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Friction assisted solid state lap seam welding and additive manufacturing method

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Defence Technology（防务技术） 2016年第1期12卷 16-24页

作者： prasad Rao KALVALA Javed AKRAM Mano MISRA Dept. of Metallurgical Engineering University of Utah

This paper describes results of seam welding of relatively high temperature melting materials, AISI 304, C-Mn steels, Ni-based alloys, CP Cu, CP Ni, Ti6Al4V and relatively low temperature melting material, AA6061. It describes the seam welding of multi-layered similar and dissimilar metallic sheets. The method described and involved advancing a rotating non-consumable rod(CP Mo or AISI 304) toward the upper sheet of a metallic stack clamped under pressure. As soon as the distal end of the rod touched the top portion of the upper metallic sheet, an axial force was applied. After an initial dwell time, the metallic stack moved horizontally relative to the stationery non-consumable rod by a desired length, thereby forming a metallurgical bond between the metallic sheets. Multi-track and multi-metal seam welds of high temperature metallic sheets, AISI 304, C-Mn steel,Nickel-based alloys, Cp Cu, Ti6Al4V and low temperature metallic sheets, AA6061 were obtained. Optical and scanning electron microscopy examination and 180 degree U-bend test indicated that defect free seam welds could be obtained with this method. Tensile- shear testing showed that the seam welds of AISI 304, C-Mn steel, Nickel-based alloy were stronger than the starting base metal counterparts while AA6061 was weaker due to softening. The metallurgical bonding at the interface between the metallic sheets was attributed to localized stick and slip at the interface, dynamic recrystallization and diffusion. The method developed can be used as a means of welding, cladding and additive manufacturing.

关键词： Lap seam welding Friction assisted welding Solid-state welding Cladding Additive manufacturing

Assessing resource vulnerability quadrants under changing precipitation trends in Uttarakhand,Central Himalayan region

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Journal of Mountain Science 2021年第10期18卷 2722-2741页

作者： Ayushi VLJHANI Vinay Shankar prasad SINHA Mini GOVINDAN Department of Natural Resources TERI School of Advanced Studies10 Institutional AreaVasant Kunj New Delhi 110070India The Energy and Resources Institute India Habitat CentreNew Delhi 110003India

The Central Himalayan region is vulnerable to the adverse effects of climate change and characterized by regional climatic *** livelihood of the mountain communities across the Himalaya is at risk owing to the consequences of variable precipitation *** exists limited empirical research on precipitation variability due to inadequate hydro-meteorological stations at highaltitude *** study uses a novel methodology which integrates precipitation variability with resource sensitivity over the three verticals of Central Himalaya:Himadri,Himachal and Shivaliks and across four major river basins:Yamuna,Upper Ganga,Ghaghar and *** magnitude of the significant precipitation trends was estimated through time series analysis at a 95%confidence *** assess the sensitivity of natural resources(forest,water and land)and human resources,fourteen mountain-specific indicators were identified which captured resource index using data standardization and principal component ***’s slope and Resource index were plotted in a 2D Cartesian coordinate to draw precipitation-resource quadrants with their effective coverage area:High Precipitation and Scarce Resources(35.92%);Low Precipitation and Abundant Resources(30.10%);Low Precipitation and Scarce Resources(22.33%)and High Precipitation and Abundant Resources(11.65%).This helped in developing quadrant-specific adaptation strategies under regional variability of *** methodology and the research findings will certainly assist water experts,resource managers and policy makers to strengthen adaptive capacity and improve the resilience of vulnerable communities across Himalaya.

关键词： Climate Change Trend analysis Resource-quadrant Vulnerability Adaptation Central Himalaya

Properties of Ternary One Dimensional Plasma Photomic Crystals for an Obliquely Incident Electromagnetic Wave Considering the Effect of Collisions in Plasma Layers

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Plasma Science and Technology 2012年第12期14卷 1084-1090页

作者： S. prasad Vivek SINGH A. K. SINGH Department of Physics Faculty of ScienceBanaras Hindu University

An analytical study is presented on the modal dispersion characteristics, group velocity, and effective group, as well as the phase index of a ternary one dimensional plasma photonic crystal for an obliquely incident electromagnetic wave considering the effect of collisions in plasma layers. The dispersion relation is derived by using the transfer matrix method and the boundary conditions based on electromagnetic theory. The dispersion curves are plotted for both the normal photonic band gap structure and the absorption photonic band gap structure. It is found that the increase in the angle of incidence shifts the photonic band gap toward higher frequencies. Also, the cutoff frequency is independent of collisions.

