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Experimental analysis of radially resolved dynamic inflow effects due to pitch steps

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.

Dynamic lighting systems in psychogeriatric care facilities in The Netherlands

Long-term care facilities are currently installing dynamic lighting systems with the aim to improve the well-being and behaviour of residents with dementia. The aim of this study was to investigate the implementation of dynamic lighting systems from the perspective of stakeholders and the performance of the technology. Therefore, a questionnaire survey was conducted with the management and care professionals of six care facilities. Moreover, light measurements were conducted in order to describe the exposure of residents to lighting. The results showed that the main reason for purchasing dynamic lighting systems lied in the assumption that the well-being and day/night rhythmicity of residents could be improved. The majority of care professionals were not aware of the reasons why dynamic lighting systems were installed. Despite positive subjective ratings of the dynamic lighting systems, no data were collected by the organizations to evaluate the effectiveness of the lighting. Although the care professionals stated that they did not see any large positive effects of the dynamic lighting systems on the residents and their own work situation, the majority appreciated the dynamic lighting systems more than the old situation. The light values measured in the care facilities did not exceed the minimum threshold values reported in the literature. Therefore, it seems illogical that the dynamic lighting systems installed in the researched care facilities will have any positive health effects.

The Relational Dimension of Radicalization: Context and Tie Formation in Dutch Salafi-Jihadi Networks

Despite the widely held notion that processes of radicalization tend to happen in relation to others, systematic evidence on the social context in which actors meet and form ties is scarce. This is problematic, as without a more thorough understanding of the relational dimension of radicalization, any strategy to intervene may turn out less effective than perhaps hoped for. Based on our access to detailed police information on eleven Dutch Salafi-Jihadi networks (2001–2014; 273 actors), this article presents a descriptive analysis of the social context in which actors meet and form ties. In most networks, we observe pre-existing family and friendship ties, actors to frequent Salafi mosques and radicalizing settings, and committed actors engaged in functional roles. We also find indications for these elements to facilitate actors to form ties. It is important to note however that we also observe exceptions, both in terms of prevalence and impact of the relational factors we study. In the article, we describe our detailed empirical findings and reflect on the (differential) social context is which actors participating in Dutch Salafi-Jihadi networks meet and form ties.

Application of a dynamic energy budget model to Mytilus edulis (L.)

A dynamic courtship

The Salvation Army has been battling social problems in the Netherlands for more than 125 years. Over the course of this period, the Dutch Salvation Army has developed into a well-known faith-based organization as well as an important professional social service provider. These two characteristics: religious work and social work, are regarded by the Army as essential to its identity, and are considered distinct but in – separable. However, as this study shows, during much of the Army’s history this bilateral character created an inescapable field of tension. This became explicitly clear with the development of the Dutch social policy system during the twentieth century, when the evolving relationship between the Salvation Army and the Dutch government created certain problems for both actors. How would the government cooperate with a valued social service provider that had an explicit faith-based identity? And on the other hand, how did the Army cope with this relationship in relation to its identity? The work presented in this thesis was supported by the University of Applied Sciences Utrecht (HU) and the VU University Amsterdam.

Rethinking dynamic fabric through wearing and designing