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Influence of alumina/MWCNT hybrid nanoparticle additives on tribological properties of lubricants in turning operations

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Friction 2019年第2期7卷 153-168页

作者： Anuj kumar SHARMA Jitendra kumar KATIYAR Shubrajit BHAUMIK Sandipan roy Tribology and Surface Interaction Research Lab Department of Mechanical EngineeringSRM Institute of Science and Technology Kattankulathur

A hybrid lubricant with improved thermal and tribological properties was developed by blending multiwalled carbon nanotubes(MWCNTs) with alumina-based nanoparticles into cutting fluid at fixed volumetric proportions(10:90). The hybrid cutting fluid was prepared in different volumetric concentrations(0.25, 0.75, and 1.25 vol%), and the tribological properties and contact angles were measured using pin-on-disc tribometry and goniometry, respectively. The study showed a reduction in wear and friction coefficient with increasing nanoparticle concentration. The cutting fluid performance was investigated using minimum quantity lubrication(MQL) in the turning of AISI 304 stainless steel. Regression models were developed for measuring the temperature and tool flank wear in terms of cutting speed, feed, depth of the cut, and nanoparticle concentration using response surface methodology. The developed hybrid nanolubricants significantly reduced the tool flank wear and nodal temperature by 11% and 27.36%, respectively, as compared to alumina-based lubricants.

关键词： hybrids nanolubricants MQL MWCNT tool wear friction coefficient

Fast Identification of Symmetrical or Asymmetrical Faults During Power Swings with Dual Use Line Relays

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CSEE Journal of Power and Energy Systems 2020年第1期6卷 184-192页

作者： Soumesh Chatterjee Biman kumar Saha roy National Institute of Technology Agartala AgartalaTripura-799046India National Institute of Technology Durgapur DurgapurWest Bengal-713209India

Increasing power demand,penetration of renew-ables,and limitations of necessary grid expansion are proffering new challenges to existing power system protection and control ***,with the advancement in intelligent elec-tronic devices and relaying technology,fast,accurate and reliable protection schemes can be developed for smart power *** this paper,a new protection scheme based on admittance and power change has been proposed with dual-use line relays to detect symmetrical/asymmetrical faults in power systems.A large number of fault environments have been simulated by varying fault distances from relay location,fault resistance,and power angle in single machine infinite bus and WSCC 9-bus *** crucial decisive fault scenarios *** in/far end faults,faults in series compensated line,faults during asymmetrical swings,switching ON/OFF large loads,single and multi-modal swings have also been verified for the proposed *** this paper,for the first time,detection of faults during power swings have been examined and verified in the presence of wind *** simulation results show the proficiency of the proposed algorithm for detecting faults in the presence or absence of power swings.

关键词： Dual use line relays(DULR) power swing power system protection synchrophasor measurements

All-optical adder/subtractor based on terahertz optical asymmetric demultiplexer

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Chinese Optics Letters 2009年第6期7卷 530-533页

作者： Dilip kumar Gayen Rajat kumar Pal Jitendra Nath roy Department of Computer Science College of Engineering and Management Department of Computer Science and Engineering Calcutta University Department of Physics College of Engineering and ManagementKolaghat KTPP Township

An all-optical adder/subtractor （A/S） unit with the （TOAD） is proposed. The all-optical A/S unit with help of terahertz optical asymmetric demultiplexer a set of all-optical full-adders and optical exclusive- ORs （XORs）, can be used to perform a fast central processor unit using optical hardware components. We try to exploit the advantages of TOAD-based optical switch to design an integrated all-optical circuit which can perform binary addition and subtraction. With computer simulation results confirming the described methods, conclusions are given.

关键词： EDFA XOR All-optical adder/subtractor based on terahertz optical asymmetric demultiplexer mode

Convergence of Weak Galerkin Finite Element Method for Second Order Linear Wave Equation in Heterogeneous Media

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Numerical Mathematics(Theory,Methods and Applications) 2023年第2期16卷 323-347页

作者： Bhupen Deka Papri roy Naresh kumar Raman kumar Department of Mathematics Indian Institute of Technology GuwahatiGuwahati 781039India

Weak Galerkin finite element method is introduced for solving wave equation with interface on weak Galerkin finite element space(Pk(K),P_(k−1)(∂K),[P_(k−1)(K)]^(2)).Optimal order a priori error estimates for both space-discrete scheme and implicit fully discrete scheme are derived in L1(L2)*** method uses totally discontinuous functions in approximation space and allows the usage of finite element partitions consisting of general polygonal *** element algorithm presented here can contribute to a variety of hyperbolic problems where physical domain consists of heterogeneous media.

