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| Registros recuperados: 25 | |
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| Raillard, Nicolas; Prevosto, Marc; Pineau, H.. |
| Design optimization is crucial as offshore structures are exposed to deeper and harsher marine conditions. The structure behaviour is dependent on several joint environmental parameters (wind, wave, currents, etc.). Environmental contours are useful representations to provide multivariate design conditions. However, these contours may lead to different design points depending on the method used to compute them, and thus may be misleading to structural engineer. In this work, we propose to use a response meta-model for the inter-comparison of some state-of-the-art methods available for modelling multivariate extremes, in order to provide a straightforward methodology, focusing on the derivation of three-dimensional contours. The considered case study... |
| Tipo: Text |
Palavras-chave: Multivariate extreme value modelling; Environmental contours; POT; Joint probability distribution; Sea state; Engineering design. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00498/60948/64413.pdf |
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| Stringari, Ce; Prevosto, Marc; Filipot, Jean-francois; Leckler, Fabien; Guimaraes, Pv. |
| This paper presents a novel method for obtaining the probability wave of breaking (Pb) of deep water, dominant wind‐sea waves (that is, waves made of the energy within ±30% of the peak wave frequency) derived from Gaussian wave field theory. For a given input wave spectrum we demonstrate how it is possible to derive a joint probability density function between wave phase speed (c) and horizontal orbital velocity at wave crest (u) from which a model for Pb can be obtained. A non‐linear kinematic wave breaking criterion consistent with the Gaussian framework is further proposed. Our model would allow, therefore, for application of the classical wave breaking criterion (that is, wave breaking occurs if u/c > 1) in spectral wave models which, to the... |
| Tipo: Text |
Palavras-chave: Wave Breaking; Gaussian Field Theory; Wave Modeling. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00677/78894/81199.pdf |
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| Guanche Garcia, Yanira; Prevosto, Marc; Maisondieu, Christophe; Bulteau, Thomas; Paris, François. |
| The knowledge of extreme events of environmental variables is an issue of increasing concern to the scientific community. Within the branch of coastal and ocean engineering there are many fields of application where an accurate estimation of long term return period events is needed, i.e. coastal defenses design, coastal flooding management, estimation of changes of the littoral morphology, offshore and onshore renewable energy devices design, etc. But not only the engineers are concerned by extreme events; biological communities in the open sea and estuarine systems are also exposed to extreme events that may affect its natural development (i.e. extreme sea levels in estuarine environments could raze fields of plants not able to deal with salt in just a... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00378/48967/49370.pdf |
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| Venugopal, Vengatesan; Davey, Thomas; Smith, Helen; Smith, George; Holmes, Brian; Barrett, Sean; Prevosto, Marc; Maisondieu, Christophe; Cavalieri, Luigi; Bertotti, Luciana; Lawrence, John; Girard, Francoise. |
| This report gives guidance relevant to the resource assessment of sites considered for the deployment of wave and tidal energy converters. Areas considered include: instrumentation and measurement; techniques and requirements for wave and tidal parameterisation; wave-current interaction; spatial and temporal variation. A number of case studies are also included examining several European sites. |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00250/36152/34706.pdf |
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| Paillard, Michel; Prevosto, Marc; Barstow, Sf; Soares, Cg. |
| The MAST II WAVEMOD Project aimed at improving stochastic modelling of ocean waves and currents in coastal waters. In order to supplement existing data, two measurement campaigns were carried our, one on the Atlantic coast of Portugal, and, secondly, on the northern coast of Crete in the Mediterranean. The Portuguese measurements covered 7 months during winter 1993-1994, while off Crete, measurements started early in February 1994 and continued for 10 months, In both sites, two directional Waveriders and one non-directional Waverider were deployed along a transect our from the coast in water depths between 10 and 100 m. In addition, the Mediterranean site also incorporated measurements of mean current velocities. Available satellite data were analysed to... |
| Tipo: Text |
Palavras-chave: Waves; Currents; Portugal; Greece. |
| Ano: 2000 |
URL: https://archimer.ifremer.fr/doc/00000/10506/66722.pdf |
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| Prevosto, Marc; Soulard, Thomas. |
