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Sample records for m2 tidal current

  1. Coastal tomographic mapping of nonlinear tidal currents and residual currents

    Science.gov (United States)

    Zhu, Ze-Nan; Zhu, Xiao-Hua; Guo, Xinyu

    2017-07-01

    Depth-averaged current data, which were obtained by coastal acoustic tomography (CAT) July 12-13, 2009 in Zhitouyang Bay on the western side of the East China Sea, are used to estimate the semidiurnal tidal current (M2) as well as its first two overtide currents (M4 and M6). Spatial mean amplitude ratios M2:M4:M6 in the bay are 1.00:0.15:0.11. The shallow-water equations are used to analyze the generation mechanisms of M4 and M6. In the deep area, where water depths are larger than 60 m, M4 velocity amplitudes measured by CAT agree well with those predicted by the advection terms in the shallow water equations, indicating that M4 in the deep area is predominantly generated by the advection terms. M6 measured by CAT and M6 predicted by the nonlinear quadratic bottom friction terms agree well in the area where water depths are less than 20 m, indicating that friction mechanisms are predominant for generating M6 in the shallow area. In addition, dynamic analysis of the residual currents using the tidally averaged momentum equation shows that spatial mean values of the horizontal pressure gradient due to residual sea level and of the advection of residual currents together contribute about 75% of the spatial mean values of the advection by the tidal currents, indicating that residual currents in this bay are induced mainly by the nonlinear effects of tidal currents. This is the first ever nonlinear tidal current study by CAT.

  2. Diffuser Augmented Horizontal Axis Tidal Current Turbines

    Directory of Open Access Journals (Sweden)

    Nasir Mehmood

    2012-09-01

    Full Text Available The renewal energy technologies are increasingly popular to ensure future energy sustenance and address environmental issues. The tides are enormous and consistent untapped resource of renewable energy. The growing interest in exploring tidal energy has compelling reasons such as security and diversity of supply, intermittent but predictable and limited social and environmental impacts. The tidal energy industry is undergoing an increasing shift towards diffuser augmented turbines. The reason is the higher power output of diffuser augmented turbines compared to conventional open turbines. The purpose of this study is to present a comprehensive review of diffuser augmented horizontal axis tidal current turbines. The components, relative advantages, limitations and design parameters of diffuser augmented horizontal axis tidal current turbines are presented in detail. CFD simulation of NACA 0016 airfoil is carried out to explore its potential for designing a diffuser. The core issues associated with diffuser augmented horizontal axis tidal current turbines are also discussed.

  3. On M2 tidal amplitude enhancement in the Taiwan Strait and its asymmetry in the cross-strait direction

    Science.gov (United States)

    Yu, Haiqing; Yu, Huaming; Ding, Yang; Wang, Lu; Kuang, Liang

    2015-10-01

    Enhanced M2 tidal amplitude in the Taiwan Strait (TS) and asymmetric M2 tidal amplitude in the cross-strait direction have been found and reproduced in numerical simulations. In this study, Finite Volume Coastal Ocean Model (FVCOM) is applied to investigate the mechanisms behind these features. Model results show that the linear interaction of waves from the East China Sea (ECS) and the Luzon Strait (LS) can explain the formation of the co-amplitude and co-phase lines of the M2 tide in the nodal point area, while the waves from the ECS dominate the tidal motion in the TS according to a basic linear wave superposition. Model simulation also show that wave reflection and transition occur when the M2 tidal waves from the ECS propagate through the TS and encounter an sharply deepened topography. The interaction of these induced reflection waves and the incident waves from the ECS is the main cause for the enhanced M2 tidal amplitude in the TS. The distribution of the sharply deepened topography, rather than the Coriolis effect, is the main reason for the asymmetry of the M2 tidal amplitude in the cross-strait direction in the TS. These findings provide some references for tidal dynamics in other areas, especially where long waves propagate through the shallow water to the deep sea.

  4. Harnessing Ocean Energy by Tidal Current Technologies

    Directory of Open Access Journals (Sweden)

    Nasir Mehmood

    2012-09-01

    Full Text Available The world is heavily dependent on fossil fuels since most of its energy requirements are fulfilled by conventional methods of burning these fuels. The energy demand is increasing by day with growing population. The energy production by fossil fuels is devastating the environment and survival of life on globe is endangered. The renewal energy technologies are vital to ensure future energy sustenance and environmental issues. Ocean is a vast resource of renewable energy. The technology today makes it possible to extract energy from tides. The growing interest in exploring tidal current technologies has compelling reasons such as security and diversity of supply, intermittent but predictable and limited social and environmental impacts. The purpose of this study is to present a comprehensive review of tidal current technologies to harness ocean energy. The ocean energy resources are presented. The author discusses tidal energy technologies. The tidal current turbines are discussed in detail. The author reviews today’s popular tidal current technologies. The present status of ocean energy development is also reported.

  5. Tidal currents assessment in the Tagus estuary

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, A. (CEHIDRO, Instituto Superior Tecnico, Av. Rovisco Pais, Lisboa, (PT)); Trigo Teixeira, A. (Department of Civil Engineering and Architecture, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, Lisboa (PT))

    2007-07-01

    The authors present in this paper the results of an initial assessment of the potential of tidal currents to generate energy in the Tagus estuary. The work is divided into three phases. The first phase comprises the setting up and calibration of a detailed finite element model for the estuary starting in the ocean boundary. The model was calibrated and verified using water levels and current velocities for several measuring stations within the estuary. The measuring campaign took place in 1987 and was performed by Instituto Hidrografico of the Portuguese Navy. The records are of good quality and cover a period of spring and neap tides. The model give clear indication about the flow pattern within the estuary showing the places were high current velocities are likely to occur. Calculation of the tidal power on selected locations was made. The second phase consisted on the study of the requirements of tidal turbines in terms of site conditions: mainly the minimum water depth and current velocity required for installation. In addition a review was made to understand the development of tidal turbine technology. Three types of turbines were selected as having potential for the site, which usually are associated with moderate current velocity. The third and final phase was the study of the estuary 'map-use' through the construction of a GIS system that allows the identification of locations of potential conflict.

  6. A process study of the interaction of tidal currents, tidal mixing and density gradients in a region of freshwater influence

    Science.gov (United States)

    Xing, Jiuxing; Chen, Shengli

    2017-08-01

    A three dimensional unstructured grid model of the west coast of Britain is used to study the process of the interaction of tidal currents, tidal mixing and density gradient in the Liverpool Bay region. Calculations with M2 tidal forcing and omitting freshwater discharge show that tidal currents in the region are strong (of order 1 ms- 1), with tidal current ellipses essentially rectilinear in the surface and bottom. In the absence of tidal forcing, the freshwater is confined to a thin surface layer. With the inclusion of tidal mixing the surface layer thickens, and in the shallow water area mixed layer occupies the whole water depth. This has a significant effect of reducing its lateral spread. A detailed study of time series of velocity, salinity and turbulence reveals that at flood tide, more saline water is advected into the coastal region and rapid vertical mixing occurs, whereas at ebb tide, fresher water is advected over more saline water. The induced strong pycnocline uncouples surface and bottom layers leading to more circular tidal ellipses which rotate in opposite directions in the vertical, as found in observations. The three dimensional nature of the model reveals that this process involves both horizontal and vertical density gradients, and shows significant horizontal variability in the Liverpool Bay region.

  7. NOAA Tidal Current Data for the Coastal United States

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Knowledge of the timing and strength of tidal currents is extremely important for safe navigation in coastal waters. Tidal currents are almost always the strongest...

  8. NOAA Historical Tidal Current Data for the Coastal United States

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Knowledge of the timing and strength of tidal currents is extremely important for safe navigation in coastal waters. Tidal currents are almost always the strongest...

  9. Diurnal and semi-diurnal tidal currents in the deep mid-Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Gouveia, A.D.; Shetye, S.R.

    been determined using the currents recorded at hourly intervals during May 1986-May 1987. The clockwise rotating M2 tidal currents were the strongest. The maximum horizontal velocities due to M2, S2 and K1 tides were 2.2 cm/s, 1.0 cm/s and 0.89 cm...

  10. Study on the Tidal Wave System and Formation Mechanism of M2 Tide in the Taiwan Strait

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-sheng; SONG Zhi-yao; ZHANG Jin-shan; ZHANG Hong-gui; KONG Jun; WANG Yan-hong

    2008-01-01

    To study the Taiwan Strait (TS), an unusual sea area, the numerical model in marginal seas of China is used to simulate and analyze the tidal wave motion in the strait. The numerical modeling experiments reproduce the amphidromic system of the M2 tide in the south end of the Taiwan strait, and consequently confirm the existence of the degenerate amphidromic system. On this basis, further discussion is conducted on the M2 system and its formation mechanism. It can be concluded that the tidal waves of the TS is consisted of the progressing wave from the north entrance and the degenerate amphidromic system from the south entrance, in which the progressing wave from the north entrance dominates the tidal wave motion in the strait. Except for the convergent effect caused by the landform and boundary, the degenerate amphidromic system produced in the south of the strait is another important factor for the following phenomena: the large tidal range in the middle of the strait, the concentrative zone of co-amplitude and co-phase line in the south of the strait. The degenerate amphidromic system is mainly produced by the incident Pacific Ocean tidal wave from the Luzon strait and the action by the shoreline and landform. The position of the amphidromic point is compelled to move toward southwest until degenerating by the powerful progressing wave from the north entrance.

  11. Numerical study on tidal currents and seawater exchange in the Benoa Bay, Bali, Indonesia

    Institute of Scientific and Technical Information of China (English)

    HENDRAWAN I. Gede; ASAI Koji

    2014-01-01

    A three-dimensional (3-D) finite volume coastal ocean model (FVCOM) was used for the study of water cir-culation and seawater exchange in the Benoa Bay, Bali Island. The M2 tidal component was forced in open boundary and discharge from six rivers was included in the numerical calculation. The M2 tidal elevation produced by the FVCOM has a good agreement with the observation data. The M2 tidal current is also suc-cessfully calculated under the ebb tide and flood tide conditions. The non-linear M2 tidal residual current was produced by the coastline geometry, especially surrounding the narrow strait between the Serangan Is-land and the Benoa Peninsula. The tidal residual current also generated two small eddies within the bay and one small eddy in the bay mouth. The salinity distribution influenced by river discharge could be success-fully calculated, where the numerical calculation and the observation results have a good correlation (r2) of 0.75. Finally in order to examine the seawater exchange in the Benoa Bay, the Lagrangian particle tracking method and calculation of residence time are applied. The mechanism of particle transport to the flushing of seawater is depicted clearly by both methods.

  12. Seasonal variability of tidal and non-tidal currents off Beypore, SW coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    DineshKumar, P.K.; Srinivas, K.; AnilKumar, N.

    Analyses of current meter records generated in the coastal waters off Beypore (11 degrees 10 minutes S; 75 degrees 48 minutes E) on the southwest coast of India have been made to understand the tidal and non-tidal variability during premonsoon...

  13. Can Tidal Current Energy Provide Base Load?

    Directory of Open Access Journals (Sweden)

    Simone Giorgi

    2013-06-01

    Full Text Available Tidal energy belongs to the class of intermittent but predictable renewable energy sources. In this paper, we consider a compact set of geographically diverse locations, which have been assessed to have significant tidal stream energy, and attempt to find the degree to which the resource in each location should be exploited so that the aggregate power from all locations has a low variance. An important characteristic of the locations chosen is that there is a good spread in the peak tidal flow times, though the geographical spread is relatively small. We assume that the locations, all on the island of Ireland, can be connected together and also assume a modular set of tidal turbines. We employ multi-objective optimisation to simultaneously minimise variance, maximise mean power and maximise minimum power. A Pareto front of optimal solutions in the form of a set of coefficients determining the degree of tidal energy penetration in each location is generated using a genetic algorithm. While for the example chosen the total mean power generated is not great (circa 100 MW, the case study demonstrated a methodology that can be applied to other location sets that exhibit similar delays between peak tidal flow times.

  14. Tidal currents in the Yucatan Channel

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo Gonzalez, Fatima [Centro Universitario de la Costa, Universidad de Guadalajara, Guadalajara, Jalisco (Mexico); Ochoa, Jose; Candela, Julio; Badan, Antonio; Sheinbaum; Gonzalez Navarro, Juan Ignacio [Departamento de Oceanografia Fisica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Ensenada, Baja California (Mexico)

    2007-07-15

    Currents data from a ten-month period at 197 measuring points covering all Yucatan Channel were processed by harmonic analysis to estimate tidal parameters for the O{sub 1}, K{sub 1}, M{sub 2} and S{sub 2} components. The highly detailed coverage confirms the known dominance for the O{sub 1} and K{sub 1} diurnal components, but also showed, for the first time, their intensification in the deep eastern margin of the channel where maximum amplitudes in main axis are 17 and 19 cm.s{sup -}1. The data also confirms weak semi-diurnal components, of which the most intense, M{sub 2} and S{sub 2}, have amplitudes only up to 2 cm.s{sup -}1. The tidal ellipses were elongated (i.e. with eccentricities close to one) in the NNW direction. The O{sub 1}, K{sub 1}, M{sub 2} and S{sub 2} contributions in transport variability through the channel have amplitudes of 11.7, 12.5, 1.2 and 1.0 Sv, all well determined above noise. [Spanish] Se presentan, a detalle sin precedente, las caracteristicas de las corrientes de marea O{sub 1}, K{sub 1}, M{sub 2} y S{sub 2} en el canal de Yucatan. Mapas de los parametros que definen las elipses, como son las amplitudes en los ejes principales, la orientacion, la fase y la razon-senal-ruido se obtienen, por el clasico analisis armonico en mediciones de 10 meses en duracion, en 197 puntos que cubren ampliamente un plano vertical del canal. En acuerdo con reportes anteriores, las senales diurnas O{sub 1} y K{sub 1} dominan, demostrandose aqui que sus amplitudes alcanzan, en la parte profunda y Este, 17 y 19 cm.s{sup -}1. El analisis tambien revela senales semidiurnas M{sub 2} y S{sub 2} muy debiles con amplitudes maximas de 2 y 1cm.s{sup -}1. Las elipses son muy alargadas (i.e. con excentricidad cercana a uno) y orientadas al nornoroeste. Los valores de la razon senal a ruido indican que los parametros de las dos constituyentes diurnas se encuentran bien determinados, mientras que las semidiurnas quedan muy contaminadas por el ruido. El rasgo mas

  15. Optimal Selection of Floating Platform for Tidal Current Power Station

    Directory of Open Access Journals (Sweden)

    Fengmei Jing

    2013-06-01

    Full Text Available With continuous development of marine engineering, more and more new structures are used in the exploring of tidal current energy. Three are there different kinds of support structures for tidal current power station, which are sea-bed mounted/gravity based system, pile mounted system and floating moored platform. Comparison with them, the floating mooring system is suit for deep water and the application of which will be widely. In this study, catamaran and semi-submersible as floating platform of tidal current power station are studied. And they are compared with its economic, efficiency of turbine and stability of station. It is found that the catamaran is optimal choice. Based on basic ship theory and using software MOSES, the stability of Catamaran tidal current power station is also calculated. The research of this study is significant and it will be as the reference for the future study.

  16. Inversion of two-dimensional tidal open boundary conditions of M2 constituent in the Bohai and Yellow Seas

    Institute of Scientific and Technical Information of China (English)

    CAO Anzhou; GUO Zheng; L(U) Xianqing

    2012-01-01

    Two-dimensional tidal open boundary conditions of the M2 constituent in the Bohai and Yellow Seas(BYS)have been estimated by assimilating T/P altimeter data.During inversion,independent point (IP)strategy was used,in which several IPs on the open boundary is assumed,values at these IPs can be optimized with an adjoint method,and those at other grid points are determined by linearly interpolating the values at IPs.The reasonability and feasibility of the model are tested by ideal twin experiments.In the practical experiment(PE)after assimilation,the cost function may reach 1% or less of its initial value.Mean absolute errors in amplitude and phase can be less than 5 cm and 5°,respectively,and the obtained co-chart can show the character of the M2 constituent in the BYS.The results of the PE indicate that using only two IPs on the open boundary can yield better simulated results.

  17. Tidal elevation, current, and energy flux in the area between the South China Sea and Java Sea

    Science.gov (United States)

    Wei, Zexun; Fang, Guohong; Dwi Susanto, R.; Rameyo Adi, Tukul; Fan, Bin; Setiawan, Agus; Li, Shujiang; Wang, Yonggang; Gao, Xiumin

    2016-04-01

    The South China Sea (SCS) and the Java Sea (JS) are connected through the Karimata Strait, Gaspar Strait, and the southern Natuna Sea, where the tides are often used as open boundary condition for tidal simulation in the SCS or Indonesian seas. Tides, tidal currents, and tidal energy fluxes of the principle constituents K1, O1, Q1, M2, S2, and N2 at five stations in this area have been analyzed using in situ observational data. The results show that the diurnal tides are the dominant constituents in the entire study area. The constituent K1 has the largest amplitude, exceeding 50 cm, whereas the amplitudes of M2 are smaller than 5 cm at all stations. The amplitudes of S2 may exceed M2 in the Karimata and Gaspar straits. Tidal currents are mostly of rectilinear type in this area. The semi-major axes lengths of the diurnal tidal current ellipses are about 10 cm s-1, and those of the semidiurnal tidal currents are smaller than 5 cm s-1. The diurnal tidal energy flows from the SCS to the JS. The semidiurnal tidal energy flows from the SCS to the JS through the Karimata Strait and the eastern part of the southern Natuna Sea but flows in the opposite direction in the Gaspar Strait and the western part of the southern Natuna Sea. Harmonic analysis of sea level and current observation also suggest that the study area is located in the antinodal band of the diurnal tidal waves, and in the nodal band of the semidiurnal tidal waves. Comparisons show that the existing models are basically consistent with the observational results, but further improvements are necessary.

  18. 3-D Simulation of Vertical-Axial Tidal Current Turbine

    Directory of Open Access Journals (Sweden)

    Zhiyang Zhang

    2016-12-01

    Full Text Available Vertical-axial tidal current turbine is the key for the energy converter, which has the advantages of simple structure, adaptability to flow and uncomplex convection device. It has become the hot point for research and application recently. At present, the study on the hydrodynamic performance of vertical-axial tidal current turbine is almost on 2-D numerical simulation, without the consideration of 3-D effect. CFD (Computational Fluid Dynamics method and blade optimal control technique are used to improve accuracy in the prediction of tidal current turbine hydrodynamic performance. Numerical simulation of vertical-axial tidal current turbine is validated. Fixed and variable deflection angle turbine are comparatively studied to analysis the influence of 3-D effect and the character of fluid field and pressure field. The method, put the plate on the end of blade, of reduce the energy loss caused by 3-D effect is proposed. The 3-D CFD numerical model of vertical-axial tidal current turbine hydrodynamic performance in this study may provide theoretical, methodical and technical reference for the optimal design of turbine.

  19. Tidal and residual currents in the Bransfield Strait, Antarctica

    Directory of Open Access Journals (Sweden)

    O. López

    Full Text Available During the 1992-1993 oceanographic cruise of the Spanish R/V Hespérides, recording equipment was deployed in the Bransfield Strait. Six Aanderaa RCM7 current meters and three Aanderaa WLR7 tide gauges were successfully recovered after an operation period of 2.5 months. Relevant features of the time series obtained are presented and discussed in this paper. The emphasis is placed on the tidal character of the currents and the relative importance of tidal flow in the general hydrodynamics of the strait. For these purposes a dense grid of hydrographic stations, completed during the BIOANTAR 93 cruise, is used. Preliminary geostrophic calculations relative to a 400 m depth, yield current velocities of around 0.20 m s-1 in the study area, whereas the magnitude of tidal currents is seen to be 0.30-0.40 m s-1.

  20. Combined tidal and wind driven flows and residual currents

    Science.gov (United States)

    Holmedal, Lars Erik; Wang, Hong

    2015-05-01

    The effect of a residual current on the combined tidal and wind driven flow and the resulting bedload sediment transport in the ocean has been investigated, using a simple one dimensional two-equation turbulence closure model. Predictions of the combined tidal and wind driven flow with given residual currents are presented, showing that the residual current has a substantial effect on both the depth averaged mass transport and the mean bedload transport directions; in some cases the effect of the residual current is to almost reverse the mean bedload transport direction. The residual current affects the rotation of the flow due to the Coriolis effect in the lower part of the water column (the near-surface flow is wind dominated), causing a larger or smaller clockwise rotation of the depth averaged mass transport, depending on the direction of the residual current.

  1. Application of adjoint assimilation technique in simulating tides and tidal currents of the Bohai Sea, the Yellow Sea and the East China Sea

    Institute of Scientific and Technical Information of China (English)

    Cheng Yongcun; Lu Xianqing; Liu Yuguang; Xu Qing

    2007-01-01

    Considering the interaction of different tidal waves, an adjoint numerical model is developed to simulate M2, S2, K1 and O1 tidal waves in the Bohai Sea, the Yellow Sea and the East China Sea(B-Y-E) simultaneously. Compared with previous researches, by using the adjoint assimilation technique to inverse open boundary conditions and bottom friction coefficients based on altimetric data from TOPEX/Poseidon (T/P)and tidal gauges data, the precision of the numerical simulation is significantly improved. Selecting 14 days of simulated results after t11e initial warming run to conduct harmonic analysis, the results can show the characteristics of M2, S2, K1 and O1 tidal wave systems perfectly in B-Y-E. Compared with 9 current stations, the calculated harmonic constants of tidal currents for M2 and K1 are in good agreement With the observed ones.

  2. Tidal power harnessing energy from water currents

    CERN Document Server

    Lyatkher, Victor

    2014-01-01

    As the global supply of conventional energy sources, such as fossil fuels, dwindles and becomes more and more expensive, unconventional and renewable sources of energy, such as power generation from water sources, is becoming more and more important.  Hydropower has been around for decades, but this book suggests new methods that are more cost-effective and less intrusive to the environment for creating power sources from rivers, the tides, and other sources of water.   The energy available from water currents is potentially much greater than society's needs.  Presenting a detailed discussi

  3. Extraction of Internal Tidal Currents from A Portion of Sea Current Profile

    Institute of Scientific and Technical Information of China (English)

    韩春明; 潘增弟; 范典

    2002-01-01

    Internal tide is one of the major oceanic phenomena. Determination of internal tide is important for theoretical studyand for ocean engineering research. As an inverse problem, extraction of internal tidal currents from sea currents is diffi-cult. In this paper, a method is developed to extract internal tidal currents from a portion of the sea current profile basedon the fact that the directions of internal tidal currents above and below the thermocline are inverse. Sea current data col-lected from the South China Sea is processed with this method. The internal tidal currents and the depth of the thermo-cline are successfully extracted. The depth of the thermocline determined is in good agreement with that measured in 1959.

  4. Sediment Dynamics in Shallow Tidal Landscapes: The Role of Wind Waves and Tidal Currents

    Science.gov (United States)

    Carniello, L.; D'Alpaos, A.

    2014-12-01

    A precise description of sediment dynamics (resuspension and re-distribution of sediments) is crucial when investigating the long term evolution of the different morphological entities characterizing tidal landscapes. It has been demonstrated that wind waves are the main responsible for sediment resuspension in shallow micro-tidal lagoons where tidal currents, which produce shear stresses large enough to carry sediments into suspension only within the main channels, are mainly responsible for sediment redistribution. A mathematical model has been developed to describe sediment entrainment, transport and deposition due to the combined effect of tidal currents and wind waves in shallow lagoons considering both cohesive and non-cohesive sediments. The model was calibrated and tested using both in situ point observations and turbidity maps obtained analyzing satellite images. Once calibrated the model can integrate the high temporal resolution of point observations with the high spatial resolution of remote sensing, overcoming the intrinsic limitation of these two types of observations. The model was applied to the specific test case of the Venice lagoon simulating an entire year (2005) which was shown to be a "representative" year for wind and tide characteristics. The time evolution of the computed total bottom shear stresses (BSS) and suspended sediment concentration (SSC) was analyzed on the basis of a "Peaks Over Threshold" method once a critical value for shear stress and turbidity were chosen. The analyses of the numerical results enabled us to demonstrate that resuspension events can be modeled as marked Poisson processes: interarrival time, intensity of peak excesses and duration being exponentially distributed random variable. The probability distributions of the interarrival time of overthreshold exceedances in both BSS and SSC as well as their intensity and duration can be used in long-term morphodynamic studies to generate synthetic series statistically

  5. Monitoring Tidal Currents with a Towed ADCP System

    Science.gov (United States)

    2015-12-22

    throughout the water column were corrected for boat motion, using both bottom-tracking and GPS coordinates available at 1-s resolution, and then...successful selection of technology and devices to be deployed. However, site selection is not simply a case of identifying areas with strong tidal currents... Naval Research Laboratory, Stennis Space Center, Bldg. 1009, Mississippi, MS 39529, USA Ocean Dynamics (2016) 66:119–132 DOI 10.1007/s10236-015-0913-z

  6. Canada ocean energy atlas phase 1 : potential tidal current energy resources analysis background

    Energy Technology Data Exchange (ETDEWEB)

    Tarbotton, M.; Larson, M. [Triton Consultants Ltd., Vancouver, BC (Canada)

    2006-05-15

    This report was prepared as a background document for a preliminary tidal current resource inventory for Canadian waters. Energy calculations in the study were based on preliminary estimates of known tidal flows. The inventory was based on nautical charts, Canadian sailing directions, tide and tidal current constituent data, and numerical tidal modelling data. A finite element harmonic tidal model tool was used to provide tidal height and current velocities data for a varying number of tidal constituents. The study identified several major tidal current power resources throughout Canada. It was concluded that modelling studies should concentrate on Minas Basin in Nova Scotia; Georgia and Johnstone Straits in British Columbia; and Hudson's Strait and Ungava Bay. Modelling studies should provide estimates of extractable energy as well as provide initial assessments of the environmental impacts of tidal energy extraction in all 3 regions. 3 refs., 8 tabs., 16 figs.

  7. Tide and tidal current observation in the Karimata Strait

    Science.gov (United States)

    Wei, Zexun; Fang, Guohong; Sulistiyo, Budi; Dwi Susanto, R.; Setiawan, Agus; Rameyo Adi, Tukul; Qiao, Fangli; Fan, Bin; Li, Shujiang

    2013-04-01

    It is believed that the water exchanges between the South China Sea and the Indonesian Seas are significant, and play an important role in the water mass formation and air-sea interactions of both the South China Sea and Indonesian Seas. It has also been found that the current in Sunda Strait has been obvious seasonal variation, which indicates the water exchange between West Indonesian Seas and India Ocean. In order to make quantitative evaluation of the magnitudes of the exchange, the First Institute of Oceanography (FIO), China, the Agency for Marine and Fisheries Research, Indonesia, and the Lamont-Doheries Earth Observatory, USA established a collaborative program, "The South-China Sea-Indonesian Seas Transport/Exchange (SITE) and Impacts on Seasonal Fish Migration" in 2006. And, they extend and expand the cooperation to Sunda Strait in 2008, the title of the collaborative program was changed to "The South China Sea - Indonesian Seas Transport/Exchange (SITE) and Dynamics of Sunda and Lombok Straits, and Their Impacts on Seasonal Fish Migration". Till now, 12 joint cruises have been conducted since December, 2007. Ten Trawl-Resistant Bottom Mounts (TRBM) have been deployed in the Karimata and Sunda Straits. The TRBMs are equipped with ADCPs and tide gauges for measuring current profiles and sea levels, respectively. The temperature-salinity profiles were measured with ship-board CTD during the cruises. Data obtained in Karimata Strait revealed that a significant water mass transport. This indicates that the Karimata Strait throughflow can greatly impacts the circulation of both the South China Sea and the Indonesian Seas. The data obtained at the 5 stations alone the two sections in the Karimata Strait were used to study the tide and tidal currents in the Karimata Strait. 2 TRBMs were deployed at Section A, as well as 3 at Section B, which lies at the southeast of Section A. Station B1 is in the Gaspar Strait between Bangka Island and Belitung Island, Stations

  8. Tidal residual current and its role in the mean flow on the Changjiang Bank

    Energy Technology Data Exchange (ETDEWEB)

    Xuan, Jiliang; Yang, Zhaoqing; Huang, Daji; Wang, Taiping; Zhou, Feng

    2016-02-01

    Tidal residual current may play an important role in the mean flow in the Changjiang Bank region, in addition to other residual currents, such as the Taiwan Warm Current, the Yellow Sea Coastal Current, and the Yellow Sea Warm Current. In this paper, a detailed structure of the tidal residual current, in particular the meso-scale eddies, in the Changjiang Bank region is observed from model simulations, and its role in the mean flow is quantified using the well-validated Finite Volume Coastal Ocean Model). The tidal residual current in the Changjiang Bank region consists of two components: an anticyclonic regional-scale tidal residual circulation around the edge of the Changjiang Bank and some cyclonic meso-scale tidal residual eddies across the Changjiang Bank. The meso-scale tidal residual eddies occur across the Changjiang Bank and contribute to the regional-scale tidal residual circulation offshore at the northwest boundary and at the northeast edge of the Changjiang Bank, southeastward along the 50 m isobath. Tidal rectification is the major mechanism causing the tidal residual current to flow along the isobaths. Both components of the tidal residual current have significant effects on the mean flow. A comparison between the tidal residual current and the mean flow indicates that the contribution of the tidal residual current to the mean flow is greater than 50%.

  9. Tidal current turbine based on hydraulic transmission system

    Institute of Scientific and Technical Information of China (English)

    Hong-wei LIU; Wei LI; Yong-gang LIN; Shun MA

    2011-01-01

    Tidal current turbines (TCTs) are newly developed electricity generating devices.Aiming at the stabilization of the power output of TCTs,this paper introduces the hydraulic transmission technologies into TCTs.The hydrodynamics of the turbine was analyzed at first and its power output characteristics were predicted.A hydraulic power transmission system and a hydraulic pitch-controlled system were designed.Then related simulations were conducted.Finally,a TCT prototype was manufactured and tested in the workshop.The test results have confirmed the correctness of the current design and availability of installation of the hydraulic system in TCTs.

  10. Monitoring tidal currents with a towed ADCP system

    Science.gov (United States)

    Sentchev, Alexei; Yaremchuk, Max

    2016-01-01

    The tidal circulation in the semi-enclosed Boulogne harbour (eastern English Channel) is measured during the various stages of the tidal cycle with a low-cost towed Acoustic Doppler Current Profiler (ADCP) system for the first time. The system is equipped with an interpolation algorithm which allows reconstructing space-time evolution of the velocity field for surveys whose duration is comparable or larger than the typical time of tidal variation (1-2 h). The method employs space-time velocity covariances derived from a numerical simulation of the surveyed area by a high-resolution relocatable model "Model for Applications on Regional Scale" (MARS). The covariances are utilized by the optimal interpolation algorithm to obtain the most likely evolution of the velocity field under the constraints provided by the ADCP observations and their error statistics. Technically, the MARS model run provides the first guess (background) evolution of the velocity field in the surveyed area which is then corrected by the data in a statistically consistent manner as it explicitly takes into the account both observational and modeling errors. The quality of the velocity reconstruction was validated against independent bottom-mounted ADCP data, the background model evolution, and against the results of spatial interpolation by Kriging technique. All tests demonstrated significant (30 to 60 %) reduction of the model-data misfit for the velocity field obtained as a result of space-time optimal interpolation. Although the method was applied to recover surface circulation, it can be extended for assessment of the full 4D tidal flow dynamics using the data recorded throughout the entire water column.

  11. Recent TCP(Tidal Current Power) projects in Korea

    Institute of Scientific and Technical Information of China (English)

    Chul; Hee; JO; Kang; Hee; LEE; Yu; Ho; RHO

    2010-01-01

    Having strong current on the west coast with up to 10 m tidal range in Korea,there are many suitable and applicable locations for TCP(Tidal Current Power) application in Korea.Not only the west coast,but also the south west regions having narrow channels between islands creating fast ocean stream are suitable for TCP.The first TCP application in Korea is 1 MW helical VAT(Vertical Axis Turbine) device installed in Wooldolmog area in 2008.The first HAT(Horizontal Axis Turbine) TCP device of 25 KW was developed and installed in cooling water weir of Samchonpo power plant in 2008.Furthermore,a 100 kW prototype HAT TCP device is being planned to be installed in Daebang strait in 2009.Another big project would be Inchon TCP farm of 200 MW on the west coast in Korea.The consortium of 5 members was formed in April,2009.This site will be the largest TCP site in the world.The paper describes recent TCP projects in Korea with background and environmental conditions of the projects.

  12. Dynamics of tidal and non-tidal currents along the southwest continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Aruna, C.; Ravichandran, C.; Srinivas, K.; Rasheed, P.A.A; Lekshmi, S.

    are predominantly mixed, semidiurnal in nature. Motion over any continental shelf is governed by the tide-driven oscillatory flow. In this paper, tidal and non-tidal characteristics of the waters of Southwest continental shelf of India are assessed using...

  13. New Concept for Assessment of Tidal Current Energy in Jiangsu Coast, China

    Directory of Open Access Journals (Sweden)

    Ji-Sheng Zhang

    2013-01-01

    Full Text Available Tidal current energy has attracted more and more attentions of coastal engineers in recent years, mainly due to its advantages of low environmental impact, long-term predictability, and large energy potential. In this study, a two-dimensional hydrodynamic model is applied to predict the distribution of mean density of tidal current energy and to determine a suitable site for energy exploitation in Jiangsu Coast. The simulation results including water elevation and tidal current (speed and direction were validated with measured data, showing a reasonable agreement. Then, the model was used to evaluate the distribution of mean density of tidal current energy during springtide and neap tide in Jiangsu Coast. Considering the discontinuous performance of tidal current turbine, a new concept for assessing tidal current energy is introduced with three parameters: total operating time, dispersion of operating time, and mean operating time of tidal current turbine. The operating efficiency of tidal current turbine at three locations around radial submarine sand ridges was taken as examples for comparison, determining suitable sites for development of tidal current farm.

  14. Design of Bi-Directional Hydrofoils for Tidal Current Turbines

    Science.gov (United States)

    Nedyalkov, Ivaylo; Wosnik, Martin

    2015-11-01

    Tidal Current Turbines operate in flows which reverse direction. Bi-directional hydrofoils have rotational symmetry and allow such turbines to operate without the need for pitch or yaw control, decreasing the initial and maintenance costs. A numerical test-bed was developed to automate the simulations of hydrofoils in OpenFOAM and was utilized to simulate the flow over eleven classes of hydrofoils comprising a total of 700 foil shapes at different angles of attack. For promising candidate foil shapes physical models of 75 mm chord and 150 mm span were fabricated and tested in the University of New Hampshire High-Speed Cavitation Tunnel (HiCaT). The experimental results were compared to the simulations for model validation. The numerical test-bed successfully generated simulations for a wide range of foil shapes, although, as expected, the k - ω - SST turbulence model employed here was not adequate for some of the foils and for large angles of attack at which separation occurred. An optimization algorithm is currently being coupled with the numerical test-bed and additional turbulence models will be implemented in the future.

  15. Carrier Current Line Systems Technologies in M2M Architecture for Wireless Communication

    Directory of Open Access Journals (Sweden)

    Hua-Ching Chen

    2016-01-01

    Full Text Available This paper investigates the Carrier Current Line Systems (CCLS technologies of Machine to Machine (M2M architecture which applied for mobile station coverage working with metro, high speed railway, and subway such as analysis for public transport of an indoor transition system. It is based on the theory and practical engineering principle which provide guidelines and formulas for link budget design to help designers fully control and analyze the single output power of uplink and downlink between Fiber Repeaters (FR and mobile station as well as base station. Finally, the results of this leakage cable system are successfully applied to indoor coverage design for metro rapid transit system which are easily installed cellular over fiber solutions for WCDMA/LTE access is becoming Ubiquitous Network to Internet of Thing (IOT real case hierarchy of telecommunication.

  16. Numerical modelling of tides and tidal currents in the Gulf of Kutch

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    An application of a two-dimensional tidal model to study the tidal regime in the Gulf of Kutch is made. This is with a view to synthesise various information on tides and currents that are available in the Gulf. A comparison of surface elevations...

  17. Survey on utility technology of a tidal and ocean current energy

    Science.gov (United States)

    Hirose, Manabu; Kadoyu, Masataka; Tanaka, Hiroyoshi

    1987-06-01

    A study is made to show the current technological levels in Japan and other nations regarding the conversion of tidal current or ocean current energy to electric power and to determine the latent energy quantities and energy-related characteristics of tidal and ocean currents. In Japan, relatively large-scale experiments made so far mostly used one of the following three types of devices: Savonius-wheel type, Darrieus-wheel type, and cross-flow-wheel type. Field experiments of tidal energy conversion have been performed at the Naruto and Kurushima Straits. The energy in the Kuroshio current is estimated at about 170 billion kWh per year. Ocean current energy does not undergo large seasonal variations. The total energy in major straits and channels in the Inland Sea and other sea areas to the west is estimated at about 124 billion kWh per year. Tidal current energy shows large seasonal variations, but it is possible to predict the changes. A survey is made to determine energy-related characteristics of a tidal current at Chichino-seto, Kagoshima Prefecture. At Chichino-seto, the flow velocity ranges from 0 to 2.2m/s, with a latent tidal current energy of about 70 kW, of which about 20 kW can actually be utilized.

  18. Development, installation and testing of a large-scale tidal current turbine

    Energy Technology Data Exchange (ETDEWEB)

    Thake, J.

    2005-10-15

    This report summarises the findings of the Seaflow project to investigate the feasibility of building and operating a commercial scale marine current horizontal axis tidal turbine and to evaluate the long-term economics of producing electricity using tidal turbines. Details are given of competitive tidal stream technologies and their commercial status, the selection of the site on the North Devon coast of the UK, and the evaluation of the turbine design, manufacture, testing, installation, commissioning, and maintenance of the turbine. The organisations working on the Seaflow project and cost estimations are discussed.

  19. Sand-Mud Sediment Transport induced by tidal currents and wind waves in shallow microtidal basins

    Science.gov (United States)

    Carniello, L.; Defina, A.; D'Alpaos, L.

    2011-12-01

    Field data and mathematical modeling have demonstrated that the morphological evolution of shallow tidal basins is the result of the combined effect of tidal currents and wind waves. Tidal currents, in particular, drive the morphological evolution of shallow tidal systems in proximity of the inlets and within the channel network, whereas in shallow areas tidal current mainly acts enhancing the bottom shear stress due to wind waves and redistributing sediments within the basin. In this study we present a mathematical model for sediment entrainment, transport and deposition due to the combined effect of tidal currents and wind waves. The model is coupled with a hydrodynamic module based on the shallow water equations and with a module for the generation and propagation of wind waves. The sediment transport model describes the sediments by the way of a bi-granular mixtures composed by both cohesive and non-cohesive sediments thus considering the contemporary presence of clay, silt and sand which usually characterizes estuaries and tidal basins. Moreover, the model describes the bed evolution and evaluates the variation of bed sediment composition considering also the transition between cohesive and non-cohesive behavior. Attention is focused on some issues concerning the definition of a reliable initial bed composition and the incipient sediment motion which is treated following a stochastic approach for the bottom shear stress and for the critical shear stress distribution. The model is applied to the Lagoon of Venice (Italy) and the results of different simulations are compared, with good agreement, to a series of turbidity measurements collected inside the lagoon. The application of the model to the present bathymetry of the Venice lagoon allows for a first estimation of the actual net amount of sand and mud flowing through the three inlets and also gives some information on bottom evolution in terms of elevation and composition.

  20. Assessment of Power Potential of Tidal Currents and Impacts of Power Extraction on Flow Conditions in Indonesia

    Science.gov (United States)

    Orhan, Kadir; Mayerle, Roberto

    2017-04-01

    Climate change is an urgent and potentially irreversible threat to human societies and the planet and thus requires an effective and appropriate response, with a view to accelerating the reduction of global greenhouse gas emissions. At this point, a worldwide shift to renewable energy is crucial. In this study, a methodology comprising of the estimates of power yield, evaluation of the effects of power extraction on flow conditions, and near-field investigations to deliver wake characteristics, recovery and interactions is described and applied to several straits in Indonesia. Site selection is done with high-resolution, three-dimensional flow models providing sufficient spatiotemporal coverage. Much attention has been given to the meteorological forcing, and conditions at the open sea boundaries to adequately capture the density gradients and flow fields. Model verifications using tidal records show excellent agreement. Sites with adequate depth for the energy conversion using horizontal axis tidal turbines, average kinetic power density greater than 0.5 kW/m2, and surface area larger than 0.5km2 are defined as energy hotspots. Spatial variation of the average extractable electric power is determined, and annual tidal energy resource is estimated for the straits in question. The results showed that the potential for tidal power generation in Indonesia is likely to exceed previous predictions reaching around 4,800MW. Models with higher resolutions have been developed to assess the impacts of devices on flow conditions and to resolve near-field turbine wakes in greater detail. The energy is assumed to be removed uniformly by sub-grid scale arrays of turbines. An additional drag force resulting in dissipation of the pre-existing kinetic power from 10% to 60% within a flow cross-section is introduced to capture the impacts. k-ɛ model, which is a second order turbulence closure model is selected to involve the effects of the turbulent kinetic energy and turbulent

  1. Corrected Formula of Bed Resistance Coefficient for Plane Numerical Simulation of Tidal Current

    Institute of Scientific and Technical Information of China (English)

    宋志尧; 刘一凡

    2000-01-01

    By means of a logarithm law for the velocity profile, a corrected formula of bed resistance coefficient, which involves many factors such as gradient of still water depth, variation of surface elevation, flow direction, and so on, is derived from the 3D governing equations of tidal current by averaging over the whole water depth. Theoretical analysis and application have shown that the 2D plane tidal current numerical model would be more reasonable and could be applied to steep bottom topography when the corrected bed resistance coefficient is used, therefore the results of reproduction simulation and engineering calculation would be more scientific and reasonable.

  2. A study on the interference effects for tidal current power rotors

    Institute of Scientific and Technical Information of China (English)

    Chul-Hee; JO; Kang-Hee; LEE; Jin-Young; YIM

    2010-01-01

    Due to global warming, the need to secure an alternative resource has become more important nationally. With the high tidal range of up to 9.7 m on the west coast of Korea, numerous tidal current projects are being planned and constructed. To extract a significant quantity of power, a tidal current farm with a multi-arrangement is necessary in the ocean. The rotor, which initially converts the energy, is a very important component because it affects the efficiency of the entire system, and its performance is determined by various design variables. The power generation is strongly dependent on the size of the rotor and the incoming flow velocity. However, the interactions between devices also contribute significantly to the total power capacity. Therefore, rotor performance considering the interaction problems needs to be investigated for generating maximum power in a specific field. This paper documents a performance study of devices considering the interference between rotating rotors with axial, transverse and diagonal arrangements.

  3. Feasibility of Tidal and Ocean Current Energy in False Pass, Aleutian Islands, Alaska final report

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Bruce Albert [Aleutian Pribilof Islands Association, Inc., Anchorage, AK (United States)

    2014-05-07

    The Aleutian Pribilof Islands Association was awarded a U.S. Department of Energy Tribal Energy Program grant (DE-EE0005624) for the Feasibility of Tidal and Ocean Current Energy in False Pass, Aleutian Islands, Alaska (Project). The goal of the Project was to perform a feasibility study to determine if a tidal energy project would be a viable means to generate electricity and heat to meet long-term fossil fuel use reduction goals, specifically to produce at least 30% of the electrical and heating needs of the tribally-owned buildings in False Pass. The Project Team included the Aleut Region organizations comprised of the Aleutian Pribilof Island Association (APIA), and Aleutian Pribilof Island Community Development Association (APICDA); the University of Alaska Anchorage, ORPC Alaska a wholly-owned subsidiary of Ocean Renewable Power Company (ORPC), City of False Pass, Benthic GeoScience, and the National Renewable Energy Laboratory (NREL). The following Project objectives were completed: collected existing bathymetric, tidal, and ocean current data to develop a basic model of current circulation at False Pass, measured current velocities at two sites for a full lunar cycle to establish the viability of the current resource, collected data on transmission infrastructure, electrical loads, and electrical generation at False Pass, performed economic analysis based on current costs of energy and amount of energy anticipated from and costs associated with the tidal energy project conceptual design and scoped environmental issues. Utilizing circulation modeling, the Project Team identified two target sites with strong potential for robust tidal energy resources in Isanotski Strait and another nearer the City of False Pass. In addition, the Project Team completed a survey of the electrical infrastructure, which identified likely sites of interconnection and clarified required transmission distances from the tidal energy resources. Based on resource and electrical data

  4. M sub(2) tidal currents on the shelf off Goa, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Gouveia, A.D.; Shetye, S.R.

    Current meter records collected during three different months from a site off Goa (15 degrees 08'N, 73 degrees 16'E) over the western continental shelf of India have been used to describe the M sub(2) tidal structure in a water column of depth about...

  5. CFD Study of NACA 0018 for Diffuser Design of Tidal Current Turbines

    Directory of Open Access Journals (Sweden)

    Nasir Mehmood

    2012-11-01

    Full Text Available This study is focused on diffuser augmented tidal current turbines that capture the kinetic energy in a tidal stream. The energy that can be extracted from tides is proportional to the cube of the current velocity. The role of the diffuser in diffuser augmented tidal turbines is to help accelerate the incoming current velocity. Consequently, the efficiency of the turbine can be significantly increased by using a diffuser. The research community is investing considerable time and financial resources in this growing domain. The diffuser augmented tidal turbines research data is rather scarce due to their emerging nature, large and costly research and development setup, startup cost and proprietary issues. The purpose of this study is to investigate the effect of length and angle on NACA 0018 airfoil for diffuser design. CFD simulation is carried out to investigate velocity and mass flow rate at the throat. The drag force due to diffuser installation is also calculated. Velocity inside the diffuser increases with diffuser length and angle of attack. Velocity increases up to stall angle and then drops due to flow separation. The drag force is also dominant compared to lift coefficient near stall angle region.

  6. Residual currents and bedform migration in a natural tidal inlet (Knudedyb, Danish Wadden Sea)

    Science.gov (United States)

    Fraccascia, S.; Winter, C.; Ernstsen, V. B.; Hebbeln, D.

    2016-10-01

    The morphology and hydrodynamics of the natural tidal inlet Knudedyb in the Danish Wadden Sea were investigated by the analysis of high resolution bathymetric data and hydrodynamic numerical modeling. In contrast to the expected anticlockwise pattern similar to the other inlets in the Wadden Sea, a clockwise tidal residual current was found, which drives the sediment transport and results from the presence of a confluent meander bend. The channel is draped by bedforms of several hierarchical scales (on average, approximately 155 m long and 2.3 m high), with average sizes decreasing from south to north and seaward (i.e., westward). Primary bedforms in the area are mostly asymmetric ebb-directed and migrate in the ebb direction in the order of 3 m yr- 1. Bedform sections at the northern channel flank show more symmetrical profiles; crests migrate flood-ward, leading to crestal flexing in the central channel. Lateral recirculation cells develop during ebb tide on both sides of the channel seaward of a bend, before the tidal reversal occurs in the rest of the model domain. As a result of the longer flood phase, a main clockwise residual eddy exists in the middle reach of the channel. Bedform migration patterns and hydrodynamic simulations reveal that the pronounced tidal asymmetry in the channel is enhanced by the effects of the channel morphology on the confined flow (at low tide).

  7. Tidal current-induced formation——storm-induced change——tidal current-induced recovery——Interpretation of depositional dynamics of formation and evolution of radial sand ridges on the Yellow Sea seafloor

    Institute of Scientific and Technical Information of China (English)

    张长宽; 张东生; 张君伦; 王震

    1999-01-01

    The results of simulated tidal current field, wave field and storm-induced current field are employed to interpret the depositional dynamic mechanism of formation and evolution of the radial sand ridges on the Yellow Sea seafloor. The anticlockwise rotary tidal wave to the south of Shandong Peninsula meets the following progressive tidal wave from the South Yellow Sea, forming a radial current field outside Jianggang. This current field provides a necessary dynamic condition for the formation and existence of the radial sand ridges on the Yellow Sea seafloor. The results of simulated "old current field (holocene)" show that there existed a convergent-divergent tidal zone just outside the palaeo-Yangtze River estuary where a palaeo-underwater accumulation was developed. The calculated results from wave models indicate that the wave impact on the topography, under the condition of high water level and strong winds, is significant. The storm current induced by typhoons landing in the Yangtze River estuary

  8. Fatigue Life Prediction of Mooring Chains for a Floating Tidal Current Power Station

    Institute of Scientific and Technical Information of China (English)

    Fengmei Jing; Liang Zhang; Zhong Yang

    2012-01-01

    As a kind of clean and renewable energy,tidal current energy is becoming increasingly popular all over the world with the shortage of energy and environmental problems becoming more and more severe.A floating tidal current power station is a typical type of tidal current power transformers which can sustain the loads of wind,waves,and current,and even the extreme situation of a typhoon.Therefore,the mooring system must be reliable enough to keep the station operating normally and to survive in extreme situations.The power station examined in this paper was installed at a depth of 40 m.A 44 mm-diameter R4-RQ4 chain was chosen,with a 2 147 kN minimum break strength and 50 kN pretension.Common studless link chain was used in this paper.Based on the Miner fatigue cumulative damage rule,S-N curves of chains,and MOSES software,a highly reliable mooring system was designed and analyzed.The calculation results show that the mooring system designed is reliable throughout a 10-year period.It can completely meet the design requirements of American Petroleum institution (API).Therefore,the presented research is significant for advancing the design of this kind of power station.

  9. Fog and Tidal Current Connection at Cape Cod Canal-Early Recognition and Recent Measurements.

    Science.gov (United States)

    Woodcock, Alfred H.

    1982-02-01

    Notes by Gardner Emmons about the initiation of low advective fogs on Cape Cod are presented. Subsequent measurements made in these fogs confirm his suggestion that mixing and temperature changes associated with tidal currents account for the fog. Puzzling temperature measurements that are at apparent variance with the mixing theory of fog formation are presented. It is proposed that these temperature discrepancies are due to the effects of water vapor condensation on the sea water surface.

  10. Numerical Investigation of Flow Motion and Performance of A Horizontal Axis Tidal Turbine Subjected to A Steady Current

    Institute of Scientific and Technical Information of China (English)

    李林娟; 郑金海; 彭于轩; 张继生; 吴修广

    2015-01-01

    Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerically investigates the flow motion and performance of a horizontal axis tidal turbine with a supporting vertical cylinder under steady current. In the numerical model, the continuous equation and incompressible Reynolds-averaged Navier-Stokes equations are solved, and the volume of fluid method is employed to track free surface motion. The RNG k-εmodel is adopted to calculate turbulence transport while the fractional area/volume obstacle representation method is used to describe turbine characteristics and movement. The effects of installation elevation of tidal turbine and inlet velocity on the water elevation, and current velocity, rotating speed and resultant force on turbine are discussed. Based on the comparison of the numerical results, a better understanding of flow structure around horizontal axis tidal turbine and turbine performance is achieved.

  11. Optical Estimation of Depth and Current in a Ebb Tidal Delta Environment

    Science.gov (United States)

    Holman, R. A.; Stanley, J.

    2012-12-01

    A key limitation to our ability to make nearshore environmental predictions is the difficulty of obtaining up-to-date bathymetry measurements at a reasonable cost and frequency. Due to the high cost and complex logistics of in-situ methods, research into remote sensing approaches has been steady and has finally yielded fairly robust methods like the cBathy algorithm for optical Argus data that show good performance on simple barred beach profiles and near immunity to noise and signal problems. In May, 2012, data were collected in a more complex ebb tidal delta environment during the RIVET field experiment at New River Inlet, NC. The presence of strong reversing tidal currents led to significant errors in cBathy depths that were phase-locked to the tide. In this paper we will test methods for the robust estimation of both depths and vector currents in a tidal delta domain. In contrast to previous Fourier methods, wavenumber estimation in cBathy can be done on small enough scales to resolve interesting nearshore features.

  12. An Experimental Study on the Darrieus-Savonius Turbine for the Tidal Current Power Generation

    Science.gov (United States)

    Kyozuka, Yusaku

    The Darrieus turbine is popular for tidal current power generation in Japan. It is simple in structure with straight wings rotating around a vertical axis, so that it has no directionality against the motion of tidal flow which changes its direction twice a day. However, there is one defect in the Darrieus turbine; its small starting torque. Once it stops, a Darrieus turbine is hard to re-start until a fairly fast current is exerted on it. To improve the starting torque of the Darrieus turbine used for tidal power generation, a hybrid turbine, composed of a Darrieus turbine and a Savonius rotor is proposed. Hydrodynamic characteristics of a semi-circular section used for the Savonius bucket were measured in a wind tunnel. The torque of a two bucket Savonius rotor was measured in a circulating water channel, where four different configurations of the bucket were compared. A combined Darrieus and Savonius turbine was tested in the circulating water channel, where the effect of the attaching angle between Darrieus wing and Savonius rotor was studied. Finally, power generation experiments using a 48 pole electric generator were conducted in a towing tank and the power coefficients were compared with the results of experiments obtained in the circulating water channel.

  13. Tidal and inertial currents in the southern Bay of Campeche, southern Gulf of Mexico

    Science.gov (United States)

    Exposito-Diaz, G.

    2007-05-01

    Data from March 1 to June 17, 1997 of currents, water temperature, salinity, and sea level in the southern Bay of Campeche were used to describe tidal and inertial currents. Data were low pass filtered using a Lanczos type filter, and transformed to the frequency space with classical Fast Fourier Transform (FFT), and Morlet Wavelets Method (MWM). Results presented the strongest currents in the southwestern part of the bay, with a dominant east-west component. The predominant direction of the current was parallel to the coast, and followed the bathymetry, depicting the strong barotropic effect. The amplitude of tidal current was very small when compared to total amplitudes. The spectral energy was concentrated at the low frequencies bands, correspond to inertial periods, with an approximate duration between two to three days. Some of these oscillations were also observed in the progressive vectors diagrams. The dominance of the spectral energy at low frequencies demonstrated the influence of the mesoscale cyclonic and the small anticyclonic eddies, of the northeastern Bay of Campeche, in southwestern currents.

  14. Analytical assessments on the potential of harnessing tidal currents for electricity generation in Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Yun Seng; Koh, Siong Lee [Department of Physical Science, Electrical and Electronic Engineering, Tunku Abdul Rahman University (Malaysia)

    2010-05-15

    Malaysia is heavily dependent on fossil fuel for electricity generation. With the rapidly diminishing of its fuel reserve and the increasingly negative effects of fossil fuels to the environment, the government has begun to utilise bio-fuel and solar radiation for electricity generation. However, the potential of harnessing other renewable sources, particular ocean energy, in Malaysia has not been fully realised. Therefore, studies were carried out to identify the potential of harnessing ocean energy for electricity generation. The Princeton Ocean Model was used to create a three-dimensional numerical ocean model for Malaysia which was calibrated against measurement by a means of adjoint data assimilation approach. A set of reliable tidal speed and tidal elevation data was therefore generated to determine the types of tides available in Malaysia, the potential areas of installing marine current turbines (MCTs), the total amount of electricity to be generated by MCT, the economical viability and the environmental benefits of using MCT in Malaysia. This paper presents the findings on the studies, encompassing the technical, economical and environmental aspects of installing MCT in Malaysia. The results are critical to policy makers and the potential investors on tidal energy in Malaysia for decision making. It may also help the neighboring countries to realize the possible potential of their ocean energy for electricity generation. (author)

  15. Structural Design of a Horizontal-Axis Tidal Current Turbine Composite Blade

    Energy Technology Data Exchange (ETDEWEB)

    Bir, G. S.; Lawson, M. J.; Li, Y.

    2011-10-01

    This paper describes the structural design of a tidal composite blade. The structural design is preceded by two steps: hydrodynamic design and determination of extreme loads. The hydrodynamic design provides the chord and twist distributions along the blade length that result in optimal performance of the tidal turbine over its lifetime. The extreme loads, i.e. the extreme flap and edgewise loads that the blade would likely encounter over its lifetime, are associated with extreme tidal flow conditions and are obtained using a computational fluid dynamics (CFD) software. Given the blade external shape and the extreme loads, we use a laminate-theory-based structural design to determine the optimal layout of composite laminas such that the ultimate-strength and buckling-resistance criteria are satisfied at all points in the blade. The structural design approach allows for arbitrary specification of the chord, twist, and airfoil geometry along the blade and an arbitrary number of shear webs. In addition, certain fabrication criteria are imposed, for example, each composite laminate must be an integral multiple of its constituent ply thickness. In the present effort, the structural design uses only static extreme loads; dynamic-loads-based fatigue design will be addressed in the future. Following the blade design, we compute the distributed structural properties, i.e. flap stiffness, edgewise stiffness, torsion stiffness, mass, moments of inertia, elastic-axis offset, and center-of-mass offset along the blade. Such properties are required by hydro-elastic codes to model the tidal current turbine and to perform modal, stability, loads, and response analyses.

  16. Observed wintertime tidal and subtidal currents over the continental shelf in the northern South China Sea

    Science.gov (United States)

    Li, Ruixiang; Chen, Changsheng; Xia, Huayong; Beardsley, Robert C.; Shi, Maochong; Lai, Zhigang; Lin, Huichan; Feng, Yanqing; Liu, Changjian; Xu, Qichun; Ding, Yang; Zhang, Yu

    2014-08-01

    Synthesis analyses were performed to examine characteristics of tidal and subtidal currents at eight mooring sites deployed over the northern South China Sea (NSCS) continental shelf in the 2006-2007 and 2009-2010 winters. Rotary spectra and harmonic analysis results showed that observed tidal currents in the NSCS were dominated by baroclinic diurnal tides with phases varying both vertically and horizontally. This feature was supported by the CC-FVCOM results, which demonstrated that the diurnal tidal flow over this shelf was characterized by baroclinic Kelvin waves with vertical phase differences varying in different flow zones. The northeasterly wind-induced southwestward flow prevailed over the NSCS shelf during winter, with episodic appearances of mesoscale eddies and a bottom-intensified buoyancy-driven slope water intrusion. The moored current records captured a warm-core anticyclonic eddy, which originated from the southwestern coast of Taiwan and propagated southwestward along the slope consistent with a combination of β-plane and topographic Rossby waves. The eddy was surface-intensified with a swirl speed of >50 cm/s and a vertical scale of ˜400 m. In absence of eddies and onshore deep slope water intrusion, the observed southwestward flow was highly coherent with the northeasterly wind stress. Observations did not support the existence of the permanent wintertime South China Sea Warm Current (SCSWC). The definition of SCSWC, which was based mainly on thermal wind calculations with assumed level of no motion at the bottom, needs to be interpreted with caution since the observed circulation over the NSCS shelf in winter included both barotropic and baroclinic components.

  17. Tidal currents and mixing in the Gulf of St. Lawrence : an application of the incremental approach to data assimilation

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Y.; Thompson, K.R. [Dalhousie Univ., Halifax, NS (Canada). Inst. of Oceanography; Wright, D.G. [Bedford Inst. of Oceanography, Dartmouth, NS (Canada)

    2001-04-01

    The physical factors that control the distribution and abundance of the planktonic copepod Calanus finmarchicus in the Gulf of St. Lawrence (GSL) were studied. The species is an important component of the region's marine pelagic food web. In this study, the positions of baroclinic fronts formed by tidal mixing in the GSL were studied to determine if the tidal fronts, which are regions of convergence and enhanced biological activity, have important implications for the spatial distribution of biomass. The study also presented a new and effective method of data assimilation that makes it possible to convert standard physical information, (such as tidal heights) into a more biologically meaningful product, such as a map of tidal fronts. The method could be used assimilate sparse measurements of zooplankton abundance into biological models embedded within circulation models. Tidal heights from 19 tide gauges were assimilated into a fully nonlinear, three-dimensional model using the incremental approach to data assimilation. Tidal currents were predicted with good accuracy. The maps of predicted tidal currents can be used to identify regions of mixed and stratified water in the GSL using a version of the Simpson-Hunter stability parameter. 28 refs., 2 tabs., 10 figs.

  18. Effect of Distortion Ratio on Local Scour Under Tidal Currents and Waves

    Institute of Scientific and Technical Information of China (English)

    窦希萍; 董凤舞

    2004-01-01

    Five generalized physical models of different distortion ratios were built according to DOU Guo-ren' s similarity theory of total sediment transport modeling for estuarine and coastal regions. Experiments on local scour in front of groins were made under the actions of tidal currents and waves with clear and sediment entraining water. The scour depths under different dynamic actions are compared. The effect of the distortion ratio on the depth of scour hole is discussed. A relationship between scour depths for distorted and undistorted models is given.

  19. Tidal Current Short-Term Prediction Based on Support Vector Regression

    Science.gov (United States)

    Guozhen, Yang; Haifeng, Wang; Hui, Qian; Jianming, Fang

    2017-05-01

    The traditional method of short-term tidal current prediction, harmonic method, typically needs more than 18 years of history records. The method in the article uses univariate feature selection and F-test to reduce the dimension of the data fed to support vector regressor, which reduces the need of history records to less than a year. Model parameters are selected by grid searching and cross-validation. History records from two datasets are used to build prediction models, spanning 3 months and 1 year respectively. Mean average errors of both datasets after normalizing are less than 0.05.

  20. Strategies for the Use of Tidal Stream Currents for Power Generation

    Science.gov (United States)

    Orhan, Kadir; Mayerle, Roberto

    2015-04-01

    Indonesia is one of the priority countries in Southeast Asia for the development of ocean renewable energy facilities and The National Energy Council intends to increase the role of ocean energy significantly in the energy mix for 2010-2050. To this end, the joint German-Indonesian project "Ocean Renewable Energy ORE-12" aims at the identification of marine environments in the Indonesian Archipelago, which are suitable for the efficient generation of electric power by converter facilities. This study, within the ORE-12 project, is focused on the tidal stream currents on the straits between the Indian Ocean and Flores Sea to estimate the energy potentials and to develop strategies for producing renewable energy. FLOW module of Delft3D has been used to run hydrodynamic models for site assessment and design development. In site assessment phase, 2D models have been operated for a-month long periods and with a resolution of 500 m. Later on, in design development phase, detailed 3D models have been developed and operated for three-month long periods and with a resolution of 50 m. Bathymetric data for models have been obtained from the GEBCO_08 Grid and wind data from the Global Forecast System of NOAA's National Climatic Data Center. To set the boundary conditions of models, tidal forcing with 11 harmonic constituents was supplied from TPXO Indian Ocean Atlas (1/12° regional model) and data from HYCOM+NCODA Global 1/12° Analysis have been used to determine salinity and temperature on open boundaries. After the field survey is complete, water level time-series supplied from a tidal gauge located in the domain of interest (8° 20΄ 9.7" S, 122° 54΄ 51.9" E) have been used to verify the models and then energy potentials of the straits have been estimated. As a next step, correspondence between model outputs and measurements taken by the radar system of TerraSAR-X satellite (DLR) will be analysed. Also for the assessment of environmental impacts caused by tidal stream

  1. High-resolution velocimetry in energetic tidal currents using a convergent-beam acoustic Doppler profiler

    Energy Technology Data Exchange (ETDEWEB)

    Sellar, Brian [Univ. of Edinburgh, Scotland (United Kingdom); Harding, Samuel F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Richmond, Marshall C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-16

    An array of convergent acoustic Doppler velocimeters has been developed and tested for the high resolution measurement of three-dimensional tidal flow velocities in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use diverging acoustic beams emanating from a single instrument. This is achieved using converging acoustic beams with a sample volume at the focal point of 0.03 m3. The array is also able to simultaneously measure three-dimensional velocity components in a profile throughout the water column, and as such is referred to herein as a converging-beam acoustic Doppler profiler (CADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational Alstom 1MW DeepGen-IV Tidal Turbine. This proof-of-concept paper outlines system configuration and comparison to measurements provided by co-installed reference instrumentation. Comparison of CADP to standard ADP velocity measurements reveals a mean difference of 8 mm/s, standard deviation of 18 mm/s, and order-of-magnitude reduction in realizable length-scale. CADP focal point measurements compared to a proximal single-beam reference show peak cross-correlation coefficient of 0.96 over 4.0 s averaging period and a 47% reduction in Doppler noise. The dual functionality of the CADP as a profiling instrument with a high resolution focal point make this configuration a unique and valuable advancement in underwater velocimetry enabling improved turbulence, resource and structural loading quantification and validation of numerical simulations. Alternative modes of operation have been implemented including noise-reducing bi-static sampling. Since waves are simultaneously measured it is expected that derivatives of this system will be a powerful tool in wave-current interaction studies.

  2. Repeated surveys by acoustic Doppler current profiler for flow and sediment dynamics in a tidal river

    Science.gov (United States)

    Dinehart, R. L.; Burau, J. R.

    2005-11-01

    A strategy of repeated surveys by acoustic Doppler current profiler (ADCP) was applied in a tidal river to map velocity vectors and suspended-sediment indicators. The Sacramento River at the junction with the Delta Cross Channel at Walnut Grove, California, was surveyed over several tidal cycles in the Fall of 2000 and 2001 with a vessel-mounted ADCP. Velocity profiles were recorded along flow-defining survey paths, with surveys repeated every 27 min through a diurnal tidal cycle. Velocity vectors along each survey path were interpolated to a three-dimensional Cartesian grid that conformed to local bathymetry. A separate array of vectors was interpolated onto a grid from each survey. By displaying interpolated vector grids sequentially with computer animation, flow dynamics of the reach could be studied in three-dimensions as flow responded to the tidal cycle. Velocity streamtraces in the grid showed the upwelling of flow from the bottom of the Sacramento River channel into the Delta Cross Channel. The sequential display of vector grids showed that water in the canal briefly returned into the Sacramento River after peak flood tides, which had not been known previously. In addition to velocity vectors, ADCP data were processed to derive channel bathymetry and a spatial indicator for suspended-sediment concentration. Individual beam distances to bed, recorded by the ADCP, were transformed to yield bathymetry accurate enough to resolve small bedforms within the study reach. While recording velocity, ADCPs also record the intensity of acoustic backscatter from particles suspended in the flow. Sequential surveys of backscatter intensity were interpolated to grids and animated to indicate the spatial movement of suspended sediment through the study reach. Calculation of backscatter flux through cross-sectional grids provided a first step for computation of suspended-sediment discharge, the second step being a calibrated relation between backscatter intensity and sediment

  3. Experimental study on hydrodynamic characteristics of vertical-axis floating tidal current energy power generation device

    Science.gov (United States)

    Ma, Yong; Li, Teng-fei; Zhang, Liang; Sheng, Qi-hu; Zhang, Xue-wei; Jiang, Jin

    2016-10-01

    To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device (VAFTCEPGD), a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.

  4. Sedimentary history of the eastern Bohai Sea, China since the deglacial and implications for paleo-tidal current

    Science.gov (United States)

    Yao, Zhengquan; Shi, Xuefa

    2016-04-01

    Numerical simulation suggests that the Holocene sediments re-suspension and distribution in the Bohai Sea was mainly controlled by tidal current regime, which was closely related with sea-level change. Study on sediments in the Bohai Sea thus can provide insights into the evolution of tidal-influenced sedimentary environment and its links with sea-level change. Our understanding of this issue remains incomplete, however, owing to the lack of comprehensive study on sediment core with high-resolution proxies to test such inference. In this study, analyses of sedimentary facies, proxies (grain size, total organic carbon and total nitrogen, X-ray fluorescence scanning Sulfur and Chlorine ratio) and accelerator mass spectrometry 14C dates of a sediment core recovered from the eastern Bohai Sea were carried out to clarify the Holocene sedimentary environment, tidal current change and its relation to the sea-level. The results indicate that the eastern Bohai Sea was dominated by fluvial-coastal environment prior to 12400 cal. a BP due to the sea-level lowstand and changed to tidal-influenced environment from 12400 to 6700 cal. a BP following the rapid sea-level rising. Thereafter shelf environment with minor tidal influence dominated the eastern Bohai Sea under the condition of a deceleration of sea-level rise. The significant change at ~6700 cal. a BP both in sedimentary environment and sediment proxies, indicating an environmental transition from strong tidal-influenced to less tidal-influenced setting. With the sea-level rising from the early Holocene to the mid-Holocene, tidal-current was much strong due to the low sea-level stand and became weak after the maximum transgression at ~6700 cal. a BP. These results are consistent with the numerical simulation, which suggested that less strong tidal current were the consequence of the most highstand sea-level since the mid-Holocene. Our study thus provides a sedimentary record to support the interpretation of numerical

  5. A Finite Volume Method with Unstructured Triangular Grids for Numerical Modeling of Tidal Current

    Institute of Scientific and Technical Information of China (English)

    SHI Hong-da; LIU zhen

    2005-01-01

    The finite volume method (FVM) has many advantages in 2-D shallow water numerical simulation. In this study, the finite volume method is used with unstructured triangular grids to simulate the tidal currents. The Roe scheme is applied in the calculation of the intercell numerical flux, and the MUSCL method is introduced to improve its accuracy. The time integral is a two-step scheme of forecast and revision. For the verification of the present method, the Stoker's problem is calculated and the result is compared with the mathematically analytic solutions. The comparison indicates that the method is feasible. A sea area of a port is used as an example to test the method established here. The result shows that the present computational method is satisfactory, and it could be applied to the engineering fields.

