Journal Articles
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Item Drag reduction on vessels and study on its viability /(IJARIIT, 2019-02-23) George, Kevin Mathew; Bharotiyal, Prashant KumarThe most severe component in the resistance of a ship is the frictional one. As we know the source of this bare hull frictional resistance is the basic wave resistance and viscous resistance or drag. Drag as we know it is directly proportional to the area it acts upon. By reducing the frictional resistance through form optimization, and more viably and hence, more importantly, air lubrication, total resistance and so fuel costs can be decreased. Especially for existing ships, reduction of ship resistance by form optimization is difficult and not cost effective, but the application of air lubrication through injection methods like in the Mitsubishi air film injection study. Reducing the frictional resistance by air injection below the ship in combination with special coatings is an active area of research; anecdotally, performance gains are usually large. The paper gives an overview of some model scale and full-scale measurement results of ships. In this study, the air lubrication method is presented and the effect of air lubrication on resistance. The analyses are performed by a commercial code solving Navier-Stokes equations. The coefficient of frictional resistance of the ship is calculated as an equivalent flat plate of the ship’s wetted surface.Item Cosine similarity approaches to reliability of likert scale and items /(Hyperion University, 2018-02-02) Chakrabartty, Satyendra NathBased on cosine similarities, the paper proposes two non-parametric methods of finding reliability of Likert items and Likert scale from single administration of the questionnaire, considering only the frequency or proportion for each cell of the Item-Response category matrix without involving any assumptions of continuous nature or linearity or normality for the observed variables or the underlying variable being measured. Each method enables to find reliability irrespective of distribution of the observed or underlying variables and avoiding test of uni-dimensionality or assumption of normality for Cronbach's alpha or bivariate normality for polychoric correlations. The proposed methods thus are considered as improvement over the existing ones. Reliability as per Bhattacharyya's measure appears to be preferred over the Angular Association method as the former expresses test reliability as a function of item reliabilities. In addition to offering the computational steps, empirical verification with real data is given to illustrate the concepts and usefulness of the proposed non-parametric reliability procedures.Item Bandwidth analysis and optimization of ð§ shaped microstrip patch antenna with artificial neural network /(Innovative Space of Scientific Research Journals, 2017-09-02) Chakraborty, SamikIn this paper an artificial neural network optimization technique and models is used for analysis the bandwidth of Microstrip antenna. The Ч shaped Microstrip patch antenna designed and use operating frequency 6.83 GHz to analysis the bandwidth of antenna. Artificial neural network models used and varying the different parameters of Microstrip antenna to measure the bandwidth and its results is compared with artificial neural network results. The most common dielectric substrate Polyethylene =2.25. ANN is vey suited for analysis the proposed antenna and gives more easy calculation and design of microstrip patch antenna.Item Seakeeping analysis of an indian research vessel /(Elsevier, 2017-05-01) Ramesh, U S; Pavankumar, G V VA multidisciplinary research vessel Sagar Manjusha was considered for seakeeping analysis, which was exclusively used for deployment, maintenance and retrieval of data buoys, Tsunami buoys and so on. During rough sea conditions, the ship undergoes extreme rolling, which hinders deployment/retrieval operation. It also leads to seasickness for scientists and crew onboard. An experimental study was carried out to improve its seakeeping qualities. Ship Motion Reference Unit (MRU) data and the corresponding wave climate data were collected to study seakeeping capabilities. A model test was carried out in a towing tank facility and the design was optimized based on outcomes of test results. An Anti-Roll Tank (ART) was fabricated and installed on boatdeck. Inclination test was carried out in the presence of Indian Register of Shipping surveyor. Stability booklet was prepared as per class recommendation and the procedure was accepted by the class. It was observed during testing in rough sea condition that ship rolling had reduced by considerable amount, which in turn improved comfort and safety during extreme sea conditions. This experiment resulted in a transformation of an innovative idea into best outcome so that similar