bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multidisciplinary Design Analysis and Optimisation of Floating Offshore Wind Turbine Support Structures - Coupled Model Solution Strategies
Authors: Patryniak K , Collu M , Coraddu A 
Published: November 2023

Abstract
Floating Offshore Wind Turbines (FOWT) can be installed at the sites of the most abundant wind resource. However, the design uncertainties and risks must be reduced to make them economically competitive. The design and optimisation methodologies for FOWT support structures adopted up to date tend to follow a sequential analysis strategy. Since the FOWT system involves multiple distinct, highly coupled disciplines, its analysis and design are challenging. This paper presents an efficient implementation of a coupled model of dynamics in an optimisation process by applying a Multidisciplinary Design Analysis and Optimisation (MDAO) methodology. The coupling effects studied include the interdependence of the mean offset of the platform and the aerodynamic and mooring loads, as well as the velocity of the platform and the viscous damping. The trade-off between the solution accuracy and efficiency for the coupled and uncoupled models was quantified, and a range of iterative solvers were compared. The study showed that the coupling between the platform offset and the mooring and thrust loads has a significant influence on the values of the responses, converging at higher surge and pitch offsets, higher mooring loads, and at lower thrust. These non-conservative results demonstrated the criticality of the two-way coupling between the platform excursion and the mooring loads. Notably, the coupled solution was achieved at a relatively low increase in the total solution time (+16%), due to the high efficiency of Broyden’s method.
Constrained optimization of offshore wind turbine positions under uncertain wind conditions with correlated data
Authors: Pettersson Per , Aursjø Olav , Helland Johan Olav , Jettestuen Espen 
Published: November 2023

Abstract
Offshore wind power production is subject to substantial uncertainty due to variability in wind conditions. Planning of new wind parks should take these uncertainties into account by means of stochastic modeling and uncertainty quantification. Wind speed and wind direction exhibit dependence that needs to be properly modeled to yield reliable uncertainty estimates. In particular, the dependence is strong when data are averaged over a short time-horizon, e.g., on a monthly rather than an annual basis. In this work we introduce a stochastic model for wind speed and wind direction using Rosenblatt transformation and an empirical model. This allows efficient numerical quadrature that replaces thousands of Monte Carlos samples by a few tens of model evaluations at quadrature points in parametric space. A robust design formulation for maximizing power production honoring dependent data is proposed and demonstrated on data from the North Sea site Sørlige Nordsjø II.
Effect of the vertical wake deflection on the response of a 12MW semisubmersible FWT
Authors: Rivera-Arreba I , Eliassen L , Bachynski-Polić E 
Published: November 2023

Abstract
The need to understand the interaction of floating wind turbines operating in the marine boundary layer with other surrounding turbines is of increasing importance as wind farms and rotor sizes get larger. For low wind speed conditions, the wake deflects upwards due to the floating wind turbine built-in rotor tilt and the platform pitch angle. Furthermore, based on field data from the North Sea, a convective atmosphere is likely to occur, especially for lower wind speeds. It is therefore key to understand the combined effect of meandering, wake deflection and atmospheric stability for low wind speed conditions on the floating wind turbines in a wind farm.
In this work, to account for atmospheric stability, data from large-eddy simulation (LES) for a 7.5m/s wind speed scenario and three atmospheric stability conditions, are used as input to FAST. Farm to study the effect of the wake deflection upwards on a 12 MW semisubmersible placed 8 rotor diameters (D) downwind of a stationary wind turbine. Three built-in shaft tilt angles cases are considered for the fixed upwind turbine: 12°, 6° and no tilt angle. The main effects of the wake deflection are on the power output of the floating wind turbine in the wake, and on the tower top yaw moment. For stable conditions, the mean tower top yaw moment increases by more than three times. The findings of this work contribute to the investigation of the wake deflection as a control strategy to minimize wake losses in floating wind farms.
A comparison of extreme mooring loads and response of a spar-buoy wind turbine using conditional waves
Authors: Ripe Aminda M. T. , Lande-Sudall David R. 
Published: November 2023

Abstract
Three-hour random sea-state evaluations for ultimate limit state design of floating offshore wind installations are time-consuming and prevent the use of high-fidelity numerical methods from being implemented. In this work, three conditional waves, Most-Likely Wave (MLW), Most-Likely Response Wave (MLRW) and Conditional Random Response Wave (CRRW), are experimentally investigated as alternative means to generate statistical extreme responses in surge and mooring line loads of a spar-buoy substructure, with shorter time-series duration compared to a 3-hour JONSWAP sea-state. MLW and MLRW are found to generate the greatest mooring line loads, far greater than the statistical expected maximum from a 3-hour random sea-state. However, MLW is uncorrelated with the substructure’s linear transfer function of response, and the MLRW includes no memory effects from a random background sea, indicating possible conservatism in the associated load magnitudes. CRRW is a MLRW embedded within a random background and is found to excite a similar mooring load as the 3-hour sea-state, with memory effects included. CRRW could thus be an appropriate method of generating statistically appropriate load responses within a reduced time-series. However, nonlinear effects on the mooring are not accounted for in any of the methods and will be included in future work.
Data-driven modeling of hydrodynamic loading using NARX and harmonic probing
Authors: Stamenov D , Abbiati G , Sauder T 
Published: November 2023

