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propulsion and power research 2022年第3期11卷 353-375页

作者： Debanjan das p.padmanabhan Systems reliability Group ISRO Propulsion ComplexIndian Space Research OrganisationTirunelveli(Mahendragiri)Tamil Nadu627133India

In this paper, transient phenomenon during start up process of a pump fed liquidrocket engine is investigated through numerical simulation. The engine studied in this workis designed such that engine systems are not wetted with propellant until the engine is com-manded to start. This is achieved by positioning the valves for propellant admission at the inter-face of test stand/flight stage and the engine. To evaluate engine performance during starttransient for such systems, unsteady flow simulation was conducted using Method of Charac-teristics and equations for priming. The same has been reported in this work. The results indi-cated a brief period of abrupt pressure rise at pump upstream after opening of the propellantadmission valves, during the process of priming of engine systems at valve *** peak pressure obtained was significantly higher than the propellant tank pressure as wellas the steady state pump suction pressure. The transitory pressure rise was found to occurdue to flow resistance at impeller inlet caused by formation of a forced vortex for orientingthe flow through impeller blades during off design transient regime. The maximum pressureat pump upstream, as computed from start transient simulation, was used as a design inputfor pump inlet feed lines. The engine was realized and subsequently qualified in a ground test facility. Hot test data obtained for pressure and flow rate during transient regime were found tobe in good agreement with the simulation results.

关键词： Method of Characteristics priming analysis Liquid rocket engines Start transient Off design pump losses

Impedance spectroscopy study of Na_(2)SmV_(5)O_(15) ceramics

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Journal of Advanced Ceramics 2014年第1期3卷 1-6页

作者： p.S.das p.K.CHAKrABOrTY Banarji BEHErA N.K.MOHANTY r.N.p.CHOUDHArY Department of physics Midnapore CollegeMidnapore 721101India School of physics Sambalpur UniversityBurla 768019SambalpurOdishaIndia Department of physics ITERSiksha“O”Anusandhan UniversityBhubaneswar 751030OdishaIndia

The polycrystalline Na_(2)SmV_(5)O_(15)(NSV),a new member of the tungsten bronze(TB)family,was prepared by a mixed-oxide *** room-temperature X-ray diffraction(XrD)confirmed the formation of single phase compound with orthorhombic crystal *** scanning electron microscopy(SEM)analysis indicated that the compound has homogeneous micrograph with a uniform distribution of small grains over the entire surface of the *** analysis of impedance spectra of NSV in a low-temperature range(-100℃to 100℃)at different frequencies exhibited interesting electrical properties like the contribution of bulk effect in conduction *** study of imaginary part of the impedance at different temperatures showed existence of relaxation peak with its shift towards higher frequency on increasing *** suggested the presence of frequency and temperature dependent relaxation process in the *** loss peak spectra were found to abide by Arrhenius law with small activation energy of 0.12 *** temperature dependence of AC and DC electrical conductivity(σ_(AC) and σ_(DC))was also obtained.

关键词： solid-state reaction microstructure impedance conductivity

Low-tension gas process in high-salinity and low-permeability reservoirs

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petroleum Science 2020年第5期17卷 1329-1344页

作者： Alolika das Nhut Nguyen Quoc p.Nguyen Hildebrand Department of petroleum and Geosystems Engineering University of Texas at Austin200 E.Dean KeetonAustinTX 78712USA

polymer-based EOr methods in low-permeability reservoirs face injectivity issues and increased fracturing due to near wellbore plugging,as well as high-pressure gradients in these *** may cause pore blockage and undergo shear degradation and even oxidative degradation at high temperatures in the presence of very hard ***-tension gas(LTG) flooding has the potential to be applied successfully for low-permeability carbonate reservoirs even in the presence of high formation brine *** LTG flooding,the interfacial tension between oil and water is reduced to ultra-low values(10^-3 dyne/cm) by injecting an optimized surfactant formulation to maximize mobilization of residual oil ***(nitrogen,hydrocarbon gases or C02) is co-injected along with the surfactant slug to generate in situ foam which reduces the mobility ratio between the displaced(oil) and displacing phases,thus improving the displacement efficiency of the *** this work,the mechanism governing LTG flooding in low-permeability,high-salinity reservoirs was studied at a microscopic level using microemulsion properties and on a macroscopic scale by laboratory-scale coreflooding *** main injection parameters studied were injected slug salinity and the interrelation between surfactant concentration and injected foam quality,and how they influence oil mobilization and displacement *** assessment of the results was performed by studying oil recovery,oil fractional flow,oil bank breakthrough and effluent salinity and pressure drop characteristics.

