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characteristic Study of the Boundary Layer Parameters over the Arabian Sea and the Bay of Bengal Using the QuikScAT Dataset

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Advances in Atmospheric Sciences 2007年第4期24卷 631-643页

作者： V.HAMZA c.A.BABU T.P.SABIN Department of Atmospheric Sciences Cochin University of Science and TechnologyCochin-682 016India

The marine atmospheric boundary layer （MABL） plays a vital role in the transport of momentum and heat from the surface of the ocean into the atmosphere. A detailed study on the MABL characteristics was carried out using high-resolution surface-wind data as measured by the QuikScAT （Quick scatterometer） satellite. Spatial variations in the surface wind, frictional velocity, roughness parameter and drag coefficient for the different seasons were studied. The surface wind was strong during the southwest monsoon season due to the modulation induced by the Low Level Jetstream. The drag coefficient was larger during this season, due to the strong winds and was lower during the winter months. The spatial variations in the frictional velocity over the seas was small during the post-monsoon season （-0.2 m s^-1）. The maximum spatial variation in the frictional velocity was found over the south Arabian Sea （0.3 to 0.5 m s^-1） during the southwest monsoon period, followed by the pre-monsoon over the Bay of Bengal （0.1 to 0.25 m s^-1）. The mean wind-stress curl during the winter was positive over the equatorial region, with a maximum value of 1.5×10^-7 N m^-3, but on either side of the equatorial belt, a negative wind-stress curl dominated. The area average of the frictional velocity and drag coefficient over the Arabian Sea and Bay of Bengal were also studied. The values of frictional velocity shows a variability that is similar to the intraseasonal oscillation （ISO） and this was confirmed via wavelet analysis. In the case of the drag coefficient, the prominent oscillations were ISO and quasi-biweekly mode （QBM）. The interrelationship between the drag coefficient and the frictional velocity with wind speed in both the Arabian Sea and the Bay of Bengal was also studied.

关键词： boundary layer characteristics drag coefficient frictional velocity roughness length QuikScAT wind

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Mixed convection flow in vertical channel with boundary conditions of third kind in presence of heat source/sink

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Applied Mathematics and Mechanics(English Edition) 2012年第8期33卷 1015-1034页

作者： J.c.UMAVATHI J.PRATHAP KUMAR JAWERIYA SULTANA Department of Mathematics Gulbarga UniversityGulbarga 585106KarnatakaIndia

The effects of viscous dissipation and heat source/sink on fully developed mixed convection for the laminar flow in a parallel-plate vertical channel are investigated. The plate exchanges heat with an external fluid. Both conditions of equal and different reference temperatures of the external fluid are considered. first, the simple cases of the negligible Brinkman number or the negligible Grashof number are solved analytically. Then, the combined effects of buoyancy forces and viscous dissipation in the presence of heat source/sink are analyzed by a perturbation series method valid for small values of the perturbation parameter. To relax the conditions on the perturbation parameter, the velocity and temperature fields are solved by using the Runge-Kutta fourth-order method with the shooting technique. The velocity, temperature, skin friction, and Nusselt num- bers at the plates are discussed numerically and presented through graphs.

关键词： mixed convection viscous fluid perturbation method Runge-Kuttashooting method heat source/sink

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Identifying coastal towns and small cities in Denmark using global population data to support climate change adaptation

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International Journal of Digital Earth 2020年第9期13卷 1040-1054页

作者： James M.fitton Martin Lehmann David c.Major Department of Planning Aalborg UniversityAalborgDenmark The Earth Institute Columbia UniversityNew YorkNYUSA

coastal settlements face many hazards from climate ***,there has been extensive focus on developing and implementing ***,these efforts have prodominantly centred on larger *** towns and small cities(urban areas between 1000 and 100,000 people)have received little attention,despite experiencing a number of barriers to *** absence of information on the global scale of the adaptation challenge within coastal towns and small cities may have contributed to these settlements being *** paper develops a method that can be used to estimate the numbers,sizes,and locations of coastal towns and small cities worldwide from global population data(Global Human Settlement data).Denmark is used as a pilot for this method with settlements over 1000 people classified with relatively high *** method developed here represents a potentially fruitful approach to supporting coastal adaptation,as coastal towns and small cities are identifiable globally,they can be classified into *** will support an assessment of their risk to coastal hazards,and could facilitate knowledge and practice sharing between similar coastal towns and small cities.

