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A High Order Spectral Volume Formulation for Solving Equations Containing Higher Spatial Derivative Terms II:Improving the Third Derivative Spatial Discretization Using the LDG2 Method

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Communications in Computational Physics 2012年第8期12卷 767-788页

作者： ravi kannan CFD Research Corporation 215Wynn DriveHuntsville AL 35805USA

In this paper,the second in a series,we improve the discretization of the higher spatial derivative terms in a spectral volume(SV)*** motivation for the above comes from[***.,46(2),314–328],wherein the authors developed a variant of the LDG(Local Discontinuous Galerkin)flux discretization *** variant(aptly named LDG2),not only displayed higher accuracy than the LDG approach,but also vastly reduced its unsymmetrical *** this paper,we adapt the LDG2 formulation for discretizing third derivative terms.A linear Fourier analysis was performed to compare the dispersion and the dissipation properties of the LDG2 and the LDG *** results of the analysis showed that the LDG2 scheme(i)is stable for 2nd and 3rd orders and(ii)generates smaller dissipation and dispersion errors than the LDG formulation for all the *** 4th order LDG2 scheme is howevermildly unstable:as the real component of the principal eigen value briefly becomes *** order to circumvent the above,a weighted average of the LDG and the LDG2 fluxes was used as the final numerical *** a weight of 1.5%for the LDG(i.e.,98.5%for the LDG2)was sufficient tomake the scheme *** scheme is still predominantly LDG2 and hence generated smaller dissipation and dispersion errors than the LDG *** experiments are performed to validate the *** general,the numerical results are very promising and indicate that the approach has a great potential for higher dimension korteweg-de Vries(kdV)type problems.

关键词： Spectral volume LDG2 LDG higher spatial derivative terms kDV Fourier analysis

A High Order Spectral Volume Formulation for Solving Equations Containing Higher Spatial Derivative Terms:Formulation and Analysis for Third Derivative Spatial Terms Using the LDG Discretization Procedure

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Communications in Computational Physics 2011年第10期10卷 1257-1279页

作者： ravi kannan CFD Research Corporation 215Wynn DriveHuntsvilleAL 35805USA

In this paper,we develop a formulation for solving equations containing higher spatial derivative terms in a spectral volume(SV)context;more specifically the emphasis is on handling equations containing third derivative *** formulation is based on the LDG(Local Discontinuous Galerkin)flux discretization method,originally employed for viscous equations containing second derivatives.A linear Fourier analysis was performed to study the dispersion and the dissipation properties of the new *** Fourier analysis was utilized for two purposes:firstly to eliminate all the unstable SV partitions,secondly to obtain the optimal SV *** experiments are performed to illustrate the capability of this *** this formulation is extremely local,it can be easily parallelized and a h-p adaptation is relatively straightforward to *** general,the numerical results are very promising and indicate that the approach has a great potential for higher dimension korteweg-de Vries(kdV)type problems.

关键词： Spectral volume LDG higher spatial derivative terms kDV Fourier analysis

Recent advances in the in-plane shear testing of Mg alloy sheets

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Journal of Magnesium and Alloys 2023年第2期11卷 405-424页

作者： Mahesh Panchal Lalit kaushik ravi k.R Rajesh khatirkar Shi-Hoon Choi Jaiveer Singh Department of Mechanical Engineering Indian Institute of Technology JodhpurKarwarJodhpur 342030RajasthanIndia Department of Advanced Components and Materials Engineering Sunchon National University255 Jungang-roSuncheonJeonnam 57922Republic of Korea Department of Metallurgical and Materials Engineering Indian Institute of Technology JodhpurKarwarJodhpur 342030RajasthanIndia Department of Metallurgical and Materials Engineering Visvesvaraya National Institute of Technology(VNIT)South Ambazari RoadNagpur 440010MaharashtraIndia

Sheet-metal products are integral parts of engineering industries and academia research. Various testing techniques have revealed the deformation behaviors of sheet metals under complex stress states. Information obtained from tensile and compression tests, however, are insufficient for the identification of material parameters relevant to modern constitutive laws, which require experimental setups capable of generating various loading conditions and applying great amounts of strain to sheet metals. In-plane shear testing has emerged as an important method to overcome the challenges associated with tension and compression tests and can provide additional information about deformation behaviors under large plastic strains. Materials such as Mg alloys with poor levels of both ductility and formability cannot accommodate large plastic strains. Therefore, tension and compression tests have limitations in explaining the material behaviors that occur during sheet metal forming where large plastic strains are introduced. Many studies have been conducted to explain the deformation behaviors of Mg alloys under shear deformation techniques. These include severe plastic deformation(SPD), especially the equal channel angular pressing(ECAP)and equal channel angular extrusion, rolling combined with shear deformation i.e. differential speed rolling(DSR), and also in-plane shear for sheet metals, particularly under large levels of plastic strain. These in-plane shear technique involves the Miyauchi shear test, ASTM shear test, and twin bridge shear tests. Moreover, many experimental results have revealed that the evolution of microstructure and texture during in-plane shear is closely related to the failure behavior of materials. Therefore, this review is focused on techniques for in-plane shear testing that have been reported thus far, on the effect of in-plane shear on the microstructure development of Mg alloy sheets, and on the usefulness of in-plane shear testing to evaluate t

