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Journal of materials Science & Technology 2014年第1期30卷 13-18页

作者： S.Sudhahar m.krishna kumar V.Jayaram.krishnan R.muralidharan R.mohan kumar Department of Physics Presidency College Department of Physics P.S.G.College of Arts and Science Department of Science and Humanities Vel Tech High Tech Dr.Rangarajan Dr.Sakunthala Engineering College

Rare earth Sm＋ ion doped potassium hydrogen phthalate （KHP） single crystal was grown by slow evaporation technique. Single crystal and powder X-ray diffraction analyses confirm the crystalline perfection of Sm＋ ion doped KHP crystal. The functional groups of pure and Sm＋ ion doped KHP crystals were identified by Fourier transform infrared spectroscopy （FTIR） spectral studies. Thermogravimetric and differential thermal analyses were carried out to study the thermal behavior of the grown crystals. UV-Vis studies explored the optical transmittance of the grown crystals in the entire visible region. The mechanical strength and etching studies were performed to assess the perfection of the pure and Sm＋ ion doped KHP crystals. The refractive index and birefringence properties of the grown crystal were analyzed. The second harmonic generation efficiency of Sm＋ ion doped KHP crystals was observed by Kurtz-Perry powder test.

关键词： Crystal growth Potassium hydrogen phthalate (KHP) single crystal Differential thermal analysis FTIR Hardness

Steady rotation of a composite sphere in a concentric spherical cavity

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Acta mechanica Sinica 2012年第3期28卷 653-658页

作者： D.Srinivasacharya m.krishna Prasad Department of mathematics National Institute of Technology

The problem of steady rotation of a composite sphere located at the centre of a spherical container has been investigated. A composite particle referred to in this paper is a spherical solid core covered with a permeable spherical shell. The Brinkman＇s model for the flow inside the compos- ite sphere and the Stokes equation for the flow in the spheri- cal container were used to study the motion. The torque ex- perienced by the porous spherical particle in the presence of cavity is obtained. The wall correction factor is calculated. In the limiting cases, the analytical solution describing the torque for a porous sphere and for a solid sphere in an un- bounded medium are obtained from the present analysis.

关键词： Rotation Porous sphere Solid core Stokesflow Brinkman equation Stress jump coefficient. Torque Wall correction factor

Nonlinear Thermal Buoyancy on Ferromagnetic Liquid Stream Over a Radiated Elastic Surface with Non Fourier Heat Flux

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Computer modeling in Engineering & Sciences 2021年第2期126卷 599-616页

作者： T.K.Sreelakshmi Abraham Annamma A.S.Chethan m.krishna murthy C.S.K.Raju Department of mathematics BMS Institute of Technology and ManagementBengaluru560064India Department of mathematics School of Applied SciencesREVA UniversityBengaluru560064India Department of mathematics GITAM School of ScienceGITAM Deemed to be UniversityBengaluru562163India

The current article discusses the heat transfer characteristics of ferromagnetic liquid over an elastic surface with the thermal radiation and non-Fourier heat *** most of the existing studies,the heat flux is considered as constant,but whereas we incorporated the non-Fourier flux to get the exact performance of the ***,we excluded the PWT and PHF cases to control the boundary layer of the *** governing equations related to our contemplate are changed into non-linear ordinary differential equations(ODE’s)by utilizing appropriate similarity changes,which are at the point enlightened by Runge–Kutta based shooting *** equations are broken down concerning boundary conditions and to be explained prescribed wall temperature(PWT)and prescribed heat flux(PHF)*** impacts of diverse non-dimensional physical parameters on velocity and temperature profiles are laid out ***,the assortment of skin friction and local Nusselt number for both PWT and PHF cases for various assessments of non-dimensional parameters have been sorted *** the wrap-up of the examination,we suspect that the friction factor coefficient is higher in the PWT case compared to the PHF *** result helps to conclude that the flux conditions are useful for cooling applications.

关键词： Ferromagnetic liquid nonlinear thermal buoyancy non-Fourier heat flux radiated elastic surface

Effect of laminate thickness on moisture diffusion of polymer matrix composites in artificial seawater ageing

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Frontiers of materials Science 2012年第3期6卷 225-235页

作者： Ratna PAL H.N.NARASImHA mURTHY m.SREEJlTHz,K.R.VISHNU mAHESH m.krishna IS.C.SHARmA Department of mechanical Engineering R.V.College of EngineeringBangalore-560059KarnatakaIndia Department of P.G.Studies and Research in Industrial Chemistry Kuvempu UniversityShankaraghattaShimoga-577451KarnatakaIndia Tumkur University Tumkur-572103KarnatakaIndia

The influence of laminate thickness of polymer matrix composites on moisture diffusion in seawater immersion, as well as the resulting mechanical property degradation for composites of glass/isopolyester （G/IPE）, carbon/isopolyester （C/IPE）, glass/vinylester （G/VE） and carbon/vinylester （CNE）, was investigated in this paper. Laminates 3 and 10 mm in thickness, fabricated using the wet hand lay-up technique, were characterized for moisture absorption in artificial seawater medium, and their flexural strength and interlaminar shear strength （ILSS） degradations were studied. moisture diffusion was observed to be anamolous to the Fick＇s law for both 3 and 10 mm thick samples in the later stage of diffusion. moisture permeability of 10 mm thick samples was two to three order greater than that of 3 mm thick ones, while the time to moisture saturation remained unchanged. With the increase of laminate thickness, moisture saturation increased by 1.4% for CNE and 7% for GriPE. The residual flexural strength and ILSS were greater in case of 10 mm thick specimens after 200 days of exposure. SEm examination of the fractured specimens showed greater levels of fibre/matrix debonding in 10 mm thick specimens.

