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Raul Primicerio - One of the best experts on this subject based on the ideXlab platform.
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Impact Scenario for the invasive red king crab paralithodes camtschaticus tilesius 1815 reptantia lithodidae on norwegian native epibenthic prey
Hydrobiologia, 2007Co-Authors: Lis Lindal Jørgensen, Raul PrimicerioAbstract:Large invasive predators like the king crab, Paralithodes camtschaticus, deserve particular attention due to their potential for catastrophic ecological Impact on recipient communities. Conspicuous, epibenthic prey species, such as the slow growing commercial scallop Chlamys islandica, are particularly exposed to the risk of local extinction. A research program integrating experiments and field monitoring is attempting to predict and track the Impact of invasive king crab on scallop beds and associated fauna along the north Norwegian coast. The claw gape of the crab shows no limitations in handling the flat-bodied scallop. However, the potential Impact of the crab on scallop may depend on the availability of other calcified prey associated with scallop beds, such as the sea star, sea urchin, and blue mussel, all species recorded in the diet of P. camtschaticus. To address this issue, a laboratory experiment on foraging behaviour of P. camtschaticus was conducted. The experimental results show that all size classes of red king crab prefer scallops, but small juveniles and medium sized crabs demonstrate active selection for starfish (Asterias rubens) that equals or surpasses the electivity of the large crab. The selection of sea urchin (Strongylocentrotus droebachiensis) and blue mussel (Mytilus edulis) is slightly positive or neutral for the three crab size classes. These results suggest that scallop beds with a rich associated fauna are less vulnerable to red king crabs predation and possibly more resilient than beds with few associated species. Also, crab size distribution is likely relevant for invasion Impact, with increasing abundance of small and medium sized crabs being detrimental for alternative calcified prey associated with scallop beds. Successive stages of crab invasion will see an acceleration of scallop mortality rates associated with (i) decreasing availability of alternative prey, due to protracted predation pressure intensified by recruitment of juvenile crabs, and (ii) increased number of large crabs. Estimates of crab density and intake rates suggest that the accelerated loss rates will eventually endanger scallop beds persistence.
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Impact Scenario for the invasive red king crab paralithodes camtschaticus tilesius 1815 reptantia lithodidae on norwegian native epibenthic prey
Hydrobiologia, 2007Co-Authors: Lis Lindal Jørgensen, Raul PrimicerioAbstract:Large invasive predators like the king crab, Paralithodes camtschaticus, deserve particular attention due to their potential for catastrophic ecological Impact on recipient communities. Conspicuous, epibenthic prey species, such as the slow growing commercial scallop Chlamys islandica, are particularly exposed to the risk of local extinction. A research program integrating experiments and field monitoring is attempting to predict and track the Impact of invasive king crab on scallop beds and associated fauna along the north Norwegian coast. The claw gape of the crab shows no limitations in handling the flat-bodied scallop. However, the potential Impact of the crab on scallop may depend on the availability of other calcified prey associated with scallop beds, such as the sea star, sea urchin, and blue mussel, all species recorded in the diet of P. camtschaticus. To address this issue, a laboratory experiment on foraging behaviour of P. camtschaticus was conducted. The experimental results show that all size classes of red king crab prefer scallops, but small juveniles and medium sized crabs demonstrate active selection for starfish (Asterias rubens) that equals or surpasses the electivity of the large crab. The selection of sea urchin (Strongylocentrotus droebachiensis) and blue mussel (Mytilus edulis) is slightly positive or neutral for the three crab size classes. These results suggest that scallop beds with a rich associated fauna are less vulnerable to red king crabs predation and possibly more resilient than beds with few associated species. Also, crab size distribution is likely relevant for invasion Impact, with increasing abundance of small and medium sized crabs being detrimental for alternative calcified prey associated with scallop beds. Successive stages of crab invasion will see an acceleration of scallop mortality rates associated with (i) decreasing availability of alternative prey, due to protracted predation pressure intensified by recruitment of juvenile crabs, and (ii) increased number of large crabs. Estimates of crab density and intake rates suggest that the accelerated loss rates will eventually endanger scallop beds persistence.
Pentti Kujala - One of the best experts on this subject based on the ideXlab platform.