关键词： Mg alloys In-plane shear Texture Formability EBSD

Accounting for the uncertainties in the estimation of average shear wave velocity using VS-N correlations

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Frontiers of Structural and Civil Engineering 2021年第5期15卷 1199-1208页

作者： Jithin P ZACHARIAH ravi S JAkkA Department of Earthquake Engineering Indian Institute of Technology RoorkeeRoorkee 247667India

Site-specific seismic hazard analysis is crucial for designing earthquake resistance structures,particularly in seismically active *** wave velocity(V_(S))is a key parameter in such analysis,although the economy and other factors restrict its direct field measurement in many *** V_(S)-SPT-N correlations are routinely incorporated in seismic hazard analysis to estimate the value of V_(S).However,many uncertainties question the reliability of these estimated V_(S)*** paper comes up with a statistical approach to take care of such uncertainties involved in V_(S)*** measured SPT-N values from all the critical boreholes were converted into statistical parameters and passed through various correlations to estimate V_(S)at different *** effect of different soil layers in the boreholes on the V_(S)estimation was also taken into ***,the average shear wave velocity of the top 30 m soil coverV_(S30))is estimated after accounting for various epistemic and aleatoric *** scattering nature of the V_(S)values estimated using different V_(S)-N correlations was reduced significantly with the application of the *** results further clearly demonstrated the potential of the approach to eliminate various uncertainties involved in the estimation of V_(S)30 using general and soil-specific correlations.

关键词： uncertainties V_(S)-N correlations V_(S30) SPT data statistical methodology

Dynamic analysis and split range control for maximization of operating range of continuous microbial fuel cell

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Chinese Journal of Chemical Engineering 2020年第9期28卷 2368-2381页

作者： Ashish Yewale ravi Methekar Shailesh Agrawal Department of Chemical Engineering Visvesvaraya National Institute of TechnologySouth Ambazari RoadNagpur 440010India

Human development is inherently connected with availability of water and *** production requires water,whereas water treatment needs *** the other hand,microbial fuel cell has capability to produce energy and water simultaneously from waste water or organic *** this paper,first principle-based model of variable volume microbial fuel cell is *** retention time is selected as the manipulated variable using the study of steady state and dynamic *** PI and model predictive control strategies are developed for controlling the produced power from the cell,and its performance is tested for servo *** time for positive and negative set points is found to be 126 and 889 h in case of classical PI and 120 and 750 h in case of linear MPC,respectively along with large increase(three times order of magnitude)in working volume for negative set *** control challenges are overcome by using split range controller with variable and constant volume microbial fuel *** settling time for negative set point is found to be 49 and 21 h for classical PI and linear MPC schemes,respectively,which is significantly lower than using only variable volume microbial fuel ***,there is no increase in the working volume of the constant volume microbial fuel ***,operating range of the microbial fuel cell is enhanced using split range controller.

关键词： CMFC Modeling Variable Volume Split Range Controller

Detection of latent fingerprints using luminescent Gd_(0.95)Eu_(0.05)PO_(4) nanorods

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Journal of Rare Earths 2022年第4期40卷 572-578,I0003页

作者： Pushpendra Indranil Suryawanshi Rimple kalia ravi k.kunchala Shyam Lal Mudavath Boddu S.Naidu Energy and Environment Unit Institute of Nano Science and Technology(INST)MohaliPunjab-140306India Chemical Biology Unit Institute of Nano Science and Technology(INST)MohaliPunjab-140306India

Lanthanide ions doped luminescent materials are widely studied for latent fingerprint ***,most of these materials are synthesized at very high temperatures and use UV C light for visualization,which is harmful to eye,skin,***,the Gd_(0.95)Eu_(0.05)PO_(4) nanorods synthesized by a simple co-precipitation method at 185℃ were reported for latent fingerprint visualization under 395 nm *** Gd_(0.95)Eu_(0.05)PO_(4) nanomaterial has monoclinic crystal structure and shows rod-shaped ***,these Gd_(0.95)Eu_(0.05)PO_(4) nanorods exhibit excellent photoluminescence properties and strong fuchsia emission under UV *** nanorods have been employed for developing latent fingerprints on various porous and non-porous substrates by the powder dusting technique,which exhibits clear and well defined details with high contrast,selectivity and sensitivity under 395 nm UV *** fingerprints developed after 72 h of their deposition also show clear contrast with these ***,the Gd_(0.95)Eu_(0.05)PO_(4) nanorods can be used for latent fingerprint visualization applications.

