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Microstructures and impact toughness behavior of Al 5083 alloy processed by cryorolling and afterwards annealing

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International Journal of Minerals,Metallurgy and Materials 2013年第8期20卷 759-769页

作者： dharmendra singh P.Nageswara Rao R.Jayaganthan Department of Metallurgical and Materials Engineering Indian Institute of Technology RoorkeeRoorkee-247667India

The influence of rolling at liquid nitrogen temperature and annealing on the microstructure and mechanical properties of Al 5083 alloy was studied in this paper. Cryorolled samples of Al 5083 show significant improvements in strength and hardness. The ultimate tensile strength increases up to 340 MPa and 390 MPa for the 30% and 50% cryorolled samples, respectively. The cryorolled samples, with 30% and 50% reduction, were subjected to Charpy impact testing at various temperatures from 190℃ to 100℃. It is observed that increasing the percentage of reduction of samples during cryorolling has significant effect on decreasing impact toughness at all temperatures by increasing yield strength and decreasing ductility. Annealing of samples after cryorolling shows remarkable increment in impact toughness through recovery and recrystallization. The average grain size of the 50% cryorolled sample （14 μm） after annealing at 350℃ for 1 h is found to be finer than that of the 30% cryorolled sample （25 μm）. The scanning electron microscopy （SEM） analysis of fractured surfaces shows a large-size dimpled morphology, resembling the ductile fracture mechanism in the starting material and fibrous structure with very fine dimples in cryorolled samples corresponding to the brittle fracture mechanism.

关键词： aluminum alloys cryorolling annealing microstructure impact toughness recovery recrystallization

Effect of Post Cryorolling Treatments on Microstructural and Mechanical Behaviour of Ultrafine Grained Al-Mg-Si Alloy

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Journal of Materials Science & Technology 2014年第10期30卷 998-1005页

作者： P.Nageswara rao dharmendra singh R.Jayaganthan Department of Metallurgical and Materials Engineering Indian Institute of Technology Roorkee

To investigate the effect of post cryorolling treatments on simultaneous enhancement in strength and ductility of ultrafine grained material （UFG）, AI 6061 alloy was subjected to cryorolling followed by warm rolling （CR ＋ WR） and compared with cryorolling followed by short annealing （CR ＋ SA） at the same temperature. Transmission electron microscopy （TEM） was used to characterize the microstructural features of the processed material. The mechanical properties were investigated through Vickers hardness testing and tensile testing at room temperature. TEM, X-ray diffraction （XRD） and differential scanning calorimetry （DSC） were used to investigate the precipitation evolution in UFG material. Results indicated that the alloy subjected to CR ＋ WR has shown improved mechanical properties （114 HV, ultimate tensile strength （UTS）： 350 MPa） as compared to that in the case of CR ＋ SA （105 HV, UTS： 285 MPa）. The size of the precipitates observed in CR ＋ WR sample after peak ageing treatment is finer than that of peak aged CR ＋ SA sample. The UTS of peak aged CR ＋ WR sample （UTS： 390 MPa） was found to be higher than that of peak aged CR ＋ SA sample （UTS： 355 MPa）, without decrease in ductility.

关键词： Aluminium alloy Cryorolling Warm rolling Short annealing Mechanical properties Differential scanning calorimetry (DSC)

Optical performance of hybrid dielectric loaded plasmonic waveguide using PTFE for nano-scale light confinement

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Optoelectronics Letters 2020年第4期16卷 284-289页

作者： Pintu Kumar dharmendra Kumar singh Rakesh Ranjan Optical Fiber Communication and Photonics Lab Department of Electronics and Communication EngineeringNational Institute of Technology(NIT)PatnaPatna 800005India

Different characteristics of fundamental mode of hybrid dielectric loaded plasmonic waveguide have been explored at1550 nm wavelength,to resolve the issue of large propagation loss and diffraction limit with minimal waveguide *** length of 432μm has been achieved with the optimal dimension of 200 nm×40 *** the numerical simulation results,the effective area of 0.021μm^2 and normalized intensity of 40.71μm^-2 in the spacer region of the waveguide have been *** accomplish the ultra-compact directional coupler,the smaller coupling length of about 1.42μm has been ***-based waveguide can be highly beneficial for the realization of monolithic integration with active optical devices.