关键词： climate change adaptation global data coastal hazards Denmark small urban areas

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fractal Basins in the Lorenz Model

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chinese Physics Letters 2011年第6期28卷 59-62页

作者： I.Djellit J.c.Sprott M.R.ferchichi Laboratory of Mathematics Dynamics and ModelizationAnnaba-Algeria Department of Physics University of WisconsinMadisonWI 53706 USA

The Lorenz mapping is a discretization of a pair of differential *** illustrates the pertinence of computational *** describe complex dynamics,bifurcations,and chaos in the *** basins are displayed by numerical simula... 详细信息

关键词： equations chaos map

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Effects of water stress and Nacl stress on different life cycle stages of the cold desert annual Lachnoloma lehmannii in china

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Journal of Arid Land 2019年第5期11卷 774-784页

作者： Jannathan MAMUT TAN Dunyan carol c BASKIN Jerry M BASKIN Xinjiang Key Laboratory of Grassland Resources and Ecology and Ministry of Education Key Laboratory for Western Arid Region Grassland Resources and EcologyCollege of Grassland and Environment SciencesXinjiang Agricultural UniversityUrumqi 830052China college of Biology and Environmental Sciences Jishou UniversityJishou 416000China Department of Biology University of KentuckyLexingtonKY 40506USA Department of Plant and Soil Sciences University of KentuckyLexingtonKY 40546USA

for a plant species to complete its life cycle in arid and saline environments,each stage of the life cycle must be tolerant to the harsh environmental *** aim of the study was to determine the effects of water stress(water potentials of–0.05,–0.16,–0.33,–0.56,–0.85 and–1.21 MPa)and Nacl stress(50,100,200,300,400,500 and 600 mmol/L Nacl)on seed germination percentage,seedling survival and growth,juvenile growth and plant reproduction of Lachnoloma lehmannii Bunge(Brassicaceae),an cold desert annual that grows in the Junggar Basin of Xinjiang,china in *** indicated that low water stress(–0.05 and–0.16 MPa)had no significant effect on seed germination *** a decrease in water potential,germination percentage decreased,and no seeds germinated at–0.85 and–1.21 MPa water *** percentage of seeds was significantly affected by Nacl stress,and higher germination percentages were observed under non-saline than saline *** increase in Nacl concentrations progressively inhibited seed germination percentage,and no seeds germinated at ≥400 mmol/L Nacl ***-germinated seeds were transferred from both PEG(polyethylene glycol-6000)and Nacl solutions to distilled water for seed germination *** number of surviving seedlings and their heights and root lengths significantly decreased as Nacl stress *** 30% of the plants survived and produced fruits/seeds at 200 mmol/L Nacl ***,seed germination,seedling establishment and reproductive stage in the life cycle of *** are water-and salt-tolerant,with seedlings being the least *** tolerances help explain why this species can survive and produce seeds in arid and saline habitats.

关键词： drought stress Lachnoloma lehmannii salinity tolerance seed germination seedling growth

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An analytical symplectic approach to the vibration analysis of orthotropic graphene sheets

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Acta Mechanica Sinica 2017年第5期33卷 912-925页

作者： Xinsheng Xu Dalun Rong c.W.Lim changyu Yang Zhenhuan Zhou State Key Laboratory of Structure Analysis of Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of Technology Department of Architecture and civil Engineering City University of Hong Kong

A nonlocal continuum orthotropic plate model is proposed to study the vibration behavior of single-layer graphene sheets (SLGSs) using an analytical symplectic approach. A Hamiltonian system is established by introducing a total unknown vector consisting of the displacement amplitude, rotation angle, shear force, and bending moment. The high-order governing differential equation of the vibration of SLGSs is transformed into a set of ordinary differential equations in symplectic space. Exact solutions for free vibration are obtianed by the method of separation of variables without any trial shape functions and can be expanded in series of symplectic eigenfunctions. Analytical frequency equations are derived for all six possible boundary conditions. Vibration modes are expressed in terms of the symplectic eigenfunctions. In the numerical examples, comparison is presented to verify the accuracy of the proposed method. comprehensive numerical examples for graphene sheets with Levy-type boundary conditions are given. A parametric study of the natural frequency is also included.

