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Applied Mathematics and Mechanics(English Edition) 2020年第11期41卷 1651-1670页

作者： R.Kumar R.Kumar S.A.SHEHZAD A.J.CHAMKHA Department of Mathematics Central University of Himachal PradeshDharamshala 273001India Department of Mathematics COMSATS University IslamabadSahiwal 57000Pakistan Institute of research and Development Duy Tan UniversityDa Nang 550000Vietnam Institute of Theoretical and Applied research(ITAr) Duy Tan UniversityHanoi 100000Vietnam

A comparative three-dimensional(3D)analysis for Casson-nanofluid and Carreau-nanofluid flows due to a flat body in a magnetohydrodynamic(MHD)stratified environment is presented.Flow is estimated to be suspended in a Darcy-Forchheimer medium.Soret and Dufour responses are also accommodated in the flow field.A moving(rotating)coordinate system is exercised to examine the bidirectionally stretched flow fields(flow,heat transfer,and mass transfer).Nanofluid is compounded by taking ethylene glycol/sodium alginate as base fluid and ferric-oxide(Fe3O4)as nanoparticles.Governing equations are handled by the application of optimal homotopy asymptotic method(OHAM),where convergence parameters are optimized through the classical least square procedure.The novel mechanism(hidden physics)due to appearing parameters is explored with the assistance of tabular and graphical expositions.Outcomes reveal the double behavior state for temperature field with thermal stratification/Dufour number,and for concentration field with Soret number due to the presence of turning points.

关键词： thermal-solutal stratification Soret-Dufour effect Casson-Carreau nanofluid model porous matrix

Deep Neural Network Driven Automated Underwater Object Detection

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Computers, Materials & Continua 2022年第3期70卷 5251-5267页

作者： Ajisha Mathias Samiappan Dhanalakshmi R.Kumar r.Narayanamoorthi Department of Electronics and Communication Engineering SRMInstitute of Science and TechnologyKattankulathurChennai603203India Department of Electrical and Electronics Engineering SRMInstitute of Science and TechnologyKattankulathurChennai603203India

Object recognition and computer vision techniques for automated object identification are attracting marine biologist’s interest as a quicker and easier tool for estimating the fish abundance in marine environments.However,the biggest problem posed by unrestricted aquatic imaging is low luminance,turbidity,background ambiguity,and context camouflage,which make traditional approaches rely on their efficiency due to inaccurate detection or elevated false-positive rates.To address these challenges,we suggest a systemic approach to merge visual features and Gaussian mixture models with You Only Look Once(YOLOv3)deep network,a coherent strategy for recognizing fish in challenging underwater images.As an image restoration phase,pre-processing based on diffraction correction is primarily applied to frames.The YOLOv3 based object recognition system is used to identify fish occurrences.The objects in the background that are camouflaged are often overlooked by the YOLOv3 model.A proposed Bi-dimensional Empirical Mode Decomposition(BEMD)algorithm,adapted by Gaussian mixture models,and integrating the results of YOLOv3 improves detection efficiency of the proposed automated underwater object detection method.The proposed approach was tested on four challenging video datasets,the Life Cross Language Evaluation Forum(CLEF)benchmark from the F4K data repository,the University of Western Australia(UWA)dataset,the bubble vision dataset and theDeepFish dataset.The accuracy for fish identification is 98.5 percent,96.77 percent,97.99 percent and 95.3 percent respectively for the various datasets which demonstrate the feasibility of our proposed automated underwater object detection method.

关键词： Underwater images diffraction correction marine object recognition gaussian mixture model image restoration YOLO

应用响应曲面法优化摩擦焊接Ti-6Al-4V和SS304L工艺参数（英文）

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Transactions of Nonferrous Metals Society of China 2015年第11期25卷 3625-3633页

作者： R.Kumar M.BALASUBrAMANIAN Department of Mechanical Engineering SKP Institute of Technology rMK College of Engineering and Technology

提出了摩擦焊接过程中近优化设置工艺参数。基于不同的输入参数,如摩擦压力、摩擦时间、顶锻压力和顶锻时间及输出参数,如拉伸强度、硬度和材料损耗,成功获得摩擦焊接工艺。采用夹层技术,通过摩擦焊接工艺,连接Ti-6Al-4V和SS304L。采用... 详细信息

提出了摩擦焊接过程中近优化设置工艺参数。基于不同的输入参数,如摩擦压力、摩擦时间、顶锻压力和顶锻时间及输出参数,如拉伸强度、硬度和材料损耗,成功获得摩擦焊接工艺。采用夹层技术,通过摩擦焊接工艺,连接Ti-6Al-4V和SS304L。采用响应曲面法和Box-Behnken设计确定实验次数并证实优化工艺参数,以得到更好的接头强度。结果很令人满意。在摩擦压力为12 N/mm^2、顶锻压力为40 N/mm^2、摩擦时间为1.2 s、定锻时间为7 s的条件下,得到接头强度为523 MPa。

