The dynamic inflow effect describes the unsteady aerodynamic response to fast changes in rotor loading due to the inertia of the wake. Fast changes in turbine loading due to pitch actuation or rotor speed transients lead to load overshoots. The phenomenon is suspected to be also relevant for gust situations; however, this was never shown, and thus the actual load response is also unknown. The paper’s objectives are to prove and explain the dynamic inflow effect due to gusts, and compare and subsequently improve a typical dynamic inflow engineering model to the measurements. An active grid is used to impress a 1.8m diameter model turbine with rotor uniform gusts of the wind tunnel flow. The influence attributed to the dynamic inflow effect is isolated from the comparison of two experimental cases. Firstly, dynamic measurements of loads and radially resolved axial velocities in the rotor plane during a gust situation are performed. Secondly, corresponding quantities are linearly interpolated for the gust wind speed from lookup tables with steady operational points. Furthermore,simulations with a typical blade element momentum code and a higher-fidelity free-vortex wake model are performed. Both the experiment and higher-fidelity model show a dynamic inflow effect due to gusts in the loads and axial velocities. An amplification of induced velocities causes reduced load amplitudes. Consequently, fatigue loading would be lower. This amplification originates from wake inertia. It is influenced by the coherent gust pushed through the rotor like a turbulent box. The wake is superimposed on that coherent gust box, and thus the inertia of the wake and consequently also the flow in the rotor plane is affected. Contemporary dynamic inflow models inherently assume a constant wind velocity. They filter the induced velocity and thus cannot predict the observed amplification of the induced velocity. The commonly used Øye engineering model predicts increased gust load amplitudes and thus higher fatigue loads. With an extra filter term on the quasi-steady wind velocity, the qualitative behaviour observed experimentally and numerically can be caught. In conclusion, these new experimental findings on dynamic inflow due to gusts and improvements to the Øye model enable improvements in wind turbine design by less conservative fatigue loads.
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The dynamic inflow effect denotes the unsteady aerodynamic response to fast changes in rotor loading due to a gradual adaption of the wake. This does lead to load overshoots. The objective of the paper was to increase the understanding of that effect based on pitch step experiments on a 1.8 m diameter model wind turbine, which are performed in the large open jet wind tunnel of ForWind – University of Oldenburg. The flow in the rotor plane is measured with a 2D laser Doppler anemometer, and the dynamic wake induction factor transients in axial and tangential direction are extracted. Further, integral load measurements with strain gauges and hot-wire measurements in the near and close far wake are performed. The results show a clear gradual decay of the axial induction factors after a pitch step, giving the first direct experimental evidence of dynamic inflow due to pitch steps. Two engineering models are fitted to the induction factor transients to further investigate the relevant time constants of the dynamic inflow process. The radial dependency of the axial induction time constants as well as the dependency on the pitch direction is discussed. It is confirmed that the nature of the dynamic inflow decay is better described by two rather than only one time constant. The dynamic changes in wake radius are connected to the radial dependency of the axial induction transients. In conclusion, the comparative discussion of inductions, wake deployment and loads facilitate an improved physical understanding of the dynamic inflow process for wind turbines. Furthermore, these measurements provide a new detailed validation case for dynamic inflow models and other types of simulations.
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Dynamic inflow effects occur due to the rapid change of the rotor loading underconditions such as fast pitch steps. The paper presents a setup suitable for the investigation ofthose effects for non-axisymmetric rotor conditions, namely individual pitch steps. Furthermore, insights into the relevant phenomena are gathered. An individual pitch control capable model wind turbine is set up in a wind tunnel in order to conduct measurement under controllable conditions. During the execution of the collective and individual pitch steps, the loads and the operational parameters are recorded by the onboard sensors. Meanwhile, simulations engineering aeroelastic codes are run in order to evaluate their accuracy for predicting the relevant phenomena. Results show distinct behaviour of the rotor loads during an individual pitch step, which differs from the loads under collective steps. The free vortex wake simulations are able to predict the turbines’ response satisfactory while the blade element momentum tools show deviations from the measurements. The findings serve as a basis for discussion and future work.
