Browsing by Author "Acharya, S."

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Artificial intelligence and machine learning in battery materials and their applications
(Elsevier, 2024) Acharya, S.; Viswesh, P.; Sridhar, M.K.; Pathak, A.D.; Sharma, H.; Nazir, A.; Kasbe, A.; Sahu, K.K.
The fast-depleting fossil fuels and other environmental impacts necessitate rapid development and deployment of efficient, smart, intelligent, and future-ready energy storage solutions. Gone are the days of only trial-and-error-based research and development protocols that take a long time to mature and yield meaningful results, say, in discovering new structures/functional materials (nano to microstructure) for batteries or the development of new battery systems. As the existing computational power is increasing rapidly, coupled with the rapidly falling cost of computation, artificial intelligence (AI) and machine learning (ML) have proved their potential in discovering new battery materials in a short period. This chapter begins with a brief introduction to various AI and ML methods used in the development and deployment of battery material and their applications. Then we focus on the AI and ML methods used in different stages of battery production, from the material selection stage to the manufacturing, state of charge, and state of health prediction, understanding and controlling degrading and aging mechanisms and testing of battery performance, as well as some emerging AI and ML-assisted battery technologies. © 2024 by Elsevier Inc. All rights reserved, including those for text and data mining, AI training, and similar technologies.
Broker-based mechanism for cloud provider selection
(Inderscience Publishers, 2020) Achar, R.; Santhi Thilagam, P.; Acharya, S.
Cloud computing has recently emerged as a new computing paradigm for delivering on demand virtualised computing resources over the internet on a pay-as-use basis. Applications hosted in cloud have different requirements which include both low level (resource) requirements and high level (performance) requirements. However, most of the cloud providers satisfy SLAs based on resource requirements rather than providing performance guarantees to applications. This gap creates a need for selecting a more suitable cloud provider who can satisfy performance requirements of applications along with resource requirements. This work aims at proposing a broker-based approach to rank cloud providers based on QoS requirements of customers. It helps the SaaS providers to save cost and complexity in choosing a suitable cloud provider for hosting applications. The experimental results show that proposed approach selects the suitable cloud provider for hosting various types of applications satisfying the needs of different cloud customers. Â© 2020 Inderscience Enterprises Ltd.
Characterization of magnetorheological brake utilizing synthesized and commercial fluids
(Elsevier Ltd, 2019) Acharya, S.; Shyam Saini Tak, R.; Bhanu Singh, S.; Kumar, H.
Magnetorheological (MR) brakes produce braking torque due to variation in the magnetorheological properties of the MR fluid when external magnetic field is applied. In this study, MR fluids having 70% and 80% weight fractions of iron powder were prepared and MR brake characteristics were tested for prepared MR fluids and a commercial Lord MRF 132 DG fluid. It was found that there was an increase in braking torque with applied current to MR brake at all speeds indicating the MR effect. With increase in weight fraction, there is an increase in braking torque though the reduction in speed is not significant. However, in case of MRF 132 DG fluid, the decrease in rpm is significant especially at higher speeds. Though, the prepared fluids and commercial fluid produce closer braking torque values at higher currents, the increase in braking torque without magnetic field to that with magnetic field at maximum current of MR brake utilizing commercial fluid is very high due to its low viscous torque. Finally, analysis in finite element method magnetics software combined with analytical equations was used to compute torque and compared with experimental results of MR brake utilizing commercial fluid. Â© 2019 Elsevier Ltd.
Computational materials discovery and development for Li and non-Li advanced battery chemistries
(International Association of Physical Chemists, 2023) Sharma, H.; Nazir, A.; Kasbe, A.; Kekarjawlekar, P.; Chatterjee, K.; Motevalian, S.; Claus, A.; Prakash, V.; Acharya, S.; Sahu, K.K.