关键词：摩擦焊接焊接参数 Ti-6Al-4V SS304L 铜夹层

Natural Convection of Fe_3O_4-Ethylene Glycol Nanofluid under the Impact of Electric Field in a Porous Enclosure

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Communications in Theoretical Physics 2018年第6期69卷 667-675页

作者： M.Sheikholeslami S.A.Shehzad R.Kumar Department of Mechanical Engineering Babol Noshirvani University of Technology Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Central University of Himachal Pardesh

Free convection of Fe_3O_4-Ethylene glycol nanofluid in existence of Coulomb forces is studied. Effect of thermal radiation is taken into account. Properties of nanofluid are varied with supplied voltage and shape of nanoparticles. The bottom wall is considered as positive electrode. Control Volume based Finite Element Method is used to obtain the results, which are the roles of Darcy number(Da), radiation parameter(rd), rayleigh number(ra), nanofluid volume fraction(φ), and supplied voltage(?φ). results indicate that Nusselt number is an enhancing function of supplied voltage and Darcy number. Maximum values for temperature gradient are occurred for platelet shape nanoparticles.

关键词：乙二醇 Fe3O4 乙烯对流传送电场围场多孔

Experimental investigation of Tie6Ale4V titanium alloy and 304L stainless steel friction welded with copper interlayer

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Defence Technology（防务技术） 2015年第1期11卷 65-75页

作者： R.Kumar M.BALASUBrAMANIAN Mechanical Engineering SKP Institute of Technology rMK College of Engineering and Technology

The basic principle of friction welding is intermetallic bonding at the stage of super plasticity attained with self-generating heat due to friction and finishing at upset pressure. Now the dissimilar metal joints are especially popular in defense, aerospace, automobile, bio-medical,refinery and nuclear engineerings. In friction welding, some special alloys with dual phase are not joined successfully due to poor bonding strength. The alloy surfaces after bonding also have metallurgical changes in the line of interfacing. The reported research work in this area is scanty. Although the sound weld zone of direct bonding between Tie6Ale4 V and SS304 L was obtained though many trials, the joint was not successful. In this paper, the friction welding characteristics between Tie6Ale4 V and SS304 L into which pure oxygen free copper(OFC) was introduced as interlayer were investigated. Boxe Behnken design was used to minimize the number of experiments to be performed. The weld joint was analyzed for its mechanical strength. The highest tensile strength between Tie6Ale4 V and SS304 L between which pure copper was used as insert metal was acquired. Micro-structural analysis and elemental analysis were carried out by EDS, and the formation of intermetallic compound at the interface was identified by XrD analysis.

关键词： Friction welding Tie6Ale4V SS304L Oxygen free copper Interlayer Microstructure Interface

Feeder and post Deccan Trap dyke activities in the northern slope of the Satpura Mountain： Evidence from new 40Ar-39Ar ages

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Geoscience Frontiers 2017年第3期8卷 483-492页

作者： J.P.Shrivastava R.Kumar N.rani Department of Geology University of Delhi

We present new 40Ar-39Ar plagioclase crystallization ages from the dykes exposed at the northern slope of the Satpura Mountain range near Betul-Jabalpur-Pachmarhi area, - 800 km NE of the Western Ghats escarpment. Among the two plateau ages, the first age of 66.56 ± 0.42 Ma from a dyke near Mohpani village represents its crystallization age which is either slightly older or contemporaneous with the nearby Mandla lava flows （63-65 Ma）. We suggest that the Mohpani dyke might be one of the feeders for the surrounding lava flows as these lavas are significantly younger than the majority of the main Deccan lavas of the Western Ghats （66.38-65.54 Ma）. The second age of 56.95 -- 1.08 Ma comes from a younger dyke near Olini village which cuts across the lava flows of the area. The age correlates well with the Mandla lavas which are chemically similar to the uppermost Poladpur, Ambenali and Mahabaleshwar Formation lavas of SW Deccan. Our study shows that the dyke activities occurred in two phases, with the second one representing the terminal stage.

