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.

Influence of Cutting Speed and Offset Distance over Cutting Tool Vibration in Multi-Tool Turning Process

Abstract: Multi-tool turning process employs more than one cutting tool for machining the work piece simultaneously. In the conventional turning process, effect of machining parameters over cutting forces, vibration, work piece surface finish and dimensional tolerances have been discussed in detail, however no attempt has been made in the multi-tool turning process. Cutting tool vibration is very important as it reveals the condition of cutting tool as well as work piece quality. In this study, a second cutting tool is introduced at the rear side of the lathe with some distance from conventional front cutting tool to machine the work piece simultaneously. Accelerometers are used to measure the vibration signals in the tangential direction of cutting. Obtained time domain vibration signals are converted to frequency domain signals by Fast Fourier Transform to reveal its power spectral density. In this work cutting speed and distance between front and rear cutting tool are varied to understand the cutting tool vibration. With increase in cutting speed and increase in distance between front and rear cutting tool, vibration reduces.

Non-statistical intermolecular energy transfer from vibrationally excited benzene in a mixed nitrogen-benzene bath.

Abstract: A chemical dynamics simulation was performed to model experiments [N. A. West et al., J. Chem. Phys. 145, 014308 (2016)] in which benzene molecules are vibrationally excited to 148.1 kcal/mol within a N2-benzene bath. A significant fraction of the benzene molecules are excited, resulting in heating of the bath, which is accurately represented by the simulation. The interesting finding from the simulations is the non-statistical collisional energy transfer from the vibrationally excited benzene C6H6* molecules to the bath. The simulations find that at ∼10-7 s and 1 atm pressure there are four different final temperatures for C6H6* and the bath. N2 vibration is not excited and remains at the original bath temperature of 300 K. Rotation and translation degrees of freedom of both N2 and C6H6 in the bath are excited to a final temperature of ∼340 K. Energy transfer from the excited C6H6* molecules is more efficient to vibration of the C6H6 bath than its rotation and translation degrees of freedom, and the final vibrational temperature of the C6H6 bath is ∼453 K, if the average energy of each C6H6 vibration mode is assumed to be RT. There is no vibrational equilibration between C6H6* and the C6H6 bath molecules. When the simulations are terminated, the vibrational temperatures of the C6H6* and C6H6 bath molecules are ∼537 K and ∼453 K, respectively. An important question is the time scale for complete energy equilibration of the C6H6* and N2 and C6H6 bath system. At 1 atm and 300 K, the experimental V-T (vibration-translation) relaxation time for N2 is ∼10-4 s. The simulation time was too short for equilibrium to be attained, and the time for complete equilibration of C6H6* vibration with translation, rotation, and vibration of the bath was not determined.

A Data-Driven Physics-Informed Method for Prognosis of Infrastructure Systems: Theory and Application to Crack Prediction

Abstract: Infrastructure systems are the backbones of the socioeconomic development of a community. However, after installation, these engineered systems undergo deterioration, leading to a degradati...

A real-time DWT and traveling waves-based multi-functional scheme for transmission line protection reinforcement

Abstract: This paper presents a multifunctional scheme to reinforce the protection of Extra High Voltage (EHV)/Ultra High Voltage (UHV) transmission lines. The proposed scheme employs d–q transformed traveling waves and the time of incidence of first traveling waves at both ends of the line for fault detection and location respectively. Furthermore, the faults are classified using energy values of approximation coefficients and the phasors are estimated from the approximation coefficients. The traveling waves are nothing but detail coefficients. The detail and approximation coefficients are obtained using discrete wavelet transform multi-resolution analysis (DWT-MRA) of the 3-ɸ current signals. The proposed algorithm detects and locates a fault within a quarter cycle. The proposed scheme has been implemented on a two-bus and the WSCC-9 bus systems in EMTDC/PSCAD software to verify the efficacy and reliability. Also, it has been realized on a laboratory model of an EHV transmission line of length 200 km using NI cDAQ-9178 chassis, NI-9227 current sensor card, and LabVIEW software. The simulation and hardware results evince the protection reinforcing property of the proposed multifunctional scheme.