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ABSTRACT In the present paper a multi objective optimization mathematical model of a Floating Flexible System (FFS) subjected to regular incident waves is developed and presented. FFS is considered as a system for both wave energy production and protection. The performance criteria considered for the optimum design of the FFS are the produced power, the protection effectiveness of the area behind the FFS, and the structural integrity of system parts. A mathematical approach is developed, based on genetic algorithms and global criterion method, in order to properly address FFS's design variables towards a most preferable (optimum) design. INTRODUCTION FFS present nowadays one of the most characteristic types of offshore and coastal structures that can be utilized in the sea environment in order to develop modern and sophisticated projects that address new trends and needs and satisfy new requirements. Floating island cities, floating entertainment facilities, floating emergency bases, floating storage bases of oil or water, floating wave energy devices, floating offshore wind turbines and/or sea water desalination plants, floating bridges and breakwaters represent characteristic current and future potential FFSs. The design of an effective FFS in terms of desired performance, properly defined, is the key element for their successful implementation. Performance should include the structural integrity of system parts that compose the FFS and more specifically the avoidance of any structural failure of the connectors of the modules of the FFS. Meanwhile, significant opportunities and benefits have been identified in the area of ocean wave energy due to extremely abundant and promising resource of alternative, renewable and clean energy in the world's ocean (Falnes, 2007). FFS present a major category of wave energy converters that up to now numerate a very large number of proposed and developed energy devices (Drew et al., 2009, Falnes, 2007 and Falcao, 2010).
- North America > United States (0.46)
- Asia (0.46)
- Europe > Greece (0.28)
- South America > Brazil (0.28)
ABSTRACT: The risk of failing to achieve the acceptable performance (performance risk) of a free floating structure under the combined action of various wave frequencies is investigated in the frequency domain. Here, performance is quantified in terms of no exceedance of a threshold for the response level corresponding to each degree of freedom. Quantification of the performance risk is based on a Monte Carlo simulation technique. The numerical analysis of the free floating structure is carried out using a three dimensional hydrodynamic analysis. Several cases of different combinations of wave frequencies are investigated. The second-order hydrodynamic interactions of pertinent wave frequencies are considered in the analysis for each combination examined. Two issues are investigated, namely:performance and performance risk for the free floating structure considered. The performance and risk levels of the second-order solution are compared with the results of the corresponding first-order solution in order to investigate the significance of second-order quantities in the assessment of both performance and performance risk levels. According to the results generated by the present study, secondorder wave effects can generally strongly affect performance and performance risk levels. INTRODUCTION Considering the case of a free floating body subjected to the simultaneous action of two or more wave frequencies, non-linear hydrodynamic analysis needs to be carried since second-order wave effects can highly affect the response of the free floating body. This happens because several effects can hardly be predicted when using linear (first-order) theory, such as wave drifting and interaction between wave trains of different frequencies (Murao, 1960; Newman, 1990 and 2004 and McIver, 1992). For this reason, plenty of investigations, relevant to the analysis and computation of second-order wave effects have been carried out including among others Kosmeyer et al. (1988), Lee (1991) and Kim M.H. (1992 and 1993).
- Europe (1.00)
- North America > United States (0.28)
- Asia > Japan (0.28)