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D. N. Pawaskar

Publications and source records attributed to D. N. Pawaskar.

3 recordsLinked to original sources

Autonomous Crack Detection using Deep Learning on Synthetic Thermogram Datasets

In a lot of scientific problems, there is the need to generate data through the running of an extensive number of experiments. Further, some tasks require constant human intervention. We consider the problem of crack detection in steel plates. The way in which this generally happens is through humans looking at an image of the thermogram generated by heating the plate and classifying whether it is cracked or not. There has been a rise in the use of Artificial Intelligence (AI) based methods which try to remove the requirement of a human from this loop by using algorithms such as Convolutional Neural Netowrks (CNN)s as a proxy for the detection process. The issue is that CNNs and other vision models are generally very data-hungry and require huge amounts of data before they can start performing well. This data generation process is not very easy and requires innovation in terms of mechanical and electronic design of the experimental setup. It further requires massive amount of time and energy, which is difficult in resource-constrained scenarios. We try to solve exactly this problem, by creating a synthetic data generation pipeline based on Finite Element Simulations. We employ data augmentation techniques on this data to further increase the volume and diversity of data generated. The working of this concept is shown via performing inference on fine-tuned vision models and we have also validated the results by checking if our approach translates to realistic experimental data. We show the conditions where this translation is successful and how we can go about achieving that.

cs.CV

Effects of DC voltage on initiation of whirling motion of an electrostatically actuated nanowire oscillator

Planar driven nanowire oscillators are susceptible to undergo whirling motion due to coupling between flexural planar and nonplanar modes of vibration. This investigation is concerned with planar to whirling motion transition in the oscillation of an electrostatically actuated nanowire, which is pre-deflected due to applied DC voltage. We have derived dynamical equations of motion using Euler-Bernoulli beam theory and Galerkin formulation as reduced order model of the governing coupled partial differential equations. The dynamical equations have been solved using second-order averaging method and the averaging solution has been validated by comparing with the numerical solution of the reduced order model. Further, planar to whirling motion transition has been investigated by studying qualitative changes in resonance curves with variation of electrostatic actuation. In this paper, we provide a simple analytical condition which takes into account the effects of DC voltage for prediction of initiation of whirling motion. Our main observation of the present investigation is that DC voltage can tune the initiation pattern of the whirling motion and change the qualitative nature of resonance curves.

cond-mat.mes-hall

Effects of Residual Stress on Static and Dynamic Characteristics of an Electrostatically Actuated Nanobeam

Electrostatically actuated nanotubes and nanowires have many promising applications as nano-switches, ultra sensitive sensors and signal processing elements. These devices can be modelled as slender beams with circular cross-section. In this paper, effects of residual stress on static and dynamic characteristics of a cylindrical nanobeam are presented. Galerkin based multi-modal reduced order model technique has been used to solve the governing differential equation. The equation has also been solved numerically by collocation method for verification of the results. The effects of higher modes in reduced order modelling have been investigated. The analysis shows that the residual stress significantly influence the static and dynamic characteristics of the nanobeam. In particular, the results show that resonating frequency tunability increases significantly under the presence of compressive residual stress. In addition, an inherent resonating frequency stability mechanism under temperature variation in nanobeam resonators has also been explored.

cond-mat.mes-hall