  6. Effects of Tidal Currents on Nonlinear Internal Solitary Waves in the South China Sea

    Institute of Scientific and Technical Information of China (English)

    FAN Zhisong; SHI Xingang; Antony K. Liu; LIU Hailong; LI Peiliang

    2013-01-01

    The propagation and fission process of intemal solitary waves (ISWs) with amplitudes of about 170m are simulated in the northeast of the South China Sea (NSCS) by using the generalized Korteweg-de Vries (KdV) equation under continuous stratification.More attention is paid to the effects of the ebb and flood background currents on the fission process of ISWs.This kind of background current is provided by the composed results simulated in terms of monthly mean baroclinic circulation and barotropic tidal current.It is found that the obtained relation of the number of fission solitons to the water depth and stratification is roughly in accordance with the fission law derived by Djordjevic and Redekopp in 1978; however,there exists obvious difference between the effects of the ebb and flood background currents on the wave-lengths of fission solitons (defined as the distance between two neighboring peaks of ISWs).The difference in nonlinearity coefficient α between the ebb and flood background currents is a main cause for the different wave-lengths of fission solitons.

  7. High-resolution velocimetry in energetic tidal currents using a convergent-beam acoustic Doppler profiler

    Science.gov (United States)

    Sellar, Brian; Harding, Samuel; Richmond, Marshall

    2015-08-01

    An array of single-beam acoustic Doppler profilers has been developed for the high resolution measurement of three-dimensional tidal flow velocities and subsequently tested in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use divergent acoustic beams emanating from a single instrument. This is achieved using geometrically convergent acoustic beams creating a sample volume at the focal point of 0.03 m3. Away from the focal point, the array is also able to simultaneously reconstruct three-dimensional velocity components in a profile throughout the water column, and is referred to herein as a convergent-beam acoustic Doppler profiler (C-ADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational commercial-scale Alstom 1 MW DeepGen-IV Tidal Turbine deployed at the European Marine Energy Center, Orkney Isles, UK. This proof-of-concept paper outlines the C-ADP system configuration and comparison to measurements provided by co-installed reference instrumentation. Comparison of C-ADP to standard divergent ADP (D-ADP) velocity measurements reveals a mean difference of 8 mm s-1, standard deviation of 18 mm s-1, and an order of magnitude reduction in realisable length scale. C-ADP focal point measurements compared to a proximal single-beam reference show peak cross-correlation coefficient of 0.96 over 4.0 s averaging period and a 47% reduction in Doppler noise. The dual functionality of the C-ADP as a profiling instrument with a high resolution focal point make this configuration a unique and valuable advancement in underwater velocimetry enabling improved quantification of flow turbulence. Since waves are simultaneously measured via profiled velocities, pressure measurements and surface detection, it is expected that derivatives of this system will be a powerful tool in

  8. Effect of Doubly Fed Induction GeneratorTidal Current Turbines on Stability of a Distribution Grid under Unbalanced Voltage Conditions

    Directory of Open Access Journals (Sweden)

    Dahai Zhang

    2017-02-01

    Full Text Available This paper analyses the effects of doubly fed induction generator (DFIG tidal current turbines on a distribution grid under unbalanced voltage conditions of the grid. A dynamic model of an electrical power system under the unbalanced network is described in the paper, aiming to compare the system performance when connected with and without DFIG at the same location in a distribution grid. Extensive simulations of investigating the effect of DFIG tidal current turbine on stability of the distribution grid are performed, taking into account factors such as the power rating, the connection distance of the turbine and the grid voltage dip. The dynamic responses of the distribution system are examined, especially its ability to ride through fault events under unbalanced grid voltage conditions. The research has shown that DFIG tidal current turbines can provide a good damping performance and that modern DFIG tidal current power plants, equipped with power electronics and low-voltage ride-through capability, can stay connected to weak electrical grids even under the unbalanced voltage conditions, whilst not reducing system stability.

  9. Tides, tidal currents and their effects on the intertidal ecosystem of the southern bay, Inhaca Island, Mozambique

    NARCIS (Netherlands)

    Boer, de W.F.; Rydberg, L.; Saide, V.

    2000-01-01

    Sediment characteristics and tidal currents were studied in the 1500 ha intertidal area south of Inhaca Island, Mozambique. The tide is semi-diurnal with a range at spring of about 3 m. The area connects directly to the ocean through the Ponta Torres Strait and (indirectly) through several narrow ti

  10. Tides, tidal currents and their effects on the intertidal ecosystem of the southern bay, Inhaca Island, Mozambique

    NARCIS (Netherlands)

    Boer, de W.F.; Rydberg, L.; Saide, V.

    2000-01-01

    Sediment characteristics and tidal currents were studied in the 1500 ha intertidal area south of Inhaca Island, Mozambique. The tide is semi-diurnal with a range at spring of about 3 m. The area connects directly to the ocean through the Ponta Torres Strait and (indirectly) through several narrow

  11. Hydrodynamic Performance Analysis on Different Airfoils of Straight Blade H Type of Vertical Axis Tidal Current Energy Turbine

    Directory of Open Access Journals (Sweden)

    Kan Kan

    2016-01-01

    Full Text Available Airfoil is a key factor that influences the hydrodynamic performance of vertical axis tidal current energy turbine. In order to explore the influences from the runner’s blade airfoil towards its hydrodynamic performance, three-dimensional unsteady flow numerical simulation on four airfoils of straight blade H type of tidal current energy turbines was carried out, under the precondition of same turbine compactness. Through investigating the influences from the four different airfoils of H blade towards the runner in terms of its dynamic torque feature and hydropower utilization coefficient, this research has analyzed the hydrodynamic performance of the tidal current energy turbine. As the research result indicates, the maximum dynamic torque value of the single-blade turbine with NACA0015 airfoil is significantly higher than that of the other three airfoils; while the maximum value of the overall runner torque is determined by the operating conditions such as different stream speed etc. As a whole, hydropower utilization coefficient of the turbine with asymmetric airfoil NACA4415 is better than that of the other three airfoils. This research has provided references for the design and airfoil selection for the new type of tidal current energy turbine.

  12. Tidal Stream Generators, current state and potential opportunities for condition monitoring

    DEFF Research Database (Denmark)

    Kappatos, Vassilios; Georgoulas, George; Avdelidis, Nicolas

    2016-01-01

    Tidal power industry has made significant progress towards commercialization over the past decade. Significant investments from sector leaders, strong technical progress and positive media coverage have established the credibility of this specific renewable energy source. However, its progress...

  13. Field Measurements at River and Tidal Current Sites for Hydrokinetic Energy Development: Best Practices Manual

    Energy Technology Data Exchange (ETDEWEB)

    Neary, Vincent S [ORNL; Gunawan, Budi [Oak Ridge National Laboratory (ORNL)

    2011-09-01

    In this report, existing data collection techniques and protocols for characterizing open channel flows are reviewed and refined to further address the needs of the MHK industry. The report provides an overview of the hydrodynamics of river and tidal channels, and the working principles of modern acoustic instrumentation, including best practices in remote sensing methods that can be applied to hydrokinetic energy site characterization. Emphasis is placed upon acoustic Doppler velocimeter (ADV) and acoustic-Doppler current profiler (ADCP) instruments, as these represent the most practical and economical tools for use in the MHK industry. Incorporating the best practices as found in the literature, including the parameters to be measured, the instruments to be deployed, the instrument deployment strategy, and data post-processing techniques. The data collected from this procedure aims to inform the hydro-mechanical design of MHK systems with respect to energy generation and structural loading, as well as provide reference hydrodynamics for environmental impact studies. The standard metrics and protocols defined herein can be utilized to guide field experiments with MHK systems.

  14. Dune convergence/divergence controlled by residual current vortices in the Jade tidal channel, south-eastern North Sea

    Science.gov (United States)

    Kubicki, Adam; Kösters, Frank; Bartholomä, Alexander

    2017-02-01

    A field of large to very large subaqueous dunes was investigated in the Jade tidal channel, south-eastern North Sea, between January 2006 and October 2011. A ground-truthed sidescan sonar sediment map shows that the dunes, which are located on top of a consolidated clay surface, are composed of medium to coarse sand. A series of 35 consecutive high-resolution bathymetric surfaces collected by multibeam echosounder revealed a complex migration pattern induced by the reversing tidal currents. Various parts of the dune field are under the influence of either ebb- or flood-dominated currents, as indicated by dune asymmetries. Although some dunes migrate at a pace exceeding 100 m/year, the majority are displaced by 30 m/year in the direction of the locally dominant current. In the deepest part of the channel, however, dunes were observed to converge head-on, resulting in practically zero net transport with minor oscillations of symmetrical dunes at the apex. Applying the numerical UnTRIM model for the simulation of the fair-weather hydrology, a simplified map of residual current vectors over the dune field was generated. The residual flow vectors are found to perfectly match the derived dune migration vectors, suggesting that dune convergence is controlled by two counter-rotating residual current vortices caused by the local shape of the tidal channel. As no sediment build-up is observed, a mechanism of sediment bypassing with potential recirculation must exist, but has not yet been identified.

  15. Assessment of Power Potential of Tidal Currents and Impacts of Power Extraction on Flow Speeds in Indonesia

    Science.gov (United States)

    Orhan, K.; Mayerle, R.

    2016-12-01

    A methodology comprising of the estimates of power yield, evaluation of the effects of power extraction on flow conditions, and near-field investigations to deliver wake characteritics, recovery and interactions is described and applied to several straits in Indonesia. Site selection is done with high-resolution, three-dimensional flow models providing sufficient spatiotemporal coverage. Much attention has been given to the meteorological forcing, and conditions at the open sea boundaries to adequately capture the density gradients and flow fields. Model verification using tidal records shows excellent agreement. Sites with adequate depth for the energy conversion using horizontal axis tidal turbines, average kinetic power density greater than 0.5 kW/m2, and surface area larger than 0.5km2 are defined as energy hotspots. Spatial variation of the average extractable electric power is determined, and annual tidal energy resource is estimated for the straits in question. The results showed that the potential for tidal power generation in Indonesia is likely to exceed previous predictions reaching around 4,800MW. To assess the impact of the devices, flexible mesh models with higher resolutions have been developed. Effects on flow conditions, and near-field turbine wakes are resolved in greater detail with triangular horizontal grids. The energy is assumed to be removed uniformly by sub-grid scale arrays of turbines, and calculations are made based on velocities at the hub heights of the devices. An additional drag force resulting in dissipation of the pre-existing kinetic power from %10 to %60 within a flow cross-section is introduced to capture the impacts. It was found that the effect of power extraction on water levels and flow speeds in adjacent areas is not significant. Results show the effectivess of the method to capture wake characteritics and recovery reasonably well with low computational cost.

  16. Tidal Forms

    Science.gov (United States)

    Bolla Pittaluga, M.; Seminara, G.; Tambroni, N.

    2003-04-01

    centrifugally as well as topographically induced secondary flows, though the oscillatory character of the flow field makes the point bar pattern typical of tidal channels fairly symmetric (Solari et al., 2002, Solari and Toffolon, 2001). However, the detailed analysis of the planimetric pattern of tidal meanders performed by Marani et al. (2002) has shown that the often observed features of fluvial meanders which typically exhibit upstream skewing and downstream migration are both absent in tidal environments. The cause of such a behaviour as well as the weakly dynamic character of tidal meanders still awaits mechanistic explanations. The hydrodynamics of sharp tidal inlets is characterised by a strong asymmetry in the case of fixed beds (Blondeaux et al., 1982), displaying a nearly irrotational flow field in the flood phase and an unsteady jet in the ebb phase. The erodible character of the bed makes the asymmetry weaker due to the progressive excavation of a submerged channel (Tambroni et al., 2003a) which tends to constrain the flow direction also during the flood phase. The consequences of such feature on the exchange of sediments between the channel and the sea are currently being investigated. Finally, the presence of tidal flats has a significant effect on channel hydrodynamics which tends to attain an ebb dominant character as the role of the flats increases (Tambroni et al., 2003b). The morphodynamic effect of such novel feature as well as the exchange of sediments between channel and adjacent flats are also the subject of current investigations. Most of the theoretical results mentioned above have been substantiated through a set of experiments performed at the laboratory of the Department of Environmental Engineering of the University of Genova (Tambroni et al., 2003a). References Blondeaux, P., de Bernardinis, B. and Seminara, G. 1982. Correnti di marea in prossimita di imboccature e loro influenza sul ricambio lagunare. Atti XVIII Conv. Idraulica e Costruzioni

  17. The agonist-specific voltage dependence of M2 muscarinic receptors modulates the deactivation of the acetylcholine-gated K(+) current (I KACh).

    Science.gov (United States)

    Moreno-Galindo, Eloy G; Alamilla, Javier; Sanchez-Chapula, José A; Tristani-Firouzi, Martin; Navarro-Polanco, Ricardo A

    2016-07-01

    Recently, it has been shown that G protein-coupled receptors (GPCRs) display intrinsic voltage sensitivity. We reported that the voltage sensitivity of M2 muscarinic receptor (M2R) is also ligand specific. Here, we provide additional evidence to understand the mechanism underlying the ligand-specific voltage sensitivity of the M2R. Using ACh, pilocarpine (Pilo), and bethanechol (Beth), we evaluated the agonist-specific effects of voltage by measuring the ACh-activated K(+) current (I KACh) in feline and rabbit atrial myocytes and in HEK-293 cells expressing M2R-Kir3.1/Kir3.4. The activation of I KACh by the muscarinic agonist Beth was voltage insensitive, suggesting that the voltage-induced conformational changes in M2R do not modify its affinity for this agonist. Moreover, deactivation of the Beth-evoked I KACh was voltage insensitive. By contrast, deactivation of the ACh-induced I KACh was significantly slower at -100 mV than at +50 mV, while an opposite effect was observed when I KACh was activated by Pilo. These findings are consistent with the voltage affinity pattern observed for these three agonists. Our findings suggest that independent of how voltage disturbs the receptor binding site, the voltage dependence of the signaling pathway is ultimately determined by the agonist. These observations emphasize the pharmacological potential to regulate the M2R-parasympathetic associated cardiac function and also other cellular signaling pathways by exploiting the voltage-dependent properties of GPCRs.

  18. Development of a Multi-Site and Multi-Device Webgis-Based Tool for Tidal Current Energy Development

    Science.gov (United States)

    Ang, M. R. C. O.; Panganiban, I. K.; Mamador, C. C.; De Luna, O. D. G.; Bausas, M. D.; Cruz, J. P.

    2016-06-01

    A multi-site, multi-device and multi-criteria decision support tool designed to support the development of tidal current energy in the Philippines was developed. Its platform is based on Geographic Information Systems (GIS) which allows for the collection, storage, processing, analyses and display of geospatial data. Combining GIS tools with open source web development applications, it becomes a webGIS-based marine spatial planning tool. To date, the webGIS-based tool displays output maps and graphs of power and energy density, site suitability and site-device analysis. It enables stakeholders and the public easy access to the results of tidal current energy resource assessments and site suitability analyses. Results of the initial development showed that it is a promising decision support tool for ocean renewable energy project developments.

  19. Optimization of hydrofoil for tidal current turbine based on particle swarm optimization and computational fluid dynamic method

    OpenAIRE

    Zhang De-Sheng; Chen Jian; Shi Wei-Dong; Shi Lei; Geng Lin-Lin

    2016-01-01

    Both efficiency and cavitation performance of the hydrofoil are the key technologies to design the tidal current turbine. In this paper, the hydrofoil efficiency and lift coefficient were improved based on particle swarm optimization method and XFoil codes. The cavitation performance of the optimized hydrofoil was also discussed by the computational fluid dynamic. Numerical results show the efficiency of the optimized hydrofoil was improved 11% ranging from...

  20. Interactions between wind and tidally induced currents in coastal and shelf basins

    Science.gov (United States)

    Jacob, Benjamin; Stanev, Emil Vassilev

    2017-10-01

    This paper addresses the impact of atmospheric variability on ocean circulation in tidal and non-tidal basins. The data are generated by an unstructured-grid numerical model resolving the dynamics in the coastal area, as well as in the straits connecting the North Sea and Baltic Sea. The model response to atmospheric forcing in different frequency intervals is quantified. The results demonstrate that the effects of the two mechanical drivers, tides and wind, are not additive, yet non-linear interactions play an important role. There is a tendency for tidally and wind-driven circulations to be coupled, in particular in the coastal areas and straits. High-frequency atmospheric variability tends to amplify the mean circulation and modify the exchange between the North and the Baltic Sea. The ocean response to different frequency ranges in the wind forcing is area-selective depending on specific local dynamics. The work done by wind on the oceanic circulation depends strongly upon whether the regional circulation is tidally or predominantly wind-driven. It has been demonstrated that the atmospheric variability affects the spring-neap variability very strongly.

  1. Observed tidal currents on the continental shelf off the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Subeesh, M.P.; Unnikrishnan, A.S.; Fernando, V.; Agarwadekar, Y.; Khalap, S.T.; Satelkar, N.P.; Shenoi, S.S.C.

    . The observations extended over a 6-month period (March–August), which includes two seasons, pre-monsoon (March–April) and southwest (SW) monsoon (May–August) during 2008, 2009 and 2011. Tidal ellipses, constructed for M2 and K1 constituents...

  2. Residual circulation and tidal stress in the Gulf of California

    Science.gov (United States)

    Salas-De-León, David Alberto; Carbajal-PéRez, Noel; Monreal-Gómez, Maria Adela; Barrientos-MacGregor, Gerardo

    2003-10-01

    Results of a three-dimensional nonlinear barotropic shelf model are used to study the effect of the M2 tidal stress on the residual current in the Gulf of California. The tidal stress summarizes the nonlinear interactions and forces the residual circulation. It is calculated following the method developed by [1975]. The vertical structure of the tidal stress reveals clearly the zones where the interaction between tidal currents and the basin geometry is strong. The highest values of tidal stress were found over the Salsipuedes sill and in the Ballenas Channel in the central archipelago and in the Colorado River Delta. Relatively high values of tidal stress were also found in deeper layers in the southern part. The high tidal stress values coincide well with the anomalous cold-water patches observed in the archipelago area, attributed to tidal mixing. The calculated residual currents show a maximum of about 15 cm s-1 in the upper layers in the archipelago area. At subsurface layers an anticyclonic circulation is observed. Divergence patterns in the upper layers suggest that M2 tide residuals contribute, to significant upward movements of water, on the west side of Tiburón island. This barotropic process may contribute to the generation of the observed cold patches.

  3. Characterization of the Vertical Structure of Tidal Currents in the Mouth of the Columbia River and Evaluation of the Selfe Model

    Science.gov (United States)

    2014-06-01

    time for reviewing instruction, searching existing data sources , gathering and maintaining the data needed, and completing and reviewing the collection...VERTICAL STRUCTURE OF TIDAL CURRENTS IN THE MOUTH OF THE COLUMBIA RIVER AND EVALUATION OF THE SELFE MODEL 5. FUNDING NUMBERS 6. AUTHOR(S) Joseph R...declination to the Earth (27.3 days) ( Disney and Overshiner 1925). Changes in the moon’s phase and distance from Earth cause changes in tidal current

  4. From selective tidal transport to counter-current swimming during watershed colonisation: an impossible step for young-of-the-year catadromous fish?

    Directory of Open Access Journals (Sweden)

    Trancart T.

    2014-01-01

    Full Text Available During watershed colonisation by catadromous species, two main phases have been identified: tidal estuary crossing and non-tidal river colonisation. Fishes use selective tidal-stream transport (STST during the first phase of this colonisation, and counter-current swimming during the second phase. Therefore, catadromous species have to achieve a behavioural shift, from STST to constant counter-current swimming. This has not yet been observed, and the location and period of this shift is still unknown. Our experimental protocol aimed to mimic the spatial progression of crossing the tidal limit within a 3-week experiment. Two catadromous fishes, thinlip mullets and European eels, were initially subjected to current reversal every 6.2 h during the first week. A gradual tidal distortion was performed during the second week, and fishes were submitted to a unidirectional water current during the third week. Our results reveal that all catadromous species use STST as far as possible within the tidal limit. At this point, in this experimental study, no young-of-the-year (YOY fishes shifted from STST to constant counter-current swimming. This confirms that the behavioural shift occurs later, and that the second part of the upstream migration, counter-current progression, is performed by larger, older fishes and not YOY fishes.

  5. Hydrodynamic performance of a vertical-axis tidal-current turbine with different preset angles of attack

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guang; YANG Ran-sheng; LIU Yan; ZHAO Peng-fei

    2013-01-01

    The instantaneous angle of attack on the blade has a significant effect on the hydrodynamic performance of a vertical-axis tidal-current turbine with straight blades.This paper investigates the influence of different preset angles of attack on the hydrodynamic performance of a three-bladed,vertical-axis,tidal-current turbine both experimentally and numerically.Experiments are carried out in a towing tank.This tested turbine's solidity is 0.1146.The preset angles of attack on the blade are-3°,0°,3°,and 5°,in the experiments.Experimental results show that with the increase of the preset angle of attack from-3°,to 5°,the hydrodynamic performance of the turbine is improved significantly with the power coefficients being increased from 15.3% to 34.8%,respectively.Compared to the result of a 0° preset angle of attack,the performance of the turbine with positive preset angles of attack is experimentally demonstrated to be beneficial.This performance improvement is also shown by numerical simulations based on the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations.In addition,the numerical results show that the optimal positive preset angle of attack is 7° for the turbine studied.The corresponding power coefficient is 38%.Beyond this optimal preset angle of attack,the hydrodynamic performance of the turbine decreases.Therefore,due to the dynamic stall phenomenon,an optimal preset angle of attack exists for any vertical-axis turbine.This value should be considered in the design of a vertical-axis tidal-current turbine.

  6. Numerical and Experimental Study of the 3D Effect on Connecting Arm of Vertical Axis Tidal Current Turbine

    Institute of Scientific and Technical Information of China (English)

    郭伟; 康海贵; 陈兵; 谢宇; 王胤

    2016-01-01

    Vertical axis tidal current turbine is a promising device to extract energy from ocean current. One of the important components of the turbine is the connecting arm, which can bring about a significant effect on the pressure distribution along the span of the turbine blade, herein we call it 3D effect. However, so far the effect is rarely reported in the research, moreover, in numerical simulation. In the present study, a 3D numerical model of the turbine with the connecting arm was developed by using FLUENT software compiling the UDF (User Defined Function) command. The simulation results show that the pressure distribution along the span of blade with the connecting arm model is significantly different from those without the connecting arm. To facilitate the validation of numerical model, the laboratory experiment has been carried out by using three different types of NACA aerofoil connecting arm and circle section connecting arm. And results show that the turbine with NACA0012 connecting arm has the best start-up performance which is 0.346 m/s and the peak point of power conversion coefficient is around 0.33. A further study has been performed and a conclusion is drawn that the aerofoil and thickness of connecting arm are the most important factors on the power conversion coefficient of the vertical axis tidal current turbine.

  7. Application of 2D numerical model to unsteady performance evaluation of vertical-axis tidal current turbine

    Science.gov (United States)

    Liu, Zhen; Qu, Hengliang; Shi, Hongda; Hu, Gexing; Hyun, Beom-Soo

    2016-12-01

    Tidal current energy is renewable and sustainable, which is a promising alternative energy resource for the future electricity supply. The straight-bladed vertical-axis turbine is regarded as a useful tool to capture the tidal current energy especially under low-speed conditions. A 2D unsteady numerical model based on Ansys-Fluent 12.0 is established to conduct the numerical simulation, which is validated by the corresponding experimental data. For the unsteady calculations, the SST model, 2×105 and 0.01 s are selected as the proper turbulence model, mesh number, and time step, respectively. Detailed contours of the velocity distributions around the rotor blade foils have been provided for a flow field analysis. The tip speed ratio (TSR) determines the azimuth angle of the appearance of the torque peak, which occurs once for a blade in a single revolution. It is also found that simply increasing the incident flow velocity could not improve the turbine performance accordingly. The peaks of the averaged power and torque coefficients appear at TSRs of 2.1 and 1.8, respectively. Furthermore, several shapes of the duct augmentation are proposed to improve the turbine performance by contracting the flow path gradually from the open mouth of the duct to the rotor. The duct augmentation can significantly enhance the power and torque output. Furthermore, the elliptic shape enables the best performance of the turbine. The numerical results prove the capability of the present 2D model for the unsteady hydrodynamics and an operating performance analysis of the vertical tidal stream turbine.

  8. Application of 2D Numerical Model to Unsteady Performance Evaluation of Vertical-Axis Tidal Current Turbine

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen; QU Hengliang; SHI Hongda; HU Gexing; HYUN Beom-Soo

    2016-01-01

    Tidal current energy is renewable and sustainable, which is a promising alternative energy resource for the future elec-tricity supply. The straight-bladed vertical-axis turbine is regarded as a useful tool to capture the tidal current energy especially under low-speed conditions. A 2D unsteady numerical model based on Ansys-Fluent 12.0 is established to conduct the numerical simulation, which is validated by the corresponding experimental data. For the unsteady calculations, the SST model, 2×105and 0.01s are se-lected as the proper turbulence model, mesh number, and time step, respectively. Detailed contours of the velocity distributions around the rotor blade foils have been provided for a flow field analysis. The tip speed ratio (TSR) determines the azimuth angle of the appearance of the torque peak, which occurs once for a blade in a single revolution. It is also found that simply increasing the incident flow velocity could not improve the turbine performance accordingly. The peaks of the averaged power and torque coeffi-cients appear at TSRs of 2.1 and 1.8, respectively. Furthermore, several shapes of the duct augmentation are proposed to improve the turbine performance by contracting the flow path gradually from the open mouth of the duct to the rotor. The duct augmentation can significantly enhance the power and torque output. Furthermore, the elliptic shape enables the best performance of the turbine. The numerical results prove the capability of the present 2D model for the unsteady hydrodynamics and an operating performance analy-sis of the vertical tidal stream turbine.

  9. Near shore waves, long-shore currents and sediment transport along micro-tidal beaches, central west coast of India

    Institute of Scientific and Technical Information of China (English)

    Sajiv Philip CHEMPALAYIL; V Sanil KUMAR; G Udhaba DORA; Glejin JOHNSON

    2014-01-01

    Coastlines are undergoing constant geomorphologic changes with respect to the incident wave climate. Based on waves measured at 9 m water depth, simulation of near shore wave transformation is done using REFDIF-1 numerical model and the near shore breaker parameters are estimated at two micro-tidal beaches along central west coast of India. Model results are validated with measured values. From the breaker parameters, long-shore current and long-shore sediment transport rates (LSTR) are computed by using semi-empirical equations. Estimated long-shore current and LSTR are showing dramatic variations with respect to seasons. Predominant direction of LSTR is observed towards north since the approach waves are from south-west direction during pre-monsoon and post monsoon. During monsoon season, waves are from west south-west and resulted in southerly transport. The estimated annual net and gross LSTR by Cambridge Environmental Research Consultants (CERC) at two locations are in the same order whereas LSTR estimated by Walton & Bruno and Kamphuis equations are showing different estimations because of difference in surf-zone width and foreshore slope between the two locations. For micro-tidal beaches with length less than 6 km, Kamphuis equation is giving agreeable estimation of LSTR. Sensitivity analysis of LSTR estimate shows that coastal inclination is the prominent factor in determining LSTR than incident wave angle.

  10. A three-dimensional model of tidal currents in the mouth of the Tagus estuary

    Science.gov (United States)

    Fortunato, AndréB.; Baptista, António M.; Luettich, Richard A.

    1997-12-01

    Three-dimensional simulations of barotropic tides are used to investigate the complex circulation at the mouth of the Tagus estuary. Comparison with field data shows that elevations are well represented in the main area of interest, but velocities are slightly over-predicted due to a simplified treatment of intertidal flats. Model results show the existence of strong velocity phase lags (up to 1.75 hours for the semi-diurnal constituents) between the shallow areas and the deep channel. These phase lags are partially responsible for the generation by advective accelerations of a strong residual velocity field (velocities reach 0.5 m s -1) with well defined eddies. The interaction between the residual and tidal velocity fields in turn generates strong chaotic stirring. Localized sigma coordinates (LSC), a recently proposed method which allows the number of nodes per vertical to vary horizontally, are used for the first time in a three-dimensional application. A previously proposed criterion for the horizontal distribution of the total number of vertical nodes is shown to be inadequate when advective accelerations are important. However, with an alternative criterion, the use of LSC reduces maximum errors by a factor of two relative to traditional sigma coordinates.

  11. Optimization of hydrofoil for tidal current turbine based on particle swarm optimization and computational fluid dynamic method

    Directory of Open Access Journals (Sweden)

    Zhang De-Sheng

    2016-01-01

    Full Text Available Both efficiency and cavitation performance of the hydrofoil are the key technologies to design the tidal current turbine. In this paper, the hydrofoil efficiency and lift coefficient were improved based on particle swarm optimization method and XFoil codes. The cavitation performance of the optimized hydrofoil was also discussed by the computational fluid dynamic. Numerical results show the efficiency of the optimized hydrofoil was improved 11% ranging from the attack angle of 0-7° compared to the original NACA63-818 hydrofoil. The minimum pressure on leading edge of the optimized hydrofoil dropped above 15% at the high attack angle conditions of 10°, 15°, and 20°, respectively, which is benefit for the hydrofoil to avoiding the cavitation.

  12. Cross-shelf transport of pink shrimp larvae: Interactions of tidal currents, larval vertical migrations and internal tides

    Science.gov (United States)

    Criales, Maria M.; Browder, Joan A.; Mooers, C.N.K.; Robblee, M.B.; Cardenas, H.; Jackson, Thomas L.

    2007-01-01

    Transport and behavior of pink shrimp Farfantepenaeus duorarum larvae were investigated on the southwestern Florida (SWF) shelf of the Gulf of Mexico between the Dry Tortugas spawning grounds and Florida Bay nursery grounds. Stratified plankton samples and hydrographic data were collected at 2 h intervals at 3 stations located on a cross-shelf transect. At the Marquesas station, midway between Dry Tortugas and Florida Bay, internal tides were recognized by anomalously cool water, a shallow thermocline with strong density gradients, strong current shear, and a high concentration of pink shrimp larvae at the shallow thermocline. Low Richardson numbers occurred at the pycnocline depth, indicating vertical shear instability and possible turbulent transport from the lower to the upper layer where myses and postlarvae were concentrated. Analysis of vertically stratified plankton suggested that larvae perform vertical migrations and the specific behavior changes ontogenetically; protozoeae were found deeper than myses, and myses deeper than postlarvae. Relative concentrations of protozoea in the upper, middle and bottom layers were consistent with a diel vertical migration, whereas that of postlarvae and myses were consistent with the semidiurnal tides in phase with the flood tide. Postlarvae, the shallowest dwellers that migrate with a semidiurnal periodicity, experienced the largest net onshore flux and larval concentrations were highly correlated with the cross-shelf current. These results provide the first evidence of an onshore tidal transport (a type of selective tidal stream transport, STST), in decapod larvae migrating in continental shelf waters offshore, ca. 100 km from the coast and at a depth of 20 m, while approaching the coastal nursery grounds. Longer time series would be necessary to establish whether internal tides play any role in the larval onshore transport of this species and determine if the STST is the dominant onshore transport mechanism.

  13. Oceanography of Wadge bank - current measurements over a tidal cycle off the south coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    RamaRaju, V.S.; RameshBabu, V.; Anto, A.F.

    Direct current measurements made during the onset and termination of SW monsoon indicate wide fluctuations in space and time. The nearshore current decreases in magnitude from the onset to the termination of the monsoon. The resultant surface...

  14. Three-dimensional numerical simulation of M2 internal tides in the Luzon Strait

    Institute of Scientific and Technical Information of China (English)

    LI Bingtian; CAO Anzhou; LV Xianqing

    2015-01-01

    A three-dimensional isopycnic-coordinate internal tidal model is employed to investigate the generation, propagation, vertical structure and energy conversion of M2 internal tides in the Luzon Strait (LS) with mooring observations. Simulated results, especially the tidal current amplitudes, agree well with observations, demonstrating the reasonability and accuracy of the model. Results indicate that M2 internal tides mainly propagate into three directions horizontally, i.e., eastward towards the western Pacific Ocean, westward towards the Dongsha Island and southwestward towards the South China Sea Basin. In the horizontal direction, tidal current amplitudes decrease as distance increases away from the LS; in the vertical direction, they show an obvious decreasing tendency with depth. Between the double ridges of the LS, a clockwise gyre of M2 baroclinic energy flux appears, which is caused by reflections of M2 internal tides at supercritical topographies, and resonance of M2 internal tides happens along 19.5° and 21.5°N due to the heights and separation distance of the double ridges. The total energy conversion in the LS is about 14.20 GW.

  15. Tidal analysis in the venturi-shaped area between Zhenhai and Shenjiamen in the East China Sea

    Institute of Scientific and Technical Information of China (English)

    L(U) Huaqing; HU Jianjiong

    2009-01-01

    In order to better understand the general tidal features in the venturi-shaped area between Zhenhai and Shenjiamen in the northern coastal region of Zhejiang Province in the East China Sea, the tidal data were obtained from both the three permanent tide stations of Zhenhai, Dinghai and Shenjiamen, and four temporary tide stations of Mamu, Chuanshan, Guoju and Liuheng, along with the current speed being observed at Luotou Waterway. Results from harmonic analysis show that: (1) The area was dominated by shallow water tides with irregular semi-diurnal features, and the smallest tidal range occurred in the area near a crossing line between Zhenhai and Dinghai stations, indicating that a tidal node existed in the southern Hangzhou Bay; (2) Formulae, HS2/HM2 >0.4 and gM2-(gK1+gO1)=270° (where H and g are harmonic constants), could be used as judging criteria for high and low tidal level diurnal inequalities; (3) The duration difference between ebb and flood tides could be roughly assessed by the ratio of HM4 vs. HM2; and the larger the ratio is, the bigger the duration difference is. At the same time, the duration period could be assessed by 2gM2-gM4, the epoch difference between M2 and M4 tidal constituents. If 2gM2-gM4 <180°, then the ebb duration is longer than the flood duration; if 180°< 2gM2-gM4 <360°, the result is reversed; (4) Taking Dinghai station as a center point, the highest tidal levels and the average high tidal levels, as well as the average tidal ranges at all stations became higher and larger both southeastwards and northwestwards, while the lowest tidal levels and the average low tidal levels appeared to be lower both southeastwards and northwestwards; and (5) The tidal patterns were not all in line with the tidal current patterns. As a conclusion, the smallest tidal range occurred in the narrow part of the venturi-shaped area. Along the both sides of the area, the highest tidal level and tidal range became higher and larger, while the lowest

  16. Tidal influence on the seasonal variation in current and salinity around Willingdon Island

    Digital Repository Service at National Institute of Oceanography (India)

    Varma, P.U.; Pylee, A.; RamaRaju, V.S.

    varies from 5 ppt at the surface to 25 ppt at the bottom during flood tide. The flood and ebb currents are comparatively high in the Ernakulam channel than in the Mattancherry channel. The ebb currents are strong in the surface layers and the flood...

  17. Estimates of global M2 internal tide energy fluxes using TOPEX/POSEIDON altimeter data

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yanwei; LIANG Xinfeng; TIAN Jiwei; YANG Lifen

    2009-01-01

    TOPEX/POSEIDON altimeter data from October 1992 to June 2002 are used to calculate the global barotropic M2 tidal currents using long-term tidal harmonic analysis. The tides calculated agree well with ADCP data obtained from the South China Sea (SCS). The maximum tide velocities along the semi-major axis and semi-minor axis can be computed from the tidal ellipse. The global distribution of M2 internal tide vertical energy flux from the sea bottom is calculated based on a linear internal wave generation model. The global vertical energy flux of M2 internal tide is 0.96 TW, with 0.36 TW in the Pacific, 0.31 TW in the Atlantic and 0.29 TW in the Indian Ocean, obtained in this study. The total horizontal energy flux of M2 internal tide radiating into the open ocean from the lateral boundaries is 0.13 TW, with 0.06 TW in the Pacific, 0.04TW in the Atlantic, and 0.03 TW in the Indian Ocean. The result shows that the principal lunar semi-diurnal tide M2 provides enough energy to maintain the large-scale thermohaline circulation of the ocean.

  18. Tidal and low-frequency currents along the CK Line (31 deg 45 min N) over the East China Sea shelf

    Science.gov (United States)

    Yoshikawa, Yutaka; Matsuno, Takeshi; Wagawa, Taku; Hasegawa, Toru; Nishiuchi, Kou; Okamura, Kazumaro; Yoshimura, Hiroshi; Morii, Yasuhiro

    2012-12-01

    The bottom-mounted and ship-mounted ADCP velocities were analyzed to quantify tidal and low-frequency currents between 124.0 deg E and 128.5 deg E over the CK line (31 deg 45 min N) in the East China Sea shelf. The bottom-mounted ADCP, deployed in summer and autumn at station 1 (127 deg 25 min E) or station 2 (125 deg 30 min E), reveals relatively large (≃0.2ms-1) mean currents to the north or northwest at station 1 and a small (≤0.03ms-1) eastward current at station 2, as well as large tidal currents whose major axis amplitude amounts to 0.25ms-1 at station 1 and 0.5ms-1 at station 2. The bottom-mounted ADCP velocities were used to correct the tidal harmonic coefficients of the NAO.99Jb model under the assumption of uniform correction coefficients. The corrected coefficients were then used to remove the tidal currents in the ship-mounted ADCP velocity obtained over the whole CK-line. The detided ship-mounted ADCP velocities, which agree well with the bottom-mounted ADCP velocities at stations 1 and 2, show a more detailed spatial structure of the low-frequency current and its seasonal variations. The overall structure is characterized by a large northward/northwestward current in the eastern part and a small eastward current in the western part. The northward/northwestward current is largest (0.24ms-1) and most baroclinic in summer, while it becomes weakest (0.11ms-1) and most barotropic in winter. The zonal position of the boundary between the northward/northwestward current and the eastward current changes seasonally.

  19. Continuous measurements of discharge from a horizontal acoustic Doppler current profiler in a tidal river

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Buschman, F.A.; Vermeulen, B.

    2009-01-01

    Acoustic Doppler current profilers (ADCPs) can be mounted horizontally at a river bank, yielding single-depth horizontal array observations of velocity across the river. This paper presents a semideterministic, semistochastic method to obtain continuous measurements of discharge from horizontal ADCP

  20. Continuous river discharge monitoring with bottom-mounted current profilers at narrow tidal estuaries

    Science.gov (United States)

    Garel, E.; D'Alimonte, D.

    2017-02-01

    The objective of this study is to verify whether accurate and continuous estimates of freshwater discharge at the mouth of a narrow estuary with a single channel can be obtained from a bottom-mounted current profiler (ADCP). The focus is on moderate- to high-discharge events that significantly affect the water circulation corresponding to low river flow conditions. Observations at the Guadiana Estuary (southern Iberia) indicate lateral subtidal flow variability, constant cross-channel area, and quasi-steady response of the axial velocity to discharge events. Based on the concept of maximum entropy, the mean and maximum channel velocities were related by a constant ratio, Ω, using data from three cross-channel surveys. This relationship was then used to estimate the freshwater discharge at the mouth based on the maximum velocity obtained from the detided ADCP velocity profiles. This approach was possible because the ADCP was deployed near the position of maximum current velocity, that is, over the deepest part of the channel. The results show good correspondence with observations, indicating that the entropy model can complete or substitute the records from upstream gauged stations that do not include the contribution from downstream tributaries. A Multilayer Perceptron neural net (MLP) based on the entropy approach was then implemented with the purpose of estimating the discharge when Ω is unknown. This latter analysis showsthat the relationship between maximum velocity and discharge is quasi-stationary. Consequently, the MLP can successfully estimate freshwater runoff if the training data represent all statistical properties of the river discharge dynamics. The results also indicate that Ω may vary not only with concomitant hydrographic conditions, but also with the recent (i.e., several days prior) discharge magnitude.

  1. The M2 Channel

    DEFF Research Database (Denmark)

    Santner, Paul

    and inhibition mechanisms, drug design studies were recently able to achieve successes in finding new potent inhibitors, some of which are even able to inhibit resistant M2 variants. Effective and robust methods for measuring M2 activity on the other hand are still scarce and tactics to assess the genetic...... barrier of new inhibitors as well as resistance development non-existent. Therefore we developed a fluorescence sensor based assay that directly measures proton conduction (pHlux assay) and combined it with an already established directed evolution selection and screening system of M2 to identify possible...... resistance escape routes from drug inhibition. We thereby were hopefully able to provide a platform for the large-scale evaluation of M2 channel activity, inhibitors and resistance....

  2. Tidal analysis in the venturi-shaped area between Zhenhai and Shenjiamen in the East China Sea

    Science.gov (United States)

    Lü, Huaqing; Hu, Jianjiong

    2009-02-01

    In order to better understand the general tidal features in the venturi-shaped area between Zhenhai and Shenjiamen in the northern coastal region of Zhejiang Province in the East China Sea, the tidal data were obtained from both the three permanent tide stations of Zhenhai, Dinghai and Shenjiamen, and four temporary tide stations of Mamu, Chuanshan, Guoju and Liuheng, along with the current speed being observed at Luotou Waterway. Results from harmonic analysis show that: (1) The area was dominated by shallow water tides with irregular semi-diurnal features, and the smallest tidal range occurred in the area near a crossing line between Zhenhai and Dinghai stations, indicating that a tidal node existed in the southern Hangzhou Bay; (2) Formulae, H_{S_2 } /H_{M_2 } > 0.4 and g_{M_2 } - (g_{K_1 } + g_{O_1 } ) =270° (where H and g are harmonic constants), could be used as judging criteria for high and low tidal level diurnal inequalities; (3) The duration difference between ebb and flood tides could be roughly assessed by the ratio of H_{M_4 } vs. H_{M_2 } ; and the larger the ratio is, the bigger the duration difference is. At the same time, the duration period could be assessed by 2g_{M_2 } - g_{M_4 } , the epoch difference between M 2 and M 4 tidal constituents. If 2g_{M_2 } - g_{M_4 } venturi-shaped area. Along the both sides of the area, the highest tidal level and tidal range became higher and larger, while the lowest tidal level became lower with the increase of the distance from the narrow throat area. This is somehow different from the theory that the tidal level increases gradually when it moves towards the top narrow area of a V-shaped bay or estuary.

  3. Modeling Evaluation of Tidal Stream Energy and the Impacts of Energy Extraction on Hydrodynamics in the Taiwan Strait

    Directory of Open Access Journals (Sweden)

    Ming-Hsi Hsu

    2013-04-01

    Full Text Available Tidal stream speeds in straits are accelerated because of geographic and bathymetric features. For instance, narrow channels and shallows can cause high tidal stream energy. In this study, water level and tidal current were simulated using a three-dimensional semi-implicit Eulerian-Lagrangian finite-element model to investigate the complex tidal characteristics in the Taiwan Strait and to determine potential locations for harnessing tidal stream energy. The model was driven by nine tidal components (M2, S2, N2, K2, K1, O1, P1, Q1, and M4 at open boundaries. The modeling results were validated with the measured data, including water level and tidal current. Through the model simulations, we found that the highest tidal currents occurred at the Penghu Channel in the Taiwan Strait. The Penghu Channel is an appropriate location for the deployment of a tidal turbine array because of its deep and flat bathymetry. The impacts of energy extraction on hydrodynamics were assessed by considering the momentum sink approach. The simulated results indicate that only minimal impacts would occur on water level and tidal current in the Taiwan Strait if a turbine array (55 turbines was installed in the Penghu Channel.

  4. Study on the Log-Linear Velocity Profile of Near-Bed Tidal Current in Estuarine and Coastal Waters

    Institute of Scientific and Technical Information of China (English)

    SONG Zhi-yao; YAN Yi-xin; HAO Jia-ling; KONG Jun; ZHANG Hong-gui

    2006-01-01

    Many observed data show that the near-bed tidal velocity profile deviates from the usual logarithmic law. The amount of deviation may not be large, but it results in large errors when the logarithmic velocity profile is used to calculate the bed roughness height and friction velocity (or shear stress). Based on their investigation, Kuo et al. (1996) indicate that the deviation amplitude may exceed 100%. On the basis of fluid dynamic principle, the profile of the near-bed tidal velocity in estuarine and coastal waters is established by introducing Prandtl's mixing length theory and Von Karman self-similarity theory. By the fitting and calculation of the near-bed velocity profile data observed in the west Solent, England, the results are compared with those of the usual logarithmic model, and it is shown that the present near-bed tidal velocity profile model has such advantages as higher fitting precision, and better inner consistency between the roughness height and friction velocity. The calculated roughness height and friction velocity are closer to reality. The conclusions are validated that the logarithmic model underestimates the roughness height and friction velocity during tidal acceleration and overestimates them during tidal deceleration.

  5. Study on an accelerated diffuser of tidal current power generation%潮流能发电增速导流罩研究

    Institute of Scientific and Technical Information of China (English)

    荆丰梅; 张亮; 张鹏远; 肖立家

    2012-01-01

    In order to prolong the working time of turbines during one cycle of tidal current, and obtain more power of generation for a turbine which generates power by making use of tidal current energy, a new kind of accelerated diffuser for a horizontal tidal current turbine was designed. The computational fluid dynamics ( CFD) method was used to calculate performance of this diffuser, and an experiment was carried out to validate simulation results. A comparison between simulation results and experimental results shows thai the accelerated diffuser can reduce the serf-starting speed of the turbine and significantly increase the power obtained. The research on a accelerated diffuser of tidal current power generation provides a way to compensate for energy shortage. It is also significant for out-ting back on environmental pollution.%为提高潮流能水轮机的发电功率同时延长一个潮流周期内的可发电时间,采用数值计算(CFD)方法对一种新型水平轴水轮机增速导流罩的主要参数进行理论研究,并通过水池模型试验对计算结果进行验证.研究结果表明:增速导流罩可降低水轮机的启动流速,同时可以使水轮机发电功率得到显著提高,从而增加发电量.潮流能发电增速导流装置的研究将对弥补能源短缺,缓解环境污染起到重要作用.

  6. 成山头海域潮流能资源可开发量评估%ASSESSMENT OF EXTRACTABLE ENERGY OF TIDAL CURRENT AT CHENGSHANTOU CAPE

    Institute of Scientific and Technical Information of China (English)

    武贺; 王鑫; 韩林生

    2013-01-01

    针对潮流能资源较丰富的成山头外海域,利用FVCOM数值模式,在良好模拟该海域潮流场的基础上,运用能量耗散原理,对该海域的潮流能资源可开发量进行了评估.结果表明,在转换装置的拖拽系数为0.07时,面积为27km2的成山头近岸海域的可开发潮流能资源约为17.9MW,其中大潮期间的可开发量高达37.7MW,而小潮期间则为7.3MW.在此条件下,该海域大潮期间涨急和落急时刻的流速分别减小了40%和38%,但发电装置对潮汐的影响较小,在成山头顶端的高潮潮位仅下降了4cm.%In this study,the extractable energy resource of the tidal current is estimated using the FVCOM model in the open sea area of the Chengshantou Cape in the area of 27km2,which is known as an area of good potential in the exploitability of tidal current energy.Based on the energy dissipation principle,simulation of the tidal current in this area was performed to estimate the available energy quantity.Our results show that when the drag coefficient of turbines is 0.07,the available energy of the tidal current for the area is 17.9MW,and during the periods of spring tide and neap tide,the estimated energy quantity is 37.7MW and 7.3MW,respectively.The maximum decrease in the current velocity in the flood period and ebb period is 40% and 38%,respectively.However,the tidal level is slightly affected by turbines,which decreases by 4cm only in the spring tide period at the tip of the Chengshantou Cape.

  7. Numerical simulation of tides and tidal currents in the Beibu Gulf and Guangxi coastal areas%北部湾及广西近海潮流数值模拟

    Institute of Scientific and Technical Information of China (English)

    施华斌; 牛小静; 余锡平

    2012-01-01

    该文采用二维浅水模型模拟分析了北部湾海域潮流系统,并在此基础上建立了广西沿海一、二维耦合水动力模型,模型中考虑了广西沿岸6条主要入海河流对近岸水动力的影响,进一步分析了广西近海海域潮致余流场及其对近海污染物输移扩散的影响。模型潮位计算值和实测值符合良好。结果显示:K1分潮在北部湾口形成一个逆时针旋转潮波系统,M2分潮在湾顶越南海防附近形成逆时针旋转潮波系统,广西近海海域K1分潮占优。广西沿海海域内,离岸较近的海域余流场相对较强,余流速度受浅水效应及湾口等地形缩窄影响而增强;离岸较远海域余流明显减弱,水体交换能力降低。%A two dimensional numerical model was used to simulate the tides in the Beibu Gulf. A 1 13 and 2 D coupled numerical model was then used to simulate the tidal currents to analyze pollutant transport in Guangxi coastal areas, north of the Beibu Gulf. The simulations of the tides and tidal currents are in good agreement with observationss. In the Beibu Gulf, K1 is a counterclockwise rotating system with the amphidromic point located in the baymouth. M2 is also a counterclockwise rotating system with the amphidromic point in the north, close to Hal Phong, Vietnam. ]n the Guangxi coastal areas, the tide-induced residual currents in the areas near the shore are much stronger than those further away. The shallow water and narrowed baymouth strengthen the residual currents.

  8. Experimental study on rectangular tidal current turbines%矩形潮流能水轮机性能的实验研究

    Institute of Scientific and Technical Information of China (English)

    陈展; 马勇; 张亮; 苏国卿

    2013-01-01

    To study the performance of rectangular tidal current turbines,a rectangular tidal current turbine and its experimental model were designed.An experiment platform was established and the experiment instrument and devices were selected.Then,some experiments were conducted,including the model of reciprocating flow experiment,the changing installation angle experiments,the impact of compactness experiment and the output power in different flow velocity experiment.The experimental results show that the rectangular tidal current turbine has good two-way flow of unidirectional rotation characteristic and the forward and reverse flows with the same energy capture capacity in the case of a constant flow velocity; when installation angle Ψ=±15°,the tidal turbine's ability of energy-capture is superior to the one when the installation angle Ψ=± 5°; the tidal turbine's ability of energycapture increases as the compactness increases within different speed ratio intervals; the peak value of output power increases with the increase of the flow velocity and the peak point moves right.%为了研究矩形潮流能水轮机的性能,设计了矩形潮流能水轮机及其实验模型装置,构建了实验平台,选配了实验仪器和设备,进行矩形潮流能水轮机模型的往复流及变安装摆角实验、密实度影响实验和不同流速下的功率输出实验.实验结果表明:矩形水轮机具有良好的双向来流单向旋转特性,在来流速度大小恒定的情况下,正向来流和反向来流具有相同的能量捕获能力;当安装摆角Ψ=±15°时,水轮机的能量捕获能力优于Ψ=±5°时的;不同速比区间内,随密实度增加,水轮机的获能能力也相应增加;流速增加,输出功率峰值增大,峰值点右移.

  9. Effect of variable winds on current structure and Reynolds stresses in a tidal flow: analysis of experimental data in the eastern English Channel

    Directory of Open Access Journals (Sweden)

    K. A. Korotenko

    2012-11-01

    Full Text Available Wind and wave effects on tidal current structure and turbulence throughout the water column are examined using an upward-looking acoustic Doppler current profiler (ADCP. The instrument has been deployed on the seafloor of 18-m mean depth, off the north-eastern French coast in the eastern English Channel, over 12 tidal cycles, and covered the period of the transition from mean spring to neap tide, and forcing regimes varied from calm to moderate storm conditions. During storms, we observed gusty winds with magnitudes reaching 15 m s−1 and wave heights reaching up to 1.3 m. Analysis of velocity spectra revealed a noticeable contribution of wind-induced waves to spectral structure of velocity fluctuations within the subsurface layer. Near the surface, stormy winds and waves produced a significant intensification of velocity fluctuations, particularly when the sustained wind blew against the ebb tide flow. As during wavy periods, the variance-derived Reynolds stress estimates might include a wave-induced contamination, we applied the Variance Fit method to obtain unbiased stresses and other turbulent quantities. Over calm periods, the turbulent quantities usually decreased with height above the seabed. The stresses were found to vary regularly with the predominantly semidiurnal tidal flow. The along-shore stress being generally greater during the flood flow (~2.7 Pa than during the ebb flow (~−0.6 Pa. The turbulent kinetic energy production rate, P, and eddy viscosity, Az, followed a nearly regular cycle with close to a quarter-diurnal period. As for the stresses, near the seabed, we found the maximum values of estimated quantities of P and Az to be 0.1 Wm−3 and 0.5 m2 s−1, respectively, during the flood flow. Over the storm periods, we found the highest unbiased stress values (~−2.6 Pa during ebb when tidal currents were opposite to the

  10. Field testing of a convergent array of acoustic Doppler profilers for high-resolution velocimetry in energetic tidal currents

    Energy Technology Data Exchange (ETDEWEB)

    Harding, Samuel F.; Sellar, Brian; Richmond, Marshall C.

    2016-04-25

    An array of single-beam acoustic Doppler profilers has been developed for the high resolution measurement of three-dimensional tidal flow velocities and subsequently tested in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use divergent acoustic beams emanating from a single instrument. This is achieved using geometrically convergent acoustic beams creating a sample volume at the focal point of 0.03 m3. Away from the focal point, the array is also able to simultaneously reconstruct three-dimensional velocity components in a profile throughout the water column, and is referred to herein as a convergent-beam acoustic Doppler profiler (C-ADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational commercial-scale Alstom 1MW DeepGen-IV Tidal Turbine deployed at the European Marine Energy Center, Orkney Isles, UK. This proof-of-concept paper outlines the C-ADP system configuration and comparison to measurements provided by co-installed reference instrumentation.

  11. What is $\\Delta m^2_{ee}$ ?

    CERN Document Server

    Parke, Stephen

    2016-01-01

    The current short baseline reactor experiments, Daya Bay and RENO (Double Chooz) have measured (or are capable of measuring) an effective $\\Delta m^2$ associated with the atmospheric oscillation scale of 0.5 km/MeV in electron anti-neutrino disappearance. In this paper, I compare and contrast the different definitions of such an effective $\\Delta m^2$ and argue that the simple, L/E independent, definition given by $\\Delta m^2_{ee} \\equiv \\cos^2 \\theta_{12} \\Delta m^2_{31}+ \\sin^2 \\theta_{12} \\Delta m^2_{32}$, i.e. "the $\

  12. Homogeneous M2 duals

    CERN Document Server

    Figueroa-O'Farrill, José

    2015-01-01

    Motivated by the search for new gravity duals to M2 branes with $N>4$ supersymmetry --- equivalently, M-theory backgrounds with Killing superalgebra $\\mathfrak{osp}(N|4)$ for $N>4$ --- we classify (except for a small gap) homogeneous M-theory backgrounds with symmetry Lie algebra $\\mathfrak{so}(n) \\oplus \\mathfrak{so}(3,2)$ for $n=5,6,7$. We find that there are no new backgrounds with $n=6,7$ but we do find a number of new (to us) backgrounds with $n=5$. All backgrounds are metrically products of the form $\\operatorname{AdS}_4 \\times P^7$, with $P$ riemannian and homogeneous under the action of $\\operatorname{SO}(5)$, or $S^4 \\times Q^7$ with $Q$ lorentzian and homogeneous under the action of $\\operatorname{SO}(3,2)$. At least one of the new backgrounds is supersymmetric (albeit with only $N=2$) and we show that it can be constructed from a supersymmetric Freund--Rubin background via a Wick rotation. Two of the new backgrounds have only been approximated numerically.

  13. Tidal hydrodynamics in a two-inlet coastal lagoon in the Gulf of California

    Science.gov (United States)

    Serrano, David; Ramírez-Félix, Evlin; Valle-Levinson, Arnoldo

    2013-07-01

    The aim of this study is to understand the effects of friction and advection in the hydrodynamics of a two-inlet coastal lagoon, Santa María La Reforma, in Northwest Mexico. A vertically integrated numerical model is used to describe sea level variations and tidal currents, and to study the dynamics inside the system. Observed sea level and current measurements were used to calibrate the model. Results show a ˜90 min phase lag of the tidal signal in the center of the system with respect to both inlets. Tidal currents greater than 1.0 m s-1 were recorded and modeled at both inlets. The sea level in the lagoon shows one-quarter of period of M2 out of phase (˜3 h) with respect to the velocity. Bottom friction generated the greatest M4 harmonic and largest tidal asymmetries at the narrowest section of the lagoon, ˜35 km away from the inlets. The tidal momentum balance along the main axis of the lagoon was dominated by pressure gradient and friction, describing a quasi-standing tidal wave in currents and in amplitude. This behavior resulted from waves traveling in opposite directions from the two tidal inlets, causing constructive interference in elevation but destructive interference inflow.

  14. 潮流能水轮机叶片设计与计算%Design and Computation about Blades of Tidal Current Turbine

    Institute of Scientific and Technical Information of China (English)

    赵陈; 刘羽; 陈正寿; 沈志华; 黄聪汉; 赵春慧

    2015-01-01

    叶片作为潮流能水轮机的关键部位,其设计水准直接关系到水轮机性能的优劣。基于风力机相关的叶片设计方法,辅以翼型设计分析技术和数据编程优化软件对新近提出的一种轴流式潮流能水轮机的叶片进行优化设计。对优化后水轮机叶片在不同转速下的工作效率数值仿真分析结果显示,设定转速100 r/min的水轮机在设定工况范围内有较好的输出效率。另外,带15°攻角的折线型导流罩结构可以极大提高水轮机的工作效率,相同工况下比无导流罩式水轮机输出功率提高30%。%As a critical part of tidal current energy conversion device, the turbine plays an important role to determine whether the hydrodynamic performance is well or not. By means of the design and analysis methods for wind turbine blade, the turbine blades of an axial-flow tidal current turbine newly developed by the author have been optimized. The results attributing to numerical simulation show that it has nice conversion efficiency when the turbine is set to revolve at speed 100 r/min. Otherwise, it has been found that the polygonal duct with 15? attacked angle has good hydrodynamic performances and can greatly improve the efficient of the tidal current turbine system. It has been testified that in the case of same conditions, the output conversion power of tidal current turbine with duct is about 30%larger than that that concerning the case without it.

  15. Ocean tidal signals in observatory and satellite magnetic measurements

    DEFF Research Database (Denmark)

    Maus, S.; Kuvshinov, A.

    2004-01-01

    Ocean flow moves sea water through the Earth's magnetic field, inducing electric fields, currents and secondary magnetic fields. These motionally induced magnetic fields have a potential for the remote sensing of ocean flow variability. A first goal must be to gain a better understanding...... of magnetic field generation by tidal ocean flow. We predict the motionally induced magnetic fields for the six major tidal constituents and compare their amplitudes with the spectra of night time observatory and satellite magnetic measurements for the Indian Ocean. The magnetic variations at the solar S2, K1......, and P1 periods turn out to be dominated by unrelated external fields. In contrast, observed lunar M2 and N2 tidal signals are in fair agreement with predictions from motional induction. The lunar diurnal O1 signal, visible at some observatories, could be caused by ocean flow but disagrees in amplitude...

  16. Effect of variable winds on current structure and Reynolds stresses in a tidal flow: analysis of experimental data in the Eastern English Channel

    Directory of Open Access Journals (Sweden)

    K. A. Korotenko

    2012-06-01

    Full Text Available Wind and wave effects on tidal current structure and turbulence throughout the water column are examined using an upward-looking acoustic Doppler current profiler (ADCP. The instrument has been deployed on the seafloor of 20-m depth, off the North-Eastern French coast in the Eastern English Channel over 12 tidal cycles and covered the period of the transition from mean spring to neap tide and forcing regimes varied from calm to moderate storm conditions. During storms, we observed gusty winds with magnitude reached 15 m s−1 and wave height reached up to 1.3 m. Analysis of velocity spectra revealed a noticeable contribution of wind-induced waves to spectral structure of velocity fluctuations within the upper 10-m layer. Near the surface, stormy winds and waves produced a significant intensification of velocity fluctuations, particularly when the sustained wind blew against the ebb tide flow. As during wavy periods the variance-derived Reynolds stress estimates might include a wave-induced contamination, we applied the Variance Fit method to obtain unbiased stresses and other turbulent quantities. Over calm periods, the turbulent quantities usually decreased with height above the seabed. The stresses were found to vary regularly with the predominantly semidiurnal tidal flow, with the along-shore stress being generally greater during the flood flow (~2.7 Pa than during the ebb flow (~−0.6 Pa. The turbulent kinetic energy production rate, P, and eddy viscosity, Az}, followed a nearly regular cycle with close to a quarter-diurnal period. As for the stresses, near the seabed, we found the maximum values of estimated quantities of P and Az to be 0.1 W m−3 and 0.5 m2 s−1, respectively, during the flood flow. Over the storm periods, we found the highest stress values (~−2 Pa during ebb when tidal currents were opposite to the southwesterly winds while

  17. A large-eddy simulation study of wake propagation and power production in an array of tidal-current turbines.

    Science.gov (United States)

    Churchfield, Matthew J; Li, Ye; Moriarty, Patrick J

    2013-02-28

    This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally periodic precursor simulation is performed to create turbulent flow data. Then those data are used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modelled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. We found that staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement. For example, using a larger precursor domain would better capture elongated turbulent structures, and including salinity and temperature equations would account for density stratification and its effect on turbulence. Additionally, the wall shear stress modelling could be improved, and more array configurations could be examined.

  18. Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Churchfield, M. J.; Li, Y.; Moriarty, P. J.

    2012-07-01

    This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. Staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement, such as the use of a larger precursor domain to better capture elongated turbulent structures, the inclusion of salinity and temperature equations to account for density stratification and its effect on turbulence, improved wall shear stress modelling, and the examination of more array configurations.

  19. Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Churchfield, M. J.; Li, Y.; Moriarty, P. J.

    2011-07-01

    This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used to determine the inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. Staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement, such as the use of a larger precursor domain to better capture elongated turbulent structures, the inclusion of salinity and temperature equations to account for density stratification and its effect on turbulence, improved wall shear stress modeling, and the examination of more array configurations.

  20. M2M massive wireless access

    DEFF Research Database (Denmark)

    Zanella, Andrea; Zorzi, Michele; Santos, André F.

    2013-01-01

    of the current cellular standards. Here, we provide insights and introduce potential solutions for the cellular radio protocol that will allow the efficient support of Machine-to-Machine (M2M) communications. The paper focuses on the massive aspect of M2M. We will introduce PHY and MAC approaches such as Coded...... and research guidelines for enabling future networks to support efficiently M2M communications....

  1. Incorporating future change into current conservation planning: Evaluating tidal saline wetland migration along the U.S. Gulf of Mexico coast under alternative sea-level rise and urbanization scenarios

    Science.gov (United States)

    Enwright, Nicholas M.; Griffith, Kereen T.; Osland, Michael J.

    2015-11-02

    In this study, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, quantified the potential for landward migration of tidal saline wetlands along the U.S. Gulf of Mexico coast under alternative future sea-level rise and urbanization scenarios. Our analyses focused exclusively on tidal saline wetlands (that is, mangrove forests, salt marshes, and salt flats), and we combined these diverse tidal saline wetland ecosystems into a single grouping, “tidal saline wetland.” Collectively, our approach and findings can provide useful information for scientists and environmental planners working to develop future-focused adaptation strategies for conserving coastal landscapes and the ecosystem goods and services provided by tidal saline wetlands. The primary product of this work is a public dataset that identifies locations where landward migration of tidal saline wetlands is expected to occur under alternative future sea-level rise and urbanization scenarios. In addition to identifying areas where landward migration of tidal saline wetlands is possible because of the absence of barriers, these data also identify locations where landward migration of these wetlands could be prevented by barriers associated with current urbanization, future urbanization, and levees.

  2. Carbachol augments Na/Ca exchange current via M2 muscarinic receptors in guinea pig ventricular myocytes%氨甲酰胆碱通过M2毒蕈碱受体增加豚鼠心肌细胞钠钙交换电流

    Institute of Scientific and Technical Information of China (English)

    崔香丽; 陈还珍; 武冬梅; 吴博威

    2004-01-01

    Stimulation of cardiac mAChRs by carbachol (CCh) produces a biphasic inotropic response. The mechanisms of the positive inotropic response by higher concentration of CCh appear to be paradoxical. This article was aimed to study the mechanism of the positive inotropic effect of CCh in guinea pig ventricular myocytes. The effects of CCh on L-type calcium current (ICa) and Na/Ca exchange current (INa/Ca) were observed in voltage-clamped guinea pig ventricular myocytes by using Axon 200A amplifier. The results showed that CCh (100 μmol/L) increased both forword mode and reverse mode INa/Ca from (1.2±0.1) pA/pF to (2.0±0.3) pA/pF for forward mode (P<0.01) and from (1.3+0.5) pA/pF to (2.1+0.8) pA/pF for reverse mode (P<0.01), respectively. CCh had no effect on ICa. The stimulating effect of CCh on INa/Ca could be blocked by application of atropine, a nonselective blocker of muscarinic receptors,which means that the stimulating effect of CCh is through the activation of muscarinic receptors. We made a further study by using methoctramine, a selective antagonist of M2 muscarinic receptors. It completely abolished INa/Ca induced by 100 μmol/L CCh, indicating that the effect of CCh on INa/Ca was mediated by M2 muscarinic receptors. It is generally accepted that contraction in cardiac myocytes results from elevation of intracellular Ca2+ concentration. Ca2+ enters the cells through two pathways: L-type Ca2+ channels and, less importantly, reverse mode Na/Ca exchange. The calcium influx via both pathways promotes the contraction of cardiac myocytes.Because CCh had no effect on L-type Ca2+ current, the increase in Na/Ca exchange current might be the main factor in the positive inotropism of CCh. These results suggest that the positive inotropic effect of CCh in guinea pig heart is through stimulation of Na/Ca exchange and is mediated by M2 muscarinic receptors.%本文旨在研究氨甲酰胆碱(carbachol,CCh)对豚鼠心肌的正性变力性机制.用Axon200A膜片钳

  3. Design of full guide diffuser for tidal current generator%潮流发电机全向导流罩设计

    Institute of Scientific and Technical Information of China (English)

    陈登曜; 李维维; 刘彭听

    2016-01-01

    In order to adapt to the characteristics of the low speed of the tidal current, a new type of full guide diffuser which can significantly improve the efficiency of energy harvesting is designed. In order to reduce the manufacturing cost, the full guide diffuser is designed to be symmetrical structure. The full guide diffuser is applied to the vertical axis tidal current generator, which can be used to guide the flow of any direction from the outside of the turbine, which can significantly improve the efficiency of the energy harvesting efficiency of the turbine.%为了适应我国海洋潮流低速的特点,设计了一种可以显著提高捕能效率的新型全向导流罩。为了降低制造成本,全向导流罩设计成对称式结构。全向导流罩适用于竖轴潮流发电机,通过罩在水轮机的外围,可以对任意方向的来流进行导流,显著提高了水轮机的捕能效率。

  4. Numerical and experimental investigation on the performance of three newly designed 100 kW-class tidal current turbines

    Directory of Open Access Journals (Sweden)

    Museok Song

    2012-09-01

    Full Text Available Three types of 100 kW-class tidal stream turbines are proposed and their performance is studied both numerically and experimentally. Following a wind turbine design procedure, a base blade is derived and two additional blades are newly designed focusing more on efficiency and cavitation. For the three designed turbines, a CFD is performed by using FLUENT. The calculations predict that the newly designed turbines perform better than the base turbine and the tip vortex can be reduced with additional efficiency increase by adopting a tip rake. The performance of the turbines is tested in a towing tank with 700 mm models. The scale problem is carefully investigated and the measurements are compared with the CFD results. All the prediction from the CFD is supported by the model experiment with some quantitative discrepancy. The maximum efficiencies are 0.49 (CFD and 0.45 (experiment at TSR 5.17 for the turbine with a tip rake.