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Impact Scenario models for probabilistic risk based design for ship ship collision
Marine Structures, 2013Co-Authors: Kaarle Stahlberg, Floris Goerlandt, Soren Ehlers, Pentti KujalaAbstract:Abstract A number of authors have proposed probabilistic risk based ship design for ship–ship collision, conditional to the local trading area of a vessel. The probability of collision and consequences are determined based on the traffic conditions in which a vessel is expected to operate. This paper investigates the adequacy of currently available models for Impact Scenarios, i.e. models linking the traffic conditions to the conditions at the moment of collision. An exploratory statistical model is presented to establish such a link. A probabilistic risk based design case study is performed for a fleet of RoPax vessels trading on a specified route in the Gulf of Finland. The available Impact Scenario models from the literature are compared with the developed probabilistic evasive maneuvering model. The results show that the Impact Scenario models have a very significant influence to the calculated hull breach probabilities. No well-justified Impact Scenario models are presently available and also the presented probabilistic evasive maneuvering model is burdened with uncertainty. Hence, to move toward a probabilistic risk based ship design paradigm for ship–ship collision in a local trading area, more focus and research is needed to establish a credible link.
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Impact Scenario models for probabilistic risk-based design for ship–ship collision
Marine Structures, 2013Co-Authors: Kaarle Stahlberg, Floris Goerlandt, Soren Ehlers, Pentti KujalaAbstract:Abstract A number of authors have proposed probabilistic risk based ship design for ship–ship collision, conditional to the local trading area of a vessel. The probability of collision and consequences are determined based on the traffic conditions in which a vessel is expected to operate. This paper investigates the adequacy of currently available models for Impact Scenarios, i.e. models linking the traffic conditions to the conditions at the moment of collision. An exploratory statistical model is presented to establish such a link. A probabilistic risk based design case study is performed for a fleet of RoPax vessels trading on a specified route in the Gulf of Finland. The available Impact Scenario models from the literature are compared with the developed probabilistic evasive maneuvering model. The results show that the Impact Scenario models have a very significant influence to the calculated hull breach probabilities. No well-justified Impact Scenario models are presently available and also the presented probabilistic evasive maneuvering model is burdened with uncertainty. Hence, to move toward a probabilistic risk based ship design paradigm for ship–ship collision in a local trading area, more focus and research is needed to establish a credible link.
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influence of Impact Scenario models on collision risk analysis
Ocean Engineering, 2012Co-Authors: Floris Goerlandt, Kaarle Stahlberg, Pentti KujalaAbstract:Abstract An important element in assessing the consequences in a tanker collision is the probability of breaching an oil cargo tank. It is well recognized that the dynamic parameters at the moment of Impact significantly affect the deformation energy. Assumptions regarding dynamic parameters at the moment of Impact are nevertheless little discussed in context of collision risk analysis. The available Impact Scenario models are analyzed using a system risk approach. Comparison of Impact Scenario models from literature is performed with a risk analysis algorithm emphasizing on oil tanker collisions. Monte Carlo simulation is applied in the risk analysis algorithm for each Impact Scenario model. Only the Impact Scenario module is changed while other modules of the algorithm (encounter Scenario generation, determination of deformation energy and structural hull capacity) are kept the same. Analysis reveals important differences in results of risk analysis when performed with different assumptions for the Impact Scenario. Moreover, in the discussion inherent conceptual limitations of the Impact Scenario models in the system risk framework are revealed. It is concluded that using more accurate collision energy and/or structural capacity models for purposes of maritime traffic risk analysis is currently not worthwhile, as the uncertainty regarding Impact Scenario is overwhelming.
