) waves in the solar wind and magnetosphere are propagated in a medium whose velocity is comparable to or greater than the wave velocity and which varies in both space and time. In the approximation where the scales of the time and space variation are long compared with the period and wavelength, the ray-tracing equations can be generalized and then include an additional first-order differential equation that determines the variation of frequency. In such circumstances the wave can exchange energy with the background: wave energy is not conserved. In such processes the wave action theorem shows that the wave action, defined as the ratio of the wave energy to the frequency in the local rest frame, is conserved. In this paper we discuss ray-tracing techniques and the energy exchange relation for MHD waves. We then provide a unified account of how to deal with energy transport by MHD waves in non-uniform media. The wave action theorem is derived directly from the basic MHD equations for sound waves, transverse Alfvén waves, and the fast and slow magnetosonic waves. The techniques described are applied to a number of illustrative cases. These include a sound wave in a medium undergoing a uniform compression, an isotropic Alfvén wave in a steady-state shear layer, and a transverse Alfvén wave in a simple model of the magnetotail undergoing compression. In each case the nature and magnitude of the energy exchange between wave and background is found.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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

    2015-05-15

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

  10. Energy and Information Transfer Via Coherent Exciton Wave Packets

    NASA Astrophysics Data System (ADS)

    Zang, Xiaoning

    Electronic excitons are bound electron-hole states that are generated when light interacts with matter. Such excitations typically entangle with phonons and rapidly decohere; the resulting electronic state dynamics become diffusive as a result. However, if the exciton-phonon coupling can be reduced, it may be possible to construct excitonic wave packets that offer a means of efficiently transmitting information and energy. This thesis is a combined theory/computation investigation to design condensed matter systems which support the requisite coherent transport. Under the idealizing assumption that exciton-phonon entanglement could be completely suppressed, the majority of this thesis focuses on the creation and manipulation of exciton wave packets in quasi-one-dimensional systems. While each site could be a silicon quantum dot, the actual implementation focused on organic molecular assemblies for the sake of computational simplicity, ease of experimental implementation, potential for coherent transport, and promise because of reduced structural uncertainty. A laser design was derived to create exciton wave packets with tunable shape and speed. Quantum interference was then exploited to manipulate these packets to block, pass, and even dissociate excitons based on their energies. These developments allow exciton packets to be considered within the arena of quantum information science. The concept of controllable excitonic wave packets was subsequently extended to consider molecular designs that allow photons with orbital angular momentum to be absorbed to create excitons with a quasi-angular momentum of their own. It was shown that a well-defined measure of topological charge is conserved in such light-matter interactions. Significantly, it was also discovered that such molecules allow photon angular momenta to be combined and later emitted. This amounts to a new way of up/down converting photonic angular momentum without relying on nonlinear optical materials. The

  11. 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

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

    SciTech Connect

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

    1996-01-01

    When the resonance condition of the particle-wave interaction is varied adiabatically, the particles trapped in a wave are found to form phase space holes or clumps that enhance the particle-wave energy exchange. This mechanism can cause increased saturation levels of instabilities and even allow the free energy associated with instability to be tapped in a system in which background dissipation suppresses linear instability.

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

    SciTech Connect

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

    1995-10-01

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

  14. Experimental study of ultrasonic beam sectors for energy conversion into Lamb waves and Rayleigh waves.

    PubMed

    Declercq, Nico Felicien

    2014-02-01

    When a bounded beam is incident on an immersed plate Lamb waves or Rayleigh waves can be generated. Because the amplitude of a bounded beam is not constant along its wave front, a specific beam profile is formed that influences the local efficiency of energy conversion of incident sound into Lamb waves or Rayleigh waves. Understanding this phenomenon is important for ultrasonic immersion experiments of objects because the quality of such experiments highly depends on the amount of energy transmitted into the object. This paper shows by means of experiments based on monochromatic Schlieren photography that the area within the bounded beam responsible for Lamb wave generation differs from that responsible for Rayleigh wave generation. Furthermore it provides experimental verification of an earlier numerical study concerning Rayleigh wave generation.

  15. Unstructured-grid Modeling for Wave Energy Resource Assessment

    NASA Astrophysics Data System (ADS)

    Wu, W. C.; Yang, Z.; Wang, T.

    2016-12-01

    Model hindcasts of wave climate have been widely recognized in assessing wave energy resource and understanding the temporal and spatial variability in the wave resource. However, there is a challenge to simulate wave climate with localized high resolution in a large model domain. Therefore there is a need to explore the benefits and evaluate the performance of unstructured-grid models for a large wave modeling domain of interests. In this study, the unstructured-grid, third generation spectral wave model - Simulating Waves Nearshore (UNSWAN) was evaluated in a test bed in the central Oregon Coast, with comparison to structured-grid models, such as WaveWatchIII (WWIII). UNSWAN was forced by open boundary input from WaveWatchIII model outputs and wind forcing from NOAA NCEP's Climate Forecast System Reanalysis (CFSR) dataset. The WWIII model outputs were generated by the regional wave models nested with the global wave model. The CFSR winds have 0.5o spatial resolution and 1-hour temporal resolution. The model was validated with observed wave data from National Data Buoy Center (NDBC) buoys within the test bed. Simulated six IEC wave resource parameters using UNSWAN showed a good agreement with observed data. The average root-mean-squared error and correlation coefficient are 0.45 and 0.94 for significant wave height, and 0.96 and 0.91 for energy period respectively. The UNSWAN model can successfully reproduce the temporal variability of wave climate in the test bed. This study shows that unstructured-grid wave modeling provides advantages in computational efficiency and practical approach for simulating wave climates near complex geometries. Potential application of UNSWAN to a regional-scaled model domain is also discussed.

  16. Energy cascades and rogue waves in superfluid 4He

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

    We report the results of recent experiments on second sound in a high Q resonator. Nonlinear wave interactions give rise to a form of acoustic turbulence in which there is a Kolmogorov-like cascade of energy through the frequency scales from the frequency at which it is injected towards higher frequencies until, eventually, dissipative processes come to dominate and terminate the energy flux. We report that that, under some circumstances, an inverse energy cascade occurs, whereby there is a steady flux of energy towards lower frequencies, a wholly unexpected result that bears on the suggestion that rogue waves on the ocean may arise through nonlinear interactions between conventional wind-blown waves.

  17. Preliminary Analysis of a Submerged Wave Energy Device

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  18. 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.

  19. Wave energy gradients and shoreline change on Vabbinfaru platform, Maldives

    NASA Astrophysics Data System (ADS)

    Beetham, Edward Paul; Kench, Paul Simon

    2014-03-01

    This study examined coral reef platform wave processes and shoreline dynamics over short timescales. Wave energy gradients and shoreline change were measured over a 3-week period on Vabbinfaru platform, North Malé Atoll, Maldives, during the westerly monsoon in June 2010. Wave processes were measured using nine pressure sensors recording near continuous data for 19 days around the reef and shoreline of a small circular sand cay. Toe of beach position was surveyed before, during and after the deployment to map changes in shoreline configuration. Results show that wave height and direction on the windward reef are closely controlled by local wind activity inside the atoll lagoon. Wave transformation across the platform was found to exhibit strong tidal modulation and results in distinct cross-reef energy zonation. Results are presented by comparing two contrasting boundary wind conditions: the first 2 weeks characterised by moderate southwest winds, and the third week characterised by stronger northwest winds. Wave data was interpolated to platform scale and used to show spatial variations in energy exposure during the different boundary conditions. Under southwest winds, greatest wave energy was present on the western and leeward (eastern) reefs, driving an energy gradient towards the sheltered northern and southern shorelines. A net 4.5% increase in beach area was measured during this period. During stronger northwest winds, higher wave energy impacted the reef and was concentrated on the western reef, northern reef and northwest shoreline. An energy gradient formed around the island towards a low energy zone located at the southeast shoreline. Significant shoreline change occurred during this period with the toe of beach retreating landward by more than 10 m on the northwest, northeast and southwest of Vabbinfaru Island. Beach area was reduced by 3761 m2 (17%) as the shoreline was forced to adjust in response to a new hydrodynamic regime. Results show that the

  20. ENERGY CONTENT AND PROPAGATION IN TRANSVERSE SOLAR ATMOSPHERIC WAVES

    SciTech Connect

    Goossens, M.; Van Doorsselaere, T.; Soler, R.; Verth, G.

    2013-05-10

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

  1. 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.

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

    PubMed

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

    2017-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

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

  4. Wave energy driven resonant sea water pump

    SciTech Connect

    Czitrom, S.P.R.

    1996-12-31

    A wave driven sea-water pump which operates by resonance is described. Oscillations in the resonant and exhaust ducts perform similar to two mass-spring systems coupled by a third spring acting for the compression chamber. Performance of the pump is optimized by means of a variable volume air compression chamber (patents pending) which tunes the system to the incoming wave frequency. Wave tank experiments with an instrumented, 1:20 scale model of the pump are described. Performance was studied under various wave and tuning conditions and compared to a numerical model which was found to describe the system accurately. Successful sea trials at an energetic coastline provide evidence of the system`s viability under demanding conditions.

  5. Microstructural Design for Stress Wave Energy Management

    DTIC Science & Technology

    2013-04-01

    simulations are based on elastic moduli of generic CFRP taken from literature. We ordered 8 customized 16"xl6"xl/8" panel of unidirectional CFRP from a...speed measurements. We plan to use ultrasonic transducers to measure pressure and shear wave speeds in samples taken from CFRP panel in order to find...of CFRP panel and assembling in a multilayered design. Then we will investigate wave propagation in the layered structure by sending an elastic

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

    NASA Astrophysics Data System (ADS)

    Stoutenburg, E.; Jacobson, M. Z.

    2009-12-01

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

  7. 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.

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

    PubMed

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

    2014-12-01

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

  9. Observations of nearshore infragravity wave dynamics under high energy swell and wind-wave conditions

    NASA Astrophysics Data System (ADS)

    Inch, Kris; Davidson, Mark; Masselink, Gerd; Russell, Paul

    2017-04-01

    Infragravity waves (0.005-0.04 Hz) can dominate the water motion close to shore on low sloping beaches and play a significant role in beach and dune erosion. A new field data set of water surface elevation at 15 cross-shore locations on a dissipative, fetch-unlimited beach is analysed to investigate the forcing and surf zone behaviour of infragravity waves during a wide range of offshore wave conditions (Ho=0.38-3.88 m; Tp=6-20 s). Infragravity waves approach the shore as bound waves lagging slightly ( 4 s) behind the short wave (0.04-0.33 Hz) envelope and are released in the surf zone as free waves. Infragravity wave heights of up to 1 m are measured close to shore and are best predicted using an offshore forcing parameter that represents the short wave energy flux (Ho2 Tp). Considerable infragravity dissipation is observed in the surf zone and dissipation increases with offshore wave energy. Dissipation is highly frequency-dependant and a frequency-domain Complex Empirical Orthogonal Function analysis reveals (quasi-)standing waves at frequencies <0.017 Hz, but an increasingly progressive wave pattern at higher frequencies with reflection coefficients <0.1, indicative of more than 90% dissipation. Much of the observed dissipation occurs very close to shore and the dependence of the reflection coefficient on a normalised bed slope parameter implies that energy at high infragravity frequencies is dissipated by wave breaking, since these frequencies fit into a mild sloping regime. This is supported by the results of bispectral analysis which show predominantly infragravity-infragravity interactions in shallow water and the development of infragravity harmonics indicative of steepening and eventual breaking of the infragravity waves.

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

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

    DOE PAGES

    Gershman, Daniel J.; F-Viñas, Adolfo; Dorelli, John C.; ...

    2017-03-31

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

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

    PubMed Central

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

    2017-01-01

    Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations. PMID:28361881

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

    PubMed

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

    2017-03-31

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

  15. 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.

  16. Mass, momentum, and energy flux conservation for nonlinear wave-wave interaction

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Lin, Zhiliang; Tao, Longbin

    2016-12-01

    A fully nonlinear solution for bi-chromatic progressive waves in water of finite depth in the framework of the homotopy analysis method (HAM) is derived. The bi-chromatic wave field is assumed to be obtained by the nonlinear interaction of two monochromatic wave trains that propagate independently in the same direction before encountering. The equations for the mass, momentum, and energy fluxes based on the accurate high-order homotopy series solutions are obtained using a discrete integration and a Fourier series-based fitting. The conservation equations for the mean rates of the mass, momentum, and energy fluxes before and after the interaction of the two nonlinear monochromatic wave trains are proposed to establish the relationship between the steady-state bi-chromatic wave field and the two nonlinear monochromatic wave trains. The parametric analysis on ɛ1 and ɛ2, representing the nonlinearity of the bi-chromatic wave field, is performed to obtain a sufficiently small standard deviation Sd, which is applied to describe the deviation from the conservation state (Sd = 0) in terms of the mean rates of the mass, momentum, and energy fluxes before and after the interaction. It is demonstrated that very small standard deviation from the conservation state can be achieved. After the interaction, the amplitude of the primary wave with a lower circular frequency is found to decrease; while the one with a higher circular frequency is found to increase. Moreover, the highest horizontal velocity of the water particles underneath the largest wave crest, which is obtained by the nonlinear interaction between the two monochromatic waves, is found to be significantly higher than the linear superposition value of the corresponding velocity of the two monochromatic waves. The present study is helpful to enrich and deepen the understanding with insight to steady-state wave-wave interactions.

  17. Use of numerical wind-wave models for assessment of the offshore wave energy resource

    SciTech Connect

    Pontes, M.T.; Barstow, S.; Bertotti, L.; Cavaleri, L.; Oliveira-Pires, H.

    1997-08-01

    In the last two decades the performance of numerical wind-wave models has improved considerably. Several models have been routinely producing good quality wave estimates globally since the mid-1980s. The verifications of wind-wave models have mainly focused on the evaluation of the error of the significant wave height H{sub s} estimates. However, for wave energy purposes, the main parameters to be assessed are the wave power P{sub w} and the mean (energy) period T{sub e}. Since P{sub w} is proportional to H{sub s}{sup 2}T{sub e}, its expected error is much larger than for the single-wave parameters. This paper summarizes the intercomparison of two wind-wave models against buoy data in the North Atlantic and the Mediterranean Sea to select the most suitable one for the construction of an Atlas of the wave energy resource in European waters. A full verification in the two basins of the selected model--the WAM model, implemented in the routine operation of the European Centre for Medium-Range Weather Forecasts--was then performed against buoy and satellite altimeter data. It was found that the WAM model accuracy is very good for offshore locations in the North Atlantic; but for the Mediterranean Sea the results are much less accurate, probably due to a lower quality of the input wind fields.

  18. Use of numerical wind-wave models for assessment of the offshore wave energy resource

    SciTech Connect

    Pontes, M.T.; Barstow, S.; Bertotti, L.; Cavaleri, L.; Oliveira-Pires, H.

    1996-12-31

    In the last two decades the performance of numerical wind-wave models has improved considerably. Several models have been routinely producing since the mid 1980`s good quality wave estimates globally. The verifications of wind-wave models have mainly focused on the evaluation of the error of the significant wave height H{sub s} estimates. However for wave energy purposes the main parameters to be assessed are the wave power P{sub w} and the mean (energy) period T{sub e}. Since P{sub w} is proportional to H{sub s}{sup 2}T{sub e}, its expected error is much larger than for the single wave parameters. This paper summarizes the intercomparison of two wind-wave models against buoy data in the North Atlantic and the Mediterranean Sea to select the most suitable one for the construction of an Atlas of the wave energy resource in Europe. A full verification in the two basins of the selected model--the WAM model, implemented in the routine operation of the European Centre for Medium-Range Weather Forecasts--was then performed against buoy and satellite altimeter data. It was found that the WAM model accuracy is very good for offshore locations in the North Atlantic, but for the Mediterranean Sea the results are much less accurate probably due to a lower quality of the input wind fields.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    Dallman, A.; Neary, V. S.

    2016-02-01

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

  1. 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.

  2. Methodology for evaluation of European wave energy resource

    SciTech Connect

    Pontes, T.

    1994-12-31

    This paper presents the work performed in order to establish a common methodology for evaluation of the European offshore as well as shoreline wave energy resource. It includes a review (1) on the background theory of ocean waves that is required to deal with resource evaluation, (2) on the phenomena involved in and the methods used to calculate the transformation that waves undergo as they approach the coastline through waters of decreasing depth as well as (3) on the adequate wave data available in Europe. A methodology (proposed to and accepted by the European Community) for the assessment of the European wave energy resource is described. Further research and development work in this field is identified.

  3. Computer Simulation of a Traveling-Wave Direct Energy Converter

    NASA Astrophysics Data System (ADS)

    Katayama, Hideaki; Sato, Kunihiro; Miyawaki, Fujio

    Beam-circuit code is presented to simulate a Traveling-Wave Direct Energy Converter (TWDEC), which recovers the energy of fusion protons escaping from a FRC/D3He fusion reactor. A transmission line loop for propagation of the electrostatic traveling wave is designed using lumped constant elements L.C.R. Electrostatic coupling between proton beam and circuits is treated by directly solving Poisson’s equation. Circuit equations are transformed to temporal finite-difference equations, which are solved following the leap-flog scheme. Simulation results display desirable performance characteristics. Traveling wave with a fixed frequency is excited spontaneously without any external power supply. The wave is kept its equilibrium state under loading, and the wave is stable to variation of the load.

  4. 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.

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

    PubMed

    Jose, Sumy; Hueting, Raymond J E

    2014-10-01

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

  6. Analysis of Waves in the Near-Field of Wave Energy Converter Arrays through Stereo Video

    NASA Astrophysics Data System (ADS)

    Black, C.; Haller, M. C.

    2013-12-01

    Oregon State University conducted a series of laboratory experiments to measure and quantify the near-field wave effects caused within arrays of 3 and 5 Wave Energy Converters (WEC). As the waves and WECs interact, significant scattering and radiation occurs increasing/decreasing the wave heights as well as changing the direction the wave is traveling. These effects may vary based on the number of WECs within an array and their respective locations. The findings of this analysis will assist in selecting the WEC farm location and in improving WEC design. Analyzing the near-field waves will help determine the relative importance of absorption, scattering, and radiation as a function of the incident wave conditions and device performance. The WEC mooring system design specifications may also be impacted if the wave heights in the near-field are greater than expected. It is imperative to fully understand the near-field waves before full-scale WEC farms can be installed. Columbia Power Technologies' Manta served as the test WEC prototype on a 1 to 33 scale. Twenty-three wave gages measured the wave heights in both regular and real sea conditions at locations surrounding and within the WEC arrays. While these gages give a good overall picture of the water elevation behavior, it is difficult to resolve the complicated wave field within the WEC array using point gages. Here stereo video techniques are applied to extract the 3D water surface elevations at high resolution in order to reconstruct the multi-directional wave field in the near-field of the WEC array. The video derived wave information will also be compared against the wave gage data.

  7. 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.

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

    DOE PAGES

    Chang, G.; Ruehl, K.; Jones, C. A.; ...

    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

  9. Effect of spatial discretization of energy on detonation wave propagation

    NASA Astrophysics Data System (ADS)

    Mi, XiaoCheng; Timofeev, Evgeny V.; Higgins, Andrew J.

    2017-04-01

    Detonation propagation in the limit of highly spatially discretized energy sources is investigated. The model of this problem begins with a medium consisting of a calorically perfect gas with a prescribed energy release per unit mass. The energy release is collected into sheet-like sources that are now embedded in an inert gas that fills the spaces between them. The release of energy in the first sheet results in a planar blast wave that propagates to the next source, which is triggered after a prescribed delay, generating a new blast, and so forth. The resulting wave dynamics as the front passes through hundreds of such sources is computationally simulated by numerically solving the governing one-dimensional Euler equations in the lab-fixed reference frame. The average wave speed for each simulation is measured once the wave propagation has reached a quasi-periodic solution. Velocities in excess of the CJ speed are found as the sources are made increasingly discrete, with the deviation above CJ being as great as $15\\%$. The total energy release, delay time, and whether the sources remain lab-fixed or are convected with the flow do not have a significant influence on the deviation of the average wave speed away from CJ. Such continuous waves can also be shown to have a time-averaged structure consistent with the classical ZND structure of a detonation. In the limit of highly discrete sources, temporal averaging of the wave structure shows that the effective sonic surface does not correspond to an equilibrium state. The average state of the flow leaving the wave in this case does eventually reach the equilibrium Hugoniot, but only after the effective sonic surface has been crossed. Thus, the super-CJ waves observed in the limit of highly discretized sources can be understood as weak detonations due to the non-equilibrium state at the effective sonic surface.

  10. 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).

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Orazov, B.; O'Reilly, O. M.; Savaş, Ö.

    2010-11-01

    Buoy-type ocean wave energy converters are designed to exhibit resonant responses when subject to excitation by ocean waves. A novel excitation scheme is proposed which has the potential to improve the energy harvesting capabilities of these converters. The scheme uses the incident waves to modulate the mass of the device in a manner which amplifies its resonant response. To illustrate the novel excitation scheme, a simple one-degree of freedom model is developed for the wave energy converter. This model has the form of a switched linear system. After the stability regime of this system has been established, the model is then used to show that the excitation scheme improves the power harvesting capabilities by 25-65 percent even when amplitude restrictions are present. It is also demonstrated that the sensitivity of the device's power harvesting capabilities to changes in damping becomes much smaller when the novel excitation scheme is used.

  13. 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.

  14. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  16. 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.

  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 propagation of spectral energy content in a granular chain

    NASA Astrophysics Data System (ADS)

    Shrivastava, Rohit Kumar; Luding, Stefan

    2017-06-01

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

  19. 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.

  20. Basic aspects and contributions to the optimization of energy systems exploitation of a super tanker ship

    NASA Astrophysics Data System (ADS)

    Faitar, C.; Novac, I.

    2017-08-01

    Today, the concept of energy efficiency or energy optimization in ships has become one of the main problems of engineers in the whole world. To increase the fiability of a crude oil super tanker ship it means, among other things, to improve the energy performance and optimize the fuel consumption of ship through the development of engines and propulsion system or using alternative energies. Also, the importance of having an effective and reliable Power Management System (PMS) in a vessel operating system means to reduce operational costs and maintain power system of machine parts working in minimum stress in all operating conditions. Studying the Energy Efficiency Design Index and Energy Efficiency Operational Indicator for a crude oil super tanker ship, it allows us to study the reconfiguration of ship power system introducing new generation systems.

  1. 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

  2. Energy transfer from lower energy to higher-energy electrons mediated by whistler waves in the radiation belts

    NASA Astrophysics Data System (ADS)

    Shklyar, D. R.

    2017-01-01

    We study the problem of energy exchange between waves and particles, which leads to energization of the latter, in an unstable plasma typical of the radiation belts. The ongoing Van Allen Probes space mission brought this problem among the most discussed in space physics. A free energy which is present in an unstable plasma provides the indispensable condition for energy transfer from lower energy particles to higher-energy particles via resonant wave-particle interaction. This process is studied in detail by the example of electron interactions with whistler mode wave packets originated from lightning-induced emission. We emphasize that in an unstable plasma, the energy source for electron energization is the energy of other particles, rather than the wave energy as is often assumed. The way by which the energy is transferred from lower energy to higher-energy particles includes two processes that operate concurrently, in the same space-time domain, or sequentially, in different space-time domains, in which a given wave packet is located. In the first process, one group of resonant particles gives the energy to the wave. The second process consists in wave absorption by another group of resonant particles, whose energy therefore increases. We argue that this mechanism represents an efficient means of electron energization in the radiation belts.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. Ultrasound waveform tomography using wave-energy-based preconditioning

    NASA Astrophysics Data System (ADS)

    Zhang, Zhigang; Huang, Lianjie

    2013-03-01

    Ultrasound waveform tomography using the conjugate gradient method produces images with different qualities in different regions of the imaging domain, partly because the ultrasound wave energy is dominant around transducer elements. In addition, this uneven distribution of the wave energy slows down the convergence of the inversion. Using the Hessian matrix to scale the gradients in waveform inversion can reduce the artifacts caused by the geometrical spreading and the defocusing effect resulting from the incomplete data coverage. However, it is computationally expensive to calculate the Hessian matrix. We develop a new ultrasound waveform tomography method that weights the gradient with the ultrasound wave energies of the forward and backward propagation wavefields. Our new method balances the wave energy distribution throughout the entire imaging domain. This method scales the gradients using the square root of the wave energy of forward propagated wavefields from sources and that of backpropagated synthetic wavefields from receivers. We numerically demonstrate that this new ultrasound waveform tomography method improves sound-speed reconstructions of breast tumors and accelerates the convergence of ultrasound waveform tomography.

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

    NASA Astrophysics Data System (ADS)

    Ikehata, Ryo

    2005-06-01

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

  9. Plasmonic assisted two wave mixing phenomenon for energy transfer in ferroelectric PZT film

    NASA Astrophysics Data System (ADS)

    Gupta, Reema; Kumari, Satchi; Tomar, Monika; Gupta, Vinay

    2017-04-01

    Ferroelectric - photorefractive PZT thin films have been exploited to study the energy transfer using pump probe technique for the development of optical delay lines. Two-wave mixing has been studied for three different PZT thin film samples deposited using pulsed laser deposition (PLD) technique. Uniform distribution of gold micro-discs of 40 nm thickness and 120 μm diameter over the surface of PZT thin film plays a vital role in enhancing the two-wave mixing. This is due to the ferroelectric domains present in PZT thin film which get polarized as a result of excited surface plasmons at the Au-PZT interface. The dual effect leads to an enhanced energy transfer from pump to 'Probe Beam'. The maximum two-wave mixing gain was found to be about 1.185 and 1.055 respectively for gold micro-discs patterned and bare PZT thin film deposited on STO substrate. In comparison, the PZT thin film covered completely with the gold overlayer does not show any significant two wave mixing gain due to the scattering of light by Au overlayer.

  10. Method of, and apparatus for, extracting energy from waves

    SciTech Connect

    Laithwaite, E.R.; Salter, S.H.

    1981-11-17

    In a method of, and apparatus for, extracting energy from waves on a liquid, the precession of a gyroscope in response to angular motion of a member in response to waves performs useful work by operating a hydraulic pump. Advantageously, pairs of gyroscopes having their rotors spinning in opposite directions are mounted in the member so as to balance the output torques of the gyroscopes.

  11. Near IR-emitting DNA-probes exploiting stepwise energy transfer processes.

    PubMed

    Bodi, Andras; Borbas, K Eszter; Bruce, James I

    2007-10-10

    The synthesis and characterisation of two new cyclen-based near IR-emitting lanthanide complexes is reported; the lanthanides are sensitised by rhodamine, which in turn is excited by energy transfer from a coumarin 2 moiety. The three lumophores function as an energy transfer cascade spanning the UV-visible-near IR region of the spectrum, resulting in large Stokes shifts. Double stranded DNA selectively switches one of the two energy transfer processes off, enabling luminescent DNA-sensing in the near IR region. The regioselective di-alkylation of the cyclen scaffold is explained with the help of DFT calculations.

  12. 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

  13. Exploiting rotational and translational invariance of the energy in derivative calculations in quantum chemistry

    NASA Astrophysics Data System (ADS)

    Page, M.; Saxe, P.; Adams, G. F.; Lengsfield, B. H., III

    1984-02-01

    It is shown how the invariance of the Born—Oppenheimer potential energy to overall translations and rotations of a molecule can be used to reduce the computational labor required for derivative evaluations at various orders.

  14. Multistable chain for ocean wave vibration energy harvesting

    NASA Astrophysics Data System (ADS)

    Harne, R. L.; Schoemaker, M. E.; Wang, K. W.

    2014-03-01

    The heaving of ocean waves is a largely untapped, renewable kinetic energy resource. Conversion of this energy into electrical power could integrate with solar technologies to provide for round-the-clock, portable, and mobile energy supplies usable in a wide variety of marine environments. However, the direct drive conversion methodology of gridintegrated wave energy converters does not efficiently scale down to smaller, portable architectures. This research develops an alternative power conversion approach to harness the extraordinarily large heaving displacements and long oscillation periods as an excitation source for an extendible vibration energy harvesting chain. Building upon related research findings and engineering insights, the proposed system joins together a series of dynamic cells through bistable interfaces. Individual impulse events are generated as the inertial mass of each cell is pulled across a region of negative stiffness to induce local snap through dynamics; the oscillating magnetic inertial mass then generates current in a coil which is connected to energy harvesting circuitry. It is shown that linking the cells into a chain transmits impulses through the system leading to cascades of vibration and enhancement of electrical energy conversion from each impulse event. This paper describes the development of the multistable chain and ways in which realistic design challenges were addressed. Numerical modeling and corresponding experiments demonstrate the response of the chain due to slow and large amplitude input motion. Lastly, experimental studies give evidence that energy conversion efficiency of the chain for wave energy conversion is much higher than using an equal number of cells without connections.

  15. Energy Partitioning of Seismic Waves in Fractured Rocks

    SciTech Connect

    1997-08-31

    Advances in locating and characterizes fractures in oil and gas reservoirs, and at waste isolation sites from seismic surveys requires improved interpretation methods. Experimental and theoretical results from this work have lead to an understanding of diagnostic signatures of energy that is partitioned into body waves and guided modes by fractures. Compressional waves and shear waves (i.e., shear waves with particle motion perpendicular to the fracture plane) are sensitive to changes in shear stress on a pre-existing fracture and to the formation of a fracture in a previously intact specimen. Both types of waves exhibit a shift in frequency content and a change in the amplitude of the wave as a fracture is formed or a pre-existing fracture is closed. The dispersion characteristics of interfact waves that propagate along a fracture enable quantification of fracture specific stiffness. A new compressional-mode interface wave was measured that has the potential for becoming a diagnostic tool for changes in stress in a fracture. The results of this research provide the basis for the development of seismic imaging techniques and analyses tools for locating and characterizing fractures on the field scale.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

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

    2015-06-15

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

  18. 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.

  19. Energy density of relic gravity waves from inflation

    SciTech Connect

    Sahni, V. )

    1990-07-15

    We evaluate both the spectral energy density and the total energy density for relic gravity waves produced during the transition from an early inflationary phase to a matter-dominated Friedmann-Robertson-Walker-type expansion: {ital a}{similar to}{ital t}{sup {ital c}} ({ital c}{lt}1). We find that for power-law inflation the spectral energy density for gravity waves has more power on larger scales than for purely exponential inflation. Evaluating the energy density of created massless particles (both gravitons and massless scalars) we find that in the case of exponential inflation the ratio of the density of created particles to the total density of matter is a constant, if {ital c}{ge}1/2. This unusual behavior is a consequence of the fact that the equation of state for created particles mimics the equation of state for matter driving the expansion of the Universe. As a result, self-consistent solutions of the Einstein equations can be found, in which the expansion of the Universe is sustained solely by the ongoing production of massless particles, so that {ital G}{sub {mu}{nu}}=8{pi}{ital G}{l angle}{ital T}{sub {mu}{nu}}{r angle}. In the case of power-law and quasiexponential inflation we find that the ratio of the energy density of gravity waves to the background matter density increases with time, as gravity waves with longer wavelengths and larger amplitudes enter the horizon at successively later epochs. This could lead to the energy density of gravity waves becoming comparable to the energy density of matter at late times, if inflation commenced at Planckian energies.

