Life Cycle Cost Analysis of a Floating Wind Farm Located in the Norwegian Sea

This thesis aims to investigate the levelized cost of energy of an offshore floating wind farm, as well as evaluate its financial feasibility. Thus, the research question is as follows: How to estimate the life cycle costs of a floating wind farm off the coast of Norway? The investigated wind farm is located off the coast of Norway, more specifically in the Troll field area west of Bergen. This area has a water depth of 325 m and a distance to shore of 65 km. The wind farm is set to consist of 50 wind turbines and has a lifespan of 25 years. The OC4 Deepwind semisubmersible floater developed by the National Renewable Energy Laboratory, complemented with a 15 MW turbine, is used as the research model. To find the capital expenditures of the planned wind farm, the Offshore Renewables Balance-of-system and Installation Tool is used, while the operational expenditures are calculated based on the theoretical energy output. The total levelized cost of energy of the wind farm is calculated to be 100.69 $/MWh. Capital expenditure is the most prominent cost and constitutes 63.1 expenditures constitute the remaining 36.9 lifespan, capacity factor, and project discount rate are the factors with the most potential to influence the levelized cost of energy. The financial calculations show that the wind farm is not economically feasible as it has a computed net present value of negative$ 561 900 000. Finally, novel offshore wind energy solutions involving the utilization of shared substructures and mooring lines have been studied, and the findings suggest the possibility of a diminished levelized cost of energy

Life Cycle Cost Analysis of a Floating Wind Farm Located in the Norwegian Sea

This thesis aims to investigate the levelized cost of energy of an offshore floating wind farm, as well as evaluate its financial feasibility. Thus, the research question is as follows: How to estimate the life cycle costs of a floating wind farm off the coast of Norway? The investigated wind farm is located off the coast of Norway, more specifically in the Troll field area west of Bergen. This area has a water depth of 325 m and a distance to shore of 65 km. The wind farm is set to consist of 50 wind turbines and has a lifespan of 25 years. The OC4 Deepwind semisubmersible floater developed by the National Renewable Energy Laboratory, complemented with a 15 MW turbine, is used as the research model. To find the capital expenditures of the planned wind farm, the Offshore Renewables Balance-of-system and Installation Tool is used, while the operational expenditures are calculated based on the theoretical energy output. The total levelized cost of energy of the wind farm is calculated to be 100.69 $/MWh. Capital expenditure is the most prominent cost and constitutes 63.1 expenditures constitute the remaining 36.9 lifespan, capacity factor, and project discount rate are the factors with the most potential to influence the levelized cost of energy. The financial calculations show that the wind farm is not economically feasible as it has a computed net present value of negative$ 561 900 000. Finally, novel offshore wind energy solutions involving the utilization of shared substructures and mooring lines have been studied, and the findings suggest the possibility of a diminished levelized cost of energy

Life Cycle Cost Analysis of a Floating Wind Farm Located in the Norwegian Sea

This thesis aims to investigate the levelized cost of energy of an offshore floating wind farm, as well as evaluate its financial feasibility. Thus, the research question is as follows: How to estimate the life cycle costs of a floating wind farm off the coast of Norway? The investigated wind farm is located off the coast of Norway, more specifically in the Troll field area west of Bergen. This area has a water depth of 325 m and a distance to shore of 65 km. The wind farm is set to consist of 50 wind turbines and has a lifespan of 25 years. The OC4 Deepwind semisubmersible floater developed by the National Renewable Energy Laboratory, complemented with a 15 MW turbine, is used as the research model. To find the capital expenditures of the planned wind farm, the Offshore Renewables Balance-of-system and Installation Tool is used, while the operational expenditures are calculated based on the theoretical energy output. The total levelized cost of energy of the wind farm is calculated to be 100.69 $/MWh. Capital expenditure is the most prominent cost and constitutes 63.1$ 561 900 000. Finally, novel offshore wind energy solutions involving the utilization of shared substructures and mooring lines have been studied, and the findings suggest the possibility of a diminished levelized cost of energy

Prediction of dynamic mooring responses of a floating wind turbine using an artificial neural network

