Information and display requirements for aircraft terrain following

The display design procedure for manned vehicle systems, is applied and validated, for a particular scenario. The scenario chosen is that of zero visibility high speed terrain following (V = 466 ft/sec, H = 200 ft) with an A-10 aircraft. The longitudal (linearized) dynamics are considered. The variations in (command path over) terrain pi(t) are modeled as a third order random process. The display design methodology is based on the optimal control model of pilot response, and employs this model in various ways in different phases of the design process. The overall methodology indicates that the design process is intended as a precursor to manned simulation. It provides a rank ordering of candidate displays through a three level process

Drug Legalization: The Importance of Asking the Right Question Symposium on Drug Decriminalization

As a policy analysis, this article\u27s central argument is that that the costs imposed by markets in licit psychoactives are significantly greater than those imposed by drug prohibition

Accelerated procedures for the solution of discrete Markov control problems Final report

Accelerated procedures for solution of discrete Markov control problem

Mathematical programming and the control of Markov chains

Linear and dynamic programming and Markov chain optimal contro

Modeling the effects of high-G stress on pilots in a tracking task

Air-to-air tracking experiments were conducted at the Aerospace Medical Research Laboratories using both fixed and moving base dynamic environment simulators. The obtained data, which includes longitudinal error of a simulated air-to-air tracking task as well as other auxiliary variables, was analyzed using an ensemble averaging method. In conjunction with these experiments, the optimal control model is applied to model a human operator under high-G stress

A population synthesis study of the luminosity function of hot white dwarfs

We present a coherent and detailed Monte Carlo simulation of the population of hot white dwarfs. We assess the statistical significance of the hot end of the white dwarf luminosity function and the role played by the bolometric corrections of hydrogen-rich white dwarfs at high effective temperatures. We use the most up-to-date stellar evolutionary models and implement a full description of the observational selection biases to obtain realistic simulations of the observed white dwarf population. Our theoretical results are compared with the luminosity function of hot white dwarfs obtained from the Sloan Digital Sky Survey (SDSS), for both DA and non-DA white dwarfs. We find that the theoretical results are in excellent agreement with the observational data for the population of white dwarfs with hydrogen deficient atmospheres (non-DA white dwarfs). For the population of white dwarfs with hydrogen-rich atmospheres (white dwarfs of the DA class), our simulations show some discrepancies with the observations for the brightest luminosity bins. These discrepancies can be attributed to the way in which the masses of the white dwarfs contributing to this luminosity bin have been computed, as most of them have masses smaller than the theoretical lower limit for carbon-oxygen white dwarfs. We conclude that the way in which the observational luminosity function of hot white dwarfs is obtained is very sensitive to the particular implementation of the method used to derive the masses of the sample. We also provide a revised luminosity function for hot white dwarfs with hydrogen-rich atmospheres.Comment: 6 pages, 5 figures, accepted for publication in A&

A model for the submarine depthkeeping team

The most difficult task the depthkeeping team must face occurs during periscope-depth operations during which they may be required to maintain a submarine several hundred feet long within a foot of ordered depth and within one-half degree of ordered pitch. The difficulty is compounded by the facts that wave generated forces are extremely high, depth and pitch signals are very noisy and submarine speed is such that overall dynamics are slow. A mathematical simulation of the depthkeeping team based on the optimal control models is described. A solution of the optimal team control problem with an output control restriction (limited display to each controller) is presented

SDSS White Dwarf mass distribution at low effective temperatures

The DA white dwarfs in the Sloan Digital Sky Survey, as analyzed in the papers for Data Releases 1 and 4, show an increase in surface gravity towards lower effective temperatures below 11500 K. We study the various possible explanations of this effect, from a real increase of the masses to uncertainties or deficiencies of the atmospheric models. No definite answer is found but the tentative conclusion is that it is most likely the current description of convection in the framework of the mixing-length approximation, which leads to this effect.Comment: to appear in the proceedings of the 16th European Workshop on White Dwarfs, Barcelona, 200

New Pulsating DB White Dwarf Stars from the Sloan Digital Sky Survey

We are searching for new He atmosphere white dwarf pulsators (DBVs) based on the newly found white dwarf stars from the spectra obtained by the Sloan Digital Sky Survey. DBVs pulsate at hotter temperature ranges than their better known cousins, the H atmosphere white dwarf pulsators (DAVs or ZZ Ceti stars). Since the evolution of white dwarf stars is characterized by cooling, asteroseismological studies of DBVs give us opportunities to study white dwarf structure at a different evolutionary stage than the DAVs. The hottest DBVs are thought to have neutrino luminosities exceeding their photon luminosities (Winget et al. 2004), a quantity measurable through asteroseismology. Therefore, they can also be used to study neutrino physics in the stellar interior. So far we have discovered nine new DBVs, doubling the number of previously known DBVs. Here we report the new pulsators' lightcurves and power spectra.Comment: 15 pages, 2 figures, 3 tables, ApJ accepte