关键词： Hamiltonian system Analytical method Nonlocal elasticity theory Orthotropic graphene sheet Natural frequency

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Assessing support alternatives for longwall gateroads subject to changing stress

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International Journal of Mining Science and Technology 2021年第1期31卷 103-110页

作者： Gabriel S.Esterhuizen I.Berk Tulu Dave f.Gearhart Heather Dougherty Mark Van Dyke National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA West Virginia University MorgantownWV 26506USA

Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted *** stress changes can result in significant deformation of the entries that may include roof sag,rib dilation,and floor *** operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall *** paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support *** research included monitoring of ground and support interaction at several operating longwall mines in the U.S.,analysis and calibration of numerical models that adequately represent the bedded rock mass,and observation of the support systems and their response to changes in *** models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic *** research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress *** information is then used to assess the ability of support systems to maintain the stability of the *** application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof *** method is shown to produce realistic estimates of gateroad entry stability and support performance,allowing alternative support systems to be assessed during the design and planning stage of longwall operations.

关键词： Longwall Gateroad Support design coal Standing support

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Microstructure and mechanical properties of similar and dissimilar metal gas tungsten constricted arc welds:Maraging steel to 13-8 Mo stainless steel

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Defence Technology（防务技术） 2019年第1期15卷 111-121页

作者： c.V.S.Murthy A.Gopala Krishna G.M.Reddy Defence Research and Development Laboratory Jawaharlal Nehru Technological University Defence Metallurgical Research Laboratory

Maraging steel (250) and 13-8 Mo stainless steel plates were joined by gas tungsten constricted arc welding(GTcAW) process in similar and dissimilar metal combinations using 13-8 Mo stainless steel filler wire. The similar and dissimilar metal welds made in solutionized condition were subjected to standard post weld hardening treatments direct ageing at 485 ℃, soaking for 31/2 hours followed by air cooling(ageing treatment of maraging steel) and direct ageing at 510 ℃, soaking for 4 h followed by air cooling(ageing treatment of 13-8 Mo stainless steel). The joint characterization studies include microstructure examination, microhardness survey across the weldments and transverse weld tensile *** and dissimilar metal weldments responded to both the post weld ageing treatment. After post weld aging, increase in yield strength, UTS and slight reduction in % elongation of similar and dissimilar metal were observed. The observed tensile properties were correlated with microstructure and hardness distribution across the welds.

关键词： Maraging steel(250) 13-8 Mo stainless steel Mechanical properties Microstructure

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Revisiting the death of geography in the era of Big Data:the friction of distance in cyberspace and real space

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International Journal of Digital Earth 2018年第5期11卷 451-469页

作者： Su Yeon Han Ming-Hsiang Tsou Keith c.clarke Department of Geography San Diego State UniversitySan DiegoCAUSA Department of Geography University of CaliforniaSanta BarbaraCAUSA

Many scholars have argued that the importance of geographic proximity in human interactions has been diminished by the use of the Internet,while others disagree with this *** have noted the distance decay effect in both cyberspace and real space,showing that interactions occur with an inverse relationship between the number of interactions and the distance between the locations of the ***,these studies rarely provide strong evidence to show the influence of distance on interactions in cyberspace,nor do they quantify the differences in the amount of friction of distance between cyberspace and real *** fill this gap,this study used massive amounts of social media data(Twitter)to compare the influence of distance decay on human interactions between cyberspace and real space in a quantitative *** estimate the distance decay effect in both cyberspace and real space,the distance decay function of interactions in each space was *** the distance decay in cyberspace in this study can help predict the degree of information flow across space through social *** how far ideas can be diffused through social media is useful for users of location-based services,policy advocates,public health officials,and political campaigners.

关键词： first law of geography distance decay Big Data Twitter social media information diffusion

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ORTHOGONAL POLYNOMIAL EXPANSIONS Of THERMODYNAMIcPROPERTIES Of BINARY AND TERNARY SYSTEMS

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Acta Metallurgica Sinica(English Letters) 1998年第5期11卷 329-334页

作者： Y.Su L.Liu Z.c.Wang central Iron & Steel Research Inst Beijing China

Orthogonal polynomial expansions are ased to present integral properties of binary and ternary sgstems. The partial property of each component can be expressed with the same set of coeffcients. It was shown that the coefficients are completely independent. Ternary system of Pb-Sb-Sn and its three binary sub-systems are calculated as example.

关键词： orthogonal polynomial thermodynamic property binary andternary systems

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