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Journal of Control and Decision 2023年第4期10卷 538-546页

作者： k.ramkumar k.Ravikumar E.M.Elsayed Department of Mathematics with CA PSG College of Arts&ScienceCoimbatoreIndia Department of Mathematics PSG College of Arts&ScienceCoimbatoreIndia Department of Mathematics Faculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia Department of Mathematics Faculty of ScienceMansoura UniversityMansouraEgypt

In this work,the optimal control for a class of Hilfer fractional stochastic integrodifferential systems driven by Rosenblatt process and Poisson jumps has been discussed in infinite dimensional space involving the Hilfer fractional ***,we study the existence and uniqueness of mild solution results are proved by the virtue of fractional calculus,successive approximation method and stochastic analysis ***,the optimal control of the proposed problem is presented by using Balder’s ***,an example is demonstrated to illustrate the obtained theoretical results.

关键词： Hilfer fractional derivative stochastic integrodifferential systems Rosenblatt process Poisson jumps successive approximation optimal control

Vastly Synergistic Fe2CuNiS4-Nanoarchitectures Anchored 2D-Nano-Sandwich Derived from Flower-Like-CuFeS2/N-Graphene and Cube-Like-NiFeS2/N-CNTs for Water Oxidation and Nitrophenol Reduction

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ENERGY & ENVIRONMENTAL MATERIALS 2024年第6期7卷 274-289页

作者： Mayakrishnan, Gopiraman Vanaraj, ramkumar Xiong, Junpeng Farooq, Muhammad Ullah, Azeem Zhang, keqin kim, Seong Cheol kim, Ick Soo Shinshu Univ Inst Fiber Engn IFES Interdisciplinary Cluster Cutting Edge Res ICCER Nano Fus Technol Res GrpDiv Mol & Polymers Tokida 3-15-1 Ueda Nagano 3868567 Japan Yeungnam Univ Sch Chem Engn Gyongsan 38541 South Korea Shinshu Univ Grad Sch Med Sci & Technol Tokida 3-15-1 Ueda Nagano 3868567 Japan Soochow Univ Coll Text & Clothing Engn Natl Engn Lab Modern Silk Suzhou 215123 Peoples R China

Surface area, pore properties, synergistic behavior, homogenous dispersion, and interactions between carbon matrix and metal-nanostructures are the key factors for achieving the better performance of carbon-metal based (electro)catalysts. However, the traditional hydro- or solvothermal preparation of (electro)catalysts, particularly, bi- or tri-metallic nanostructures anchored graphene (G) or carbon nanotubes (CNTs), often pose to poor metal-support interaction, low synergism, and patchy dispersion. At first, bimetallic flower-like-CuFeS2/NG and cube-like-NiFeS2/NCNTs nanocomposites were prepared by solvothermal method. The resultant bimetallic nanocomposites were employed to derive the 2D-nano-sandwiched Fe2CuNiS4/NGCNTs-SW (electro)catalyst by a very simple and green urea-mediated "mix-heat" method. The desired physicochemical properties of Fe2CuNiS4/NGCNTs-SW such as multiple active sites, strong metal-support interaction, homogenous dispersion and enhanced surface area were confirmed by various microscopic and spectroscopic techniques. To the best of our knowledge, this is the first urea-mediated "mix-heat" method for preparing 2D-nano-sandwiched carbon-metal-based (electro)catalysts. The Fe2CuNiS4/NGCNTs-SW was found to be highly effective for alkaline-mediated oxygen evolution reaction at low onset potential of 284.24 mV, and the stable current density of 10 mA cm(-2) in 1.0 m kOH for 10 h. Further, the Fe2CuNiS4/NGCNTs-SW demonstrated excellent catalytic activity in the reduction of 4-nitrophenol with good kapp value of 87.71 x 10(-2) s(-1) and excellent reusability over five cycles. Overall, the developed urea-mediated "mix-heat" method is highly efficient for the preparation of metal-nanoarchitectures anchored 2D-nano-sandwiched (electro)catalysts with high synergism, uniform dispersion and excellent metal-support interaction.

关键词： (electro)catalyst metal-sulfide nanoarchitectures mix-heat N-graphene/N-CNTs synergistic effect urea CELLULOSE NANOFIBER COMPOSITES OXYGEN EVOLUTION TRANSFER HYDROGENATION GRAPHENE CATALYST FACILE ELECTROCATALYST NANOTECHNOLOGY NANOPARTICLES EFFICIENT

key Management Using Chebyshev Polynomials for Mobile Ad Hoc Networks

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China Communications 2017年第11期14卷 237-246页

作者： k.R.ramkumar Raman Singh Chitkara University Chandigarh - Patiala National Highways (NH 64)Patiala - 140401 Punjab India Thapar University Patiala- 147004 Punjab India