  20. Water and energy linkages for groundwater exploitation: a case study of Gujarat State, India.

    PubMed

    Gupta, Rajiv K

    2002-01-01

    Water and energy, two important resources for human development, have inextricable interlinkages between them. Their complementarity, a blessing otherwise, causes a vicious cycle in a complex situation like the present case study of Gujarat State, India. This paper analyses the demand-supply situation of both sectors for a State that is primarily agrarian but also with a high industrial growth rate. Due to inequitable distribution of surface water, recurrent droughts and ever increasing demand trend, groundwater (a major source in the State) has been overexploited in many parts, leading to 'water mining' with worsening water quality. With more than 40% energy consumed for extracting groundwater, this has had a serious impact on the energy balance. The paper discusses the energy requirements to satisfy the water needs and the water requirements for generation of energy. Finally, the feasible options available to meet the crisis, ranging from development of mega projects like Sardar Sarovar and Kalpasar to micro water harvesting structures, water pricing, consumer training etc., are reviewed.

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

    NASA Astrophysics Data System (ADS)

    Behzad, Hamed; Panahi, Roozbeh

    2017-06-01

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

  2. 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

  3. Exploiting neutron-rich radioactive ion beams to constrain the symmetry energy

    NASA Astrophysics Data System (ADS)

    Kohley, Z.; Christian, G.; Baumann, T.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Jones, M.; Smith, J. K.; Snyder, J.; Spyrou, A.; Thoennessen, M.

    2013-10-01

    The Modular Neutron Array (MoNA) and 4 Tm Sweeper magnet were used to measure the free neutrons and heavy charged particles from the radioactive ion beam induced 32Mg+9Be reaction. The fragmentation reaction was simulated with the constrained molecular dynamics model (CoMD), which demonstrated that the of the heavy fragments and free neutron multiplicities were observables sensitive to the density dependence of the symmetry energy at subsaturation densities. Through comparison of these simulations with the experimental data, constraints on the density dependence of the symmetry energy were extracted. The advantage of radioactive ion beams as a probe of the symmetry energy is demonstrated through examination of CoMD calculations for stable and radioactive-beam-induced reactions.

  4. Exploitation of a tristable nonlinear oscillator for improving broadband vibration energy harvesting

    NASA Astrophysics Data System (ADS)

    Zhou, Shengxi; Cao, Junyi; Lin, Jing; Wang, Zezhou

    2014-09-01

    Numerical and experimental investigations of a broadband vibration energy harvester with triple-well are presented. The nonlinear restoring force of the tristable oscillator is experimentally identified as a high order polynomial that depends on the relative spacing and locations of the magnets in the magnetically coupled piezoelectric cantilever. Simulations and experiments are performed at different harmonic excitation levels ranging from 10 to 35 Hz. The tristable energy harvester possesses the unique jump characteristics of oscillation center stemming from excitation level and initial displacements. Its broad frequency range of 15.1-32.5 Hz is obtained from the transition among three wells. It is also demonstrated that the tristable nonlinear oscillator will be more helpful to improve the broadband performance for harvesting vibration energy under low frequency excitations.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. Energy eigenstates of magnetostatic waves and oscillations.

    PubMed

    Kamenetskii, E O

    2001-06-01

    Effect of excitation of magnetostatic oscillations in a ferrite resonator by the microwave magnetic field was a subject of many publications of more than the last 40 years. The most interesting multiresonance spectrum of absorption peaks one can observe experimentally is a case of disk-form small ferrite resonators. It is shown in this paper that such small ferrite resonators can be considered as "artificial molecular structures" with properties characterized by energy eigenstates of magnetostatic oscillations. A special interest in these properties may be found in the field of microwave artificial composite materials.

  11. Energy eigenstates of magnetostatic waves and oscillations

    SciTech Connect

    Kamenetskii, E. O.

    2001-06-01

    Effect of excitation of magnetostatic oscillations in a ferrite resonator by the microwave magnetic field was a subject of many publications of more than the last 40 years. The most interesting multiresonance spectrum of absorption peaks one can observe experimentally is a case of disk-form small ferrite resonators. It is shown in this paper that such small ferrite resonators can be considered as {open_quotes}artificial molecular structures{close_quotes} with properties characterized by energy eigenstates of magnetostatic oscillations. A special interest in these properties may be found in the field of microwave artificial composite materials.

  12. 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

  13. Traveling-Wave Direct Energy Converter for Fusion Products

    NASA Astrophysics Data System (ADS)

    Sato, Kunihiro; Katayama, Hideaki

    1999-11-01

    A Traveling-Wave Direct Energy Converter (TWDEC), which is designed to recover kinetic energy of fusion protons escaped from a FRC/ D^3He fusion reactor, is studied by numerical calculation and computer simulation. To develop a simulation code, a transmission line loop for an electrostatic traveling wave is designed using lumped constant elements L, C, R. Electrostatic coupling between proton beam and circuits is treated by directly solving Poisson's equation. Circuit equations are transformed to temporal finite-difference equations, which are solved following the leap-flog scheme. Simulation results display desirable performance characteristics of the TWDEC. Traveling wave with a fixed frequency is excited spontaneously without any external electric power supply. High energy conversion rate of the TWDEC up to 0.8 is obtained both from orbit calculation and from computer simulation as a result of improvement of proton beam bunching. The wave keeps its equilibrium state under loading, and the wave responds to variation of the electric load stably.

  14. Exploiting stiffness nonlinearities to improve flow energy capture from the wake of a bluff body

    NASA Astrophysics Data System (ADS)

    Alhadidi, Ali H.; Abderrahmane, Hamid; Daqaq, Mohammed F.

    2016-12-01

    Fluid-structure coupling mechanisms such as wake galloping have been recently utilized to develop scalable flow energy harvesters. Unlike traditional rotary-type generators which are known to suffer serious scalability issues because their efficiency drops significantly as their size decreases; wake-galloping flow energy harvesters (FEHs) operate using a very simple motion mechanism, and, hence can be scaled down to fit the desired application. Nevertheless, wake-galloping FEHs have their own shortcomings. Typically, a wake-galloping FEH has a linear restoring force which results in a very narrow lock-in region. As a result, it does not perform well under the broad range of shedding frequencies normally associated with a variable flow speed. To overcome this critical problem, this article demonstrates theoretically and experimentally that, a bi-stable restoring force can be used to broaden the steady-state bandwidth of wake galloping FEHs and, thereby to decrease their sensitivity to variations in the flow speed. An experimental case study is carried out in a wind tunnel to compare the performance of a bi-stable and a linear FEH under single- and multi-frequency vortex street. An experimentally-validated lumped-parameters model of the bi-stable harvester is also introduced, and solved using the method of multiple scales to study the influence of the shape of the potential energy function on the output voltage.

  15. 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.

  16. Small energy traveling waves for the Euler-Korteweg system

    NASA Astrophysics Data System (ADS)

    Audiard, Corentin

    2017-09-01

    We investigate the existence and properties of traveling waves for the Euler-Korteweg system with general capillarity and pressure. Our main result is the existence in dimension two of waves with arbitrarily small energies. They are obtained as minimizers of a modified energy with fixed momentum. The proof builds upon various ideas developed for the Gross-Pitaevskii equation (and more generally nonlinear Schrödinger equations with non zero limit at infinity). Even in the Schrödinger case, the fact that we work with the hydrodynamical variables and a general pressure law both brings new difficulties and some simplifications. Independently, in dimension one we prove that the criterion for the linear instability of traveling waves from Benzoni-Gavage (2013 Differ. Integral Equ. 26 439-85) actually implies nonlinear instability.

  17. [High energy shock wave treatment of the painful heel spur].

    PubMed

    Perlick, L; Boxberg, W; Giebel, G

    1998-12-01

    Extracorporal shock wave application (ESWA) has been used in the treatment of stones located in kidneys, bile, pancreas and the glandula parotis. In the last 2 years several studies have shown the benefit of the ESWA on the treatment of soft tissue disorders. The aim of this study was to explore the effect of high energy extracorporal shock waves in patients with painful calcaneus spurs. 83 patients who underwent medicophysical treatment without benefit were treated with 3000 impulses of 0.30 mj/mm2. Follow-ups after 12 weeks and 12 months showed that 51 of 83 patients became pain-free and 20 patients improved from the treatment. The results are showing the benefit of the high energy extracorporal shock wave application in the treatment of chronic plantar fasciitis.

  18. 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

  19. 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

    2016-06-08

    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.

  20. Exploiting a nonlinear restoring force to improve the performance of flow energy harvesters

    NASA Astrophysics Data System (ADS)

    Bibo, Amin; Alhadidi, Ali H.; Daqaq, Mohammed F.

    2015-01-01

    This paper investigates employing a nonlinear restoring force to improve the performance of flow energy harvesters (FEHs). To that end, a galloping FEH possessing a quartic potential energy function of the form V =1/2 μy2+1/4 γy4 is considered. This potential function is used to model either a softening (μ > 0, γ < 0), hardening (μ > 0, γ > 0), or bi-stable (μ < 0, γ > 0) restoring force. A physics-based model of the harvester is obtained assuming piezoelectric transduction and a quasi-steady flow field. The model is validated against experimental data and used to obtain a closed-form solution of the response by employing a multiple scaling perturbation analysis using the Jacobi elliptic functions. The attained solution is subsequently used to investigate the influence of the nonlinearity on the performance of the harvester and to illustrate how to optimize the restoring force in order to maximize the output power for given design conditions and airflow parameters. Specifically, it is shown that for similar design parameters and equal magnitudes of μ, and γ, a bi-stable energy harvester outperforms all other configurations as long as the inter-well motions are activated. On the other hand, if the motion of the bi-stable harvester is limited to a single well, then a harvester incorporating a softening nonlinear restoring force outperforms all other configurations. Furthermore, when comparing two FEHs incorporating the same type of restoring force at the optimal load and similar values of μ, then the FEH with the smaller γ is shown to provide higher output power levels.

  1. Energy Content & Spectral Energy Representation of Wave Propagation in a Granular Chain

    NASA Astrophysics Data System (ADS)

    Shrivastava, Rohit; Luding, Stefan

    2017-04-01

    A mechanical wave is propagation of vibration with transfer of energy and momentum. Studying the energy as well as spectral energy characteristics of a propagating wave through disordered granular media can assist in understanding the overall properties of wave propagation through materials like soil. The study of these properties is aimed at modeling wave propagation for oil, mineral or gas exploration (seismic prospecting) or non-destructive testing for the study of internal structure of solids. Wave propagation through granular materials is often accompanied by energy attenuation which is quantified by Quality factor and this parameter has often been used to characterize material properties, hence, determining the Quality factor (energy attenuation parameter) can also help in determining the properties of the material [3], studied experimentally in [2]. The study of Energy content (Kinetic, Potential and Total Energy) of a pulse propagating through an idealized one-dimensional discrete particle system like a mass disordered granular chain can assist in understanding the energy attenuation due to disorder as a function of propagation distance. The spectral analysis of the energy signal can assist in understanding dispersion as well as attenuation due to scattering in different frequencies (scattering attenuation). The selection of one-dimensional granular chain also helps in studying only the P-wave attributes of the wave and removing the influence of shear or rotational waves. Granular chains with different mass distributions have been studied, by randomly selecting masses from normal, binary and uniform distributions and the standard deviation of the distribution is considered as the disorder parameter, higher standard deviation means higher disorder and lower standard deviation means lower disorder [1]. For obtaining macroscopic/continuum properties, ensemble averaging has been invoked. Instead of analyzing deformation-, velocity- or stress

  2. 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.

  3. Chained lightning, part I: Exploitation of energy and radiobiological principles for therapeutic purposes.

    PubMed

    Hoh, Daniel J; Liu, Charles Y; Pagnini, Paul G; Yu, Cheng; Wang, Michael Y; Apuzzo, Michael L J

    2007-07-01

    The fundamental principle of radiosurgery is the focusing of energy within a restricted target volume. In examining the history of radiosurgery, various strategies for addressing this issue of energy containment become apparent. This is the first in a series of articles that reviews the evolution of radiosurgery through the development of instruments for beam generation and delivery for improved conformal therapy. In this first part of the series, we focus specifically on beam generation and the development of particle beams as the initial approach in radiosurgery for focused radiation treatment. We examine the physical characteristics and biological effects of particles and the unique advantage they confer for radiosurgery. We consider clinical studies and treatment of neurological diseases with particles and also assess boron neutron capture therapy as a strategy for selectively targeting neutron beams. Later in this series, we explore methods of beam delivery with the development of stereotactic radiosurgery. Finally, we introduce new concepts and applications in radiosurgery such as nanotechnology, radiation enhancement, ultrasound, near infrared, and free electron lasers. The elaboration of these efforts sets the stage for neurosurgeons to further explore new ideas, develop innovative technology, and advance the practice of radiosurgery.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  9. Self-similar relativistic blast waves with energy injection

    NASA Astrophysics Data System (ADS)

    van Eerten, Hendrik

    2014-08-01

    A sufficiently powerful astrophysical source with power-law luminosity in time will give rise to a self-similar relativistic blast wave with a reverse shock travelling into the ejecta and a forward shock moving into the surrounding medium. Once energy injection ceases and the last energy is delivered to the shock front, the blast wave will transit into another self-similar stage depending only on the total amount of energy injected. I describe the effect of limited duration energy injection into environments with density depending on radius as a power law, emphasizing optical/X-ray Gamma-ray Burst afterglows as applications. The blast wave during injection is treated analytically, the transition following last energy injection with one-dimensional simulations. Flux equations for synchrotron emission from the forward and reverse shock regions are provided. The reverse shock emission can easily dominate, especially with different magnetizations for both regions. Reverse shock emission is shown to support both the reported X-ray and optical correlations between afterglow plateau duration and end time flux, independently of the luminosity power-law slope. The model is demonstrated by application to bursts 120521A and 090515, and can accommodate their steep post-plateau light-curve slopes.

  10. WEC3: Wave Energy Converter Code Comparison Project: Preprint

    SciTech Connect

    Combourieu, Adrien; Lawson, Michael; Babarit, Aurelien; Ruehl, Kelley; Roy, Andre; Costello, Ronan; Laporte Weywada, Pauline; Bailey, Helen

    2017-01-01

    This paper describes the recently launched Wave Energy Converter Code Comparison (WEC3) project and present preliminary results from this effort. The objectives of WEC3 are to verify and validate numerical modelling tools that have been developed specifically to simulate wave energy conversion devices and to inform the upcoming IEA OES Annex VI Ocean Energy Modelling Verification and Validation project. WEC3 is divided into two phases. Phase 1 consists of a code-to-code verification and Phase II entails code-to-experiment validation. WEC3 focuses on mid-fidelity codes that simulate WECs using time-domain multibody dynamics methods to model device motions and hydrodynamic coefficients to model hydrodynamic forces. Consequently, high-fidelity numerical modelling tools, such as Navier-Stokes computational fluid dynamics simulation, and simple frequency domain modelling tools were not included in the WEC3 project.

  11. Stochastic control of inertial sea wave energy converter.

    PubMed

    Raffero, Mattia; Martini, Michele; Passione, Biagio; Mattiazzo, Giuliana; Giorcelli, Ermanno; Bracco, Giovanni

    2015-01-01

    The ISWEC (inertial sea wave energy converter) is presented, its control problems are stated, and an optimal control strategy is introduced. As the aim of the device is energy conversion, the mean absorbed power by ISWEC is calculated for a plane 2D irregular sea state. The response of the WEC (wave energy converter) is driven by the sea-surface elevation, which is modeled by a stationary and homogeneous zero mean Gaussian stochastic process. System equations are linearized thus simplifying the numerical model of the device. The resulting response is obtained as the output of the coupled mechanic-hydrodynamic model of the device. A stochastic suboptimal controller, derived from optimal control theory, is defined and applied to ISWEC. Results of this approach have been compared with the ones obtained with a linear spring-damper controller, highlighting the capability to obtain a higher value of mean extracted power despite higher power peaks.

  12. 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

  13. 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.

  14. Optimization of quantum Monte Carlo wave functions by energy minimization.

    PubMed

    Toulouse, Julien; Umrigar, C J

    2007-02-28

    We study three wave function optimization methods based on energy minimization in a variational Monte Carlo framework: the Newton, linear, and perturbative methods. In the Newton method, the parameter variations are calculated from the energy gradient and Hessian, using a reduced variance statistical estimator for the latter. In the linear method, the parameter variations are found by diagonalizing a nonsymmetric estimator of the Hamiltonian matrix in the space spanned by the wave function and its derivatives with respect to the parameters, making use of a strong zero-variance principle. In the less computationally expensive perturbative method, the parameter variations are calculated by approximately solving the generalized eigenvalue equation of the linear method by a nonorthogonal perturbation theory. These general methods are illustrated here by the optimization of wave functions consisting of a Jastrow factor multiplied by an expansion in configuration state functions (CSFs) for the C2 molecule, including both valence and core electrons in the calculation. The Newton and linear methods are very efficient for the optimization of the Jastrow, CSF, and orbital parameters. The perturbative method is a good alternative for the optimization of just the CSF and orbital parameters. Although the optimization is performed at the variational Monte Carlo level, we observe for the C2 molecule studied here, and for other systems we have studied, that as more parameters in the trial wave functions are optimized, the diffusion Monte Carlo total energy improves monotonically, implying that the nodal hypersurface also improves monotonically.

  15. Optimization of quantum Monte Carlo wave functions by energy minimization

    NASA Astrophysics Data System (ADS)

    Toulouse, Julien; Umrigar, C. J.

    2007-02-01

    We study three wave function optimization methods based on energy minimization in a variational Monte Carlo framework: the Newton, linear, and perturbative methods. In the Newton method, the parameter variations are calculated from the energy gradient and Hessian, using a reduced variance statistical estimator for the latter. In the linear method, the parameter variations are found by diagonalizing a nonsymmetric estimator of the Hamiltonian matrix in the space spanned by the wave function and its derivatives with respect to the parameters, making use of a strong zero-variance principle. In the less computationally expensive perturbative method, the parameter variations are calculated by approximately solving the generalized eigenvalue equation of the linear method by a nonorthogonal perturbation theory. These general methods are illustrated here by the optimization of wave functions consisting of a Jastrow factor multiplied by an expansion in configuration state functions (CSFs) for the C2 molecule, including both valence and core electrons in the calculation. The Newton and linear methods are very efficient for the optimization of the Jastrow, CSF, and orbital parameters. The perturbative method is a good alternative for the optimization of just the CSF and orbital parameters. Although the optimization is performed at the variational Monte Carlo level, we observe for the C2 molecule studied here, and for other systems we have studied, that as more parameters in the trial wave functions are optimized, the diffusion Monte Carlo total energy improves monotonically, implying that the nodal hypersurface also improves monotonically.

  16. 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

  17. 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

    2016-06-06

    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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Hydroelectromechanical modelling of a piezoelectric wave energy converter

    NASA Astrophysics Data System (ADS)

    Renzi, E.

    2016-11-01

    We investigate the hydroelectromechanical-coupled dynamics of a piezoelectric wave energy converter. The converter is made of a flexible bimorph plate, clamped at its ends and forced to motion by incident ocean surface waves. The piezoceramic layers are connected in series and transform the elastic motion of the plate into useful electricity by means of the piezoelectric effect. By using a distributed-parameter analytical approach, we couple the linear piezoelectric constitutive equations for the plate with the potential-flow equations for the surface water waves. The resulting system of governing partial differential equations yields a new hydroelectromechanical dispersion relation, whose complex roots are determined with a numerical approach. The effect of the piezoelectric coupling in the hydroelastic domain generates a system of short- and long-crested weakly damped progressive waves travelling along the plate. We show that the short-crested flexural wave component gives a dominant contribution to the generated power. We determine the hydroelectromechanical resonant periods of the device, at which the power output is significant.

  3. 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.

  4. Performance Optimization of a Pneumatic Wave Energy Conversion Device.

    DTIC Science & Technology

    1982-08-26

    The edges of the internal plexi - glass turbine casing was rounded off to reduce turbulence in the air flow. The turbine was now read-F for the second...As a wave approaches shore it interacts with the sea floor and loses energy due to bottom friction and irrotationalities. The deep water condition...heavier parts had increased the internal friction of the system, and to see if the turbine could handle the effects of greater air flow. For this

  5. High-Energy Waves in Superpolynomial FPU-Type Chains

    NASA Astrophysics Data System (ADS)

    Herrmann, Michael

    2017-02-01

    We consider periodic traveling waves in FPU-type chains with superpolynomial interaction forces and derive explicit asymptotic formulas for the high-energy limit as well as bounds for the corresponding approximation error. In the proof we adapt twoscale techniques that have recently been developed by Herrmann and Matthies for chains with singular potential and provide an asymptotic ODE for the scaled distance profile.

  6. Energy device powered by the motion of water beneath waves

    SciTech Connect

    Smith, E.J.

    1983-02-01

    A device for extracting both kinetic and potential energy from the motion beneath waves over a considerable depth comprising a power member or sail guided to reciprocate with the movement of the water. The power sail is connected to and operates a power device such as an electric generator or pump. A second member, or sail, is located in geometric position relative to the power sail to reflect energy back to the power sail. Sensors, servo systems, and computers may be used to optimize power output. Multiple units can be arranged in ''farms'' to furnish megawatts of power.

  7. Electronic Quasiparticle Renormalization on the Spin Wave Energy Scale

    NASA Astrophysics Data System (ADS)

    Schäfer, J.; Schrupp, D.; Rotenberg, Eli; Rossnagel, K.; Koh, H.; Blaha, P.; Claessen, R.

    2004-03-01

    High-resolution photoemission data of the (110) iron surface reveal the existence of well-defined metallic surface resonances in good correspondence to band calculations. Close to the Fermi level, their dispersion and momentum broadening display anomalies characteristic of quasiparticle renormalization due to coupling to bosonic excitations. Its energy scale exceeds that of phonons by far, and is in striking coincidence with that of the spin wave spectrum in iron. The self-energy behavior thus gives spectroscopic evidence of a quasiparticle mass enhancement due to electron-magnon coupling.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Initiation of reactive blast waves by external energy sources

    NASA Astrophysics Data System (ADS)

    Liñán, Amable; Kurdyumov, Vadim N.; Sánchez, Antonio L.

    2012-11-01

    This article is devoted to the analysis of the direct initiation, by concentrated centrally-symmetric external energy sources, of self-sustained detonation waves in gaseous reactive mixtures. The dynamics of the detonation front will be described in the fast reaction limit, when the thickness of the reaction layer that follows the shock front is very small compared with the shock radius. At early times, after starting the external thermal energy deposition, the detonation front, associated with a strongly expanding flow, is overdriven; thus it is reached by expansion waves that decrease its velocity towards the Chapman-Jouguet (CJ) value, for which the expansion waves can no longer reach the front. The decay occurs for detonation radii such that the energy released by the external source equals the heat released by the chemical reaction. For planar detonations the CJ velocity is only approached asymptotically for large times, while for cylindrical and spherical detonations the flow divergence provides an additional decay mechanism associated with the front curvature that causes the transition to the constant CJ velocity to occur at a finite value of the detonation radius. The time evolution of the flow field and the corresponding variation with deposition time of the transition radius is computed for energy sources of constant heating rate. The analysis includes a detailed quantitative description of the near-front flow structure for times close to the transition time, given here for the first time, along with the study of the evolution towards the Zel'dovich-Taylor cylindrical or spherical self-similar flow structure, which corresponds to a CJ detonation front ideally initiated at the center without any external energy source. The asymptotic decay to CJ is also described for planar detonations initiated with energy sources of constant heating rate and finite nonzero deposition time. A brief discussion will be given on how the reaction may be quenched by the flow

  13. Experimental Investigation of Irregular Wave Cancellation Using a Cycloidal Wave Energy Converter

    DTIC Science & Technology

    2012-07-01

    energy converter (CycWEC) as 2 ω Γ1 Γ2 R W1 W2 W3 W-1 W-2 W-3 D x (xc,yc) y H Ocean Floor Water Surface WAiry η(x,t) Φ(x,y,t) Figure 1. Cycloidal...5kHz AC and consisted of two stainless steel wires and a ground electrode. The signal from the wave gages was first filtered by a high-pass analog

  14. 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%.

  15. Energy flux measurement from the dissipated energy in capillary wave turbulence.

    PubMed

    Deike, Luc; Berhanu, Michael; Falcon, Eric

    2014-02-01

    We study experimentally the influence of dissipation on stationary capillary wave turbulence on the surface of a liquid by changing its viscosity. We observe that the frequency power-law scaling of the capillary spectrum departs significantly from its theoretical value when the dissipation is increased. The energy dissipated by capillary waves is also measured and found to increase nonlinearly with the mean power injected within the liquid. Here we propose an experimental estimation of the energy flux at every scale of the capillary cascade. The latter is found to be nonconstant through the scales. For fluids of low enough viscosity, we found that both capillary spectrum scalings with the frequency and the newly defined mean energy flux are in good agreement with wave turbulence theory. The Kolmogorov-Zakharov constant is then experimentally estimated and compared to its theoretical value.

  16. A closure for eddy-mean flow effects based on the Rossby wave energy equation

    NASA Astrophysics Data System (ADS)

    Eden, Carsten; Olbers, Dirk

    2017-06-01

    The concept of IDEMIX was recently developed to simulate and parameterize the effect of gravity waves on the large-scale circulation. It is applied here to Rossby waves. Since gravity wave drag is formally identical to baroclinic instability it appears possible to parameterize the effect of baroclinic and barotropic instability on the large-scale circulation following the IDEMIX concept which is based here on the Rossby wave energy equation in physical and phase space. The dimensions of that equation are reduced by assuming a fixed shape of the energy spectrum with respect to horizontal wave number. The result is a set of coupled conservation equations for Rossby wave energy compartments resolved in horizontal direction and wave vector angle. Using simple parameterisations for wave-wave interaction, the performance of the closure is tested in an idealized model of baroclinic and barotropic instability where the Rossby waves are assumed to contain the subgrid-scale energy.

  17. 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.

  18. Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter

    SciTech Connect

    Tom, Nathan M.; Yu, Yi-Hsiang; Wright, Alan D.; Lawson, Michael

    2016-06-24

    The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.

  19. 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.

  20. 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

  1. 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.

  2. Pulse energy evolution for high-resolution Lamb wave inspection

    NASA Astrophysics Data System (ADS)

    Hua, Jiadong; Lin, Jing; Zeng, Liang; Gao, Fei

    2015-06-01

    Generally, tone burst excitation methods are used to reduce the effect of dispersion in Lamb wave inspection. In addition, algorithms for dispersion compensation are required to simplify responses, especially in long-range inspection. However, the resolution is always limited by the time duration of tone burst excitation. A pulse energy evolution method is established to overcome this limitation. In this method, a broadband signal with a long time (e.g. a chirp, white noise signal, or a pseudo-random sequence) is used as excitation to actuate Lamb waves. First of all, pulse compression is employed to estimate system impulse response with a high signal-to-noise ratio. Then, dispersion compensation is applied repeatedly with systemically varied compensation distances, obtaining a series of compensated signals. In these signals, amplitude (or energy) evolution associated with the change of compensation distance is utilized to estimate the actual propagation distance of the interested wave packet. Finally, the defect position is detected by an imaging algorithm. Several experiments are given to validate the proposed method.

  3. Performance optimization of a pneumatic wave energy conversion device

    NASA Astrophysics Data System (ADS)

    Surko, S. W.

    1982-08-01

    The purpose of this study was, for the first time, to optimize the performance of a pneumatic wave energy conversion device. The experiments of Jolly and Newmaster (1979) and Trop and Casey (1980) left a capture chamber and turbine for further investigation. To optimize the system performance the turbine had to be first analyzed so that its power performance curves could be determined. These curves were needed to help define the possible overall performance of the system, and for the impedance matching of the system necessary for performance optimization. With this knowledge, an appropriate generator was purchased and a generator-turbine linkage designed and built. The completed system was then analyzed in the 380 ft wave tank at the U.S. Naval Academy to establish its optimum performance. From the research it is clear that pneumatic wave energy conversion is a promising concept. With several hundred of these devices situated some 100 km off the coast of the Pacific Northwest each device would be producing from 50 to 200 kW which would be transferred back to shore.

  4. 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

  5. Marine Hydrokinetic Energy Site Identification and Ranking Methodology Part I: Wave Energy

    SciTech Connect

    Kilcher, Levi; Thresher, Robert

    2016-10-01

    Marine hydrokinetic energy is a promising and growing piece of the renewable energy sector that offers high predictability and additional energy sources for a diversified energy economy. This report investigates the market opportunities for wave energy along the U.S. coastlines. It is part one of a two-part investigation into the United State's two largest marine hydrokinetic resources (wave and tidal). Wave energy technology is still an emerging form of renewable energy for which large-scale, grid-connected project costs are currently poorly defined. Ideally, device designers would like to know the resource conditions at economical project sites so they can optimize device designs. On the other hand, project developers need detailed device cost data to identify sites where projects are economical. That is, device design and siting are, to some extent, a coupled problem. This work describes a methodology for identifying likely deployment locations based on a set of criteria that wave energy experts in industry, academia, and national laboratories agree are likely to be important factors for all technology types. This work groups the data for the six criteria into 'locales' that are defined as the smaller of either the local transmission grid or a state boundary. The former applies to U.S. islands (e.g., Hawaii, American Samoa) and rural villages (e.g., in Alaska); the latter applies to states in the contiguous United States. These data are then scored from 0 to 10 according to scoring functions that were developed with input from wave energy industry and academic experts. The scores are aggregated using a simple product method that includes a weighting factor for each criterion. This work presents two weighting scenarios: a long-term scenario that does not include energy price (weighted zero) and a near term scenario that includes energy price. The aggregated scores are then used to produce ranked lists of likely deployment locales. In both scenarios, Hawaii and

  6. Wave energy absorption by a floating air bag

    NASA Astrophysics Data System (ADS)

    Kurniawan, A.; Chaplin, J. R.; Greaves, D. M.; Hann, M.

    2017-02-01

    A floating air bag, ballasted in water, expands and contracts as it heaves under wave action. Connecting the bag to a secondary volume via a turbine transforms the bag into a device capable of generating useful energy from the waves. Small-scale measurements of the device reveal some interesting properties, which are successfully predicted numerically. Owing to its compressibility, the device can have a heave resonance period longer than that of a rigid device of the same shape and size, without any phase control. Furthermore, varying the amount of air in the bag is found to change its shape and hence its dynamic response, while varying the turbine damping or the air volume ratio changes the dynamic response without changing the shape.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Energy transfer due to nonlinear wave-wave interactions in deep ocean

    NASA Astrophysics Data System (ADS)

    Yokoyama, Naoto; Lvov, Yuri V.

