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Plasma Science and Technology 2010年第4期12卷 421-425页

作者： R.S.PANDEY m.singh Pramod kUmAR k.m.singh S.kUmAR Department of Applied Physics Amity School of Science and TechnologyAmity University Noida UP Department of Physics J. L. N. College Chakradharpur Ranchi University Ranch Department of Physics Veer Kunwar Singh University Department of Physics Nalanda college Biharsharif Nalanda MU Bodh Gaya Bihar

VLF （very low frequency） mode instability with parallel AC electric field was studied for generalized loss-cone distribution with an index j, which is reducible to bi-maxwellian, loss- cone and delta function for j = 0, 1 and co. The particle trajectories and dispersion relation are obtained through a kinetic approach and method of characteristic solutions. The calculations are compared with the observations of low frequency waves of Voyager 2. The growth rate of plasma parameters suited to magnetosphere of Uranus is obtained. It is inferred that the magnitude as well as frequency of AC （alternating current） field increases the growth rate and widen the band width significantly. In addition to temperature anisotropy, particles in plasma having generalized loss-cone distribution provide an additional source of energy.

关键词： generation of VLF mode instability in Uranus

Petrographic characteristics and paleoenvironmental history of Eocene lignites of Cambay basin, Western India

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International Journal of Coal Science & Technology 2017年第3期4卷 214-233页

作者： Prakash k. singh Vijay k. singh m. P. singh P. k. Rajak Coal and Organic Petrology Lab Centre of Advanced Study in Geology Banaras Hindu University Varanasi Uttar Pradesh 221005 India

Lignite samples collected from Vastan, Rajpardi and Tadkeshwar lignite mines of Cambay basin （Gujarat） were subjected to organic petrographic investigations and geochemical analyses and the data, thus generated, is used to reconstruct the paleodepositional history of these lignite sequences. The lignites of Cambay basin dominantly comprise huminite maceral group （71.6%-86.3%） followed by liptinite （10.1%-19.3%） and inertinite （3.6%-11.0%） maceral groups. The mineral matter varies from 9.0% to 20.0%. The petrography based facies model indicates that these lignites have high values of gelification index （GI） and low tissue preservation index revealing a continuous wet condition in the basin and a relatively slower rate of subsidence during the decay of organic matter. On several occasions, during the formation of seams in Tadkeshwar, Rajpardi and Vastan mines, the value of GI exceeded 10 which indicates a forest permanently flooded and the cause of pronounced degree of degradation. However, few sections in Tadkeshwar seam had relatively drier spells of environmental conditions due to fluctuation in the water table as revealed by moderately high content of inertinite macerals. This is specially indicated by the occurrence of funginite which normally thrives in the upper oxy- genated peatigenic layer and indicates prevalence of oxic conditions during plant deposition. Such conditions prevailed during a transgressive phase but there were intermittent fluvial activities also giving rise to supratidal flood plain as reflected in the form of associated carbonaceous shales in the basin.

关键词： Cambay basin Western India Lignite maceral Paleodepositional environment

Understanding the paleomires of Eocene lignites of kachchh Basin, Gujarat （Western India）： petrological implications

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International Journal of Coal Science & Technology 2017年第2期4卷 80-101页

作者： Prakash k. singh Vijay k. singh m. P. singh P. k. Rajak Coal and Organic Petrology Lab Centre of Advanced Studyin Geology Banaras Hindu University VaranasiUttar Pradesh 221005 India

