Robust and fast schemes in broadband active noise and vibration control

This thesis presents robust and fast active control algorithms for the suppression of broadband noise and vibration disturbances. Noise disturbances, e.g., generated by engines in airplanes and cars or by air ow, can be reduced by means of passive or active methods

Blockwise Subspace Identification for Active Noise Control

In this paper, a subspace identification solution is provided for active noise control (ANC) problems. The solution is related to so-called block updating methods, where instead of updating the (feedforward) controller on a sample by sample base, it is updated each time based on a block of N samples. The use of the subspace identification based ANC methods enables non-iterative derivation and updating of MIMO compact state space models for the controller. The robustness property of subspace identification methods forms the basis of an accurate model updating mechanism, using small size data batches. The design of a feedforward controller via the proposed approach is illustrated for an acoustic duct benchmark problem, supplied by TNO Institute of Applied Physics (TNO-TPD), the Netherlands. We also show how to cope with intrinsic feedback. A comparison study with various ANC schemes, such as block filtered-U, demonstrates the increased robustness of a subspace derived controlle

Extremely fast focal-plane wavefront sensing for extreme adaptive optics

We present a promising approach to the extremely fast sensing and correction of small wavefront errors in adaptive optics systems. As our algorithm's computational complexity is roughly proportional to the number of actuators, it is particularly suitable to systems with 10,000 to 100,000 actuators. Our approach is based on sequential phase diversity and simple relations between the point-spread function and the wavefront error in the case of small aberrations. The particular choice of phase diversity, introduced by the deformable mirror itself, minimizes the wavefront error as well as the computational complexity. The method is well suited for high-contrast astronomical imaging of point sources such as the direct detection and characterization of exoplanets around stars, and it works even in the presence of a coronagraph that suppresses the diffraction pattern. The accompanying paper in these proceedings by Korkiakoski et al. describes the performance of the algorithm using numerical simulations and laboratory tests.Comment: SPIE Paper 8447-7

Het einde van het monisme

Het rapport van de Commissie van Thijn is uit en het pleit voor een gekozen burgemeester, maar is dit zo werkelijk een oplossing voor de huidige problematiek, of moet er meer gebeuren

Eerst de Tweede Kamer

Door het optreden van de Eerste Kamer-fractie van het CDA is de Senaat in opspraak gekomen. Met name fractievoorzitter Kaland en senator prof. Boorsma (bestuurskundige in Twente) werpen zich op als beschermers van de democratie: indien de Tweede Kamer verzaakt haar controlefunctie uit te oefenen, dan moet de Eerste Kamer die overnemen. Ondertussen gaan er stemmen op juist de Eerste Kamer op te heffen. Kaland wil echter van geen wijken weten

Optimal and Robust Feedback Controller Estimation for a Vibrating Plate using Subspace Model Identification

This paper presents a method to estimate the H2 optimal and a robust feedback controller by means of Subspace Model Identification using the internal model control (IMC) approach. Using IMC an equivalent feed forward control problem is obtained, which is solved by the Causal Wiener filter for the H2 optimal controller. The robust variant, called the Cautious Wiener filter, optimizes the average performance w.r.t. probabilistic model errors. The identification of the Causal and Cautious Wiener filters are control-relevant. The method is illustrated by experiments on a 4-inputs 4-outputs vibrating plate with additional mass variation

De beste, maar niet goed genoeg

Effective Protection of Fundamental Rights in a pluralist worl