Compressible Dynamic Stall Control using a Variable Droop Leading Edge Airfoil

(AIAA Paper 2003-0048), Journal of Aircraft, Vol. 41, No. 4, pp. 862-969, Jul. - Aug. 2004.The control of compressible dynamic stall using a variable droop leading edge airfoil is described. The leading 25% of a VR-12 airfoil is drooped as it executes sinusoidal pitch oscillations such that the leading portion of the airfoil is always at a low effective incidence to the flow. Airfoil performance data determined for freestream Mach numbers ranging from 0.2 to 0.4, at reduced frequencies from 0 to 0.1, and using unsteady pressure transducer measurements, show that droop reduces the tendency of the airfoil to enter the dynamic stall state. Even when it does, the strength of the dynamic stall vortex is significantly reduced, which is reflected in the 40 to 50% smaller negative peak pitching-moment values, with positive damping of the airfoil. Also, the airfoil drag when the droop is dynamically varied is reduced by up to 75% relative to a nondrooped airfoil, making a strong case for the use of this concept for dynamic stall control.U.S. Army Research Offic

Bragg spectroscopy with an accelerating Bose-Einstein condensate

We present the results of Bragg spectroscopy performed on an accelerating Bose-Einstein condensate. The Bose condensate undergoes circular micro-motion in a magnetic TOP trap and the effect of this motion on the Bragg spectrum is analyzed. A simple frequency modulation model is used to interpret the observed complex structure, and broadening effects are considered using numerical solutions to the Gross-Pitaevskii equation.Comment: 5 pages, 3 figures, to appear in PRA. Minor changes to text and fig

Systeemtoezicht in de Nederlandse gezondheidszorg. Een experimentele innovatie van toezicht.

__Abstract__ Al jaren wordt nagedacht over de vraag in hoeverre zorginstellingen zelf in staat zijn om te waarborgen dat zij verantwoorde zorg leveren (lees: veilige en kwalitatief goede zorg). Er is wetgeving die voorschrijft dat zorginstellingen alleen kunnen worden toegelaten als zij een aantal organisatorische zaken op orde hebben.1 In 1996 is in de Kwaliteitswet geregeld dat zorginstellingen zelf de kwaliteit van de zorg systematisch moeten bewaken, beheersen en verbeteren. Bestuurders en raden van toezicht zijn in eerste instantie zelf verantwoordelijk voor de kwaliteit van zorg in hun instelling, waarbij zij zorgdragen voor passende procedures en cultuur. De veronderstelling is dat als zorginstellingen deze verantwoordelijkheid opnemen en daadwerkelijk waarmaken, het publieke toezicht op de naleving beperkt kan worden tot toezicht op (de werking van) het zelf opgezette ‘systeem’ om kwaliteit en veiligheid te borgen en risico’s te beheersen. Deze manier van inspecteren wordt in Nederland systeemtoezicht (ST) genoemd. De vragen die we in dit artikel willen beantwoorden zijn waarom en hoe ST aan de toezichtmethoden van de Inspectie voor de Gezondheidszorg (IGZ) toegevoegd zou kunnen worden

Interacting dark matter contribution to the Galactic 511 keV gamma ray emission: constraining the morphology with INTEGRAL/SPI observations

We compare the full-sky morphology of the 511 keV gamma ray excess measured by the INTEGRAL/SPI experiment to predictions of models based on dark matter (DM) scatterings that produce low-energy positrons: either MeV-scale DM that annihilates directly into e+e- pairs, or heavy DM that inelastically scatters into an excited state (XDM) followed by decay into e+e- and the ground state.By direct comparison to the data, we find that such explanations are consistent with dark matter halo profiles predicted by numerical many-body simulations for a Milky Way-like galaxy. Our results favor an Einasto profile over the cuspier NFW distribution and exclude decaying dark matter scenarios whose predicted spatial distribution is too broad. We obtain a good fit to the shape of the signal using six fewer degrees of freedom than previous empirical fits to the 511 keV data. We find that the ratio of flux at Earth from the galactic bulge to that of the disk is between 1.9 and 2.4, taking into account that 73% of the disk contribution may be attributed to the beta decay of radioactive 26Al.Comment: 7 pages, 4 figures. Includes minor corrections, and a discussion of threshold energies in XDM models. Published in JCA

