scholarly journals Connectivity of larval stages of sedentary marine communities between hard substrates and offshore structures in the North Sea

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Johan van der Molen ◽  
Luz María García-García ◽  
Paul Whomersley ◽  
Alexander Callaway ◽  
Paulette E. Posen ◽  
...  
Keyword(s):  
North Sea ◽  
Offshore Structures ◽  
Marine Communities ◽  
Larval Stages ◽  
The North ◽  
The North Sea ◽  
Hard Substrates

Emergency Towing: Field Exercises and Simulator-Based Training

2008 ◽  
Author(s):  
Tor E. Berg ◽  
Gunnar Gudmundset ◽  
Ulf Klevstad
Keyword(s):  
Emergency Response ◽  
North Sea ◽  
Offshore Structures ◽  
Coastal Environment ◽  
Traffic Density ◽  
Functional Requirements ◽  
Northern Norway ◽  
The North ◽  
Different Types ◽  
The North Sea

Recently there have been a number of incidents involving drifting ships and offshore structures in the North Sea. Increasing traffic density combined with harsher weather and less experienced crews has led the Norwegian Coastal Administration to focus on improving the skills of personnel on board emergency response vessels operating off the coast of Northern Norway. This is order to reduce the consequences of incidents with disabled vessels sailing in the vulnerable coastal environment of the Norwegian and Barents Seas. In addition to field exercises involving dedicated Norwegian emergency response vessels and different types of vessels made available by shipping companies, training takes place on full mission bridge simulators. As part of an ongoing R&D project, MARINTEK and SMS invite stakeholders to participate in short workshops on topics related to the specification of functional requirements for emergency towing vessels and the sharing of experience from recent emergency towing operations.

Sole larval distribution (Solea solea) in the eastern English Channel and Southern Bight of the North Sea

2001 ◽  
Vol 81 (4) ◽  
pp. 673-678 ◽  
Author(s):  
A. Grioche ◽  
P. Koubbi ◽  
X. Harlay ◽  
B. Sautour
Keyword(s):  
North Sea ◽  
Environmental Parameters ◽  
English Channel ◽  
Southern Bight ◽  
Intermediate Variable ◽  
Larval Stages ◽  
The North ◽  
Larval Distribution ◽  
Solea Solea ◽  
The North Sea

The distribution of sole (Solea solea) eggs and larvae were described from two cruises conducted in April and May 1995 along the French coast of the eastern English Channel and the Belgian coast of the Southern Bight of the North Sea. Sole migration was investigated using larval stages and univariate spatial analysis as geostatistics (variograms). Important environmental parameters were selected by comparison with larval distribution. Path analysis was used to remove spatial correlation and to define links between abundance and environmental variables.  Sole larvae were found to be coastal throughout their development. Strong links between larval distribution and environmental parameters were identified, particularly for the younger stages which were found in higher abundance in areas of high chlorophyll-a concentration. The association was not direct, suggesting that the larval spatial distribution was influenced by an undetermined, intermediate variable, such as larval prey. Sole larvae are retained in the coastal area throughout ontogeny despite the strong hydrodynamics which characterize the region. Larval distribution resulted from behavioural mechanisms as well as environmental influences.

Reliability analysis of foundation stability for gravity platforms in the North Sea

1989 ◽  
Vol 26 (3) ◽  
pp. 359-368 ◽  
Author(s):  
Tien H. Wu ◽  
Oddvar Kjekstad ◽  
In-Mo Lee ◽  
Suzanne Lacasse
Keyword(s):  
North Sea ◽  
Reliability Index ◽  
Site Investigation ◽  
Offshore Structures ◽  
Material Strength ◽  
Strength Measurement ◽  
The North ◽  
The North Sea ◽  
Coefficients Of Variations ◽  
The Mean

The uncertainties encountered in the evaluation of foundation stability for four offshore gravity structures in the North Sea are reviewed. The uncertainties include those about the load, the material type, the material strength, and the analytical method. The means and coefficients of variations of these are used as inputs to compute the mean and coefficient of variation of the safety factor and the reliability index. The latter are used to assess the effect of various options in site exploration and strength measurement on foundation reliability. Key words: foundation, gravity platforms, offshore structures, probability, reliability, shear strength, site investigation, stability.

scholarly journals The Larval Stages of processa canaliculata Leach

1923 ◽  
Vol 13 (1) ◽  
pp. 245-265 ◽  
Author(s):  
Robert Gurney
Keyword(s):  
North Sea ◽  
Short Stay ◽  
Larval Form ◽  
Additional Material ◽  
Larval Stages ◽  
Working Through ◽  
The North ◽  
The North Sea

The material upon which the following account of the development of P.canaliculata is based was mainly obtained in 1902 when working in the Laboratory at Plymouth. The larvæ were first noticed, and their identity suspected, in April of that year, and identification was made certain by keeping the larvæ in the “mysis” stage until they moulted into the post-larval form, some individuals being kept also through several subsequent moults. The intermediate stages were all taken from the plankton, since I was unable to hatch the larvæ from the egg. The only egg-bearing female seen at that time was taken on the Eddystone Ground on April 29, and her eggs were so far advanced that, although she was unfortunately killed, a few larvæ escaped from the eggs and made it possible to obtain some idea of the structure of the first zoæa.During a short stay in Plymouth during April, 1922,1 was able not only to pick out a few more specimens from the plankton then brought in, but also, by working through a large number of preserved plankton samples, to obtain a considerable amount of additional material, mainly of later stages. A few specimens have also been found in samples of plankton from the North Sea preserved at the Fisheries Laboratory at Lowestoft, for the loan of which I am indebted to Mr. A. C. Hardy. But the larvæ of this species are much rarer in the North Sea than in the neighbourhood of Plymouth, where they are quite common.

