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.

Human gait classification using combined HMM & SVM hybrid classifier

Abstract: The paper describes the work on human gait recognition using Hidden Markov Model (HMM), Support Vector Machine (SVM) and Hybridized classifiers (developed using both HMM and SVM). Human gait data obtained from CASIA gait database were segmented to locate major human body part and generate corresponding stick view in order to extract gait features. A total of 25 features were obtained using the length of body parts and major joint angles along with other features and classified using HMM, SVM and Hybridized classifiers. The Hybridized classifier outperforms individual classifiers by 11.25% and 18.14% during training and testing respectively.

Particle dynamics in a symmetrically driven underdamped inhomogeneous periodic potential system.

Abstract: We numerically solve the underdamped Langevin equation to obtain the trajectories of a particle in a sinusoidal potential driven by a temporally sinusoidal force in a medium with coefficient of friction periodic in space as the potential but with a phase difference. With the appropriate choice of system parameters, like the mean friction coefficient and the period of the applied field, only two kinds of periodic trajectories are obtained for all possible initial conditions at low noise strengths: one with a large amplitude and a large phase lag with respect to the applied field and the other with a small amplitude and a small phase lag. Thus, the periodic potential system is effectively mapped dynamically into a bistable system. Though the directional asymmetry, brought about only by the frictional inhomogeneity, is weak we find both the phenomena of stochastic resonance, with ready explanation in terms of the two dynamical states of trajectories, and ratchet effect simultaneously in the same parameter space. We analyze the results in detail attempting to find plausible explanations for each.

Experimental characterization of quaternary blended mortar exposed to marine environment using mechanical strength, corrosion resistance and chemical composition

Abstract: The durability of concrete is significantly influenced by its binder composition, especially in the presence of aggressive chemical environment. This paper represents a study on the strength, durability, and corrosion resistance of quaternary blended mortar made with Portland pozzolana cement (PPC), ground granulated blast furnace slag (GGBS) and rice husk ash (RHA) exposed to marine environment. Binary blended concrete mix using GGBS and RHA as partial replacement for cement is already well established. Previous research reports several shortcomings in using binary blended and ternary mix including low initial strength and increasing shrinkage strains with increasing percentages of GGBS, silica fume and RHA as partial substitutes for cement. Hence, this study is focused on overcoming the limitations of binary and ternary blended mixes by implementing a quaternary blended mix using GGBS and RHA to partially replace cement. This quaternary blended cementitious system is optimized based on its mortar compressive strength , determined by varying the percentages of GGBS and RHA as substitute for cement. These optimized quaternary mortar specimens are moist-cured for 28 days and then exposed to an artificially prepared marine environment for 180 days. The optimized quaternary blended mortar specimens show improved mechanical strengths, both compressive and flexural. These specimens also exhibit enhanced resistance to chloride penetration , corrosion, and water absorption compared to the control mix after 28 days of water curing. A quaternary blended mortar mix prepared with 70% PPC, 20% GGBS, and 10% RHA exhibits the maximum mechanical strength, resistance to chloride penetration, and corrosion, mass loss and water absorption upon exposure to marine environment up to a period of 180 days. Mineralogical analyses using X-ray diffraction (XRD), chemical bond analyses using Fourier Transform Infra-Red (FTIR) spectroscopy, and microanalyses using scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray spectroscopy (EDS) are implemented to determine the effects of marine environment exposure on the different mixes. The findings are then used to corroborate the observations from the specimen scale mechanical and chemical characterizations .

Parallel state space exploration of linear systems with inputs using XSpeed

Abstract: We present on-going work on XSpeed, a tool for parallel state space exploration of continuous systems with linear dynamics and non-deterministic inputs. XSpeed exploits the computational power of multi-core architectures to speed up reachability analysis. A parallel exploration algorithm with multiple initial sets in partitions of the time horizon has been proposed and implemented in XSpeed. A parallel implementation of a reachability algorithm using support functions as symbolic states is also provided. Performance of XSpeed is compared with an optimized implementation of the support function algorithm and with SpaceEx (LGG scenario), a scalable tool for hybrid systems with linear dynamics. Experiments on Intel core i7-4770 having 4 physical cores and 8 threads of execution show that XSpeed achieves a speed up of 5 times when compared to SpaceEx over a 28 dimensional Helicopter model. We could also show computation of precise reachable states with our parallel exploration algorithm in comparison to the support function algorithm.