  5. Using Principal Component and Tidal Analysis as a Quality Metric for Detecting Systematic Heading Uncertainty in Long-Term Acoustic Doppler Current Profiler Data

    Science.gov (United States)

    Morley, M. G.; Mihaly, S. F.; Dewey, R. K.; Jeffries, M. A.

    2015-12-01

    Ocean Networks Canada (ONC) operates the NEPTUNE and VENUS cabled ocean observatories to collect data on physical, chemical, biological, and geological ocean conditions over multi-year time periods. Researchers can download real-time and historical data from a large variety of instruments to study complex earth and ocean processes from their home laboratories. Ensuring that the users are receiving the most accurate data is a high priority at ONC, requiring quality assurance and quality control (QAQC) procedures to be developed for all data types. While some data types have relatively straightforward QAQC tests, such as scalar data range limits that are based on expected observed values or measurement limits of the instrument, for other data types the QAQC tests are more comprehensive. Long time series of ocean currents from Acoustic Doppler Current Profilers (ADCP), stitched together from multiple deployments over many years is one such data type where systematic data biases are more difficult to identify and correct. Data specialists at ONC are working to quantify systematic compass heading uncertainty in long-term ADCP records at each of the major study sites using the internal compass, remotely operated vehicle bearings, and more analytical tools such as principal component analysis (PCA) to estimate the optimal instrument alignments. In addition to using PCA, some work has been done to estimate the main components of the current at each site using tidal harmonic analysis. This paper describes the key challenges and presents preliminary PCA and tidal analysis approaches used by ONC to improve long-term observatory current measurements.

  6. Estudo preliminar da maré e das correntes de maré da região estuarina de Cananéia (25ºS-48ºW Preliminary study of the tidal heights and currents of the estuarine region of Cananéia (25ºS-48ºW

    Directory of Open Access Journals (Sweden)

    Sadako Yadoya Miyao

    1989-01-01

    Full Text Available A preliminary study of tidal height and tidal current data from Cananéia region made through harmonic and spectral analysis shows different amplifications and phase delays of the principal tidal components inwards the estuary. M3 tidal component is particularly amplified in Mar de Cananéia - Mar Pequeno, probably because of near-resonance conditions in the channel. Tidal currents in Mar de Cubatâo and Mar de Cananéia show, besides the semidiurnal components, significative presence of M3 and M4 constituents. Residual current spectra show two main peaks: one, of tidal frequency, attributed to tidal pumping; another, of subtidal frequency, attributed to a long-period cumulative effect, associated to the estuary mean level variation.

  7. Tidal meanders

    Science.gov (United States)

    Marani, Marco; Lanzoni, Stefano; Zandolin, Diego; Seminara, Giovanni; Rinaldo, Andrea

    2002-11-01

    Observational evidence is presented on the geometry of meandering tidal channels evolved within coastal wetlands characterized by different tidal, hydrodynamic, topographic, vegetational and ecological features. New insight is provided on the geometrical properties of tidal meanders, with possible dynamic implications on their evolution. In particular, it is shown that large spatial gradients of leading flow rates induce important spatial variabilities of meander wavelengths and widths, while their ratio remains remarkably constant in the range of scales of observation. This holds regardless of changes in width and wavelength up to two orders of magnitude. This suggests a locally adapted evolution, involving the morphological adjustment to the chief landforming events driven by local hydrodynamics. The spectral analysis of local curvatures reveals that Kinoshita's model curve does not fit tidal meanders due to the presence of even harmonics, in particular the second mode. Geometric parameters are constructed that are suitable to detect possible geomorphic signatures of the transitions from ebb- to flood-dominated hydrodynamics, here related to the skewness of the tidal meander. Trends in skewness, however, prove elusive to measure and fail to show detectable patterns. We also study comparatively the spatial patterns of evolution of the ratios of channel width to depth, and the ratio of width to local radius of curvature. Interestingly, the latter ratio exhibits consistency despite sharp differences in channel incision. Since the degree of incision, epitomized by the width-to-depth ratio, responds to the relevant erosion and migrations mechanisms and is much sensitive to vegetation and sediment properties, it is noticeable that we observe a great variety of landscape carving modes and yet recurrent planar features like constant width/curvature and wavelength/width ratios.

  8. Influence of near-shore marine structures in a beach nourishment project on tidal currents in Haitan Bay, facing the Taiwan Strait

    Institute of Scientific and Technical Information of China (English)

    顾杰; 马悦; 王彬谕; Jueyi SUI; 匡翠萍; 刘建辉; 雷刚

    2016-01-01

    The Longfengtou Beach in the Haitan Bay, located in Fujian Province of China and facing the Haitan Strait, has been suffering severe erosion due to the construction of seawalls. A simple beach nourishment project implemented has not achieved the anticipated beach restoration. Thus a practical solution has to rely on a combination with near-shore marine structures. In this study, a 2-D calibrated flow model is set up to investigate the effects of three different layouts of near-shore marine structures on the tidal current. It is shown that the breakwaters situated in both the north and south ends play a vital part in the protection against erosion. The offshore breakwaters can serve as a barrier to obstruct the current circulation then reduce the current velocity. The groyne linking the Guimo islet and the coast significantly reduces the south-to-north water exchange through the channel and redirects the current direction nearly perpendicular to the north breakwater, which cuts off the longshore transport that may have a negative influence on the beach, especially, the northern part. It is also noted that the monsoon at the site with different directions increases the current velocity. In general, proper layouts of marine structures can reduce the current velocity thus lead to less intense sand transport near the beach.

  9. DEVELOPMENT STATUS, TREND AND THE PROBLEMS OF MECHANICS OF TIDAL CURRENT ENERGY 1)%潮流能开发现状、发展趋势及面临的力学问题1)

    Institute of Scientific and Technical Information of China (English)

    张理; 李志川

    2016-01-01

    随着化石能源大规模应用导致的环境污染问题日益严重,世界各国越来越关注清洁可再生能源的开发和利用.潮流能属于海洋可再生能源,清洁无污染且资源丰富,具有良好的开发前景.21世纪以来,潮流能开发在世界范围内取得较大进步,装机规模呈上升趋势,多种潮流能转换装置进入示范研究或准商业化阶段.在此方面,人们将面临如何利用研制生产的各类转换装置提高对潮流能的利用效率这一关键力学问题.通过调研和分析,详细梳理了我国潮流能资源状况、国内外开发利用最新状况、潮流能开发利用关键技术以及潮流能利用前景,最后结合我国研究现状给出技术发展建议.主要内容包括:潮流能的生成、特点及分布,主要介绍潮流的生成、潮流能的特点、潮流能资源及分布等;潮流能开发利用发展现状,主要介绍潮流能开发利用技术研发进程、国外发展现状、国内发展现状等;潮流能开发利用关键技术,主要介绍能量捕获与转换、传动系统与发电机、潮流能发电阵列布置、海上电网构建、支撑结构等;潮流能开发利用技术研究展望,主要介绍国外潮流能技术研究的重点、我国潮流能技术研究的重点等;我国潮流能开发利用的建议;最后是前景展望.%As energy and climate change are currently two of the most important issues in society, many governments in the world are paying more attentions to renewable energy. Tidal current energy is a kind of ocean renewable energy;its resources are rich and its development prospects are very good. Since the 21st century, the development of tidal current energy has made great progress worldwide;a variety of tidal current energy generating devices has been in stage of demonstration project or stage of pre-commercialization. In this aspect, people are faced with the key mechanical problems of how

  10. Tidal flow separation at protruding beach nourishments

    Science.gov (United States)

    Radermacher, Max; de Schipper, Matthieu A.; Swinkels, Cilia; MacMahan, Jamie H.; Reniers, Ad J. H. M.

    2017-01-01

    In recent years, the application of large-scale beach nourishments has been discussed, with the Sand Motor in the Netherlands as the first real-world example. Such protruding beach nourishments have an impact on tidal currents, potentially leading to tidal flow separation and the generation of tidal eddies of length scales larger than the nourishment itself. The present study examines the characteristics of the tidal flow field around protruding beach nourishments under varying nourishment geometry and tidal conditions, based on extensive field observations and numerical flow simulations. Observations of the flow field around the Sand Motor, obtained with a ship-mounted current profiler and a set of fixed current profilers, show that a tidal eddy develops along the northern edge of the mega-nourishment every flood period. The eddy is generated around peak tidal flow and gradually gains size and strength, growing much larger than the cross-shore dimension of the coastline perturbation. Based on a 3 week measurement period, it is shown that the intensity of the eddy modulates with the spring-neap tidal cycle. Depth-averaged tidal currents around coastline perturbations are simulated and compared to the field observations. The occurrence and behavior of tidal eddies is derived for a large set of simulations with varying nourishment size and shape. Results show that several different types of behavior exist, characterized by different combinations of the nourishment aspect ratio, the size of the nourishment relative to the tidal excursion length, and the influence of bed friction.

  11. The distribution and tapping tidal energy

    Directory of Open Access Journals (Sweden)

    Zygmunt Kowalik

    2004-09-01

    Full Text Available Tidal power along tidal shores has been used for centuries to run small tidal mills. Generating electricity by tapping tidal power proved to be very successful only in the last century through the tidal power plant constructed in 1967 in La Rance, France. This used a large barrier to generate the sea level head necessary for driving turbines. Construction of such plants evolved very slowly because of prohibitive costs and concerns about the environmental impact. Developments in the construction of small, efficient and inexpensive underwater turbines admit the possibility of small scale operations that will use local tidal currents to bring electricity to remote locations. Since the generation of such electricity is concerned with the tidal energy in local water bodies, it is important to understand the site-specific energy balance, i.e., the energy flowing in through open boundaries, and the energy generated and dissipated within the local domain. The question is how to tap the tidal energy while keeping possible changes in the present tidal regimes to a minimum. The older approach of constructing barrages may still be quite useful in some locations. The basics of such tidal power plants constructed in a small bay are analyzed in order to understand the principal parameter for tidal plant evaluation, i.e., the power produced.     The new approach is to place turbines - devices similar to windmills - in the pathway of tidal currents. Theoretically, the amount of power available by such turbines for electricity generation is proportional to the water density and velocity cubed of the tidal flow. The naturally dissipated tidal power due to bottom friction forces is also proportional to the cube of the velocity. Because of this similarity, the exploitation of tidal energy can be directed to reinvesting the naturally dissipated power into tidal power for the generation of electricity. This approach to tidal power exploitation is better tuned

  12. The Value of Information and Geospatial Technologies for the analysis of tidal current patterns in the Guanabara Bay (Rio de Janeiro)

    Science.gov (United States)

    Isotta Cristofori, Elena; Demarchi, Alessandro; Facello, Anna; Cámaro, Walther; Hermosilla, Fernando; López, Jaime

    2016-04-01

    The study and validation of tidal current patterns relies on the combination of several data sources such as numerical weather prediction models, hydrodynamic models, weather stations, current drifters and remote sensing observations. The assessment of the accuracy and the reliability of produced patterns and the communication of results, including an easy to understand visualization of data, is crucial for a variety of stakeholders including decision-makers. The large diffusion of geospatial equipment such as GPS, current drifters, aerial photogrammetry, allows to collect data in the field using mobile and portable devices with a relative limited effort in terms of time and economic resources. Theses real-time measurements are essential in order to validate the models and specifically to assess the skill of the model during critical environmental conditions. Moreover, the considerable development in remote sensing technologies, cartographic services and GPS applications have enabled the creation of Geographic Information Systems (GIS) capable to store, analyze, manage and integrate spatial or geographical information with hydro-meteorological data. This valuable contribution of Information and geospatial technologies can benefit manifold decision-makers including high level sport athletes. While the numerical approach, commonly used to validate models with in-situ data, is more familiar for scientific users, high level sport users are not familiar with a numerical representations of data. Therefore the integration of data collected in the field into a GIS allows an immediate visualization of performed analysis into geographic maps. This visualization represents a particularly effective way to communicate current patterns assessment results and uncertainty in information, leading to an increase of confidence level about the forecast. The aim of this paper is to present the methodology set-up in collaboration with the Austrian Sailing Federation, for the study of

  13. Effect of cytosolic pH on inward currents reveals structural characteristics of the proton transport cycle in the influenza A protein M2 in cell-free membrane patches of Xenopus oocytes.

    Directory of Open Access Journals (Sweden)

    Mattia L DiFrancesco

    Full Text Available Transport activity through the mutant D44A of the M2 proton channel from influenza virus A was measured in excised inside-out macro-patches of Xenopus laevis oocytes at cytosolic pH values of 5.5, 7.5 and 8.2. The current-voltage relationships reveal some peculiarities: 1. "Transinhibition", i.e., instead of an increase of unidirectional outward current with increasing cytosolic H(+ concentration, a decrease of unidirectional inward current was found. 2. Strong inward rectification. 3. Exponential rise of current with negative potentials. In order to interpret these findings in molecular terms, different kinetic models have been tested. The transinhibition basically results from a strong binding of H(+ to a site in the pore, presumably His37. This assumption alone already provides inward rectification and exponential rise of the IV curves. However, it results in poor global fits of the IV curves, i.e., good fits were only obtained for cytosolic pH of 8.2, but not for 7.5. Assuming an additional transport step as e.g. caused by a constriction zone at Val27 resulted in a negligible improvement. In contrast, good global fits for cytosolic pH of 7.5 and 8.2 were immediately obtained with a cyclic model. A "recycling step" implies that the protein undergoes conformational changes (assigned to Trp41 and Val27 during transport which have to be reset before the next proton can be transported. The global fit failed at the low currents at pHcyt = 5.5, as expected from the interference of putative transport of other ions besides H(+. Alternatively, a regulatory effect of acidic cytosolic pH may be assumed which strongly modifies the rate constants of the transport cycle.

  14. Individual blade pitching system for horizontal axis tidal current turbine%水平轴潮流能发电机组独立变桨距系统

    Institute of Scientific and Technical Information of China (English)

    徐全坤; 李伟; 刘宏伟; 林勇刚; 石茂顺

    2013-01-01

    针对水平轴潮流能发电机组轮毂空间小、变桨角度大、变桨力矩大等特点,设计一种新型的基于电液比例控制的齿轮齿条传动方案的独立变桨距系统.该系统机械结构紧凑,占用空间小,各个桨叶变桨执行机构相互独立.在分析变桨距载荷的基础上,建立系统的数学模型,并在AMESim软件中对系统进行了仿真研究.仿真结果表明:该系统顺桨变桨180°只需1.1s,逆桨变桨180°只需3.4s,响应速度快,稳定性好,并且可以实现独立变桨,满足了水平轴潮流能发电机组的变桨要求.%Aiming at the characteristics of horizontal axis tidal current turbine such as small hub, large pitching load, large angles of pitch adjustment and so on, a novel pinion-and-rack individual pitch actuator based on electro-hydraulic proportional technology was designed. This pitching system has a compact structure, takes up little space and the mechanism of each blade works independently. Based on the analysis of the load that the blade subjected to during pitch adjustment, a mathematical model for the system was established, and then simulated in AMESim software. The simulation shows that the individual pitching system costs only 1. 1 s when pitching 180° during feathering, and 3. 4 s inverse. The system has good performance in terms of quick response and stability and can realize the pitch adjustment independently, meeting the requirements of tidal current turbine.

  15. The interaction of tidal advection, diffusion and mussel filtration in a tidal channel

    Science.gov (United States)

    Simpson, John H.; Berx, Barbara; Gascoigne, Joanna; Saurel, Camille

    2007-12-01

    Time series measurements of flow and pigment concentrations (Chl) in the Menai Strait have revealed that the strong residual flow in a tidal channel (˜ 500 m 3 s - 1 ) transports phytoplankton from the open sea into the channel where much of it is consumed by suspension feeders, mainly in commercial beds of Mytilus edulis. The progressive depletion of phytoplankton along the channel results in a strong horizontal gradient of plankton and hence Chl. Tidal displacement of this gradient causes large (± 50% of mean) oscillations of Chl in the vicinity of the mussel beds. Vertical mixing by the strong tidal flows is sufficiently vigorous for most of the tidal cycle to ensure that downward diffusion can resupply the near-bed layer although there are indications of some transient depletion around slack water. This paradigm of the interaction of advection, diffusion and filtration determining the distribution of plankton and its supply to mussels has been encapsulated in a series of simple models forced only by boundary values. In the first, a 1-D model of tidal flow in the channel reproduces the principal features of the observed currents including the unusually large spatial change in phase of the currents and the variation of the residual transport with tidal range. The flow field from this physical model is used to drive a second model based on the advection diffusion equation for Chl with a source at the Irish Sea boundary and a sink over the mussel bed. This model illustrates the formation of a strong Chl gradient along the channel and simulates the amplitude and phase of the M 2 oscillations of Chl and the development of the M 4 variation apparent in the observations. This second model has been extended to 2-D over the mussel beds to allow investigation of the effects of water column mixing. The model indicates that only for a short period (˜ 30 min), close to slack water, is mixing sufficiently reduced to permit the development of a depletion boundary layer and

  16. M2M massive wireless access

    DEFF Research Database (Denmark)

    Zanella, Andrea; Zorzi, Michele; Santos, André F.

    2013-01-01

    In order to make the Internet of Things a reality, ubiquitous coverage and low-complexity connectivity are required. Cellular networks are hence the most straightforward and realistic solution to enable a massive deployment of always connected Machines around the globe. Nevertheless, a paradigm...... of the current cellular standards. Here, we provide insights and introduce potential solutions for the cellular radio protocol that will allow the efficient support of Machine-to-Machine (M2M) communications. The paper focuses on the massive aspect of M2M. We will introduce PHY and MAC approaches such as Coded...

  17. Tidal flow characteristics at Kasheli (Kalwa/ Bassein creek), Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Swamy, G.N.; Suryanarayana, A.

    Tidal flow characteristics of waters at Kasheli, connected to the sea through Thane and Bassein Creeks in Bombay, Maharashtra, India are investigated based on tide and current observations carried out in 1980-81. The results establish that the tidal...

  18. Assessment of Soil Quality of Tidal Marshes in Shanghai City

    Institute of Scientific and Technical Information of China (English)

    Qing; WANG; Juan; TAN; Jianqiang; WU; Chenyan; SHA; Junjie; RUAN; Min; WANG; Shenfa; HUANG

    2013-01-01

    We take three types of tidal marshes in Shanghai City as the study object:tidal marshes in mainland,tidal marshes in the rim of islands,and shoal in Yangtze estuary.On the basis of assessing nutrient quality and environmental quality,respectively,we use soil quality index(SQI)to assess the soil quality of tidal flats,meanwhile formulate the quality grading standards,and analyze the current situation and characteristics of it.The results show that except the north of Hangzhou Bay,Nanhui and Jiuduansha with low soil nutrient quality,there are not obvious differences in soil nutrient quality between other regions;the heavy metal pollution of tidal marshes in mainland is more serious than that of tidal marshes in the rim of islands;in terms of the comprehensive soil quality index,the regions are sequenced as follows:Jiuduansha wetland>Chongming Dongtan wetland>Nanhui tidal flat>tidal flat on the periphery of Chongming Island>tidal flat on the periphery of Hengsha Island>Pudong tidal flat>Baoshan tidal flat>tidal flat on the periphery of Changxing Island>tidal flat in the north of Hangzhou Bay.Among them,Jiuduansha wetland and Chongming Dongtan wetland have the best soil quality,belonging to class III,followed by Nanhui tidal flat,tidal flat on the periphery of Chongming Island and tidal flat on the periphery of Hengsha Island,belonging to class IV;tidal flat on the periphery of Changxing Island,Pudong tidal flat,Baoshan tidal flat and tidal flat in the north of Hangzhou Bay belong to class V.

  19. Estimation of annual energy output from BCM tidal barrage and the corresponding marine environmental impact

    Science.gov (United States)

    Yu, Huaming; Wang, Lu; Kuang, Liang; Yu, Haiqing; Sun, Yuchen; Qu, Yuhuan; Wu, Xin

    2016-04-01

    Based on the finite-volume coastal ocean model (FVCOM), a three-dimensional numerical model FVCOM was built to simulate the ocean dynamics in pre-dam and post-dam conditions in Bachimen (BCM). The domain decomposition method, which is effective in describing the conservation of volume and non-conservation of mechanical energy in the utilization of tidal energy, was employed to estimate the theoretical tidal energy resources and developable energy resources, and to analyze the hydrodynamic effect of the tidal power station. This innovative approach has the advantage of linking physical oceanography with engineering problems. The results indicate that the theoretical annual tidal energy resources is about 2×108 kWh under the influence of tidal power station; Optimized power installation is confirmed according to power generation curve from numerical analysis; the developable resources is about 38.2% of theoretical tidal energy resources with the employment of one-way electricity generation. The electricity generation time and power are 3479 hours and 2.55×104 KW, respectively. The power station has no effect on the tide pattern which is semi-diurnal tide in both two conditions, but the amplitudes of main constituents apparently decrease in the area near the dam, with the M2 decreasing the most, about 62.92 cm. The tidal prism shrinks to 2.28×107 m3, but can still meet the flow requirement for tidal power generation. The existence of station increases the flow rate along the waterway and enhances the residual current. There are two opposite vortexes formed on the east side beside the dam of the station, which leads to pollutants gathering.

  20. 漂浮式潮流电站载体船结构强度分析%Strength analysis on floating platform of tidal current power station

    Institute of Scientific and Technical Information of China (English)

    荆丰梅; 何宝; 王洪庆; 张亮

    2013-01-01

    The floating tidal current power station is used to transfer the tidal current energy into power energy. Because of the complexity of its structure and the particularity of the loads, theories and criterions existed can not be used directly to evaluate the overall strength of the power station. Based on the potential theory, software of Hydrostar is used to simulate the wave loads; and hydrodynamics loads of the turbine are calculated using CFX. Turbine loads are equivalented and transformed reasonably. ‘Equivalent rigid shaft’ method is used to apply loads on the structure, and plant carrier (floating platform) strength is calculated by finite element method. The calculation results show that methods adopted in this paper can truly reflect features of stress distribution of the support structure, and strength of the carrier satisfies the working re-quirements of the turbine.%  漂浮式潮流电站是一种海洋潮流能转换系统。考虑载体的稳性,经济性以及其对水轮机水动力性能的影响,文章采用一种新型双体船作为潮流电站的载体。与常规船相比,该双体船结构较复杂,中间开口结构严重不连续;采用井字结构支撑水轮机组;其无航速且必须具有足够的稳性。另外,载体结构承受的载荷特性也较为复杂,除了承受环境载荷外还要承受水轮机组的水动力载荷。因潮流电站双体船载体结构新颖,载荷复杂的特性,很难直接利用规范或者现成的理论评估电站载体结构的整体强度。文中基于三维势流理论计算载体的波浪载荷,利用CFX软件计算水轮机的水动力载荷,采用“等效刚性轴”方法施加载荷;最后利用有限元方法对载体船结构进行计算。计算结果显示:该方法能够真实反映支撑结构的应力分布特点。该文的研究可为潮流能电站载体结构选型,设计提供参考,将对弥补能源短缺,缓解环境污染起到重要作用。

  1. Harnessing Tidal Energy Using Vertical Axis Tidal Turbine

    Directory of Open Access Journals (Sweden)

    Syed Shah Khalid

    2013-01-01

    Full Text Available An overview of the current design practices in the field of Renewable Energy (RE is presented; also paper delineates the background to the development of unique and novel techniques for power generation using the kinetic energy of tidal streams and other marine currents. Also this study focuses only on vertical axis tidal turbine. Tidal stream devices have been developed as an alternative method of extracting the energy from the tides. This form of tidal power technology poses less threat to the environment and does not face the same limiting factors associated with tidal barrage schemes, therefore making it a more feasible method of electricity production. Large companies are taking interest in this new source of power. There is a rush to research and work with this new energy source. Marine scientists are looking into how much these will affect the environment, while engineers are developing turbines that are harmless for the environment. In addition, the progression of technological advancements tracing several decades of R & D efforts on vertical axis turbines is highlighted.

  2. Adelie penguin foraging location predicted by tidal regime switching.

    Directory of Open Access Journals (Sweden)

    Matthew J Oliver

    Full Text Available Penguin foraging and breeding success depend on broad-scale environmental and local-scale hydrographic features of their habitat. We investigated the effect of local tidal currents on a population of Adélie penguins on Humble Is., Antarctica. We used satellite-tagged penguins, an autonomous underwater vehicle, and historical tidal records to model of penguin foraging locations over ten seasons. The bearing of tidal currents did not oscillate daily, but rather between diurnal and semidiurnal tidal regimes. Adélie penguins foraging locations changed in response to tidal regime switching, and not to daily tidal patterns. The hydrography and foraging patterns of Adélie penguins during these switching tidal regimes suggest that they are responding to changing prey availability, as they are concentrated and dispersed in nearby Palmer Deep by variable tidal forcing on weekly timescales, providing a link between local currents and the ecology of this predator.

  3. Numerical Simulation Investigation on Hydraulic Performance of the Horizontal-Axis Tidal Current Turbine%水平轴潮流水轮机水力性能的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    肖惠民

    2015-01-01

    Three-dimensional numerical simulations are carried out to investigate the hydraulic characteristics of the hori -zontal-axis tidal current turbine with speed-up tube .Effects of the dimension parameters of the speed-up tube , such as the length-diameter ratio and the area ratio , on the turbine's performance are also studied .Results show that the horizon-tal-axis tidal current turbine is of high energy utilization rate and great self-starting performance , while it is sensitive to the variation of the tidal current velocity .The speed-up tube can significantly improve the hydraulic performance , espe-cially the output power , of the tidal current turbine .The optimum length-diameter ratio of the speed-up tube is also de-termined .%采用数值模拟方法对一种带增速管的水平轴潮流水轮机的流量特性和转速特性进行了研究,并分析了增速管长径比、面积比对该水轮机水力性能的影响。计算结果表明:该潮流水轮机能量转换效率较高,同时自启动性能好,但对潮流流速变化较敏感;增速管可显著提高水轮机的水力性能,特别是输出功率;对于一定结构形式的潮流水轮机,增速管具有最佳的长径比。

  4. Tidal characteristics in the Wenzhou offshore waters and changes resulting from the Wenzhou Shoal Reclamation Project

    Science.gov (United States)

    Bao, Min; Bao, Xianwen; Yu, Huaming; Ding, Yang

    2015-12-01

    The Wenzhou Shoal Reclamation Project is the core part of Wenzhou Peninsula Engineering which is a big comprehensive development project to expand the city space. The dynamics of the surrounding area was proved to suffer little effect in response to the Lingni north dyke since it was built approximately along the current direction. Therefore, this paper focuses firstly on the tidal characteristics in the Wenzhou and Yueqing bays with the Lingni north dyke being built and then on the changes resulting from the implementation of the on-going Wenzhou Shoal Reclamation Project (WSRP) which will reclaim land from the whole Wenzhou Shoal. To simulate the tidal dynamics, a high-resolution coastal ocean model with unstructured triangular grids was set up for the Wenzhou and Yueqing Bays. The model resolved the complicated tidal dynamics with the simulated tidal elevation and current in good agreement with observations. In the study area, M2 is the predominant tidal component, which means the tide is semidiurnal. The new reclamation project hardly affects the Yueqing Bay and the open ocean, but there are concentrated effects on the mouth of the southern branch of the Oujiang River and the southwest of Wenzhou Shoal. This study provides an indicative reference to the local government and helps to weigh the advantages and disadvantages of the project.

  5. Tidal mixing in Dahej creek waters

    Digital Repository Service at National Institute of Oceanography (India)

    Swamy, G.N.; Sarma, R.V.

    Mixing characteristics of a tidal inlet near Dahej at the mouth of Narmada River, Gujarat, India are examined in terms of tides, currents and bathymetry. The dilution potential of the Dahej Creek waters during a tidal march for a given rate...

  6. DYNAMICAL SIMULATION ON TIDAL CURRENT FIELD IN ANCIENT YELLOW SEA DURING YOUNGER DRYAS EPISODE%新仙女木期古黄海潮流场的数值模拟

    Institute of Scientific and Technical Information of China (English)

    韩喜彬; 史经昊; 李家彪; 李广雪

    2009-01-01

    During Younger Dryas episode (12. 9 ~11. 6 cal. Ka), the sea level oscillated at about - 66 m depth contour in the continental shelf seas in eastern China and the seawater got into the south of the present North Yellow Sea,so Yellow Sea became a long narrow channel gulf. To simulate the tidal current of this special gulf, Environmental Fluid Dynamics Computer Code is used in this paper. The calculation combines curvilinear orthogonal coordinates in the horizontal direction with Sigma mapping coordinates in the vertical direction, and it uses a method which transforms a problem from three-dimension into two-dimension. The results show that the tidal current was still very strong in Yellow Sea during Younger Dryas episode, entering the special gulf along the right side entrance. From both shallow sides to deep centre, rotating flow changes reciprocating flow. Under the effect of reciprocating flow, the floor is eroded and the mud and sand are carried away. Progressive wave turns into rotating wave and two ateliotic amphidromic points appear on the western side of the gulf after tidal wave coming into Yellow Sea. At the same time, tidal residual current flows to southeast and east with relatively great velocity at the west and interior gulf and it becomes weakly near the entrance. The current may carry the bottom sediments and discharge them to the present mud sediment zone in north East China Sea. But at eastern Yellow Sea the tidal residual current flows to north and forms an anticlockwise circulation at centre of the eastern gulf which is corresponding to the eddy mud zone in Southeast Yellow Sea (Heishan mud zone). The anticlockwise circulation captures suspended sediment and may gestate the present mud sediment zone. The extension direction of tidal sand ridges and the size composition of the tidal current sand in eastern South Yellow Sea have a close relationship with the tidal current field of the ancient Yellow Sea, so the less fluctuating sea level changing

  7. 基于最大功率跟踪控制的海流发电能量管理系统%Tidal current power management system with MPPT

    Institute of Scientific and Technical Information of China (English)

    石茂顺; 李伟; 刘宏伟; 林勇刚; 徐全坤

    2013-01-01

    Aim at the problem of the tidal current turbine's low capture inefficiency under lower current velocity,a control method realizing maximum power point tracking of tidal current turbine through adjusting the load characteristics was proposed.The power management system based on double DC/DC convertors was designed.The system could realize the closed loop power control of the tidal current turbine and the charge-discharge control of the batteries.For validating the power manage system,the mathematics model of a small tidal current turbine prototype was analyzed and the matlab/simulink model was built for studying the control characteristics of the power management system.The results show that the double DC/DC convertors topology can realize the maximum power point tracking control of the tidal current turbine under the premise of meeting the charge-discharge control.%针对海流能发电机组在低于额定流速时能量捕获效率低的问题,提出通过负载调节实现离网式海流发电机组最大能量捕获控制的方法.设计三相桥式整流-斩波为主的双直流电压变换器能量管理系统,利用升降压变换器分别实现机组功率的闭环控制和蓄电池的充放电控制.为验证该能量控制系统的有效性,对所设计的小型海流能发电样机进行系统数学模型分析,并建立系统Matlab/Simulink模型进行系统控制特性仿真研究.结果表明,采用双直流电压变换器的拓扑结构在满足蓄电池充放电控制要求的前提下可以实现机组最大功率跟踪控制.

  8. Simulation of the Great Bay Estuarine System: Tides with tidal flats wetting and drying

    Science.gov (United States)

    Ertürk, Ş. N.; Bilgili, A.; Swift, M. R.; Brown, W. S.; Çelikkol, B.; Ip, J. T. C.; Lynch, D. R.

    2002-05-01

    Realistic lunar tides of the Great Bay Estuarine System have been simulated using a fixed boundary finite element numerical model as described by Ip et al. [1998]. It is a two-dimensional, nonlinear, time-stepping model with a groundwater component coupled to a kinematic force balance to facilitate the realistic drainage and filling of elements during ebb and flood, respectively. The numerical model reproduces the observed M2 tides as described by Swift and Brown [1983], and it successfully captures qualitatively correct residual currents and transports, realistic mass-conserving flooding and dewatering of the tidal flats, and current asymmetry between flood and ebb. The simulation results were sensitive to local bathymetry and the implemented friction law. The accuracy of the model is demonstrated by comparison with the 1975 Great Bay study [Swift and Brown, 1983] in terms of tidal elevations at 14 tidal stations and 4 cross-sectionally averaged current measurements in the estuary. Quantitatively, the model results show good agreement with observations, displaying correlation coefficients of >=0.96 in surface elevation and >=0.95 in averaged current, with average RMS errors of 0.12 m and 0.26 m s-1, respectively. In addition, tidal flat hydrodynamics, characteristic distributions of residual current, sediment bed load transport, and influence of topography on the overall circulation in the region are also discussed.

  9. 矩形潮流水轮机水动力性能研究%Research on hydrodynamic performance of rectangle tidal current turbine

    Institute of Scientific and Technical Information of China (English)

    盛其虎; 梁姝婷; 孙科

    2013-01-01

    海洋潮流能发电转换装置对于解决众多岛屿的无电问题,改善海岛居民条件,增强海防建设具有重要意义。设计了一种矩形潮流能水轮机装置,建立了基于动量定理的矩形水轮机单盘面多流管方法,计算不同参数情况下矩形水轮机的水动力特性,分析各参数对水轮机性能的影响。总结了水轮机密实度、安装摆角和速比对水轮机水动力特性的影响规律,并给出了矩形水轮机的优选设计参数的建议范围。研究工作可以为矩形潮流能发电站的工程设计提供参考。%The research on the power-generating switch equipment by utilizing marine tidal current energy has for providing electric energy to many islands, improving the living conditions of isolated islands and enhancing the sea defense. In this paper, the authors designed a kind of rectangular tide current turbine, established the SDMT meth-od specific to the turbine and based on momentum theorem, calculated the hydrodynamic properties of the rectangu-lar turbine under different parameters conditions, analyzed the influence caused by the parameters to the perform-ances of turbine, summarized the law of influence caused by the solidity, installation swing angle and speed ratio to the hydrodynamic properties, gave the suggested scope of the optimized design parameters of rectangular turbine. The research can provide references for the engineering design of rectangular tide energy power station.

  10. Assessment of Soil Quality of Tidal Marshes in Shanghai City

    OpenAIRE

    Wang, Qing; TAN, JUAN; SHA, Chenyan; RUAN, Junjie; Min WANG; HUANG, Shenfa; Wu, Jianqiang

    2013-01-01

    We take three types of tidal marshes in Shanghai City as the study object: tidal marshes in mainland, tidal marshes in the rim of islands, and shoal in Yangtze estuary. On the basis of assessing nutrient quality and environmental quality, respectively, we use soil quality index (SQI) to assess the soil quality of tidal flats, meanwhile formulate the quality grading standards, and analyze the current situation and characteristics of it. The results show that except the north of Hangzhou Bay, N...

  11. TIDAL FEATURES IN THE CHINA SEAS AND THEIR ADJACENT SEA AREAS AS DERIVED FROM TOPEX/POSEIDON ALTIMETER DATA

    Institute of Scientific and Technical Information of China (English)

    胡建宇; HiroshiKAWAMURA; 洪华生; FumiakiKOBASHI; 谢强

    2001-01-01

    Some important tidal features of 8 major tidal constituents (M2, S2, K1, O1, P1,Sa, N2 and K2 ) in the china Seas and their adjacent sea areas were obtained using six years' TOPEX/POSEIDON altimeter data. The results showed that the obtained co-tidal and co-range charts for these major tidal constituents agreed well with those of previous researches using observational data from coastal tidal gauge stations and numerical models.

  12. 海流发电液压传动系统设计及仿真验证%Design of Hydraulic Transmission Systems for Tidal Current Turbines and Its Simulation Validation

    Institute of Scientific and Technical Information of China (English)

    石茂顺; 刘宏伟; 李伟; 林勇刚; 丁金钟; 周宏宾

    2014-01-01

    In light of the problem of speed control for the tidal current turbine,the volume control method is adopted to control the impeller speed and the generator speed of the stand-alone tidal current turbine.Two similar hydraulic transmission systems for the tidal current turbine are designed,both adopting the pump-motor-generator direct connecting structure.To validate the hydraulic transmission systems,the mathematical models for the systems are analyzed and the MATLAB/Simulink models are developed to study the working characteristics of the hydraulic transmission systems.The results show that both hydraulic transmission topologies can realize constant-frequency control of the generator on the premise of meeting the requirement of maximum power point tracking control.%针对海流发电机组转速控制问题,采用容积调速方法控制离网型海流发电液压传动机组的叶轮转速和发电机转速。设计了两种类似的海流发电液压传动系统方案,均采用泵-马达-发电机直接连接的结构形式。为验证所设计的液压传动系统方案的有效性,对其进行数学模型分析,并建立系统的MATLAB/Simulink模型进行系统控制特性仿真研究。结果表明,两种液压传动拓扑结构在满足最大功率跟踪控制要求的前提下,均可以在液压传动系统环节同时实现发电机恒频输出控制。

  13. Tidal flow separation at protruding beach nourishments

    OpenAIRE

    Rademacher, Max; de Schipper, Matthieu A.; Swinkels, Cilia; MacMahan, Jamie H.; Reniers, Ad J.H.M.

    2017-01-01

    The article of record as published may be found at http://dx.doi.org/10.1002/2016JC011942 In recent years, the application of large-scale beach nourishments has been discussed, with the Sand Motor in the Netherlands as the first real-world example. Such protruding beach nourishments have an impact on tidal currents, potentially leading to tidal flow separation and the generation of tidal eddies of length scales larger than the nourishment itself. The present study examines the cha...

  14. Dynamical response to a stationary tidal field

    CERN Document Server

    Landry, Philippe

    2015-01-01

    We demonstrate that a slowly rotating compact body subjected to a stationary tidal field undergoes a dynamical response, in which the fluid variables and the interior metric vary on the time scale of the rotation period. This dynamical response requires the tidal field to have a gravitomagnetic component generated by external mass currents; the response to a gravitoelectric tidal field is stationary. We confirm that in a calculation carried out to first order in the body's rotation, the exterior geometry bears no trace of this internal dynamics; it remains stationary in spite of the time-dependent interior.

  15. Water Level and Current Simulation for LOTS Operations - Persian Gulf and Gulf of Oman

    Science.gov (United States)

    1994-07-01

    equations are solved by a finite element approach. However the equations are reformulated mathematically to a form with much improved numerical solution...longer than the tidal cycle, since tidal ebb and flood currents tend to cancel each other. 23Chqpwr 3 Ceibraga wnd Vedication 30 25 (Z 20 M2 "W 15 0 10Q...circulation in the Arabian Gulf," Applied Mathematical Modeling, 14, 410-419. Bogdanov, K. T. (1987). "T’idal wave propagation and tidal level oscillations

  16. Tidal river dynamics

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Jay, D.A.

    2016-01-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity

  17. Cosmic Tidal Reconstruction

    CERN Document Server

    Zhu, Hong-Ming; Yu, Yu; Er, Xinzhong; Chen, Xuelei

    2015-01-01

    The gravitational coupling of a long wavelength tidal field with small scale density fluctuations leads to anisotropic distortions of the locally measured small scale matter correlation function. Since the local correlation function is statistically isotropic in the absence of such tidal interactions, the tidal distortions can be used to reconstruct the long wavelength tidal field and large scale density field in analogy with the cosmic microwave background lensing reconstruction. In this paper we present in detail a formalism for the cosmic tidal reconstruction and test the reconstruction in numerical simulations. We find that the density field on large scales can be reconstructed with good accuracy and the cross correlation coefficient between the reconstructed density field and the original density field is greater than 0.9 on large scales ($k\\lesssim0.1h/\\mathrm{Mpc}$). This is useful in the 21cm intensity mapping survey, where the long wavelength radial modes are lost due to foreground subtraction proces...

  18. 竖轴水轮机式潮流能发电装置开发现状与发展趋势%Developing Status and Development Trend of Vertical Axis Turbine-type Tidal Current Energy Power Generation Device

    Institute of Scientific and Technical Information of China (English)

    马勇; 张亮; 马良; 陈展

    2012-01-01

    世界能源日趋紧张,而环境污染不断加剧.潮流能作为清洁无污染的绿色可再生新能源,具有储量大、分布广、可预测性强、环境污染小等特点,开发利用潮流能对缓解能源紧张、降低环境污染具有重要的现实意义.潮流能利用的主要形式是利用潮流能发电装置发电,其原理是:潮流冲击水轮机,将潮流水平流动的动能转换为水轮机的机械能,水轮机经机械传动装置,带动发电机发电,将机械能转换为电能.潮流能发电装置根据水轮机结构形式的不同,分为水平轴式、竖轴式和横轴式.与水平轴水轮机式和横轴水轮机式潮流能发电装置相比,竖轴水轮机式潮流能发电装置具有适应流向性强,适合大规模阵列布置等特点,具有独特的应用优势.本文针对竖轴水轮机式潮流能发电装置,阐述发电装置的开发现状,分析不同结构形式发电装置的特点,指出竖轴水轮机式潮流能发电装置的发展趋势和关键技术,为竖轴潮流能发电装置的理论研究与工程应用提供参考和借鉴.%Energy shortage and environment pollutes aggravate ceaselessly all over the world. As a green clean pollution-free renewable energy, tidal current energy has characteristics such as large reserves, wide distribution, predictability, little environmental pollution, etc. Development and utilization of tidal energy has important practical significance to ease the energy shortage and reduce the pollution of the environment. The main form to utilize tidal energy is to generate power, this paper studies the vertical axis turbine-type tidal current energy power generation device, describes the present development situation of the power generation device which could be divided into three kinds, namely the floating structures, the seabed piled structures and the sit seabed structures, analyzes the characteristic of different structural forms of the power generation device, pointed

  19. The Concept Design and Hydrodynamic Performance Analysis of New Tidal Current Power Station Carrier%新式潮流电站载体概念设计及水动力性能分析

    Institute of Scientific and Technical Information of China (English)

    关超; 张亮; 马勇

    2014-01-01

    To achieve the complementary use of tidal current and wind power, a new type of carrier platform is designed. The module of tidal turbine and wind power is successful constructed, and then a“600 kW autocephalous electric system”is built. Based on the new carrier and take the effects of turbine force and environment into consideration, the stability of the system is investigated, and its seakeeping is analyzed by finite element software ANSYS. This work may provide some suggestions for the development and construction of multi-energy complementary power stations.%为了实现潮流能和风能的互补利用,设计一种新式潮流电站载体平台,实现了对潮流水轮机和风能发电模块的搭载,构建了600 kW独立电力系统。基于新式潮流电站载体,考虑水轮机受力和环境的影响,分析发电装置的稳性,并应用有限元软件ANSYS对新式结构建模,分析了装置的耐波性。本研究将为多能互补潮流发电装置研究、开发和建设提供参考和借鉴。

  20. Tidal dynamics of the Terminos Lagoon, Mexico: observations and 3D numerical modelling

    Science.gov (United States)

    Contreras Ruiz Esparza, Adolfo; Douillet, Pascal; Zavala-Hidalgo, Jorge

    2014-09-01

    The tidal circulation patterns in the Terminos Lagoon were studied based on the analysis of 1 year of measurements and numerical simulations using a baroclinic 3D hydrodynamic model, the MARS3D. A gauging network was installed consisting of six self-recording pressure-temperature sensors, a tide gauge station and two current profilers, with pressure and temperature sensors moored in the main lagoon inlets. Model simulations were validated against current and sea level observations and were used to analyse the circulation patterns caused by the tidal forcing. The numerical model was forced with eight harmonic components, four diurnal ( K 1, O 1, P 1, Q 1) and four semi-diurnal ( M 2, S 2, N 2, K 2), extracted from the TPX0.7 database. The tidal patterns in the study area vary from mixed, mainly diurnal in the two main inlets of the lagoon, to diurnal in its interior. The tidal residual circulation inside the lagoon is dominated by a cyclonic gyre. The results indicate a net flux from the southwest Ciudad del Carmen inlet (CdC) towards the northeast Puerto Real inlet (PtR) along the southern side of the lagoon and the opposite in the northern side. The results indicate two areas of strong currents in the vicinity of the inlets and weak currents inside the lagoon. The area of strong currents in the vicinity of the CdC inlet is larger than that observed in the PtR inlet. Nevertheless, the current analysis indicates that the highest current speeds, which can reach a magnitude of 1.9 m s-1, occurred in PtR. A further analysis of the tide distortion in the inlets revealed that both passages are ebb dominated.

  1. Interactions Between Wetlands and Tidal Inlets

    Science.gov (United States)

    2008-08-01

    Madre, TX), (3) fjord-type (e.g., Penobscot Bay , ME), and (4) tectonically created estuaries (e.g., San Francisco Bay , CA) (Pritchard 1967). This CHETN...small marsh island in San Francisco Bay , CA. Wolaver et al. (1988) measured suspended sediment flux of 827 g/m2/year into a marsh in North Inlet, SC...permanent or ephemeral inlets. Conversely, the development or construction of wetlands within an estuary reduces bay area and the tidal prism, which will

  2. Design of hydrodynamic performance experimental system of horizontal axis tidal current energy blade%水平轴潮流能桨叶水动力性能实验系统设计

    Institute of Scientific and Technical Information of China (English)

    林躜; 张利; 张惠娣; 陈俊华

    2016-01-01

    Based on the analysis of the characteristics of the impeller’s design for horizontal axis tidal current energy turbine .a 1 kW hydrodynamic performance test system of horizontal axis tidal current energy blade is achieved .The experimental system consists of the making flow subsystem ,tidal current energy capturing subsystem ,transmission subsystem ,measuring and control subsystem and load resistor .It can simulate maximum 2m/s flow velocity .Many hydrodynamic performance tests are supported in the experimental system such as variable tip speed ratio ,mounting angle and wing profile of turbine blade .Using airMAX wireless technology ,the experimental system is capable of wireless remote control and data acquisition , and accomplishes procedure management to monitor the entire experimental system .Under 1 .5 m/s flow velocity energy capture efficiency of blade was tested ,and it is proved that the experimental system is stable ,reliable and easy to control .The experimental system has laid the foundation for blade performance test and wing profile design .%在分析现有水平轴潮流能发电水轮机设计特点的基础上,设计了1 kw水平轴潮流能捕获桨叶水动力性能实验系统。该实验系统由造流子系统、潮流能捕获子系统、传动子系统、测控子系统和负载组成。该系统可模拟2m/s以下潮流,能实现不同尖速比、桨叶安装角、桨叶翼型等多种水动力性能测试研究。该系统应用了无线airM AX技术,能够无线远程控制和数据采集,实现了整个系统的流程化管理和监控。在1.5 m/s模拟潮流下,利用该系统对桨叶的捕能效率进行测试,测试表明系统运行稳定、工作可靠、控制方便。该实验系统奠定了桨叶翼型设计、验证桨叶性能等方面的基础。

  3. Tidal effects on the shoreface: Towards a conceptual framework

    Science.gov (United States)

    Dashtgard, Shahin E.; MacEachern, James A.; Frey, Shannon E.; Gingras, Murray K.

    2012-11-01

    Tidal processes can have a significant impact on the sedimentological and ichnological character of wave-dominated shoreface deposits. As the influence of tides increases, the resulting shoreface successions begin to depart markedly from those postulated by the conventional, wave-dominated shoreface model, which was built upon essentially non-tidal shoreline settings. In shoreface settings subject to stronger tidal flux, tides can be manifest either directly or indirectly. Direct tidal effects refer to those characteristics imparted by tidal energy (e.g., tidal currents) per se, and are best expressed in offshore and lower shoreface positions. Key evidence of direct tidal control includes uniform sediment calibres from the upper shoreface to the offshore, and little or no mud preserved in the lower shoreface. Additionally, sands in the lower shoreface and offshore tend to be intensely bioturbated. Where primary stratification is preserved, it largely comprises current-generated structures. Such shoreface deposits are referred to herein as "tide-influenced shorefaces", and are expected in settings with low storm-wave input coupled with strong tidal currents (e.g., straits). Indirect tidal influences are manifest by the lateral translation of wave zones across the shoreface profile owing to changes in water depth during the tidal cycle. This is best developed in macrotidal to megatidal settings. Indirect tidal influences are more pronounced in the upper and lower shoreface, and are recorded through the interbedding of sedimentary structures produced by shoaling waves, breakers and surf, swash-backwash, and surface runoff. The boundaries between shoreface subenvironments are correspondingly poorly defined. The foreshore in settings of elevated tidal range is also generally much thicker (typically 4 to 5 m). Bioturbation tends to be patchy in distribution across the shoreface, and dominated by vertical structures. Such systems are defined as "tidally modulated

  4. Organic geochemistry in Pennsylvanian tidally influenced sediments from SW Indiana

    Energy Technology Data Exchange (ETDEWEB)

    Mastalerz, M.; Kvale, E.P.; Stankiewicz, B.A.; Portle, K. [Indiana University, Bloomington, IN (United States). Indiana Geological Survey

    1999-05-01

    Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana were analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter preserved in an environment of daily interactions between marine and fresh waters.

  5. The effects of tidal range on saltmarsh morphology

    Science.gov (United States)

    Goodwin, Guillaume; Mudd, Simon

    2017-04-01

    Saltmarshes are highly productive coastal ecosystems that act simultaneously as flood barriers, carbon storage, pollutant filters and nurseries. As halophytic plants trap suspended sediment and decay in the settled strata, innervated platforms emerge from the neighbouring tidal flats, forming sub-vertical scarps on their eroding borders and sub-horizontal pioneer zones in areas of seasonal expansion. These evolutions are subject to two contrasting influences: stochastically generated waves erode scarps and scour tidal flats, whereas tidally-generated currents transport sediment to and from the marsh through the channel network. Hence, the relative power of waves and tidal currents strongly influences saltmarsh evolution, and regional variations in tidal range yield marshes of differing morphologies. We analyse several sheltered saltmarshes to determine how their morphology reflects variations in tidal forcing. Using tidal, topographic and spectral data, we implement an algorithm based on the open-source software LSDTopoTools to automatically identify features such as marsh platforms, tidal flats, erosion scarps, pioneer zones and tidal channels on local Digital Elevation Models. Normalised geometric properties are then computed and compared throughout the spectrum of tidal range, highlighting a notable effect on channel networks, platform geometry and wave exposure. We observe that micro-tidal marshes typically display jagged outlines and multiple islands along with wide, shallow channels. As tidal range increases, we note the progressive disappearance of marsh islands and linearization of scarps, both indicative of higher hydrodynamic stress, along with a structuration of channel networks and the increase of levee volume, suggesting higher sediment input on the platform. Future research will lead to observing and modelling the evolution of saltmarshes under various tidal forcing in order to assess their resilience to environmental change.

  6. Site Characterization at a Tidal Energy Site in the East River, NY (usa)

    Science.gov (United States)

    Gunawan, B.; Neary, V. S.; Colby, J.

    2012-12-01

    A comprehensive tidal energy site characterization is performed using ADV measurements of instantaneous horizontal current magnitude and direction at the planned hub centerline of a tidal turbine over a two month period, and contributes to the growing data base of tidal energy site hydrodynamic conditions. The temporal variation, mean current statistics, and turbulence of the key tidal hydrodynamic parameters are examined in detail, and compared to estimates from two tidal energy sites in Puget Sound. Tidal hydrodynamic conditions, including mean annual current (at hub height), the speed of extreme gusts (instantaneous horizontal currents acting normal to the rotor plane), and turbulence intensity (as proposed here, relative to a mean current of 2 m s-1) can vary greatly among tidal energy sites. Comparison of hydrodynamic conditions measured in the East River tidal straight in New York City with those reported for two tidal energy sites in Puget Sound indicate differences of mean annual current speeds, difference in the instantaneous current speeds of extreme gusts, and differences in turbulence intensities. Significant differences in these parameters among the tidal energy sites, and with the tidal resource assessment map, highlight the importance of conducting site resource characterization with ADV measurements at the machine scale. As with the wind industry, which adopted an International Electrotechnical Commission (IEC) wind class standard to aid in the selection of wind turbines for a particular site, it is recommended that the tidal energy industry adopt an appropriate standard for tidal current classes. Such a standard requires a comprehensive field campaign at multiple tidal energy sites that can identify the key hydrodynamic parameters for tidal current site classification, select a list of tidal energy sites that exhibit the range of hydrodynamic conditions that will be encountered, and adopt consistent measurement practices (standards) for site

  7. Tidal alignment of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Blazek, Jonathan; Vlah, Zvonimir; Seljak, Uroš

    2015-08-01

    We develop an analytic model for galaxy intrinsic alignments (IA) based on the theory of tidal alignment. We calculate all relevant nonlinear corrections at one-loop order, including effects from nonlinear density evolution, galaxy biasing, and source density weighting. Contributions from density weighting are found to be particularly important and lead to bias dependence of the IA amplitude, even on large scales. This effect may be responsible for much of the luminosity dependence in IA observations. The increase in IA amplitude for more highly biased galaxies reflects their locations in regions with large tidal fields. We also consider the impact of smoothing the tidal field on halo scales. We compare the performance of this consistent nonlinear model in describing the observed alignment of luminous red galaxies with the linear model as well as the frequently used "nonlinear alignment model," finding a significant improvement on small and intermediate scales. We also show that the cross-correlation between density and IA (the "GI" term) can be effectively separated into source alignment and source clustering, and we accurately model the observed alignment down to the one-halo regime using the tidal field from the fully nonlinear halo-matter cross correlation. Inside the one-halo regime, the average alignment of galaxies with density tracers no longer follows the tidal alignment prediction, likely reflecting nonlinear processes that must be considered when modeling IA on these scales. Finally, we discuss tidal alignment in the context of cosmic shear measurements.

  8. Hofbauer cells of M2a, M2b and M2c polarization may regulate feto-placental angiogenesis.

    Science.gov (United States)

    Loegl, J; Hiden, U; Nussbaumer, E; Schliefsteiner, C; Cvitic, S; Lang, I; Wadsack, C; Huppertz, B; Desoye, G

    2016-11-01

    The human placenta comprises a special type of tissue macrophages, the Hofbauer cells (HBC), which exhibit M2 macrophage phenotype. Several subtypes of M2-polarized macrophages (M2a, M2b and M2c) exist in almost all tissues. Macrophage polarization depends on the way of macrophage activation and leads to the expression of specific cell surface markers and the acquisition of specific functions, including tissue remodeling and the promotion of angiogenesis. The placenta is a highly vascularized and rapidly growing organ, suggesting a role of HBC in feto-placental angiogenesis. We here aimed to characterize the specific polarization and phenotype of HBC and investigated the role of HBC in feto-placental angiogenesis. Therefore, HBC were isolated from third trimester placentas and their phenotype was determined by the presence of cell surface markers (FACS analysis) and secretion of cytokines (ELISA). HBC conditioned medium (CM) was analyzed for pro-angiogenic factors, and the effect of HBC CM on angiogenesis, proliferation and chemoattraction of isolated primary feto-placental endothelial cells (fpEC) was determined in vitro Our results revealed that isolated HBC possess an M2 polarization, with M2a, M2b and M2c characteristics. HBC secreted the pro-angiogenic molecules VEGF and FGF2. Furthermore, HBC CM stimulated the in vitro angiogenesis of fpEC. However, compared with control medium, chemoattraction of fpEC toward HBC CM was reduced. Proliferation of fpEC was not affected by HBC CM. These findings demonstrate a paracrine regulation of feto-placental angiogenesis by HBC in vitro Based on our collective results, we propose that the changes in HBC number or phenotype may affect feto-placental angiogenesis. © 2016 Society for Reproduction and Fertility.

  9. Assigning error to an M2 measurement

    Science.gov (United States)

    Ross, T. Sean

    2006-02-01

    The ISO 11146:1999 standard has been published for 6 years and set forth the proper way to measure the M2 parameter. In spite of the strong experimental guidance given by this standard and the many commercial devices based upon ISO 11146, it is still the custom to quote M2 measurements without any reference to significant figures or error estimation. To the author's knowledge, no commercial M2 measurement device includes error estimation. There exists, perhaps, a false belief that M2 numbers are high precision and of insignificant error. This paradigm causes program managers and purchasers to over-specify a beam quality parameter and researchers not to question the accuracy and precision of their M2 measurements. This paper will examine the experimental sources of error in an M2 measurement including discretization error, CCD noise, discrete filter sets, noise equivalent aperture estimation, laser fluctuation and curve fitting error. These sources of error will be explained in their experimental context and convenient formula given to properly estimate error in a given M2 measurement. This work is the result of the author's inability to find error estimation and disclosure of methods in commercial beam quality measurement devices and building an ISO 11146 compliant, computer- automated M2 measurement device and the resulting lessons learned and concepts developed.

  10. Tidal propagation and dissipation in the Taiwan Strait

    Science.gov (United States)

    Yu, Haiqing; Yu, Huaming; Wang, Lu; Kuang, Liang; Wang, Hui; Ding, Yang; Ito, Shin-ichi; Lawen, Johannes

    2017-03-01

    Previous research on tides and tidal dynamics in the Taiwan Strait (TS) is reviewed in this paper. Tidal dynamics, which is the basic and dominant hydrodynamics in this area, attracts much interest in the last 30 years and till now its physical mechanism is still in debate. In this study, the major research methods and findings of previous works on barotropic tides in the TS are summarized. Based on Finite Volume Coastal Ocean Model (FVCOM), the main tidal constituents (M2, S2, K1, O1) are well simulated with the mean root-mean-square (RMS) errors of 4.7, 2.0, 1.3 and 0.7 cm between the observed and simulated tidal constants, respectively. It has been proved that semi-diurnal tidal movement is mainly determined by the waves from the East China Sea (ECS), while waves from the ECS and the Luzon Strait (LS) play comparable roles in diurnal tidal movement in the TS by linear superposition and the interaction of these two waves is the main cause for the progressive diurnal tidal waves in the TS. Furthermore, energy analysis revealed that the M2 tidal wave system in the TS and its adjacent area south to the shoal is an standing wave system and the anti-node appears in the central TS while the wave node locates in the shoal area, which can be contributed to the interaction of the incident waves from the ECS and the topography step south to Taiwan island, while the shoal also has an impact on the whole semi-diurnal tidal wave system in the TS. This standing wave system is consistent with the little energy dissipation in the central TS and much energy dissipation in the southern TS, where the shallow water effect also contributes to the local dissipation to some extent.

  11. Adélie penguin foraging location predicted by tidal regime switching.

    Science.gov (United States)

    Oliver, Matthew J; Irwin, Andrew; Moline, Mark A; Fraser, William; Patterson, Donna; Schofield, Oscar; Kohut, Josh

    2013-01-01

    Penguin foraging and breeding success depend on broad-scale environmental and local-scale hydrographic features of their habitat. We investigated the effect of local tidal currents on a population of Adélie penguins on Humble Is., Antarctica. We used satellite-tagged penguins, an autonomous underwater vehicle, and historical tidal records to model of penguin foraging locations over ten seasons. The bearing of tidal currents did not oscillate daily, but rather between diurnal and semidiurnal tidal regimes. Adélie penguins foraging locations changed in response to tidal regime switching, and not to daily tidal patterns. The hydrography and foraging patterns of Adélie penguins during these switching tidal regimes suggest that they are responding to changing prey availability, as they are concentrated and dispersed in nearby Palmer Deep by variable tidal forcing on weekly timescales, providing a link between local currents and the ecology of this predator.

  12. 基于ECOMSED模型的湛江湾水道三维潮流数值模拟%Three dimensional numerical imitation of tidal current in the Zhanjiang Bay channel based on ECOMSED model

    Institute of Scientific and Technical Information of China (English)

    赵婉璐; 郝瑞霞

    2015-01-01

    This study used half implicit three-dimensional ocean turbulence model ECOMSED(Estuarine, Coastal and Ocean Modeling System with Sediments) to build 3D tidal current numerical model of the Zhanjiang Bay upstream channel. The model uses refined orthogonal grid to joint the shoreline boundary in horizontal direction, and uses sigma coordinates to better fit bottom topography in the vertical direction. Through verification, it is shown that the simulation results are in good agreement with the measured data, suggesting that this model can well forecast the dynamic charac-teristics of Zhanjiang Bay's tidal, which provides a technical support for further study of the offshore estuary water temperature change, saltwater intrusion and sediment transport.%采用半隐式的ECOMSED(Estuarine, Coastal and Ocean Modeling System with Sediments)三维海洋紊流模式, 建立湛江湾湾顶水道的三维潮流数值模型.模型的水平方向采用加密的正交网格以贴合岸线边界, 垂向上采用σ坐标以更好地拟合海底地形.通过验证, 模拟结果与实测数据符合良好, 表明运用该模型可以较好地预报湛江湾的潮流动力特性.为进一步研究湛江湾水道附近水域的温盐变化、泥沙输运提供技术支持.

  13. Tachyonic Anti-M2 Branes

    CERN Document Server

    Bena, Iosif; Kuperstein, Stanislav; Massai, Stefano

    2014-01-01

    We study the dynamics of anti-M2 branes in a warped Stenzel solution with M2 charges dissolved in fluxes by taking into account their full backreaction on the geometry. The resulting supergravity solution has a singular magnetic four-form flux in the near-brane region. We examine the possible resolution of this singularity via the polarization of anti-M2 branes into M5 branes, and compute the corresponding polarization potential for branes smeared on the finite-size four-sphere at the tip of the Stenzel space. We find that the potential has no minimum. We then use the potential for smeared branes to compute the one corresponding to a stack of localized anti-M2 branes, and use this potential to compute the force between two anti-M2 branes at tip of the Stenzel space. We find that this force, which is zero in the probe approximation, is in fact repulsive. This surprising result points to a tachyonic instability of anti-M2 branes in backgrounds with M2 brane charge dissolved in flux.

  14. 被动式摆动水翼潮流能量获取技术实验研究%Experimental studies of passive oscillating hydrofoil for tidal current energy extracting

    Institute of Scientific and Technical Information of China (English)

    徐建安; 孙洪雨

    2016-01-01

    Regarding to the issue existing in the acquisition process of tidal energy by conventional rotary vane water turbine, this paper proposes a kind of passive oscillating hydrofoil tidal energy extracting technology that imitates the tail swinging of aquatic organisms. On the basis of analyzing the relationship of the motion rules of hydrofoil and the parameters including power coefficient, efficiency and reduced frequency, this paper designs a test device for the passive oscillating hydrofoil tidal energy extracting. Under the action of three sets of forward and reverse crank and rocker mechanisms, the passive oscillating hydrofoil has realized the cyclic process with two degrees of freedom. The flywheel is used to overcome the dead point in the process of crank and rocker mechanisms movement. The torque sensor is used to extract the rotating speed signal and torque single of output shaft torque. The energy extrac⁃ting experiment of passive oscillating hydrofoil was carried out in the circulating water channel. Experiment results show that the passive oscillating hydrofoil can be used to extract tidal current energy. When the reduced frequency reaches 0.09, the highest energy extracting efficiency can achieve 0.18.%针对传统的旋转叶片式水轮机在潮流能量获取过程中存在的问题,提出一种模仿水中生物尾部摆动的被动式摆动水翼潮流能量获取技术。在分析水翼的运动规律和功率系数、效率、折算频率等各参数之间关系的基础上,设计了被动式摆动水翼潮流能量获取实验装置;在三套正反向曲柄摇杆机构的作用下,被动式摆动水翼实现了两自由度周期循环,利用飞轮克服曲柄摇杆机构运动中存在的死点问题,利用扭矩传感器实现了输出轴的转速信号和转矩信号提取;循环水槽环境下完成了被动式摆动水翼能量获取实验,实验结果表明利用被动式摆动水翼能够进行潮流能量获取,当

  15. Research and Application of Two Different Anti-corrosion coating Systems on Tidal current Generator%两种防腐蚀涂层体系在潮流发电机组上的应用研究

    Institute of Scientific and Technical Information of China (English)

    李景; 贾朋刚; 过洁; 王辉亭

    2013-01-01

    Marine current is an important offshore source of renewable energy. Marine current turbine generator is one kind of facility which converts marine current energy into electric energy. Generally, marine current turbine generator works in offshore field with high speed of marine current, which always encounters challenges of serious corrosion and biofouling in marine environment. In this paper, two different kinds of coating systems have been tested and utilized to paint the main parts of tidal current generator. The results tested in laboratory and in sea indicate that these two coating systems show good anti-corrosive property.%  潮流能是一种重要的海洋可再生能源。潮流能发电机组是一种将潮流能转化为电能的装置。潮流能发电机组一般运行在海流流速较大的近海海域,面临着海水腐蚀,微生物附着等因素的严重影响。本文分析了两种防腐蚀涂层体系的各项性能参数,在潮流能发电机的各主要部件外表面进行了涂装,并且进行了海试。实验室检验结果和海试结果表明,两种涂层均表现出良好的耐腐蚀效果。

  16. A stand-alone tidal prediction application for mobile devices

    Science.gov (United States)

    Tsai, Cheng-Han; Fan, Ren-Ye; Yang, Yi-Chung

    2017-04-01

    It is essential for people conducting fishing, leisure, or research activities at the coasts to have timely and handy tidal information. Although tidal information can be found easily on the internet or using mobile device applications, this information is all applicable for only certain specific locations, not anywhere on the coast, and they need an internet connection. We have developed an application for Android devices, which allows the user to obtain hourly tidal height anywhere on the coast for the next 24 hours without having to have any internet connection. All the necessary information needed for the tidal height calculation is stored in the application. To develop this application, we first simulate tides in the Taiwan Sea using the hydrodynamic model (MIKE21 HD) developed by the DHI. The simulation domain covers the whole coast of Taiwan and the surrounding seas with a grid size of 1 km by 1 km. This grid size allows us to calculate tides with high spatial resolution. The boundary conditions for the simulation domain were obtained from the Tidal Model Driver of the Oregon State University, using its tidal constants of eight constituents: M2, S2, N2, K2, K1, O1, P1, and Q1. The simulation calculates tides for 183 days so that the tidal constants for the above eight constituents of each water grid can be extracted by harmonic analysis. Using the calculated tidal constants, we can predict the tides in each grid of our simulation domain, which is useful when one needs the tidal information for any location in the Taiwan Sea. However, for the mobile application, we only store the eight tidal constants for the water grids on the coast. Once the user activates the application, it reads the longitude and latitude from the GPS sensor in the mobile device and finds the nearest coastal grid which has our tidal constants. Then, the application calculates tidal height variation based on the harmonic analysis. The application also allows the user to input location and

  17. Introduction to Tidal Streams

    Science.gov (United States)

    Newberg, Heidi Jo

    Dwarf galaxies that come too close to larger galaxies suffer tidal disruption; the differential gravitational force between one side of the galaxy and the other serves to rip the stars from the dwarf galaxy so that they instead orbit the larger galaxy. This process produces "tidal streams" of stars, which can be found in the stellar halo of the Milky Way, as well as in halos of other galaxies. This chapter provides a general introduction to tidal streams, including the mechanism through which the streams are created, the history of how they were discovered, and the observational techniques by which they can be detected. In addition, their use in unraveling galaxy formation histories and the distribution of dark matter in galaxies is discussed, as is the interaction between these dwarf galaxy satellites and the disk of the larger galaxy.

  18. Estimates of the global tidal range energy resource

    Science.gov (United States)

    Robins, Peter; Walkington, Ian

    2017-04-01

    Renewable energy generation through tidal lagoons and barrages is an attractive energy source due to tidal predictability and the potential for energy storage. Yet so far, the annual tidal range resource has only been estimated at relatively coarse spatial resolutions and without detailed investigation of the temporal variation from individual or aggregated sites. In this study, we estimate the theoretical tidal range resource of the northwest European shelf seas, using the 3D Regional Ocean Modelling System (ROMS) at roughly 1 km spatial resolution. Through tidal analysis of model output, we calculate the potential energy in both the rising and falling tides and, hence, show temporal variations in PE throughout the year. Based on a range of energy yield thresholds (rather than thresholds based on M2 range and water depth), we calculate the total annual theoretical resource from dual (flood and ebb) strategies. Using the FES global tidal model, which resolves tidal elevations at 1/16° resolution, the global resource was also estimated with the regions with the highest energy yield isolated. We discuss our estimates in relation to the yield that can actually be obtained mechanically, and in relation to the total energy flux of a region and the potential impacts of different lagoon scenarios on the local and far-field energy fluxes.