The present paper entails the results of the investigations carried out on the lignite deposits of kachchh Basin. The lignite samples were drawn from five lignite seams from Panandhro lignite field （Seam-I to -V） and eight lignite seams （Seam-I to -VIII） from the matanomadh lignite field which are currently operational. The petrographic analysis of the lignites indicates a dominance of huminite group of macerals which is mainly contributed by ulminite-A, ulminite-B, attrinite, densinite, and phlobaphinite. Liptinite （chiefly sporinite, cutinite, resinite, and liptodetrinite） and inertinite （chiefly fusinite, funginite, and inertodetrinite） groups occur in subordinated amount. The mineral matter occurs in moderate concentration. Though sulfur content is high in these lignites, there is no fixed trend of variation of sulfur from bottom seam to top seam. The investigation reveals a flooded forest swamp having high rate of degradation. However, there were a few drier periods indicated by relatively more inertinite macerals. The petrography-based models indicate that the kachchh lignites of Gujarat evolved in coastal marshy setting under transgressive phase. However, there were few intermittent fluvial activities giving rise to supratidal flood plain. This led to the formation of the associated carbonaceous shales in the basin.

关键词： kachchh Basin Eocene lignite Petrography Paleomire

Chatter stability prediction in high-speed micromilling of Ti6Al4 Vvia finite element based microend mill dynamics

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Advances in manufacturing 2018年第1期6卷 95-106页

作者： kundan k. singh Ramesh singh Department of mechanical Engineering Indian Institute of Technology Bombay Powai Mumbai 400076 India

High-speed micromilling （spindle speeds 100 000r/min） can create complex three-dimensional microfeaturesin difficult-to-machine materials. The micromachined sur-face must be of high quatity, to meet functional require-ments. However, chatter-induced dynamic instabilitydeteriorates the surface quality and can be detrimental totool life. Chatter-free machining can be accomplished byidentifying stable process parameters via stability lobe dia-gram. To generate accurate stability lobe diagram, it isessential to determine the microend mill dynamics. Fre-quency response function is required to determine the tool-tip dynamics obtained by experimental impact *** that application of impact load at the microend mill tip（typically 100 - 500 μm） is not feasible as it would invari-ably end with tool failure. Consequently, alternative meth-ods need to be developed to identify the microend milldynamics. In the present work, the frequency responsefunction for the microend mill is obtained by finite elementmethod modal analysis. The frequency response functionobtained from modal analysis has been verified from theexperimentally obtained frequency response function. Theexperimental frequency response function was obtained byimpacting the microend mill near the taper portion with animpact hammer and measuring the vibration of the tool-tipwith a laser displacement sensor. The fundamental fre-quency obtained from finite element method modal analysisshows a difference of 6.6% from the experimental funda-mental frequency. microend mill dynamics obtained fromthe finite element method is used for chatter prediction inhigh-speed micromilling operations. The stability lobe dia-gram predicts the stability boundary accurately at 60 000r/min and 80 000 r/min; however, a slight deviation isobserved at 100 000 r/min.

关键词： Chatter micromilling microend milldynamics Frequency response function Finite elementmodal analysis

Peat swamps at Giral lignite field Western India： understanding the modelling of Barmer basin, Rajasthan, evolution through petrological

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International Journal of Coal Science & Technology 2016年第2期3卷 148-164页

作者： Prakash k. singh P. k. Rajaka m. P. singh V. k. singh A. S. Naik Alok k. singh Coal & Organic Petrology Lab Centre of Advanced Study inGeology Banaras Hindu UniversityVaranasi 221005 Uttar Pradesh India Rajiv Gandhi Institute of Petroleum Technology Rae Bareli 229316 UP India

The lignite samples collected from Giral lignite field of Barmer basin have been subjected to petrological investigation. The data generated has been discussed to understand the evolution of the paleomires of these lignites. The present study reveals that these low rank C coals are chiefly composed of huminite group macerals, mainly telohuminite and detrohuminite, while liptinite and inertinite group macerals occur in subordinate amounts. Not much variation in the maceral composition from Seam-I to Seam-VIII has been observed. Barmer lignites are characterized by a very high GI （〉10） and moderate TPI indicating topogenous mire in the basin which was permanently flooded. The GI and TPI values and the petrography-based facies critical models indicate that these lignites originated mostly under wet forest swamp to clastic marsh having telmatic to limno-telmatic conditions with a moderate rate of subsidence and a very slow fall in ground water table. Further, the GWI and VI values are suggestive of mesotrophic to rheotrophic hydrological conditions having the dominance of herbaceous to marginal aquatic vegetation. There were spells of periodic drowning of peat especially during the formation of Seam-VII. moderately high concentration of calcium in these lignites along with the presence of framboidal pyrite indicate enhanced sulphate-reducing bacterial activity present in carbonate and sulphate-rich waters in the basin during peat formation.

