Showing papers by "Nitte Meenakshi Institute of Technology published in 2010"

Analysis of fluid flow in centrifugal casting

Abstract: Centrifugal casting process is a fast process with melt, cast and moulds being opaque It is almost impossible to observe the melt behavior during casting Cold modeling experiments were conducted using horizontal transparent moulds and transparent fluids of different viscosities to study the effect of different process variables on the flow pattern Effects of the thickness of fluid cylinder, viscosity of the fluid, diameter of the mould, and rotational speed of the mould on the formation of complete hollow fluid cylinder are investigated The influence of rotational speed has been studied in aluminum casting The cylinders are cast at different rotational speed with varying thickness It is observed that the speed required to form uniform cylinder increases with the increase in thickness of a fluid cylinder As rotational speed is increased the hardness of the cast cylinder also increases The flow patterns seen in cold modeling experiments and actual castings agree reasonably well

Influence of rotational speed of centrifugal casting process on appearance, microstructure, and sliding wear behaviour of Al-2Si cast alloy

Abstract: Although the manner in which the molten metal flows plays a major role in the formation of the uniform cylinder in centrifugal casting, not much information is available on this topic. The flow in the molten metal differs at various rotational speeds, which in turn affects the final casting. In this paper, the influence of the flow of molten metal of hyper eutectic Al-2Si alloys at various rotational speeds is discussed. At an optimum speed of 800 rpm, a uniform cylinder was formed. For the rotational speeds below and above these speeds, an irregular shaped casting was formed, which is mainly due to the influence of melt. Primary a-Al particles were formed in the tube periphery at low rotational speed, and their sizes and shapes were altered with changes in rotational speeds. The wear test for the inner surface of the casting showed better wear properties for the casting prepared at the optimum speed of rotation.

Characterization and wear behavior of plasma-sprayed Al2O3 and ZrO25CaO coatings on cast iron substrate

Abstract: Plasma spraying is one of the methods used for combating wear. Despite of its wide spread industrial use, little is known about the basic friction behavior and mechanism by which such coatings wear. In this work, the abrasive wear resistance of plasma-sprayed ceramic coatings on cast iron substrate has been investigated through pin-on-disc test. It was found that the coefficient of friction and wear affected mainly by splats and porosity, surface roughness, and coating thickness. The coefficient of friction is found to be more significantly affected by load than by other test parameters. This work also includes the characterization of coatings.

FPGA implementation of network on chip framework using HDL

Abstract: Traditional System on Chip (SOC) designs offer integrated solutions to exigent design tribulations in areas which necessitate outsized computation and restriction in certain area. But the performance of these has been sluggish due to the restriction of the common bus architecture espoused by these systems and thereby low processing speeds. This has been the main stumbling block for scalability in terms of computation and enhancement in its performance. With the advancement in semi conductor devices and fabrication technology, it is possible to pack more logic in smaller area of silicon. But the implementation of these mega functional modules using common bus architecture, parallel bus architecture, pipelining are becoming ineffective and posing a bottleneck in terms of performance and throughput in this billion transistor era. As an elucidation for this problem, Network on chip is being adopted in this paper as the core bus architecture across different spectrum of SOCs. Our approach presents a supple design using FPGA based system. Hence, it is a very flexible network design that will accommodate to various needs.

Synthesis, Characterization & Impedance Studies of some New Nano Filtration Membranes

Abstract: In the recent years membrane technology has gained significant attention from polymer chemists all around the world due to their attractive features such as efficiency, low costs, low energy costs and as effective solutions to longstanding problems in the chemical industries. Membrane technologies have been widely applied in the separation of liquids and even gases. Many separation problems can be solved economically by nanofiltration alone or in combination with other separation processes. This study aimed to synthesize polysulfone based nanofiltration membranes using DIPS (diffusion induced phase separation) technique. Newly synthesized polymer membranes were subjected to Infra red spectral and water uptake studies. Membranes were also characterized using electrochemical spectroscopy for their proton conducting property. Their surface morphology is visualized by SEM.

