12,960 research outputs found

    Limited evaluation of an F-14A airplane utilizing an aileron-rudder interconnect control system in the landing configuration

    Get PDF
    A flight test was conducted for preliminary evaluation of an aileron-rudder interconnect (ARI) control system for the F-14A airplane in the landing configuration. Two ARI configurations were tested in addition to the standard F-14 flight control system. Results of the flight test showed marked improvement in handling qualities when the ARI systems were used. Sideslip due to adverse yaw was considerably reduced, and airplane turn rate was more responsive to pilot lateral control inputs. Pilot comments substantiated the flight data and indicated that the ARI systems were superior to the standard control system in terms of pilot capability to make lateral offset corrections and heading changes on final approach

    Optimal symmetric flight with an intermediate vehicle model

    Get PDF
    Optimal flight in the vertical plane with a vehicle model intermediate in complexity between the point-mass and energy models is studied. Flight-path angle takes on the role of a control variable. Range-open problems feature subarcs of vertical flight and singular subarcs. The class of altitude-speed-range-time optimization problems with fuel expenditure unspecified is investigated and some interesting phenomena uncovered. The maximum-lift-to-drag glide appears as part of the family, final-time-open, with appropriate initial and terminal transient exceeding level-flight drag, some members exhibiting oscillations. Oscillatory paths generally fail the Jacobi test for durations exceeding a period and furnish a minimum only for short-duration problems

    UNWRAPPING RACIAL HARASSMENT LAW

    Get PDF
    This article is based on a pioneering empirical study of racial harassment in the workplace in which we statistically analyze federal court opinions from 1976 to 2002. Part I offers an overview of racial harassment law and research, noting its common origin with and its close dependence upon sexual harassment legal jurisprudence. In order to put the study’s analysis in context, Part I describes the dispute resolution process from which racial harassment cases arise. Parts II and III present a clear picture of how racial harassment law has played out in the courts—who are the plaintiffs and defendants, the nature of the claims, who wins and loses, and what factors affect those outcomes. We consider dozens of characteristics of the parties, the nature of the harassment, and litigation characteristics (such as the forum, type of proceedings, and legal issues). While it reveals that individuals in all kinds of occupations, in all parts of the country, of all races, and of both genders complain about racial harassment—it also shows that African Americans are disproportionately likely to be plaintiffs. While Whites are the most likely harassers, minority individuals also are defendants. The data also discloses that the most typical legal proceeding is the court’s consideration of the defendants’ motion for summary judgment where the judges end up terminating most plaintiffs’ cases. In fact, the judicial opinions in this study find in the plaintiffs’ favor only 21.5% of the time. (In contrast, an earlier study revealed that judges in sexual harassment cases find in the plaintiffs’ favor 48% of the time – more than twice as often as in racial harassment cases.) As it turns out in racial harassment cases, the race of the plaintiff and of the alleged harasser makes a difference in the parties’ success rates, but the gender of the plaintiff does not. Judges are a bit more likely to find racial harassment when plaintiffs allege blatant racist behavior rather than more subtle and contextual racism. Results vary depending on the location of the case. Part IV provides an integrated analysis of the data, including a look at how racial harassment litigation has evolved over time. It also offers explanations and implications of the study’s results. This article contributes detailed baseline data for litigants, judges, and legislators. Each group can draw upon the totality of racial harassment cases to guide their decisionmaking. The article also offers a sound basis for creating a new racial harassment jurisprudence that should be distinct from both sexual harassment and racial discrimination jurisprudence

    Arkansas Wheat Cultivar Performance Tests 2010-2011

    Get PDF
    Wheat cultivar performance tests are conducted each year in Arkansas by the Arkansas Agricultural Experiment Station, Department of Crop, Soil and Environmental Sciences. The tests provide information to companies developing cultivars and/or marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for small-grain producers

    Climb-dash real-time calculations

    Get PDF
    On-board rear-optimal climb-dash energy management, optimal symmetric flight with an intermediate vehicle model, and energy states are presented

    Optimal symmetric flight studies

    Get PDF
    Several topics in optimal symmetric flight of airbreathing vehicles are examined. In one study, an approximation scheme designed for onboard real-time energy management of climb-dash is developed and calculations for a high-performance aircraft presented. In another, a vehicle model intermediate in complexity between energy and point-mass models is explored and some quirks in optimal flight characteristics peculiar to the model uncovered. In yet another study, energy-modelling procedures are re-examined with a view to stretching the range of validity of zeroth-order approximation by special choice of state variables. In a final study, time-fuel tradeoffs in cruise-dash are examined for the consequences of nonconvexities appearing in the classical steady cruise-dash model. Two appendices provide retrospective looks at two early publications on energy modelling and related optimal control theory