Abstract
Optimizing floating wind turbines and their mooring systems requires validated computational models that predict wave-frequency and low-frequency hydrodynamic loads. Low-frequency loads are crucial for determining extreme offsets and tension in mooring lines and are generally described by a quadratic transfer function. The quadratic transfer function, obtained with numerical tools, accurately predicts low-frequency loads in mild sea states. However, since the existing numerical methods are based on potential and perturbation theory, they generally fail to accurately predict low-frequency loads in moderate-to-extreme sea states where current, viscous, and beyond-second-order potential effects become significant. Developing a procedure for empirical transfer function estimation is, therefore, necessary to overcome these limitations. This paper describes an existing framework for estimating any higher-order transfer functions from experimental data. The framework employs a nonlinear auto-regressive model based on Kriging to establish a causal input/output relationship between the wave-elevation and hydrodynamic force histories exerted on the floater. Then, higher-order transfer functions are extracted using harmonic probing. The procedure was validated by estimating the linear surge transfer function of the INO WINDMOOR 12 MW floater using synthetic data. The data-driven results showed an excellent agreement with the theoretically computed transfer function.
Experimental Validation of Models of a Hull-Based Tuned Mass Damper System for a Semisubmersible Floating Offshore Wind Turbine Platform
Authors: Wang L , Bergua R , Robertson A , Jonkman J , Ngo T , Das T , Sarker D , Flavia F Fabregas , Harries R , Fowler M , Lenfest E , Muro J López , Burlion L , Bilgen O 
Published: November 2023

Abstract
Floating offshore wind turbine designs can be further optimized if the controller and remaining systems are designed together, known as control co-design. To effectively perform control co-design, modeling tools predicting the influence of the control systems on the response of a system must be validated. This article presents an experimental validation that utilizes a scale model of a semisubmersible platform for an offshore wind turbine that is fitted with adjustable tuned mass dampers. These dampers can be tuned to attenuate either the hull-pitch resonance or the tower-bending resonance. The data from the experiment are used to validate state-of-the-art modeling tools. It is shown that the models capture the overall effects of the tuned mass dampers; however, some models overpredict the reduction in platform pitch motion when the dampers are tuned to the pitch resonance. The relative reduction in the tower-base bending moment is more consistently captured by the models when the dampers are tuned to the tower-bending resonance. However, there are significant differences in the absolute level of tower-base bending moment between the models and the experiment. Much of the differences observed are a consequence of the challenge with accurately predicting the baseline platform resonance motion and the tower-bending moment, which should be addressed in future modeling efforts.
Whispers in the Wind: Ethical dimensions of social conflict in offshore wind
Authors: Vasconcellos Oliveira R 
Published: November 2023

Abstract
The current European energy crisis in combination with the international climate agreements dictate the need for strong investment in green energy. Among others, offshore wind is widely considered an efficient low-impact low-carbon technology. Despite the positive institutional landscape for the adoption of this form of energy generation, European nations witness societal resistance to its deployment. This paper explores the critical ethical dimensions of offshore wind fuelling relevant societal controversies surrounding its deployment and governance. I argue that at the core of most societal disputes lay normative issues shaping and contributing to the polarisation of the discourses and affecting the viability of initiatives. The method applied to characterise the social controversies is ethical analysis. Using the conceptualisation of the three tenets of energy justice-distributive, procedural, and recognition - I uncover the prevailing justice dimensions present in thematic literature and specific European offshore wind initiatives (Taggen park and Utsira Nord). I also use ethical analysis to characterise further normative implications of offshore wind. At the end, I offer normative insights on how project developers and policymakers can lower the barriers to offshore wind energy implementation and improve governance mechanisms.
Numerical investigation of blade roughness impact on the aerodynamic performance and wake behavior of horizontal axis wind turbine
Authors: Mian H H , Siddiqui M S , Yang L , Kvamsdal T , Asim T 
Published: November 2023

