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

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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

Ruddlesden-Popper phase A2BO4 oxides:Recent studies on structure,electrical,dielectric,and optical properties

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作者： Ajay k.singh原

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Journal of Advanced Ceramics 2020年第2期9卷 129-148页

作者： Gurudeo NIRALA dharmendra YADAV Shail UPADHYAY Department of Physics Indian Institute of Technology(BHU)Varanasi-221005India

In the last two decades,structure and properties of Ruddlesden–Popper phase(RP)A2BO4 oxides with k2NiF4 structure,have been widely *** to the best of our knowledge,no review article is available in the literature on recent studies on these ***,in this article,recent studies on structure,electrical,dielectric,and optical properties of these oxides have been *** attention is put on to highlight the effect of doping and oxygen stoichiometry on the structure and properties of these ***,important applications of these oxides have also been mentioned in this article.

关键词： Ruddlesden-Popper(RP)phase A2BO4 oxides electrical conductivity dielectric

RSS-Based Selective Clustering Technique Using Master Node for WSN

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Computers, Materials & Continua 2021年第12期69卷 3917-3930页

作者： Vikram Rajpoot Vivek Tiwari Akash Saxena Prashant Chaturvedi dharmendra singh Rajput Mohammed Alkahtani Mustufa Haider Abidi GLA University MathuraIndia DPSM IIIT Naya RaipurIndia Compucom Institute of Technology&Management JaipurIndia Lakshmi Narain College of Technology BhopalIndia Vellore Institute of Technology Vellore632014India Industrial Engineering Department College of EngineeringKing Saud UniversityRiyadh11421Saudi Arabia Raytheon Chair for Systems Engineering Advanced Manufacturing InstituteKing Saud UniversityRiyadh11421Saudi Arabia

Wireless sensor networks(WSN)are designed to monitor the physical properties of the target *** received signal strength(RSS)plays a significant role in reducing sensor node power consumption during data *** utilization of RSS values with clustering is required to harvest the energy of each network node to prolong the network life *** paper introduces the RSS-based energy-efficient selective clustering technique using a master node(RESCM)to improve energy utilization using a master *** master node positioned at the center of the network area and base station(BS)is placed outside the network *** cluster head(CH)selection,the node with a high RSS value is more likely to become *** network is divided into segments according to the distance from the master *** nodes near BS or master node transmit their data using direct transmission without the clustering *** simulation results showed that the RESCM method improves the total network lifespan effectively.

关键词： Wireless sensor network received signal strength clustering base station master node

Micronization enhanced extractability of polyphenols and anthocyanins in tart cherry puree

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Food Bioscience 2022年第6期50卷 676-684页

作者： Nishtha Lukhmana Fanbin kong Rakesh k.singh Department of Food Science and Technology The University of Georgia100 Cedar StreetAthensGA30602-2610USA

Tart cherries(Prunus cerasus L.)are the richest in phenolic compounds,among all the members of drupe family of *** reduce the inherent sourness of the cherries,thermal processing or filtration steps are *** processes lead to changes in pH,and exposure to temperature enhances oxidation leading to degradation of *** the present study,Megatron®and high-pressure homogenization(HPH)were employed to produce micronized puree,which was analyzed for polyphenolic,flavonoid and anthocyanin contents using various *** methods of micronization lead to breakage of cell wall structure facilitating enhanced release of bioactives from the cellular matrix and thus higher antioxidant *** presence of functional groups was corroborated by FTIR spectrophotometric analysis,and reversed phase HPLC for the presence and relative amounts of various polyphenols and *** was a significant increase(p<0.05)of in the extractability of polyphenols with HPH(285.05 GAEμg/g)in comparison with the non-micronized samples(166.80 GAEμg/g).The changes in anthocyanins and flavonoids were also significant(p<0.05),thus confirming the impact of micronization on the antioxidant release in tart cherries.

关键词： Particle size Antioxidants Polyphenols High-pressure homogenization Bioaccessibility

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

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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

The Limit of Rotational Energy Transfer in Atom-Diatom Collision and the Hard Ellipsoid Potential Model

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Journal of Chemistry and Chemical Engineering 2014年第2期8卷 180-186页

作者： dharmendra singh Flrozla Department of Physics Govt. P.G. College Rampura Neemuch 458441 lndia

The limit of rotational energy transfer in atom-diatomic systems due to inelastic collision was investigated over the wide range of collision energy, reduced mass and potential parameters of F2-He system. The IICS （integral inelastic cross-sections） is obtained by the IOSAM （infinite order sudden approximation method） and predicted by PG （power-gap） law in the variation of cross-sections. The investigation provided that the classical limit of angular momentum transfer is given by hard ellipsoid potential is meaningful even the cross-sections computed on the real potential, provided the classical turning point on the surface of soft potential is assumed as hard potential surface.

关键词： Diatomic collision with inert gas atom inelastic scattering rotational energy transfer.

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

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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

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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