    Variations in Fe\u3csup\u3e3+\u3c/sup\u3e/∑Fe of Mariana Arc Basalts and Mantle Wedge \u3cem\u3ef\u3c/em\u3eO\u3csub\u3e2\u3c/sub\u3e

    Get PDF
    Arc basalts are more oxidized than mid-ocean ridge basalts, but it is unclear whether this difference is due to differentiation processes in the Earth’s crust or to a fundamental difference in the oxygen fugacity of their mantle sources. Distinguishing between these two hypotheses is important for understanding redox-sensitive processes related to arc magmatism, and thus more broadly how Earth materials cycle globally. We present major, volatile, and trace element concentrations in combination with Fe3+/∑Fe ratios determined in olivine-hosted glass inclusions and submarine glasses from five Mariana arc volcanoes and two regions of the Mariana Trough. For single eruptions, Fe3+/∑Fe ratios vary along liquid lines of descent that are either slightly oxidizing (olivine + clinopyroxene + plagioclase fractionation, CO2 ± H2O degassing) or reducing (olivine + clinopyroxene + plagioclase ± magnetite fractionation, CO2 + H2O + S degassing). Mariana samples are consistent with a global relationship between calc-alkaline affinity and both magmatic H2O and magmatic oxygen fugacity, where wetter, higher oxygen fugacity magmas display greater affinity for calc-alkaline differentiation. We find, however, that low-pressure differentiation cannot explain the majority of variations observed in Fe3+/∑Fe ratios for Mariana arc basalts, requiring primary differences in magmatic oxygen fugacity. Calculated oxygen fugacities of primary mantle melts at the pressures and temperatures of melt segregation are significantly oxidized relative to mid-ocean ridge basalts (∼QFM, where QFM is quartz–fayalite–magnetite buffer), ranging from QFM + 1·0 to QFM + 1·6 for Mariana arc basalts, whereas back-arc related samples record primary oxygen fugacities that range from QFM + 0·1 to QFM + 0·5. This Mariana arc sample suite includes a diversity of subduction influences, from lesser influence of a homogeneous H2O-rich component in the back-arc, to sediment melt- and fluid-dominated influences along the arc. Primary melt oxygen fugacity does not correlate significantly with sediment melt contributions (e.g. Th/La), nor can it be attributed to previous melt extraction in the back-arc. Primary melt oxygen fugacity correlates strongly with indices of slab fluids (e.g. Ba/La) from the Mariana Trough through the Mariana arc, increasing by 1·5 orders of magnitude as Ba/La increases by a factor of 10 relative to mid-ocean ridge basalts. These results suggest that contributions from the slab to the mantle wedge may be responsible for the elevated oxygen fugacity recorded by Mariana arc basalts and that slab fluids are potentially very oxidized

    Milli-second Oscillations in the Persistent and Bursting Flux of Aql X-1 During an Outburst

    Get PDF
    The Rossi X-Ray Timing Explorer observed the soft X-Ray transient Aql X-1 during its outburst in February and March 1997. We report the discovery of quasi-periodic oscillations (QPOs) in its persistent flux with frequencies in the range of 740 to 830 Hz, Q-value of over 100, and a fractional RMS amplitude of (6.8 +- 0.6)%, and nearly coherent oscillations (NCOs) during a Type-I burst with a frequency of 549 Hz. The frequency of the QPOs in the persistent flux is correlated with the mass accretion rate on time scale of hours, but not on time scale of days. This is most likely the manifestation in a single source of the kHz QPO puzzle observed among many sources, i.e., on the one hand, individual sources show a correlation between the QPO frequency and the inferred mass accretion rate, on the other hand, the dozen or so sources with luminosities spanning two decades have essentially the same QPO frequencies. We propose that this multi-valued QPO frequency and mass accretion rate correlation indicates the existence of many similar regimes of the accretion disk. These regimes, with a very similar energy spectrum and QPO frequency, are distinguished from each other by the mass accretion rate or the total X-ray flux. The NCOs during the burst can be made almost perfectly coherent by taking into account a large frequency derivative. This strongly suggests that this frequency is related to the neutron star spin frequency. The large frequency derivative is attributable to the expansion or contraction of the neutron star photosphere during the burst.Comment: 6 pages, LaTex (aas2pp4), Accepted for publication in ApJ Let
    • …
    corecore