关键词： waveguide dielectric loaded

A New Fuzzy Adaptive Algorithm to Classify Imbalanced Data

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Computers, Materials & Continua 2022年第1期70卷 73-89页

作者： Harshita Patel dharmendra singh Rajput Ovidiu Petru Stan Liviu Cristian Miclea School of Information Technology&Engineering Vellore Institute of TechnologyVellore632014India Technical University of Cluj Napoca Faculty of Automation and Computer ScienceCluj Napoca400114Romania

Classification of imbalanced data is a well explored issue in the data mining and machine learning community where one class representation is overwhelmed by other *** Imbalanced distribution of data is a natural occurrence in real world datasets,so needed to be dealt with carefully to get important *** case of imbalance in data sets,traditional classifiers have to sacrifice their performances,therefore lead to *** paper suggests a weighted nearest neighbor approach in a fuzzy manner to deal with this *** have adapted the‘existing algorithm modification solution’to learn from imbalanced datasets that classify data without manipulating the natural distribution of data unlike the other popular data balancing *** K nearest neighbor is a non-parametric classification method that is mostly used in machine learning *** classification with the nearest neighbor clears the belonging of an instance to classes and optimal weights with improved nearest neighbor concept helping to correctly classify imbalanced *** proposed hybrid approach takes care of imbalance nature of data and reduces the inaccuracies appear in applications of original and traditional *** show that it performs well over the existing fuzzy nearest neighbor and weighted neighbor strategies for imbalanced learning.

关键词： Machine learning fuzzy classification nearest neighbor adaptive approach optimal weights

Immunochemical characterization of antigens of Brucella canis and their use in seroprevalence study of canine brucellosis

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Asian Pacific Journal of Tropical Medicine 2011年第11期4卷 857-861页

作者： Sharma Barkha Sinha dharmendra Kumar singh Dhirendra Kumar Department of Epidemiology and Preventive Medicine College of Veterinary SciencePandit Deen Dayal Upadhaya Veterinary UniversityMathuraUttar PradeshPin-281001India Division of Epidemiology Indian Veterinary Research InstituteIzatnagarBareillyUttar Pradesh243122India Division of Veterinary Public Health Indian Veterinary Research InstituteIzatnagarBareillyUttar Pradesh243122 India

Objective:To explore immunochemical characterization of antigens of Brucella canis(B. canis),and the use in seroprevalence study of canine ***:External hot phosphate buffer saline extract(HPBSE) and internal sonicated(SA) antigens were prepared from *** strain MEX 51 and imniunochemically *** antigens were used to test 527 serum samples of dogs by 2-mercaptoethanol-tubc agglutination test(2 ME-TAT), agar gel immunodiffusion test(AGID).dot-ELISA and indirect enzyme-linked immunosorbent assay(I-ELISA) to assess the seroprevalence of canine ***:The protein content of HPBSE and SA antigens was 0.387 mg/*** 0.195 mg/mL,respectively,whereas carbohydrate content was 0.174 mg/mL and 0.150 mg/mL,*** sodium dodecyl sulfate-polyacrylamide gel electrophoresis(12.5%) of HPBSE and SA,revealed 6 and 8 visible peptide bands ranging from 18-80 kDa and 12-45 kDa,*** blot analysis showed immunodominant bands of MW 12.28.39 and 45 kl)a for HPBSE and 20-24 kl)a for SA. The AGII) revealed HPBSE as more specific antigen than SA but both I-ELISA and dot-ELISA indicated SA antigen to be more specific and reliable than *** seroprevalence of canine brucellosis was 2.27%by 2ME-TAT.1.5%by AGID.3.03%by dot-ELISA and 16.12%by I-ELISA. Conclusions:On the basis of the results of present study,we concluded that HPBSE is suitable antigen for AGID,which is more specific:whereas SA antigen is suitable for I-ELISA,which is highly ***,initial screening of serum samples should be carried out by I-ELISA followed by confirmation with AGID.