    2007-11-01

    It was believed that the Garrett-Munk spectrum was the ``universal'' energy spectrum of oceanic internal waves. However, it has become apparent from recent categorization of oceanic observations that the Garrett-Munk spectrum can not be as universal as been previously thought. One may use the weak turbulence theory to attempt to explain the formation of the spectral energy density of internal waves. It turns out that the large wavenumbers (small scales) interact in triads via small wavenumbers (large scales). This hypothesis provides possible explanation for the variability of the energy spectra. Namely, several families of statistically steady solutions are found in consideration of the nonlocality in wavenumber spaces of resonant interactions. The new families of power-law exponents of the energy spectra are in good agreement with the observations. To check these theory we perform direct numerical simulations based on Hamiltonian formalism. It is shown also by the numerical simulations that the nonlocal interactions in the wavenumber space are dominant in the inertial wavenumbers. The validity of the weak turbulence theory is also discussed.

  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. 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.

  15. Theoretical and experimental study on the acoustic wave energy after the nonlinear interaction of acoustic waves in aqueous media

    NASA Astrophysics Data System (ADS)

    Lan, Chao-feng; Li, Feng-chen; Chen, Huan; Lu, Di; Yang, De-sen; Zhang, Meng

    2015-06-01

    Based on the Burgers equation and Manley-Rowe equation, the derivation about nonlinear interaction of the acoustic waves has been done in this paper. After nonlinear interaction among the low-frequency weak waves and the pump wave, the analytical solutions of acoustic waves' amplitude in the field are deduced. The relationship between normalized energy of high-frequency and the change of acoustic energy before and after the nonlinear interaction of the acoustic waves is analyzed. The experimental results about the changes of the acoustic energy are presented. The study shows that new frequencies are generated and the energies of the low-frequency are modulated in a long term by the pump waves, which leads the energies of the low-frequency acoustic waves to change in the pulse trend in the process of the nonlinear interaction of the acoustic waves. The increase and decrease of the energies of the low-frequency are observed under certain typical conditions, which lays a foundation for practical engineering applications.

  16. Artificial upwelling using the energy of surface waves

    NASA Astrophysics Data System (ADS)

    Soloviev, A.

    2016-02-01

    The ocean is an important component of climate and climate change, since the heat capacity of a few meters of the upper ocean is equivalent to the heat capacity of the entire atmosphere. (Solar radiation and IR balance in the atmosphere are of course major factors as well.) Artificial upwelling devices using the energy of surface waves, similar to those developed by Vershinskiy, Pshenichnyy, and Soloviev (1987), can bring cold water from below the thermocline to the sea surface. Their wave-inertia pump consisted of a vertical tube, a valve, and a buoy to keep the device afloat. The device operated by using energy of surface waves to create an upward flow of water in the tube. An outlet valve at the top of the unit synchronized the operation of the device with surface waves and prevented 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 10oC 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. This type of artificial upwelling can cool down the sea surface, modify climate on a regional scale and possibly help mitigate hurricanes. The cold water brought from the deep 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 has been estimated for different environmental conditions using a computational fluid dynamics model. The cooled near-surface layer of the ocean will be getting more heat from the sun, which is a detrimental consequence. Cloud seeding can help to mitigate this extra warming. A synergistic approach to climate engineering can thus reduce detriments and increase potential benefits of this system to society.

  17. Capillary Waves And Energy Coupling In Laser Materials Processing

    NASA Astrophysics Data System (ADS)

    Gasser, A.; Herziger, G.; Holtgen, B.; Kreutz, E. W.; Treusch, H. G.

    1987-09-01

    Static and dynamic measurements of the incident laser power, of the diffuse and specular reflected power have been performed in order to determine the absorption behavior of various metals and semiconductors during the interaction with powerful CO2-and Nd:YAG-laser-radiation. The absorptivity of the vapor and laser-induced plasma was probed by high-speed photography and measurements of conductivity transients as a function of intensity, composition, and pressure of the ambient atmosphere. For Ienergy coupling is given by the temperature-dependent refractive index and absorption coefficient of matter. For I>IB the intensity-dependent energy coupling is governed by the generation of photon-induced plasma in the surface region in combination with the dynamics of the molten and vaporized material within the interaction zone giving in addition indication for capillary waves.

  18. 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.

  19. Wave-energy distribution and hurricane effects on Margarita Reef, southwestern Puerto Rico

    NASA Astrophysics Data System (ADS)

    Lugo-Fernández, A.; Hernández-Ávila, M. L.; Roberts, H. H.

    1994-01-01

    Wave measurements at Margarita Reef in southwestern Puerto Rico show that wave height decreases as waves travel across the forereef and into the backreef. Wave spectra reveal the presence of two wave trains impinging on the reef during the study: trade-wind waves and locally generated seas. Significant wave height calculated from the spectra show an average reduction of 19.5% from 20- to 10-m isobaths and 26% from 20- to 5-m isobaths. The significant wave height decreases an average of 82% for waves traveling across the reef crest and into the backreef. Wave-energy reduction is 35% from 20- to 10-m isobaths and 45% from 20- to 5-m isobaths. Energy loss across the reef crest is 97% which translates into the formation of strong across-the-reef currents capable of moving coarse sediment. Refraction diagrams of waves impinging on the reef from the SE provide a display of wave energy distribution around the reef. The transmission coefficients calculated for trade-wind waves and locally generated seas have means of 18% and 39%, respectively. A wave height model with negligible energy dissipation, produces wave height estimates that are, in general, within the ±15% error bands. Results of wave-energy changes from this study were applied to waves representative of hurricane conditions at the reef. Aerial photographs of the reef before and after the passage of hurricanes were compared to assess the reef changes. Changes observed in the photographs are interpreted as products of sediment transport by hurricane-generated waves. The patterns of change agree with the refraction diagrams suggesting that waves were the main agents of change at margarita Reef during severe storms.

  20. 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.

  1. An energy ratio based measure for F-wave backfiring rate estimation.

    PubMed

    Kong, Xuan; Gozani, Shai N

    2010-01-01

    F-wave persistence is a frequently reported parameter for nerve conduction studies. F-wave activities are generated through backfiring of motor neurons. F-wave persistence is designed to estimate the backfiring rate. Through computational models and probability analyses, we demonstrated that the F-wave persistence definition is deficient in providing a robust and consistent estimate of the backfiring rate. We proposed an energy ratio based measure as an alternative to F-wave persistence to estimate backfiring rates. The energy ratio measure is shown to be robust to activity detection threshold and without the ceiling effect suffered by the traditional F-wave persistence.

  2. Single-wave-number representation of nonlinear energy spectrum in elastic-wave turbulence of the Föppl-von Kármán equation: Energy decomposition analysis and energy budget

    NASA Astrophysics Data System (ADS)

    Yokoyama, Naoto; Takaoka, Masanori

    2014-12-01

    A single-wave-number representation of a nonlinear energy spectrum, i.e., a stretching-energy spectrum, is found in elastic-wave turbulence governed by the Föppl-von Kármán (FvK) equation. The representation enables energy decomposition analysis in the wave-number space and analytical expressions of detailed energy budgets in the nonlinear interactions. We numerically solved the FvK equation and observed the following facts. Kinetic energy and bending energy are comparable with each other at large wave numbers as the weak turbulence theory suggests. On the other hand, stretching energy is larger than the bending energy at small wave numbers, i.e., the nonlinearity is relatively strong. The strong correlation between a mode ak and its companion mode a-k is observed at the small wave numbers. The energy is input into the wave field through stretching-energy transfer at the small wave numbers, and dissipated through the quartic part of kinetic-energy transfer at the large wave numbers. Total-energy flux consistent with energy conservation is calculated directly by using the analytical expression of the total-energy transfer, and the forward energy cascade is observed clearly.

  3. Single-wave-number representation of nonlinear energy spectrum in elastic-wave turbulence of the Föppl-von Kármán equation: energy decomposition analysis and energy budget.

    PubMed

    Yokoyama, Naoto; Takaoka, Masanori

    2014-12-01

    A single-wave-number representation of a nonlinear energy spectrum, i.e., a stretching-energy spectrum, is found in elastic-wave turbulence governed by the Föppl-von Kármán (FvK) equation. The representation enables energy decomposition analysis in the wave-number space and analytical expressions of detailed energy budgets in the nonlinear interactions. We numerically solved the FvK equation and observed the following facts. Kinetic energy and bending energy are comparable with each other at large wave numbers as the weak turbulence theory suggests. On the other hand, stretching energy is larger than the bending energy at small wave numbers, i.e., the nonlinearity is relatively strong. The strong correlation between a mode a(k) and its companion mode a(-k) is observed at the small wave numbers. The energy is input into the wave field through stretching-energy transfer at the small wave numbers, and dissipated through the quartic part of kinetic-energy transfer at the large wave numbers. Total-energy flux consistent with energy conservation is calculated directly by using the analytical expression of the total-energy transfer, and the forward energy cascade is observed clearly.

  4. Dispersion and energy conservation relations of surface waves in semi-infinite plasma

    NASA Astrophysics Data System (ADS)

    Atanasov, V.

    1981-04-01

    The hydrodynamic theory of surface wave propagation in semiinfinite homogeneous isotropic plasma is considered. Explicit linear surface wave solutions are given for the electric and magnetic fields, charge and current densities. These solutions are used to obtain the well-known dispersion relations and, together with the general energy conservation equation, to find appropriate definitions for the energy and the energy flow densities of surface waves. These densities are associated with the dispersion relation and the group velocity by formulae similar to those for bulk waves in infinite plasmas. Both cases of high-frequency and low-frequency surface waves are considered.

  5. Operational Exploitation of Satellite-Based Sounding Data and Numerical Weather Prediction Models for Directed Energy Applications

    DTIC Science & Technology

    2015-12-01

    The wealth of available scientific data collected by the modern constellation of meteorological satellites can be exploited in new and innovative...derive optical turbulence strength, as modeled by index of the refraction structure function Cn 2, are applied to integrated meteorological satellite...9 2.3 Additional Meteorological Satellite Instruments Investigated ..........................11 2.3.1 Advanced

  6. 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.

  7. 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.

  8. Gravitational wave sirens as a triple probe of dark energy

    NASA Astrophysics Data System (ADS)

    Linder, Eric V.

    2008-03-01

    Gravitational wave standard sirens have been considered as precision distance indicators of high redshift; however, at high redshift standard sirens or standard candles such as supernovae suffer from lensing noise. We investigate lensing noise as a signal instead and show how measurements of the maximum demagnification (minimum convergence) probe cosmology in a manner highly complementary to the distance itself. Revisiting the original form for minimum convergence we quantify the bias arising from the commonly used approximation. Furthermore, after presenting a new lensing probability function we discuss how the width of the lensed standard siren amplitude distribution also probes growth of structure. Thus standard sirens and candles can serve as triple probes of dark energy, measuring both the cosmic expansion history and growth history.

  9. Comparison of performances of turbines for wave energy conversion

    NASA Astrophysics Data System (ADS)

    Kinoue, Yoichi; Setoguchi, Toshiaki; Kuroda, Tomohiko; Kaneko, Kenji; Takao, Manabu; Thakker, Ajit

    2003-11-01

    The Wells turbine for a wave power generator is a self-rectifying air turbine that is available for an energy conversion in an oscillating water-air column without any rectifying valve. The objective of this paper is to compare the performances of the Wells turbines in which the profile of blade are NACA0020, NACA0015, CA9 and HSIM15-262123-1576 in the small-scale model testing. The running characteristics in the steady flow, the start and running characteristics in the sinusoidal flow and the hysteretic characteristics in the sinusoidal flow were investigated for four kinds of turbine. As a conclusion, the turbine in which the profile of blade is NACA0020 has the best performances among 4 turbines for the running and starting characteristics in the small-scale model testing.

  10. Gravitational wave sirens as a triple probe of dark energy

    SciTech Connect

    Linder, Eric V

    2008-03-15

    Gravitational wave standard sirens have been considered as precision distance indicators of high redshift; however, at high redshift standard sirens or standard candles such as supernovae suffer from lensing noise. We investigate lensing noise as a signal instead and show how measurements of the maximum demagnification (minimum convergence) probe cosmology in a manner highly complementary to the distance itself. Revisiting the original form for minimum convergence we quantify the bias arising from the commonly used approximation. Furthermore, after presenting a new lensing probability function we discuss how the width of the lensed standard siren amplitude distribution also probes growth of structure. Thus standard sirens and candles can serve as triple probes of dark energy, measuring both the cosmic expansion history and growth history.

  11. 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.

  12. Experimental investigation on the hydrodynamic performance of a wave energy converter

    NASA Astrophysics Data System (ADS)

    Zheng, Xiong-bo; Ma, Yong; Zhang, Liang; Jiang, Jin; Liu, Heng-xu

    2017-06-01

    Wave energy is an important type of marine renewable energy. A wave energy converter (WEC) moored with two floating bodies was developed in the present study. To analyze the dynamic performance of the WEC, an experimental device was designed and tested in a tank. The experiment focused on the factors which impact the motion and energy conversion performance of the WEC. Dynamic performance was evaluated by the relative displacements and velocities of the oscillator and carrier which served as the floating bodies of WEC. Four factors were tested, i.e. wave height, wave period, power take-off (PTO) damping, and mass ratio ( R M) of the oscillator and carrier. Experimental results show that these factors greatly affect the energy conversion performance, especially when the wave period matches R M and PTO damping. According to the results, we conclude that: (a) the maximization of the relative displacements and velocities leads to the maximization of the energy conversion efficiency; (b) the larger the wave height, the higher the energy conversion efficiency will be; (c) the relationships of energy conversion efficiency with wave period, PTO damping, and R M are nonlinear, but the maximum efficiency is obtained when these three factors are optimally matched. Experimental results demonstrated that the energy conversion efficiency reached the peak at 28.62% when the wave height was 120 mm, wave period was 1.0 s, R M was 0.21, and the PTO damping was corresponding to the resistance of 100 Ω.

  13. 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 .

  14. 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 .

  15. Potential applications of low-energy shock waves in functional urology.

    PubMed

    Wang, Hung-Jen; Cheng, Jai-Hong; Chuang, Yao-Chi

    2017-08-01

    A shock wave, which carries energy and can propagate through a medium, is a type of continuous transmitted sonic wave with a frequency of 16 Hz-20 MHz. It is accompanied by processes involving rapid energy transformations. The energy associated with shock waves has been harnessed and used for various applications in medical science. High-energy extracorporeal shock wave therapy is the most successful application of shock waves, and has been used to disintegrate urolithiasis for 30 years. At lower energy levels, however, shock waves have enhanced expression of vascular endothelial growth factor, endothelial nitric oxide synthase, proliferating cell nuclear antigen, chemoattractant factors and recruitment of progenitor cells; shock waves have also improved tissue regeneration. Low-energy shock wave therapy has been used clinically with musculoskeletal disorders, ischemic cardiovascular disorders and erectile dysfunction, through the mechanisms of neovascularization, anti-inflammation and tissue regeneration. Furthermore, low-energy shock waves have been proposed to temporarily increase tissue permeability and facilitate intravesical drug delivery. The present review article provides information on the basics of shock wave physics, mechanisms of action on the biological system and potential applications in functional urology. © 2017 The Japanese Urological Association.

  16. Removal of Trigger Delays from Cross-borehole Seismic Data by Exploiting Tube Wave Coherency - A Pre-processing Tool for Waveform Inversion

    NASA Astrophysics Data System (ADS)

    Mol, S.; Pratt, R. G.; Maurer, H.; Smithyman, B. R.

    2015-12-01

    A cross-borehole seismic dataset was acquired using two 50 m deep test boreholes drilled into Permian age sandstones near Mels, Switzerland. The boreholes were approximately 20 m apart, and useful data frequencies between 100 Hz and 4000 Hz. The survey comprised 181 source locations and 192 receiver locations, using multiple deployments of a 24-element receiver array to ensure adequate spatial sampling. Imaging velocities and attenuation using Full Waveform Inversion (FWI) proved difficult due to the presence of significant trigger delays in the survey. Trigger delays can be solved for using either a Traveltime Tomography (TT) approach (by including additional unknowns), or a FWI approach (by individual source estimation). However, these methods introduce significant ambiguities, particularly in the presence of an unknown level of anisotropy. Moreover, the trigger delays break coherency in the common source and common receiver domains, preventing simple removal of the tube wave energy in the data. We introduce a novel method for estimating the trigger delays through cross-correlation of tube waves. Repeat records from identical source-receiver array combinations are shifted and then stacked to create a "reference dataset". We make use of the high amplitude and highly coherent tube waves, which travel at a constant velocity: receiver hole tube wave arrivals are aligned and enhanced by applying a linear moveout and an f-k filter to the common source gathers. Each physical source location is recorded by four closely spaced and interleaved receiver elements; the high level of redundancy enables recovery of a stable set of delay estimates. A similar approach is used for the common receiver gathers to remove the remaining delays between source locations. Trigger delays were corrected with a mean absolute value of 153 μs, a mean bulk shift of -41 μs and a standard deviation of 75 μs. Their removal from the raw seismic data, allowed i) the tube waves to be removed by

  17. Controlling Energy Radiations of Electromagnetic Waves via Frequency Coding Metamaterials

    PubMed Central

    Wu, Haotian; Liu, Shuo; Wan, Xiang; Zhang, Lei; Wang, Dan; Li, Lianlin

    2017-01-01

    Metamaterials are artificial structures composed of subwavelength unit cells to control electromagnetic (EM) waves. The spatial coding representation of metamaterial has the ability to describe the material in a digital way. The spatial coding metamaterials are typically constructed by unit cells that have similar shapes with fixed functionality. Here, the concept of frequency coding metamaterial is proposed, which achieves different controls of EM energy radiations with a fixed spatial coding pattern when the frequency changes. In this case, not only different phase responses of the unit cells are considered, but also different phase sensitivities are also required. Due to different frequency sensitivities of unit cells, two units with the same phase response at the initial frequency may have different phase responses at higher frequency. To describe the frequency coding property of unit cell, digitalized frequency sensitivity is proposed, in which the units are encoded with digits “0” and “1” to represent the low and high phase sensitivities, respectively. By this merit, two degrees of freedom, spatial coding and frequency coding, are obtained to control the EM energy radiations by a new class of frequency‐spatial coding metamaterials. The above concepts and physical phenomena are confirmed by numerical simulations and experiments. PMID:28932671

  18. Controlling Energy Radiations of Electromagnetic Waves via Frequency Coding Metamaterials.

    PubMed

    Wu, Haotian; Liu, Shuo; Wan, Xiang; Zhang, Lei; Wang, Dan; Li, Lianlin; Cui, Tie Jun

    2017-09-01

    Metamaterials are artificial structures composed of subwavelength unit cells to control electromagnetic (EM) waves. The spatial coding representation of metamaterial has the ability to describe the material in a digital way. The spatial coding metamaterials are typically constructed by unit cells that have similar shapes with fixed functionality. Here, the concept of frequency coding metamaterial is proposed, which achieves different controls of EM energy radiations with a fixed spatial coding pattern when the frequency changes. In this case, not only different phase responses of the unit cells are considered, but also different phase sensitivities are also required. Due to different frequency sensitivities of unit cells, two units with the same phase response at the initial frequency may have different phase responses at higher frequency. To describe the frequency coding property of unit cell, digitalized frequency sensitivity is proposed, in which the units are encoded with digits "0" and "1" to represent the low and high phase sensitivities, respectively. By this merit, two degrees of freedom, spatial coding and frequency coding, are obtained to control the EM energy radiations by a new class of frequency-spatial coding metamaterials. The above concepts and physical phenomena are confirmed by numerical simulations and experiments.

  19. 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

  20. Wave energy dissipation due to mudbanks formed off southwest coast of India

    NASA Astrophysics Data System (ADS)

    Samiksha, S. V.; Vethamony, P.; Rogers, W. Erick; Pednekar, P. S.; Babu, M. T.; Dineshkumar, P. K.

    2017-09-01

    Mudbanks (MBs) are a unique natural phenomenon, and form along the southwest coast of India during the southwest monsoon. They are characterized by a calm-water region, bordered by a rough sea. In order to quantify the wave energy dissipation, wave data were collected at two water depths (15 m and 7 m) before and during the period of formation of MBs off Alappuzha, Kerala. The observations indicate that MBs exist even in deeper water beyond 15 m water depth, contrary to earlier findings that they only form in depths of 0-5 m. The analysis showed 65-70% wave height attenuation. As spectral density evolves with shoaling, energy dissipation was examined using the concept of wave energy flux. The combination of high frequency dissipation and nonlinear energy transfer from higher-frequency to low-frequency waves resulted in a reduction of energy across a wide frequency range. The WAVEWATCH III® (WW3) model with wave-mud interaction physics was used to capture the signature of wave energy dissipation due to MBs. The accuracy of prediction of significant wave heights (Hs) of the WW3 model was verified using Hs of measured waves and ERA- Interim (ECMWF Reanalysis Interim data). The model accurately reproduced both the wave heights in the MB region and their general characteristics. The measurements and model results complement each other in explaining changes associated with an apparent shift of the MBs.

  1. 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.

  2. 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.

  3. 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.

  4. Effects of a Single Open Joint on Energy Transmission Coefficients of Stress Waves with Different Waveforms

    NASA Astrophysics Data System (ADS)

    Wang, Weihua; Hao, Hong; Li, Xibing; Yan, Zhe; Gong, Fengqiang

    2015-09-01

    Open joints have significantly different effects on stress wave propagation across them as compared to closed and filled joints. In the present study, a theoretical model is developed based on the analysis of interaction process between stress waves and a single open joint. The analytical solutions to the energy transmission coefficient are mathematically derived for stress waves across an open joint. Parametric studies are conducted to evaluate the effects of various parameters on the energy transmission coefficient. It is found that the energy transmission coefficient follows a similar trend for all types of stress waves, but stress waves with different waveforms have different values. The energy transmission coefficient increases with the increase in the wave amplitude and duration, but decreases with the gap width. It also increases at the outset, and then decreases gradually with the increase in the incident angle for rectangle, symmetric triangle and ascending triangle waves, but it decreases with the incident angle for sine and descending triangle waves. Furthermore, different-shaped stress waves have different critical gap widths for wave transmission. The optimal incident angle and the critical gap width increase as the wave duration increases, but the critical stress amplitude decreases.

  5. 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.

  6. Study of Ocean Bottom Interactions with Acoustic Waves by a New Elastic Wave Propagation Algorithm and an Energy Flow Analysis Technique

    DTIC Science & Technology

    2016-06-07

    Study Of Ocean Bottom Interactions With Acoustic Waves By A New Elastic Wave Propagation Algorithm And An Energy Flow Analysis Technique Ru-Shan Wu...imaging to study the wave/sea-bottom interaction, energy partitioning, scattering mechanism and other problems that are crucial for many ocean bottom...Elastic Wave Propagation Algorithm And An Energy Flow Analysis Technique 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR

  7. An oscillating wave energy converter with nonlinear snap-through Power-Take-Off systems in regular waves

    NASA Astrophysics Data System (ADS)

    Zhang, Xian-tao; Yang, Jian-min; Xiao, Long-fei

    2016-07-01

    Floating oscillating bodies constitute a large class of wave energy converters, especially for offshore deployment. Usually the Power-Take-Off (PTO) system is a directly linear electric generator or a hydraulic motor that drives an electric generator. The PTO system is simplified as a linear spring and a linear damper. However the conversion is less powerful with wave periods off resonance. Thus, a nonlinear snap-through mechanism with two symmetrically oblique springs and a linear damper is applied in the PTO system. The nonlinear snap-through mechanism is characteristics of negative stiffness and double-well potential. An important nonlinear parameter γ is defined as the ratio of half of the horizontal distance between the two springs to the original length of both springs. Time domain method is applied to the dynamics of wave energy converter in regular waves. And the state space model is used to replace the convolution terms in the time domain equation. The results show that the energy harvested by the nonlinear PTO system is larger than that by linear system for low frequency input. While the power captured by nonlinear converters is slightly smaller than that by linear converters for high frequency input. The wave amplitude, damping coefficient of PTO systems and the nonlinear parameter γ affect power capture performance of nonlinear converters. The oscillation of nonlinear wave energy converters may be local or periodically inter well for certain values of the incident wave frequency and the nonlinear parameter γ, which is different from linear converters characteristics of sinusoidal response in regular waves.

  8. 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.

  9. 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.

  10. Dispersion energy analysis of Rayleigh and Love waves in non-layered earth models

    NASA Astrophysics Data System (ADS)

    Mi, B.; Xia, J.; Shen, C.

    2016-12-01

    Surface-wave analysis methods have been effectively and widely used to determine shear (S) wave velocity. Dispersive curves extracted according to the dispersion energy are the basis for surface-wave analysis. The traditional surface-wave analysis method is a 1D approach because the inverted S-wave velocity profiles from surface waves are based on the assumption of horizontally layered earth model. In 2D environments, it can cause perturbations on the observed phase velocity of surface waves if the wave path is horizontally heterogeneous. In the real world applications of surface waves for the lateral variation reconstruction, it is very important to assess the errors of phase velocities that could be introduced because of the presence of lateral variations. We analyze the dispersion energy of Rayleigh and Love waves in non-layered earth models with a fault or a slope based on finite-difference modeling. Synthetic multichannel records are simulated with a finite-difference method for the non-layered earth models and dispersion images are generated by the high-resolution linear Radon transformation (LRT). We compare the dispersion energy with theoretical dispersion curves calculated by the Knopoff method. Errors of phase velocities with different receiver spread lengths are analyzed quantitatively. Results demonstrate that the extracted dispersion curve is an average result of the subsurface covered by the receiver spread length. To select the optimal receiver spread length is imperative for the investigation of lateral variation with surface-wave methods.

  11. 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.

  12. 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.

  13. A Novel True Triaxial Apparatus to Study the Geomechanical and Fluid Flow Aspects of Energy Exploitations in Geological Formations

    NASA Astrophysics Data System (ADS)

    Li, Minghui; Yin, Guangzhi; Xu, Jiang; Li, Wenpu; Song, Zhenlong; Jiang, Changbao

    2016-12-01

    Fluid-solid coupling investigations of the geological storage of CO2, efficient unconventional oil and natural gas exploitations are mostly conducted under conventional triaxial stress conditions ( σ 2 = σ 3), ignoring the effects of σ 2 on the geomechanical properties and permeability of rocks (shale, coal and sandstone). A novel multi-functional true triaxial geophysical (TTG) apparatus was designed, fabricated, calibrated and tested to simulate true triaxial stress ( σ 1 > σ 2 > σ 3) conditions and to reveal geomechanical properties and permeability evolutions of rocks. The apparatus was developed with the capacity to carry out geomechanical and fluid flow experiments at high three-dimensional loading forces and injection pressures under true triaxial stress conditions. The control and measurement of the fluid flow with effective sealing of rock specimen corners were achieved using a specially designed internally sealed fluid flow system. To validate that the apparatus works properly and to recognize the effects of each principal stress on rock deformation and permeability, stress-strain and permeability experiments and a hydraulic fracturing simulation experiment on shale specimens were conducted under true triaxial stress conditions using the TTG apparatus. Results show that the apparatus has advantages in recognizing the effects of σ 2 on the geomechanical properties and permeability of rocks. Results also demonstrate the effectiveness and reliability of the novel TTG apparatus. The apparatus provides a new method of studying the geomechanical properties and permeability evolutions of rocks under true triaxial stress conditions, promoting further investigations of the geological storage of CO2, efficient unconventional oil and gas exploitations.

  14. Weak turbulant theory estimation for non-linear energy, wave action and momentum fluxes in wind wave spectrum

    NASA Astrophysics Data System (ADS)

    Lavrenov, I.

    2003-04-01

    Direct numerical simulations of the Hasselmann kinetic equation for gravity waves in water surface confirms basic predictions of the weak-turbulent theory. Three different stages can be defined in the wave spectrum evolution.. At the first stage the spectrum unstable growth is observed within the range of the external force input. High frequency spectrum development is observed at the second stage of spectrum evolution. The frequency spectrum is becoming larger within high frequency range and a spectral growth is penetrated to a larger frequency range. After that the spectrum remains almost constant at high frequency range. In both isotropic and non-isotropic cases the spectra are found out to be close to the Zakharov-Filonenko spectrum pow(w,-4) not only in the universal range, but in the range of wave energy input. Formation of this asymptotic spectrum happens explosively. The third stage of spectrum evolution is revealed for a larger time period. It is characterized by a slow spectrum evolution into a low frequency range. The spectrum value becomes larger penetrating to a smaller frequency range with decreasing speed in accordance with experimental data. In low frequency range a power spectrum is revealed for both isotropic and non-isotropic cases with the spectra close to the Zakharov-Zaslavskii spectrum pow(w,-11/3). Main energy flux is directed to the high frequency range. Its value makes up 77 per cent of total value of wave energy input coming from external source. Main wave action flux is directed to low frequency range. Its relative value is equal to 75 per cents of total wave action flux input. 25 per cents of wave action is directed to high frequency range. Almost all wave momentum (up to 98 per cents) is directed to high frequency range. The investigations are supported by the Grants: RFBR 01-05-64846, and INTAS-(99)-666, INTAS - (01)-234, INTAS-(01)-2156.

  15. 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

  16. 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.

  17. 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.

  18. Wave energy patterns of counterpulsation: a novel approach with wave intensity analysis.

    PubMed

    Lu, Pong-Jeu; Yang, Chi-Fu Jeffrey; Wu, Meng-Yu; Hung, Chun-Hao; Chan, Ming-Yao; Hsu, Tzu-Cheng

    2011-11-01

    In counterpulsation, diastolic augmentation increases coronary blood flow and systolic unloading reduces left ventricular afterload. We present a new approach with wave intensity analysis to revisit and explain counterpulsation principles. In an acute porcine model, a standard intra-aortic balloon pump was placed in descending aorta in 4 pigs. We measured pressure and velocity with probes in left anterior descending artery and aorta during and without intra-aortic balloon pump assistance. Wave intensities of aortic and left coronary waves were derived from pressure and flow measurements with synchronization correction. We identified predominating waves in counterpulsation. In the aorta, during diastolic augmentation, intra-aortic balloon inflation generated a backward compression wave, with a "pushing" effect toward the aortic root that translated to a forward compression wave into coronary circulation. During systolic unloading, intra-aortic balloon pump deflation generated a backward expansion wave that "sucked" blood from left coronary bed into the aorta. While this backward expansion wave translated to reduced left ventricular afterload, the "sucking" effect resulted in left coronary blood steal, as demonstrated by a forward expansion wave in left anterior descending coronary flow. The waves were sensitive to inflation and deflation timing, with just 25 ms delay from standard deflation timing leading to weaker forward expansion wave and less coronary regurgitation. Intra-aortic balloon pumps generate backward-traveling waves that predominantly drive aortic and coronary blood flow during counterpulsation. Wave intensity analysis of arterial circulations may provide a mechanism to explain diastolic augmentation and systolic unloading of intra-aortic balloon pump counterpulsation. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  19. 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.

