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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

The energetic relationship among geoeffective solar flares, associated CMEs and SEPs

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Research in Astronomy and Astrophysics 2013年第8期13卷 978-990页

作者： Nipa j Bhatt Rajmal jain Arun kumar Awasthi Physics Dept C. U. Shah Science College Physical Research Laboratory (Dept. of Space Govt. of India)

Major solar eruptions （flares, coronal mass ejections （CMEs） and solar energetic particles （SEPs）） strongly influence geospace and space weather. Currently, the mechanism of their influence on space weather is not well understood and requires a detailed study of the energetic relationship among these eruptive phenomena. From this perspective, we investigate 30 flares （observed by RHESSI）, followed by weak to strong geomagnetic storms. Spectral analysis of these flares suggests a new power-law relationship （r - 0.79） between the hard X-ray （HXR） spectral index （before flarepeak） and linear speed of the associated CME observed by LASCO/SOHO. For 12 flares which were followed by SEP enhancement near Earth, HXR and SEP spectral analysis reveals a new scaling law （r - 0.9） between the hardest X-ray flare spectrum and the hardest SEP spectrum. Furthermore, a strong correlation is obtained between the linear speed of the CME and the hardest spectrum of the corresponding SEP event （r - 0.96）. We propose that the potentially geoeffective flare and associated CME and SEP are well-connected through a possible feedback mechanism, and should be regarded within the framework of a solar eruption. Owing to their space weather effects, these new results will help improve our current understanding of the Sun-Earth relationship, which is a major goal of research programs in heliophysics.

关键词： Sun coronal mass ejections (CMEs) - Sun flares - Sun particle emission - Sun solar-terrestrial relations - Sun X-rays

Nanostructured porous polyaniline(PANI)coated carbon cloth(CC)as electrodes for flexible supercapacitor device

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journal of Materials Science & Technology 2021年第29期88卷 168-182页

作者： Dinesh j.Ahirrao Ajay kumar Pal Vikalp Singh Neetu jha Department of Physics Institute of Chemical TechnologyMatunga(E)Mumbai400019India Department of Physics Ramniranjan Jhunjhunwala CollegeGhatkopar(W)Mumbai 400086India

Nanostructured porous polyaniline(PANI)has been synthesized and coated simultaneously on a highly flexible and conductive carbon cloth(CC)substrate using a simple in-situ chemical oxidative polymerization *** coated CC(PANI-CC)based flexible electrodes were further used for the fabrication of flexible supercapacitor *** the comparison purpose,pure PANI has also been synthesized and tested for its electrochemical *** energy storage capacity of PANI and PANI–CC composite was investigated using electrochemical techniques like CV,GCD,and EIS in a potential range from 0 to 0.8 V in 1 M H_(2)SO_(4)***-CC flexible electrodes exhibited the highest specific capacitance of 691 F/g;whereas,pure PANI could only achieve 575 F/g of specific capacitance at 1 A/*** also exhibited outstanding cyclic stability by recollecting 94%of its initial capacitance after 2000 GCD *** actual implementation,a flexible supercapacitor device has been fabricated using stainless steel sheets and PANI-CC flexile *** energy storage performance of the PANI-CC flexible supercapacitor device was tested at several bending angles,which resulted in 72%of capacitance retention at a maximum bending angle of 140°compared to the capacitance obtained at an angle 0°(flat state).PANI-CC exhibited improved electrochemical performance than pure PANI due to the synergistic effect between PANI and ***,CC helped in enhancing the conductivity and stability;whereas,PANI boosted the capacitance owing to its excellent porosity and fast pseudocapacitive charge storage response.

关键词： Polyaniline Carbon cloth Flexible supercapacitor Flexible electrode Composite

Metrology for sub-Rayleigh-length target positioning in~10^(22)W/cm^(2)laser-plasma experiments

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High Power Laser Science and Engineering 2024年第3期12卷 90-105页

