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RANSE-based simulation and analysis of scale effects on open-water performance of the PPTC-II benchmark propeller

Journal of Ocean Engineering and Science 2018年第3期3卷 186-204页

作者： Xiao-Qian Dong Wei Li Chen-Jun Yang Francis Noblesse Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration(CISSE) State Key Laboratory of Ocean Engineering(SKLOE)Shanghai Jiao Tong UniversityShanghai 200240China

This paper presents our numerical study of the scale effects on a tip-rake propeller,the PPTC-II,based on the RANS simulations using software FLUENT *** low Re option in SST k-ωmodel is adopted at model scale,together with fine prism grids to resolve the viscous *** full scale,standard wall function is *** scale-effect corrections yielded by our RANS simulations are compared with those obtained from the ITTC *** explain the CFD results,an analysis of sectional forces is *** investigate how the tip rake influences propeller scale effects,the geometry of PPTC-II is modified by removing the tip rake only,and the RANS-predicted scale effects for the modified propeller,PPTC-II-m,are compared with those for the *** study indicates that the scale effect on propeller thrust can be as important as that on the torque;somehow the RANS-and ITTC-based predictions for full-scale efficiency agree quite well;the tip-rake reduces tip loading and tip vortex strength,and brings about large differences in the scale effects as compared with the propeller without tip-rake.

关键词： Propeller Tip rake open water Scale effect RANSE

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Identifying important habitats for waterbird conservation at a Greek Regional Nature Park

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Avian Research 2020年第4期11卷 452-464页

作者： Vasilios Liordos Vasileios J.Kontsiotis Hellenic Forest Service 12 Minoas str19100 MegaraAttikiGreece Department of Forest and Natural Environment Sciences International Hellenic UniversityP.O.Box 17266100 DramaGreece.

Background:Small coastal wetlands are vital sites for wintering *** important habitats is critical for managing waterbirds *** Vourkari inlet is a small coastal wetland located near the capital Athens,within the most urbanized and industrialized area of *** aimed at identifying the most important habitats for waterbirds at the Vourkari inlet during ***:Data about habitat use and availability were collected for 14 waterbird species and for seven habitat *** selection(Manly’s selection ratio),overlap indices(Pianka’s niche overlap index)and null models were ***:All the studied waterbird species selected available habitats *** waters(0–2 m),were used by 13 waterbirds and selected by five *** and channels were used and selected by 10 *** was used by nine species and selected by six *** with rocky substrate was used by nine species and selected by eight ***(2–4 m)and deep(4–6 m)open water habitats were used by seven species and selected by four *** vegetation was used by six species and selected by two *** habitats were selected by nationally important populations:mudflat habitats(i.e.,mud,mud with rocky substrate and pools and channels)by Common Redshanks(Tringa totanus),halophytic vegetation by Little Egrets(Egretta garzetta),shallow waters by Common Shelducks(Tadorna tadorna)and medium and deep waters by Sandwich Terns(Thalasseus sandvicencis),whilst shallow waters and mudflat habitats were preferred by a possibly internationally important population of Mediterranean Gulls(Ichthyaetus melanocephalus).Although overlap in habitat use between species was generally low,null models indicated habitat sharing and a lack of ***:waterbirds coexisted in the absence of competition for habitats at Vourkari,where they mostly used and preferred shallow water and *** coastal wetlands are numerous,

关键词： Habitat selection Habitat use Mudflats Niche overlap Null models open water Small coastal wetlands

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An improved optical flow method to estimate Arctic sea ice velocity(winter 2014-2016)

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Acta Oceanologica Sinica 2021年第12期40卷 148-160页

作者： Haili Li Changqing Ke Qinghui Zhu Xiaoyi Shen Mengmeng Li Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology/Key Laboratory for Land Satellite Remote Sensing Applications of Ministry of Natural Resources School of Geography and Ocean ScienceNanjing UniversityNanjing 210023China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing 210023China Collaborative Innovation Center of South China Sea Studies Nanjing 210023China

Sea ice velocity impacts the distribution of sea ice,and the flux of exported sea ice through the Fram Strait increases with increasing ice ***,improving the accuracy of estimates of the sea ice velocity is *** introduce a pyramid algorithm into the Horn-Schunck optical flow(HS-OF)method(to develop the PHS-OF method).Before calculating the sea ice velocity,we generate multilayer pyramid images from an original brightness temperature ***,the sea ice velocity of the pyramid layer is calculated,and the ice velocity in the original image is calculated by layer *** Arctic sea ice velocities from 2014 to 2016 are obtained and used to discuss the accuracy of the HS-OF method and PHS-OF(specifically the 2-layer PHS-OF(2 LPHS-OF)and 4-layer PHS-OF(4 LPHS-OF))*** results prove that the PHS-OF method indeed improves the accuracy of sea ice velocity estimates,and the 2 LPHS-OF scheme is more appropriate for estimating ice *** error is smaller for the 2 LPHS-OF velocity estimates than values from the Ocean and Sea Ice Satellite Application Facility and the Copernicus Marine Environment Monitoring Service,and estimates of changes in velocity by the 2 LPHS-OF method are consistent with those from the National Snow and Ice Data *** ice undergoes two main motion patterns,i.e.,transpolar drift and the Beaufort *** addition,cyclonic and anticyclonic ice drift occurred during winter *** in sea ice velocity are related to the open water area,sea ice retreat time and length of the open water season.

关键词： winter sea ice velocity pyramid Horn-Schunck optical flow(PHS-OF)method transpolar drift Beaufort Gyre open water Arctic

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