关键词： 40Aro39Ar ages Deccan dykes Betul-Jabalpur-Pachmarhi area Narmada-Tapi dyke system

Influence of Spark Plasma Sintering Temperature on the Densification, Microstructure and Mechanical Properties of Al-4.5 wt.%Cu Alloy

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Acta Metallurgica Sinica(English Letters) 2013年第6期26卷 761-771页

作者： S.Devaraj S.Sankaran R.Kumar Department of Metallurgical and Materials Engineering Indian Institute of Technology Madras (IIT Madras)

The effect of sintering temperature on the densification mechanisms, microstructural evolution and mechanical properties of spark plasma sintered （SPS） compacts of a gas atomized Al-4.5 wt.%Cu alloy was investigated. The powder particles whose size varied between 10 to 500μm was subjected to SPS at 400, 450 and 500℃ at a pressure of 30 MPa. The compact sintered at 500℃ exhibited fully dense microstructure which was characterized by a uniform distribution of the secondary phase, free of dendrites and micro-porosity. Microscopy and the SPS data reveal that the events such as particle rearrangement, localized deformation and bulk deformation appear to be the sequence of sintering mechanisms depending on the size range of powder particles used for consolidation. The compact sintered at 500℃ exhibited the highest hardness and compression strength since the microstructure was characterized by fine distribution of precipitates, large fraction of submicron grains and complete metallurgical bonding.

关键词： Spark plasma sintering Sintering mechanisms Precipitation Compression strength

An Interacting Gauge Field Theoretic Model for Hodge Theory: Basic Canonical Brackets

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Communications in Theoretical Physics 2014年第6期61卷 715-728页

作者： R.Kumar S.Gupta r.P.Malik Department of Physics Centre of Advanced Studies Banaras Hindu University DST Centre for Interdisciplinary Mathematical Sciences Faculty of Science Banaras Hindu University

We derive the basic canonical brackets amongst the creation and annihilation operators for a two(1 + 1)-dimensional(2D) gauge field theoretic model of an interacting Hodge theory where a U(1) gauge field(Aμ) is coupled with the fermionic Dirac fields(ψ andˉψ). In this derivation, we exploit the spin-statistics theorem, normal ordering and the strength of the underlying six infinitesimal continuous symmetries(and the concept of their generators) that are present in the theory. We do not use the definition of the canonical conjugate momenta(corresponding to the basic fields of the theory) anywhere in our whole discussion. Thus, we conjecture that our present approach provides an alternative to the canonical method of quantization for a class of gauge field theories that are physical examples of Hodge theory where the continuous symmetries(and corresponding generators) provide the physical realizations of the de rham cohomological operators of differential geometry at the algebraic level.

关键词：规范场理论相互作用场模型支架物理实现湮灭算符使用规范规范方法

Multi objective prediction and optimization of control parameters in the milling of aluminium hybrid metal matrix composites using ANN and Taguchi-grey relational analysis

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Defence Technology（防务技术） 2019年第4期15卷 545-556页

作者： S.Ajith Arul Daniel r.Pugazhenthi R.Kumar S.Vijayananth Department of Mechanical Engineering Vels Institute of ScienceTechnology and Advanced Studies

This study aims to optimize the input parameters such as mass fraction and particle size of SiC along with depth of cut,feed and cutting speed in the milling of Al5059/SiC/MoS2.The hybrid metal matrix composites are generally fabricated by reinforcing of different sizes(10,20,40 μm)of SiC with aluminium at a different levels(5%,10%& 15%)whereas the MoS2 addition is fixed as 2%.The effect of each control factor on response variables are analyzed through Taguchi S/N ratio method.Also,the most significant method for prediction of response parameters is satisfied by ANN model than the regression model.Analysis of variance(ANOVA)results envisage that mass fraction of SiC,feed rate is the most domineering factor on response variable.

关键词： Silicon carbide Temperature Surface roughness Cutting forces Artificial neural network Grey relational analysis

Thermomagnetic effect with microtemperature in a semiconducting photothermal excitation medium

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Applied Mathematics and Mechanics(English Edition) 2018年第6期39卷 783-796页

作者： K.LOTFY R.Kumar W.HASSAN M.GABr Department of Mathematics Faculty of ScienceZagazig University Department of Mathematics Kurukshetra University Mathematics and Physics Department Faculty of EngineeringPort Said University

The main goal of this paper is to focus on the investigation of interaction between a magnetic field and elastic materials with microstructure, whose microelements possess microtemperatures with photothermal excitation. The elastic-photothermal prob- lem in one-dimension is solved by introducing photothermal excitation at the free surface of a semi-infinite semiconducting medium （semiconductor rod）. The integral transform technique is used to solve the governing equations of the problem under the effect of the microtemperature field. The analytical expressions for some physical quantities in the physical domain are obtained with the heating boundary surface and free traction. The numerical inversion technique is used to obtain the resulting quantities in the physical domain. The obtained numerical results with some comparisons are discussed and shown graphically.

关键词： photothermal theory carrier density magnetic field microtemperature Laplace transform