  20. 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

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

    USGS Publications Warehouse

    Sallenger, A.H.; 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

  2. 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.

  3. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. 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

  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. H-He elastic scattering at low energies: Contribution of nonzero partial waves

    SciTech Connect

    Sinha, Prabal K.; Ghosh, A.S.

    2005-01-01

    The present study reports the nonzero partial wave elastic cross sections together with s-wave results for the scattering of an antihydrogen atom off a gaseous helium target at thermal energies (up to 10{sup -2} a.u.). We have used a nonadiabatic atomic orbital method having different basis sets to investigate the system. The consideration of all the significant partial waves (up to J=24) reduces the oscillatory nature present in the individual partial wave cross section. The added elastic cross section is almost constant up to 10{sup -7} a.u. and then decreases steadily and very slowly with increasing energy.

  7. Low-energy D-wave positronium-hydrogen scattering

    NASA Astrophysics Data System (ADS)

    Woods, Denton; van Reeth, P.; Ward, S. J.

    2014-03-01

    We are investigating the four-body Coulomb process of positronium-hydrogen (Ps-H) scattering below the Ps(n=2) excitation threshold using the Kohn variational method and variants. Our Ps-H 1 D -wave phase shifts compare reasonably well with the close-coupling results, but our 3 D -wave phase shifts are appreciably lower. In an attempt to improve the accuracy of these, we are employing a sectors-based approach and the modification of the short-range Hylleraas terms with an exponential in the r12 coordinate. We are investigating the use of the Born approximation for higher partial waves. We plan also to present our latest S-wave and P-wave results using the Kohn variational method. S.J. Ward acknowledges support from NSF under grant no. PHYS-968638.

  8. Marine Planning for Potential Wave Energy Facility Placement Amongst a Crowded Sea of Existing Resource Uses

    NASA Astrophysics Data System (ADS)

    Feist, B. E.; Fuller, E.; Plummer, M. L.

    2016-12-01

    Conversion to renewable energy sources is a logical response to increasing pressure to reduce greenhouse gas emissions. Ocean wave energy is the least developed renewable energy source, despite having the highest energy per unit area. While many hurdles remain in developing wave energy, assessing potential conflicts and evaluating tradeoffs with existing uses is essential. Marine planning encompasses a broad array of activities that take place in and affect large marine ecosystems, making it an ideal tool for evaluating wave energy resource use conflicts. In this study, we focus on the potential conflicts between wave energy conversion (WEC) facilities and existing marine uses in the context of marine planning, within the California Current Large Marine Ecosystem. First, we evaluated wave energy facility development using the Wave Energy Model (WEM) of the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) toolkit. Second, we ran spatial analyses on model output to identify conflicts with existing marine uses including AIS based vessel traffic, VMS and observer based measures of commercial fishing effort, and marine conservation areas. We found that regions with the highest wave energy potential were distant from major cities and that infrastructure limitations (cable landing sites) restrict integration with existing power grids. We identified multiple spatial conflicts with existing marine uses; especially shipping vessels and various commercial fishing fleets, and overlap with marine conservation areas varied by conservation designation. While wave energy generation facilities may be economically viable in the California Current, this viability must be considered within the context of the costs associated with conflicts that arise with existing marine uses. Our analyses can be used to better inform placement of WEC devices (as well as other types of renewable energy facilities) in the context of marine planning by accounting for economic tradeoffs

  9. 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.

  10. 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.

  11. Laboratory air-entraining breaking waves: Imaging visible foam signatures to estimate energy dissipation

    NASA Astrophysics Data System (ADS)

    Callaghan, A. H.; Deane, G. B.; Stokes, M. D.

    2016-11-01

    Oceanic air-entraining breaking waves fundamentally influence weather and climate through bubble-mediated ocean-atmosphere exchanges, and influence marine engineering design by impacting statistics of wave heights, crest heights, and wave loading. However, estimating individual breaking wave energy dissipation in the field remains a fundamental problem. Using laboratory experiments, we introduce a new method to estimate energy dissipation by individual breaking waves using above-water images of evolving foam. The data show the volume of the breaking wave two-phase flow integrated in time during active breaking scales linearly with wave energy dissipated. To determine the volume time-integral, above-water images of surface foam provide the breaking wave timescale and horizontal extent of the submerged bubble plume, and the foam decay time provides an estimate of the bubble plume penetration depth. We anticipate that this novel remote sensing method will improve predictions of air-sea exchanges, validate models of wave energy dissipation, and inform ocean engineering design.

  12. 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

  13. Omni-directional lens for structure-borne wave focusing and energy harvesting

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    In this paper, a Luneburg lens is explored for omnidirectional structure-borne wave focusing both numerically and experimentally. The proposed lens is formed by radially distributed blind holes with different diameters based on the gradient index phononic crystal theory. The radial orientation and diameter of the holes are determined according to the refractive index distribution which is guided by finite-element simulations of the lowest asymmetric mode Lamb wave band diagrams. According to this design, the wave travels slower at the center of the lens and converges at the focal spot which is on the circular lens boundary. Wave simulations are performed in COMSOL Multiphysics® under plane wave excitation from a line source and wave focusing is observed at the opposite border of the lens with respect to the incoming wave direction. Experimentally measured wave fields with a scanning laser vibrometer successfully validate simulated wave focusing. Furthermore, omnidirectionality is verified by testing the lens under plane wave excitation from different directions. With piezoelectric energy harvesters located at the boundary of the Luneburg lens substantially larger power output can be obtained as compared to the baseline case of energy harvesting without the lens on the uniform plate counterpart for the same incident plane wave excitation.

  14. 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…

  15. 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…

  16. Effect of pressurization on helical guided wave energy velocity in fluid-filled pipes.

    PubMed

    Dubuc, Brennan; Ebrahimkhanlou, Arvin; Salamone, Salvatore

    2017-03-01

    The effect of pressurization stresses on helical guided waves in a thin-walled fluid-filled pipe is studied by modeling leaky Lamb waves in a stressed plate bordered by fluid. Fluid pressurization produces hoop and longitudinal stresses in a thin-walled pipe, which corresponds to biaxial in-plane stress in a plate waveguide model. The effect of stress on guided wave propagation is accounted for through nonlinear elasticity and finite deformation theory. Emphasis is placed on the stress dependence of the energy velocity of the guided wave modes. For this purpose, an expression for the energy velocity of leaky Lamb waves in a stressed plate is derived. Theoretical results are presented for the mode, frequency, and directional dependent variations in energy velocity with respect to stress. An experimental setup is designed for measuring variations in helical wave energy velocity in a thin-walled water-filled steel pipe at different levels of pressure. Good agreement is achieved between the experimental variations in energy velocity for the helical guided waves and the theoretical leaky Lamb wave solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. 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.

  18. Influence of deposited energy on shock wave induced by underwater pulsed current discharge

    NASA Astrophysics Data System (ADS)

    Li, Xian-Dong; Liu, Yi; Liu, Si-Wei; Li, Zhi-Yuan; Zhou, Gu-Yue; Li, Hua; Lin, Fu-Chang; Pan, Yuan

    2016-10-01

    In this paper, an integrated experimental system is established to study the influence of deposited energy on the intensity of the shock wave induced by underwater pulse discharge. Considering the time varying behavior of the arc, the calculation methods of the deposited energy into the plasma channel and the average arc resistance are proposed and presented. The effect of the breakdown process on the deposited energy and the shock wave is analyzed. It can be concluded that the shock wave intensity can be improved by depositing more energy in the first half oscillation period and increasing the arc resistance. It is also found that the energy deposition and the shock wave intensity are significantly influenced by the breakdown time delay and the shape of the initial plasma channel.

  19. Generation of Alfvén wave energy during magnetic reconnection in Hall MHD

    NASA Astrophysics Data System (ADS)

    Li, Lingjie; Ma, Zhiwei; Wang, Licheng

    2017-10-01

    The effect of the reconnection rate on the generation of Alfvén wave energy is systematically investigated using Hall magnetohydrodynamics (MHD). It is well known that a decrease in magnetic energy is proportional to the reconnection rate. It is found that an instantaneous increase in Alfvén wave energy in unit Alfvén time is the square dependence on the reconnection rate. The converted Alfvén wave energy is strongly enhanced due to the large increase in the reconnection rate in Hall MHD. For solar-terrestrial plasmas, the maximum converted Alfvén wave energy in unit Alfvén time with the Hall effect can be over 50 times higher than that without the Hall effect during magnetic reconnection.

  20. 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.

  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. 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.

  3. Thermal and Behavioral Effects of Exposure to 30 kW, 95-GHz Millimeter Wave Energy

    DTIC Science & Technology

    2017-05-04

    AFRL-RH-FS-TR-2017-0016 Thermal and Behavioral Effects of Exposure to 30-kW, 95-GHz Millimeter Wave Energy James E. Parker Eric...30-kW, 95-GHz Millimeter Wave Energy " LELAND JOHNSON, DR-III, DAF Contract Monitor Radio Frequency Bioeffects Branch STEPHANIE A. MILLER, DRIV, DAF...CONTRACT NUMBER FA8650-13-D-6368-0007 Thermal and Behavioral Effects of Exposure to 30-kW, 95-GHz Millimeter Wave Energy 5b. GRANT NUMBER N/A

  4. 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.

  5. 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

  6. 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

  7. Unusual energy properties of leaky backward Lamb waves in a submerged plate.

    PubMed

    Nedospasov, I A; Mozhaev, V G; Kuznetsova, I E

    2017-05-01

    It is found that leaky backward Lamb waves, i.e. waves with negative energy-flux velocity, propagating in a plate submerged in a liquid possess extraordinary energy properties distinguishing them from any other type of waves in isotropic media. Namely, the total time-averaged energy flux along the waveguide axis is equal to zero for these waves due to opposite directions of the longitudinal energy fluxes in the adjacent media. This property gives rise to the fundamental question of how to define and calculate correctly the energy velocity in such an unusual case. The procedure of calculation based on incomplete integration of the energy flux density over the plate thickness alone is applied. The derivative of the angular frequency with respect to the wave vector, usually referred to as the group velocity, happens to be close to the energy velocity defined by this mean in that part of the frequency range where the backward mode exists in the free plate. The existence region of the backward mode is formally increased for the submerged plate in comparison to the free plate as a result of the liquid-induced hybridization of propagating and nonpropagating (evanescent) Lamb modes. It is shown that the Rayleigh's principle (i.e. equipartition of total time-averaged kinetic and potential energies for time-harmonic acoustic fields) is violated due to the leakage of Lamb waves, in spite of considering nondissipative media.

  8. Combining Wind and Wave Energy in Offshore Power Plants to Reduce Variability in Electrical Generation

    NASA Astrophysics Data System (ADS)

    Stoutenburg, E.

    2008-12-01

    While wave energy is primarily a wind driven phenomenon, at a particular location and time the energy levels in the wind and waves may be different. The correlation between wind and wave energy is sufficiently weak that combining the two energy sources in a collocated offshore power plant reduces the variability in electrical generation. A preliminary examination of offshore locations along the west coast of the U.S. using buoy data shows two advantages of combining the two energy sources: 1) the number of hours of no power generation in a given year is significantly decreased, which reduces the intermittency of the power plant; 2) a decrease in the variability of the generation curve, which reduces the drops and surges of voltage at the grid interconnection point. The power generation curves for the hypothetical combined wind and wave offshore power plants use atmospheric conditions, wind speed, and wave statistics collected by NOAA buoys, and a common commercial offshore wind turbine model paired with a wave energy convertor in early commercial development in a reasonable array configuration. The hypothetical offshore power plants are located in areas with both a quality wind and wave resource near existing or feasible transmission corridors. Multiple locations along the west coast of the U.S. are used to demonstrate this reduction in power variability and intermittency.

  9. 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...

  10. On the modifications of near-inertial waves at fronts: implications for energy transfer across scales

    NASA Astrophysics Data System (ADS)

    Thomas, Leif N.

    2017-10-01

    In the ocean, wind-generated kinetic energy (KE) manifests itself primarily in balanced currents and near-inertial waves. The dynamics of these flows is strongly constrained by the Earth's rotation, causing the KE in balanced currents to follow an inverse cascade but also preventing wave-wave interactions from fluxing energy in the near-inertial band to lower frequencies and higher vertical wavenumbers. How wind-generated KE is transferred to small-scale turbulence and dissipated is thus a non-trivial problem. This article presents a review of recent theoretical calculations and numerical simulations that demonstrate how some surprising modifications to internal wave physics by the lateral density gradients present at ocean fronts allow for strong interactions between balanced currents and near-inertial waves that ultimately result in energy loss for both types of motion.

  11. On the modifications of near-inertial waves at fronts: implications for energy transfer across scales

    NASA Astrophysics Data System (ADS)

    Thomas, Leif N.

    2017-08-01

    In the ocean, wind-generated kinetic energy (KE) manifests itself primarily in balanced currents and near-inertial waves. The dynamics of these flows is strongly constrained by the Earth's rotation, causing the KE in balanced currents to follow an inverse cascade but also preventing wave-wave interactions from fluxing energy in the near-inertial band to lower frequencies and higher vertical wavenumbers. How wind-generated KE is transferred to small-scale turbulence and dissipated is thus a non-trivial problem. This article presents a review of recent theoretical calculations and numerical simulations that demonstrate how some surprising modifications to internal wave physics by the lateral density gradients present at ocean fronts allow for strong interactions between balanced currents and near-inertial waves that ultimately result in energy loss for both types of motion.

  12. 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.

  13. Laboratory Study of surface-gravity wave energy dissipation due to breaking.

    NASA Astrophysics Data System (ADS)

    Savelyev, I.; Donelan, M.; Haus, B.; Slinn, D.

    2006-12-01

    Detailed quantitative analysis of wave energy dissipation is required for air-sea interaction modeling. The main mechanism of wave energy dissipation - wave breaking - is poorly studied because of the lack of theoretical and experimental techniques needed for such complex phenomena. In the University of Miami an Air-Sea Interaction Sea-Water Tank was constructed to study processes on air- sea interface using the most modern experimental techniques. That includes wind tunnel (0-25 m/s); programmable wave-maker; water temperature control; water current control; turbulence instrumentation including: hot-film anemometry; particle image velocimetry; wave instrumentation including: laser slope and height gauges; capacitance height gauges; two-dimensional slope-imaging devices, etc. Using these techniques, the fine structure of breaking waves was studied. In order for phenomena to be reproducible, a breaking wave was created by a paddle using a `wave focusing' technique with no wind forcing. Three dimensional velocity vectors in the vertical plane were obtained with 1 mm resolution. Experimental results were compared with existing models, such as direct numerical simulation and an exactly solved linear problem with similar boundary and initial conditions. Turbulent components of water motion velocities during wave breaking were separated and the turbulent kinetic energy distribution and dissipation dynamics was studied.

  14. Wave energy resource of Brazil: An analysis from 35 years of ERA-Interim reanalysis data

    PubMed Central

    Araújo, Alex Maurício

    2017-01-01

    This paper presents a characterization of the wave power resource and an analysis of the wave power output for three (AquaBuoy, Pelamis and Wave Dragon) different wave energy converters (WEC) over the Brazilian offshore. To do so it used a 35 years reanalysis database from the ERA-Interim project. Annual and seasonal statistical analyzes of significant height and energy period were performed, and the directional variability of the incident waves were evaluated. The wave power resource was characterized in terms of the statistical parameters of mean, maximum, 95th percentile and standard deviation, and in terms of the temporal variability coefficients COV, SV e MV. From these analyses, the total annual wave power resource available over the Brazilian offshore was estimated in 89.97 GW, with largest mean wave power of 20.63 kW/m in the southernmost part of the study area. The analysis of the three WEC was based in the annual wave energy output and in the capacity factor. The higher capacity factor was 21.85% for Pelamis device at the southern region of the study area. PMID:28817731

  15. Multifractal energy exchange between gravity waves and turbulence in an upper tropospheric front

    NASA Astrophysics Data System (ADS)

    Koch, Steven

    2014-05-01

    Intermittent generation of strong turbulence measured by reconnaissance aircraft occurred in association with a wide spectrum of upward propagating gravity waves above the core of an upper level jet stream. The turbulence generation process could be described as an energy cascade process, initiated as gravity-inertia waves were produced in a region of diagnosed unbalanced upper-level frontogenesis near a tropopause fold. High resolution numerical weather prediction model forecasts produced bimodal waves with dominant wavelengths of 120-216 km and 1-20 km, the latter of which perturbed the atmosphere to create conditions conducive to turbulence generation. Cross spectral, wavelet transformation, and polarization analysis of the in situ aircraft data allowed unambiguous determination of the presence of the spectrum of gravity waves, reconstruction of the waves' evolving character, and identification of intermittent wave packets. Introduction of wavelet cross spectrum into the Stokes parameter theory shed light on how turbulence production was intimately related to increasing levels of polarization, only to be followed by sudden reduction of polarization as turbulence arose. Wavelet and structure function analysis indicated that episodes of high turbulent kinetic energy were the result of upscale feedback effects ("inverse energy cascade" processes linked to wave breaking). The bi-fractal nature of the gravity waves and turbulence suggest new approaches for parameterizing sub grid-scale effects caused by the interaction of waves and turbulence in numerical models.

  16. Wave energy resource of Brazil: An analysis from 35 years of ERA-Interim reanalysis data.

    PubMed

    Espindola, Rafael Luz; Araújo, Alex Maurício

    2017-01-01

    This paper presents a characterization of the wave power resource and an analysis of the wave power output for three (AquaBuoy, Pelamis and Wave Dragon) different wave energy converters (WEC) over the Brazilian offshore. To do so it used a 35 years reanalysis database from the ERA-Interim project. Annual and seasonal statistical analyzes of significant height and energy period were performed, and the directional variability of the incident waves were evaluated. The wave power resource was characterized in terms of the statistical parameters of mean, maximum, 95th percentile and standard deviation, and in terms of the temporal variability coefficients COV, SV e MV. From these analyses, the total annual wave power resource available over the Brazilian offshore was estimated in 89.97 GW, with largest mean wave power of 20.63 kW/m in the southernmost part of the study area. The analysis of the three WEC was based in the annual wave energy output and in the capacity factor. The higher capacity factor was 21.85% for Pelamis device at the southern region of the study area.

  17. Impact of Parameterized Internal Wave Drag on the Semidiurnal Energy Balancein a Global Ocean Circulation Model

    DTIC Science & Technology

    2016-04-12

    Impact of Parameterized Internal Wave Drag on the Semidiurnal Energy Balance in a Global Ocean Circulation Model* MAARTENC. BUIJSMAN,1 JOSEPHK...of Southern Mississippi, Stennis Space Center, Mississippi #University of Michigan, Ann Arbor, Michigan @Center for Ocean -Atmospheric Prediction...parameterized linear internal wave drag on the semidiurnal barotropic and baroclinic energetics of a realistically forced, three-dimensional global ocean

  18. 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.

  19. 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.

  20. 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.

    2017-05-01

    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.

  1. Beyond H₂: exploiting 2-hydroxypyridine as a design element from [Fe]-hydrogenase for energy-relevant catalysis.

    PubMed

    Moore, Cameron M; Dahl, Eric W; Szymczak, Nathaniel K

    2015-04-01

    The unique primary and secondary coordination environments surrounding the active site of hydrogenase enzymes play a crucial role in H2 activation and transfer reactions. [Fe]-hydrogenase contains a 2-hydroxypyridine ligand motif, and many researchers have incorporated this design element into synthetic catalysts. Transition metal complexes supported by 2-hydroxypyridine scaffolds are catalysts for chemical conversion schemes relevant to alternative energy applications and, in addition to hydrogenase-type reactivity, find new uses in other chemical domains. In this review, the current status of 2-hydroxypyridine-derived catalysts is described with an emphasis on design features that lead to lower energy catalytic pathways. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Frequency dependent power and energy flux density equations of the electromagnetic wave

    NASA Astrophysics Data System (ADS)

    Muhibbullah, M.; Haleem, Ashraf M. Abdel; Ikuma, Yasuro

    The calculation of the power and energy of the electromagnetic wave is important for numerous applications. There are some equations to compute the power and energy density of the electromagnetic wave radiation. For instance, the Poynting vector is frequently used to calculate the power density. However those including the Poynting vector are not perfect to represent the actual values because the equations are frequency independent. In the present study we have derived the frequency-dependent equations to calculate the power and energy flux density of the electromagnetic wave by help of the classical electromagnetic theories. It is seems that the Poynting vector with a certain electric and magnetic fields is correct only for a specific frequency. However our equations are perfect to calculate the values of the power and energy flux density for all frequencies of the electromagnetic radiation. The equations may help to develop the applications of the electromagnetic wave radiation.

  3. 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.

  4. 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.

  5. An effective noise reduction method for multi-energy CT images that exploit spatio-spectral features.

    PubMed

    Li, Zhoubo; Leng, Shuai; Yu, Lifeng; Manduca, Armando; McCollough, Cynthia H

    2017-05-01

    To develop and evaluate an image-domain noise reduction method for multi-energy CT (MECT) data. Multi-Energy Non-Local Means (MENLM) is a technique that uses the redundant information in MECT images to achieve noise reduction. In this method, spatio-spectral features are used to determine the similarity between pixels, making the similarity evaluation more robust to image noise. The performance of this MENLM filter was tested on images acquired on a whole-body research photon counting CT system. The impact of filtering on image quality was quantitatively evaluated in phantom studies in terms of image noise level (standard deviation of pixel values), noise power spectrum (NPS), in-plane and cross-plane spatial resolution, CT number accuracy, material decomposition performance, and subjective low-contrast spatial resolution using the American College of Radiology (ACR) CT accreditation phantom. Clinical feasibility was assessed by performing MENLM on contrast-enhanced swine images and unenhanced cadaver head images using clinically relevant doses and dose rates. The phantom studies demonstrated that the MENLM filter reduced noise substantially and still preserved the shape and peak frequency of the NPS. With 80% noise reduction, MENLM filtering caused no degradation of high-contrast spatial resolution, as illustrated by the modulation transfer function (MTF) and slice sensitivity profile (SSP). CT number accuracy was also maintained for all energy channels, demonstrating that energy resolution was not affected by filtering. Material decomposition performance was improved with MENLM filtering. The subjective evaluation using the ACR phantom demonstrated an improvement in low-contrast performance. MENLM achieved effective noise reduction in both contrast-enhanced swine images and unenhanced cadaver head images, resulting in improved detection of subtle vascular structures and the differentiation of white/gray matter. In MECT, MENLM achieved around 80% noise reduction

  6. Energy partitioning in {sup 1}S-wave electron-impact ionization of atomic hydrogen

    SciTech Connect

    Shakeshaft, Robin

    2010-03-15

    Results of calculations of the integrated cross section and the energy distribution for ionization of ground-state hydrogen by {sup 1}S-wave electron impact are presented. The breakup amplitude is expressed as a volume integral that contains an approximate final-state wave function which accounts for postcollision dynamic screening. The error in this wave function is accounted for by the response function, which is represented on a real discrete (Sturmian) basis, with its physical branch specified by the arrow of time. It is found that the energy distribution is primarily convex for impact energies from about 2 to 10 eV above threshold, and primarily flat from about 10 to 20 eV above threshold. The shape of the energy distribution appears to reflect both the competition between escape and recapture, and the substantial postcollision exchange of energy between the electrons. A rough, nonclassical criterion for predicting the curvature of the energy distribution is derived.

  7. High-energy extracorporeal shock wave therapy as a treatment for chronic noninsertional Achilles tendinopathy.

    PubMed

    Furia, John P

    2008-03-01

    High-energy extracorporeal shock wave therapy has been shown to be an effective treatment for chronic insertional Achilles tendinopathy. The results of high-energy shock wave therapy for chronic noninsertional Achilles tendinopathy have not been determined. Shock wave therapy is an effective treatment for noninsertional Achilles tendinopathy. Case control study; Level of evidence, 3. Thirty-four patients with chronic noninsertional Achilles tendinopathy were treated with a single dose of high-energy shock wave therapy (shock wave therapy group; 3000 shocks; 0.21 mJ/mm(2); total energy flux density, 604 mJ/mm(2)). Thirty-four patients with chronic noninsertional Achilles tendinopathy were treated not with shock wave therapy but with additional forms of nonoperative therapy (control group). All shock wave therapy procedures were performed using regional anesthesia. Evaluation was by change in visual analog score and by Roles and Maudsley score. One month, 3 months, and 12 months after treatment, the mean visual analog scores for the control and shock wave therapy groups were 8.4 and 4.4 (P < .001), 6.5 and 2.9 (P < .001), and 5.6 and 2.2 (P < .001), respectively. At final follow-up, the number of excellent, good, fair, and poor results for the shock wave therapy and control groups were 12 and 0 (P < .001), 17 and 9 (P < .001), 5 and 17 (P < .001), and 0 and 8 (P < .001), respectively. A chi(2) analysis revealed that the percentage of patients with excellent ("1") or good ("2") Roles and Maudsley scores, that is, successful results, 12 months after treatment was statistically greater in the shock wave therapy group than in the control group (P < .001). Shock wave therapy is an effective treatment for chronic noninsertional Achilles tendinopathy.

  8. GNSS-TEC observations of infrasound excited by a volcanic eruption: Inference of wave front geometry and acoustic wave energy

    NASA Astrophysics Data System (ADS)

    Nakashima, Y.; Aoki, Y.; Nishida, K.; Heki, K.

    2016-12-01

    Volcanic eruptions excite various oscillations depending on various factors. Very low frequency infrasound (-5 mHz) can reach the upper atmosphere and are often observed as ionospheric fluctuations. We can see three types of ionospheric disturbances excited by volcanic eruptions: (1) acoustic trap mode, (2) atmospheric internal gravity wave and (3) traveling acoustic waves come from volcanic explosion. The third one is important to improve our knowledge of acoustic energy by volcanic explosions because we cannot detect infrasound propagating upward by barometers deployed on the ground. We found ionospheric disturbances made by the Kuchinoerabujima volcano eruption on 29 May, 2015, using the GNSS-TEC method. This case is similar to the 2004 Asamayama volcano explosion, and we tried to estimate the energy of the acoustic wave. In this presentation, we will compare TEC perturbations and surface pressure changes. We use 1 Hz-sampled GEONET data from stations in Southwest Japan. Conversion from slant-TEC to vertical-TEC was done using the minimum scalloping. We used apparent velocities calculated from cross correlation function of the TEC disturbances to infer the wave front geometry. Previous studies discussed wave fronts calculated by ray-tracing. However, ray tracing may be inappropriate to such a case because it assumes very short wave length compared with the scale height. Accordingly, we estimated the incident angles from the apparent wave velocities assuming that the ionosphere is a thin layer located at 300 km above the surface. We derived incident angles, and they were similar to those we obtained by ray tracing. In addition, we found that the incident angles inferred in this way had significant dependence on azimuths. We need to find out whether it is real or an apparent phenomenon caused by stations-satellites-wave geometry. We are now trying to estimate the energy, but it varies around the estimated value for the 2004 Asama volcano case. We will consider the

  9. New Ion-Wave Path in the Energy Cascade

    SciTech Connect

    Valentini, Francesco; Califano, Francesco; Pegoraro, Francesco; Perrone, Denise; Veltri, Pierluigi

    2011-04-22

    We present the results of kinetic numerical simulations that demonstrate the existence of a novel branch of electrostatic nonlinear waves driven by particle trapping processes. These waves have an acoustic-type dispersion with phase speed comparable to the ion thermal speed and would thus be heavily Landau damped in the linear regime. At variance with the ion-acoustic waves, this novel electrostatic branch can exist at a small but finite amplitude even for low values of the electron to ion temperature ratio. Our results provide a new interpretation of observations in space plasmas, where a significant level of electrostatic activity is observed in the high frequency region of the solar-wind turbulent spectra.

  10. Spectral Characterization of the Wave Energy Resource for Puerto Rico (PR) and the United States Virgin Islands (USVI)

    NASA Astrophysics Data System (ADS)

    Garcia, C. G.; Canals, M.; Irizarry, A. A.

    2016-02-01

    Nowadays a significant amount of wave energy assessments have taken place due to the development of the ocean energy markets worldwide. Energy contained in surface gravity waves is scattered along frequency components that can be described using wave spectra. Correspondingly, characterization and quantification of harvestable wave energy is inherently dictated by the nature of the two-dimensional wave spectrum. The present study uses spectral wave data from the operational SWAN-based CariCOOS Nearshore Wave Model to evaluate the capture efficiency of multiple wave energy converters (WEC). This study revolves around accurately estimating available wave energy as a function of varying spectral distributions, effectively providing a detailed insight concerning local wave conditions for PR and USVI and the resulting available-energy to generated-power ratio. Results in particular, provide a comprehensive characterization of three years' worth of SWAN-based datasets by outlining where higher concentrations of wave energy are localized in the spectrum. Subsequently, the aforementioned datasets were processed to quantify the amount of energy incident on two proposed sites located in PR and USVI. Results were largely influenced by local trade wind activity, which drive predominant sea states, and the amount of North-Atlantic swells that propagate towards the region. Each wave event was numerically analyzed in the frequency domain to evaluate the capacity of a WEC to perform under different spectral distribution scenarios, allowing for a correlation between electrical power output and spectral energy distribution to be established.

  11. Wave energy in white dwarf atmospheres. I - Magnetohydrodynamic energy spectra for homogeneous DB and layered DA stars

    NASA Technical Reports Server (NTRS)

    Musielak, Zdzislaw E.

    1987-01-01

    The radiative damping of acoustic and MHD waves that propagate through white dwarf photospheric layers is studied, and other damping processes that may be important for the propagation of the MHD waves are calculated. The amount of energy remaining after the damping processes have occurred in different types of waves is estimated. The results show that lower acoustic fluxes should be expected in layered DA and homogeneous DB white dwarfs than had previously been estimated. Acoustic emission manifests itself in an enhancement of the quadrupole term, but this term may become comparable to or even lower than the dipole term for cool white dwarfs. Energy carried by the acoustic waves is significantly dissipated in deep photospheric layers, mainly because of radiative damping. Acoustically heated corona cannot exist around DA and DB white dwarfs in a range T(eff) = 10,000-30,000 K and for log g = 7 and 8. However, relatively hot and massive white dwarfs could be exceptions.

  12. Wave energy in white dwarf atmospheres. I - Magnetohydrodynamic energy spectra for homogeneous DB and layered DA stars

    NASA Technical Reports Server (NTRS)

    Musielak, Zdzislaw E.

