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International Journal of Coal Science & Technology 2024年第2期11卷 111-122页

作者： Heena dhawan d.k.sharma ANRF Ministry of ScienceNew DelhiIndia department of Energy Science and Engineering Indian Institute of Technology DelhiNew Delhi 110016India

Chemical leaching of coals would be required to produce cleaner coals for some special applications where physical benefi-ciation may not be effective *** would also help in recovering Li and rare earth metals besides in the sequestration of CO_(2).About 20 Indian coals having complexly distributed moderate to high ash contents were sequentially treated with various alkali–acid such as NaOH-HCl,HF,HCl,HCl-HF,and NaOH-HCl-HF *** aimed to establish and design the best stepwise sequential process for the highest degree of demineralisation through a chemical leaching *** and process intensification studies were carried *** than 80%demineralisation of Madhaipur and Neemcha coals was observed using the best sequential treatment designed *** repeated stepwise treatment of the alkali and the acid was also studied,which was found to significantly enhance the degree of demineralisation of *** integrated process of alkali–acid leaching followed by solvent extraction(Organo-refining)and vice versa of the treated coal was also studied for producing cleaner coals.

关键词： Alkali–acid leaching demineralisation Integrated process Rare earth elements

View Creation for Queriesin Object Oriented databases

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Journal of Computer Science & Technology 1999年第4期14卷 349-362页

作者： RajeshNarang k.d.sharma departmentofComputerScience UniversityofDelhiDelhi110007，I departmentofComputerScience Universityof

A view in object oriented databases corresponds to virtual schemawith restructured generalization and decomposition hierarchies. Numbers of viewcreation methodologies have been proposed. A major drawback of existing method-ologies is that they do not maintain the closure property. That is, the result of aquery does not have the same semantics as embodied in the object oriented datamodel. Therefore, this paper presents a view creation methodology that derives aclass in response to a user's query, integrates derived class in global schema (i.e.,considers the problem of classes moving in class hierarchy) and selects the requiredclasses from global schema to create the view for user's query. Novel idea of viewcreation includes: (a) an object algebra for class derivation and customization (wherethe derived classes in terms of object instances and procedure/methods are studied),(b) maintenance of closure property, and (c) classification algorithm which providesmechanism to deal with the problem of a class moving in a class hierarchy.

关键词： object manipulation type level operation instance level operation,object algebra object operator operator syntax operator semantics derived class,class integration view creation algorithm

Vibration analysis of axisymmetric functionally graded viscothermoelastic spheres

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Acta Mechanica Sinica 2014年第1期30卷 100-111页

作者： d.k.sharma J.N.sharma S.S.dhaliwal V.Walia department of Mathematics Sant Longowal Institute of Engineering and Technology department of Mathematics National Institute of Technology

The present study focuses on the analysis of free vibrations of axisymmetric functionally graded hollow spheres. The material is assumed to be graded in radial di- rection with a simple power law. Matrix Frrbenious method of extended power series is employed to derive the analytical solutions for displacement, temperature, and stresses. The dispersion relations for the existence of various types of pos- sible modes of vibrations in the considered hollow sphere are derived in a compact form. In order to explore the character- istics of vibrations, the secular equations are further solved by using fixed point iteration numerical technique with the help of MATLAB software. The numerical results have been presented graphically for polymethyl methecrylate materials in respect of natural frequencies, frequency shift, inverse quality factor, displacement, temperature change, and radial stress.

关键词： Functionally graded Stresses Vibrations Fr6benius - dispersion - Spherical structures

design of experiments to optimize the extraction parameters of a power grade Indian coal

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International Journal of Coal Science & Technology 2018年第4期5卷 417-429页

作者： Heena dhawan Sreedevi Upadhyayula d.k.sharma Centre tor Energy Studies Indian Institute of TechnologyNew Delhi 110016India department of Chemical Engineering Indian Institute of TechnologyNew Delhi 110016India