关键词： Peat swamp Petrography - Giral lignite Barmer basin Western India

kinetics of mild Steel Corrosion in Aqueous Acetic Acid Solutions

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Journal of materials Science & Technology 2010年第3期26卷 264-269页

作者： S.k.singh A.k.mukherjee Department of Applied Chemistry Institute of TechnologyBanaras Hindu University Department of Chemistry University of Delhi

The kinetics of mild steel corrosion in aqueous acetic acid solution has been investigated by weight loss and polarization techniques at 25,35 and 45℃.The weight loss of mild steel at room temperature （25℃） has been found to be quite significant,indicating poor corrosion resistance in acetic *** maximum corrosion rate has been observed in 25% acetic acid solution at all three experimental *** decrease in corrosion rate after attaining a maximum value has been attributed to the deposition of corrosion product on the *** polarization curves exhibit active behaviour at each concentration and temperature with a shift towards higher current density region and increased corrosion rates at higher *** cathodic polarization curves are almost identical irrespective either of the concentration of acetic acid or *** results obtained by both the techniques are in good agreement,while the surface studies support the conclusions drawn from the weight loss method.

关键词： Corrosion mild steel Acetic acid

Eocene lignites from Cambay basin, Western India： An excellent source of hydrocarbon

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Geoscience Frontiers 2016年第5期7卷 811-819页

作者： P.k.singh V.k.singh P.k.Rajak m.P.singh A.S.Naik S.V.Raju D.mohanty Coal & Organic Petrology Lab Centre of Advanced Study in Geology Banaras Hindu University Varanasi 221005 Uttar Pradesh India Research & Development Oil India Limited Duliajan Assam 786 602 India Central Institute of mining and Fuel Research Barwa Road Dhanbad 826015 India

In the present paper lignites from the Cambay basin have been studied for their hydrocarbon *** samples were collected from three lignite fieldse Vastan, Rajpardi and Tadkeshwar, and were investigated by petrography, chemical analyses and Rock-Eval pyrolysis. The results are well comparable with the empirically derived values. The study reveals that these ‘low rank C＇ lignites are exceedingly rich in reactive macerals（huminite t liptinite） while inertinite occurs in low concentration. These high volatile lignites generally have low ash yield except in few sections. The Rock-Eval data indicates the dominance of kerogen type-III with a little bit of type-II. The study reveals that the lignites of Vastan（lower and upper seams） and Tadkeshwar upper seam are more gas-prone while Rajpardi and Tadkeshwar lower seams are oil-prone. Further, the fixed hydrocarbons are several times higher than the free hydrocarbons. The relation between TOC and fixed hydrocarbon indicates that these lignites are excellent source rock for hydrocarbon which could be obtained mainly through thermal cracking. The empirically derived values reveal a high conversion（94e96%） and high oil yield（64e66%） for these lignites.