    1987-01-01

    The radiative damping of acoustic and MHD waves that propagate through white dwarf photospheric layers is studied, and other damping processes that may be important for the propagation of the MHD waves are calculated. The amount of energy remaining after the damping processes have occurred in different types of waves is estimated. The results show that lower acoustic fluxes should be expected in layered DA and homogeneous DB white dwarfs than had previously been estimated. Acoustic emission manifests itself in an enhancement of the quadrupole term, but this term may become comparable to or even lower than the dipole term for cool white dwarfs. Energy carried by the acoustic waves is significantly dissipated in deep photospheric layers, mainly because of radiative damping. Acoustically heated corona cannot exist around DA and DB white dwarfs in a range T(eff) = 10,000-30,000 K and for log g = 7 and 8. However, relatively hot and massive white dwarfs could be exceptions.

  13. 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

  14. 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.

  15. Wave energy transfer in elastic half-spaces with soft interlayers.

    PubMed

    Glushkov, Evgeny; Glushkova, Natalia; Fomenko, Sergey

    2015-04-01

    The paper deals with guided waves generated by a surface load in a coated elastic half-space. The analysis is based on the explicit integral and asymptotic expressions derived in terms of Green's matrix and given loads for both laminate and functionally graded substrates. To perform the energy analysis, explicit expressions for the time-averaged amount of energy transferred in the time-harmonic wave field by every excited guided or body wave through horizontal planes and lateral cylindrical surfaces have been also derived. The study is focused on the peculiarities of wave energy transmission in substrates with soft interlayers that serve as internal channels for the excited guided waves. The notable features of the source energy partitioning in such media are the domination of a single emerging mode in each consecutive frequency subrange and the appearance of reverse energy fluxes at certain frequencies. These effects as well as modal and spatial distribution of the wave energy coming from the source into the substructure are numerically analyzed and discussed.

  16. A low-energy chilled ammonia process exploiting controlled solid formation for post-combustion CO2 capture.

    PubMed

    Sutter, Daniel; Gazzani, Matteo; Mazzotti, Marco

    2016-10-20

    A new ammonia-based process for CO2 capture from flue gas has been developed, which utilizes the formation of solid ammonium bicarbonate to increase the CO2 concentration in the regeneration section of the process. Precipitation, separation, and dissolution of the solid phase are realized in a dedicated process section, while the packed absorption and desorption columns remain free of solids. Additionally, the CO2 wash section applies solid formation to enable a reduction of the wash water consumption. A rigorous performance assessment employing the SPECCA index (Specific Primary Energy Consumption for CO2 Avoided) has been implemented to allow for a comparison of the overall energy penalty between the new process and a standard ammonia-based capture process without solid formation. A thorough understanding of the relevant solid-solid-liquid-vapor phase equilibria and an accurate modeling of them have enabled the synthesis of the process, and have inspired the development of the optimization algorithm used to screen a wide range of operating conditions in equilibrium-based process simulations. Under the assumptions on which the analysis is based, the new process with controlled solid formation achieved a SPECCA of 2.43 MJ kgCO2(-1), corresponding to a reduction of 17% compared to the process without solid formation (with a SPECCA of 2.93 MJ kgCO2(-1)). Ways forward to confirm this significant improvement, and to increase the accuracy of the optimization are also discussed.

  17. 8.4% efficient fullerene-free organic solar cells exploiting long-range exciton energy transfer.

    PubMed

    Cnops, Kjell; Rand, Barry P; Cheyns, David; Verreet, Bregt; Empl, Max A; Heremans, Paul

    2014-03-07

    In order to increase the power conversion efficiency of organic solar cells, their absorption spectrum should be broadened while maintaining efficient exciton harvesting. This requires the use of multiple complementary absorbers, usually incorporated in tandem cells or in cascaded exciton-dissociating heterojunctions. Here we present a simple three-layer architecture comprising two non-fullerene acceptors and a donor, in which an energy-relay cascade enables an efficient two-step exciton dissociation process. Excitons generated in the remote wide-bandgap acceptor are transferred by long-range Förster energy transfer to the smaller-bandgap acceptor, and subsequently dissociate at the donor interface. The photocurrent originates from all three complementary absorbing materials, resulting in a quantum efficiency above 75% between 400 and 720 nm. With an open-circuit voltage close to 1 V, this leads to a remarkable power conversion efficiency of 8.4%. These results confirm that multilayer cascade structures are a promising alternative to conventional donor-fullerene organic solar cells.

  18. A nanowire based triboelectric nanogenerator for harvesting water wave energy and its applications

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyi; Tao, Juan; Zhu, Jing; Pan, Caofeng

    2017-07-01

    The ocean wave energy is one of the most promising renewable and clean energy sources for human life, which is the so-called "Blue energy." In this work, a nanowire based triboelectric nanogenerator was designed for harvesting wave energy. The nanowires on the surface of FEP largely raise the contacting area with water and also make the polymer film hydrophobic. The output can reach 10 μ A and 200 V. When combined with a capacitor, an infrared emitter, and a receiver, a self-powered wireless infrared system is fabricated, which can be used in the fields of communication and detecting.

  19. Phononic crystal Luneburg lens for omnidirectional elastic wave focusing and energy harvesting

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

    We explore a phononic crystal Luneburg lens through design, fabrication, and analysis for omnidirectional elastic wave focusing and enhanced energy harvesting both numerically and experimentally. The proposed lens is formed using hexagonal unit cells with blind holes of different diameters, which are determined according to the Luneburg lens refractive index distribution obtained by finite-element simulations of the lowest asymmetric mode Lamb wave band structure. Wave simulations are performed numerically under plane wave excitation from a line source, and focusing is observed at the opposite border of the lens with respect to the incident wave direction. Numerically simulated elastic wave focusing results are validated through a set of experiments. Omnidirectionality is demonstrated by testing the lens under plane wave excitation for different angles of incidence. With piezoelectric energy harvesters located at the boundary of the phononic crystal Luneburg lens, more than an order of magnitude larger power output can be extracted as compared to the baseline case of energy harvesting without the lens under the same plane wave excitation.

  20. 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.

  1. 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.

  2. Group bound long waves as a source of infragravity energy in the surf zone

    NASA Astrophysics Data System (ADS)

    Masselink, Gerhard

    1995-11-01

    Measurements of water surface elevation and cross-shore currents were made under moderate-energy conditions ( Hrms = 1.1 m and Tz = 7.5 s) on a low-gradient macrotidal beach in central Queensland, Australia. The infragravity signal (<0.04 Hz) is separated into incoming and outgoing components and compared with the wind wave envelope. The variances associated with the incoming and outgoing infragravity signals are comparable and increase four- to five-fold from a water depth of around 4 m to a depth of 1 m. Cross-correlation and cross-spectral analysis indicate the presence of an incoming bound long wave (BLW) that lags approximately 5 s behind the wind wave envelope. The BLW decouples from the wind wave groups as the incident waves break. The released BLW then travels onshore through the surf zone as a free wave and reflects some distance seaward (5 m) of the shoreline. The superposition of the released BLW and the reflected leaky wave results in standing wave motion in the inner surf zone. Coherence-spectra suggest that about 40% of the incoming infragravity energy is forced by the wind wave envelope.

  3. Energy Flux and Density of Nonuniform Electromagnetic Waves with Total Reflection

    NASA Astrophysics Data System (ADS)

    Petrov, N. S.

    2014-07-01

    Analytic expressions are obtained for the energy flux and density of refracted nonuniform waves produced during total reflection at the boundary between two isotropic media for the general case of elliptically polarized incident light. The average values are determined as functions of the parameters of the adjoining media and the angle of incidence. The cases of linearly and circularly polarized incident waves are examined in detail. An explicit general expression relating the energy fl ux and density of these waves for arbitrarily polarized incident light is obtained.

  4. Analytical expressions for partial wave two-body Coulomb transition matrices at ground-state energy

    NASA Astrophysics Data System (ADS)

    Kharchenko, V. F.

    2016-11-01

    Leaning upon the Fock method of the stereographic projection of the three-dimensional momentum space onto the four-dimensional unit sphere the possibility of the analytical solving of the Lippmann-Schwinger integral equation for the partial wave two-body Coulomb transition matrix at the ground bound state energy has been studied. In this case new expressions for the partial p-, d- and f-wave two-body Coulomb transition matrices have been obtained in the simple analytical form. The developed approach can also be extended to determine analytically the partial wave Coulomb transition matrices at the energies of excited bound states.

  5. 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.

  6. 78 FR 40132 - Wave Energy Converter Prize Administration Webinar

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-03

    ... available for public review on the DOE Office of Energy Efficiency and Renewable Energy (EERE) Web site at...) deep by 15.2 m (50 ft) wide trench parallel to the long side of the south side. Webinar Discussion...

  7. 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.

  8. 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

  9. Rapid Energy Exchange Between Balanced Eddies and Near-Inertial Waves at Fronts.

    NASA Astrophysics Data System (ADS)

    Thomas, L. N.

    2016-02-01

    Inertia-gravity waves, mesoscale eddies, and density fronts are ubiquitous in the ocean. Classical theory predicts that the interaction between the fast, unbalanced waves and the slow, balanced eddies should be weak. A new theory will be described that demonstrates, however, that this interaction can be strong in regions of frontogenesis, where mesoscale strain intensifies lateral density gradients. Such frontogenetic strain leads to an exponentially fast increase in the vertical shear of the along-front geostrophic flow and a concomitant cross-front ageostrophic circulation that is vertically-sheared as well. These changes in geostrophic flow modify the polarization relation of inertia-gravity waves that are present, making their horizontal velocity rectilinear and resulting in a Reynolds stress that draws energy from the eddies. The process is most effective for near-inertial waves and for a geostrophic flow with low Richardson number. Nonetheless, even in a background flow that is initially strongly stratified, frontogenesis leads to an exponentially fast reduction in the Richardson number, facilitating a rapid energy extraction by the waves. The theory predicts that the kinetic energy transferred from eddies is ultimately lost to the unbalanced ageostrophic circulation and hence the near-inertial waves play a catalytic role in loss-of-balance. The theory is tested with numerical simulations configured with an array of barotropic eddies that strain a density front. Simulations run with and without a field of near-inertial waves are compared to isolate the wave-mean flow interactions. The modifications of the polarization relations and consequent energy exchange with the mean flow predicted by the theory are realized in the simulations. However, unlike the theory, inhomogeneities in the wave field are allowed in the simulations and are analyzed to quantify the wave-driven accelerations of the mean flow.

  10. 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.

  11. Relationship between energy deposition and shock wave phenomenon in an underwater electrical wire explosion

    NASA Astrophysics Data System (ADS)

    Han, Ruoyu; Zhou, Haibin; Wu, Jiawei; Qiu, Aici; Ding, Weidong; Zhang, Yongmin

    2017-09-01

    An experimental study of pressure waves generated by an exploding copper wire in a water medium is performed. We examined the effects of energy deposited at different stages on the characteristics of the resulting shock waves. In the experiments, a microsecond time-scale pulsed current source was used to explode a 300-μm-diameter, 4-cm-long copper wire with initial stored energies ranging from 500 to 2700 J. Our experimental results indicated that the peak pressure (4.5-8.1 MPa) and energy (49-287 J) of the shock waves did not follow a simple relationship with any electrical parameters, such as peak voltage or deposited energy. Conversely, the impulse had a quasi-linear relationship with the parameter Π. We also found that the peak pressure was mainly influenced by the energy deposited before separation of the shock wave front and the discharge plasma channel (DPC). The decay time constant of the pressure waveform was affected by the energy injection after the separation. These phenomena clearly demonstrated that the deposited energy influenced the expansion of the DPC and affected the shock wave characteristics.

  12. A time domain energy theorem for scattering of plane electromagnetic waves

    NASA Astrophysics Data System (ADS)

    de Hoop, A. T.

    1984-10-01

    A time domain analysis of the scattering problem reveals the more general conditions under which the relevant theorems in the theory of the scattering of electromagnetic waves by an obstacle of bounded extent may also hold in the time domain. The present investigation is concerned with the energy theorem for plane wave scattering. Three different kinds of time behavior are considered, taking into account transient fields, time-periodic fields, and perpetuating fields. The derived energy theorem relates the energy which is both absorbed and scattered by the object to the spherical-wave amplitude of the scattered field in the far-field region, when observed in the direction of propagation of the incident plane wave.

  13. 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.

  14. 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.

  15. Energy of hydrodynamic and magnetohydrodynamic waves with point and continuous spectra

    NASA Astrophysics Data System (ADS)

    Hirota, M.; Fukumoto, Y.

    2008-08-01

    Energy of waves (or eigenmodes) in an ideal fluid and plasma is formulated in the noncanonical Hamiltonian context. By imposing the kinematical constraint on perturbations, the linearized Hamiltonian equation provides a formal definition of wave energy not only for eigenmodes corresponding to point spectra but also for singular ones corresponding to a continuous spectrum. The latter becomes dominant when mean fields have inhomogeneity originating from shear or gradient of the fields. The energy of each wave is represented by the eigenfrequency multiplied by the wave action, which is nothing but the action variable and, moreover, is associated with a derivative of a suitably defined dispersion relation. The sign of the action variable is crucial to the occurrence of Hopf bifurcation in Hamiltonian systems of finite degrees of freedom [M. G. Krein, Dokl. Akad. Nauk SSSR, Ser. A 73, 445 (1950)]. Krein's idea is extended to the case of coalescence between point and continuous spectra.

  16. 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.

  17. 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.

  18. Multicomponent long-wave-short-wave resonance interaction system: Bright solitons, energy-sharing collisions, and resonant solitons.

    PubMed

    Sakkaravarthi, K; Kanna, T; Vijayajayanthi, M; Lakshmanan, M

    2014-11-01

    We consider a general multicomponent (2+1)-dimensional long-wave-short-wave resonance interaction (LSRI) system with arbitrary nonlinearity coefficients, which describes the nonlinear resonance interaction of multiple short waves with a long wave in two spatial dimensions. The general multicomponent LSRI system is shown to be integrable by performing the Painlevé analysis. Then we construct the exact bright multisoliton solutions by applying the Hirota's bilinearization method and study the propagation and collision dynamics of bright solitons in detail. Particularly, we investigate the head-on and overtaking collisions of bright solitons and explore two types of energy-sharing collisions as well as standard elastic collision. We have also corroborated the obtained analytical one-soliton solution by direct numerical simulation. Also, we discuss the formation and dynamics of resonant solitons. Interestingly, we demonstrate the formation of resonant solitons admitting breather-like (localized periodic pulse train) structure and also large amplitude localized structures akin to rogue waves coexisting with solitons. For completeness, we have also obtained dark one- and two-soliton solutions and studied their dynamics briefly.

  19. Novel two-stage piezoelectric-based ocean wave energy harvesters for moored or unmoored buoys

    NASA Astrophysics Data System (ADS)

    Murray, R.; Rastegar, J.

    2009-03-01

    Harvesting mechanical energy from ocean wave oscillations for conversion to electrical energy has long been pursued as an alternative or self-contained power source. The attraction to harvesting energy from ocean waves stems from the sheer power of the wave motion, which can easily exceed 50 kW per meter of wave front. The principal barrier to harvesting this power is the very low and varying frequency of ocean waves, which generally vary from 0.1Hz to 0.5Hz. In this paper the application of a novel class of two-stage electrical energy generators to buoyant structures is presented. The generators use the buoy's interaction with the ocean waves as a low-speed input to a primary system, which, in turn, successively excites an array of vibratory elements (secondary system) into resonance - like a musician strumming a guitar. The key advantage of the present system is that by having two decoupled systems, the low frequency and highly varying buoy motion is converted into constant and much higher frequency mechanical vibrations. Electrical energy may then be harvested from the vibrating elements of the secondary system with high efficiency using piezoelectric elements. The operating principles of the novel two-stage technique are presented, including analytical formulations describing the transfer of energy between the two systems. Also, prototypical design examples are offered, as well as an in-depth computer simulation of a prototypical heaving-based wave energy harvester which generates electrical energy from the up-and-down motion of a buoy riding on the ocean's surface.

  20. Energy Flux in the Cochlea: Evidence Against Power Amplification of the Traveling Wave.

    PubMed

    van der Heijden, Marcel; Versteegh, Corstiaen P C

    2015-10-01

    Traveling waves in the inner ear exhibit an amplitude peak that shifts with frequency. The peaking is commonly believed to rely on motile processes that amplify the wave by inserting energy. We recorded the vibrations at adjacent positions on the basilar membrane in sensitive gerbil cochleae and tested the putative power amplification in two ways. First, we determined the energy flux of the traveling wave at its peak and compared it to the acoustic power entering the ear, thereby obtaining the net cochlear power gain. For soft sounds, the energy flux at the peak was 1 ± 0.6 dB less than the middle ear input power. For more intense sounds, increasingly smaller fractions of the acoustic power actually reached the peak region. Thus, we found no net power amplification of soft sounds and a strong net attenuation of intense sounds. Second, we analyzed local wave propagation on the basilar membrane. We found that the waves slowed down abruptly when approaching their peak, causing an energy densification that quantitatively matched the amplitude peaking, similar to the growth of sea waves approaching the beach. Thus, we found no local power amplification of soft sounds and strong local attenuation of intense sounds. The most parsimonious interpretation of these findings is that cochlear sensitivity is not realized by amplifying acoustic energy, but by spatially focusing it, and that dynamic compression is realized by adjusting the amount of dissipation to sound intensity.

  1. Surf zone, infragravity wave energy flux, and runup in extreme conditions

    NASA Astrophysics Data System (ADS)

    Fiedler, J. W.; Brodie, K. L.; McNinch, J.; Guza, R. T.

    2014-12-01

    Waves, currents, and sand levels were observed on a 1.4 km-long cross-shore transect extending from the back beach to ~11 m water depth at Agate Beach, Oregon in Fall 2013. Wave runup and water table fluctuations on this low slope (1:80) beach were measured with a cliff-mounted scanning Lidar and buried pressure sensors. Significant wave heights at an offshore buoy in 128m depth ranged from small (0.5m) to extreme (7.5m), with peak periods between 4-22 seconds. Infragravity frequency (nominally 0.01 Hz) horizontal runup excursions exceeded 100m, and infragravity cross-shore velocity exceeded 3 m/s. Cross-shore patterns of infragravity wave energy flux, observed with seven co-located pressure and current meters, indicate 'proto-saturation' of the inner surfzone in extreme conditions. That is, the intensification of incident wave forcing (e.g. higher energy, longer swell) leads to a wider surfzone and an increase in the shoreward infragravity wave energy seaward of the surfzone, but produces more modest increases in flux in the inner surfzone, and in the runup. Nonlinear energy balances, based on the observations, show transfer of energy from sea-swell to infragravity waves, and vice-versa. The infragravity energy balance closes in cases with low energy incident sea-swell. With more energetic incident waves, there is an unexplained inner surfzone energy sink at the lowest IG frequencies (0.004-0.02 Hz). Ongoing work aims to quantify the effect on infragravity energy balances by infragravity wave breaking and bottom friction. Additionally, the estimates may be degraded by contamination with rotational velocities of surfzone eddies. Whatever the dynamical explanation, infragravity wave runup on a low slope beach in high-energy conditions is limited significantly by dissipation. The slow rate of runup increase suggests nascent, or 'proto' saturation. This work was supported by the U.S. Army Corps of Engineers.

  2. Discretized energy minimization in a wave guide with point sources

    NASA Technical Reports Server (NTRS)

    Propst, G.

    1994-01-01

    An anti-noise problem on a finite time interval is solved by minimization of a quadratic functional on the Hilbert space of square integrable controls. To this end, the one-dimensional wave equation with point sources and pointwise reflecting boundary conditions is decomposed into a system for the two propagating components of waves. Wellposedness of this system is proved for a class of data that includes piecewise linear initial conditions and piecewise constant forcing functions. It is shown that for such data the optimal piecewise constant control is the solution of a sparse linear system. Methods for its computational treatment are presented as well as examples of their applicability. The convergence of discrete approximations to the general optimization problem is demonstrated by finite element methods.

  3. Gravity wave vertical energy flux at 95 km

    NASA Astrophysics Data System (ADS)

    Jacob, P. G.; Jacka, F.

    1985-12-01

    A three-field photometer (3FP) located at Mt. Torrens near Adelaide, is capable of monitoring different airglow emissions from three spaced fields in the sky. A wheel containing up to six different narrow bandpass interference filters can be rotated, allowing each of the filters to be sequentially placed into each of the three fields. The airglow emission of interest is the 557.7 nm line which has an intensity maximum at 95 km. Each circular field of view is located at the apexes of an equilateral triangle centered on zenith with diameters of 5 km and field separations of 13 km when projected to the 95-km level. The sampling period was 30 seconds and typical data lengths were between 7 and 8 hours. The analysis and results from the interaction of gravity waves on the 557.7 nm emission layer are derived using an atmospheric model similar to that proposed by Hines (1960) where the atmosphere is assumed isothermal and perturbations caused by gravity waves are small and adiabatic, therefore, resulting in linearized equations of motion. In the absence of waves, the atmosphere is also considered stationary. Thirteen nights of quality data from January 1983 to October 1984, covering all seasons, are used in this analysis.

  4. Gravity wave vertical energy flux at 95 km

    NASA Technical Reports Server (NTRS)

    Jacob, P. G.; Jacka, F.

    1985-01-01

    A three-field photometer (3FP) located at Mt. Torrens near Adelaide, is capable of monitoring different airglow emissions from three spaced fields in the sky. A wheel containing up to six different narrow bandpass interference filters can be rotated, allowing each of the filters to be sequentially placed into each of the three fields. The airglow emission of interest is the 557.7 nm line which has an intensity maximum at 95 km. Each circular field of view is located at the apexes of an equilateral triangle centered on zenith with diameters of 5 km and field separations of 13 km when projected to the 95-km level. The sampling period was 30 seconds and typical data lengths were between 7 and 8 hours. The analysis and results from the interaction of gravity waves on the 557.7 nm emission layer are derived using an atmospheric model similar to that proposed by Hines (1960) where the atmosphere is assumed isothermal and perturbations caused by gravity waves are small and adiabatic, therefore, resulting in linearized equations of motion. In the absence of waves, the atmosphere is also considered stationary. Thirteen nights of quality data from January 1983 to October 1984, covering all seasons, are used in this analysis.

  5. Energy from Ocean Waves, River Currents, and Wind

    NASA Astrophysics Data System (ADS)

    Guha, Shyamal

    2006-03-01

    The Earth we live in is surrounded by fluids, which are in perpetual motion. The air in the atmosphere and water found in lakes, ocean, and rivers form our natural environment. Much of the fluid medium is in constant motion. The kinetic energy of this moving fluid is astronomical in magnitude. Over the years, I have considered methods of converting a fraction of the vast reserve of this kinetic energy into electro-mechanical energy. I have conceived a few schemes of such conversions. The fluids whose kinetic energy can be converted into electro-mechanical energy are the following: ocean waters, river currents and atmospheric air. In a book to be published in the spring of 2006, I have described different techniques of energy conversion. In the upcoming APS meeting, I plan to discuss some of these techniques.

  6. Energy from Ocean Waves, River Currents, and Wind

    NASA Astrophysics Data System (ADS)

    Guha, Shyamal

    2006-05-01

    The earth we live in is surrounded by fluids, which are in perpetual motion. There is air in the atmosphere, water in lakes, oceans and rivers. The air and water around us form our natural environment. Much of the fluid medium is in constant motion. The kinetic energy of this moving fluid is astronomical in magnitude. Over the years, I considered methods of converting a fraction of the vast reserve of this kinetic energy into electro-mechanical energy. I conceived a few schemes of such conversion. The fluids whose kinetic energy can be converted into electro-mechanical energy are: ocean waters, river current and atmospheric air. In a book to be published in 2006, I have described different techniques of energy conversion. In the APS meeting, I plan to discuss some of these techniques.

  7. Alaskan wave and river hydrokinetic energy resource assessment, river energy converter testing and surface debris mitigation performance

    NASA Astrophysics Data System (ADS)

    Johnson, J.; Kasper, J.; Schmid, J.; Duvoy, P.; Ravens, T. M.; Hansen, N.; Montlaur, A.

    2014-12-01

    The Alaska Hydrokinetic Energy Research Center (AHERC) is conducting a wave energy assessment study at Yakutat, Alaska, and conducting ongoing river technology studies at the Tanana River Tests Site (TRTS) at Nenana, Alaska. In Aug. 2013 an acoustic Doppler current profiler (ADCP) was deployed in 40 m of water off Cannon Beach in Yakutat, AK as part of the Yakutat area wave energy resource assessment. Over the course of the 1.5 year deployment, the ADCP will record area wave and current data in order to verify the area wave energy resource. Preliminary data analysis shows a vigorous wave field with maximum wave heights up to 16 m in Nov. 2013. In addition to the in-situ directional wave data recorded by the ADCP, a SWAN wave climatology spanning the past 20 years is being developed along with a simulation of the wave field for the near shore (5 mwave statistics provided by the ADCP. Technology studies at the TRTS include performance tests of a research debris diversion platform (RDDP) at protecting a 5 kW New Energy hydrokinetic turbine from river debris flows and to determine the effect of RDDP generated river current turbulence on turbine efficiency. Previous tests have shown that the RDDP effectively sheds debris, however, large debris objects can cause RDDP rotation about its mooring point requiring that a stable attachment between the RDDP and protected floating structure be in place to ensure that debris is diverted away from the protected structure. Performance tests of an Oceana hydrokinetic power turbine will be conducted in late August or early September, 2014 at the TRTS in realistic Alaskan river conditions of current turbulence, high sediment flow and debris. Measurements of river sediment concentration, current velocity and river stage will be made, and current turbulence will be derived. CFD simulations of the RDDP interaction with the river flow will be completed to compare current velocity and turbulence results, depending on

  8. Immediate Dose-Response Effect of High-Energy Versus Low-Energy Extracorporeal Shock Wave Therapy on Cutaneous Microcirculation.

    PubMed

    Kraemer, Robert; Sorg, Heiko; Forstmeier, Vinzent; Knobloch, Karsten; Liodaki, Eirini; Stang, Felix Hagen; Mailaender, Peter; Kisch, Tobias

    2016-12-01

    Elucidation of the precise mechanisms and therapeutic options of extracorporeal shock wave therapy (ESWT) is only at the beginning. Although immediate real-time effects of ESWT on cutaneous hemodynamics have recently been described, the dose response to different ESWT energies in cutaneous microcirculation has never been examined. Thirty-nine Sprague-Dawley rats were randomly assigned to three groups that received either focused high-energy shock waves (group A: total of 1000 impulses, 10 J) to the lower leg of the hind limb, focused low-energy shock waves (group B: total of 300 impulses, 1 J) or placebo shock wave treatment (group C: 0 impulses, 0 J) using a multimodality shock wave delivery system (Duolith SD-1 T-Top, Storz Medical, Tägerwilen, Switzerland). Immediate microcirculatory effects were assessed with the O2C (oxygen to see) system (LEA Medizintechnik, Giessen, Germany) before and for 20 min after application of ESWT. Cutaneous tissue oxygen saturation increased significantly higher after high-energy ESWT than after low-energy and placebo ESWT (A: 29.4% vs. B: 17.3% vs. C: 3.3%; p = 0.003). Capillary blood velocity was significantly higher after high-energy ESWT and lower after low-energy ESWT versus placebo ESWT (group A: 17.8% vs. group B: -22.1% vs. group C: -5.0%, p = 0.045). Post-capillary venous filling pressure was significantly enhanced in the high-energy ESWT group in contrast to the low-energy ESWT and placebo groups (group A: 25% vs. group B: 2% vs. group C: -4%, p = 0.001). Both high-energy and low-energy ESWT affect cutaneous hemodynamics in a standard rat model. High-energy ESWT significantly increases parameters of cutaneous microcirculation immediately after application, resulting in higher tissue oxygen saturation, venous filling pressure and blood velocity, which suggests higher tissue perfusion with enhanced oxygen saturation, in contrast to low-energy as well as placebo ESWT. Low-energy ESWT also increased tissue oxygen

  9. Terminal energy distribution of blast waves from bursting spheres

    NASA Technical Reports Server (NTRS)

    Adamczyk, A. A.; Strehlow, R. A.

    1977-01-01

    The calculation results for the total energy delivered to the surroundings by the burst of an idealized massless sphere containing an ideal gas are presented. The logic development of various formulas for sphere energy is also presented. For all types of sphere bursts the fraction of the total initial energy available in the sphere that is delivered to the surroundings is shown to lie between that delivered for the constant pressure addition of energy to a source region and that delivered by isentropic expansion of the sphere. The relative value of E sub/Q increases at fixed sphere pressure/surrounding pressure as sphere temperature increases because the velocity of sound increases.

  10. 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.

  11. Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter: Preprint

    SciTech Connect

    Tom, Nathan M.; Yu, Yi-Hsiang; Wright, Alan D.; Lawson, Michael

    2016-06-01

    The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.

  12. ULF Wave Electromagnetic Energy Flux into the Ionosphere: Joule Heating Implications

    NASA Astrophysics Data System (ADS)

    Hartinger, M.; Moldwin, M.; Zou, S.; Bonnell, J. W.; Angelopoulos, V.

    2014-12-01

    Ultra Low Frequency (ULF) waves - such as standing Alfven waves - are one mechanism for coupling the inner magnetosphere to the Earth's ionosphere. For example, they transfer energy from the solar wind or ring current into the Earth's ionosphere via Joule heating. In this study, we use NASA Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite data to investigate the spatial, frequency, and geomagnetic activity dependence of the ULF wave Poynting vector (electromagnetic energy flux) mapped to the ionosphere. We use these measurements to estimate Joule heating rates. We compare these rates to empirical models of Joule heating associated with large scale, static (on ULF wave timescales) current systems, finding that ULF waves usually contribute little to the global, integrated Joule heating rate. However, there are extreme cases when ULF waves make significant contributions to global Joule heating. Finally, we find ULF waves routinely make significant contributions to local Joule heating rates near the noon and midnight local time sectors, where static current systems nominally contribute less to Joule heating; the most important contributions come from lower frequency (<7 mHz) waves.

  13. Energy Transport by Propagating Alfvén Waves in Solar Flares

    NASA Astrophysics Data System (ADS)

    Reep, Jeffrey

    2017-08-01

    Magnetic reconnection generates Alfvénic waves, which carry a significant fraction of energy in a solar flare. In previous work, we showed that the dissipation of these waves due to ion-neutral collisions effectively deliver that energy to the upper chromosphere, and are capable of heating the atmosphere strongly enough to drive explosive evaporation. However, that work disregarded travel times of these waves, which is an assumption that we now correct. Using a ray tracing method, we have implemented heating by propagating Alfvénic waves into a hydrodynamics code. We validate the method against an MHD code. We examine the effects of travel times, and find that the waves are extremely efficient at heating the chromosphere, that the ionization level plays a critical role in determining the depths and rate of wave dissipation, that the first waves effectively bore a hole into the chromosphere so that any successive waves travel even deeper into the chromosphere so that the heating falls to greater depths with time, which is opposite to the behavior of an electron beam.

