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Zhao, D. (author), Ferreira, J.A. (author), Roc'h, A. (author), Leferink, F. (author)Filters used in electromagnetic interference suppression are often described in literature on drive systems and have become a standard solution in industry. The effect of the commercial off-the-shelf filter depends significantly on how it is installed. A model that includes the installation parameters is made first and then the parameters of the...journal article 2009
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Zhou, Y. (author), Bauer, P. (author), Ferreira, J.A. (author), Pierik, J. (author)Doubly fed induction generator (DFIG) still shares a large part in today's wind power market. It provides the benefits of variable speed operation cost-effectively, and can control its active and reactive power independently. Crowbar protection is often adopted to protect the rotor-side voltage source converter (VSC) from transient overcurrent...journal article 2009
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- Bang, D. (author), Polinder, H. (author), Shrestha, G. (author), Ferreira, J.A. (author) conference paper 2009
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Shrestha, G. (author), Polinder, H. (author), Bang, D. (author), Jassal, A.K. (author), Ferreira, J.A. (author)A direct drive generator used in wind turbine has high energy yield compared to other drivetrain topologies and low maintenance is expected as the technology matures. On the other hand direct drive generator weight and size increases rapidly when scaled up to larger units. This paper will investigate the possibility of weight reduction of large...conference paper 2009
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Baalbergen, F. (author), Bauer, P. (author), Ferreira, J.A. (author)Diesel generators in small electricity grids are mostly not used in a very efficient way. The reason for this is twofold. First of all, the efficiency of a diesel generator is dependent on the ratio determined by the average power divided by the peak power of the generator. The smaller this ratio is, the lower the efficiency. Furthermore, some...journal article 2009
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Ani, S.O. (author), Polinder, H. (author), Ferreira, J.A. (author), Ockels, W.J. (author)This paper discusses the possibilities of applying high temperature superconducting (HTS) synchronous motor to Superbus, an alternative and sustainable type of public transportation developed at TU Delft. Two important factors within the Superbus drive that influence the operating range are weight and efficiency: increasing the weight results in...conference paper 2009
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Micallef, D. (author), Kloosterman, M. (author), Ferreira, C.S. (author), Sant, T. (author), Van Bussel, G.J.W. (author)The primary objective of the MEXICO (Model Experiments in Controlled Conditions) project was to generate experimental data for validation of models for wind turbines. Kulite©pressure sensors were used for pressure measurements while Particle Image Velocimetry was used with the aim of tracking the tip vortex trajectory. The pressure measurements...conference paper 2010
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Akay, B. (author), Ferreira, C.S. (author), Van Bussel, G.J.W. (author)Several methods from experimental to analytical are used to investigate the aerodynamics of a horizontal axis wind turbine. To understand 3D and rotational effects at the root region of a wind turbine blade, correct modeling of the flow field is essential. Aerodynamic models need to be validated by accurate experimental data. In this paper, the...conference paper 2010
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Ferreira, C. (author), Hofemann, C. (author), Dixon, K. (author), Van Kuik, G.A.M. (author), Van Bussel, G.J.W. (author)The Vertical Axis Wind Turbine, in its 2D form, is characterized by a complex unsteady aerodynamic flow, including dynamic stall and blade vortex interaction. Adding to this complexity, the 3D flow causes spanwise effects and the presence of trailing vorticity and tip vortices. The objective of the current paper is to bring insight into the 3D...conference paper 2010
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Van der Pijl, F.F.A. (author), Ferreira, J.A. (author), Bauer, P. (author), Castilla, M. (author)The invention relates to an adaptive controlling method for controlling energy- supplied by an electrical source (14) to a resonance tank (Cr, Lr) that is connectable to an electric load (13a, 13b). The method comprises the step of determining an energy amount to be supplied to the tank (Cr, Lr), based on information of energy in the resonance...patent 2011
