2,437 research outputs found

    Design of an all-attitude flight control system to execute commanded bank angles and angles of attack

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    A flight control system for use in air-to-air combat simulation was designed. The input to the flight control system are commanded bank angle and angle of attack, the output are commands to the control surface actuators such that the commanded values will be achieved in near minimum time and sideslip is controlled to remain small. For the longitudinal direction, a conventional linear control system with gains scheduled as a function of dynamic pressure is employed. For the lateral direction, a novel control system, consisting of a linear portion for small bank angle errors and a bang-bang control system for large errors and error rates is employed

    Electron paramagnetic resonance of rutile pigments

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    An Electron Paramagnetic Resonance study of rutile (TiO(_2)) pigments doped with either iron or chromium has been performed. The spectra of the Cr(^3+) ion has been observed and confirmed by computation. In iron doped pigments a signal with g = 4.28 was observed and has been attributed to the Fe(^3+) ion in a site of rhombic symmetry. The effect of irradiation by light on the Fe(^3*) ion in a substitutional site has been examined and seen to be different from that for single crystal samples ; only wavelengths longer than 700 nm affect it. A light-generated line was observed with 'g' values g(_11) = 2.010, g(_1) = 2.005. The response of this line is related to the concentration of iron. The data has been analysed and correlates reasonably well with accepted models for the positions of the defect centres within the band gap

    Ritual and the origins of first impressions

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    When encountering a stranger for the first time, adults spontaneously attribute to them a wide variety of character traits based solely on their physical appearance, most notably from their face. While these trait inferences exert a pervasive influence over our behaviour, their origins remain unclear. Whereas nativist accounts hold that first impressions are a product of gene-based natural selection, the Trait Inference Mapping framework (TIM) posits that we learn face-trait mappings ontogenetically as a result of correlated face-trait experience. Here, we examine the available anthropological evidence on ritual in order to better understand the mechanism by which first impressions from faces are acquired. Consistent with the TIM framework, we argue that examination of ritual body modification performed by communities around the world demonstrates far greater cross-cultural variability in face-trait mappings than currently appreciated. Furthermore, rituals of this type may be a powerful mechanism through which face-trait associations are transmitted from one generation to the next

    A Method for the Calculation of the Lateral Response of Airplanes to Random Turbulence

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    In this method, the gust velocities are represented as rolling gusts, yawing gusts, and side gusts. Random distributions of gust velocities across the span are taken into account in defining the rolling and yawing gusts. Complex stability derivatives are used to account for the random distribution of side gusts along the fuselage and vertical tail and the lag effects in gust penetration. A sample calculation procedure is presented for obtaining the response of the airplane in each degree of freedom

    Measuring migration motives with open-ended survey data:Methodological and conceptual issues

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    Motives for migration are difficult to measure. Open‐ended data collection can be an attractive option, but also comes with pitfalls. We use the “Motives for Migration” survey on internal migration in Sweden to identify some of these pitfalls. We identify five categories of methodological issues: how the respondents—and we—dealt with multiple motives for migration; who the motive pertained to (i.e., the respondents themselves or someone else in the household); whether the motive was related to a status or an event; which third‐party person(s) the respondent meant to refer to; and which geographical unit the motive pertained to. We also identify two conceptual issues: (1) the distinction between reasons for moving and location choice and (2) the distinction between moving “from” and moving “to” somewhere. We present some suggestions that will be useful for future attempts to study the topic and possibly such other topics as motives for immigration, getting married, or leaving the parental home

    Hospital ownership and quality of care: what explains the different results?

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    Does quality of care systematically differ among government-owned, private not-for-profit, and for-profit hospitals? A large empirical literature provides conflicting evidance. Through quantitative review of 46 studies since 1990, we find that several study features that can explain divergent results: analytic methods, disease studied, and data sources. For unprofitable care, how studies handle market competition and regional differences account for substantial variation. Policymakers should be aware that differences in results appear to arise predominately from differences between studies' analytic methods. Moreover, conventional methods of meta-analysis synthesis should be applied with great caution given the considerable overlap among studied hospitals

    Book Reviews

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    Thermodynamics of an ideal generalized gas:II Means of order α\alpha

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    The property that power means are monotonically increasing functions of their order is shown to be the basis of the second laws not only for processes involving heat conduction but also for processes involving deformations. In an LL-potentail equilibration the final state will be one of maximum entropy, while in an entropy equilibrium the final state will be one of minimum LL. A metric space is connected with the power means, and the distance between means of different order is related to the Carnot efficiency. In the ideal classical gas limit, the average change in the entropy is shown to be proportional to the difference between the Shannon and R\'enyi entropies for nonextensive systems that are multifractal in nature. The LL-potential, like the internal energy, is a Schur convex function of the empirical temperature, which satisfies Jensen's inequality, and serves as a measure of the tendency to uniformity in processes involving pure thermal conduction.Comment: 8 page

    Track Reconstruction Progress from the DMTPC Directional Dark Matter Experiment

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    he Dark Matter Time Projection Chamber (DMTPC) collaboration is developing prototype detectors to measure both the energies and directions of nuclear recoils. The intended application is to exploit the expected directional anisotropy of dark matter velocities at Earth to unambiguously observe dark matter induced recoils. The detector consist of low-pressure CF[subscript 4] TPC's with CCD cameras, PMT's, and charge amplifiers for readout. This talk gives an overview of the experiment and describes recent advances in hardware and analysis

    Longitudinally diode-pumped Nd:YAG double-clad planar waveguide laser

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    We report the demonstration of a near-diffraction-limited, compact, diode-end-pumped double-clad planar waveguide Nd:YAG laser. Efficient laser operation was achieved for the three dominant Nd3+ transitions at 1.064”m 0.946”m, and 1.32”m, with TE polarised output powers of 1.33W, 0.57W, and 0.33W for the available output couplers. The output beam from the monolithic plane-plane laser cavity had measured M2 values of 1.0 and 1.8, perpendicular and parallel to the plane of the waveguide respectively
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