Numerical Simulation of Incompressible Turbulent Flow using Linear Eddy Viscosity-based Turbulence Models

Abstract: The present study focuses on the recent development of an implicit pressure-based finite volume algorithm for numerical solution of Reynolds averaged Navier-Stokes equations (RANS) in an inertial frame of reference for the prediction of unsteady incompressible flow problems. The algorithm uses boundary-conforming, multiblock structured grid with moving boundaries, collocated variable arrangement with momentum equations resolved along cartesian directions, second-order accurate spatial and temporal discretisation schemes for the convective fluxes and a pressure-velocity solution strategy. Effect of turbulence was simulated using appropriate linear eddy viscosity-based turbulence models. The capabilities and limitations of the cost-effective unsteady Reynolds averaged Navier-Stokes (URANS) approach has been demonstrated for few application problems of engineering interest. Defence Science Journal, 2010, 60(6), pp.614-627 , DOI:http://dx.doi.org/10.14429/dsj.60.603

Corona pulse rise time measurements between point plane electrodes in atmospheric air

Abstract: Extremely fast rate of rise voltage and current pulses (rate of rise in range of few tens of nanoseconds) are of great importance in recent years. They have applications in electrostatic Discharges (ESD) and Electromagnetic interference. Also, in medical sciences, fast rate of rise voltages with rise time in range of few nanoseconds are used for study of electroporation effects in biological cells. In view of these considerations experimental investigations have been carried out using point plane gaps for the positive polarity of the point electrode in atmospheric air under fair weather conditions for determination of corona pulse voltage rise time at instant of corona inception. The radii of tip of hemispherically capped cylindrical electrode varied from 0.5mm to 1.5mm and the gap spacing from 10mm to 50mm (approximately). Also, the phenomena have been investigated using electroplated brass electrodes, the electroplated materials being Nickel, Chromium and silver. The minimum rise time of corona pulse obtained in these experiments is 35 nanoseconds. In all these experiments the input voltage was increased continuously (rate of rise 2KV/Sec) from near zero value upto occurrence of corona inception voltage and results are characterized as steady state corona inception. Another set of experimental investigations has been carried out by applying overvoltage with extremely fast rise voltage to a point plane electrode system which is kept energized at a steady potential by applying a steady DC voltage of magnitude equal to 65% value of the steady corona inception voltage. The peak value of overvoltage corresponds to magnitude of voltage, which can cause 108 electron multiplications (threshold multiplication for streamer formation) close to the point electrode (highly non uniform field electrode configuration). The calculation of field intensities and electron multiplication have been made using ANSYS software version 9.0 (multiphysics) and numerical method. These investigations have shown that the rise time of pulse can be decreased from 80 nanoseconds which is the value recorded for the steady state corona inception phenomena. The reduced value in rise time can be 30 nanoseconds (approximately) for the case of overvoltage applied to point plane gap for hemispherical tip diameter of 1mm and gap distance of 10mm in atmospheric air under fair weather conditions.

N-[(4-Amino-5-sulfanyl­idene-4,5-dihydro-1H-1,2,4-triazol-3-yl)meth­yl]-4-methyl­benzamide

Abstract: In the title compound, C11H13N5OS, the dihedral angle between the triazole ring and the benzene ring is 84.21 (7)°. The amino group adopts a pyramidal configuration. An intra­molecular N—H⋯O hydrogen bond stabilizes the mol­ecular structure and generates an S(8) ring. In the crystal, mol­ecules are linked by inter­molecular N—H⋯O, N—H⋯S, N—H⋯N and C—H⋯S hydrogen bonds into layers lying parallel to the bc plane. The crystal structure is further stabilized by aromatic π–π stacking inter­actions [centroid–centroid distance = 3.3330 (7) A].