The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Franck Schoefs - One of the best experts on this subject based on the ideXlab platform.
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Stochastic Modeling of Forces on Jacket-Type Offshore Structures Colonized by Marine Growth
Journal of Marine Science and Engineering, 2019Co-Authors: Hamed Ameryoun, Franck Schoefs, Laurent Barillé, Yoann ThomasAbstract:The present paper deals with the stochastic modeling of bio-colonization for the computation of stochastic hydrodynamic loading on jacket-type offshore structures. It relies on a multidisciplinary study gathering biological and physical research fields that accounts for uncertainties at all the levels. Indeed, bio-colonization of offshore structures is a complex phenomenon with two major but distinct domains: (i) Marine biology, whose processes are modeled with biomathematics methods, and (ii) hydrodynamic processes. This paper aims to connect these two domains. It proposes a stochastic model for the Marine organism’s Growth and then continues with transfers for the assessment of drag coefficient and forces probability density functions that account for Marine Growth evolution. A case study relies on the characteristics (Growth and shape) of the blue mussel (Mytilus edulis) in the northeastern Atlantic.
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Stochastic Modeling of Forces on Jacket-Type Offshore Structures Colonized by Marine Growth
2019Co-Authors: Hamed Ameryoun, Franck Schoefs, Laurent Barillé, Yoann ThomasAbstract:The present paper deals with the stochastic modeling of bio-colonization for the computation of stochastic hydrodynamic loading on jacket-type offshore structures. It relies on a multidisciplinary study gathering biological and physical research fields that accounts of uncertainties at all the levels. Indeed, bio-colonization of offshore structures is a complex phenomenon with two major but distinct domains (i) Marine biology whose processes are modeled with biomathematics methods and (ii) hydrodynamic processes. This paper aims to connect these two domains. It proposes a stochastic model for the Marine organism’s Growth and then continues with transfers for assessment of drag coefficient and forces probability density functions that accounts for Marine Growth evolution. A case study relies on the characteristics (Growth and shape) of the blue mussel (Mytilus edulis) in northeastern Atlantic.
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A Comparison of Image Based 3D Recovery Methods for Underwater Inspections
2014Co-Authors: Michael O'byrne, Franck Schoefs, Vikram Pakrashi, Bidisha GhoshAbstract:Offshore structures can be subjected to millions of variable amplitude load cycles during their service life which is the primary cause of structural deterioration. Such fatigue loading is exacerbated by Marine Growth colonization which changes the surface roughness characteristics and increases the diameter of structural members. Having an accurate knowledge of these parameters is essential for analyzing the increased hydrodynamic forces acting on the structure. This paper addresses the issue of acquiring shape information by comparing two popular classes of image based shape recovery techniques, stereo photography and Structure from Motion (SfM). Stereo photography utilises a dual camera set-up to simultaneously photograph an object of interest from slightly different viewpoints, whilst SfM methods generally involve a single camera moving in a static scene. In this paper, these techniques are performed on a controlled shape in an underwater setting, as well as synthetic data which allows for an irregular shape typical of Marine Growth to be tested whilst still having knowledge of the exact geometrical shape. The results reveal that the self-calibrated stereo approach fared well at getting an appropriately scaled full metric reconstruction, whilst the SfM approach was more susceptible to breaking down.
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Probabilistic Modeling of Roughness Effects Caused by Bio-Colonization on Hydrodynamic Coefficients: A Sensitivity Study for Jacket-Platforms in Gulf of Guinea
Volume 1: Offshore Technology, 2013Co-Authors: Hamed Ameryoun, Franck SchoefsAbstract:Nowadays, challenge for requalification of existing offshore platforms through the reassessment process leads to consider the importance of updating new information (e.g. environmental data, new regulations, etc.). Regarding to this information and depending on offshore fields, data of Marine Growth colonization is shown to have a dominant effect. This is a real challenge in the Gulf of Guinea that this study focuses on. Marine Growth is known to cause adverse effects on the performance of offshore structures. Its presence can change the roughness and the diameter of structural members and hence change the level of hydrodynamic coefficients. Moreover, modifying the added mass can change the natural period and hence dynamic responses of structures. Even platforms with the best protection schemes against Marine organisms will after few weeks at least few months start to be covered by various types of Marine Growth. Generally, it was also recognized that the most important source of loading exerted on offshore structures comes from hydrodynamic actions which are influenced by hydrodynamic coefficient values. The colonization process is very complex and results are in a large diversity of Marine Growth type (animal, vegetal — hard, soft) and species. This study therefore proposes a stochastic modeling of Marine Growth and the roughness of hard species based on Response Surface Methodology. A geometrical description of nth order of Stokes model, formed by a random linear combination of deterministic vectors is employed. Finally, the complexity level of roughness modeling is analyzed and the results are discussed.