Low grade high ash coals with difficult physical washability characteristics require chemical cleaning techniques such as solvent extractio n to obtain super clean coal with lower ash conte ***,an In di an low grade coal has ash con tent around 44%-50%and there is a need to maximize its solvent extraction yield so as to make this power grade coal industrially *** paper highlights the use of definitive screening design and response surface methodology to extract the maximum organic matter from kedla coal using ethylenediannnine(EdA)and N-methyl pyrollidone(NMP)as solvents under mild atmospheric pressure *** coal was pre-treated with acetic acid before extractions were carried *** parameters such as the acid pre-treatment time,acid concenmion,particle size,the co-solvent concentratio n and the solvent concentration were optimized in this *** this design of experimenls technique about 40%of the organic matter with minimal ash(less than 2%)content was「endered extractable unlike the already postulated designer solvent system—e,N system(*** containing small amount of EdA)that uses coal to solve nt ratio as 1:17(wt/vol)and coal to co-solvent ratio as 1:l(wt/vol)thus only giving 19%extraction ***,the present design of experimetechnique helps in conserving the number of experimems for process intensification.

关键词： Coal Extraction yield Acid pre-treatment definitive screening design Response surface methodology

Bio-amelioration of alkali soils through agroforestry systems in central Indo-Gangetic plains of India

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Journal of Forestry Research 2014年第4期25卷 887-896页

作者： Y.P.Singh Gurbachan Singh d.k.sharma Central Soil Salinity Research Institute Regional Research StationLucknow (U.P.) 226005 India Indian Council of Agricultural Research New Delhi 110001 India Central Soil Salinity Research Institute Karnal Haryana 132001 India

A long-term field study was initiated during 1995 at Central Soil Salinity Research Institute, Regional Research Station, Lucknow （26047＇58＂ N and 80°46＇24＂ E） to analyze the effect of agroforestry systems on amelioration of alkali soils. Three agroforestry systems （pas- toral, silvipastoral and silvicultural） were compared with the control where no agroforestry system was introduced. Tree-based silvicultural and silvipastoral systems were characterized by tree species Prosopis juliflora and Acacia nilotica along with grass species Leptochloafusca, Panicum maximum, Trifolium alexandrium and Chloris gayana. Growth of ten-year-old Prosopis juliflora and Acacia nilotica planted in combi- nation with grasses was significantly higher over the silviculture system with the same species. Tree biomass yields of P. juliflora （77.20 t·ha-1） and A. nilotica （63.20 t·ha-1） planted under silvipastoral system were significantly higher than the sole plantation of （64.50 t·ha-1 and 52.75 t·ha-1）. Fodder yield under the pastoral system was significantly higher than the silvipastoral system during initial years but it was at par with that of silvipastoral systems after eight years of plantation. The microbial biomass carbon in the soils of silvipastoral systems was significantly higher than in soils under sole plantation of trees and control systems. The Prosopis-based silvipastoral system proved more effective in reduc- ing soil pH, displacing Na＋ from the exchange complex, increasing or- ganic carbon and available N, P and k. Improvement in soil physical properties such as bulk density, porosity, soil moisture and infiltration rate was higher in the Prosopis-based silvipastoral system than in the silviculture system or control On the basis of biomass production and improvement in soil health due to tree ＋ grass systems, silvipastoral agroforestry system could be adopted for sustainable reclamation ofhighly alkali soils.

关键词： agroforcstry systems alkali soils biomass production mi-crobial biomass soil amelioration

Fractionation of coal through organo-separative refining for enhancing its potential for the CO2-gasification

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International Journal of Coal Science & Technology 2020年第3期7卷 504-515页

作者： Heena dhawan Rohit kumar Sreedevi Upadhyayula k.k.Pant d.k.sharma Centre for Energy Studies Indian Institute of Technology DelhiNew Delhi110016India department of Chemical Engineering Indian Institute of Technology DelhiNew Delhi110016India

Coal gasification has already been extensively studied earlier under varying conditions of steam,CO2,O2,inert *** coal and its e,N and NMP-dETA SCC products recovered through organo-refining under milder ambient pressure conditions were subjected to CO2-gasification in a fixed bed reactor under varying ***2 being an inert gas becomes the most challenging to be utilized during the gasification *** SCCs showed better CO2-gasification reactivity than the raw Belbaid coal at 900°*** use of the catalyst k2CO3 tremendously increased the gasification reactivity for both raw coal and the *** use of sugarcane bagasse for CO2-gasification along with raw coal as well as with residual coal was also *** under CO2 atmosphere conditions was used to structurally understand the coals as the coal structure gets loosened after extraction.

