Srivastava S.,Indian navy |
Chatterjee A.,Indian Institute of Technology Kanpur
International Journal of Mechanical Sciences | Year: 2014
Oscillations of solid bodies like boats interacting with liquids like water are commonly studied in the marine science community but less so in the broader mechanical sciences. This paper presents a clear and simple exposition of a basic problem in this field, for a general nonspecialist audience. A two dimensional analysis is developed from first principles of small free oscillations of a boat in inviscid water in a finite tank. The water motions obey the Laplace equation. The boat motions are not imposed, but rather found as a part of the overall solution using rigid body dynamics under time-varying pressures on the hull. The importance is clarified of the difference between nominal and displaced configurations of the boat. The equations for water, boat, and boundary conditions are assembled into an eigenvalue problem that determines the oscillation frequencies and mode shapes. The equations are discretized using a boundary element formulation, and the corresponding discrete version of the eigenvalue problem is constructed and solved. The mode shapes thus found include (i) a well defined roll-dominated oscillation, (ii) easily interpretible nearby equilibrium solutions ("rigid body" modes), and (iii) tank-scale sloshing-dominated modes. The roll frequency is found to vary negligibly with tank size, and goes to zero as the boat center of mass is moved to the metacenter. The net added inertia implied by the roll frequency is discussed. Finally, experiments conducted with two boat models, one round bottomed and one square, match roll frequencies predicted by the above calculations. © 2013 Elsevier Ltd.
Waghmare R.G.,Dr iversity Lonere |
Nalbalwar S.L.,Dr iversity Lonere |
Das A.,Indian navy
Procedia Engineering | Year: 2012
In underwater passive surveillance systems, narrowband displays help in classifying tonal sounds but transient sounds are largely classified through audition. Over the years, the intensity of tonal has been reduced by ship/submarine constructors, and so their use for classifying underwater targets has become diminished. Transient sounds are harder to disguise and are becoming more useful for detecting targets. In the naval scenario, quick and accurate detection of transient signals offers an advantage of longer response time to thwart an enemy attack. Underwater transients from manmade objects and biologics are very rich in structure and detail, very diverse in terms of duration, highly non-stationary, and often mixed with multipath. The need is for automatic detection and classification of underwater transients, in order to assist the overburdened sonar operator. Recently, the work on wavelet transform for transient signal detection is carried out but the problem with these detectors is that these are computationally very expensive. We are presenting a new kind of detector which works on energy of the segments and the corresponding mean of the zero crossings of the signal.
Das A.,Indian navy
Applied Acoustics | Year: 2011
Study and characterization of distant shipping component of ambient noise in shallow water aid in design of passive surveillance algorithms and effective signature analysis of marine vessels. This letter presents the work carried out on real ambient noise recording in very shallow water condition close to a commercial port with heavy shipping activity to study and characterize the distant shipping noise component for variations due to tide. Ambient noise recording was carried out by a bottom mounted sensor at 30 m depth at regular interval for a period of over one month and the spectrum in the band 10-1.6 kHz was characterized for its diurnal spectral variation. The study concluded that the distant shipping noise component due to heavy small vessel activity in the nearby port resulted in up to 35 dB variation in the shallow water ambient noise in coastal areas that may have serious implication on passive surveillance algorithms performance in the vicinity if adequately not addressed. This is the first such effort in ambient noise measurement and characterization in the extremely shallow water channel condition prevalent in the tropical waters off the west coast of India. © 2011 Elsevier Ltd. All rights reserved.
Vanithakumari S.C.,Indira Gandhi Center for Atomic Research |
Yadavalli P.,Indian navy |
George R.P.,Indira Gandhi Center for Atomic Research |
Mudali U.M.,Indira Gandhi Center for Atomic Research
Surface Innovations | Year: 2015
A close observation of natural lotus leaves provided the inspiration to develop superhydrophobic surfaces on marine steels to inhibit biofouling. Low-alloyed steel such as DMR 249A is chosen for the present study and modified using mechanical polishing, shot blasting, grit blasting, glass bead blasting and pickling, and coated with a low-surface energy material such as silane. The resultant samples are found to be superhydrophobic with apparent advancing water contact angles around 150° and tilting angles less than 5°. The surface morphology and surface roughness are analysed using scanning electron microscopy and surface proflometer. Depending on the surface treatment employed, the morphology and surface roughness vary widely and they are correlated to the wetting behaviour of the samples. The surface-modified marine steels are exposed to the bacterial cultures of Pseudomonas sp. to elucidate their antifouling behaviour. The exposure studies revealed less bacterial adhesion in surface-modifed samples as compared to the uncoated samples. The aim of this paper is to stress the unconventional use of superhydrophobic coatings based on silanes to inhibit biofouling on marine steels. © 2015, ICE Publishing. All rights reserved
Ray A.,Indian navy
RINA, Royal Institution of Naval Architects - Warship 2014: Naval Submarines and UUV's, Papers | Year: 2014
Prototypes for technology induction are rare for submarines. In the second half of the 20∗ century, several design prototypes were built in the USA and the erstwhile USSR as test platforms for radical new submarine technologies. These one-of-a-kind prototypes represented advances in hydrodynamics, propulsion, silencing, materials and payload that led to incorporation of new features in series production. In the present scenario of shrinking numbers of submarines in most navies, prototypes appear to be an unaffordable luxury. Their alternatives for new technology induction are discussed. Proposals are offered for fostering technological innovations, and for scheduling induction timelines for better management of the development process. © 2014 The Royal Institution of Naval Architects.
