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Impact of foundation modelling in offshore wind turbines: Comparison between simulations and field data
Get PDFThe design of Offshore Wind Turbines (OWTs) relies on integrated simulation tools capable of predicting the system dynamic characteristics and the coupled loads and responses. Despite allefforts to develop accurate integrated models, these often fail to reproduce the measured naturalfrequencies, partly due to the modelling of the foundation. Several foundation models and ca-libration approaches have been proposed and compared with small or large scale field tests,where only the soil and the foundation are included. However, there is a lack of more integralvalidation where the interaction between the foundation and the structure is taken into account.The paper investigates the impact of the foundation model and calibration approach on the si-mulated response of a monopile-based OWT installed in the North Sea by comparing simulationsand full-scale field data. The OWT structure and the environmental actions are implemented inthe aero-servo-hydro-elastic code 3DFloat. Two foundation models and two calibration ap-proaches are evaluated. The results indicate that, with a conceptually correct foundation modeland a realistic calibration, it is possible to match the measured natural frequency and predictaccurate fatigue loads. More accurate predicted loads will reduce uncertainties in the estimatedfatigue lifetime and therefore reduce risk in the designImpact of foundation modelling in offshore wind turbines: Comparison between simulations and field dataacceptedVersio
Increased sensitivity in near infrared hyperspectral imaging by enhanced background noise subtraction
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Vulnerabilities in prevention and treatment of malnutrition – the role of the electronic patient journal
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Miljøgifter i ferskvann - MILFERSK År: 2018
No full textThis report studies the distribution and fate of contaminants such as mercury (Hg), cyclic volatile methylated siloxanes (cVMS: D4, D5, D6), brominated flame retardants (BFR, PBDEs), alkylphenols, organic phosphorous flame retardants (oPFR), poly- and perfluorated alkyl substances (PFAS), new brominated flame retardants (nBFR) and UV-chemicals. Samples of the pelagic food web of Lake Mjøsa (zooplankton, Mysis, vendace, European smelt and brown trout) and the top predator brown trout in Lake Femunden are studied. Results are compared to environmental quality standards (EQS) and the time trends for major contaminants are studied.Monitoring of environmental contaminants in freshwater ecosystems 2018 – Occurrence and biomagnificationMiljøgifter i ferskvann - MILFERSK År: 2018publishedVersio
Investigation of oil-water flow in concentric and fully eccentric annuli pipes
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Application of Hydrides in Hydrogen Storage and Compression: Achievements, Outlook and Perspectives
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Changes in Thermal Stability of Cyclic Aged Commercial Lithium-Ion Cells
Get PDFThermal stability is one of several factors affecting the safety properties of lithium-ion cells. The thermal stability for uncycled cells is well-documented, but the effect of cyclic ageing on thermal stability is far less studied and only for 18650 sized cells. In this paper, we describe how different temperature and current loads are affecting the thermal stability during cyclic aging. Three cylindrical lithium-ion power cells with different cathode, energy content and size were cyclic aged. Decrease in thermal stability was found in all three cyclic ageing test series as a function of relatively high current and low temperature. The decrease in thermal stability could be dangerous and should be an end of life criterion.acceptedVersio
Modelling the Effect of Porous Iron Sulfide Layers on Sour Corrosion Behaviour
Get PDFSurface layers and deposits of iron sulfides formed from sour corrosion may exhibit both protective and corrosive properties, depending on the types of iron sulfide formed and the physical structure of the layers. The protective barrier and blocking effects of the layers may be counteracted by significant cathodic activity on the surfaces of electrically conductive iron sulfides and galvanic corrosion of the underlying steel surface. Experimental and modelling work were performed to quantify the effects that parameters such as layer thickness and porosity, H2S partial pressure, temperature and pH can have on the electrochemical reactions, aqueous equilibria and mass-transport processes governing the corrosion rate. The results were discussed in the light of available literature and compared to relevant sour corrosion data, including both native corrosion product layers and applied iron sulfide deposits (UDC). Paper reproduced with permission from CORROSION/2019 Annual Conference and Exhibition. www.nace.orgpublishedVersio