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Akay, B. (author), Micallef, D. (author), Ferreira, C.S. (author), Van Bussel, G.J.W. (author)This paper sets out to describe the measurements and computations to construct three components of velocity field around the blade. The primary aim of the measurements was to gain insight into the physics of the flow field produced by a horizontal axis wind turbine-HAWT blade. Stereo Particle Image Velocimetry experiments were performed on a two...conference paper 2011
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Bijlsma, D. (author), Ferreira, M.A. (author), Luijten, B. (author), Visser, J. (author)We performed an empirical study of the relation between technical quality of software products and the issue resolution performance of their maintainers. In particular, we tested the hypothesis that ratings for source code maintainability, as employed by the Software Improvement Group (SIG) quality model, are correlated with ratings for issue...journal article 2011
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Ferreira, D.S. (author), Mirkovic, J. (author), Wolffenbuttel, R.F. (author), Correia, J.H. (author), Feld, M.S. (author), Minas, G. (author)A strategy for spectroscopy tissue diagnosis using a small number of wavelengths is reported. The feasibility to accurately quantify tissue information using only 16 wavelengths is demonstrated with several wavelength reduction simulations of the existing esophageal data set. These results are an important step for the development of a...journal article 2011
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Weber, J.H. (author), Schouhamer Immink, K.A. (author), Ferreira, H.C. (author)Knuth's celebrated balancing method consists of inverting the first z bits in a binary information sequence, such that the resulting sequence has as many ones as zeroes, and communicating the index z to the receiver through a short balanced prefix. In the proposed method, Knuth's scheme is extended with error-correcting capabilities, where it is...conference paper 2011
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Akay, B. (author), Ferreira, C.S. (author), Van Bussel, G.J.W. (author), Herraez, I. (author)This paper explores the evolution of radial flow in a Horizontal Axis Wind Turbine (HAWT) blade root region. The radial flow is analyzed in the potential flow and viscous flow regions. An experiment carried out by means of stereo Particle Image Velocimetry to measure the velocity field produced by a HAWT blade. While the radial flow in the...conference paper 2012
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Haerens, P. (author), Ciavola, P. (author), Ferreira, O. (author), Van Dongeren, A. (author), Van Koningsveld, M. (author), Bolle, A. (author)Extreme coastal storms have a destructive impact on coastal areas and directly affect people living in the coastal zone, being this emphasized by recent events (e.g. Katrina, Xynthia) which reminded the world of the vulnerability of coastal areas. The economic constraints and the increasing vulnerability of coastal areas (due to sea level rise...conference paper 2012
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Vu Xuan, H. (author), Lahaye, D. (author), Polinder, H. (author), Ferreira, J.A. (author)The use of slotted stator permanent-magnet machines with concentrated windings is increasing in industry. In this paper, the effect of the slot opening on flux linkage, internal voltage, mean torque, rotor eddy current loss and stator iron losses is evaluated. This gives new insight into the influence of slotting on the performance of machines...report 2012
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Ferreira, M.C. (author), Juliao, M.D. (author), Martins, C.J.A.P. (author), Monteiro, A.M.R.V.L. (author)We discuss the usage of measurements of the stability of nature’s fundamental constants coming from comparisons between atomic clocks as a means to constrain coupled variations of these constants in a broad class of unification scenarios. After introducing the phenomenology of these models, we provide updated constraints based on a global...journal article 2012
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Van der Geest, M. (author), Wolmarans, J.J. (author), Polinder, H. (author), Ferreira, J.A. (author), Zeilstra, D. (author)High speed fault tolerant permanent magnet machines have strong asynchronous airgap harmonics, making them susceptible to rotor eddy-current losses. These losses can be reduced by using novel high resistivity materials like plastic bonded magnets and carbon fiber reinforced retaining sleeves. This paper examines by numerical studies the...conference paper 2012
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Ferreira, J. (author), Christiaans, H.H.C.M. (author)This paper presents the first observational study of an ongoing research project. The research focuses on ‘teaching conceptual design’ and on the investigation of new teaching methods and strategies. Presently, in the commonly established educational setting, students practice the role of designing during design exercises while being tutored by...conference paper 2012