检索结果-南通市图书馆

Seasonal Inhomogeneity of Soot Particles over the Central Indo-Gangetic Plains,India:Influence of Meteorology

Journal of Meteorological research 2015年第6期29卷 935-949页

作者： singh B.P. TIWArI S. HOPkE Philip k. singh r.S. BISHT D.S. SrIVASTAVA A.k. singh r.k. DUMkA U.C. singh A.k. rAI B.N. SrIVASTAVA Manoj k. Department of Geophysics Banaras Hindu University Indian Institute of Tropical Meteorology(New Delhi Branch) Clarkson University Department of Chemical Engineering Banaras Hindu University Aryabhatta research Institute of Observational Sciences Department of Physics Banaras Hindu University

Black carbon（BC） particles play a unique and important role in earth’s climate *** was measured（in-situ） in the central part of the Indo-Gangetic Plains（IGP） at Varanasi,which is a highly populated and polluted region due to its topography and extensive emission *** annual mean BC mass concentration was 8.92 ± 7.0 μg m-3,with 34%of samples exceeding the average ***,BC was highest during the post-monsoon and winter periods（approximately 18 μg m-3） and lower in the premonsoon/monsoon seasons（approximately 6 μg m-3）.The highest frequency（approximately 46%） observed for BC mass was in the interval from 5 to 10 μg ***,during the post-monsoon season,the most common values（approximately 23%） were between 20 and 25 μg *** nighttime concentrations of BC were approximately twice as much as the daytime values because of lower boundary layer heights at *** Angstrom exponent was significantly positively correlated（0.55） with ground-level BC concentrations,indicating the impact of BC on the columnar aerosol *** estimated mean absorption Angstrom exponent was 1.02 ± 0.08 μg m-3,indicating that the major source of BC was from fossil fuel *** negative correlations between BC mass and meteorological parameters indicate a pronounced effect of atmospheric dynamics on the BC mass in this *** highest mean BC mass concentration（18.1 ± 6.9 μg m-3） as a function of wind speed was under calm wind conditions（38%of the time）.

关键词： black carbon Indo-Gangetic Plains absorption Angstr(o|¨)m exponent biomass fossil fuel

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Plant Species Diversity along an Altitudinal Gradient of Bhabha Valley in Western Himalaya

引用

Journal of Mountain Science 2008年第2期5卷 157-177页

作者： Amit Chawla S.rajkumar k.N.singh Brij Lal r.D.singh A.k.Thukral Bioresource Development Unit Institute of Himalayan Bioresource Technology (CSIR) Palampur Himachal Pradesh-176 061 India Department of Botanical & Environmental Sciences Guru Nanak Dev University Amritsar-143 005 India

The present study highlights the rich species diversity of higher plants in the Bhabha Valley of western Himalaya in India. The analysis of species diversity revealed that a total of 313 species of higher plants inhabit the valley with a characteristic of moist alpine shrub vegetation. The herbaceous life forms dominate and increase with increasing altitude. The major representations are from the families Asteraceae, rosaceae, Lamiaceae and Poaceae, suggesting thereby the alpine meadow nature of the study area. The effect of altitude on species diversity displays a hump-shaped curve which may be attributed to increase in habitat diversity at the median ranges and relatively less habitat diversity at higher altitudes. The anthropogenic pressure at lower altitudes results in low plant diversity towards the bottom of the valley with most of the species being exotic in nature. Though the plant diversity is less at higher altitudinal ranges, the uniqueness is relatively high with high species replacement rates. More than 90 % of variability in the species diversity could be explained using appropriate quantitative and statistical analysis along the altitudinal gradient. The valley harbours 18 threatened and 41 endemic species, most of which occur at higher altitudinal gradients due to habitat specificity.

关键词： Plant species diversity threatened species altitudinal gradient flora Bhabha Valley western Himalaya India

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

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

引用

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

来源：

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

Generation of VLF Mode Instability by Generalized Distribution Function in the Presence of Parallel AC Electric Field in Uranus

引用

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

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Catalytic performances of kaoline and silica alumina in the thermal degradation of polypropylene

引用

燃料化学学报 2011年第3期39卷 198-202页

作者： Achyut k Panda r.k.singh National Institute of Technology rourkela Orissa Centurion Institute of Technology Bhubaneswar Orissa

Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃～550℃ in order to obtain suitable liquid *** dependencies between process temperatures,types of catalyst,feed compositions and product yields of the obtained fuel fractions were *** was observed that up to 450℃ thermal cracking temperature,the major product of pyrolysis was liquid oil and the major product at other higher temperatures(475℃～550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃.Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid *** the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid *** alumina was found better as compared to kaoline in liquid yield and in reducing the reaction *** maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% *** the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.

关键词： polypropylene pyrolysis silica alumina kaoline engine fuel

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

kinetics of Mild Steel Corrosion in Aqueous Acetic Acid Solutions

引用

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

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Properties of Ternary One Dimensional Plasma Photomic Crystals for an Obliquely Incident Electromagnetic Wave Considering the Effect of Collisions in Plasma Layers

引用

Plasma Science and Technology 2012年第12期14卷 1084-1090页

作者： S. PrASAD Vivek singh A. k. singh Department of Physics Faculty of ScienceBanaras Hindu University

An analytical study is presented on the modal dispersion characteristics, group velocity, and effective group, as well as the phase index of a ternary one dimensional plasma photonic crystal for an obliquely incident electromagnetic wave considering the effect of collisions in plasma layers. The dispersion relation is derived by using the transfer matrix method and the boundary conditions based on electromagnetic theory. The dispersion curves are plotted for both the normal photonic band gap structure and the absorption photonic band gap structure. It is found that the increase in the angle of incidence shifts the photonic band gap toward higher frequencies. Also, the cutoff frequency is independent of collisions.

