Technology research for strapdown inertial experiment and digital flight control and guidance

A helicopter flight-test program to evaluate the performance of Honeywell's Tetrad - a strapdown, laser gyro, inertial navitation system is discussed. The results of 34 flights showed a mean final navigational velocity error of 5.06 knots, with a standard deviation of 3.84 knots; a corresponding mean final position error of 2.66 n.mi., with a standard deviation of 1.48 n.m.; and a modeled mean-position-error growth rate for the 34 tests of 1.96 knots, with a standard deviation of 1.09 knots. Tetrad's four-ring laser gyros provided reliable and accurate angular rate sensing during the test program and on sensor failures were detected during the evaluation. Criteria suitable for investigating cockpit systems in rotorcraft were developed. This criteria led to the development of two basic simulators. The first was a standard simulator which could be used to obtain baseline information for studying pilot workload and interactions. The second was an advanced simulator which integrated the RODAAS developed by Honeywell into this simulator. The second area also included surveying the aerospace industry to determine the level of use and impact of microcomputers and related components on avionics systems

Ab initio parametrised model of strain-dependent solubility of H in alpha-iron

The calculated effects of interstitial hydrogen on the elastic properties of alpha-iron from our earlier work are used to describe the H interactions with homogeneous strain fields using ab initio methods. In particular we calculate the H solublility in Fe subject to hydrostatic, uniaxial, and shear strain. For comparison, these interactions are parametrised successfully using a simple model with parameters entirely derived from ab initio methods. The results are used to predict the solubility of H in spatially-varying elastic strain fields, representative of realistic dislocations outside their core. We find a strong directional dependence of the H-dislocation interaction, leading to strong attraction of H by the axial strain components of edge dislocations and by screw dislocations oriented along the critical slip direction. We further find a H concentration enhancement around dislocation cores, consistent with experimental observations.Comment: part 2/2 from splitting of 1009.3784 (first part was 1102.0187), minor changes from previous version

LANDSAT and environmental impact in the Paraiba Valley of Sao Paulo

There are no author-identified significant results in this report

Causes of death up to 10 years after admissions to hospitals for self-inflicted, drug-related or alcohol-related, or violent injury during adolescence: a retrospective, nationwide, cohort study

Background: Emergency hospital admission with adversity-related injury (ie, self-inflicted, drug-related or alcohol-related, or violent injury) affects 4% of 10–19-year-olds. Their risk of death in the decade after hospital discharge is twice as high as that of adolescents admitted to hospitals for accident-related injury. We established how cause of death varied between these groups. Methods: We did a retrospective, nationwide, cohort study comparing risks of death in five causal groups (suicide, drug-related or alcohol-related, homicide, accidental, and other causes of death) up to 10 years after hospital discharge following adversity-related (self-inflicted, drug-related or alcohol-related, or violent injury) or accident-related (for which there was no recorded adversity) injury. We included adolescents (aged 10–19 years) who were admitted as an emergency for adversity-related or accident-related injury between April 1, 1997, and March 31, 2012. We excluded adolescents who did not have their sex recorded, died during the index admission, had no valid discharge date, or were admitted with injury related to neither adversity nor accidents. We identified admissions for adversity-related or accident-related injury to the National Health Service in England with the International Classification of Diseases-10 codes in Hospital Episode Statistics data, linked to the Office for National Statistics mortality data for England, to establish cause-specific risks of death between the first day and 10 years after discharge, and to compare risks between adversity-related and accident-related index injury after adjustment for age group, socioeconomic status, and chronic conditions. Findings: We identified 1 080 368 adolescents (388 937 [36·0%] girls, 690 546 [63·9%] boys, and 885 [0·1%] adolescents who did not have their sex recorded). Of these adolescents, we excluded 40 549 (10·4%) girls, 56 107 (8·1%) boys, and all 885 without their sex recorded. Of the 333 009 (30·8%) adolescents admitted with adversity-related injury (181 926 [54·6%] girls and 151 083 [45·4%] boys) and 649 818 (60·2%) admitted with accident-related injury (166 462 [25·6%] girls and 483 356 [74·4%] boys), 4782 (0·5%) died in the 10 years after discharge (1312 [27·4%] girls and 3470 [72·6%] boys). Adolescents discharged after adversity-related injury had higher risks of suicide (adjusted subhazard ratio 4·54 [95% CI 3·25–6·36] for girls, and 3·15 [2·73–3·63] for boys) and of drug-related or alcohol-related death (4·71 [3·28–6·76] for girls, and 3·53 [3·04–4·09] for boys) in the next decade than they did after accident-related injury. Although we included homicides in our estimates of 10-year risks of adversity-related deaths, we did not explicitly present these risks because of small numbers and risks of statistical disclosure. There was insufficient evidence that girls discharged after adversity-related injury had increased risks of accidental deaths compared with those discharged after accident-related injury (adjusted subhazard ratio 1·21 [95% CI 0·90–1·63]), but there was evidence that this risk was increased for boys (1·26 [1·09–1·47]). There was evidence of decreased risks of other causes of death in girls (0·64 [0·53–0·77]), but not in boys (0·99 [0·84–1·17]). Risks of suicide were increased following self-inflicted injury (adjusted subhazard ratio 5·11 [95% CI 3·61–7·23] for girls, and 6·20 [5·27–7·30] for boys), drug-related or alcohol-related injury (4·55 [3·23–6·39] for girls, and 4·51 [3·89–5·24] for boys), and violent injury in boys (1·43 [1·15–1·78]) versus accident-related injury. However, the increased risk of suicide in girls following violent injury versus accident-related injury was not significantly increased (adjusted subhazard ratio 1·48 [95% CI 0·73–2·98]). Following each type of index injury, risks of suicide and risks of drug-related or alcohol-related death were increased by similar magnitudes. Interpretation: Risks of suicide were significantly increased after all types of adversity-related injury except for girls who had violent injury. Risks of drug-related or alcohol-related death increased by a similar magnitude. Current practice to reduce risks of harm after self-inflicted injury should be extended to drug-related or alcohol-related and violent injury in adolescence. Prevention should address the substantial risks of drug-related or alcohol-related death alongside risks of suicide. Funding: UK Department of Health

