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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

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

Comparison of wear behaviour of LM13 Al−Si alloy based composites reinforced with synthetic(B_(4)C)and natural(ilmenite)ceramic particles

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Transactions of Nonferrous Metals Society of China 2021年第12期31卷 3613-3625页

作者： Rahul GUpTA tarun NANDA O.p.pANDEY Mechanical Engineering Department Thapar Institute of Engineering and TechnologyPatiala 147004PunjabIndia School of physics and Materials Science Thapar Institute of Engineering and TechnologyPatiala 147004PunjabIndia

Dry sliding wear behaviour of stir-cast aluminium matrix composites(AMCs)containing LM13 alloy as matrix and ceramic particles as reinforcement was *** different ceramic particle reinforcements were used separately:synthetic ceramic particles(B_(4)C),and natural ceramic particles(ilmenite).Optical micrographs showed uniform dispersion of reinforced particles in the matrix *** particles refined the grain size of eutectic silicon and changed its morphology to globular type.B_(4)C reinforced composites(BRCs)showed maximum improvement in hardness of *** reinforced composites(IRCs)showed maximum reduction in coefficient of friction values due to strong matrix−reinforcement interfacial bonding caused by the formation of interfacial *** sliding wear behaviour of composites was significantly improved as compared to base *** low density and high hardness of B_(4)C particles resulted in high dislocation density around filler particles in *** the other hand,the low thermal conductivity of ilmenite particles resulted in early oxidation and formation of a tribo-layer on surface of ***,both types of reinforcements led to the improvement in wear properties of AMCs,though the mechanisms involved were very ***,the low-cost ilmenite particles can be used as alternative fillers to the high-cost B_(4)C particles for processing of wear resistant composites.

关键词： aluminium matrix composites ilmenite boron carbide particle-reinforcement wear test tribolayer XRD analysis SEM−EDS

Coal mining in northeast India： an overview of environmental issues and treatment approaches

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International Journal of Coal Science & Technology 2016年第2期3卷 87-96页

作者： Mayuri Chabukdhara O. p. singh Department of Environmental Biology and Wildlife Sciences Cotton College State University Guwahati Assam 781001India Department of Environmental Studies North Eastern HillUniversity Shillong Meghalaya 793022 India

Northeast India has a good deposit of sub-bituminous tertiary coal. The northeast Indian coals have unusual physico-chemical characteristics such as high sulfur, volatile matter and vitrinite content, and low ash content. In addition, many environmental sensitive organic and mineral bound elements such as Fe, Mg, Bi, AI, V, Cu, Cd, Ni, pb, and Mn etc. remain enriched in these coals. Such characteristics are associated with more severe environmental impacts due to mining and its utilization in coal based industries. Environmental challenges include large scale landscape damage, soil erosion, loss of forest ecosystem and wildlife habitat, air, water and soil pollution. Several physical and chemical methods are reported in literature for the removal of mineral matter, total sulfur and different forms of sulfur from high sulfur coal in northeast India. This paper may help different researchers and stakeholders to understand current state of research in the field. Initiatives may be taken towards sustainable use of coal resources by adopting innovative clean technologies and by implementing effective control measures and regulatory policies.

关键词： Northeast India Sub-bituminous coal Environmental issues Innovative technologies Management andregulatory policies

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

Evaluation of Fujinon intelligent chromo endoscopy-assisted capsule endoscopy in patients with obscure gastroenterology bleeding

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World Journal of Gastroenterology 2011年第41期17卷 4590-4595页

作者： tarun Gupta Mostafa Ibrahim Jacques Deviere André Van Gossum Department of Hepato-Gastroenterology Erasme Hospital-Free University of Brussels

AIM:To investigate the potential benef it of Fujinon in-telligent chromo endoscopy(FICE)-assisted small bowel capsule endoscopy(SBCE)for detection and character-ization of small bowel lesions in patients with obscure gastroenterology bleeding(OGIB).METHODS:The SBCE examinations(pillcam SB2,Giv-en Imaging Ltd)were retrospectively analyzed by two GI fellows(observers)with and without FICE *** was such that a fellow did not assess the same examination with and without FICE *** senior consultant described f indings as p0,p1 and p2 lesions(non-pathological,intermedi-ate bleed potential,high bleed potential),which were considered as reference f *** outcome mea-surements:Inter-observer correlation was calculated using kappa *** and specif icity for p2 lesions was calculated for FICE and white light ***:In 60 patients,the intra-class kappa cor-relations between the observers and reference f indings were 0.88 and 0.92(p2),0.61 and 0.79(p1),for SBCE using FICE and white light,*** 157 le-sions were diagnosed using FICE as compared to 114 with white light SBCE(p = 0.15).For p2 lesions,the sensitivity was 94% vs 97% and specif icity was 95% vs 96% for FICE and white light,***(p2 le-sions)out of 55 arterio-venous malformations could be better characterized by FICE as compared to white light *** more p0 lesions were diagnosed when FICE was used as compared to white light(39 vs 8,p pathological ***,some vascular le-sions could be more accurately characterized with FICE as compared to white light SBCE.

关键词： Endoscopy Video-capsule Small bowel Obscure gastrointestinal bleeding Arterio-venous malformation Fujinon intelligent chromo endoscopy

One Step Synthesis and Growth Mechanism of Carbon Nanotubes

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Journal of Materials Science & Technology 2014年第2期30卷 112-116页

作者： Akshay Kumar K.singh O.p.pandey Sri Guru Granth Sahib World University School of physics and Materials Science Thapar University

A simple one step, reproducible, synthesis route for carbon nanotubes was proposed. No external catalyst was used for the synthesis. These nanotubes were obtained after decomposition of acetone at 650 ℃ in a specially designed autoclave. The pressure generated due to decomposition of acetone played a vital role in the synthesis. The X-ray diffraction pattern and transmission electron microscopy of the sample showed that the diameter of nanotubes is in the range of 3-14 nm. The thermo gravimetric analysis showed 3% weight loss below 500 ℃; the content of amorphous carbon is very less. The growth mechanism of CNTs was also proposed in the present paper.

