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Suspended sediment dynamics in the meltwater of Chhota Shigri glacier, Chandra basin, Lahaul-Spiti valley, India

Journal of Mountain Science 2018年第1期15卷 68-81页

作者： virendra bahadur singh AL.RAMANATHAN School of Environmental Sciences Jawaharlal Nehru University

Present study shows suspended sediment dynamics in the meltwater of Chhota Shigri glacier,Himachal Pradesh,India for different melt seasons during the period *** suspended sediment concentration in the meltwater was found during the month of July 2011,2012 and 2014 constituting to 55.2%,48.3% and 46.9%,*** in 2013,maximum suspended sediment concentration was observed in August accounting for46.1% of the *** the other hand,maximum suspended sediment load was monitored in the month of July 2011,2012 and 2014 constituting 59.5%,63% and 55.7% of the total,*** in2013,maximum suspended sediment load was observed in the month of August accounting for 49.8% of the total suspended sediment *** distribution of suspended sediment concentration(SSC)and suspended sediment load(SSL)in the Chhota Shigri glacier shows higher value of SSC and SSL during the study period 2012 and 2013,which may be due to the presence of high glacial runoff and negative mass balance of the studied area during these time *** diurnal variation has been observed in the SSC of *** correlation was observed between SSC and SSL with *** the other hand,SSC and SSL also showed strong exponential correlation with air temperature of the studied *** yield from the catchment of Chhota Shigri glacier is high during the peak melt season(July and August)and low during the late melt season(September and October).The average value of erosion rate for Chhota Shigri glacier basin during the study period 2011-2014 was calculated to be 1.1mm/yr,which is lower than the average erosion rate of other Himalayan glaciers such as Rakiot,Chorabari and Gangotri glaciers,which may be caused by its geological setting containing high erosion resistant rocks such as granite,granite gneiss and porphyritic granite.

关键词： Suspended sediment concentration Hysteresis Sediment yield Erosion rate Western Himalaya Chhota Shigri glacier

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Seasonal variations and health risk assessment of trace elements in the Badigad River,lesser Himalayas,Nepal

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Acta Geochimica 2023年第4期42卷 689-703页

作者： Ramesh Raj Pant Kiran Bishwakarma Kshitiz Kandel Sudip Poudel Jharana Nepal Bhanu Bhakta Neupane virendra bahadur singh Central Department of Environmental Science Institute of Science and TechnologyTribhuvan UniversityKathmanduNepal University of Chinese Academy of Sciences Beijing 100049China Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing 100101China Central Department of Chemistry Institute of Science and TechnologyTribhuvan UniversityKathmanduNepal Department of Environmental Studies Ram Lal Anand CollegeUniversity of DelhiNew Delhi 110021India

The consumption of contaminated river water can have severe effects on human *** study aims to investigate the trace elements(TEs)content and their health risk assessment in the Badigad River Basin in the lesser Himalayas of *** total,44 water samples were collected from 22 different sites during the pre-monsoon and monsoon seasons,and 25 TEs were *** matrix and principal component analysis(PCA)were used to analyze the potential relationship between the measured TEs and their source ***,the water quality index(WQI),metal index(MI),and cancer index(CI)were *** TEs content in all samples were found to be within the WHO recommended guideline for drinking and domestic *** dominancy order of the TEs was observed as Sr>Ba>Li>Rb>Zn>Cr>Sc>Mn>Ti>Cu>As>Ni>Co>U>V>Pb>Cs>Ga>Y>Tl>Th>Zr>Bi>Cd>*** PCA analysis suggested that TEs could have natural,anthropogenic,and mixed *** WQI indicated that the river water is safe from a human health *** MI suggested that Badigad River can be considered safer for drinking purposes,and the cancer index(CI)showed that all the reported TEs are at low-risk *** findings of this study could be useful for government agencies in developing more sustainable water management policies in the ***,it is suggested that further investigations should be conducted in terms of other hydrogeochemical variables,including major ions,at spatiotemporal levels for the sustainability of the river basin.

