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Journal of rare Earths 2015年第2期33卷 160-167页

作者： M.Bradha T.Vijayaraghavan S.P.Suriyaraj r.selvakumar Anuradha M.Ashok Nanotech research Facility PSG Institute of Advanced StudiesCoimbatore-641 004 India Nanobiotechnology Laboratory PSG Institute of Advanced StudiesCoimbatore-641 004 India

A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites were prepared by sol-gel method and characterized using thermogravimetry/differential thermal analysis（TGA/DTA）, X-ray diffraction（XrD）, ultraviolet-visible（UV-Vis） spectroscopy and transmission electron microscopy（TEM）. XrD analysis showed that the La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites derived after calcination at 800 oC were in single phase with orthorhombic structure. The particle size of all nano perovskites was found to be ~20 nm. The synthesized nano perovskites were tested for the photocatalytic decomposition of an azo dye, Congo red. The sequential behavior of La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nanoperovskites for photocatalytic decomposition of congo red in aqueous solution by visible light at room temperature was studied at various time intervals and the efficiency of degradation of the nanoperovskites was compared. Among all the A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites, Ba substituted compound showed the highest dye degradation.

关键词： nano perovskite oxidation photocatalyst congo red dye degradation rare earths

High-Velocity Projectile Impact Behaviour of Friction Stir Welded AA7075 Thick Plates

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Defence Technology（防务技术） 2023年第11期29卷 153-163页

作者： r.Praveen S.r.Koteswara rao G.selvakumar r.Damodaram Department of robotics and Automation Karpaga Vinayaga College of Engineering and TechnologyChengalpattu603308TamilNaduIndia Department of Mechanical Engineering Sri Sivasubramaniya Nadar College of EngineeringChennai603110TamilNaduIndia

In this study, high velocity impact behaviour of friction stir welded AA7075-T651 25 mm thick plates were investigated using a 7.62 mm × 51 mm lead core and 7.62 mm × 39 mm steel core projectiles. Prior to ballistic trails, mechanical and metallurgical properties of friction stir welded AA 7075-T651 25 mm thick plates were studied. Microstructural and hardness studies revealed that friction stir welds constituted three distinct regions namely Weld Nugget(WN), Thermo-Mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). Base Material(BM) and all three weld regions were ballistically tested as per military standard NIJ.0108.01 using lead and steel core bullets at maximum permissible velocities of 830 ± 20 and 700 ± 30 m/s, respectively. It has been found that base material(AA7075-T651)and all three weld regions of 25 mm thick plates were able to resist perforation by both types of projectiles used. However depth of penetration has been found to increase from BM to WN, HAZ and TMAZ for both types of projectiles. In all cases steel core projectiles caused higher depth of penetration compared to those caused by lead core projectiles. TMAZs of the friction stir welds were found to be the weakest zone. The fracture that occurred in the base material was spall fragmentation indicating brittle failure, whereas all zones of friction stir welded AA7075-T651 targets with a front petalling, indicating ductile failure. The post-ballistic tested samples showed no significant change in the microstructure of the BM and WN. On the other hand, TMAZ and HAZ showed severe grain deformation in the direction of projectile penetration, and the formation of adiabatic shear bands(ASB). This work showed that 25 mm thick friction stir welded AA7075-T651 joints responded well to ballistic impact loads, making them a good choice for light combat vehicles.

关键词： Aluminum alloy Thick plate Friction stir welding Ballistic performance Depth of penetration

Local outlier factor and stronger one class classifier based hierarchical model for detection of attacks in network intrusion detection dataset

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Frontiers of Computer Science 2016年第4期10卷 755-766页

作者： Alampallam ramaswamy VASUDEVAN Subramanian selvakumar CDBr-SSE Lab Department of Computer Science and Engineering National Institute of Technology Tiruchirappalli (NITT) Tiruchirappalli 620015 India

