Tentative civil airworthiness flight criteria for powered-lift transports

Representatives of the U.S., British, French, and Canadian airworthiness authorities participated in a NASA/FAA program to formulate tentative civil airworthiness flight criteria for powered-lift transports. The ultimate limits of the flight envelope are defined by boundaries in the airspeed/path-angle plane. Angle of attack and airspeed margins applied to these ultimate limits provide protection against both atmospheric disturbances and disturbances resulting from pilot actions or system variability, but do not ensure maneuvering capability directly, as the 30% speed margin does for conventional transports. Separate criteria provide for direct demonstration of adequate capability for approach path control, flare and landing, and for go-around. Demonstration maneuvers are proposed, and appropriate abuses and failures are suggested. Taken together, these criteria should permit selection of appropriate operating points within the flight envelopes for the approach, landing, and go-around flight phases which are likely to be most critical for powered-lift aircraft

Factors affecting handling qualities of a lift-fan aircraft during steep terminal area approaches

The XV-5B lift-fan aircraft was used to explore the factors affecting handling qualities in the terminal area. A 10 deg ILS approach task was selected to explore these problems. Interception of the glide slope at 457.2 m, glide slope tracking, deceleration along the glide slope to a spot hover were considered. Variations in airplane deck angle, deceleration schedule, and powered-lift management were studied. The overall descent performance envelope was identified on the basis of fan stall, maximum comfortable descent rate, and controllability restrictions. The collective-lift stick provided precise glide slope tracking capability. The pilot preferred a deck-parallel attitude for which he used powered lift to control glide slope and pitch attitude to keep the angle of attack near zero. Workload was reduced when the deceleration schedule was delayed until the aircraft was well established on the glide slope, since thrust vector changes induced flight path disturbances

The effects of recreational footpaths on terrestrial invertebrate communities in a UK ancient woodland: a case study from Blean Woods, Kent, UK

Globally, terrestrial invertebrates are in decline, in part due to habitat fragmentation. Footpaths provide nature-based recreation to the public but can present small-scale spatially continuous changes in forest dynamics. However, their effects on terrestrial invertebrate communities are unknown. Pitfall trapping was undertaken to identify whether terrestrial invertebrate communities were disrupted by a popular recreational footpath in Blean Woods, an ancient UK woodland. The study identified 720 invertebrates across 36 taxa from 20 footpath edge and forest interior traps. It was found that footpaths did not significantly affect terrestrial invertebrate communities. There was no difference in the taxonomic abundance, richness, and diversity; invertebrate trait abundance and richness; or invertebrate community composition between the footpath edge and woodland interior traps. Thus, footpaths in Blean Woods do not disturb the terrestrial invertebrate community, and therefore present a sustainable mechanism for facilitating public engagement with conservation in a nationally important protected ancient woodland

From Monterey to Galway: Evolution of the Oceans in National Income Accounts

This paper provides an introduction and overview of selected papers from the 5th International Symposium on the Oceans in National Income Accounts organized by the Socio-Economics Marine Research Unit at the National University of Ireland Galway in March 2021. Eleven papers drawn from the symposium are included in this volume. The papers cover the current status of defining the ocean economy within national accounts, the expansion of ocean accounting to include environmental economic values, and methodological tools to assist the integration

On the Optical -- X-ray correlation from outburst to quiescence in Low Mass X-ray Binaries: the representative cases of V404 Cyg and Cen X-4