Abstract
The prolonged operation of wind turbines in harsh offshore environments leads to deterioration and roughness accumulation on the blade surface. This roughness, particularly on the leading edge and other surfaces, can affect the laminar-to-turbulent transition, alter the flow characteristics in the turbine wake and turbulent boundary layer, and become critical for the accurate design and performance analysis of offshore horizontal axis wind turbines (HAWT). This study investigates the effects of blade surface roughness on the aerodynamic performance and wake evolution of the NREL Phase VI wind turbine rotor using the Reynolds-Averaged Navier-Stokes (RANS) technique. First, 2D simulations are validated against experimental data of the S809 airfoil. Then, full-scale 3D simulations of the complete turbine model are conducted with roughness effects to simulate natural conditions. The results show that surface roughness reduces the blade’s aerodynamic performance. The rough surface increases the boundary layer thickness, causing flow separation and turbulence, which decrease the lift generated by the blade and increase its drag, resulting in decreased overall blade performance. At higher wind speeds, surface roughness has a negligible effect on turbine performance due to flow separation at the leading edge. The analysis of surface roughness effects on the turbine wake flow indicates that blade roughness positively correlates with wake recovery, where the wake velocity recovers faster with an increase in roughness height.
Planning the Installation of Marine Renewable Energies in Portugal - a tool for decision making
Authors: Simões Teresa , Couto António , Estanqueiro Ana 
Published: November 2023

Abstract
In the latest years, the European governments have developed and published the goals for their countries in terms of energy and climate as requested by the European Commission - The National Energy and Climate Plans (NECPs). In this sense, an intense activity on the planning of the installation of renewable energy systems took place in each Member State in order to meet the goals established on the NECPs. Following the recent energy crisis and the urgency to transform Europe’s energy system in Europe, the NECPs are also being adapted to this situation and the installation of renewable energy systems assumed an even higher relevance. In this sense, offshore wind, due to its characteristics – high wind resource, less occupation issues and others – will play a key role in the future energy mix. This work proposed the development and application of a holistic planning methodology considering the available offshore renewable resource, restrictions to the installation of marine energy systems and economic indicators, which resulted in a techno-economic platform – MarinePlan, developed in the scope of a National funded project – OffshorePlan
Influence of compaction direction on selected thermal and moisture properties of a lightweight composite based on magnesium binder and organic filler
Authors: Brzyski P , Jóźwiak M , Siwiec J , Sinka M , Medved I 
Published: November 2023

Abstract
An alternative binder in thermal insulation composites based on hemp shives is magnesium cement. It provides higher mechanical strength of the composite in comparison to the lime binder. Thanks to this, it is possible to reduce the amount of binder in relation to the shives, and as a result, obtain a lower density and better thermal insulation parameters. The process of compacting the composite mixture determines many of its properties. The longitudinal shape of the shives causes that during compaction they are arranged mainly perpendicular to the direction of compaction. The unidirectional course of the fibers in the shives determines the anisotropic nature of both the shives and the composite. The article presents the results of tests of thermal conductivity and capillary rise of the compacted composite in the direction perpendicular and parallel to the heat flux and moisture transport. A composite with a low binder content, characterized by a density of about 250 kg/m3, was tested. The direction of the mix compaction had an impact on the differences in the obtained results. This phenomenon can be used, for example, in the production of blocks or other prefabricated elements, using the appropriate direction of compaction depending on the expected properties and applications of the composite.
Quasi-one-dimensional treatment of heat transfer in beams of non-uniform cross-section
Authors: Bulatovič G , Bokes P 
Published: November 2023

Abstract
We test performance of a quasi-one-dimensional approach to steady state heat transfer in broadening beams, characterized by variable cross-sectional area. The results obtained analytically and by solving the governing equation numerically in Python, for three different instances, are compared to FEM simulations. We demonstrate that the quasi-one-dimensional model gives accurate predictions for beam suitably averaged temperatures but the range of Biot numbers for which it can be accurately applied to is currently limited by a crucial parameter.
Resistance to molds of flax-fiber based materials
Authors: Kobetičová K , Nábělková J , Brejcha V , Brich J , Böhm M , Černý R 
Published: November 2023

Abstract
In the present study, the prepared covering material based on flax fibers containing caffeine, nano-copper, or corundum (Al2O3) as a potential biocidal substance was prepared and tested on biological resistance. Two experimental designs were performed: a) the samples were placed in a desiccator at the air humidity of about 90 % and at a temperature of 25 °C for one month. The samples were then transferred to sterile agar and the coverage of the agars and the samples with molds were observed after a week of incubation. All samples were found to be infected. The samples containing copper were the least resistant. b) The samples were placed on sterile agar and the petri dishes were subjected to the fallout method, where both the samples and the agars were insulted by mold spores from the air. The Petri dishes with the samples were then placed in a thermostat in the dark at 25 °C for a week. After the end of the exposure, the samples and agars were observed. The samples were covered by molds with an increasing intensity in the following rank: caffeine sample = corundum sample < Cu sample = control sample = pure flax fibers.
Reaction kinetics of basaltic elements in cementitious matrices: theoretical considerations
Authors: Kočí V , Keppert M , Černý R. 
Published: November 2023