Narula K.,Indira Gandhi Institute of Development Research |
Narula K.,Indian navy
Renewable and Sustainable Energy Reviews | Year: 2013
Well designed Renewable Energy (RE) policies and their effective regulation is the key to promote RE generation in the world. Renewable Energy Certificate (REC) mechanism is a market-based policy instrument which facilitates Renewable (Energy) Purchase Obligations (RPOs) in order to increase RE generation in a country. The recently conceived and implemented REC mechanism in India attempts to involve various stakeholders in an economically efficient manner and has been effective in its first year of operation. The paper commences with the background and the genesis of REC mechanism in India. It characterises the REC trading mechanism and analyses the performance of the REC market for the FY 2011-12. Comparing the financial viability for sale of RE by project developers in certain key states, the paper shows that REC mechanism is more profitable than entering into a Power Purchase Agreement (PPA) for sale of RE at Preferential Tariff (Feed-in-Tariffs). Thus, the REC market which has attained a size of 2.3 billion INR in its first year of existence is forecasted to grow manifold in the future and the paper attempts to forecast the market size in near term. Further analysis of the REC market reveals that although there are inherent advantages of the REC mechanism over other methods of promoting growth of RE, the market is currently subject to various distortions and the paper suggests few steps for correcting these distortions by appropriate market re-design. The paper concludes that the REC market mechanism has gained momentum and can effectively promote RE generation in an economically efficient manner, with benefits to all stakeholders, provided it is strictly implemented and continuous corrections are given in the right direction by the market regulator. © 2013 Elsevier Ltd.
News Article | September 9, 2014
The foundation stone for the Naval Headquarters building complex named as ‘Nau Sena Bhawan’, was laid by Defence Minister Shri Arun Jaitley on 20 Aug 14 in New Delhi. On this occasion Minister of State for Defence Shri Rao Inderjit Singh, Chairman Chiefs of Staff Committee and Chief of Air Staff Air Chief Marshal Arup Raha, Chief of the Army Staff General Dalbir Singh, Defence Secretary Shri RK Mathur, Shri Arunava Dutt, Financial Advisor (Defence Services), Shri Avinash Chander, Scientific Advisor to RM and Secretary Department of Defence (R&D) & DG DRDO, and other senior officials of MoD and Navy were present. The state-of-the-art ‘Nau Sena Bhawan’ complex will be constructed adjacent to the DRDO Headquarters building on the land allotted to the Navy by the Ministry of Urban Development. While addressing the gathering, Admiral RK Dhowan emphasised that the construction of the building complex would mark a new high in terms of quality, ergonomics, time and Green factors. Having the same ‘facade’ as the existing DRDO building, the complex would be futuristic in design, space, habitability, parking and environmental aspects that would conform to the heritage norms of ‘Lutyens Bunglow Zone (LBZ)’ and imbibe modern ‘Green eco-friendly’ norms with’ zero-carbon footprints’. The construction of the complex would be steered by DRDO and would be in conformity with architectural surroundings, aesthetics and ambience of the area. The project would make use of latest construction technologies, materials, services and GRIHA norms giving due consideration to landscaping, energy & water conservation and solar power generation. At present, the Navy’s establishments in New Delhi function out of various dispersed locations, including the South Block, Sena Bhavan, A-Block hutments, buildings in R K Puram, Kailash Colony and Yashwant Place. The new headquarters complex will house offices of the Navy, which are required to be in close vicinity of South Block for functional requirements.
News Article | April 28, 2016
HYDERABAD, India - A biofuel manufacturing plant caught fire in southern India, triggering explosions in biodiesel tanks and forcing around 150 workers to flee the facility, officials said Wednesday. As flames rose and a giant column of black smoke filled the air, dozens of navy firefighters joined civil authorities to try to douse the fire, which started Tuesday night, said Rajesh Shetty, an Indian navy officer.
News Article | December 5, 2016
The Indian Navy celebrated Navy Day on Sunday, the 4th December 2016, with colorful performances by the personnel to cherish the vital role of the Indian navy.