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| Registros recuperados: 25 | |
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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... |
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| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00116/22715/20457.pdf |
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| Prevosto, Marc; Maisondieu, Christophe; Forristall, George Z.; Jeans, Gus; Harrington-missin, Liam; Watson, Andrew; Harte, Gavin; Dooley, Patrick; Frelin, Cyril; Herry, Christelle; Muller, Héloïse; Casitas, Sophie. |
| The design of catenary risers, riser towers, and export lines is key to oil and gas production in the deep ocean. Winds, waves, surface currents and current profiles are essential inputs to the design of these riser systems. With regards to current loading, the variety and abundance of current profiles can make it difficult to determine which profiles are most appropriate for determining extreme and fatigue loading on risers. The choices become increasingly difficult on the frontier of deepwater oil and gas developments as risers are increasingly being required to successfully operate in harsher environments and deeper water. However, longer and more detailed current measurements from in-situ deployments continue to become available. Two or three year... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00499/61056/64504.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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| 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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| 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. |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00250/36152/34706.pdf |
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| Filipot, Jean-francois; Prevosto, Marc; Maisondieu, Christophe; Le Boulluec, Marc; Thomson, Jim. |
| This work presents the analysis of wave and turbulence measurements collected at a tidal energy site. A new method is introduced to produce more consistent and rigorous estimations of the velocity fluctuations power spectral densities. An analytical function is further proposed to fit the observed spectra and could be input to the numerical models predicting power production and structural loading on tidal turbines. Another new approach is developed to correct for the effect of the Doppler noise on the high frequencies power spectral densities. The analysis of velocity time series combining wave and turbulent contributions demonstrates that the turbulent motions are coherent throughout the water column, rendering the wave coherence-based methods not... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00254/36537/35074.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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| 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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| 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. |
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| Ano: 1986 |
URL: https://archimer.ifremer.fr/doc/00480/59128/61756.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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| 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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| 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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| 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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| Lindgren, Georg; Prevosto, Marc. |
| Water particle orbits are key elements in the Lagrange wave formulation. The stochastic Miche implementation of the Lagrange model is a linear Gaussian two-dimensional or three-dimensional space-time model which exhibits typical nonlinear wave characteristics when transformed to Eulerian coordinates. This paper investigates the statistical relation between the degree of front-back asymmetry of individual waves and the orbit orientation for the particle located at the wave maximum at the point of observation. It is shown that, in the Lagrangian model with statistical front-back symmetry, for individual waves there is a clear connexion between the degree of individual wave asymmetry and the orientation of the randomly deformed elliptic orbit: a steep front... |
| Tipo: Text |
Palavras-chave: Computational methods; Surface gravity waves; Ocean processes. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00658/76986/78255.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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| Registros recuperados: 25 | |
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