Development of numerical and data models for the support of digital twins in offshore wind engineering

Error on title page. Date of award is 2022.As offshore wind farms grow there is a continued demand for reduced costs. Maintenance costs and downtime can be reduced through greater information on the asset in relation to its operational loads and structural resistance to damage and so there is an increasing interest in digital twin technologies. Through digital twins, an operational asset can be replicated computationally, thus providing more information. Modelling these aspects requires a wide variety of models in different fields. To advance the feasibility of digital twin technology this thesis aims to develop the multi-disciplinary set of modelling domains which help form the basis of future digital twins. Throughout this work, results have been validated against operational data recorded from sensors on offshore structures. This has provided value and confidence to the results as it shows how well the mix of state-of-the art models compare to real world engineering systems. This research presents a portfolio of five research areas which have been published in a mix of peer-reviewed journal articles and conference papers. These areas are: 1) A computational fluid dynamics (CFD) model of an offshore wind farm conducted using a modified solver in the opensource software. This work implements actuator disk turbine models and uses Reynolds averaged Naiver Stokes approaches to represent the turbulence. This investigates the impact of modelling choices and demonstrates the impact of varied model parameters. The results are compared to operational site data and the modelling errors are quantified. There is good agreement between the models and site data. 2) An expansion on traditional CFD approaches through incorporating machine learning (ML). These ML models are used to approximate the results of the CFD and thereby allow for further analysis which retains the fidelity of CFD at comparatively negligible computational cost. The results are compared to operational site data and the errors at each step are quantified for validation. 3) A time-series forecasting of weather variables based on past measured data. A novel approach for forecasting time-series is developed and compared to two existing methods: Markov-Chains and Gradient Boosting. While this new method is more complex and requires more time to train, it has the desirable feature of incorporating seasonality at multiple timescales and thus providing a more representative time-series. 4) An investigation of the change in modal parameters in an offshore wind jacket structure from damages or from changing operational conditions. In this work the detailed design model of the structure from Ramboll is used. This section relates the measurable modal parameters to the operational condition through a modelling approach. 5) A study conducted using accelerometer data from an Offshore Substation located in a wind farm site. Operational data from 12 accelerometers is used to investigate the efficacy of several potential sensor layouts and therefore to quantify the consequence of placement decisions. The results of these developments are an overall improvement in the modelling approaches necessary towards the realisation of digital twins as well as useful development in each of the component areas. Both areas related to wind loading as well as structural dynamics have been related to operational data. The validation of this link between the measured and the modelled domains facilitates operators and those in maintenance in gaining more information and greater insights into the conditions of their assets.As offshore wind farms grow there is a continued demand for reduced costs. Maintenance costs and downtime can be reduced through greater information on the asset in relation to its operational loads and structural resistance to damage and so there is an increasing interest in digital twin technologies. Through digital twins, an operational asset can be replicated computationally, thus providing more information. Modelling these aspects requires a wide variety of models in different fields. To advance the feasibility of digital twin technology this thesis aims to develop the multi-disciplinary set of modelling domains which help form the basis of future digital twins. Throughout this work, results have been validated against operational data recorded from sensors on offshore structures. This has provided value and confidence to the results as it shows how well the mix of state-of-the art models compare to real world engineering systems. This research presents a portfolio of five research areas which have been published in a mix of peer-reviewed journal articles and conference papers. These areas are: 1) A computational fluid dynamics (CFD) model of an offshore wind farm conducted using a modified solver in the opensource software. This work implements actuator disk turbine models and uses Reynolds averaged Naiver Stokes approaches to represent the turbulence. This investigates the impact of modelling choices and demonstrates the impact of varied model parameters. The results are compared to operational site data and the modelling errors are quantified. There is good agreement between the models and site data. 2) An expansion on traditional CFD approaches through incorporating machine learning (ML). These ML models are used to approximate the results of the CFD and thereby allow for further analysis which retains the fidelity of CFD at comparatively negligible computational cost. The results are compared to operational site data and the errors at each step are quantified for validation. 3) A time-series forecasting of weather variables based on past measured data. A novel approach for forecasting time-series is developed and compared to two existing methods: Markov-Chains and Gradient Boosting. While this new method is more complex and requires more time to train, it has the desirable feature of incorporating seasonality at multiple timescales and thus providing a more representative time-series. 4) An investigation of the change in modal parameters in an offshore wind jacket structure from damages or from changing operational conditions. In this work the detailed design model of the structure from Ramboll is used. This section relates the measurable modal parameters to the operational condition through a modelling approach. 5) A study conducted using accelerometer data from an Offshore Substation located in a wind farm site. Operational data from 12 accelerometers is used to investigate the efficacy of several potential sensor layouts and therefore to quantify the consequence of placement decisions. The results of these developments are an overall improvement in the modelling approaches necessary towards the realisation of digital twins as well as useful development in each of the component areas. Both areas related to wind loading as well as structural dynamics have been related to operational data. The validation of this link between the measured and the modelled domains facilitates operators and those in maintenance in gaining more information and greater insights into the conditions of their assets

