Papers by Gajanan Navelkar
CURRENT SCIENCE, VOL. 120, NO. 4, 25 FEBRUARY 2021 622 Antonio Mascarenhas, Nitin Dabholkar, Jayu... more CURRENT SCIENCE, VOL. 120, NO. 4, 25 FEBRUARY 2021 622 Antonio Mascarenhas, Nitin Dabholkar, Jayu Narvekar, Shivanand Prabhudesai, Siddharth Ghatkar, Sadaf Ansari, Pramod Maurya, Elgar Desa, Anand Lokapure, Surekha Nagvekar, Gajanan Navelkar, R. Madhan, Fernando Vijayan, Vidish Shetye, Llewellyn Fernandes, Sanjeev Afzulpurkar and T. Suresh are in the National Institute of Oceanography, Dona Paula, Goa 403 004, India. *For correspondence. (e-mail: [email protected]) Technology demonstration of a novel seabed resident event-driven profiling system
A significant step in developing a prototype small AUV, called Maya, was achieved at the National... more A significant step in developing a prototype small AUV, called Maya, was achieved at the National Institute of Oceanography (NIO), Goa, India, in May 2006. The project received initial seed funding from NIO in 2003 and a subsequent full grant (2004-2006) from the Ministry of Communications and Information Technology (MIT), New Delhi, India. In addition, cooperative work was also carried out under the scope of the Indo-Portuguese Cooperation Programme in S&T with the group headed by Professor Antonio Pascoal, Institute of Systems and Robotics, Instituto Superior Tecnico, Lisbon, Portugal. This programme was funded through an exchange visit programme by the Department of Science & Technology, New Delhi, and GRICES (Gabinete de Relacoes Internacionais da Ciencia e do Ensino Superior), the International Relations Unit of the Portuguese Ministry for Science, Technology and Higher Education. This article describes the Maya AUV’s mechanical design, control systems, navigation, on board sen...
International Journal of Innovative Research in Science, Engineering and Technology, 2016
Autonomous Surface Vehicles (ASV) are vehicles that operate on the surface of the water without a... more Autonomous Surface Vehicles (ASV) are vehicles that operate on the surface of the water without a human in order to get multiple oceanic property details. ASVs are valuable in oceanographic domain, as they are more capable than moored or drifting weather buoys, but far cheaper. In the project, It has been configured an ASV having two hulls and two thrusters which will move at a certain speed through the surface of the water and it will take turn depending upon the speed variations of the thrusters. The Arduino Uno as the control kit has been used, and programmed accordingly in order to actuate the thrusters. In this project, two types of batteries are used. Batteries, either primary or secondary, are by far the most common choice of energy storage for past and present ASVs. In the power management section, several DC-DC converters, N-MOSFET, Gate Triggering Circuit has been used. In eagle board the packaging has done and formed a board which will be having the Arduino embedded on it with the other elements.
2016 IEEE/OES Autonomous Underwater Vehicles (AUV), 2016
The variations in oceanic variables that influence global climate, hypoxia in freshwater reservoi... more The variations in oceanic variables that influence global climate, hypoxia in freshwater reservoirs and in coastal waters as in the west coast of India, the rise of harmful algal blooms are amongst current problems that need to be understood through the assimilation of observational data collected in the horizontal, vertical and temporal scales into mathematical models of climate change. Conventional data collection techniques from ships, shore based stations, moorings, and data buoys permit such data collection but show gross under sampling as they are highly restrictive in space and time coverage. To address these issues, autonomous platforms such as Autonomous Vehicles (AUVs and ASVs), Langragian Profilers (eg. ALACE) are being used by several research groups. This paper is based on a concept patent on a thruster driven Autonomous Vertical profiler [AVP], and describes the developmental steps being taken on the integration of sensors, control electronics, communications and a Gra...
Acta Acustica united with Acustica
Acoustic characteristics of a subsurface, cold core eddy observed in the Bay of Bengal during sou... more Acoustic characteristics of a subsurface, cold core eddy observed in the Bay of Bengal during southwest monsoon period is presented based on CTD (Conductivity Temperature Depth) data from 42 stations. The effect of the eddy is to reduce the ambient sound speed by about 10 m.s sup(-1). Under the influence of the eddy, depth of SOFAR channel axis remains constant (1600 m) which otherwise should have shown a deepening in this region. Simulated ray arrival structure depicts the typical characteristics of weak acoustic wave guide in the Bay of Bengal - the early arrival cluster of near axial flat angle rays, later arrivals of deep turning rays followed by the weak latest arrivals of near-surface turning rays. The arrivals of the acoustic rays are delayed by about 100-200 ms under the influence of eddy. The intensity computations show that when the ray passes through the eddy, it suffers an additional loss of 20-25 dB. From the simulated travel time delays, the eddy profile is reconstruct...