| When Newman's approximation is used to calculate the low frequency part of the nonlinear transfer between the waves and the forces on an LNG carrier, the CPU time to make the time series reconstruction of wave loads is a small part of the total. However, using full QTF-matrices increases the required work by a factor equal to the number of wave components in the sea states and the total simulation time can be increased by 5 or 10. Moreover, if we consider the multi-directional sea, the double summation becomes a quadruple summation at second order which is extremely time-consuming. There is a way to accelerate this computation by making an algebraic or system approximation of the QTF. The aim of this report is to present the solutions, the problems and the... |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00239/34986/33520.pdf |
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| Klinghammer, Christian; Prevosto, Marc; Le Boulluec, Marc; Perignon, Yves. |
| Up to this day, design recommendations or practices for floating structures, such as DNVs RP-C205 and F205 for example, do not account for the existence of low frequency free Infragravity (IG) waves. These are low-frequency water waves which represent an additional excitation for (moored) floating structures. In this study, the influence of free IG waves on moored floating structures response is investigated and compared to second-order low-frequency wave forces, as the standard low frequency excitation, for two selected important free IG events in 2013 and 2014 at the SEM-REV (Site d'Experimentation En Mer - Récupération de l'Energie des Vagues) test site near Le Croisic, Pays-de-la-Loire, France. The wave forces and motion response for two example... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00384/49584/50094.pdf |
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| Filipot, Jean-francois; Guimaraes, P.; Leckler, Fabien; Hortsmann, J.; Carrasco, R.; Leroy, Elodie; Fady, N.; Accensi, Mickael; Prevosto, Marc; Duarte, Rui; Roeber, V.; Benetazzo, A.; Raoult, C.; Franzetti, M.; Varing, Audrey; Le Dantec, N.. |
| This paper presents results from an experiment designed to improve the understanding of the relationship between extreme breaking waves and their mechanical loading on heritage offshore lighthouses. The experiment, conducted at La Jument, an iconic French offshore lighthouse, featured several records of wave, current and structure accelerations acquired during severe storm conditions, with individual waves as high as 24 m. Data analysis focuses on a storm event marked by a strong peak in the horizontal accelerations measured inside La Jument. Thanks to stereo-video wave measurements synchronized to the acceleration record we were able to identify and describe the breaking wave responsible for this intense loading. Our observations suggest that this giant... |
| Tipo: Text |
Palavras-chave: Extreme wave; Wave breaking; Wave loading. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00513/62480/66803.pdf |
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| Olagnon, Michel; Prevosto, Marc; Ozanne, Philippe. |
| This report gives some examples of instrumentation used or anticipated for use on some fixed platforms, aimed at obtaining answers to the questions posed by the heads of petroleum industries concerning the design techniques of these platforms : validity of calculations, guarantee of a normal behaviour of structures until the end of their anticipated serviceable lifetime, detection of serious damage, possibility of extending the serviceable lifetime of structures beyond the lifetime initially anticipated. |
| Tipo: Text |
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| Ano: 1986 |
URL: https://archimer.ifremer.fr/doc/00480/59128/61756.pdf |
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| Raillard, Nicolas; Prevosto, Marc; Ailliot, Pierre. |
| Many records in environmental science exhibit asymmetries: for example in shallow water and with variable bathymetry, the sea wave time series shows front–back asymmetries and different shapes for crests and troughs. In such situation, numerical models are available but their computational cost and complexity are high. A stochastic process aimed at modeling such asymmetries has recently been proposed, the Laplace moving average process, which consists in applying a linear filter on a non-Gaussian noise built using the generalized Laplace distribution. The objective is to propose a new non-parametric estimator for the kernel involved in the definition of this process. Results based on a comprehensive numerical study will be shown in order to evaluate the... |
| Tipo: Text |
Palavras-chave: Laplace moving average; Non-linear time series; FIR estimation; Splines; High-order spectrum; Asymmetries. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00201/31189/29588.pdf |
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| Prevosto, Marc; Le Louarne, Jean-franois; Guede, Zakoua. |