A dedicated key server cannot be instituted to manage keys for MANETs since they are dynamic and unstable. The Lagrange's polynomial and curve fitting are being used to implement hierarchical key management for Mobile Ad hoc Networks(MANETs). The polynomial interpolation by Lagrange and curve fitting requires high computational efforts for higher order polynomials and moreover they are susceptible to Runge's phenomenon. The Chebyshev polynomials are secure, accurate, and stable and there is no limit to the degree of the polynomials. The distributed key management is a big challenge in these time varying networks. In this work, the Chebyshev polynomials are used to perform key management and tested in various conditions. The secret key shares generation, symmetric key construction and key distribution by using Chebyshev polynomials are the main elements of this projected work. The significance property of Chebyshev polynomials is its recursive nature. The mobile nodes usually have less computational power and less memory, the key management by using Chebyshev polynomials reduces the burden of mobile nodes to implement the overall system.

关键词： chebyshev polynomials interpolation secret sharing key management

Characterization of Microstructure, Strength, and Toughness of Dissimilar Weldments of Inconel 625 and Duplex Stainless Steel SAF 2205

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Acta Metallurgica Sinica(English Letters) 2014年第6期27卷 1018-1030页

作者： R. Sridhar k. Devendranath ramkumar N. Arivazhagan School of Mechanical & Building Sciences VIT University Saraswathy Velu College of Engineering

The dissimilar combinations of Inconel 625 and duplex stainless steel SAF 2205 obtained from manual GTA welding process employing ER2209 and ERNi CrMo-3 filler metals have been investigated. Formation of secondary phases at the HAZ of Inconel 625 and grain coarsening at the HAZ of SAF 2205 were witnessed while using these filler wires. The average hardness of ER2209 weldments was found to be greater than ERNi CrMo-3 weld. Tensile fracture was observed at the weld zones for both the fillers. Impact test trials showed brittle mode of fracture on employing ER2209 filler and mixed（ductile–brittle） mode of fracture while using ERNi CrMo-3 filler. Further optical microscopy and SEM/EDS analysis were carried out across the weldments to investigate the structure–property relationships.

关键词： Inconel 625 Duplex stainless steel SAF 2205 Dissimilar metal welding Microstructure Mechanical characterization

A Blockchain Based Framework for Information System Integrity

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China Communications 2019年第6期16卷 1-17页

作者： Mahalingam ramkumar Department of Computer Science and Engineering Mississippi State University

A blockchain based system integrity(BCSI)framework for assuring the integrity of information system processes is *** is well suited for a broad class of large scale real-world information *** the BCSI framework,the integrity of any information system I is assured by executing the finite state machine model for system I processes in a blockchain *** BCSI framework is compared and contrasted with the Clark-Wilson(CW)system integrity model,and existing blockchain based frameworks like Ethereum.

关键词： blockchains finite state machine model ordered merkle tree

Utilization of chemical looping strategy in coal gasification processes

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Particuology 2008年第3期6卷 131-142页

作者： Liangshih Fan Shwetha ramkumar Department of Chemical and Biomolecular Engineering The Ohio State UniversityUnited States

Three chemical looping gasification processes, i.e. Syngas Chemical Looping （SCL） process, Coal Direct Chemical Looping （CDCL） process, and Calcium Looping process （CLP）, are being developed at the Ohio State University （OSU）. These processes utilize simple reaction schemes to convert carbonaceous fuels into products such as hydrogen, electricity, and synthetic fuels through the transformation of a highly reactive, highly recyclable chemical intermediate. In this paper, these novel chemical looping gasification processes are described and their advantages and potential challenges for commercialization are discussed.

关键词： Chemical looping Gasification process Combustion Hydrogen

Hot Corrosion Behavior of Friction Welded AISI 4140 and AISI 304 in k_2SO-60% NaCl Mixture

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Journal of Materials Science & Technology 2012年第10期28卷 895-904页

作者： N.Arivazhagan k.Senthilkumaran S.Narayanan k.Devendranath ramkumar S.Surendra S.Prakash School of Mechanical and Building Sciences VIT University Department of Metallurgical and Materials Engineering Indian Institute of Technology Roorkee

Understanding the behavior of weldment at elevated temperatures and especially the corrosion behavior has become an object of scientific investigation recently. Investigation has been carried out on friction welded AISI 4140 and AISI 304 in molten salt of k2SO4-60% NaCI environment at 550, 600 and 650 ℃ under cyclic condition. The resulted oxide scales in the weldment have been characterized systematically by surface analytical techniques. From the results of the experiments~ it is observed that the scale thickness on low alloy steel side was higher than that on stainless steel side. Furthermore, weld interface has been found to be more susceptible to degradation than base metals due to inter diffusion of element across the interface and the formation of intermetallic compound. The influences of welding parameters and the temperature of exposure on the hot corrosion behavior of the weldment were discussed in this paper.