作者： E.A.Vishnyakov A.Sagisaka K.Ogura T.Zh.Esirkepov B.Gonzalez-Izquierdo C.D.Armstrong T.A.Pikuz S.A.Pikuz W.Yan T.M.jeong S.Singh P.Hadjisolomou O.Finke G.M.Grittani M.Nevrkla C.M.Lazzarini A.Velyhan T.Hayakawa Y.Fukuda j.K.Koga M.Ishino K.Kondo Y.Miyasaka A.Kon M.Nishikino Y.V.Nosach D.Khikhlukha I.P.Tsygvintsev D.kumar j.Nejdl D.Margarone P.V.Sasorov S.Weber M.Kando H.Kiriyama Y.Kato G.Korn K.Kondo S.V.Bulanov T.Kawachi A.S.Pirozhkov ELI Beamlines Facility The Extreme Light Infrastructure ERICDolníBrežanyCzech Republic Kansai Institute for Photon Science(KPSI) QSTKyotoJapan Central Laser Facility Rutherford Appleton LaboratorySTFCHarwell OxfordDidcotUK Institute for Open and Transdisciplinary Research Initiatives Osaka UniversityOsakaJapan HB11 Energy Holdings FreshwaterAustralia Key Laboratory for Laser Plasmas(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghaiChina Institute of Plasma Physics ASCR PragueCzech Republic FZU-Institute of Physics ASCR PragueCzech Republic Czech Technical University in Prague FNSPEPragueCzech Republic Institute of Laser Engineering Osaka UniversityOsakaJapan Institute of Physics National Academy of Sciences of UkraineKyivUkraine ISTEQ AR YerevanArmenia

Tight focusing with very small f-numbers is necessary to achieve the highest at-focus ***,tight focusing imposes strong demands on precise target positioning in-focus to achieve the highest on-target irradiance We describe several near-infrared,visible,ultraviolet and soft and hard X-ray diagnostics employed in a~10^(22)W/cm^(2)laser±plasma *** used nearly 10 j total energy femtosecond laser pulses focused into an approximately1.3-μm focal spot on 5±20μm thick stainless-steel *** discuss the applicability of these diagnostics to determine the best in-focus target position with approximately 5μm accuracy(i.e.,around half of the short Rayleigh length)and show that several diagnostics(in particular,3ωreflection and on-axis hard X-rays)can ensure this *** demonstrated target positioning within several micrometers from the focus,ensuring over 80%of the ideal peak laser intensity *** approach is relatively fast(it requires 10±20 laser shots)and does not rely on the coincidence of low-power and high-power focal planes.

关键词： laser-plasma interaction precise target positioning spectroscopy ultra-high intensity X-rays

Projective Changes between Generalized (<i>α</i>, <i>β</i>)-Metric and Randers Metric

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Advances in Pure Mathematics 2020年第5期10卷 312-321页

作者： Pradeep kumar Madhu T. S. sharath B. R. Department of Mathematics School of Engineering Presidency University Bengaluru India Department of Mathematics Sri Jagadguru Renukacharya College of Science Arts and Commerce Bengaluru India Department of Mathematics Vemana Institute of Technology Bengaluru India

Projective change between two Finsler metrics arises from Information Geom-etry. Such metrics have special geometric properties and will play an important role in Finsler geometry. The purpose of the present paper is to find a relation to characterize the projective change between generalized (α, β) - metric ( μ1, μ2 and μ3 ≠ 0 are constants) and Randers metric , where α and are two Riemannian metrics, β and are 1-forms. Further, we study such projective change when generalized (α, β) -metric F has some curvature property.

关键词： Finsler Space with (α β) -Metric Projective Change Locally Projectively Flat Randers Metric

Image based leaf segmentation and counting in rosette plants

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Information Processing in Agriculture 2019年第2期6卷 233-246页

作者： j.Praveen kumar S.Domnic National Institute of Technology TiruchirappalliIndia

This paper proposes an efficient method to extract the leaf region and count the number of leaves in digital plant *** plant image analysis plays a significant role in viable and productive *** is used to record the plant growth,plant yield,chlorophyll fluorescence,plant width and tallness,leaf area,*** and *** growth is a major character to be analyzed among these plant characters and it directly depends on the number of leaves in the *** this paper,a new method is presented for leaf region extraction from plant images and counting the number of *** proposed method has three *** first step involves a new statistical based technique for image *** second step involves in the extraction of leaf region in plant image using a graph based *** third step involves in counting the number of leaves in the plant image by applying Circular Hough Transform(CHT).The proposed work has been experimented on benchmark datasets of Leaf Segmentation Challenge(LSC).The proposed method achieves the segmentation accuracy of 95.4%and it also achieves the counting accuracy of0.7(DiC)and 2.3(|DiC|)for datasets(A1,A2 and A3),which are better than the state-of-the-art methods.