关键词： Coal Solvent extraction CO2 gasification Catalyst

Effect of organic component(tartrate) addition on cerium nitrate's ability to inhibit corrosion of mild steel in NaCl solution

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Journal of Rare Earths 2024年第10期42卷 1995-2002页

作者： Minakshi koundal Chhaya sharma A.k.Singh department of Applied Science and Engineering Indian Institute of Technology RoorkeeSaharanpur Campus department of Pulp and Paper Technology Indian Institute of Technology Roorkee Saharanpur Campus

Cerium tartrate（CeTar）,produced in this study by precipitating cerium nitrate with potassium sodium tartrate（kNaTar）,was examined as a corrosion *** loss tests show inhibition efficiency of 71.7% with Ce（NO3）3and 88.7% with CeTar inhibitor for one-month exposure to mild steel in 7 g/L NaCl *** inhibition efficiency drops to 28.6% with the fo rmer and remains around 8 7% with the latter inhibitor after six months of *** results from electrochemical testing indicate that the inhibition efficiency decreases by adding cerium ***,the cerium tartrate inhibitor demonstrates a nearly constant inhibition efficiency for up to 30 d,i.e.,≈90%.Electrochemical impedance spectroscopy（EIS） performed in these cases shows the following results:（ⅰ） with cerium nitrate,a film of iron and cerium oxide,which on prolonged exposure diminishes,and（ⅱ） with cerium tartrate,the formation of a bimetallic film（Fe-tartrate-Ce） and a mixture of cerium hydroxide and iro n oxide that protects steel for a longer *** inferences are based on the analyses of scanning electron microscopy/energydispersive X-ray analysis（SEM/EdAX）,X-ray diffraction（XRd）,Fourier transform infrared spectroscopy（FTIR）,X-ray photoelectron（XPS）,and Raman spectroscopy results.

关键词： Cerium nitrate Cerium tartrate Corrosion inhibition Inhibitor film characterization Mild steel Rare earths

Nonlinear Coupling of kinetic Alfvén Waves and Ion Acoustic Waves in the Inner Heliosphere

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Research in Astronomy and Astrophysics 2024年第10期24卷 141-158页

作者： Mani k.Chettri Vivek Shrivastav Rupak Mukherjee Nidhi Gaur R.P.sharma Hemam d.Singh department of Physics Sikkim UniversityGangtokSikkimIndia dAV Public School Sector 14GurugramHaryanaIndia Plasma Simulation Laboratory Department of Energy Science and EngineeringIndian Institute of Technology DelhiDelhiIndia

We study the nonlinear coupling of kinetic Alfvén waves with ion acoustic waves applicable to the Earth’s radiation belt and near-Sun streamer belt solar wind using dynamical equations in the form of modified Zakharov *** simulations show the formation of magnetic field filamentary structures associated with density humps and dips which become turbulent at later times,redistributing the energy to higher *** magnetic power spectra exhibit an inertial range kolmogorov-like spectral index value of-5/3 for k_(⊥)ρ_(i)d by a steeper dissipation range spectra with indices~-3 for the radiation belt case and~-4 for the nearSun streamer belt solar wind case,here k_(⊥)andρ_(i)represent the wavevector component perpendicular to the background magnetic field and the ion thermal gyroradius,*** quasilinear theory in terms of the Fokker-Planck equation in the region of wavenumber turbulent spectra,we find the particle distribution function flattening in the superthermal tail population which is the signature of particle energization and plasma heating.