关键词： ternary plasma photonic crystal dispersion curves group and phase velocities,obliquely incident collision effect

Effect of Diffuser Vane Shape on the Performance of a Centrifugal Compressor Stage

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Journal of Thermal Science 2014年第2期23卷 127-132页

作者： T Ch Siva Reddy GV ramana Murty MVSSSM prasad Sreenidhi Institute of Science and Technology GhatkesarHyderabadA.P.India Vasavi College of Engineering Hhyderabad

The present paper reports the results of experimental investigations on the effect of diffuser vane shape on the performance of a centrifugal compressor stage. These studies were conducted on the chosen stage having a back- ward curved impeller of 500 turn tip diameter and 24.5 mm width and its design flow coefficient is Фd=0.0535. Three different low solidity diffuser vane shapes namely uncarnbered aerofoil, constant thickness flat plate and circular arc cambered constant thickness plate were chosen as the variants for diffuser vane shape and all the three shapes have the same thickness to chord ratio （t/c=0.1）. Flow coefficient, polytropic efficiency, total head coeffi- cient, power coefficient and static pressure recovery coefficient were chosen as the parameters for evaluating the effect of diffuser vane shape on the stage performance. The results show that there is reasonable improvement in stage efficiency and total head coefficient with the use of the chosen diffuser vane shapes as compared to conven- tional vaneless diffuser. It is also noticed that the aero foil shaped LSD has shown better performance when com- pared to flat plate and circular arc profiles. The aerofoil vane shape of the diffuser blade is seen to be tolerant over a considerable range of incidence.

关键词： Centrifugal compressor Vaneless diffuser Low solidity diffuser

Four-dimensional imaging of lattice dynamics using ab-initio simulation

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npj Computational Materials 2021年第1期7卷 53-59页

作者： Navdeep Rana Aditya prasad Roy Dipanshu Bansal Gopal Dixit Department of Physics Indian Institute of Technology BombayPowaiMumbai 400076India Department of Mechanical Engineering Indian Institute of Technology BombayPowaiMumbai 400076India

Time-resolved mapping of lattice dynamics in real-and momentum-space is essential to better understand several ubiquitous phenomena such as heat transport,displacive phase transition,thermal conductivity,and many *** this regard,time-resolved diffraction and microscopy methods are employed to image the induced lattice dynamics within a pump–probe *** this work,we demonstrate that inelastic scattering methods,with the aid of theoretical simulation,are competent to provide similar information as one could obtain from the time-resolved diffraction and imaging *** illustrate the robustness of the proposed method,our simulated result of lattice dynamics in germanium is in excellent agreement with the time-resolved x-ray diffuse scattering measurement performed using x-ray free-electron *** a given inelastic scattering data in energy and momentum space,the proposed method is useful to image in-situ lattice dynamics under different environmental conditions of temperature,pressure,and magnetic ***,the technique will profoundly impact where time-resolved diffraction within the pump–probe setup is not feasible,for instance,in inelastic neutron scattering.

关键词： field lattice dynamics

DYNAMICAL BEHAVIOR OF AN INNOVATION DIFFUSION MODEL WITH INTRA-SPECIFIC COMPETITION BETWEEN COMPETING ADOPTERS

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Acta Mathematica Scientia 2022年第1期42卷 364-386页

作者： Rakesh KUMAR Anuj Kumar SHARMA Govind prasad SAHU Department of Applied Sciences Shaheed Bhagat Singh State UniversityFerozepurPunjab 152004India Department of Mathematics L.R.D.A.V.CollegeJagraonLudhianaPunjab 142026India Center for Basic Sciences Pt Ravishankar Shukla UniversityRaipur(Chhattisgarh).India

In this paper,we proposed an innovation diffusion model with three compartments to investigate the diffusion of an innovation(product)in a particular *** model exhibits two equilibria,namely,the adopter-free and an interior *** existence and local stability of the adopter-free and interior equilibria are explored in terms of the effective Basic Influence Number(BIN)R_(A).It is investigated that the adopter free steady-state is stable if R_(A)<*** consideringτ(the adoption experience of the adopters)as the bifurcation parameter,we have been able to obtain the critical value ofτresponsible for the periodic solutions due to Hopf *** direction and stability analysis of bifurcating periodic solutions has been performed by using the arguments of normal form theory and the center manifold *** numerical simulations in the support of analytical results have been presented.