M. Reza Emami Azadi - One of the best experts on this subject based on the ideXlab platform.
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The Influence of Different Scenarios of Supply Ship Collision on the Dynamic Response of a North-Sea Jacket-Pile-Soil System
Journal of Offshore Mechanics and Arctic Engineering, 2010Co-Authors: M. Reza Emami AzadiAbstract:In the present study, the influence of various Scenarios of supply ship collisions, namely, bow, stern, and also broad-side Impacts on a jacket-pile-soil system, is investigated. In the previous study of ship Impact on an eight-leg North-Sea jacket platform by Amdahl and other authors, the effect of jacket-pile-soil interaction was not considered. The collision points on the jacket structure are also taken as joints and midspan of leg, horizontal and vertical braces, namely, hard and soft Impact points. The speed and the weight of the colliding vessel are also varied for typical supply vessels. Several supply ship collision analyses are carried out for bow, stern and broad-side Impact Scenarios on an eight-leg North-Sea jacket platform. It is observed that by taking into account the jacket-pile-soil interaction effects, particularly in softer clayey soils, the amplitude of displacement response after the supply ship Impact at the deck level is increased due to yield in the upper soil layers. Contrary to this finding, less linear dynamic effects can be seen in the studied jacket-pile-soil system subjected to the supply ship Impact. It can also be concluded that for a soft Impact Scenario, the dynamic effects in the global response of the platform located in the mainly over-consolidated (OC) clayey soil may be much less than those for a hard Impact Scenario on the same platform. For instance, for a brace Impact at its midspan, a less significant dynamic effect has been observed than for a leg Impact. The duration of Impact in such cases is shown to play an important role in determining the dynamic influence of the platform response. The relative energy absorption of the platform is shown to be more for broad-side loading. It is shown that the global response of the jacket platform during the collision with a supply vessel might depend largely on the Scenario of the Impact and, to some extent, on the pile-soil behavior. It is found that for the bow and stern Impact Scenarios, the energy contribution of the local member dent or buckling might be more significant than that for the broad-side loading for which the global frame energy contribution and the overall inertia effect of the platform might be a dominant factor.
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The Influence of Different Scenarios of Supply Ship Collision on the Dynamic Response of a North-Sea Jacket-Pile-Soil System
Volume 2: Structures Safety and Reliability; Petroleum Technology Symposium, 2007Co-Authors: M. Reza Emami AzadiAbstract:In the present study, the influence of various Scenarios of supply ship collisions, namely, bow, stern and also broad-side Impacts on a jacket-pile-soil system is investigated. In the previous study of ship Impact on an 8-leg North-Sea Jacket Platform by Amdahl et al. [2] and also other authors, the effect of jacket-pile-soil interaction was not considered. The collision points on the jacket structure are also taken as joints and mid-span of leg, horizontal and vertical braces, namely, hard and soft Impact points. The speed and the weight of the colliding vessel are also varied for typical supply vessels. Several supply ship collision analyses are carried out for bow, stern and broad-side Impact Scenarios on an 8-leg North-sea Jacket platform It is observed that by taking into account the jacket-pile-soil interaction effects, in particular in softer clay soils the amplitude of displacement response after supply ship Impact at the deck level is increased due to yield in the upper soil layers. Contrary to this finding, less linear dynamic effects can be seen in the studied jacket-pile-soil system subjected to the supply ship Impact. It can also be concluded that for soft Impact Scenario, the dynamic effects in the global response of the platform located in the mainly OC clayey soil may be much less than those for hard Impact Scenario on the same platform. For instance, for a brace Impact at its mid-span, a less significant dynamic effect has been observed than for a leg Impact. The duration of Impact in such cases is shown to play an important role in determining the dynamic influence of the platform response. The relative energy absorption of the platform is shown to be more for broad-side loading. It is shown that the global response of the jacket platform during the collision with a supply vessel might depend largely on the Scenario of the Impact and to some extent on the pile-soil behavior. It is found that for the bow and stern Impact Scenarios, the energy contribution of the local member dent or buckling might be more significant than for the broad-side loading for which the global frame energy contribution and the overall inertia effect of the platform might be a dominant factor.Copyright © 2007 by ASME
Lis Lindal Jørgensen - One of the best experts on this subject based on the ideXlab platform.