Numerical simulations in coupled aero-hydro-servo-elastic codes are known to be a challenge for design and analysis of offshore wind turbine systems because of the large number of design load cases involved in checking the ultimate and fatigue limit states. To alleviate the simulation burden, machine learning methods can be useful. This article investigates the effect of machine learning methods on predicting the mooring line tension of a spar floating wind turbine. The OC3 Hywind wind turbine with a spar-buoy foundation and three mooring lines is selected and simulated with SIMA. A total of 32 sea states with irregular waves are considered. Artificial neural works with different constructions were applied to reproduce the time history of mooring tensions. The best performing network provides a strong average correlation of 71% and consists of two hidden layers with 35 neurons, using the Bayesian regularisation backpropagation algorithm. Sea states applied in the network training are predicted with greater accuracy than sea states used for validation of the network. The correlation coefficient is primarily higher for sea states with lower significant wave height and peak period. One sea state with a significant wave height of 5 meters and a peak period of 9 seconds has an average extreme value deviation for all mooring lines of 0.46%. Results from the study illustrate the potential of incorporating artificial neural networks in the mooring design process.publishedVersio

Finiteness Obstruction in Model Categories

Vi viser in denne oppgaven at det er en naturlig måte og gjøre god for endelighets obstruksjon i en generell modell kategori. Operatoren $(Wa(-), w(-))$ vises å være en funktor fra modell kategorier hvor det eksisterer kofibrant generering til kategorien av abelske grupper. Vi viser også hvordan denne oppfører seg på produkter

Prediction of dynamic mooring responses of a floating wind turbine using an artificial neural network

Numerical simulations in coupled aero-hydro-servo-elastic codes are known to be a challenge for design and analysis of offshore wind turbine systems because of the large number of design load cases involved in checking the ultimate and fatigue limit states. To alleviate the simulation burden, machine learning methods can be useful. This article investigates the effect of machine learning methods on predicting the mooring line tension of a spar floating wind turbine. The OC3 Hywind wind turbine with a spar-buoy foundation and three mooring lines is selected and simulated with SIMA. A total of 32 sea states with irregular waves are considered. Artificial neural works with different constructions were applied to reproduce the time history of mooring tensions. The best performing network provides a strong average correlation of 71% and consists of two hidden layers with 35 neurons, using the Bayesian regularisation backpropagation algorithm. Sea states applied in the network training are predicted with greater accuracy than sea states used for validation of the network. The correlation coefficient is primarily higher for sea states with lower significant wave height and peak period. One sea state with a significant wave height of 5 meters and a peak period of 9 seconds has an average extreme value deviation for all mooring lines of 0.46%. Results from the study illustrate the potential of incorporating artificial neural networks in the mooring design process

Circulating cytokine levels in the treatment of comorbid anxiety disorders

Psychotherapy research aims to investigate predictors and moderators of treatment outcome, but there are few consistent findings. This study aimed to investigate cytokines in patients undergoing treatment for anxiety disorders and whether the level of cytokines moderated the treatment outcome. Thirty-seven patients with comorbid and treatment-resistant anxiety disorders were investigated using multilevel modelling. Serum cytokine levels were measured three times: pretreatment, in the middle of treatment, and at the end of treatment. Anxiety and metacognitions were measured weekly throughout treatment by self-report. The levels of monocyte chemoattractant protein-1, tumour necrosis factor-alpha, and interleukin-1 receptor antagonist did not change during therapy or were not related to the level of anxiety. Metacognitive beliefs predicted anxiety, but the relationship between metacognitions and anxiety was not moderated by cytokines. Limitations of the study include that the patients were not fasting at blood sampling, and we did not assess body mass index, which may affect cytokine levels. The lack of significance for cytokines as a predictor or moderator may be due to a lack of power for testing moderation hypotheses, a problem associated with many psychotherapy studies. Cytokines did not predict the outcome in the treatment of comorbid anxiety disorders in our sample. Furthermore, cytokines did not moderate the relationship between metacognitions and anxiety. Keywords: anxiety; comorbidity; cytokines; metacognition; psychotherapy

Circulating cytokine levels in the treatment of comorbid anxiety disorders

Psychotherapy research aims to investigate predictors and moderators of treatment outcome, but there are few consistent findings. This study aimed to investigate cytokines in patients undergoing treatment for anxiety disorders and whether the level of cytokines moderated the treatment outcome. Thirty-seven patients with comorbid and treatment-resistant anxiety disorders were investigated using multilevel modelling. Serum cytokine levels were measured three times: pretreatment, in the middle of treatment, and at the end of treatment. Anxiety and metacognitions were measured weekly throughout treatment by self-report. The levels of monocyte chemoattractant protein-1, tumour necrosis factor-alpha, and interleukin-1 receptor antagonist did not change during therapy or were not related to the level of anxiety. Metacognitive beliefs predicted anxiety, but the relationship between metacognitions and anxiety was not moderated by cytokines. Limitations of the study include that the patients were not fasting at blood sampling, and we did not assess body mass index, which may affect cytokine levels. The lack of significance for cytokines as a predictor or moderator may be due to a lack of power for testing moderation hypotheses, a problem associated with many psychotherapy studies. Cytokines did not predict the outcome in the treatment of comorbid anxiety disorders in our sample. Furthermore, cytokines did not moderate the relationship between metacognitions and anxiety. Keywords: anxiety; comorbidity; cytokines; metacognition; psychotherapy