Since the discovery of batteries in the 1800s, their fascinating physical and chemical properties have led to much research on their synthesis and manufacturing. Though lithium-ion batteries have been crucial for civilization, they can still not meet all the growing demands for energy storage because of the geographical distribution of lithium resources and the intrinsic limitations in the cell energy density, performance, and reliability issues. As a result, non-Li-ion batteries are becoming increasingly popular alternatives. Designing novel materials with desired properties is crucial for a quicker transition to the green energy ecosystem. Na, K, Mg, Zn, Al ion, etc. batteries are considered the most alluring and promising. This article covers all these Li, non-Li, and metal-air cell chemistries. Recently, computational screening has proven to be an effective tool to accelerate the discovery of active materials for all these cell types. First-principles methods such as density functional theory, molecular dynamics, and Monte Carlo simulations have become established techniques for the preliminary, theoretical analysis of battery systems. These computational methods generate a wealth of data that might be immensely useful in the training and validating of artificial intelligence and machine learning techniques to reduce the time and capital expenditure needed for discovering advanced materials and final product development. This review aims to summarize the application of these techniques and the recent developments in computational methods to discover and develop advanced battery chemistries. © 2023 by the authors; licensee IAPC, Zagreb, Croatia.
Conduction Mechanism in n-CdSe/p-ZnTe Heterojunction
(Springer New York LLC barbara.b.bertram@gsk.com, 2016) Acharya, S.; Bangera, K.V.; Shivakumar, G.K.
This work reports on fabrication using vacuum evaporation and characterization of n-CdSe/p-ZnTe heterojunctions. Before forming the junction, CdSe and ZnTe layers were characterized for crystal structure and chemical composition to account for observed electrical properties. The heterojunction was characterized by current–voltage (I–V) measurements, temperature dependence of reverse saturation current, admittance, and capacitance–voltage (C–V) measurements. I–V characteristics of the heterojunction exhibited clear diode nature with rectification ratio of 9.05 at ±0.5 V and ideality factor n = 3.34. From the temperature dependence of the I–V characteristic, a barrier height ?b of 0.36 eV was determined for the CdSe–ZnTe junction. Conduction mechanism analysis revealed contributions from both thermionic and space-charge-limited conduction. Furthermore, the shunt leakage current was found to be space-charge limited, showing symmetry in current near V = 0 V. The dependence of capacitance on frequency and bias voltage has been analyzed to identify the bulk and interface defects. These measurements indicate the presence of bulk defects and high series resistance, severely affecting current transport. © 2016, The Minerals, Metals & Materials Society.
Determination of optimal magnetorheological fluid particle loading and size for shear mode monotube damper
(Springer Verlag service@springer.de, 2019) Acharya, S.; Saini, R.S.S.; Kumar, H.
Magnetorheological (MR) fluids belong to a class of controllable fluids, and the composition and concentration of its components govern its magnetorheological properties. In this study, an optimum particle loading (or mass fraction) and size of iron particles in MR fluid for use in a shear mode monotube MR damper were determined based on the damping force and off-state viscosity of synthesized MR fluid samples. Initially, the morphological and magnetic properties of carbonyl iron particles were characterized. Six MR fluid samples were prepared composed of combination of three different particle loadings and two sizes of iron particles. Magnetorheological tests were conducted on these samples to determine the flow curves at off-state and on-state magnetic field conditions. Herschel–Bulkley model was used for mathematical representation of flow curves at different magnetic fields and to determine their dynamic yield stress. Further, a shear mode monotube MR damper with accumulator was designed by using optimization technique for desired dynamic range and damping force. Magnetostatic analysis was performed to determine the magnetic field strength generated in the shear gap at different currents. The damping force was calculated for synthesized MR fluids based on their dynamic yield stress corresponding to the magnetic field strength in the shear gap. Analysis of variance was performed to analyse the significance of independent factors on the damping force and off-state viscosity of MRF. The optimal particle loading and size which yielded maximum damping force with minimum off-state viscosity were determined using a multi-objective genetic algorithm. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.
Dynamic behavior of sandwich beams with different compositions of magnetorheological fluid core
(Taylor and Francis Ltd., 2021) Acharya, S.; Allien, V.J.; Puneet, P.; Kumar, H.
