Showing papers by "Nitte Meenakshi Institute of Technology published in 2011"
01 Feb 2011-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this article, numerical simulations of the flow field and visualization experiments on cold models have been carried out for a centrifugal casting system using horizontal molds and fluids of different viscosities to study the effect of different process variables on the flow pattern.
Abstract: In a centrifugal casting process, the fluid flow eventually determines the quality and characteristics of the final product. It is difficult to study the fluid behavior here because of the opaque nature of melt and mold. In the current investigation, numerical simulations of the flow field and visualization experiments on cold models have been carried out for a centrifugal casting system using horizontal molds and fluids of different viscosities to study the effect of different process variables on the flow pattern. The effects of the thickness of the cylindrical fluid annulus formed inside the mold and the effects of fluid viscosity, diameter, and rotational speed of the mold on the hollow fluid cylinder formation process have been investigated. The numerical simulation results are compared with corresponding data obtained from the cold modeling experiments. The influence of rotational speed in a real-life centrifugal casting system has also been studied using an aluminum-silicon alloy. Cylinders of different thicknesses are cast at different rotational speeds, and the flow patterns observed visually in the actual castings are found to be similar to those recorded in the corresponding cold modeling experiments. Reasonable agreement is observed between the results of numerical simulation and the results of cold modeling experiments with different fluids. The visualization study on the hollow cylinders produced in an actual centrifugal casting process also confirm the conclusions arrived at from the cold modeling experiments and numerical simulation in a qualitative sense.
34 citations
TL;DR: In this paper, polysulfone based composite nanofiltration (NF) membranes were synthesized and characterized by FT-IR, SEM and membrane performance studies, and the modification effect was characterized in terms of contact angle, AFM employed roughness measurement and dielectric property.
23 citations
05 Mar 2011
TL;DR: The steps involved in design, development and fabrication of a Pico-satellite ‘STUDSAT’: STUDent SATellite along with the development of ground station that is capable of communicating with STUDSats elaborates upon the different subsystems in the satellite.
Abstract: In the era of development of space technology, miniaturization plays a vital role in low cost small satellite missions. 12The versatile application capabilities and low cost of Pico/Nano satellites missions make them attractive for a wide scope of space exploration projects. This paper outlines the steps involved in design, development and fabrication of a Pico-satellite ‘STUDSAT’: STUDent SATellite along with the development of ground station that is capable of communicating with STUDSAT. It elaborates upon the different subsystems in the satellite. The satellite falls in the category of pico satellites, where the mass of satellite is restricted to 1 Kg and volume to 1.1 liters. The overall dimension of the satellite is (10 × 10 × 13.5) cm. The satellite is capable of capturing images of ground resolution 90 meters at an altitude of 680 Kms. The STUDSAT was launched with ISRO's PSLV C-15 on 12th July 2010 as a secondary payload. Further, the paper elaborates on the beacon and telemetry data that were received from the satellite. The satellite mission was terminated officially after 3 months from its launch date. The paper also presents the analysis on failures that had caused early termination of STUDSAT mission.
10 citations
TL;DR: The work done on Retinex so far is presented and a method to reduce the halo artifacts for better performance of human vision system is proposed.
Abstract: In recent days, with the increasing use of digital camera capturing and rendering a good image is not a trivial task. Recorded images differ from direct view to the lack of dynamic range compression and colour constancy. Dynamic range is the ratio of the largest value to the smallest value of a physical quantity. Dynamic range of a scene is the ratio of the brightest and darkest part of the scene. The range of human vision system is quite large. The luminance of starlight is around 0.001 cd/m 2 to that of a sunlit is around 100,000 cd/m 2 , which is hundred million times higher. The human eye can accommodate a
9 citations
01 Dec 2011
TL;DR: In this paper, a grade-based two-level node selection method along with genetic algorithm (GA) is proposed for realizing an efficient routing scheme, which assumes that the nodes are intelligent and that there exists a knowledge base about the environment in their local memory.
Abstract: In the past decade, significant research has been carried out for realizing intelligent network routing using advertisement, position and near-optimum node selection schemes. In this paper, a grade-based two-level node selection method along with genetic algorithm (GA) is proposed for realizing an efficient routing scheme. This method assumes that the nodes are intelligent and that there exists a knowledge base about the environment in their local memory. There are two levels for approaching the effective route selection process through grading. At the first level, grade-based selection is applied and at the second level, the optimum path is explored using GA. The simulation has been carried out on different topological structures, and a significant reduction in time is achieved for determining the optimal path through this method compared to the non-graded networks.
9 citations
TL;DR: In this paper, the effect of the motion of molten metal at various speeds and its effect during casting is addressed and the Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds.
Abstract: True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds is discussed.
