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FLOW FIELD IN SCOURED ZONE OF CHANNEL CONTRACTIONS

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International Journal of Sediment Research 2004年第4期19卷 292-311页

作者： Rajkumar V. RAIKAR,Subhasish DEY Kharagpur 721302 West Bengal India. Doctoral Research Fellow Department of Civil Engineering indian institute of technology Kharagpur 721302 West Bengal India. associate Professor Department of Civil Engineering indian institute of technology

Experiments were conducted in a laboratory flume to measure the two-dimensional turbulent flow field in the scoured zone of channel contractions under a clear-water scour condition. The Acoustic Doppler Velocimeter (ADV) was used to detect the flow field at different vertical lines along the centerline of uncontracted (main channel) and contracted zones of the channel. The distributions of time-averaged velocity components, turbulent intensity, turbulent kinetic energy, and Reynolds stresses are presented in nondimensional graphical form. The bed shear stresses are computed from the measured Reynolds stresses being in threshold condition within the zone of contraction where bed was scoured. The data presented in this paper would be useful to the investigators for the development of kinematic flow model and morphological model of scour at a channel or river contraction.

关键词： Channel contraction Open channel flow Turbulent flow Erosion Scour Sediment transport Fluvial hydraulics

REVIEW ON LOCAL SCOUR DUE TO JETS

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International Journal of Sediment Research 2004年第3期19卷 210-238页

作者： Arindam SARKAR,Subhasish DEY Doctoral Research Fellow Department of Civil Engineering indian institute of technology Kharagpur 721302 West Bengal India. associate Professor Department of Civil Engineering indian institute of technology Kharagpur 721302 West Bengal India.

The safety of an apron of the energy dissipator is threatened by the large-scale scour in the downstream of the apron due to the erosive action of a horizontal jet issuing from a sluice opening. Also, large-scale deposition of the scoured sediments due to an impinging jet in a plunging pool type energy dissipator affects the passage of flow adversely in the downstream channels. Owing to the significant practical importance, the problem of local scour due to jets has been studied by many investigators. In this paper, a comprehensive review of the up-to-date investigations on local scour due to horizontal and impinging jets is presented including all possible aspects, such as scouring process, parameters affecting scour, time variation of scour, velocity distribution on the apron and within the scour hole, development of boundary layer thickness, bed shear stress, scour estimation formulas and protection works.

关键词： Scour Erosion Sediment transport Jets

VORTEX FLOW FIELD IN A SCOUR HOLE AROUND ABUTMENTS

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International Journal of Sediment Research 2003年第4期18卷 310-325页

作者： Abdul Karim BARBHUIYA,Subhasish DEY West Bengal India. Lecturer Department of Applied Mechanics National institute of technology Silchar 788010 Assam India associate Professor Department of Civil Engineering indian institute of technology Kharagpur 721302

The three-dimensional flow field in a scour hole around different abutments under a clear water regime was experimentally measured in a laboratory flume, using the Acoustic Doppler Velocimeter (ADV). Three types of abutments used in the experiments were vertical-wall (rectangular section), 45° wing-wall (45° polygonal section) and semicircular. The three-dimensional time-averaged velocity components were detected at different vertical planes for vertical-wall abutment and azimuthal planes for wing-wall and semicircular abutments. The velocity components were also measured at different horizontal planes. In the upstream, presentations of flow field through vector plots at vertical / azimuthal and horizontal planes show the existence of a primary vortex associated with the downflow inside the scour hole. On the other hand, in the downstream, the flow field shows a reversed flow near the abutments having a subsequent recovery with a passage of flow as a part of the main flow. The data presented in this p

关键词： Abutments Three-dimensional flow Vortex flow Open channel flow Scour Sediment transport Fluvial hydraulics

Friction and wear behavior of Cu-4 wt.％Ni-TiC composites under dry sliding conditions

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Friction 2017年第4期5卷 437-446页

作者： Pushkar JHA Rakesh Kumar GAUTAM Rajnesh TYAGI Department of Mechanical Engineering Indian Institute of Technology(Banaras Hindu University)Varanasi 221005India

The present study synthesized Cu-4 wt％ Ni matrix composites reinforced with different percentages of TiC (0,2,4,6,and 8 wt％) through high-energy ball milling,followed by compaction and *** friction and wear behavior was examined at four different normal loads of 5,10,15,and 20 N.A constant sliding speed of 1.25 m/s was maintained while sliding against a hardened counterface made of EN31 steel (HRC 60) under ambient conditions using a pin-on-disk test *** composite hardness increased until the addition of 4 wt％ of TiC,beyond which it was observed to *** a trend may be attributed to the TiC agglomeration in the composites containing relatively larger amounts of TiC (i.e.,6 and 8 wt％).The wear rate linearly increased with the ***,the composites exhibited a lower rate of wear than the matrix alloy,which may have resulted from the relatively higher hardness of *** observed friction and wear behavior has been explained on the basis of hardness and presence of the transfer layer on the worn surface and its nature,i.e.,loose or well *** of 4 wt％ TiC showed the optimum performance in terms of friction and wear caused by its higher hardness and ability to hold a transfer layer of a relatively larger thickness compared to the other *** wear mechanism for the Cu4Ni matrix alloy was a mix of adhesive and oxidative wear and primarily abrasive for the composites containing hard TiC particles.