关键词： Trace elements Water quality Health risk assessment Multivariate analysis Badigad River

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Endoscopic management of postcholecystectomy biliary leakage

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Hepatobiliary & Pancreatic Diseases International 2010年第4期9卷 409-413页

作者： virendra singh Gurpreet singh Ganga R Verma Rajesh Gupta Departments of Hepatology Postgraduate Institute of Medical Education and Research Departments of Surgery Postgraduate Institute of Medical Education and Research

BACKGROUND: Biliary leak is an uncommon but significant complication following cholecystectomy. Endotherapy is an established method of treatment. However, the optimal intervention is not known. METHOD: Eighty-five patients with postcholecystectomy biliary leaks from July 2000 to March 2009 were retrospectively evaluated. RESULTS: The study population was 20 males and 65 females with a mean age of 42.47 years. Patients presented with abdominal pain (46), jaundice (23), fever (23), abdominal distension (42), or bilious abdominal drain (67). Endoscopic retrograde cholangiopancreatography detected a leak at the cystic duct stump in 45 patients, stricture with middle common bile duct leak in 4, leak from the right hepatic duct in 3, and a ligated common bile duct in 32. Twelve also had bile duct stones. One had a broken T-tube with stones Endotherapy was possible in 53 patients. Three patients with stones, one with a broken T-tube with stones, and 4 with stricture of the common bile duct with a leak were managed with sphincterotomy and stenting. Eight patients with a cystic duct stump leak with stones were managed with sphincterotomy and stone extraction. Three outpatients and 12 inpatients with a cystic duct stump leak were managed with sphincterotomy and stent and sphincterotomy and nasobiliary drain, respectively. Five patients with a cystic duct stump leak were managed with stenting. Sixteen with coagulopathy were managed with only nasobiliary drain (9) or stent (7). Leak closure was achieved in 100% patients Four developed mild pancreatitis which improved with conservative ***: Endoscopic intervention is a safe and effective method of treatment of postcholecystectomy biliary leaks. However, management should be individualized based on factors such as outpatients or inpatients, presence of stone, stricture, ligature, or coagulopathy.

关键词： biliary fistulae endoscopic retrograde cholangiopancreatography sphincterotomy biliary stent nasobiliary drain biliary strictures

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Relationship between species richness,taxonomic distinctness,functional diversity,and local contribution toβdiversity and effects of habitat disturbance in the riparian spider community of the Ganga River,India

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Ecological Processes 2023年第1期12卷 204-216页

作者： Kritish De Amar Paul singh Arkojyoti Sarkar Kritika singh Manju Siliwal virendra Prasad Uniyal Syed Ainul Hussain Wildlife Institute of India ChandrabaniDehradun 248001India Present Address:Department of Life Sciences Sri Sathya Sai University for Human ExcellenceNavanihalOkali PostKamalapurKalaburagiKarnataka 585313India

Background In the riverine riparian ecosystem,particularly in India,the knowledge of the effects of habitat disturbance on taxonomic distinctness,functional diversity,and local contribution toβdiversity(LCBD)of spider community is *** present study examined the relationships between the index of taxonomic distinctness(Δ^(+)),index of variation in taxonomic distinctness(λ^(+)),functional evenness(FEve),functional divergence(FDiv),functional dispersion(FDis),and LCBD of spider community of the Ganga River and the effects of habitat disturbance on these indices.A total of 27 sampling sites were selected along the bank of the Ganga *** on the rating of the disturbance scores,the sites were classified into lowly,moderately,and highly disturbed *** understand the relationships between species richness,Δ^(+),λ^(+),FDis,FDiv,FEve,LCBD,and habitat disturbance score,Pearson’s correlation was calculated,followed by the linear regression *** one-way multivariate analysis of variance was used to find differences in taxonomic distinctness and functional diversity in the different disturbed *** Significant relationships were found betweenλ^(+)andΔ^(+),FDis andΔ^(+),FDis andλ^(+),FDiv and species richness,FEve and species richness,FEve andλ^(+),FEve and habitat disturbance,LCBD and FEve,and LCBD and habitat disturbance.A significant difference was present in the indices of functional diversity between the lowly,moderately,and highly disturbed ***,garbage dump,human settlement,and created embankment influenced the spider community’sλ^(+),FEve,and *** Unrestrained anthropogenic activities exacerbate habitat disturbance by affecting ecological ***,understanding linkages between ecosystem disturbance,taxonomic,functional,andβdiversity can be fundamental to managing and conserving natural *** work highlights the importance of including taxonomic and functional diversity to comprehend the impact of habit