关键词： Nanostructures Chemical synthesis Electron diffraction Raman spectroscopy Defects

Enhancement of Second- and Third-Order Nonlinear Optical Susceptibilities in Magnetized Semiconductors

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Chinese physics Letters 2008年第9期25卷 3276-3279页

作者： M. singh p. Aghamkar S. Duhan Department of Applied Sciences P.D.M. College of Engineering Bahadurgarh-124507 India Department of Applied physics G.J. University of Science and Technology Hisar-125001 India Department of physics Chaudhary Devi Lal University Sirsa-125055 India

Using electromagnetic treatment, an expression of effective nonlinear optical susceptibility χe [= χe^（2）＋ χe^（3） E] is obtained for Ⅲ-Ⅴ semiconducting crystals in an applied transverse dc magnetic fieM under off-resonant transition regime. The origin of nonlinear interaction lies in nonlinear polarization arising from the crystal properties such as piezoelectricity and electrostriction. Numerical estimates have been made by a representative n-InSb crystal at 77K duly irradiated by a pulsed 10.6-μm CO2 laser under off-resonant transition regime. Efforts are dedicated to optimizing doping level and externally applied dc magnetic field to achieve maximum χe^（2） and χ3^（3）. The results are found to be in good agreement with the available literature. The analysis shows that χe^（2） and χe^（3） can be significantly enhanced in doped Ⅲ-Ⅴ semiconductors by the proper selection of doping concentration and dc magnetic field, which confirms its potential as a candidate material for the fabrication of nonlinear optical devices.

关键词： the power-law exponents precipitation durative abrupt precipitation change

Influence of slope position and aspect on the vegetation attributes and treewater relations in forests of the central Himalayas

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Journal of Mountain Science 2023年第9期20卷 2592-2602页

作者： Vidit TYAGI Surendra p.singh Ripu Daman singh Surabhi GUMBER Rajesh THADANI Rajiv pANDEY Dolphin(pG)Institute of Bio-medical and Natural Sciences Dehra Dun 248007India Central Himalayan Environment Association(CHEA) Dehradun 248007India Department of Forestry and Environmental Science DSB CampusKumaun UniversityNainital 263001India Centre for Ecology Development and Research(CEDAR) A-17 Mayfair GardensNew Delhi 110016India Indian Council of Forestry Research and Education(ICFRE) Dehra Dun 248007India

While the need for understanding the effects of topographical factors on forest structure and function is well recognized,comprehensive studies are *** study evaluates the effect of slope aspect and slope position on water relations and forest attributes across six forest types occurring between 400 m and 2600 m altitude in the Central Himalaya(27°-38°N).We found that predawn tree water potential and soil water potential were generally higher on moist north slope aspect(-0.78±0.05 Mpa and-3.34±0.18 Mpa,respectively)than dry south slope aspect(-0.82±0.18 Mpa and-3.77±0.18 Mpa,respectively).Across six different forests,these values were higher at hill base(-0.71±0.06 Mpa and-2.77±0.19 Mpa,tree predawn water potential and soil water potential,respectively)than other topographical *** favorable effect of north aspect and hill base was also observed in maintaining soil water and tree water potential during the dry *** attributes,such as species richness,unique species and plant density were also generally higher on north slope and hill base than southern aspect and lowest at hill *** forest types,the hill base provided shelter to 46 unique species,compared to 16-18 at the other positions,thus emphasizing its importance as refugia for species to survive climate change induced *** favorable conditions of hill base position not only contribute to increase in alpha diversity,but also to extended species distributional range.

关键词： Hill base Himalaya Refugia Unique species Water relation

Numerical analysis of surface subsidence in asymmetric parallel highway tunnels

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 170-179页

作者： Ratan Das p.K.singh Ashutosh Kainthola Suman panthee T.N.singh Department of Earth Sciences Indian Institute of Technology Bombay Department of Civil Engineering National Institute of Technology Central Department of Geology Tribhuvan University

Tunnelling related hazards are very common in the Himalayan terrain and a number of such instances have been reported. Several twin tunnels are being planned for transportation purposes which will require good understanding for prediction of tunnel deformation and surface settlement during the engineering life of the structure. The deformational behaviour, design of sequential excavation and support of any jointed rock mass are challenging during underground construction. We have raised several commonly assumed issues while performing stability analysis of underground opening at shallow depth. For this purpose, Kainchi-mod Nerchowck twin tunnels(Himachal pradesh, India) are taken for in-depth analysis of the stability of two asymmetric tunnels to address the influence of topography, twin tunnel dimension and geometry. The host rock encountered during excavation is composed mainly of moderately to highly jointed grey sandstone, maroon sandstone and siltstones. In contrast to equidimensional tunnels where the maximum subsidence is observed vertically above the centreline of the tunnel, the result from the present study shows shifting of the maximum subsidence away from the tunnel centreline. The maximum subsidence of 0.99 mm is observed at 4.54 m left to the escape tunnel centreline whereas the maximum subsidence of 3.14 mm is observed at 8.89 m right to the main tunnel centreline. This shifting clearly indicates the influence of undulating topography and inequidimensional noncircular tunnel.

关键词： Twin tunnels Numerical analysis Stability Finite element method(FEM) Subsidence