关键词： polymer matrix composite diffusion coefficient Fick's law degradation

Constructing a biofunctionalized 3D-printed gelatin/sodium alginate/chitosan tri-polymer complex scaffold with improvised biological andmechanical properties for bone-tissue engineering

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Bio-Design and manufacturing 2024年第1期7卷 57-73页

作者： Amit kumar Singh krishna Pramanik Amit Biswas Centre of Excellence in Tissue Engineering Department of Biotechnology and Medical EngineeringNational Institute of TechnologyRourkela 769008India

Sodium alginate(SA)/chitosan(CH)polyelectrolyte scaffold is a suitable substrate for tissue-engineering *** present study deals with further improvement in the tensile strength and biological properties of this type of scaffold to make it a potential template for bone-tissue *** experimented with adding 0%–15%(volume fraction)gelatin(GE),a protein-based biopolymer known to promote cell adhesion,proliferation,and *** resulting tri-polymer complex was used as bioink to fabricate SA/CH/GEmatrices by three-dimensional(3D)*** studies using scanning electron microscopy revealed the microfibrous porous architecture of all the structures,which had a pore size range of 383–419μm.X-ray diffraction and Fourier-transform infrared spectroscopy analyses revealed the amorphous nature of the scaffold and the strong electrostatic interactions among the functional groups of the polymers,thereby forming polyelectrolyte complexes which were found to improve mechanical properties and structural *** scaffolds exhibited a desirable degradation rate,controlled swelling,and hydrophilic characteristics which are favorable for bone-tissue *** tensile strength improved from(386±15)to(693±15)kPa due to the increased stiffness of SA/CH scaffolds upon addition of *** enhanced protein adsorption and in vitro bioactivity(forming an apatite layer)confirmed the ability of the SA/CH/GE scaffold to offer higher cellular adhesion and a bone-like environment to cells during the process of tissue *** vitro biological evaluation including the mTT assay,confocal microscopy analysis,and alizarin red S assay showed a significant increase in cell attachment,cell viability,and cell proliferation,which further improved biomineralization over the scaffold *** addition,SA/CH containing 15%gelatin designated as SA/CH/GE15 showed superior performance to the other fabricated 3D structures,demonstrating its pote

关键词： Scaffold Biomaterial Sodium alginate Chitosan Gelatin 3D printing Tissue engineering

Investigations on Low Speed Axial Compressor with Forward and Backward Sweep

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Journal of Thermal Science 2007年第2期16卷 121-133页

作者： m.Govardhan O.G.krishna kumar N.Sitaram Thermal Turbomachines Laboratory Department of Mechanical EngineeringIndian Institute of Technology MadrasChennai 600036India

In the recent past, experimental studies have shown some advantages of blade lean and sweep in axial compressors. As most of the experimental results are combined with other features, it is difficult to determine the effect of individual parameters on the performance of the compressor. The present numerical studies are aimed at understanding the performance and three-dimensional flow pattern at the exit of swept and unswept rotors. Three rotors, namely; unswept, 200 forward swept and 200 backward swept rotors are analysed with a specific intention of understanding the pattern of the blade boundary layer flow. The analysis was done using a fully three-dimensional viscous CFD code CFX-5. Results indicated reduction in pressure rise with sweep. Backward sweep is detrimental as far as the performance near endwalls is considered. On the other hand total pressure loss in the wake in mid span region is less with backward sweep, which favours its application here. However, backward sweep adversely affects the stall margin. The ability of the forward sweep to deflect the streamlines towards hub gets diminished at low flow rates. Forward sweep changes the streamline pattern in such a way that the suction surface streamlines are deflected towards the hub and the pressure surface streamlines are deflected towards the easing. An opposite behaviour is observed in backward swept rotors.