9 citations
01 Jan 2011
TL;DR: In this article, the effect of global and local image enhancement using multi-resolution pyramids is examined for a set of quality metric parameters for comparative performance analysis and use it to assess the enhanced output image for a number of image enhancement algorithms using pyramids.
Abstract: 4 Abstract— Image enhancement has been an area of active research for decades. Most of the studies are aimed at improving the quality of image for better visualization. An approach for contrast enhancement utilizing multi-scale analysis is introduced. To show the effects of image enhancement, quantitative measures should be introduced. In this paper, we examine the effect of global and local enhancement using multi resolution pyramids. We identify a set of quality metric parameters for comparative performance analysis and use it to assess the enhanced output image for a number of image enhancement algorithms using pyramids
8 citations
01 Jan 2011
TL;DR: The classical histogram specification technique is extended by using a target image which is obtained by fusing multiple high resolution images, and a set of Quality Metrics were identified to assess the quality of the output enhanced image.
Abstract: Shape and characteristics of the histogram plays a major role in finding the quality of an image. Histogram Specification is an image enhancement technique, where the histogram of the input image is transformed to a pre-specified histogram derived from a high resolution image, called target image. In this paper, the classical histogram specification technique is extended by using a target image which is obtained by fusing multiple high resolution images. A set of Quality Metrics were identified to assess the quality of the output enhanced image. The paper addresses the following issues: a) Effect of varying the number of target images on the quality of the output enhanced image b) Role of using different methods of fusion on the quality of the output enhanced image c) Category of the target image on the quality of the output enhanced image. If the input image is from a forest, whether in order to obtain an enhanced image, all target images has to be selected from the forest category d) Effect of preprocessing of target image on the quality of the output enhanced image.
7 citations
TL;DR: In this article, the authors used Al-17%wt Si to cast FGM's using Centrifuge Technique and found that enrichment of primary Si was largest in 1.5 ratio compared to other two.
Abstract: Functionally Graded Material (FGM) is a class of material wherein the properties and structure are varied intentionally from one side to the other side of the specimen. This paper describes the effect of L/D (Length to Diameter) ratio of the cast on cast Al-Si FGM. The present study uses Al-17%wt Si to cast FGM's. The cast is evaluated for Microstructure and Hardness all along the length of the specimen. Three L/D ratios: 0.5, 1.0, 1.5 were cast using the Centrifuge Technique. The microstructures showed that enrichment of primary Si was largest in 1.5 ratio compared to other two. Hardness value of the cast at the upper and lower region were examined and found that gradient of hardness was more in 1.5 case. High volume percentage of primary Si was nearly 26% in the upper region and a hypoeutectic structure in the lower region.
3 citations
TL;DR: In this article, the impact of removal of entry load on Net New Money (NNM) of mutual fund industry as a whole has been analyzed and ANOVA and Levene statistic have been used to test the assumption and found that removal of the entry load does not have significant impact on the net new money.
Abstract: Retail investors have nice time to enjoy the initiation taken by the market regulator SEBI i.e. Removal of entry load on all mutual fund schemes. In any case this norm does not affect the investment style of investors who invest more than Rs. 5 Crore but truly bring change in the investment style of retail category. This act by market regulator brings in certain amount of advantages as well as disadvantages to the core participants say Investors, Distributors, Government and obviously Mutual fund. This study basically proposes to analyse the impact of removal of entry load on NNM of mutual fund industry as a whole because NNM is the prime barometer for any scheme. In order to understand whether the removal of entry load has significant impact on NNM or insignificant, ANOVA and Levene statistic have been used to test the assumption and found that removal of entry load does not have significant impact on the Net New Money.
TL;DR: In this paper, the effects of the irreversible boundary reaction and the particle drag on mass transfer in concentric annulus flows are studied analytically in a generalized dispersion model.
Abstract: The effects of the irreversible boundary reaction and the particle drag on mass transfer are studied analytically in concentric annulus flows. The solution of mathematical model, based on the generalized dispersion model brings out the mass transport following by the insertion of catheter on an artery in terms of the three effective transport coefficients, viz., the exchange, convection and diffusion coefficient. A general expression is derived which shows clearly the time dependent nature of the coefficients in the dispersive model. The complete time dependent expression for the exchange coefficient is obtained explicitly and independent of velocity distribution in the flow; however it does depend on the initial solute distribution. Because of the complexity of the problem only asymptotic large time evaluations are made for the convective and diffusion coefficients, but these are sufficient to give the physical insight into the nature of the problem of the effects of drag and absorption parameters. It is found that as absorption parameter increases exchange and convection coefficients will be enhanced, but diffusion coefficient will be reduced. After certain period of time exchange coefficient will be constant for different values annular gap. As the drag parameter increases convection and diffusion coefficients will be reduced. With the enhancement of catheter radius i.e., the annular gap will be reduced then the convection and diffusion coefficients will be decreased.