检索结果-南通市图书馆

Role of activation energies of individual phases in two-phase range on constitutive equation of Zr-2.5Nb-0.5Cu alloy

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2017年第1期27卷 172-183页

作者： k.k.SAXENA S.k.JHA V.PANCHOLI g.P.CHAUDHARI D.SRIVASTAVA g.k.dey N.SAIBABA Department of Metallurgical and Materials Engineering Indian Institute of TechnologyRoorkee-247667UttarakhandIndia Nuclear Fuel Complex Limited Hyderabad-501301India Materials Science Division Bhabha Atomic Research CenterMumbai-40085India Department of Mechanical Engineering Insitute of Engineering and TechnologyGLA UinversityMathura-281406Uttar PradeshIndia

Dominant phase during hot deformation in the two-phase region of Zr-2.5Nb-0.5Cu （ZNC） alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on a two-phase ZNC alloy in the temperature range of 700-925 ℃ and strain rate range of 10-2-10 s-l, Flow stress data of the single phase were extrapolated in the two-phase range to calculate flow stress data of individual phases. Activation energies of individual phases were then calculated using calculated flow stress data in the two-phase range, Comparison of activation energies revealed that a phase is the dominant phase （deformation controlling phase） in the two-phase range. Constitutive equations were also developed on the basis of the deformation temperature range （or according to phases present） using a sine-hyperbolic type constitutive equation. The statistical analysis revealed that the constitutive equation developed for a particular phase showed good agreement with the experimental results in terms of correlation coefficient （R） and average absolute relative error （AARE）.

关键词： Zr-2.5Nb-0.5Cu alloy hot deformation activation energy constitutive equation two-phase material

Mechanical properties and microstructural evolution of ultrafine grained zircaloy-4 processed through multiaxial forging at cryogenic temperature

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2015年第7期25卷 2221-2229页

作者： D.FULORIA S.gOEL R.JAYAgANTHAN D.SRIVASTAVA g.k.dey N.SAIBABA Department of Metallurgical and Materials Engineering Centre of Nanotechnology ⅡT Roorkee Materials Science Division Bhabha Atomic Research Center Nuclear Fuel Complex Limited

The mechanical properties and microstructural evolution of zircaloy-4 subjected to cumulative strains of 1.48,2.96,4.44 and 5.91 through multiaxial forging（MAF） at cryogenic temperature（77 k） were *** mechanical properties of the MAF treated alloy were measured through universal tensile testing and Vickers hardness testing *** zircaloy-4 deformed up to a cumulative strain of 5.91 showed improvement in both ultimate tensile strength and hardness from 474 MPa to 717 MPa and from HV 190 to HV 238,respectively,as compared with the as-received ***,there was a noticeable decrement in ductility（from 18%to 3.5%） due to the low strain hardening ability of deformed *** improvement in strength and hardness of the deformed alloy is attributed to the grain size effect and higher dislocation density generated during multiaxial *** microstructural evolutions of deformed samples were characterized by optical microscopy and transmission electron microscopy（TEM）.The evolved microstructure at a cumulative strain of 5.91 obtained after MAF up to 12 cycles depicted the formation of ultrafine grains with an average size of 150-250 nm.

关键词： zircaloy-4 multiaxial forging cryogenic temperature ultrafine-grain microstructural evolution mechanical properties

Few-shot learning for screening 2D ga2CoS4-x supported single-atom catalysts for hydrogen production

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2025年第01期 665-673页

作者： Nabil khossossi Poulumi dey Department of Mechanical Engineering (ME) Delft University of Technology

Hydrogen generation and related energy applications heavily rely on the hydrogen evolution reaction（HER）,which faces challenges of slow kinetics and high *** electrocatalysts,particularly single-atom catalysts （SACs） on two-dimensional （2D） materials,are *** study presents a few-shot machine learning （ML） assisted high-throughput screening of 2D septuple-atomic-layer ga2CoS4-xsupported SACs to predict HER catalytic ***,density functional theory （DFT）calculations showed that 2D ga2CoS4is inactive for ***,defective ga2CoS4-x（x=0–0.25）monolayers exhibit excellent HER activity due to surface sulfur vacancies （SVs）,with predicted overpotentials （0–60 mV） comparable to or lower than commercial Pt/C,which typically exhibits an overpotential of around 50 m V in the acidic electrolyte,when the concentration of surface SV is lower than 8.3%.SVs generate spin-polarized states near the Fermi level,making them effective HER *** demonstrate ML-accelerated HER overpotential predictions for all transition metal SACs on 2D *** DFT data from 18 SACs,an ML model with high prediction accuracy and reduced computation time was *** intrinsic descriptor linking SAC atomic properties to HER overpotential was *** study thus provides a framework for screening SACs on 2D materials,enhancing catalyst design.