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Probabilistic Modeling of the Bio-Colonization Effects on Hydrodynamic Forces With Several Combinations of Sea-State Condition: A Study on Jacket-Platforms in the Gulf of Guinea
Volume 1: Offshore Technology, 2013Co-Authors: Franck Schoefs, Hamed AmeryounAbstract:During the stage of designing or re-assessment of a jacket-type offshore structure, one of the most important phases is the re-evaluation of environmental loads, which are exerted by the waves, the wind and the currents, and updating the new data (e.g. meteocean, new regulation, structural damaging etc.). The former is mainly caused by the randomness or uncertainty nature of the Marine environment as well as the presence of Marine Growth that makes the modeling of environmental loading more complicated. The general species of Marine Growth may be divided into two main categories: vegetable (e.g. algae) and animal (e.g. mussel, anemones, and corals). Indeed, the structures can be covered by many Marine organisms quickly (in the first weeks). The influence of bio-colonization on an offshore structure can be measured at several levels: obstruct or prohibits a visual inspection of the subjacent support, cost of procedures of cleaning for oil industries and increasing the hydrodynamic forces on the structure. Considering the latter, loading change due screen effect and added mass are shown to be the most relevant. This study aims to provide a probabilistic modeling of Marine Growth colonization in the Gulf of Guinea. A physical matrix response surface is used in view to provide a probabilistic modeling of the environmental loading on Jacket type offshore structures for quasi-static behavior in the presence of Marine Growth. The paper focuses on uncertainty and sensitivity studies respecting to the effects of wave, wind-sea and currents.Copyright © 2013 by ASME
Mahdi Hassan - One of the best experts on this subject based on the ideXlab platform.
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A Deformable Spiral Based Algorithm to Smooth Coverage Path Planning for Marine Growth Removal
2018 IEEE RSJ International Conference on Intelligent Robots and Systems (IROS), 2018Co-Authors: Mahdi HassanAbstract:Marine Growths that flourish on the surfaces of underwater structures, such as bridge pylons, make the inspection and maintenance of these structures challenging. A robotic solution, using an Intervention Autonomous Underwater Vehicle (I-AUV), is developed for removing Marine Growth. This paper presents a Deformable Spiral Coverage Path Planning (DSCPP) algorithm for Marine Growth removal. DSCPP generates smooth paths to prevent damage to the surfaces of the structures and to avoid frequent or aggressive decelerations and accelerations due to sharp turns. DSCPP generates a spiral path within a circle and analytically maps the path to a minimum bounding rectangle which encompasses an area of a surface with Marine Growth. It aims to achieve a spiral path with minimal length while preventing missed areas of coverage. Several case studies are presented to validate the algorithm. Comparison results show that DSCPP outperforms the popular boustrophedon-based coverage approach when considering the requirements for the application under consideration.
Hamed Ameryoun - One of the best experts on this subject based on the ideXlab platform.
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Stochastic Modeling of Forces on Jacket-Type Offshore Structures Colonized by Marine Growth
Journal of Marine Science and Engineering, 2019Co-Authors: Hamed Ameryoun, Franck Schoefs, Laurent Barillé, Yoann ThomasAbstract:The present paper deals with the stochastic modeling of bio-colonization for the computation of stochastic hydrodynamic loading on jacket-type offshore structures. It relies on a multidisciplinary study gathering biological and physical research fields that accounts for uncertainties at all the levels. Indeed, bio-colonization of offshore structures is a complex phenomenon with two major but distinct domains: (i) Marine biology, whose processes are modeled with biomathematics methods, and (ii) hydrodynamic processes. This paper aims to connect these two domains. It proposes a stochastic model for the Marine organism’s Growth and then continues with transfers for the assessment of drag coefficient and forces probability density functions that account for Marine Growth evolution. A case study relies on the characteristics (Growth and shape) of the blue mussel (Mytilus edulis) in the northeastern Atlantic.
