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A Twin Unidirectional Impulse Turbine for Wave energy Conversion

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Journal of Thermal Science 2011年第5期20卷 394-397页

作者： Manabu Takao Akiyasu Takami Shinya Okuhara Toshiaki Setoguchi Matsue College of Technology 14-4 NishiikumaMatsueShimane 690-8518Japan Saga University 1 HonjoSagaSaga 840-8502Japan

A twin unidirectional impulse turbine has been proposed in order to enhance the performance of wave energy plant. This turbine system uses two unidirectional impulse turbines and their flow direction is different from each other. However, the turbine characteristics have not been clarified to date. The performances of a unidirectional impulse turbine under steady flow conditions were investigated experimentaUy by using a wind tunnel with large piston/cylinder in this study. Then, efficiency of the twin impulse turbine have been estimated by a quasi-steady analysis using experimental results.

关键词： Fluid machinery impulse turbine wave energy conversion ocean energy.

Floating Type ocean Wave Power Station Equipped with Hydroelectric Unit

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Journal of Thermal Science 2013年第5期22卷 467-471页

作者： Shun Okamoto Toshiaki Kanemoto Toshihiko Umekage Kyushu institute of Technology Sensui 1-1 Tobata Kitakyushu 804-8550 Japan

The authors have invented the unique ocean wave power station,which is composed of the floating type platform with a pair of the floats lining up at the interval of one wave pitch and the counter-rotating type wave power unit,its runners are submerged in the seawater at the middle position of the *** profiles make the flow velocity at the runner is twice faster than that of the traditional fixed/caisson type OWC,on the ideal flow ***,the runners counter-rotate the inner and the outer armatures of the peculiar generator,respectively,and the relative rotational speed is also twice faster than the speed of the single runner/*** characteristics make the runner diameter large,namely the output higher,as requested,because the torque of the power unit never act on the floating type *** the preliminary reseach,this paper verifies to get the power using a Wells type single runner installed in the model *** runner takes the output which is affected by the oscillating amplitude of the platform,the rotational speed and the inertia force of the runner,etc.

关键词： Renewable energy ocean wave Float Platform Counter-rotation Power unit

Artificial nesting habitats as a conservation strategy for turtle populations experiencing global change

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Integrative Zoology 2013年第2期8卷 209-221页

作者： John P.WNEK Walter F.BIEN Harold W.AVERY Department of Biology Drexel UniversityPhiladelphiaPennsylvaniaUSA

Diamondback terrapins(Malaclemys terrapin)inhabit estuaries in eastern USA and may tolerate salinity of seawater for short *** North American estuaries are adversely affected by anthropogenic impacts,such as pollution,dredging and invasion by non-native *** nesting areas have been altered or destroyed,causing terrapins to nest on roadsides and artificial islands made of dredged substrate from bottom *** by non-native plants may suppress development and reduce survival of *** Barnegat Bay,New Jersey,USA,there is a mosaic of natural and degraded terrapin nesting *** investigated the effects of dredge soil and shade on the hatching success of diamondback terrapins to determine whether nesting habitat could be increased by using dredged bottom *** year 1,unshaded nests in natural loamy-sand had the highest hatching success(55.2%),while nests in dredge soil produced no *** year 2,nests in unshaded loamy-sand had a hatching success of 85.3%,whereas those in dredge soil,aged 1 year,had a hatching success of 59.4%.Dredge soil improved as an incubation substrate after aging 1 year by the washout of *** temperatures were generally cool and produced mostly male *** dredge soil may provide suitable nesting substrates for diamondback terrapins if used after one year,and may be particularly beneficial if used for constructing islands that provide new nesting sites with reduced access of mammalian predators.

