Coimbatore Institute of Technology
Coimbatore, India

The Coimbatore Institute of Technology is Government-aided Autonomous engineering college located in Coimbatore, Tamil Nadu, India. It was founded in 1956 by V.Rangaswamy Naidu Educational Trust with the aim of disseminating knowledge in the fields of science, engineering and technology. It is affiliated to Anna University. The Institute was granted autonomous status in 1987 and is recognized by the AICTE and NAAC. Wikipedia.

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Thyageswaran S.,Coimbatore Institute of Technology
Heat Transfer Engineering | Year: 2017

A closed-form and easy-to-use analytical expression is derived for calculating the radiation view factor between a pair of dissimilar rectangular surfaces facing each other from two different parallel planes. The alignment of the rectangles is such that: (i) a line joining their centers would be normal to both surfaces, and (ii) observed in a plan view in the direction of this shared axis, the rectangles are not turned by an angle relative to each other. Strangely enough, a simple formula for finding view factors for this configuration is not available at present in well-known references on this topic. The usefulness of the proposed expression, for quick calculations of view factors, is demonstrated with examples. It is shown that this generalized expression can be readily specialized to a few well-documented view factor formulae. It can be easily extended for view factor calculations involving pairs of unequal and non-aligned parallel rectangular surfaces, making it a flexible and handy result for heat transfer pedagogy. © 2017 Taylor & Francis Group, LLC.

Anusuya N.,Coimbatore Institute of Technology | Manian S.,Bharathiar University
International Journal of Pharmacy and Pharmaceutical Sciences | Year: 2013

Indigofera tinctoria L. (Fabaceae) is traditionally used in Indian and Chinese medicinal systems for various ailments including cancer, liver disorder, inflammation, ulcers and nervous disorders. Since the said curative effects are often related to antioxidant properties, different solvent (petroleum ether, benzene, chloroform, ethyl acetate, methanol and water) extracts of I. tinctoria leaves were evaluated for the antioxidant and free radical scavenging potentialby employing different in vitro assays such as reducing power assay, DPPH•, ABTS•+, NO• and•OH radical scavenging capacities, peroxidation inhibiting activity through linoleic acid emulsion system, antihemolytic assay through hydrogen peroxide induced hemolytic cells and metal ion chelating ability. Ethyl acetate, water and methanol extracts exhibited higher phenolic and tannin contents whereas benzene and ethyl acetate extracts showed higher flavonoid contents. Though all the extracts exhibited reducing power, the ethyl acetate extract was found to have more hydrogen donating ability. Ethyl acetate extract further exhibited higher DPPH• and NO• scavenging activities. All the studied extracts exhibited 22-56% •OH scavenging activities at 250μg concentration in the reaction mixture and strong peroxidation inhibition against linoleic acid emulsion system (87-96%). Methanol extract registered strong ABTS•+ scavenging activity (1434. 5 ± 236. 8 μmolg-1DM). The potential of multiple antioxidant activity of this plant is evident as the extracts possessed antihemolytic and metal ion chelating activities.

Senthilnathan B.,Coimbatore Institute of Technology
RAIRO - Operations Research | Year: 2017

In this paper, a single server queue with variable batch size service, Poisson bulk arrival with multiple working vacations and server breakdown is considered. In working vacation, the server works with different rates rather than completely stoping the service during the vacation period. In this model, during the working vacation the server starts the service if it finds at least one customer in the queue with a maximum of 'b' customers, otherwise the server serves with variable batch size. Service time in working vacation and in regular period follows general distribution. The probability generating function of a queue size at an arbitrary time epoch as well as other completion epochs is derived. Expected queue length in a steady state is obtained. Also a numerical illustration is presented. © 2017 EDP Sciences, ROADEF, SMAI.