Claiming Valhalla: Archaeology, National Identity, and the German-Danish Borderland, 1830-1950

This dissertation traces the emergence of an academic community of archaeologists in the contested German-Danish borderland of Schleswig-Holstein from 1830 to 1950 in order to explore the uses of the distant past for creating modern national identities. The study considers the role of professional scholars in claiming and contesting shared heritages for diverging nationalist ends and explains how scholars handled the paradox of participating in nation-building projects while maintaining their commitments as members of a transnational scholarly community. The study begins in the 1830s with the founding of the Kiel Museum of Antiquities, which was the product of collaboration between German and Danish antiquarians. It then follows the work of antiquarian scholars in the period of the German-Danish Wars from 1848 to 1864, when prehistory became a focal point of claims to territory and led antiquarians to contest the ownership of artifacts such as the Nydam Boat and the Flensburg Collection. In the wake of the wars, the work of scholars such as Johanna Mestorf and Sophus Müller led to a renewal of cross-border collaboration, which resulted in the discovery of the lost Viking trading town of Haithabu and aided the development of a scientific model for the practice of archaeology. The success of research in both countries fostered the production of narratives of prehistory based on scientific methods but tied to national histories. Archaeologists such as Gustaf Kossinna envisioned the borderland as the site of the earliest Germanic peoples and the starting point of Germanic prehistory. The result was a "Nordic paradigm" for prehistoric development with strong racial and imperialist overtones that coexisted with traditional scientific approaches. The dissertation traces the transformation of such thinking in Schleswig-Holstein during the early twentieth century and considers its political implications in the Nazi Era, when the transnational context played a key role in the engagement of borderland scholars with the Third Reich. The study concludes with an appraisal of the fate of nationalist orientations for German and Danish archaeology and the impact of borderland archaeologists on their discipline and their respective national communities

Cost and uncertainty in the design of offshore wind farms

Offshore wind cost modelling seeks to understand and quantify how different project specifications, technology choices and market trends contribute to the overall project finances; linking extensive financial valuation to the engineering design and supporting investment decisions at the initial stages of development. This offers a basis for objective communication and decision-making; allowing for a greater number of cases to be analysed; and when considering new ideas, offering the option to assess the economic feasibility and potential. Cost modelling involves a heavy reliance on models. As models become more realistic, they also become more complex and difficult to understand; especially where model inputs are subjected to sources of uncertainty. The goal of the Engineering Doctorate is to develop new methodologies to optimise the design of offshore wind farms subject to uncertainty, simultaneously considering cost and risk aspects. This thesis describes the methodology of a cost modelling tool to evaluate the financial performance of offshore wind assets, as well as the development, validation and deployment of a framework for quantitative uncertainty management with several applications relevant to the offshore wind industry. This framework is key for risk analysis, producing metrics for the spread of the project performance. However, due to model complexity and input uncertainty, modellers find it difficult to grasp the response of the risk metric to variation in cost drivers based, solely, on intuition. For this reason, global sensitivity analysis is used to identify key cost drivers and neglect the contribution of those that are not relevant. To accomplish this, a toolbox is built to benchmark two techniques: the variance-based and distribution-based method against a set of well-known test functions. This comparison provides new insights on the applicability of the methods. In addition, the application of the framework to the cost modelling tool highlights: key parameters when building financial models for offshore wind farms, guidance on additional efforts towards reducing their uncertainties and recommendations when choosing among global sensitivity analysis techniques. The application of this framework to offshore wind cost modelling equips management with a method to arrive at optimal solutions to complex decision-making problems. For example, it provides a competitive advantage when performing strategic and competitive tender analysis, comparative evaluation of multiple sites, detailed evaluation of specific project layouts and sensitivity studies on both design/technology choices and cost variations. Finally, two techno-economic applications are dealt with in this thesis. While the first one provides a framework to answer the question: does the deployment of additional advanced sensing technology, which presumably reduces wind speed uncertainty, compensate for the incurred development expenditure? The second aims at answering the question: given the fact that most of the time the wind farm is not generating at full power, is there any economic benefit to install additional wind turbines for a given export capacity