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Electrohydrodynamic atomization (EHDA) is a technique which uses the influence of strong electric fields to manipulate the break-up of a liquid, pumped through a capillary nozzle, into droplets. In this work, an extended description of a specific high flow EHDA mode, known as the simple-jet mode, is presented. In it, a review of different works published about the mode is presented as well as results about the droplet population generated with varicose and whipping break-up using water as the atomized liquid. Additionally, experiments were conducted to investigate whether such atomization method could be used to improve the efficiency of droplet inair evaporation, using a single effect evaporation chamber coupled with a EHDA multinozzle system functioning as a shower head. The liquid used in these experiments was a solution of water and NaCl (35 g L−1) to simulate sea water average concentrations. The results have shown that, the manipulation of the droplet diameter, droplet size distribution and spray angle, provided by EHDA, could improve the droplet evaporation efficiency by up to 40% when combinedwith, e.g. forced convection and higher inlet temperatures.
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This report maps different programs that supportrefugees on the road to entrepreneurship. The municipality of The Hague, along with the refugee and migrant support organization EnterStart (MigrantINC) asked for an evaluation of the program The Hague Test Garden (from now on called The Test Garden) where refugees can ask for help starting their own businesses. The evaluation is not just based on the experiences in The Test Garden; other programs have been included in the evaluation to come to a broader view of the road to entrepreneurship and the obstacles encountered. The increased inflow of refugees in Dutch society and on the Dutch labor market has generated different support programs for starting-up a business. Some of these programs already existed but shifted to accommodate the needs of this specific target group. Other programs were initiated to support refugees because of perceived barriers in Dutch society. Most programs are private initiatives, funded on a project basis. In the Netherlands, refugees that hold a residence permit are called ‘status holders’. Upon arrival, they received a temporary permit for at least five years. They need to follow a civic integration and language program and they are expected to be part of the (regular) education system or labor market as soon as possible. The Test Garden started in 2016, a time when multiple support systems for refugee-entrepreneurs began their programs. This report starts with a short overview ofrefugee flows to the Netherlands. The main part of the report consists of the comparison and evaluation of the different programs. The information was gathered through literature, websites, and in-depth interviews with program managers and others involved. Interviews with the participants are only included for The Test Garden (Appendix 1 gives an overview of the meetings and interviews). LinkedIn: https://www.linkedin.com/in/karijn-nijhoff-89589316/
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This paper seeks to contribute to sustainable business model innovation (SBMI) literature. It aims to do so by putting forward a relatively simple tool that simultaneously calculates the financial value alongside sustainability impact based on the Sustainable Development Goals (SDGs) of a proposed business model innovation. For small businesses to validate the outcome of a proposed SBMI, some form of sustainability measurement will be necessary. Simple tooling specifically aimed at small businesses do not exist. We address this gap in how to predict or create a prognosis of the combined financial and sustainability effect of a proposed business model (BM) in a frugal (easy, time and knowledge effective) and effectual (allowing for iterations, available means and calculating affordable loss) manner. The tool is called the Pos-FSBC (Positive Financial and Sustainability Business Case). The instrument is a calculation model in Excel where users insert a limited number of numerical variables. Alongside financial variables the tool uniquely links the key variable ∆ SDG to the expected quantity sold, it then calculates the contribution to the SDGs in a relevant and measurable unit. By being successful with a sustainable innovation, the tool helps businesses drive out nonsustainable competitors. The tool has been iteratively developed and tested in several students’ projects and in a pilot with practitioners. Based on the findings we propose more iterations to develop an understanding whether the tool inspires business change and if so how.
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This paper presents the results of an exercise to assess the effects of metaphors on knowledge management. Knowledge is an abstract phenomenon with no direct referent in the real world. To think and talk about knowledge we use conceptual metaphors. The exercise shows that these metaphors greatly influence the problems we identify related to knowledge in organizations and the type of knowledge management solutions we propose. The knowledge as water metaphor used in this exercise – which reflects the dominant way of thinking in Western knowledge management literature – leads to the thingification of knowledge, resulting in a discourse about ways to formalize, manage and control knowledge. This discourse primarily serves the interests of management. In contrast, the knowledge as love metaphor used in this exercise – which reflects more an Asian way of thinking about knowledge – shifts the discourse from the topic of knowledge as a thing to the underlying preconditions for good knowledge work. These conditions include the facilitation of knowledge professionals, the quality of the relationships in the organization, and the quality of the organizational culture. This discourse is aimed at humanizing the organization instead of formalizing it and is more in the interest of employees.