Shanmuga Sundaram N.,PSG College of Technology | Murugan N.,Coimbatore Institute of Technology
Materials and Design | Year: 2010

The heat treatable aluminium alloy AA2024 is used extensively in the aircraft industry because of its high strength to weight ratio and good ductility. The non-heat treatable aluminium alloy AA5083 possesses medium strength and high ductility and used typically in structural applications, marine, and automotive industries. When compared to fusion welding processes, friction stir welding (FSW) process is an emerging solid state joining process which is best suitable for joining these alloys. The friction stir welding parameters such as tool pin profile, tool rotational speed, welding speed, and tool axial force influence the mechanical properties of the FS welded joints significantly. Dissimilar FS welded joints are fabricated using five different tool pin profiles. Central composite design with four parameters, five levels, and 31 runs is used to conduct the experiments and response surface method (RSM) is employed to develop the model. Mathematical regression models are developed to predict the ultimate tensile strength (UTS) and tensile elongation (TE) of the dissimilar friction stir welded joints of aluminium alloys 2024-T6 and 5083-H321, and they are validated. The effects of the above process parameters and tool pin profile on tensile strength and tensile elongation of dissimilar friction stir welded joints are analysed in detail. Joints fabricated using Tapered Hexagon tool pin profile have the highest tensile strength and tensile elongation, whereas the Straight Cylinder tool pin profile have the lowest tensile strength and tensile elongation. The results are useful to have a better understanding of the effects of process parameters, to fabricate the joints with desired tensile properties, and to automate the FS welding process. © 2010 Elsevier Ltd.

Murugan N.,Coimbatore Institute of Technology | Ashok Kumar B.,Erode Builder Educational Trusts Group of Institutions
Materials and Design | Year: 2013

Over the last two decades, aluminium matrix composites (AMCs) reinforced with particulate form of ceramics have attracted much attention due to their superior mechanical properties. In recent years, friction stir welding (FSW) is largely employed to successfully join the AMCs reinforced with ceramic particulates. An attempt has been made to develop a regression model to predict the ultimate tensile strength (UTS) of the friction stir (FS) welded AA6061 matrix composite reinforced with aluminium nitride particles (AlNp) by incorporating significant parameters such as tool rotational speed, welding speed, axial force and percentage of AlNp reinforcement in the matrix. A four factor, five level central composite rotatable design has been used to minimize the number of experimental runs. The effects of those factors on UTS of the welded joints have been analyzed using the developed regression model. The developed regression model has been validated by statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student's t test. It was found that the model was accurate. The developed regression model can be effectively used to predict the UTS of FS welded joints at 95% confidence level. It was observed from the investigation that factors considered in this study independently influenced the UTS of the FS welded composite joints. © 2013 Elsevier Ltd.

Ashok Kumar B.,Erode Builder Educational Trusts Group of Institutions | Murugan N.,Coimbatore Institute of Technology
Materials and Design | Year: 2012

An attempt has been made to manufacture aluminium (6061-T6) matrix composites reinforced with aluminium nitride particles (AlNp) of size 3-4μ using indigenously developed modified stir casting method with bottom pouring arrangement in controlled argon environment. To improve the wettability of AlNp with molten Al matrix, 2% Mg has been added. AA6061-AlNp composites have been successfully produced at different weight percentages (viz 0, 5, 10, 15 and 20) of AlNp and their metallurgical and mechanical properties have been analysed. Macrohardness, microhardness, Yield strength and ultimate tensile strength of the composite have improved with the addition of AlNp in the Al matrix. Optical and SEM micrographs reveal the homogeneous distribution of reinforcement particles in the matrix and X-ray diffraction patterns ensure the dispersion of AlNp reinforcement in AA6061 matrix. © 2012 Elsevier Ltd.