Identification of attacks by a network intrusion detection system （NIDS） is an important task. In signature or rule based detection, the previously encountered attacks are modded, and signatures/rules are extracted. These rules are used to detect such attacks in future, but in anomaly or outlier detection system, the normal network traffic is modeled. Any deviation from the normal model is deemed to be an outlier/attack. Data mining and machine learning techniques are widely used in offline NIDS. Unsupervised and supervised learning techniques differ the way NIDS dataset is treated. The characteristic features of unsupervised and supervised learning are finding patterns in data, detecting outliers, and determining a learned function for input features, generalizing the data instances respectively. The intuition is that if these two techniques are combined, better performance may be obtained. Hence, in this paper the advantages of unsupervised and supervised techniques are inherited in the proposed hierarchical model and devised into three stages to detect attacks in NIDS dataset. NIDS dataset is clustered using Dirichiet process （DP） clustering based on the underlying data distribution. Iteratively on each cluster, local denser areas are identified using local outlier factor （LOF） which in turn is discretized into four bins of separation based on LOF score. Further, in each bin the normal data instances are modeled using one class classifier （OCC）. A combination of Density Estimation method, reconstruction method, and Boundary methods are used for OCC model. A product rule combination of the three methods takes into consideration the strengths of each method in building a stronger OCC model. Any deviation from this model is considered as an attack. Experiments are conducted on KDD CUP＇99 and SSENet-2011 datasets. The results show that the proposed model is able to identify attacks with higher detection rate and low false alarms.

关键词： hierarchical model DP clustering LOF Dis-cretizer one class classifier NIDS

Organic micro-pollutant removal in liquid-phase using carbonized silk cotton hull

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Journal of Environmental Sciences 2008年第9期20卷 1046-1054页

作者： M Sathishkumar A r Binupriya D Kavitha r.selvakumar K K Sheema J G Choi Department of Food Science and Technology Institute of Agricultural Science and Technology Chonbuk National University Department of Chemical Engineering Yonsei University Department of Biotechnology Bharathiar University Department of Plant biology and Biotechnology Government Arts College National Agricultural Products Quality Management Services

Phenolic compounds constitute one of the major pollutants in the modern world. Although many physical and chemical treatment technologies for their removal exist, most of them are economically not feasible. The present study was aimed at using silk cotton hull, a potent agricultural waste as an adsobent for removal of 2,4-dichlorophenol (2,4-DCP), which was used as a model phenolic compound. The process parameters were investigated and optimized conditions were determined. The equilibrium time was found to ...

关键词： silk cotton hull carbon adsorption 2 4-DCP temperature kinetic study

Fatigue crack growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combined torsion and bending load

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Frontiers of Structural and Civil Engineering 2021年第4期15卷 905-913页

作者： selvakumar VEErArAJAN Dakshinamurthy PUKAZHENDHI Palla GANDHI Department of Civil Engineering Taipei University of TechnologyTaipei106-08China Fatigue&Fracture Laboratory CSIR-Structural Engineering Research CentreChennai600113India

In a nuclear powerplant,the rotary equipment,such as a pump directly fitted with hanger in the piping system,experiences torsional and bending *** crack growth rate occurs because of this torsional load in addition to the bending ***,it is necessary to study the fatigue behavior of piping components under the influence of combined torsional and bending *** this study,experimental fatigue life evaluation was conducted on a notched stainless steel SA312 Type 304LN straight pipe having an outer diameter of 170 *** experimental crack depth was measured using alternating current potential drop *** fatigue life of the stainless steel straight pipe was predicted using experiments,Delale and Erdogan method,and area-averaged root mean square-stress intensity factor approach at the deepest and surface points of the ***,the fatigue crack growth and crack pattern were *** a result,fatigue crack growth predicted using analytical methods are in good agreement with experimental results.