关键词： Habitat disturbance Taxonomic distinctness Functional evenness Functional divergence Functional dispersion Local contribution to beta diversity Spider community Riparian area Ganga River

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Contrast-free air cholangiography-assisted unilateral plastic stenting in malignant hilar biliary obstruction

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Hepatobiliary & Pancreatic Diseases International 2010年第1期9卷 88-92页

作者： virendra singh Gurpreet singh Vikas Gupta Rajesh Gupta Rakesh Kapoor Departments of Hepatology Postgraduate Institute of Medical Education and Research Departments of Surgery Postgraduate Institute of Medical Education and Research Departments of Radiotherapy Postgraduate Institute of Medical Education and Research

BACKGROUND:Endoscopic palliation in malignant hilar biliary obstruction requires endoscopic retrograde cholangiopancreatography (ERCP),whereas contrast injection leads to ***-free metal stenting with or without magnetic resonance cholangiopancreatography (MRCP) has shown encouraging results,but MRCP and metal stents are *** have been no reports on the use of air ***:We prospectively evaluated the role of air cholangiography-assisted unilateral plastic stenting in 10 patients with type Ⅱ malignant hilar biliary obstruction.A retrospectively analysed group of 10 patients treated with contrast-free unilateral metal stenting served as historical ***:Ten patients with unresectable type Ⅱ malignant hilar biliary obstruction were *** cholangiography detected type Ⅱ obstruction in all patients,similar to *** patients underwent unilateral *** endoscopic drainage was achieved in all *** mean patency of the stent was 95.8±17.5 days in the study group and 143.9±115.1 days in the control group (P=0.20).The mean survival was 121.8±41.6 days in the study group and 154.9±122.5 days in the control group (P=0.42).KaplanMeier analysis showed an estimated median survival of 100:95% CI (65.9,134.1) days in the study group and 98:95% CI (84.1,111.9) days in the control group (P=0.62).Cholangitis occurred in none of the patients and there were no 30-day deaths nor major *** cholangiographyassisted unilateral plastic stenting was cheaper than contrastfree unilateral metal ***:Air cholangiography-assisted unilateral plastic stenting is as safe and effective as contrast-free unilateral metal stenting in type Ⅱ malignant hilar biliary obstruction for palliating patients,but it is cheaper.

关键词： air cholangiogram hilar obstruction malignant plastic stent metal stent unilateral

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Rock excavation using surface miners: An overview of some design and operational aspects

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International Journal of Mining Science and Technology 2013年第1期23卷 33-40页

作者： Prakash Amar Murthy Vemavarapu Mallika Sita Ramachandra singh Kalendra bahadur Central Institute of Mining & Fuel Research Dhanbad 826015 India Indian School of Mines Dhanbad 826004 India

Surface miner, a continuous mining machine, is being manufactured in India and abroad owing to enhanced demand of production in various mining industries like coal, limestone, gypsum, bauxite etc. Different types of surface miners are manufactured today based on cutting drum placement and design specifications. Selective mining without drilling and blasting, high production and small size products are some of the prominent attractive features obtained with these moving marvels. This machine can be used with good efficiency in soft to medium hard rock (100-120 MPa). This paper synthesizes the different applications, equipment models, features offered, operating methods, cutting performance assessment models as well as typical production performance of surface miner in coal and limestone mines of India. Engine hour metre reading, diesel and pick consumptions are linearly influenced by production. The emphasis for future research is also brought out.

关键词： Surface miner Cutting performance Compressive strength Operating methods

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Endoscopic management of hilar biliary strictures

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World Journal of Gastrointestinal Endoscopy 2015年第8期7卷 806-813页

作者： Rajiv Ranjan singh virendra singh Departments of Hepatology Post Graduate Institute of Medical Education and Research

Hilar biliary strictures are caused by various benign and malignant conditions. It is difficult to differentiate benign and malignant strictures. Postcholecystectomy benign biliary strictures are frequently encountered. Endoscopic management of these strictures is challenging. An endoscopic method has been advocated that involves placement of increasing number of stents at regular intervals to resolve the stricture. Malignant hilar strictures are mostly unresectable at the time of diagnosis and only palliation is *** palliation is preferred over surgery or radiological intervention. Magnetic resonance cholangiopancreaticography is quite important in the management of these strictures. Metal stents are superior to plastic stents. The opinion is divided over the issue of unilateral or bilateral *** contrast or no contrast technique has been advocated during endoscopic retrograde cholangiopancreatography of these patients. The role of intraluminal brachytherapy, intraductal ablation devices, photodynamic therapy, and endoscopic ultrasound still remains to be defined.