Magnetorheological fluid (MRF) sandwich beams belong to a class of adaptive beams that consists of MRF sandwiched between two or more face layers and have a great prospective for use in semi-active control of beam vibrations due to their superior vibration suppression capabilities. The composition of MRF has a strong influence on the MRF properties and hence affects the vibration characteristics of the beam. In this work, six MRF samples (MRFs) composed of combination of two particle sizes and three weight fractions of carbonyl iron powder (CIP) were prepared and their viscoelastic properties were measured. The MRFs were used to fabricate different MRF core sandwich beams. Additionally, a sandwich beam with commercially available MRF 132DG fluid as core was fabricated. The modal parameters of the cantilever MRF sandwich beams were determined at different magnetic fields. Further, sinusoidal sweep excitation tests were performed on these beams at different magnetic fields to investigate their vibration suppression behavior. MRF having larger particle size and higher weight fraction of CIP resulted in higher damping ratio and vibration suppression. Finally, optimal particle size and weight fraction of CIP were determined based on the maximization of damping ratio and minimization of weight of MRF. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
Electrical characterization of vacuum-deposited p-CdTe/n-ZnSe heterojunctions
(Springer Nature, 2015) Acharya, S.; Bangera, K.V.; Shivakumar, G.K.
In this paper, we report a heterojunction of p-CdTe/n-ZnSe fabricated on a quartz substrate using thermal evaporation technique. The materials have a larger band gap difference in comparison to other II–VI heterojunctions-involving CdTe. The larger band gap difference is expected to increase diffusion potential and photovoltaic conversion efficiency. The electrical conduction mechanism involved, barrier height and band offset at the interface that are crucial to determine device performance are evaluated using electrical characterization of heterojunction. The junction exhibited excellent rectification behavior with an estimated barrier height of 0.9 eV. © 2015, The Author(s).
Investigation of magnetorheological brake with rotor of combined magnetic and non-magnetic materials
(Springer Nature, 2019) Acharya, S.; Kumar, H.
Magnetorheological (MR) brakes are a type of electromagnetic brakes that make use of controllable viscoelastic properties of magnetorheological fluid for braking. The torque capacity of the MR brake depends on the magnitude of magnetic flux density generated in the MR fluid. In this study, the effect of combination of magnetic and non-magnetic materials for rotor disk of MR brake with the objective to maximizing the flux density in the MR fluid gap at the rotor periphery was investigated. Initially, the MR brake rotor disk radius and MR fluid gap thickness were determined by using Genetic Algorithm optimization technique for desired torque ratio and torque capacity. Magnetostatic analyses were performed at different current magnitudes to determine the magnetic field and flux density in the MR brake. Further, to enhance the magnetic field intensity in the MR fluid at the rotor periphery, the rotor was modeled with three different configurations of MR brake with combinations of magnetic and non-magnetic steel and magnetostatic analyses of the MR brake were performed. It was found that the leakage of flux away from rotor periphery was reduced and there is significant increase and concentration of the magnetic field and flux density in the MR fluid gap through the use of rotor disk with combined magnetic and non-magnetic materials which would subsequently increase the torque capacity of the MR brake. © 2019, Springer Nature Switzerland AG.
Machine Learning Approaches for Designing Electrode Materials for Lithium-Ion Batteries
(wiley, 2024) Prakash, V.; Acharya, S.; Sharma, H.; Pathak, A.D.; Sahu, K.K.
[No abstract available]
On the improved performance of luby transform codes over selective repeat ARQ in turbulent free space optical links
(2013) Prakash, G.; Nayak, A.; Kulkarni, M.; Acharya, S.