关键词： fatigue life Delale and Erdogan method rMS-SIF approach stainless steel torsion and bending load fatigue crack growth

Enhanced Mechanism for Link Failure rerouting in Software-Defined Exchange Point Networks

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Computers, Materials & Continua 2024年第9期80卷 4361-4385页

作者： Abdijalil Abdullahi selvakumar Manickam Department of Information Technology SIMAD UniversityMogadishu630Somalia National Advanced IPv6 Centre Universiti Sains MalaysiaPulua Pinang11800Malaysia

Internet Exchange Point(IXP)is a system that increases network bandwidth *** exchange points facilitate interconnection among network providers,including Internet Service Providers(ISPs)andContent Delivery Providers(CDNs).To improve service management,Internet exchange point providers have adopted the Software Defined Network(SDN)*** implementation is known as a Software-Defined Exchange Point(SDX).It improves network providers’operations and ***,performance issues still exist,particularly with multi-hop *** issues include switch memory costs,packet processing latency,and link failure recovery *** paper proposes Enhanced Link Failure rerouting(ELFr),an improved mechanism for rerouting link failures in software-defined exchange point *** proposed mechanism aims to minimize packet processing time for fast link failure recovery and enhance path calculation efficiency while reducing switch storage overhead by exploiting the Programming Protocol-independent Packet Processors(P4)*** paper presents the proposed mechanisms’efficiency by utilizing advanced algorithms and demonstrating improved performance in packet processing speed,path calculation effectiveness,and switch storage management compared to current *** proposed mechanism shows significant improvements,leading to a 37.5%decrease in recovery Time(rT)and a 33.33%decrease in both Calculation Time(CT)and Computational Overhead(CO)when compared to current *** study highlights the effectiveness and resource efficiency of the proposed mechanism in effectively resolving crucial issues inmulti-hop software-defined exchange point networks.

关键词： Link failure recovery Internet exchange point software-defined exchange point software-defined network multihop topologies

Ideal-Based k-Zero-Divisor Hypergraph of Commutative rings

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Algebra Colloquium 2021年第4期28卷 655-672页

作者： K.selvakumar M.Subajini Department of Mathematics Manonmaniam Sundaranar University Tirunelveli 627012Tamil NaduIndia

Let r be a commutative ring,I an ideal of r and k≥2 a fixed *** ideal-based k-zero-divisor hypergraph HkI(r)of r has vertex set ZI(r,k),the set of all ideal-based k-zero-divisors of r,and for distinct elements x1,x2,…,xk in ZI(r,k),the set{x1,x2,…,xk}is an edge in HkI(r)if and only if x1x2…xk∈I and the product of the elements of any(k-1)-subset of{x1,x2,…,xk}is not in *** this paper,we show that H3I(r)is connected with diameter at most 4 provided that x^(2)(∈)I for all ideal-based 3-zero-divisor ***,we find the chromatic number of H3(r)when r is a product of finite ***,we find some necessary conditions for a finite ring r and a nonzero ideal I of r to have H3I(r)planar.

关键词： hypergraph zero-divisor graph linear local ring k-prime ideal

Watershed Prioritization of Palar Sub-watershed Based on the Morphometric and Land Use Analysis

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Journal of Mountain Science 2014年第4期11卷 906-916页

作者： Evangelin ramani SUJATHA radhakrishnan selvakumar Balasubramaniam rAJASIMMAN School of Civil Engineering SASTRA University Thanjavur 613 401Tamilnadu India Centre for remote Sensing Bharathidasan UniversityTiruchirapalli 620003 India