  19. Analysis of Tidal Data for Dagang Tidal Gauge and Study of the Changes for the National Height Datum

    Directory of Open Access Journals (Sweden)

    WU Fumei

    2015-07-01

    Full Text Available The main tides affecting Dagang sea level are analyzed and the national height datum is studied by analyzing 1980—2011 hourly tidal data and 1952—2007 monthly mean tidal data. Firstly, the frequencies and amplitudes of main tides including 180 short-period tides and 6 long-period tides are gained by the Fouirer transform. Then the actual amplitudes and their variations of main tides are obtained by the harmonic analysis of the 1980—2011 hourly tidal data, and the changes with about 19 year period can easily be found in the amplitudes of Q1、O1、M2、K1、K2. And then the changes of the mean sea level at Dagang tidal gauge defining national height datum during the period of 1952—2011 are studied by the harmonic analysis and the shifting average of 18.61 year tidal heights. The results of these methods show that the mean sea level at Dagang tidal gauge descended with the speed of 1.07 mm/a and 0.76 mm/a respectively during 1952—1980, and that it ascended with the speed of 1.59 mm/a and 1.62 mm/a respectively during 1980—2011. And finally the difference of 0.14 cm is achieved by the shifting average of 18.61 year tidal heights for 1985 National Height Datum.

  20. Ocean tidal signals in observatory and satellite magnetic measurements

    DEFF Research Database (Denmark)

    Maus, S.; Kuvshinov, A.

    2004-01-01

    , and P1 periods turn out to be dominated by unrelated external fields. In contrast, observed lunar M2 and N2 tidal signals are in fair agreement with predictions from motional induction. The lunar diurnal O1 signal, visible at some observatories, could be caused by ocean flow but disagrees in amplitude...

  1. STUDY ON BLADE PITCHING SYSTEM FOR HORIZONTAL AXIS TIDAL CURRENT TURBINE%水平轴潮流能发电机组变桨距系统研究

    Institute of Scientific and Technical Information of China (English)

    马舜; 李伟; 刘宏伟; 林勇刚

    2011-01-01

    针对水平轴潮流能发电机组的变桨距系统进行研究.利用理论力学及叶素动量理论对桨叶在机组工作时的受力进行详细分析,提出变桨载荷的理论计算方法.根据潮流能机组轮毂体积小、变桨载荷及凋桨范围大等特点,设计了一种新型的基于电液比例技术的齿轮齿条式变桨距执行机构.该机构结构紧凑、油路新颖、驱动力矩及调桨角度大.在建立系统数学模型的基础上,通过数字仿真对系统的控制特性进行研究.仿真结果表明采用PID控制算法的变桨距系统具有较好的动态特性,能够满足机组功率控制的需求.%A novel blade pitching system for horizontal axis tidal current turbine was presented. The force that the blades were subject to when the turbine worked was analyzed in detail using theoretical mechanics and blade element momentum theory. A theoretical pitching load calculation method was proposed. According to tidal current turbine's characteristics including small hub, large pitching load, and large range of pitch adjustment, a novel pin-ion-and-rack variable pitch actuating mechanism based on electrohydraulic proportional technique was designed. This mechanism has a compact structure, an original oil passage, large driving torque, and large range of pitch adjustment. The system' s control performance was studied through simulation after the mathematic model was built. The simulation results showed that the blade pitching system with a PID control algorithm has good dynamic characteristics , and with the designed pitching system the turbine' s power control can be performed.

  2. Los Angeles and Long Beach Harbors Model Study. Report 5. Tidal Verification and Base Circulation Tests. Appendix B: Surface-Current Pattern Mosaics

    Science.gov (United States)

    1975-09-01

    BEACH HARBORS SURFACE CURRENT PATTERNS BASEz TEST SPRING TIDE HOUR 4 PLATE 85 4’. ’I / ’,~4 $ N 4 A".1 1 A. 9 . wit , - -- p cCCALES -IN FEET VELOCITYSCALE...PATTERNS rn A e- r- r -e-- SPRING TIDE HOUR 16 PLATE B17 ? ~ \\ ~ ii -- I-’ ~v ’I #~k 4 1< ’~ £ ~ I-. * 9 *1 4 440 A 4.00P cSCLE ;N EE if - - ~ *1 V 5- 5

  3. Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

    CERN Document Server

    Barnes, Rory; Goldblatt, Colin; Meadows, Victoria S; Kasting, James F; Heller, Rene

    2012-01-01

    Traditionally stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at high enough levels to induce a runaway greenhouse for a long enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets "Tidal Venuses," and the phenomenon a "tidal greenhouse." Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits in the habitable zone (HZ). However, these planets are not habitable as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulate the evolution of hypothetical planetary systems in a quasi-continuous ...

  4. Tidal Heating in a Magma Ocean within Jupiter's Moon Io

    Science.gov (United States)

    Tyler, Robert H.; Henning, Wade G.; Hamilton, Christopher W.

    2015-06-01

    Active volcanism observed on Io is thought to be driven by the temporally periodic, spatially differential projection of Jupiter's gravitational field over the moon. Previous theoretical estimates of the tidal heat have all treated Io as essentially a solid, with fluids addressed only through adjustment of rheological parameters rather than through appropriate extension of the dynamics. These previous estimates of the tidal response and associated heat generation on Io are therefore incomplete and possibly erroneous because dynamical aspects of the fluid behavior are not permitted in the modeling approach. Here we address this by modeling the partial-melt asthenosphere as a global layer of fluid governed by the Laplace Tidal Equations. Solutions for the tidal response are then compared with solutions obtained following the traditional solid-material approach. It is found that the tidal heat in the solid can match that of the average observed heat flux (nominally 2.25 W m-2), though only over a very restricted range of plausible parameters, and that the distribution of the solid tidal heat flux cannot readily explain a longitudinal shift in the observed (inferred) low-latitude heat fluxes. The tidal heat in the fluid reaches that observed over a wider range of plausible parameters, and can also readily provide the longitudinal offset. Finally, expected feedbacks and coupling between the solid/fluid tides are discussed. Most broadly, the results suggest that both solid and fluid tidal-response estimates must be considered in exoplanet studies, particularly where orbital migration under tidal dissipation is addressed.

  5. Anti-influenza M2e antibody

    Science.gov (United States)

    Bradbury, Andrew M.

    2011-12-20

    Humanized recombinant and monoclonal antibodies specific for the ectodomain of the influenza virus M2 ion channel protein are disclosed. The antibodies of the invention have anti-viral activity and may be useful as anti-viral therapeutics and/or prophylactic/vaccine agents for inhibiting influenza virus replication and for treating individuals infected with influenza.

  6. Anti-influenza M2e antibody

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, Andrew M.

    2013-04-16

    Humanized recombinant and monoclonal antibodies specific for the ectodomain of the influenza virus M2 ion channel protein are disclosed. The antibodies of the invention have anti-viral activity and may be useful as anti-viral therapeutics and/or prophylactic/vaccine agents for inhibiting influenza virus replication and for treating individuals infected with influenza.

  7. Anti-influenza M2e antibody

    Science.gov (United States)

    Bradbury, Andrew M.

    2013-04-16

    Humanized recombinant and monoclonal antibodies specific for the ectodomain of the influenza virus M2 ion channel protein are disclosed. The antibodies of the invention have anti-viral activity and may be useful as anti-viral therapeutics and/or prophylactic/vaccine agents for inhibiting influenza virus replication and for treating individuals infected with influenza.

  8. 竖轴潮流能水轮机水动力性能水池试验分析%Analysis of Hydrodynamic Performance of Vertical-Axis Tidal-Current Turbine with Experiment in Towing Tank

    Institute of Scientific and Technical Information of China (English)

    李广年; 吴卫国; 谢永和; 劳展杰; 张波

    2014-01-01

    Based on model experiments in the towing tank in Zhejiang Ocean University, hydrodynamic performance of vertical-axis tidal-current turbine is investigated. Energy efficiency index of the turbine is discussed under different conditions of rotating speeds and flow velocities. Influence of tip-speed ratio, preset angle of airfoil attack and solidity of turbine on the energy efficiency index is analyzed. Effect of waves on the energy efficiency index is investigated. Experimental results may provide technical support for relevant researches.%针对竖轴潮流能水轮机的水动力性能,在拖曳水池中开展模型试验研究。在若干给定的转速和流速情况下考察水轮机能效指数。改变水轮机模型的结构形式及其工作环境,分析尖速比、叶片偏角以及密实度对能效指数的影响。研究竖轴潮流能水轮机在波流耦合作用下的水动力响应,分析波浪对水轮机能效指数的影响。期望试验结果可为相关研究人员提供技术支持。

  9. University of Washington/ Northwest National Marine Renewable Energy Center Tidal Current Technology Test Protocol, Instrumentation, Design Code, and Oceanographic Modeling Collaboration: Cooperative Research and Development Final Report, CRADA Number CRD-11-452

    Energy Technology Data Exchange (ETDEWEB)

    Driscoll, Frederick R. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-11-01

    The University of Washington (UW) - Northwest National Marine Renewable Energy Center (UW-NNMREC) and the National Renewable Energy Laboratory (NREL) will collaborate to advance research and development (R&D) of Marine Hydrokinetic (MHK) renewable energy technology, specifically renewable energy captured from ocean tidal currents. UW-NNMREC is endeavoring to establish infrastructure, capabilities and tools to support in-water testing of marine energy technology. NREL is leveraging its experience and capabilities in field testing of wind systems to develop protocols and instrumentation to advance field testing of MHK systems. Under this work, UW-NNMREC and NREL will work together to develop a common instrumentation system and testing methodologies, standards and protocols. UW-NNMREC is also establishing simulation capabilities for MHK turbine and turbine arrays. NREL has extensive experience in wind turbine array modeling and is developing several computer based numerical simulation capabilities for MHK systems. Under this CRADA, UW-NNMREC and NREL will work together to augment single device and array modeling codes. As part of this effort UW NNMREC will also work with NREL to run simulations on NREL's high performance computer system.

  10. Interaction between the tidal and seasonal variability of the Gulf of Maine and Scotian Shelf region

    Science.gov (United States)

    Katavouta, Anna; Thompson, Keith; Lu, Youyu; Loder, John

    2017-04-01

    In the Gulf of Maine and Scotian Shelf (off the northeastern coast of North America) tides are large and can alter the local hydrographic properties, circulation, and sea surface height through processes such as tidal rectification, mixing, and horizontal advection. Furthermore, the stratification of the water column can influence tidal elevation and currents over the shelves (e.g., baroclinic tides). To investigate this interaction, a newly developed high resolution (1/36 degree) regional circulation model is used (GoMSS model). First, numerical experiments with and without density stratification are used to demonstrate the influence of stratification on the tides. GoMSS model is then used to interpret the physical mechanisms responsible for the largest seasonal variations in the M2 surface current which occur over, and to the north of, Georges Bank. An alternating pattern of highs and lows in the summer maximum M2 surface speed in the Gulf of Maine is identified, for the first time, in both the model output and observations by a high frequency coastal radar system. This pattern consists of extended striations in tidal speed aligned with the northern flank of Georges Bank that separates the Gulf of Maine from the North Atlantic. The striations are explained in terms of a linear superposition of the barotropic tide flowing across the northern flank of Georges Bank and the reflected, phase-locked baroclinic tide. The striations have amplitudes of about 0.1 m/s and longitudinal length scales of order 100 km, and are thus of practical significance.

  11. M$^2$I Communication: From Theoretical Modeling to Practical Design

    CERN Document Server

    Guo, Hongzhi

    2015-01-01

    Wireless communications in complex environments are constrained by lossy media and complicated structures. Magnetic Induction (MI) has been proved to be an efficient solution to extend the communication range. Due to the small coil antenna's physical limitation, however, MI's communication range is still very limited. To this end, Metamaterial-enhanced Magnetic Induction (M$^2$I) communication has been proposed and the theoretical results suggest that it can significantly increase the communication performance, namely, data rate and communication range. Nevertheless, currently, the real implementation of M$^2$I is still a challenge and there is no guideline on design and fabrication of spherical metamaterial. In this paper, we propose a practical design by using a spherical coil array to realize M$^2$I and we prove that it can achieve negative permeability and there exists a resonance condition where the radiated magnetic field can be significantly amplified. The radiation and communication performance are ev...

  12. Multiwavelength photometry in the Globular Cluster M2

    CERN Document Server

    Dalessandro, E; Lanzoni, B; Ferraro, F R; Schiavon, R; Rood, R T

    2009-01-01

    We present a multiwavelength photometric analysis of the globular cluster M2. The data-set has been obtained by combining high-resolution (HST/WFPC2 and ACS) and wide-field (GALEX) space observations and ground based (MEGACAM-CFHT, EMMI-NTT) images. The photometric sample covers the entire cluster extension from the very central regions up to the tidal radius and beyond. It allows an accurate determination of the cluster center of gravity and other structural parameters derived from the star count density profile. Moreover we study the BSS population and its radial distribution. A total of 123 BSS has been selected, and their radial distribution has been found to be bimodal (highly peaked in the center, decreasing at intermediate radii and rising outward), as already found in a number of other clusters. The radial position of the minimum of the BSS distribution is consistent with the radius of avoidance caused by the dynamical friction of massive objects over the cluster age. We also searched for gradients in...

  13. 水平轴潮流能捕获桨叶设计流速研究%Research on the design flow velocity of blade of horizontal axis tidal current turbine

    Institute of Scientific and Technical Information of China (English)

    林躜; 张利; 李江花; 姜楚华; 陈俊华; 杨灿军

    2016-01-01

    Aiming at solving the key problem of fixed-pitch blade of tidal current turbine, a mathematical model for design velocity in variable flow velocities and blade capturing power is established using blade momentum and fluid dynamics theory. Based on the testing data around Jiushan archipelago and by maximizing the total capturing energy within a month and a half cycle of tidal current velocity variation as the goal, MATLAB is used to calculate iteration to get the right design velocity. Compared with the method of maximizing velocity as a design velocity, it makes a theoretical prediction on the angular velocity and the power captured of the turbine under different flow velocities. An experimental platform is set up for actual testing and the results show that the capturing power of the blade which is designed under appropriate design flow velocities is superior to that of the previous design blade during most time of marine current velocity variation, with the total capturing energy in a month and a half cycle of variable flow velocities increased by about 8%, validating the correctness and rationality of the design method, which has a certain reference value for the design of fixed-pitch marine current turbine blades in variable flow velocities.%针对定桨距桨叶在时变潮流流速中设计流速选取的关键问题,应用叶素动量与流体动力学理论,建立变流速中设计流速与桨叶捕获功率之间的数学模型。结合韭山列岛的实测数据,以潮流流速变化的一个半月周期内捕获总能量最大为目标,利用MATLAB计算迭代得到合适的设计流速。与最大潮流流速作为设计流速的设计方法作对比,对不同流速下桨叶的旋转角速度及捕获功率情况作理论预测对比。搭建实验平台进行实际测试,结果显示:基于合适设计流速下的桨叶设计在潮流流速变化的大部分时间段内功率捕获优于以往设计桨叶,在潮流流速变化

  14. Tidal and subtidal hydrodynamics and energetics in a constricted estuary

    Science.gov (United States)

    Zarzuelo, Carmen; López-Ruiz, Alejandro; Díez-Minguito, Manuel; Ortega-Sánchez, Miguel

    2017-02-01

    The dynamics of coastal plain estuaries are mainly associated with variable tidal forcing and local winds in combination with bathymetric complexity and coastline irregularity. Specific features, such as constricted areas, can potentially affect and energize the hydrodynamics of these types of systems. Particularly, tidal range and tidal currents can be significantly amplified where the incoming tidal wave becomes constricted. In this work, the impact of a narrow constriction on a mesotidal estuary was analysed at tidal and subtidal time scales. Tidal hydrodynamics, energy fluxes and energy dissipation were determined for the entire Cádiz Bay (southwestern Spain) using the Delft3D numerical model. Field observations were used to analyse tidal propagation and energy dissipation along the bay constriction and to calibrate and test the numerical model. The results indicate that the presence of the constriction transformed and distorted the tide and increased the tidal range and flow velocities along the channel, with implications on energy dissipation. The tidal currents were oriented along-channel at the central part of the constriction, although abrupt bathymetric changes at the channel inner boundary provoked a sudden rotation of the flow. Although the energy fluxes were higher for spring tides and were strongly influenced by winds, the energy dissipation was controlled by bed shear stresses and vertical dispersion. The significance of this energy dissipation was that it destabilized the water column, which resulted in a weakly stratified system with implications on water quality. At a subtidal scale, the residual water volume exchange was the result of the combined effects of the neap/spring tides, wind and waves, whereas tides were dominant at the tidal scale.

  15. Superconformal indices and M2-branes

    Energy Technology Data Exchange (ETDEWEB)

    Eager, Richard [Kavli Institute for the Physics and Mathematics of the Universe (WPI),University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Schmude, Johannes [RIKEN Nishina Center, Saitama 351-0198 (Japan)

    2015-12-10

    We derive the superconformal index of the world-volume theory on M2-branes probing the cone over an arbitrary Sasaki-Einstein seven-manifold. The index is expressed in terms of the cohomology groups of the cone. We match our supergravity results with known results from gauge theory. Along the way we derive the spectrum of short Kaluza-Klein multiplets on generic Sasaki-Einstein seven-manifolds.

  16. Superconformal indices and M2-branes

    Science.gov (United States)

    Eager, Richard; Schmude, Johannes

    2015-12-01

    We derive the superconformal index of the world-volume theory on M2-branes probing the cone over an arbitrary Sasaki-Einstein seven-manifold. The index is expressed in terms of the cohomology groups of the cone. We match our supergravity results with known results from gauge theory. Along the way we derive the spectrum of short Kaluza-Klein multiplets on generic Sasaki-Einstein seven-manifolds.

  17. LES of Langmuir supercells under constant crosswind tidal forcing

    Science.gov (United States)

    Walker, Rachel; Zhang, Jie; Juha, Mario; Gosch, Chester; Tejada-Martinez, Andres

    2015-11-01

    We report on the impact of a crosswind tidal current on Langmuir supercells (LSCs) in shallow water computed via LES. LSCs consist of parallel counter rotating vortices engulfing the water column in unstratified conditions. These cells have been observed in shallow continental shelf regions of ~15 meters depth during the passage of storms. The cells are aligned roughly in the wind direction and are generated by the interaction of the wind-driven shear current with the Stokes drift velocity induced by surface gravity waves. Without tides, LES reveals that the typical crosswind width of a LSC is ~4 times the water column depth (H). Under a relatively weak crosswind tidal current (weaker than the downwind current), the constant crosswind tidal forcing applied causes a merging of cells leading to cells of width ~8H. The opposite occurs under a crosswind tidal current stronger than the downwind current as the constant crosswind tidal force is able to break up the LSCs giving rise to smaller scale cells with different turbulent structure than that associated with LSC. Statistics of the turbulence during strong and weak crosswind tides will be contrasted and implications of an oscillating crosswind tidal force will be discussed. Support from the US National Science Foundation and the Gulf of Mexico Research Initiative is gratefully acknowledged.

  18. Tidal Evolution of Exoplanets

    CERN Document Server

    Correia, Alexandre C M

    2010-01-01

    Tidal effects arise from differential and inelastic deformation of a planet by a perturbing body. The continuous action of tides modify the rotation of the planet together with its orbit until an equilibrium situation is reached. It is often believed that synchronous motion is the most probable outcome of the tidal evolution process, since synchronous rotation is observed for the majority of the satellites in the Solar System. However, in the 19th century, Schiaparelli also assumed synchronous motion for the rotations of Mercury and Venus, and was later shown to be wrong. Rather, for planets in eccentric orbits synchronous rotation is very unlikely. The rotation period and axial tilt of exoplanets is still unknown, but a large number of planets have been detected close to the parent star and should have evolved to a final equilibrium situation. Therefore, based on the Solar System well studied cases, we can make some predictions for exoplanets. Here we describe in detail the main tidal effects that modify the...

  19. How does a tidal embayment morphodynamically react on sea level rise?

    Science.gov (United States)

    van der Wegen, Mick

    2010-05-01

    Conditions for (assumed) equilibrium in tidal embayments have been studied extensively in the past years with morphodynamic 1D models (Van Dongeren and De Vriend, 1994; Schuttelaars and de Swart, 1996, 2000; Lanzoni and Seminara, 2002) and 2D models (Hibma et al. [2003], Van der Wegen and Roelvink [2008]) Van der Wegen et al 2008). The current research addresses the impact of sea level rise on tidal embayments. Although effects of sea level rise may only become apparent after decades, the character of the embayment can change considerably. Examples are the (dis)appearance or re-allocation of intertidal flats, increased tidal resonance, shift from sediment export to import, deepening of channel area and other related (ecological) parameters. The research applies a 2D morphodynamic model (Delft3D) in an idealized environment. The model is based on the 2 D shallow water equations, the Engelund -Hansen transport formula and includes bed slope effects, drying and flooding procedures and an advanced morphodynamic update scheme (Roelvink 2006). The initial condition of the bathymetry is generated by 3000 years of morphodynamic calculations in a 80 km long and 2.5 km wide rectangular tidal embayment under constant M2 tidal forcing conditions (Van der Wegen and Roelvink [2008]). After this period sea level rise gradually developing towards a rate of 0.4 m/century is added to the boundary conditions. Model results describe development towards less intertidal area and a transition from an exporting system to a importing system. Model results are evaluated in terms of M2, M4 and M6 tidal constituents as well as against Vs/Vc (shoal volume over channel volume) versus a/h (amplitude over water depth) relationship as proposed by Friedrichs and Aubrey (1988). Although the model describes morphodynamic development in a strongly idealized environment the results can provide an excellent tool to systematically study the impact of sea level rise in tidal embayments as well as the time

  20. Sensitivity of growth characteristics of tidal sand ridges and long bed waves to formulations of bed shear stress, sand transport and tidal forcing: A numerical model study

    Science.gov (United States)

    Yuan, Bing; de Swart, Huib E.; Panadès, Carles

    2016-09-01

    Tidal sand ridges and long bed waves are large-scale bedforms that are observed on continental shelves. They differ in their wavelength and in their orientation with respect to the principal direction of tidal currents. Previous studies indicate that tidal sand ridges appear in areas where tidal currents are above 0.5 m s-1, while long bed waves occur in regions where the maximum tidal current velocity is slightly above the critical velocity for sand erosion and the current is elliptical. An idealized nonlinear numerical model was developed to improve the understanding of the initial formation of these bedforms. The model governs the feedbacks between tidally forced depth-averaged currents and the sandy bed on the outer shelf. The effects of different formulations of bed shear stress and sand transport, tidal ellipticity and different tidal constituents on the characteristics of these bedforms (growth rate, wavelength, orientation of the preferred bedforms) during their initial formation were examined systematically. The results show that the formulations for bed shear stress and slope-induced sand transport are not critical for the initial formation of these bedforms. For tidal sand ridges, under rectilinear tidal currents, increasing the critical bed shear stress for sand erosion decreases the growth rate and the wavelength of the preferred bedforms significantly, while the orientation angle slightly decreases. The dependence of the growth rate, wavelength and the orientation of the preferred bedforms on the tidal ellipticity is non-monotonic. A decrease in tidal frequency results in preferred bedforms with larger wavelength and smaller orientation angle, while their growth rate hardly changes. In the case of joint diurnal and semidiurnal tides, or spring-neap tides, the characteristics of the bedforms are determined by the dominant tidal constituent. For long bed waves, the number of anticyclonically/cyclonically oriented bedforms with respect to the principal

  1. The study method of estimation tidal flat with remote sensing waterlines

    Science.gov (United States)

    Gao, Zhiqiang; Liu, Xiangyang; Zhang, Yuanyuan; Liu, Chaoshun; Sun, Zhibin

    2016-09-01

    A tidal flat, the important potential land resource, is the sensitive area of intersection between the sea and the land. With Chinese HJ-1A/B remote sensing images of 2014 as data sources, based on the definition of a tidal flat, using DSAS software and Jenks Natural Breaks classification method synthetically, a more reasonable and accurate method of extracting tidal flat was imposed. In addition, the Bohai Rim was taken as an example to carry out investigation on the current situation of tidal flat. This paper can provide basic date and scientific evidence for rational utilization and sustainable development of tidal flat.

  2. Study on the Numerical Simulation of Hydrodynamic Performance of the Horizontal Axis Tidal Current Turbine%水平轴潮流能水轮机水动力数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    侯二虎; 杜敏; 王兵振

    2015-01-01

    Aimed at the horizontal axis tidal current turbine, this paper conducts mechanical analysis and simulated calculation on its hydrodynamic performance using the CFD method. The steady and unsteady computing results are compared, and the power, torque and thrust characteristic curve of the turbine performance is obtained with the MRF method. The performance of the turbine at different tip speed ratios is also analyzed. An experiment was carried out that dragged the turbine in a pool, before comparing with the simulated data, proving good fitting of each other. The damping of power coefficient under high tip speed ratio during the experiment process is analyzed, indicating that the CFD simulation on the turbine can guide the engineering practice. The velocity image, streamline and damping curve of the wake are obtained, which shows that the region of wake influenced by turbine is larger compared with the turbine's diameter. The damping circumstances of different locations behind the turbine are analyzed and the results show that considerable difference exists in the velocity recovery with different axial distances behind the turbine. The method presented in this paper can provide a basis for studying the arrangement method of large-scale tidal current turbines.%针对水平轴潮流能水轮机,对其进行了力学分析并运用CFD方法对其水动力性能进行了仿真计算。比较了定常计算与非定常计算结果的区别,运用定常计算(MRF)方法得到了表现水轮机性能的功率、扭矩和推力特性曲线,分析了水轮机在不同尖速比时的表现。对水轮机模型进行了拖曳水池试验,并与仿真数据进行了比对分析,两者吻合度较好,并分析了试验过程中出现的在尖速比较大时功率系数衰减的现象,表明CFD方法对水轮机的工程实践有着指导意义。得到了尾流场的速度云图、流线分布图与衰减曲线,结果表明相对于水轮机的直径,受

  3. Tidal energy resource complexity in a large strait: The Karori Rip, Cook Strait

    Science.gov (United States)

    Stevens, C. L.; Smith, M. J.; Grant, B.; Stewart, C. L.; Divett, T.

    2012-02-01

    Successful extraction of tidal stream energy will require a good understanding of flow at a range of scales, including those relating to average energy, variability in energy supply and fatigue. Current and turbulence measurements from the Karori Rip area of Cook Strait, the prime focal region of open-water tidal stream electricity generation in New Zealand, are described. A key issue is that a significant portion of the energy is contained in waters deeper than normally considered for energy extraction. Here we compare shallow and deep sites. Velocity data were derived from acoustic Doppler current profiler moorings, as well as spatial surveys and show flow magnitudes reaching 3.4 m s -1 in the shallow regions. The maximum speeds in both shallow and deep sites were typically located in the upper part of the measured water column although moored acoustic Doppler current profiler (ADCP) observations showed some complexity in this regard. Benthic boundary-layers were resolved in the bottom ˜20 m of the water column. Measured turbulent kinetic energy dissipation rates ɛ exceeded 10 -5 m 2 s -3 and estimated maximum ɛ is a factor of 10 greater. This was not distributed evenly through the water column, with stratification and velocity shear clearly persisting, especially around the turn of the tide. The implications for tidal stream energy are that (i) there is sufficient energy resource in the region for a moderate sized array of turbines, (ii) the vertical variability in the flow speed suggests turbines that can operate near the surface would be more effective at accessing the resource, (iii) stratification may persist and influence the scales of turbulence and (iv) wave-current interaction effects will influence any near-surface structure as well as vessel operations.

  4. Hydromechanics for the formation and development of radial sandbanks (Ⅰ)——Plane characteristics of tidal flow

    Institute of Scientific and Technical Information of China (English)

    严以新; 诸裕良; 薛鸿超

    1999-01-01

    Based upon the long-term observation of field data, a two-dimensional numerical model is applied to simulating the tidal flow covering from the neap tide to spring tide in the radial sandbank area in the southern Yellow Sea. From the development of tidal current ridges under the hydrodynamic action, multi-purpose analysis and study are carried out, which include the propagation process of tidal wave, the distributions of tidal wave energy rate and tidal range, the tidal ellipses and traces. It is shown that the tidal current is the major dynamic factor for the formation and development of the radial sandbanks, and the differences of tidal wave energy rate and current strength determine the distinct plane shapes of ridges and troughs in this region.

  5. 竖直轴潮流发电水轮机调距机构设计%Variable-pitch mechanism design of a vertical-axis tidal current turbine

    Institute of Scientific and Technical Information of China (English)

    孔凡凯; 郑大勇; 孙桂林; 应丽霞

    2011-01-01

    为了进行竖直轴潮流发电水轮机的水动力性能模型试验研究,需重点设计该水轮机的叶片调距机构.在分析现有叶片控制机构的设计思路基础上,提出了一种双偏心机构与双曲柄六杆机构相结合的新型竖直轴水轮机调距机构.对该机构进行了运动学分析,应用相关软件对其进行运动仿真,验证了该方案设计的合理性,并分别给出了工作原理和装配图.所建立的运动学模型对进一步开展竖轴水轮机的相关模型试验研究具有一定的参考意义.%To research the hydrodynamic performance of the vertical-axis variable-pitch tidal current turbine, it is necessary to design the blade control mechanism of the turbine. On the basis of analyzing the existing design idea for the blade control mechanism, this paper proposed a new style of a vertical-axis turbine variable-pitch mechanism which combined a double-eccentric mechanism and double-crank six-rod mechanism. A kinematic analysis was carried out of the mechanism and motion simulation was conducted on it with related software, verifying the reasonableness of the design scheme and giving the working principle and assembly drawing. The established kinematic model has a significant reference value for the further development of vertical axis turbine model testing.

  6. Don't Cross the (Tidal) Streams

    Science.gov (United States)

    Kohler, Susanna

    2015-09-01

    In a tidal disruption event (TDE), an unfortunate star passes too close to a dormant supermassive black hole (BH) and gets torn apart by tidal forces, feeding the BH for a short time. Oddly, were not finding nearly as many TDEs typically detected due to their distinctive observational signatures as theory says we should. A recent study suggests that we might be missing many of these events, due to the way the streams of shredded stars fall onto the BHs.Signatures of ShreddingWhen a BH tears a star apart, the stars material is stretched out into whats known as a tidal stream. That stream continues on a trajectory around the BH, with roughly half the material eventually falling back on the BH, whipping around it in a series of orbits. Where those orbits intersect each other, the material smashes together and circularizes, forming a disk that then accretes onto the BH.What does a TDE look like? We dont observe anything until after the tidal streams collide and the material begins to accrete onto the BH. At that point we observe a sudden peak in luminosity, which then gradually decreases (scaling roughly as time-5/3) as the tail end of whats left of the star accretes and the BHs food source eventually runs out.So why have we only been observing about a tenth as many TDEs as theory predicts we should see? By studying the structure of tidal streams in TDEs, James Guillochon (Harvard-Smithsonian Center for Astrophysics) and Enrico Ramirez-Ruiz (UC Santa Cruz) have found a potential reason and the culprit is general relativity.Dark YearsThe authors run a series of simulations of TDEs around black holes of varying masses and spins to see what form the resulting tidal streams take over time. They find that precession of the tidal stream due to the BHs gravitational effects changes how the stream interacts with itself, and therefore what we observe. Some cases behave like what we expect for whats currently considered a typical TDE but some dont.Example from simulations of a

  7. A simple approach to adjust tidal forcing in fjord models

    Science.gov (United States)

    Hjelmervik, Karina; Kristensen, Nils Melsom; Staalstrøm, André; Røed, Lars Petter

    2017-07-01

    To model currents in a fjord accurate tidal forcing is of extreme importance. Due to complex topography with narrow and shallow straits, the tides in the innermost parts of a fjord are both shifted in phase and altered in amplitude compared to the tides in the open water outside the fjord. Commonly, coastal tide information extracted from global or regional models is used on the boundary of the fjord model. Since tides vary over short distances in shallower waters close to the coast, the global and regional tidal forcings are usually too coarse to achieve sufficiently accurate tides in fjords. We present a straightforward method to remedy this problem by simply adjusting the tides to fit the observed tides at the entrance of the fjord. To evaluate the method, we present results from the Oslofjord, Norway. A model for the fjord is first run using raw tidal forcing on its open boundary. By comparing modelled and observed time series of water level at a tidal gauge station close to the open boundary of the model, a factor for the amplitude and a shift in phase are computed. The amplitude factor and the phase shift are then applied to produce adjusted tidal forcing at the open boundary. Next, we rerun the fjord model using the adjusted tidal forcing. The results from the two runs are then compared to independent observations inside the fjord in terms of amplitude and phases of the various tidal components, the total tidal water level, and the depth integrated tidal currents. The results show improvements in the modelled tides in both the outer, and more importantly, the inner parts of the fjord.

  8. Tidal Energy Research

    Energy Technology Data Exchange (ETDEWEB)

    Stelzenmuller, Nickolas [Univ of Washington; Aliseda, Alberto [Univ of Washington; Palodichuk, Michael [Univ of Washington; Polagye, Brian [Univ of Washington; Thomson, James [Univ of Washington; Chime, Arshiya [Univ of Washington; Malte, Philip [Univ of washington

    2014-03-31

    This technical report contains results on the following topics: 1) Testing and analysis of sub-scale hydro-kinetic turbines in a flume, including the design and fabrication of the instrumented turbines. 2) Field measurements and analysis of the tidal energy resource and at a site in northern Puget Sound, that is being examined for turbine installation. 3) Conceptual design and performance analysis of hydro-kinetic turbines operating at high blockage ratio, for use for power generation and flow control in open channel flows.

  9. Tidal and marine energy in the uk– identifying the future challenges for supply chain development

    OpenAIRE

    Thomas, Andrew; Mason-Jones, Rachel; Turner, David,; Davies, Paul; O’Doherty, Tim; O’Doherty, Daphne; Mason-Jones, Allan; Murphy, Lyndon

    2013-01-01

    The purpose of this paper is to investigate the current technical and operational supply chain issues surrounding the development of tidal and marine energy production in the UK. The paper outlines the market and growth potential of tidal energy production in the UK before identifying the key supply chain themes surrounding tidal energy production including an analysis of the portability and transferability of current supply chain thinking and development from other renewable energy systems s...

  10. The influence of the “tidal stress” on the residual circulation

    OpenAIRE

    NIHOUL, JACQUES C. J.; Ronday, Francois C.

    2011-01-01

    The residual current field in the sea is defined as the mean velocity field over a time sufficiently long to cancel transitory wind currents and tidal oscillations. The hydrodynamic equations governing the residual circulation are established and it is shown that, in the regions of intensive tides, the tidal motion has a cogent influence on the residual flow pattern. This effect which arises from the non linear terms is equivalent to the application of a “tidal stress” which combines with the...

  11. LOSA-M2 aerosol Raman lidar

    Energy Technology Data Exchange (ETDEWEB)

    Balin, Yu S; Bairashin, G S; Kokhanenko, G P; Penner, I E; Samoilova, S V [V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

    2011-10-31

    The scanning LOSA-M2 aerosol Raman lidar, which is aimed at probing atmosphere at wavelengths of 532 and 1064 nm, is described. The backscattered light is received simultaneously in two regimes: analogue and photon-counting. Along with the signals of elastic light scattering at the initial wavelengths, a 607-nm Raman signal from molecular nitrogen is also recorded. It is shown that the height range of atmosphere probing can be expanded from the near-Earth layer to stratosphere using two (near- and far-field) receiving telescopes, and analogue and photon-counting lidar signals can be combined into one signal. Examples of natural measurements of aerosol stratification in atmosphere along vertical and horizontal paths during the expeditions to the Gobi Desert (Mongolia) and Lake Baikal areas are presented.

  12. Periodic Arrays of M2-Branes

    CERN Document Server

    Jeon, Imtak; Richmond, Paul

    2012-01-01

    We consider periodic arrays of M2-branes in the ABJM model in the spirit of a circle compactification to D2-branes in type IIA string theory. The result is a curious formulation of three-dimensional maximally supersymmetric Yang-Mills theory in terms of fermions, seven transverse scalars, a non-dynamical gauge field and an additional scalar `dual gluon'. Upon further T-duality on a transverse torus we obtain a non-manifest-Lorentz-invariant description of five-dimensional maximally supersymmetric Yang-Mills. Here the additional scalar field can be thought of as the components of a two-form along the torus. This action can be viewed as an M-theory description of M5-branes on ${\\mathbb T}^3$.

  13. The (178m2)Hf Controversy

    Energy Technology Data Exchange (ETDEWEB)

    Becker, J A; Gemmell, D S; Schiffer, J P; Wilhelmy, J B

    2003-07-24

    Since its discovery in the 1960's the {sup 178m2}Hf isomer has garnered high attention from both the basic and applied communities in nuclear science. It's combination of high spin (16+), long half life (31 yrs), and high excitation energy (2.446 MeV) offer unique possibilities as an energy storage medium. Interest in the isomer was rekindled beginning in 1999 when a series of publications began to appear from a group (referred to here as the ''Texas collaboration'') primarily based at the University of Texas, Dallas [1]. They reported observations that some of the stored energy could be released (''triggered'') when the isomer was exposed to a fluence of photons in the energy range {approx}10 to {approx}60 keV. The implications of this observation are profound. Even though the claimed cross section for the process was {approx}7 orders of magnitude greater than would be predicted from the known systematics of photon absorption by nuclei in this mass range [2], such a highly efficient method for triggering the isomeric deexcitation immediately suggested applications utilizing the explosive or the controlled gradual energy release from a very compact source. The prospect of such applications has focused considerable interest on realizing the promise that is implicit in the reported observations. However, two experiments performed by a group from ANL/LANL/LLNL at the Advanced Photon Source at Argonne (the ''APS collaboration'') reported negative results for the observation of any photon-triggered deexcitation of the {sup 178m2}Hf isomer [3]. This has led to a continued controversy, where both sides have adamantly defended their observations. At this point an outsider has difficulty determining whether there is indeed a triggering effect that should be pursued energetically with substantial resources, or whether the phenomenon consists of overly optimistic interpretation of data.

  14. Tidal motions and tidally induced fluxes through La Línea submarine canyon, western Alboran Sea

    Science.gov (United States)

    Lafuente, Jesús GarcíA.; Sarhan, Tarek; Vargas, Manuel; Vargas, Juan M.; Plaza, Francisco

    1999-02-01

    Detailed observations from two mooring lines deployed in La Línea submarine canyon, western Alboran Sea, are presented. This is a narrow canyon in the sense that its width is always less than the internal radius of deformation. Tidal currents within the canyon are polarized in the along-canyon direction according to its narrow nature. They have considerable amplitude (values of around 0.5 m/s are often observed) and are forced by the internal pressure gradients associated with the baroclinic tide that is generated in the surroundings. Subsequent amplification of onshore baroclinic currents within the canyon accounts for the large amplitude observed. Cross-shelf exchange through the canyon due to tidal motions is different from zero despite the close to zero mean of tidal currents. The explanation is based on the asymmetry of water properties flowing up-canyon and down-canyon (some sort of tidal rectification). Regarding the energy flux, the canyon seems to be an adequate conduit to carry energy to the shore. Estimations made from our observations indicate that energy input onto the shelf per unit length parallel to the shore at the canyon head is enough to maintain mixing on the shelf at intermediate depths.

  15. Study on maximum power control of turbines in a tidal current power generation system based on hydraulic transmission%液压型潮流能发电系统叶轮最大功率控制

    Institute of Scientific and Technical Information of China (English)

    林躜; 李磊; 陈俊华; 郑堤; 唐辰; 李浩

    2014-01-01

    In order to solve the problem of low energy capturing efficiency of the horizontal axis turbine in tidal current power generation system at low current speed, a variable pump counter torque reference value model was established. In this study, based on the maximum power tracking theory and the torque equilibrium equation of turbine versus variable pump, a control system with indirect speed control, pressure feedback, and torque control was designed to achieve the maximum power capture of the turbine by regulating the output of the variable pump in a small range. The performance of the designed control system was simulated by means of the Automation Studio software, and corresponding sea test was conducted. Test results showed that the control system ran steadily, the captured power coefficient of the turbine fluctuated near 0.35 and 0.33, respectively, in the simulation and sea trials; compared with the uncontrolled, these numbers increased by 0.03 and 0.05, respectively. The capture efficiency of the turbine was enhanced, and the effectiveness of the control system was verified.%文章为解决水平轴潮流能发电系统在低于设计流速下叶轮能量捕获效率低的问题,运用最大功率跟踪控制理论及叶轮与变量泵传动轴力矩平衡方程,建立了变量泵反力矩参考值模型,设计了间接速度控制的压力反馈加转矩控制系统,通过小范围内调节变量泵排量,实现叶轮最大功率捕获。整个系统的性能在自动化工作室(automation studio)中进行了仿真测试,实验样机也进行了海上试验。仿真测试和海试结果显示,该控制系统工作稳定性好,仿真和海试时叶轮的捕获功率系数分别在0.35和0.33附近波动,相比不加控制,分别增加了约0.03和0.05,提高了叶轮的捕获效率,验证了控制系统的有效性。

  16. Modeling the Ocean Tide for Tidal Power Generation Applications

    Science.gov (United States)

    Kawase, M.; Gedney, M.

    2014-12-01

    Recent years have seen renewed interest in the ocean tide as a source of energy for electrical power generation. Unlike in the 1960s, when the tidal barrage was the predominant method of power extraction considered and implemented, the current methodology favors operation of a free-stream turbine or an array of them in strong tidal currents. As tidal power generation moves from pilot-scale projects to actual array implementations, numerical modeling of tidal currents is expected to play an increasing role in site selection, resource assessment, array design, and environmental impact assessment. In this presentation, a simple, coupled ocean/estuary model designed for research into fundamental aspects of tidal power generation is described. The model consists of a Pacific Ocean-size rectangular basin and a connected fjord-like embayment with dimensions similar to that of Puget Sound, Washington, one of the potential power generation sites in the United States. The model is forced by an idealized lunar tide-generating potential. The study focuses on the energetics of a tidal system including tidal power extraction at both global and regional scales. The hyperbolic nature of the governing shallow water equations means consequence of tidal power extraction cannot be limited to the local waters, but is global in extent. Modeling power extraction with a regional model with standard boundary conditions introduces uncertainties of 3 ~ 25% in the power extraction estimate depending on the level of extraction. Power extraction in the model has a well-defined maximum (~800 MW in a standard case) that is in agreement with previous theoretical studies. Natural energy dissipation and tidal power extraction strongly interact; for a turbine array of a given capacity, the higher the level of natural dissipation the lower the power the array can extract. Conversely, power extraction leads to a decrease in the level of natural dissipation (Figure) as well as the tidal range and the

  17. Modern changes of tidal troughs among the radial sand ridges in northern Jiangsu coastal zone

    Institute of Scientific and Technical Information of China (English)

    HUANG Haijun; DU Tingqin; GAO Ang

    2009-01-01

    Using satellite images taken on different dates, GIS analysis of aerial photos, bathymetric maps and other field survey data, tidal troughs and major sand ridges in the northern Jiangsu coastal area were contrasted. The results show that there have been three types of movement or migration of tidal trough in this area: (1) Periodic and restricted, this type of trough usually developed along the beaches with immobile gully head as a result of the artificial dams and the swing range increased from gully head to the low reaches, so they have been obviously impacted by human activity and have longer swing periods; (2) Periodic and actively, this kind of trough, which swung with a fast rate and moved periodically on sand ridges, were mainly controlled by the swings of the host tidal troughs and hydrodynamic forces upon tidal sand ridge and influenced slightly by human constructions; (3) Steadily and slowly, they are the main tidal troughs with large scale and a steady orientation in this area and have slow lateral movement. The differences in migration mode of tidal trough shift result in different rates of migration and impact upon tidal sand ridges. Lateral accumulation on current tidal trough and deposition on abandoned tidal troughs are the two types of sedimentation of the tidal sand ridges formation. The whole radial sand ridge was generally prone to division and retreat although sand ridges fluctuated by the analysis of changes in talwegs of tidal troughs and shorelines of sand ridges.

  18. Evidence of paired M2 muscarinic receptors

    Energy Technology Data Exchange (ETDEWEB)

    Potter, L.T.; Ballesteros, L.A.; Bichajian, L.H.; Ferrendelli, C.A.; Fisher, A.; Hanchett, H.E.; Zhang, R. (Univ. of Miami School of Medicine, FL (USA))

    1991-02-01

    Binding assays involving various antagonists, including N-(3H) methylscopolamine, (3H)quinuclidinyl benzilate, AFDX-116, pirenzepine, and propylbenzilylcholine mustard, disclosed only a single population of M2 muscarinic receptors in membranes from the rat brainstem (medulla, pons, and colliculi). However, competition curves between N-(3H)methylscopolamine and various agonists, including oxotremorine, cis-dioxolane, and acetylethylcholine mustard, showed approximately equal numbers of guanine nucleotide-sensitive high affinity (H) sites and guanine nucleotide-insensitive low affinity (L) sites. This 50% H phenomenon persisted in different buffers, at different temperatures, after the number of receptors was halved (and, thus, the remaining receptor to guanine nucleotide-binding protein ratio was doubled), after membrane solubilization with digitonin, and when rabbit cardiac membranes were used instead of rat brainstem membranes. Preferential occupation of H sites with acetylethylcholine mustard, and of L sites with quinuclidinyl benzilate or either mustard, yielded residual free receptor populations showing predominantly L and H sites, respectively. Low concentrations of (3H)-oxotremorine-M labeled only H sites, and the Bmax for these sites was 49% of the Bmax found with (3H)quinuclidinyl benzilate plus guanine nucleotide. These and other results are most consistent with the idea that H and L receptor sites exist on separate but dimeric receptor molecules and with the hypothesis that only the H receptors cycle between high and low affinity, depending upon interactions between this receptor molecule and a guanine nucleotide-binding protein.

  19. 垂直轴潮流水轮机流场的三维数值模拟%Three-dimensional Numerical Simulation on the Flow Field of the Vertical Axis Tidal Current Turbine

    Institute of Scientific and Technical Information of China (English)

    朱萍; 成明

    2012-01-01

    为了研究流场的空间分布特点,建立了垂直轴潮流水轮机在水槽中的物理模型,采用Fluent软件中的滑移网格技术对模型的流场进行了三维数值模拟,分析了不同时刻不同截面上模型速度场的变化规律以及同一时刻不同直线上模型速度场和压力场的分布特点.结果表明,叶轮在水槽中旋转,所处位置不同,流场的分布有所差异,流动充分后,流场的变化具有周期性;叶轮内部速度场的变化最为紊乱,叶片周围的速度发生急剧变化;叶轮在旋转过程中产生漩涡,叶片迎流面的压力急剧上升,背流面的负压最为强烈.%In order to study the spatial distribution of the flow field, a physical model of the vertical axis tidal current turbine inside the sink is established. Based on the physical model and sliding grid technology, the three dimensional numerical simulation of the flow field is given by using the software Fluent. Both the velocity field on different sections at different moments and the distribution of the velocity and pressure field on different lines at the same moment are analyzed. The result shows that the distribution of the flow field varies at different positions with the impeller rotating in the sink and the change of the flow field will be cyclical under fully developed flow areas. The velocity field is very disordered inside the impellers and the speed changes rapidly around the blades. Under the impeller rotating, vortexes appear. The pressure increases rapidly in the front of the blades facing the flow and decreases to negative pressure rapidly in the back of the blades.

  20. Experimental hydrodynamic study of the Qiantang River tidal bore

    Institute of Scientific and Technical Information of China (English)

    HUANG Jing; PAN Cun-hong; KUANG Cui-ping; ZENG Jian; CHEN Gang

    2013-01-01

    To study the hydrodynamics of tidal bore,a physical modeling study is carried out in a rectangular flume with considerations of the tidal bore heights,the propagation speeds,the tidal current velocities,the front steepness,and the bore shapes.After the validation with the field observations,the experimental results are analyzed,and it is shown that:(1) the greater initial ebb velocity or the larger initial water depth impedes the tidal bore propagation,(2) the maximum bore height appears at an initial ebb velocity in the range of 0.5 m/s-1.5 m/s,(3) when the Froude number exceeds 1.2,an undular bore appears,after it exceeds 1.3,a breaking bore occurs,and after it exceeds 1.7,the bore is broken.

  1. 3-D modelling the electric field due to ocean tidal flow and comparison with observations

    DEFF Research Database (Denmark)

    Kuvshinov, A.; Junge, A.; Utada, H.

    2006-01-01

    of the global distribution of the electric signal due to tidal ocean flow. We simulate the electric signals for two tidal constituents - lunar semidiurnal (M2) and diurnal (O1) tides. We assume a realistic Earth's conductivity model with a surface thin shell and 1-D mantle underneath. Simulations demonstrate......The tidal motion of the ocean water through the ambient magnetic field, generates secondary electric field. This motionally induced electric field can be detected in the sea or inland and has a potential for electrical soundings of the Earth. A first goal of the paper is to gain an understanding...

  2. Tidal controls on riverbed denitrification along a tidal freshwater zone

    Science.gov (United States)

    Knights, Deon; Sawyer, Audrey H.; Barnes, Rebecca T.; Musial, Cole T.; Bray, Samuel

    2017-01-01

    In coastal rivers, tidal pumping enhances the exchange of oxygen-rich river water across the sediment-water interface, controlling nitrogen cycling in riverbed sediment. We developed a one-dimensional, fluid flow and solute transport model that quantifies the influence of tidal pumping on nitrate removal and applied it to the tidal freshwater zone (TFZ) of White Clay Creek (Delaware, USA). In field observations and models, both oxygenated river water and anoxic groundwater deliver nitrate to carbon-rich riverbed sediment. A zone of nitrate removal forms beneath the aerobic interval, which expands and contracts over daily timescales due to tidal pumping. At high tide when oxygen-rich river water infiltrates into the bed, denitrification rates decrease by 25% relative to low tide. In the absence of tidal pumping, our model predicts that the aerobic zone would be thinner, and denitrification rates would increase by 10%. As tidal amplitude increases toward the coast, nitrate removal rates should decrease due to enhanced oxygen exchange across the sediment-water interface, based on sensitivity analysis. Denitrification hot spots in TFZs are more likely to occur in less permeable sediment under lower tidal ranges and higher rates of ambient groundwater discharge. Our models suggest that tidal pumping is not efficient at removing surface water nitrate but can remove up to 81% of nitrate from discharging groundwater in the TFZ of White Clay Creek. Given the high population densities of coastal watersheds, the reactive riverbeds of TFZs play a critical role in mitigating new nitrogen loads to coasts.

  3. Tidal Signatures of the Benthic Nepheloid Layer (BNL) in the Gaoping/Kaoping Submarine Canyon off Southwestern Taiwan

    Science.gov (United States)

    Liu, J. T.; Lee, I.; Wang, Y.

    2008-12-01

    Temporal and spatial variations of benthic nepheloid layer (BNL) have been observed in the head region of the Gaoping/Kaoping Submarine Canyon (KPSC) along the canyon thalweg in different seasons between 1999 and 2000. The top of the BNL could be as high as 100 m above the canyon floor whose suspended sediment concentration (SSC) could be as high as 30 mg/l. In the BNL, silt comprises the largest size-class in the suspended sediment population. In 2000, 2002, and 2004 three taut-line moorings were deployed at different locations in the head region of the KPSC for one month. Time series measurements of along- canyon flow velocity, water temperature, and the volume concentration (VC) of clay, very-fine-to-medium silt, coarse silt and sand size-classes were obtained near the canyon floor from each mooring. Results show that the BNL is strongly modulated by the tides in the descending order at semidiurnal, diurnal, and spring-neap frequencies. In the course of a semidiurnal tidal cycle, the flood (up-canyon) current brings colder water from seaward part of the canyon and the SSC and thickness of the BNL increases. The SSC near the canyon floor also increases in response to the peaks of flood and ebb currents of the semidiurnal tide. The tidal-to-total energy ratio (ER) for the along-canon flow is between 70-80%, and between 50-80% among the suspended sediment of clay, very-fine-to-medium silt, coarse silt and sand size-classes. M2 is the most important constituent in the along-canyon flow, water temperature, and the VC of the four size-classes. The local phase difference between the forcing (velocity), and the responses (temperature and VC) at the M2 frequency suggest the a mixture of progressive and standing waves and that topographic effect caused the phase varied along the canyon. The VC tidal amplitude ratio between M4 and M2 constituents of the four size-classes indicates that the temporal fluctuations of the suspended sediment concentration in the BNL are highly

  4. On luminescence bleaching of tidal channel sediments

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Pejrup, Morten; Murray, Andrew S.

    2015-01-01

    We investigate the processes responsible for bleaching of the quartz OSL signal from tidal channel sediment. Tidal dynamics are expected to play an important role for complete bleaching of tidal sediments. However, no studies have examined the amount of reworking occurring in tidal channels and o...

  5. Comprehensive Characterization a Tidal Energy Site (Invited)

    Science.gov (United States)

    Polagye, B. L.; Thomson, J. M.; Bassett, C. S.; Epler, J.; Northwest National Marine Renewable Energy Center

    2010-12-01

    Northern Admiralty Inlet, Puget Sound, Washington is the proposed location of a pilot tidal energy project. Site-specific characterization of the physical and biological environment is required for device engineering and environmental analysis. However, the deep water and strong currents which make the site attractive for tidal energy development also pose unique challenges to collecting comprehensive information. This talk focuses on efforts to optimally site hydrokinetic turbines and estimate their acoustic impact, based on 18 months of field data collected to date. Additional characterization efforts being undertaken by the University of Washington branch of the Northwest National Marine Renewable Energy Center and its partners include marine mammal presence and behavior, water quality, seabed geology, and biofouling potential. Because kinetic power density varies with the cube of horizontal current velocity, an accurate map of spatial current variations is required to optimally site hydrokinetic turbines. Acoustic Doppler profilers deployed on the seabed show operationally meaningful variations in flow characteristics (e.g., power density, directionality, vertical shear) and tidal harmonic constituents over length scales of less than 100m. This is, in part, attributed to the proximity of this site to a headland. Because of these variations, interpolation between stationary measurement locations introduces potentially high uncertainty. The use of shipboard acoustic Doppler profilers is shown to be an effective tool for mapping peak currents and, combined with information from seabed profilers, may be able to resolve power density variations in the project area. Because noise levels from operating turbines are expected to exceed regulatory thresholds for incidental harassment of marine mammals known to be present in the project area, an estimate of the acoustic footprint is required to permit the pilot project. This requires site-specific descriptions of pre

  6. Study on tidal gravity observations obtained at stations Zhongshan and Changcheng, Antarctic

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the international tidal gravity reference values at station Wuhan, the tidal gravity parameters, including the amplitude factors and phase differences are determined accurately by using the observations with three La-Coste-Romberg (LCR) gravimeters (G-589, ET-20 and ET-21) at stations Zhongshan and Changcheng in the Ant-arctic, respectively. The standard deviations of the determined amplitude factors of the main tidal waves are better than 0.5%. The amplitude of each tidal wave observed at station Zhongshan is much less than that of the same wave at station Changcheng. The differences of amplitude factors in the diurnal band (O1) at these two stations are less than 7% while those in the semi-diurnal band (M2) are larger than 40%. The influences of meteorology factors, such as atmospheric pressure and temperature, on the tidal gravity observations are very obvious. The oceanic loading effects on the tidal gravity are also very prominent. It is found that the amplitude of the final residual vec-tor of every tidal wave reduces significantly after oceanic correction based on the Schwiderski's global co-tides. However, because the local oceanic loading is not taken into account, the discrepancies of amplitude factors of wave O1 observed at Zhongshan from the corresponding values of theoretical tidal model are about 4%, and 9% at Changcheng.

  7. Enceladus' tidal dissipation revisited

    Science.gov (United States)

    Tobie, Gabriel; Behounkova, Marie; Choblet, Gael; Cadek, Ondrej; Soucek, Ondrej

    2016-10-01

    A series of chemical and physical evidence indicates that the intense activity at Enceladus' South Pole is related to a subsurface salty water reservoir underneath the tectonically active ice shell. The detection of a significant libration implies that this water reservoir is global and that the average ice shell thickness is about 20-25km (Thomas et al. 2016). The interpretation of gravity and topography data further predicts large variations in ice shell thickness, resulting in a shell potentially thinner than 5 km in the South Polar Terrain (SPT) (Cadek et al. 2016). Such an ice shell structure requires a very strong heat source in the interior, with a focusing mechanism at the SPT. Thermal diffusion through the ice shell implies that at least 25-30 GW is lost into space by passive diffusion, implying a very efficient dissipation mechanism in Enceladus' interior to maintain such an ocean/ice configuration thermally stable.In order to determine in which conditions such a large dissipation power may be generated, we model the tidal response of Enceladus including variable ice shell thickness. For the rock core, we consider a wide range of rheological parameters representative of water-saturated porous rock materials. We demonstrate that the thinning toward the South Pole leads to a strong increase in heat production in the ice shell, with a optimal thickness obtained between 1.5 and 3 km, depending on the assumed ice viscosity. Our results imply that the heat production in the ice shell within the SPT may be sufficient to counterbalance the heat loss by diffusion and to power eruption activity. However, outside the SPT, a strong dissipation in the porous core is required to counterbalance the diffusive heat loss. We show that about 20 GW can be generated in the core, for an effective viscosity of 1012 Pa.s, which is comparable to the effective viscosity estimated in water-saturated glacial tills on Earth. We will discuss the implications of this revisited tidal

  8. Signatures of LCDM substructure in tidal debris

    CERN Document Server

    Siegal-Gaskins, Jennifer M

    2007-01-01

    In the past decade, surveys of the stellar component of the Galaxy such as SDSS and 2MASS have revealed a number of stellar streams. Current and future observations are rapidly increasing the precision and quantity of data available, raising the possibility of using tidal streams to constrain the distribution of dark matter in the halo. Simulations of hierarchical structure formation in LCDM cosmologies predict that the dark matter halo of a galaxy like the Milky Way contains a smooth component as well as hundreds of subhalos with masses of ~10^8 solar masses and greater, and it has been suggested that the existence of coherent tidal streams is incompatible with the expected abundance of substructure. We investigate the properties of tidal streams arising from the disruption of satellites in a variety of dark matter halo models. In general, we find that the halo shape and the specific orbital path more strongly determine the degree of disruption of the satellite than does the presence or absence of substructu...

  9. The tidal filament of NGC 4660

    CERN Document Server

    Kemp, S N; Marquez-Lugo, R A; Zepeda-Garcia, D; Franco-Hernandez, R; Nigoche-Netro, A; Ramos-Larios, G; Navarro, S G; Corral, L J

    2016-01-01

    NGC 4660, in the Virgo cluster, is a well-studied elliptical galaxy which has a strong disk component (D/T about 0.2-0.3). The central regions including the disk component have stellar populations with ages about 12-13 Gyr from SAURON studies. However we report the discovery of a long narrow tidal filament associated with the galaxy in deep co-added Schmidt plate images and deep CCD frames, implying that the galaxy has undergone a tidal interaction and merger within the last few Gyr. The relative narrowness of the filament implies a wet merger with at least one spiral galaxy involved, but the current state of the system has little evidence for this. However a 2-component photometric fit using GALFIT shows much bluer B-V colours for the disk component than for the elliptical component, which may represent a residual trace of enhanced star formation in the disk caused by the interaction 1-2 Gyr ago. There are brighter concentrations within the filament which resemble Tidal Dwarf Galaxies, although they are at l...

  10. Tidal Creek Sentinel Habitat Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Ecological Research, Assessment and Prediction's Tidal Creeks: Sentinel Habitat Database was developed to support the National Oceanic and Atmospheric...

  11. Tidal disruption of inviscid planetesimals

    Science.gov (United States)

    Boss, A. P.; Cameron, A. G. W.; Benz, W.

    1991-01-01

    In view of previous efforts' demonstration that strongly dissipative planetesimals are immune to tidal disruption, an examination is presently conducted of the complementary case of inviscid planetesimals arising from collisions that are sufficiently energetic to entirely melt the resulting planetesimal and debris. The tidal disruption is numerically simulated by means of the smoothed particle hydrodynamics (SPH) code of Cameron and Benz (1991), concentrating on the tidal disruption of 0.01 earth-mass planetesimals passing by the earth with variations in the impact parameter at perigee and velocity at infinity. The SPH models show that tidal forces during a close encounter can efficiently convert orbital angular momentum into spin angular momentum, thereby initiating equatorial mass-shedding to inviscid planetesimals that have been spun up beyond the limit of rotational stability.

  12. A new high resolution tidal model in the arctic ocean

    DEFF Research Database (Denmark)

    Cancet, M.; Andersen, Ole Baltazar; Lyard, F.

    The Arctic Ocean is a challenging region for tidal modeling, because of its complex and not well-documented bathymetry, together combined with the intermittent presence of sea ice and the fact that the in situ tidal observations are rather scarce at such high latitudes. As a consequence, the accu......The Arctic Ocean is a challenging region for tidal modeling, because of its complex and not well-documented bathymetry, together combined with the intermittent presence of sea ice and the fact that the in situ tidal observations are rather scarce at such high latitudes. As a consequence...... of the tides improves the quality of the high latitudes altimeter sea surface heights and of all derived products, such as the altimetry-derived geostrophic currents, the mean sea surface and the mean dynamic topography. In addition, accurate tidal models are highly strategic information for ever......-growing maritime and industrial activities in this region. NOVELTIS and DTU Space have developed a regional, high-resolution tidal atlas in the Arctic Ocean, in the framework of the CryoSat Plus for Ocean (CP4O) ESA project. In particular, this atlas benefits from the assimilation of the most complete satellite...

  13. Dynamical Tidal Response of a Rotating Neutron Star

    Science.gov (United States)

    Landry, Philippe; Poisson, Eric

    2017-01-01

    The gravitational wave phase of a neutron star (NS) binary is sensitive to the deformation of the NS that results from its companion's tidal influence. In a perturbative treatment, the tidal deformation can be characterized by a set of dimensionless constants, called Love numbers, which depend on the NS equation of state. For static NSs, one type of Love number encodes the response to gravitoelectric tidal fields (associated with mass multipole moments), while another does likewise for gravitomagnetic fields (associated with mass currents). A NS subject to a gravitomagnetic tidal field develops internal fluid motions through gravitomagnetic induction; the fluid motions are irrotational, provided the star is non-rotating. When the NS is allowed to rotate, the situation is complicated by couplings between the tidal field and the star's spin. The problem becomes tractable in the slow-rotation limit. In this case, the fluid motions induced by an external gravitomagnetic field are fully dynamical, even if the tidal field is stationary: interior metric and fluid variables are time-dependent, and vary on the timescale of the rotation period. Remarkably, the exterior geometry of the NS remains time-independent.

  14. Tidal Energy Resource Assessment in Chacao Channel, Chile

    Science.gov (United States)

    Guerra, M.; Suarez, L.; Cienfuegos, R.; Thomson, J. M.

    2014-12-01

    The Chacao Channel, located in Los Lagos region in Chile (41º S; 73º W), is a highly energetic tidal channel, with a complex hydrodynamics resulting from the propagation of tidal waves through a narrow channel. The channel flow exhibits bi-directional tidal currents up to 4 to 5 m/s along with a high tidal range up to 6 m in its east end (Aiken, 2008: Cáceres et al., 2003). The channel has previously been identified as one of the most attractive sites in Chile for tidal energy extraction (Garrad Hassan and Partners, 2009); however this statement is based on global model predictions over coarse bathymetric information. In this investigation, the first hydrodynamic characterization of the Chacao channel is carried out in order to assess the hydrokinetic power available and to select the most interesting spots where the first tidal energy extraction devices might be installed in Chile. The Chacao channel hydrodynamic characterization and resource assessment is carried out in two stages: field measurements and numerical hydrodynamic modeling. The first stage involves a 10 m resolution multi-beam bathymetry of the channel, sea-level measurements using 6 tidal gauges distributed over the channel berms, tidal current measurements with 6 ADCPs distributed along the channel, and detailed measurements of turbulence in a specific spot in the channel using the Tidal Turbulence Mooring (TTM) developed by Thomson et al. (2013). In a second stage, numerical hydrodynamic modeling using FVCOM (Chen et al., 2003) was prepared for the entire Chacao channel region, using the field data collected in the first stage for calibration and validation of the model. The obtained results allow us to define suitable sites for marine energy extraction, finding large areas with 30 to 60 m depths where horizontal currents are above 1.5 m/s during 60% of the time of a 28 days tidal cycle, however the high levels of turbulence detected by the TTM indicate the need for more detailed studies on the

  15. Regional tidal lung strain in mechanically ventilated normal lungs.

    Science.gov (United States)

    Paula, Luis Felipe; Wellman, Tyler J; Winkler, Tilo; Spieth, Peter M; Güldner, Andreas; Venegas, Jose G; Gama de Abreu, Marcelo; Carvalho, Alysson R; Vidal Melo, Marcos F

    2016-12-01

    Parenchymal strain is a key determinant of lung injury produced by mechanical ventilation. However, imaging estimates of volumetric tidal strain (ε = regional tidal volume/reference volume) present substantial conceptual differences in reference volume computation and consideration of tidally recruited lung. We compared current and new methods to estimate tidal volumetric strains with computed tomography, and quantified the effect of tidal volume (VT) and positive end-expiratory pressure (PEEP) on strain estimates. Eight supine pigs were ventilated with VT = 6 and 12 ml/kg and PEEP = 0, 6, and 12 cmH2O. End-expiratory and end-inspiratory scans were analyzed in eight regions of interest along the ventral-dorsal axis. Regional reference volumes were computed at end-expiration (with/without correction of regional VT for intratidal recruitment) and at resting lung volume (PEEP = 0) corrected for intratidal and PEEP-derived recruitment. All strain estimates demonstrated vertical heterogeneity with the largest tidal strains in middependent regions (P < 0.01). Maximal strains for distinct estimates occurred at different lung regions and were differently affected by VT-PEEP conditions. Values consistent with lung injury and inflammation were reached regionally, even when global measurements were below critical levels. Strains increased with VT and were larger in middependent than in nondependent lung regions. PEEP reduced tidal-strain estimates referenced to end-expiratory lung volumes, although it did not affect strains referenced to resting lung volume. These estimates of tidal strains in normal lungs point to middependent lung regions as those at risk for ventilator-induced lung injury. The different conditions and topography at which maximal strain estimates occur allow for testing the importance of each estimate for lung injury.

  16. Parametric Dwarf Spheroidal Tidal Interaction

    CERN Document Server

    Fleck, J J; Fleck, Jean-Julien; Kuhn, Jeff R.

    2003-01-01

    The time dependent tidal interaction of the Local Group Dwarf Spheroidal (dS) Galaxies with the Milky Way (MW) can fundamentally affect their dynamical properties. The model developed here extends earlier numerical descriptions of dS-MW tidal interactions. We explore the dynamical evolution of dS systems in circular or elliptical MW orbits in the framework of a parametric oscillator. An analytic model is developed and compared with more general numerical solutions and N-body simulation experiments.

  17. Review of Tidal Lagoon Technology and Opportunities for Integration within the UK Energy System

    Directory of Open Access Journals (Sweden)

    Grazia Todeschini

    2017-07-01

    Full Text Available The number of distributed resources for renewable energy installed worldwide has been increasing rapidly in the last decade, and the great majority of these installations consist of solar panels and wind turbines. Other renewable sources of energy are not exploited to the same level: for instance, tidal energy is still a minute portion of the global energy capacity, in spite of the large amount of potential energy stored in tidal waves, and of the successful experience of the few existing plants. The world’s second largest tidal range occurs in the UK but at the moment tidal installations in this country are limited to a few prototypes. More recently, there has been a renewed interest in harnessing tidal energy in the UK, and a few tidal lagoon projects have been evaluated by the UK government. This paper provides an overview of the historical and current developments of tidal plants, a description of operation of tidal lagoons, challenges and opportunities for their integration within the UK energy systems and solutions to improve the dispatchability of tidal energy. The concepts described in the paper are applied to a tidal project proposed for South Wales.

