检索结果-南通市图书馆

Effect of induced magnetic field on natural convection in vertical concentric annuli

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第2期28卷 315-323页

作者： R.k.singh A.k.singh Department of Mathematics Central University of BiharPatnaIndia Department of Mathematics Banaras Hindu UniversityVaranasiIndia

In the present paper, we have considered the steady fully developed laminar natural convective flow in open ended vertical concentric annuli in the presence of a ra- dial magnetic field. The induced magnetic field produced by the motion of an electrically conducting fluid is taken into account. The transport equations concerned with the con- sidered model are first recast in the non-dimensional form and then unified analytical solutions for the velocity, induced magnetic field and temperature field are obtained for the cases of isothermal and constant heat flux on the inner cylin- der of concentric annuli. The effects of the various phys- ical parameters appearing into the model are demonstrated through graphs and tables. It is found that the magnitude of maximum value of the fluid velocity as well as induced magnetic field is greater in the case of isothermal condition compared with the constant heat flux case when the gap be- tween the cylinders is less or equal to 1.70 times the radius of inner cylinder, while reverse trend occurs when the gap between the cylinders is greater than 1.71 times the radius of inner cylinder. These fields are almost the same when the gap between the cylinders is equal to 1.71 times the radius of inner cylinder for both the cases. It is also found that as the Hartmann number increases, there is a flattening ten- dency for both the velocity and the induced magnetic field. The influence of the induced magnetic field is to increase the velocity profiles.

关键词： Natural convection Isothermal Heat flux Skin-friction Induced magnetic field Magnetohydrody- namics

Reflection of three-dimensional plane waves at the free surface of a rotating triclinic half-space under the context of generalized thermoelasticity

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2021年第9期42卷 1363-1378页

作者： P.singh A.k.singh A.CHATTOPADHYAY Department of Mathematics and Computing Indian Institute of Technology(ISM)Dhanbad-826004JharkhandIndia

The reflection of three-dimensional(3D) plane waves in a highly anisotropic(triclinic) medium under the context of generalized thermoelasticity is studied. The thermoelastic nature of the 3D plane waves in an anisotropic medium is investigated in the perspective of the three-phase-lag(TPL), dual-phase-lag(DPL), Green-Naghdi-III(GNIII), Lord-Shulman(LS), and classical coupled(CL) theories. The reflection coefficients and energy ratios for all the reflected waves are obtained in a mathematical form. The rotational effects on the reflection characteristics of the 3D waves are discussed under the context of generalized thermoelasticity. Comparative analyses for the reflection coefficients of the waves among these generalized thermoelastic theories are performed. The energy ratios for each of the reflected waves establish the energy conservation law in the reflection phenomena of the plane waves. The highly anisotropic materials along with the rotation may have a significant role in the phenomenon of the reflection behavior of the 3D waves. Numerical computations are performed for the graphical representation of the study.

关键词： reflection energy ratio triclinic thermoelasticity rotation three-dimensional(3D)wave

Rayleigh-type wave propagation in incompressible visco-elastic media under initial stress

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2018年第3期39卷 317-334页

作者： P.singh A.CHATTOPADHYAY A.k.singh Department of Applied Mathematics Indian Institute of Technology (ISM)

Propagation of Rayleigh-type surface waves in an incompressible visco-elastic material over incompressible visco-elastic semi-infinite media under the effect of initial stresses is discussed. The dispersion equation is determined to study the effect of differ- ent types of parameters such as inhomogeneity, initial stress, wave number, phase velocity, damping factor, visco-elasticity, and incompressibility on the Rayleigh-type wave prop- agation. It is found that the affecting parameters have a significant effect on the wave propagation. Cardano＇s and Ferrari＇s methods are deployed to estimate the roots of dif- ferential equations associated with layer and semi-infinite media. The MATHEMATICA software is applied to explicate the effect of these parameters graphically.

关键词： Rayleigh-type wave inhomogeneity initial stress visco-elasticity incom-pressible

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

在线全文

学校读者我要写书评

暂无评论

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

kinetics of Mild Steel Corrosion in Aqueous Acetic Acid Solutions

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 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

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

在线全文

学校读者我要写书评

暂无评论

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

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

在线全文

学校读者我要写书评

暂无评论

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

Influence of anthropogenic activities on landslide susceptibility:A case study in Solan district,Himachal Pradesh,India

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2023年第2期20卷 429-447页

作者： Sangeeta S.k.singh Department of Civil Engineering Punjab Engineering CollegeChandigarh 16012India

Landslides in the Himalayan region are primarily controlled by natural parameters,including rainfall,seismic activity,and anthropogenic parameters,such as the construction of large-scale projects like road development,tunneling and hydroelectric power projects and climate *** parameters which are more crucial among these are a matter of scientific study and *** research,taking Solan district,Himachal Pradesh,India,as the study area,aims to assess the impact of anthropogenic activities on landslide susceptibility at a regional *** distribution was characterized into two groups,namely Rainfall-Induced Landslide(RIL)and Human-Induced Landslide(HIL)based on triggering *** data such as slope angle,aspect,profile curvature,distance to drainage,distance to lineament,lithology,distance to road,normalized difference vegetation index(NDVI)and land use land cover(LULC)have been considered for delineating the landslide susceptibility zonation(LSZ)*** effect of anthropogenic activities on landslide occurrences has been examined through the distribution of landslides along national highways and land use land cover changes(LULCC).Two sets of LSZ maps with a LULC of time interval covering five years(2017&2021)were prepared to compare the temporal progression of LULC and landslide susceptibility during the five *** results indicated the significant impact of anthropogenic activities on the landslide *** map of the year 2021 shows that 23%area falls into high and very high susceptible classes and 48%area falls into very low and low susceptibility *** to LSZ map of 2017,high and very high susceptible classes have been increased by 15%,whereas very low and low susceptible classes have been reduced by 7%.The present case study will help to understand the potential driving parameters responsible for HIL and also suggest the inclusion of LULC in landslide susceptibility *** study will demonstrate new

关键词： Landslide Anthropogenic Human-Induced Landslide(HIL) Rainfall-Induced Landslide(RIL)

Study on the Reflection Spectra of One Dimensional Plasma Photonic Crystals Having Exponentially Graded Materials

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2013年第5期15卷 443-447页

作者： S. PRASAD Vivek singh A. k. singh Department of Physics Faculty of Science Banaras Hindu University

The transfer matrix method is used to study the effect of the permittivity profile on the reflectivity of a one dimensional plasma photonic crystal having exponentially graded material. The analysis shows that the proposed structure works as a perfect mirror within a certain frequency range. These frequency ranges can be completely controlled by the permittivity profile of a graded dielectric layer. As expected we observed that these frequency ranges are also controlled by plasma parameters.

关键词： graded dielectric layer plasma photonic crystal reflectivity transfer matrixmethod