关键词： Wave equation heterogeneous medium finite element method weak Galerkin method semidiscrete and fully discrete schemes optimal error estimates

Chromium-induced membrane damage: protective role of ascorbic acid

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Journal of Environmental Sciences 2001年第3期13卷 272-275页

作者： Sankar kumar Dey Prasunpriya Nayak Somenath roy Department of Human Physiology with Community Health Vidyasagar UniversityMidnapore 721102West BengalIndia

Importance of chromium as environmental toxicant is largely due to impact on the body to produce cellular toxicity. The impact of chromium and their supplementation with ascorbic acid was studied on plasma membrane of liver and kidney in male Wistar rats (80-100g body weight). It has been observed that the intoxication with chromium (i.p.) at the dose of 0.8 mg/100g body weight per day for a period of 28 days causes significant increase in the level of cholesterol and decrease in the level of phospholipid of both liver and kidney. The alkaline phosphatase, total ATPase and Na\++\|K\++\|ATPase activities were significantly decreased in both liver and kidney after chromium treatment, except total ATPase activity of kidney. It is suggested that chromium exposure at the present dose and duration induce for the alterations of structure and function of both liver and kidney plasma membrane. Ascorbic acid (i.p. at the dose of 0.5 mg/100g body weight per day for period of 28 days) supplementation can reduce these structural changes in the plasma membrane of liver and kidney. But the functional changes can not be completely replenished by the ascorbic acid supplementation in response to chromium exposure. So it is also suggested that ascorbic acid (nutritional antioxidant) is useful free radical scavenger to restrain the chromium induced membrane damage.

关键词： chromium liver kidney membrane ascorbic acid

Alpha-tocopherol supplementation on chromium toxicity: a study on rat liver and kidney cell membrane

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Journal of Environmental Sciences 2003年第3期15卷 356-359页

作者： Sankar kumar Dey Prasunpriya Nayak Somenath roy Department of Human Physiology with Community Health Vidyasagar UniversityDepartment of Human Physiology with Community Health Vidyasagar UniversityDepartment of Human Physiology with Community Health Vidyasagar University Midnapore-721 102 West Bengal IndiaMidnapore-721 102 West Bengal IndiaMidnapore-721 102 West Bengal India

Membrane damage is one of the important consequence of chromium, an environmental toxicant, to produce cytotoxicity. α-tocopherol, a membrane protectant can be used to reduce the chromium-induced membrane damage. In the present study, the impact of chromium in presence and absence of α-tocopherol was studied on plasma membrane of liver and kidney in male Wistar rats (80—100 g body weight). Significant increase in membrane cholesterol level as well as significant decrease in membrane phospholipid level in chromium exposed ( 0.8 mg /100 g body weight/d, i.p., for 4 weeks) animals suggest structural alteration of both liver and kidney plasma memebrane. The alkaline phosphatase, total ATPase and Na +-K +-ATPase activities of plasma membrane were significantly decreased in both liver and kidney after chromium treatment. However, α-tocopherol (30 mg/100 g diet) supplementation can restrict the changes in these membrane-bound enzyme activities. Thus, the usefulness of dietary supplementation of α-tocopherol to restrain the chromium-induced membrane damage is suggested.