关键词： Eocene lignites Cambay basin Rock-Eval maceral Hydrocarbon

Study of cyanide removal from contaminated water using zinc peroxide nanomaterial

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Journal of Environmental Sciences 2017年第5期29卷 76-85页

作者： Himani Uppal S. Swarupa Tripathy Sneha Chawla Bharti Sharma m.k. Dalai S.P. singh Sukhvir singh Nahar singh CSIR-National Physical Laboratory New Delhi 110012 India Electronic Science Kurukshetra University Kurukshetra Haryana 136119 India Academy of Scientific and Innovative Research (AcSIR) India

The present study highlights the potential application of zinc peroxide （ZnO2） nanomaterial as an efficient material for the decontamination of cyanide from contaminated water. A process patent for ZnO2 synthesis has been granted in United States of America （US Patent number 8,715,612; may 2014）, South Africa, Bangladesh, and India. The ZnO2 nanomaterial was capped with polyvinylpyrrolidone （PVP） to control the particle size. The PVP capped ZnO2 nanomaterial （PVP-ZnO2） before and after adsorption of cyanide was characterized by scanning electron microscope, transmission electron microscope, X-ray diffractorneter, Fourier transform infrared spectroscopy and time of flight-secondary ion mass spectrom- etry. The remaining concentration of cyanide after adsorption by PVP-ZnO2 was determined using ion chromatograph. The adsorption of cyanide over PVP-ZnO2 was also studied as a function of pH, adsorbent dose, time and concentration of cyanide. The maximum removal of cyanide was observed in pH range 5.8-7.8 within 15 rain. The adsorption data was fitted to Langmuir and Fruendlich isotherm and it has been observed that data follows both the isotherms and also follows second order kinetics.

关键词： Cyanide Zinc peroxide Adsorption Ion chromatograph

Stimulated Raman Scattering in a Weakly Polar Ⅲ-Ⅴ Semiconductor： Effect of dc magnetic Field and Free Carrier Concentration

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Chinese Physics Letters 2007年第8期24卷 2245-2248页

作者： m. singh P. Aghamkar P. k. Sen Department of Applied Physics Guru Jambheshwar University of Science and Technology Hisar-125001 India Department of Applied Physics S.G.S. Institute of Technology and Science 23-Park Road Indore-452003 India

Using the hydrodynamic model of semiconductor plasmas, we perform an analytical investigation of stimulated Raman scattering （SITS） of an electromagnetic pump wave in a transversely magnetized weakly polar semicon- ductor arising from electron-density perturbations and molecular vibrations of the medium both produced at the longitudinal optical phonon frequency. Assuming that the origin of SItS lies in the third-order susceptibility of the medium, we investigate the growth rate of Stokes mode. The dependence of stimulated Raman gain on the external dc magnetic field strength and free carrier concentration is reported. The possibility of the occurrence of optical phase conjugation via SItS is also studied. The steady-state Raman gain is found to be greatly enhanced by the presence of the strong external dc magnetic field.

关键词： Stimulated Raman Scattering Weakly Polar Semiconductor

Correlation between microstructure and wear behavior of AZX915 mg-alloy reinforced with 12 wt%TiC particles by stir-casting process

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Journal of magnesium and Alloys 2016年第4期4卷 306-313页

作者： Nagaraj m.Chelliah Harpreet singh m.k.Surappa Department of mechanical Engineering Indian Institute of Technology RoparRupnagar 140001PunjabIndia Department of materials Engineering Indian Institute of ScienceBengaluru 560012KarnatakaIndia

The present work concerns with correlation between microstructure and wear behavior of AZX915 mg-alloy reinforced with 12 wt%of TiC particles by stir-casting *** sliding tests were performed under ambient environment by using a pin-on-disc(EN8 steel)configuration with a normal load of 50 N at a constant sliding speed of 2.50 ms^(−1).While as-cast composite experienced delamination wear,heat treated composite suffered from delamination and oxidation wear during dry sliding ***,the heat treated composite exhibited lower friction and higher wear rate as compared to the as-cast *** and wear behavior were correlated with microstructures based on the concept of oxidation tendency and crack nucleation/***,a schematic model has been proposed illustrating wear mechanisms from the point of view of subsurface microstructural evolution of the AZX915-TiCp composite.

关键词： mg-alloys magnesium matrix composites Heat treatment Delamination Tribo-oxidation