scholarly journals The Early Stages of Nephrops norvegicus, from the Northumberland Plankton, together with a note on the post-larval development of Homarus vulgaris

1925 ◽  
Vol 13 (4) ◽  
pp. 870-879 ◽  
Author(s):  
Olga M. Jorgensen
Keyword(s):  
Larval Development ◽  
North Sea ◽  
Young Fish ◽  
Nephrops Norvegicus ◽  
Larval Stages ◽  
Early Stages ◽  
The North ◽  
Third Stage ◽  
The North Sea

Although adult Norway lobsters are extremely common on the southern part of the Northumberland coast, there were no records of the taking of larvæ of the species in this part of the North Sea until the Plankton Investigation now being carried out at Cullercoats (1) was commenced.During the period 1921–23 a few specimens were taken from time to time in the ordinary plankton hauls, but the best catches of Nephrops larvæ were obtained from the young fish trawl used at a number of stations in 1922 arid 1923. It is, therefore, chiefly on the material from the last two years' samples that the following observations are based.All three of the larval stages have been obtained, together with a single post-larva, but the majority of our specimens are second and third stage larvæ.

Development of Fatigue Design Standards for Marine Structures

2017 ◽  
Author(s):  
Inge Lotsberg
Keyword(s):  
North Sea ◽  
Wind Turbines ◽  
Offshore Structures ◽  
Support Structures ◽  
Marine Structures ◽  
Design Standards ◽  
The North ◽  
Fatigue Design ◽  
The North Sea

Fatigue design standards for offshore structures became needed with development of offshore structures in harsh environments like the North Sea during the 1970s. The Ultimate Limit State had earlier been the most significant design requirement for similar platforms in the Mexican Gulf being less utilized with respect fatigue. The need for fatigue design of ship structures became increased as more high strength steel was being used in these structures during the 1970s. The analysis method for long term loading and assessment of fatigue capacity has been improved over the years and this has also resulted in need for new and revised design standards. New types of structures and structural components have been developed like tension leg platforms and support structures for wind turbines. These structures are subjected to significant dynamic loading such that fatigue design becomes the main issue and relevant fatigue design standards are needed. Fatigue assessment of fixed offshore structures in the North Sea has been standard practice since the 1970s. Fatigue of floating platforms became a requirement after the accident with the Alexander Kielland platform in 1980. Later new types of structures have been installed in the North Sea such as tension leg platforms and floating production ships where fatigue has been an important part of the design. A further challenge with respect to fatigue came with the development of support structures for wind turbines to be installed in the sea. This paper gives an overview of the development of fatigue design standards for marine structures over the last 40 years. This includes the significance of refined calculation of long term stress range distribution, calculation of hot spot stress, size effect and effect of mean stress effect on fatigue design of ship structures.

scholarly journals Assessing Extreme Environmental Loads on Offshore Structures in the North Sea from High-Resolution Ocean Currents, Waves and Wind Forecasting

2021 ◽  
Vol 9 (10) ◽  
pp. 1052
Author(s):  
Nikolaos Skliris ◽  
Robert Marsh ◽  
Meric Srokosz ◽  
Yevgeny Aksenov ◽  
Stefanie Rynders ◽  
...  
Keyword(s):  
High Resolution ◽  
Continental Shelf ◽  
North Sea ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Environmental Loads ◽  
The North ◽  
Shelf Slope ◽  
Hourly Data ◽  
The North Sea

The fast development of the offshore energy industry becomes an essential component of resilient economies in most of the countries around the North Sea, addressing an increasing demand for cost-efficient and environmentally safe energy sources. Offshore wind farms are planned to be installed further away from the coasts to ensure stronger and more stable wind resources in this region. Oil and gas extraction infrastructures are also planned to move into deeper areas of the continental shelf and continental shelf slopes to explore new fields. These deeper areas of the ocean are characterised by harsh environmental conditions: stronger winds, larger waves and strong shelf slope currents, inducing considerably larger loads on offshore structures. This study brings together operational physical oceanography and the mathematics of fluid-structure interactions to estimate the likelihood of extreme environmental loads on offshore structures in the North Sea. We use the state-of-the-art Met Office high resolution ocean forecasting system, which provides high-frequency data on ocean and tidal currents, wave heights and periods and winds at a ~7 km horizontal resolution grid, spanning the North–West European Shelf. The Morison equation framework is used to calculate environmental loads on various types of offshore structures that are typically employed by the offshore industries in the North Sea. We use hourly data for a 2-year period to analyse the spatio-temporal variability of mean and extreme hydrodynamic loads and derive the relative contributions of currents, waves and winds in the region. The results indicate that waves dominate extreme hydrodynamic forces on the shallow shelf, whereas the current contribution is important at the shelf break and in the English Channel.

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