  18. 长江口北槽丁坝坝田区潮流及污染物迁移扩散特征%Tidal current and pollutant diffusion characteristics in spur dike field of North Passage in Yangtze Estuary

    Institute of Scientific and Technical Information of China (English)

    路川藤; 黄华聪; 钱明霞

    2016-01-01

    In order to study the flow structure in a spur dike field of the North Passage in the Yangtze Estuary, a two⁃dimensional large⁃scale coupling model for tidal current and water quality was established using the finite volume method ( FVM ) and unstructured grids. Based on model verification, the flow structure and pollutant diffusion in the spur dike field of the North Passage during flood tides and ebb tides were studied. The following conclusions are drawn: the high tide level in the north spur dike field in the middle⁃upper reach of the North Passage is significantly higher than that in the main channel, while the high tide level in the lower reach of the North Passage is close to that in the main channel;the high tide level in the south spur dike field is mostly higher than that in the main channel, and the low tide levels in the north and south spur dike fields are close to that in the main channel;the rate of pollutant diffusion in the south spur dike field is higher than that in the north spur dike field , with a relatively high rate of diffusion during ebb tides;the rate of pollutant diffusion in the spur dike field is higher during spring tides than during neap tides, with a relatively high rate of pollutant diffusion outside the spur dike field in contrast to that inside the spur dike field; after release of pollutants in the spur dike field, the pollutants are transported within the spur dike field and the main channel following flood tides and ebb tides, and lesser amounts enter into the waterway in a short period.%为研究长江口深水航道北槽坝田水流结构,基于非结构网格FVM法,建立了长江口大范围二维潮流水质耦合数学模型,在数学模型验证良好的基础上,对北槽涨落潮水流结构及坝田污染物扩散进行了研究。结果表明,北槽中上段北坝田高潮位明显高于主槽,北槽下段,高潮位与主槽相近;南坝田高潮位大都高于主槽,南北坝田低潮位

  19. Paleoecological Perspectives on Tidal Marsh Degradation at Elkhorn Slough, California

    Science.gov (United States)

    Watson, E. B.; Wasson, K.; Woolfolk, A.; van Dyke, E.

    2007-05-01

    Elkhorn Slough is the second largest area of estuarine tidal wetlands in California, and one of the first U.S. estuarine sanctuaries. Region-wide, 90% of historic tidal wetlands have been lost or restricted from tidal flow due to diking for agricultural use, salt pond construction, and development. However, wetland loss at Elkhorn Slough is currently being driven largely by tidal erosion, and the subsequent expansion of tidal channels and shoreline recession. This study reports on the use of paleoecological analyses to support and inform current restoration and conservation activities at Elkhorn Slough. Analyses of three sediment cores for fossil pollen, organic content, accretion rates, and the removal and stratigraphic description of twelve additional cores have established the timing of marsh establishment, current and prehistoric estuarine salinity, wetland plant abundance and distributions, and the relative contributions of mineral and organic sediment to wetland sediment accumulation. By understanding prehistoric processes and conditions and past variability more thoroughly, managers will be able to evaluate conservation, restoration, and management alternatives in a more informed fashion.

  20. Tidal and sub-tidal sea level variability at the northern shelf of the Brazilian Northeast Region

    Directory of Open Access Journals (Sweden)

    FELIPE F. FROTA

    2016-01-01

    Full Text Available ABSTRACT A characterization of the sea level variability at tidal and sub-tidal frequencies at the northern shore of the Brazilian Northeast shelf for the period 2009-2011 is presented. The sea level data used was obtained from the Permanent Geodetic Tide Network from the Brazilian Institute of Geography and Statistics for the Fortaleza gauge station. Local wind data was also used to assess its effects on the low-frequency sea level variability. The variability of the sea level was investigated by classical harmonic analysis and by morphology assessment over the tidal signal. The low frequencies were obtained by low-pass filtering. The tidal range oscillated with the highest value of 3.3 m during the equinox and the lowest value of 0.7 m during the solstice. Differences between the spring and neap tides were as high as 1 m. A total of 59 tidal constituents were obtained from harmonic analysis, and the regional tide was classified as semi-diurnal pure with a form number of 0.11. An assessment of the monthly variability of the main tidal constituents (M2, S2, N2, O1, and K1 indicated that the main semi-diurnal solar S2 presented the highest variability, ranging from 0.21 to 0.41 m; it was the main element altering the form number through the years. The low frequency sea-level variability is negligible, although there is a persistent signal with an energy peak in the 10-15 day period, and it cannot be explained by the effects of local winds.

  1. Tidal disruption event demographics

    Science.gov (United States)

    Kochanek, C. S.

    2016-09-01

    We survey the properties of stars destroyed in tidal disruption events (TDEs) as a function of black hole (BH) mass, stellar mass and evolutionary state, star formation history and redshift. For M_{BH} ≲ 10^7 M_{⊙}, the typical TDE is due to a M* ˜ 0.3 M⊙ M-dwarf, although the mass function is relatively flat for M_{ast } ≲ M_{⊙}. The contribution from older main-sequence stars and sub-giants is small but not negligible. From MBH ≃ 107.5-108.5 M⊙, the balance rapidly shifts to higher mass stars and a larger contribution from evolved stars, and is ultimately dominated by evolved stars at higher BH masses. The star formation history has little effect until the rates are dominated by evolved stars. TDE rates should decline very rapidly towards higher redshifts. The volumetric rate of TDEs is very high because the BH mass function diverges for low masses. However, any emission mechanism which is largely Eddington-limited for low BH masses suppresses this divergence in any observed sample and leads to TDE samples dominated by MBH ≃ 106.0-107.5 M⊙ BHs with roughly Eddington peak accretion rates. The typical fall-back time is relatively long, with 16 per cent having tfb plausible if tfb has any relation to the transient rise time. For almost any BH mass function, systematic searches for fainter, faster time-scale TDEs in smaller galaxies, and longer time-scale TDEs in more massive galaxies are likely to be rewarded.

  2. Tidal dunes versus tidal bars: The sedimentological and architectural characteristics of compound dunes in a tidal seaway, the lower Baronia Sandstone (Lower Eocene), Ager Basin, Spain

    Science.gov (United States)

    Olariu, Cornel; Steel, Ronald J.; Dalrymple, Robert W.; Gingras, Murray K.

    2012-11-01

    The Lower Eocene Baronia Formation in the Ager Basin is interpreted as a series of stacked compound dunes confined within a tectonically generated embayment or tidal seaway. This differs from the previous interpretation of lower Baronia sand bodies as tidal bars in the front of a delta. The key architectural building block of the succession, the deposit of a single compound dune, forms a 1-3 m-thick, upward coarsening succession that begins with highly bioturbated, muddy, very fine to fine grained sandstone that contains an open-marine Cruziana ichnofacies. This is overlain gradationally by ripple-laminated sandstone that is commonly bioturbated and contains mud drapes. The succession is capped by fine- to coarse-grained sandstones that contain both planar and trough cross-strata with unidirectional or bi-directional paleocurrent directions and occasional thin mud drapes on the foresets. The base of a compound dune is gradational where it migrated over muddy sandstone deposited between adjacent dunes, but is sharp and erosional where it migrated over the stoss side of a previous compound dune. The cross strata that formed by simple superimposed dunes dip in the same direction as the inclined master bedding planes within the compound dune, forming a forward-accretion architecture. This configuration is the fundamental reason why these sandbodies are interpreted as compound tidal dunes rather than as tidal bars, which, in contrast, generate lateral-accretion architecture. In the Baronia, fields of compound dunes generated tabular sandbodies 100s to 1000s of meters in extent parallel to the paleocurrent direction and up to 6 m thick that alternate vertically with highly bioturbated muddy sandstones (up to 10 m thick) that represent the low-energy fringes of the dune fields or periods of high sea level when current speeds decreased. Each cross-stratified sandstone sheet (compound-dune complexes) contains overlapping lenticular "shingles" formed by individual compound

  3. Tidal Dissipation and Obliquity Evolution in Hot Jupiter Systems

    CERN Document Server

    Valsecchi, Francesca

    2014-01-01

    Two formation scenarios have been proposed to explain the tight orbits of hot Jupiters. These giant planets could be formed in low-obliquity orbits via disk migration or in high-obliquity orbits via high-eccentricity migration, where gravitational interactions with a companion are at play, together with tidal dissipation. Here we target the observed misaligned hot Jupiter systems to investigate whether their current properties are consistent with high-eccentricity migration. Specifically, we study whether tidal dissipation in the star can be responsible for the observed distribution of misalignments and orbital separations. Improving on previous studies, we use detailed models for the stellar component, thus accounting for how convection (and thus tidal dissipation) depends on the host star properties. We find that the currently observed degree of misalignment increases as the amount of surface convection in the host star decreases. This trend supports the hypothesis that tides are the mechanism shaping the o...

  4. Shelf waves with diurnal tidal frequency at the Greenland shelf edge

    NARCIS (Netherlands)

    Lam, F.P.A

    1999-01-01

    Tidal analysis was carried out on current measurements at a 'cross-shelf' transect off Greenland at 71°N. The diurnal tides manifest themselves mainly as a barotropic continental shelf wave, travelling southward along the shelf slope. This follows from the amplitude distribution of the diurnal tidal

  5. Atmospheric dynamics of tidally synchronized extrasolar planets.

    Science.gov (United States)

    Cho, James Y-K

    2008-12-13

    Tidally synchronized planets present a new opportunity for enriching our understanding of atmospheric dynamics on planets. Subject to an unusual forcing arrangement (steady irradiation on the same side of the planet throughout its orbit), the dynamics on these planets may be unlike that on any of the Solar System planets. Characterizing the flow pattern and temperature distribution on the extrasolar planets is necessary for reliable interpretation of data currently being collected, as well as for guiding future observations. In this paper, several fundamental concepts from atmospheric dynamics, likely to be central for characterization, are discussed. Theoretical issues that need to be addressed in the near future are also highlighted.

  6. On the tilting of protostellar disks by resonant tidal effects

    CERN Document Server

    Lubow, S H

    2000-01-01

    We consider the dynamics of a protostellar disk surrounding a star in acircular-orbit binary system. Our aim is to determine whether, if the disk isinitially tilted with respect to the plane of the binary orbit, the inclinationof the system will increase or decrease with time. The problem is formulated inthe binary frame in which the tidal potential of the companion star is static.We consider a steady, flat disk that is aligned with the binary plane andinvestigate its linear stability with respect to tilting or warpingperturbations. The dynamics is controlled by the competing effects of the m=0and m=2 azimuthal Fourier components of the tidal potential. In the presence ofdissipation, the m=0 component causes alignment of the system, while the m=2component has the opposite tendency. We find that disks that are sufficientlylarge, in particular those that extend to their tidal truncation radii, aregenerally stable and will therefore tend to alignment with the binary plane ona time-scale comparable to that found ...

  7. Detecting areal changes in tidal flats after sea dike construction using Landsat-TM images

    Indian Academy of Sciences (India)

    Moon Seong Kang; Sang June Im; Tae Il Jang; Seung Woo Park; Sang Min Kim

    2007-12-01

    The main objective of this study was to estimate changes in the area of tidal flats that occurred after sea dike construction on the western coast of South Korea using Landsat-TM images. Applying the ISODATA method of unsupervised classification for Landsat-TM images, the tidal flats were identified, and the resulting areas were quantified for each image. The area of tidal flats from a topographic map published in one year differs significantly from that shown in another, which appears to be attributable to the tide levels at the time of aerial photography. During the study period, the area of tidal flats, as estimated from Landsat-TM images, increased by 4.57 km2 per year in the study areas. The tidal flats in the inner sea of Chunsu Harbor area increased by 200m2 per zone, while the accumulation for a number of inner sea areas within Asan Harbor area occurred at over 50m2 per zone. The results of this research may serve as the basis of an environmentallyfriendly development plan for tidal flats.

  8. Characteristics of electricity generation and biodegradation in tidal river sludge-used microbial fuel cells.

    Science.gov (United States)

    Touch, Narong; Hibino, Tadashi; Nagatsu, Yoshiyuki; Tachiuchi, Kouhei

    2014-04-01

    The electricity generation behavior of microbial fuel cell (MFC) using the sludge collected from the riverbank of a tidal river, and the biodegradation of the sludge by the electricity generation are evaluated. Although the maximum current density (150-300 mA/m(2)) was higher than that of MFC using freshwater sediment (30 mA/m(2)), the output current was greatly restricted by the mass transfer limitation. However, our results also indicate that placing the anode in different locations in the sludge could reduce the mass transfer limitation. After approximately 3 months, the removal efficiency of organic carbon was approximately 10%, demonstrated that MFC could also enhance the biodegradation of the sludge by nearly 10-fold comparing with the natural biodegradation. We also found that the biodegradation could be identified by the behavior of oxygen consumption of the sludge. Importantly, the oxygen consumption of the sludge became higher along with the electricity generation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Main: 1M2Q [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1M2Q トウモロコシ Corn Zea mays L. Casein Kinase Ii, Alpha Chain Name=Ack2; Zea Mays Mole...LVGRHSRKPWLKFMNADNQHLVSPEAIDFLDKLLRYDHQERLTALEAMTHPYFQQVRAAENSRTRA corn_1M2Q.jpg ...

  10. Main: 1M2P [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1M2P トウモロコシ Corn Zea mays L. Casein Kinase Ii, Alpha Chain Name=Ack2; Zea Mays Mole...LVGRHSRKPWLKFMNADNQHLVSPEAIDFLDKLLRYDHQERLTALEAMTHPYFQQVRAAENSRTRA corn_1M2P.jpg ...

  11. Main: 1M2R [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1M2R トウモロコシ Corn Zea mays L. Casein Kinase Ii, Alpha Chain Name=Ack2; Zea Mays Mole...ELLVDLQDYDYSLDMWSLGCMFAGMIFRKEPFFYGHDNHDQLVKIAKVLGTDGLNVYLNKYRIELDPQLEALVGRHSRKPWLKFMNADNQHLVSPEAIDFLDKLLRYDHQERLTALEAMTHPYFQQVRAAENSRTRA corn_1M2R.jpg ...

  12. Can Tidal Perturbations Associated with Sea Level Variations in the Western Pacific Ocean Be Used to Understand Future Effects of Tidal Evolution?

    Science.gov (United States)

    Devlin, A. T.; Zaron, E. D.; Jay, D. A.; Talke, S. A.

    2014-12-01

    This study examines connections between mean sea level (MSL) variability and diurnal and semidiurnal tidal constituent variations in the western tropical Pacific Ocean, a region showing anomalous MSL rise over the last 20 years and strong inter-annual variability. MSL fluctuations are found to be correlated to tidal amplitude and phase fluctuations at 13 of 17 open-ocean and 7 of 9 continental shelf tide gauges, after de-trending the time series. Twenty statistically significant tidal anomaly trends (TATs) in both phase and amplitude are found for the two largest tidal constituents, K1 (diurnal) and M2 (semidiurnal). Smaller constituents (O1 and S2) show significant trends at nearly half of all gauges. MSL fluctuations are concurrent with shifts in tidal amplitudes and phases, and both positive and negative relations are observed. Changing overtides suggest TATs are influenced by changing shallow water friction over the equatorial Western Pacific and the eastern coast of Australia (especially near the Great Barrier Reef). At stations around the Solomon Islands, a strong connection is observed between semidiurnal TATs and changes in thermocline depth, overtide generation, and the El Niño Southern Oscillation (ENSO). TATs for O1, K1, and M2 are related to each other in a manner that is consistent with resonant triad interactions. Since the response of tides to MSL variability is spatially complex and frequency dependent; short-term responses may not predict long-term behavior.

  13. 基于改进差分进化算法的潮流发电机组微观选址%Tidal Current Turbines Micrositing Based on Improved Differential Evolution Algorithm

    Institute of Scientific and Technical Information of China (English)

    王丛佼; 王锡淮; 陈国初; 陈建民; 陈晶

    2016-01-01

    针对潮流能发电机组布局依赖经验法、缺乏自主优化而导致微观选址难度大的问题,提出了一种基于差分进化算法并结合流场仿真模型的微观选址优化方法。通过对流场的有限元仿真,获取选址区域在原始状态下的流速分布;在充分考虑地形、潮汐和尾流效应等因素的前提下,以仿真结果为依据,以潮流发电机组群输出功率最大为优化目标,以机组间距及水深限制为约束,建立微观选址优化的数学模型;采用差分进化算法进行模型求解,同时为更利于最优解的搜索,提出了对其变异算子及参数设置的改进策略。以龟山水道为例进行微观选址优化计算,验证了所提模型的准确性与算法的高效性。%A micrositing method based on differential evolution algorithm combined with flow field simulation model is proposedfor solving the problems that tidal generator layout depends on experience without optimization technology. This method firstly employsthe finite element simulation to obtain the original flow velocity distribution. Then a mathematical model based on the simulation results is built in full consideration of topography,tide,and wake effect. The objective function is the maximization of the whole tidal turbines’power outputand the free variables are the turbines’coordinates which are subject to the minimum distance conditions and the depth conditions. In order to solve this model,an improved differential evolution algorithmis proposed, in whichthe adaptive mutation operator and parameters increase the global search ability. The micrositing of tidal turbines is performed on the Guishan waterway. Then the optimized results demonstrate the accurateness of the proposed model and the effectiveness of the solving algorithm.

  14. Tidal disruption of inviscid protoplanets

    Science.gov (United States)

    Boss, Alan P.; Cameron, A. G. W.; Benz, W.

    1991-01-01

    Roche showed that equilibrium is impossible for a small fluid body synchronously orbiting a primary within a critical radius now termed the Roche limit. Tidal disruption of orbitally unbound bodies is a potentially important process for planetary formation through collisional accumulation, because the area of the Roche limit is considerably larger then the physical cross section of a protoplanet. Several previous studies were made of dynamical tidal disruption and different models of disruption were proposed. Because of the limitation of these analytical models, we have used a smoothed particle hydrodynamics (SPH) code to model the tidal disruption process. The code is basically the same as the one used to model giant impacts; we simply choose impact parameters large enough to avoid collisions. The primary and secondary both have iron cores and silicate mantles, and are initially isothermal at a molten temperature. The conclusions based on the analytical and numerical models are summarized.

  15. Tidally induced lateral dispersion of the Storfjorden overflow plume

    Directory of Open Access Journals (Sweden)

    F. Wobus

    2013-10-01

    Full Text Available We investigate the flow of brine-enriched shelf water from Storfjorden (Svalbard into Fram Strait and onto the western Svalbard Shelf using a regional set-up of NEMO-SHELF, a 3-D numerical ocean circulation model. The model is set up with realistic bathymetry, atmospheric forcing, open boundary conditions and tides. The model has 3 km horizontal resolution and 50 vertical levels in the sh-coordinate system which is specially designed to resolve bottom boundary layer processes. In a series of modelling experiments we focus on the influence of tides on the propagation of the dense water plume by comparing results from tidal and non-tidal model runs. Comparisons of non-tidal to tidal simulations reveal a hotspot of tidally induced horizontal diffusion leading to the lateral dispersion of the plume at the southernmost headland of Spitsbergen which is in close proximity to the plume path. As a result the lighter fractions in the diluted upper layer of the plume are drawn into the shallow coastal current that carries Storfjorden water onto the western Svalbard Shelf, while the dense bottom layer continues to sink down the slope. This bifurcation of the plume into a diluted shelf branch and a dense downslope branch is enhanced by tidally induced shear dispersion at the headland. Tidal effects at the headland are shown to cause a net reduction in the downslope flux of Storfjorden water into the deep Fram Strait. This finding contrasts previous results from observations of a dense plume on a different shelf without abrupt topography.

  16. Linking channel hydrology with riparian wetland accretion in tidal rivers

    Science.gov (United States)

    Ensign, Scott H.; Noe, Gregory B.; Hupp, Cliff R.

    2014-01-01

    hydrologic processes by which tide affects river channel and riparian morphology within the tidal freshwater zone are poorly understood yet are fundamental to predicting the fate of coastal rivers and wetlands as sea level rises. We investigated patterns of sediment accretion in riparian wetlands along the nontidal through oligohaline portion of two coastal plain rivers in Maryland, U.S., and how flow velocity, water level, and suspended sediment concentration (SSC) in the channel may have contributed to those patterns. Sediment accretion was measured over a 1 year period using artificial marker horizons, channel hydrology was measured over a 1 month period using acoustic Doppler current profilers, and SSC was predicted from acoustic backscatter. Riparian sediment accretion was lowest at the nontidal sites (mean and standard deviation = 8 ± 8 mm yr-1), highest at the upstream tidal freshwater forested wetlands (TFFW) (33 ± 28 mm yr-1), low at the midstream TFFW (12 ± 9 mm yr-1), and high at the oligohaline (fresh-to-brackish) marshes (19 ± 8 mm yr-1). Channel maximum flood and ebb velocity was twofold faster at the oligohaline than tidal freshwater zone on both tidal rivers, corresponding with the differences in in-channel SSC: The oligohaline zone's SSC was more than double the tidal freshwater zone's and was greater than historical SSC at the nontidal gages. The tidal wave characteristics differed between rivers, leading to significantly greater in-channel SSC during floodplain inundation in the weakly convergent than the strongly convergent tidal river. High sediment accretion at the upstream TFFW was likely due to high river discharge following a hurricane.

  17. Tidal Hydrodynamics in the Lower Columbia River Estuary through Depth Averaged Adaptive Hydraulics Modeling

    Directory of Open Access Journals (Sweden)

    Gaurav Savant

    2014-01-01

    Full Text Available The adaptive hydraulics (AdH numerical code was applied to study tidal propagation in the Lower Columbia River (LCR estuary. The results demonstrate the readiness of this AdH model towards the further study of hydrodynamics in the LCR. The AdH model accurately replicated behavior of the tide as it propagated upstream into the LCR system. Results show that the MSf tidal component and the M4 overtidal component are generated in the middle LCR and contain a substantial amount of tidal energy. An analysis was performed to determine the causes of MSf tide amplification, and it was found that approximately 80% of the amplification occurs due to nonlinear interaction between the M2 and the S2 tidal components.

  18. The outer envelopes of globular clusters - I. NGC 7089 (M2)

    Science.gov (United States)

    Kuzma, P. B.; Da Costa, G. S.; Mackey, A. D.; Roderick, T. A.

    2016-10-01

    We present the results of a wide-field imaging survey of the periphery of the Milky Way globular cluster NGC 7089 (M2). Data were obtained with MegaCam on the Magellan Clay Telescope and the Dark Energy Camera on the Blanco Telescope. We find that M2 is embedded in a diffuse stellar envelope extending to a radial distance of at least ˜60 arcmin (˜210 pc) - five times the nominal tidal radius of the cluster. The envelope appears nearly circular in shape, has a radial density decline well described by a power law of index γ = -2.2 ± 0.2, and contains approximately 1.6 per cent of the luminosity of the entire system. While the origin of the envelope cannot be robustly identified using the presently available data, the fact that M2 also hosts stellar populations exhibiting a broad dispersion in the abundances of both iron and a variety of neutron capture elements suggests that this object might plausibly constitute the stripped nucleus of a dwarf galaxy that was long ago accreted and destroyed by the Milky Way.

  19. The Outer Envelopes of Globular Clusters. I. NGC 7089 (M2)

    CERN Document Server

    Kuzma, P B; Mackey, A D; Roderick, T A

    2016-01-01

    We present the results of a wide-field imaging survey of the periphery of the Milky Way globular cluster NGC 7089 (M2). Data were obtained with MegaCam on the Magellan Clay Telescope, and the Dark Energy Camera on the Blanco Telescope. We find that M2 is embedded in a diffuse stellar envelope extending to a radial distance of at least $\\sim 60^{\\prime}$ ($\\sim 210$ pc) -- five times the nominal tidal radius of the cluster. The envelope appears nearly circular in shape, has a radial density decline well described by a power law of index $\\gamma = -2.2 \\pm 0.2$, and contains approximately $1.6\\%$ of the luminosity of the entire system. While the origin of the envelope cannot be robustly identified using the presently available data, the fact that M2 also hosts stellar populations exhibiting a broad dispersion in the abundances of both iron and a variety of neutron capture elements suggests that this object might plausibly constitute the stripped nucleus of a dwarf Galaxy that was long ago accreted and destroyed...

  20. On the dynamics of compound bedforms in high-energy tidal channels: field observations in the German Bight and the Danish Wadden Sea

    DEFF Research Database (Denmark)

    Ernstsen, Verner; Christian, Winter; Becker, Marius

    2010-01-01

    Tidal inlets are a common feature along much of the world’s coastlines. They interrupt the alongshore continuity of shoreline processes, and by being exposed to both wave and current forcing, tidal inlets belong to the morphologically most dynamic and complex coastal systems on Earth. The tidal...

  1. Water Current Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Tidal, river and ocean current observations collected by the U.S. Coast and Geodetic Survey. Period of record is late 1800s to mid-1980s.

  2. Towards Selective Tidal-Stream Transport for Lagrangian profilers

    DEFF Research Database (Denmark)

    Jouffroy, Jerome; Zhou, Qiuyang; Zielinski, Oliver

    2011-01-01

    select and use tidal currents so that a profiler can autonomously reach a desired destination. After presenting the profiler and possible modifications for a coastal environment, we introduce simple mathematical models for the profiler and its environment. We then present a feedback controller that...

  3. Simulating tidal turbines with mesh optimisation and RANS turbulence models

    NARCIS (Netherlands)

    Abolghasemi, A.; Piggott, M.D.; Spinneken, J.; Vire, A.; Cotter, C.J.

    2015-01-01

    A versatile numerical model for the simulation of flow past horizontal axis tidal turbines has been developed. Currently most large-scale marine models employed to study marine energy use the shallow water equations and therefore can fail to account for important turbulent physics. The model present

  4. Identification of the Opportunities for Future Development of Tidal Energy

    Directory of Open Access Journals (Sweden)

    Navid Bozorgan

    2015-09-01

    Full Text Available An overview of status of development of tidal energy is given in this article. To reduce the dependance on fossil fuel and imported energy resources, the need for ocean energy is a global demand in developing countries. The ability to directly extract from the world’s oceans may be in the form of mechanical energy from waves, tides, or currents, or in the form of thermal energy from the sun’s heat. This paper identifies the opportunities for future development of tidal energy.

  5. Research on Local Scour at Bridge Pier under Tidal Action

    Directory of Open Access Journals (Sweden)

    Wang Jianping

    2015-01-01

    Full Text Available Through the local scour test at bridge pier under tidal action in a long time series, this paper observes the growing trend of the deepest point of local scour at bridge pier under tidal conditions with different characteristic parameters, analyzes the impact of repeat sediment erosion and deposition in the scouring pit caused by reversing current on the development process of the scouring pit, and clarifies the relation between the tide and local scouring depth at bridge pier under steady flow conditions, so as to provide a scientific basis for bridge design and safe operation of estuary and harbor areas.

  6. Long-Term Morphological Modeling of Barrier Island Tidal Inlets

    Directory of Open Access Journals (Sweden)

    Richard Styles

    2016-09-01

    Full Text Available The primary focus of this study is to apply a two-dimensional (2-D coupled flow-wave-sediment modeling system to simulate the development and growth of idealized barrier island tidal inlets. The idealized systems are drawn from nine U.S. coastal inlets representing Pacific Coast, Gulf Coast and Atlantic Coast geographical and climatological environments. A morphological factor is used to effectively model 100 years of inlet evolution and the resulting morphological state is gauged in terms of the driving hydrodynamic processes. Overall, the model performs within the range of established theoretically predicted inlet cross-sectional area. The model compares favorably to theoretical models of maximum inlet currents, which serve as a measure of inlet stability. Major morphological differences are linked to inlet geometry and tidal forcing. Narrower inlets develop channels that are more aligned with the inlet axis while wider inlets develop channels that appear as immature braided channel networks similar to tidal flats in regions with abundant sediment supply. Ebb shoals with strong tidal forcing extend further from shore and spread laterally, promoting multi-lobe development bisected by ebb shoal channels. Ebb shoals with moderate tidal forcing form crescent bars bracketing a single shore-normal channel. Longshore transport contributes to ebb shoal asymmetry and provides bed material to help maintain the sediment balance in the bay.

  7. Relativistic theory of tidal Love numbers

    OpenAIRE

    Binnington, Taylor; Poisson, Eric

    2009-01-01

    In Newtonian gravitational theory, a tidal Love number relates the mass multipole moment created by tidal forces on a spherical body to the applied tidal field. The Love number is dimensionless, and it encodes information about the body's internal structure. We present a relativistic theory of Love numbers, which applies to compact bodies with strong internal gravities; the theory extends and completes a recent work by Flanagan and Hinderer, which revealed that the tidal Love number of a neut...

  8. Tidal Models In A New Era of Satellite Gravimetry

    Science.gov (United States)

    Ray, Richard D.; Rowlings, David D.; Edbert, G. D.; Chao, Benjamin F. (Technical Monitor)

    2002-01-01

    The high precision gravity measurements to be made by recently launched (and recently approved) satellites place new demands on models of Earth, atmospheric, and oceanic tides. The latter is the most problematic. The ocean tides induce variations in the Earth's geoid by amounts that far exceed the new satellite sensitivities, and tidal models must be used to correct for this. Two methods are used here to determine the standard errors in current ocean tide models. At long wavelengths these errors exceed the sensitivity of the GRACE mission. Tidal errors will not prevent the new satellite missions from improving our knowledge of the geopotential by orders of magnitude, but the errors may well contaminate GRACE estimates of temporal variations in gravity. Solar tides are especially problematic because of their long alias periods. The satellite data may be used to improve tidal models once a sufficiently long time series is obtained. Improvements in the long-wavelength components of lunar tides are especially promising.

  9. Tidal River Management (TRM and Tidal Basin Management (TBM: A case study on Bangladesh

    Directory of Open Access Journals (Sweden)

    Talchabhadel Rocky

    2016-01-01

    Full Text Available Bangladesh is the biggest delta of the world. Construction of numbers of polders is one of the flood resilient approach. But the presence of coastal polders de-linked the flood plain. The siltation in river causes riverbeds to become higher than the adjacent crop lands, and vast area under the polders became permanently water logged rendering large tract of land uncultivable. The current practice is temporarily de-poldering by cutting embankment. This is a natural water management process with very little human interventions but it needs strong participation and consensus with a great deal of sacrifice by the stakeholders for a specific period (3 to 5 years or even more[1]. An attempt has been made to study the phenomena of tidal basin management reviewing some secondary data and processes involved in successfully operated tidal basins of Bangladesh. And preliminary laboratory experiments are carried out to precisely look into the suspended sediment transport. With varying outflow discharge and sediment supply, the transport processes are investigated. 3D sediment transport model developed using openFOAM has good agreement with experimental result and can be used to better understand effectiveness of tidal basin management.

  10. Characteristic and paleoenvironmental evolution of subaerial tidal sand body in Subei coastal plain

    Institute of Scientific and Technical Information of China (English)

    李从先; 张家强; 杨守业; 范代读

    1999-01-01

    The subaerial tidal sand area in the northern Jiangsu Province (Subei), stretching from Dongtai towards east with a fan shape, is an early developing stage of radial sand ridges distributed in the South Yellow Sea. Since 5 000—6 000 a BP, after the Holoeene transgression maximum in the northern Jiangsu Province, subaqueous tidal sand bodies were exposed and changed into land gradually. The environmental magnetism analysis shows that subaerial tidal sand strata are formed by the convergent-divergent palco-tidal current field. The sediment source of tidal sand strata came early from the Changjiang River and late from the Yellow River. Sea floor erosion by tidal currents also served as an important sand source. Drilling cores and ground-penetrating profile show that there exists no probability of sand supplying directly by a large river through the apical area of tidal sand ridges either on land or in the sea. Fluvial deposits supplied the tidal sand bodies by alongshore transportation, which corresponds

  11. Wound administration of M2-polarized macrophages does not improve murine cutaneous healing responses.

    Science.gov (United States)

    Jetten, Nadine; Roumans, Nadia; Gijbels, Marion J; Romano, Andrea; Post, Mark J; de Winther, Menno P J; van der Hulst, Rene R W J; Xanthoulea, Sofia

    2014-01-01

    Macrophages play a crucial role in all stages of cutaneous wound healing responses and dysregulation of macrophage function can result in derailed wound repair. The phenotype of macrophages is influenced by the wound microenvironment and evolves during healing from a more pro-inflammatory (M1) profile in early stages, to a less inflammatory pro-healing (M2) phenotype in later stages of repair. The aim of the current study was to investigate the potential of exogenous administration of M2 macrophages to promote wound healing in an experimental mouse model of cutaneous injury. Bone marrow derived macrophages were stimulated in-vitro with IL-4 or IL-10 to obtain two different subsets of M2-polarized cells, M2a or M2c respectively. Polarized macrophages were injected into full-thickness excisional skin wounds of either C57BL/6 or diabetic db/db mice. Control groups were injected with non-polarized (M0) macrophages or saline. Our data indicate that despite M2 macrophages exhibit an anti-inflammatory phenotype in-vitro, they do not improve wound closure in wild type mice while they delay healing in diabetic mice. Examination of wounds on day 15 post-injury indicated delayed re-epithelialization and persistence of neutrophils in M2 macrophage treated diabetic wounds. Therefore, topical application of ex-vivo generated M2 macrophages is not beneficial and contraindicated for cell therapy of skin wounds.

  12. Tidal impacts on the subtidal flow division at the main bifurcation in the Yangtze River Delta

    Science.gov (United States)

    Zhang, Wei; Feng, Haochuan; Hoitink, A. J. F.; Zhu, Yuliang; Gong, Fei; Zheng, Jinhai

    2017-09-01

    ,000 m3s-1. This effect on the flow distribution can even overwhelm the effects induced by river discharge based on geometry only, when the flow discharge is lowest. Furthermore, the fortnightly tidal cycle plays an important role in enhancing the inequality of the subtidal flow division caused by the M2 tidal component solely at the tidal bifurcation in the Yangtze River Delta during low flow.

  13. Energy storage inherent in large tidal turbine farms.

    Science.gov (United States)

    Vennell, Ross; Adcock, Thomas A A

    2014-06-08

    While wind farms have no inherent storage to supply power in calm conditions, this paper demonstrates that large tidal turbine farms in channels have short-term energy storage. This storage lies in the inertia of the oscillating flow and can be used to exceed the previously published upper limit for power production by currents in a tidal channel, while simultaneously maintaining stronger currents. Inertial storage exploits the ability of large farms to manipulate the phase of the oscillating currents by varying the farm's drag coefficient. This work shows that by optimizing how a large farm's drag coefficient varies during the tidal cycle it is possible to have some flexibility about when power is produced. This flexibility can be used in many ways, e.g. producing more power, or to better meet short predictable peaks in demand. This flexibility also allows trading total power production off against meeting peak demand, or mitigating the flow speed reduction owing to power extraction. The effectiveness of inertial storage is governed by the frictional time scale relative to either the duration of a half tidal cycle or the duration of a peak in power demand, thus has greater benefits in larger channels.

  14. Towards Horizontal Architecture for Autonomic M2M Service Networks

    Directory of Open Access Journals (Sweden)

    Juhani Latvakoski

    2014-05-01

    Full Text Available Today, increasing number of industrial application cases rely on the Machine to Machine (M2M services exposed from physical devices. Such M2M services enable interaction of physical world with the core processes of company information systems. However, there are grand challenges related to complexity and “vertical silos” limiting the M2M market scale and interoperability. It is here expected that horizontal approach for the system architecture is required for solving these challenges. Therefore, a set of architectural principles and key enablers for the horizontal architecture have been specified in this work. A selected set of key enablers called as autonomic M2M manager, M2M service capabilities, M2M messaging system, M2M gateways towards energy constrained M2M asset devices and creation of trust to enable end-to-end security for M2M applications have been developed. The developed key enablers have been evaluated separately in different scenarios dealing with smart metering, car sharing and electric bike experiments. The evaluation results shows that the provided architectural principles, and developed key enablers establish a solid ground for future research and seem to enable communication between objects and applications, which are not initially been designed to communicate together. The aim as the next step in this research is to create a combined experimental system to evaluate the system interoperability and performance in a more detailed manner.

  15. Revisiting the Endocytosis of the M2 Muscarinic Acetylcholine Receptor

    OpenAIRE

    Wymke Ockenga; Ritva Tikkanen

    2015-01-01

    The agonist-induced endocytosis of the muscarinic acetylcholine receptor M2 is different from that of the other members of the muscarinic receptor family. The uptake of the M2 receptor involves the adapter proteins of the β-arrestin family and the small GTPase ADP-ribosylation factor 6. However, it has remained inconclusive if M2 endocytosis is dependent on clathrin or the large GTPase dynamin. We here show by means of knocking down the clathrin heavy chain that M2 uptake upon agonist stimul...

  16. Standing Crop and Primary Production of Benthic Microalgae on the Tidal Flats in Yueqing Bay

    Institute of Scientific and Technical Information of China (English)

    HAO Qiang; CAI Yuming; NING Xiuren; LIU Chenggang; PENG Xin; TANG Xuexi

    2011-01-01

    The standing stock and primary production of benthic microalgae on tidal flats were measured seasonally at 3 transects (Puqing, Dahengchuang and Puqi) in Yueqing Bay during 2002-2003. The results showed that the integral chlorophyll a (Chl a) concentration in tidal flat mud exhibited a seasonal variation with the order of magnitude: winter (14.0±4.2 mgm-2) > spring (13.±6.3 mgm-2) > autumn (7.7±5.9 mgm-2) > summer (4.6±3.2 mg m-2). The primary production showed an order of magnitude: spring (270.5±224.9 mgC m-2 d-1)>winter (238.7±225.5 rgC m-2 d-1)>autumn (214.1±56.2 mgC m-2 d-1)>summer (71.6±44.6 mgC m-2 d-1).Both chlorophyll a and primary production showed maximum values in the surface layer of sediment, and decreased rapidly with increasing depth due to sun light limitation. The results of variance analysis indicated that seasonal variation and tidal flat condition affected Chl a greatly, but had no significant effect on primary production. The annual primary production of benthic microalgae on tidal flats in Yueqing Bay was estimated at 16143 tons carbon, which is sufficient to support 1.02×l05 tons shellfish production. The environmental factors affecting chlorophyll and primary production on the tidal flats in Yueqing Bay were discussed. By comparing with other bays on China's coast, it was observed that Yueqing Bay is a region with high benthic microalgae standing crop and primary production, which may be related to the type of its sediment.

  17. Wound Administration of M2-Polarized Macrophages Does Not Improve Murine Cutaneous Healing Responses

    OpenAIRE

    Nadine Jetten; Nadia Roumans; Marion J. Gijbels; Andrea Romano; Post, Mark J.; de Winther, Menno P.J.; Van der Hulst, Rene R. W. J.; Sofia Xanthoulea

    2014-01-01

    Macrophages play a crucial role in all stages of cutaneous wound healing responses and dysregulation of macrophage function can result in derailed wound repair. The phenotype of macrophages is influenced by the wound microenvironment and evolves during healing from a more pro-inflammatory (M1) profile in early stages, to a less inflammatory pro-healing (M2) phenotype in later stages of repair. The aim of the current study was to investigate the potential of exogenous administration of M2 macr...

  18. Abundance, distribution, mobility and oligomeric state of M2 muscarinic acetylcholine receptors in live cardiac muscle

    OpenAIRE

    Nenasheva, Tatiana A.; Neary, Marianne; Gregory I. Mashanov; Birdsall, Nigel J.M.; Breckenridge, Ross A.; Molloy, Justin E.

    2013-01-01

    M2 muscarinic acetylcholine receptors modulate cardiac rhythm via regulation of the inward potassium current. To increase our understanding of M2 receptor physiology we used Total Internal Reflection Fluorescence Microscopy to visualize individual receptors at the plasma membrane of transformed CHOM2 cells, a cardiac cell line (HL-1), primary cardiomyocytes and tissue slices from pre- and post-natal mice. Receptor expression levels between individual cells in dissociated cardiomyocytes and he...

  19. General relativistic tidal heating for Moller pseudotensor

    CERN Document Server

    So, Lau Loi

    2015-01-01

    Thorne elucidated that the relativistic tidal heating is the same as the Newtonian theory. Moreover, Thorne also claimed that the tidal heating is independent of how one localizes gravitational energy and is unambiguously given by a certain formula. Purdue and Favata calculated the tidal heating for different classical pseudotensors including Moller and obtained the results all matched with the Newtonian perspective. After re-examined this Moller pseudotensor, we find that there does not exist any tidal heating value. Thus we claim that the relativistic tidal heating is pseudotensor independent under the condition that if the peusdotensor is a Freud typed superpotential.

  20. Maine Tidal Power Initiative: Environmental Impact Protocols For Tidal Power

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Michael Leroy [Univ. of Maine, Orono, ME; Zydlewski, Gayle Barbin [Univ. of Maine, Orono, ME; Xue, Huijie [Univ. of Maine, Orono, ME; Johnson, Teresa R. [Univ. of Maine, Orono, ME

    2014-02-02

    The Maine Tidal Power Initiative (MTPI), an interdisciplinary group of engineers, biologists, oceanographers, and social scientists, has been conducting research to evaluate tidal energy resources and better understand the potential effects and impacts of marine hydro-kinetic (MHK) development on the environment and local community. Project efforts include: 1) resource assessment, 2) development of initial device design parameters using scale model tests, 3) baseline environmental studies and monitoring, and 4) human and community responses. This work included in-situ measurement of the environmental and social response to the pre-commercial Turbine Generator Unit (TGU®) developed by Ocean Renewable Power Company (ORPC) as well as considering the path forward for smaller community scale projects.

  1. Tidal Friction: Darwin's Theory Re-Visited

    Science.gov (United States)

    Ferraz-Mello, Sylvio

    2009-05-01

    Our knowledge of tidal friction is even today directly founded on Darwin's theory. Many progresses from studies done in the past century deserve mention. To quote just a few, we may mention Love's theory on the elastic response of one body submitted to an external potential and the understanding of the role played by tides in generating heat in synchronous planetary satellites. We may also mention the many applications that leaded to the understanding of the evolution of systems with close-in satellites, the Earth-Moon system in the first place, and those concerning systems formed by close binary stars. However, notwithstanding the existence of some high-order formal theories, the essential of our knowledge is yet nowadays the one established by Darwin and crucial questions on the action of viscosity, for instance, remains unanswered. We still are strongly tied to Darwin's assumption that the tidal waves lag proportionally to frequency or, in some favorable cases (e.g. the Earth), that the lags are constants. We intend to critically review our current understanding of Darwin's theory and some of its limitations.

  2. Organic geochemistry in Pennsylvanian tidally influenced sediments from SW Indiana

    Science.gov (United States)

    Mastalerz, Maria; Kvale, E.P.; Stankiewicz, B.A.; Portle, K.

    1999-01-01

    Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana have been analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter (OM) preserved in an environment of daily interactions between marine and fresh waters. The concentration of organic matter (TOC) ranges from traces to 6.9% and sulfur rarely exceeds 0.1% in individual laminae. Angular vitrinite is the major organic matter type, accounting for 50-90% of total OM. The C/S ratio decreases as the verfical distance from the underlying coal increases. A decreasing C/S ratio coupled with decreases in Pr/Ph, Pr/n-C17, Ph/n-C18 ratios and a shift of carbon isotopic composition towards less negative values suggest an increase in salinity from freshwater in the mudflat tidal rhythmite facies close to the coal to brackish/marine in the sandflat tidal rhythmite facies further above from the coal. Within an interval spanning one year of deposition, TOC and S values show monthly variability. On a daily scale, TOC and S oscillations are still detectable but they are of lower magnitude than on a monthly scale. These small-scale variations are believed to reflect oscillations in water salinity related to tidal cycles.Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana have been analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter (OM) preserved in an environment of daily interactions between marine and fresh waters. The concentration of organic matter

  3. Determining Tidal Phase Differences from X-Band Radar Images

    Science.gov (United States)

    Newman, Kieran; Bell, Paul; Brown, Jennifer; Plater, Andrew

    2017-04-01

    Introduction Previous work by Bell et. al. (2016) has developed a method using X-band marine radar to measure intertidal bathymetry, using the waterline as a level over a spring-neap tidal cycle. This has been used in the Dee Estuary to give a good representation of the bathymetry in the area. However, there are some sources of inaccuracy in the method, as a uniform spatial tidal signal is assumed over the entire domain. Motivation The method used by Bell et. al. (2016) applies a spatially uniform tidal signal to the entire domain. This fails to account for fine-scale variations in water level and tidal phase. While methods are being developed to account for small-scale water level variations using high resolution modelling, a method to determine tidal phase variations directly from the radar intensity images could be advantageous operationally. Methods The tidal phase has been computed using two different methods, with hourly averaged images from 2008. In the first method, the cross-correlation between each raw pixel time series and a tidal signal at a number of lags is calculated, and the lag with the highest correlation to the pixel series is recorded. For the second method, the same method of correlation is used on signals generated by tracking movement of buoys, which show up strongly in the radar image as they move on their moorings with the tidal currents. There is a broad agreement between the two methods, but validation is needed to determine the relative accuracy. The phase has also been calculated using a Fourier decomposition, and agrees broadly with the above methods. Work also needs to be done to separate areas where the recorded phase is due to tidal current (mostly subtidal areas) or due to elevation (mostly the wetting/drying signal in intertidal areas), by classifying radar intensities by the phases and amplitudes of the tides. Filtering out signal variations due to wind strength and attenuation of the radar signal will also be applied. Validation

  4. Understanding the potential risk to marine mammals from collision with tidal turbines

    Energy Technology Data Exchange (ETDEWEB)

    Copping, Andrea; Grear, Molly; Jepsen, Richard; Chartrand, Chris; Gorton, Alicia

    2017-09-01

    The advent of the marine renewable energy industry has raised questions, particularly for tidal turbines, about potential threats to populations of marine mammals. This research examines the sequence of behavioral events that lead up to a potential collision of a marine mammal with a tidal turbine, within the context of the physical environment, the attributes of the tidal device, and the biomechanical properties of a marine mammal that may resist injury from a tidal blade collision. There are currently no data available to determine the risk of collision to a marine mammal, and obtaining those data would be extremely difficult. The surrogate data examined in this research (likelihood of a marine mammal being in close proximity to a tidal turbine, biomechanics of marine mammal tissues, and engineering models) provide insight into the interaction.

  5. Explicitly modelled deep-time tidal dissipation and its implication for Lunar history

    Science.gov (United States)

    Green, J. A. M.; Huber, M.; Waltham, D.; Buzan, J.; Wells, M.

    2017-03-01

    Dissipation of tidal energy causes the Moon to recede from the Earth. The currently measured rate of recession implies that the age of the Lunar orbit is 1500 My old, but the Moon is known to be 4500 My old. Consequently, it has been proposed that tidal energy dissipation was weaker in the Earth's past, but explicit numerical calculations are missing for such long time intervals. Here, for the first time, numerical tidal model simulations linked to climate model output are conducted for a range of paleogeographic configurations over the last 252 My. We find that the present is a poor guide to the past in terms of tidal dissipation: the total dissipation rates for most of the past 252 My were far below present levels. This allows us to quantify the reduced tidal dissipation rates over the most resent fraction of lunar history, and the lower dissipation allows refinement of orbitally-derived age models by inserting a complete additional precession cycle.

  6. Preliminary investigation of the potential of harnessing tidal energy for electricity generation in Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.S.; Seng, L.Y. [Tunku Abdul Rahman Univ. (Malaysia). Dept. of Electrical and Electronic Engineering

    2008-07-01

    Malaysia relies heavily on fossil fuels to meet its energy demands. However, Malaysia has started to explore the use of other forms of renewable energy such as solar energy, biofuels and tidal power. This paper focused on the potential of harnessing tidal energy in Malaysia for electricity production. There are several sites with great potential for tidal energy conversion, which could supplement the energy needs of Malaysia while reducing greenhouse gas emissions. Illustrations were included to show the amplitude of the main harmonic component of the tidal range around Malaysia. The main harmonic component found in the region has a maximum amplitude of 1.4 m, confirming the potential of tidal energy in Malaysia's Ocean. Since the tidal cycle is highly predictable, it has the potential to be a very reliable renewable energy source. Two main approaches are being researched internationally to harness the energy from tides, notably the barrage approach and the tidal stream approach. For the barrage approach, a physical barrier is created within the sea, and a sluice gate controls the flow of sea water. In the tidal stream approach, horizontal axis turbines are placed in the path of tidal currents to generate electricity, similar to the operation of wind turbines. This paper described the flow velocity, power output, availability of power supply and monthly yield of turbines using both the barrage and tidal stream approaches. The study showed that for the barrage approach, there are 6 sites in Malaysia where 14,970 kWH of energy can be generated monthly with a single turbine with a 5 m long blade. The tidal stream approach showed equally promising results at 2 sites. It was concluded that tidal energy is a promising form of renewable energy because of its cyclic, reliable and predictable nature and the vast energy contained within it. According to United Kingdom Department of Trade and Industry, 10 per cent of the United Kingdom's electricity needs could be

  7. The Demand for Divisia M2 in China%中国Divisa M2需求模型

    Institute of Scientific and Technical Information of China (English)

    潘红宇; 邓述慧

    2001-01-01

    本文计算中国Divisa M2指数并对其建立需求模型,研究发现实际Divisa M2 与实际产出存在协整关系,采用误差校正方法建立的动态需求模型具有良好的稳定性。%This paper computes the Divisa M2 in China and makes the money demand model for it. The research finds that the demand for real Divisa M2 is cointegrated with the real output, the short-run model is stable also.

  8. A Survey on M2M Service Networks

    Directory of Open Access Journals (Sweden)

    Juhani Latvakoski

    2014-11-01

    Full Text Available The number of industrial applications relying on the Machine to Machine (M2M services exposed from physical world has been increasing in recent years. Such M2M services enable communication of devices with the core processes of companies. However, there is a big challenge related to complexity and to application-specific M2M systems called “vertical silos”. This paper focuses on reviewing the technologies of M2M service networks and discussing approaches from the perspectives of M2M information and services, M2M communication and M2M security. Finally, a discussion on technologies and approaches potentially enabling future autonomic M2M service networks are provided. According to our conclusions, it is seen that clear definition of the architectural principles is needed to solve the “vertical silo” problem and then, proceeding towards enabling autonomic capabilities for solving complexity problem appears feasible. Several areas of future research have been identified, e.g., autonomic information based services, optimization of communications with limited capability devices, real-time messaging, creation of trust and end to end security, adaptability, reliability, performance, interoperability, and maintenance.

  9. Observations and modeling of a tidal inlet dye tracer plume

    Science.gov (United States)

    Feddersen, Falk; Olabarrieta, Maitane; Guza, R. T.; Winters, D.; Raubenheimer, Britt; Elgar, Steve

    2016-10-01

    A 9 km long tracer plume was created by continuously releasing Rhodamine WT dye for 2.2 h during ebb tide within the southern edge of the main tidal channel at New River Inlet, NC on 7 May 2012, with highly obliquely incident waves and alongshore winds. Over 6 h from release, COAWST (coupled ROMS and SWAN, including wave, wind, and tidal forcing) modeled dye compares well with (aerial hyperspectral and in situ) observed dye concentration. Dye first was transported rapidly seaward along the main channel and partially advected across the ebb-tidal shoal until reaching the offshore edge of the shoal. Dye did not eject offshore in an ebb-tidal jet because the obliquely incident breaking waves retarded the inlet-mouth ebb-tidal flow and forced currents along the ebb shoal. The dye plume largely was confined to <4 m depth. Dye was then transported downcoast in the narrow (few 100 m wide) surfzone of the beach bordering the inlet at 0.3 m s-1 driven by wave breaking. Over 6 h, the dye plume is not significantly affected by buoyancy. Observed dye mass balances close indicating all released dye is accounted for. Modeled and observed dye behaviors are qualitatively similar. The model simulates well the evolution of the dye center of mass, lateral spreading, surface area, and maximum concentration, as well as regional ("inlet" and "ocean") dye mass balances. This indicates that the model represents well the dynamics of the ebb-tidal dye plume. Details of the dye transport pathways across the ebb shoal are modeled poorly perhaps owing to low-resolution and smoothed model bathymetry. Wave forcing effects have a large impact on the dye transport.

  10. M2 factor of four-petal Gaussian beam

    Institute of Scientific and Technical Information of China (English)

    Zhou Guo-Quan; Fan Yan

    2008-01-01

    Based on the second-order moments,this paper derives an analytical expression of the M2 factor of four-petal Gaussian beam.The results show that the M2 factor is only determined by the beam order n.The corresponding numerical calculations are also given.As the beam order increases,the augment of M2 factor is disciplinary.As the expression of M2 factor is expressed in series form and becomes more complicated,a new concise formula of M2 factor is also presented by using curve fitting of numerical calculations.When 3≤n≤200,the maximum error rate of fitting formula will not exceed 2.6% and the average error rate is 0.28%.This research is helpful to the applications of four-petal Gaussian beam.

  11. InSAR-Based Mapping of Tidal Inundation Extent and Amplitude in Louisiana Coastal Wetlands

    Directory of Open Access Journals (Sweden)

    Talib Oliver-Cabrera

    2016-05-01

    Full Text Available The Louisiana coast is among the most productive coastal areas in the US and home to the largest coastal wetland area in the nation. However, Louisiana coastal wetlands have been disappearing at an alarming rate due to natural and anthropogenic processes, including sea level rise, land subsidence and infrastructure development. Wetland loss occurs mainly along the tidal zone, which varies in width and morphology along the Louisiana shoreline. In this study, we use Interferometric Synthetic Aperture Radar (InSAR observations to detect the extent of the tidal inundation zone and evaluate the interaction between tidal currents and coastal wetlands. Our data consist of ALOS and Radarsat-1 observations acquired between 2006–2011 and 2003–2008, respectively. Interferometric processing of the data provides detailed maps of water level changes in the tidal zone, which are validated using sea level data from a tide gauge station. Our results indicate vertical tidal changes up to 30 cm and horizontal tidal flow limited to 5–15 km from open waters. The results also show that the tidal inundation is disrupted by various man-made structures, such as canals and roads, which change the natural tidal flow interaction with the coast.

  12. Tidal and residual flows in the western Dutch Wadden Sea III: Vorticity balances

    Science.gov (United States)

    Ridderinkhof, H.

    A vorticity-dynamics approach is used to examine the origin of the small-scale residual current field in the western Dutch Wadden Sea. For a representative part of the Wadden Sea, the magnitude of vorticity and of terms in the balance equation for vorticity is determined on the basis of results from a two-dimensional numerical model. The torque from bottom friction along the side walls of the tidal channels appears to be the dominating mechanism in generating tidal relative vorticity, the magnitude of which is much larger than planetary vorticity. Especially near a tidal inlet, stretching and squeezing of fluid columns is of importance in increasing/decreasing relative vorticity. Averaging over a tidal period shows, compared to the tidal equations, an increased influence of the non-linear advective and streching/squeezing terms in the tidally-averaged balance. However, although the relative influence of these strong non-linear terms increases, the influence of the weak non-linear terms originating in bottom friction cannot be ignored. The mechanism responsible for the headland eddies near a tidal inlet and the topographical eddies in the channels of the Wadden Sea is essentially the same, viz. the transfer of vorticity from a source region where this vorticity is produced by differential bottom friction, to adjacent regions. This transfer of tidal vorticity, or advection, is most effective near a transition from straight to curved isobaths where a gradient in the production of tidal vorticity occurs. This is illustrated by showing the vorticity possessed by a particular fluid column during a tidal excursion. The dominant influence of the bathymetry on the small scale residual current pattern is used for a qualitative discussion of the residual flow field in other parts of our numerical model.

  13. Habitat Distribution of Denitrifier and Denitrification Activity in the Tidal Flat of the Interior Parts of the Ariake Sea

    Science.gov (United States)

    Koga, Akane; Seguchi, Masahiro; Koriyama, Masumi

    The spatial distributions of denitrifier numbers in the tidal sediment (0∼4cm depth) in the interior parts of the Ariake Sea changed largely with the properties of tidal flat and seasons. The denitrifier numbers in summer were many in the muddy tidal flat in the interior parts of this bay and about 18,000MPNs/g-dry on the average. But, its numbers were few in the sandy and mud-sandy tidal flats in the east and west coast areas and about 1,700MPN/g-dry on the average. A close relation between the denitrifier numbers in the tidal sediment (0∼4cm depth) and its mud (clay and silt) content was found and its numbers rose with the increase of mud content. The vertical distribution of denitrifier numbers in the muddy tidal flat was high near the surface layer (0∼2cm depth) where Eh was almost zero in summer, but its distribution decreased in other season. The denitrification rate in the muddy tidal flat changed largely with time (0.35-13.86mg-N·m-2·d-1). The denitrification activity in the muddy tidal flat was assumed to be affected by the environmental factors and substrate concentration other than the denitrifier numbers.

  14. M2 polarization enhances silica nanoparticle uptake by macrophages

    Directory of Open Access Journals (Sweden)

    Jessica eHoppstädter

    2015-03-01

    Full Text Available While silica nanoparticles have enabled numerous industrial and medical applications, their toxicological safety requires further evaluation. Macrophages are the major cell population responsible for nanoparticle clearance in vivo. The prevailing macrophage phenotype largely depends on the local immune status of the host. Whereas M1-polarized macrophages are considered as pro-inflammatory macrophages involved in host defense, M2 macrophages exhibit anti-inflammatory and wound-healing properties, but also promote tumor growth.We employed different models of M1 and M2 polarization: GM-CSF/LPS/IFN-gamma was used to generate primary human M1 cells and M-CSF/IL-10 to differentiate M2 monocyte-derived macrophages. PMA-differentiated THP-1 cells were polarized towards an M1 type by LPS/IFN-gamma and towards M2 by IL-10. Uptake of fluorescent silica nanoparticles (Ø 26 and 41 nm and microparticles (Ø 1.75 µm was quantified. At the concentration used (50 µg/ml, silica nanoparticles did not influence cell viability as assessed by MTT assay. Nanoparticle uptake was enhanced in M2-polarized primary human monocyte-derived macrophages compared with M1 cells, as shown by flow cytometric and microscopic approaches. In contrast, the uptake of microparticles did not differ between M1 and M2 phenotypes. M2 polarization was also associated with increased nanoparticle uptake in the macrophage-like THP-1 cell line. In accordance, in vivo polarized M2-like primary human tumor-associated macrophages (TAM obtained from lung tumors took up more nanoparticles than M1-like alveolar macrophages isolated from the surrounding lung tissue.In summary, our data indicate that the M2 polarization of macrophages promotes nanoparticle internalization. Therefore, the phenotypical differences between macrophage subsets should be taken into consideration in future investigations on nanosafety, but might also open up therapeutic perspectives allowing to specifically target M2

  15. Tidal Evolution of Planetary Systems

    Science.gov (United States)

    Rodríguez, A.

    2017-07-01

    We review the orbital and rotational evolution of single and two-planet systems under tidal dissipation. In the framework of mutual gravitational perturbation and tidal interaction between the star and the innermost planet, we shall present the main results for the variations of eccentricities in both cases. These results are obtained through the numerical solution of the exact equations of motions. Moreover, we will also give an analysis of the planetary rotation, which can be temporarily trapped in special configurations such as spin-orbit resonances. Results will be shown using a Maxwell viscoelastic deformation law for the inner planet. This rheology is characterized by a viscous relaxation time, τ, that can be seen as the characteristic average time that the planet requires to achieve a new equilibrium shape after being disturbed by an external forcing (tides of the star).

  16. Hydromechanics for the formation and development of radial sandbanks (Ⅱ)——Vertical characteristics of tidal flow

    Institute of Scientific and Technical Information of China (English)

    严以新; 宋志尧; 薛鸿超; 茅丽华

    1999-01-01

    In order to study the tidal current ridges, a three-dimensional numerical model is, for the first time, applied to studying the hydrodynamic circumstance with Houbolt’ s spiral assumption in the radial sandbank area. It successfully reveals that the radial sandbanks are molded by to-and-fro tidal current as well as the subtransverse circulation current, and that both contribute to maintaining the interior dynamic balance of the sandbanks. It is also found that the subtransverse circulation current would not always appear in pair within the ridges. These discoveries enrich the theoretical results in hydrodynamics of tidal current ridges.

  17. Prediction of CBS tidal evolution

    Science.gov (United States)

    Dryomova, G. N.

    The time series of basic processes, accompanying the tidal evolution of star components of Close Binary Systems (CBS) are predicted in the framework of evolutionary stellar models by Claret (2004). The series includes the apsidal motion period, timescale of synchronization of axial rotation of a star with the orbital revolution, the orbit circularization timescale, and the age. Data from the catalogues by Svechnikov & Perevozkina (1999) and by Torres, Andersen, Gimenez (2010) are used for testing the sensitivity of the numerical prediction algorithm.

  18. Tidal peritoneal dialysis: preliminary experience.

    Science.gov (United States)

    Flanigan, M J; Doyle, C; Lim, V S; Ullrich, G

    1992-01-01

    To determine the feasibility of home tidal peritoneal dialysis (TPD) and to assess whether eight hours of TPD can achieve uremia control and urea removal equal to that of continuous cycling peritoneal dialysis (CCPD). An open enrollment pilot study. The Home Dialysis Training Center of the University of Iowa Hospitals and Clinics, a tertiary care teaching hospital. Nine patients experienced with CCPD and living 80 km to 280 km from the dialysis center began TPD, because they wished to decrease their dialysis time. Following baseline measurements, each patient was taught to perform TPD. TPD consisted of an initial fill volume of 40 mL/kg, a residual volume approximately 20 mL/kg, and tidal exchanges of 10 to 20 mL/kg to achieve the desired hourly flow rate. Clinic assessments took place every four to six weeks, and prescriptions were subsequently altered to attain urea removal equal to that of CCPD. Patient interviews were used to determine TPD acceptance. Prior to each clinic visit, dialysate effluent volume and dialysis duration were recorded, and a sterile sample of the effluent was obtained for urea, creatinine, and total nitrogen measurement. Urea and creatinine clearances increased with dialysate flow. Dialysate nonurea nitrogen was 3.0 +/- 0.2 mmol/kg/D and changed minimally with increasing dialysate volumes. Eight hours of TPD (initial fill: 40 mL/kg; residual volume: 20 mL/kg; tidal inflow: 20 mL/kg) with hourly tidal flow exceeding 40 mL/kg/hr and no daytime volume achieved urea removal equal to that of the patient's prior CCPD prescription. TPD can provide dialysis equal to that of CCPD within a shorter amount of time (eight vs ten hours), but uses a greater volume of dialysate (16.0 L for TPD vs 9.5 L for CCPD).

  19. Trans World Tidal Gravity Profile.

    Science.gov (United States)

    1984-12-31

    America Curitiba (BraziZ) This station, situated at the Universidade Federal do Parana, in the Instituto de Ciencias Geod6sicas under Professor C...SUL COMPOSANTE VEPTICALE ERESIL 29 40 17S 53 49 22W H 700M P 2M 0 330KM DEPOTS SEDIMENTAIRES SUk BASALTE DEPT* DE INGENIERIA RURAL-UNIV. FED. DE SANTA...PRECAMBRIENIGNEISS * UNIVERSIDADE FEDERAL DO RIO GRANDE DO NORTE - DEPARTAMENTO DE FISICA TRANS WORLD TIDAL GRAVITY PROFILES P. MELCHIOR CENTRO POLITECNICO

  20. Effect of Sea Level Variation on Tidal Characteristic Values for the East China Sea

    Institute of Scientific and Technical Information of China (English)

    于宜法; 俞聿修; 左军成; 万振文; 陈宗镛

    2003-01-01

    Tidal waves in the East China Sea are simulated numerically with POM(Princeton Ocean Model) model for normal mean sea level, 30 cm higher, 60 cm higher, and 100 cm higher, respectively, and the simulated result is compared with the harmonic analysis result of hourly sea level data from 19 tide gauges for more than 19 years. It is indicated that the long-term mean sea level variation affects notably tidal waves in this region. Generally, the tidal amplitude increases when the mean sea level rises, but this relationship may be inverse for some sea areas. The maximal variation of tidal amplitude takes place in the zones near the Fujian coast and the Zhejiang coast, rather than the shallowest Bohai Sea. The maximum increase of M2 amplitude can exceed about 15 cm corresponding to the 60 cm rise of the mean sea level along the Fujian coast. The other regions with large variations of tidal amplitude are those along the Jiangsu coast, the south-east coast of Shandong, and the south-east coast of Dalian. The propagation of tidal waves is also related to mean sea level variation, and the tidal phase-lag decreases generally when the mean sea level rises. Almost all the regions where the tidal phase-lag increases with rising mean sea level are close to amphidromic points, meanwhile the spatial area of such regions is very small. Because the influence of mean sea level variation upon tidal waves is spatially marked, such spatial effect should be considered in calculation of the tidal characteristic value and engineering water level. In the region where the amplitudes of the major tidal constituents increase, the probable maximum high water level becomes higher, the probable maximum low water level becomes lower, and both design water level andcheck water level increase obviously. For example, the design water level at Xiamen increases by 13.5 cm due to the variation of tidal waves when the mean sea level rises 60 cm, the total increase of design water level being 73.5 cm.

  1. 竖轴水轮机三维水动力响应的数值模拟%THREE DIMENSIONAL NUMERICAL SIMULATION FOR HYDRODYNAMIC RESPONSE OF VERTICAL AXIS TIDAL CURRENT TURBINE

    Institute of Scientific and Technical Information of China (English)

    康海贵; 郭伟

    2013-01-01

    基于Realizable κ-ε湍流模型和三维N-S方程,应用CFD软件FLUENT的滑动网格方法,对一种新型变攻角竖轴水轮机三维情况下的水动力响应及能量转换系数进行理论分析和数值模拟计算.研究结果表明:连接杆件的截面为NACA翼型时对转轴提供的附加扭矩大于圆形截面连接杆件;选取截面翼型为NACA4415的连接杆件对其安装角度的影响进行比较分析,可知当连接杆件翼型的弦线与来流平行时,能量转换系数最大,与实验数据有较高的吻合度.表明Realizable κ-ε湍流模型是一种有效的数值模拟方法.%Based on Realizable k-ε turbulence model and three-dimensional Navier-Stokes equation, the hydro-dynamic response of the vertical-axis variable-pitch tidal turbine under three-dimensional was theoretical analyzed and numerically simulated by advanced CFD software FLUENT with Moving Mesh method. The numerical simulation results showed that the torque generated by different NACA aerofoils connecting rods are higher than generated by circular section connecting rod. It suggests that when the chord of the NACA4415 aerofoil parallels with the coming flow, the torque is the biggest after analyzing the influence of installation angle of aerofoils. Finally the results showed that Realizable k-ε turbulence model is a kind of effective numerical simulation method for predicting three-dimensional hydrodynamic response.

  2. Chaotic Dispersal of Tidal Debris

    CERN Document Server

    Price-Whelan, Adrian M; Valluri, Monica; Pearson, Sarah; Kupper, Andreas H W; Hogg, David W

    2015-01-01

    Several long, dynamically cold stellar streams have been observed around the Milky Way Galaxy, presumably formed from the tidal disruption of globular clusters. In integrable potentials---where all orbits are dynamically regular---tidal debris phase-mixes close to the orbit of the progenitor system. However, cosmological simulations of structure formation suggest that the Milky Way's dark matter halo is expected not to be fully integrable; an appreciable fraction of orbits will be chaotic. This paper examines the influence of chaos on the phase-space morphology of cold tidal streams. We find very stark results: Streams in chaotic regions look very different from those in regular regions. We find that streams (simulated using test particle ensembles of nearby orbits) can be sensitive to chaos on a much shorter time-scale than any standard prediction (from the Lyapunov or frequency-diffusion times). For example, on a weakly chaotic orbit with a chaotic timescale predicted to be >1000 orbital periods (>1000 Gyr)...