关键词： Sun:chromosphere Sun:corona Sun:heliosphere

Biomass and bio-energy production of ten multipurpose tree species planted in sodic soils of indo-gangetic plains

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Journal of Forestry Research 2010年第1期21卷 19-24,I0001页

作者： Y.P.Singh Gurbachan Singh d.k.sharma Principal Scientist Central Soil Salinity Research InstituteRegional Research StationJail RoadLucknow(U.P.) India-226005 Central Soil Salinity Research Institute Kachwa RoadKarnalHaryanaIndia132001 Director Central Soil Salinity Research Institute Regional Research StationJail RoadLucknow (U.P.) India-226005 Head5

Ten multipurpose tree species, Terminalia arjuna, Azadirechta indica, Prosopis juliflora, Pongamia pinnata, Casuarina equisetifolia, Prosopis alba, Acacia nilotica, Eucalyptus tereticornis, Pithecellobium dulce and Cassia siamea, were raised in a monoculture tree cropping system on the sodic soil of Gangetic alluvium in north India （26° 47° N： 80°46′ E） for 10 years to evaluate the biomass and bio-energy production. The soil was compact, sodic and impervious to water associated with nutrient deficiency or toxicity. Maximum plant height was recorded with E. tereticornis followed by *** and P. juliflora. A. nilotica performed better than the other species in terms of diameter at breast height （dBH） with a basal area of 13.04 m^2·ha^-1, followed by P. juliflora and C. equisetifolia. P. juliflora and A. nilotica produced nearly similar biomass of 56.50 and 50.75 Mg·ha^-1, respectively, at 10 years; whereas, A. indica, P. pinnata, C. siamea and P. alba did not perform well. P. juliflora scored maximum in net biomass production and nutrient demand. Nutrient （N, P, k, Ca, and Mg） concentrations were higher in leaf component of P. juliflora. However, in woody components, there was little variation between the species. N removal for production of one ton of wood was lowest in Acacia nilotica, P in T. arjuna, k in P. dulce and Ca and Mg in P. juliflora. P. juliflora gave the highest energy production of 1267.75 ***^-1 followed by A. nilotica with 1206 ***^-1 and the lowest ofA. indica （520.66 ***^-1）.

关键词： biomass sodic soils Gangetic alluvium multipurpose treespecies nutrient concentration nutrient use efficiency.

Numerical simulation and experiment of error field measurement using luminous trace of electron beam in SST-1

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Plasma Science and Technology 2019年第10期21卷 9-16页

作者： Someswar dUTTA Y PARAVASTU J dHONGdE H CHUdASMA S GEORGE k dHANANI A MAkWANA C dOdIYA P VARMORA d k sharma A k SINGH U kUMAR d RAVAL U PRASAd Z kHAN R SRINIVASAN d RAJU Institute for Plasma Research GandhinagarGujrat 382428India Homi Bhabha National Institute (HBNI) AnushaktinagarMumbai 400094India

In contrast to the earlier experiments conducted in other machines, here, in SST-1 the error field measurement experiment is performed with a filled gas pressure ~8×10^-4 mbar which helped to create a luminescent toroidal beam of electron path originated due to impact excitation and guided by the toroidal magnetic field. Beam path deviations are observed and recorded from radial and top ports using visible range cameras. Such creation and detection of the electron beam path differs from the earlier works where the gun emitted electron beam deviation in ultrahigh vacuum was detected on a collector-grid/fluorescent screen. In the present experiment, large beam deviations were observed. Later investigation of the experimental set-up reveals existence of a possible source of radial electric field in between the source and the vacuum vessel which are separately grounded. Thus, to understand the observed phenomena, experiments are numerically modeled with deviated TF coil set, PF coil set and the electron source location. A particle tracing code is used to follow the electron path in the magnetic field generated by the coil set of interest. Simulation results suggest that the large deviation corresponds to the E×B drifts and not due to the large field errors. Toroidally averaged field errors of the SST-1 TF coils at toroidal field of B0?=?15 kG are negligibly small ~B0?×?10^-6 or less, which should not adversely affect the plasma performance.

关键词： electron beam error field SST-1 TF coil