Journal Articles
Permanent URI for this collectionhttps://dspacenew8-imu.refread.com/handle/123456789/2069
Browse
13 results
Search Results
Item Underwater noise levels in Indian waters off the coast of Mormugao Port /(Taylor & Francis, 2019-06-25) Kumar, G. V. V. Pavan; Ramesh, U. S.Among various factors influencing the ocean noise levels, shipping traffic radiated underwater noise levels were identified as the major contributors. The increase in ambient noise levels due to natural and anthropogenic sources threatens the marine species communication. India has a coastline of 7,516.6 Km with 12 major and ∼187 minor ports. The hydrophone system measured for 39 days helped in investigating the distant shipping traffic lane noise levels and its influence on ambient noise levels of the region. The ocean noise levels measurement were ∼115 dB re 1 µPa for the prevailing environmental conditions. The noise exposure levels were ∼10 dB higher at <1 kHz due to ship passage to and from the port. The fish noise dominated the ambient sea noise mostly at high frequencies >1 kHz. The maximum and minimum range of shipping noise spectra for both the month’s data indicated peak sound pressure level in the lower frequency. Thus, the outcome of the measurements helped in understanding ocean noise levels off the coast of Mormugao Port and the influence of shipping traffic. A similar study for longer duration shall be useful to develop specific traffic lanes in the port entrance which is free from the mammal movements.Item Optimization with load prediction in asynchronous generator driven tugboat propulsion system /(IEEE, 2017-12-01) Ramesh, U. S.Mostly tugboats are powered by diesel-electric generators for meeting power of auxiliary loads and of electric motors for propulsive load. This paper proposes the optimal fuel management in diesel-electric generators considering doubly fed asynchronous machine (DFAM) as generator. An optimization problem is formulated to schedule the available power sources aiming for best possible fuel efficiency. The performance of optimal control strategies critically depends on future load applied in generator. Considering this for predicting tugboat load demand a simple predictive methodology is proposed based on the average mode time per cycle. The proposed control mechanism is able to respond to any sudden load change and also to emergency halt condition. DFAM as generator is considered for improving the system efficiency at low load region. Speed of the diesel engine is decided by the load demand. Output voltage and frequency of DFAM at variable speeds are regulated by power electronic convertors, connected in rotor circuit.Item Control strategy for fuel saving in asynchronous generator driven electric tugboats /(IEEE, 2016-01-01) Ramesh, U. S.Usually electric tugboats are equipped with diesel engine based electric generator for power production, battery for supplying power to auxiliary loads and electric motors for propulsion. This paper proposes control strategies for diesel engine and electric generators used in electric tugboat to improve energy efficiency of the system. Doubly fed induction machine (DFIM), asynchronous in nature, is considered in this research which serves as generator (power production). The speed of diesel engine is controlled in accordance with the power demanded by the tug. Output voltage and frequency of generator during sub-synchronous operation are regulated by controlling its rotor current with the help of power electronic convertors. Comparison of fuel consumption at fixed and variable speeds of operation is performed. From the test results, it is observed that the variable speed operation of diesel generator offers significant reduction in fuel consumption.Item Improved Fuel-Use Efficiency in Diesel–Electric Tugboats With an Asynchronous Power Generating Unit(IEEE, 2019-03-20) Ramesh, U. S.High capacity diesel-electric tugboats are employed at every modernized harbor for assisting big marine vessels and other harbor applications. Contemporary tugboats use multiple power sources to meet their propulsion and auxiliary on-board load demands. The effective utilization of multiple power sources leads to better fuel use efficiency with reduced emissions, economic, and environmental benefits. This paper presents a simple optimization technique for scheduling available power sources of a diesel-electric tugboat [diesel engine generators (DEGs) and batteries] to meet its load demand with an objective to minimize fuel consumption. For this paper, a diesel-electric tugboat system of 1.1-MW capacity with different generating systems is considered: 1) fixed speed generating unit (2 × 550 kW fixed speed DEG employing synchronous generators) and 2) variable speed generating unit [1×1.1 MW variable speed DEG employing doubly fed induction generator (DFIG)]. From the optimized test results, it is inferred that the variable speed generating unit offers a fuel saving of 29.86% in comparison with diesel-mechanical propelled system and 2.9% in comparison with fixed speed diesel- electric system. The simulation of a 1.1-MW variable speed generating system is performed in MATLAB/Simulink 2014A environment, and experimental demonstration