The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform
Subrata K Chakrabarti - One of the best experts on this subject based on the ideXlab platform.
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hydrodynamics of Offshore Structures
2003Co-Authors: Subrata K ChakrabartiAbstract:The subject of hydrodynamics applied to Offshore Structures is vast. The topics covered in this book aim to help the reader understand basic principles while at the same time giving the Designer enough information for particular Designs. Thus, results are given with derivations, and applications are discussed with the aid of examples, with an overview of the advantages and limitations of the method involved. This makes the book suitable as a text for undergraduate and graduate students specializing in Offshore and ocean engineering. In addition, the final results, including tables and illustrations may be referenced directly without going through detailed derivations. They can therefore be used by Design and applications engineers involved in Offshore Structure Design. This title also introduces various types of Offshore Structures with reference to actual installations in various parts of the world. It describes wave mechanics and how to choose wave theories and Design waves. After a choice of Design wave is made, the author describes how this wave is used to obtain forces on a fixed Offshore Structure. If the Structure is allowed to move, various methods of obtaining the motions of the Structure are given. The short- and long-term responses are derived and different methods are described. The use of model tests to verify these methods at each step is shown.
Gertjan Ordeman - One of the best experts on this subject based on the ideXlab platform.
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ice loads the effect of climate change on arctic Offshore Structure Design
2020Co-Authors: Gertjan OrdemanAbstract:For the development of Arctic Offshore Structures, Design ice loads are required. These Design loads represent the ice loads a Structure may be exposed to for specified requirements. The Design ice loads depend on magnitude of the ice loads and on the probability of exposure to the ice loads. Both are impacted by local sea ice conditions. Climate change affects the sea ice conditions causing change in the ice loads Arctic Offshore Structures are expected to experience. To obtain accurate Design loads, the effect of climate change should be considered in defining those. Conventional methods to determine Design ice loads are based on historical data and assume this data can be used to represent the loads during the lifetime of the Structure. However, historical data cannot represent future ice conditions if climate change is considered as sea ice conditions will change. This means that the effect of climate change is not incorporated in the Design ice loads when these are based on conventional methods. To include the effect of climate change a new method needs to be developed. In this thesis, such a new method is proposed that enables to include the effect of climate change into the Design ice loads. Instead of historical data, the new method considers the future ice conditions. The method allows to base the Design ice loads on sea ice conditions that change over time. To determine Design ice loads, extremal distributions are used. Extremal distributions describe the probability of seasonal maximum ice loads. Commonly, the extremal distribution is based on data covering multiple seasons and cannot properly include inter-seasonal change in sea ice conditions. The new method allows to determine the Design ice loads based upon changing extremal distributions. The extremal distributions are determined for seasons separately based on sea ice conditions of one season only. For the proposed method, a concept referred to as an 'ice state' is introduced. Ice states describe a period of time in which the sea ice conditions are assumed to be constant. When sea ice conditions are constant, the corresponding short-term ice load distributions and the ice load frequency can be determined. Both are required to be able to determine the extremal distribution for one season. According to the new method, the increase of drift speeds causes increase of Design ice loads whereas the decrease of ice concentration, thickness and compressive strength causes decrease of the Design ice loads. Based upon expected future climate change scenarios, the new method indicates that Design ice loads are lower when compared to the Design ice loads according to the conventional method.
Zhao Gengxian - One of the best experts on this subject based on the ideXlab platform.
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hydrodynamic analysis in marine and Offshore Structure Design
China offshore Platform, 2008Co-Authors: Zhao GengxianAbstract:The widely used hydrodynamic analysis methods and relevant software are introduced in this paper,and their merits and advantages are illustrated and summarized.It is helpful for structural Designer to select appropriate method and software in hydrodynamic analysis of marine and Offshore Structures.
Martin Richard - One of the best experts on this subject based on the ideXlab platform.
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evaluation of pack ice pressure approaches and engineering implications for Offshore Structure Design
Cold Regions Science and Technology, 2018Co-Authors: Lawrence Charlebois, Robert Frederking, G W Timco, David C Watson, Martin RichardAbstract:Abstract A probabilistic model for ice forces on a caisson platform in the Beaufort Sea was used to evaluate two different approaches for describing pack ice pressure. The ridge-building equation in the ISO Arctic Offshore Structures standard was compared to a more recently derived exceedance curve (EC) approach. The results indicated that the EC approach yielded a wider range of pack ice pressures compared to ISO estimates; however, when these results were used to determine the ultimate ice force on the platform, the effect of the pack ice approach selected was minimal. The influence of floe size in affecting the pack ice pressure did not yield agreement amongst several data sets examined. Furthermore, the influence of adfreeze was examined but no definite relationship was quantified. The paper discusses the engineering implications of these results in the context of Offshore Structure Design. When evaluating the ice loads at a candidate site for Offshore development, relevant information on floe size distribution and pack ice thickness, concentration, and movement are required in order to assess the influence of pack ice pressure on Design calculations.
Farhad Lalji - One of the best experts on this subject based on the ideXlab platform.
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vortex induced vibration super upper response branch boundaries
International Journal of Offshore and Polar Engineering, 2008Co-Authors: Brad Stappenbelt, Farhad LaljiAbstract:The purpose of this study was to experimentally investigate the vortex-induced vibration response of cylindrical Structures with low mass ratio. Much of our understanding of vortex-induced vibration has been established through single degree of freedom and/or higher mass ratio experiments. The empirical relationships based on these data capture only the characteristics of the upper vortex-induced vibration response branch. The corresponding super-upper response branch observed in 2 degree of freedom systems at low mass ratio is shown to present significantly larger amplitudes and more regular oscillations. Understanding the boundaries of this super-upper response has implications for Offshore Structure Design. This study revealed that damping in addition to the mass ratio appears to be one of the governing parameters in establishing super-upper response branch vibrations. Based on the experimental evidence available, super-upper response boundaries are suggested, and the potential bearing of these on empirical Design formulations not considering the super-upper response are discussed.