关键词：

Chemical Reduction of CO_2 to Different Products during Photo Catalytic Reaction on TiO_2 under Diverse Conditions:an Overview

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Natural gas Chemistry 2007年第3期16卷 217-226页

作者： g.R.dey Radiation and Photochemistry Division Bhabha Atomic Research CentreTrombayMumbai 400085India

The chemical reduction of CO2 remains a challenge with respect to the reversal of the oxidative degradation of any organic materials. The conversion of CO2 into useful substances is essential in developing alternative fuels and various raw materials for different industries. This also aids in preventing the continuous rise in tropospheric temperature due to the green house effect of CO2. In this article an overview of the growth taken place so far in the field of CO2 chemical reduction is pre- sented. The discussion comprises of photochemical methods for the development of different products, viz. CO, CH3OH and CH4, through chemical reduction of CO2. This includes the use of photo catalysts, mainly TiO2, and the role of a hole scavenger （such as 2-propanol） for this purpose.

关键词： CO2 chemical reduction H2 CH4 CO TiO2 hole scavenger photolysis

Approach for C_(1)to C_(2)products commencing from carbon dioxide:A brief review

在线全文

学校读者我要写书评

暂无评论

Petroleum 2024年第3期10卷 373-398页

作者： g.R.dey Radiation and Photochemistry Division Bhabha Atomic Research CentreTrombayMumbai 400085India Homi Bhabha National Institute AnushaktinagarMumbai 400094India

The carbon dioxide(CO_(2))conversion to useable compounds remains a great contest to scientists,engineers,and environmentalists with regard to the reverse of the oxidative degradation of *** conversion is essential for the development of complementary fuels and raw materials for various industries,which in turn will help in avoiding the drastic increase in tropospheric temperature due to greenhouse effect leading to global *** solar energy is the earth's essential power source along with the other various forms of energy for example fossil fuels,hydropower,wind,and biomaterials,*** final goal is to establish the artificial photosynthesis,which can be replicated thru various chemical reduction techniques of CO_(2)by employing appropriate photo-,thermal-and electro-catalysts in order to produce different one carbon atom(C_(1))and higher carbon atoms containing ***,the utilization of clean and sustainable CO_(2)towards high-value products is of great interest today due to the recognized environmental worries and subsequent lessening of the fossil fuels utilization load to meet the energy demand of *** way,solar energy can directly and/or indirectly be altered and stored in chemical energy form for industrial as well as societal *** this article our endeavor is to summarize the advances in CO_(2)chemical reduction research area till date especially in free radical-based methods such as electrochemical,photochemical and plasma chemical for the development of carbon species up to two carbon(C_(2))atoms containing products perceived in the chemical reduction of CO_(2).The author hopes that this piece of work will be helpful to researchers and readers who are focused on the field of CO_(2).

关键词： Photocatalysis Electrocatalysis Plasmolysis Thermolysis Carbon dioxide Chemical reduction

Sulfide oxidation in fluidized bed bioreactor using nylon support material

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2012年第3期24卷 512-519页

作者： Varsha Midha M k Jha Apurba dey Department of Chemical Engineering National Institute of TechnologyJalandhar 144011India Department of Biotechnology National Institute of Technology DurgapurIndia

A continuous fluidized bed bioreactor （FBBR） with nylon support particles was used to treat synthetic sulfide wastewater at different hydraulic retention time of 25, 50 and 75 min and upflow velocity of 14, 17 and 20 m/hr. The effects of upflow velocity, hydraulic retention time and reactor operation time on sulfide oxidation rate were studied using statistical model. Mixed culture obtained from the activated sludge, taken from tannery effluent treatment plant, was used as a source for microorganisms. The diameter and density of the nylon particles were 2-3 mm and 1140 kg/m3, respectively. Experiments were carried out in the reactor at a temperature of （30 ± 2）°C, at a fixed bed height of 16 cm after the formation of biofilm on the surface of support particles. Biofilm thickness reached （42 ± 3） μm after 15 days from reactor start-up. The sulfide oxidation, sulfate and sulfur formation is examined at all hydraulic retention times and upflow velocities. The results indicated that almost 90%-92% sulfide oxidation was achieved at all hydraulic retention times. Statistical model could explain 94% of the variability and analysis of variance showed that upflow velocity and hydraulic retention time slightly affected the sulfide oxidation rate. The highest sulfide oxidation of 92% with 70% sulfur was obtained at hydraulic retention time of 75 min and upflow velocity of 14 m/hr.

