Research Publications
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Item An Approximation Algorithm for Path Planning of Vehicles for Data Collection in Wireless Rechargeable Sensor Networks(2023) Kumar R.; Mukherjee J.C.Wireless rechargeable sensor networks (WRSNs) have been extensively used in various event detection and environmental monitoring applications, where it is important to collect environmental data from the sensors. Data may be collected at the base station (BS) through multi-hop communication. But it may cause sensors located near the BS to run out of their energy quickly. In a WRSN, data may also be collected using mobile vehicles that visit different sensors to collect data. However, in a large scale WRSN, travelling to all the sensors for data collection may cause vehicles to run out of their energy in the middle of their journey. In this paper, we formulate an optimization problem that minimizes the average travel distance of the vehicles while collecting data from maximum number of sensors. The problem is proved to be NP-complete. To avoid visiting all the sensors, our scheme selects a subset of sensors as anchor nodes that first collects data from neighboring sensors through one-hop transfer. Then, the anchor nodes are divided among the vehicles. Finally, a convex-hull based 3-approximation algorithm is proposed that finds the travel plan for each vehicle through the anchor nodes only, where the vehicle starts from the BS, collects data from the anchor nodes, while returning back to the BS at the end of its journey. Simulation results show that our scheme outperforms the existing schemes in terms of the average travel distance by vehicles, while collecting data from a large number of sensors. � 2023 ACM.Item ELLIPTIC PROBLEM IN AN EXTERIOR DOMAIN DRIVEN BY A SINGULARITY WITH A NONLOCAL NEUMANN CONDITION(2023) Choudhuri D.; Saoudi K.We prove existence of a ground state solution to the following problem. (Formula presented) where N \geq 2, \lambda > 0, 0 < s, \gamma < 1, p \in (1, 2\asts -1) with (Formula presented). Moreover, (Formula presented) is a smooth bounded domain, (-\Delta)s denotes the s-fractional Laplacian and finally Ns denotes a nonlocal operator that describes the Neumann boundary condition. We further establish existence of infinitely many bounded solutions to the problem. � (2023), (Institute of Mathematics). All rights reserved.Item Channel Estimation and Performance Analysis of a Wide-FOV Visible Light Communication System With Random Receiver Orientation and Location(2023) Pal R.K.; Dash S.P.; Joshi S.; Ghose D.A practical visible light communications (VLC) system accounting for the effect of the random orientation and the random location of the photo-detector receiver is considered in this paper. The characterizations of the random orientation of the receiver, modeled as the receiver employing wide field of view (FOV) for data detection, and the random location of the receiver are utilized to derive the statistics for the scenarios in which (i) only the orientation of the receiver is random, (ii) only the location of the receiver is random, and (iii) both the orientation and location of the receiver are random. Furthermore, the receiver structures for a fully coherent VLC system and a VLC system employing the least-squares technique for channel estimation are proposed. Employing the receiver structures, the closed/series-form expressions for the symbol error probabilities are derived for all three scenarios of practical VLC channel models. The numerical results particularly show the crucial role of the ratio of the distance of the location of the receiver from the center of the receiving plane to the distance from the light-emitting diode (LED) to the center of the receiving plane in the performance of all the considered VLC systems. � 2002-2012 IEEE.Item A Novel Mapping of ECG and PPG to Ensure the Safety of Health Monitoring Applications(2023) Panda A.; Pinisetty S.; Roop P.Biophysical signals, such as electrocardiogram (ECG) and photoplethysmogram (PPG) are key to the sensing of vital parameters for wellbeing. Coincidentally, both ECG and PPG provide a different window into the same phenomena, namely, the cardiac cycle. However, they are used separately for various health monitoring tasks, which often have safety implications. As these sensors are subject to errors and failures, there is a need to develop methods that consider both sensors so as to enhance the safety of the health monitoring application. Considering this, we present the first approach to establish the key relationships between ECG and PPG signals formally. We combine formal runtime monitoring with statistical analysis and regression analysis for our results. � 2009-2012 IEEE.Item Bohr and Rogosinski inequalities for operator valued holomorphic functions(2023) Allu V.; Halder H.; Pal S.For any complex Banach space X and each p?