Abstract
Basalt fibers, the frequently mentioned alternative to those made of steel, possess very good mechanical properties and temperature resistance. The alkaline environment of cement matrix makes it vulnerable due to partial fiber decomposition by the effects of OH- ions. This paper aims at computational modelling of such reactions in order to approximate the course of degradation or to predict it lately. The isothermal reaction models are discussed to reveal their strong/weak points by means of fundamental reaction mechanisms analysis. The shape factor and diffusion-based deceleration of the reactions are mentioned as the most significant ones in that respect. The model accuracy is quantified based on fitting the modelling outputs to reference experimental data. The effect of discussion was found to be the most significant factor as the model fitting reached the lowest RMSE (0.0047). Further application of a diffusion model is therefore recommended. The geometrical models need to have reaction rate reduction explicitly incorporated in the reaction constant, otherwise inapplicable data is produced (RMSE = 0.0193).
Applications of thermal insulation materials by aircraft
Authors: Eze A H , Lakatos Á 
Published: November 2023

Abstract
Lightweight materials such as microfiber insulation or polymer foam are typically used to insulate cars and aircraft. But here, too, the use of state-of-the-art “super-insulating” materials is a valid answer. Vacuum insulation panels also serve as reliable insulators for electric vehicles. In this study, we will analyze in depth the potential uses for aerogels, polymer foams, and microfiber insulation. In addition, their thermal properties are briefly outlined, with a special focus on thermal conductivity and compressibility. Finding the right solution for the aircraft industry is critical. To meet increasingly stringent requirements, aircraft materials must meet several criteria, including lightweight, minimal noise, and insulation from the heat.
Application of automatic image analysis to evaluate the anisotropy of autoclaved aerated concrete for moisture transport
Authors: Majerek D , Wośko E , Pasnikowska-Łukaszuk M , Łazuka E , Suchorab Z , Łagód G 
Published: November 2023

Abstract
Autoclaved aerated concrete (AAC) is an artificial building material commonly applied in energy efficient buildings. Blocks of AAC are characterized by relatively homogenous distribution of pores and their dimensions. However, during manufacturing there occurs irregular pores positioning which may influence water transport processes. This phenomenon is called anisotropy which could be evaluated using standard gravimetric or electric methods of moisture detection. In this article we propose a method of level of anisotropy evaluation using image analysis. During the research a set of AAC samples was prepared and examined using time domain reflectometry (TDR) method for capillary uptake phenomenon and in parallel the cross-sections visual analyses were conducted. Both techniques confirmed the anisotropic features of the tested material.
Thermodilatometry of Quartz Porcelain Mixture Under Tensile Loading
Authors: Ondruška Ján , Al-Shantir Omar , Štubňa Igor 
Published: November 2023

Abstract
Specimens composed of 50 wt.% kaolin, 25 wt.% quartz, and 25 wt.% feldspar were subjected to constant tensile stress during linear heating at 5 °C/min rate to measure their tensile deformation behavior. Deformation occurs at temperatures above 300 °C and depends on the tensile stress: higher external tensile stresses led to a more pronounced expansion of the sample during the dehydroxylation region. Consequently, at temperatures above 1100 °C, sintering of the samples in the liquid state and intense contraction occurred. The dilatation behaviour of the samples was governed by the combined effect of opposing forces. One of these forces originated from external loading and caused the elongation of the specimen. The other force resulted from surface tension, which resulted in the shortening of the specimen. At temperatures above 1100 °C, a distinct V-shaped minimum appeared on the dilatometric plot, indicating a balance between these forces. As the temperature increased, the viscosity of the glassy phase decreased, weakening the surface forces. Eventually, the external force prevailed, causing further elongation of the samples.
The influence of the cooling system on the efficiency of thermal management and the performance of computer components
Authors: Szulzyk-Cieplak J , Oborski D , Paśnikowska-Łukaszuk M , Wlazło M , Urzędowski A , Zaburko J 
Published: November 2023

Abstract
The article attempts to evaluate the existing methods of cooling computer components in terms of ensuring their efficient operation. Issues related to heat exchange were discussed and individual computer components were characterized in terms of heat reception and the available methods of cooling computer components were reviewed. Based on the analysis of cooling methods, the most appropriate solution was selected in terms of: efficiency, costs and generated noise. A liquid cooling system was designed for the model computer, allowing for a significant increase in the clock speed of the computer’s main components. In order to determine the efficiency of the system, i.e. the maximum flow that can be discharged by the system, and to determine the efficiency of the required coolers, appropriate calculations were made regarding: thermal conductivity between each of the cooled elements and the corresponding block and heat transfer to the cooling liquid inside each of the blocks.