关键词： Biliary strictures Malignant Benign Endoscopy Endoscopic retrograde cholangiopancreatography

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Effects of Boundary Conditions on Postbuckling Strengths of Composite Laminate with Various Shaped Cutouts under In-Plane Shear

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Open Journal of Composite Materials 2013年第2期3卷 38-50页

作者： Dinesh Kumar Shamsher bahadur singh Department of Civil Engineering Birla Institute of Technology and Science (BITS) Pilani India.

Cutouts are often provided in composite structural components for practical reasons. For instance, aircraft components such as wingspar, fuselage and ribs are provided with cutouts for access, inspection, fuel lines and electric lines or to reduce the overall weight. This paper addresses the effect of boundary condition on buckling and postbuckling responses, failure loads, and failure characteristics of composite laminate with various shaped cutouts (i.e., circular, square, diamond, elliptical-vertical and elliptical-horizontal) and having different lay-ups under in-plane shear (positive and negative) load, using finite-element method. The FEM formulation is based on the first order shear deformation theory in conjunction with geometric nonlinearity using von Karman’s assumptions. The 3-D Tsai-Hill criterion is used to predict the failure of a lamina while the onset of delamination is predicted by the interlaminar failure criterion. It is observed that the effect of boundary condition on buckling, first-ply failure and ultimate failure loads of a quasi-isotropic laminate with cutout is more for positive shear load than that for the negative shear load for almost all cutout shapes. It is also noted that under in-plane shear loads postbuckling stiffness of (0/90)4s laminate with circular cutout is maximum, while it is minimum for (45/—45)4s laminate with circular cutout, irrespective of boundary conditions.

关键词： Boundary Conditions Buckling Postbuckling Cutouts Composite Laminate FEM

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Evolution of Weak Shock Waves in Perfectly Conducting Gases

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Applied Mathematics 2011年第5期2卷 653-660页

作者： Lal Pratap singh Dheerendra bahadur singh Subedar Ram 不详

This article aims at studying one dimensional unsteady planar and cylindrically symmetric flow involving shocks under the influence of magnetic field. The method of generalized wavefront expansion (GWE) is employed to derive a coupled system of nonlinear transport equations for the jump of field variables and of its spatial derivatives across the shock, which, in turn determine the evolution of wave amplitude and admit a solution that agrees with the classical decay laws of weak shocks. A closed form solution exhibiting the features of nonlinear steepening of the wave front. A general criterion for a compression wave to steepen into a shock is derived. An analytic expression elucidating how the shock formation distance is influenced by the magnetic field strength is obtained. Also, the effects of geometrical spreading and nonlinear convection on the distortion of the waveform are investigated in the presence of magnetic field.

关键词： Magnetogasdynamic Flow Weak Shock Induced Discontinuity Generalized Wavefrontexpansion (GWE)

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One-Step One Chemical Synthesis Process of Graphene from Rice Husk for Energy Storage Applications

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Graphene 2017年第3期6卷 61-71页

作者： Pushpendra singh Jitendra bahadur Kaushik Pal Centre of Nanotechnology Indian Institute of Technology Roorkee India Department of Mechanical and Industrial Engineering Indian Institute of Technology Roorkee India

Few layer graphene was synthesized using rice husk ash (RHA) and potassium hydroxide (KOH). This methodology demonstrates the utility of RHA as carbon source for graphene synthesis and as a protective barrier against oxidation of parent rice husk and KOH mixture. Oxidation may occur during synthesis process due to high temperature annealing of RHA and KOH mixture. Electrochemical characterization showed decent capacitance value 86 F·g-1 at 500 mV·s-1. XRD and Raman spectroscopy analysis confirmed the presence of graphitic structure. Transmission electron microscopy visually confirmed presence of few layer graphene. Novelty of this synthesis technique can be described as one-pot, one chemical synthesis technique. Use of natural precursor makes this technique highly cost effective for large scale production.

关键词： Rice Husk Graphene Silicon Dioxide Cyclic Voltammetry

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