is performed through a 2.2-kW laboratory prototype.Item Need of natural biocides in antifouling paints for prevention of marine pollution(International Journal of Innovation Research & Development, 2015-07) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S."Antifouling paints were developed to prevent marine growth on ship hulls in the middle of the 19th century. As they were designed to continuously leach biocides at the paint/seawater interface which were the predominant means of controlling fouling for a vast majority of the vessels, over a period of years in the latter part of the last century there has been a marked improvement in the effective life of antifouling paints. Different types of antifouling paints came into being but after a particular breakthrough when self- polishing paints were developed in 1960s. Due to its controlled leaching rate, the self -polishing paints containing TBT was a huge success. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. It was observed that the extensive use of copper based antifouling paints has led to the accumulation of copper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. Foul release coatings are biocide-free –works on a foul release basis by providing a very smooth, low-friction surface which reduce the strength of adhesion of fouling. However, they are applicable only to high- speed, high-activity vessels, in addition to other issues such as high cost, difficult, application procedure and are easily prone to mechanical damage. Biocides from natural products appear to be the only viable alternative in the foreseeable future to protect ship hulls from fouling. This paper reviews the possible natural products that have the potential to be incorporated in to commercial antifouling paints and explores their range of activity"Item Information needs and usage pattern in maritime industry - Considerations & need for setting up a national documentation centre for maritime information(International Journal of Innovation Research & Development, 2015-07) Padmashree, S.; Ramesh, U. S.In any field of study, R & D requires information and information resources and services, through which National development is directly affected. Keeping in view the maritime information needs of our country by government establishments, the industry and the corporate sector an attempt has been made in this paper to show the need for setting up of a “National Documentation Centre for Maritime Information”. The model design of NDCMI and its possible services have been sketched out for further review and suggestions from its stakeholders.Item Failure analysis of antifouling paints on ships hull(NISCAIR-CSIR, India, 2014-11) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.Fouling on ships hull occurs due to the attachment of barnacles, mollusks and other aquatic organisms on the underwater area of the hull. This leads to increased drag, fuel consumption, resulting in unscheduled dry-docking. Recent advances in antifouling (AF) paints, in general, offer protection against fouling in about 95 % of the vessels immersed surface. However, the remaining area which amounts to 5% or less of the total area does get fouled. Although this level of fouling has marginal impact on the routine performance of the vessel, it is a predominant vector for the transmigration of invasive species which is a serious environmental concern. Virtually all ocean going vessels are coated with antifouling paints, predominant among them are “Self polishing coatings”. These coatings depend on the shear forces on the hull surface caused by the motion of the vessel for the paint to “polish” away and release a biocide at a predetermined rate that results in the hull to be essentially fouling free. Currently hulls are coated with a uniform layer of antifouling paints. However, computational fluid dynamics (CFD) analysis conducted on various types of vessels have indicated that there are certain “hotspots” where shear stresses and therefore the polishing rates are exceedingly high which would polish the AF paints at a much faster rate and ultimately result in the failure of the AF coating. The analysis also indicates that these hotspots primarily depend on the profile of the vessels, its speed and its draft. The current practice of a uniform coat of AF paint does not take into account the fact that there are certain areas of the vessel where the polishing rates are excessive. A possible solution to this issue is to first identify these hotspots and suitable paint schemes/formulations are to be applied in these areas. Such painting schemes would prevent the premature failure of the AF coating in general and significantly reduce the risk of transmigration of invasive species.Item Improving the efficiency of marine power plant using stirling engine in waste heat recovery systems(International Journal of Innovation Research & Development, 2012-12) Ramesh, U. S.; Kalyani, T.Energy seems to be the subject at the heart of many of the greatest issues and debates facing the world today. Global warming is a huge issue that promises to change the face of the planet in unimaginable and irreversible ways. This alone is considered as a major driving factor in development