Profile of a cell test database and a corresponding reliability database

The development of computerized control, and data retrieval for aerospace cell testing affords an excellent opportunity to incorporate three specific concepts to both manage the test area and to track product performance on a real-time basis. The adoption and incorporation of precepts fostered by this total quality management (TQM) initiative are critical to us for retaining control of our business while substantially reducing the separate quality control inspection activity. Test discrepancies are all 'equally bad' in cell acceptance testing because, for example, we presently do not discriminate between 1 or 25 mV for an overvoltage condition. We must take leadership in classifying such discrepancies in order to expedite their clearance and redirect our resources for prevention activities. The development and use of engineering alerts (or guardbanding) which more closely match our product capabilities and are toleranced tighter than the required customer specification are paramount to managing the test unit in order to remain both quality and cost effective

Propfan noise propagation

The unconventional supersonic tip speed of advanced propellers has led to uncertainties about Propfan's noise acceptability and compliance with Federal Aviation Noise Regulation (FAR 36). Overhead flight testing of the Propfan with an SR-7L blade during 1989's Propfan Test Assessment (PTA) Program have shown unexpectedly high far-field sound pressure levels. This study here attempts to provide insights into the acoustics of a single-rotating propeller (SRP) with supersonic tip speed. At the same time, the role of the atmosphere in shaping the far-field noise characteristics is investigated

X-ray spectrum of the high polarization quasar PKS 1510-089

We present results on the X-ray spectra of the radio-loud, high-polarization quasar, PKS 1510-089, based on new data obtained using ASCA, and from archival ROSAT data. The X-ray spectrum obtained by ASCA is unusually hard, with the photon index=1.30+-0.06, while the (non-simultaneous) ROSAT data indicate a steeper spectrum (1.9+-0.3). The X-ray flux at 1 keV is within 10% during both observations. A break in the underlying continuum at about 0.7 keV is suggested. Flat X-ray spectra seem to be the characteristic of high polarization quasars, and their spectra also appear to be harder than that of the other radio-loud but low-polarization quasars. The multiwavelength spectrum of PKS 1510-089 is similar to many other gamma-ray blazars, suggesting the emission is dominated by that from a relativistic jet. A big blue-bump is also seen in its multiwavelength spectrum, suggesting the presence of a strong thermal component as well.Comment: 19 pages (Latex + 5 ps figures), Accpeted for publication in the Astrophysical Journal, December 20, 199

Modeling the surface and interior structure of comet nuclei using a multidisciplinary approach

The goal was to investigate the structural properties of the surface of comet nucleus and how the surface should change with time under effect of solar radiation. The basic model that was adopted was that the nucleus is an aggregate of frosty particles loosely bound together, so that it is essentially a soil. The nucleus must mostly be composed of dust particles. The observed mass ratios of dust to gas in the coma is never much greater than unity, but this ratio is probably a much lower limit than that of the nucleus because it is vastly easier to remove the gaseous component by sublimation than by carrying off the dust. Therefore the described models assumed that the particles in the soil were frost covered grains of submicron basic size, closely resembling the interstellar grains. The surface properties of such a nucleus under the effects of heating and cooling as the nucleus approaches and recedes from the Sun generally characterized

Dyadic Green's Functions and Guided Surface Waves for a Surface Conductivity Model of Graphene

An exact solution is obtained for the electromagnetic field due to an electric current in the presence of a surface conductivity model of graphene. The graphene is represented by an infinitesimally-thin, local and isotropic two-sided conductivity surface. The field is obtained in terms of dyadic Green's functions represented as Sommerfeld integrals. The solution of plane-wave reflection and transmission is presented, and surface wave propagation along graphene is studied via the poles of the Sommerfeld integrals. For isolated graphene characterized by complex surface conductivity, a proper transverse-electric (TE) surface wave exists if and only if the imaginary part of conductivity is positive (associated with interband conductivity), and a proper transverse-magnetic (TM) surface wave exists when the imaginary part of conductivity is negative (associated with intraband conductivity). By tuning the chemical potential at infrared frequencies, the sign of the imaginary part of conductivity can be varied, allowing for some control over surface wave properties.Comment: 9 figure

A unitary quantum lattice gas algorithm for two dimensional quantum turbulence

Quantum vortex structures and energy cascades are examined for two dimensional quantum turbulence (2D QT) at zero temperature. A special unitary evolution algorithm, the quantum lattice gas (QLG) algorithm, is employed to simulate the Bose-Einstein condensate (BEC) governed by the Gross-Pitaevskii (GP) equation. A parameter regime is uncovered in which, as in 3D QT, there is a short Poincar\'e recurrence time. It is demonstrated that such short recurrence times are destroyed as the nonlinear interaction is strengthened. The similar loss of Poincar\'e recurrence is also reported in 3D QT [1] Energy cascades for 2D QT are considered to examine whether 2D QT exhibits inverse cascades as in 2D classical turbulence. In the parameter regime considered, the spectra analysis reveals no such dual cascades-dual cascades being a hallmark of 2D classical turbulence

Effects of Information about Invasive Species on Risk Perception and Seafood Demand by Gender and Race

In this paper we consider the effects of negative and positive risk information on perceived seafood risks and seafood consumption by gender and race. The data is from a Mid-Atlantic survey of coastal seafood consumers. We elicit risk perceptions in three risk scenarios with a dichotomous choice with a follow-up question format. We elicit continuous revealed and stated preference seafood consumption in nine risk and price scenarios. Analysis in four gender and race categories indicates that demographic groups respond to the positive and negative information in different ways. Communication of risk information as risk mitigation policy is a challenge. Key Words:

Structural Control of Metamaterial Oscillator Strength and Electric Field Enhancement at Terahertz Frequencies

The design of artificial nonlinear materials requires control over the internal resonant charge densities and local electric field distributions. We present a MM design with a structurally controllable oscillator strength and local electric field enhancement at terahertz frequencies. The MM consists of a split ring resonator (SRR) array stacked above an array of nonresonant closed conducting rings. An in-plane, lateral shift of a half unit cell between the SRR and closed ring arrays results in a decrease of the MM oscillator strength by a factor of 4 and a 40% change in the amplitude of the resonant electric field enhancement in the SRR capacitive gap. We use terahertz time-domain spectroscopy and numerical simulations to confirm our results and we propose a qualitative inductive coupling model to explain the observed electromagnetic reponse.Comment: 11 pages, 5 figure

The Welfare Effects of Pfiesteria-Related Fish Kills: A Contingent Behavior Analysis of Seafood Consumers

We use contingent behavior analysis to study the effects of pfiesteria-related fish kills on the demand for seafood in the Mid-Atlantic region. We estimate a set of demand difference models based on individual responses to questions about seafood consumption in the presence of fish kills and with different amounts of information provided about health risks. We use a random-effects Tobit model to control for correlation across each observation and to account for censoring. We find that (i) pfiesteria-related fish kills have a significant negative effect on the demand for seafood even though the fish kills pose no known threat to consumers through sea-food consumption, (ii) seafood consumers are not responsive to expert risk information designed to reassure them that seafood is safe in the presence of a fish kill, and (iii) a mandatory seafood inspection program largely eliminates the welfare loss incurred due to misinformation.pfiesteria, seafood demand, non-market valuation, Resource /Energy Economics and Policy,