共查询到11条相似文献,搜索用时 6 毫秒
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Many formulations have been developed so far to predict the wave height and period from fetch length and wind blowing duration for a constant wind speed. This study aimed to predict wave parameters from fetch length and meteorological factors by using triple diagram methodology based on Kriging principles. Proposed model results were compared with Joint North Sea Wave Project (JONSWAP) model which is used so commonly in the ocean and coastal engineering studies. For the implementation of the methodology hourly wave and wind data were obtained from a buoy located in Lake Ontario. Numerical and graphical comparisons demonstrated that the proposed method outperforms the classical formulation. 相似文献
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Recently, a mesh-size insensitive structural stress definition (Battelle structural stress method) has been proposed. This method gives a stress state at a weld toe with a relatively coarse mesh, such as up to 2t (t=plate thickness) or irregular mesh shapes. The structural stress definition is based on the elementary structural mechanics theory and provides an effective measure of a stress state in front of a weld toe. In this present study, a fatigue strength assessment was carried out for a side shell connection of a container vessel using both the hot spot stress and the structural stress methods. A consistent approach to computing extrapolated hot spot stress for design purposes based on converged hot spot stresses is described and current fatigue guidance is evaluated. Fatigue strength predicted by the two methods, i.e. hot spot stress and structural stress approaches, at hot spot locations of a typical ship structure are compared and discussed. 相似文献
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Jean-Baptiste Saulnier Alain Clément Teresa Pontes Pierpaolo Ricci 《Ocean Engineering》2011,38(1):130-147
To date the estimation of long-term wave energy production at a given deployment site has commonly been limited to a consideration of the significant wave height Hs and mean energy period Te. This paper addresses the sensitivity of power production from wave energy converters to the wave groupiness and spectral bandwidth of sea states. Linear and non-linear systems are implemented to simulate the response of converters equipped with realistic power take-off devices in real sea states. It is shown in particular that, when the converters are not much sensitive to wave directionality, the bandwidth characteristic is appropriate to complete the set of overall wave parameters describing the sea state for the purpose of estimating wave energy production. 相似文献
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To assist in the prototyping and controller design of point-absorber wave energy converters (WECs), an easy-to-implement hybrid integral-equation method is presented for computing the frequency-domain hydrodynamic properties of bodies with a vertical axis of symmetry in waves. The current hybrid method decomposes the flow domain into two parts: an inner domain containing the body and an outer domain extending to infinity. The solution in the inner domain is computed using the boundary-element method, and the outer-domain solution is expressed using eigenfunctions. Proper matching at the domain boundary is achieved by enforcing continuity of velocity potential and its normal derivative. Body symmetry allows efficient computation using ring sources in the inner domain. The current method is successfully applied to three different body geometries including a vertical truncated floating cylinder, the McIver toroid, and the coaxial-cylinder WEC being developed in the authors’ laboratory. In particular, the current results indicate that, by replacing the flat bottom of the coaxial-cylinder WEC with the Berkeley-Wedge (BW) shape, viscous effect can be significantly reduced with only minor negative impact on wave-exciting force, thus increasing WEC efficiency. Finally, by comparing to experimental measurements, the current method is demonstrated to accurately predict the heave added mass and wave-exciting force on the coaxial-cylinder WEC with BW geometry. If a viscous damping correction factor is used, the heave motion amplitude can also be accurately computed. 相似文献
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An assessment model for the fate and environmental effects of offshore drilling mud discharges 总被引:1,自引:0,他引:1
Charles G. Hannah Adam Drozdowski John Loder Kee Muschenheim Tim Milligan 《Estuarine, Coastal and Shelf Science》2006,70(4):577
The benthic boundary layer transport (bblt) model was developed to assess potential impact zones from drilling mud discharges from offshore oil and gas drilling. The model focuses on the drift, dispersion and concentration levels of the suspended fraction of the drilling mud fines in the benthic boundary layer with the assumption of a spatially homogeneous environment. The current version of the model includes a wave boundary layer, a breakup module for drilling mud flocs, a dose–response module for scallops, and a graphical user interface (GUI). The GUI was written in Java which makes the code largely platform independent. Simulations of suspended barite concentration near Sable Island on the Scotian Shelf during drilling in the fall of 1999 reproduce the very low concentrations (generally less than 1 μg L−1) observed during the Environmental Effects Monitoring program. However, the simulations also exhibited concentrations in excess of the no-effects concentration for scallops (100 μg L−1) prior to the sampling program. The model estimates that the potential impact on scallops in the vicinity of the drilling is a few days of lost growth over scales of a few kilometers. 相似文献
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参考目前国际上被广泛应用的第2代富营养化评价方法体系,结合我国近岸海域生态环境特点和监测资料现状,建立了一种以压力-状态-响应模式为基本框架、以富营养化症状为主的第2代近岸海域富营养化评价体系。实际应用结果表明,应用本方法得出的长江口海域富营养化状况评价结论,与目前国外主流评价方法的评价结论一致,而且本方法具有评价指标代表性强、数据资料易得、评价标准有据、方法简便易行等优点。 相似文献
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Most of the existing relevant materials have been obtained from experiments, in which evaluating the added mass at the resonant frequency corresponding to the peak of a frequency-response curve obtained from the “forced” vibration analysis is the most popular technique. In this paper, a simple experimental method was presented where the “free” vibration responses instead of the “forced” ones were used to determine the values of mah and Iap. The main part of the experimental system is composed of a floating body (model) and a spring–shaft shaker. The “free” vibration of this main part was induced by imposing on it an initial displacement (and/or an initial velocity), and from the time histories of displacements information such as the “damped” natural frequencies, damping ratios, sectional added mass coefficients (CV and CP) were obtained. Since the displacements of the spring–shaft shaker are “translational” and those of the floating body due to pitch motions are “angular”, a technique for the transformation between the associated parameters of the two components of the main part was presented. 相似文献