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Stochastic Modeling of Forces on Jacket-Type Offshore Structures Colonized by Marine Growth
2019Co-Authors: Hamed Ameryoun, Franck Schoefs, Laurent Barillé, Yoann ThomasAbstract:The present paper deals with the stochastic modeling of bio-colonization for the computation of stochastic hydrodynamic loading on jacket-type offshore structures. It relies on a multidisciplinary study gathering biological and physical research fields that accounts of uncertainties at all the levels. Indeed, bio-colonization of offshore structures is a complex phenomenon with two major but distinct domains (i) Marine biology whose processes are modeled with biomathematics methods and (ii) hydrodynamic processes. This paper aims to connect these two domains. It proposes a stochastic model for the Marine organism’s Growth and then continues with transfers for assessment of drag coefficient and forces probability density functions that accounts for Marine Growth evolution. A case study relies on the characteristics (Growth and shape) of the blue mussel (Mytilus edulis) in northeastern Atlantic.
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Probabilistic Modeling of Roughness Effects Caused by Bio-Colonization on Hydrodynamic Coefficients: A Sensitivity Study for Jacket-Platforms in Gulf of Guinea
Volume 1: Offshore Technology, 2013Co-Authors: Hamed Ameryoun, Franck SchoefsAbstract:Nowadays, challenge for requalification of existing offshore platforms through the reassessment process leads to consider the importance of updating new information (e.g. environmental data, new regulations, etc.). Regarding to this information and depending on offshore fields, data of Marine Growth colonization is shown to have a dominant effect. This is a real challenge in the Gulf of Guinea that this study focuses on. Marine Growth is known to cause adverse effects on the performance of offshore structures. Its presence can change the roughness and the diameter of structural members and hence change the level of hydrodynamic coefficients. Moreover, modifying the added mass can change the natural period and hence dynamic responses of structures. Even platforms with the best protection schemes against Marine organisms will after few weeks at least few months start to be covered by various types of Marine Growth. Generally, it was also recognized that the most important source of loading exerted on offshore structures comes from hydrodynamic actions which are influenced by hydrodynamic coefficient values. The colonization process is very complex and results are in a large diversity of Marine Growth type (animal, vegetal — hard, soft) and species. This study therefore proposes a stochastic modeling of Marine Growth and the roughness of hard species based on Response Surface Methodology. A geometrical description of nth order of Stokes model, formed by a random linear combination of deterministic vectors is employed. Finally, the complexity level of roughness modeling is analyzed and the results are discussed.
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Probabilistic Modeling of the Bio-Colonization Effects on Hydrodynamic Forces With Several Combinations of Sea-State Condition: A Study on Jacket-Platforms in the Gulf of Guinea
Volume 1: Offshore Technology, 2013Co-Authors: Franck Schoefs, Hamed AmeryounAbstract:During the stage of designing or re-assessment of a jacket-type offshore structure, one of the most important phases is the re-evaluation of environmental loads, which are exerted by the waves, the wind and the currents, and updating the new data (e.g. meteocean, new regulation, structural damaging etc.). The former is mainly caused by the randomness or uncertainty nature of the Marine environment as well as the presence of Marine Growth that makes the modeling of environmental loading more complicated. The general species of Marine Growth may be divided into two main categories: vegetable (e.g. algae) and animal (e.g. mussel, anemones, and corals). Indeed, the structures can be covered by many Marine organisms quickly (in the first weeks). The influence of bio-colonization on an offshore structure can be measured at several levels: obstruct or prohibits a visual inspection of the subjacent support, cost of procedures of cleaning for oil industries and increasing the hydrodynamic forces on the structure. Considering the latter, loading change due screen effect and added mass are shown to be the most relevant. This study aims to provide a probabilistic modeling of Marine Growth colonization in the Gulf of Guinea. A physical matrix response surface is used in view to provide a probabilistic modeling of the environmental loading on Jacket type offshore structures for quasi-static behavior in the presence of Marine Growth. The paper focuses on uncertainty and sensitivity studies respecting to the effects of wave, wind-sea and currents.Copyright © 2013 by ASME
Yoann Thomas - One of the best experts on this subject based on the ideXlab platform.
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Stochastic Modeling of Forces on Jacket-Type Offshore Structures Colonized by Marine Growth
Journal of Marine Science and Engineering, 2019Co-Authors: Hamed Ameryoun, Franck Schoefs, Laurent Barillé, Yoann ThomasAbstract:The present paper deals with the stochastic modeling of bio-colonization for the computation of stochastic hydrodynamic loading on jacket-type offshore structures. It relies on a multidisciplinary study gathering biological and physical research fields that accounts for uncertainties at all the levels. Indeed, bio-colonization of offshore structures is a complex phenomenon with two major but distinct domains: (i) Marine biology, whose processes are modeled with biomathematics methods, and (ii) hydrodynamic processes. This paper aims to connect these two domains. It proposes a stochastic model for the Marine organism’s Growth and then continues with transfers for the assessment of drag coefficient and forces probability density functions that account for Marine Growth evolution. A case study relies on the characteristics (Growth and shape) of the blue mussel (Mytilus edulis) in the northeastern Atlantic.
