National Institute of Technology, Meghalaya

About: National Institute of Technology, Meghalaya is a education organization based out in Shillong, India. It is known for research contribution in the topics: Control theory & Electric power system. The organization has 503 authors who have published 1062 publications receiving 6818 citations. The organization is also known as: NIT Meghalaya & NITM.

Process Parameters Optimization of EDMed Surface of Titanium-Grade-4 Alloy Using Topsis Coupled with Taguchi Philosophy

Abstract: EDM is one of the non-conventional machining systems. It is a specialized thermal machining process which is used for machining parts of varying hardness and complex shapes. The major drawback of this system is that it has a lower machining rate. As there is no contact between the work-piece and the tool, so it is independent of the hardness of the work material. Titanium-Grade 4 (3.7065, R50700) finds its application in the aerospace industry. Machining of titanium was not an easy task, as it has poor thermal conductivity, higher pressure load, non-uniform chip thickness, etc. Peak current, pulse on time, and voltage were taken as input control parameters, whereas material removal rate, tool wear rate, and surface roughness were taken as response parameters. Desirability function was used to design the experiments using the L9 orthogonal array. The effects of each parameter on the response while machining using a copper electrode were studied.

An Empirical Seed Initialization Idea for K-Means Algorithm Inspired by CLIQUE Algorithm

Abstract: The K-means clustering algorithm gives good clustering results when the initial centroids or seeds are chosen close to actual cluster centers. In this paper an empirical centroid initialization technique has been presented for the K-means clustering algorithm. The technique is inspired by a well-known grid-based clustering algorithm called 'CLIQUE.' The technique evaluates the initial centroids by evaluating validity indices to check their vicinity from actual cluster centers. Experiments on datasets show that the technique obtains good initial centroids for the datasets compared to state-of-the-art K-means++ clustering algorithm.

Analysis of Different Types of Micro Grains in Stick Welded Mild Steel Plates

Abstract: Nowadays, arc welding is the most essential thing in every field. Therefore, researchers are focusing on the improvement of the quality of the arc welding. For that microstructure plays a major role in this work, mild steel plates were taken as workpiece material to do welding operation in stick welding. V-edge was prepared to conduct butt welding between the plates which has to be joined by application of 120 A current. After cooling, the microstructure of the welded specimen was observed. Importantly, two main constituents’ ferrite and pearlite were found mostly. Eight varieties of ferrite were analyzed in fusion zone and heat-affected zone. The primary ferrites were distinguished in the heat-affected zone and the Widmanstatten ferrites in fusion zone in between the dendritic structures. The primary ferrites have been more circular in nature and the Widmanstatten ferrites were columnar. The mechanical properties also vary due to the variation of ferrite structures. Pearlites were observed in between the ferrites with more percentage of carbon content which is the most distinguished feature of pearlite grains.

Perturbations on K-fusion frames

Abstract: K-fusion frames are generalizations of fusion frames in frame theory This article characterizes various kinds of property of K-fusion frames Several perturbation results on K-fusion frames are formulated and analyzed

Power quality analysis in a grid connected PV system employing a hybrid technique based on Fractional Wavelet Transform

Abstract: In this paper, a novel detection technique using Fractional Wavelet Transform (FRWT) is applied for monitoring three-phase grid connected PV generation system. The idea behind this protection scheme is based on combined features derived from Discrete Fractional Fourier Transform (DFRFT) and Discrete Wavelet Transform (DWT) techniques, which provides more actual time-frequency information. In this study, DFRFT is applied for the fast recognition of a transformed signal via fractional rotation in time-frequency plane and DWT is applied for detecting power disruption in the system more accurately. The effectiveness of applied hybrid technique is also compared with Wavelet Transform (WT) by simulating the system in MATLAB/SIMULINK environment. The simulated results demonstrate the feasibility and effectiveness of the proposed detection strategy under noisy situation and also in the existence of harmonics.