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Effect of deep cryogenic treatment on the microstructural,mechanical and ballistic properties of AA7075-T6 aluminum alloy

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Defence Technology（防务技术） 2023年第12期30卷 101-110页

作者： s.Dharani kumar U.Magarajan saurabh s kumar Rodríguez-Millan M Centre for Machining and Material Testing KPR Institute of Engineering and TechnologyCoimbatoreIndia Department of Mechanical Engineering Sri Venkateswara College of EngineeringChennaiIndia scientific Officer Ballistic Research Centre&Testing RangeNational Forensic Sciences UniversityGandhi NagarIndia Department of Mechanical Engineering University Carlos Ⅲ of MadridLeganesMadridSpain

The study focused on investigating the effect of Deep Cryogenic Treatment(DCT)on the mechanical and ballistic properties of AA7075-T6 aluminum *** microstructure,microhardness,tensile strength,and impact strength of the Base Material(BM)and DCT-treated 7075 samples were analyzed through metallographic analysis and mechanical *** microstructure of the DCT-treated 7075 samples revealed fine grains and a distribution of secondary phase *** tensile strength,impact strength,and microhardness of DCT-treated samples increased by 7.41%,4%,and 9.68%,respectively,compared to the BM *** fractography analysis of the tensile samples showed cleavage facets,microvoids,and dimples in both the *** ballistic behavior of the BM and DCT target plates were studied by impacting hard steel core projectiles at a velocity of 750±10 m/*** target plates failed due to petaling and ductile hole enlargement,and the depth of penetration(DOP)of the DCT target was less than that of the BM target,indicating a higher ballistic *** post-ballistic microstructure examination of the target plates showed the formation of an Adiabatic shear Band(AsB)without any *** was concluded that the DCT treatment improved the mechanical and ballistic properties of the aluminum alloy due to grain refinement and high dislocation density.

关键词： Deep cryogenic treatment AA7075-T6 Mechanical properties Ballistic Adiabatic shear band

Power system reconfiguration and loss minimization for a distribution systems using ＂Catfish PsO＂ algorithm

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Frontiers in Energy 2014年第4期8卷 434-442页

作者： K sathish kumar s NAVEEN school of Electrical Engineering VIT University Vellore 632014 India

One of the very important ways to save electrical energy in the distribution system is network reconfiguration for loss reduction. Distribution networks are built as interconnected mesh networks; however, they are arranged to be radial in operation. The distribution feeder reconfiguration is to find a radial operating structure that optimizes network performance while satisfying operating constraints. The change in network configuration is performed by opening sectionalizing （normally closed） and closing tie （normally opened） switches of the network. These switches are changed in such a way that the radial structure of networks is maintained, all of the loads are energized, power loss is reduced, power quality is enhanced, and system security is increased. Distribution feeder reconfiguration is a complex nonlinear combinator- ial problem since the status of the switches is non- differentiable. This paper proposes a new evolutionary algorithm （EA） for solving the distribution feeder reconfiguration （DFR） problem for a 33-bus and a 16- bus sample network, which effectively ensures the loss minimization.

关键词： distribution system reconfiguration (DFR),power loss reduction catfish particle swarm optimization(catfish PsO) radial structure

A new mathematical model for studying fully ionized plasma flows in MPD thrusters

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International Journal of Modeling, simulation, and scientific Computing 2016年第3期7卷 87-106页

作者： Vijai kumar s Thanigaiarasu s Department of Aerospace Engineering MIT Campus Anna UniversityChennaiTamilnadu 600044India

The paper describes a novel mathematical model to study the physics of fully ionized plasma flow through MPD thrusters otherwise known as magnetoplasmadynamic *** developed model consists of a set of differential equations obtained by coupling the Navier–stokes equations with Maxwell’s *** model developed was tested for various 1D and 1.5D *** simulations have been carried out for a special case of geometries called Tikhonov fitted geometries for alleviating the instability phenomenon commonly known as onset phenomenon in self-field MPD *** work was also extended to applied field MPD thrusters.A new equation for magnetic field was introduced to incorporate a virtual *** the computations were carried out using a higher order integration *** results obtained were found to be in good agreement with the previous work done on similar models.