  14. Redistribution of energy available for ocean mixing by long-range propagation of internal waves.

    PubMed

    Alford, Matthew H

    2003-05-08

    Ocean mixing, which affects pollutant dispersal, marine productivity and global climate, largely results from the breaking of internal gravity waves--disturbances propagating along the ocean's internal stratification. A global map of internal-wave dissipation would be useful in improving climate models, but would require knowledge of the sources of internal gravity waves and their propagation. Towards this goal, I present here computations of horizontal internal-wave propagation from 60 historical moorings and relate them to the source terms of internal waves as computed previously. Analysis of the two most energetic frequency ranges--near-inertial frequencies and semidiurnal tidal frequencies--reveals that the fluxes in both frequency bands are of the order of 1 kW x m(-1) (that is, 15-50% of the energy input) and are directed away from their respective source regions. However, the energy flux due to near-inertial waves is stronger in winter, whereas the tidal fluxes are uniform throughout the year. Both varieties of internal waves can thus significantly affect the space-time distribution of energy available for global mixing.

  15. 3D-printed lens for structure-borne wave focusing and energy harvesting

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    In this paper, we explore 3D-printed Gradient-Index Phononic Crystal Lens (GRIN-PCL) for structure-borne focusing both numerically and experimentally. The proposed lens consists of an array of nylon stubs with different heights which is fabricated by 3D printing the PA2200 nylon. The orientation and height of the stubs are determined according to the hyperbolic secant gradient distribution of refractive index which is guided by finite-element simulations of the lowest asymmetric mode Lamb wave band diagrams. The fabricated lens is then bonded to an aluminum plate to focus the wave energy in the structure. The wave focusing performance is simulated in COMSOL Multiphysics® under plane wave excitation from a line source indicating that the focal points are consistent with the analytical beam trajectory results. Experiments are conducted with a scanning laser vibrometer and experimentally measured wave field successfully validates the numerical simulation of wave focusing within the 3D-printed GRIN-PCL domain. With a piezoelectric energy harvester disk located at the focal region of the GRIN-PCL larger power output is obtained as compared to the baseline case of energy harvesting without the GRIN-PCL on the uniform plate counterpart for the same incident plane wave excitation.

  16. From T-wave energy to fault parameters: empirical relationship and preliminary results from modelling

    NASA Astrophysics Data System (ADS)

    Tsang-Hin-Sun, Eve; Royer, Jean-Yves

    2015-04-01

    T-waves are acoustic waves generated by underwater events that propagate over great distances in the SOFAR channel. Their recordings proved to be very useful for monitoring seafloor tectonic activity, principally because of their low attenuation in the sound channel. Even so, determining seismic source parameters such as focal mechanism, depth or magnitude remains a topical issue. In order to investigate the possible relationship between fault parameters and the T-waves, the acoustic energy was estimated for a subset of earthquakes recorded by both hydrophones and land-based networks so their seismic source parameters are known. Variations of the acoustic source level with azimuth can be compared to seismic wave energy variations, even if such a relationship has to be demonstrated. In an attempt to investigate source radiation in the oceanic crust on T-wave generation we perform 2D numerical modelling to synthesized T-waves seismograms. Modelling was implemented using the SPECFEM2D package and realistic seismic source parameters were extracted from the GCMT database for two source types in the Indian Ocean: normal and strike slip. It seems likely that T-wave energy would show directional patterns because of source radiation anisotropy. Source effects and directivity are presented for both source types.

  17. Airborne lidar measurements of wave energy dissipation in a coral reef lagoon system

    NASA Astrophysics Data System (ADS)

    Huang, Zhi-Cheng; Reineman, Benjamin D.; Lenain, Luc; Melville, W. Kendall; Middleton, Jason H.

    2012-03-01

    Quantification of the turbulent kinetic energy dissipation rate in the water column, ɛ, is very important for assessing nutrient uptake rates of corals and therefore the health of coral reef lagoon systems. However, the availability of such data is limited. Recently, at Lady Elliot Island (LEI), Australia, we showed that there was a strong correlation between in situ measurements of surface-wave energy dissipation and ɛ. Previously, Reineman et al. (2009), we showed that a small airborne scanning lidar system could measure the surface wavefield remotely. Here we present measurements demonstrating the use of the same airborne lidar to remotely measure surface wave energy fluxes and dissipation and thereby estimate ɛ in the LEI reef-lagoon system. The wave energy flux and wave dissipation rate across the fore reef and into the lagoon are determined from the airborne measurements of the wavefield. Using these techniques, observed spatial profiles of energy flux and wave energy dissipation rates over the LEI reef-lagoon system are presented. The results show that the high lidar backscatter intensity and point density coming from the high reflectivity of the foam from depth-limited breaking waves coincides with the high wave-energy dissipation rates. Good correlations between the airborne measurements and in situ observations demonstrate that it is feasible to apply airborne lidar systems for large-scale, long-term studies in monitoring important physical processes in coral reef environments. When added to other airborne techniques, the opportunities for efficient monitoring of large reef systems may be expanded significantly.

  18. Charging System Optimization of Triboelectric Nanogenerator for Water Wave Energy Harvesting and Storage.

    PubMed

    Yao, Yanyan; Jiang, Tao; Zhang, Limin; Chen, Xiangyu; Gao, Zhenliang; Wang, Zhong Lin

    2016-08-24

    Ocean waves are one of the most promising renewable energy sources for large-scope applications due to the abundant water resources on the earth. Triboelectric nanogenerator (TENG) technology could provide a new strategy for water wave energy harvesting. In this work, we investigated the charging characteristics of utilizing a wavy-structured TENG to charge a capacitor under direct water wave impact and under enclosed ball collision, by combination of theoretical calculations and experimental studies. The analytical equations of the charging characteristics were theoretically derived for the two cases, and they were calculated for various load capacitances, cycle numbers, and structural parameters such as compression deformation depth and ball size or mass. Under the direct water wave impact, the stored energy and maximum energy storage efficiency were found to be controlled by deformation depth, while the stored energy and maximum efficiency can be optimized by the ball size under the enclosed ball collision. Finally, the theoretical results were well verified by the experimental tests. The present work could provide strategies for improving the charging performance of TENGs toward effective water wave energy harvesting and storage.

  19. All-optical NRZ-to-RZ format conversion at 10 Gbit/s with 1-to-4 wavelength multicasting exploiting cross-phase modulation & four-wave-mixing in single dispersion-flattened highly nonlinear photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Hui, Zhan-Qiang; Zhang, Bo; Zhang, Jian-Guo

    2016-04-01

    All-optical NRZ-to-RZ format conversion with a function of wavelength multicasting is proposed in this paper, which is realized by exploiting cross-phase modulation (XPM) and four-wave-mixing (FWM) in a dispersion-flattened highly nonlinear photonic crystal fiber (DF-HNL-PCF). The designed format converter is experimentally demonstrated, for which the 1-to-4 wavelength multicasting is achieved simultaneously by filtering out two FWM idler waves and both blue-chirped and red-chirped components of the broadened NRZ spectrum induced by XPM. Moreover, the wavelength tunability and dynamic characteristics of the proposed NRZ-to-RZ format converter are also exploited using the different central wavelengths of an optical clock signal and varying the input optical power at a DF-HNL-PCF in our experiment. It is shown that the designed format converter can possess a wide range of operational wavelength over 17 nm, an optimal extinction ratio of 11.6 dB, and a Q-factor of 7.1, respectively. Since the proposed scheme uses an optical fiber-based configuration and is easy for implementation, it can be very useful for future applications in advanced fiber-optic communication networks.

  20. Underwater Sound Levels at a Wave Energy Device Testing Facility in Falmouth Bay, UK.

    PubMed

    Garrett, Joanne K; Witt, Matthew J; Johanning, Lars

    2016-01-01

    Passive acoustic monitoring devices were deployed at FaBTest in Falmouth Bay, UK, a marine renewable energy device testing facility during trials of a wave energy device. The area supports considerable commercial shipping and recreational boating along with diverse marine fauna. Noise monitoring occurred during (1) a baseline period, (2) installation activity, (3) the device in situ with inactive power status, and (4) the device in situ with active power status. This paper discusses the preliminary findings of the sound recording at FabTest during these different activity periods of a wave energy device trial.

  1. The impulsive effects of momentum transfer on the dynamics of a novel ocean wave energy converter

    NASA Astrophysics Data System (ADS)

    Diamond, Christopher A.; O'Reilly, Oliver M.; Savaş, Ömer

    2013-10-01

    In a recent paper by Orazov et al. [On the dynamics of a novel ocean wave energy converter. Journal of Sound and Vibration329 (24) (2010) 5058-5069], a wave energy converter (WEC) was proposed. The converter features a mass modulation scheme and a simple model was used to examine its efficacy. The simple model did not adequately account for the momentum transfer which takes place during the mass modulation. The purpose of the present paper is to account for this transfer and to show that the WEC equipped with a novel and more general mass modulation scheme has the potential to improve its energy harvesting capabilities.

  2. Can cellulite be treated with low-energy extracorporeal shock wave therapy?

    PubMed Central

    Angehrn, Fiorenzo; Kuhn, Christoph; Voss, Axel

    2007-01-01

    The present study investigates the effects of low-energy defocused extracorporeal generated shock waves on collagen structure of cellulite afflicted skin. Cellulite measurement using high-resolution ultrasound technology was performed before and after low-energy defocused extracorporeal shock wave therapy (ESWT) in 21 female subjects. ESWT was applied onto the skin at the lateral thigh twice a week for a period of six weeks. Results provide evidence that low-energy defocused ESWT caused remodeling of the collagen within the dermis of the tested region. Improving device-parameters and therapy regimes will be essential for future development of a scientific based approach to cellulite treatment. PMID:18225463

  3. MAGNETOHYDRODYNAMIC KINK WAVES IN NONUNIFORM SOLAR FLUX TUBES: PHASE MIXING AND ENERGY CASCADE TO SMALL SCALES

    SciTech Connect

    Soler, Roberto; Terradas, Jaume

    2015-04-10

    Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar atmosphere. The propagation and damping of these waves may play relevant roles in the transport and dissipation of energy in the solar atmospheric medium. However, in the atmospheric plasma dissipation of transverse MHD wave energy by viscosity or resistivity needs very small spatial scales to be efficient. Here, we theoretically investigate the generation of small scales in nonuniform solar magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the usual approach based on the existence of a global quasi-mode that is damped in time due to resonant absorption. Instead, we use a modal expansion to express the MHD kink wave as a superposition of Alfvén continuum modes that are phase mixed as time evolves. The comparison of the two techniques evidences that the modal analysis is more physically transparent and describes both the damping of global kink motions and the building up of small scales due to phase mixing. In addition, we discuss that the processes of resonant absorption and phase mixing are closely linked. They represent two aspects of the same underlying physical mechanism: the energy cascade from large scales to small scales due to naturally occurring plasma and/or magnetic field inhomogeneities. This process may provide the necessary scenario for efficient dissipation of transverse MHD wave energy in the solar atmospheric plasma.

  4. Synthesis of Numerical Methods for Modeling Wave Energy Converter-Point Absorbers: Preprint

    SciTech Connect

    Li, Y.; Yu, Y. H.

    2012-05-01

    During the past few decades, wave energy has received significant attention among all ocean energy formats. Industry has proposed hundreds of prototypes such as an oscillating water column, a point absorber, an overtopping system, and a bottom-hinged system. In particular, many researchers have focused on modeling the floating-point absorber as the technology to extract wave energy. Several modeling methods have been used such as the analytical method, the boundary-integral equation method, the Navier-Stokes equations method, and the empirical method. However, no standardized method has been decided. To assist the development of wave energy conversion technologies, this report reviews the methods for modeling the floating-point absorber.

  5. Comparing Ray-Based and Wave-Based Models of Cross-Beam Energy Transfer

    NASA Astrophysics Data System (ADS)

    Follett, R. K.; Edgell, D. H.; Shaw, J. G.; Froula, D. H.; Myatt, J. F.

    2016-10-01

    Ray-based models of cross-beam energy transfer (CBET) are used in radiation-hydrodynamics codes to calculate laser-energy deposition. The accuracy of ray-based CBET models is limited by assumptions about the polarization and phase of the interacting laser beams and by the use of a paraxial Wentzel-Kramers-Brillouin (WKB) approximation. A 3-D wave-based solver (LPSE-CBET) is used to study the nonlinear interaction between overlapping laser beams in underdense plasma. A ray-based CBET model is compared to the wave-based model and shows good agreement in simple geometries where the assumptions of the ray-based model are satisfied. Near caustic surfaces, the assumptions of the ray-based model break down and the calculated energy transfer deviates from wave-based calculations. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  6. Characterisation of the biofouling community on a floating wave energy device.

    PubMed

    Nall, Christopher R; Schläppy, Marie-Lise; Guerin, Andrew J

    2017-05-01

    Wave energy devices are novel structures in the marine environment and, as such, provide a unique habitat for biofouling organisms. In this study, destructive scrape samples and photoquadrats were used to characterise the temperate epibenthic community present on prototypes of the Pelamis wave energy converter. The biofouling observed was extensive and diverse with 115 taxa recorded including four non-native species. Vertical zonation was identified on the sides of the device, with an algae-dominated shallow subtidal area and a deeper area characterised by a high proportion of suspension-feeding invertebrates. Differences in species composition and biomass were also observed between devices, along the length of the device and between sampling dates. This research provides an insight into the variation of biofouling assemblages on a wave energy device as well as the potential technical and ecological implications associated with biofouling on marine renewable energy structures.

  7. Thermal compression waves. 2: Mass adjustment and vertical transfer of the total energy

    NASA Astrophysics Data System (ADS)

    Nicholls, Melville E.; Pielke, Roger A.

    1994-01-01

    A fully compressible model is used to simulate the mass adjustment that occurs in response to a prescribed heat source. Results illustrate the role that thermal compression waves have in this process. The vertical mass transport associated with compression waves decreases rapidly with height. Most of the mass transport occurs in the horizontal, with the vertical structure of the disturbance similar to that of a Lamb wave. The vertical transfer of total energy in a thermally driven mixed layer is also examined. It is shown that the upward transport of total energy is accomplished by a compression effect rather than by the exchange of warm and cold air by buoyant thermals. Model results are analyzed to determine budgets of total energy, mass and entropy. It is demonstrated that buoyant thermals are predominantly responsible for a transfer of entropy, rather than total energy. In the light of these results the notion of 'heat transport' in a fluid is discussed.

  8. Anomalous electron-ion energy coupling in electron drift wave turbulence

    NASA Astrophysics Data System (ADS)

    Zhao, Lei

    Turbulence is a ubiquitous phenomenon in nature, and it is well known that turbulence couples energy input to dissipation by cascade processes. Plasma turbulence play a critical role in tokamak confinement. Magnetized plasma turbulence is quasi 2D, anisotropic, wave like and two fluid (i.e. electrons and ions) in structure. Thus, weakly collisional plasma turbulence can mediate electron and ion energy transfer. The issue of anomalous electron and ion energy coupling is particularly important for low collisionality, electron heated plasmas, such as ITER. In this work, we reconsider the classic problem of turbulent heating and energy transfer pathways in drift wave turbulence. The total turbulent heating, composed of quasilinear electron cooling, quasilinear ion heating, nonlinear ion heating and zonal flow frictional heating, is analyzed. In Chapter 2, the electron and ion energy exchange via linear wave and particle resonance will be computed. To address net heating, we show the turbulent heating in an annulus arises due to a wave energy flux differential across this region. We show this net heating is proportional to the Reynolds work on the zonal flow. Zonal flow friction heats ions, thus the turbulence and zonal flow interaction enters as an important energy transfer channel. Since zonal flows are nonlinearly generated, it follows that we should apply weak turbulence theory to calculate the nonlinear ion turbulent heating via the virtual mode resonance in the electron drift wave turbulence, which will be discussed in Chapter 3. We defines a new collisionless turbulent energy transfer channel through nonlinear Landau damping in the electron and ion energy coupling process. The result shows that nonlinear ion heating can exceed quasilinear ion heating, so that nonlinear heating becomes the principal collisionless wave energy dissipation channel in electron drift wave turbulence. This follows since the beat mode resonates with the bulk of the ion distribution, in

  9. Quantification of the Energy Dissipated by Alfven Waves in a Polar Coronal Hole

    NASA Astrophysics Data System (ADS)

    Hahn, M.; Savin, D. W.

    2013-12-01

    We present a measurement of the energy carried and dissipated by Alfven waves in a polar coronal hole. Alfven waves have been proposed as the energy source that heats the corona and drives the solar wind. Previous work has shown that line widths decrease with height in coronal holes, which is a signature of wave damping, but have been unable to quantify the energy lost by the waves. This is because line widths depend on both the non-thermal velocity vnt and the ion temperature Ti. We have implemented a means to separate the Ti and vnt contributions using the observation that, at low heights, the waves are undamped and the ion temperatures do not change with height. This enables us to determine the amount of energy carried by the waves at low heights, which is proportional to vnt. We find the initial energy flux density present was 6.7×0.7×10^5 erg cm^-2 s^-1, which is sufficient to heat the coronal hole and accelerate the solar wind during the 2007 - 2009 solar minimum. Additionally, we find that about 85% of this energy is dissipated below 1.5 R_sun, sufficiently low that thermal conduction can transport the energy throughout the coronal hole, heating it and driving the fast solar wind. The remaining energy is roughly consistent with what models show is needed to provide the extended heating above the sonic point for the fast solar wind. We have also studied Ti, which we found to be in the range of 1 - 2 MK, depending on the ion species.

  10. 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.

  11. Urodynamic and Immunohistochemical Evaluation of Intravesical Botulinum Toxin A Delivery Using Low Energy Shock Waves.

    PubMed

    Chuang, Yao-Chi; Huang, Tung-Liang; Tyagi, Pradeep; Huang, Chao-Cheng

    2016-08-01

    We investigated the feasibility of using low energy shock waves for intravesical botulinum toxin A delivery. We also evaluated its efficacy for acetic acid induced bladder hyperactivity in rats. In study 1 magnetic resonance imaging with intravesical administration of Gd-DTPA (Gd-diethylenetriamine pentaacetic acid) contrast medium was performed to visualize increased bladder urothelial permeability after low energy shock waves. In study 2 saline (1 ml) or botulinum toxin A (20 U/1 ml saline) was administered in the bladder with or without low energy shock waves (300 pulses at 0.12 mJ/mm(2)) and retained for 1 hour on day 1. Continuous cystometrograms were performed on day 8 by filling the bladder with saline followed by 0.3% acetic acid. The bladder was harvested for histology, and SNAP-25, SNAP-23 and COX-2 expression by Western blot or immunostaining. Magnetic resonance imaging established bladder urothelial leakage of Gd-DTPA after low energy shock waves, which was not seen in controls. The intercontraction interval was decreased 71.9%, 72.6% and 70.6% after intravesical instillation of acetic acid in saline, saline plus low energy shock wave and botulinum toxin A pretreated rats, respectively. However, rats that received botulinum toxin A plus low energy shock waves showed a significantly reduced response (48.6% decreased intercontraction interval) to acetic acid instillation without compromising voiding function. Rats pretreated with botulinum toxin A plus low energy shock waves showed a decreased inflammatory reaction (p <0.05), and decreased expression of SNAP-23 (p <0.05), SNAP-25 (p = 0.061) and COX-2 (p <0.05) compared with the control group. Low energy shock waves increased urothelial permeability, facilitated intravesical botulinum toxin A delivery and blocked acetic acid induced hyperactive bladder. These results support low energy shock waves as a promising method to deliver botulinum toxin A without the need for injection. Copyright © 2016

  12. Smart metacomposite-based systems for transient elastic wave energy harvesting

    NASA Astrophysics Data System (ADS)

    Yi, K.; Monteil, M.; Collet, M.; Chesne, S.

    2017-03-01

    In this paper, novel harvesting systems are proposed and studied to obtain enhanced energy from transient waves. Each of these systems contains a piezo-lens to focus waves and a harvester to yield energy from the induced focused waves. The piezo-lens comprises a host plate and piezoelectric patches bonded on the plate surfaces. The piezoelectric patches are shunted with negative capacitance (NC) circuits in order to control the spatial variation of the effective refractive index inside the piezo-lens domain. The harvester is placed at the designed focal point of the piezo-lens, two different synchronized switch harvesting on inductor (SSHI) based harvesters are analyzed in the studies. Corrected reduced models are developed to predict the transient responses of the harvesting systems. The performances of the systems incorporating SSHI-based harvesters in transient wave energy harvesting are studied and compared with the system using a standard DC harvester. The focusing effect of the piezo-lens on transient waves and its capability to improve the harvested energy are verified. Since the NC circuits are active elements, an energy balance analysis is performed. Applicability of the harvesting systems is also discussed.

  13. Eikonal Simulations for the Energy Transfer in the Deep Ocean Internal Wave Field near Mixing Hotspots

    NASA Astrophysics Data System (ADS)

    Ijichi, T.; Hibiya, T.

    2016-02-01

    In the proximity of mixing hotspots, the observed internal wave spectra are usually distorted from the Garrett-Munk (GM) spectrum and are characterized by the high energy level E as well as the shear/strain ratio Rω quite different from the corresponding value for the GM spectrum (Rω = 3). Accurate parameterization of the energy transfer toward dissipation scales that takes into account the effects of E and Rω is therefore indispensable to quantify the deep ocean mixing. In this study, a series of eikonal simulations are carried out to examine energy transfer within such distorted internal wave spectra. The obtained results are used to assess the recently proposed parameterization for energy dissipation in the distorted internal wave field near mixing hotspots (Ijichi and Hibiya, 2015). In particular, several factors neglected by these authors in formulating the parameterization such as the background vertical divergence and the WKB horizontal scale-separation between small-scale test waves and the background waves are all taken into account throughout the eikonal simulations. It is shown that the calculated energy transfer rate ɛ is fairly consistent with the scaling ɛ E2N2f with N the local buoyancy frequency and f the local inertial frequency. Furthermore, the calculated results exhibit strong Rω dependence quite similar to that predicted from the parameterization by Ijichi and Hibiya (2015), suggesting the validity of their formulation.

  14. Degenerate RS perturbation theory. [Rayleigh-Schroedinger energies and wave functions

    NASA Technical Reports Server (NTRS)

    Hirschfelder, J. O.; Certain, P. R.

    1974-01-01

    A concise, systematic procedure is given for determining the Rayleigh-Schroedinger energies and wave functions of degenerate states to arbitrarily high orders even when the degeneracies of the various states are resolved in arbitrary orders. The procedure is expressed in terms of an iterative cycle in which the energy through the (2n + 1)-th order is expressed in terms of the partially determined wave function through the n-th order. Both a direct and an operator derivation are given. The two approaches are equivalent and can be transcribed into each other. The direct approach deals with the wave functions (without the use of formal operators) and has the advantage that it resembles the usual treatment of nondegenerate perturbations and maintains close contact with the basic physics. In the operator approach, the wave functions are expressed in terms of infinite-order operators which are determined by the successive resolution of the space of the zeroth-order functions.

  15. Energy flow measurements in acoustic waves in a duct.

    PubMed

    Biwa, Tetsushi

    2006-12-22

    Where, how much and how efficiently the energy conversion takes place in a regenerator of a thermoacoustic engine are expressed using the axial distribution of acoustic work flow and heat flow. As a first step in determining the energy flows inside the regenerator, measuring methods of the work flow are briefly described and the experimental results in an acoustic resonator are shown. Applicability of these methods to the regenerator is discussed.

  16. Electron energy distribution functions in low-pressure oxygen plasma columns sustained by propagating surface waves

    SciTech Connect

    Stafford, L.; Margot, J.; Moisan, M.; Khare, R.; Donnelly, V. M.

    2009-01-12

    Electron energy distribution functions (EEDFs) were measured in a 50 mTorr oxygen plasma column sustained by propagating surface waves. Trace-rare-gas-optical-emission spectroscopy was used to derive EEDFs by selecting lines to extract ''electron temperature''(T{sub e}) corresponding to either lower energy electrons that excite high-lying levels through stepwise excitation via metastable states or higher energy electrons that excite emission directly from the ground state. Lower energy T{sub e}'s decreased from 8 to 5.5 eV with distance from the wave launcher, while T{sub e}{approx_equal}6 eV for higher energy electrons and T{sub e}>20 eV for a high-energy tail. Mechanisms for such EEDFs are discussed.

  17. ULF wave electromagnetic energy flux into the ionosphere: Joule heating implications

    NASA Astrophysics Data System (ADS)

    Hartinger, M. D.; Moldwin, M. B.; Zou, S.; Bonnell, J. W.; Angelopoulos, V.

    2015-01-01

    Ultralow-frequency (ULF) waves—in particular, Alfvén waves-transfer energy into the Earth's ionosphere via Joule heating, but it is unclear how much they contribute to global and local heating rates relative to other energy sources. In this study we use Time History of Events and Macroscale Interactions during Substorms satellite data to investigate the spatial, frequency, and geomagnetic activity dependence of the ULF wave Poynting vector (electromagnetic energy flux) mapped to the ionosphere. We use these measurements to estimate Joule heating rates, covering latitudes at or below the nominal auroral oval and below the open/closed field line boundary. We find ULF wave Joule heating rates (integrated over 3-30 mHz frequency band) typically range from 0.001 to 1 mW/m2. We compare these rates to empirical models of Joule heating associated with large-scale, static (on ULF wave timescales) current systems, finding that ULF waves nominally contribute little to the global, integrated Joule heating rate. However, there are extreme cases with ULF wave Joule heating rates of ≥10 mW/m2—in these cases, which are more likely to occur when Kp ≥ 3, ULF waves make significant contributions to the global Joule heating rate. We also find ULF waves routinely make significant contributions to local Joule heating rates near the noon and midnight local time sectors, where static current systems nominally contribute less to Joule heating; the most important contributions come from lower frequency (<7 mHz) waves.

  18. 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.

  19. Hydrodynamic analysis and shape optimization for vertical axisymmetric wave energy converters

    NASA Astrophysics Data System (ADS)

    Zhang, Wan-chao; Liu, Heng-xu; Zhang, Liang; Zhang, Xue-wei

    2016-12-01

    The absorber is known to be vertical axisymmetric for a single-point wave energy converter (WEC). The shape of the wetted surface usually has a great influence on the absorber's hydrodynamic characteristics which are closely linked with the wave power conversion ability. For complex wetted surface, the hydrodynamic coefficients have been predicted traditionally by hydrodynamic software based on the BEM. However, for a systematic study of various parameters and geometries, they are too multifarious to generate so many models and data grids. This paper examines a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped and stepped surfaces based on the boundary discretization method (BDM) which overcomes the previous difficulties. In such case, by using the linear wave theory based on eigenfunction expansion matching method, the expressions of velocity potential in each domain, the added mass, radiation damping and wave excitation forces of the oscillating absorbers are obtained. The good astringency of the hydrodynamic coefficients and wave forces are obtained for various geometries when the discrete number reaches a certain value. The captured wave power for a same given draught and displacement for various geometries are calculated and compared. Numerical results show that the geometrical shape has great effect on the wave conversion performance of the absorber. For absorbers with the same outer radius and draught or displacement, the cylindrical type shows fantastic wave energy conversion ability at some given frequencies, while in the random sea wave, the parabolic and conical ones have better stabilization and applicability in wave power conversion.

  20. Symmetry of spherically converging shock waves through reflection, relating to the shock ignition fusion energy scheme.

    PubMed

    Davie, C J; Evans, R G

    2013-05-03

    We examine the properties of perturbed spherically imploding shock waves in an ideal fluid through the collapse, bounce, and development into an outgoing shock wave. We find broad conservation of the size and shape of ingoing and outgoing perturbations when viewed at the same radius. The outgoing shock recovers the velocity of the unperturbed shock outside the strongly distorted core. The results are presented in the context of the robustness of the shock ignition approach to inertial fusion energy.

  1. Atomic radiative transition probabilities using negative-energy orbitals in fully variational wave functions

    NASA Astrophysics Data System (ADS)

    Jitrik, Oliverio; Bunge, Carlos F.

    2005-07-01

    Transition probabilities have been computed using a variational many-electron theory [R. Jáuregui, C.F. Bunge, E. Ley-Koo, Phys. Rev. A 55 (1997) 1781] incorporating positive-energy and negative-energy orbitals without ambiguities, and absolutely free from variational collapse. The results agree with experiment and with other calculations based on the no-pair Hamiltonian where ad hoc negative-energy orbitals occur in first-order corrections to the wave functions.

  2. Vaporization front in the interaction of a high-energy laser with aerosols - A solitary wave

    NASA Astrophysics Data System (ADS)

    Lee, C. T.; Miller, T. G.

    1982-06-01

    If a high-energy laser beam were to propagate through highly absorbent aerosols, the aerosols might be subject to extinction by evaporation. This could occur, for instance, if a high-energy CO2 laser beam were to propagate through a medium containing a mist of water droplets. The incident energy would evaporate the droplets, thus increasing the transmission with time. In this paper, solitary waves are obtained as the asymptotic solution to the coupled nonlinear equations describing such an interaction.

  3. Energy dissipation within the wave run-up at stepped revetments

    NASA Astrophysics Data System (ADS)

    Kerpen, Nils B.; Bung, Daniel B.; Valero, Daniel; Schlurmann, Torsten

    2017-08-01

    To understand the processes and energy dissipation performance caused by turbulence during the wave run-up over a stepped revetment, hydraulic model tests with steady flow conditions are conducted and correlated with unsteady flow conditions of the wave run-up within a short time frame. Under irregular waves, the run-up reduction over a stepped revetment is dependent on the Iribarren number and decreases for decreasing Iribarren numbers. Velocity gradients are found to be similar in a steady and unsteady flow regime near the pseudo-bottom.

  4. Inverse energy cascade and emergence of large coherent vortices in turbulence driven by Faraday waves.

    PubMed

    Francois, N; Xia, H; Punzmann, H; Shats, M

    2013-05-10

    We report the generation of large coherent vortices via inverse energy cascade in Faraday wave driven turbulence. The motion of floaters in the Faraday waves is three dimensional, but its horizontal velocity fluctuations show unexpected similarity with two-dimensional turbulence. The inverse cascade is detected by measuring frequency spectra of the Lagrangian velocity, and it is confirmed by computing the third moment of the horizontal velocity fluctuations. This is observed in deep water in a broad range of wavelengths and vertical accelerations. The results broaden the scope of recent findings on Faraday waves in thin layers [A. von Kameke et al., Phys. Rev. Lett. 107, 074502 (2011)].

  5. Power maximization of a point absorber wave energy converter using improved model predictive control

    NASA Astrophysics Data System (ADS)

    Milani, Farideh; Moghaddam, Reihaneh Kardehi

    2017-08-01

    This paper considers controlling and maximizing the absorbed power of wave energy converters for irregular waves. With respect to physical constraints of the system, a model predictive control is applied. Irregular waves' behavior is predicted by Kalman filter method. Owing to the great influence of controller parameters on the absorbed power, these parameters are optimized by imperialist competitive algorithm. The results illustrate the method's efficiency in maximizing the extracted power in the presence of unknown excitation force which should be predicted by Kalman filter.