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Impact Scenario for the invasive red king crab paralithodes camtschaticus tilesius 1815 reptantia lithodidae on norwegian native epibenthic prey
Hydrobiologia, 2007Co-Authors: Lis Lindal Jørgensen, Raul PrimicerioAbstract:Large invasive predators like the king crab, Paralithodes camtschaticus, deserve particular attention due to their potential for catastrophic ecological Impact on recipient communities. Conspicuous, epibenthic prey species, such as the slow growing commercial scallop Chlamys islandica, are particularly exposed to the risk of local extinction. A research program integrating experiments and field monitoring is attempting to predict and track the Impact of invasive king crab on scallop beds and associated fauna along the north Norwegian coast. The claw gape of the crab shows no limitations in handling the flat-bodied scallop. However, the potential Impact of the crab on scallop may depend on the availability of other calcified prey associated with scallop beds, such as the sea star, sea urchin, and blue mussel, all species recorded in the diet of P. camtschaticus. To address this issue, a laboratory experiment on foraging behaviour of P. camtschaticus was conducted. The experimental results show that all size classes of red king crab prefer scallops, but small juveniles and medium sized crabs demonstrate active selection for starfish (Asterias rubens) that equals or surpasses the electivity of the large crab. The selection of sea urchin (Strongylocentrotus droebachiensis) and blue mussel (Mytilus edulis) is slightly positive or neutral for the three crab size classes. These results suggest that scallop beds with a rich associated fauna are less vulnerable to red king crabs predation and possibly more resilient than beds with few associated species. Also, crab size distribution is likely relevant for invasion Impact, with increasing abundance of small and medium sized crabs being detrimental for alternative calcified prey associated with scallop beds. Successive stages of crab invasion will see an acceleration of scallop mortality rates associated with (i) decreasing availability of alternative prey, due to protracted predation pressure intensified by recruitment of juvenile crabs, and (ii) increased number of large crabs. Estimates of crab density and intake rates suggest that the accelerated loss rates will eventually endanger scallop beds persistence.
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Impact Scenario for the invasive red king crab paralithodes camtschaticus tilesius 1815 reptantia lithodidae on norwegian native epibenthic prey
Hydrobiologia, 2007Co-Authors: Lis Lindal Jørgensen, Raul PrimicerioAbstract:Large invasive predators like the king crab, Paralithodes camtschaticus, deserve particular attention due to their potential for catastrophic ecological Impact on recipient communities. Conspicuous, epibenthic prey species, such as the slow growing commercial scallop Chlamys islandica, are particularly exposed to the risk of local extinction. A research program integrating experiments and field monitoring is attempting to predict and track the Impact of invasive king crab on scallop beds and associated fauna along the north Norwegian coast. The claw gape of the crab shows no limitations in handling the flat-bodied scallop. However, the potential Impact of the crab on scallop may depend on the availability of other calcified prey associated with scallop beds, such as the sea star, sea urchin, and blue mussel, all species recorded in the diet of P. camtschaticus. To address this issue, a laboratory experiment on foraging behaviour of P. camtschaticus was conducted. The experimental results show that all size classes of red king crab prefer scallops, but small juveniles and medium sized crabs demonstrate active selection for starfish (Asterias rubens) that equals or surpasses the electivity of the large crab. The selection of sea urchin (Strongylocentrotus droebachiensis) and blue mussel (Mytilus edulis) is slightly positive or neutral for the three crab size classes. These results suggest that scallop beds with a rich associated fauna are less vulnerable to red king crabs predation and possibly more resilient than beds with few associated species. Also, crab size distribution is likely relevant for invasion Impact, with increasing abundance of small and medium sized crabs being detrimental for alternative calcified prey associated with scallop beds. Successive stages of crab invasion will see an acceleration of scallop mortality rates associated with (i) decreasing availability of alternative prey, due to protracted predation pressure intensified by recruitment of juvenile crabs, and (ii) increased number of large crabs. Estimates of crab density and intake rates suggest that the accelerated loss rates will eventually endanger scallop beds persistence.
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Impact Scenario for an introduced decapod on Arctic epibenthic communities.
Biological Invasions, 2005Co-Authors: Lis Lindal JørgensenAbstract:The intentional introduction of a species for the enhancement of stock or establishment of new fisheries, often has unforeseen effects. The red king crabs, Paralithodes camtschaticus, which was introduced into the Barents Sea by Russian scientists, has established a self-sustaining population that has expanded into Norwegian waters. As top benthic predators, the introduced red king crabs may have possible effects upon native epifaunal scallop (Chlamys islandica) communities. These benthic communities may be a source of prey species in late spring, when the red king crabs feed most intensively. Foraging rates (consumption, killing or severely damaging) of red king crab on native prey organisms were measured by factorial manipulation of crab density (0.5, 1.5 and 3 per m 2), size classes (immature, small mature, and large mature crabs), and by evaluating prey consumption after 48 h, in order to extrapolate a Scenario of the likely Impacts. Foraging rates of the red king crab on scallops ranged between 150 and 335 g per m2 within 48 h. These rates did not change when crab density was altered, though an increased amount of crushed scallops left uneaten at the tank floor, were correlated with high density of small mature crabs. Foraging rate changed significantly with crab size. Consequently, the susceptibility of native, shallow water epibenthic communities to red king crab predation in the early life history stages, and during the post-mating/molting spring period, must be considered significant when foraging rates are contrasted with natural scallop biomass between 400 and 1200 g scallops per m2.