关键词： chromium liver kidney membrane α-tocopherol

Probing the compound effect of spatially varying intrinsic defects and doping on mechanical properties of hybrid graphene monolayers

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Journal of Materials Science & Technology 2020年第15期47卷 44-58页

作者： Kritesh kumar Gupta Tanmoy Mukhopadhyay Aditya roy Sudip Dey Department of Mechanical Engineering National Institute of Technology SilcharSilcharIndia Department of Aerospace Engineering Indian Institute of Technology KanpurKanpurIndia

Doping in pristine 2 D materials brings about the advantage of modulating wide range of mechanical properties ***,intrinsic defects(such as Stone-Wales and nanopore) in such hybrid materials are inevitable due to complex manu facturing and synthesis *** that,de fects and irregularities can be intentionally induced in a pristine nanostructure for multi-synchronous modulation of various multi-functional *** the case may be,in order to realistically analyse a doped graphene sheet,it is of utmost importance to investigate the compound effect of doping and defects in such 2 D *** we present a molecular dynamics based investigation for probing mechanical properties(such as Young’s modulus,post-elastic behaviour,failure strength and strain)of doped graphene(C14 and Si) coupling the effect of inevitable *** sensitivity of defect and doping are systematically analyzed considering different rational *** study reveals the effects of individual defects and doping along with their possible compounded influences on the failure stress,failure strain,Young’s modulus and constitutive relations beyond the elastic *** detailed mechanical characterization under the practically relevant compound effects would allow us to access the viability of adopting doped graphene in various multifunctional nanoelectromechanical devices and systems in a realistic situation.

关键词： Defect in graphene Doped graphene Defected 2D material Temperature-dependent mechanical properties Spatial sensitivity of defect and doping

Estimation of the internal and external damping from the forward and backward spectrum of a rotor with a fatigue crack

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Propulsion and Power Research 2020年第1期9卷 62-74页

作者： Dipendra kumar roy Rajiv Tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiAssam781039India Faculty of Mechanical Engineering Indian Institute of Technology GuwahatiAssam781039India

Both internal and external damping are concurrently present in a rotor ***,the internal damping that originates from various sources often leads to instability in the rotor system,and hence its accurate estimation is *** goal of the present paper is to distinctly estimate both external and internal damping in a Jeffcott rotor containing transverse *** modelling of the fatigue crack is based on the assumption of a switching crack,which additionally provides the internal damping due to rubbing on crack faces,which is hardly addressed in ***,the fatigue crack leads to the forward and backward whirls due to asymmetry in the *** the process of development of the identification procedure in the form of the regression equation for the estimation of internal damping,other important unknown rotor system parameters,like the external damping,unbalance and loss of stiffness of the shaft due to the crack,are also *** reduces the estimation error of the internal damping due to reduction in deviations of other model *** simulated responses are obtained from equations of motion of the rotor system in the form of a closed-form expression and by the Runge-Kutta integration *** full-spectrum response data(both magnitude and phase)are utilized during the testing of the proposed identification *** corrections have been incorporated in the *** noise is added in numerical responses during identification of parameters to check the robustness of the algorithm and found to be working satisfactorily.

关键词： Internal damping External damping Switching crack Unbalance Full spectrum

Hydrodynamic dispersion of reactive solute in a Hagen–Poiseuille flow of a layered liquid

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Chinese Journal of Chemical Engineering 2017年第7期25卷 862-873页

作者： Sudip Debnath Apu kumar Saha B.S.Mazumder Ashis kumar roy Department of Mathematics National Institute of TechnologyAgartala 799046India Fluvial Mechanics Laboratory Physics and Applied Mathematics UnitIndian Statistical InstituteKolkata 700108India Fluid Mechanics and Hydraulic Laboratory(FMHL) Department of Aernspace Engineering and Applied MechanicsIndian Institute of Engineering Science and Technology(IIEST)ShibpurHowrah 711103India

An analysis of the solute dispersion in the liquid flowing through a pipe by means of Aris–Barton's ‘method of moments', under the joint effect of some finite yield stress and irreversible absorption into the wall is presented in this paper. The liquid is considered as a three-layer liquid where the center region is Casson liquid surrounded by Newtonian liquid layer. A significant change from previous modelling exercises in the study of hydrodynamic dispersion, different molecular diffusivity has been considered for the different region yet to be constant. For all time period, finite difference implicit scheme has been adopted to solve the integral moment equation arising from the unsteady convective diffusion equation. The purpose of the study is to find the dependency of solute transport coefficients on absorption parameter, yield stress, viscosity ratio, peripheral layer variation and in addition with various diffusivity coefficients in different liquid layers. This kind of study may be useful for understanding the dispersion process in the blood flow analysis.

关键词： Casson liquid Yield stress Axial-dispersion coefficient Irreversible reaction Diffusivity