Free Space Optical (FSO) links are capable of offering high data transfer rates, secure and low interference links for connectivity as a last mile solution. However, atmospheric turbulence can degrade the performance for distances over 1 km. This degradation is in the form of packet loss and hence drop in the error performance. Error Control Coding (ECC) can be used to mitigate the effects of the atmospheric turbulence. In this paper we prove analytically and verify through simulations that Luby Transform(LT) Codes show an improved performance over Automatic Repeat Request(ARQ) schemes for FSO transmission. FSO systems are limited by the safety limits of the input power to the laser transmitter. A notable contribution in this paper is that we prove that this improvement with LT codes is within Maximum Permissible Exposure (MPE) limit for an FSO link for a BER performance of 10-5. � 2013 IEEE.
On the improved performance of luby transform codes over selective repeat ARQ in turbulent free space optical links
(2013) Prakash, G.; Nayak, A.; Kulkarni, M.; Acharya, S.
Free Space Optical (FSO) links are capable of offering high data transfer rates, secure and low interference links for connectivity as a last mile solution. However, atmospheric turbulence can degrade the performance for distances over 1 km. This degradation is in the form of packet loss and hence drop in the error performance. Error Control Coding (ECC) can be used to mitigate the effects of the atmospheric turbulence. In this paper we prove analytically and verify through simulations that Luby Transform(LT) Codes show an improved performance over Automatic Repeat Request(ARQ) schemes for FSO transmission. FSO systems are limited by the safety limits of the input power to the laser transmitter. A notable contribution in this paper is that we prove that this improvement with LT codes is within Maximum Permissible Exposure (MPE) limit for an FSO link for a BER performance of 10-5. Â© 2013 IEEE.
Optimal design and analyses of t-shaped rotor magnetorheological brake
(2019) Acharya, S.; Saini, T.R.S.; Kumar, H.
Magnetorheological (MR) brakes, belonging to the class of electromagnetic brakes, have a potential to replace conventional hydraulic brakes owing to reversible, rapidly controllable torque characteristics. In this study, T-shaped rotor MR brake was considered due to their higher braking torque capability and compactness compared to other configurations of brake. Optimal design of the brake was performed considering brake rotor radius, rotor thickness, flange length, casing thickness, coil height and coil width. Magnetostatic analyses were performed for different combinations of parameters of the brake dimensions to compute the magnetic flux density generated in the MR fluid region and the torque ratio and mass were calculated. The optimum dimensions of the brake were determined based on maximization of torque ratio and minimization of mass of the brake using multi-objective Genetic algorithm optimization technique. Further, magnetostatic analyses of the T-rotor brake with optimal dimensions were performed and torque characteristics were compared with those obtained for brake with simple disk rotor. It was concluded that T-rotor brake produces higher braking torque compared to simple disk rotor type MR brake for similar dimensions. � 2019 IOP Publishing Ltd. All rights reserved.
Optimal design and analyses of t-shaped rotor magnetorheological brake
(Institute of Physics Publishing helen.craven@iop.org, 2019) Acharya, S.; Saini, R.S.S.; Kumar, H.
Magnetorheological (MR) brakes, belonging to the class of electromagnetic brakes, have a potential to replace conventional hydraulic brakes owing to reversible, rapidly controllable torque characteristics. In this study, T-shaped rotor MR brake was considered due to their higher braking torque capability and compactness compared to other configurations of brake. Optimal design of the brake was performed considering brake rotor radius, rotor thickness, flange length, casing thickness, coil height and coil width. Magnetostatic analyses were performed for different combinations of parameters of the brake dimensions to compute the magnetic flux density generated in the MR fluid region and the torque ratio and mass were calculated. The optimum dimensions of the brake were determined based on maximization of torque ratio and minimization of mass of the brake using multi-objective Genetic algorithm optimization technique. Further, magnetostatic analyses of the T-rotor brake with optimal dimensions were performed and torque characteristics were compared with those obtained for brake with simple disk rotor. It was concluded that T-rotor brake produces higher braking torque compared to simple disk rotor type MR brake for similar dimensions. Â© 2019 IOP Publishing Ltd. All rights reserved.