Gopalakrishnan S.,KS Rangasamy College of Technology | Murugan N.,Coimbatore Institute of Technology
Materials and Design | Year: 2011

The usage of particulate reinforced metal matrix composite (MMC) is steadily increasing due to its properties such as high specific strength, high specific modulus and good wear resistance. Aluminium matrix composite (AMC) plays an important role to meet the above requirements. Effective utilization of AMC is based on not only its production but also on fabrication methods. Among AMCs, those based on particulate reinforcements are particularly attractive, due to their lower production costs. Aluminium matrix titanium carbide reinforced composite (Al-TiCp) was produced in an inert atmosphere by indigenously developed Modified Stir Casting Process with bottom pouring arrangement (3-7% TiC by weight). Friction stir welding process (FSW) is employed to make weld joints. The welding parameters such as axial force, welding speed, tool rotational speed, percentage TiC addition etc., and profile of the tool were considered for analysis. In this study, an attempt is made to predict ultimate tensile strength (UTS) of the welded joints using a mathematical model. The FSW specimens without any post-weld heat treatment belonging to a different set of parameters tested, exhibited a high joint efficiency (most of them ranging from 90% to 98%) with respect to the ultimate tensile strength of the base material AA6061. It was found from the analysis of the model that the tool pin profile and the welding speed have more significant effect on tensile strength. © 2010 Elsevier Ltd.

Thyageswaran S.,Coimbatore Institute of Technology
Applied Thermal Engineering | Year: 2016

An arrangement is proposed for a four-stroke internal combustion engine to: (a) recover thermal energy from products of combustion during the exhaust stroke; (b) store that energy as sensible heat in a micro-channel regenerator matrix; and (c) transfer the stored heat to compressed fresh charge that flows through the regenerator during the succeeding mechanical cycle. An extra moveable piston that can be locked at preferred positions and a sequence of valve events enable the regenerator to lose heat to the working fluid during one interval of time but gain heat from the fluid during another interval of time. This paper examines whether or not this scheme for in-cylinder regeneration (ICR) improves the cycle thermal efficiency ηI. Models for various thermodynamic processes in the cycle and treatments for unsteady compressible flow and heat transfer inside the regenerator are developed. Digital simulations of the cycle are made. Compared to an idealized engine cycle devoid of regeneration, provisions for ICR seem to deteriorate the thermal efficiency. In an 8:1 compression ratio octane engine simulated with an equivalence ratio of 0.75, ηI = 0.455 with regeneration and ηI = 0.491 without. This study shows that previous claims on efficiency gains via ICR, using highly-simplified models, may be misleading. © 2015 Elsevier Ltd. All rights reserved.

Gopalakrishnan S.,KS Rangasamy College of Technology | Murugan N.,Coimbatore Institute of Technology
Composites Part B: Engineering | Year: 2012

Metal matrix composite (MMC) focuses primarily on improved specific strength, high temperature and wear resistance application. Aluminium matrix reinforced with titanium carbide (Al-TiC p) has good potential. The main challenge is to produce this composite in a cost effective way to meet the above requirements. In this study Al-TiC p castings with different volume fraction of TiC were produced in an argon atmosphere by an enhanced stir casting method. Specific strength of the composite has increased with higher % of TiC addition. Dry sliding wear behaviour of AMC was analysed with the help of a pin on disc wear and friction monitor. The present analyses reveal the improved specific strength as well as wear resistance. © 2011 Elsevier Ltd. All rights reserved.

Lakshmi K.,KS Rangasamy College of Technology | Vasantharathna S.,Coimbatore Institute of Technology
International Journal of Electrical Power and Energy Systems | Year: 2014

This paper presents an Artificial Immune System approach for solving generation scheduling problem of a Genco comprised of thermal and wind energy systems. Wind-thermal scheduling problem determine the time of instant to start up and shut down the generating units over a scheduled time period, while satisfying the 'system' and 'generator' constraints including minimum up/down time; ramp rate limits of thermal units and wind power constraints. In this work, the impact of wind energy on short term generation scheduling problem is analyzed through the adaptive search which is inspired from the Artificial Immune System. The effectiveness of the proposed approach is demonstrated through a Genco consists of 10 thermal units with 2 wind farms and the results for the near optimal schedule are discussed. © 2013 Elsevier Ltd. All rights reserved.

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