关键词： Plant image analysis Plant phenotyping Leaf region extraction Leaf count

AtGGM2014, an Arabidopsis gene co-expression network for functional studies

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Science China(Life Sciences) 2015年第3期58卷 276-286页

作者： MA ShiSong BOHNERT Hans j DINESH-kumar Savithramma P Department of Plant Biology and the Genome Center College of Biological Sciences University of California Departments of Plant Biology and of Crop Sciences University of Illinois at Urbana-Champaign

Gene co-expression networks provide an important tool for systems biology studies. Using microarray data from the Array Express database, we constructed an Arabidopsis gene co-expression network, termed At GGM2014, based on the graphical Gaussian model, which contains 102,644 co-expression gene pairs among 18,068 genes. The network was grouped into 622 gene co-expression modules. These modules function in diverse house-keeping, cell cycle, development, hormone response, metabolism, and stress response pathways. We developed a tool to facilitate easy visualization of the expression patterns of these modules either in a tissue context or their regulation under different treatment conditions. The results indicate that at least six modules with tissue-specific expression pattern failed to record modular regulation under various stress conditions. This discrepancy could be best explained by the fact that experiments to study plant stress responses focused mainly on leaves and less on roots, and thus failed to recover specific regulation pattern in other tissues. Overall, the modular structures revealed by our network provide extensive information to generate testable hypotheses about diverse plant signaling pathways. At GGM2014 offers a constructive tool for plant systems biology studies.

关键词： Arabidopsis gene co-expression network graphical Gaussian model plant development stress response hormone response

Mechanics of granular column collapse in fluid at varying slope angles

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journal of Hydrodynamics 2017年第4期29卷 529-541页

作者： K.kumar j.-Y.Delenne K.Soga Computational Geomechanics Research Group Department of Engineering University of Cambridge IATE UMR 1208 INRA-CIRAD-Montpellier Supagro-UM2 University of Montpellier 2 Department of Civil and Environmental Engineering University of California

This paper investigates the effect of initial volume fraction on the runout characteristics of collapse of granular columns on slopes in fluid. 2-D sub-grain scale numerical simulations are performed to understand the flow dynamics of granular collapse in fluid. The discrete element method（DEM） technique is coupled with the lattice Boltzmann method（LBM）, for fluid-grain interactions, to understand the evolution of submerged granular flows. The fluid phase is simulated using multiple-relaxation-time LBM（LBM-MRT） for numerical stability. In order to simulate interconnected pore space in 2-D, a reduction in the radius of the grains（hydrodynamic radius） is assumed during LBM computations. The collapse of granular column in fluid is compared with the dry cases to understand the effect of fluid on the runout behaviour. A parametric analysis is performed to assess the influence of the granular characteristics（initial packing） on the evolution of flow and run-out distances for slope angles of 0 °, 2.5°, 5 ° and 7.5 °. The granular flow dynamics is investigated by analysing the effect of hydroplaning, water entrainment and viscous drag on the granular mass. The mechanism of energy dissipation, shape of the flow front, water entrainment and evolution of packing density is used to explain the difference in the flow characteristics of loose and dense granular column collapse in fluid.

关键词： Lattice Boltzmann method(LBM) discrete element method(DEM) granular column collapse granular flows hydroplaning water entrainment viscous drag

Feeder and post Deccan Trap dyke activities in the northern slope of the Satpura Mountain： Evidence from new 40Ar-39Ar ages

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Geoscience Frontiers 2017年第3期8卷 483-492页

作者： j.P.Shrivastava R.kumar N.Rani Department of Geology University of Delhi

We present new 40Ar-39Ar plagioclase crystallization ages from the dykes exposed at the northern slope of the Satpura Mountain range near Betul-jabalpur-Pachmarhi area, - 800 km NE of the Western Ghats escarpment. Among the two plateau ages, the first age of 66.56 ± 0.42 Ma from a dyke near Mohpani village represents its crystallization age which is either slightly older or contemporaneous with the nearby Mandla lava flows （63-65 Ma）. We suggest that the Mohpani dyke might be one of the feeders for the surrounding lava flows as these lavas are significantly younger than the majority of the main Deccan lavas of the Western Ghats （66.38-65.54 Ma）. The second age of 56.95 -- 1.08 Ma comes from a younger dyke near Olini village which cuts across the lava flows of the area. The age correlates well with the Mandla lavas which are chemically similar to the uppermost Poladpur, Ambenali and Mahabaleshwar Formation lavas of SW Deccan. Our study shows that the dyke activities occurred in two phases, with the second one representing the terminal stage.

关键词： 40Aro39Ar ages Deccan dykes Betul-jabalpur-Pachmarhi area Narmada-Tapi dyke system