关键词： dredge estuarine turtles hatching success Malaclemys terrapin nesting ecology nest temperature nest substrate shade

Weather Induced Quasi-Periodic Motions in Estuaries and Bays:Meteoro-logical Tide

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China ocean Engineering 2020年第3期34卷 299-313页

作者： LI Chun-yan HUANG Wei WU Ren-hao Alex SHEREMET College of the Coast and Environment Louisiana State UniversityBaton Rouge 70803USA Virginia institute of Marine Science College of William and MaryGloucester Pt.23062USA School of Atmospheric Sciences Sun Yat-Sen UniversityZhuhai 519082China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China Engineering School of Sustainable Infrastructure and Environment University of FloridaGainesville FL 32611USA

Influenced by weather, the estuaries and bays often exhibit recurring oscillations in flow and water level similar to astronomical tides. The weather impact however is less regular than tides and more difficult to predict. The spectrum of weather induced motions in estuaries and bays is mostly at the low-frequency end with time scales longer than those of diurnal tides. The repeated weather impact produces meteorological tide: the recurring flood and ebb and flushing of the estuaries and bays but at lower frequencies than those of tides. The variation in weather conditions is quasi-periodic and of large scale nature(~1000-3000 km) because of the alternating low-and high-atmospheric pressure systems of extra-tropical cyclones and anti-cyclones and associated fronts. By examining 40 years of data between Jan. 1, 1977 and Dec. 31, 2016, we identified 1648 frontal events(averaging ~41.2±4.7 per year)influencing the northern Gulf of Mexico for time periods in the spring, fall and winter. The late spring and summer months(May, Jun, July, and August) were not included in the calculation because of much weaker activities involving synoptic weather systems with fronts during these months. It is found that the number of frontal events reached the maximum in Jan. and Dec. while the minimum occurred in April and Sept. It is found that there is an increasing trend of number of fronts over the 40-year period. Our data show that the low pass filtered water level,velocity, and vorticity(velocity shear) all vary in response to the weather and appear as the meteorological tide. The particle excursions of meteorological tides are much larger than those from the astronomical tides. In addition, the irregular nature of the meteorological tide makes the inward flux and outward flux asymmetric in general and thus it has a significant implication to dispersion and transport of waterborne materials. A scaling analysis shows that the meteorological tide generally reaches quasi-steady state;a

关键词： meteorological tide atmospheric fronts particle excursion quasi-steady state northern Gulf of Mexico estuarine exchange flows

Effect of Calcium Leaching on the Properties of Cement-based Composites

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Journal of Wuhan University of Technology(Materials Science) 2011年第5期26卷 990-997页

作者：林威廷鄭安 institute of Nuclear energy Research Atomic Energy Council Dept.of Civil Engineering National Ilan University

Leaching is one of the major factors that alter the mechanical properties of cement-based *** study is aimed to investigate the effect of leaching on the properties of cement-based *** with two water/cementitious ratios and two mineral admixtures were *** electrical potential was applied to accelerate the leaching *** strength test,scanning electronic microscopy,thermogravimetric analysis and X-ray diffraction analysis were *** results demonstrated that the calcium leaching reduced compressive strengths of concrete specimens,and such effect was prominent on the specimens without mineral *** leaching resistance increased with a decrease in water/cementitious ratio and an increase in amount of mineral *** mineral admixtures would reduce the amount of calcium hydroxide and refine the pore structure through pozzolanic reactions.A fair relationship was found between the calcium leaching and the compressive strength.

关键词： leaching slag silica fume X-ray diffraction analysis thermo gravimetric analysis

Extreme Cold Events from East Asia to North America in Winter 2020/21:Comparisons,Causes,and Future Implications

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Advances in Atmospheric Sciences 2022年第4期39卷 553-565页

作者： Xiangdong ZHANG Yunfei FU Zhe HAN James E.OVERLAND Annette RINKE Han TANG Timo VIHMA Muyin WANG Univeristy of Alaska Fairbanks FairbanksAK 99775USA University of Science and Technology of China Hefei 230026China institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China NOAA/Pacific Marine Environmental Laboratory SeattleWA 98115USA Alfred Wegener institute Helmholtz Center for Polar and Marine Research14401 PotsdamGermany Finnish Meteorological institute FI-00101 HelsinkiFinland University of Washington SeattleWA 98105USA

