The Determination of Stellar Parameters of Giants in the Galactic Disks and Bulge

Here, we present our on-going work on the determination of stellar parameters of giants in the Galactic Disks and Bulge observed with UVES on the VLT. We present some preliminarily results.Comment: 2 pages, IAU241 conference proceeding

A Decision Model for the Risk Management of Hazardous Processes

We formulate a decision model for the risk management of hazardous processes as an optimization problem of a point process. The essential features of the model are: long-term (process lifetime) objective function which is a risk-averse utility function, a dynamic risk model (marked point process model) representing the stochastic process of events observable or unobservable to the decision-maker and a long-term control variable guiding the selection of optimal solutions for short-term problems. The model is demonstrated by a case study of a hazardous process with reparable safety systems, such as a nuclear power plant. The short-term decision problem of the case study is whether it is sometimes beneficial to temporarily shut the process down in order to cut, off the high risk periods. The long-term decision problem is to optimize a long-term control variable that determines which decision alternative is preferred in a case of increased risk in the process: (1) to shut the process down during the repair time or (2) to continue the operation. Several long-term strategies are analysed and compared. As a solution approach for the optimization problem, we use the stochastic quasi-gradient procedure

Mixed Strategies in Discriminatory Divisible-good Auctions

Author: Edward J. Anderson, Pär Holmberg and Andrew B. Philpott Keywords: Pay-as-bid Auction; Divisible Good Auction; Mixed Strategy Equilibria; Wholesale Electricity Markets Pages: 71 Published: November 24, 2009 JEL-codes: D43; D44; C72 Download Wp814.pdf (756 kB) Abstract Using the concept of market-distribution functions, we derive general optimality conditions for discriminatory divisible-good auctions, which are also applicable to Bertrand games and non-linear pricing. We introduce the concept of offer distribution function to analyze randomized offer curves, and characterize mixed-strategy Nash equilibria for pay-as-bid auctions where demand is uncertain and costs are common knowledge; a setting for which pure-strategy supply function equilibria typically do not exist. We generalize previous results on mixtures over horizontal offers as in Bertrand-Edgeworth games, but more importantly we characterize novel mixtures over partly increasing supply functions.Pay-as-bid Auction; Divisible Good Auction; Mixed Strategy Equilibria; Wholesale Electricity Markets

Seeing Galaxies Through Thick & Thin. III. HST Imaging of the Dust in Backlit Spiral Galaxies

We present analysis of WFPC2 imaging of two spiral galaxies partially backlit by E/S0 systems in the pairs AM1316-241 and AM0500-620, and the spiral foreground system in NGC 1275. Images in B and I are used to determine the reddening curve of in these systems. The spiral component of AM1316-241 shows dust strongly concentrated in discrete arms, with a reddening law very close to the Milky Way mean. The dust distribution is scale-free between about 100 pc and the arm scale. The spiral in AM0500-620 shows dust concentrated in arms and interarm spurs, with measurable interarm extinction as well. Although its dust properties are less well-determined, we find evidence for a steeper extinction law here. The shape of the reddening law suggests that, at least in AM1316-241, we have resolved most of the dust structure. In AM0500-620, the slope of the fractal perimeter-scale relation steepens systematically from low to high extinction. In AM1316-241, we cannot determine a unique fractal dimension from the defining area-perimeter relation, so the projected dust distribution is best defined as fractal-like. In neither galaxy do we see regions even on single-pixel scales in spiral arms with AB > 2.5. The measurements in NGC 1275 are compromised by our lack of independent knowledge of the foreground system's light distribution, but masked sampling of the absorption suggests an effective reddening curve much flatter than the Milky Way mean (perhaps indicating that the foreground system has been affected by immersion in the hot intracluster gas).Comment: Astronomical Journal, in press. 13 figures. Full-size PostScript figures available at http://www.astr.ua.edu/preprints/kee

Transonic aerodynamic characteristics of a wing/body combination incorporating jet flaps

A 0.25-scale semispan wing/body model with two types of jet flaps was tested in the Ames 11- by 11-Foot Transonic Wind Tunnel. The objective of that testing was to measure the static aerodynamic forces and moments and wing pressure distributions on six configurations differentiated by wing camber, jet flap type, and jet flap angle. Maximum thrust coefficients were limited to 0.12. Angle of attack was varied from -4 deg to 15 deg for Mach numbers between 0.6 and 0.95 at a constant unit Reynolds number of 18.0 million/m (5.5 million/ft). More refined designs and considerably more testing will be required to establish the practicability of the total-exhausting jet flap concept

Two new species of Sabacon harvestmen, with descriptions of the females of Sabacon astoriensis Shear and Sabacon sheari Cokendolpher, from Western North America. (Arachnida, Opiliones, Sabaconidae)

Two new species of Sabaconidae (Ischyropsalidoidea) are described: Sabacon # 1 from central Alberta and British Columbia and Sabacon # 2 from Oregon. Descriptions of the females of Sabacon astoriensis Shear 1975, from Oregon, and Sabacon sheari Cokendolpher 1984, from Oregon and Idaho, are also given

The Geneva-Copenhagen Survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk

Ages, metallicities, space velocities, and Galactic orbits of stars in the Solar neighbourhood are fundamental observational constraints on models of galactic disk evolution. We aim to consolidate the calibrations of uvby photometry into Te, [Fe/H], distance, and age for F and G stars and rediscuss the results of the Geneva-Copenhagen Survey (Nordstrom et al. 2004; GCS) in terms of the evolution of the disk. We substantially improve the Te and [Fe/H] calibrations for early F stars, where spectroscopic temperatures have large systematic errors. Our recomputed ages are in excellent agreement with the independent determinations by Takeda et al. (2007), indicating that isochrone ages can now be reliably determined. The revised G-dwarf metallicity distribution remains incompatible with closed-box models, and the age-metallicity relation for the thin disk remains almost flat, with large and real scatter at all ages (sigma intrinsic = 0.20 dex). Dynamical heating of the thin disk continues throughout its life; specific in-plane dynamical effects dominate the evolution of the U and V velocities, while the W velocities remain random at all ages. When assigning thick and thin-disk membership for stars from kinematic criteria, parameters for the oldest stars should be used to characterise the thin disk.Comment: Accepted for publication in A&A on June 20, 200