885 research outputs found

    Emerging as a Major Carrier: A Case Study of America West Airlines

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    The increasing concentration and turbulent financial environment of the U.S. airline industry raise serious questions regarding the efficacy of airline deregulation. The deregulatory experience has brought into question many of the critical assumptions of entry freedom and contestable markets upon which much of deregulation was based. The current environment poses the important question: How does a smaller or new carrier compete with today\u27s increasingly global megacarriers? The evolution of America West Airlines in its struggle to build a strong market niche provides an interesting case study of one start-up carrier\u27s strategies and policies

    Dissipation in nanocrystalline-diamond nanomechanical resonators

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    We have measured the dissipation and frequency of nanocrystalline-diamond nanomechanical resonators with resonant frequencies between 13.7 MHz and 157.3 MHz, over a temperature range of 1.4–274 K. Using both magnetomotive network analysis and a time-domain ring-down technique, we have found the dissipation in this material to have a temperature dependence roughly following T^(0.2), with Q^(–1) ≈ 10^(–4) at low temperatures. The frequency dependence of a large dissipation feature at ~35–55 K is consistent with thermal activation over a 0.02 eV barrier with an attempt frequency of 10 GHz

    INTERDIFFUSION OF HELIUM AND ARGON IN SPEER MODERATOR NO. 1 GRAPHITE (A TERMINAL REPORT ON LARGE-PORE GRAPHITES--EXPERIMENTAL PHASE)

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    An experimental investigation of the interdiffusion and forced-flow behavior of helium and argon in Speer Moderator No. 1 graphite was performed. The data were employed to determine a mutual diffusion coefficient and to verify certain superposed-flow equations. In addition, two series of experiments at high values of the forced-flow component were conducted to investigate contributions of the backdiffusion mechanism of those pores whose diameters are equal to or smaller than the mean free path of the gas molecules, approaching Rhudsen or free-molecule difiusion. At small forced-flow rates, normal diffusion was the controlling diffusion mechanism, while Knudsen effects were negligible. Flow equations employed previously are applicable to these data. Experiments conducted at high forced-flow rates show the contribution of small channels, which appears to follow the Knudsen diffusion mechanism. A critical value of sweep rate was determined. If the sweep rate is lower than the critical, the contamination will increase, whereas sweep rates greater than this would require large reprocessing capacities without additional decrease in contamination. (auth

    Electrical spin injection from an organic-based ferrimagnet in a hybrid organic/inorganic heterostructure

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    We report the successful extraction of spin polarized current from the organic-based room temperature ferrimagnetic semiconductor V[TCNE]x (x~2, TCNE: tetracyanoethylene; TC ~ 400 K, EG ~ 0.5 eV, s ~ 10-2 S/cm) and its subsequent injection into a GaAs/AlGaAs light-emitting diode (LED). The spin current tracks the magnetization of V[TCNE]x~2, is weakly temperature dependent, and exhibits heavy hole / light hole asymmetry. This result has implications for room temperature spintronics and the use of inorganic materials to probe spin physics in organic and molecular systems

    Graduate Education in Airport Administration: Preparing Airport Managers for the 21st Century

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    Growing numbers of students pursuing management careers in aviation are seeking graduate degrees to prepare for the complex and evolving challenges in the aviation industry. This study questioned members of the American Association of Airport Executives (AAAE) about their profession and the appropriateness of current education opportunities in aviation administration. The purpose of this study was to identify the knowledge and skills that the next generation of airport administrators will need to effectively contend with the new industrial environment

    Very Shallow Water Bathymetry Retrieval from Hyperspectral Imagery at the Virginia Coast Reserve (VCR\u2707) Multi-Sensor Campaign

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    A number of institutions, including the Naval Research Laboratory (NRL), have developed look up tables for remote retrieval of bathymetry and in-water optical properties from hyperspectral imagery (HSI) [6]. For bathymetry retrieval, the lower limit is the very shallow water case (here defined as \u3c 2m), a depth zone which is not well resolved by many existing bathymetric LIDAR sensors, such as SHOALS [4]. The ability to rapidly model these shallow water depths from HSI directly has potential benefits for combined HSI/LIDAR systems such as the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) [10]. In this study, we focused on the validation of a near infra-red feature, corresponding to a local minimum in absorption (and therefore a local peak in reflectance), which can be correlated directly to bathymetry with a high degree of confidence. Compared to other VNIR wavelengths, this particular near-IR feature corresponds to a peak in the correlation with depth in this very shallow water regime, and this is a spectral range where reflectance depends primarily on water depth (water absorption) and bottom type, with suspended constituents playing a secondary role
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