关键词： MPD thrusters computational fluid dynamics mathematical modeling

Antidiabetic and anti-lipemic effects of Cassia siamea leaves extract in streptozotocin induced diabetic rats

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Asian Pacific Journal of Tropical Medicine 2010年第11期3卷 871-873页

作者： s kumar V kumar Om Prakash Institute of Pharmaceutical sciences Kurukshetra UniversityKurukshetra -136119HaryanaIndia

Objective:To investigate the antidiabetic and anti-lipemic effects of Cassia siamea methanolic leaves ***:The antidiabetic study was performed by measuring blood glucose level with elegance glucometer at weekly intervals i.e.0,7,14 and 21 in normal and streptozotocin induced diabetic *** cholesterol,triglyceride and HDL-cholesterol were determined in normal and streptozotocin induces diabetic rats by *** was used as a reference drug at a dose of 10 mg/***:After the oral administration of extracts at doses of 250 mg/kg and 500 mg/kg for three weeks,blood glucose levels and body weights were significantly improved(Pso resulted in significantly reduction of serum cholesterol and ***-cholesterol level was found to be improved to(Psions:The Cassia siamea leaf extract is useful in controlling blood glucose level as well as improving lipid metabolism and body weight in rats with induced diabetes.

关键词： Cassia siamea Antidiabetic Anti-lipemic Rat streptozotocin

Pattern classification using fuzzy relation and genetic algorithm

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International Journal of Intelligent Computing and Cybernetics 2012年第4期5卷 533-565页

作者： kumar s.Ray Electronics and Communication sciences Unit Indian Statistical InstituteKolkataIndia

Purpose–This paper aims to consider a soft computing approach to pattern classification using the basic tools of fuzzy relational calculus(FRC)and genetic algorithm(GA).Design/methodology/approach–The paper introduces a new interpretation of multidimensional fuzzy implication(MFI)to represent the author’s knowledge about the training data *** also considers the notion of a fuzzy pattern vector(FPV)to handle the fuzzy information granules of the quantized pattern space and to represent a population of training patterns in the quantized pattern *** construction of the pattern classifier is essentially based on the estimate of a fuzzy relation Ri between the antecedent clause and consequent clause of each one-dimensional fuzzy *** the estimation of Ri floating point representation of GA is ***,a set of fuzzy relations is formed from the new interpretation of *** set of fuzzy relations is termed as the core of the pattern *** the classifier is constructed the non-fuzzy features of a test pattern can be ***–The performance of the proposed scheme is tested on synthetic ***,the paper uses the proposed scheme for the vowel classification problem of an Indian *** all these case studies the recognition score of the proposed method is very ***,a benchmark of performance is established by considering Multilayer Perceptron(MLP),support Vector Machine(sVM)and the proposed *** Abalone,Hosse colic and Pima Indians data sets,obtained from UCL database repository are used for the said benchmark *** benchmark study also establishes the superiority of the proposed ***/value–This new soft computing approach to pattern classification is based on a new interpretation of MFI and a novel notion of FPV.A set of fuzzy relations which is the core of the pattern classifier,is estimated using floating point GA and very effective classification of patterns under vague and impreci

关键词： Pattern classifier Multidimensional fuzzy implication Fuzzy information granule Fuzzy patter vector Fuzzy relational calculus Genetic algorithms Fuzzy logic Pattern recognition

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

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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

Global operational land imager Landsat-8 reflectance-based active fire detection algorithm

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International Journal of Digital Earth 2018年第2期11卷 154-178页

作者： s.s.kumar D.P.Roy Plant and Environmental sciences New Mexico State UniversityLas CrucesNMUSA Geospatial sciences Center of Excellence South Dakota State UniversityBrookingsSDUSA

