Searched for: mods_originInfo_publisher_s%3A%22IOP%255C+Publishing%22
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Doekemeijer, B.M. (author), van Wingerden, J.W. (author), Boersma, S. (author), Pao, L. Y. (author)Wind turbines are often grouped together for financial reasons, but due to wake development this usually results in decreased turbine lifetimes and power capture, and thereby an increased levelized cost of energy (LCOE). Wind farm control aims to minimize this cost by operating turbines at their optimal control settings. Most state-of-the-art...conference paper 2016
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Vali, M. (author), van Wingerden, J.W. (author), Boersma, S. (author), Petrović, V. (author), Kühn, M. (author)This paper proposes an adjoint-based model predictive control for optimal energy extraction of wind farms. It employs the axial induction factor of wind turbines to influence their aerodynamic interactions through the wake. The performance index is defined here as the total power production of the wind farm over a finite prediction horizon. A...conference paper 2016
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Boersma, S. (author), Gebraad, P.M.O. (author), Vali, M. (author), Doekemeijer, B.M. (author), van Wingerden, J.W. (author)In this paper, we present and extend the dynamic medium fidelity control-oriented Wind Farm Simulator (WFSim) model. WFSim resolves flow fields in wind farms in a horizontal, two dimensional plane. It is based on the spatially and temporally discretised two dimensional Navier-Stokes equations and the continuity equation and solves for a...conference paper 2016
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Mulders, S.P. (author), van Solingen, E. (author), van Wingerden, J.W. (author), Beerens, J (author)At present, the cost of offshore wind energy does not meet the level of onshore wind and fossil-based energy sources. One way to extend the turbine lifetime, and thus reduce cost, is by reduction of the fatigue loads of blades and other turbine parts using Individual Pitch Control (IPC). This type of control, which is generally implemented by...conference paper 2016
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Kramers, H.C. (author), van der Valk, P.L.C. (author), van Wingerden, J.W. (author)With the increased need for renewable energy, new offshore wind farms are being developed at an unprecedented scale. However, as the costs of offshore wind energy are still too high, design optimization and new innovations are required for lowering its cost. The design of modern day offshore wind turbines relies on numerical models for...conference paper 2016
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Barlas, T (author), Jost, E. (author), Pirrung, G. (author), Tsiantas, T. (author), Navalkar, S.T. (author), Lutz, T. (author), van Wingerden, J.W. (author)Simulations of a stiff rotor configuration of the DTU 10MW Reference Wind Turbine are performed in order to assess the impact of prescribed flap motion on the aerodynamic loads on a blade sectional and rotor integral level. Results of the engineering models used by DTU (HAWC2), TUDelft (Bladed) and NTUA (hGAST) are compared to the CFD...conference paper 2016
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Rocha, I.B.C.M. (author), Raijmaekers, S (author), Nijssen, RPL (author), van der Meer, F.P. (author), Sluys, Lambertus J. (author)In this work a glass/epoxy composite commonly used in wind turbine blades is exposed to a humid environment at an elevated temperature. To research the anisotropic di_usion behaviour observed in unidirectional composite specimens, experimental results of slices cut along the three directional planes of the laminate immersed in demineralised...conference paper 2016
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Stoop, A.H. (author), Bakker, T.W. (author), Kramer, H.J.M. (author)In several studies the beneficial influence of pre-treatment of waste activated sludge with cavitation on the biogas production was demonstrated. It is however, still not fully certain whether this effect should be mainly contributed to an increase in conversion rate of organics into biogas by anaerobic bacteria, and how much cavitation...conference paper 2015
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Lapeire, L. (author), Sidor, J. (author), Martinez Lombardia, E. (author), Verbeken, K. (author), De Graeve, I. (author), Terryn, H.A. (author), Kestens, L.A.I. (author)Nowadays, there is a considerable scientific interest in bulk ultrafine grained materials, due to their potential for superior mechanical properties. One of the possible formation methods of nano-grained materials is cryogenic rolling. The influence of rolling at cryogenic temperatures has been investigated. Significant differences in the...conference paper 2015