Intravenous alteplase for stroke with unknown time of onset guided by advanced imaging: systematic review and meta-analysis of individual patient data

Background: Patients who have had a stroke with unknown time of onset have been previously excluded from thrombolysis. We aimed to establish whether intravenous alteplase is safe and effective in such patients when salvageable tissue has been identified with imaging biomarkers. Methods: We did a systematic review and meta-analysis of individual patient data for trials published before Sept 21, 2020. Randomised trials of intravenous alteplase versus standard of care or placebo in adults with stroke with unknown time of onset with perfusion-diffusion MRI, perfusion CT, or MRI with diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR) mismatch were eligible. The primary outcome was favourable functional outcome (score of 0–1 on the modified Rankin Scale [mRS]) at 90 days indicating no disability using an unconditional mixed-effect logistic-regression model fitted to estimate the treatment effect. Secondary outcomes were mRS shift towards a better functional outcome and independent outcome (mRS 0–2) at 90 days. Safety outcomes included death, severe disability or death (mRS score 4–6), and symptomatic intracranial haemorrhage. This study is registered with PROSPERO, CRD42020166903. Findings: Of 249 identified abstracts, four trials met our eligibility criteria for inclusion: WAKE-UP, EXTEND, THAWS, and ECASS-4. The four trials provided individual patient data for 843 individuals, of whom 429 (51%) were assigned to alteplase and 414 (49%) to placebo or standard care. A favourable outcome occurred in 199 (47%) of 420 patients with alteplase and in 160 (39%) of 409 patients among controls (adjusted odds ratio [OR] 1·49 [95% CI 1·10–2·03]; p=0·011), with low heterogeneity across studies (I 2=27%). Alteplase was associated with a significant shift towards better functional outcome (adjusted common OR 1·38 [95% CI 1·05–1·80]; p=0·019), and a higher odds of independent outcome (adjusted OR 1·50 [1·06–2·12]; p=0·022). In the alteplase group, 90 (21%) patients were severely disabled or died (mRS score 4–6), compared with 102 (25%) patients in the control group (adjusted OR 0·76 [0·52–1·11]; p=0·15). 27 (6%) patients died in the alteplase group and 14 (3%) patients died among controls (adjusted OR 2·06 [1·03–4·09]; p=0·040). The prevalence of symptomatic intracranial haemorrhage was higher in the alteplase group than among controls (11 [3%] vs two [<1%], adjusted OR 5·58 [1·22–25·50]; p=0·024). Interpretation: In patients who have had a stroke with unknown time of onset with a DWI-FLAIR or perfusion mismatch, intravenous alteplase resulted in better functional outcome at 90 days than placebo or standard care. A net benefit was observed for all functional outcomes despite an increased risk of symptomatic intracranial haemorrhage. Although there were more deaths with alteplase than placebo, there were fewer cases of severe disability or death. Funding: None

Production of inclusive ϒ(1S) and ϒ(2S) in p–Pb collisions at sNN=5.02\sqrt{s_{\rm NN}} = 5.02 TeV

We report on the production of inclusive ϒ (1S) and ϒ (2S) in p–Pb collisions at sNN=5.02 TeV at the LHC. The measurement is performed with the ALICE detector at backward ( −4.46<ycms<−2.96 ) and forward ( 2.03<ycms<3.53 ) rapidity down to zero transverse momentum. The production cross sections of the ϒ (1S) and ϒ (2S) are presented, as well as the nuclear modification factor and the ratio of the forward to backward yields of ϒ (1S). A suppression of the inclusive ϒ (1S) yield in p–Pb collisions with respect to the yield from pp collisions scaled by the number of binary nucleon–nucleon collisions is observed at forward rapidity but not at backward rapidity. The results are compared to theoretical model calculations including nuclear shadowing or partonic energy loss effects