关键词： sliding wear composites TiC particles friction

India's Engagement With East Asia and The China Factor

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Contemporary International Relations 2010年第5期20卷 97-109页

作者： Li Li associate Research Professor of the institute of South and Southeast Asian Studies CICIR

Introduction India’s engagement with East Asia has enjoyed a long history. In ancient times, the indian Civilization exerted substantial influence on Southeast and East Asia. Buddhism, originating on the Subcontinent... 详细信息

关键词：东亚印度中国交往远古时代东南亚

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Towards an actionable One Health approach

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贫困所致传染病(英文) 2024年第2期13卷 1-6页

作者： Zhang Xiao-Xi Lederman Zohar Han Le-Fei Schurer Janna M. Xiao Li-Hua Zhang Zhi-Bing Chen Qiu-Lan Pfeiffer Dirk Ward Michael P. Sripa Banchob Gabri?l Sarah Dhama Kuldeep Acharya Krishna Prasad Robertson Lucy J. Deem Sharon L. Aenishaenslin Cécile Dantas-Torres Filipe Otranto Domenico Grace Delia Wang Yang Li Peng Fu Chao Poeta Patrícia Rahman Md. Tanvir Kassegne Kokouvi Zhu Yong-Zhang Yin Kun Liu Jiming Wang Zhao-Jun Guo Xiao-Kui Gong Wen-Feng Schwartl?nder Bernhard Ren Ming-Hui Zhou Xiao-Nong School of Global Health Chinese Center for Tropical Diseases Research Shanghai Jiao Tong University School of Medicine Shanghai People’s Republic of China institute of One Health Shanghai Jiao Tong University Shanghai People’s Republic of China Medical Ethics and Humanities Unit Hong Kong University Hong Kong People’s Republic of China Center for One Health University of Global Health Equity Butaro Rwanda College of Veterinary Medicine South China Agricultural University Guangzhou People’s Republic of China School of Ecology and Environment Hainan University Haikou Hainan People’s Republic of China Branch of animal and vector-borne diseases Division of Infectious Disease Control Chinese Center for Disease Control and Prevention Beijing People’s Republic of China Centre for Applied One Health Research and Policy Advice Department of Infectious Diseases and Public Health Jockey Club College of Veterinary Medicine and Life Sciences City University of Hong Kong Hong Kong SAR People’s Republic of China Department of Pathobiology and Population Sciences Royal Veterinary College London United Kingdom Sydney School of Veterinary Science The University of Sydney Camden Australia Tropical Disease Research Center Department of Tropical Medicine Faculty of Medicine Khon Kaen University Khon Kaen Thailand Laboratory of foodborne parasitic zoonoses Department of translational physiology infectiology and public health Chair Faculty Committee on Internationalisation Faculty of Veterinary Medicine Ghent University Merelbeke Belgium Division of Pathology ICAR-Indian Veterinary Research Institute (IVRI) Bareilly Uttar Pradesh India Department of Livestock Services Animal Quarantine Office-Kathmandu Budhanilkantha Kathmandu Nepal Parasitology Department of Paraclinical Sciences Faculty of Veterinary Medicine Norwegian University of Life Sciences ?s Norway One Government Drive Saint Louis Zoo Institute for Conservation Medicine St. Louis USA Groupe de Recherche en épidémi

Background Despite the increasing focus on strengthening One Health capacity building on global level, challenges remain in devising and implementing real-world interventions particularly in the Asia-Pacific region. Recognizing these gaps, the One Health Action Commission (OHAC) was established as an academic community for One Health action with an emphasis on research agenda setting to identify actions for highest *** text This viewpoint describes the agenda of, and motivation for, the recently formed OHAC. Recognizing the urgent need for evidence to support the formulation of necessary action plans, OHAC advocates the adoption of both bottom-up and top-down approaches to identify the current gaps in combating zoonoses, antimicrobial resistance, addressing food safety, and to enhance capacity building for context-sensitive One Health *** By promoting broader engagement and connection of multidisciplinary stakeholders, OHAC envisions a collaborative global platform for the generation of innovative One Health knowledge, distilled practical experience and actionable policy advice, guided by strong ethical principles of One Health.