[1,?), we introduce the p-Bohr radius of order N(?N) is R�p,N(X) defined by R�p,N(X)=sup?{r?0:?k=0N?xk?prpk??f?Hp}, where f(z)=?k=0?xkzk?H?(D,X). Here D={z?C:|z|<1} denotes the unit disk. We also introduce the following geometric notion of p-uniformly C-convexity of order N for a complex Banach space X for some N?N. For p?[2,?), a complex Banach space X is called p-uniformly C-convex of order N if there exists a constant ?>0 such that (?x0?p+??x1?p+?2?x2?p+?+?N?xN?p)1/p?max??[0,2?)??x0+?k=1Nei?xk? for all x0, x1, �, xN ?X. We denote Ap,N(X), the supremum of all such constants ? satisfying (0.1). We obtain the lower and upper bounds of R�p,N(X) in terms of Ap,N(X). In this paper, for p?[2,?) and each N?N, we prove that a complex Banach space X is p-uniformly C-convex of order N if, and only if, the p-Bohr radius of order N R�p,N(X)>0. We also study the p-Bohr radius of order N for the Lebesgue spaces Lq(?) for 1?pItem Monsoon depressions and air-sea interactions during different phases of monsoon intraseasonal oscillation(2023) Ray A.; Sil S.The present study focuses on climatological distributions of Monsoon Depressions (MDs) during different phases of Monsoon Intraseasonal Oscillation (MISO) and their relationship with different observed meteorological and oceanic parameters from buoys. The MISO is represented as a cyclic process with eight phases to show the northward propagation of the rainfall band. Almost 60% of MDs occur during the third and fourth phases of MISO over the north Bay of Bengal (BoB) and central India. Interestingly, a similar climatological composite of SST for different MISO phases does not precisely match the spatial precipitation pattern over the BoB. Instead, the oscillation is shown over a confined area near the east coast and to the north of 15? N. The lagged (6�12�days) impact of SST is well recognized in central and west BoB. The characteristics of MISO are explained through a detailed investigation of two contrasting years (2017 and 2018) in terms of the number of MDs. The analysis showed possible impacts of intensity and track of depressions on the MISO in terms of its intensity and successive phases. The intraseasonal signal of surface salinity is mostly negative during the weak phases of MISO (7, 8, and 1) with a slight lag (10�15�days) because of a freshwater flux resulting from the previous wet period. Similarly, during the active phases (phase 3 to phase 6), the salinity signal becomes positive for the lagged impact of higher evaporation during the current and prior phases. A consecutive repetition of phases 4 to 6, associated with different MDs concurrence with increasing ocean heat content (OHC), is noted during both years. The ISO in subsurface (25�60�m) temperature is stronger in 2018, and upward propagation of temperature anomaly helps in formations of more depressions than in 2017. In addition, six years (2013�2018) of subsurface temperature showed that MDs formation followed the warmer subsurface. The ISO signals for different meteorological parameters, Air Temperature, Sea Level Pressure, and Wind Speed are comparatively stronger (by amplitude) in 2018 than in 2017, resulting in higher variability of MISO and more MDs. � 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item Stabilization of DC Bus Voltage of an Isolated DC Microgrid(2023) Singh P.N.; Ranjan R.; Karanki S.B.This paper deals with the robust control strategy used for the isolated DC microgrid. The DC microgrid considered here comprises a solar photo voltaic (PV) source, biomass, biogas, energy storage, and mixed loads. An observer based sliding mode controller is designed for biomass and biogas systems. The salient feature of a sliding mode controller is that it has a proportional integral sliding surface, due to which it can properly regulate the DC bus voltage irrespective of the disturbances caused by change in load. In order to integrate energy storage systems, a cascaded hybrid proportional integral Lypanov stability-based controller is designed, which ensures the global asymptotic stability of the closed loop system. This controller has better performance and faster response, irrespective of the presence of mixed loads. The effectiveness of controller is explored by simulation using MATLAB/Simulink. � 2023 IEEE.Item Study of the peritectic phase transformation kinetics with elastic effect in the Fe�C system by quantitative phase-field modeling(2023) Parida H.; Kundin