Scaling Behaviour and Complexity of the Portevin-Le Chatelier Effect

The plastic deformation of dilute alloys is often accompanied by plastic instabilities due to dynamic strain aging and dislocation interaction. The repeated breakaway of dislocations from and their recapture by solute atoms leads to stress serrations and localized strain in the strain controlled tensile tests, known as the Portevin-Le Chatelier (PLC) effect. In this present work, we analyse the stress time series data of the observed PLC effect in the constant strain rate tensile tests on Al-2.5%Mg alloy for a wide range of strain rates at room temperature. The scaling behaviour of the PLC effect was studied using two complementary scaling analysis methods: the finite variance scaling method and the diffusion entropy analysis. From these analyses we could establish that in the entire span of strain rates, PLC effect showed Levy walk property. Moreover, the multiscale entropy analysis is carried out on the stress time series data observed during the PLC effect to quantify the complexity of the distinct spatiotemporal dynamical regimes. It is shown that for the static type C band, the entropy is very low for all the scales compared to the hopping type B and the propagating type A bands. The results are interpreted considering the time and length scales relevant to the effect.Comment: 35 pages, 6 figure

Impact of active and passive social facilitation on self paced endurance and sprint exercise: encouragement augments performance and motivation to exercise

Objective The positive effect of an audience on performance is anecdotally well known, but the impact of such social facilitation to both performance and the motivation to exercise have not been thoroughly explored. The aim of this study was therefore to investigate verbal encouragement as a means to promote positive behavioural adherence to exercise and augmented performance. Methods Twelve untrained but active individuals (seven female), age 24±3 years participated in this study. Exercise conditions with external verbal encouragement (EVE) and without external verbal encouragement (WEVE) were compared in both endurance (20 min) and sprint (2 × 30 s Wingate) cycling tasks in a randomised crossover design. Results were analysed by separate 2 (EVE/WEVE) × 2 (sprint/endurance) within-subjects analyses of variance for each dependent variable. Statistical significance was set at p≤0.05. Results EVE resulted in a significant increase, F (1,11)=15.37, p=0.002, η p 2=0.58 in the average power generated by participants in each exercise bout on the cycle ergometer. EVE also had a significant effect on reported motivation to exercise the next day, F (1,11)=5.5, p=0.04, η p 2 =0.33, which did not differ between type of exercise. Conclusion External encouragement in both sprint and endurance activities resulted in large improvements in performance and motivation to continue an exercise regimen the next day, which has important implications for health, adherence and maximising physical performance using a practical intervention