Faculty Publications
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Item Power management of a hybrid PEMFC-PV and ultracapacitor for stand-alone and grid connected applications(2012) Naik, A.; Yaragatti, R.Y.; Kole, V.This paper presents the integration of photovoltaic (PV), fuel cell (FC) and energy storage systems for reliable power generation. In this system FC is used as main power source and power from PV whenever available is harvested completely with storage system compensating for power fluctuations. This topology has high efficiency, modularity and fuel flexibility. The sources in this hybrid system complement each other very well against environmental variations and load variations. Of the many storage systems the use of ultracapacitor gives advantage of absorbing and contributing to power transients quickly and efficiently. The aim of this study is to design an effective power management system for PV/FC/storage hybrid system thus to give high quality reliable power. MPPT for PV system is used for maximum power extraction. Finally the structure of hybrid system with control strategies for power management is discussed. The proposed hybrid system is modeled, simulated and verified by MATLAB/Simulink simulations for standalone and grid connected systems. © 2012 IEEE.Item Comparison of three popular control strategies used in shunt active power filters(2012) Naik, A.; Yaragatti, U.K.Active power filtering has gained more importance in the power quality arena as it gives best solution for all power quality issues. Shunt active power filtering is effective and the performance of such units largely depends upon the control strategies used for reference current generation. There are different techniques used for this. Here an attempt is made to compare three major methods used for generation of reference current. The results are obtained using these three methods for the same system under balanced and unbalanced supply voltage conditions. Matlab/Simulink is used to model and simulate the various components of the systems. © 2012 IEEE.Item A systematic approach to grid connected PV system(2012) Afroze, S.; Yaragatti, R.Y.; Naik, A.This paper proposes a detailed mathematical model of Photovoltaic(PV) array and a three-level control scheme of a single-phase grid-connected system including maximum power point tracker, voltage source inverter and its controller based on the MATLAB/Simulink tool. The PV model is developed by using basic circuit equations of the photovoltaic (PV) solar cells including the effects of solar irradiation and temperature changes. The perturb-and-observe algorithm is used to extract maximum power from PV arrays and deliver it to the inverter and PI control algorithm is used to control the three-level voltage source inverter. The simulation result shows the power sharing between PV and the Grid for any given load. Here generation of PV depends on the insolation of PV array. © 2012 IEEE.Item Inventory Management for Transmission Line Projects(Springer Science and Business Media Deutschland GmbH, 2021) Singh, C.K.; Naik, A.; Das, B.B.In the developing countries, the industrial development plays the key role for enhancing growth of the nation and the industries have basic necessity of continuous and day by day increasing demand for electricity. The transmission lines have the most important responsibility for the effective transmission of electricity, i.e. to transmit the electricity from the generating station to the load centres. In the recent days, the physical storage and distribution have vital roles to play for the organization. The importance of the management of stores for inventory management is related to eradicate the unused, surplus or leftover materials that add cost to the supply chain so as to cultivating the efficiency and the effectiveness of the store functions at the same time intends to maximize those areas, which can add value. Inventory management is complex and crucial task of any transmission line project. At present, the organisations normally set inventory targets using thumb rules or single-stage calculations. Thumb rules involve to set the number of days for supply as the coverage target. Single-stage calculations include the single item in the single location and thereby calculating the amount of inventory needed to satisfy or fulfil the demand. This study is trying to implement statistical inventory management model in the construction of transmission line projects. In this study, we will try to optimize the inventory level of a transmission line project to reduce the overall cost of project by reducing the excess cost associated with excess inventory. This paper is anticipated to help the decision-makers by enhancing the current performance of the store management in the construction projects by finding the economic order quantity to minimize the total inventory cost. © 2021, Springer Nature Singapore Pte Ltd.Item SUPER-NATURALINSTRUCTIONS: Generalization via Declarative Instructions on 1600+ NLP Tasks(Association for Computational Linguistics (ACL), 2022) Wang, Y.; Mishra, S.; Alipoormolabashi, P.; Kordi, Y.; Mirzaei, A.; Arunkumar, A.; Ashok, A.; Dhanasekaran, A.S.; Naik, A.; Stap, D.; Pathak, E.; Karamanolakis, G.; Lai, H.G.; Purohit, I.; Mondal, I.; Anderson, J.; Kuznia, K.; Doshi, K.; Patel, M.; Pal, K.K.; Moradshahi, M.; Parmar, M.; Purohit, M.; Varshney, N.; Kaza, P.R.; Verma, P.; Puri, R.S.; Karia, R.; Sampat, S.K.; Doshi, S.; Mishra, S.; Reddy, S.; Patro, S.; Dixit, T.; Shen, X.; Baral, C.; Choi, Y.; Smith, N.A.; Hajishirzi, H.; Khashabi, D.How well can NLP models generalize to a variety of unseen tasks when provided with task instructions? To address this question, we first introduce SUPER-NATURALINSTRUCTIONS, a benchmark of 1, 616 diverse NLP tasks and their expert-written instructions. Our collection covers 76 distinct task types, including but not limited to classification, extraction, infilling, sequence tagging, text rewriting, and text composition. This large and diverse collection of tasks enables rigorous benchmarking of cross-task generalization under instructions-training models to follow instructions on a subset of tasks and evaluating them on the remaining unseen ones. Furthermore, we build Tk-INSTRUCT, a transformer model trained to follow a variety of in-context instructions (plain language task definitions or k-shot examples). Our experiments show that Tk-INSTRUCT outperforms existing instruction-following models such as InstructGPT by over 9% on our benchmark despite being an order of magnitude smaller. We further analyze generalization as a function of various scaling parameters, such as the number