Dynamic stall phenomena bring risk for negative damping and instability in wind turbine blades. It is crucial to model these phenomena accurately to reduce inaccuracies in predicting design driving (fatigue) loads. Inaccuracies in currentdynamic stall models may be due to the facts that they are not properly designed for high angles of attack, and that they do not 10 specifically describe vortex shedding behaviour. The Snel second order dynamic stall model attempts to explicitly model unsteady vortex shedding. This model could therefore be a valuable addition to DNV GL’s turbine design software Bladed. In this thesis the model has been validated with oscillating airfoil experiments and improvements have been proposed for reducing inaccuracies. The proposed changes led to an overall reduction in error between the model and experimental data. Furthermore the vibration frequency prediction improved significantly. The improved model has been implemented in Bladed and tested 15 against small scale turbine experiments at parked conditions. At high angles of attack the model looks promising for reducing mismatches between predicated and measured (fatigue) loading. Leading to possible lower safety factors for design and more cost efficient designs for future wind turbines.
Dynamic stall phenomena carry the risk of negative damping and instability in wind turbine blades. It is crucial to model these phenomena accurately to reduce inaccuracies in predicting design driving (fatigue and extreme) loads. Some of the inaccuracies in current dynamic stall models may be due to the fact that they are not properly designed for high angles of attack and that they do not specifically describe vortex shedding behaviour. The Snel second-order dynamic stall model attempts to explicitly model unsteady vortex shedding. This model could therefore be a valuable addition to a turbine design software such as Bladed. In this paper the model has been validated with oscillating aerofoil experiments, and improvements have been proposed for reducing inaccuracies. The proposed changes led to an overall reduction in error between the model and experimental data. Furthermore the vibration frequency prediction improved significantly. The improved model has been implemented in Bladed and tested against small-scale turbine experiments at parked conditions. At high angles of attack the model looks promising for reducing mismatches between predicted and measured (fatigue and extreme) loading, leading to possible lower safety factors for design and more cost-efficient designs for future wind turbines.
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Crime script analysis as a methodology to analyse criminal processes is underdeveloped. This is apparent from the various approaches in which scholars apply crime scripting and present their cybercrime scripts. The plethora of scripting methods raise significant concerns about the reliability and validity of these scripting studies. In this methodological paper, we demonstrate how object-oriented modelling (OOM) could address some of the currently identified methodological issues, thereby refining crime script analysis. More specifically, we suggest to visualise crime scripts using static and dynamic modelling with the Unified Modelling Language (UML) to harmonise cybercrime scripts without compromising their depth. Static models visualise objects in a system or process, their attributes and their relationships. Dynamic models visualise actions and interactions during a process. Creating these models in addition to the typical textual narrative could aid analysts to more systematically consider, organise and relate key aspects of crime scripts. In turn, this approach might, amongst others, facilitate alternative ways of identifying intervention measures, theorising about offender decision-making, and an improved shared understanding of the crime phenomenon analysed. We illustrate the application of these models with a phishing script.
MULTIFILE
The COVID19 pandemic highlighted the vulnerability in supply chain networks in the healthcare sector and the tremendous waste problem of disposable healthcare products, such as isolation gowns. Single-use disposable isolation gowns cause great ecological impact. Reusable gowns can potentially reduce climate impacts and improve the resilience of healthcare systems by ensuring a steady supply in times of high demand. However, scaling reusable, circular isolation gowns in healthcare organizations is not straightforward. It is impeded by economic barriers – such as servicing costs for each use – and logistic and hygiene barriers, as processes for transport, storage and safety need to be (re)designed. Healthcare professionals (e.g. purchasing managers) lack complete information about social, economic and ecological costs, the true cost of products, to make informed circular purchasing decisions. Additionally, the residual value of materials recovered from circular products is overlooked and should be factored into purchasing decisions. To facilitate the transition to circular procurement in healthcare, purchasing managers need more fine-grained, dynamic information on true costs. Our RAAK Publiek proposal (MODLI) addresses a problem that purchasing managers face – making purchasing decisions that factor in social, economic and ecological costs and future benefits from recovered materials. Building on an existing consortium that developed a reusable and recyclable isolation gown, we design and develop an open-source decision-support tool to inform circular procurement in healthcare organizations and simulate various purchasing options of non-circular and circular products, including products from circular cascades. Circular procurement is considered a key driver in the transition to a circular economy as it contributes to closing energy and material loops and minimizes negative impacts and waste throughout entire product lifecycles. MODLI aims to support circular procurement policies in healthcare organizations by providing dynamic information for circular procurement decision making.
The Ph.D. candidate will investigate the seismic response of connection details frequently used in traditional Dutch construction practice, specifically in the Groningen area. The research will focus on the experimental and numerical definition of the complete load-deflection behaviour of each considered connection; specifically, the tests will aim at identifying stiffness, strength, ductility, and dissipative behaviour of the connections. The experiments will be conducted on scaled or full-scale components that properly resemble the as-built and retrofitted as well connection details. The tests will involve monotonic and cyclic loading protocols to be able to define the load and displacement response of the connection to reversal loads, such as earthquakes, as well as the development of failure mechanisms under such loading cases. Possibly, also dynamic tests will be performed. Numerical models will be created and calibrated versus the experimental findings. Characteristic hysteretic behaviours of the examined connection types will be provided for the use of engineers and researchers.