Orthovanillin azine ester as a potential functional material for organic electronic devices
(Elsevier B.V., 2023) Kagatikar, S.; Acharya, S.; Mp, Y.; Dhanya, D.; Kekuda, D.; Abdul Salam, A.A.; Sudhakar, S.N.; Mn, S.; De, S.
The present study reports the synthesis of OVAE, an ester of ortho-vanillin azine, and its structural characterization using spectral and single crystal-XRD studies. Intermolecular interactions of OVAE are investigated using the Hirshfield surface analysis, 3D Hirshfield surface maps, 2D fingerprint plots, and electrostatic energy frameworks. Good thermal stability in thermogravimetric analysis, irreversible redox peaks in electrochemical studies, high carrier concentration and dielectric constant in electrical measurements, uniform films observed upon surface morphology examination, fabrication of a diode, the obtained current-voltage characteristics, dielectric constant and frequency-dependent AC conductivities directed towards the use of OVAE as a potential semiconducting functional material in suitable electronic devices. Based on cyclic voltammetry and AC impedance response, the performance of OVAE as an electrode material is explored by constructing a supercapacitor, which exhibited a specific capacitance of 56 Fg−1 at 10 mV s−1. © 2023 Elsevier B.V.
Selection of optimal composition of MR fluid for a brake designed using MOGA optimization coupled with magnetic FEA analysis
(SAGE Publications Ltd, 2021) Acharya, S.; Saini, T.R.S.; Sundaram, V.; Kumar, H.
The design of Magnetorheological (MR) brake and the composition of MR fluid (MRF) used in it have a significant effect on its performance and hence an effort has been made in this study to determine the optimal dimensions of MR brake and composition of MRF suitable for the brake application. Initially, optimum parameters of MR brake were computed considering the properties of commercially available MRF 132DG fluid using multi-objective genetic algorithm (MOGA) optimization. This was performed in MATLAB software coupled with magnetostatic analyses in ANSYS APDL software. The braking torque of designed MR brake utilizing MRF 132DG fluid was experimentally determined and validated with analytical ones. Further, selection of optimal composition of MRF was done considering In-house MRF samples composed of different combinations of particle mass fractions, mean particle diameters and base oil viscosities. A design of experiments (DOE) technique was employed and braking torque corresponding to the synthesized MRF samples at different speeds and current supplied were measured along with the variation of shaft speed during braking process. Grounded on the experimental results, using MOGA optimization technique, MRF composed of smaller sized iron particles (2.91 microns) with mass fraction of 80.95% and lower viscosity base oil (50 cSt) was selected as optimal composition of MRF for use in MR brake. Maximization of field induced braking torque and minimization of off-state torque were chosen as the objective functions for both the optimal design of MR brake and selection of optimal composition of MRF. Finally, the sedimentation stability of MRFs were investigated. © The Author(s) 2020.
Synthesis of magnetorheological fluid and its application in a twin-tube valve mode automotive damper
(SAGE Publications Ltd info@sagepub.co.uk, 2020) Madhavrao Desai, R.; Acharya, S.; Jamadar, M.-E.-H.; Kumar, H.; Joladarashi, S.; Sekaran, S.C.R.
The change in rheological properties of smart materials like magnetorheological fluid when brought under the influence of a magnetic field can be utilized to develop magnetorheological devices where the output has to be continuously and quickly varied using electronic control interface. In the present study, magnetorheological fluid is synthesized and used as a smart fluid in a twin-tube magnetorheological damper operating in valve mode. The behavior of the magnetorheological fluid is experimentally characterized in a rheometer and mathematically modeled using Herschel–Bulkley model. The parameters of the Herschel–Bulkley model are expressed as polynomial functions of strength of the magnetic field in order to find the shear stress developed by the magnetorheological fluid at any given strength of the magnetic field applied. The magnetorheological damper, which was designed for application in a passenger van, is tested in the damper testing machine. The performance of the damper at different damper velocities and current supplied is studied. The range of values for the parameters of the experimental testing are chosen to emulate the actual conditions of operation in its intended application. Nondimensional analysis is performed, which links magnetorheological fluid rheological properties and geometrical parameters of magnetorheological damper design with the force developed by the damper. Finite element method magnetics is used to find the strength of the magnetic field at the fluid flow gap. Analytical methods are used to calculate the damper force developed due to the field-dependent yield stress and compared with experimental force values. The resulting dynamic range of the magnetorheological damper is also assessed. © The Author(s) 2020.