Commercialised History: Popular History Magazines in Europe

[EN]This volume of essays is the result of the EU project «EHISTO», which dealt with the mediation of history in popular history magazines and explored how history in the commercialised mass media can be used in history teaching in order to develop the media literacy and the transcultural competences of young people. The volume offers articles which for the first time address the phenomenon of popular history magazines in Europe and their mediating strategies in a foundational way. The articles are intended as introductory material for teachers and student teachers. The topic also offers an innovative approach in terms of making possible a European cross-country comparison, in which results based on qualitative and quantitative methods are presented, related to the content focus areas profiled in the national magazines.This project has been funded with support from the European Commission. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein

Von PISA nach Wien: Historische und politische Kompetenzen in der Unterrichtspraxis. Empirische Befunde aus qualitativen Interviews mit Lehrkräften

How has the competence orientation influenced the practice of teaching and in the beliefs of teachers in the subject History/Social Studies and Citizenship Education? The author conducted and evaluated 50 qualitative interviews with teachers in order to investigate this question.Wie ist die Kompetenzorientierung im Fach Geschichte und Sozialkunde/Politische Bildung in der Praxis des Unterrichts und in den Überzeugungen von Lehrpersonen angekommen? Der Autor hat 50 qualitative Interviews mit in der Praxis stehenden Lehrpersonen durchgeführt und ausgewertet, um dieser Frage nachzugehen

Commercialised History: Popular History Magazines in Europe

This volume of essays is the result of the EU project «EHISTO», which dealt with the mediation of history in popular history magazines and explored how history in the commercialised mass media can be used in history teaching in order to develop the media literacy and the transcultural competences of young people. The volume offers articles which for the first time address the phenomenon of popular history magazines in Europe and their mediating strategies in a foundational way. The articles are intended as introductory material for teachers and student teachers. The topic also offers an innovative approach in terms of making possible a European cross-country comparison, in which results based on qualitative and quantitative methods are presented, related to the content focus areas profiled in the national magazines

A case study of the use of popular history magazines in history teaching in England

The paper reports the outcomes of one strand of the EHISTO Project (http://www.european-crossroads.de). The EHISTO Project is an EU funded collaboration which explores the use of popular history magazines in history education in schools with the aim of developing pupils’ critical and media literacy. The baseline study at the start of the project found that although many history teachers in the five countries involved in the project believed that popular history magazines had the potential to be a useful resource for history teaching, only a minority of teachers made regular use of them in their teaching. The paper looks at attempts to use the EHISTO website to encourage teachers and student teachers to explore the use of popular history magazines in their teaching. The outcomes of the study provide some insight into the potential of popular history magazines as a useful resource in history teaching, the ways in which teachers and student teachers made use of the magazines and the EHISTO website in their teaching. The conclusion also reflects on some of the limitations, problems and mistakes which were made in the execution of the project. There is some evidence to suggest that in spite of these problems, many teachers did find popular history magazines and the EHISTO website to be useful resources and there was a substantial increase in the proportion of teachers and student teachers involved in the study who read and made use of the materials, compared to the outcomes of the baseline study conducted at the start of the study

Exploring Resources. On Cultural, Spatial and Temporal Dimensions of ResourceCultures

This book presents case studies of the SFB 1070 ResourceCultures, which use an extended resource definition. Resources are analysed as contingent means to construct, sustain and alter social relations, units and identities. Accordingly, resources are seen as means of social practices of actors that depend on cultural and social appropriation and valuation. They constitute ResourceCultures. The contributions cover the topics of cross-sectional working groups and conferences that shaped the interdisciplinary collaboration on cultural, spatial and temporal dimensions of resources and ResourceCultures