Morphometric analysis is an indispensable tool for hydrological investigation that involves the development and management of drainage basin. This study characterizes the micro watersheds in the Palar sub-watershed using morphometric analysis and assesses its risk by land use and land cover features in a particular micro watershed. Palar sub-watershed is divided into 6 micro watersheds for prioritization based on morphometric and land use analysis. Several morphometric parameters （linear, shape and relief） are determined from the drainage map; ranks are assigned based on their capacity to induce erodability and degradation. Final ranking is based on the composite index calculated from the sum of the ranks of each morphometric parameter. Morphometric analysis reveals micro watersheds 5 and 6 as most susceptible and 2 and 3 as low susceptible. Land use is mapped using IrS ID LISS III satellite data. The risk in terms of watershed degradation involved to each micro watershed is based on the ranks of each land use feature, obtained from a similar composite index as that of morphometric analysis. Land use analysis shows that micro watersheds 2 and 4 fall under high priority category while 5 and 6 under low priority category. Integration of the morphometric and land use analysis shows that only microwatershed 1 falls under the same category in both analyses. Control measures are suggested to contain degradation depending on its specific land use pattern and morphometric features. This study ean be used to prepare a comprehensive watershed plan for the development or for planning resource conservation strategies, by integrating land use features with the drainage characteristics of the region, in particular for a hill ecosystem as the prioritization is at micro level.

关键词： Morphometric analysis Watersheddeterioration risk Land use Palar sub-watershed Kodaikkkanal

An Improved Lifetime and Energy Consumption with Enhanced Clustering in WSNs

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Intelligent Automation & Soft Computing 2023年第2期35卷 1939-1956页

作者： I.Adumbabu K.selvakumar Department of Electronics&Communication Engineering Annamalai UniversityChidambaram608002India Department of Information Technology Annamalai UniversityChidambaram608002TamilnaduIndia

Awireless sensor network(WSN)is made up of sensor nodes that communicate via radio waves in order to conduct sensing *** WSN,the location of the base station is *** base stations are fixed,they may move in response to data received from sensor nodes under specific *** is a highly efficient approach of minimising energy *** issues of extending the life of WSNs and optimising their energy consumption have been addressed in this *** has been established that integrating mobile sinks into wireless sensor networks extends their ***,this research proposes an optimal clustering and routing technique for optimising the energy usage and lifetime of *** minimise energy consumption,this research employs movable and stationary sink *** K-Medoid clustering model is used to generate the initial number of nodes in the various *** that,the cluster head is chosen using a hybrid Interval Type-2 Fuzzy technique that takes three aspects into account:residual energy,node centrality,and neighbourhood.A highly efficient backup cluster head(CH)collecting system can provide in significant energy savings while also prolonging the system’s ***,better reinforcement learning combined with a Genetic algorithm routing protocol is used to ensure effective data *** suggested approach’s efficacy is evaluated in comparison to earlier approaches utilising residual node energy,delay or average delay,packet delivery ratio,throughput,network longevity,average energy consumption,and multiple alive *** experiments,the proposed strategy outperforms existing strategies.

关键词： Fuzzy logic genetic algorithm wireless sensor networks routing

Growth and Characterization of Organic NLO Crystal:β-Naphthol

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Journal of Materials Science & Technology 2011年第3期27卷 271-274页

作者： S.Janarthanan r.Sugaraj Samuel S.selvakumar Y.C.rajan D.Jayaraman S.Pandi Department of Physics Presidency College Department of Chemistry Presidency College Department of Physics L.N.Govt.College Department of Material Science Engineering National Chiao Tung University

Single crystals of β-Naphthol （/3N）, an organic nonlinear optical （NLO） material was successfully grown by temperature lowering method using chloroform as solvent. The initial compound was purified by repeated recrystallization process. As-grown crystals were characterized by single crystal X-ray diffraction （XrD） studies to ascertain that βN crystal crystallized in the monoclinic system with a noncemtrosymmetric space group. Vibrational frequencies of various functional groups in the crystals were derived from Fourier transform infrared （FTIr） spectroscopy and proton nuclear magnetic resonance （NMr） spectrum. Optical characterization was done using UV-Visible near-infrared （NIr） spectroscopy. The thermal behaviour of the material was studied by thermo gravimetric and differential thermal plots. Scanning electron microscopy （SEM） study was carried out on the surface of the grown crystals to investigate the nature of defects in the crystal surface and the NLO property of the crystal was tested by Nd：YAG laser as a source.

关键词： Crystal growth Fourier transform infrared (FTIr) spectroscopy Nonlinear optical crystal Scanning electron microscopy (SEM)