关键词： Brucella canis SDS-PAGE Western blotting Agar gel immunodiffusion test Dot-ELISA I-ELISA

Changes in species composition, diversity and biomass of herbaceous plant traits due to N amendment in a dry tropical environment of India

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Journal of Plant Ecology 2015年第3期8卷 321-332页

作者： Punita Verma R.Sagar Hariom Verma Preeti Verma dharmendra K.singh Department of Botany Banaras Hindu UniversityVaranasi-221005India

Aim European and North american studies have suggested that nitrogen(N)depositions reduce plant diversity and increase primary pro-ductivity due to changes in plant *** predict the vegetation response to future global change,experimental validations from other regions are widely *** assessed the effects of N treat-ment by urea fertilization on the diversity and biomass of the her-baceous plant traits(HPTs)in a dry tropical environment of *** Diversity and biomass of different HPTs were determined on the basis of data collected in year 2010,from 135,1 m×1 m plots dis-tributed over 15 *** plots were treated with urea fertilizer in different doses(Control,60 kgNha−1 yr−1 and 120 kg N ha−1yr−1)since 1st January *** plots were ordinated and data were subjected to appropriate statistical *** Findings Correspondence analysis(Ca)suggested uniqueness of species composition due to N *** number and biomass of the trait categories varied due to N fertilization and *** studied trait categories(except N-fixers)yielded maximum mean species number at moderate level of N *** levels of N fer-tilization exhibited different species diversity-primary productivity(D-P)***,study showed reduction in plant diver-sity due to increase in biomass at high rates of N *** Tall,erect,non N-fixers,annuals,grasses HPTs were favoured by N enrichment.N dose above 60 kg enhanced the biomass of fast grow-ing,erect,annuals,non N-fixers,nitrophilic *** changes in traits with N addition,especially the increase in annuals and grasses and decrease in typically N-rich N-fixers,have implications for sus-tainable cattle production.

关键词： biomass Ca ordination dry tropics N amendment herbaceous plant traits primary productivity species diversity

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

Structural,optical and antimicrobial properties of pure and Agdoped ZnO nanostructures

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Journal of Semiconductors 2022年第3期43卷 78-86页

作者： Sagar Vikal Yogendra K.Gautam Anit K.Ambedkar Durvesh Gautam Jyoti singh dharmendra pratap Ashwani Kumar Sanjay Kumar Meenal Gupta Beer Pal singh Smart Materials and Sensor Laboratory Department of PhysicsCh.Charan Singh UniversityMeerutUttar Pradesh 250004India Department of Genetics and Plant Breeding Ch.Charan Singh UniversityMeerutUttar Pradesh 250004India Nanoscience Laboratory Institute Instrumentation CentreIIT RoorkeeRoorkee 247667India Department of Physics University of RajasthanJaipur 302004India Department of Physics SBSRSharda UniversityGreater NoidaUttar PradeshIndia

In the present work,zinc oxide(ZnO)and silver(Ag)doped ZnO nanostructures are synthesized using a hydrothermal *** quality of the products is attested using X-ray diffraction,which confirms the hexagonal wurtzite struc-ture of pure ZnO and Ag-doped ZnO *** further confirms the crystallite orientation along the c-axis,(101)*** field emission scanning electron microscope study reveals the change in shape of the synthesized ZnO particles from hexagonal nanoparticles to needle-shaped nanostructures for 3 wt%Ag-doped *** optical band gaps and lattice strain of nanostructures is increased significantly with the increase of doping concentration of Ag in ZnO *** anti-microbial activity of synthesized nanostructures has been evaluated against the gram-positive human pathogenic bacteria,Staphylococcus aureus via an agarose gel diffusion *** maximum value of zone of inhibition(22 mm)is achieved for 3 wt%Ag-doped ZnO nanostructure and it clearly demonstrates the remarkable antibacterial activity.

关键词： zinc oxide silver hydrothermal FESEM antimicrobial activity Staphylococcus

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.