关键词： Enhanced oil recovery Foam Microemulsion Carbonate High salinity Low permeability

recovery of rare earth metals through biosorption: An overview

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Journal of rare Earths 2013年第10期31卷 933-943页

作者： Nilanjana das Devlina das Bioremediation Laboratory Environmental Biotechnology Division School of Biosciences and Technology VIT University

rare earth metals （rEMs） are a series of 17 elements that have widespread and unique applications in high technology, power generation, communications, and defense industries. These resources are also pivotal to emergent sustainable energy and car- bon alternative technologies. recovery of rEMs is interesting due to its high market prices along with various industrial applications. Conventional technologies, viz. precipitation, filtration, liquid-liquid extraction, solid-liquid extraction, ion exchange, super critical extraction, electrowinning, electrorefining, electroslag ref＇ming, etc., which have been developed for the recovery of rEMs, are not economically attractive. Biosorption represents a biotechnological innovation as well as a cost effective excellent tool for the recovery of rare earth metals from aqueous solutions. A variety ofbiomaterials such as algae, fungi, bacteria, resin, activated carbon, etc., have been reported to serve as potential adsorbents for the recovery of rEMs. The metal binding mechanisms, as well as the parameters in- fluencing the uptake of rare earth metals and isotherm modeling are presented here. This article provides an overview of past achievements and current scenario of the biosorption studies carried out using some promising biosorbents which could serve as an economical means for recovering rEMs. The experimental findings reported by different workers will provide insights into this re- search frontier.

关键词： biosorption biosorbent desorption rare earth metals recovery

Effect of Zn Concentration on Microstructural,Optical,and Hyperfine properties of Nanocrystalline a-Fe_(2)O_(3)

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Acta Metallurgica Sinica(English Letters) 2014年第4期27卷 563-568页

作者： N.r.panda D.Sahu B.S.Acharya p.Nayak S.p.pati D.das School of Basic Science Indian Institute of Technology BhubaneswarBhubaneswar 751013OdishaIndia School of physics Sambalpur UniversitySambalpur 768019OdishaIndia School of Chemistry Sambalpur UniversitySambalpur 768019OdishaIndia C.V.raman College of Engineering Bhubaneswar 752054OdishaIndia Department of Electronic Engineering Tohoku UniversitySendai 980-8579Japan UGC-DAE CSr Sector IIILB-8Bidhan NagarKolkata 700098India

Efforts have been made to prepare nanocomposites of a-Fe2O3-ZnO by wet chemical route with varying concentrations of the *** microstructural properties of the samples are investigated by powder X-ray diffractometry（pXrD） and Transmission electron *** concentration of Zn ions（up to 20 at%） leads to the formation of nanocomposites of a-Fe2O3 and *** of ZnFe2O4 phase is detected by the substitution of higher concentration of Zn2？（30 at%） in the *** average size of the nanoparticles remains in the range of 22–27 nm as obtained from XrD *** results obtained from electron microscopic studies are also close to these *** measurement shows the excitonic peak of ZnO around 390 nm which gets strengthened with Zn *** spectra show the metal–oxygen band below 700 *** temperature Mssbauer studies of the samples show the transition of iron oxide form antiferromagnetic state to paramagnetic state with increasing concentration of Zn2？.Sharp quenching of hyperfine field with Zn concentration is observed as the Hintvalue reduced to zero from 51 T.

关键词： Iron oxide ZnO Electron microscopy Mssbauer study

An empirical method for estimating surface area of aggregates in hot mix asphalt

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Journal of Traffic and Transportation Engineering(English Edition) 2016年第2期3卷 127-136页

作者： r.p.panda Sudhanshu Sekhar das p.K.Suhoo Department of Civil Engineering Siksha'O'Anusandhan UniversityBhubanesvoarIndia Institute of Technical Education and research Siksha'O'Anusandhan UniversityBhubaneswarIndia Department of Civil Engineering Veer Surendra Sai University of TeehologyBurlaIndia

Bitumen requirement in hot mix asphalt （HMA） is directly dependent on the surface area of the aggregates in the mix, which in turn has effect on the asphalt film thickness and the flow characteristics. The surface area of aggregate blend in HMA is calculated using the specific surface area factors assigned to percentage passing through some specific standard sieve sizes and the imaging techniques. The first process is less capital intensive, but purely manual and labour intensive and prone to human errors. Imaging techniques though eliminating the human errors, still have limited use due to capital intensiveness and requirement of well-established ]aboratories with qualified technicians. Most of the developing countries like India are shortage of well-equipped laboratories and qualified technicians. To overcome these difficulties, the present mathematical model has been developed to estimate the surface area of aggregate blend of HMA from physical properties of aggregates evaluated using simple laboratory equipment. This model has been validated compared with the existing established methods of calculations and can be used as one of the tools in different developing and under developed countries for proper design of HMA.

