Federal Aviation Administration

International audience

In 4 experiments, participants alternated between different tasks or performed the same task repeatedly. The tasks for 2 of the experiments required responding to geometric objects in terms of alternative classification rules, and the tasks for the other 2 experiments required solving arithmetic problems in terms of alternative numerical operations. Performance was measured as a function of whether the tasks were familiar or unfamiliar, the rules were simple or complex, and visual cues were present or absent about which tasks should be performed. Task alternation yielded switching-time costs that increased with rule complexity but decreased with task cuing. These factor effects were additive, supporting a model of executive control that has goal-shifting and rule-activation stages for task switching. It appears that rule activation takes more time for switching from familiar to unfamiliar tasks than for switching in the opposite direction.

The literature on blink rate as a measure of fatigue is reviewed. The evidence of increases in blink rate as a function of time on task is compelling. However, variables other than time on task also affect blink rate. These variables range from perceptual demandingness of the task to cognitive variables. Other aspects of blinking, such as flurries of blinks, timing with respect to information-processing demands, and blink closure duration, are reviewed as additional variables sensitive to task demands and fatigue effects.

© 2018 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).* RetiredCORRESPONDING AUTHOR: Mary Cairns, cairnsmm@gmail.com

This tutorial provides a practical approach to assessing modified condition/decision coverage (MC/DC) for aviation software products that must comply with regulatory guidance for DO-178B level A software. The tutorial''s approach to MC/DC is a 5-step process that allows a certification authority or verification analyst to evaluate MC/DC claims without the aid of a coverage tool. In addition to the MC/DC approach, the tutorial addresses factors to consider in selecting and qualifying a structural coverage analysis tool, tips for reviewing life cycle data related to MC/DC, and pitfalls common to structural coverage analysis.

The fire response of a potassium aluminosilicate (Geopolymer) matrix carbon fiber composite was measured and the results compared to organic matrix composites being used for transportation, military, and infrastructure applications. At irradiance levels of 50 kWm−2 typical of the heat flux in a well-developed fire, glass- or carbon-reinforced polyester, vinylester, epoxy, bismaleimde, cyanate ester, polyimide, phenolic, and engineering thermoplastic laminates ignited readily and released appreciable heat and smoke, while carbon-fiber reinforced Geopolymer composites did not ignite, burn, or release any smoke even after extended heat flux exposure. The Geopolymer matrix carbon fiber composite retains 67% of its original flexural strength after a simulated large fire exposure. © 1997 US Government

Weather radars with conventional antenna cannot provide desired volume scan updates at intervals of one minute or less, which is essential for significant improvement in warning lead time of impending storm hazards. The agile-beam multimission phased array radar (MPAR) discussed herein is one potential candidate that can provide faster scanning. It also offers a unique potential for multipurpose use to not only sample weather, but support air traffic needs and track noncooperative airplanes, thus making it an affordable option. After introducing the basic idea behind electronic beam steering, the needs for frequent observations of convective weather are explained. Then, advantages of the phased array radar (PAR) for weather monitoring and improving data quality are examined. To explore and develop weather-related applications of the PAR, a National Weather Radar Testbed (NWRT) has been established in Norman, Oklahoma. The NWRT's main purpose is to address the advanced capabilities anticipated within the next decade so that these could be projected to a possible network of future weather radars. Examples of data illustrating advantages of this advanced radar are shown, and forthcoming plans are discussed.

Although the benefits of requirements traceability are widely recognized, the actual practice of maintaining a traceability scheme is not always entirely successful. The traceability infrastructure underlying a software system tends to erode over its lifetime, as time-pressured practitioners fail to consistently maintain links and update impacted artifacts each time a change occurs, even with the support of automated systems. This paper proposes a new method of traceability based upon event-notification and is applicable even in a heterogeneous and globally distributed development environment. Traceable artifacts are no longer tightly coupled but are linked through an event service, which creates an environment in which change is handled more efficiently, and artifacts and their related links are maintained in a restorable state. The method also supports enhanced project management for the process of updating and maintaining the system artifacts.