Low mass X-ray binaries (LMXBs) show evidence of a global correlation of debated origin between X-ray and optical luminosity. We study for the first time this correlation in two transient LMXBs, the black hole V404 Cyg and the neutron star Cen X-4, over 6 orders of magnitude in X-ray luminosity, from outburst to quiescence. After subtracting the contribution from the companion star, the Cen X-4 data can be described by a single power law correlation of the form $L_{opt}\propto\,L_{X}^{0.44}$, consistent with disk reprocessing. We find a similar correlation slope for V404 Cyg in quiescence (0.46) and a steeper one (0.56) in the outburst hard state of 1989. However, V404 Cyg is about $160-280$ times optically brighter, at a given $3-9$ keV X-ray luminosity, compared to Cen X-4. This ratio is a factor of 10 smaller in quiescence, where the normalization of the V404 Cyg correlation also changes. We show that once the bolometric X-ray emission is considered and the known main differences between V404 Cyg and Cen X-4 are taken into account (a larger compact object mass, accretion disk size, and the presence of a strong jet contribution in the hard state for the black hole system) the two systems lie on the same correlation. In V404 Cyg, the jet dominates spectrally at optical-infrared frequencies during the hard state, but makes a negligible contribution in quiescence, which may account for the change in its correlation slope and normalization. These results provide a benchmark to compare with data from the 2015 outburst of V404 Cyg and, potentially, other transient LMXBs as well.Comment: Accepted on ApJ, 12 pages, 4 figures, 4 table

Expanding hot flow in the black hole binary SWIFT J1753.5-0127: evidence from optical timing

We describe the evolution of optical and X-ray temporal characteristics during the outburst decline of the black hole X-ray binary SWIFT J1753.5-0127. The optical/X-ray cross-correlation function demonstrates a single positive correlation at the outburst peak, then it has multiple dips and peaks during the decline stage, which are then replaced by the precognition dip plus peak structure in the outburst tail. Power spectral densities and phase lags show a complex evolution, revealing the presence of intrinsically connected optical and X-ray quasi-periodic oscillations. For the first time, we quantitatively explain the evolution of these timing properties during the entire outburst within one model, the essence of which is the expansion of the hot accretion flow towards the tail of the outburst. The pivoting of the spectrum produced by synchrotron Comptonization in the hot flow is responsible for the appearance of the anti-correlation with the X-rays and for the optical quasi-periodic oscillations. Our model reproduces well the cross-correlation and phase lag spectrum during the decline stage, which could not be understood with any model proposed before.Comment: 13 pages, 11 figures, MNRAS submitte

An investigation of the mechanisms of sound generation in initially laminar subsonic jets using the Goldstein acoustic analogy

This version has been accepted for publication.Published in Journal of Fluid Mechanics / Volume 714 / January 2013, pp 24 - 57 Copyright © Cambridge University Press 2013 DOI: http://dx.doi.org/10.1017/jfm.2012.448, Published online: 02 January 201

MAJOR DIFFERENCE: AN EXAMINATION OF STUDENT WRITING PERFORMANCE BY MAJOR AND ITS IMPLICATIONS FOR BUSINESS COMMUNICATION

This study analyzes the writing performance levels of 352 students to determine the extent to which business students are achieving written communication competency and whether differences exist among the business majors. Although most students met or exceeded expectations in format and content on a common writing task, students were weakest in grammar and mechanics, with almost half scoring below expectations across all majors. The findings indicate no statistically significant differences in writing competency among majors. This study also suggests that business communicators can serve as “collegial consultants” in a cross-disciplinary effort to improve student writing

Multiwavelength Observations of Swift J1753.5-0127

We present contemporaneous X-ray, ultraviolet, optical and near-infrared observations of the black hole binary system, Swift J1753.5-0127, acquired in 2012 October. The UV observations, obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope, are the first UV spectra of this system. The dereddened UV spectrum is characterized by a smooth, blue continuum and broad emission lines of CIV and HeII. The system was stable in the UV to <10% during our observations. We estimated the interstellar reddening by fitting the 2175 A absorption feature and fit the interstellar absorption profile of Ly$\alpha$ to directly measure the neutral hydrogen column density along the line of sight. By comparing the UV continuum flux to steady-state thin accretion disk models, we determined upper limits on the distance to the system as a function of black hole mass. The continuum is well fit with disk models dominated by viscous heating rather than irradiation. The broadband spectral energy distribution shows the system has declined at all wavelengths since previous broadband observations in 2005 and 2007. If we assume that the UV emission is dominated by the accretion disk the inner radius of the disk must be truncated at radii above the ISCO to be consistent with the X-ray flux, requiring significant mass loss from outflows and/or energy loss via advection into the black hole to maintain energy balance.Comment: To appear in the Ap