Mechanization of and experience with a triplex fly-by-wire backup control system

A redundant three-axis analog control system was designed and developed to back up a digital fly-by-wire control system for an F-8C airplane. Forty-two flights, involving 58 hours of flight time, were flown by six pilots. The mechanization and operational experience with the backup control system, the problems involved in synchronizing it with the primary system, and the reliability of the system are discussed. The backup control system was dissimilar to the primary system, and it provided satisfactory handling through the flight envelope evaluated. Limited flight tests of a variety of control tasks showed that control was also satisfactory when the backup control system was controlled by a minimum-displacement (force) side stick. The operational reliability of the F-8 digital fly-by-wire control system was satisfactory, with no unintentional downmodes to the backup control system in flight. The ground and flight reliability of the system's components is discussed

Mechanization of and experience with a triplex fly-by-wire backup control system

A redundant three axis analog control system was designed and developed to back up a digital fly by wire control system for an F-8C airplane. The mechanization and operational experience with the backup control system, the problems involved in synchronizing it with the primary system, and the reliability of the system are discussed. The backup control system was dissimilar to the primary system, and it provided satisfactory handling through the flight envelope evaluated. Limited flight tests of a variety of control tasks showed that control was also satisfactory when the backup control system was controlled by a minimum displacement (force) side stick. The operational reliability of the F-8 digital fly by wire control system was satisfactory, with no unintentional downmodes to the backup control system in flight. The ground and flight reliability of the system's components is discussed

Flight test of a resident backup software system

A new fault-tolerant system software concept employing the primary digital computers as host for the backup software portion has been implemented and flight tested in the F-8 digital fly-by-wire airplane. The system was implemented in such a way that essentially no transients occurred in transferring from primary to backup software. This was accomplished without a significant increase in the complexity of the backup software. The primary digital system was frame synchronized, which provided several advantages in implementing the resident backup software system. Since the time of the flight tests, two other flight vehicle programs have made a commitment to incorporate resident backup software similar in nature to the system described in this paper

Factors influencing fruit and vegetable intake among urban Fijians: A qualitative study.

Low fruit and vegetable intake is an important risk factor for micronutrient deficiencies and non-communicable diseases, but many people worldwide, including most Fijians, eat less than the World Health Organization recommended amount. The present qualitative study explores factors that influence fruit and vegetable intake among 57 urban Fijians (50 women, 7 men) of indigenous Fijian (iTaukei) and South Asian (Indian) descent. Eight focus group discussions were held in and around Suva, Fiji's capital and largest urban area, which explored motivation for eating fruit and vegetables, understandings of links to health and disease, availability and sources, determinants of product choice, and preferred ways of preparing and eating fruit and vegetables. Data were analysed using thematic content analysis. Regardless of ethnicity, participants indicated that they enjoyed and valued eating fruit and vegetables, were aware of the health benefits, and had confidence in their cooking skills. In both cultures, fruit and vegetables were essential components of traditional diets. However, increasing preferences for processed and imported foods, and inconsistent availability and affordability of high-quality, low-priced, fresh produce, were identified as important barriers. The findings indicate that efforts to improve fruit and vegetable intake in urban Fijians should target the stability of the domestic fruit and vegetable supply and access

Alien macrocrustaceans in freshwater ecosystems in the eastern part of Flanders (Belgium)

Biological invasions of freshwater macroinvertebrates are gaining more and more interest because the ecological and economical impact of some of these species is high. Since crustacean taxa appear to be successful groups invading new areas, an inventory of the macrocrustaceans in Flanders was made. At least 22 freshwater macrocrustacean species have been reported from Flemish water bodies. A detailed study of six canals, one small artificial watercourse and one natural river in the eastern part of Flanders revealed that invaders such as Dikerogammarus villosus, Gammarus tigrinus and Chelicorophium curvispinum are already quite common. Especially D. villosus is currently rapidly expanding and has a serious impact on native and other exotic gammarid species. Based on observations in neighbouring countries, several additional species are expected to arrive in the near future. A follow-up of the alien species together with a monitoring scheme to detect new incoming species is valuable to estimate the size of the problem and to be able to closely follow their ecological and economical impact

Cancellation of probe effects in measurements of spin polarized momentum density by electron positron annihilation