problems can be solved and the ship’s comfort, safety, productivity and so on can be improved considerably. Seakeeping analysis and installation of ART resulted in improvement in the safety of vessel, onboard machineries, instrument used for scientific research and quality of life onboard.Item Advanced in autonomous underwater vehicles : design and performance perspective /(OnePetro, 2014-01-01) Raj, Saurabh; Chandra, SauravAn Autonomous Underwater Vehicle (AUV) is a self-powered underwater information gathering system controlled by on board computer. An AUV has been designed basically to complete three tasks namely oceanographic sampling, exploration, and observation. Oceanographic instrumentation can be used for sampling and data collection in particular location under a specified depth. In current scenario when global warming has become a challenging task for our environment which will result in rising water level also, we can utilize autonomous underwater vehicle as most suitable tool for conduction of surveys concerning these global environmental problems. Future ocean sampling and surveillance systems should be capable of global deployment, sustained presence, three dimensional adaptive aperture, real time control and robust performance. These requirements can be met affordably by a network of Autonomous Underwater Vehicles (AUVs).Thus for the precision exploration we need more advanced and affordable vehicle. One of the most important components of an AUV is a sensor used for measuring different parameters in air and marine environment. Currently researchers need small, cheaper, efficient underwater sensors which can perform also in rough sea condition. Priced appropriately, and readily available with defined physical and software interfaces, these components open the door to the development of a low-R&D, simplified vehicle. Hydrodynamic properties and propulsion efficiency should be enhanced in order to improve the performance of the vehicle. Application of solar energy and variable buoyancy concept is to be utilized to improve the endurance of the vehicle. The autonomy of an AUV is to be modified in order to optimize efficiency. Biomimetics (bio inspired AUVs) are better performing, more efficient and have large potential scope of developing more advance AUVs.Item Underwater noise radiated by fishing vessels in visakhapatnam fishing harbor /(Journal of Offshore Structure and Technology, 2019-04-24) Kumar, G.V.V. Pavan; Ramesh, U.S.The sound has always been a better measure to understand the oceans. Among the various sources of underwater noise, mainly physical, biological and anthropogenic, it is seen that through the increase in anthropogenic noise in the oceans, the ambient noise levels are rising. Fishing vessel radiated noise has been a major concern in the fisheries acoustic scientific community due to the possible effects on altering the natural activities of the target species. The fishing vessel noise signature shall be valuable in building a quiet vessel with effective combination of the machinery in opposing excessive noise levels. In the present paper, the measurements of the underwater noise levels within the Visakhapatnam fishing harbor (VFH) limits are detailed to understand the fishing vessel radiated noise levels. The VFH is a bay spreading over 22 ha next to the Visakhapatnam Port channel entrance. At VHF, there are around 700 fishing boats engaged in fishing activity within the coast of Andhra Pradesh. A vertical omni-directional hydrophone and TASCAM handheld linear PCM recorder was deployed at five different locations with deployment depth of 2 m within the VHF bay. Fast Fourier Transformation spectral analysis program is used to post-process the time domain signal to the frequency domain. The measured data helped to understand the ambient noise levels within the VFH limits being ~120 dB re 1 μPa and with a distant boat idling having peak amplitude 136.97 dB re 1 μPa at peak frequency of 425 Hz. The regular fishing vessel movement recorded peak amplitude 160.39 dB re 1 μPa at peak frequency of 425 Hz. The changes in the ambient noise levels due to the fishing vessel movement recorded a significant increase in sound pressure levels (SPL) by about 20 dB. The increase in SPL is mainly due to propeller and machinery radiated noise which is clearly identified in lower frequency range <500 Hz. The measurements also helped to understand the effect of each vessel type on the ambient levels due to vessel movements, mainly during entrance and exit within the VHF bay. However, the noise pollution due to vessel movement has similar effects on the local environment, i.e., the residential area close to VFH.Item Infrastructure in india: contribution of ports to the economy and the road ahead /(2012-09-04) Rao, B.V. RamalingeswaraThe economic development of a nation depends on several factors, and a developed infrastructure sector is one of the key determinants. 