Research Publications
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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 Analysis of antifouling paints using drum test apparatus(RINA, 2015-12) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.Ship has been recognized as a major factor in introduction of non-native and harmful organisms which causes deleterious effects on the performance of the vessel. More than 70% of Invasive species worldwide have found to be due to hull fouling. To mitigate fouling, underwater parts of the vessels are coated with antifouling paints. Antifouling paints provide foul-free hulls up to a maximum of 95 % of the vessels underwater area. There are a number of types of these paints but “self-polishing coatings” are predominantly preferred by the shipping industry. In these types of coatings, a thin layer of biocide containing paint (typically 2 to 5 microns/month) is leached or “polished” away. This polishing action primarily depends on the hydrodynamic surface forces on the vessels hull. The higher the fluid velocity, the higher are the polishing rate. Certain areas of the vessel such as near the bow, stern, etc experience higher fluid velocity and therefore higher polishing rates thereby resulting in premature fouling. Conversely, areas where the flow rates are considerably smaller would experience lesser polishing rates which would result in insufficient amount of biocides being delivered which would again result in premature fouling. In order to study and estimate the polishing rates of Anti Fouling paint we have designed, fabricated a rotating drum test facility .Wall shear stress are to be calculated by CFD methodsItem Some statistical relationships among dredger particulars observed in the indian dredging fleet(International Conference on Ship and Offshore Structures, 2015-12) Arun Kishore, Eswara; Ramesh, U. S."Cutter suction dredgers(CSD), Trailing suction hopper dredgers (TSHD) and Grab dredgers form 88% of the total Indian fleet size, respectively in the order of individual share. Indian yards have achieved 90% indigenization in design and construction of grab hopper dredgers. However, there is a techno-economic backlog in India to manufacture some vital components for CSDs and TSHDs and companies are increasingly looking to buy foreign made dredgers at a high price. Dredging demand in India at ports and in navigable inland water ways is set to grow with the encouragement for water transport. Ministry of Shipping, Govt. of India has sponsored studies at Indian Maritime University – Visakhapatnam (formerly, NSDRC) for indigenization of dredger design and manufacture. The present paper aims to illustrate the existing dredger fleet of India and bring out some interesting correlations or conclusions that aid the design of dredgers. Dredgers are built for a specific function. Due to this design objective, they differ from other marine vessels on the aspects of principle particulars, hopper capacities, powering and other functional data such as cutter power for CSD and dredge pumps power etc. The identified correlations among a few parameters observed from the Indian dredging fleet are discussed. Certain ratios among the main dimensions for a TSHD such as length/breadth, breadth/dredge depth and breadth/draught, also known as ship ratios, are a key to dredger design and are known to vary with market conditions or time. They indicate design trends for future dredgers and require to be kept updated. "Item Energy saving strategy on electric propulsion system integrated with doubly fed asynchronous motors(IEEE, 2016-11) Singh, Raja R.; Chelliah, Thanga Raj; Khare, Deepak; Ramesh, U. S.Electric propulsion system integrated with doubly-fed asynchronous motor contributes efficient characteristics and flexibility in operation. However, in perception of energy saving and full-scale speed variation, the conventional doubly fed asynchronous motor is limited by the ratings of power converters. Generally, the electrical machines are designed to attain maximum efficiency around the full load. To increase energy saving and operating speed range under lightly loaded condition, the proposed strategy injects a low voltage DC supply to the stator winding instead of full rated AC supply. Wherein the DC supply is obtained from the converter's DC-link instead of external source. The proposed system is mathematically modelled using Matlab/Simulink tool and implemented experimentally with a 2.2 kW doubly fed asynchronous motor. In addition to this, the comparative energy conservation analysis of an electric propulsion system (2 MW) with the proposed strategy is carried out as a case study.Item Control strategy for fuel saving in asynchronous generator driven electric tugboats(IEEE, 2016-12) Anil Kumar, B.; Anil Kumar, K.; Radha, T.; Chelliah, Thanga Raj; Khare, Deepak; 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.