Measurements of the two dimensional angular correlation of the electron-positron annihilation radiation have been done in the past to detect the momentum spin density and the Fermi surface. We point out that the momentum spin density and the Fermi Surface of ferromagnetic metals can be revealed within great detail owing to the large cancellation of the electron-positron matrix elements which in paramagnetic multiatomic systems plague the interpretation of the experiments. We prove our conjecture by calculating the momentum spin density and the Fermi surface of the half metal CrO2, who has received large attention due to its possible applications as spintronics material

Fermi surface of the colossal magnetoresistance perovskite La_{0.7}Sr_{0.3}MnO_{3}

Materials that exhibit colossal magnetoresistance (CMR) are currently the focus of an intense research effort, driven by the technological applications that their sensitivity lends them to. Using the angular correlation of photons from electron-positron annihilation, we present a first glimpse of the Fermi surface of a material that exhibits CMR, supported by ``virtual crystal'' electronic structure calculations. The Fermi surface is shown to be sufficiently cubic in nature that it is likely to support nesting.Comment: 5 pages, 5 PS figure

Screening and brief interventions for hazardous and harmful alcohol use in primary care: a cluster randomised controlled trial protocol

A large number of randomised controlled trials in health settings have consistently reported positive effects of brief intervention in terms of reductions in alcohol use. However,although alcohol misuse is common amongst offenders, there is limited evidence of alcohol brief interventions in the criminal justice field. This factorial pragmatic cluster randomised controlledtrial with Offender Managers (OMs) as the unit of randomisation will evaluate the effectiveness and cost-effectiveness of different models of screening to identify hazardous and harmful drinkers in probation and different intensities of brief intervention to reduce excessive drinking in probation clients. Ninety-six OMs from 9 probation areas across 3 English regions (the NorthEast Region (n = 4) and London and the South East Regions (n = 5)) will be recruited. OMs will berandomly allocated to one of three intervention conditions: a client information leaflet control condition (n = 32 OMs); 5-minute simple structured advice (n = 32 OMs) and 20-minute brieflifestyle counselling delivered by an Alcohol Health Worker (n = 32 OMs). Randomisation will be stratified by probation area. To test the relative effectiveness of different screening methods all OMs will be randomised to either the Modified Single Item Screening Questionnaire (M-SASQ) orthe Fast Alcohol Screening Test (FAST). There will be a minimum of 480 clients recruited into the trial. There will be an intention to treat analysis of study outcomes at 6 and 12 months postintervention. Analysis will include client measures (screening result, weekly alcohol consumption,alcohol-related problems, re-offending, public service use and quality of life) and implementation measures from OMs (the extent of screening and brief intervention beyond the minimum recruitment threshold will provide data on acceptability and feasibility of different models of brief intervention). We will also examine the practitioner and organisational factors associated with successful implementation.The trial will evaluate the impact of screening and brief alcohol intervention in routine probation work and therefore its findings will be highly relevant to probation teams and thus the criminal justice system in the UK

High resolution Compton scattering as a Probe of the Fermi surface in the Iron-based superconductor LaO1−xFxFeAsLaO_{1-x}F_xFeAs

We have carried out first principles all-electron calculations of the (001)-projected 2D electron momentum density and the directional Compton profiles along the [100], [001] and [110] directions in the Fe-based superconductor LaOFeAs within the framework of the local density approximation. We identify Fermi surface features in the 2D electron momentum density and the directional Compton profiles, and discuss issues related to the observation of these features via Compton scattering experiments.Comment: 4 pages, 3 figure

Consistent Treatment of Relativistic Effects in Electrodisintegration of the Deuteron

The influence of relativistic contributions to deuteron electrodisintegration is systematically studied in various kinematic regions of energy and momentum transfer. As theoretical framework the equation-of-motion and the unitarily equivalent S-matrix approaches are used. In a (p/M)-expansion, all leading order relativistic $\pi$-exchange contributions consistent with the Bonn OBEPQ model are included. In addition, static heavy meson exchange currents including boost terms, $\gamma\pi\rho/\omega$-currents, and $\Delta$-isobar contributions are considered. Sizeable effects from the various relativistic two-body contributions, mainly from $\pi$-exchange, have been found in inclusive form factors and exclusive structure functions for a variety of kinematic regions.Comment: 41 pages revtex including 15 postscript figure