  6. Observation of energy cascade creating periodic shock waves in a resonator.

    PubMed

    Biwa, Tetsushi; Yazaki, Taichi

    2010-03-01

    Nonlinear excitation of periodic shock waves in high-amplitude standing waves was studied from measurements of the acoustic intensity. A gas column of atmospheric air in a cylindrical resonator was driven sinusoidally by an oscillating piston at the fundamental resonance frequency. Acoustic pressure and axial acoustic particle velocity were simultaneously measured and decomposed into the Fourier components, from which the intensity associated with each of the oscillating modes in the resonator was determined. This letter reports the energy cascade from the driven mode to the second harmonic in the periodic shock waves in the resonator.

  7. Energy dissipation of Alfven wave packets deformed by irregular magnetic fields in solar-coronal arches

    NASA Technical Reports Server (NTRS)

    Similon, Philippe L.; Sudan, R. N.

    1989-01-01

    The importance of field line geometry for shear Alfven wave dissipation in coronal arches is demonstrated. An eikonal formulation makes it possible to account for the complicated magnetic geometry typical in coronal loops. An interpretation of Alfven wave resonance is given in terms of gradient steepening, and dissipation efficiencies are studied for two configurations: the well-known slab model with a straight magnetic field, and a new model with stochastic field lines. It is shown that a large fraction of the Alfven wave energy flux can be effectively dissipated in the corona.

  8. Energy dissipation of Alfven wave packets deformed by irregular magnetic fields in solar-coronal arches

    NASA Technical Reports Server (NTRS)

    Similon, Philippe L.; Sudan, R. N.

    1989-01-01

    The importance of field line geometry for shear Alfven wave dissipation in coronal arches is demonstrated. An eikonal formulation makes it possible to account for the complicated magnetic geometry typical in coronal loops. An interpretation of Alfven wave resonance is given in terms of gradient steepening, and dissipation efficiencies are studied for two configurations: the well-known slab model with a straight magnetic field, and a new model with stochastic field lines. It is shown that a large fraction of the Alfven wave energy flux can be effectively dissipated in the corona.

  9. On the use of evanescent plane waves for low-frequency energy transmission across material interfaces.

    PubMed

    Woods, Daniel C; Bolton, J Stuart; Rhoads, Jeffrey F

    2015-10-01

    The transmission of airborne sound into high-impedance media is of interest in several applications. For example, sonic booms in the atmosphere may impact marine life when incident on the ocean surface, or affect the integrity of existing structures when incident on the ground. Transmission across high impedance-difference interfaces is generally limited by reflection and refraction at the surface, and by the critical angle criterion. However, spatially decaying incident waves, i.e., inhomogeneous or evanescent plane waves, may transmit energy above the critical angle, unlike homogeneous plane waves. The introduction of a decaying component to the incident trace wavenumber creates a nonzero propagating component of the transmitted normal wavenumber, so energy can be transmitted across the interface. A model of evanescent plane waves and their transmission across fluid-fluid and fluid-solid interfaces is developed here. Results are presented for both air-water and air-solid interfaces. The effects of the incident wave parameters (including the frequency, decay rate, and incidence angle) and the interfacial properties are investigated. Conditions for which there is no reflection at the air-solid interface, due to impedance matching between the incident and transmitted waves, are also considered and are found to yield substantial transmission increases over homogeneous incident waves.

  10. Identification of wave energy potential with floating oscillating water column technology in Pulau Baai Beach, Bengkulu

    NASA Astrophysics Data System (ADS)

    Alifdini, I.; Sugianto, D. N.; Andrawina, Y. O.; Widodo, A. B.

    2017-02-01

    Pulau Baai is a beach which is located in Bengkulu, Indonesia. This location has swell waves which is beneficial for wave energy, because it directly faces the Indian Ocean. Floating Oscillating Water Column (OWC) is a prototype used to generate electricity from wave energy. The objective of this research is to identify how much electricity can be generated from floating OWC. This research used a quantitative method by processing wind data (speed and direction) from ogimet.com in 2000-2016. The wind speed rate for wave energy potential of this location is above 5.14 m/s. Wind data is converted to significant wave height and periods data by Sverdrup, Munk, and Bretschneider (SMB) method. Significant wave height rate of this location is 0.06 – 5.33 meters. Assuming that this power plant uses 3 chambers of floating OWC, the power output of OWC is 1.9 GW/year. Thus, suppose each residents’ house uses 1300 watt, this power plant can be used for 1,461,538 residents per year.

  11. On the instability and energy flux of lower hybrid waves in the Venus plasma mantle

    NASA Technical Reports Server (NTRS)

    Strangeway, R. J.; Crawford, G. K.

    1993-01-01

    Waves generated near the lower hybrid resonance frequency by the modified two stream instability have been invoked as a possible source of energy flux into the topside ionosphere of Venus. These waves are observed above the ionopause in a region known as the plasma mantle. The plasma within the mantle appears to be a mixture of magnetosheath and ionospheric plasmas. Since the magnetosheath electrons and ions have temperatures of several tens of eV, any instability analysis of the modified two stream instability requires the inclusion of finite electron and ion temperatures. Finite temperature effects are likely to reduce the growth rate of the instability. Furthermore, the lower hybrid waves are only quasi-electrostatic, and the energy flux of the waves is mainly carried by parallel Poynting flux. The magnetic field in the mantle is draped over the ionopause. Lower hybrid waves therefore cannot transport any significant wave energy to lower altitudes, and so do not act as a source of additional heat to the topside ionosphere.

  12. Balancing Power Absorption and Structural Loading for an Assymmetric Heave Wave-Energy Converter in Regular Waves: Preprint

    SciTech Connect

    Tom, Nathan M.; Madhi, Farshad; Yeung, Ronald W.

    2016-07-01

    The aim of this paper is to maximize the power-to-load ratio of the Berkeley Wedge: a one-degree-of-freedom, asymmetrical, energy-capturing, floating breakwater of high performance that is relatively free of viscosity effects. Linear hydrodynamic theory was used to calculate bounds on the expected time-averaged power (TAP) and corresponding surge restraining force, pitch restraining torque, and power take-off (PTO) control force when assuming that the heave motion of the wave energy converter remains sinusoidal. This particular device was documented to be an almost-perfect absorber if one-degree-of-freedom motion is maintained. The success of such or similar future wave energy converter technologies would require the development of control strategies that can adapt device performance to maximize energy generation in operational conditions while mitigating hydrodynamic loads in extreme waves to reduce the structural mass and overall cost. This paper formulates the optimal control problem to incorporate metrics that provide a measure of the surge restraining force, pitch restraining torque, and PTO control force. The optimizer must now handle an objective function with competing terms in an attempt to maximize power capture while minimizing structural and actuator loads. A penalty weight is placed on the surge restraining force, pitch restraining torque, and PTO actuation force, thereby allowing the control focus to be placed either on power absorption or load mitigation. Thus, in achieving these goals, a per-unit gain in TAP would not lead to a greater per-unit demand in structural strength, hence yielding a favorable benefit-to-cost ratio. Demonstrative results in the form of TAP, reactive TAP, and the amplitudes of the surge restraining force, pitch restraining torque, and PTO control force are shown for the Berkeley Wedge example.

  13. Balancing Power Absorption and Structural Loading for an Asymmetric Heave Wave-Energy Converter in Regular Waves

    SciTech Connect

    Tom, Nathan M.; Madhi, Farshad; Yeung, Ronald W.

    2016-06-24

    The aim of this paper is to maximize the power-to-load ratio of the Berkeley Wedge: a one-degree-of-freedom, asymmetrical, energy-capturing, floating breakwater of high performance that is relatively free of viscosity effects. Linear hydrodynamic theory was used to calculate bounds on the expected time-averaged power (TAP) and corresponding surge restraining force, pitch restraining torque, and power take-off (PTO) control force when assuming that the heave motion of the wave energy converter remains sinusoidal. This particular device was documented to be an almost-perfect absorber if one-degree-of-freedom motion is maintained. The success of such or similar future wave energy converter technologies would require the development of control strategies that can adapt device performance to maximize energy generation in operational conditions while mitigating hydrodynamic loads in extreme waves to reduce the structural mass and overall cost. This paper formulates the optimal control problem to incorporate metrics that provide a measure of the surge restraining force, pitch restraining torque, and PTO control force. The optimizer must now handle an objective function with competing terms in an attempt to maximize power capture while minimizing structural and actuator loads. A penalty weight is placed on the surge restraining force, pitch restraining torque, and PTO actuation force, thereby allowing the control focus to be placed either on power absorption or load mitigation. Thus, in achieving these goals, a per-unit gain in TAP would not lead to a greater per-unit demand in structural strength, hence yielding a favorable benefit-to-cost ratio. Demonstrative results in the form of TAP, reactive TAP, and the amplitudes of the surge restraining force, pitch restraining torque, and PTO control force are shown for the Berkeley Wedge example.

  14. Acoustic noise and pneumatic wave vortices energy harvesting on highways

    NASA Astrophysics Data System (ADS)

    Pogacian, S.; Bot, A.; Zotoiu, D.

    2012-02-01

    This paper is aimed to present the structure and the principle of a energy harvesting system that uses the air movement emanated from passing traffic to produce and accumulate electrical energy. Each of the system's elements consists of a inertial mass panel which oscillate when driving cars pass. The panel is attached to a linear electromagnetic mini generator (or/and some piezo electric micro generators) and at the time of passing, it produces energy which is store it in a supercapacitor or in a rechargeable battery. The concept can be applied to busy roads, and to high-frequented rail networks and it can work with street and road lighting, information panels and monitoring devices.

  15. Low-energy proton increases associated with interplanetary shock waves.

    NASA Technical Reports Server (NTRS)

    Palmeira, R. A. R.; Allum, F. R.; Rao, U. R.

    1971-01-01

    Impulsive increases in the low energy proton flux observed by the Explorer 34 satellite, in very close time association with geomagnetic storm sudden commencements are described. It is shown that these events are of short duration (20-30 min) and occur only during the decay phase of a solar cosmic-ray flare event. The differential energy spectrum and the angular distribution of the direction of arrival of the particles are discussed. Two similar increases observed far away from the earth by the Pioneer 7 and 8 deep-space probes are also presented. These impulsive increases are compared with Energetic Storm Particle events and their similarities and differences are discussed. A model is suggested to explain these increases, based on the sweeping and trapping of low energy cosmic rays of solar origin by the advancing shock front responsible for the sudden commencement detected on the earth.

  16. Optimal control of wave energy devices with various power-take-off mechanisms

    SciTech Connect

    Nichols, N.K.; Crossley, A.

    1996-12-31

    The aims of this research are to develop and test methods for analyzing and computing optimal control strategies for maximizing the useful power generated from wave energy converters incorporating realistic power-take-off and control mechanisms. Previously, strategies for maximizing energy absorbed by wave devices have been investigated, but these studies have assumed an ideal conversion rate using perfectly efficient turbomachinery with no constraints imposed by the generator capacity. In this paper various turbine characteristics and control mechanisms incorporating nonlinear losses are modelled, the qualitative properties of the optimal control strategy for maximizing average power delivered at the turbine shaft are analyzed, computational techniques for determining numerical solutions to the optimal control problem are established and the results are tested on a fully developed hydrodynamic model of a wave energy device.

  17. Controlled high-energy ion acceleration with intense chirped standing waves

    NASA Astrophysics Data System (ADS)

    Mackenroth, Felix; Gonoskov, Arkady; Marklund, Mattias

    2016-10-01

    We present the latest results of the recently proposed ion acceleration mechanism ``chirped standing wave acceleration''. This mechanism is based on locking the electrons of a thin plasma layer to the moving nodes of a standing wave formed by a chirped laser pulse reflected from a mirror behind the thin layer. The resulting longitudinal charge separation field between the displaced electrons and the residual ions then accelerates the latter. Since the plasma layer is stabilized by the standing wave, the formation of plasma instabilities is suppressed. Furthermore, the experimentally accessible laser chirp provides a versatile tool for manipulating the resulting ion beam in terms of maximum particle energy, particle number and spectral distribution. Through this scheme, proton beams, with energy spectra peaked around 100 MeV, were shown to be feasible for pulse energies at the level of 10 J. Wallenberg Foundation within the Grant ''Plasma based compact ion sources'' (PLIONA).

  18. Rayleigh-wave dispersive energy imaging using a high-resolution linear radon transform

    USGS Publications Warehouse

    Luo, Y.; Xia, J.; Miller, R.D.; Xu, Y.; Liu, J.; Liu, Q.

    2008-01-01

    Multichannel Analysis of Surface Waves (MASW) analysis is an efficient tool to obtain the vertical shear-wave profile. One of the key steps in the MASW method is to generate an image of dispersive energy in the frequency-velocity domain, so dispersion curves can be determined by picking peaks of dispersion energy. In this paper, we propose to image Rayleigh-wave dispersive energy by high-resolution linear Radon transform (LRT). The shot gather is first transformed along the time direction to the frequency domain and then the Rayleigh-wave dispersive energy can be imaged by high-resolution LRT using a weighted preconditioned conjugate gradient algorithm. Synthetic data with a set of linear events are presented to show the process of generating dispersive energy. Results of synthetic and real-world examples demonstrate that, compared with the slant stacking algorithm, high-resolution LRT can improve the resolution of images of dispersion energy by more than 50%. ?? Birkhaueser 2008.

  19. Mechanisms of ignition by transient energy deposition: Regimes of combustion wave propagation

    NASA Astrophysics Data System (ADS)

    Kiverin, A. D.; Kassoy, D. R.; Ivanov, M. F.; Liberman, M. A.

    2013-03-01

    Regimes of chemical reaction wave propagating in reactive gaseous mixtures, whose chemistry is governed by chain-branching kinetics, are studied depending on the characteristics of a transient thermal energy deposition localized in a finite volume of reactive gas. Different regimes of the reaction wave propagation are initiated depending on the amount of deposited thermal energy, power of the source, and the size of the hot spot. The main parameters which define regimes of the combustion waves facilitated by the transient deposition of thermal energy are acoustic time scale, duration of the energy deposition, ignition time scale, and size of the hot spot. The interplay between these parameters specifies the role of gasdynamical processes, the formation and steepness of the temperature gradient, and speed of the spontaneous wave. The obtained results show how ignition of one or another combustion regime depends on the value of energy, rate of the energy deposition, and size of the hot spot, which is important for the practical use and for risk assessment.

  20. Analytical studies on a traveling wave direct energy converter for D-{sup 3}He fusion

    SciTech Connect

    Syu, L.Y.; Tomita, Yukihiro; Momota, Hiromu; Miley, G.H.

    1995-04-01

    Analytical studies on a traveling wave direct energy converter (TWDEC) for D-{sup 3}He fueled fusion are carried out. The energy of 15 MeV carried by fusion protons is too high to handle with an electrostatic device. The TWDEC controls these high energy particles on the base of the principle of a Linac. This traveling wave method is discussed and the details of proton dynamics and excitation mechanism of electric power are clarified. The TWEDC consists of a modulator and decelerator. The applied traveling wave potential to the modulator modulates the velocity of fusion proton beams. This modulation makes a form of bunched protons at a down stream of the modulator. The decelerator has a set of meshed grids, each of which is connected to a transmission circuit. The phase velocity of excited wave on the transmission circuit is controlled the same way as that of decelerated protons. The kinetic energy 15 MeV of proton beams changes into an oscillating electromagnetic energy on the transmission circuit. This highly efficient direct energy converter of fusion protons brings a fusion reactor with a high plant efficiency. 4 refs., 4 figs.

  1. Preliminary Analysis of an Oscillating Surge Wave Energy Converter with Controlled Geometry: Preprint

    SciTech Connect

    Tom, Nathan; Lawson, Michael; Yu, Yi-Hsiang; Wright, Alan

    2015-09-09

    The aim of this paper is to present a novel wave energy converter device concept that is being developed at the National Renewable Energy Laboratory. The proposed concept combines an oscillating surge wave energy converter with active control surfaces. These active control surfaces allow for the device geometry to be altered, which leads to changes in the hydrodynamic properties. The device geometry will be controlled on a sea state time scale and combined with wave-to-wave power-take-off control to maximize power capture, increase capacity factor, and reduce design loads. The paper begins with a traditional linear frequency domain analysis of the device performance. Performance sensitivity to foil pitch angle, the number of activated foils, and foil cross section geometry is presented to illustrate the current design decisions; however, it is understood from previous studies that modeling of current oscillating wave energy converter designs requires the consideration of nonlinear hydrodynamics and viscous drag forces. In response, a nonlinear model is presented that highlights the shortcomings of the linear frequency domain analysis and increases the precision in predicted performance.

  2. Low energy, low latitude wave-dominated shallow marine depositional systems: examples from northern Borneo

    NASA Astrophysics Data System (ADS)

    Lambiase, Joseph J.; Suraya Tulot

    2013-12-01

    The depositional environments of the wave-dominant successions in the middle to late Miocene Belait and Sandakan Formations in northwestern and northern Borneo, respectively, were determined based on grain size distributions, sedimentary structures and facies successions, as well as trace and microfossil assemblages. Generally, progradational shoreface successions in the Belait Formation were deposited in very low wave energy environments where longshore currents were too weak to generate trough cross-bedding. Shoreface sands are laterally continuous for several km and follow the basin contours, suggesting attached beaches similar to the modern Brunei coastline. In contrast, trough cross-bedding is common in the coarser Sandakan Formation and back-barrier mangrove swamp deposits cap the progradational succession as on the modern northern Dent Peninsula coastline, indicating barrier development and higher wave energy conditions than in the Belait Formation. The Borneo examples indicate that barrier systems that include significant tidal facies form under higher wave energy conditions than attached beaches with virtually no tidal facies. Also, Borneo's low latitude climate promotes back-barrier mangrove which reduces tidal exchange and reduces tidal influence relative to comparable temperate climate systems. The results of the study indicate that depositional systems on low energy, wave-dominated coasts are highly variable, as are the sand bodies and facies associations they generate.

  3. The influence of the directional energy distribution on the nonlinear dispersion relation in a random gravity wave field

    NASA Technical Reports Server (NTRS)

    Huang, N. E.; Tung, C.-C.

    1977-01-01

    The influence of the directional distribution of wave energy on the dispersion relation is calculated numerically using various directional wave spectrum models. The results indicate that the dispersion relation varies both as a function of the directional energy distribution and the direction of propagation of the wave component under consideration. Furthermore, both the mean deviation and the random scatter from the linear approximation increase as the energy spreading decreases. Limited observational data are compared with the theoretical results. The agreement is favorable.

  4. The influence of the directional energy distribution on the nonlinear dispersion relation in a random gravity wave field

    NASA Technical Reports Server (NTRS)

    Huang, N. E.; Tung, C.-C.

    1977-01-01

    The influence of the directional distribution of wave energy on the dispersion relation is calculated numerically using various directional wave spectrum models. The results indicate that the dispersion relation varies both as a function of the directional energy distribution and the direction of propagation of the wave component under consideration. Furthermore, both the mean deviation and the random scatter from the linear approximation increase as the energy spreading decreases. Limited observational data are compared with the theoretical results. The agreement is favorable.

  5. Nonlinear saturation of wave packets excited by low-energy electron horseshoe distributions.

    PubMed

    Krafft, C; Volokitin, A

    2013-05-01

    Horseshoe distributions are shell-like particle distributions that can arise in space and laboratory plasmas when particle beams propagate into increasing magnetic fields. The present paper studies the stability and the dynamics of wave packets interacting resonantly with electrons presenting low-energy horseshoe or shell-type velocity distributions in a magnetized plasma. The linear instability growth rates are determined as a function of the ratio of the plasma to the cyclotron frequencies, of the velocity and the opening angle of the horseshoe, and of the relative thickness of the shell. The nonlinear stage of the instability is investigated numerically using a symplectic code based on a three-dimensional Hamiltonian model. Simulation results show that the dynamics of the system is mainly governed by wave-particle interactions at Landau and normal cyclotron resonances and that the high-order normal cyclotron resonances play an essential role. Specific features of the dynamics of particles interacting simultaneously with two or more waves at resonances of different natures and orders are discussed, showing that such complex processes determine the main characteristics of the wave spectrum's evolution. Simulations with wave packets presenting quasicontinuous spectra provide a full picture of the relaxation of the horseshoe distribution, revealing two main phases of the evolution: an initial stage of wave energy growth, characterized by a fast filling of the shell, and a second phase of slow damping of the wave energy, accompanied by final adjustments of the electron distribution. The influence of the density inhomogeneity along the horseshoe on the wave-particle dynamics is also discussed.

  6. The Contribution of Environmental Siting and Permitting Requirements to the Cost of Energy for Wave Energy Devices

    SciTech Connect

    Copping, Andrea E.; Geerlofs, Simon H.; Hanna, Luke A.

    2014-06-01

    Responsible deployment of marine and hydrokinetic (MHK) devices in estuaries, coastal areas, and major rivers requires that biological resources and ecosystems be protected through siting and permitting (consenting) processes. Scoping appropriate deployment locations, collecting pre-installation (baseline) and post-installation data all add to the cost of developing MHK projects, and hence to the cost of energy. Under the direction of the U.S. Department of Energy, Pacific Northwest National Laboratory scientists have developed logic models that describe studies and processes for environmental siting and permitting. Each study and environmental permitting process has been assigned a cost derived from existing and proposed tidal, wave, and riverine MHK projects. Costs have been developed at the pilot scale and for commercial arrays for a surge wave energy converter

  7. Feasibility study of tuned liquid column damper for ocean wave energy extraction

    NASA Astrophysics Data System (ADS)

    Wong, Yihong; King, Yeong-Jin; Lai, An-Chow; Chong, Kok-Keong; Lim, Boon-Han

    2017-04-01

    Intermittent nature and low efficiency are the major issues in renewable energy supply. To overcome these issues, one of the possible methods is through a hybrid system where multiple sources of renewable energy are combined to compensate each other's weaknesses. The hybrid of solar energy and wave energy becomes possible through the introduction of a stable floating platform which enables solar energy generation above it and wave energy harvesting underneath it. This paper is intended to study the feasibility of harnessing ocean wave energy using a tuned liquid column damper (TLCD), a type of passive damping device that is designed to suppress externally induced vibration force at a specific frequency range. The proposed TLCD is to be implemented within a floating offshore structure to serve as a vibration mitigating mechanism by reducing the dynamic response of the structure and simultaneously utilize the flowing motion of liquid within the TLCD for generating electricity. The constructed TLCD prototype is tuned according to theoretical study and tested using a shaking table with a predetermined frequency range. The oscillating motion of water within the TLCD and the potential of installation of hydro turbine generator in term of recoverable amount of energy are studied.

  8. A long-term nearshore wave hindcast for Ireland: Atlantic and Irish Sea coasts (1979-2012). Present wave climate and energy resource assessment

    NASA Astrophysics Data System (ADS)

    Gallagher, Sarah; Tiron, Roxana; Dias, Frédéric

    2014-08-01

    The Northeast Atlantic possesses some of the highest wave energy levels in the world. The recent years have witnessed a renewed interest in harnessing this vast energy potential. Due to the complicated geomorphology of the Irish coast, there can be a significant variation in both the wave and wind climate. Long-term hindcasts with high spatial resolution, properly calibrated against available measurements, provide vital information for future deployments of ocean renewable energy installations. These can aid in the selection of adequate locations for potential deployment and for the planning and design of those marine operations. A 34-year (from 1979 to 2012), high-resolution wave hindcast was performed for Ireland including both the Atlantic and Irish Sea coasts, with a particular focus on the wave energy resource. The wave climate was estimated using the third-generation spectral wave model WAVEWATCH III®; version 4.11, the unstructured grid formulation. The wave model was forced with directional wave spectral data and 10-m winds from the European Centre for Medium Range Weather Forecasts (ECMWF) ERA-Interim reanalysis, which is available from 1979 to the present. The model was validated against available observed satellite altimeter and buoy data, particularly in the nearshore, and was found to be excellent. A strong spatial and seasonal variability was found for both significant wave heights, and the wave energy flux, particularly on the north and west coasts. A strong correlation between the North Atlantic Oscillation (NAO) teleconnection pattern and wave heights, wave periods, and peak direction in winter and also, to a lesser extent, in spring was identified.

  9. Relative velocity of seagrass blades: Implications for wave attenuation in low-energy environments

    NASA Astrophysics Data System (ADS)

    Bradley, Kevin; Houser, Chris

    2009-03-01

    While the ability of subaquatic vegetation to attenuate wave energy is well recognized in general, there is a paucity of data from the field to describe the rate and mechanisms of wave decay, particularly with respect to the relative motion of the vegetation. The purpose of this study was to quantify the attenuation of incident wave height through a seagrass meadow and characterize the blade movement under oscillatory flow under the low-energy conditions characteristic of fetch-limited and sheltered environments. The horizontal motion of the seagrass blades and the velocity just above the seagrass canopy were measured using a digital video camera and an acoustic Doppler velicometer (ADV) respectively in order to refine the estimates of the drag coefficient based on the relative velocity. Significant wave heights (Hs) were observed to increase by ˜0.02 m (˜20%) through the first 5 m of the seagrass bed but subsequently decrease exponentially over the remainder of the bed. The exponential decay coefficient varied in response to the Reynolds number calculated using blade width (as the length scale) and the oscillatory velocity measured immediately above the canopy. The ability of the seagrass to attenuate wave energy decreases as incident wave heights increase and conditions become more turbulent. Estimates of the time-averaged canopy height and the calculated hydraulic roughness suggest that, as the oscillatory velocity increases, the seagrass becomes fully extended and leans in the direction of flow for a longer part of the wave cycle. The relationship between the drag coefficient and the Reynolds number further suggests that the vegetation is swaying (going with the flow) at low-energy conditions but becomes increasingly rigid as oscillatory velocities increase over the limited range of the conditions observed (200 < Re < 800). In addition to the changing behavior of the seagrass motion, the attenuation was not uniform with wave frequency, and waves at a

  10. Nonlinear Elastic Effects on the Energy Flux Deviation of Ultrasonic Waves in GR/EP Composites

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    In isotropic materials, the direction of the energy flux (energy per unit time per unit area) of an ultrasonic plane wave is always along the same direction as the normal to the wave front. In anisotropic materials, however, this is true only along symmetry directions. Along other directions, the energy flux of the wave deviates from the intended direction of propagation. This phenomenon is known as energy flux deviation and is illustrated. The direction of the energy flux is dependent on the elastic coefficients of the material. This effect has been demonstrated in many anisotropic crystalline materials. In transparent quartz crystals, Schlieren photographs have been obtained which allow visualization of the ultrasonic waves and the energy flux deviation. The energy flux deviation in graphite/epoxy (gr/ep) composite materials can be quite large because of their high anisotropy. The flux deviation angle has been calculated for unidirectional gr/ep composites as a function of both fiber orientation and fiber volume content. Experimental measurements have also been made in unidirectional composites. It has been further demonstrated that changes in composite materials which alter the elastic properties such as moisture absorption by the matrix or fiber degradation, can be detected nondestructively by measurements of the energy flux shift. In this research, the effects of nonlinear elasticity on energy flux deviation in unidirectional gr/ep composites were studied. Because of elastic nonlinearity, the angle of the energy flux deviation was shown to be a function of applied stress. This shift in flux deviation was modeled using acoustoelastic theory and the previously measured second and third order elastic stiffness coefficients for T300/5208 gr/ep. Two conditions of applied uniaxial stress were considered. In the first case, the direction of applied uniaxial stress was along the fiber axis (x3) while in the second case it was perpendicular to the fiber axis along the

  11. Energy from garbage loses promise as wave of future

    SciTech Connect

    Not Available

    1988-07-01

    A front-page article in The Wall Street Journal (June 16, 1988) reports on the rising troubles of waste-to-energy projects. The garbage crisis has promoted the construction of 73 waste-to-energy plants around the country, with hundreds more planned at a combined cost of more than $18 billion, writes Bill Richards. Critics profess to feel an eerie sense of deja vu in the trend toward burning. In the 1990s, they say, this could become for municipalities what the nuclear plant building binge was to electric utilities in the 1970s. It plunged many into an economic and environmental swamp in which a few are still mired, their huge cost over-runs unrecoverable from customers, their shareholder dividends shrunken or ended.

  12. High-energy tail distributions and resonant wave particle interaction

    NASA Technical Reports Server (NTRS)

    Leubner, M. P.

    1983-01-01

    High-energy tail distributions (k distributions) are used as an alternative to a bi-Lorentzian distribution to study the influence of energetic protons on the right- and left-hand cyclotron modes in a hot two-temperature plasma. Although the parameters are chosen to be in a range appropriate to solar wind or magnetospheric configurations, the results apply not only to specific space plasmas. The presence of energetic particles significantly alters the behavior of the electromagnetic ion cyclotron modes, leading to a wide range of unstable frequencies and increased growth rates. From the strongly enhanced growth rates it can be concluded that high-energy tail distributions should not show major temperature anisotropies, which is consistent with observations.

  13. 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

    2015-12-04

    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.

  14. Design and Analysis for a Floating Oscillating Surge Wave Energy Converter: Preprint

    SciTech Connect

    Yu, Y. H.; Li, Y.; Hallett, K.; Hotimsky, C.

    2014-03-01

    This paper presents a recent study on the design and analysis of an oscillating surge wave energy converter. A successful wave energy conversion design requires the balance between the design performance and cost. The cost of energy is often used as the metric to judge the design of the wave energy conversion system. It is often determined based on the device power performance, the cost for manufacturing, deployment, operation and maintenance, as well as the effort to ensure the environmental compliance. The objective of this study is to demonstrate the importance of a cost driven design strategy and how it can affect a WEC design. Three oscillating surge wave energy converter (OSWEC) designs were used as the example. The power generation performance of the design was modeled using a time-domain numerical simulation tool, and the mass properties of the design were determined based on a simple structure analysis. The results of those power performance simulations, the structure analysis and a simple economic assessment were then used to determine the cost-efficiency of selected OSWEC designs. Finally, a discussion on the environmental barrier, integrated design strategy and the key areas that need further investigation is also presented.

  15. Proposal for determining the energy content of gravitational waves by using approximate symmetries of differential equations

    SciTech Connect

    Hussain, Ibrar; Qadir, Asghar; Mahomed, F. M.

    2009-06-15

    Since gravitational wave spacetimes are time-varying vacuum solutions of Einstein's field equations, there is no unambiguous means to define their energy content. However, Weber and Wheeler had demonstrated that they do impart energy to test particles. There have been various proposals to define the energy content, but they have not met with great success. Here we propose a definition using 'slightly broken' Noether symmetries. We check whether this definition is physically acceptable. The procedure adopted is to appeal to 'approximate symmetries' as defined in Lie analysis and use them in the limit of the exact symmetry holding. A problem is noted with the use of the proposal for plane-fronted gravitational waves. To attain a better understanding of the implications of this proposal we also use an artificially constructed time-varying nonvacuum metric and evaluate its Weyl and stress-energy tensors so as to obtain the gravitational and matter components separately and compare them with the energy content obtained by our proposal. The procedure is also used for cylindrical gravitational wave solutions. The usefulness of the definition is demonstrated by the fact that it leads to a result on whether gravitational waves suffer self-damping.