关键词： intra-specific competition basic influence number local stability Hopf-bifurcation normal form theory center manifold theorem

Genetic Diversity Analysis of Rice Germplasm in Tripura State of Northeast India Using Drought and Blast Linked Markers

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Rice science 2017年第1期24卷 10-20页

作者： Alpana ANUPAM Jahangir IMAM Syed Mohammad QUATADAH Anantha SIDDAIAH Shankar prasad DAS Mukund VARIAR Nimai prasad MANDAL Central Rainfed Upland Rice Research Station ICAR Research Complex for North Eastern Hill Region Tripura Centre

We genotyped 74 rice germplasms including Tripura＇s local landraces, improved varieties, cultivars and breeding lines and other rice varieties using molecular markers for genetic diversity, drought QTLs, and blast resistance genes. The number of alleles per locus ranged from 2 to 5 with an average of 2.9. The polymorphic information content value per locus ranged from 0.059（RM537） to 0.755（RM252） with an average of 0.475. Cluster analysis based on 30 simple sequence repeat markers revealed 5 clusters and also indicated the presence of variability within the rice accessions. The drought QTL q DTY2.1 was found in 56.0% of germplasms and q DTY1.1 was detected in only 6.8% of the germplasms. Out of seven rice blast resistance genes screened, only two rice varieties, RCPL-1-82 and Buh Vubuk（Lubuk）, were positive for four blast resistance genes while only Releng possessed two blast resistance genes. Among 74 rice germplasms, only three accessions, Releng, RCPL1-82 and Buh Vubuk（Lubuk）, possessed both drought-related QTLs and blast resistance genes. Overall, the 74 indigenous rice genotypes showed low level of genetic diversity, which is in contrast to high level of genetic diversity among rice varieties in northeast India, where highlights the good farming practice, conservation of germplasms and the limitation of molecular markers employed in this study. The presence of both drought related QTLs and blast resistance genes in some of the germplasms can be useful in future breeding programmes.

关键词： drought blast alleles breeding ranged polymorphic Northeast screened upland germplasm

Gender plasticity uncovers multiple sexual morphs in natural populations of Cedrus deodara (Roxb.) G. Don

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Ecological Processes 2021年第1期10卷 459-469页

作者： Vinod prasad Khanduri Arun Sukumaran Chandra Mohan Sharma Department of Forestry College of ForestryVCSG Uttarakhand University of Horticulture and ForestryRanichauriTehri GarhwalUttarakhand 249199India Present Address:State Farming Corporation of Kerala Chithalvetty EstateKalanjoor KollamKeralaIndia.

Background:The expression of gender in gymnosperms is challenging because the extent of variability in gender segregations in tree crowns and selection pressure of nature can modify the gender through ***:An in-depth investigation on spatial segregation of genders in tree crowns and sex expression of a total of 500 trees in five different natural populations of Cedrus deodara was carried out and verified the occurrence of subdioecious(co-existence of male,female,and monoecious)genders in ***:Five different sexual morphs were apparent among the 500 selected individuals as(1)pure male(M):bearing only male strobili in the whole crown with 22.2%;(2)pure female(F):bearing only female strobili in the whole crown with 12.4%;(3)mixed-monoecious(MM):bearing both male and female strobili with 13.6%;(4)predominantly female(PF)with 25.6%;and(5)predominantly male(PM)with 26.2%.The occurrence of multiple sexual morphs resulted from the complex selection pressure,which increased the stability of the *** segregation of genders in crown layers deemed to increase the fitness that may be a mechanism for accelerating *** results of the study suggest that the subdioecious gender expression in *** is evolved through the monoecy–paradioecy *** production of male strobili revealed non-significant effect of tree sizes whereas a significant effect was observed for the production of female *** study established that the total pollen and seed outputs in *** changed frequently according to gender ***:The size of the tree,resource availability,sex allocation,plant architecture,gender segregation in crowns,and habitat conditions are the prominent causes for gender plasticity.

关键词： Gender Sex expression Gender segregation Strobili Pre-fertilisation Monoecy Dioecy

Multi-component synthesis of methylene bis isoxazolo[4,5-b]-pyridine-N-oxides

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Chinese Chemical Letters 2010年第8期21卷 927-930页

作者： E.Rajanarendar M.Nagi Reddy K.rama Murthy Department of Chemistry Kakatiya University

A three component one-pot protocol was investigated for the synthesis of methylene bis isoxazolo[4,5-b]-pyridine-N-oxides from commercially available materials.

关键词： Multi-component synthesis Knoevenagel condensation Michael addition New methodology