关键词： Surface area of aggregates physical properties of aggregates Hot mix asphalt Film thickness

Oscillatory Shannon entropy in the process of equilibration of nonequilibrium crystalline systems

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Chinese physics B 2015年第8期24卷 658-661页

作者： A.Giri Nilangshu K.das p.Barat Variable Energy Cyclotron Centre 1/AF Bidhannagar Indira Gandhi Centre for Atomic research

We present a study of the equilibration process of some nonequilibrium crystalline systems by means of molecular dynamics simulation technique. The nonequilibrium conditions are achieved in the systems by randomly defining velocity components of the constituent atoms. The calculated Shannon entropy from the probability distribution of the kinetic energy among the atoms at different instants during the process of equilibration shows oscillation as the system relaxes towards equilibrium. Fourier transformations of these oscillating Shannon entropies reveal the existence of Debye frequency of the concerned system.

关键词： entropy and other measures of information nonequilibrium and irreversible thermodynamics

A survey on control issues in renewable energy integration and microgrid

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protection and Control of Modern power Systems 2019年第1期4卷 89-115页

作者： Faisal r.Badal purnima das Subrata K.Sarker Sajal K.das Department of Mechatronics Engineering Rajshahi University of Engineering and TechnologyKajlaRajshahi-6204Bangladesh

This paper describes the usefulness of renewable energy throughout the world to generate power. renewable energy adds a remarkable scope in power system. renewable energy sources act as the prime mover of a microgrid. The Microgrid is a small network of power system with distributed generation (DG) units connected in parallel. The integration challenges of renewable energy sources and the control of microgrid are described in this paper. The varied nature of DG system produces voltage and frequency deviation. The unknown nature of the load produces un-modeled dynamics. This un-modeled dynamic introduces measurable effects on the performance of the microgrid. This paper investigates the performance of the microgrid against different scenarios. The voltage of the microgrid is controlled by using different controllers and their results are also investigated. The performance of controllers is investigated using MATLAB/Simulink SimpowerSystems.

关键词： renewable energy Integral challenges Microgrid Control process Voltage control

relationship between the microstructure and properties of thermomechanically processed Fe-17Mn and Fe-17Mn-3Al steels

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International Journal of Minerals,Metallurgy and Materials 2019年第1期26卷 64-75页

作者： renuprava Dalai Siddhartha das Karabi das Department of Metallurgical and Materials Engineering Indian Institute of Technology

Two austenitic Mn steels(Fe-17 Mn and Fe-17 Mn-3 Al(wt%, so as the follows)) were subjected to thermomechanical processing(TMp) consisting of forging followed by solutionization and hot rolling. The rolled samples were annealed at 650 and 800°C to relieve the internal stress and to induce recrystallization. The application of TMp and heat treatment to the Fe-17 Mn/Fe-17 Mn-3 Al steels refined the austenite grain size from 169 μm in the as-solutionized state to 9–13 μm, resulting in a substantial increase in hardness from HV 213 to HV 410 for the Fe-17 Mn steel and from HV 210 to HV 387 for the Fe-17 Mn-3 Al steel. The elastic modulus values, as evaluated by the nanoindentation technique, increased from(175 ± 11) to(220 ± 12) Gpa and from(163 ± 15) to(205 ± 13) Gpa for the Fe-17 Mn and Fe-17 Mn-3 Al steels, respectively. The impact energy of the thermomechanically processed austenitic Mn steels was lower than that of the steels in their as-solutionized state. The addition of Al to the Fe-17 Mn steel decreased the hardness and elastic modulus but increased the impact energy.

关键词： austenitic manganese steel(AMS) thermomechanical processing(TMp) microstructure property hardness elastic modulus

Effect of size on momentum distribution of electrons around vacancies in NiO nanoparticles

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Chinese physics B 2015年第4期24卷 296-299页

作者： Anjan das Atis Chandra Mandal p.M.G.Nambissan Department of physics A.P.C.Roy Government College Department of physics University of Burdwan Applied Nuclear physics Division Saha Institute of Nuclear Physics

Very small nickel oxide nanoparticles were prepared by a sol-gel procedure using nickel nitrate hexahydrate and ammonium hydroxide as precursors. The particles are in the range of 5 nm-11 rim. The x-ray diffraction （XrD） crystallography and high resolution transmission electron microscopy （HrTEM） were employed to characterize the samples. They were found to be polycrystalline in nature and fcc （NaCl-type） in structure, with the lattice parameter varying with annealing temperature. HrTEM pictures show that the as-prepared samples are hexagonal in shape. positron annihilation spectroscopy was used to investigate the Doppler-broadened spectra of the samples. The S and W parameters revealed that the chemical surroundings and momentum distribution of the vacancy clusters vary with crystallite size.

关键词： nanoparticles semiconductor defect cluster positron annihilation sol-gel