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 & Computer science. The organization has 503 authors who have published 1062 publications receiving 6818 citations. The organization is also known as: NIT Meghalaya & NITM.

A Comparative Analysis of Heat Transfer in Extended Surfaces with and Without Holes

Abstract: The current fin industries are working with a prime goal to reduce the overall dimensions of the fins with enhancement of the heat transfer rate per unit weight of the fins. To meet the industrial demands it has become mandatory to optimize the shape and the size of the conventional fin systems. Introduction of an extended surface on a heated plate does not always ensures increased rate of heat transfer to the surroundings. An effective utilization of the wetted surface area is major factor in this perspective. Use of fins with different configurations of holes, over a heated surface is found to have very less effect on the average convective heat flux. However, with the considered system of holes, the weight of the fins can be hugely reduced without much lowering of the outlet convective heat flux. With air as the working fluid, a 3-D system of aluminum fins has been numerically modeled in the present work, simulating a conduction-convection scenario.

Analysis of GFDM in generalized <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1283" altimg="si285.svg"><mml:mrow><mml:mi>η</mml:mi><mml:mo linebreak="goodbreak" linebreakstyle="after">−</mml:mo><mml:mi>μ</mml:mi></mml:mrow></mml:math> fading channel: A simple probability density function approach for beyond 5G wireless applications

Abstract: Generalized frequency division multiplexing (GFDM) is a flexible radio waveform which offers high degree of freedom in varying the number of time slots, number of subcarriers, and pulse shaping filters. In addition to this, it also covers orthogonal frequency division multiplexing (OFDM) and single carrier frequency domain equalization (SC-FDE) as corner cases. A well-known fact is that the performance of a wireless communication system is predominately effected by the characteristics of the fading environment. In this paper, symbol error rate (SER) closed-form expression of GFDM system under the generalized η−μ fading channel is derived. The proposed derivation includes Rayleigh, Nakagami-m, and Nakagami-q fading channels as special cases. A Mote-Carlo simulation test-bed is carried out using MATLAB to compare with analytical results and to validate the derived expressions based on the probability density function (PDF) approach. Further, this paper investigates the performance of the GFDM system by varying various parameters such as fading values, pulse shaping filters, roll-off factor, and modulation order. The detailed analysis suggests that the probability of SER is highly dependent on the above parameters. The results obtained are more useful in evaluating the performance of GFDM based communication system in a generalized manner.

Improving the Performance of ASR System by Building Acoustic Models using Spectro-Temporal and Phase-Based Features

Abstract: State-of-the-art spectral or temporal features of speech do not provide adequate attributes for automatic speech recognition (ASR) system in noisy environments. Recently, phase-based speech processing has shown its importance in the speech community. Phase-based features are equally important as magnitude-based features, and if incorporated suitably, it can provide vital acoustic information. This work investigated whether the phase features provide complementary information to spectro-temporal features and enhance the performance of an ASR system. Here, different phase extraction approaches are analysed to identify which representation gives the best performance for the hybrid ASR system. Further, this study addresses the use of phase information along with spectro-temporal features in building an acoustic model for improving the performance of ASR system. Here, gammatonegram-based Gabor filters are utilized to extract the spectro-temporal features from the speech utterances. The combined features seem to inherit better and higher discriminable feature attributes. The experiments are carried out to analyse the performance of ASR system with the combined feature set by considering Aurora2 database and speech utterances from TIMIT corrupted with different noise sources at various SNR values. From the experimental results, it is observed that for the TIMIT database, the performance results show an average relative improvement of 18.2%, 20.1% and 4.7% over MFCC, RASTA-PLP and spectro-temporal features, respectively. In the case of Aurora2 database, a relative improvement of 6.2% on average is obtained with clean training and 6.1% on average is obtained with multi-condition training, compared to the baseline spectro-temporal features.

Anti-Synchronisation of Vallis Chaotic Systems using Nonlinear Active Control Technique Quantitative Features of El-Nino Southern Oscillation (ENSO) Phenomenon

Abstract: In this paper, anti-synchronisation of Vallis chaotic systems is reported. Vallis chaotic system represents the fluctuation of surface temperatures in the east and west part of the Equatorial Ocean and a wind driven current advecting temperature field. A nonlinear active control technique is used to achieve the anti-synchronisation of Vallis chaotic systems. The modified nonlinear active control laws are derived by using sum of the relevant variables of the master and slave systems. Required Lyapunov stability condition is derived to ensure the asymptotic stability of the error dynamics. MATLAB simulation results are presented and reflect that the proposed objective is achieved successfully.