of energy efficient technologies for various purposes including marine transportation for sustainable development. The predominant source of power in a ship is the Diesel engine which has evolved as a highly efficient means of generating necessary power for propulsion and auxiliary uses However it is widely recognized that about 30% of the total energy converted in a Diesel engine is rejected in the exhaust gas. . On large ships some of this heat is recovered partly using exhaust gas boilers. However on a majority of small ships or on large ships on short voyage durations, there is no or limited mechanism to recover this energy. The recently mandated energy efficiency design index (EEDI) has the provision to deduct the power produced from any energy saving device thereby giving credit to the design. While some of the energy saving devices being contemplated, use wind and solar power, it is being recognized that some of the energy from the engine exhaust gases and cooling water can still be tapped to generate power resulting in improved energy efficiency of the plant. One of the ways of utilizing waste heat without conversion to steam is to use a Stirling engine. A Stirling engine requires only an external heat source (such as external combustion chamber or waste heat) for its operation. For marine use this engine could be utilized to generate some amount of power from the exhaust gas. This paper advocates the use of heat balance studies for improving the efficiency of the marine power plant. An estimation of the power which could be generated from a Stirling engine is presented based on estimation of the power which could be produced from the exhaust gas of a high speed (560 KW) propulsion engine and expected savings in fuel.Item Environmentally friendly antifouling paints and painting schemes(International Journal of Innovation Research & Development, 2012-12) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.Since the 1970's Tributyl tin based antifouling paints were widely used to control fouling on ships hulls. These coatings offered up to 5 years of foul-free hulls and were the most effective antifouling paints ever produced. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. However, the extensive use of copper based antifouling paints has led to the accumulation of cooper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. This paper explores the possibility of incorporating environmentally friendly biocides in antifouling paints that exhibit a low persistence in the marine environment particularly those biocides that are available in the Indian context. Another serious problem facing the marine environment is the issue of Invasive species. In recent years the issue of invasive marine species has been receiving considerable attention due to the fact that introduction of non indegenous species or non-native species transmigrated from other areas to coastal waters often results in the reduction and even extinction of the native species and thereby severely disrupts the natural marine ecosystems. The predominant vector for the transport of nonindigenous species in marine environments has been shipping. While ballast water receives the most attention, hull fouling is now considered to be the most significant means for translocation of these organisms. Certain niche areas of the vessel such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled. Although this fouling does not affect the overall performance of the vessel, would however, be a vector for the transportation of Invasive species. In addition, the other areas that are likely to be fouled are on locations where antifouling paint has been worn of due to excessive shear and bending of the hull. This paper attempts to identify such areas using CFD simulations and suggest that special paint schemes must be incorporated in these niche areas.Item Antifouling paint schemes for green ships(Ocean Engineering, 2019) Mukherjee, A.; Madhu, Joshi; Misra, S. C.; Ramesh, U. S.Recent advances in antifouling (AF) paints in general prevent fouling in about 95% of the vessel's immersed surface. However the remaining area which amounts to 5% or less of the total area does get fouled. Although this level of fouling has marginal impact on the routine performance of the vessel it is a predominant vector for the transmigration of invasive species which is now a serious environmental concern. Virtually all ocean going vessels are coated with antifouling paints predominant among them are “Self polishing coatings”. CFD analysis conducted on various types of vessels have indicated that there are certain “hotspots” where the polishing rates are exceedingly high and would polish the AF paints at a much faster rate and ultimately result in the failure of the AF coating. A possible solution to this issue is to first identify these hotspots and suitable paint schemes/formulations are to be applied in such areas. An experimental procedure utilizing a “drum-test” apparatus can be used to compute the coating thicknesses based on wall shear stresses. Such painting schemes would prevent the premature failure of the AF coating in general and significantly reduce the risk of transmigration of invasive species in particular.