Kaarle Stahlberg - One of the best experts on this subject based on the ideXlab platform.
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Impact Scenario models for probabilistic risk based design for ship ship collision
Marine Structures, 2013Co-Authors: Kaarle Stahlberg, Floris Goerlandt, Soren Ehlers, Pentti KujalaAbstract:Abstract A number of authors have proposed probabilistic risk based ship design for ship–ship collision, conditional to the local trading area of a vessel. The probability of collision and consequences are determined based on the traffic conditions in which a vessel is expected to operate. This paper investigates the adequacy of currently available models for Impact Scenarios, i.e. models linking the traffic conditions to the conditions at the moment of collision. An exploratory statistical model is presented to establish such a link. A probabilistic risk based design case study is performed for a fleet of RoPax vessels trading on a specified route in the Gulf of Finland. The available Impact Scenario models from the literature are compared with the developed probabilistic evasive maneuvering model. The results show that the Impact Scenario models have a very significant influence to the calculated hull breach probabilities. No well-justified Impact Scenario models are presently available and also the presented probabilistic evasive maneuvering model is burdened with uncertainty. Hence, to move toward a probabilistic risk based ship design paradigm for ship–ship collision in a local trading area, more focus and research is needed to establish a credible link.
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Impact Scenario models for probabilistic risk-based design for ship–ship collision
Marine Structures, 2013Co-Authors: Kaarle Stahlberg, Floris Goerlandt, Soren Ehlers, Pentti KujalaAbstract:Abstract A number of authors have proposed probabilistic risk based ship design for ship–ship collision, conditional to the local trading area of a vessel. The probability of collision and consequences are determined based on the traffic conditions in which a vessel is expected to operate. This paper investigates the adequacy of currently available models for Impact Scenarios, i.e. models linking the traffic conditions to the conditions at the moment of collision. An exploratory statistical model is presented to establish such a link. A probabilistic risk based design case study is performed for a fleet of RoPax vessels trading on a specified route in the Gulf of Finland. The available Impact Scenario models from the literature are compared with the developed probabilistic evasive maneuvering model. The results show that the Impact Scenario models have a very significant influence to the calculated hull breach probabilities. No well-justified Impact Scenario models are presently available and also the presented probabilistic evasive maneuvering model is burdened with uncertainty. Hence, to move toward a probabilistic risk based ship design paradigm for ship–ship collision in a local trading area, more focus and research is needed to establish a credible link.
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influence of Impact Scenario models on collision risk analysis
Ocean Engineering, 2012Co-Authors: Floris Goerlandt, Kaarle Stahlberg, Pentti KujalaAbstract:Abstract An important element in assessing the consequences in a tanker collision is the probability of breaching an oil cargo tank. It is well recognized that the dynamic parameters at the moment of Impact significantly affect the deformation energy. Assumptions regarding dynamic parameters at the moment of Impact are nevertheless little discussed in context of collision risk analysis. The available Impact Scenario models are analyzed using a system risk approach. Comparison of Impact Scenario models from literature is performed with a risk analysis algorithm emphasizing on oil tanker collisions. Monte Carlo simulation is applied in the risk analysis algorithm for each Impact Scenario model. Only the Impact Scenario module is changed while other modules of the algorithm (encounter Scenario generation, determination of deformation energy and structural hull capacity) are kept the same. Analysis reveals important differences in results of risk analysis when performed with different assumptions for the Impact Scenario. Moreover, in the discussion inherent conceptual limitations of the Impact Scenario models in the system risk framework are revealed. It is concluded that using more accurate collision energy and/or structural capacity models for purposes of maritime traffic risk analysis is currently not worthwhile, as the uncertainty regarding Impact Scenario is overwhelming.
