Calculations, and comparison with an ideal minimum, of trimmed drag for conventional and canard configurations having various levels of static stability

Classical drag equations were used to calculate total and induced drag and ratios of stabilizer lift to wing lift for a variety of conventional and canard configurations. The Flight efficiencies of such configurations that are trimmed in pitch and have various values of static margin are evaluated. Classical calculation methods are compared with more modern lifting surface theory

A bright millisecond radio burst of extragalactic origin

Pulsar surveys offer one of the few opportunities to monitor even a small fraction (~0.00001) of the radio sky for impulsive burst-like events with millisecond durations. In analysis of archival survey data, we have discovered a 30-Jy dispersed burst of duration <5 ms located three degrees from the Small Magellanic Cloud. The burst properties argue against a physical association with our Galaxy or the Small Magellanic Cloud. Current models for the free electron content in the Universe imply a distance to the burst of <1 Gpc No further bursts are seen in 90-hr of additional observations, implying that it was a singular event such as a supernova or coalescence of relativistic objects. Hundreds of similar events could occur every day and act as insightful cosmological probes.Comment: 18 pages, 4 figures. Accepted by Science. Published electronically via Science Express on September 27, 200

Analytical Model for the Optical Functions of Indium Gallium Nitride with Application to Thin Film Solar Photovoltaic Cells

This paper presents the preliminary results of optical characterization using spectroscopic ellipsometry of wurtzite indium gallium nitride (InxGa1-xN) thin films with medium indium content (0.38<x<0.68) that were deposited on silicon dioxide using plasma-enhanced evaporation. A Kramers-Kronig consistent parametric analytical model using Gaussian oscillators to describe the absorption spectra has been developed to extract the real and imaginary components of the dielectric function ({\epsilon}1, {\epsilon}2) of InxGa1-xN films. Scanning electron microscope (SEM) images are presented to examine film microstructure and verify film thicknesses determined from ellipsometry modelling. This fitting procedure, model, and parameters can be employed in the future to extract physical parameters from ellipsometric data from other InxGa1-xN films

Simulation studies of STOL airplane operations in metropolitan downtown and airport air traffic control environments

The operating problems and equipment requirements for STOL airplanes in terminal area operations in simulated air traffic control (ATC) environments were studied. These studies consisted of Instrument Flight Rules (IFR) arrivals and departures in the New York area to and from a downtown STOL port, STOL runways at John F. Kennedy International Airport, or STOL runways at a hypothetical international airport. The studies were accomplished in real time by using a STOL airplane flight simulator. An experimental powered lift STOL airplane and two in-service airplanes having high aerodynamic lift (i.e., STOL) capability were used in the simulations

Terminal-area flight procedures and route design for supersonic transport New York-transatlantic operations

The results of an analytical investigation of two departure and arrival transition procedures between John F. Kennedy International Airport and projected North Atlantic track systems for supersonic transport (SST) operations are presented. The procedures studied were: (1) separated departure and arrival transition routes with departures made at supersonic speeds, and (2) superimposed departure and arrival routes with departures restricted to subsonic speed until the airplane is on the track system. For both procedures, transition routes with intercept angles of 30 deg to 90 deg to both six-and four-track systems were investigated. Track spacings of 30 and 60 nautical miles were studied

Asymptotics of the partition function for random matrices via Riemann-Hilbert techniques, and applications to graphical enumeration

We study the partition function from random matrix theory using a well known connection to orthogonal polynomials, and a recently developed Riemann-Hilbert approach to the computation of detailed asymptotics for these orthogonal polynomials. We obtain the first proof of a complete large N expansion for the partition function, for a general class of probability measures on matrices, originally conjectured by Bessis, Itzykson, and Zuber. We prove that the coefficients in the asymptotic expansion are analytic functions of parameters in the original probability measure, and that they are generating functions for the enumeration of labelled maps according to genus and valence. Central to the analysis is a large N expansion for the mean density of eigenvalues, uniformly valid on the entire real axis.Comment: 44 pages, 4 figures. To appear, International Mathematics Research Notice

Timing of pulsars found in a deep Parkes multibeam survey

We have carried out a sensitive radio pulsar survey along the northern Galactic plane ($50^{\circ} < l < 60^{\circ}$ and |b| \lapp 2^{\circ}) using the Parkes 20-cm multibeam system. We observed each position for 70-min on two separate epochs. Our analyses to date have so far resulted in the detection of 32 pulsars, of which 17 were previously unknown. Here we summarize the observations and analysis and present the timing observations of 11 pulsars and discovery parameters for a further 6 pulsars. We also present a timing solution for the 166-ms bursting pulsar, PSR~J1938+2213, previously discovered during an Arecibo drift-scan survey. Our survey data for this pulsar show that the emission can be described by a steady pulse component with bursting emission, which lasts for typically 20--25 pulse periods, superposed. Other new discoveries are the young 80.1-ms pulsar PSR~J1935+2025 which exhibits a significant amount of unmodeled low-frequency noise in its timing residuals, and the 4.2-ms pulsar PSR~J1935+1726 which is in a low-mass binary system with a 90.7-day circular orbit.Comment: 6 pages, 2 figures, accepted for publication in MNRA

A modified Newton-Raphson analysis of flight measurements of the trailing vortices of a heavy jet transport

A modified Newton-Raphson method has been used to determine the parameters in equations describing the vortex flow to obtain a best match with flight measurements of the flow behind the C-5A airplane. The flight measurements were made using a specially instrumented T-33 airplane which passed as closely as possible to the centers of the trailing vortices at several distances behind the C-5A airplane. The flight measurements were transformed to flow velocity relative to an inertial frame of reference. The assumed form of the flow consisted of the superposition of two counterrotating, finite core vortices. The positions of the vortex centers, their total circulation, the effective eddy viscosity and measurement bias were the parameters adjusted. The assumed form of vortex flow fit well the measured velocities for the numerous sets of data, both flaps up and down for the C-5A airplane. The resulting values of total circulation, however, were about two-thirds that expected of a wing with an elliptical loading. A partial explanation of the less than expected circulation is a dip in the spanwise lift distribution at the airplane's center line. The distance between the trailing vortices at the smallest times encountered is somewhat less than that expected for an elliptical wing loading

A fixed-base simulation study of two STOL aircraft flying curved, descending instrument approach paths

A real-time, fixed-base simulation study has been conducted to determine the curved, descending approach paths (within passenger-comfort limits) that would be acceptable to pilots, the flight-director-system logic requirements for curved-flight-path guidance, and the paths which can be flown within proposed microwave landing system (MLS) coverage angles. Two STOL aircraft configurations were used in the study. Generally, no differences in the results between the two STOL configurations were found. The investigation showed that paths with a 1828.8 meter turn radius and a 1828.8 meter final-approach distance were acceptable without winds and with winds up to at least 15 knots for airspeeds from 75 to 100 knots. The altitude at roll-out from the final turn determined which final-approach distances were acceptable. Pilots preferred to have an initial straight leg of about 1 n. mi. after MLS guidance acquisition before turn intercept. The size of the azimuth coverage angle necessary to meet passenger and pilot criteria depends on the size of the turn angle: plus or minus 60 deg was adequate to cover all paths execpt ones with a 180 deg turn