A global operational land imager(GOLI)Landsat-8 daytime active fire detection algorithm is *** utilizes established contextual active fire detection approaches but takes advantage of the significant increase in fire reflectance in Landsat-8 band 7(2.20μm)relative to band 4(0.66μm).The detection thresholds are fixed and based on a statistical examination of 39 million non-burning Landsat-8 ***-temporal tests based on band 7 reflectance and relative changes in normalized difference vegetation index in the previous six months are used to reduce commissions *** probabilities of active fire detection for the GOLI and two recent Landsat-8 active fire detection algorithms are simulated to provide insights into their performance with respect to the fire size and *** algorithms are applied to 11 Landsat-8 images that encompass a range of burning conditions and *** and omission errors are assessed by visual interpretation of detected active fire locations and by examination of the Landsat-8 images and higher spatial resolution Google Earth *** GOLI algorithm has lower omission and comparable commission errors than the recent Landsat-8 active fire detection *** GOLI algorithm has demonstrable potential for global application and is suitable for implementation with other Landsat-like reflective wavelength sensors.

关键词： Earth observation remote sensing visible/infrared remote sensing

Multi-year MODIs active fire type classification over the Brazilian Tropical Moist Forest Biome

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International Journal of Digital Earth 2017年第1期10卷 54-84页

作者： D.P.Roy s.s.kumar Geospatial sciences Center of Excellence South Dakota State UniversityBrookingsSDUSA

The Brazilian Tropical Moist Forest Biome(BTMFB)spans almost 4 million km^(2) and is subject to extensive annual fires that have been categorized into deforestation,maintenance,and forest fire *** on fire types is important as they have different atmospheric emissions and ecological impacts.A supervised classification methodology is presented to classify the fire type of MODerate resolution Imaging spectroradiometer(MODIs)active fire detections using training data defined by consideration of Brazilian government forest monitoring program annual land cover maps,and using predictor variables concerned with fuel flammability,fuel load,fire behavior,fire seasonality,fire annual frequency,proximity to surface transportation,and local *** fire seasonality,local temperature,and fuel flammability were the most influential on the *** fire type results for all 1.6 million MODIs Terra and Aqua BTMFB active fire detections over eight years(2003–2010)are presented with an overall fire type classification accuracy of 90.9%(kappa 0.824).The fire type user’s and producer’s classification accuracies were respectively 92.4%and 94.4%(maintenance fires),88.4%and 87.5%(forest fires),and,88.7%and 75.0%(deforestation fires).The spatial and temporal distribution of the classified fire types are presented and are similar to patterns reported in the available recent literature.

关键词： Earth observation land cover remote sensing

Influence of porosity distribution on nonlinear free vibration and transient responses of porous functionally graded skew plates

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Defence Technology（防务技术） 2021年第6期17卷 1918-1935页

作者： Naveen kumar H s subhaschandra Kattimani TNguyen-Thoi Department of Mechanical Engineering National Institute of Technology KarnatakaSurathkal575025India Division of Computational Mathematics and Engineering Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh CityViet Nam Faculty of Civil Engineering Ton Duc Thang University Ho Chi Minh CityViet Nam

This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew(PFGs)*** effective material properties of the PFGs plates are obtained from the modified power-law equations in which gradation varies through the thickness of the PFGs plate.A nonlinear finite element(FE)formulation for the overall PFGs plate is derived by adopting first-order shear deformation theory(FsDT)in conjunction with von Karman’s nonlinear strain displacement *** governing equations of the PFGs plate are derived using the principle of virtual *** direct iterative method and Newmark’s integration technique are espoused to solve nonlinear mathematical *** influences of the porosity distributions and porosity parameter indices on the nonlinear frequency responses of the PFGs plate for different skew angles are studied in various *** effects of volume fraction grading index and skew angle on the plate’s nonlinear dynamic responses for various porosity distributions are illustrated in detail.

关键词： Porous functionally graded skew plates Porosity distributions Nonlinear transient response Nonlinear frequency ratio Nonlinear frequency parameter