of observed tasks, the number of instances per task, and model sizes. We hope our dataset and model facilitate future progress towards more general-purpose NLP models. © 2022 Association for Computational Linguistics.Item A novel MPPT controlled grid-connected photovoltaic system with dual functionality of active power injection and reactive power compensation in a single phase system(Universitatea Politehnica din Timisoara blucretiu@yahoo.com, 2012) Naik, A.; Yaragatti, R.Y.This paper deals with the study of integration of distributed generation with active power filtering functionality in a single- phase system. Here the active power generated by the photovoltaic (PV) system is injected into the grid system through a coupling capacitor whenever solar input is available and the remaining capacity of the power conditioning inverter is used to compensate for the reactive power demand. The control algorithm used in this paper is simple and easy to implement. The PV system is integrated through a novel and simple MPPT technique. The system is simulated and analyzed for a given non-liner load with and without renewable source at different atmospheric conditions using MATLAB/Simulink tool. The grid current becomes sinusoidal and in phase with the grid voltage and hence the source current THD is reduced to great extent.Item Modeling a grid connected photovoltaic system with perturb and observe based maximum power point tracking(2013) Naik, A.; Yaragatti, U.This article deals with the integration study of distributed generation (DG) in the form of a photovoltaic (PV) plant in a three-phase system. Here the active power generated by the photovoltaic (PV) plant is injected into the grid system through a current controlled dual inverter topology. The main contribution in this article is the dual inverter topology. In this topology, a three level inverter output is obtained which reduces the PV injected current harmonic distortion into the grid. The control algorithm used in this article is simple and easy to implement. The PV system is operated through a maximum power point tracking (MPPT) stage. Perturb & Observe (P&O) is the modeling approach of MPPT system operation. The system is simulated and analyzed for a different set of loads with renewable source at different atmospheric conditions using MATLAB/ Simulink tool. The grid current becomes sinusoidal with three levels inverter and compared to existing three levels methods the dual inverter method is simple and easy to implement.Item Gridable Electric Vehicle (GEV) Aggregation in Distribution Network to Support Grid Requirements: A Communication Approach(Walter de Gruyter GmbH info@degruyter.com, 2017) Hampannavar, S.; Chavhan, S.; Yaragatti, U.R.; Naik, A.Electric Vehicles (EV) can be connected to the grid for power transaction and also serve as distributed resource (DR) or distributed energy storage system (DESS). The concept of connecting group of EVs or gridable EVs (GEV) to the grid is called Vehicle-To-Grid (V2G). V2G is a prominent energy storage system as it is flexible and can be used to support the grid requirements in order to meet the time varying load demand. Optimal placement of GEV aggregation in power distribution network is very challenging and helps in maintaining stability of the power system for a shorter duration of time. In this paper, algorithm is developed for estimating parameters like Ploss, Qloss, Vpu based on past history and wireless access support for Control and Monitoring Unit (CMU) to aggregator agent communication is proposed using Long Term Evolution (LTE) protocol. The load flow studies are carried using MiPOWER software in order to obtain the optimal location for the placement of GEV aggregation in power distribution network. LTE physical layer is modeled using MATLAB/SIMULINK and the performance is analyzed using bit error rate (BER) v/s signal to noise ratio (SNR) curves. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.Item Design and analysis of dual output flyback converter for standalone PV/battery system(International Journal of Renewable Energy Research, 2017) Sabhahit, N.S.; Gaonkar, D.N.; Naik, A.In this paper, the cost comparison is carried out among flyback, forward and full bridge converters based upon the number of circuit components. The performance assessment in terms of efficiency of the PV array with MPPT controller using flyback and forward converter is detailed. The design and control of Photovoltaic/battery system using a flyback converter for stand-alone applications is presented. A flyback converter is used to get DC output along with an AC output for high frequency applications without employing an inverter. The PV/battery system uses photovoltaic array as the main source of power and a battery as the storage device. The energy input of the PV system is effectively utilized by adopting an MPPT technique and the storage battery is controlled to balance the load requirements using a bi-directional dc-dc converter. This system ensures that the load demand is satisfied under varying solar irradiance conditions and a constant voltage is maintained for different load conditions. The modelling and control strategy of the implemented system is realized in MATLAB/Simulink environment.Item Fully automatic ROI extraction and edge-based segmentation of radius and ulna bones from hand radiographs(PWN-Polish Scientific Publishers bbe@ibib.waw.pl, 2017) Simu, S.; Lal, S.; Nagarsekar, P.; Naik, A.Bone age is a reliable measure of person's growth and maturation of skeleton. The difference between chronological age and bone age indicates presence of endocrinological problems. The automated bone age assessment system (ABAA) based on Tanner and Whitehouse method (TW3) requires monitoring the growth of radius, ulna and short bones (phalanges) of left hand. In this paper, a detailed analysis of two bones in the bone age assessment system namely, radius and ulna is presented. We propose an automatic extraction method for the region of interest (ROI) of radius and ulna bones from a left hand radiograph (RUROI). We also propose an improved edge-based segmentation technique for those bones. Quantitative and qualitative results of the proposed segmentation technique are evaluated and compared with other state-of-the-art segmentation techniques. Medical experts have also validated the qualitative results of proposed segmentation technique. Experimental results reveal that these proposed techniques provide better segmentation accuracy as compared to the other state-of-the-art segmentation techniques. © 2017 Nalecz Institute of Biocybernetics and Biomedical Engineering of the Polish Academy of Sciences