关键词： biofilm fluidized bed bioreactor mixed culture sulfide oxidation

Photolysis studies on HCOOH and HCOO^- in presence of TiO_2 photocatalyst as suspension in aqueous medium

在线全文

学校读者我要写书评

暂无评论

Journal of Natural gas Chemistry 2009年第1期18卷 50-54页

作者： g. R. dey k. N. R. Nair k. k. Pushpa Radiation and Photochemistry Division Bhabha Atomic Research Centre Trombay Mumbai 400 085 India

Photolysis studies on formic acid （HCOOH） and formate ion （HCOO-） in presence of TiO2, a photocatalyst, as suspension in water were carried out separately using 350 nm ultraviolet light. The products, such as H2, CO, CO2 and CH4, generated during the experiments were monitored with varying the ambient, light exposure time, and the concentration of HCOOH/HCOO-. The yields of CO in all these systems increased with light exposure time. In aerated systems, CO yields were higher in contrast to the deoxygenated （Ar-purged） systems under identical conditions. It is proposed apparently that the formation of CO is taking place during the chemical reduction of in-situ generated CO2, a photo-mineralized product of HCOOH/HCOO-, but not through the direct photodecomposition or photodehydration （CO＋H2O） of solute molecules. The rates of CO formation during 1.3 M HCOOH photolysis in presence of TiO2 photocatalyst were evaluated to be 0.21 and 0.13 μl/min in aerated and Ar-purged systems, respectively. As compared with HCOOH systems, the CO yields are lower when 0.2 M HCOONa was exposed to light under identical conditions. The CO growth rates were evaluated to be 0.07 and 0.046 μl/min^-1 for aerated and deoxygenated HCOONa systems, respectively; moreover, the trend is quite similar to that of the HCOOH system. Under these conditions, the emission of H2 was also observed, and its yield was significantly higher in Ar-purged system as compared with the CO yields. However, in aerated system, the yields of these products were just opposite. The formation of low yield of methane was observed during photolysis of HCOOH/HCOO ions. In CO2 ambient, the yields of CO and H2 varied drastically with time.

关键词： formic acid formate ion photolysis TiO2

Mineralogy and textural impact on beneficiation of goethitic ore

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2017年第3期27卷 445-450页

作者： dey Shobhana Mohanta Manoj k. Singh Ratnakar Mineral Processing Division CSIR-National Metallurgical Laboratory Jamshedpur 831007 India

The effect of mineralogy and texture on the beneficiation of goethitic ores from two different origins is highlighted. Sample A having 54.47% Fe with 8.57% loss of ignition （LOl） indicates the presence of vitreous and ochreous goethite, martite and microplaty hematite as the major minerals. Sample B contains 56.90% Fe with 14.4% LOI. There is a pisolithic laterite containing vitreous and ochreous goethite, quartz, kaolinitic clay and there is no hematite mineral. The liberated minerals in -150 ＋ 100 μm size class are 74% for Sample A and 37% only for Sample B which shows that the Sample A appears to be more amenable to beneficiate. A concentrate of 46.7% with 63.22% Fe could be recovered from Sample A while subjected to gravity separation followed by wet magnetic separation. The Sample B does not respond to gravity and magnetic separation due to its complex mineralogy. However, calcination of the Sample B followed by magnetic separation gives the encouraging results. Thus, anomalous behaviour of the goethite dominated ores in beneficiation is attributed to the different textural and liberation characteristic.

关键词： Texture Pisolitic Ochreous goethite Vitreous goethite Calcination

Suspended load in flows on erodible bed

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2009年第3期24卷 315-324页

作者： Sujit k. BOSE Subhasish dey Visiting Fellow Department of Civil Engineering Indian Institute of Technology Chair Prof. Department of Civil Engineering Indian Institute of Technology

Steady state suspended-load of sediment transported in flow over erodible beds usually is treated by the advection-diffusion approach, though in recent years, it is being treated as a two-phase flow phenomenon incorporating kinetics of sediment particles. Among the advection-diffusion approaches, Rouse’s equation is the well-known, although a number of researchers in later periods have attempted to improve it by modifying the mixing length concept taking into account other aspects. In this paper, the advection-diffusion approach and associated logarithmic law of flow velocity are revisited. It is concluded from the logarithmic law that the Reynolds shear stress is a linear function of height above the bed, which reduces to bed shear stress in the case of a long horizontal channel. As a consequence, it is shown that the volumetric concentration of sediment is best approximated by the sum of two power laws of height above the bed. An equation is derived for the suspended-load transport rate in terms of elementary functions.

关键词： Sediment transport Fluvial hydraulics Suspended load Open channel flow