Resonating structures with flapping wings: numerical modelling and validation

Tiny flying platforms with a wingspan of up to 20 centimetres are build to mimic flying insects: Flapping Wing Micro Air Vehicles (FWMAVs). Flying insects have the required size and also their flying capabilities are highly interesting. In order to maximize the energy efficiency of a FWMAV, the vehicle is usually driven in one of the resonance frequencies of the total system. The aerodynamic damping, due to the flapping of the wings, has influence on the resonance response. To control the dynamic behaviour of the system, local structural changes can be used. The influence of local structural changes on the dynamic behaviour of FWMAVs is studied in this project using a numerical model. The model consists out of a structural dynamics and an aerodynamics part. A co-rotational formulation is used to model the structural dynamics. The scope of this project is limited to two-dimensionally moving structures, which greatly reduces the complexity of the structural dynamics. The structural model shows excellent accuracy compared to an analytical expression: a difference of less than a half percent is found for a sufficient number of element to model the structure. The aerodynamics are modelled using a purely analytical model, which allows the use of arbitrary wingshapes. The aerodynamic loads are applied as external forces on the system. The time-integration is done using an elegant adaptation of the popular Newmark method, which introduces numerical damping while accuracy is maintained. The numerical model is applied on a simple example consisting out a ring structure where wings are attached to using compliant hinges. The influence of thickness changes of the compliant hinges on the performance is studied. It is found that a thickness increase of the compliant hinge of 4.6% results in a mean lift force increase of 24%. Also the stiffness of the spring which influences the pitching angle of the wing, is found to have a large influence on the mean lift force: differences up to 83% are found. Both findings indicate that local structural changes can be used to change the lift of the wings and thereby be used to control the dynamic behaviour. Furthermore, it shows that the tuning of the components of a FWMAV is a delicate matter and a small structural change can have a significant influence on the performance of such vehicle.Mechanical, Maritime and Materials EngineeringPrecision and Microsystems Engineerin

Teaching journalistic research skills in the digital age: Between traditional routines and advanced tools

The content of most journalism courses at journalism schools has been affected by the fast digital and interactive developments in the field. The changing digital organization of information and sources necessitates constant changes in news-gathering and research techniques and affects education in research skills. How can educators cope with the new demands concerning information gathering and selecting? Journalism students need to know how to use the newest research tools, how to find quick and reliable information and data on the Internet and how to best utilize social media for their journalistic research. Which research skills need to be taught to journalism students in this digital age? This article attempts to map the salient issues concerning changes in the syllabi of research skills courses by analysing scholarly literature, blogs and books by professional journalists and experiences at the – author’s – School of Journalism in Utrecht (the Netherlands) with the implementation of newly designed research courses. It is argued that digital developments have caused a shift from the information-gathering stage to the selecting stage of the research process in journalism. This implies more emphasis on evaluating and selecting skills in journalism education. New digital tools also require different research skills such as more language skills for more efficient search strategies. New digital sources, such as open data and the public on social media, call for more analytical skills and specific social skills to be added to the customary research skills

Distributed optimization for the exploitation of multi-energy flexibility under uncertainty in city districts

This dissertation centers on distributed optimization for the achievement of the electrical balance of demand and supply of an aggregator on a local distribution level. The distributed optimization techniques perform almost equally to central benchmark algorithms but, compared to a non-optimized scenario, achieve a significant flexibility exploitation. In case of heterogeneous customer and aggregator objectives, the results prove that there is a relevant trade-off. Both the customers and the aggregator can still though achieve a metric improvement. Uncertainty affects the aggregator´s portfolio balancing. Thus, this dissertation investigates the potential of robust optimization with model predictive control for a robust portfolio. The results demonstrate a reduction of the adjustments that could otherwise lead to significant imbalances for the balance responsible party and simultaneously minimize the total costs of the system. Furthermore, this dissertation describes a portfolio optimization of an aggregator as a two-stage stochastic optimization. The computational effort of stochastic optimization is only worthwhile for specific days in the year. A large spread and probability distribution of the first stage day-ahead prices as well as low presence of flexibility characterize these days. Additionally, this dissertation provides a novel customer-centric approach for flexibility exploitation of electro-thermal heating systems. The approximate differentiation method, an inverse simulation technique, turns the customer´s thermal comfort specifications into technical power profile values that are most relevant for the flexibility user

Changing Journalistic Information-Gathering Practices?: Reliability in Everyday Information Gathering in High-Speed Newsrooms

This study explores how journalists in highspeed newsrooms gather information, how gathering activities are temporally structured and how reliability manifests itself in information-gathering activities

Nederlandse journalisten: niet checken maar indekken

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Sharing similarities and discussing differences: How Utrecht’s international journalism students cross cultural borders

The Utrecht School of Journalism has a long tradition in international higher education. The School’s European Culture & European Journalism (ED&EJ) programme is an example of a pedagogical practice in higher education where advanced students learn how to perform in an international context. Journalism students from Moscow to Ottawa and from Helsinki to Bilbao learn alongside Dutch students. It is not only the content of the programme and the reporting for the Web Magazine that makes the EC&EJ programme an inspirational educational experience. The programme demonstrates the importance of sharing different professional and cultural values. This sharing and confronting of professional standards contributes to an important new qualification for all higher educated professionals: awareness of cultural differences and similaritie

To check or not to check? An exploratory study on source checking by Dutch journalists.: [Preprint version]

Verifying information is one of the core activities of journalism. However, recent research shows that many stories derive from unchecked information from news agencies and PR material. That being said, reporters who do not use this pre-packaged material, but who instead produce original stories based on independent research, might be journalists who stay devoted to the verification of information. Therefore, this study focuses on in-depth stories that originated inside the newsroom. We expected that these kinds of stories would be checked and double-checked, because time constraints are less important and these stories are characteristic of independent, quality journalism. Contrary to this expectation, the results show that even these kinds of stories are not always vetted. The lack of time was seldom mentioned as an excuse. Our research points to avoidance mechanisms which inhibit journalists from verifying their information