J.; Alves C.L.M.A quantitative phase-field model developed for two-phase growth process (Folch and Plapp, 2005) is applied to the simulation of peritectic phase transformation in a Fe�C binary alloy system with elastic effects due to the misfit on the solid/solid interface. The model includes the anti-trapping current, elastic effect, and the quantitative model parameters estimated based on the thin-interface limit. The diffusion of carbon in the solid phases (i.e. ? and ? phases) has not been neglected and an appropriate free-energy functional has been developed such that there is no presence of any extra phase in the interface. The model's behavior over a wide range of interface width has been studied and the effect of anti-trapping current and elastic effect on the phase transformation has been closely analyzed. � 2023 Elsevier B.V.Item Combined experimental and TD-DFT study of a highly sensitive AIE-based probe for the detection of water in organic solvents and its application in inkless writing(2023) Panda S.K.; Singh A.K.The present manuscript highlights a newly synthesized pyrene-based probe (PyQ), which has a high affinity for the detection of water in water-miscible organic solvents. The efficient probe followed the principle based on aggregation-induced emission and showed its potential behavior as a sensor by detecting water in common water-miscible organic solvents by the fluorometric method. The chemosensor PyQ has identified water separately from many other solvents as its emission maxima in presence of water is found near 510 nm while for others it is around 410 � 440 nm. Moreover, in different water-miscible solvents by increasing the percentage of water, fluorescence studies have been carried out and were found that increasing water content in organic solvents increased the fluorescence intensity of the PyQ as well as provided a redshift to the emission intensities. Furthermore, the response of PyQ towards pH and the LOD and LOQ of PyQ towards a low level of water content in different organic solvents were determined. TD-DFT studies were carried out in the aqueous phase to clarify the optical and electronic properties of the probe. The moisture detection capacity of PyQ in presence of silica gel desiccant was also showcased. Finally, the utilization of PyQ in inkless writing and in reusable or rewritable paper strips disclosed its potential for real-life applications, which strengthened its use as a water sensor. � 2023 Elsevier B.V.Item Semiclassical Dynamics on Machine-Learned Coupled Multireference Potential Energy Surfaces: Application to the Photodissociation of the Simplest Criegee Intermediate(2023) Sit M.K.; Das S.; Samanta K.Determination of high-dimensional potential energy surfaces (PESs) and nonadiabatic couplings have always been quite challenging. To this end, machine learning (ML) models, trained with a finite set of ab initio data, allow accurate prediction of such properties. To express the PESs in terms of atomic contributions is the cornerstone of any ML based technique because it can be easily scaled to large systems. In this work, we have constructed high fidelity PESs and nonadiabatic coupling terms at the CASSCF level of ab initio data using a machine learning technique, namely, kernel-ridge regression. Additional MRCI-level calculations were carried out to assess the quality of the PESs. We use these machine-learned PESs and nonadiabatic couplings to simulate excited-state molecular dynamics based on Tully�s fewest-switches surface hopping method (FSSH). FSSH is a semiclassical method in which nuclei move on the PESs due to the electrons according to the laws of classical mechanics. Nonadiabatic effects are taken into account in terms of transitions between PESs. We apply this scheme to study the O-O photodissociation of the simplest Criegee intermediate (CH2OO). The FSSH trajectories were initiated on the lowest optically bright singlet excited state (S2) and propagated along the three most important internal coordinates, namely, O-O and C-O bond distances and the COO bond angle. Some of the trajectories end up on energetically lower PESs as a result of radiationless transfer through conical intersections. All of the trajectories lead to the dissociation of the O-O bond due to the dissociative nature of the excited PESs through one of the two dissociative channels. The simulation reveals that there is about 88.4% probability of dissociation through the lower channel leading to the H2CO (X1A1) and O (1D) products, whereas there is only 11.6% probability of dissociation through the upper channel leading to H2CO (a3A?) and O (3P) products. � 2023 American Chemical Society.