21st century has mandated adequate investments by the government and private sectors in the infrastructure sector for sustainable economic development. Economic liberalization has allowed a free flow of investments across the world, and Multi-National Corporations (MNCs) are looking for safe avenues for easy investment and expansion. One of their primary issues of concern is obviously the status of infrastructure in the target country. India, being a favorable destination for investments from MNCs, attracts huge exports and imports. Port infrastructure is one of the key indicators of sound infrastructural setup of a country. Ports are the gateway for foreign trade and developed port facilities provide a platform for smooth exports and imports. Around 13 major and over 190 non-major ports in India contribute to around 95% in volume and 75% in value to Indian foreign trade. The substandard performance of Indian ports, in comparison to their counterparts, affects business. The present study aims to track the progress and advancements made by the Indian ports and their future scope for development. It also highlights the inherent constraints in the development of Indian ports and suggests certain pertinent measures to enhance the functioning of this key sector.Item Measurement of small vessel machinery vibration induced acoustic signature levels /(Journal of Naval Architecture and Marine Engineering, 2019-12-26) Kumar, GVV Pavan; Nagesh, B HShip vibrations, airborne and underwater noise levels have always been a challenging topic from a performance point of view in ship design, building and operation. The measurement shall help in monitoring the self-noise and the technical state of their machinery mechanism. The vibration levels on the main engine and auxiliary Genset foundation, airborne noise levels of the engine room and underwater self-noise levels of a small mechanized fishing trawler was measured at the jetty in idling condition. The vibration levels on the foundation measured the average value of 0.207 mm/s for the main engine and 1.36 mm/s for auxiliary Genset. The airborne noise levels measured 99 dB (A) in the engine room. The peak underwater sound pressure levels measured 162 dB re 1µPa. The response spectra indicate the peak vibration and noise levels in the lower frequency region <1.2 kHz. The machinery excitation forces transferred to the hull surface as pressure fluctuations which generated the airborne and underwater noise levels. Though the measurement limited to jetty conditions, detailed analysis can be useful for detection, classification, and tracking of small vessels.Item Computational design and analysis of a piston with different head thicknesses and top land widths /(Springer Nature, 2019-12-11) Kashiwal, MukulThe objective of this work is to check the structural performance of the piston, while changing some of its design parameters. This paper describes the modelling and analysis of piston, which has been done using Solid Edge and Ansys 16.0. Analysis was performed on the piston with different head thicknesses (TH) and top land widths (b1) to observe its structural performance. The comparison has been done by using different materials (Grey Cast Iron FG 200, Aluminium 4032 and AISI 1020 Steel) for the same geometry to observe the consequences. The deformation in the piston has increased slightly when we decreased the piston head thickness and top land width. Thorough observation has been done with respect to equivalent stresses and we found that AISI 1020 Steel is a better material for the piston among the three materials considered but the stresses are lowest in Aluminium 4032. For piston of 12 mm head thickness and top land width, the equivalent stresses and deformation are found to be maximum for all the three materials used and are minimum when the piston head thickness and top land width are 19 mm.Item Modification of hull design inspired by sailfish /(Institute of marine engineering, science and technology, 2019-11-05) Borah, SModification of hull design for improving performance and resistance in a ship has been of interest to ship building industries for decades. In the present study hydrodynamic analysis of morphological adaptations in sailfish having v-shaped protrusions on its skin has been done. The paper shall discuss a hull design integrated with v-shaped protrusions, inspired from sailfish. A quantitative analysis will be discussed with simulation proofs worked on Computational Fluid Dynamics (CFD) software. CFD results for total hydrodynamic resistance with detailed pressure distribution, velocity distribution, boundary layer separation are presented. The final result is an optimized hull form which shows interesting characteristics, as its overall resistance has de-creased in respect to a conventional hull.