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Shinde V.D.,Indian Institute of Technology Bombay | Joshi D.,SGS Technologie | Ravi B.,Indian Institute of Technology Bombay | Narasimhan K.,Indian Institute of Technology Bombay
Journal of Materials Engineering and Performance

The productivity of ductile iron foundries engaging in mass production of castings for the automobile and other engineering sectors depends on the number of cavities per mold. A denser packing of cavities, however, results in slower heat transfer from adjacent cavities, leading to delayed solidification, possible shrinkage defects, and lower mechanical properties. In this article, we propose a methodology to optimize mold yield by selecting the correct combination of the mold box size and the number of cavities based on solidification time and mold temperature. Simulation studies were carried out by modeling solid and hollow cube castings with different values of cavity-wall gap and finding the minimum value of the gap beyond which there is no change in casting solidification time. Then double-cavity molds were modeled with different values of cavity-cavity gap, and simulated to find the minimum value of gap. The simulation results were verified by melting and pouring ductile iron in green sand molds instrumented with thermocouples, and recording the temperature in mold at predetermined locations. The proposed approach can be employed to generate a technological database of minimum gaps for various combinations of part geometry, metal and process, which will be very useful to optimize the mold cavity layouts. © 2012 ASM International. Source

Joshi D.,SGS Technologie | Ravi B.,Indian Institute of Technology Bombay
Computer-Aided Design and Applications

Complex shaped metal parts with internal and external features and varying wall thickness are most economically produced by casting process. A higher shape complexity however, leads to lower manufacturability, implying sub-optimal quality, higher cost, and reduced productivity. Quantitative evaluation and comparison of shape complexity of alternative part designs can therefore be very useful in design for manufacturability. In this work, we define shape complexity factor using weighted criteria based on part geometry parameters such as number of cored features, volume and surface area of part, core volume, section thickness and draw distance. The coefficients of the criteria are computed by regression analysis using the actual shape complexity, which is defined as the additional cost of tooling manufacture compared to the machining of a simple shape like a cube, and computed using actual cost data from the tooling manufacturer. The regression was carried out using CAD models and cost data of 40 industrial castings of varying shapes. The equation thus obtained was successfully validated by applying it to a separate set of real life cast parts, yielding over 95% accuracy in shape complexity estimation. © 2010 CAD Solutions, LLC. Source

Jain S.K.,SGS Technologie | Jain S.,Davi Ahilya Vishwavidyalaya
Progress In Electromagnetics Research C

This paper presents a neural network based technique for the analysis of various stacked patch antennas, those can be applied for satellite and wireless local area network (WLAN) applications. In order to show the diversity of artificial neural network (ANN) modeling technique, two different trained neural networks were developed with different number of antenna geometrical parameters as inputs. These trained networks locate the operational resonance frequencies with their bands for stacked patch antennas (SPA) operating in the X-Ku (8GHz-18GHz) bands and WLAN bands (2GHz-6GHz). These frequency bands are useful for satellite communication and indoor wireless communication applications respectively. First ANN model takes design (geometrical) parameters of antenna like lower patch dimension, upper patch dimension, and height of air gap, as a input, whereas other NN model includes feed point location also as a input. The validity of the network is tested with the simulations results obtained from the full-wave Method of Moment (MoM) based IE3D and few experimental results obtained in the laboratory. Source

Tiwart S.,Banaras Hindu University | Singh B.K.,Banaras Hindu University | Soni G.G.,SGS Technologie | Pandey P.C.,Banaras Hindu University
Optoelectronics and Advanced Materials, Rapid Communications

A unique photonic crystal fiber (PCF) which consists of circular core surrounded by square lattice cladding is presented. The square lattice cladding further consists of square-shaped air holes. Flattened chromatic dispersion (D) is obtained for this structure in the C and L communication bands at different values of the ratio of square hole width to the pitch (d/A) of the PCF. The main advantage of this structure is its high dispersion tolerance capability for change in the distance between core and square holes cladding (d1). There is observed only about 2.4 ps/nm-km variation in D for -5 to +5% change in d1. Effective mode area has been obtained for this PCF structure which comes out to be small enough to make this fiber suitable to be used in non-linearity related applications. © 2015, National Institute of Optoelectronics. All rights reserved. Source

Jain S.K.,SGS Technologie | Jain S.,D.A.V.V.

A performance analysis of coaxial fed stacked dual patch electromagnetic-coupled microstrip antenna useful for satellite communication working in X/Ku band is presented. A simplified structure of stacked dual patch antenna is proposed with adjustable foam-gap between patches. Few important geometrical parameters were chosen on which the performance of stacked dual patch antenna mainly depends. Dimension of lower square patch, upper square patch and height of foam-gap between two patches are the parameters, which were varied one by one keeping other parameters constant. The performance was observed through the reflection coefficient (dB) and smith chart impedance plot, obtained from the numerical simulator (IE3D) for the dual resonance frequency and bandwidth. Proposed geometry of stacked dual patch antenna was also analyzed with cavity model and artificial neural network modeling technique. Dual resonance frequencies and associated bandwidth were calculated through them and results were cross checked in the laboratory with a few experimental findings. Source

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