Three striking and impactful extreme cold weather events successively occurred across East Asia and North America during the mid-winter of 2020/*** events open a new window to detect possible underlying physical *** analysis here indicates that the occurrences of the three events resulted from integrated effects of a concurrence of anomalous thermal conditions in three oceans and interactive Arctic-lower latitude atmospheric circulation processes,which were linked and influenced by one major sudden stratospheric warming(SSW).The North Atlantic warm blob initiated an increased poleward transient eddy heat flux,reducing the Barents-Kara seas sea ice over a warmed ocean and disrupting the stratospheric polar vortex(SPV)to induce the major *** Rossby wave trains excited by the North Atlantic warm blob and the tropical Pacific La Nina interacted with the Arctic tropospheric circulation anomalies or the tropospheric polar vortex to provide dynamic settings,steering cold polar air *** long memory of the retreated sea ice with the underlying warm ocean and the amplified tropospheric blocking highs from the midlatitudes to the Arctic intermittently fueled the increased transient eddy heat flux to sustain the SSW over a long time *** displaced or split SPV centers associated with the SSW played crucial roles in substantially intensifying the tropospheric circulation anomalies and moving the jet stream to the far south to cause cold air outbreaks to a rarely observed extreme *** results have significant implications for increasing prediction skill and improving policy decision making to enhance resilience in“One Health,One Future”.

关键词： extreme weather events sea surface temperature Arctic sea ice Arctic amplification sudden stratospheric warming stratospheric polar vortex

Application of the Latching Control System on the Power Performance of a Wave energy Converter Characterized by Gearbox,Flywheel,and Electrical GeneratorGustavor

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Journal of Marine Science and Application 2021年第4期20卷 767-786页

作者： Gustavo O.Guarniz Avalos Milad Shadman Segen F.Estefen ocean Engineering Department COPPEFederal University of Rio de JaneiroRio de Janeiro 21941-901Brazil

The latching control represents an attractive alternative to increase the power absorption of wave energy converters(WECs)by tuning the phase of oscillator velocity to the wave excitation ***,increasing the amplitude of motion of the floating body is not the only challenge to obtain a good performance of the *** also depends on the efficiency of the power take-off system(PTO).This study aims to address the actual power performance and operation of a heaving point absorber with a direct mechanical drive PTO system controlled by *** PTO characteristics,such as the gear ratio,the flywheel inertia,and the electric generator,are analyzed in the WEC *** cylindrical point absorbers are also considered in the present study.A wave-to-wire model is developed to simulate the coupled hydro-electro-mechanical system in regular *** wave energy converter(WEC)performance is analyzed using the potential linear theory but considering the viscous damping effect according to the Morison equation to avoid the overestimated responses of the linear theory near resonance when the latching control system is *** latching control system increases the mean ***,the increase is not significant if the parameters that characterize the WEC provide a considerable mean *** performance of the proposed mechanical power take-off depends on the gear ratio and ***,the gear ratio shows a more significant influence than the flywheel *** operating range of the generator and the diameter/draft ratio of the buoy also influence the PTO performance.

关键词： Wave energy converter Point absorber Mechanical power take-off Flywheel Gear ratio Latching control

An overview of research efforts to understand the effects of underwater sound on cetaceans

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Water Biology and Security 2023年第2期2卷 1-12页

作者： Shane Guan Tiffini Brookens Bureau of ocean energy Management Environmental Studies ProgramUSA Marine Mammal Commission USA The Catholic University of America USA

Cetaceans are aquatic mammals living in an environment that is more suited for hearing than *** such,their sensory systems largely utilize acoustic cues for navigation,communication,foraging,and predator ***,the elevation of underwater sound levels from increased human activities has adversely affected cetaceans’use of sound to perform vital life *** address those impacts,scientific studies have been conducted to understand the behavioral,psychoacoustical,physiological,and physical responses by cetaceans that have been exposed to anthropogenic *** studies range from captive experiments involving auditory thresholds and noise-induced threshold shifts,to field observations of behavioral disturbance from sound exposure,to post-mortem examinations of physical manifestations in stranded *** the years,results from these studies have assisted regulatory agencies in developing a series of criteria and thresholds for cetacean conservation and management around the *** paper provides a high-level overview of worldwide research efforts that have been dedicated to understanding the effects of underwater sound on *** review is not intended to be exhaustive but rather to capture major efforts and significant findings in this *** addition,the review excludes synthesis studies and modeling exercises that do not involve direct research on target species.

关键词： Cetacean Anthropogenic sound Underwater sound exposure Behavioral disturbance Environmental impact assessment Behavioral response Noise-induced threshold shift