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Stochastic Modeling of Forces on Jacket-Type Offshore Structures Colonized by Marine Growth
2019Co-Authors: Hamed Ameryoun, Franck Schoefs, Laurent Barillé, Yoann ThomasAbstract:The present paper deals with the stochastic modeling of bio-colonization for the computation of stochastic hydrodynamic loading on jacket-type offshore structures. It relies on a multidisciplinary study gathering biological and physical research fields that accounts of uncertainties at all the levels. Indeed, bio-colonization of offshore structures is a complex phenomenon with two major but distinct domains (i) Marine biology whose processes are modeled with biomathematics methods and (ii) hydrodynamic processes. This paper aims to connect these two domains. It proposes a stochastic model for the Marine organism’s Growth and then continues with transfers for assessment of drag coefficient and forces probability density functions that accounts for Marine Growth evolution. A case study relies on the characteristics (Growth and shape) of the blue mussel (Mytilus edulis) in northeastern Atlantic.
Bengt Finstad - One of the best experts on this subject based on the ideXlab platform.
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Evidence for the linkage of survival of anadromous Arctic char and brown trout during winter to Marine Growth during the previous summer
Canadian Journal of Fisheries and Aquatic Sciences, 2018Co-Authors: Arne Jensen, Bengt Finstad, Peder FiskeAbstract:Data from a 25-year study of anadromous Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) in the River Halselva provided evidence that survival during winter was linked to Marine Growth during the previous summer. The study supported the “critical size and critical period” hypothesis, which postulates that regulation of the abundance of adult salmonids occurs in two major phases. The first phase is Marine mortality that occurs shortly after smolts enter salt water, and the second is during the following winter, when individuals that have not attained a critical size are unable to meet minimum metabolic requirements and die. In the present study, Growth during summer appeared to be more important to winter survival than body size. Size-selective mortality occurred both at sea during summer and in fresh water during winter and was more evident for first-time migrants than repeat migrants.
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Relationship between Marine Growth and sea survival of two anadromous salmonid fish species
Canadian Journal of Fisheries and Aquatic Sciences, 2018Co-Authors: Arne Jensen, Bengt Finstad, Peder Fiske, Torbjørn Forseth, Audun H. Rikardsen, Ola UgedalAbstract:This study found empirical evidence supporting the “Growth–survival” paradigm in the Marine phase of Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta). The paradigm postulates that larger or faster-growing individuals are more likely to survive than smaller or slower-growing conspecifics. The study employed long-term (25 year) capture data from a trap in the River Halselva in Norway during annual migration between Marine and freshwater environments. Similar results were found for both species. Growth during the sea sojourn and return rates were positively correlated, linking increased survival with Growth. Specific Growth rate, survival, and duration of the sea sojourn of first-time migrants were correlated, suggesting that common environmental conditions at sea influence annual fish productivity. Freshwater and sea temperatures affected migration timing, whereas annual variation in Marine Growth and survival did not correlate with temperatures. This suggests that other factors such as varia...
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impact of early salmon louse lepeophtheirus salmonis infestation and differences in survival and Marine Growth of sea ranched atlantic salmon salmo salar l smolts 1997 2009
Journal of Fish Diseases, 2013Co-Authors: Ove Skilbrei, Bengt Finstad, Kurt Urdal, Gunnar O Bakke, Frode Kroglund, Rita StrandAbstract:The impact of salmon lice on the survival of migrating Atlantic salmon smolts was studied by comparing the adult returns of sea-ranched smolts treated for sea lice using emamectin benzoate or substance EX with untreated control groups in the River Dale in western Norway. A total of 143 500 smolts were released in 35 release groups in freshwater from 1997 to 2009 and in the fjord system from 2007 to 2009. The adult recaptures declined gradually with release year and reached minimum levels in 2007. This development corresponded with poor Marine Growth and increased age at maturity of ranched salmon and in three monitored salmon populations and indicated unfavourable conditions in the Norwegian Sea. The recapture rate of treated smolts was significantly higher than the controls in three of the releases performed: the only release in 1997, one of three in 2002 and the only group released in sea water in 2007. The effect of treating the smolts against salmon lice was smaller than the variability in return rates between release groups, and much smaller that variability between release years, but its overall contribution was still significant (P < 0.05) and equivalent to an odds ratio of the probability of being recaptured of 1.17 in favour of the treated smolts. Control fish also tended to be smaller as grilse (P = 0.057), possibly due to a sublethal effect of salmon lice.