Synthesis, characterization and selection of optimal constituents of magnetorheological fluid for damper application
(National Institute of Science Communication and Policy Research, 2025) Acharya, S.; Puneet, N.P.; Desai, R.M.; Sundaram, V.; Kumar, H.
Magnetorheological (MR) dampers are a category of energy dissipating devices that employ magnetorheological fluids which undergoes drastic change in its behaviour under the presence of magnetic stimulus. The damping characteristics of an MR damper predominantly depends on the dimensions of damper and on the constituents of MR fluid (MRF). In this work, an optimal MRF composition suitable for a monotube MR damper has been selected from six prepared MRF based on optimization. Initially, MR damper piston dimensions have been obtained by means of optimization. The damper has been fabricated and filled with commercial MRF 132DG™ fluid (Lord Corporation) and its performance has been tested. The experimental results have been validated with computational results. In the next part of the study, MRF samples composed of three particle weight fractions of fine and coarse sized iron particles have been synthesized and the rheological properties have been measured and compared with those of commercial MR fluid. The force-displacement characteristics of damper employing synthesized MRF have been determined with and without application of current to damper coil. Finally, by means of Multi-Objective Genetic Algorithm, optimum iron particle size and weight fraction have been selected from the pareto front solutions. © 2025, National Institute of Science Communication and Policy Research. All rights reserved.
Towards the systematic development of medical networking technology
(2011) Faust, O.; Shetty, R.; Vinitha Sree, S.V.; Acharya, S.; Acharya, R.; Ng, E.Y.K.; Poo, C.K.; Suri, J.
Currently, there is a disparity in the availability of doctors between urban and rural areas of developing countries. Most experienced doctors and specialists, as well as advanced diagnostic technologies, are available in urban areas. People living in rural areas have less or sometimes even no access to affordable healthcare facilities. Increasing the number of doctors and charitable medical hospitals or deploying advanced medical technologies in these areas might not be economically feasible, especially in developing countries. We need to mobilize science and technology to master this complex, large scale problem in an objective, logical, and professional way. This can only be achieved with a collaborative effort where a team of experts works on both technical and non-technical aspects of this health care divide. In this paper we use a systems engineering framework to discuss hospital networks which might be solution for the problem. We argue that with the advancement in communication and networking technologies, economically middle class people and even some rural poor have access to internet and mobile communication systems. Thus, Hospital Digital Networking Technologies (HDNT), such as telemedicine, can be developed to utilize internet, mobile and satellite communication systems to connect primitive rural healthcare centers to well advanced modern urban setups and thereby provide better consultation and diagnostic care to the needy people. This paper describes requirements and limitations of the HDNTs. It also presents the features of telemedicine, the implementation issues and the application of wireless technologies in the field of medical networking. © 2009 Springer Science+Business Media, LLC.
Virtual medical board: A distributed Bayesian agent based approach
(2013) Dutta, A.; Acharya, S.; Krishna, A.; Bhattacharya, S.
Distributed Decision Making has become of increasing importance to get solution of different real life problems. Application of agent and multi agent system in this Distributed Decision Support System is an evolving paradigm. One of such real life problem is medical board formation. But always formation of a medical board with a group of expert physicians may not be always possible due to lack of infrastructure, availability, time etc. In these situations the role of multi agent based distributed decision making can comes into play. In this paper we develop a Virtual Medical Board System in which a number of software agents (expert agents) act as a group of expert physicians with knowledge base(KB), reasoning capability. They coordinate with each other to diagnose a patient. Copyright � 2013 by Knowledge Systems Institute Graduate School.