Effect of the cold core eddy in the Bay of Bengal on acoustic propagation was analysed by parabol... more Effect of the cold core eddy in the Bay of Bengal on acoustic propagation was analysed by parabolic equation (PE) method. Source depth, frequency and propagation range considered respectively for the two numerical experiments are 150 m, 400 Hz, 650 km (case 1) and 1000 m, 70 Hz, 5000 km (case 2). Acoustic intensity levels varied from -20 to -35 dB in the upper 500 m (case 1). In the presence of the eddy, isolines exhibited deviations between 250 and 500 km range extending from 100 m to the abyssal region. Maximum insonified region is present in the vicinity of the channel axis depth which showed variations from 800 to 1500 m in case 2
Sound speed computed from annual mean temperature and salinity data of Levitus reveals that spati... more Sound speed computed from annual mean temperature and salinity data of Levitus reveals that spatial variation in the Arabian Sea is greater than that in the Bay of Bengal. Maximum spatial variation of sound speed in the Arabian Sea noticed between the depth levels 200 to 1500 m is due to the combined effect of variation in the salinity (to a larger extent) and temperature. In the Bay of Bengal though the spatial variation of sound speed is marginal, variations observed between 1500 m are brought about by warm Andaman Sea waters. The depth limited nature of annual mean sound speed profile for 2 marginal seas suggests that the effective acoustic channel lies much below (approximately 300 m) the surface. This results in acoustic propagation in the form of surface-refracted bottom-reflected (RBR) rays within the SOFAR channel
The coastal zone is prone to a diverse array of hazards which include natural ones caused by stor... more The coastal zone is prone to a diverse array of hazards which include natural ones caused by storm surges, tsunamis, sea level rise, hurricanes and floods and man made hazards caused by industrial effluents discharge, river runoff bearing sediments, nutrients, artificial fertilizers from agricultural fields and sewage discharge into the sea. The scientific challenges are clearly found in separating out
In a great number of practical applications, marine vehicles must follow spatial curves accuratel... more In a great number of practical applications, marine vehicles must follow spatial curves accurately. This objective is important in missions where autonomous underwater vehicles execute "lawn mowing" manoeuvres along desired tracks, without stringent temporal constraints. In the present paper, we focus on complementary filter based navigation and on the development and testing of two path following control laws for a
Communications in Computer and Information Science, 2010
... It is expected that there would be multiple profilers operating at various lo-cations, such a... more ... It is expected that there would be multiple profilers operating at various lo-cations, such as coastal seas, dams and other water bodies. ... In: Pillai, PRS, Supriya, MH (eds.) Proceedings of the International Symposium on Ocean Electronics (SYMPOL 2007), December11-14, pp. ...
Communications in Computer and Information Science, 2010
... Ranjan TN1, Arun Nherakkol1, and Gajanan Navelkar2 ... of the 29th Conference on Decision and... more ... Ranjan TN1, Arun Nherakkol1, and Gajanan Navelkar2 ... of the 29th Conference on Decision and Control, Hewall (December 1990) [9] Integration of Inertial Navigation System and Global Positioning System Using Kalman Filtering -Theses Report-Vikas Kumar N. Dept of ...
OCEANS 2006 - Asia Pacific, 2006
In this paper seafloor classifications system based on artificial neural network (ANN) has been d... more In this paper seafloor classifications system based on artificial neural network (ANN) has been designed. The ANN architecture employed here is a combination of self organizing feature map (SOFM) and linear vector quantization (LVQ1). Currently acquired echo-waveform data acquired using single beam echo-sounder from twelve seafloor sediment locations from central part of the western continental shelf of India is analyzed
... Maya. Authors: Afzulpurkar, S. Desa, E. Navelkar, G. Mascarenhas, AAMQ Maurya, PK Martins, H.... more ... Maya. Authors: Afzulpurkar, S. Desa, E. Navelkar, G. Mascarenhas, AAMQ Maurya, PK Martins, H. Madhan, R. Prabhudesai, S. Pinto, R. Marchon, N. Citation: Proceedings of the International Symposium on Ocean Electronics (SYMPOL-2007), 11-14 December, 2007, eds. Pillai, ...
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Papers by Gajanan Navelkar