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Ghodrat, S. (author), Pirgazi, H. (author), Kestens, L.A.I. (author)To the purpose of evaluating the effect of deformation on the microstructure, aluminum structures were analyzed on tensile strained samples extended to 25% elongation. In the substructure of these deformed samples linear slip patterns were observed, generally confined to the bulk of the grain. In order to study the crystallographic aspect of...conference paper 2015
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Konijnenberg, A.P. (author), Pereira, S.F. (author)In this paper we present several algorithms to find pupil functions which give focal fields with different desirable properties, such as a laterally elongated spot, a focal sheet, a spot with increased axial resolution, a lateral array of closely packed spots, and a lateral array of widely spaced diffraction-limited spots. All the algorithms...journal article 2015
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Pennings, P.C. (author), Westerweel, J. (author), Van Terwisga, T.J.C. (author)The design of an efficient propeller is limited by the harmful effects of cavitation. The insuffcient understanding of the role of vortex cavitation in noise and vibration reduces the maximum effciency by a necessary safety margin. The aim in the present study is to directly relate propeller cavitation sound to tip vortex cavity dynamics. This...conference paper 2015
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Pirgazi, H. (author), Kestens, L.A.I. (author)Manual serial sectioning which includes consecutive steps of sample preparation and Electron Back Scattering Diffraction (EBSD) measurement was employed to extract the twodimensional (2D) sections of a pure nickel sample and to reconstruct the three-dimensional (3D) microstructure. A general alignment algorithm based on the minimization of...conference paper 2015
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Gomes, E. (author), Kestens, L.A.I. (author)Two new methods, one for determining the experimentally observed Orientation Relationship (OR) and another for reconstructing prior austenite phase, are proposed. Both methods are based on the angular deviation of the OR at the grain boundaries. The first algorithm identifies the optimum OR using the misorientation distribution of the entire...conference paper 2015
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Nguyen-MInh, T. (author), Sidor, J.J. (author), Petrov, R.H. (author), Kestens, L.A.I. (author)Due to progressive deformation, the dislocation densities in crystals are accumulated and the resistance of grains to further deformation increases. Homogeneous deformation becomes energetically less favorable, which may result for some orientations in strain localization. In-grain shear banding, a typical kind of localized deformation in metals...conference paper 2015
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Örley, F. (author), Trummler, T. (author), Hickel, S. (author), Mihatsch, M.S. (author), Schmidt, S.J. (author), Adams, N.A. (author)We present implicit large-eddy simulations (LES) to study the primary breakup of cavitating liquid jets. The considered configuration, which consists of a rectangular nozzle geometry, adopts the setup of a reference experiment for validation. The setup is a generic reproduction of a scaled-up automotive fuel injector. Modelling of all components...conference paper 2015
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Ushakova, K. (author), Van den Berg, Q.Y. (author), Pereira, S.F. (author), Urbach, H.P. (author)Spot size reduction is demonstrated by printing focused spots from amplitude-modulated radially polarized light at the wavelength ? = 405 nm on a photoresist. Amplitude modulation is realized by ring illumination and by application of an optimized amplitude distribution function. Amplitude modulation is implemented via spatial light modulator,...journal article 2015
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Konijnenberg, A.P. (author), Pereira, S.F. (author)In this paper we present several algorithms to find pupil functions which give focal fields with different desirable properties, such as a laterally elongated spot, a focal sheet, a spot with increased axial resolution, a lateral array of closely packed spots, and a lateral array of widely spaced diffraction-limited spots. All the algorithms...journal article 2015
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- Van Kuik, G.A.M. (author), Yu, W. (author), Sarmast, S. (author), Ivanell, S. (author) journal article 2015
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Van Spengen, W.M. (author)In this paper a model is presented that describes the distribution of adhesion values typically experimentally observed for different MEMS devices that have been fabricated in the same way. This spread is attributed to the fact that different devices differ in the details of their surface roughness, even if these surface roughnesses are modeled...journal article 2015
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