  3. Tidal Limits to Planetary Habitability

    CERN Document Server

    Barnes, Rory; Greenberg, Richard; Raymond, Sean N

    2009-01-01

    The habitable zones of main sequence stars have traditionally been defined as the range of orbits that intercept the appropriate amount of stellar flux to permit surface water on a planet. Terrestrial exoplanets discovered to orbit M stars in these zones, which are close-in due to decreased stellar luminosity, may also undergo significant tidal heating. Tidal heating may span a wide range for terrestrial exoplanets and may significantly affect conditions near the surface. For example, if heating rates on an exoplanet are near or greater than that on Io (where tides drive volcanism that resurface the planet at least every 1 Myr) and produce similar surface conditions, then the development of life seems unlikely. On the other hand, if the tidal heating rate is less than the minimum to initiate plate tectonics, then CO_2 may not be recycled through subduction, leading to a runaway greenhouse that sterilizes the planet. These two cases represent potential boundaries to habitability and are presented along with th...

  4. North American tidal power prospects

    Science.gov (United States)

    Wayne, W. W., Jr.

    1981-07-01

    Prospects for North American tidal power electrical generation are reviewed. Studies by the US Army Corps of Engineers of 90 possible generation schemes in Cobscook Bay, ME, indicated that maximum power generation rather than dependable capacity was the most economic method. Construction cost estimates for 15 MW bulb units in a single effect mode from basin to the sea are provided; five projects were considered ranging from 110-160 MW. Additional tidal power installations are examined for: Half-Moon Cove, ME (12 MW, 18 ft tide); Cook Inlet, AK, which is shown to pose severe environmental and engineering problems due to fish migration, earthquake hazards, and 300 ft deep silt deposits; and the Bay of Fundy, Canada. This last has a 17.8 MW plant under construction in a 29 ft maximum tide area. Other tidal projects of the Maritime Provinces are reviewed, and it is noted that previous economic evaluations based on an oil price of $16/barrel are in need of revision.

  5. Properties of Red Sea coastal currents

    KAUST Repository

    Churchill, J.H.

    2014-02-14

    Properties of coastal flows of the central Red Sea are examined using 2 years of velocity data acquired off the coast of Saudi Arabia near 22 °N. The tidal flow is found to be very weak. The strongest tidal constituent, the M2 tide, has a magnitude of order 4 cm s−1. Energetic near-inertial and diurnal period motions are observed. These are surface-intensified currents, reaching magnitudes of >10 cm s−1. Although the diurnal currents appear to be principally wind-driven, their relationship with the surface wind stress record is complex. Less than 50% of the diurnal current variance is related to the diurnal wind stress through linear correlation. Correlation analysis reveals a classical upwelling/downwelling response to the alongshore wind stress. However, less than 30% of the overall sub-inertial variance can be accounted for by this response. The action of basin-scale eddies, impinging on the coastal zone, is implicated as a primary mechanism for driving coastal flows.

  6. Stellar Tidal Streams in External Galaxies

    CERN Document Server

    Carlin, Jeffrey L; Martinez-Delgado, David; Gabany, R Jay

    2016-01-01

    To place the highly substructured stellar halos of the Milky Way and M31 in a larger context of hierarchical galaxy formation, it is necessary to understand the prevalence and properties of tidal substructure around external galaxies. This chapter details the current state of our observational knowledge of streams in galaxies in and beyond the Local Group, which are studied both in resolved stellar populations and in integrated light. Modeling of individual streams in extragalactic systems is hampered by our inability to obtain resolved stellar kinematics in the streams, though many streams contain alternate luminous kinematic tracers, such as globular clusters or planetary nebulae. We compare the observed structures to the predictions of models of galactic halo formation, which provide insight in the number and properties of streams expected around Milky Way like galaxies. More specifically, we discuss the inferences that can be made about stream progenitors based only on observed morphologies. We expand our...

  7. 长江口深水航道水流特征沿程分布准调和分析%The Harmonic Analysis of Tidal Currents in the Radial Sand Ridge in the Deep Water Channel of Yangtze Estuary

    Institute of Scientific and Technical Information of China (English)

    潘金仙; 吴德安; 谢新星

    2016-01-01

    根据长江口深水航道治理工程二期2005年8月大潮期间的水文测验资料,选取NG0、NG3、CB1、CS0、CS1、CB2、CS2、CS6、CSW、CS3、CS7、CS4、CS5共13个站位测点的二个潮周期的六层流速测量资料,对这些测点数据进行准潮流调和分析,得出P1,K1,M2,M3,M4,2MK5,M6,3MK7,M8,M10共10个分潮的潮流调和常数及余流结果,并计算给出了相应椭圆要素.研究分析发现,潮流特征系数值均不超过0.25,沿程各测点区域潮流类型以半日潮为主.对太阴半日分潮M2的椭圆长半轴、椭圆短半轴、椭率以及格林威治迟角等椭圆要素空间分布特征进行分析比较.总结潮流椭圆要素、潮流特征、浅水影响分子、余流以及最大可能潮流流速的沿程空间变化规律以及动力影响分析.M2分潮的椭圆要素有较强的规律性,浅水影响因子随水深变小而增大,在总体上都有沿程减小的趋势.最大可能潮流流速在垂向从表层到近底层逐渐减小,符合水流流速沿水深的分布.研究结果对理解深水航道动力状况、淤积机制和指导航道工程整治具有一定价值.

  8. Sediment resuspension in tidally dominated coastal environments: new insights into the threshold for initial movement

    Science.gov (United States)

    Yang, Yang; Wang, Ya Ping; Gao, Shu; Wang, Xiao Hua; Shi, Ben Wei; Zhou, Liang; Wang, Dan Dan; Dai, Chen; Li, Gao Cong

    2016-03-01

    An understanding of sediment resuspension and its threshold, for initial movement in shallow marine environments, is of great importance in coastal geomorphology, ecology, and harbor/fishery management applications. In the present study, in situ measurements of tides, current velocities, waves, and suspended sediment concentrations (SSCs) were measured at three shallow water sites with different tidal current patterns and seabed sediment grain sizes. The sites were associated with the radial sand ridge system (B4 and D2, rectilinear currents) and the Great Yangtze Shoal (D1, rotatory currents), in the southern Yellow Sea, China, both representing tidally dominated environments. The SSC data were analyzed to identify the controlling factors associated with resuspension and advection processes. There is a significant correlation between the near-bed SSC and shear stress, indicating that SSC variations are dominated by resuspension processes. Based on integrated field measurements of SSCs and hydrodynamics, the bed shear stresses of currents and waves were calculated, and the critical shear stresses for seabed erosion of the three sites were determined. At D2 (non-cohesive sediment) and B4/D1 (cohesive sediment), the critical shear stresses for seabed erosion (or resuspension) were estimated to be 0.11 and 0.07/0.09 N m-2, respectively. Although this result is reasonable when only the three sites are compared, both values are lower than predicted by existing threshold models, with a difference between 30 and 83 %. Such discrepancies can be related to intermittent turbulence events. For both sites, statistical and quadrant analyses have revealed significant correlations between near-bed SSC variations and intermittent turbulence events. This observation implies that the threshold conditions using the critical bed shear stress, derived from the current velocity profile, have a spatial scale effect: on a small scale (e.g., a flume in laboratory), the threshold can be

  9. Trapping and episodic flushing of suspended sediment from a tidal river

    Science.gov (United States)

    Pritchard, Mark; Green, Malcolm

    2017-07-01

    Recent studies suggest that tidal forcing can be as important as gravitational circulation in maintaining an estuarine turbidity maximum (ETM). It is further postulated that a long-term mass balance between the import and export of sediment in an estuary may require episodic large river discharges or 'freshets' to flush sediment out of the ETM towards the open sea. In this study, we use a 2-month data set from a mooring in a tidal river that drains into a large drowned-river-valley estuary (Kaipara Harbour, New Zealand) to investigate interactions between tidal-current asymmetry and gravitational circulation. During baseflow river discharge and on spring tides, suspended-sediment transport was directed up-channel (landwards), driven by tidal pumping due to tidal-current asymmetry. During neap tides, the suspended-sediment flux was approximately zero. The data suggest that the bed was not locally erodible and that bed sediments at the site were being supplied by an ETM. The ETM only migrated far enough down channel to be observed at the mooring site during spring tides when the tidal excursion was longer. Suspended sediments were effectively trapped and recycled within the ETM. During and after two freshets, high river discharge displaced saline water from the tidal river, water-column stratification strengthened and the surface and bed current speeds increased. As a result, the advective component of the down-channel directed suspended-sediment flux increased. This provided a transport pathway for sediment out of the otherwise tidally pumped, flood-dominant system. We conclude that largest export of sediments out of the tidal river would potentially occur when a large freshet coincides with an apogean spring tide.

  10. Tidally Induced Pulsations in Kepler Eclipsing Binary KIC 3230227

    CERN Document Server

    Guo, Zhao; Fuller, Jim

    2016-01-01

    KIC 3230227 is a short period ($P\\approx 7.0$ days) eclipsing binary with a very eccentric orbit ($e=0.6$). From combined analysis of radial velocities and {\\it Kepler} light curves, this system is found to be composed of two A-type stars, with masses of $M_1=1.84\\pm 0.18M_{\\odot}$, $M_2=1.73\\pm 0.17M_{\\odot}$ and radii of $R_1=2.01\\pm 0.09R_{\\odot}$, $R_2=1.68\\pm 0.08 R_{\\odot}$ for the primary and secondary, respectively. In addition to an eclipse, the binary light curve shows a brightening and dimming near periastron, making this a somewhat rare eclipsing heartbeat star system. After removing the binary light curve model, more than ten pulsational frequencies are present in the Fourier spectrum of the residuals, and most of them are integer multiples of the orbital frequency. These pulsations are tidally driven, and both the amplitudes and phases are in agreement with predictions from linear tidal theory for $l=2, m=-2$ prograde modes.

  11. TNF Counterbalances the Emergence of M2 Tumor Macrophages

    Directory of Open Access Journals (Sweden)

    Franz Kratochvill

    2015-09-01

    Full Text Available Cancer can involve non-resolving, persistent inflammation where varying numbers of tumor-associated macrophages (TAMs infiltrate and adopt different activation states between anti-tumor M1 and pro-tumor M2 phenotypes. Here, we resolve a cascade causing differential macrophage phenotypes in the tumor microenvironment. Reduction in TNF mRNA production or loss of type I TNF receptor signaling resulted in a striking pattern of enhanced M2 mRNA expression. M2 gene expression was driven in part by IL-13 from eosinophils co-recruited with inflammatory monocytes, a pathway that was suppressed by TNF. Our data define regulatory nodes within the tumor microenvironment that balance M1 and M2 populations. Our results show macrophage polarization in cancer is dynamic and dependent on the balance between TNF and IL-13, thus providing a strategy for manipulating TAMs.

  12. TNF counterbalances the emergence of M2 tumor macrophages

    Science.gov (United States)

    Kratochvill, Franz; Neale, Geoffrey; Haverkamp, Jessica M.; de Velde, Lee-Ann Van; Smith, Amber M.; Kawauchi, Daisuke; McEvoy, Justina; Roussel, Martine F.; Dyer, Michael A.; Qualls, Joseph E.; Murray, Peter J.

    2015-01-01

    Cancer is a form of non-resolving, persistent inflammation where varying numbers of tumor-associated macrophages (TAMs) infiltrate and adopt different activation states between anti-tumor M1 and pro-tumor M2 phenotypes. Here we resolve a cascade causing differential macrophage phenotypes in the tumor microenvironment. Reduction in TNF mRNA production or loss of Type I TNF receptor signaling resulted in a striking pattern of enhanced M2 mRNA expression. M2 gene expression was driven in part by IL-13 from eosinophils co-recruited with inflammatory monocytes, a pathway that was suppressed by TNF. Our data define regulatory nodes within the tumor microenvironment that balance M1 and M2 populations. Our results show macrophage polarization in cancer is dynamic and dependent on the balance between TNF and IL-13, thus providing a strategy for manipulating TAMs. PMID:26365184

  13. Multiple Access Technologies for Cellular M 2M Communications

    Institute of Scientific and Technical Information of China (English)

    Mahyar Shirvanimoghaddam; Sarah J. Johnson

    2016-01-01

    This paper reviews the multiple access techniques for machine⁃to⁃machine (M2M) communications in future wireless cellular net⁃works. M2M communications aims at providing the communication infrastructure for the emerging Internet of Things (IoT), which will revolutionize the way we interact with our surrounding physical environment. We provide an overview of the multiple access strategies and explain their limitations when used for M2M communications. We show the throughput efficiency of different multi⁃ple access techniques when used in coordinated and uncoordinated scenarios. Non⁃orthogonal multiple access (NOMA) is also shown to support a larger number of devices compared to orthogonal multiple access techniques, especially in uncoordinated sce⁃narios. We also detail the issues and challenges of different multiple access techniques to be used for M2M applications in cellu⁃lar networks.

  14. Theoretical Assessment of 178m2Hf De-Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hartouni, E P; Chen, M; Descalle, M A; Escher, J E; Loshak, A; Navratil, P; Ormand, W E; Pruet, J; Thompson, I J; Wang, T F

    2008-10-06

    This document contains a comprehensive literature review in support of the theoretical assessment of the {sup 178m2}Hf de-excitation, as well as a rigorous description of controlled energy release from an isomeric nuclear state.

  15. Characterization of M2 antibodies in asymptomatic Chinese population

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hua Jiang; Ren-Qian Zhong; Xiao-Yun Fan; Yin Hu; Feng An; Jian-Wen Sun; Xian-Tao Kong

    2003-01-01

    AIM: To investigate the presence of M2 antibodies specific for pdmary biliary cirrhosis (PBC) in asymptomatic Chinese and identify patients with early PBC.METHODS: Enzyme-linked immunosorbent assay (ElISA)tests for M2 antibodies to recombinant protein were performed in 5 011 subjects (age range, 26-85 years; mean age: 45.81±15.02 years) who took an annual physical examination. M2-positive subjects were further analyzed for immunoglobulin (Ig) classes and subclasses of M2 antibodies.Clinical, biochemical and immunological data were obtained for M2-positive subjects. In addition, ultrasonography (US)or endoscopic retrograde cholangio-pancreatography (ERCP)was performed to exclude any disorders other than PBC.RESULTS: M2 antibodies were detected in 8 (0.16%) of the 5 0LL subjects studied. Of the 8 subjects, 7 were female and 1 was male (age range: 40-74 years). An unexplained increase of serum alkaline phosphatase (ALP) and gamma glutamyl transpeptidase (γ-GT) values, often to striking levels,was detected in 4 M2-positive subjects, 3 of them accorded with the diagnostic criteria recommended by the American Association for the Study of Liver Diseases, even though they had no symptoms of PBC (such as fatigue, pruritus or jaundice).Liver biopsy was performed in two M2-positive subjects and the histology was compatible with PBC in both cases.CONCLUSION: Our data, while not assessing the true prevalence of asymptomatic PBC in the general population,suggest that asymptomatic PBC is much more common in China than has been supposed.

  16. M2-Edge Colorings Of Cacti And Graph Joins

    Directory of Open Access Journals (Sweden)

    Czap Július

    2016-02-01

    Full Text Available An edge coloring φ of a graph G is called an M2-edge coloring if |φ(v| ≤ 2 for every vertex v of G, where φ(v is the set of colors of edges incident with v. Let 2(G denote the maximum number of colors used in an M2-edge coloring of G. In this paper we determine 2(G for trees, cacti, complete multipartite graphs and graph joins.

  17. Study of {sup 179}Hf{sup m2} excitation

    Energy Technology Data Exchange (ETDEWEB)

    Vishnevsky, I. N.; Zheltonozhsky, V. A., E-mail: zhelton@kinr.kiev.ua; Savrasov, A. N. [National Academy of Sciences of Ukraine, Institute for Nuclear Research (Ukraine); Mazur, V. M. [National Academy of Sciences of Ukraine, Institute of Electronic Physics (Ukraine)

    2016-12-15

    Isomeric ratios of {sup 179}Hf{sup m2,g} yields in the (γ, n) reaction and the cross section for the {sup 179}Hf{sup m2} population in the (α, p) reaction are measured for the first time at the end-point energies of 15.1 and 17.5 MeV for bremsstrahlung photons and 26 MeV for alpha particles. The results are σ = (1.1 ± 0.11) × 10{sup −27} cm{sup 2} for the {sup 176}Lu(α, p){sup 179}Hf{sup m2} reaction and Y{sub m2}/Y{sub g} = (6.1 ± 0.3) × 10{sup −6} and (3.7 ± 0.2) × 10{sup −6} for the {sup 180}Hf(γ, n){sup 179}Hf{sup m22} reaction at E{sub ep} =15.1 and 17.5 MeV, respectively. The experimental data on the relative {sup 179}Hf{sup m2} yield indicate a single-humped shape of the excitation function for the {sup 180}Hf(γ, n){sup 179}Hf{sup m2} reaction. Simulation is performed using the TALYS-1.4 and EMPIRE-3.2 codes.

  18. Revisiting the endocytosis of the m2 muscarinic acetylcholine receptor.

    Science.gov (United States)

    Ockenga, Wymke; Tikkanen, Ritva

    2015-05-12

    The agonist-induced endocytosis of the muscarinic acetylcholine receptor M2 is different from that of the other members of the muscarinic receptor family. The uptake of the M2 receptor involves the adapter proteins of the β-arrestin family and the small GTPase ADP-ribosylation factor 6. However, it has remained inconclusive if M2 endocytosis is dependent on clathrin or the large GTPase dynamin. We here show by means of knocking down the clathrin heavy chain that M2 uptake upon agonist stimulation requires clathrin. The expression of various dominant-negative dynamin-2 mutants and the use of chemical inhibitors of dynamin function revealed that dynamin expression and membrane localization as such appear to be necessary for M2 endocytosis, whereas dynamin GTPase activity is not required for this process. Based on the data from the present and from previous studies, we propose that M2 endocytosis takes place by means of an atypical clathrin-mediated pathway that may involve a specific subset of clathrin-coated pits/vesicles.

  19. Revisiting the Endocytosis of the M2 Muscarinic Acetylcholine Receptor

    Directory of Open Access Journals (Sweden)

    Wymke Ockenga

    2015-05-01

    Full Text Available The agonist-induced endocytosis of the muscarinic acetylcholine receptor M2 is different from that of the other members of the muscarinic receptor family. The uptake of the M2 receptor involves the adapter proteins of the β-arrestin family and the small GTPase ADP-ribosylation factor 6. However, it has remained inconclusive if M2 endocytosis is dependent on clathrin or the large GTPase dynamin. We here show by means of knocking down the clathrin heavy chain that M2 uptake upon agonist stimulation requires clathrin. The expression of various dominant-negative dynamin-2 mutants and the use of chemical inhibitors of dynamin function revealed that dynamin expression and membrane localization as such appear to be necessary for M2 endocytosis, whereas dynamin GTPase activity is not required for this process. Based on the data from the present and from previous studies, we propose that M2 endocytosis takes place by means of an atypical clathrin-mediated pathway that may involve a specific subset of clathrin-coated pits/vesicles.

  20. Dynamics of tidally captured planets in the Galactic Center

    CERN Document Server

    Trani, Alessandro; Spera, Mario; Bressan, Alessandro

    2016-01-01

    Recent observations suggest ongoing planet formation in the innermost parsec of the Galactic center (GC). The super-massive black hole (SMBH) might strip planets or planetary embryos from their parent star, bringing them close enough to be tidally disrupted. Photoevaporation by the ultraviolet field of young stars, combined with ongoing tidal disruption, could enhance the near-infrared luminosity of such starless planets, making their detection possible even with current facilities. In this paper, we investigate the chance of planet tidal captures by means of high-accuracy N-body simulations exploiting Mikkola's algorithmic regularization. We consider both planets lying in the clockwise (CW) disk and planets initially bound to the S-stars. We show that tidally captured planets remain on orbits close to those of their parent star. Moreover, the semi-major axis of the planet orbit can be predicted by simple analytic assumptions in the case of prograde orbits. We find that starless planets that were initially bo...

  1. Survey of Morphological Changes on Tidal Flats in Estuaries

    Science.gov (United States)

    Albers, Thorsten; von Lieberman, Nicole

    2010-05-01

    Tidal flat areas in estuaries are affected by strong morphodynamics. Changes of sedimentation and erosion occur on very different time and spatial scales. These changes challenge the responsible authorities due to the high importance of sufficient navigation channel depths and the ecological importance of those unique zones. The Hamburg University of Technology in cooperation with the Hamburg Port Authority runs broad field measurements on different tidal flat areas in the Elbe estuary. The results provide a fundamental data set, which improves the knowledge about morphodynamic processes and verifies mathematical descriptions. The field measurements focus on two investigation areas: One area is located in the mouth of the estuary and represents a marine tidal flat. The other one is located near the city of Hamburg and typifies a limnic tidal flat area. For more than 3 years water levels, waves, current parameters and suspended sediment concentrations are being recorded continuously and in a high resolution at different positions. Altogether, three measuring positions are operated at any time. To observe the consequences of the morphodynamic processes, the bathymetry of the investigation areas is determined with a multi-beam echo sounder (MBES) in frequent intervals. The main goal of the research project is to improve the knowledge about morphodynamic processes on tidal flats. Derived from the field data certain patterns of erosion, sediment transport and sedimentation could be observed depending on tidal currents, waves and large scale weather conditions. Seasonal effects are analysed as well as the influence of extreme events. A comparison of the processes observed on marine and limnic areas is done, whereas the latter additionally is affected by upstream water discharge. For example, on the marine tidal flats the sediment transport capacity was analysed: Extreme events cause a short peak, which does not result in significant bathymetric changes. Larger

  2. Numerical Analysis of the Mixing Zone for a Vertical Discharge into a Tidal River

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper analyzes the mixing zone of a vertical discharge of sewage into a natural tidal river with strong tidal currents. The paper presents a numerical model, which combines 1-D and 2-D models to compute the mixing zone for the Sibao Segment of the Qiantang River. The simple 1-D model was used to model the flow for the entire river using field data as the boundary conditions. The complete depth-averaged turbulence model was used for the 2-D computation. The calculated results agree well with the field observations. The analysis provides a practical method for the computation of mixing zones in tidal rivers.

  3. The fundamental characteristics of current in the Bering Strait and the Chukchi Sea from July to September 2003

    Institute of Scientific and Technical Information of China (English)

    LI Lei; DU Ling; ZHAO Jinping; ZUO Juncheng; LI Peiliang

    2005-01-01

    The characteristics of current in the Bering Strait and the Chukchi Sea are analyzed based on the two current data on the mooring stations during the Second National Arctic Research Expedition of China in 2003. The tidal currents of the principal diurnal and semidiurnal ellipses rotate clockwise in the upper layer, except for N2, S2, and Q1 at Sta. ST. In the Bering Strait (Sta. ST), the major semi-axis of tidal current constituent M2 is 2.9 cm/s in the upper layer, which is much smaller than that of semi-monthly oscillation (11.8 cm/s);and the mean current flows northwestward at the amplitude of about 20 cm/s and varies a little with depth. During the cruise, the current has significant semi-monthly oscillation at the two mooring stations. The spectra analyses of the air pressure gradient and the wind stress show that there are the semi-monthly oscillations in these two data series. The near-inertial current, approximately 4 cm/s, presents almost the same magnitude of the principal tidal currents in the Bering Strait.

  4. Feedback between tidal hydrodynamics and morphological changes induced by natural process and human interventions in a wave-dominated tidal inlet: Xiaohai, Hainan, China

    Institute of Scientific and Technical Information of China (English)

    GONG Wenping; SHEN Jian; JIA Jianjun

    2009-01-01

    The feedback between morphological evolution and tidal hydrodynamics in a wave-dominated tidal inlet, Xiaohai, China is investigated through data analysis and numerical model experiments. His-torically, Xiaohai Inlet had two openings, located at the north and south of Neizhi Island (a rocky outcrop), respectively. The evolution of Xiaohai Inlet was dominated by the natural process be-fore 1972. In addition to the natural process, human interventions, including the closure of the north opening, 50% of freshwater reduction, and increase of land reclamation, have altered tidal hydrodynamics and morphological evolution since 1972. A series of numerical model simulations were conducted to investigate the influence of morphological changes on the hydrodynamics and the influence of human activities on the inlet evolution. The natural process has caused narrowing and shoaling of the inlet throat, development of the flood-tidal delta, and shoaling of the tidal channel inside the lagoon. Human interventions have accelerated these changes. Consequently, the tidal propagation from the offshore into the lagoon has been impeded and the tidal energy has been dissipated substantially. Tidal current has changed from ebb-dominant to flood-dominant in most parts of the inlet system whereas the inlet throat has remained as ebb-dominant, the tidal prism has decreased consistently, and sediment has continued to deposit inside the inlet. As a result, the changes of morphology, hydrodynamics, and sediment transport show a positive feedback. The human interventions have had both advantageous and adverse influences on the stability of the inlet. The closure of the North Opening has decreased the longshore sediment input to the inlet, and increased the tidal prism, ebb velocity, and sediment transport in the south opening, thus enhancing the inlet's stability. However, reducing the river discharge and landfill of the tidal flats has resulted in a decrease of the tidal prism, the ebb velocity

  5. Residual flow and tidal asymmetry in the Singapore Strait, with implications for resuspension and residual transport of sediment

    NARCIS (Netherlands)

    Van Maren, D.S.; Gerritsen, H.

    2012-01-01

    The Singapore Strait connects the South China Sea, where tides are dominantly diurnal, to the dominantly semidiurnal Indian Ocean. At this transition, the tidal water level oscillations are observed to be semidiurnal while the tidal current oscillations are mixed, diurnal to fully diurnal. Due to

  6. Tidal friction in close-in planets

    Science.gov (United States)

    Rodríguez, Adrián; Ferraz-Mello, Sylvio; Hussmann, Hauke

    2008-05-01

    We use Darwin's theory (Darwin, 1880) to derive the main results on the orbital and rotational evolution of a close-in companion (exoplanet or planetary satellite) due to tidal friction. The given results do not depend on any assumption linking the tidal lags to the frequencies of the corresponding tide harmonics (except that equal frequency harmonics are assumed to span equal lags). Emphasis is given to the study of the synchronization of the planetary rotation in the two possible final states for a non-zero eccentricity : (1) the super-synchronous stationary rotation resulting from the vanishing of the average tidal torque; (2) the capture into a 1:1 spin-orbit resonance (true synchronization), which is only possible if an additional torque exists acting in opposition to the tidal torque. Results are given under the assumption that this additional torque is produced by a non-tidal permanent equatorial asymmetry of the planet. The indirect tidal effects and some non-tidal effects due to that asymmetry are considered. For sake of comparison with other works, the results obtained when tidal lags are assumed proportional to the corresponding tidal wave frequencies are also given.

  7. Calculating lunar retreat rates using tidal rhythmites

    Science.gov (United States)

    Kvale, E.P.; Johnson, H.W.; Sonett, C.P.; Archer, A.W.; Zawistoski, A.N.N.

    1999-01-01

    Tidal rhythmites are small-scale sedimenta??r}- structures that can preserve a hierarchy of astronomically induced tidal periods. They can also preserve a record of periodic nontidal sedimentation. If properly interpreted and understood, tidal rhjthmites can be an important component of paleoastronomy and can be used to extract information on ancient lunar orbital dynamics including changes in Earth-Moon distance through geologic time. Herein we present techniques that can be used to calculate ancient Earth-Moon distances. Each of these techniques, when used on a modern high-tide data set, results in calculated estimates of lunar orbital periods and an EarthMoon distance that fall well within 1 percent of the actual values. Comparisons to results from modern tidal data indicate that ancient tidal rhythmite data as short as 4 months can provide suitable estimates of lunar orbital periods if these tidal records are complete. An understanding of basic tidal theory allows for the evaluation of completeness of the ancient tidal record as derived from an analysis of tidal rhythmites. Utilizing the techniques presented herein, it appears from the rock record that lunar orbital retreat slowed sometime during the midPaleozoic. Copyright ??1999, SEPM (Society for Sedimentary Geology).

  8. Comparison of Bottom Friction Formulations for Single-Constituent Tidal Simulations in Kyunggi Bay

    Science.gov (United States)

    Lee, J. C.; Kim, C. S.; Jung, K. T.

    2001-11-01

    This paper investigates the influence of bottom friction on the tidal elevation in Kyunggi Bay, located west of Korea, by comparing the linear, linearized and quadratic bottom friction formulations, deducing an optimal bottom friction coefficient (BFC) for each formulation in single-constituent simulations. Model results are compared with observed tidal amplitudes and phases at 52 locations. The linear friction formulation with an optimal BFC produces the observed tidal elevation satisfactorily for all consitutents. However, the optimal linear BFC in Kyunggi Bay is one order smaller than that used in global tide calculations. The optimal BFC in the linearized formulation for the M 2tide is identical to the theoretical value given by Pingree (1983). The optimal linearized BFCs for other constituents are approximately 90% of optimal quadratic BFC for the M 2tide alone. Experiments with a range of quadratic BFCs show that the optimal BFCs for single-constituent tide are quite different from constituent by constituent, giving considerably large values of BFC except for the M 2tide. The single-constituent simulation shows that the optimal quadratic BFC for S 2(K 1) only is about 4 (10) times larger than that for M 2only. Multi-constituent simulation and single-constituent experiments with the force argument (Bowers et al., 1991) clearly show that the BFC in single-constituent simulations should be increased to incorporate the bulk effects of other constituents.

  9. Transport estimates in the Strait of Gibraltar with a tidal inverse model

    Science.gov (United States)

    Baschek, Burkard; Send, Uwe; Lafuente, Jesus Garcia; Candela, Julio

    2001-12-01

    To estimate the volume transport through the Strait of Gibraltar and to study the spatial structure of the time-variable flow, a varying number of current meter moorings were maintained at the eastern entrance of the strait between October 1994 and April 1998, and was complemented with intensive shipboard measurements during the European Union project Canary Island Azores Gibraltar Experiment (CANIGO). A tidal inverse model is used to merge these data sets in order to investigate the flow at the eastern entrance of the strait. The two-dimensional structure of the tidal flow was described by simple analytical functions. Harmonics with the seven most important tidal frequencies were used as temporal functions. With this model, the tidal currents can be predicted for any time and location at the eastern entrance of the strait, and more than 92% of the variance of the lower layer flow is explained. It was used to remove the tidal currents from the individual measurements and to calculate the mean flow through the strait from the residuals. Combined with a similar inverse model for determining the depth of the interface between Mediterranean and Atlantic water, the volume transport was estimated to be 0.81±0.07 Sv for the upper layer and -0.76±0.07 Sv for the lower layer. The correlation of the tidal currents and the fluctuations of the interface accounts for ˜7% of the transport at the eastern entrance.

  10. Can We Probe the Conductivity of the Lithosphere and Upper Mantle Using Satellite Tidal Magnetic Signals?

    Science.gov (United States)

    Schnepf, N. R.; Kuvshinov, A.; Sabaka, T.

    2015-01-01

    A few studies convincingly demonstrated that the magnetic fields induced by the lunar semidiurnal (M2) ocean flow can be identified in satellite observations. This result encourages using M2 satellite magnetic data to constrain subsurface electrical conductivity in oceanic regions. Traditional satellite-based induction studies using signals of magnetospheric origin are mostly sensitive to conducting structures because of the inductive coupling between primary and induced sources. In contrast, galvanic coupling from the oceanic tidal signal allows for studying less conductive, shallower structures. We perform global 3-D electromagnetic numerical simulations to investigate the sensitivity of M2 signals to conductivity distributions at different depths. The results of our sensitivity analysis suggest it will be promising to use M2 oceanic signals detected at satellite altitude for probing lithospheric and upper mantle conductivity. Our simulations also suggest that M2 seafloor electric and magnetic field data may provide complementary details to better constrain lithospheric conductivity.

  11. Tidal Constraints on Planetary Habitability

    CERN Document Server

    Barnes, Rory; Greenberg, Richard; Raymond, Sean N; Heller, Rene

    2009-01-01

    We review how tides may impact the habitability of terrestrial-like planets. If such planets form around low-mass stars, then planets in the circumstellar habitable zone will be close enough to their host stars to experience strong tidal forces. We discuss 1) decay of semi-major axis, 2) circularization of eccentric orbits, 3) evolution toward zero obliquity, 4) fixed rotation rates (not necessarily synchronous), and 5) internal heating. We briefly describe these effects using the example of a 0.25 solar mass star with a 10 Earth-mass companion. We suggest that the concept of a habitable zone should be modified to include the effects of tides.

  12. Factors Influencing the Spatial Variation of Microplastics on High-Tidal Coastal Beaches in Korea.

    Science.gov (United States)

    Kim, In-Sung; Chae, Doo-Hyeon; Kim, Seung-Kyu; Choi, SooBong; Woo, Seung-Bum

    2015-10-01

    The presence and distribution characteristics of microplastics become a big issue due to the adverse effects on marine organisms caused by not only microplastics but any incorporated and/or adsorbed pollutants. Distribution of microplastics (50- to 5000-μm size) was determined for three sandy beaches on an isolated island in a high-tidal costal region to elucidate spatial distributions in relation to beach locations. The abundances of microplastics (n = 21) measured were 56-285,673 (46,334 ± 71,291) particles/m(2) corresponding to the highest level globally. Out of observed polymer types, expanded polystyrene was overwhelmingly dominant. Although lying toward the estuary of the largest river in the country, the north-side beach contained a 100-fold lower abundance than two south-side beaches that faced southerly wind and currents that were prevalent throughout the study season. In addition, distinct differences between the beaches on either side were also present in terms of size distribution and spatial homogeneity of microplastics on the same beach. Winds and currents are therefore considered to be the driving forces in the distribution of microplastics.

  13. A randomized comparison of daunorubicin 90 mg/m2 vs 60 mg/m2 in AML induction

    DEFF Research Database (Denmark)

    Burnett, A. K.; Russell, N. H.; Hills, R. K.

    2015-01-01

    remission rate (73% vs 75%; odds ratio, 1.07 [0.83-1.39]; P = .6) or in any recognized subgroup. The 60-day mortality was increased in the 90 mg/m(2) arm (10% vs 5% (hazard ratio [HR] 1.98 [1.30-3.02]; P = .001), which resulted in no difference in overall 2-year survival (59% vs 60%; HR, 1.16 [0.95-1.43]; P...... recommended as a standard of care. However, 60 mg/m(2) is widely used and has never been directly compared with 90 mg/m(2). As part of the UK National Cancer Research Institute (NCRI) AML17 trial, 1206 adults with untreated AML or high-risk myelodysplastic syndrome, mostly younger than 60 years of age, were...... randomized to a first-induction course of chemotherapy, which delivered either 90 mg/m(2) or 60 mg/m(2) on days 1, 3, and 5 combined with cytosine arabinoside. All patients then received a second course that included daunorubicin 50 mg/m(2) on days 1, 3, and 5. There was no overall difference in complete...

  14. The challenges of M2M massive access in wireless cellular networks

    Directory of Open Access Journals (Sweden)

    Andrea Biral

    2015-02-01

    Full Text Available The next generation of communication systems, which is commonly referred to as 5G, is expected to support, besides the traditional voice and data services, new communication paradigms, such as Internet of Things (IoT and Machine-to-Machine (M2M services, which involve communication between Machine-Type Devices (MTDs in a fully automated fashion, thus, without or with minimal human intervention. Although the general requirements of 5G systems are progressively taking shape, the technological issues raised by such a vision are still partially unclear. Nonetheless, general consensus has been reached upon some specific challenges, such as the need for 5G wireless access networks to support massive access by MTDs, as a consequence of the proliferation of M2M services. In this paper, we describe the main challenges raised by the M2M vision, focusing in particular on the problems related to the support of massive MTD access in current cellular communication systems. Then we analyze the most common approaches proposed in the literature to enable the coexistence of conventional and M2M services in the current and next generation of cellular wireless systems. We finally conclude by pointing out the research challenges that require further investigation in order to provide full support to the M2M paradigm.

  15. Storm surge and tidal range energy

    Science.gov (United States)

    Lewis, Matthew; Angeloudis, Athanasios; Robins, Peter; Evans, Paul; Neill, Simon

    2017-04-01

    The need to reduce carbon-based energy sources whilst increasing renewable energy forms has led to concerns of intermittency within a national electricity supply strategy. The regular rise and fall of the tide makes prediction almost entirely deterministic compared to other stochastic renewable energy forms; therefore, tidal range energy is often stated as a predictable and firm renewable energy source. Storm surge is the term used for the non-astronomical forcing of tidal elevation, and is synonymous with coastal flooding because positive storm surges can elevate water-levels above the height of coastal flood defences. We hypothesis storm surges will affect the reliability of the tidal range energy resource; with negative surge events reducing the tidal range, and conversely, positive surge events increasing the available resource. Moreover, tide-surge interaction, which results in positive storm surges more likely to occur on a flooding tide, will reduce the annual tidal range energy resource estimate. Water-level data (2000-2012) at nine UK tide gauges, where the mean tidal amplitude is above 2.5m and thus suitable for tidal-range energy development (e.g. Bristol Channel), were used to predict tidal range power with a 0D modelling approach. Storm surge affected the annual resource estimate by between -5% to +3%, due to inter-annual variability. Instantaneous power output were significantly affected (Normalised Root Mean Squared Error: 3%-8%, Scatter Index: 15%-41%) with spatial variability and variability due to operational strategy. We therefore find a storm surge affects the theoretical reliability of tidal range power, such that a prediction system may be required for any future electricity generation scenario that includes large amounts of tidal-range energy; however, annual resource estimation from astronomical tides alone appears sufficient for resource estimation. Future work should investigate water-level uncertainties on the reliability and

  16. Dynamics of Tidally Captured Planets in the Galactic Center

    Science.gov (United States)

    Trani, Alessandro A.; Mapelli, Michela; Spera, Mario; Bressan, Alessandro

    2016-11-01

    Recent observations suggest ongoing planet formation in the innermost parsec of the Galactic center. The supermassive black hole (SMBH) might strip planets or planetary embryos from their parent star, bringing them close enough to be tidally disrupted. Photoevaporation by the ultraviolet field of young stars, combined with ongoing tidal disruption, could enhance the near-infrared luminosity of such starless planets, making their detection possible even with current facilities. In this paper, we investigate the chance of planet tidal captures by means of high-accuracy N-body simulations exploiting Mikkola's algorithmic regularization. We consider both planets lying in the clockwise (CW) disk and planets initially bound to the S-stars. We show that tidally captured planets remain on orbits close to those of their parent star. Moreover, the semimajor axis of the planetary orbit can be predicted by simple analytic assumptions in the case of prograde orbits. We find that starless planets that were initially bound to CW disk stars have mild eccentricities and tend to remain in the CW disk. However, we speculate that angular momentum diffusion and scattering by other young stars in the CW disk might bring starless planets into orbits with low angular momentum. In contrast, planets initially bound to S-stars are captured by the SMBH on highly eccentric orbits, matching the orbital properties of the clouds G1 and G2. Our predictions apply not only to planets but also to low-mass stars initially bound to the S-stars and tidally captured by the SMBH.

  17. Sediment rarefaction resuspension and contaminant release under tidal curren- ts

    Institute of Scientific and Technical Information of China (English)

    程鹏达; 朱红伟; 钟宝昌; 王道增

    2014-01-01

    Based on experiment in tidal flume, this paper analyzes the sediment rarefactive phenomenon and hydraulic characteristics of sediment resuspension with different physical properties under the effect of tidal current. According to this experiment, sediment resuspension is related to the hydraulic characteristics of overlying water and its own dry density, namely the moisture content of sediment and deposition time. Generally, river sediment can be classified into the upper layer of floating sludge and lower layer of deposit sediment. Incipient velocity goes higher as the sediment layer goes thicker. Based on the experiment, incipient velocity formula of sediment can be obtained. There is a cohesive force among natural fine sediment whose resuspension is almost irrelevant to their diameters. Therefore, the critical incipient velocity is determined by the cohesive force instead of particle diameter. The lower layer of deposit sediment is generally not so easy to start up. And it will be rarified and release into the overlying water when contacting with overlying water. However, this rarefaction release velocity is gentle and slow. Under the same flow condition, annual loss amount of lower layer deposited sediment is about one fifth of upper layer of floating sediment. Flow velocity of tidal river and variation of the water level are asymmetrical, both of which vary under different tidal cycles. During long tidal cycle, flow velocity and water level change in the same phase and amplitude with tide. During the whole ebb and flow, flow direction does not change as the water level goes under the influence of acceleration and deceleration. As the tide cycle increases, the incipient velocity of sediment goes higher. This means that the long period tide cycle plays buffer effect on the resuspension of sediment, which makes the sediment not so easy both to start up and to suspend.

  18. Observations of ebb flows on tidal flats: Evidence of dewatering?

    Science.gov (United States)

    Rinehimer, J. P.; Thomson, J. M.; Chickadel, C.

    2010-12-01

    Incised channels are a common morphological feature of tidal flats. When the flats are inundated, flows are generally forced by the tidally varying sea surface height. During low tide, however, these channels continue to drain throughout flat exposure even without an upstream source of water. While the role of porewater is generally overlooked due to the low permeability of marine muds, it remains the only potential source of flows through the channels during low tide. In situ and remotely sensed observations (Figure 1) at an incised channel on a tidal flat in Willapa Bay from Spring 2010 indicate that dewatering of the flats may be driving these low tide flows. High resolution Aquadopp ADCP velocity profiles are combined with observations from tower-based infrared (IR) video to produce a complete time series of surface velocity measurements throughout low tide. The IR video observations provide a measurement of surface currents even when the channel depth is below the blanking distance of the ADCP (10 cm). As the depth within the channel drops from 50 cm to 10 cm surface velocities increase from 10 cm/s to 60 cm/s even as the tide level drops below the channel flanks and the flats are dry. As the drainage continues, the temperature of the flow rises throughout low tide, mirroring temperatures within the sediment bed on the tidal flat. Drainage salinity falls despite the lack of any freshwater input to the flat indicating that less saline porewater may be the source. The likely source of the drainage water is from the channel flanks where time-lapse video shows slumping and compaction of channel sediments. Velocity profiles, in situ temperatures, and IR observations also are consistent with the presence of fluid muds and a hyperpycnal, density driven outflow at the channel mouth highlighting a possible pathway for sediment delivery from the flats to the main distributary channels of the bay. Figure 1: Time series of tidal flat channel velocities and temperatures

  19. Inferring tidal wetland stability from channel sediment fluxes: observations and a conceptual model

    Science.gov (United States)

    Ganju, Neil K.; Nidzieko, Nicholas J.; Kirwan, Matthew L.

    2013-01-01

    Anthropogenic and climatic forces have modified the geomorphology of tidal wetlands over a range of timescales. Changes in land use, sediment supply, river flow, storminess, and sea level alter the layout of tidal channels, intertidal flats, and marsh plains; these elements define wetland complexes. Diagnostically, measurements of net sediment fluxes through tidal channels are high-temporal resolution, spatially integrated quantities that indicate (1) whether a complex is stable over seasonal timescales and (2) what mechanisms are leading to that state. We estimated sediment fluxes through tidal channels draining wetland complexes on the Blackwater and Transquaking Rivers, Maryland, USA. While the Blackwater complex has experienced decades of degradation and been largely converted to open water, the Transquaking complex has persisted as an expansive, vegetated marsh. The measured net export at the Blackwater complex (1.0 kg/s or 0.56 kg/m2/yr over the landward marsh area) was caused by northwesterly winds, which exported water and sediment on the subtidal timescale; tidally forced net fluxes were weak and precluded landward transport of suspended sediment from potential seaward sources. Though wind forcing also exported sediment at the Transquaking complex, strong tidal forcing and proximity to a turbidity maximum led to an import of sediment (0.031 kg/s or 0.70 kg/m2/yr). This resulted in a spatially averaged accretion of 3.9 mm/yr, equaling the regional relative sea level rise. Our results suggest that in areas where seaward sediment supply is dominant, seaward wetlands may be more capable of withstanding sea level rise over the short term than landward wetlands. We propose a conceptual model to determine a complex's tendency toward stability or instability based on sediment source, wetland channel location, and transport mechanisms. Wetlands with a reliable portfolio of sources and transport mechanisms appear better suited to offset natural and

  20. Coastal Currents with Along-Track Interferometry

    NARCIS (Netherlands)

    Greidanus, H.S.F.; Bree, R.J.P. van; Huising, E.J.; Vogelzang, J.; Vaessen, E.M.J.

    1999-01-01

    Airborne radar along-track interferometric measurements of a coastal area with a complex tidal flow pattern are analyzed. The results are compared with a current field computed from a tidal model. Using wave-current interaction modeling, a radar backscatter image is simulated based on the measured c

  1. M2-F1 on lakebed with pilot Milt Thompson

    Science.gov (United States)

    1963-01-01

    NASA Flight Research Pilot Milt Thompson, shown here on the lakebed with the M2-F1 lifting body, was an early backer of R. Dale Reed's lifting-body proposal. He urged Flight Research Center director Paul Bikle to approve the M2-F1's construction. Thompson also made the first glide flights in both the M2-F1 and its successor, the heavyweight M2-F2. The wingless, lifting body aircraft design was initially conceived as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, NASA Flight Research Center (later Dryden Flight Research Center, Edwards, CA) management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a 'flying bathtub,' and was designated the M2-F1, the 'M' referring to 'manned' and 'F' referring to 'flight' version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. This vehicle needed to be able to tow the M2-F1 on the Rogers Dry Lakebed adjacent to NASA's Flight Research Center (FRC) at a minimum speed of 100 miles per hour. To do that, it had to handle the 400-pound pull of the M2-F1. Walter 'Whitey' Whiteside, who was a retired Air Force maintenance officer working in the FRC's Flight Operations Division, was a dirt-bike rider and hot-rodder. Together with Boyden 'Bud' Bearce in the Procurement and Supply Branch of the FRC, Whitey acquired a Pontiac Catalina convertible with the largest engine available. He took the car to Bill Straup's renowned hot-rod shop near Long Beach for modification. With a special gearbox and racing slicks, the Pontiac could tow the 1,000-pound M2-F1 110 miles per hour in 30 seconds. It proved

  2. Tidal Tales of Minor Mergers: Star Formation in the Tidal Debris of Minor Mergers

    CERN Document Server

    Knierman, Karen A

    2009-01-01

    How does the tidal debris of minor galaxy mergers contribute to structures in spiral galaxies or in the intergalactic medium? While major mergers are known to create structures such as tidal dwarf galaxies and star clusters within their tidal debris, less is known about minor mergers (mass ratios between a dwarf galaxy and disk galaxy of less than one-third) and their tidal debris. This work surveys 6 nearby minor mergers using optical broad-band and H-alpha narrow-band imaging to characterize star formation in their tidal debris. Young star clusters with ages less than the dynamical age of the tidal tails are found in all 6 mergers, indicating that the star clusters formed in situ. Even if minor mergers contribute less tidal debris per interaction than major mergers, they are more common and possibly contribute structure to all types of galaxies and to the intergalactic medium throughout the history of the universe.

  3. CEMS-investigations of AISI M2 steel after nitrogen plasma immersion ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Uglov, V.V. E-mail: info@research.bsu.unibel.by; Kholmetskii, A.L.; Kuleshov, A.K.; Fedotova, J.A.; Rusalsky, D.P.; Khodasevich, V.V.; Ruebenbauer, K.; Richter, E.; Guenzel, R.; Parascandola, S

    1999-01-02

    Plasma-immersion ion implantation (PIII) and high-current ion implantation (HCII) of nitrogen into M2 steel were carried out. The formation of a multilayer system consisting of a surface layer of austenite on top of {epsilon}-Fe{sub 3}N nitride precipitates was manifested in M2 steel after PIII. HCII forms a thick (more than 14 {mu}m) layer with {epsilon}-Fe{sub 3}N precipitates. Apparently, the formation of the austenite layer after PIII is connected with a local tempering of the steel surface by the pulsed nitrogen ion beam.

  4. Tidal deformations of a spinning compact object

    CERN Document Server

    Pani, Paolo; Maselli, Andrea; Ferrari, Valeria

    2015-01-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the multipole mom...

  5. Relativistic theory of tidal Love numbers

    CERN Document Server

    Binnington, Taylor

    2009-01-01

    In Newtonian gravitational theory, a tidal Love number relates the mass multipole moment created by tidal forces on a spherical body to the applied tidal field. The Love number is dimensionless, and it encodes information about the body's internal structure. We present a relativistic theory of Love numbers, which applies to compact bodies with strong internal gravities; the theory extends and completes a recent work by Flanagan and Hinderer, which revealed that the tidal Love number of a neutron star can be measured by Earth-based gravitational-wave detectors. We consider a spherical body deformed by an external tidal field, and provide precise and meaningful definitions for electric-type and magnetic-type Love numbers; and these are computed for polytropic equations of state. The theory applies to black holes as well, and we find that the relativistic Love numbers of a nonrotating black hole are all zero.

  6. Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data through Satellite Gradiometry

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

    2016-01-01

    Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semi-diurnal tidal constituents were estimated through a “Comprehensive Inversion" of the first 20.5 months of magnetic measurements from ESA's Swarm satellite constellation mission. While the con...

  7. Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data through Satellite Gradiometry

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

    2016-01-01

    Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semi-diurnal tidal constituents were estimated through a “Comprehensive Inversion" of the first 20.5 months of magnetic measurements from ESA's Swarm satellite constellation mission. While the con...

  8. Laboratory observations of velocity and density fields in the entrance of a harbor on a stratified tidal river

    NARCIS (Netherlands)

    Langendoen, E.J.; Karelse, M.

    1990-01-01

    Detailed measurements are presented of velocity and density fields in the entrance of a model harbor on a stratified tidal river. Three geometries of the harbor entrance were examined, (1) a harbor with its length axis perpendicular to the river and an entrance width of 1 m, (2) as (1) but with an

  9. A method for using shoreline morphology to predict suspended sediment concentration in tidal creeks

    Science.gov (United States)

    Ensign, Scott; Currin, Carolyn; Piehler, Michael; Tobias, Craig

    2017-01-01

    Improving mechanistic prediction of shoreline response to sea level rise is currently limited by 1) morphologic complexity of tidal creek shorelines that confounds application of mechanistic models, and 2) availability of suspended sediment measurements to parameterize mechanistic models. To address these challenges we developed a metric to distinguish two morphodynamic classes of tidal creek and tested whether this metric could be used to predict suspended sediment concentration. We studied three small tidal creeks in North Carolina, U.S.A. We collected suspended sediment at one non-tidal and two tidal sites in each creek and measured the wetland and channel width using a geographic information system. In each creek, tidal harmonics were measured for one year, sediment accretion on the salt marsh was measured for three years, and shoreline erosion was measured from aerial photographs spanning 50 years. Additional total suspended solids measurements from seven creeks reported in a national database supplemented our analysis. Among the three intensively studied creeks, shoreline erosion was highest in the most embayed creek (having a wider channel than the width of adjoining wetlands) and lowest in the wetland-dominated creek (having a channel narrower than the width of adjoining wetlands). Wetland sediment accretion rate in the wetland-dominated creek was four times higher than the accretion in the embayed creek. The wetland-dominated tidal creek had over twice the suspended sediment as the most embayed creek. Based on these results, we conclude that our metric of embayed and contrasting wetland-dominated creek morphology provides a guide for choosing between two types of morphodynamic models that are widely used to predict wetland shoreline change. This metric also allowed us to parse the 10 tidal creeks studied into two groups with different suspended sediment concentrations. This relationship between suspended sediment concentration and creek morphology provides

  10. Spatial-temporal changes of tidal flats in the Huanghe River Delta using Landsat TM/ETM+ images%黄河三角洲潮滩潮沟近期变化遥感监测

    Institute of Scientific and Technical Information of China (English)

    樊辉; 黄海军

    2004-01-01

    Integrating remote sensing, geographic information system (GIS) and fractal theory, change characteristics of tidal flats and tidal creeks in the Huanghe (Yellow) River Delta over the period of 1986-2001 were discussed. The results show that evolutions of tidal flats throughout the Huanghe River Delta are influenced by various factors, and that progressive succession and regression of tidal flats concur in different coastal segments of the delta. Human activities have played an increasingly important role in the succession process of tidal flats. Due to land reclamation in coastal zones of the delta in the last 15 years, lots of tidal flats were occupied, the artificial coastline migrated seaward (the maximum change rate was 0.8 kmyr-1) and tidal creeks became sparser (the highest decreasing rate of length of tidal creeks was 14.9 kmyr-1). Except for two coastal segments from the Tiaohe Estuary to the 106 Station and from the south of the Huanghe River mouth to the north of the Xiaodao River Estuary,fractal dimension values of tidal creeks in the remaining coastal segments of the delta decreased. In addition, the time dimension, sediment fluxes into the sea, waves and tidal-currents have profound influences on the evolution process of tidal flats. Four types of tidal flats-river-dominated tidal flats,tide-dominated tidal flats, wave-dominated tidal flats and man-dominated tidal flats can be identified.Owing to the intensification of human activities in coastal zones of the delta, man-dominated tidal flats have become the main kind of tidal flats.

  11. M2磁带机挑战极限

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    日前安百特(Exabyte)公司宣布,其OEM合作伙伴Cybernetics在对Mammoth-2(M2)磁带机的性能和可靠性测试中取得了创记录的结果,从而加快了M2的商业交付计划。M2磁带机以部门级价格提供了企业级的性能,其容量增加50%,达到60GB,性能提高一倍,传输率达到12MB/s,可在一小时内备份43GB数据(未压缩)。Cybernetics利用该公司为了故意“破坏”磁带机而创建的定制软件对M2进行了测试,包括读/写能力测试、

  12. Dimeric Complexes of Tryptophan with M2+ Metal Ions

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Polfer, N. C.; Oomens, J.

    2009-01-01

    IRMPD spectroscopy using the FELIX free electron laser and a Fourier transform ICR mass spectrometer was used to characterize the structures of electrosprayed dimer complexes M(2+)Trp(2) of tryptophan with a series of eight doubly charged metal ions, including alkaline earths Ca, Sr, and Ba, and tra

  13. M2e-Based Universal Influenza A Vaccines

    Directory of Open Access Journals (Sweden)

    Lei Deng

    2015-02-01

    Full Text Available The successful isolation of a human influenza virus in 1933 was soon followed by the first attempts to develop an influenza vaccine. Nowadays, vaccination is still the most effective method to prevent human influenza disease. However, licensed influenza vaccines offer protection against antigenically matching viruses, and the composition of these vaccines needs to be updated nearly every year. Vaccines that target conserved epitopes of influenza viruses would in principle not require such updating and would probably have a considerable positive impact on global human health in case of a pandemic outbreak. The extracellular domain of Matrix 2 (M2e protein is an evolutionarily conserved region in influenza A viruses and a promising epitope for designing a universal influenza vaccine. Here we review the seminal and recent studies that focused on M2e as a vaccine antigen. We address the mechanism of action and the clinical development of M2e-vaccines. Finally, we try to foresee how M2e-based vaccines could be implemented clinically in the future.

  14. Progress On 58m2 Passive Resonant Ring Laser Gyroscope

    Science.gov (United States)

    Shaw, G. L.; Rotge, J.; Simmons, B. J.

    1986-01-01

    An update of the large area (now 60m2) Passive Resonant Ring Laser Gyro (PRRLG) is given. Some aspects of last year's design have changed; but performance is still predicted to be in the 10-10 earth rate unit (ERU) range. This is of interest for a number of geophysical applications.

  15. A Novel Voltage Sensor in the Orthosteric Binding Site of the M2 Muscarinic Receptor.

    Science.gov (United States)

    Barchad-Avitzur, Ofra; Priest, Michael F; Dekel, Noa; Bezanilla, Francisco; Parnas, Hanna; Ben-Chaim, Yair

    2016-10-04

    G protein-coupled receptors (GPCRs) mediate many signal transduction processes in the body. The discovery that these receptors are voltage-sensitive has changed our understanding of their behavior. The M2 muscarinic acetylcholine receptor (M2R) was found to exhibit depolarization-induced charge movement-associated currents, implying that this prototypical GPCR possesses a voltage sensor. However, the typical domain that serves as a voltage sensor in voltage-gated channels is not present in GPCRs, making the search for the voltage sensor in the latter challenging. Here, we examine the M2R and describe a voltage sensor that is comprised of tyrosine residues. This voltage sensor is crucial for the voltage dependence of agonist binding to the receptor. The tyrosine-based voltage sensor discovered here constitutes a noncanonical by which membrane proteins may sense voltage.

  16. Ambient Noise in an Urbanized Tidal Channel

    Science.gov (United States)

    Bassett, Christopher

    In coastal environments, when topographic and bathymetric constrictions are combined with large tidal amplitudes, strong currents (> 2 m/s) can occur. Because such environments are relatively rare and difficult to study, until recently, they have received little attention from the scientific community. However, in recent years, interest in developing tidal hydrokinetic power projects in these environments has motivated studies to improve this understanding. In order to support an analysis of the acoustic effects of tidal power generation, a multi-year study was conducted at a proposed project site in Puget Sound (WA) are analyzed at a site where peak currents exceeded 3.5 m/s. From these analyses, three noise sources are shown to dominate the observed variability in ambient noise between 0.02-30 kHz: anthropogenic noise from vessel traffic, sediment-generated noise during periods of strong currents, and flow-noise resulting from turbulence advected over the hydrophones. To assess the contribution of vessel traffic noise, one calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site in northern Admiralty Inlet. The variability in spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband and M-weighted sound pressure levels is driven largely by vessel traffic. Within the one-year study period, at least one AIS transmitting vessel is present in the study area 90% of the time and over 1,363 unique vessels are recorded. A noise budget for vessels equipped with AIS transponders identifies cargo ships, tugs, and passenger vessels as the largest contributors to noise levels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessel types yields a cumulative probability density function of broadband sound pressure

  17. Internal steel structure of M2-F1

    Science.gov (United States)

    1963-01-01

    The internal steel structure for the M2-F1 was built at the Flight Research Center (predecessor of the Dryden Flight Research Center, Edwards, CA) in a section of the calibration hangar dubbed 'Wright Bicycle Shop.' Visible are the stick, rudder pedals, and ejection seat. The external wooden shell was attached to the steel structure. The wingless, lifting body aircraft design was initially conceived as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, Dryden management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a 'flying bathtub,' and was designated the M2-F1, the 'M' referring to 'manned' and 'F' referring to 'flight' version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. This vehicle needed to be able to tow the M2-F1 on the Rogers Dry Lakebed adjacent to NASA's Flight Research Center (FRC) at a minimum speed of 100 miles per hour. To do that, it had to handle the 400-pound pull of the M2-F1. Walter 'Whitey' Whiteside, who was a retired Air Force maintenance officer working in the FRC's Flight Operations Division, was a dirt-bike rider and hot-rodder. Together with Boyden 'Bud' Bearce in the Procurement and Supply Branch of the FRC, Whitey acquired a Pontiac Catalina convertible with the largest engine available. He took the car to Bill Straup's renowned hot-rod shop near Long Beach for modification. With a special gearbox and racing slicks, the Pontiac could tow the 1,000-pound M2-F1 110 miles per hour in 30 seconds. It proved adequate for the roughly 400 car tows that got the M2-F1 airborne to prove it could fly

  18. Tidal energy conversion. Renewable energy; 3-3 choseki / choryu hatsuden. II. saisei kano energy ni yoru hatsuden

    Energy Technology Data Exchange (ETDEWEB)

    Makino, T. [Tobishima Corp., Tokyo (Japan)

    1998-10-15

    There are not much examples applying tidal energy conversion, but tide and tidal current phenomena can be forecasted so correctly regardless of weather that the applying tidal energy is to be expected in the future. The largest tidal power plant is at Reims in France and install 24 Kaplan turbines each of which outlet power is 10,000kW (rotational direction is reversible) on the breakwater (750m is length). Tidal range at this place being 8.5m on an average, during the period of flowing seawater into the reservoir and on the contrary during the period of discharging seawater to the sea generation is both performed. Though there is no actual result of tidal power plant in Japan, in tidal current power system experimental generators have been installed at Kurushima channel and Naruto channel. Nihon University carried out various kinds of experiment using a Darius turbine (1.6m in dia.) at Kurushima channel and got outlet power of 3kW at the maximum (1983-`88). There are few coasts which have sufficient tide range in Japan, but there are so good many applicable coasts in China and Southeast Asia that the tidal power generation is to be expectatively. 12 refs., 5 figs., 1 tab.

  19. The Sagittarius Dwarf Galaxy Tidal Debris in the south Galactic Cap

    Science.gov (United States)

    Thompson, Jeffery; Newby, M.; Newberg, H. J.; Desell, T.

    2014-01-01

    We characterize the spatial properties of the Sagittarius dwarf galaxy tidal debris, both primary and secondary (bifurcated) tidal tails, in the south Galactic cap. The Sagittarius dwarf galaxy is currently being ripped apart by tidal forces from the Milky Way galaxy. The spatial density of turnoff stars from the Sloan Digital Sky Survey Data Release 8 are fit using statistical photometric parallax with half a petaFLOPS of computing power from the MilkyWay@home volunteer computing platform. The secondary tail appears to be significantly wider than the originally detected primary tail. These results are compared with the leading tidal tail stream density measured in the north Galactic cap. This research was funded by NSF grant AST 10-09670.

  20. Tidal Tails around the Outer Halo Globular Clusters Eridanus and Palomar 15

    Science.gov (United States)

    Myeong, G. C.; Jerjen, Helmut; Mackey, Dougal; Da Costa, Gary S.

    2017-05-01

    We report the discovery of tidal tails around the two outer halo globular clusters, Eridanus and Palomar 15, based on gi-band images obtained with DECam at the CTIO 4 m Blanco Telescope. The tidal tails are among the most remote stellar streams currently known in the Milky Way halo. Cluster members have been determined from the color-magnitude diagrams and used to establish the radial density profiles, which show, in both cases, a strong departure in the outer regions from the best-fit King profile. Spatial density maps reveal tidal tails stretching out on opposite sides of both clusters, extending over a length of ˜760 pc for Eridanus and ˜1160 pc for Palomar 15. The great circle projected from the Palomar 15 tidal tails encompasses the Galactic Center, while that for Eridanus passes close to four dwarf satellite galaxies, one of which (Sculptor) is at a comparable distance to that of Eridanus.

  1. Star Formation in NGC4532/DDO 137'S Tidal Dwarf Galaxies and 500 KPC HI Stream

    Science.gov (United States)

    Higdon, Sarah

    Mergers and close-passages between gas rich galaxies can result in the formation of long HI/stellar streams. The tidally induced star formation and gas concentrations can result in the creation of tidal dwarf galaxies (TDGs). TDGs may contribute significantly to the dwarf galaxy population, by far the most common galaxy type in the current epoch. We have discovered one of the longest known tidal streams (500 kpc) in the NGC 4535/DDO 137 system. We propose 3 ksec FUV/NUV images centered on the stream and its five TDGs. We will readily detect faint/low mass star forming regions (~2E-17 erg s-1 cm-2 A-1) to 5-sigma. The GALEX observations are a unique opportunity to undertake a sensitive and comprehensive study of tidally induced star formation, dwarf galaxy formation and inter-galactic enrichment in this system.

  2. Prophylactic and therapeutic activity of fully human monoclonal antibodies directed against Influenza A M2 protein

    Directory of Open Access Journals (Sweden)

    Gwerder Myriam

    2009-12-01

    Full Text Available Abstract Influenza virus infection is a prevalent disease in humans. Antibodies against hemagglutinin have been shown to prevent infection and hence hemagglutinin is the major constituent of current vaccines. Antibodies directed against the highly conserved extracellular domain of M2 have also been shown to mediate protection against Influenza A infection in various animal models. Active vaccination is generally considered the best approach to combat viral diseases. However, passive immunization is an attractive alternative, particularly in acutely exposed or immune compromized individuals, young children and the elderly. We recently described a novel method for the rapid isolation of natural human antibodies by mammalian cell display. Here we used this approach to isolate human monoclonal antibodies directed against the highly conserved extracellular domain of the Influenza A M2 protein. The identified antibodies bound M2 peptide with high affinities, recognized native cell-surface expressed M2 and protected mice from a lethal influenza virus challenge. Moreover, therapeutic treatment up to 2 days after infection was effective, suggesting that M2-specific monoclonals have a great potential as immunotherapeutic agents against Influenza infection.

  3. Tidal Tails in Interacting Galaxies: Formation of Compact Stellar Structures

    CERN Document Server

    Mullan, B; Konstantopoulos, I S; Bastian, N; Chandar, R; Durrell, P R; Elmegreen, D; English, J; Gallagher, S C; Gronwall, C; Hibbard, J E; Hunsberger, S; Johnson, K E; Kepley, A; Knierman, K; Koribalski, B; Lee, K H; Maybhate, A; Palma, C; Vacca, W D

    2009-01-01

    We have used V- and I- band images from the Hubble Space Telescope (HST) to identify compact stellar clusters within the tidal tails of twelve different interacting galaxies. The seventeen tails within our sample span a physical parameter space of HI/stellar masses, tail pressure and density through their diversity of tail lengths, optical brightnesses, mass ratios, HI column densities, stage on the Toomre sequence, and tail kinematics. Our preliminary findings in this study indicate that star cluster demographics of the tidal tail environment are compatible with the current understanding of star cluster formation in quiescent systems, possibly only needing changes in certain parameters or normalization of the Schechter cluster initial mass function (CIMF) to replicate what we observe in color-magnitude diagrams and a brightest absolute magnitude -- log N plot.

  4. Tidal dissipation in a homogeneous spherical body. I. Methods

    Energy Technology Data Exchange (ETDEWEB)

    Efroimsky, Michael; Makarov, Valeri V., E-mail: michael.efroimsky@usno.navy.mil, E-mail: vvm@usno.navy.mil [US Naval Observatory, 3450 Massachusetts Avenue NW, Washington, DC 20392 (United States)

    2014-11-01

    A formula for the tidal dissipation rate in a spherical body is derived from first principles to correct some mathematical inaccuracies found in the literature. The development is combined with the Darwin-Kaula formalism for tides. Our intermediate results are compared with those by Zschau and Platzman. When restricted to the special case of an incompressible spherical planet spinning synchronously without libration, our final formula can be compared with the commonly used expression from Peale and Cassen. However, the two turn out to differ, as in our expression the contributions from all Fourier modes are positive-definite, which is not the case with the formula from Peale and Cassen. Examples of the application of our expression for the tidal damping rate are provided in the work by Makarov and Efroimsky (Paper II) published back to back with the current paper.

  5. Dawes Review. The tidal downsizing hypothesis of planet formation

    CERN Document Server

    Nayakshin, Sergei

    2016-01-01

    Tidal Downsizing is the modern version of the Kuiper (1951) scenario of planet formation. Detailed simulations of self-gravitating discs, gas fragments, dust grain dynamics, and planet evolutionary calculations are summarised here and used to build a predictive planet formation model and population synthesis. A new interpretation of exoplanetary and debris disc data, the Solar System's origins, and the links between planets and brown dwarfs is offered. This interpretation is contrasted with the current observations and the predictions of the Core Accretion theory. Observations that can distinguish the two scenarios are pointed out. In particular, Tidal Downsizing predicts that presence of debris discs, sub-Neptune mass planets, planets more massive than $\\sim 5$~Jupiter masses and brown dwarfs should not correlate strongly with the metallicity of the host. For gas giants of $\\sim$ Saturn to a few Jupiter mass, a strong host star metallicity correlation is predicted only inwards of a few AU from the host. Comp...

  6. Tyrosine 129 of the murine gammaherpesvirus M2 protein is critical for M2 function in vivo.

    Directory of Open Access Journals (Sweden)

    Udaya S Rangaswamy

    Full Text Available A common strategy shared by all known gammaherpesviruses is their ability to establish a latent infection in lymphocytes--predominantly in B cells. In immunocompromised patients, such as transplant recipients or AIDS patients, gammaherpesvirus infections can lead to the development of lymphoproliferative disease and lymphoid malignancies. The human gamma-herpesviruses, EBV and KSHV, encode proteins that are capable of modulating the host immune signaling machinery, thereby subverting host immune responses. Murine gamma-herpesvirus 68 (MHV68 infection of laboratory strains of mice has proven to be useful small-animal model that shares important pathogenic strategies with the human gamma-herpesviruses. The MHV68 M2 protein is known to manipulate B cell signaling and, dependent on route and dose of virus inoculation, plays a role in both the establishment of latency and virus reactivation. M2 contains two tyrosines that are targets for phosphorylation, and have been shown to interact with the B cell signaling machinery. Here we describe in vitro and in vivo studies of M2 mutants which reveals that while both tyrosines Y120 and Y129 are required for M2 induction of IL-10 expression from primary murine B cells in vitro, only Y129 is critical for reactivation from latency and plasma cell differentiation in vivo.