关键词： ternary plasma photonic crystal dispersion curves group and phase velocities,obliquely incident collision effect

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Diagenesis,facies and palaeocurrent analysis of Upper rewa Sandstone around Sagar,Central India

引用

Journal of Palaeogeography 2023年第4期12卷 546-563页

作者： Gaurav k.singh Ashish k.rai Arvind k.singh Department of Applied Geology Dr.Harisingh Gour VishwavidyalayaSagar 470003Madhya PradeshIndia Geological Survey of India ShillongIndia

The stratigraphic surface represented by a major contact between the Archean Bundelkhand Granite and the extensive Proterozoic Vindhyan sediments is a regional basement cover *** crystalline—sedimentary interface reflects an intense weathering of continental crust during marine *** time-transgressive sand deposition events ***,rewa and Bhander are mainly witnessed during the entire Vindhyan ***,the Upper rewa Sandstone comprises one of these events in the Vindhyan *** progress has been made in interpreting these sandstones as a function of entirely marine process to a combination of tidal—fluvio—eolian *** the results have so far been attained on the basis of sedimentary facies,provenance,palaeocurrent analysis,and some of petrography.A distinct differentiation between marine and fluvial components of the Upper rewa Sandstone still remains ***,we use diagenesis as a parameter for the first time along with facies and palaeocurrent analysis to acquire a clear comprehension of marine-and fluvial-dominated *** present study spans 27 square kilometer area covering 15 stratigraphic sections with a collection of 571directional data from the facies specific sedimentary structures,and 28 samples obtained for the thin section *** lower unit of the Upper rewa Sandstone shows facies association typical of tidal environment,along with polymodal *** rocks are well sorted and dominantly lithified by authigenic *** development of a complex of syntaxial,passive pore fills,and grain replacive cements reflect normally pressured nature of the lower unit *** upper unit of the Upper rewa Sandstone however,reveals a facies pattern resembling fluvial processes and unimodal palaeocurrent *** exhibit poor sorting,siliceous,and ferruginous matrix,and development of intense ***,pressure solution is a dominant mode of l

关键词： Palaeocurrent Diagenesis Facies Upper rewa Sandstone Vindhyan Basin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Nonlinear mixing-based terahertz emission in inclined rippled density plasmas

引用

Chinese Physics B 2023年第6期32卷 384-390页

作者： k Gopal A P singh S Divya rajdhani College Department of Physics&ElectronicsUniversity of DelhiNew DelhiIndia Computational Plasma Dynamics Laboratory Rajdhani CollegeDepartment of Physics&ElectronicsUniversity of DelhiNew DelhiIndia

We propose to investigate the THz field generation using nonlinear mixing mechanism of laser beat wave with inclined rippled density *** laser pulses with frequencies(ω_(1),ω_(2)) and wave vectors(k_(1),k_(2)) co-propagate and resultant laser beat wave forms at beat frequency(ω_(1)-ω_(2)).Laser beat wave imparts a nonlinear force on the ambient electrons and pushes them outward with nonlinear velocity v_(NL).Coupling of induced density perturbation and nonlinear velocity v_(NL)generates nonlinear currents at laser beat frequency that further generates electromagnetic field E_((ω_(1)-ω_(2))) in terahertz(THz)*** the present scheme,density ripples are introduced at an angle with respect to laser propagation and flat Gaussian index(f) is introduced in laser field profile that transform curved top of Gaussian field envelope into flat top field *** combined effect of flat laser pulses with inclined density ripples in plasmas shows 10-fold enhancement in THz field amplitude when flat-Gaussian index(f) varies from 1 to ***,the THz field intensifies when density ripples inclination increases upto a certain angle and then decreases.

关键词： terahertz inclined ripple flat laser laser plasma interaction

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Optimization of process for the production of bio-oil from eucalyptus wood

引用

燃料化学学报 2010年第2期38卷 162-167页

作者： Gaurav kUMAr Achyut k PANDA r.k.singh National Institute of Technology Rourkela Orissa PIN： 769008 India Jagannath Institute for Technology and Management Parlakhemundi Orissa India

The pyrolysis of eucalyptus wood was carried out in a batch reactor to optimize the yield of *** of various parameters like feed(particle) size,temperature,presence of catalyst and heating rate on the yield of bio-oil was *** optimum conditions for high yield of bio-oil are for the particle size 2 mm^5 mm(average l/d=12.84/2.03 mm) at 450 ℃ in high heating *** reaction kinetics and the quality of bio-oil produced are independent of the presence of different catalysts like mordenite,kaoline clay,fly ash and silica *** physical properties like odour,colour,PH,viscosity,heating value were *** FT-Ir analysis of bio-oil indicates the presence of different functional groups such as monomeric alcohol,phenol,ketones,aldehydes,carboxylic acid,amines,and nitro *** composition of the bio-oil at different conditions was analyzed using GC-MS and found that the components are temperature dependent but independent of catalysts used.

关键词：热反应晶体结构生物能源

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：