关键词： GdPO_(4) Nanorods Europium Photoluminescence Latent fingerprint visualization Rare earths

New exact solutions of coupled Boussinesq-Burgers equations by Exp-function method

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Journal of Ocean Engineering and Science 2017年第1期2卷 34-46页

作者： L.k.ravi S.Saha Ray S.Sahoo National Institute of Technology Department of MathematicsRourkela 769008India

In the present paper,we build the new analytical exact solutions of a nonlinear differential equation,specifically,coupled Boussinesq-Burgers equations by means of Exp-function ***,we analyze the results by plotting the three dimensional soliton graphs for each case,which exhibit the simplicity and effectiveness of the proposed *** primary purpose of this paper is to employ a new approach,which allows us victorious and efficient derivation of the new analytical exact solutions for the coupled Boussinesq-Burgers equations.

关键词： Exp-function method Solitary wave solutions Non-linear evolution equations Coupled Boussinesq-Burgers equations

Evaluation of the wound healing potential of isoquercetin-based cream on scald burn injury in rats

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Burns & Trauma 2016年第1期4卷 45-52页

作者： Nitish Bhatia Gursharan kaur Varinder Soni Juhi kataria ravi k Dhawan Pharmacology Research Laboratory Department of PharmacologyKhalsa College of PharmacyAmritsarIndia. Department of PharmaceuticalAnalysis Khalsa College of PharmacyAmritsarIndia. Department ofBiochemistry Khalsa College of Pharmacy and TechnologyAmritsarIndia.

Background:The present study was designed to evaluate the potential of isoquercetin-based cream formulation on scald burn wound injury in ***:Four isoquercetin-based cream formulations viz.0.01,0.02,0.04,and 0.06%w/w were *** base and standard anti-burn cream containing silver sulfadiazine were also used for *** burn was given to rats by pouring water at 90℃on a shaved dorsal area of 20 *** second-degree burn injury was produced which was evaluated for the next 21 days for the percentage of wound contraction and period of *** day 21,the rats were sacrificed and histopathological slides were prepared using hematoxylin-eosin *** tissue was also screened for levels of oxidative stress using thiobarbituric acid reactive species(TBARS)and reduced glutathione(GSH)***:There was a significant increase in the percentage of wound contraction and a significant decrease in the period of epithelialization in isoquercetin-based cream-treated groups as compared with the control ***,most significant results were obtained with isoquercetin 0.06%w/w *** y,isoquercetin 0.06%w/w cream treatment resulted in almost complete re-epithelialization and re-structuring of the wound *** was a significant rise in TBARS and a decrease in GSH levels in the burn injury group which was reversed to a major extent by the application of isoquercetin-based ***:The results indicate the wound healing potential of isoquercetin-based *** biochemical studies indicate towards a possible role of free radical scavenging in the observed effects of isoquercetin in wound healing.

关键词： Isoquercetin Scald Burn Free radicals Wound healing

Relative effects of different leaf attributes on sapling growth in tropical dry forest

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Journal of Plant Ecology 2014年第6期7卷 544-558页

作者： ravi k.Chaturvedi A.S.Raghubanshi J.S.Singh Institute of Environment and Sustainable Development Banaras Hindu UniversityVaranasi 221005India Ecosystems Analysis laboratory Department of BotanyBanaras Hindu UniversityVaranasi 221005India

Aims Soil moisture content(SMC)influences establishment,survival and development of plant species and is considered as the most important limiting factor in tropical dry forest(TDF).In this study we attempt to establish the relationship between leaf attributes and of tree saplings in TDF and address the following questions:(i)how are the functional attributes of dominant tree saplings of TDF affected by seasonal changes in SMC at different habitats?,(ii)what is the relationship of functional attributes with each other?,(iii)how are the functional attributes and their plasticity affected by habitat con-ditions?and(iv)can the functional attributes in single or in com-bination predict the growth rate of tree saplings of TDF?The study was conducted on four sites(Hathinala,Gaighat,Harnakachar and Ranitali,listed in order of decreasing SMC)within the tropical dry deciduous forest in northern *** We analysed eight leaf attributes,specific leaf area(SLA);leaf dry matter content(LDMC);leaf nitrogen concentration(leaf N);leaf phosphorus concentration(leaf P);chlorophyll concentration(Chl);mass-based photosynthetic rate(Amass);mass-based stomatal con-ductance(Gsmass);intrinsic water use efficiency(WUEi)and three growth attributes,relative diameter increment(RDI);relative height increment(RHI);relative growth rate(RGR)of the 10 dominant tree saplings(viz.,Acacia catechu,Anogeissus latifolia,Boswellia serrata,Buchanania lanzan,Diospyros melanoxylon,Hardwickia binata,Lagerstroemia parviflora,Lannea coromandelica,Shorea robusta and Terminalia tomentosa)of a TDF and observed the effects of site,season and species for a period of 2 *** were selected in gradients of ***-wise multiple regression was performed to predict RDI,RHI and RGR from mean values of SMC and leaf *** Findings All the 11 attributes were interrelated and differed significantly among the 10 *** response varied across sites and *** the SMC g

关键词： tropical dry forest soil moisture content deciduousness tree saplings leaf attributes relative growth rate