关键词： Sweep pressure rise streamline shift stall margin blade loading

Sources and dynamics of sedimentary organic matter in Sundarban mangrove estuary from Indo-Gangetic delta

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Ecological Processes 2017年第1期6卷 69-83页

作者： m.Bala krishna Prasad Alok kumar A.L.Ramanathan Dilip kumar Datta 22616 Shining Harness Street ClarksburgMD 20871USA School of Environmental Sciences Jawaharlal Nehru UniversityNew Delhi 110067India Environmental Science Discipline Khulna UniversityKhulna 9208Bangladesh

Introduction:mangrove forests are highly productive ecosystems distributed along the tropical coast *** biogeochemistry of mangroves are primarly driven by both allochthonous and autochthonous *** of organic matter in coastal ecosystems enables to understand the biogeochemical transformation of organic matter and its influence on ecosystem productivity in response to various changing environmental ***,the elemental and stable carbon and nitrogen levels were employed to understand the organic matter(Om)dynamics in the Sundarban mangrove ecosystem(India-Bangladesh).Results:Differences in stable isotope values indicate that variable sources influence the Om dynamics in Sundarban *** progressive enrichment inδ13C levels along the land-coastal continuum indicates that the terrestrial and marine inputs are dominant at the landward and seaward ends,*** CuO oxidationderived lignin phenol monomers describe significant levels of total lignin are preserved in Sundarban mangrove sediments during *** phenol monomer ratios are lower than the plant litter explaining that aromatic ring cleavage is the dominant mechanism for the lignin ***,the Ad/Al ratios were higher than the plant litter explaining the oxidation of propyl side chain of vascular Om influencing the carbon cycling in Sundarban ***,the Ad/Al ratios describe the vascular Om degradation is through the oxidation of propyl side ***:The regional variability in land-use regulates the spatial variability in C,N,OC/TN ratio,δ13C andδ15N between the Indian and the Bangladesh Sundarban mangroves and indicates that in the upstream terrestrial organic matter and/or mangrove plant litter contribute significant amount of organic matter,whereas the marine POC influences the organic matter dynamics in *** three end-member mixing model applying terrestrial plant litter,seston,and marine POC as e

关键词： Sundarban mangrove Organic carbon Stable isotopes Lignin phenols Three end-member mixing model

Radiation-absorption,chemical reaction,Hall and ion slip impacts on magnetohydrodynamic free convective flow over semi-infinite moving absorbent surface

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Chinese Journal of Chemical Engineering 2021年第6期34卷 40-52页

作者： m.Veera krishna Department of mathematics Rayalaseema UniversityKurnoolAndhra Pradesh 518007India

The investigation of radiation-absorption,chemical reaction,Hall and ion-slip impacts on unsteady mHD free convective laminar flow of an incompressible viscous,electrically conducting and heat generation/absorbing fluid enclosed with a semi-infinite porous plate within a rotating frame has been *** plate is assumed to be moving with a constant velocity in the direction of fluid movement.A uniform transverse magnetic field is applied at right angles to the porous surface,which is absorbing the fluid with a suction velocity changing with *** non-dimensional governing equations for present investigation are solved analytically making use of two term harmonic and non-harmonic *** graphical results of velocity,temperature and concentration distributions on the analytical solutions are displayed and discussed with reference to pertinent *** is found that the velocity profiles decreased with an increasing in Hartmann number,rotation parameter,the Schmidt number,heat source parameter,while it increased due to an increase in permeability parameter,radiation-absorption parameter,Hall and ion slip ***,the temperature profile is an increasing function of radiation-absorption parameter,whereas an increase in chemical reaction parameter,the Schmidt number Sc or frequency of oscillations decrease the temperature profile on ***,it is found that the concentration profile is decreased with an escalating in the Schmidt number or the chemical reaction parameter.

关键词： Chemical reaction Free convection Heat source Heat transfer mass diffusion Radiation absorption

Design and Robustness Analysis of a Wave-Based Controller for Tethered Towing of Defunct Satellites

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IEEE/CAA Journal of Automatica Sinica 2023年第1期10卷 278-280页

作者： Rui Qi Yang Zhang krishna D.kumar the School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China IEEE the Department of Aerospace Engineering Ryerson UniversityToronto M5B 2K3Canada

Dear Editor, A microgravity environment in space, the elasticity of the tether,and complex flexible appendages make the tethered-towing system a nonlinear and underactuated system, which is sensitive and difficult to stabilize. This letter develops a controller based on wave propagation for tethered towing of defunct satellites, and carries out a robustness analysis of the controller via numerical simulation.

关键词： system elasticity letter

AN m/m/C RETRIAL QUEUEING SYSTEm WITH BERNOULLI VACATIONS

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Journal of Systems Science and Systems Engineering 2009年第2期18卷 222-242页

作者： B.krishna kumar R.RUKmANI V.THANGARAJ Department of mathematics College of EngineeringAnna UniversityChennai600 025India Department of mathematics Pachaiyappa's CollegeChennai600030India Ramanujan Institute for Advanced Study in mathematics University of MadrasChennai600 005India

In this paper, a steady-state markovian multi-server retrial queueing system with Bernoulli vacation scheduling service is studied. Using matrix-geometric approach, various interesting and important system performance measures are obtained. Further, the probability descriptors like ideal retrial and vain retrial are provided. Finally, extensive numerical illustrations are presented to indicate the quantifying nature of the approach to obtain solutions to this queueing system.

关键词： Retrial queue Bernoulli vacation matrix-geometric methods busy period vain retrial ideal retrial