关键词： Friction Welding Dissimilar metals Hot corrosion

Distribution of clay minerals in marine sediments off Chennai,Bay of Bengal,India:Indicators of sediment sources and transport processes

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International Journal of Sediment Research 2014年第1期29卷 11-23页

作者： Subramanian VEERASINGAM Ramdoss VENkATACHALAPATHY Thirunavukkarasu ramkumar CSIR-National Institute of Oceanography Department of Physics Annamalai University Centre of Advanced Study in Marine Biology Faculty of Marine SciencesAnnamalai University Department of Earth Sciences Annamalai University

Clay mineralogy,texture size and statistical analyses were carried out on surface sediments from the continental shelf of Chennai,Bay of Bengal,*** purpose of this study is to characterize the clay mineral distribution and its relation to the hydrodynamics off Chennai to identify the sources and transport pathways of the marine *** of clay minerals in coastal sediments by Fourier Transform Infrared(FTIR)spectroscopy has provided the association of quartz,feldspar,kaolinite,chlorite,illite and iron oxides(magnetite and hematite) derived from river catchments and coastal ***,chlorite,illite,iron oxides,and organic matter are the dominant minerals in Cooum,and Adayar *** quartz and feldspar zones were identified in Marina,which are being confined the sand zone and paralleling the *** strong relationships among the wave energy density,sand,quartz and carbonate revealed that wave induced littoral drift system play a dominant role in transportation and deposition of sediments in the Chennai *** sediment texture and minerals data are in agreement well with the previous results of hydrodynamics and littoral drift models in this *** statistical analyses(correlation,cluster and factor analyses) were carried out and obtained results suggested that clay minerals and organic matter are trapped in silt and clay particles,whereas quartz,feldspar and carbonate are associated with sand *** of sediment sources and transport processes from this study will be useful to predict the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas.

关键词： Clay minerals Texture size Marine sediment Hydrodynamics Multivariate statistics

Application of remote sensing and GIS analysis for identifying groundwater potential zone in parts of kodaikanal Taluk, South India

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Frontiers of Earth Science 2013年第1期7卷 65-75页

作者： Murugesan BAGYARAJ Thirunavukkarasu ramkumar Senapathi VENkATRAMANAN Balasubramanian GURUGNANAM Department of Earth Sciences Annamalai University Annamalai Nagar 608002 India Department of Geology Gandhigram Rural Institute Deemed University Gandhigarm 624302 India

Groundwater potential zones were demarcated with the help of remote sensing and Geographic Informa- tion System （GIS） techniques. The study area is composed rocks of Archaean age and chamockite dominated over others. The parameters considered for identifying the groundwater potential zone of geology slope, drainage density, geomorphic units and lineament density were generated using the resource sat （IRS P6 LISS IV MX） data and survey of India （SO1） toposheets of scale 1：50000 and integrated them with an inverse distance weighted （IDW） model based on GIS data to identify the ground- water potential of the study area. Suitable weightage factors were assigned for each category of these para- meters. For the various geomorphic units, weightage factors were assigned based on their capability to store ground-water. This procedure was repeated for all the other layers and resultant layers were reclassified. The reclassi- fied layers were then combined to demarcate zones as very good, good, moderate, low, and poor. This groundwater potentiality information could be used for effective identification of suitable locations for extraction of potable water for rural populations.

关键词： remote sensing GIS slope geomorphic lineament kodaikanal

Variations in texture of beach sediments in the vicinity of the Tirumalairajanar river mouth of India

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International Journal of Sediment Research 2011年第4期26卷 460-470页

作者： Senapathi VENkATRAMANAN Thirunavukkarasu ramkumar Irudhayanathan ANITHAMARY Govindaraj RAMESH Research scholar Department of Earth SciencesAnnamalai UniversityAnnamalainagar608002.TamilnaduIndia Department of Earth Sciences Annamalai University

The distribution of grain size parameters along 11 km stretch of the beach sediments between karikal and Nagore,reveals that the mean grain size exhibits a marked decreasing trend on either side of the mouth of the Tirumalairajanar River which flow from west to *** sediments are mainly of medium to coarse grained,moderately sorted,near-symmetrical skewed to fine skewed and leptokurtic to mesokurtic in *** of various parameters shows bimodal nature of sediments having dominance of medium to coarse *** major part of the sediment fall in a coarse to fine grained category(sand and silt).Based on the CM(Coarser one percentile value in micron) pattern,the sediment fall in rolling and suspension *** factors includes the sediments discharged from the river mixes with offshore sediments and with the sediments eroded from a source *** effect of wave sorting, and the northward drifting of sediments by littoral current are *** indicate that the Tirumalairajanar River is the most important source for modern sediments in the study *** agitation by waves is an important sorting mechanism in the study area,and the net sediment transport in the study area is *** findings are based on the grain sizes and also corroborated by shortterm observations of the beach sediment dynamics and transport during the monsoon and summer seasons between karaikal and Nagore region.

关键词： Grain size analysis Beach sediments Tirumalairajanr East coast