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Most European countries have to find a delicate balance between long term economic reform and short term impact on GDP.
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Network Applied Design Research (NADR) made an inventory of the current state of Circular Design Research in the Netherlands. In this publication, readers will find a summary of six promising ‘gateways to circularity’ that may serve as entry points for future research initiatives. These six gateways are: Looped Systems; Extension of Useful Lifetime; Servitisation; New Materials and Production Techniques; Information Technology and Digitization; and Creating Public and Industry Awareness. The final chapter offers an outlook into topics that require more profound examination. The NADR hopes that this publication will serve as a starting point for discussions among designers, entrepreneurs, and researchers, with the goal of initiating future collaborative projects. It is the NADR's belief that only through intensive international cooperation, we can contribute to the realization of a sustainable, circular, and habitable world.
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Deze agenda is een strategisch kader voor human capitalontwikkelingen in de creatieve industrie in de Metropoolregio Amsterdam voor de komende vier jaar (2012-2016). De agenda bestrijkt de gehele breedte van de creatieve industrie en richt zich op een interdisciplinaire aanpak en op het stimuleren van een onderzoekende en ondernemende cultuur in het onderwijs. Leidende thema’s zijn: • onderwijs over ondernemerschap;; • vraag en aanbod op elkaar afstemmen;; • alumni & permanente educatie;; • internationalisering. De Creatieve Industrie is de belangrijkste top sector voor de Metropoolregio Amsterdam (CBS monitor topsectoren 2012). Voor de beschrijving van de Creatieve Industrie in de Metropoolregio is een benadering vanuit drie clusters aangehouden: Kunsten & Cultureel Erfgoed, Media & Entertainment, Creatieve Zakelijke Diensten (reclame, mode vormgeving, architectuur). Het Kernteam Creatieve Industrie MRA wil een belangrijke bijdrage leveren aan de Europese en landelijke ambitie om Nederland in 2020 de meest creatieve economie van Europa te laten zijn. Dit vraagt om continue innovatie, slimme en creatieve oplossingen. Daarvoor is slim, creatief, jong (top)talent onmisbaar. Bij deze ambitie hoort een naadloze verbinding en samenwerking tussen bedrijfsleven en kennis- en onderwijsinstellingen. Het concurrerende klimaat, dynamiek en tempo in de sector vragen om snelle toepassing van nieuwe kennis en technologie en om een voortdurende instroom van nieuw (internationaal) creatief (top)talent en permanente bijscholing. Naast een economische waarde heeft de creatieve sector ook een maatschappelijk toegevoegde waarde. Met name de subsector Kunsten & Cultureel Erfgoed bevordert, met een vaak cross-sectorele aanpak, participatie en cohesie van diverse groepen in de samenleving. De toegevoegde waarde van de creatieve industrie wordt door andere sectoren nog onvoldoende op waarde geschat en benut. Voor professionals en aankomend talent is het cruciaal dat zij de juiste kennis en vaardigheden ontwikkelen om de meerwaarde en identiteit van de creatieve industrie over het voetlicht te brengen. De ondertekenaars van deze HCA hebben de intentie de ingezette samenwerking nog concreter vorm te geven. Het Centre of Expertise, Centrum voor Innovatief Vakmanschap en de Amsterdam Campus zijn hierbij dé vehikels om concrete afspraken en projecten tussen de drie partijen uit de gouden driehoek te realiseren. Prioriteit hierbij is de vraagarticulatie vanuit het bedrijfsleven verder aan te scherpen, afspraken hierover tussen partijen zijn reeds gemaakt. AIM wordt gevraagd twee per jaar een bijeenkomst te organiseren om concrete acties met elkaar te benoemen. Deze HCA, met bijbehorende ambitie en invulling, zal dan ook jaarlijks door het Kernteam geëvalueerd en zo nodig bijgesteld worden. Hierbij blijft afstemming met de MRA –agenda’s: HCA ICT en HCA Toerisme en Congressen gewenst.
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