  7. Tyrosine 129 of the murine gammaherpesvirus M2 protein is critical for M2 function in vivo.

    Science.gov (United States)

    Rangaswamy, Udaya S; O'Flaherty, Brigid M; Speck, Samuel H

    2014-01-01

    A common strategy shared by all known gammaherpesviruses is their ability to establish a latent infection in lymphocytes--predominantly in B cells. In immunocompromised patients, such as transplant recipients or AIDS patients, gammaherpesvirus infections can lead to the development of lymphoproliferative disease and lymphoid malignancies. The human gamma-herpesviruses, EBV and KSHV, encode proteins that are capable of modulating the host immune signaling machinery, thereby subverting host immune responses. Murine gamma-herpesvirus 68 (MHV68) infection of laboratory strains of mice has proven to be useful small-animal model that shares important pathogenic strategies with the human gamma-herpesviruses. The MHV68 M2 protein is known to manipulate B cell signaling and, dependent on route and dose of virus inoculation, plays a role in both the establishment of latency and virus reactivation. M2 contains two tyrosines that are targets for phosphorylation, and have been shown to interact with the B cell signaling machinery. Here we describe in vitro and in vivo studies of M2 mutants which reveals that while both tyrosines Y120 and Y129 are required for M2 induction of IL-10 expression from primary murine B cells in vitro, only Y129 is critical for reactivation from latency and plasma cell differentiation in vivo.

  8. Impacts of the reclamation project of Nanhui tidal flat on the currents and saltwater intrusion in the Changjiang estuary%长江口南汇边滩围垦工程对流场和盐水入侵的影响

    Institute of Scientific and Technical Information of China (English)

    李林江; 朱建荣

    2015-01-01

    考虑枯季一般状况的径流量和风况,数值计算和动力分析南汇边滩围垦工程对长江河口流场和盐水入侵的影响.南汇边滩围垦工程实施后,南槽喇叭口形状减小,改变了涨潮流和纳潮量.研究表明,围垦工程导致南槽大潮期间纳潮量减少13%,小潮期间减少16%,越过深水航道导堤的涨潮流减小;从南槽向北的越堤盐通量减小,导致北槽向海的盐通量减弱,中上段向陆的盐通量减弱,工程东南侧向陆的盐通量减弱,但因南槽口门处缩窄向陆的盐通量增强.围垦工程后南槽盐度锋面减弱,大潮期间南槽口门处和工程东南侧盐度上升,量值超过1.0;因纳潮量、越堤流和向陆盐通量减小,南槽中上段、北槽和横沙东滩盐度下降,量值超过0.5;北港和崇明东滩盐度上升,盐度超过0.5.小潮期间因潮动力减弱口门处的涨潮流和向陆盐通量减小,整个南槽盐度下降,量值超过1.5.因围垦工程后南槽盐度锋面减弱,阻挡径流进入南港的作用减弱,大潮和小潮期间北港净分流比略微减小,南槽的分流比大潮和小潮期间分别比工程前增加了1.57%和1.50%.%Considering the averaged river discharge and wind in dry season,the impacts of rec-lamation project of Nanhui tidal flat on the currents and saltwater intrusion were numerically cal-culated and dynamically analyzed.The funnel shape was reduced,flood current and tidal prism in the South Passage were changed after the reclamation project.The reclamation project resulted in tidal prism in the South Passage reducing 13% in spring tide and 16% in neap tide,and the flood currents spilling over the dikes of the deep water channel decreased;The northward salt fluxes spilling over the dykes from the South Passage were weakened which made the seaward salt flux in the North Passage reduced,the landward salt flux decreased the upper and

  9. No Snowball on Habitable Tidally Locked Planets

    Science.gov (United States)

    Checlair, Jade; Menou, Kristen; Abbot, Dorian S.

    2017-08-01

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin-orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  10. Tidal river dynamics: Implications for deltas

    Science.gov (United States)

    Hoitink, A. J. F.; Jay, D. A.

    2016-03-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity intrusion, a realm that can extend inland hundreds of kilometers. One key phenomenon resulting from this interaction is the emergence of large fortnightly tides, which are forced long waves with amplitudes that may increase beyond the point where astronomical tides have become extinct. These can be larger than the linear tide itself at more landward locations, and they greatly influence tidal river water levels and wetland inundation. Exploration of the spectral redistribution and attenuation of tidal energy in rivers has led to new appreciation of a wide range of consequences for fluvial and coastal sedimentology, delta evolution, wetland conservation, and salinity intrusion under the influence of sea level rise and delta subsidence. Modern research aims at unifying traditional harmonic tidal analysis, nonparametric regression techniques, and the existing understanding of tidal hydrodynamics to better predict and model tidal river dynamics both in single-thread channels and in branching channel networks. In this context, this review summarizes results from field observations and modeling studies set in tidal river environments as diverse as the Amazon in Brazil, the Columbia, Fraser and Saint Lawrence in North America, the Yangtze and Pearl in China, and the Berau and Mahakam in Indonesia. A description of state-of-the-art methods for a comprehensive analysis of water levels, wave propagation, discharges, and inundation extent in tidal rivers is provided. Implications for lowland river deltas are also discussed in terms of sedimentary deposits, channel bifurcation, avulsion, and salinity intrusion, addressing contemporary research challenges.

  11. Activation and dynamic network of the M2 muscarinic receptor

    OpenAIRE

    Miao, Yinglong; Nichols, Sara E.; Gasper, Paul M.; Metzger, Vincent T; McCammon, J. Andrew

    2013-01-01

    G-protein-coupled receptors (GPCRs) mediate cellular responses to various hormones and neurotransmitters and are important targets for treating a wide spectrum of diseases. Although significant advances have been made in structural studies of GPCRs, details of their activation mechanism remain unclear. The X-ray crystal structure of the M2 muscarinic receptor, a key GPCR that regulates human heart rate and contractile forces of cardiomyocytes, was determined recently in an inactive antagonist...

  12. Wilson Loops for M2- and M5-brane spaces

    CERN Document Server

    Quijada, Edward

    2015-01-01

    We calculate the quark and anti-quark interaction energy in different positions in spaces generated by $N$ coincident $M2$- and $M5$-branes. We use the Maldacena-Rey-Yee method for calculating this energy as a function of quark-antiquark separation. We obtain the solution for these problems as integrals of the metric elements. For limiting regimes we find simpler solutions for which some potentials exhibit a confinement behavior.

  13. Modelling of tidal hydrodynamics for a tropical ecosystem with implications for pollutant dispersion (Cochin Estuary, Southwest India)

    Digital Repository Service at National Institute of Oceanography (India)

    Balachandran, K.K.; Reddy, G.S.; Revichandran, C.; Srinivas, K.; Vijayan, P.R.; Thottam, T.J.

    Tidal circulation in the Cochin Estuary, a moderately polluted estuary along the southwest coast of India, was studied using a 2D hydrodynamic model. The predicted tides and currents showed very good agreement with measured tides. Particle...

  14. On the Tidal Dissipation of Obliquity

    CERN Document Server

    Rogers, T M

    2013-01-01

    We investigate tidal dissipation of obliquity in hot Jupiters. Assuming an initial random orientation of obliquity and parameters relevant to the observed population, the obliquity of hot Jupiters does not evolve to purely aligned systems. In fact, the obliquity evolves to either prograde, retrograde or 90^{o} orbits where the torque due to tidal perturbations vanishes. This distribution is incompatible with observations which show that hot jupiters around cool stars are generally aligned. This calls into question the viability of tidal dissipation as the mechanism for obliquity alignment of hot Jupiters around cool stars.

  15. A quasilocal calculation of tidal heating

    CERN Document Server

    Booth, I S; Booth, Ivan S.; Creighton, Jolien D. E.

    2000-01-01

    We present a method for computing the flux of energy through a closed surfacecontaining a gravitating system. This method, which is based on the quasilocalformalism of Brown and York, is illustrated by two applications: a calculationof (i) the energy flux, via gravitational waves, through a surface nearinfinity and (ii) the tidal heating in the local asymptotic frame of a bodyinteracting with an external tidal field. The second application represents thefirst use of the quasilocal formalism to study a non-stationary spacetime andshows how such methods can be used to study tidal effects in isolatedgravitating systems.

  16. Settlement, mortality and growth of the asari clam (Ruditapes philippinarum) for a collapsed population on a tidal flat in Nakatsu, Japan

    Science.gov (United States)

    Tezuka, Naoaki; Kamimura, Satomi; Hamaguchi, Masami; Saito, Hajime; Iwano, Hideki; Egashira, Junichi; Fukuda, Yuichi; Tawaratsumida, Takahiko; Nagamoto, Atsushi; Nakagawa, Koichi

    2012-04-01

    Although fluctuation and decline in bivalve populations have been reported worldwide, the underlying processes are not yet fully understood. This lack of understanding is partly due to an absence of demographic information for the early post-settlement period. This is the case particularly for annual production of the asari clam (also commonly known as the Manila clam, Ruditapes philippinarum) in Japan, which has greatly decreased in recent years. A remarkable decrease has been observed in the Nakatsu tidal flat, where current yields are less than 0.02% of the maximum yield. Possible explanations for this decline are: 1. limitation on recruitment due to overfishing; and 2. the demographic processes of growth and mortality have been altered by environmental changes, such as rise in seawater temperature or decrease in phytoplankton abundance. However, because of a lack of demographic information (e.g., the initial densities of larval settlement and mortality and growth rates post-settlement), the reasons for the decline, and the relative importance of each period in the life cycle in determining population abundance, remain unclear. Despite the decline, we observed high levels of recruitment of 0-year-class clams on the Nakatsu tidal flat in spring 2005, where more than 10,000 individuals m- 2 3-5 mm in shell length, estimated to have settled during the previous autumn, were observed. To obtain demographic information on the Nakatsu clams, we investigated two factors. First, we investigated the distribution of the 0-year-class clams and their rate of change in density as a combination of mortality, emigration and immigration on the whole tidal flat after a year. Second, we investigated the rate of change in the density and growth of clams after settlement in the center of the flat for 3 years. The rate of decrease in the density of the 0-year-class clams over the whole tidal flat after a year was greater at the stations where the initial density was higher. This

  17. In situ measurements of shear stress, erosion and deposition in man-made tidal channels within a tidal saltmarsh

    Science.gov (United States)

    Pieterse, Aline; Puleo, Jack A.; McKenna, Thomas E.; Figlus, Jens

    2017-06-01

    A field study was conducted in man-made ditches in a tidal saltmarsh in Lewes, Delaware, USA. Ditches are prevalent throughout tidal marshes along the Atlantic US coast, and influence hydrodynamics and sediment transport. The field study focused on measuring near-bed velocity, shear stress, sediment concentration, and bed level variability at 5 stations over a 3-week period. Velocities in the ditch (2-5 m wide, 1 m deep) peaked between 0.4 and 0.6 m/s and were slightly ebb dominated. Velocity and shear stress were maximum during a storm event, with peak shear stresses of 2 N/m2. Bed levels were estimated from acoustic amplitude return of a downward-looking velocity profiler. The bed level in the ditch at the landward locations increased ∼ 0.03 m over 3 weeks, while there was ∼ 0.01 m bed level decrease at the most seaward site suggesting a net import of sediment into the channel. At all sites, erosion (∼ 0.005-0.015 m) occurred during the accelerating phase of the flood tide, and accretion of a similar magnitude occurred during the decelerating phase of the ebb tide. This erosion-deposition sequence resulted in small net changes in bed level at the end of each tidal cycle. The intratidal behavior of the bed level was simulated using erosion and deposition flux equations based on shear stress, critical shear stress, and suspended sediment concentration. Erosion was predicted well with RMS errors on the order of 2 ṡ10-3 m. The bed level during the deposition phase could not be reproduced using the simple approach. Model inaccuracies for deposition were attributed to advection and variations in fall velocity due to flocculation that were not modeled due to lack of ground-truth observations.

  18. Downstream hydraulic geometry of a tidally influenced river delta

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Brye, de B.; Deleersnijder, E.

    2012-01-01

    Channel geometry in tidally influenced river deltas can show a mixed scaling behavior between that of river and tidal channel networks, as the channel forming discharge is both of river and tidal origin. We present a method of analysis to quantify the tidal signature on delta morphology, by extendin

  19. The change of characteristics of tidal wave in the Changjiang River mouth area since the post-glacial transgression maximum

    Institute of Scientific and Technical Information of China (English)

    朱玉荣

    2001-01-01

    During the period of the post-glacial transgression maximum (PGTM), there was a huge trumpet estuary in the modern Changjiang River Delta area. The location and the shape of the Paleo-Changjiang River Estuary (PCRE) were much different from those of the present Chang-Jiang River Estuary. The study on the change of characteristics of tidal wave in the Changjiang River mouth area since the PGTM can help to understand better the dynamic development of the Changjiang River Delta. The course curves of tidal level and tidal current velocity during a single tidal cycle for 35 points are calculated, and characteristics of tidal waves in the PCRE and its adjacent area are compared with those of tidal waves in the modern Changjiang River mouth area. The results show that the tidal waves within the PCRE and in its adjacent area during the period of the PGTM belonged to standing wave or a mixture of standing wave and progressive wave. Since then, the tidal wave in the Changjiang River mouth become gradually to be pr

  20. Trans World Tidal Gravity Profile.

    Science.gov (United States)

    1976-12-01

    PROFILE FIJI-ISLANDS STATION SUVA — VU NI KAWA I STATION 4460 SUVA — VUN IKA WA I VERTICAL COMPONENT V III LEVU — F IJ I MINERAL RESO URCES D IVISION R...1470.99 M I N , CORREC TION 0 ATT ENUATION DIFFERENT IFLLE M2/O1 1.00922 / MODELE 2/ GEO 765 76 4 4 76 4 4 76 4 9 76 4 11 76 4 14 76 5 10 GE O 765 76 5 1...ENT IELLE M2/O1 1.01611 / MODELE 2/ LCR 336 76 4 11 76 4 21 76 4 25 76 5 3 76 5 7 76 5 7 LCR 336 76 5 12 76 5 20 76 5 22 76 5 2? 76 5 25 76 6 4 LCR 336

  1. Analysis on hydrodynamic performances of a tidal current energy conversion device-flexible vane turbine%潮流能柔性叶片水轮机水动力学特性分析

    Institute of Scientific and Technical Information of China (English)

    王树杰; 李华军; 李冬; 鹿兰帅; 单忠德; 赵龙武

    2009-01-01

    The paper puts forward a new type of marine current energy conversion device, a flexible vane turbine. Its flexible vane is made of flexible material, which can deform to adapt to fluid. Thus the turbine can adjust the attack angle automatically to take full advantage of the lift effect and drag effect and produce as more power as possible, so it has unique hydrodynamic performances. Focusing on the power efficiency coefficient ( C_p ) , the authors studied its hydrodynamic characteristics and the affecting factors on them via a model test in a water tank. The results proved its characteristics and showed that, the shape of flexible vane and the structure of turbine rotor are the main factors affecting on its performance. Based on the analysis of the results, an optimal scheme of the flexible vane turbine having higher coefficient of power was proposed.%提出了一种新型海洋潮流能获取装置--潮流能柔性叶片水轮机.其叶片采用柔性材料,可适应流体发生形变,从而它能自动调节攻角,能充分利用流体的升力效应和阻力效应做功,具有独特的水动力学特性.以柔性叶片水轮机获能系数(C_p)为主要研究目标,通过水槽模型实验对其影响因素进行了研究.实验证实了该柔性叶片水轮机的独特水动力学特性,而且证明,叶片形状和水轮机结构形式是其性能的主要影响因素,并通过分析得到了具有较佳水动力学特性的水轮机的叶片形状和水轮机结构形式.

  2. Long-Period Tidal Variations in the Length of Day

    Science.gov (United States)

    Ray, Richard D.; Erofeeva, Svetlana Y.

    2014-01-01

    A new model of long-period tidal variations in length of day is developed. The model comprises 80 spectral lines with periods between 18.6 years and 4.7 days, and it consistently includes effects of mantle anelasticity and dynamic ocean tides for all lines. The anelastic properties followWahr and Bergen; experimental confirmation for their results now exists at the fortnightly period, but there remains uncertainty when extrapolating to the longest periods. The ocean modeling builds on recent work with the fortnightly constituent, which suggests that oceanic tidal angular momentum can be reliably predicted at these periods without data assimilation. This is a critical property when modeling most long-period tides, for which little observational data exist. Dynamic ocean effects are quite pronounced at shortest periods as out-of-phase rotation components become nearly as large as in-phase components. The model is tested against a 20 year time series of space geodetic measurements of length of day. The current international standard model is shown to leave significant residual tidal energy, and the new model is found to mostly eliminate that energy, with especially large variance reduction for constituents Sa, Ssa, Mf, and Mt.

  3. Strong tidal dissipation in Io and Jupiter from astrometric observations.

    Science.gov (United States)

    Lainey, Valéry; Arlot, Jean-Eudes; Karatekin, Ozgür; Van Hoolst, Tim

    2009-06-18

    Io is the volcanically most active body in the Solar System and has a large surface heat flux. The geological activity is thought to be the result of tides raised by Jupiter, but it is not known whether the current tidal heat production is sufficiently high to generate the observed surface heat flow. Io's tidal heat comes from the orbital energy of the Io-Jupiter system (resulting in orbital acceleration), whereas dissipation of energy in Jupiter causes Io's orbital motion to decelerate. Here we report a determination of the tidal dissipation in Io and Jupiter through its effect on the orbital motions of the Galilean moons. Our results show that the rate of internal energy dissipation in Io (k(2)/Q = 0.015 +/- 0.003, where k(2) is the Love number and Q is the quality factor) is in good agreement with the observed surface heat flow, and suggest that Io is close to thermal equilibrium. Dissipation in Jupiter (k(2)/Q = (1.102 +/- 0.203) x 10(-5)) is close to the upper bound of its average value expected from the long-term evolution of the system, and dissipation in extrasolar planets may be higher than presently assumed. The measured secular accelerations indicate that Io is evolving inwards, towards Jupiter, and that the three innermost Galilean moons (Io, Europa and Ganymede) are evolving out of the exact Laplace resonance.

  4. Hydrodynamics and sediment suspension in shallow tidal channels intersecting a tidal flat

    Science.gov (United States)

    Pieterse, Aline; Puleo, Jack A.; McKenna, Thomas E.

    2016-05-01

    A field study was conducted on a tidal flat intersected by small tidal channels (depth stress and turbulent kinetic energy were computed from high frequency velocity measurements. Maximum water depth at the field site varied from 0.11 m during the lowest neap high tide to 0.58 m during a storm event. In the channel intersecting the tidal flat, the shear stress, turbulence and along-channel velocity were ebb dominant; e.g. 0.33 m/s peak velocity for ebb compared to 0.19 m/s peak velocity for flood. Distinct pulses in velocity occurred when the water level was near the tidal flat level. The velocity pulse during flood tide occurred at a higher water level than during ebb tide. No corresponding velocity pulse on the tidal flat was observed. Sediment concentrations peaked at the beginning and end of each tidal cycle, and often had a secondary peak close to high tide, assumed to be related to sediment advection. The influence of wind waves on bed shear stress and sediment suspension was negligible. Water levels were elevated during a storm event such that the tidal flat remained inundated for 4 tidal cycles. The water did not drain from the tidal flat into the channels during the storm, and no velocity pulses occurred. Along-channel velocities, turbulent kinetic energy, and shear stresses were therefore smaller in the channels during storm conditions than during non-storm conditions.

  5. Microbial quality of a marine tidal pool

    CSIR Research Space (South Africa)

    Genthe, Bettina

    1995-01-01

    Full Text Available In this study the source of microbial pollution to a tidal pool was investigated. Both adjacent seawater which could contribute to possible faecal pollution and potential direct bather pollution were studied. The microbial quality of the marine...

  6. Tides and tidal harmonics at Umbharat, Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Suryanarayana, A.; Swamy, G.N.

    A part of the data on tides recorded at Machiwada near Umbharat, Gulf of Cambay during April 1978 was subjected to harmonic analysis following the Admiralty procedure. The general tidal characteristics and the value of four major harmonic...

  7. Analysis of 19-year tidal data

    Institute of Scientific and Technical Information of China (English)

    黄祖珂; 陈宗镛; 司鸿业; 叶琳

    1997-01-01

    19-year tidal data of the 3 stations, Huludao, Qinhuangdao and Kanmen, have totally been analysed, and the amplitudes and phases of 472 tidal constituents have been calculated with a resolution of Δ≥ 0.002 2 /h. Based on the draconitic tide, the anomalistic tide and pole tide obtained, the ultra-long-period variations of the mean sea level have been predicted. The annual tidal analysis of 19-year data at the above-mentioned stations and at Tanggu, Longkou has been carried out. The stability of the annual tidal analysis has been investigated with regard to the astronomical factors, the nonlinear effects and the variations of sea-bottom topography.

  8. Stingray tidal stream energy device - phase 3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    The 150 kW Stingray demonstrator was designed, built and installed by The Engineering Business (EB) in 2002, becoming the world's first full-scale tidal stream generator. The concept and technology are described in the reports from Phases 1 and 2 of the project. This report provides an overview of Phase 3 - the re-installation of Stingray in Yell Sound in the Shetland Isles between July and September 2003 for further testing at slack water and on the flood tide to confirm basic machine characteristics, develop the control strategy and to demonstrate performance and power collection through periods of continuous operation. The overall aim was to demonstrate that electricity could be generated at a potentially commercially viable unit energy cost; cost modelling indicated a future unit energy cost of 6.7 pence/kWh when 100 MW capacity had been installed. The report describes: project objectives, targets and activities; design and production; marine operations including installation and demobilisation; environmental monitoring and impact, including pre-installation and post-decommissioning surveys; stakeholder involvement; test results on machine characteristics, sensor performance, power cycle analysis, power collection, transmission performance and efficiency, current data analysis; validation of the mathematical model; the background to the economic model; cost modelling; and compliance with targets set by the Department of Trade and Industry (DTI).

  9. Tidal Modulation of Ice-shelf Flow: a Viscous Model of the Ross Ice Shelf

    Science.gov (United States)

    Brunt, Kelly M.; MacAyeal, Douglas R.

    2014-01-01

    Three stations near the calving front of the Ross Ice Shelf, Antarctica, recorded GPS data through a full spring-neap tidal cycle in November 2005. The data revealed a diurnal horizontal motion that varied both along and transverse to the long-term average velocity direction, similar to tidal signals observed in other ice shelves and ice streams. Based on its periodicity, it was hypothesized that the signal represents a flow response of the Ross Ice Shelf to the diurnal tides of the Ross Sea. To assess the influence of the tide on the ice-shelf motion, two hypotheses were developed. The first addressed the direct response of the ice shelf to tidal forcing, such as forces due to sea-surface slopes or forces due to sub-ice-shelf currents. The second involved the indirect response of ice-shelf flow to the tidal signals observed in the ice streams that source the ice shelf. A finite-element model, based on viscous creep flow, was developed to test these hypotheses, but succeeded only in falsifying both hypotheses, i.e. showing that direct tidal effects produce too small a response, and indirect tidal effects produce a response that is not smooth in time. This nullification suggests that a combination of viscous and elastic deformation is required to explain the observations.

  10. Global characteristics of the lunar tidal modulation of the equatorial electrojet derived from CHAMP observations

    Directory of Open Access Journals (Sweden)

    H. Lühr

    2012-03-01

    Full Text Available It has been known since many decades that lunar tide has an influence on the strength of the equatorial electrojet (EEJ. There has, however, never been a comprehensive study of the tidal effect on a global scale. Based on the continuous magnetic field measurements by the CHAMP satellite over 10 years it is possible to investigate the various aspects of lunar effects on the EEJ. The EEJ intensity is enhanced around times when the moon is overhead or at the antipode. This effect is particularly strong around noon, shortly after new and full moon. The lunar tide manifests itself as a semi-diurnal wave that precesses through all local times within one lunar month. The largest tidal amplitudes are observed around December solstice and smallest around June solstice. The tidal wave crest lags behind the moon phase. During December this amounts to about 4 days while it is around 2 days during other times of the year. We have not found significant longitudinal variations of the lunar influence on the EEJ. When comparing the average EEJ amplitude at high solar activity with that during periods of solar minimum conditions a solar cycle dependence can be found, but the ratio between tidal amplitude and EEJ intensity stays the same. Actually, tidal signatures standout clearer during times of low solar activity. We suggest that the tidal variations are caused by a current system added to the EEJ rather than by modulating the EEJ. Gravitational forcing of the lower atmosphere by the moon and the sun is assumed to be the driver of an upward propagating tidal wave. The larger tidal amplitudes around December solstice can be related to stratospheric warming events which seem to improve the conditions for upward propagation.

    The results described here have to large extent been presented as a Julius-Bartels Medal Lecture during the General Assembly 2011 of the European Geosciences Union.

  11. Global characteristics of the lunar tidal modulation of the equatorial electrojet derived from CHAMP observations

    Science.gov (United States)

    Lühr, H.; Siddiqui, T. A.; Maus, S.

    2012-03-01

    It has been known since many decades that lunar tide has an influence on the strength of the equatorial electrojet (EEJ). There has, however, never been a comprehensive study of the tidal effect on a global scale. Based on the continuous magnetic field measurements by the CHAMP satellite over 10 years it is possible to investigate the various aspects of lunar effects on the EEJ. The EEJ intensity is enhanced around times when the moon is overhead or at the antipode. This effect is particularly strong around noon, shortly after new and full moon. The lunar tide manifests itself as a semi-diurnal wave that precesses through all local times within one lunar month. The largest tidal amplitudes are observed around December solstice and smallest around June solstice. The tidal wave crest lags behind the moon phase. During December this amounts to about 4 days while it is around 2 days during other times of the year. We have not found significant longitudinal variations of the lunar influence on the EEJ. When comparing the average EEJ amplitude at high solar activity with that during periods of solar minimum conditions a solar cycle dependence can be found, but the ratio between tidal amplitude and EEJ intensity stays the same. Actually, tidal signatures standout clearer during times of low solar activity. We suggest that the tidal variations are caused by a current system added to the EEJ rather than by modulating the EEJ. Gravitational forcing of the lower atmosphere by the moon and the sun is assumed to be the driver of an upward propagating tidal wave. The larger tidal amplitudes around December solstice can be related to stratospheric warming events which seem to improve the conditions for upward propagation. The results described here have to large extent been presented as a Julius-Bartels Medal Lecture during the General Assembly 2011 of the European Geosciences Union.

  12. Tidal Response of Preliminary Jupiter Model

    OpenAIRE

    Wahl, Sean M; Hubbard, Willam B.; Militzer, Burkhard

    2016-01-01

    In anticipation of improved observational data for Jupiter's gravitational field from the Juno spacecraft, we predict the static tidal response for a variety of Jupiter interior models based on ab initio computer simulations of hydrogen-helium mixtures. We calculate hydrostatic-equilibrium gravity terms using the non-perturbative concentric Maclaurin Spheroid (CMS) method that eliminates lengthy expansions used in the theory of figures. Our method captures terms arising from the coupled tidal...

  13. M2-Branes in N = 3 Harmonic Superspace

    Directory of Open Access Journals (Sweden)

    E. Ivanov

    2010-01-01

    Full Text Available We give a brief account of the recently proposed N = 3 superfield formulation of the N = 6, 3D superconformal theory of Aharony et al (ABJM describing a low-energy limit of the system of multiple M2-branes on the AdS4×S7/Zk background. This formulation is given in harmonic N = 3 superspace and reveals a number of surprising new features. In particular, the sextic scalar potential of ABJM arises at the on-shell component level as the result of eliminating appropriate auxiliary fields, while there is no explicit superpotential at the off-shell superfield level.

  14. M2-branes and AdS/CFT

    CERN Document Server

    Klebanov, Igor R

    2009-01-01

    These notes provide a brief introduction to the ABJM theory, the level k U(N) x U(N) superconformal Chern-Simons matter theory which has been conjectured to describe N coincident M2-branes. We discuss its dual formulation in terms of M-theory on AdS_4 x S^7/Z_k and review some of the evidence in favor of the conjecture. We end with a brief discussion of the important role played by the monopole operators.

  15. Superconformal M2-branes and generalized Jordan triple systems

    CERN Document Server

    Nilsson, Bengt E W

    2008-01-01

    Three-dimensional conformal theories with six supersymmetries and SU(4) R-symmetry describing stacks of M2-branes are here proposed to be related to generalized Jordan triple systems. Writing the four-index structure constants in an appropriate form, the Chern-Simons part of the action immediately suggests a connection to such triple systems. In this note we show that the whole theory with six manifest supersymmetries can be naturally expressed in terms of structure constants of generalized Jordan triple systems. We comment on the associated graded Lie algebra, which corresponds to an extension of the gauge group.

  16. Conformational variability of the glycine receptor M2 domain in response to activation by different agonists.

    Science.gov (United States)

    Pless, Stephan A; Dibas, Mohammed I; Lester, Henry A; Lynch, Joseph W

    2007-12-07

    Models describing the structural changes mediating Cys loop receptor activation generally give little attention to the possibility that different agonists may promote activation via distinct M2 pore-lining domain structural rearrangements. We investigated this question by comparing the effects of different ligands on the conformation of the external portion of the homomeric alpha1 glycine receptor M2 domain. Conformational flexibility was assessed by tethering a rhodamine fluorophore to cysteines introduced at the 19' or 22' positions and monitoring fluorescence and current changes during channel activation. During glycine activation, fluorescence of the label attached to R19'C increased by approximately 20%, and the emission peak shifted to lower wavelengths, consistent with a more hydrophobic fluorophore environment. In contrast, ivermectin activated the receptors without producing a fluorescence change. Although taurine and beta-alanine were weak partial agonists at the alpha1R19'C glycine receptor, they induced large fluorescence changes. Propofol, which drastically enhanced these currents, did not induce a glycine-like blue shift in the spectral emission peak. The inhibitors strychnine and picrotoxin elicited fluorescence and current changes as expected for a competitive antagonist and an open channel blocker, respectively. Glycine and taurine (or beta-alanine) also produced an increase and a decrease, respectively, in the fluorescence of a label attached to the nearby L22'C residue. Thus, results from two separate labeled residues support the conclusion that the glycine receptor M2 domain responds with distinct conformational changes to activation by different agonists.

  17. Spatial patterns of tidal heating

    CERN Document Server

    Beuthe, Mikael

    2012-01-01

    In a body periodically strained by tides, heating produced by viscous friction is far from homogeneous. I show here that the distribution of the dissipated power within a spherically stratified body is a linear combination of three angular functions. These angular functions depend only on the tidal potential whereas the radial weights are specified by the internal structure of the body. The 3D problem of predicting spatial patterns of dissipation at all radii is thus reduced to the 1D problem of computing weight functions. I compute spatial patterns in various toy models without assuming a specific rheology: a viscoelastic thin shell stratified in conductive and convective layers, an incompressible homogeneous body and a two-layer model of uniform density with a liquid or rigid core. For a body in synchronous rotation undergoing eccentricity tides, dissipation in a mantle surrounding a liquid core is highest at the poles. Within a softer layer (asthenosphere or icy layer), the same tides generate maximum heat...

  18. Half Moon Cove Tidal Project. Feasibility report

    Energy Technology Data Exchange (ETDEWEB)

    1980-11-01

    The proposed Half Moon Cove Tidal Power Project would be located in a small cove in the northern part of Cobscook Bay in the vicinity of Eastport, Maine. The project would be the first tidal electric power generating plant in the United States of America. The basin impounded by the barrier when full will approximate 1.2 square miles. The average tidal range at Eastport is 18.2 feet. The maximum spring tidal range will be 26.2 feet and the neap tidal range 12.8 feet. The project will be of the single pool-type single effect in which generation takes place on the ebb tide only. Utilizing an average mean tidal range of 18.2 feet the mode of operation enables generation for approximately ten and one-half (10-1/2) hours per day or slightly in excess of five (5) hours per tide. The installed capacity will be 12 MW utilizing 2 to 6 MW units. An axial flow, or Bulb type of turbine was selected for this study.

  19. VISCOELASTIC MODELS OF TIDALLY HEATED EXOMOONS

    Energy Technology Data Exchange (ETDEWEB)

    Dobos, Vera [Konkoly Thege Miklos Astronomical Institute, Research Centre of Astronomy and Earth Sciences, Hungarian Academy of Sciences, H-1121 Konkoly Thege Miklós út 15-17, Budapest (Hungary); Turner, Edwin L., E-mail: dobos@konkoly.hu [Department of Astrophysical Sciences, Princeton University, 08544, 4 Ivy Lane, Peyton Hall, Princeton, NJ (United States)

    2015-05-01

    Tidal heating of exomoons may play a key role in their habitability, since the elevated temperature can melt the ice on the body even without significant solar radiation. The possibility of life has been intensely studied on solar system moons such as Europa or Enceladus where the surface ice layer covers a tidally heated water ocean. Tidal forces may be even stronger in extrasolar systems, depending on the properties of the moon and its orbit. To study the tidally heated surface temperature of exomoons, we used a viscoelastic model for the first time. This model is more realistic than the widely used, so-called fixed Q models because it takes into account the temperature dependence of the tidal heat flux and the melting of the inner material. Using this model, we introduced the circumplanetary Tidal Temperate Zone (TTZ), which strongly depends on the orbital period of the moon and less on its radius. We compared the results with the fixed Q model and investigated the statistical volume of the TTZ using both models. We have found that the viscoelastic model predicts 2.8 times more exomoons in the TTZ with orbital periods between 0.1 and 3.5 days than the fixed Q model for plausible distributions of physical and orbital parameters. The viscoelastic model provides more promising results in terms of habitability because the inner melting of the body moderates the surface temperature, acting like a thermostat.

  20. Viscoelastic Models of Tidally Heated Exomoons

    CERN Document Server

    Dobos, Vera

    2015-01-01

    Tidal heating of exomoons may play a key role in their habitability, since the elevated temperature can melt the ice on the body even without significant solar radiation. The possibility of life is intensely studied on Solar System moons such as Europa or Enceladus, where the surface ice layer covers tidally heated water ocean. Tidal forces may be even stronger in extrasolar systems, depending on the properties of the moon and its orbit. For studying the tidally heated surface temperature of exomoons, we used a viscoelastic model for the first time. This model is more realistic than the widely used, so-called fixed Q models, because it takes into account the temperature dependency of the tidal heat flux, and the melting of the inner material. With the use of this model we introduced the circumplanetary Tidal Temperate Zone (TTZ), that strongly depends on the orbital period of the moon, and less on its radius. We compared the results with the fixed Q model and investigated the statistical volume of the TTZ usi...

  1. High resolution multibeam and hydrodynamic datasets of tidal channels and inlets of the Venice Lagoon.

    Science.gov (United States)

    Madricardo, Fantina; Foglini, Federica; Kruss, Aleksandra; Ferrarin, Christian; Pizzeghello, Nicola Marco; Murri, Chiara; Rossi, Monica; Bajo, Marco; Bellafiore, Debora; Campiani, Elisabetta; Fogarin, Stefano; Grande, Valentina; Janowski, Lukasz; Keppel, Erica; Leidi, Elisa; Lorenzetti, Giuliano; Maicu, Francesco; Maselli, Vittorio; Mercorella, Alessandra; Montereale Gavazzi, Giacomo; Minuzzo, Tiziano; Pellegrini, Claudio; Petrizzo, Antonio; Prampolini, Mariacristina; Remia, Alessandro; Rizzetto, Federica; Rovere, Marzia; Sarretta, Alessandro; Sigovini, Marco; Sinapi, Luigi; Umgiesser, Georg; Trincardi, Fabio

    2017-09-05

    Tidal channels are crucial for the functioning of wetlands, though their morphological properties, which are relevant for seafloor habitats and flow, have been understudied so far. Here, we release a dataset composed of Digital Terrain Models (DTMs) extracted from a total of 2,500 linear kilometres of high-resolution multibeam echosounder (MBES) data collected in 2013 covering the entire network of tidal channels and inlets of the Venice Lagoon, Italy. The dataset comprises also the backscatter (BS) data, which reflect the acoustic properties of the seafloor, and the tidal current fields simulated by means of a high-resolution three-dimensional unstructured hydrodynamic model. The DTMs and the current fields help define how morphological and benthic properties of tidal channels are affected by the action of currents. These data are of potential broad interest not only to geomorphologists, oceanographers and ecologists studying the morphology, hydrodynamics, sediment transport and benthic habitats of tidal environments, but also to coastal engineers and stakeholders for cost-effective monitoring and sustainable management of this peculiar shallow coastal system.

  2. A comprehensive survey of M(2)AX phase elastic properties.

    Science.gov (United States)

    Cover, M F; Warschkow, O; Bilek, M M M; McKenzie, D R

    2009-07-29

    M(2)AX phases are a family of nanolaminate, ternary alloys that are composed of slabs of transition metal carbide or nitride (M(2)X) separated by single atomic layers of a main group element. In this combination, they manifest many of the beneficial properties of both ceramic and metallic compounds, making them attractive for many technological applications. We report here the results of a large scale computational survey of the elastic properties of all 240 elemental combinations using first-principles density functional theory calculations. We found correlations revealing the governing role of the A element and its interaction with the M element on the c axis compressibility and shearability of the material. The role of the X element is relatively minor, with the strongest effect seen in the in-plane constants C(11) and C(12). We identify several elemental compositions with extremal properties such as W(2)SnC, which has by far the lowest value of C(44), suggesting potential applications as a high-temperature dry lubricant.

  3. Tidal asymmetry in a funnel-shaped estuary with mixed semidiurnal tides

    Science.gov (United States)

    Gong, Wenping; Schuttelaars, Henk; Zhang, Heng

    2016-05-01

    Different types of tidal asymmetry (see review of de Swart and Zimmerman Annu Rev Fluid Mech 41: 203-229, 2009) are examined in this study. We distinguish three types of tidal asymmetry: duration and magnitude differences between flood and ebb tidal flow, duration difference between the rising and falling tides. For waterborne substance transport, the first two asymmetries are important while the last one is not. In this study, we take the Huangmaohai Estuary (HE), Pearl River Delta, China as an example to examine the spatio-temporal variations of the tidal asymmetry in a mixed semidiurnal tidal regime and to explain them by investigating the associated mechanisms. The methodology defining the tidal duration asymmetry and velocity skewness, proposed by Nidzieko (J Geophys Res 115: C08006. doi: 10.1029/2009JC005864 , 2010) and synthesized by Song et al. (J Geophys Res 116: C12007. doi: 10.1029/2011JC007270 , 2011), is utilized here and referred to as tidal duration asymmetry (TDA) and flow velocity asymmetry (FVA), respectively. The methodology is further used to quantify the flow duration asymmetry (FDA). A positive asymmetry means a shorter duration of low water slack for FDA, a shorter duration of the rising tide for TDA, and a flood dominance for FVA and vice versa. The Regional Ocean Modeling System (ROMS) model is used to provide relatively long-term water elevation and velocity data and to conduct diagnostic experiments. In the HE, the main tidal constituents are diurnal tides K 1, O 1 and semidiurnal tides M 2 and S 2. The interaction among the diurnal and semidiurnal tides generates a negative tidal asymmetry, while the interactions among semidiurnal tides and their overtides or compound tides result in a positive tidal asymmetry. The competition among the above interactions determines the FDA and TDA, whereas for the FVA, aside from the interaction among different tidal constituents, an extra component, the residual flow, plays an important role. The

  4. Biogeomorphology of tidal landforms: physical and biological processes shaping the tidal landscape

    Science.gov (United States)

    Marani, M.; D'Alpaos, A.; Da Lio, C.

    2011-12-01

    The equilibrium states and transient dynamics of tidal landforms are the result of many concurring physical and biological forcings, such as tidal range, wind climate, sediment supply, vegetation and microphytobenthos development, and rates of relative sea level rise (RSLR). A 0D model of the coupled elevation-vegetation dynamics is used to explore the relative role of the physical and biological factors shaping these systems. We find that salt marshes exposed to large tidal ranges are more stable, and therefore more resilient to increasing rates of RSLR, than marshes subjected to low tidal ranges and that subtidal platforms in macrotidal systems are less exposed to wind-induced erosion processes than their counterparts in systems with smaller tidal fluctuations. Notably, we find that vegetation crucially affects both the equilibrium marsh elevation, through dissipation of wind waves and organic accumulation, and marsh resilience to accelerations in RSLR rates, important differences being associated with different vegetation types. Furthermore, our results show that the existence and stability of equilibrium states fundamentally depend on the local wind and tidal regime, even within the same tidal system. Finally, we propose a modelling framework to study how biological evolution lead to the emergence of tidal landforms as we know them.

  5. Three-dimensional semi-idealized model for tidal motion in tidal estuaries

    NARCIS (Netherlands)

    Kumar, M.; Schuttelaars, H.M.; Roos, P.C.; Möller, M.

    2015-01-01

    In this paper, a three-dimensional semi-idealized model for tidal motion in a tidal estuary of arbitrary shape and bathymetry is presented. This model aims at bridging the gap between idealized and complex models. The vertical profiles of the velocities are obtained analytically in terms of the firs

  6. Impact of phase angle on the hydrodynamic performance of a bi-unit vertical axis tidal current energy water turbine%相位角对双机组立轴水轮机的水动力性能影响

    Institute of Scientific and Technical Information of China (English)

    王凯; 孙科; 张亮; 盛其虎

    2016-01-01

    The impact of phase angles on the hydrodynamic performance of a bi⁃unit two⁃blade vertical axis tidal current energy water turbine were investigated using a CFD numerical simulation method. We analyzed the hydrody⁃namic performance of a water turbine under different starting phase angles and derived the change law for the effi⁃ciency of the water turbine, and the normal and tangential force coefficients of the blades. By analyzing velocity vector drawing and pressure drawing, the change mechanism was also investigated. The results demonstrated that the efficiency of two single⁃unit water turbines was less than that of a single bi⁃unit tidal current energy water tur⁃bine, particularly at middle and high speeds. The overall efficiency of the water turbine at all phase angles was close to or higher than the efficiency at 0 degrees. The efficiency curves of the two units converged when the phase angle was 90 degrees, and at the same time, the bearing force was small because both the force⁃bearing coefficient of the blade and the high pressure area on the blade top were also small. An initial starting phase angle of 90 de⁃grees improved the efficiency of the bi⁃unit water turbine and reduced the bearing force on the blade, allowing the life of the turbine to be extended.%为了研究相位角对双机组两叶片垂直轴潮流能水轮机的水动力性能影响,采用CFD数值模拟方法,计算了不同初始相位角下水轮机水动力性能,得到水轮机的效率、叶片切向力系数及法向力系数的变化规律,并通过速度矢量图和压力图的细节分析,解释变化机理。研究结果表明:双机组潮流能水轮机效率比两个单机组水轮机工作效率高,特别在中高速比时更明显。除0°以外的相位角下水轮机总效率相近且高于0°时的效率。90°相位角时两个机组的效率曲线基本重合,且此时叶片受力系数小,叶尖高压区域也小,从

  7. Estuary/ocean exchange and tidal mixing in a Gulf of Maine Estuary: A Lagrangian modeling study

    Science.gov (United States)

    Bilgili, Ata; Proehl, Jeffrey A.; Lynch, Daniel R.; Smith, Keston W.; Swift, M. Robinson

    2005-12-01

    A Lagrangian particle method embedded within a 2-D finite element code, is used to study the transport and ocean-estuary exchange processes in the well-mixed Great Bay Estuarine System in New Hampshire, USA. The 2-D finite element model, driven by residual, semi-diurnal and diurnal tidal constituents, includes the effects of wetting and drying of estuarine mud flats through the use of a porous medium transport module. The particle method includes tidal advection, plus a random walk model in the horizontal that simulates sub-grid scale turbulent transport processes. Our approach involves instantaneous, massive [O(500,000)] particle releases that enable the quantification of ocean-estuary and inter-bay exchanges in a Markovian framework. The effects of the release time, spring-neap cycle, riverine discharge and diffusion strength on the intra-estuary and estuary-ocean exchange are also investigated. The results show a rather dynamic interaction between the ocean and the estuary with a fraction of the exiting particles being caught up in the Gulf of Maine Coastal Current and swept away. Three somewhat different estimates of estuarine residence time are calculated to provide complementary views of estuary flushing. Maps of residence time versus release location uncover a strong spatial dependency of residence time within the estuary that has very important ramifications for local water quality. Simulations with and without the turbulent random walk show that the combined effect of advective shear and turbulent diffusion is very effective at spreading particles throughout the estuary relatively quickly, even at low (1 m 2/s) diffusivity. The results presented here show that a first-order Markov Chain approach has applicability and a high potential for improving our understanding of the mixing processes in estuaries.

  8. The Extreme Type I Planetary Nebula M2-52

    Directory of Open Access Journals (Sweden)

    M. Peña

    2002-01-01

    Full Text Available Se presentan los resultados obtenidos a partir de espectroscopía de alta resolución de la parte central de la nebulosa planetaria bipolar M2-52 que muestra un tipo morfológico Br. Hemos confirmado que M2-52 es una nebulosa de Tipo I de Peimbert, con un espectro rico en líneas de alto y bajo grado de ionización y un fuerte enriquecimiento de He y N. La composición química del gas ionizado es: He/H = 0:165 0:010, O/H = (2:6 0:5 x 10_4, N/O = 2:3 0:3, Ne/O = 0:37 0:10, Ar/O = (9:2 2:0 x 10_3 y S/O > 2:0 x 10_3. La velocidad de expansión de la nebulosa es, en promedio, de 20 2 km s_1 y varía ligeramente dependiendo del ión considerado. Los iones de menor grado de ionización, N+ y S+, muestran vexp _ 18 km s_1, O++ y He+ muestran vexp _ 20 km s_1, en tanto que He++ y H+ muestran vexp _ 22 km s_1. Es posible que la zona de N+ y S+ esté siendo frenada por el anillo de material molecular encontrado alrededor de la estrella.

  9. Marginal fluctuations as instantons on M2/D2-branes

    Energy Technology Data Exchange (ETDEWEB)

    Naghdi, M. [University of Ilam, Department of Physics, Faculty of Basic Sciences, Ilam (Iran, Islamic Republic of)

    2014-03-15

    We introduce some (anti-) M/D-branes through turning on the corresponding field strengths of the 11- and 10-dimensional supergravity theories over AdS{sub 4} x M{sup 7} {sup vertical} {sup stroke} {sup 6} spaces, where we use S{sup 7}/Z{sub k} and CP{sup 3} for the internal spaces. Indeed, when we add M2/D2-branes on the same directions with the near horizon branes of the Aharony-Bergman-Jafferis- Maldacena model, all symmetries and supersymmetries are preserved trivially. In this case, we obtain a localized object just in the horizon. This normalizable bulk massless scalar mode is a singlet of SO(8) and SU(4) x U(1), and it agrees with a marginal boundary operator of the conformal dimension of Δ{sub +} = 3. However, after performing a special conformal transformation, we see that the solution is localized in the Euclideanized AdS{sub 4} space and is attributable to the included anti-M2/D2-branes, which are also necessary to ensure that there is no back-reaction. The resultant theory now breaks all N = 8, 6 supersymmetries to N = 0, while the other symmetries are so preserved. The dual boundary operator is then set up from the skew-whiffing of the representations 8s and 8v for the supercharges and scalars, respectively, while the fermions remain fixed in 8c of the original theory. Besides, we also address another alternate bulk to boundary matching procedure through turning on one of the gauge fields of the full U(N){sub k} x U(N){sub -k} gauge group along the same lines with a similar situation to the one faced in the AdS{sub 5}/CFT{sub 4} correspondence. The latter approach covers the difficulty already faced with in the bulk-boundary matching procedure for k = 1, 2 as well. (orig.)

  10. Viral M2 ion channel protein: a promising target for anti-influenza drug discovery.

    Science.gov (United States)

    Moorthy, N S Hari Narayana; Poongavanam, Vasanthanathan; Pratheepa, V

    2014-01-01

    Influenza virus is an important RNA virus causing pandemics (Spanish Flu (1918), Asian Flu (1957), Hong Kong Flu (1968) and Swine Flu (2009)) over the last decades. Due to the spontaneous mutations of these viral proteins, currently available antiviral and anti-influenza drugs quickly develop resistance. To account this, only limited antiinfluenza drugs have been approved for the therapeutic use. These include amantadine and rimantadine (M2 proton channel blockers), zanamivir, oseltamivir and peramivir (neuraminidase inhibitors), favipravir (polymerase inhibitor) and laninamivir. This review provides an outline on the strategies to develop novel, potent chemotherapeutic agents against M2 proton channel. Primarily, the M2 proton channel blockers elicit pharmacological activity through destabilizing the helices by blocking the proton transport across the transmembrane. The biologically important compounds discovered using the scaffolds such as bisnoradmantane, noradamantane, triazine, spiroadamantane, isoxazole, amino alcohol, azaspiro, spirene, pinanamine, etc are reported to exhibit anti-influenza activity against wild or mutant type (S31N and V27A) of M2 proton channel protein. The reported studies explained that the adamantane based compounds (amantadine and rimantadine) strongly interact with His37 (through hydrogen bonding) and Ala30, Ile33 and Gly34 residues (hydrophobic interactions). The adamantane and the non-adamantane scaffolds fit perfectly in the active site pocket present in the wild type and the charged amino groups (ammonium) create positive electrostatic potential, which blocks the transport of protons across the pore. In the mutated proteins, larger or smaller binding pocket are created by small or large mutant residues, which do not allow the molecules fit in the active site. This causes the channel to be unblocked and the protons are allowed to transfer inside the pore. The structural analysis of the M2 proton channel blockers illustrated that

  11. Methylmercury Cycling and Tidal Exchange in a Chesapeake Bay Salt Marsh (Invited)

    Science.gov (United States)

    Mitchell, C. P.; Jordan, T. E.; Heyes, A.; Gilmour, C. C.

    2010-12-01

    The importance of salt marshes to methylmercury budgets in coastal regions is poorly understood. Given that salt marshes are important coastal features around Chesapeake Bay and in many other coastal areas, and that methylmercury is a bioaccumulated neurotoxin to aquatic biota and the humans that consume them, fully understanding methylmercury sources is an important step in mitigating detrimental health and ecosystem effects. In this research, we highlight the important biogeochemical controls on methylmercury production in a Chesapeake Bay salt marsh and link this production with tidal exchange using hydrological measurements and sampling over a 12-month period. Our findings point to an important linkage between iron cycling and methylmercury production. Net tidal exchange of total mercury and methylmercury showed marked seasonal variation, especially for methylmercury. Overall, we estimate the salt marsh was a large net sink for total mercury (~60 μg m-2 yr-1) and a net source of methylmercury (~0.25 μg m-2 yr-1). In addition to significant in situ methylmercury exposure risk to biota that utilize salt marshes as habitat or breeding grounds, the contribution of methylmercury to the estuarine zone as a result of salt marsh tidal exchange is not negligible.

  12. A preliminary study of the turbulence features of the tidal bore in the Qiantang River, China

    Institute of Scientific and Technical Information of China (English)

    谢东风; 潘存鸿

    2013-01-01

    In this paper, the turbulence characteristics of the tidal flow in the Qiantang River, China, the world-famous Qiantang bore, are studied. A detailed field observation at the Yanguan section of the Qiantang River was carried out during the spring tide in October 2010 with a continuous collection of high frequency turbulence data. The data analysis shows that the hydrodynamic processes are characterized by a strong tidal bore. Statistics of the turbulence such as the probability distributions of the turbulent components, the variance terms and the covariance terms are found consistent with those of previous studies of estuaries without the tidal bore. However, along the vertical profile, the distributions of all variables become more scattered downwards. The horizontal turbulence fluctuations are of a similar magnitude while the vertical turbulence has a fluctuation magnitude about 1/3 of that of the horizontal turbulences. The fluctuation strengths and the Reynolds stresses are much larger than those of other estuaries when the bore arrives. The bottom shear stress varies periodically with the tides, less than 0.44 N/m2 during the ebb but is increased drastically at the bore arrival, with the maximum being 0.92 N/m2. A good linear relationship is found between the bottom shear stress and the bottom suspended sediment concentration.

  13. Modelagem numérica da região costeira de Santos (SP: circulação de maré Numerical modeling of the coast region of Santos (SP: tidal circulation

    Directory of Open Access Journals (Sweden)

    Joseph Harari

    1998-01-01

    Full Text Available Foi implementado o Princeton Ocean Model (POM para a região costeira de Santos (46° - 47°W, 23°40' - 24°30'S, com grade regular de resolução == I km e 11 níveis sigrna na vertical. O modelo foi utilizado em simulações de maré, com a especificação das correspondentes oscilações nos contornos, calculadas com base em mapas cotidais da plataforma. O modelo foi processado considerando isoladamente as componentes principais lunar e solar (M2 e S2, cada qual por 5 dias, e com as 9 principais componentes de maré conjuntamente, por 31 dias. As análises de maré das séries temporais de resultados possibilitaram a composição de mapas com linhas cotidais e eixos das elipses de correntes de superfície. Esses mapas indicam as características da propagação das ondas de maré na área modelada, com as distribuições espaciais de suas elevações e correntes. Os aspectos de maior interesse no estudo realizado são: o contraste das intensidades das circulações, entre a parte mais profunda e regiões internas rasas; as marcantes diferenças de intensidade de correntes nos dois lados da Baía de Santos; a convergência / divergência das correntes nos Canais de São Vicente e de Bertioga; assimetrias de maré nas regiões rasas; e rotação anti-horária das correntes na área costeira. O modelo pode ser utilizado em previsões operacionais de marés e correntes de maré na área de estudo.The Princeton Ocean Model (p0M was implemented for the coastal region of Santos (46° - 47°W, 23°40' - 24°30'S, with a regular grid of resolution == 1 km and 11 sigrna levels in the vertical. the model was used in tidal simulations, with the specification of the correspondent oscillations at the boundaries, computed through cotidal maps of the shelf. The model runs considering separately the lunar and solar principal components (M2 and S2, for 5 days each, and the 9 principal tidal constituents composed, for 31 days. The tidal analysis of the

  14. Carbon sequestration by Australian tidal marshes

    KAUST Repository

    Macreadie, Peter I.

    2017-03-10

    Australia\\'s tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia\\'s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha-1 (range 14-963 Mg OC ha-1). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha-1 yr-1. Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia\\'s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr-1, with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

  15. The tidal tails of NGC 2298

    CERN Document Server

    Balbinot, Eduardo; da Costa, Luiz N; Makler, Martin; Maia, Marcio A G

    2011-01-01

    We present an implementation of the matched-filter technique to detect tidal tails of globular clusters. The method was tested using SDSS data for the globular cluster Palomar 5 revealing its well known tidal tails. We also ran a simulation of a globular cluster with a tidal tail where we successfully recover the tails for a cluster at the same position and with the same characteristics of NGC 2298. Based on the simulation we estimate that the matched-filter increases the contrast of the tail relative to the background of stars by a factor of 2.5 for the case of NGC 2298. We also present the photometry of the globular cluster NGC 2298 using the MOSAIC2 camera installed on the CTIO 4m telescope. The photometry covers ~ 3deg2 reaching V ~ 23. A fit of a King profile to the radial density profile of NGC 2298 shows that this cluster has a tidal radius of 15.91' \\pm 1.07' which is twice as in the literature. The application of the matched-filter to NGC 2298 reveals several extra-tidal structures, including a leadi...

  16. Tidally Heated Terrestrial Exoplanets: Viscoelastic Response Models

    CERN Document Server

    Henning, Wade G; Sasselov, Dimitar D; 10.1088/0004-637X/707/2/1000

    2009-01-01

    Tidal friction in exoplanet systems, driven by orbits that allow for durable nonzero eccentricities at short heliocentric periods, can generate internal heating far in excess of the conditions observed in our own solar system. Secular perturbations or a notional 2:1 resonance between a Hot Earth and Hot Jupiter can be used as a baseline to consider the thermal evolution of convecting bodies subject to strong viscoelastic tidal heating. We compare results first from simple models using a fixed Quality factor and Love number, and then for three different viscoelastic rheologies: the Maxwell body, the Standard Anelastic Solid, and the Burgers body. The SAS and Burgers models are shown to alter the potential for extreme tidal heating by introducing the possibility of new equilibria and multiple response peaks. We find that tidal heating tends to exceed radionuclide heating at periods below 10-30 days, and exceed insolation only below 1-2 days. Extreme cases produce enough tidal heat to initiate global-scale parti...

  17. Carbon sequestration by Australian tidal marshes

    Science.gov (United States)

    Macreadie, Peter I.; Ollivier, Q. R.; Kelleway, J. J.; Serrano, O.; Carnell, P. E.; Ewers Lewis, C. J.; Atwood, T. B.; Sanderman, J.; Baldock, J.; Connolly, R. M.; Duarte, C. M.; Lavery, P. S.; Steven, A.; Lovelock, C. E.

    2017-03-01

    Australia’s tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia’s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha-1 (range 14-963 Mg OC ha-1). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha-1 yr-1. Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia’s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr-1, with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

  18. Tidal Response of Preliminary Jupiter Model

    Science.gov (United States)

    Wahl, Sean M.; Hubbard, William B.; Militzer, Burkhard

    2016-11-01

    In anticipation of improved observational data for Jupiter’s gravitational field, from the Juno spacecraft, we predict the static tidal response for a variety of Jupiter interior models based on ab initio computer simulations of hydrogen-helium mixtures. We calculate hydrostatic-equilibrium gravity terms, using the non-perturbative concentric Maclaurin Spheroid method that eliminates lengthy expansions used in the theory of figures. Our method captures terms arising from the coupled tidal and rotational perturbations, which we find to be important for a rapidly rotating planet like Jupiter. Our predicted static tidal Love number, {k}2=0.5900, is ˜10% larger than previous estimates. The value is, as expected, highly correlated with the zonal harmonic coefficient J 2, and is thus nearly constant when plausible changes are made to the interior structure while holding J 2 fixed at the observed value. We note that the predicted static k 2 might change, due to Jupiter’s dynamical response to the Galilean moons, and find reasons to argue that the change may be detectable—although we do not present here a theory of dynamical tides for highly oblate Jovian planets. An accurate model of Jupiter’s tidal response will be essential for interpreting Juno observations and identifying tidal signals from effects of other interior dynamics of Jupiter’s gravitational field.

  19. Metric 3-Leibniz algebras and M2-branes

    CERN Document Server

    Méndez-Escobar, Elena

    2010-01-01

    This thesis is concerned with superconformal Chern-Simons theories with matter in 3 dimensions. The interest in these theories is two-fold. On the one hand, it is a new family of theories in which to test the AdS/CFT correspondence and on the other, they are important to study one of the main objects of M-theory (M2-branes). All these theories have something in common: they can be written in terms of 3-Leibniz algebras. Here we study the structure theory of such algebras, paying special attention to a subclass of them that gives rise to maximal supersymmetry and that was the first to appear in this context: 3-Lie algebras. In chapter 2, we review the structure theory of metric Lie algebras and their unitary representations. In chapter 3, we study metric 3-Leibniz algebras and show, by specialising a construction originally due to Faulkner, that they are in one to one correspondence with pairs of real metric Lie algebras and unitary representations of them. We also show a third characterisation for six extreme...

  20. Fermi surface behavior in the ABJM M2-brane theory

    Science.gov (United States)

    DeWolfe, Oliver; Henriksson, Oscar; Rosen, Christopher

    2015-06-01

    We calculate fermionic Green's functions for states of the three-dimensional Aharony-Bergman-Jafferis-Maldacena M2-brane theory at large N using the gauge-gravity correspondence. We embed extremal black brane solutions in four-dimensional maximally supersymmetric gauged supergravity, obtain the linearized Dirac equations for each spin-1 /2 mode that cannot mix with a gravitino, and solve these equations with infalling boundary conditions to calculate retarded Green's functions. For generic values of the chemical potentials, we find Fermi surfaces with universally non-Fermi liquid behavior, matching the situation for four-dimensional N =4 super-Yang-Mills. Fermi surface singularities appear and disappear discontinuously at the point where all chemical potentials are equal, reminiscent of a quantum critical point. One limit of parameter space has zero entropy at zero temperature, and fermionic fluctuations are perfectly stable inside an energy region around the Fermi surface. An ambiguity in the quantization of the fermions is resolved by supersymmetry.

  1. Fusion to chicken C3d enhances the immunogenicity of the M2 protein of avian influenza virus

    Directory of Open Access Journals (Sweden)

    Zhang Li

    2010-05-01

    Full Text Available Abstract Background Current vaccines to avian influenzae virus (AIV, a highly contagious disease of birds, need to be constantly updated due to the high level of variation in the target antigens. Therefore, a vaccine that could induce broad cross protection against AIV is required. The M2 membrane protein is structurally conserved amongst AIV subtypes but tends in induce a poor immune response, whereas C3d has been shown in many species to enhance immunogenicity. In this study, we investigated the potential of M2-avian C3d fusion proteins to provide effective immunity. Results We fused chicken complement C3d to sM2 (M2 protein with the transmembrane region deleted of AIV and expressed four fusion proteins, GST (Glutathione S-transferase tagged proteins in pGEX expression vector -C3d-sM2, GST-C3d-L2-sM2, GST-C3d-L1-C3d-sM2 and GST-C3d-L1-C3d-L2-sM2 were used to immunize mice. In addition, Specific pathogen free (SPF chickens were inoculated with the plasmids pcDNA-sM2, pcDNA-C3d-L1-C3d-L2-sM2, GST-sM2 and GST-C3d-L1-C3d-L2-sM2. The immune response was monitored by an enzyme-linked immunosorbent assay (ELISA for sM2 antibody, and all the test animals were challenged with A/chicken/Bei Jing/WD9/98 (H9N2 virus. Results revealed that the anti-sM2 antibody in mice and chickens vaccinated with these proteins was higher than the nonfused forms of sM2, the GST-C3d-L1-C3d-L2-sM2 groups have conferred the highest 30% and 20% protection ratio in mice and chickens respectively. In addition, the pcDNA-C3d-L1-C3d-L2-sM2 also enhances the antibody responses to sM2 compared to pcDNA-sM2 in chickens, and acquired 13.3% protection ratio. Conclusion These results indicated that chicken C3d enhanced the humoral immunity against AIV M2 protein either fused proteins expressed by the prokaryotic system or with the DNA vaccine. Nevertheless, in view of the poor protection ratio for these animals, we speculated that this is not a worthy developing of vaccine in these

  2. Ocean energy. Tide and tidal power

    Energy Technology Data Exchange (ETDEWEB)

    Finkl, Charles W. [Coastal Planning and Engineering, Inc., Boca Raton, FL (United States); Charlier, Roger H.

    2009-07-01

    Engineers' dreams and fossil energy replacement schemes can come true. Man has been tapping the energy of the sea to provide power for his industries for centuries. Tidal energy combined with that of waves and marine winds rank among those most successfully put the work. Large scale plants are capital intensive but smaller ones, particularly built in China, have proven profitable. Since the initiation of the St Malo project in France, similar projects have gone into active service where methods have been devised to cut down on costs, new types of turbines developed and cost competitiveness considerably improved. Tidal power has enormous potential. The book reviews recent progress in extracting power from the ocean, surveys the history of tidal power harnessing and updates a prior publication by the author. (orig.)

  3. On Tidal Inference in the Diurnal Band

    Science.gov (United States)

    Ray, R. D.

    2017-01-01

    Standard methods of tidal inference should be revised to account for a known resonance that occurs mostly within the K(sub 1) tidal group in the diurnal band. The resonance arises from a free rotational mode of Earth caused by the fluid core. In a set of 110 bottom-pressure tide stations, the amplitude of the P(sub 1) tidal constituent is shown to be suppressed relative to K(sub 1), which is in good agreement with the resonance theory. Standard formulas for the K(sub 1) nodal modulation remain essentially unaffected. Two examples are given of applications of the refined inference methodology: one with monthly tide gauge data and one with satellite altimetry. For some altimeter-constrained tide models, an inferred P(sub 1) constituent is found to be more accurate than a directly determined one.

  4. The wave and tidal resource of Scotland

    Science.gov (United States)

    Neill, Simon; Vogler, Arne; Lewis, Matt; Goward-Brown, Alice

    2017-04-01

    As the marine renewable energy industry evolves, in parallel with an increase in the quantity of available data and improvements in validated numerical simulations, it is occasionally appropriate to re-assess the wave and tidal resource of a region. This is particularly true for Scotland - a leading nation that the international community monitors for developments in the marine renewable energy industry, and which has witnessed much progress in the sector over the last decade. With 7 leased wave and 17 leased tidal sites, Scotland is well poised to generate significant levels of electricity from its abundant natural marine resources. In this review of Scotland's wave and tidal resource, I present the theoretical and technical resource, and provide an overview of commercial progress. I also discuss issues that affect future development of the marine energy seascape in Scotland, applicable to other regions of the world, including the potential for developing lower energy sites, and grid connectivity.

  5. HI Recycling Formation of Tidal Dwarf Galaxies

    CERN Document Server

    Duc, P A; Duc, Pierre-Alain; Brinks, Elias

    2000-01-01

    Galactic collisions trigger a number of phenomena, such as transportation inward of gas from distances of up to kiloparsecs from the center of a galaxy to the nuclear region, fuelling a central starburst or nuclear activity. The inverse process, the ejection of material into the intergalactic medium by tidal forces, is another important aspect and can be studied especially well through detailed HI observations of interacting systems which have shown that a large fraction of the gaseous component of colliding galaxies can be expelled. Part of this tidal debris might fall back, be dispersed throughout the intergalactic medium or recondense to form a new generation of galaxies: the so-called tidal dwarf galaxies. The latter are nearby examples of galaxies in formation. The properties of these recycled objects are reviewed here and different ways to identify them are reviewed.

  6. Double tidal disruptions in galactic nuclei

    CERN Document Server

    Mandel, Ilya

    2015-01-01

    A star on a nearly radial trajectory approaching a massive black hole (MBH) gets tidally disrupted if it comes sufficiently close to the MBH. Here we explore what happens to binary stars whose centers of mass approach the MBH on nearly radial orbits. The interaction with the MBH often leads to both stars being disrupted in sequence. We argue that such events could produce light curves that are substantially different from those of the single disruptions, with possible features such as two local maxima. Tidal forces from the MBH can also lead the binary components to collide; these merger products can form highly magnetized stars, whose subsequent tidal disruption may enable prompt jet formation.

  7. DOUBLE TIDAL DISRUPTIONS IN GALACTIC NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Mandel, Ilya [School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT (United Kingdom); Levin, Yuri, E-mail: imandel@star.sr.bham.ac.uk, E-mail: yuri.levin@monash.edu [Monash Center for Astrophysics and School of Physics, Monash University, Clayton, VIC 3800 (Australia)

    2015-05-20

    A star on a nearly radial trajectory approaching a massive black hole (MBH) gets tidally disrupted if it comes sufficiently close to the MBH. Here we explore what happens to binary stars whose centers of mass approach the MBH on nearly radial orbits. The interaction with the MBH often leads to both stars being disrupted in sequence. We argue that such events could produce light curves that are substantially different from those of the single disruptions, with possible features such as two local maxima. Tidal forces from the MBH can also lead the binary components to collide; these merger products can form highly magnetized stars, whose subsequent tidal disruption may enable prompt jet formation.

  8. Tidal Forces in Naked Singularity Backgrounds

    CERN Document Server

    Goel, Akash; Roy, Pratim; Sarkar, Tapobrata

    2015-01-01

    The end stage of a gravitational collapse process can generically result in a black hole or a naked singularity. Here we undertake a comparative analysis of the nature of tidal forces in these backgrounds. The effect of such forces is generically exemplified by the Roche limit, which predicts the distance within which a celestial object disintegrates due to the tidal effects of a second more massive object. In this paper, using Fermi normal coordinates, we numerically compute the Roche limit for a class of non-rotating naked singularity backgrounds, and compare them with known results for Schwarzschild black holes. Our analysis indicates that there might be substantially large deviations in the magnitudes of tidal forces in naked singularity backgrounds, compared to the black hole cases. If observationally established, these can prove to be an effective indicator of the nature of the singularity at a galactic centre.