  16. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

  17. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

  18. Broad ion energy distributions in helicon wave-coupled helium plasma

    NASA Astrophysics Data System (ADS)

    Woller, K. B.; Whyte, D. G.; Wright, G. M.

    2017-05-01

    Helium ion energy distributions were measured in helicon wave-coupled plasmas of the dynamics of ion implantation and sputtering of surface experiment using a retarding field energy analyzer. The shape of the energy distribution is a double-peak, characteristic of radiofrequency plasma potential modulation. The broad distribution is located within a radius of 0.8 cm, while the quartz tube of the plasma source has an inner radius of 2.2 cm. The ion energy distribution rapidly changes from a double-peak to a single peak in the radius range of 0.7-0.9 cm. The average ion energy is approximately uniform across the plasma column including the double-peak and single peak regions. The widths of the broad distribution, ΔE , in the wave-coupled mode are large compared to the time-averaged ion energy, ⟨E ⟩. On the axis (r = 0), ΔE / ⟨E ⟩ ≲ 3.4, and at a radius near the edge of the plasma column (r = 2.2 cm), ΔE / ⟨E ⟩ ˜ 1.2. The discharge parameter space is scanned to investigate the effects of the magnetic field, input power, and chamber fill pressure on the wave-coupled mode that exhibits the sharp radial variation in the ion energy distribution.

  19. Proceedings of the Hydrokinetic and Wave Energy Technologies Technical and Environmental Issues Workshop

    SciTech Connect

    2006-03-01

    Renewable energy technologies offer the promise of non-polluting alternatives to fossil and nuclear-fueled power plants to meet growing demand for electrical energy. Two emerging categories of renewable energy technologies, hydrokinetic and wave energy conversion devices, offer ways to tap the energy of moving water without impoundment (dams) or diversion required by many conventional hydroelectric facilities. These technologies include devices designed for deployment in natural streams, tidal estuaries, ocean currents, and constructed waterways, as well as devices designed to capture the energy of ocean waves. On October 26-28, 2005, 54 representatives from government, non-governmental organizations, and private business met to (1) identify the varieties of hydrokinetic energy and wave technology devices, their stages of development, and the projected cost to bring each to market; (2) identify where these technologies can best operate; (3) identify the potential environmental issues associated with these technologies and possible mitigation measures; (4) develop a list of research needs and/or practical solutions to address unresolved environmental issues. These workshop proceedings include detailed summaries of the 24 presentations made and the discussions that followed.

  20. Energy partition, scale by scale, in magnetic Archimedes Coriolis weak wave turbulence.

    PubMed

    Salhi, A; Baklouti, F S; Godeferd, F; Lehner, T; Cambon, C

    2017-02-01

    Magnetic Archimedes Coriolis (MAC) waves are omnipresent in several geophysical and astrophysical flows such as the solar tachocline. In the present study, we use linear spectral theory (LST) and investigate the energy partition, scale by scale, in MAC weak wave turbulence for a Boussinesq fluid. At the scale k^{-1}, the maximal frequencies of magnetic (Alfvén) waves, gravity (Archimedes) waves, and inertial (Coriolis) waves are, respectively, V_{A}k,N, and f. By using the induction potential scalar, which is a Lagrangian invariant for a diffusionless Boussinesq fluid [Salhi et al., Phys. Rev. E 85, 026301 (2012)PLEEE81539-375510.1103/PhysRevE.85.026301], we derive a dispersion relation for the three-dimensional MAC waves, generalizing previous ones including that of f-plane MHD "shallow water" waves [Schecter et al., Astrophys. J. 551, L185 (2001)AJLEEY0004-637X10.1086/320027]. A solution for the Fourier amplitude of perturbation fields (velocity, magnetic field, and density) is derived analytically considering a diffusive fluid for which both the magnetic and thermal Prandtl numbers are one. The radial spectrum of kinetic, S_{κ}(k,t), magnetic, S_{m}(k,t), and potential, S_{p}(k,t), energies is determined considering initial isotropic conditions. For magnetic Coriolis (MC) weak wave turbulence, it is shown that, at large scales such that V_{A}k/f≪1, the Alfvén ratio S_{κ}(k,t)/S_{m}(k,t) behaves like k^{-2} if the rotation axis is aligned with the magnetic field, in agreement with previous direct numerical simulations [Favier et al., Geophys. Astrophys. Fluid Dyn. (2012)] and like k^{-1} if the rotation axis is perpendicular to the magnetic field. At small scales, such that V_{A}k/f≫1, there is an equipartition of energy between magnetic and kinetic components. For magnetic Archimedes weak wave turbulence, it is demonstrated that, at large scales, such that (V_{A}k/N≪1), there is an equipartition of energy between magnetic and potential components

  1. Energy partition, scale by scale, in magnetic Archimedes Coriolis weak wave turbulence

    NASA Astrophysics Data System (ADS)

    Salhi, A.; Baklouti, F. S.; Godeferd, F.; Lehner, T.; Cambon, C.

    2017-02-01

    Magnetic Archimedes Coriolis (MAC) waves are omnipresent in several geophysical and astrophysical flows such as the solar tachocline. In the present study, we use linear spectral theory (LST) and investigate the energy partition, scale by scale, in MAC weak wave turbulence for a Boussinesq fluid. At the scale k-1, the maximal frequencies of magnetic (Alfvén) waves, gravity (Archimedes) waves, and inertial (Coriolis) waves are, respectively, VAk ,N , and f . By using the induction potential scalar, which is a Lagrangian invariant for a diffusionless Boussinesq fluid [Salhi et al., Phys. Rev. E 85, 026301 (2012), 10.1103/PhysRevE.85.026301], we derive a dispersion relation for the three-dimensional MAC waves, generalizing previous ones including that of f -plane MHD "shallow water" waves [Schecter et al., Astrophys. J. 551, L185 (2001), 10.1086/320027]. A solution for the Fourier amplitude of perturbation fields (velocity, magnetic field, and density) is derived analytically considering a diffusive fluid for which both the magnetic and thermal Prandtl numbers are one. The radial spectrum of kinetic, Sκ(k ,t ) , magnetic, Sm(k ,t ) , and potential, Sp(k ,t ) , energies is determined considering initial isotropic conditions. For magnetic Coriolis (MC) weak wave turbulence, it is shown that, at large scales such that VAk /f ≪1 , the Alfvén ratio Sκ(k ,t ) /Sm(k ,t ) behaves like k-2 if the rotation axis is aligned with the magnetic field, in agreement with previous direct numerical simulations [Favier et al., Geophys. Astrophys. Fluid Dyn. (2012)] and like k-1 if the rotation axis is perpendicular to the magnetic field. At small scales, such that VAk /f ≫1 , there is an equipartition of energy between magnetic and kinetic components. For magnetic Archimedes weak wave turbulence, it is demonstrated that, at large scales, such that (VAk /N ≪1 ), there is an equipartition of energy between magnetic and potential components, while at small scales (VAk /N ≫1

  2. Computational simulations of the interaction of water waves with pitching flap-type ocean wave energy converters

    NASA Astrophysics Data System (ADS)

    Pathak, Ashish; Raessi, Mehdi

    2016-11-01

    Using an in-house computational framework, we have studied the interaction of water waves with pitching flap-type ocean wave energy converters (WECs). The computational framework solves the full 3D Navier-Stokes equations and captures important effects, including the fluid-solid interaction, the nonlinear and viscous effects. The results of the computational tool, is first compared against the experimental data on the response of a flap-type WEC in a wave tank, and excellent agreement is demonstrated. Further simulations at the model and prototype scales are presented to assess the validity of the Froude scaling. The simulations are used to address some important questions, such as the validity range of common WEC modeling approaches that rely heavily on the Froude scaling and the inviscid potential flow theory. Additionally, the simulations examine the role of the Keulegan-Carpenter (KC) number, which is often used as a measure of relative importance of viscous drag on bodies exposed to oscillating flows. The performance of the flap-type WECs is investigated at various KC numbers to establish the relationship between the viscous drag and KC number for such geometry. That is of significant importance because such relationship only exists for simple geometries, e.g., a cylinder. Support from the National Science Foundation is gratefully acknowledged.

  3. Low-energy shock waves enhance the susceptibility of staphylococcal biofilms to antimicrobial agents in vitro.

    PubMed

    Wanner, S; Gstöttner, M; Meirer, R; Hausdorfer, J; Fille, M; Stöckl, B

    2011-06-01

    Biofilm-associated infections in wounds or on implants are difficult to treat. Eradication of the bacteria is nearly always impossible, despite the use of specific antibiotics. The bactericidal effects of high-energy extracorporeal shock waves on Staphylococcus aureus have been reported, but the effect of low-energy shock waves on staphylococci and staphylococcal biofilms has not been investigated. In this study, biofilms grown on stainless steel washers were examined by electron microscopy. We tested ten experimental groups with Staph. aureus-coated washers and eight groups with Staph. epidermidis. The biofilm-cultured washers were exposed to low-energy shock waves at 0.16 mJ/mm(2) for 500 impulses. The washers were then treated with cefuroxime, rifampicin and fosfomycin, both alone and in combination. All tests were carried out in triplicate. Viable cells were counted to determine the bactericidal effect. The control groups of Staph. aureus and Staph. epidermidis revealed a cell count of 6 × 10(8) colony-forming units/ml. Complete eradication was achieved using the combination of antibiotic therapy (single antibiotic in Staph. aureus, a combination in Staph. epidermidis) and shock wave application (p < 0.01). We conclude that shock waves combined with antibiotics could be tested in an in vitro model of infection.

  4. Characterization of the Vertical Energy Distribution of the Internal Wave Field in the Upper Ocean

    NASA Astrophysics Data System (ADS)

    Bruch, Jeremy

    2013-11-01

    A method to simulate internal waves in the upper ocean is proposed by defining the vertical energy distribution as a function of mode number with the associated vertical structure functions as an appropriate set of orthogonal basis functions. An internal wave simulation is shown for a case with a stylized BV peak profile, using the Garrett and Munk internal wave model (GM) as the input energy distribution. The resulting simulated spectra are shown to be self-consistent with the proposed definition of the vertical energy distribution. Application of the GM model requires many assumptions, including the requirement that the internal waves are modeled strictly in deep water where there is little variation in the stratification. Given the typical non-uniformity of the stratification profile in the upper ocean, it may be of interest to relax this restriction of the GM model but the obvious non-stationary properties near the thermocline are incompatible with the calculation of the vertical spectrum of the internal wave field. The method described in this presentation suggests a means to reconcile this incompatibility. Membership pending.

  5. Observations of High-frequency Internal Wave Energy Offshore of Point Loma, California

    NASA Astrophysics Data System (ADS)

    Rhee, K.; Crosby, S. C.; Fiedler, J. W.

    2016-12-01

    As coastally directed internal wave energy shoals in shallow water, the resulting bores can transport cold, dense, nutrient-rich waters shoreward, influencing local fauna and ultimately dissipating tidal energy into heat. Understanding the mechanisms, propagation, and resultant transport is crucial for determining the physical-biological interactions along our coasts. We observed significant internal wave energy offshore of Point Loma, San Diego using a thermistor chain moored in 22m depth. Temperature observations spaced 1.5m apart from 0 to 18m were sampled at 2Hz and recorded for a period of ten days during July 2016. Temperature, salinity, oxygen, and nutrient profiles were obtained at 3 stations further offshore during deployment and recovery cruises. At the time of mooring deployment, thermocline depth was 10 to 20m. During recovery we observed a significant decrease of thermocline depth, which was likely caused by surface mixing during a strong wind event. During the 10-day deployment we observed many high frequency (5 to 10 minute periods) internal waves events. In addition, we noticed rapid temperature changes (4oC in less than a minute) suggestive of internal bores; however, other events appeared to be linear, possibly indicating unbroken internal waves. Here, we examine the critical slope for linear mode-1 propagation, the correlation of these events with tidal ebb and flow, and infer how a deeper mixed layer effects internal wave propagation.

  6. Performance analysis of floating double-acting wave-energy pump

    SciTech Connect

    Ueki, H.; Kawaguty, K.; Kira, T.

    1994-12-31

    A double-acting wave-energy pump with floating caisson has been reported experimentally by the authors in a previous paper. This mobile device operates independently both tidal amplitude and incidence for wave propagation. A discharge pipe connects a pressure piston to the float which is the wave energy absorber. The cylinder and piston are set under the sea level in the middle of the caisson. Four hollow columns act as the float of the caisson. In order to investigate analytically the performance of the floating wave-energy pump, motions of both caisson and float-piston were analyzed by solving the equation of vertical motion in regular water waves. In-cylinder pressure was concerned with the external force acting to both float-piston and caisson, and was calculated by the equation for conservation of mass and the Bernoulli`s equation for an unsteady flow by a personal computer. The calculated performance of the flow rate to pump head, and the displacement of both caisson and float-piston were compared well with experimental results.

  7. Vertical Kinetic Energy of Internal Gravity Waves and Turbulent Dissipation in the Ocean

    NASA Astrophysics Data System (ADS)

    Thurnherr, Andreas; St. Laurent, Louis; Richards, Kelvin; Toole, John

    2015-04-01

    Internal gravity waves in the ocean are closely associated with turbulence and mixing. The relationship between IGWs and turbulence is usually interpreted in the framework of the Garret-Munk model, a prescription for open-ocean internal-wave energy as a function of several environmental parameters. Here, we evaluate the relationship between internal-wave energy and turbulence directly, using more than 250 joint profiles of turbulent dissipation from microstructure, and vertical velocity from CTD/LADCP measurements. The observations include profiles from a wide variety of dynamical regimes and latitudes between the equator and 60°. In most profiles, finescale vertical kinetic energy (VKE) varies as kz-2, where kz is the vertical wave number. Scaling VKE with dissipation collapses all off-equatorial data-set average spectra to within √2 or better. The dissipation-normalized spectrum can be interpreted as a new single-parameter (dissipation) model for internal-wave VKE, which is considerably simpler and more accurate than the corresponding Garrett-Munk model.

  8. The influence of wave energy and sediment transport on seagrass distribution

    USGS Publications Warehouse

    Stevens, Andrew W.; Lacy, Jessica R.

    2012-01-01

    A coupled hydrodynamic and sediment transport model (Delft3D) was used to simulate the water levels, waves, and currents associated with a seagrass (Zostera marina) landscape along a 4-km stretch of coast in Puget Sound, WA, USA. A hydroacoustic survey of seagrass percent cover and nearshore bathymetry was conducted, and sediment grain size was sampled at 53 locations. Wave energy is a primary factor controlling seagrass distribution at the site, accounting for 73% of the variability in seagrass minimum depth and 86% of the variability in percent cover along the shallow, sandy portions of the coast. A combination of numerical simulations and a conceptual model of the effect of sea-level rise on the cross-shore distribution of seagrass indicates that the area of seagrass habitat may initially increase and that wave dynamics are an important factor to consider in predicting the effect of sea-level rise on seagrass distributions in wave-exposed areas.

  9. Damage Evaluation Based on a Wave Energy Flow Map Using Multiple PZT Sensors

    PubMed Central

    Liu, Yaolu; Hu, Ning; Xu, Hong; Yuan, Weifeng; Yan, Cheng; Li, Yuan; Goda, Riu; Alamusi; Qiu, Jinhao; Ning, Huiming; Wu, Liangke

    2014-01-01

    A new wave energy flow (WEF) map concept was proposed in this work. Based on it, an improved technique incorporating the laser scanning method and Betti's reciprocal theorem was developed to evaluate the shape and size of damage as well as to realize visualization of wave propagation. In this technique, a simple signal processing algorithm was proposed to construct the WEF map when waves propagate through an inspection region, and multiple lead zirconate titanate (PZT) sensors were employed to improve inspection reliability. Various damages in aluminum and carbon fiber reinforced plastic laminated plates were experimentally and numerically evaluated to validate this technique. The results show that it can effectively evaluate the shape and size of damage from wave field variations around the damage in the WEF map. PMID:24463430

  10. The importance of wave break events for synoptic scale buildups of zonal available potential energy

    NASA Astrophysics Data System (ADS)

    Bowley, K.; Gyakum, J. R.; Atallah, E.

    2016-12-01

    Zonal available potential energy (ZAPE) is an estimate of the amount of potential energy in the atmosphere available for conversion to kinetic energy, providing a good proxy for the strength of the general circulation. Previous studies have estimated total hemispheric ZAPE, ZAPE generation, and conversion to kinetic energy, and proposed physical mechanisms to describe the annual ZAPE cycle as well as short term (sub-seasonal to synoptic) APE depletion events. Large short term depletions of ZAPE have been attributed to synoptic scale processes including intense mid-latitude cyclones which are often associated with cyclonic (LC2) wave break events on the dynamic tropopause. However, increases in ZAPE on similar time scales have not been examined in detail. In this study, we examine the association of significant synoptic time-scale increases in ZAPE with dynamic tropopause wave break events. ZAPE buildup events are determined using a 1979-2011 daily Northern Hemisphere (20°-85°N) ZAPE climatology calculated from the NCEP Reanalysis-2 dataset in an isobaric framework. Build-up events are identified using a standardized anomaly (SA) technique, where the SA of ZAPE must increase by at least 2σ in a near-continuous manner for a 3-10 day period. To diagnose the importance of wave breaks in the troposphere, we objectively identify wave breaks using potential temperature on the dynamic tropopause, identifying both anti-cyclonic (LC1) and cyclonic (LC2) wave breaks during the 1979-2011 period. Our results indicate that LC1 wave break events appear to play an important role in ZAPE buildup events. In particular, the analysis of winter buildup events indicate that LC1 wave break events occur more frequently in the equatorward exit regions of the North Pacific and North Atlantic jet streams when compared with climatology. The formation of these wave break events result in the development of statistically significant warm-core high pressure anomalies in these regions, acting

  11. Dispersion Analysis of Gravity Waves in Fluid Media Discretized by Energy-Orthogonal Finite Elements

    NASA Astrophysics Data System (ADS)

    José Brito Castro, Francisco

    2014-11-01

    This article studies the dispersion of gravity waves in fluid media discretized by the finite element method. The element stiffness matrix is split into basic and higher-order components which are respectively related to the mean and deviatoric components of the gradient of displacement potential. This decomposition is applied to the kinetic energy. The dispersion analysis yields a correlation between the higher-order kinetic energy and the kinetic energy error. The use of this correlation as a reference to apply the higher-order energy as an error indicator for the sloshing modes computed by the finite element method is explored.

  12. Feasibility of Traveling Wave Direct Energy Conversion of Fission Reaction Fragments

    NASA Technical Reports Server (NTRS)

    Tarditi, A. G.; George, J. A.; Miley, G. H.; Scott, J. H.

    2013-01-01

    Fission fragment direct energy conversion has been considered in the past for the purpose of increasing nuclear power plant efficiency and for advanced space propulsion. Since the fragments carry electric charge (typically in the order of 20 e) and have 100 MeV-range kinetic energy, techniques utilizing very high-voltage DC electrodes have been considered. This study is focused on a different approach: the kinetic energy of the charged fission fragments is converted into alternating current by means of a traveling wave coupling scheme (Traveling Wave Direct Energy Converter, TWDEC), thereby not requiring the utilization of high voltage technology. A preliminary feasibility analysis of the concept is introduced based on a conceptual level study and on a particle simulation model of the beam dynamics.

  13. Do sound waves transport the AGN energy in the Perseus cluster?

    NASA Astrophysics Data System (ADS)

    Fabian, A. C.; Walker, S. A.; Russell, H. R.; Pinto, C.; Sanders, J. S.; Reynolds, C. S.

    2017-01-01

    The level of random motions in the intracluster gas lying between 20 and 60 kpc radius in the core of the Perseus cluster has been measured by the Hitomi Soft X-ray Spectrometer (SXS) at 164 ± 10 km s-1. The maximum energy density in turbulent motions on that scale is therefore low. If dissipated as heat, the turbulent energy will be radiated away in less than 80 Myr and cannot spread across the core. A higher velocity is needed to prevent a cooling collapse. Gravity waves are shown to travel too slowly in a radial direction. Here we investigate propagation of energy by sound waves. The energy travels at ˜ 1000 km s-1 and can cross the core in a cooling time. We show that the displacement velocity amplitude of the gas required to carry the power is consistent with the Hitomi result and that the inferred density and temperature variations are consistent with Chandra observations.

  14. MAGNETOACOUSTIC WAVE ENERGY FROM NUMERICAL SIMULATIONS OF AN OBSERVED SUNSPOT UMBRA

    SciTech Connect

    Felipe, T.; Khomenko, E.; Collados, M.

    2011-07-01

    We aim at reproducing the height dependence of sunspot wave signatures obtained from spectropolarimetric observations through three-dimensional MHD numerical simulations. A magnetostatic sunspot model based on the properties of the observed sunspot is constructed and perturbed at the photosphere, introducing the fluctuations measured with the Si I {lambda}10827 line. The results of the simulations are compared with the oscillations observed simultaneously at different heights from the He I {lambda}10830 line, the Ca II H core, and the Fe I blends in the wings of the Ca II H line. The simulations show a remarkable agreement with the observations. They reproduce the velocity maps and power spectra at the formation heights of the observed lines, as well as the phase and amplification spectra between several pairs of lines. We find that the stronger shocks at the chromosphere are accompanied with a delay between the observed signal and the simulated one at the corresponding height, indicating that shocks shift the formation height of the chromospheric lines to higher layers. Since the simulated wave propagation matches very well the properties of the observed one, we are able to use the numerical calculations to quantify the energy contribution of the magnetoacoustic waves to the chromospheric heating in sunspots. Our findings indicate that the energy supplied by these waves is too low to balance the chromospheric radiative losses. The energy contained at the formation height of the lowermost Si I {lambda}10827 line in the form of slow magnetoacoustic waves is already insufficient to heat the higher layers, and the acoustic energy which reaches the chromosphere is around 3-9 times lower than the required amount of energy. The contribution of the magnetic energy is even lower.

  15. Effect of stress on energy flux deviation of 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 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 a new nondestructive technique of evaluating stress in composites.

  16. Measurement of Underwater Operational Noise Emitted by Wave and Tidal Stream Energy Devices.

    PubMed

    Lepper, Paul A; Robinson, Stephen P

    2016-01-01

    The increasing international growth in the development of marine and freshwater wave and tidal energy harvesting systems has been followed by a growing requirement to understand any associated underwater impact. Radiated noise generated during operation is dependent on the device's physical properties, the sound-propagation environment, and the device's operational state. Physical properties may include size, distribution in the water column, and mechanics/hydrodynamics. The sound-propagation environment may be influenced by water depth, bathymetry, sediment type, and water column acoustic properties, and operational state may be influenced by tidal cycle and wave height among others This paper discusses some of the challenges for measurement of noise characteristics from these devices as well as a case study of the measurement of radiated noise from a full-scale wave energy converter.

  17. An energy absorbing far-field boundary condition for the elastic wave equation

    SciTech Connect

    Petersson, N A; Sjogreen, B

    2008-07-15

    The authors present an energy absorbing non-reflecting boundary condition of Clayton-Engquist type for the elastic wave equation together with a discretization which is stable for any ratio of compressional to shear wave speed. They prove stability for a second order accurate finite-difference discretization of the elastic wave equation in three space dimensions together with a discretization of the proposed non-reflecting boundary condition. The stability proof is based on a discrete energy estimate and is valid for heterogeneous materials. The proof includes all six boundaries of the computational domain where special discretizations are needed at the edges and corners. The stability proof holds also when a free surface boundary condition is imposed on some sides of the computational domain.

  18. Sub-wavelength energy trapping of elastic waves in a metamaterial.

    PubMed

    Colombi, Andrea; Roux, Philippe; Rupin, Matthieu

    2014-08-01

    Deep sub-wavelength focusing has been demonstrated for locally resonant metamaterials using electromagnetic and acoustic waves. The elastic equivalents of such objects are made of sub-wavelength resonating beams fixed to a two-dimensional plate, as presented here. Independent of a random or regular arrangement of the resonators, the metamaterial shows large bandgaps that are independent of the incident wave direction. Numerical simulations demonstrate that the insertion of a defect in the layout, as a shorter resonator, creates strong amplification of the wave-field on the defect. This energy trapping, which is localized on a spatial scale that is much smaller than the wavelength in the two-dimensional plate, leads to a >1 factor in terms of the local density of energy.

  19. Energy Conversion Process in Laser Supported Detonation Waves Induced by a Line-Focusing Laser

    NASA Astrophysics Data System (ADS)

    Ushio, Masato; Kawamura, Koichi; Komurasaki, Kimiya; Katsurayama, Hiroshi; Koizumi, Hiroyuki; Arakawa, Yoshihiro

    2006-05-01

    Propagation of two-dimensional and quasi-one-dimensional Laser Supported Detonation (LSD) waves driven by a line-focusing laser beam was investigated using the shadowgraph method. As a result, fractional laser absorption during the LSD regime for 2D and quasi-1D cases was 68% and 81%, respectively, which was lower than that of three-dimensional LSD wave driven by a point-focusing beam (typically 90%.) However, the blast wave energy efficiency was found proportional to the fractional absorption. Besides, the LSD threshold intensity was apparently lowered in the quasi-1D case due to the momentum confinement effect. Comparison with the quasi-1D simulation considering the real gas effects suggests that non-equilibrium effects and radiation loss should be playing an important role in the energy conversion process in the LSD regime.

  20. Effect of stress on energy flux deviation of 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 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 a new nondestructive technique of evaluating stress in composites.

  1. Progress Towards the Development of a Traveling Wave Direct Energy Converter for Aneutronic Fusion Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Tarditi, A. G.; Chap, A.; Wolinsky, J.; Scott, J. H.

    2015-01-01

    A coordinated experimental and theory/simulation effort has been carried out to investigate the physics of the Traveling Wave Direct Energy Converter (TWDEC), a scheme that has been proposed in the past for the direct conversion into electricity of the kinetic energy of an ion beam generated from fusion reactions. This effort has been focused in particular on the TWDEC process in the high density beam regime, thus accounting for the ion beam expansion due to its space charge.

  2. Gravitational waves from the first order phase transition of the Higgs field at high energy scales

    NASA Astrophysics Data System (ADS)

    Jinno, Ryusuke; Nakayama, Kazunori; Takimoto, Masahiro

    2016-02-01

    In a wide class of new physics models, there exist scalar fields that obtain vacuum expectation values of high energy scales. We study the possibility that the standard model Higgs field has experienced first order phase transition at the high energy scale due to the couplings with these scalar fields. We estimate the amount of gravitational waves produced by the phase transition, and discuss observational consequences.

  3. Effects of chemical fuel composition on energy generation from thermopower waves

    NASA Astrophysics Data System (ADS)

    Yeo, Taehan; Hwang, Hayoung; Jeong, Dong-Cheol; Lee, Kang Yeol; Hong, Jongsup; Song, Changsik; Choi, Wonjoon

    2014-11-01

    Thermopower waves, which occur during combustion within hybrid structures formed from nanomaterials and chemical fuels, result in a self-propagating thermal reaction and concomitantly generate electrical energy from the acceleration of charge carriers along the nanostructures. The hybrid structures for thermopower waves are composed of two primary components: the core thermoelectric material and the combustible fuel. So far, most studies have focused on investigating various nanomaterials for improving energy generation. Herein, we report that the composition of the chemical fuel used has a significant effect on the power generated by thermopower waves. Hybrid nanostructures consisting of mixtures of picric acid and picramide with sodium azide were synthesized and used to generate thermopower waves. A maximum voltage of ˜2 V and an average peak specific power as high as 15 kW kg-1 were obtained using the picric acid/sodium azide/multiwalled carbon nanotubes (MWCNTs) array composite. The average reaction velocity and the output voltage in the case of the picric acid/sodium azide were 25 cm s-1 and 157 mV, while they were 2 cm s-1 and 3 mV, in the case of the picramide/sodium azide. These marked differences are attributable to the chemical and structural differences of the mixtures. Mixing picric acid and sodium azide in deionized water resulted in the formation of 2,4,6-trinitro sodium phenoxide and hydrogen azide (H-N3), owing to the exchange of H+ and Na+ ions, as well as the formation of fiber-like structures, because of benzene π stacking. The negative enthalpy of formation of the new compounds and the fiber-like structures accelerate the reaction and increase the output voltage. Elucidating the effects of the composition of the chemical fuel used in the hybrid nanostructures will allow for the control of the combustion process and help optimize the energy generated from thermopower waves, furthering the development of thermopower waves as an energy source.

  4. Effects of chemical fuel composition on energy generation from thermopower waves.

    PubMed

    Yeo, Taehan; Hwang, Hayoung; Jeong, Dong-Cheol; Lee, Kang Yeol; Hong, Jongsup; Song, Changsik; Choi, Wonjoon

    2014-11-07

    Thermopower waves, which occur during combustion within hybrid structures formed from nanomaterials and chemical fuels, result in a self-propagating thermal reaction and concomitantly generate electrical energy from the acceleration of charge carriers along the nanostructures. The hybrid structures for thermopower waves are composed of two primary components: the core thermoelectric material and the combustible fuel. So far, most studies have focused on investigating various nanomaterials for improving energy generation. Herein, we report that the composition of the chemical fuel used has a significant effect on the power generated by thermopower waves. Hybrid nanostructures consisting of mixtures of picric acid and picramide with sodium azide were synthesized and used to generate thermopower waves. A maximum voltage of ∼2 V and an average peak specific power as high as 15 kW kg(-1) were obtained using the picric acid/sodium azide/multiwalled carbon nanotubes (MWCNTs) array composite. The average reaction velocity and the output voltage in the case of the picric acid/sodium azide were 25 cm s(-1) and 157 mV, while they were 2 cm s(-1) and 3 mV, in the case of the picramide/sodium azide. These marked differences are attributable to the chemical and structural differences of the mixtures. Mixing picric acid and sodium azide in deionized water resulted in the formation of 2,4,6-trinitro sodium phenoxide and hydrogen azide (H-N3), owing to the exchange of H(+) and Na(+) ions, as well as the formation of fiber-like structures, because of benzene π stacking. The negative enthalpy of formation of the new compounds and the fiber-like structures accelerate the reaction and increase the output voltage. Elucidating the effects of the composition of the chemical fuel used in the hybrid nanostructures will allow for the control of the combustion process and help optimize the energy generated from thermopower waves, furthering the development of thermopower waves as an energy

  5. Full wave dc-to-dc converter using energy storage transformers

    NASA Technical Reports Server (NTRS)

    Moore, E. T.; Wilson, T. G.

    1969-01-01

    Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.

  6. The Potential Energy Density in Transverse String Waves Depends Critically on Longitudinal Motion

    ERIC Educational Resources Information Center

    Rowland, David R.

    2011-01-01

    The question of the correct formula for the potential energy density in transverse waves on a taut string continues to attract attentio