关键词： One Health Global Health One Health Action Commission Research agenda

Broken Charges associated with Classical Spacetime Symmetries under Canonical Transformation in Real Scalar Field Theory

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Journal of High Energy Physics, Gravitation and Cosmology 2019年第1期5卷 167-180页

作者： Susobhan Mandal Department of Physical Sciences Indian Institute of Science Education and Research Kolkata Mohanpur India

We know from Noether’s theorem that there is a conserved charge for every continuous symmetry. In General Relativity, Killing vectors describe the spacetime symmetries and to each such Killing vector field, we can associate conserved charge through stress-energy tensor of matter which is mentioned in the article. In this article, I show that under simple set of canonical transformation of most general class of Bogoliubov transformation between creation, annihilation operators, those charges associated with spacetime symmetries are broken. To do that, I look at stress-energy tensor of real scalar field theory (as an example) in curved spacetime and show how it changes under simple canonical transformation which is enough to justify our claim. Since doing Bogoliubov transformation is equivalent to coordinate transformation which according to Einstein’s equivalence principle is equivalent to turn on effect of gravity, therefore, we can say that under the effect of gravity those charges are broken.

关键词： Noether’s Theorem Killing Vector Field Einstein’s Equivalence Broken Charges

ON THE CHARACTERISTICS OF PROPAGATION OF INTRASEASONAL OSCILLATIONS AND THEIR OBSERVED ASSOCIATION WITH TROPICAL SYNOPTIC WAVES IN THE ASIAN-WESTERN PACIFIC REGION IN BOREAL SUMMER

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Journal of Tropical Meteorology 2011年第3期17卷 248-256页

作者：何洁琳万齐林管兆勇林爱兰王黎娟 Guangzhou institute of Tropical and Marine Meteorology CMA Guangxi Climate Center Nanjing University of Information Science&technology KLME

Using the daily average outgoing longwave radiation and NCEP/NCAR reanalysis data in boreal summer(Mays to Octobers)from 1979 to 2007,the propagating characteristics of convection intraseasonal oscillations(ISOs)in the Asian-western Pacific(AWP)region and the relationship between tropical synoptic waves and ISOs are examined by means of finite-domain wavenumber-frequency energy spectrum analysis and lagged linear regression *** results are shown as follows.(1)The AWP ISOs propagate both eastward and westward,showing seasonality and *** ISOs propagate eastward with a period of 30 to 60 days over equatorial regions in the whole AWP region,while the westward propagation occurs over 10 to 20°N western Pacific or in the late summers(August,September and October) with periods of 20 to 40 *** ISOs eastward propagation mainly occurs in primary summers while the westward propagation enhances in late summers.(2)Deep ISO convections associate with westerly and cyclonic circulation anomalies that first form in the indian Ocean,propagate eastward to the dateline in the Pacific and then turn *** ISOs convections show northwestward propagating characteristics in the western North Pacific.(3)The ISOs link with the tropical synoptic waves *** convection signals,though with different spatio-temporal scale,enhance simutaneously in the northwestern Pacific,and the ISOs facilitate the forming of a cluster of tropical cyclones(TCs),while a cluster of TCs convection becomes one portion of the northwestward ISOs.

关键词： intraseasonal oscillation finite-domain wavenumber-frequency energy spectral analysis lagged linear regression technique tropical synoptic wave

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Ecosystem Responses in the Distribution of Black Clam (<i>Villorita cyprinoides</i>) Beds in Vembanad Estuary during Environmental Changes Using GIS and RS

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Journal of Geographic Information System 2017年第3期9卷 245-266页

作者： Thankam Theresa Paul Grinson George A. Dennis N. R. Athira R. S. Biradar Rajani Khandagale K. G. Padmakumar Kochi Unit of Central Inland Fisheries Research institute Ernakulam North India Fishery Resources Assessment Division Ernakulam North India Socio Economic Evaluation and technology Transfer Division Central Marine Fisheries Research Institute Ernakulam North India Socio Economic Evaluation and technology Transfer Division Central Institute of Fisheries Education Versova India Former associate Director of Research Regional Agriculture Research Station Kumarakom India

The biomass and distribution of black clam (Villorita cyprinoides) in Vembanad, a tropical estuary located along the southwest coast of India varied significantly. Sampling was done in freshwater-dominated zone in the south (distal) and brackish water zone in the north (proximal), during pre and post monsoon seasons. Clam biomass was estimated from samples, collected from different stations during the study period. Water transparency and temperature were measured at the sample sites. Water samples were collected and analysed for salinity, dissolved oxygen (DO), pH and hardness. There was a significant difference in the clam biomass during the two seasons in the distal zone, and those collected from the distal and proximal zones during pre-monsoon season. The data were further analysed to determine the factors affecting the clam biomass distribution in the two zones and seasons. Factor analyses, comparing the distal zone during two seasons and zonal variations were similar to earlier observations. Step wise regression analyses found that dissolved oxygen (adjusted R2 = 0.3) is the only variable affecting clam survival during pre-monsoon period in the distal and proximal zones. A geographic map of the region obtained from the indian satellite sensor LISS (Linear Image Self Scanner) was used along with in situ data to map the results using inverse distance weightage model.

关键词： Clam Beds Inverse Distance Weightage GIS Monitoring Environment Model