| In this study we discuss various methods to assess the statistics of extreme response of a floating structure subjected to random waves. This issue is of great importance in the case of low frequency motion of floating bodies in shallow water. Those methods are based on the evaluation of the level crossing rate, which is easily related to the extreme value statistics for stationary random processes and large levels. Four main methods are considered, namely the Rice formula with either a Gaussian assumption or an approximation of the joint distribution of the response and its first derivative by a projection method; the Breitung's formula; the Hagberg's approaches using either an asymptotic expansion or a Monte-Carlo integration and finally the time domain... |
| Tipo: Text |
Palavras-chave: Low frequency motion; Shallow water; Second order wave loading; Crossing rate; Extreme response. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/acte-6329.pdf |
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| Prevosto, Marc. |
| The statistics of the elevation and kinematics of waves in real seas are very rarely accessible from in-situ measurements which induced very high costs. An alternative to the actual waves observation is to derive from the spectral climatology of waves, completed with other environmental data like the wind and the current, the statistics of the individual waves. But this requires accurate models of irregular gravity waves which take into account all the main nonlinearities and interactions with the local wind, current and bathymetry. In a first step, methodologies have been based on second order irregular wave 3D models and have supplied the engineers with new better accurate models of statistics of wave crests. These models do not include yet the complex... |
| Tipo: Text |
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| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00116/22715/20457.pdf |
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| Monbet, Valérie; Ailliot, P; Prevosto, Marc. |
| The knowledge of sea state and wind conditions is of central importance for many offshore and nearshore operations. In this paper, we make a complete survey of stochastic models for sea state and wind time series. We begin with methods based on Gaussian processes, then non-parametric resampling methods for time series are introduced followed by various parametric models. We also propose an original statistical method, based on Monte Carlo goodness-of-fit tests, for model validation and comparison and this method is illustrated on an example of multivariate sea state time series. (C) 2006 Elsevier Ltd. All rights reserved. |
| Tipo: Text |
Palavras-chave: Model validation; Simulation; Nonlinear time series; Wind; Sea state. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2679.pdf |
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| Puillat, Ingrid; Prevosto, Marc; Mercier, Herle; Thomas, S.. |
| In our time emerged the idea of a major environmental degradation, at both local and global scales, in the face of the recurrent human pollution. Consequently in the sake of a sustainable humanity development, of the ethic and of the ecology, the protection and the monitoring of our environment have become a major stake. Many scientific and technical tools contributed to improve the environmental knowledge, as helped remote and in situ observations, and forecast modeling. In situ environmental sensor systems have been designed to be increasingly sustainable even in a hostile environment such as the deep ocean. In a similar way, the infrastructures hosting those sensors are now thought and built to be permanent. In marine sciences these considerations gave... |
| Tipo: Text |
Palavras-chave: Time series; Marine data; Signal processing; Statistics. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00161/27259/25468.pdf |
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| Prevosto, Marc; Van Iseghem, Sylvie; Moreau, Benjamin; Forristall, George Z.. |
| Despite its great theoretical and practical importance, the statistical distribution of crest heights has remained poorly known. The uncertainties are due to difficulties both with the theory, where nonlinear effects must be accurately modeled, and with measurements, where different sensors appear to give different results. In response to this uncertainty, the Wave Crest Sensor Intercomparison Study (WACSIS) was formed as a Joint Industry Project in order to provide data for comparing the response of wave sensors and for comparing theories of crest height distributions with the measurements. The key to the WACSIS experiment was to place all of the popular sensors on the same platform located where they were likely to experience large waves in one season.... |
| Tipo: Text |
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| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/00117/22841/20651.pdf |
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| Registros recuperados: 25 | |
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