  9. Tidal response of Europa's subsurface ocean

    Science.gov (United States)

    Karatekin, Özgür; Comblen, Richard; Toubeau, Jonathan; Deleersnijder, Eric; van Hoolst, Tim; Dehant, Veronique

    2010-05-01

    Observations of Cassini and Galileo spacecrafts suggest the presence of subsurface global water oceans under the icy shells of several satellites of Jupiter and Saturn. Previous studies have shown that in the presence of subsurface oceans, time-variable tides cause large periodic surface displacements and that tidal dissipation in the icy shell becomes a major energy source that can affect long-term orbital evolution. However, in most studies so far, the dynamics of these satellite oceans have been neglected. In the present study, we investigate the tidal response of the subsurface ocean of Europa to a time-varying potential. Two-dimensional nonlinear shallow water equations are solved on a sphere by means of a finite element code. The resulting ocean tidal flow velocities and surface displacements will be presented.

  10. Tidal Response of Preliminary Jupiter Model

    CERN Document Server

    Wahl, Sean M; Militzer, Burkhard

    2016-01-01

    In anticipation of improved observational data for Jupiter's gravitational field from the Juno spacecraft, we predict the static tidal response for a variety of Jupiter interior models based on ab initio computer simulations of hydrogen-helium mixtures. We calculate hydrostatic-equilibrium gravity terms using the non-perturbative concentric Maclaurin Spheroid (CMS) method that eliminates lengthy expansions used in the theory of figures. Our method captures terms arising from the coupled tidal and rotational perturbations, which we find to be important for a rapidly-rotating planet like Jupiter. Our predicted static tidal Love number $k_2 = 0.5900$ is $\\sim$10\\% larger than previous estimates. The value is, as expected, highly correlated with the zonal harmonic coefficient $J_2$, and is thus nearly constant when plausible changes are made to interior structure while holding $J_2$ fixed at the observed value. We note that the predicted static $k_2$ might change due to Jupiter's dynamical response to the Galilea...

  11. Tidal torques: a critical review of some techniques

    Science.gov (United States)

    Efroimsky, Michael; Williams, James G.

    2009-07-01

    We review some techniques employed in the studies of torques due to bodily tides, and explain why the MacDonald formula for the tidal torque is valid only in the zeroth order of the eccentricity divided by the quality factor, while its time-average is valid in the first order. As a result, the formula cannot be used for analysis in higher orders of e/ Q. This necessitates some corrections in the current theory of tidal despinning and libration damping (though the qualitative conclusions of that theory may largely remain correct). We demonstrate that in the case when the inclinations are small and the phase lags of the tidal harmonics are proportional to the frequency, the Darwin-Kaula expansion is equivalent to a corrected version of the MacDonald method. The latter method rests on the assumption of existence of one total double bulge. The necessary correction to MacDonald’s approach would be to assert (following Singer, Geophys. J. R. Astron. Soc., 15: 205-226, 1968) that the phase lag of this integral bulge is not constant, but is proportional to the instantaneous synodal frequency (which is twice the difference between the evolution rates of the true anomaly and the sidereal angle). This equivalence of two descriptions becomes violated by a nonlinear dependence of the phase lag upon the tidal frequency. It remains unclear whether it is violated at higher inclinations. Another goal of our paper is to compare two derivations of a popular formula for the tidal despinning rate, and emphasise that both are strongly limited to the case of a vanishing inclination and a certain (sadly, unrealistic) law of frequency-dependence of the quality factor Q—the law that follows from the phase lag being proportional to frequency. One of the said derivations is based on the MacDonald torque, the other on the Darwin torque. Fortunately, the second approach is general enough to accommodate both a finite inclination and the actual rheology. We also address the rheological models

  12. Elastic tidal response of a laterally heterogeneous planet: a complete perturbation formulation

    Science.gov (United States)

    Qin, Chuan; Zhong, Shijie; Wahr, John

    2016-10-01

    Constraining laterally varying structures in planetary interiors is important for understanding both the composition and the internal dynamics of a planet. Recognizing that seismic imaging technique is currently only viable for studying the Earth's interior structures, methods that can be supported by advanced space geodetic techniques may become alternatives to `image' the interiors of other planets. The method of tidal tomography is one possibility, and it relies on high precision measurement of the response of a planet to its body tide. However, it is essential to develop an efficient analytical tool that computes the dependence of tidal response to 3-D interior structures. In this paper, we present a complete formulation of such an analytical tool, which calculates to high accuracy the tidal response of a terrestrial planet with lateral heterogeneities in its elastic and density structures. We treat the lateral heterogeneities as small perturbations and derive the governing equations based on the perturbation theory. In a spherical harmonic representation, equations at each order of perturbation are reduced into multiple matrix equations at harmonics that are allowed by mode couplings, and the total response equals the sum of all those single-harmonic responses, which can be solved semi-analytically. We test our perturbation method by applying it to the Moon with a harmonic degree-1 mantle structure for which the perturbation solutions of the tidal response are compared with those from a fully numerical method. The remarkable agreement between results from these two methods validates the perturbation method. As an example, we then use the perturbation method to evaluate the impact of lunar crustal thickness variations on tidal response of the Moon. We find that lunar crust produces much smaller degree-3 tidal responses than a relatively weak degree-1 structure in the deep lunar mantle. Our calculations show that degree-3 tidal response measurements may hold key

  13. The assessment of extactable tidal energy and the effect of tidal energy turbine deployment on the hydrodynamics in Zhoushan

    Institute of Scientific and Technical Information of China (English)

    HOU Fang; BAO Xianwen; LI Benxia; LIU Qianqian

    2015-01-01

    In this study, we construct one 2–dimensional tidal simulation, using an unstructured Finite Volume Coastal Ocean Model (FVCOM). In the 2–D model, we simulated the tidal turbines through adding additional bottom drag in the element where the tidal turbines reside. The additional bottom drag was calculated from the relationship of the bottom friction dissipation and the rated rotor efficiency of the tidal energy turbine. This study analyzed the effect of the tidal energy turbine to the hydrodynamic environment, and calculated the amount of the extractable tidal energy resource at the Guishan Hangmen Channel, considering the rotor wake effect.

  14. Baroclinic Effects on Tidal Propagation and Estuarine Circulation: an Idealized Modeling Analysis

    Science.gov (United States)

    Cao, Z.; Olabarrieta, M.

    2016-02-01

    This study evaluates the baroclinic effects on the propagation of a semidiurnal tide and on the estuarine circulation by applying a three-dimensional Regional Ocean Modeling System (ROMS) to an idealized estuary. Different riverine flows and tidal amplitudes are considered to generate various types of estuaries (from strongly stratified to well mixed) in the estuarine parameter space, which is based on the freshwater Froude number (Fr) and mixing number (M). Two groups of scenarios, with and without density difference between riverine flow and ocean water, are carried out. Tidal wave characteristics and residual currents of each scenario are investigated. In strongly stratified estuaries, the baroclinic effects result in a typical bidirectional estuarine circulation, with the surface water flowing downstream and bottom water flowing upstream; if no density variations are considered, the residual current will flow downstream. In well mixed estuaries, surface water goes upstream due to Stokes Drift and bottom water goes downstream as a compensating flow, which can be found in both barotropic and baroclinic simulations. In partially mixed estuaries, without considering the density variations, the estuarine circulation patterns are similar to those in well mixed estuaries; the baroclinic effects will generate a triple-directional estuarine circulation, characterized by a downstream flow below the tidal wave trough and an upstream flow close to the bottom; between the wave crest and trough the residual current is directed upstream due to the Stokes Drift. Tidal amplitude is increasingly amplified from estuary mouth to head in all scenarios, and the intensity of this amplification is larger in baroclinic simulations. The strongest baroclinic effects on the tidal propagation occur in partially mixed estuaries, where the tidal amplitude can increase up to 30% due to baroclinic effects.

  15. Tidal forces in Kiselev black hole

    Energy Technology Data Exchange (ETDEWEB)

    Shahzad, M.U. [University of Central Punjab, CAMS, UCP Business School, Lahore (Pakistan); Jawad, Abdul [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan)

    2017-06-15

    The aim of this paper is to examine the tidal forces occurring in a Kiselev black hole surrounded by radiation and dust fluids. It is noted that the radial and angular components of the tidal force change the sign between event and Cauchy horizons. We solve the geodesic deviation equation for radially free-falling bodies toward Kiselev black holes. We explain the geodesic deviation vector graphically and point out the location of the event and Cauchy horizons for specific values of the radiation and dust parameters. (orig.)

  16. CFD for wind and tidal offshore turbines

    CERN Document Server

    Montlaur, Adeline

    2015-01-01

    The book encompasses novel CFD techniques to compute offshore wind and tidal applications. Computational fluid dynamics (CFD) techniques are regarded as the main design tool to explore the new engineering challenges presented by offshore wind and tidal turbines for energy generation. The difficulty and costs of undertaking experimental tests in offshore environments have increased the interest in the field of CFD which is used to design appropriate turbines and blades, understand fluid flow physical phenomena associated with offshore environments, predict power production or characterise offshore environments, amongst other topics.

  17. Cycloidal tidal power generation - Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This report summarises the findings of a project investigating the economic and technical viability of a cycloidal tidal stream generator and developing a performance prediction model to assess the applicability of cycloidal turbines to power generation. The concept of cycloidal power generation is described along with the use of the model to examine the performance of six designs in the tidal flow off the west coast of Scotland. Details are given of the estimated power generated and cost reductions using optimised designs. Areas to be examined for design optimisation are listed.

  18. Investigation on Tidal Components in GPS Coordinates

    Science.gov (United States)

    Araszkiewicz, Andrzej; Bogusz, Janusz; Figurski, Mariusz

    2009-01-01

    This paper presents analyses on the GPS coordinates from sub-diurnal solutions of EPN data provided by Warsaw Military University of Technology. The aim of this research is to investigate the way the tidal models used in Bernese software (solid Earth and ocean tides as well) fit to the individual conditions of EPN stations. The 1-hour solution technique of GPS data processing was utilized to obtain coordinates of above 70 EPN stations. Additionally several Polish permanent sites with clearly seen oscillations were examined. This processing technique allowed us to recognize diurnal and sub-diurnal residual oscillations which could be next utilized for validation of the tidal models.

  19. Tidal forces in Reissner-Nordstroem spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Crispino, Luis C.B.; Oliveira, Ednilton S. de [Universidade Federal do Para, Faculdade de Fisica, Belem, Para (Brazil); Higuchi, Atsushi; Oliveira, Leandro A. [University of York, Department of Mathematics, York (United Kingdom)

    2016-03-15

    We analyze the tidal forces produced in the spacetime of Reissner-Nordstroem black holes. We point out that the radial component of the tidal force changes sign just outside the event horizon if the charge-to-mass ratio is close to 1, unlike in Schwarzschild spacetime of uncharged black holes, and that the angular component changes sign between the outer and inner horizons. We solve the geodesic deviation equations for radially falling bodies toward the charged black hole. We find, for example, that the radial component of the geodesic deviation vector starts decreasing inside the event horizon unlike in the Schwarzschild case. (orig.)

  20. Turning the tide: effects of river inflow and tidal amplitude on sandy estuaries in laboratory landscape experiments

    Science.gov (United States)

    Kleinhans, Maarten; Braat, Lisanne; Leuven, Jasper; Baar, Anne; van der Vegt, Maarten; van Maarseveen, Marcel; Markies, Henk; Roosendaal, Chris; van Eijk, Arjan

    2016-04-01

    Many estuaries formed over the Holocene through a combination of fluvial and coastal influxes, but how estuary planform shape and size depend on tides, wave climate and river influxes remains unclear. Here we use a novel tidal flume setup of 20 m length by 3 m width, the Metronome (http://www.uu.nl/metronome), to create estuaries and explore a parameter space for the simple initial condition of a straight river in sandy substrate. Tidal currents capable of transporting sediment in both the ebb and flood phase because they are caused by periodic tilting of the flume rather than the classic method of water level fluctuation. Particle imaging velocimetry and a 1D shallow flow model demonstrate that this principle leads to similar sediment mobility as in nature. Ten landscape experiments recorded by timelapse overhead imaging and AGIsoft DEMs of the final bed elevation show that absence of river inflow leads to short tidal basins whereas even a minor discharge leads to long convergent estuaries. Estuary width and length as well as morphological time scale over thousands of tidal cycles strongly depend on tidal current amplitude. Paddle-generated waves subdue the ebb delta causing stronger tidal currents in the basin. Bar length-width ratios in estuaries are slightly larger to those in braided rivers in experiments and nature. Mutually evasive ebb- and flood-dominated channels are ubiquitous and appear to be formed by an instability mechanism with growing bar and bifurcation asymmetry. Future experiments will include mud flats and live vegetation.

  1. Tidal propagation off the central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    Present study reviews the characteristics of tidal propagation on the continental shelf off the central west coast of India. Available observations from tide gauges are used to describe the variations of tidal ranges along the west coast. Amplitudes...

  2. Sub-tidal water-level oscillations in the Mandovi estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.; Vijith, V.

    . The zonal and meridional components of the currents were first de-tided using the software Tidal Analysis Software Kit (TASK; Bell et al., 1998). The de-tided (residual) current components were then rotated to yield the along-shore and cross... Analysis Software Kit 2000 (TASK-2000), Permanent Service for Mean Sea Level, Proudman Oceanographic Laboratory, Merseyside, U.K. Durand, F., Shankar, D., Birol, F., Shenoi, S. S. C., 2009. Spatiotemporal structure of the East India Coastal Current...

  3. Influence of Sea Level Rise and Marsh Hypsometry on the Equilibrium Morphology of Tidal Inlets

    Science.gov (United States)

    Lovering, J. L.; Adams, P. N.

    2011-12-01

    As global sea level is predicted to rise between 0.18 and 1.9 meters by the end of the 21st century, it is critical to understand how the geomorphology and ecology of coastal regions worldwide will be affected for a range of sea level rise rate scenarios. Tidal inlets along sandy, passive margin coasts are sensitive to water levels, nearshore currents, and wave fields, so changes in environmental conditions in the vicinity of inlets should drive a morphologic response. Due to their importance in commercial shipping, military navigation, and recreation, an improved understanding of tidal inlet response to sea level rise will assist in future planning efforts. The widely accepted conceptual model of tidal inlet evolution predicts that, as sea level rises, salt marshes in the lagoon become drowned and converted to subtidal environments, increasing accommodation space in the back barrier basin. This conversion increases the tidal prism, inlet cross-sectional area, and ebb shoal volume. The purpose of this study is to quantify the relationship between sea level rise, the ecomorphodynamic environment of the back barrier basin, and the resulting changes in equilibrium tidal inlet morphology. Threshold values of sea level rise rate for which marsh habitats convert to subtidal environments, determined by the tidal range and suspended sediment concentration found in the back barrier basin, were developed using previously published numerical simulations and field-based observations. We paired the threshold values with Escoffier equilibrium curve calculations, in order to predict changes in tidal inlet equilibrium cross-sectional area. Halophytic vegetation that is supplied with high suspended sediment concentrations and lives in an area with a high tidal range is able to trap sediment and drive vertical accretion at a faster pace than vegetation in areas of low sediment availability and low tidal range; therefore marshes with high sediment availability and tidal range are

  4. Shelf waves with diurnal tidal frequency at the Greenland shelf edge

    NARCIS (Netherlands)

    Lam, F.P.A.

    1999-01-01

    Tidal analysis has been carried out on current measurements at a “cross-shelf” transect off Greenland at 71o N. The diurnal tides manifest themselves mainly as a barotropic continental shelf wave, travelling southward along the shelf slope. This follows from the amplitude distribution of the diurnal

  5. Barotropic tidal model for the Bombay High, Gulf of Khambhat and surrounding areas

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.; Shetye, S.R.; Michael, G.S.

    A barotropic model is developed for the shelf region off the central west coast of India, which includes the regions of Bombay High and Gulf of Khambhat, in order to simulate tides and tidal currents in the region. The model is forced by a composite...

  6. Methodology for a Regional Tidal Model Evaluation, With Application to Central California

    Science.gov (United States)

    2009-01-01

    diu nally varying cross-shelf pressure gradients (setup/setdown) res ilting in baro - tropic currents felt throughout the water colun n (Rosenfeld...moorings off Pt Sur and the AOSN moorings; Gary Egbert and Lana Erofeeva (OSU) for | roviding tidal solutions for the West Coast; and Paul Martin

  7. Tidal and subtidal flow patterns o a tropical continental shelf semi-insulated by coral reefs

    NARCIS (Netherlands)

    Tarya, A.; Hoitink, A.J.F.; Vegt, van der M.

    2010-01-01

    The present study sets out to describe the tidal and subtidal water motion at the Berau coastal shelf, which represents a tropical continental shelf area of variable width hosting a complex of barrier reefs along its oceanic edge. Moored and shipboard measurements on currents and turbulence were mad

  8. Tidal Channels of Skagit Bay: Three-Dimensional Hydrodynamics and Morphodynamic Evolution

    Science.gov (United States)

    2011-09-30

    is good. ] IMPACT/APPLICATIONS The fronts we measured are clear to remote sensors. Hydraulic control processes , which closely link frontal...journal. RESULTS We have found that hydraulic control theory explains the formation of intense baroclinic fronts along the edges of tidal...these researchers to compare turbulent dissipation rates estimated using our current meters with sediment flocculation estimated using their co

  9. Temporal variations in the flow of a large Antarctic ice-stream controlled by tidally induced changes in the subglacial water system

    Directory of Open Access Journals (Sweden)

    S. H. R. Rosier

    2015-04-01

    7 × 109 m2d-1, with sliding law exponents m = 3 and q =10. Coupled model results show the presence of tides result in a ~ 12% increase in mean surface velocity. Observations of tidally-induced variations in flow of ice-streams provide stronger constraints on basal sliding processes than provided by any other set of measurements.

  10. Study of the turbulent wake behind a tidal turbine through different numerical models

    Science.gov (United States)

    Teymour Javaherchi Mozafari, Amir; Aliseda, Alberto; Antheaume, Sylvain; Seydel, Joseph; Polagye, Brian

    2009-11-01

    As developing sources of renewable energy becomes a critical priority, research in this field become more essential. A novel method to produce clean renewable energy is extraction from ocean tides via a turbine. Although energy generation from tidal currents has many similarities to wind, the balance between kinetic and potential energy is a key element in tidal channels that invalidates ``Betz's'' limit. Other practical differences arise from the concentrated nature of tidal resources which impose very close turbine spacing for economic reasons. These, together with the potential influence of geometric constraints imposed by free surface and tidal channel walls, makes the study of the turbulent wake in tidal energy extraction a very important problem in development of this technology from economical and environmental aspects. We will present numerical simulations of turbulent wake behind a well characterized two-bladed turbine using a hierarchy of different models: Actuator Disk, Virtual Blade, the Single and Multiple Reference Frame and Sliding Mesh model with various boundary conditions and inlet velocity profiles. We will compare the results, discuss the differences among these models and the potential for each one to answer questions about optimization of energy extraction and environmental impacts.

  11. Preliminary assessment of landslide-induced wave hazards, Tidal Inlet, Glacier Bay National Park, Alaska

    Science.gov (United States)

    Wieczorek, Gerald F.; Jakob, Matthias; Motyka, Roman J.; Zirnheld, Sandra L.; Craw, Patricia

    2003-01-01

    A large potential rock avalanche above the northern shore of Tidal Inlet, Glacier Bay National Park, Alaska, was investigated to determine hazards and risks of landslide-induced waves to cruise ships and other park visitors. Field and photographic examination revealed that the 5 to 10 million cubic meter landslide moved between AD 1892 and 1919 after the retreat of Little Ice Age glaciers from Tidal Inlet by AD 1890. The timing of landslide movement and the glacial history suggest that glacial debuttressing caused weakening of the slope and that the landslide could have been triggered by large earthquakes of 1899-1900 in Yakutat Bay. Evidence of recent movement includes fresh scarps, back-rotated blocks, and smaller secondary landslide movements. However, until there is evidence of current movement, the mass is classified as a dormant rock slump. An earthquake on the nearby active Fairweather fault system could reactivate the landslide and trigger a massive rock slump and debris avalanche into Tidal Inlet. Preliminary analyses show that waves induced by such a landslide could travel at speeds of 45 to 50 m/s and reach heights up to 76 m with wave runups of 200 m on the opposite shore of Tidal Inlet. Such waves would not only threaten vessels in Tidal Inlet, but would also travel into the western arm of Glacier Bay endangering large cruise ships and their passengers.

  12. Quantifying the effects of tidal amplitude on river delta network flow partitioning

    Science.gov (United States)

    Hiatt, M. R.; Sendrowski, A.; Passalacqua, P.

    2014-12-01

    Deltas are generally classified as river-, tide-, or wave-dominated systems, but the influences of all environmental forces cannot be ignored when fully addressing the dynamics of the system. For example, in river-dominated deltas, river flow from the feeder channel acts as the primary driver of dynamics within the system by delivering water, sediment, and nutrients through the distributary channels, but tides and waves may affect their allocation within the network. There has been work on the asymmetry of environmental fluxes at bifurcations, but relatively few studies exist on the water partitioning at the network scale. Understanding the network and environmental effects on the flux of water, sediment, and nutrients would benefit delta restoration projects and management practices. In this study, we investigate the allocation of water flow among the five major distributary channels at Wax Lake Delta (WLD), a micro-tidal river-dominated delta in coastal Louisiana, and the effects of tidal amplitude on distributary channel discharges. We collect and compare discharge results from acoustic Doppler current profiler (ADCP) velocity transects between spring and neap tide and between falling and rising tide. The results show that discharges increased from spring to neap tide and from rising to falling tide. We investigate the spatial gradients of tidal influence within the network and validate hydraulic geometry relations for tidally influenced channels. Our results give insight into the control of network structure on flow partitioning and show the degree of tidal influence on channel flow in the river-dominated WLD.

  13. EcoM2 web portal: Collecting empirical data and supporting companies' ecodesign implementation and management

    DEFF Research Database (Denmark)

    Pigosso, Daniela Cristina Antelmi; McAloone, Tim C.; Rozenfeld, Henrique

    2013-01-01

    of strengths and limitations; and the establishment of strategic roadmaps for improved ecodesign implementation. This paper describes the development of the EcoM2 web portal, which will allow for the framework to be tested on greater numbers of companies and at the same time to provide a quick diagnosis...... of their current ecodesign maturity profile. Analyses of the collected data will allow the establishment of patterns on ecodesign implementation in regards to criteria such as sector and size of companies and the improvement of empirical knowledge on ecodesign implementation and best practices....

  14. Tidal dissipation and the strength of the Earth's internal magnetic field.

    Science.gov (United States)

    Buffett, Bruce A

    2010-12-16

    Magnetic fields at the Earth's surface represent only a fraction of the field inside the core. The strength and structure of the internal field are poorly known, yet the details are important for our understanding of the geodynamo. Here I obtain an indirect estimate for the field strength from measurements of tidal dissipation. Tidally driven flow in the Earth's liquid core develops internal shear layers, which distort the internal magnetic field and generate electric currents. Ohmic losses damp the tidal motions and produce detectable signatures in the Earth's nutations. Previously reported evidence of anomalous dissipation in nutations can be explained with a core-averaged field of 2.5 mT, eliminating the need for high fluid viscosity or a stronger magnetic field at the inner-core boundary. Estimates for the internal field constrain the power required for the geodynamo.

  15. Tidal freshwater wetlands, the fresh dimension of the estuary

    NARCIS (Netherlands)

    Barendregt, A.

    2016-01-01

    Upstream in the estuary, where the river ends, the tidal energy is still present but the constant input from the river creates permanent fresh water conditions. The physical, chemical and biological conditions differ from the brackish part of the tidal area, but by processes from the tidal wave also

  16. Ecological consequences of diurnal flooding in tidal freshwater wetlands

    NARCIS (Netherlands)

    Barendregt, A.; Wassen, M.J.

    2010-01-01

    Diurnal flooding can be observed in the upper end of tidal estuaries, where flooding water originating from the river is constantly fresh. Here, the input from the river is confronted with a tidal wave, so that the sand banks, mud flats, low and high marshes and tidal forests are flooded mostly

  17. Subtidal flow division at a shallow tidal junction

    NARCIS (Netherlands)

    Buschman, F.A.; Hoitink, A.J.F.; Vegt, van der M.; Hoekstra, P.

    2010-01-01

    Tides influence distribution of river discharge at tidally affected channel junctions. At the apex of a channel network in an Indonesian delta, observations of flow division suggest that tidally averaged flow division depends on the tidal range. To understand the mechanisms governing the subtidal fl

  18. Development of Tidal areas: some principles and issues towards systainability

    NARCIS (Netherlands)

    Sang Hyun, P.; Simm, J.; Ritzema, H.P.

    2009-01-01

    The coastal zone comprises only 3% of the earth's surface, but contains a disproportionately high amount of its assets. Tidal areas include all those coastal areas where the tidal processes are capable of affecting man's activity or of being influenced by man. Tidal areas differ greatly depending on

  19. RBP-J is required for M2 macrophage polarization in response to chitin and mediates expression of a subset of M2 genes.

    Science.gov (United States)

    Foldi, Julia; Shang, Yingli; Zhao, Baohong; Ivashkiv, Lionel B; Hu, Xiaoyu

    2016-03-01

    Development of alternatively activated (M2) macrophage phenotypes is a complex process that is coordinately regulated by a plethora of pathways and factors. Here, we report that RBP-J, a DNA-binding protein that integrates signals from multiple pathways including the Notch pathway, is critically involved in polarization of M2 macrophages. Mice deficient in RBP-J in the myeloid compartment exhibited impaired M2 phenotypes in vivo in a chitin-induced model of M2 polarization. Consistent with the in vivo findings, M2 polarization was partially compromised in vitro in Rbpj-deficient macrophages as demonstrated by reduced expression of a subset of M2 effector molecules including arginase 1. Functionally, myeloid Rbpj deficiency impaired M2 effector functions including recruitment of eosinophils and suppression of T cell proliferation. Collectively, we have identified RBP-J as an essential regulator of differentiation and function of alternatively activated macrophages.

  20. M2M communication technology and its application in the intelligrid%M2M通信技术及其在智能电网中的应用

    Institute of Scientific and Technical Information of China (English)

    钟少恒

    2013-01-01

      M2M通信是近年来随着物联网的兴起和发展而得到长足发展的下一代无线通信技术。该技术的发展和普及为智能电网功能的扩展和实现奠定了基础。文章介绍了M2M技术的发展历史和技术特色,探索了M2M通信在智能电网,特别是家庭区域网络的应用前景,同时指出了M2M通信技术目前所面临的问题和挑战。%With the rise and development of IOT, machine-to-machine (M2M) communications is a next generation wireless communications which has significant development. The development and popularization of the technology lay a foundation for the function extension and realization of the intelligrid. The development history and technical features are introduced. The development trend of the M2M communications in intelligrid, especially in home area network is explored. At the same time, the current problems and challenge of the technology is pointed out.

  1. Salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  2. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    2000-01-01

    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had

  3. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    2000-01-01

    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had high

  4. 2008 NWFSC Tidal Freshwater Genetics Results

    Energy Technology Data Exchange (ETDEWEB)

    David Teel

    2009-05-01

    Genetic Analysis of Juvenile Chinook Salmon for inclusion in 'Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008. Annual Report to Bonneville Power Administration, Contract DE-AC05-76RL01830.'

  5. An optimal tuning strategy for tidal turbines

    Science.gov (United States)

    Vennell, Ross

    2016-11-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This `impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing `patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a `smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

  6. Modeling the hydrodynamics in tidal networks

    NARCIS (Netherlands)

    Alebregtse, N.C.

    2016-01-01

    This thesis covers tidal propagation through networks of channels. Such networks are widespread and are often subject to discordant human and natural interests. First, the effect of a secondary channel on the tides in a main channel is explained with the use of an idealized model and the responsible

  7. Tidal evolution of planets around brown dwarfs

    CERN Document Server

    Bolmont, Emeline; Leconte, Jérémy

    2011-01-01

    The tidal evolution of planets orbiting brown dwarfs (BDs) presents an interesting case study because BDs' terrestrial planet forming region is located extremely close-in. In fact, the habitable zones of BDs range from roughly 0.001 to 0.03 AU and for the lowest-mass BDs are located interior to the Roche limit. In contrast with stars, BDs spin up as they age. Thus, the corotation distance moves inward. This has important implications for the tidal evolution of planets around BDs. We used a standard equilibrium tidal model to compute the orbital evolution of a large ensemble of planet-BD systems. We tested the effect of numerous parameters such as the initial semi-major axis and eccentricity, the rotation period of the BD, the masses of both the BD and planet, and the tidal dissipation factors. We find that all planets that form at or beyond the corotation distance and with initial eccentricities smaller than \\sim 0.1 are repelled from the BD. Some planets initially interior to corotation can survive if their ...

  8. On the superradiance-tidal friction correspondence

    CERN Document Server

    Glampedakis, K; Kennefick, D

    2013-01-01

    Since the work of Hartle in the 1970s, and the subsequent development of the the Membrane Paradigm approach to black hole physics it has been widely accepted that superradiant scattering of gravitational waves bears strong similarities with the phenomenon of ``tidal friction'' (well-known from Newtonian gravity) operating in binary systems of viscous material bodies. In this paper we revisit the superradiance-tidal friction analogy within the context of ultracompact relativistic bodies. We advocate that as long as these bodies have non-zero viscosity they should undergo tidal friction that can be construed as a kind of superradiant scattering from the point of view of the dynamics of an orbiting test-body. In addition we consider the presence of anisotropic matter, which is required for at least some ultracompact bodies, if they are to sustain a radius very close to the gravitational radius. We find that the tidal friction/superradiance output is enhanced with increasing anisotropy and that strongly anisotrop...

  9. An optimal tuning strategy for tidal turbines.

    Science.gov (United States)

    Vennell, Ross

    2016-11-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This 'impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing 'patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a 'smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

  10. Unravelling tidal dissipation in gaseous giant planets

    CERN Document Server

    Guenel, Mathieu; Remus, Françoise

    2014-01-01

    Tidal dissipation in planetary interiors is one of the key physical mechanisms that drive the evolution of star-planet and planet-moon systems. New constraints are now obtained both in the Solar and exoplanetary systems. Tidal dissipation in planets is intrinsically related to their internal structure. In particular, fluid and solid layers behave differently under tidal forcing. Therefore, their respective dissipation reservoirs have to be compared. In this letter, we compute separately the contributions of the potential dense rocky/icy core and the convective fluid envelope of gaseous giant planets, as a function of core size and mass. We then compare the associated dissipation reservoirs, by evaluating the frequency-average of the imaginary part of the Love numbers $k^2_2$ in each region. In the case of Jupiter and Saturn-like planets, we show that the viscoelastic dissipation in the core could dominate the turbulent friction acting on tidal inertial waves in the envelope. However, the fluid dissipation wou...

  11. Maximum Likelihood Fitting of Tidal Streams With Application to the Sagittarius Dwarf Tidal Tails

    CERN Document Server

    Cole, Nathan; Magdon-Ismail, Malik; Desell, Travis; Dawsey, Kristopher; Hayashi, Warren; Xinyang,; Liu,; Purnell, Jonathan; Szymanski, Boleslaw; Varela, Carlos; Willett, Benjamin; Wisniewski, James

    2008-01-01

    We present a maximum likelihood method for determining the spatial properties of tidal debris and of the Galactic spheroid. With this method we characterize Sagittarius debris using stars with the colors of blue F turnoff stars in SDSS stripe 82. The debris is located at (alpha, delta, R) = (31.37 deg +/- 0.26 deg, 0.0 deg, 29.22 +/- 0.20 kpc), with a (spatial) direction given by the unit vector , in Galactocentric Cartesian coordinates, and with FWHM = 6.74 +/- 0.06 kpc. This 2.5 degee-wide stripe contains 0.892% as many F turnoff stars as the current Sagittarius dwarf galaxy. Over small spatial extent, the debris is modeled as a cylinder with a density that falls off as a Gaussian with distance from the axis, while the smooth component of the spheroid is modeled with a Hernquist profile. We assume that the absolute magnitude of F turnoff stars is distributed as a Gaussian, which is an improvement over previous methods which fixed the absolute magnitude at Mg0 = 4.2. The effectiveness and correctness of the ...

  12. Thermal Diffusivity and Strength of Tidal Flat Sediments During a Tidal Simulation

    Science.gov (United States)

    2009-01-01

    energetically dynamic regions on earth. Tidal Hats are repositories of terrigenous and biogenous sediments that are shaped by tides, waves and storms and...and energetically dynamic regions on earth. Tidal flats are repositories of terrigenous and biogenous sediments that are shaped by tides, waves and...strength. Finally, sediment bearing capacity and shear strength increased with packing density with the highest shear strength occurring at depth within the

  13. A continuing discussion about the correlation of tidal gravity anomalies and heat flow densities

    Science.gov (United States)

    Melchior, P.

    1995-04-01

    On the basis of several objections, Rydelek et al. (Phys. Earth Planet. Inter., 68: 215-219, 1991) (hereafter noted RZH) denied the existence of a correlation between residuals of tidal gravity ( R) and heat flow ( H) suggested by other workers. To re-examine the whole matter on safe grounds, we previously revised and reanalysed all the original tidal data from 300 stations, taking care of the RZH objections by eliminating what they considered as the important sources of errors in the data, essentially calibration errors of the instruments in amplitude and phase. Using this new data base, we meet here, one by one, the other criticisms not related to the original tidal measurements and show that most of them are not valid, in particular those concerning oceanic load and attraction corrections. The findings are as follows: (1) no correlation between diurnal tide and semi-diurnal tide residuals is normal; (2) distance from the sea is not a valid criterion for elimination of several excellent stations; (3) unexpected residues at the South Pole are not due to imperfections of the cotidal Schwiderski maps but to ice-shelf tides not considered by RZH; (4) the correlation of the tidal gravity residues with the age of tectonic provinces is proposed as an alternative to the correlation with heat flow. The data used in 1991 having been corrected are recalculated for comparison with 1986-1991 statistics: the correlation is confirmed with the same degree of probability. Also, new tidal gravity data obtained since 1990 with 'nullified' instruments, as recommended by RZH, in Africa (31 stations) and Latin America (34 stations), are included in new statistics which also confirm the correlation. The global result, obtained from 174 revised and new stations on all continents, gives a correlation coefficient k = 0.691 with a linear regression R = 0.0201( H - 57) - 0.063 ± 0.0013 (where R is in microgals, and H is in mW m -2). As there is at present no practical or theoretical means

  14. Methods for accurate estimation of net discharge in a tidal channel

    Science.gov (United States)

    Simpson, M.R.; Bland, R.

    2000-01-01

    Accurate estimates of net residual discharge in tidally affected rivers and estuaries are possible because of recently developed ultrasonic discharge measurement techniques. Previous discharge estimates using conventional mechanical current meters and methods based on stage/discharge relations or water slope measurements often yielded errors that were as great as or greater than the computed residual discharge. Ultrasonic measurement methods consist of: 1) the use of ultrasonic instruments for the measurement of a representative 'index' velocity used for in situ estimation of mean water velocity and 2) the use of the acoustic Doppler current discharge measurement system to calibrate the index velocity measurement data. Methods used to calibrate (rate) the index velocity to the channel velocity measured using the Acoustic Doppler Current Profiler are the most critical factors affecting the accuracy of net discharge estimation. The index velocity first must be related to mean channel velocity and then used to calculate instantaneous channel discharge. Finally, discharge is low-pass filtered to remove the effects of the tides. An ultrasonic velocity meter discharge-measurement site in a tidally affected region of the Sacramento-San Joaquin Rivers was used to study the accuracy of the index velocity calibration procedure. Calibration data consisting of ultrasonic velocity meter index velocity and concurrent acoustic Doppler discharge measurement data were collected during three time periods. Two sets of data were collected during a spring tide (monthly maximum tidal current) and one of data collected during a neap tide (monthly minimum tidal current). The relative magnitude of instrumental errors, acoustic Doppler discharge measurement errors, and calibration errors were evaluated. Calibration error was found to be the most significant source of error in estimating net discharge. Using a comprehensive calibration method, net discharge estimates developed from the three

  15. Environmental change on tidal flat induced by anthropogenic effect around west coast of Korean Peninsula

    Science.gov (United States)

    Lee, Yoon-Kyung; Choi, Jong-Kuk; Ryu, Joo-Hyung; Eom, Jinah

    2014-05-01

    deposited tendency showed increase in fine sediments whereas area with eroded tendency showed increase in coarse sediments. This result was compared with the tidal current speed estimated from a hydrological model.

  16. Tidal Energy Conversion Installation at an Estuarine Bridge Site: Resource Evaluation and Energy Production Estimate

    Science.gov (United States)

    Wosnik, M.; Gagnon, I.; Baldwin, K.; Bell, E.

    2015-12-01

    The "Living Bridge" project aims to create a self-diagnosing, self-reporting "smart bridge" powered by a local renewable energy source, tidal energy - transforming Memorial Bridge, a vertical lift bridge over the tidal Piscataqua River connecting Portsmouth, NH and Kittery, ME, into a living laboratory for researchers, engineers, scientists, and the community. The Living Bridge project includes the installation of a tidal turbine at the Memorial Bridge. The energy converted by the turbine will power structural health monitoring, environmental and underwater instrumentation. Utilizing locally available tidal energy can make bridge operation more sustainable, can "harden" transportation infrastructure against prolonged grid outages and can demonstrate a prototype of an "estuarine bridge of the future". A spatio-temporal tidal energy resource assessment was performed using long term bottom-deployed Acoustic Doppler Current Profilers (ADCP) at two locations: near the planned deployment location in 2013-14 for 123 days and mid-channel in 2007 for 35 days. Data were evaluated to determine the amount of available kinetic energy that can be converted into usable electrical energy on the bridge. Changes in available kinetic energy with ebb/flood and spring/neap tidal cycles and electrical energy demand were analyzed. The target deployment site exhibited significantly more energetic ebb tides than flood tides, which can be explained by the local bathymetry of the tidal estuary. A system model is used to calculate the net energy savings using various tidal generator and battery bank configurations. Different resource evaluation methodologies were also analyzed, e.g., using a representative ADCP "bin" vs. a more refined, turbine-geometry-specific methodology, and using static bin height vs. bin height that move w.r.t. the free surface throughout a tidal cycle (representative of a bottom-fixed or floating turbine deployment, respectively). ADCP operating frequencies and bin

  17. Tidally Induced Bars of Galaxies in Clusters

    Science.gov (United States)

    Łokas, Ewa L.; Ebrová, Ivana; del Pino, Andrés; Sybilska, Agnieszka; Athanassoula, E.; Semczuk, Marcin; Gajda, Grzegorz; Fouquet, Sylvain

    2016-08-01

    Using N-body simulations, we study the formation and evolution of tidally induced bars in disky galaxies in clusters. Our progenitor is a massive, late-type galaxy similar to the Milky Way, composed of an exponential disk and a Navarro-Frenk-White dark matter halo. We place the galaxy on four different orbits in a Virgo-like cluster and evolve it for 10 Gyr. As a reference case, we also evolve the same model in isolation. Tidally induced bars form on all orbits soon after the first pericenter passage and survive until the end of the evolution. They appear earlier, are stronger and longer, and have lower pattern speeds for tighter orbits. Only for the tightest orbit are the properties of the bar controlled by the orientation of the tidal torque from the cluster at pericenter. The mechanism behind the formation of the bars is the angular momentum transfer from the galaxy stellar component to its halo. All of the bars undergo extended periods of buckling instability that occur earlier and lead to more pronounced boxy/peanut shapes when the tidal forces are stronger. Using all simulation outputs of galaxies at different evolutionary stages, we construct a toy model of the galaxy population in the cluster and measure the average bar strength and bar fraction as a function of clustercentric radius. Both are found to be mildly decreasing functions of radius. We conclude that tidal forces can trigger bar formation in cluster cores, but not in the outskirts, and thus can cause larger concentrations of barred galaxies toward the cluster center.

  18. Flow paths of water and sediment in a tidal marsh: relations with marsh developmental stage and tidal inundation height

    NARCIS (Netherlands)

    Temmerman, S.; Bouma, T.J.; Govers, G.; Lauwaet, D.

    2005-01-01

    This study provides new insights in the relative role of tidal creeks and the marsh edge in supplying water and sediments to and from tidal marshes for a wide range of tidal inundation cycles with different high water levels and for marsh zones of different developmental stage. Net import or export

  19. THREE-DIMENSIONAL NUMERICAL SIMULATION OF TIDES AND CURRENTS IN FUSHAN BAY, QINGDAO

    Institute of Scientific and Technical Information of China (English)

    LI Ming-kui; HOU Yi-jun; WEI Ze-xun

    2004-01-01

    The three-dimensional Princeton Ocean Model(POM)was employed to simulate the tide and current simultanuously for the first time in the Fushan Bay,Qingdao,China.By adopting the elevation condition that was combined with the tides M2,S2,K1 and O1 at the open boundary and by choosing the proper value of bottom roughness,the horizontal and vertical distributions of the tidal current and water level variations in the bay were computed.The results agree well with the field observation data,indicating that this model can be used to predict accurately the variation of tides and currents in the Fushan Bay and other costal regions in the future.Our study also provides useful information and a data base for the Olympic Projects that will be conducted in the Fushan Bay in 2008.

  20. Reseach on Business Model of M2M Virtual Opertion%M2M虚拟运营的商业模式研究

    Institute of Scientific and Technical Information of China (English)

    景士颖; 乔新春

    2014-01-01

    M2M市场在未来几年拥有较大的增长空间,随着移动转售业务牌照的发放,M2M将成为虚拟运营商可以切入的具备潜力的市场领域之一。探讨M2M虚拟运营的商业模式,分析国际开展M2M虚拟运营的案例,并给出国内开展M2M虚拟运营的建议。%M2M has more market space for growth in the coming years, with the issuance of mobile resale service license, M2M wil become a potential market area where MVNOs can cut into. This article discusses the business model of M2M virtual operation, analyzes the international M2M MVNO business cases, and gives advices to MNOs and MVNOs on how to provide better M2M services in China.

  1. Atmospheric dynamics of Earth-like tidally locked aquaplanets

    CERN Document Server

    Merlis, Timothy M

    2010-01-01

    We present simulations of atmospheres of Earth-like aquaplanets that are tidally locked to their star, that is, planets whose orbital period is equal to the rotation period about their spin axis, so that one side always faces the star and the other side is always dark. As extreme cases illustrating the effects of slow and rapid rotation, we consider planets with rotation periods equal to one current Earth year and one current Earth day. The dynamics responsible for the surface climate (e.g., winds, temperature, precipitation) and the general circulation of the atmosphere are discussed in light of existing theories of atmospheric circulations. For example, as expected from the increasing importance of Coriolis accelerations relative to inertial accelerations as the rotation rate increases, the winds are approximately isotropic and divergent at leading order in the slowly rotating atmosphere but are predominantly zonal and rotational in the rapidly rotating atmosphere. Free-atmospheric horizontal temperature va...

  2. M2e通用流感疫苗的研究进展%Universal influenza vaccine based on the extracellular domain of M2 protein

    Institute of Scientific and Technical Information of China (English)

    花艳红; 王希良

    2009-01-01

    M2基质蛋白是A型流感病毒膜蛋白,在A型流感病毒的生命周期中,M2具有重要的生物学功能,已成为抗病毒药物研究的靶蛋白.其胞外区M2e(M2 eetodomain,M2e)为24个氨基酸残基,该片段在多病毒株中具有极高的保守性.针对M2e产生IgG型抗体能够防止流感病毒引发的死亡,减少动物模型中流感的发病率.了解有关M2e疫苗的研究进展,以及关于M2e作为A型流感疫苗靶抗原的关键问题很重要.%Matrix protein M2 (M2) is the membrane protein of Influenza A with an extracellular domain of 24 amino acid residues, which is strongly conserved across virus strains. M2 plays an important role in the life cy-cle of the Influenza A virus and has been the target of antiviral drugs. IgG subtype antibodies directed against M2e can prevent death from influenza and reduce morbidity in animal models for influenza disease. This review summarizes the findings on M2e vaccine candidates and addresses some key questions about this Influenza A vaccine target.

  3. Decisive disappearance search at high Δ m2 with monoenergetic muon neutrinos

    Science.gov (United States)

    Axani, S.; Collin, G.; Conrad, J. M.; Shaevitz, M. H.; Spitz, J.; Wongjirad, T.

    2015-11-01

    "KPipe" is a proposed experiment which will study muon neutrino disappearance for a sensitive test of the Δ m2˜1 eV2 anomalies, possibly indicative of one or more sterile neutrinos. The experiment is to be located at the J-PARC Materials and Life Science Experimental Facility's spallation neutron source, which represents the world's most intense source of charged kaon decay-at-rest monoenergetic (236 MeV) muon neutrinos. The detector vessel, designed to measure the charged-current interactions of these neutrinos, will be 3 m in diameter and 120 m long, extending radially at a distance of 32 to 152 m from the source. This design allows a sensitive search for νμ disappearance associated with currently favored light sterile neutrino models and features the ability to reconstruct the neutrino oscillation wave within a single, extended detector. The required detector design, technology, and costs are modest. The KPipe measurements will be robust since they depend on a known energy neutrino source with low expected backgrounds. Further, since the measurements rely only on the measured rate of detected events as a function of distance, with no required knowledge of the initial flux and neutrino interaction cross section, the results will be largely free of systematic errors. The experimental sensitivity to oscillations, based on a shape-only analysis of the L /E distribution, will extend an order of magnitude beyond present experimental limits in the relevant high-Δ m2 parameter space.

  4. Tidal modulation of two-layer hydraulic exchange flows

    Directory of Open Access Journals (Sweden)

    L. M. Frankcombe

    2006-11-01

    Full Text Available Time-dependent, two layer hydraulic exchange flow is studied using an idealised shallow water model. It is found that barotropic time-dependent perturbations, representing tidal forcing, increase the baroclinic exchange flux above the steady hydraulic limit, with flux increasing monotonically with tidal amplitude (measured either by height or flux amplitude over a tidal period. Exchange flux also depends on the non-dimensional tidal period, γ, which was introduced by Helfrich (1995. Resonance complicates the relationship between exchange flux and height amplitude, but, when tidal strength is characterised by flux amplitude, exchange flux is a monotonic function of γ.

  5. Recombinant M2e outer membrane vesicle vaccines protect against lethal influenza A challenge in BALB/c mice.

    Science.gov (United States)

    Rappazzo, C Garrett; Watkins, Hannah C; Guarino, Cassandra M; Chau, Annie; Lopez, Jody L; DeLisa, Matthew P; Leifer, Cynthia A; Whittaker, Gary R; Putnam, David

    2016-03-04

    Currently approved influenza vaccines predominantly protect through antibodies directed against the highly variable glycoprotein hemagglutinin (HA), necessitating annual redesign and formulation based on epidemiological prediction of predominant circulating strains. More conserved influenza protein sequences, such as the ectodomain of the influenza M2 protein, or M2e, show promise as a component of a universal influenza A vaccine, but require a Th1-biased immune response for activity. Recently, recombinant, bacterially derived outer membrane vesicles (OMVs) demonstrated potential as a platform to promote a Th1-biased immune response to subunit antigens. Here, we engineer three M2e-OMV vaccines and show that all elicit strong IgG titers, with high IgG2a:IgG1 ratios, in BALB/c mice. Additionally, the administration of one M2e-OMV construct containing tandem heterologous M2e peptides (M2e4xHet-OMV) resulted in 100% survival against lethal doses of the mouse-adapted H1N1 influenza strain PR8. Passive transfer of antibodies from M2e4xHet-OMV vaccinated mice to unvaccinated mice also resulted in 100% survival to challenge, indicating that protection is driven largely via antibody-mediated immunity. The potential mechanism through which M2e-OMVs initiated the immune response was explored and it was found that the constructs triggered TLR1/2, TLR4, and TLR5. Our data indicate that OMVs have potential as a platform for influenza A vaccine development due to their unique adjuvant profile and intrinsic pathogen-mimetic nature. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Investigation of Texture and Residual Stresses in Reactive Magnetron Sputtered TiN coatings on M2 Steel Substrates

    Science.gov (United States)

    Mirchev, R.; Iordanova, I.; Antonov, V.; Kelly, P. J.

    2007-04-01

    The development of crystallographic texture and residual macro-stresses during the growth from 500 nm to 4000 nm of TiN films applied by reactive Closed Field Unbalanced Magnetron Sputtering (CFUBMS) on M2 tool steel at three direct target currents (Id) (namely 4, 6 and 8A) have been analyzed via X-ray diffraction.

  7. Energy supply technologies. Hydro, ocean, wave and tidal

    Energy Technology Data Exchange (ETDEWEB)

    Fenhann, J.; Larsen, Hans [Risoe National Lab. - DTU (Denmark)

    2007-11-15

    This chapter presents an overview of current hydro, ocean, wave and tidal initiatives. Large hydro remains one of the lowest-cost generating technologies, although environmental constraints, resettlement impacts and the limited availability of sites have restricted further growth in many countries. Large hydro supplied 16 % of global electricity in 2004, down from 19 % a decade ago. Large hydro capacity totalled about 720 GW worldwide in 2004 and has grown historically at slightly more than 2 % annually. China installed nearly 8 GW of large hydro in 2004, taking the country to number one in terms of installed capacity (74 GW). With the completion of the Three Gorges Dam, China will add some 18.2 GW of hydro capacity in 2009. The socio-economic benefits of hydro include improved flood control and water supply. The socio-economic benefits of hydro include improved flood control and water supply. The socio-economic cost of hydro includes displacements and submergence. Further hydro can improve peak-capacity management. Ocean currents, some of which runs close to European coasts, carry a lot of kinetic energy. Part of this energy can be captured by sub-marine windmills and converted into electricity. These are more compact than the wind turbines used on land, simply because water is much denser than air. The main European countries with useful current power potential are France and the UK. Ocean tides are driven by the gravitational pull of the moon. With one high tide every 12 hours, a tidal power plant can operate for only four or five hours per cycle, so power from a single plant is intermittent. A suitably-designed tidal plant can, however, operate as a pimped storage system, using electricity during periods of low demand to store energy that can be recovered later. The only large, modern example of a tidal power plant is the 240 MW La Rance plant, built in France in the 1960s, which represents 91 % of the world tidal power capacity. Wave energy can be seen as

  8. Shear Stress, Turbulence Production and Dissipation in Small Tidal Channels Intersecting a Tidal Flat

    Science.gov (United States)

    Pieterse, A.; Puleo, J. A.; McKenna, T. E.

    2014-12-01

    A 16-day field experiment was conducted in March and April 2013 in a tidal wetland in Kent County, Delaware. The study area was a tidal flat fed by a second-order channel that flows into the Brockonbridge Gut, a small tributary of Delaware Bay. The goal of the field study was to investigate spatio-temporal variability in the hydrodynamics of the tidal flat and the small channels that intersect it, over the period of one spring-neap tidal cycle. The experiment combined remotely-sensed imagery with high-frequency in-situ measurements. A tower with imagers (RGB, NIR, TIR) was deployed to quantify the spatial variations of inundation of the channels, flat and marsh. In-situ sensors that measure flow velocity, sediment concentration and water depth were deployed at six locations on the tidal flat and in the channels. At three locations, a Nortek Vectrino II - profiling velocimeter was deployed that measures a 30 mm velocity profile at 1 mm vertical increments at 100 Hz. These velocity profiles are used to compute turbulent kinetic energy, turbulence dissipation and stress profiles close to the bed. Results show that peak velocities in the channels occur at the beginning and end of ebbing tide, when the water level is below the tidal flat level. At these instances, peaks in turbulence and bed stress also occur. The flow velocity and turbulence peaks are smaller when the water level does not fall below the tidal flat level. On the tidal flat, the flow velocities and turbulence are generally small compared to the intersecting tidal channel. Maximum flow velocities in the channels are around 0.4 m/s, while on the flat maximum velocities are under 0.1 m/s. A comparison is made between turbulence production and dissipation in both the channel and on the tidal flat to determine if advection and diffusion are important in this environment. In addition, the hydrodynamics at several locations in the channel are compared to investigate changes throughout the study area.

  9. Hydrodynamic transport of drifting macroalgae through a tidal cut

    Science.gov (United States)

    Biber, Patrick D.

    2007-09-01

    Drifting macroalgae are unattached seaweeds that are commonly found in many South Florida and Gulf of Mexico shallow-water seagrass habitats. They are primarily comprised of species of red algae (Rhodophyta) and some brown algae (Phaeophyta). Because of the unattached nature of these species, drift algae have the ability to be moved around the landscape primarily by tidal, as well as wind-driven and alongshore currents. Numerous invertebrates and some fish species are typically found associated with drift algal clumps and aggregations. Transport of drift algae is an important dispersal mechanism for both the plants and their associated fauna. Dispersal distances have been studied in numerous locations over a range of spatial scales. However, little is known about quantities of algal material that are involved. In this study I report on composition and biomass of drifting algae that are transported through a tidal inlet in Biscayne Bay, Florida. Sargassum (a brown alga) and about 12 genera of red algae were found in three seasonal collections (Aug., Dec., May). Total biomass collected varied among seasons, with larger average amounts of drift algae collected in May than the other two months sampled. From this data, I calculate the approximate quantities of drift algae that are potentially moving in, or out of, Biscayne Bay, about a half to one ton of biomass per day.

  10. Formation, tidal evolution and habitability of the Kepler-186 system

    CERN Document Server

    Bolmont, Emeline; von Paris, Philip; Selsis, Franck; Hersant, Franck; Quintana, Elisa V; Barclay, Thomas

    2014-01-01

    The Kepler-186 system consists of five planets orbiting an early-M dwarf. The planets have physical radii of 1.0-1.50 R$_\\oplus$ and orbital periods of 4 to 130 days. The $1.1~$R$_\\oplus$ Kepler-186f with a period of 130 days is of particular interest. Its insolation of roughly $0.32~S_\\odot$places it within the liquid water habitable zone. We present a multi-faceted study of the Kepler-186 system. First, we show that the distribution of planet masses can be roughly reproduced if the planets accreted from a high-surface density disk presumably sculpted by an earlier phase of migration. However, our simulations predict the existence of 1-2 undetected planets between planets e and f. Next, we present a dynamical analysis of the system including the effect of tides. The timescale for tidal evolution is short enough that the four inner planets must have small obliquities and near-synchronous rotation rates. Tidal evolution of Kepler-186f is slow enough that its current spin state depends on a combination of its d...

  11. Modelling the transverse distribution of velocity and suspended sediment in tidal estuaries

    Science.gov (United States)

    Huijts, K. M. H.

    2011-01-01

    momentum by the Coriolis-induced transverse tidal flow and by the density-induced transverse tidal flow, respectively. The models were validated against observations in the James River and Chesapeake Bay, and against a three-dimensional numerical model for various estuarine conditions. An important finding is that the residual across-channel density gradient is crucial for the lateral distribution and trapping of sediment in many estuarine cross-sections. The gradient tends to trap sediments in fresher areas of the cross-section. Tidal variations in the across-channel density gradient were found to cause a double circulation pattern in the transverse tidal flow during slack tides. The gradient also affects along-channel residual velocity via density-induced tidal rectification. This rectification component features landward currents in the channel and seaward currents over the slopes, and is particularly effective in deeper water. Coriolis-induced tidal rectification was found to induce residual flows that are up-estuary to the right and down-estuary to the left of an estuarine channel (looking up-estuary in the northern hemisphere). The process fundamentally changes the transverse structure of along-channel residual flow for stronger tides or steeper channels, as the flow becomes internally asymmetric. For weaker tides, along-channel residual flows are typically dominated by a gravitational circulation, i.e., landward flow in the channel and seaward flow over the shoals, or river flow. Stokes return flow, which resembles river flow, is particularly important for strong tides in shallow water

  12. Electrical Resistivity Imaging of Tidal Fluctuations in the Water Table at Inwood Hill Park, Manhattan

    Science.gov (United States)

    Kenyon, P. M.; Kassem, D.; Olin, A.; Nunez, J.; Smalling, A.

    2005-05-01

    Inwood Hill Park is located on the northern tip of Manhattan and has been extensively modified over the years by human activities. In its current form, it has a backbone of exposed or lightly covered bedrock along the Hudson River, adjacent to a flat area with two tidal inlets along the northern shore of Manhattan. The tidal motions in the inlets are expected to drive corresponding fluctuations in the water table along the borders of the inlets. In the Fall of 2002, a group of students from the Department of Earth and Atmospheric Sciences at the City College of New York studied these fluctuations. Electrical resistivity cross sections were obtained with a Syscal Kid Switch 24 resistivity meter during the course of a tidal cycle at three locations surrounding the westernmost inlet in the park. No change was seen over a tidal cycle at Site 1, possibly due to the effect of concrete erosion barriers which were located between the land and the water surrounding this site. Measurements at Site 2 revealed a small, regular change in the water table elevation of approximately 5 cm over the course of a tidal cycle. This site is inferred to rest on alluvial sediments deposited by a small creek. The cross sections taken at different times during a tidal cycle at Site 3 were the most interesting. They show a very heterogeneous subsurface, with water spurting between blocks of high resistivity materials during the rising portion of the cycle. A small sinkhole was observed on the surface of the ground directly above an obvious plume of water in the cross section. Park personnel confirmed that this sinkhole, like others scattered around this site, is natural and not due to recent construction activity. They also indicated that debris from the construction of the New York City subways may have been dumped in the area in the past. Our conclusion is that the tidal fluctuations at Site 3 are being channeled by solid blocks in the construction debris, and that the sinkholes currently

  13. Morphologic and stratigraphic evolution of muddy ebb-tidal deltas along a subsiding coast: Barataria Bay, Mississippi River delta

    Science.gov (United States)

    FitzGerald, D.M.; Kulp, M.; Penland, S.; Flocks, J.; Kindinger, J.

    2004-01-01

    The Barataria barrier coast formed between two major distributaries of the Mississippi River delta: the Plaquemines deltaic headland to the east and the Lafourche deltaic headland to the west. Rapid relative sea-level rise (1??03 cm year-1) and other erosional processes within Barataria Bay have led to substantial increases in the area of open water (> 775 km2 since 1956) and the attendant bay tidal prism. Historically, the increase in tidal discharge at inlets has produced larger channel cross-sections and prograding ebb-tidal deltas. For example, the ebb delta at Barataria Pass has built seaward > 2??2 km since the 1880s. Shoreline erosion and an increasing bay tidal prism also facilitated the formation of new inlets. Four major lithofacies characterize the Barataria coast ebb-tidal deltas and associated sedimentary environments. These include a proximal delta facies composed of massive to laminated, fine grey-brown to pale yellow sand and a distal delta facies consisting of thinly laminated, grey to pale yellow sand and silty sand with mud layers. The higher energy proximal delta deposits contain a greater percentage of sand (75-100%) compared with the distal delta sediments (60-80%). Associated sedimentary units include a nearshore facies consisting of horizontally laminated, fine to very fine grey sand with mud layers and an offshore facies that is composed of grey to dark grey, laminated sandy silt to silty clay. All facies coarsen upwards except the offshore facies, which fines upwards. An evolutionary model is presented for the stratigraphic development of the ebb-tidal deltas in a regime of increasing tidal energy resulting from coastal land loss and tidal prism growth. Ebb-tidal delta facies prograde over nearshore sediments, which interfinger with offshore facies. The seaward decrease in tidal current velocity of the ebb discharge produces a gradational contact between proximal and distal tidal delta facies. As the tidal discharge increases and the inlet

  14. Formation of Massive Black Holes in Galactic Nuclei: Runaway Tidal Encounters

    Science.gov (United States)

    Stone, Nicholas C.; Küpper, Andreas H. W.; Ostriker, Jeremiah P.

    2017-01-01

    Nuclear star clusters (NSCs) and supermassive black holes (SMBHs) both inhabit galactic nuclei, coexisting in a range of bulge masses, but excluding each other in the largest or smallest galaxies. We propose that the transformation of NSCs into SMBHs occurs via runaway tidal captures, once NSCs exceed a certain critical central density and velocity dispersion. The bottleneck in this process is growing the first e-fold in black hole mass. The growth of a stellar mass black hole past this bottleneck occurs as tidally captured stars are consumed in repeated episodes of mass transfer at pericenter. Tidal captures may deactivate as a growth channel once the black hole mass ≳ 102 - 3M⊙, but tidal disruption events will continue and can grow the seed SMBH to larger sizes. The runaway slows (becomes sub-exponential) once the seed SMBH consumes the core of its host NSC. While most of the cosmic mass density in SMBHs is ultimately produced by episodic gaseous accretion in very massive galaxies, the smallest SMBHs have probably grown from strong tidal encounters with NSC stars. SMBH seeds that grow for a time t entirely through this channel will follow simple power law relations with the velocity dispersion, σ, of their host galaxy. In the simplest regime it is M_bullet ˜ σ ^{3/2}√{M_star t / G} ˜ 106M_⊙ (σ / 50 km s^{-1})^{3/2}(t/10^{10} yr)^{1/2}, but the exponents and prefactor can differ slightly depending on the details of loss cone refilling. Current tidal disruption event rates predicted from this mechanism are consistent with observations.

  15. Formation of massive black holes in galactic nuclei: runaway tidal encounters

    Science.gov (United States)

    Stone, Nicholas C.; Küpper, Andreas H. W.; Ostriker, Jeremiah P.

    2017-06-01

    Nuclear star clusters (NSCs) and supermassive black holes (SMBHs) both inhabit galactic nuclei, coexisting in a range of bulge masses, but excluding each other in the largest or smallest galaxies. We propose that the transformation of NSCs into SMBHs occurs via runaway tidal captures, once NSCs exceed a certain critical central density and velocity dispersion. The bottleneck in this process is growing the first e-fold in black hole mass. The growth of a stellar mass black hole past this bottleneck occurs as tidally captured stars are consumed in repeated episodes of mass transfer at pericentre. Tidal captures may deactivate as a growth channel once the black hole mass ≳102-3 M⊙, but tidal disruption events will continue and can grow the seed SMBH to larger sizes. The runaway slows (becomes subexponential) once the seed SMBH consumes the core of its host NSC. While most of the cosmic mass density in SMBHs is ultimately produced by episodic gaseous accretion in very massive galaxies, the smallest SMBHs have probably grown from strong tidal encounters with NSC stars. SMBH seeds that grow for a time t entirely through this channel will follow simple power-law relations with the velocity dispersion, σ, of their host galaxy. In the simplest regime, it is M_\\bullet ˜ σ ^{3/2}√{M_\\star t / G} ˜ 106 M_{⊙} (σ / 50 {km s}^{-1})^{3/2}(t/10^{10} yr)^{1/2}, but the exponents and pre-factor can differ slightly depending on the details of loss cone refilling. Current tidal disruption event rates predicted from this mechanism are consistent with observations.

  16. Effect of tidal stream power generation on the region-wide circulation in a shallow sea

    Directory of Open Access Journals (Sweden)

    G. I. Shapiro

    2010-10-01

    Full Text Available Ocean tides are deemed to become a stable source of renewable energy for the future. Tidal energy has two components, the first is the potential energy due to sea level variations and the second comes from the kinetic energy of the tidal streams. This paper is concerned with the backward effect on the ocean currents by a tidal stream farm located in the open shallow sea. Recent studies in channels with 1-D models have indicated that the power potential is not given purely by the flux of kinetic energy, as has been commonly assumed. In this study, a 3-D ocean circulation model is used to estimate (i maximum extractable energy at different levels of rated generation capacity of the farm, (ii changes in the strength of currents due to energy extraction, and (iii alterations in the pattern of residual currents and pathways of passive tracers. As water flow is influenced both by tidal and non-tidal currents, the model takes into account wind-driven and density-driven currents generated by meteorological forcing. Numerical modelling has been carried out for a hypothetical circular farm located in the Celtic Sea north of Cornwall, an area known for its high level of tidal energy. Modelling results clearly indicate that extracted power does not grow linearly with the increase in the rated capacity of the farm. For the case studies covered in this paper, a 100-fold increase in rated generation capacity of the farm results only in 7-fold increase in extracted power, this loss of efficiency is much greater than was estimated earlier with 1-D models. In case of high rated capacity of the farm, kinetic energy of currents is altered significantly as far as 10–20 km away from the farm. At high levels of extracted energy the currents tend to avoid flowing through the farm, an effect which is not captured with 1-D models. Residual currents are altered as far as a hundred kilometres. The magnitude of changes in the dispersion of tracers is highly sensitive to

  17. The Armys M-1 Abrams, M-2/M-3 Bradley, and M-1126 Stryker: Background and Issues for Congress

    Science.gov (United States)

    2016-04-05

    entered service with the Army in 1980; the M-2/M-3 Bradley Fighting Vehicle in 1981; and the Stryker Combat Vehicle in 2001. Under current Army... Under current Army modernization plans, the Army envisions all three vehicles in service with Active and National Guard forces beyond FY2028...Information from this section, unless otherwise noted, is taken from Jane’s Armour and Artillery, 2011-2012, pp.177- 185, and the author’s personal

  18. Active galactic nuclei. IV - Supplying black hole clusters by tidal disruption and by tidal capture of stars

    Science.gov (United States)

    Stoeger, W. R.; Pacholczyk, A. G.; Stepinski, T. F.

    1992-01-01

    The extent to which individual holes in a cluster of black holes with a mass spectrum can liberate and accrete the resulting material by tidally disrupting stars they encounter, or by capturing stars as binary companions is studied. It is found that the smaller black holes in 'the halo' of such clusters can adequately supply themselves to the level M-dot sub h or greater than 0.0001(M-dot sub h) sub crit, and up to 0.05(M-dot sub h)sub crit for the smallest holes, by tidal disruption, as long as the cluster is embedded in a distribution of stars of relatively high density (not less than 0.1M sub cl/cu pc), and as long as the entire cluster of stars is not too compact (not less than 0.5 pc). Consideration is given to modifications this 'internal' mode of supply introduces in the spectrum emitted by such black hole clusters, and to the current status of their viability as models for AGN and QSOs in light of dynamical studies by Quinlan and Shapiro (1987, 1989).

  19. A Vertical Two-Dimensional Model to Simulate Tidal Hydrodynamics in A Branched Estuary

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-Cheng; WU Chung-Hsing

    2005-01-01

    A vertical (laterally averaged) two-dimensional hydrodynamic model is developed for tides, tidal current, and salinity in a branched estuarine system. The governing equations are solved with the hydrostatic pressure distribution assumption and the Boussinesq approximation. An explicit scheme is employed to solve the continuity equations. The momentum and mass balance equations are solved implicitly in the Cartesian coordinate system. The tributaries are governed by the same dynamic equations. A control volume at the junctions is designed to conserve mass and volume transport in the finite difference schemes, based on the physical principle of continuum medium of fluid. Predictions by the developed model are compared with the analytic solutions of steady wind-driven circulatory flow and tidal flow. The model results for the velocities and water surface elevations coincide with analytic results. The model is then applied to the Tanshui River estuarine system. Detailed model calibration and verification have been conducted with measured water surface elevations,tidal current, and salinity distributions. The overall performance of the model is in qualitative agreement with the available field data. The calibrated and verified numerical model has been used to quantify the tidal prism and flushing rate in the Tanshui River-Tahan Stream, Hsintien Stream, and Keelung River.

  20. Discovery of a stellar tidal stream around the Whale galaxy, NGC 4631

    CERN Document Server

    Martinez-Delgado, David; Chonis, Taylor S; Beaton, Rachael L; Teuwen, Karel; GaBany, R Jay; Grebel, Eva K; Morales, Gustavo

    2014-01-01

    We report the discovery of a giant stellar tidal stream in the halo of NGC 4631, a nearby edge-on spiral galaxy interacting with the spiral NGC 4656, in deep images taken with a 40-cm aperture robotic telescope. The stream has two components: a bridge-like feature extended between NGC 4631 and NGC 4656 (stream_SE) and an overdensity with extended features on the opposite side of the NGC 4631 disk (stream_NW). Together, these features extend more than 85 kpc and display a clear (g-r) colour gradient. The orientation of stream_SE relative to the orientations of NGC 4631 and NGC 4656 is not consistent with an origin from interaction between these two spirals, and is more likely debris from a satellite encounter. The stellar tidal features can be qualitatively reproduced in an N-body model of the tidal disruption of a single, massive dwarf satellite on a moderately eccentric orbit (e=0.6) around NGC 4631 over $\\sim$ 3.5 Gyr, with a dynamical mass ratio (m1:m2) of ~40. Both modelling and inferences from the morpho...