Accuracy of the recombination correction factor (ks) in FFF beams for three ion chamber types

Flattening filter free (FFF) beams pose particular considerations for absolute dosimetry. • These beams are capable to deliver high doses per pulse (DPP) which implies special consideration regarding recombination effects in ionization chambers. • We wanted to know which type of ionization chamber (Farmer, Semiflex or Pinpoint) would be more appropriate for commisioning our new FFF beam

Chiral Dynamics and the Low Energy Kaon-Nucleon Interaction

We examine the meson-baryon interaction in the strangeness S=-1 sector using an effective chiral Lagrangian. Potentials are derived from this Lagrangian and used in a coupled-channel calculation of the low energy observables. The potentials are constructed such that in the Born approximation the s-wave scattering amplitude is the same as that given by the effective chiral Lagrangian, up to order $q^2$. Comparison is made with the available low energy hadronic data of the coupled $K^-p, \Sigma \pi, \Lambda \pi$ system, which includes the $\Lambda (1405)$ resonance, $K^-p$ elastic and inelastic scattering, and the threshold branching ratios of the $K^-p$ decay. Good fits to the experimental data and estimates of previously unknown Lagrangian parameters are obtained.Comment: 20 pages, 10 postscript figures, uses revtex, e-mail addresses: [email protected], [email protected], [email protected]

Renormalization of the asymptotically expanded Yang-Mills spectral action

We study renormalizability aspects of the spectral action for the Yang-Mills system on a flat 4-dimensional background manifold, focusing on its asymptotic expansion. Interpreting the latter as a higher-derivative gauge theory, a power-counting argument shows that it is superrenormalizable. We determine the counterterms at one-loop using zeta function regularization in a background field gauge and establish their gauge invariance. Consequently, the corresponding field theory can be renormalized by a simple shift of the spectral function appearing in the spectral action. This manuscript provides more details than the shorter companion paper, where we have used a (formal) quantum action principle to arrive at gauge invariance of the counterterms. Here, we give in addition an explicit expression for the gauge propagator and compare to recent results in the literature.Comment: 28 pages; revised version. To appear in CMP. arXiv admin note: substantial text overlap with arXiv:1101.480

Initial State Interactions for K−K^--Proton Radiative Capture

The effects of the initial state interactions on the $K^--p$ radiative capture branching ratios are examined and found to be quite sizable. A general coupled-channel formalism for both strong and electromagnetic channels using a particle basis is presented, and applied to all the low energy $K^--p$ data with the exception of the {\it 1s} atomic level shift. Satisfactory fits are obtained using vertex coupling constants for the electromagnetic channels that are close to their expected SU(3) values.Comment: 16 pages, uses revte

Three-Body approach to the K^- d Scattering Length in Particle Basis

We report on the first calculation of the scattering length A_{K^-d} based on a relativistic three-body approach where the two-body input amplitudes coupled to the Kbar N channels have been obtained with the chiral SU(3) constraint, but with isospin symmetry breaking effects taken into account. Results are compared with a recent calculation applying a similar set of two-body amplitudes,based on the fixed center approximation, considered as a good approximation for a loosely bound target, and for which we find significant deviations from the exact three-body results. Effects of the hyperon-nucleon interaction, and deuteron $D$-wave component are also evaluated.Comment: 5 pages, Submitted to Phys. Rev.

Limits on Production of Magnetic Monopoles Utilizing Samples from the DO and CDF Detectors at the Tevatron

We present 90% confidence level limits on magnetic monopole production at the Fermilab Tevatron from three sets of samples obtained from the D0 and CDF detectors each exposed to a proton-antiproton luminosity of $\sim175 {pb}^{-1}$ (experiment E-882). Limits are obtained for the production cross-sections and masses for low-mass accelerator-produced pointlike Dirac monopoles trapped and bound in material surrounding the D0 and CDF collision regions. In the absence of a complete quantum field theory of magnetic charge, we estimate these limits on the basis of a Drell-Yan model. These results (for magnetic charge values of 1, 2, 3, and 6 times the minimum Dirac charge) extend and improve previously published bounds.Comment: 18 pages, 17 figures, REVTeX