This paper provides an overview of the National Jet Fuels Combustion Program led by the Federal Aviation Administration, the U.S. Air Force Research Laboratory, and the NASA. The program follows from basic research from the U.S. Air Force Office of Scientific Research and results from the engine-company-led Combustion Rules and Tools program funded by the U.S. Air Force. The overall objective of this fuels program was to develop combustion-related generic test and modeling capabilities that can improve the understanding of the impact of fuel chemical composition and physical properties on combustion, leading to accelerating the approval process of new alternative jet fuels. In this paper, the motivation and objectives for the work, participating universities, gas-turbine-engine companies, other federal agencies, and international partners are described. This paper provides an in-depth discussion on the benefits to the fuels approval process, the rationale in selecting conventional and alternative fuels to study, the referee rig used for fuel testing, and the modeling approaches. High-level results are also briefly discussed, and will be covered in detail in separate university-led papers. Lastly, an Appendix reviewing past programs, events, and workshops that lay the groundwork for this program is also included for reference.

Charter 1 Introduction.- 2 Dimensional Analysis and the Pi Theorem Units and Dimensions.- 2-1 Units and Dimensions.- 2-2 Types of Quantities Appearing in Physical Equations.- a. Primary and Secondary Quantities.- b. Physical Constants and Independent Dimensions.- c. Nondimensional Quantities.- 2-3 Dimensional Homogeneity of Physical Equations.- 2-4 Statement and Use of the Pi Theorem.- 2-5 Rationale of the Pi Theorem.- 2-6 Huntley's Addition.- 2-7 Examples of Application of Dimensional Analysis.- 2-8 Summary.- 3 Method of Similitude and Introduction to Fractional Analysis of Overall Equations.- 3-1 Introduction.- 3-2 Method of Similitude.- a. Use of Force Ratios.- b. Generalization of the Method of Similitude.- c. Some Energy Ratios of Heat Transfer.- 3-3 Direct Use of Governing Overall Equations.- 3-4 Concluding Remarks.- 4 Fractional Analysis of Governing Equations and Conditions.- 4-1 Introduction.- 4-2 Normalization of the Governing Equations.- a. A Procedure for Normalization.- b. Meaning of Normalized Governing Equations.- 4-3 Conditions Required for Rigorous Solution of the Canonical Problem of Similitude and Dimensional Analysis Using Normalized Governing Equations.- 4-4 Basis of Improved Correlations.- a. General Basis.- b. Homogeneous Equations.- 4-5 Relations among Elementary Processes.- a. Model Laws, Similitude, and Analogues.- b. An Alternative Procedure.- c. A Remark on Force Ratios.- d. Relation among Dimensional Analysis, Governing Equations, and Boundary Conditions Internal and External Similarity.- 4-6 Approximation Theory.- a. Extension to New Classes of Information by Approximation Theory.- b. Classification of Problems and Difficulties in Approximation Theory.- c. Conditions Required for Approximation Theory.- 4-7 Some Problems Involving Uniform Behavior.- 4-8 Nonuniform Behavior-Boundary Layer Methods.- a. Use of Physical Data Alone.- b. Zonal Estimates.- 4-9 Nonuniform Behavior-Expansion Methods and Uniformization.- a. Poincare's Expansion.- b. Lighthill's Expansion.- c. WKBJ Expansion.- d. Inner and Outer Expansions.- 4-10 Processes Involving Transformations of Variables.- a. Absorption of Parameters and Natural Coordinates.- b. Supersonic and Transonic Similarity Rules.- c. Reduction in Number of Independent Variables - Separation and Similarity Coordinates 179.- 4-11 Summary and Conclusions.- a. Classification of Types of Similitude-Information Achievable from Fractional Analysis of Governing Equations.- b. Various Viewpoints-Relations among Invariance, Transformations, and Similitude.- c. Final Remarks.- 5 Summary and Comparison of Methods.- 5-1 Introduction.- 5-2 Summary of Methods.- a. The Pi Theorem.- b. The Method of Similitude.- c. Use of Governing Equations.- 5-3 Comparison of Methods.- a. Power.- b. Rigor.- c. Accuracy.- d. Simplicity.- e. Input Information.- 5-4 Concluding Remarks.- a. Utility of Various Methods.- b. Implications in Teaching.- c. Possible Further Development.- d. Final Remark.- References.

Abstract The specific heat‐release rate is the molecular‐level fire response of a burning polymer. The Federal Aviation Administration obtains the specific heat‐release rate of milligram samples by analyzing the oxygen consumed by the complete combustion of the pyrolysis gases during a linear heating program. Dividing the specific heat‐release rate (W/g) by the rate of the temperature rise (K/s) of a sample during a test gives a material fire parameter with the units (J/g K) and significance of the heat (release) capacity. The heat‐release capacity appears to be a true material property that is rooted in the chemical structure of the polymer and is calculable from additive molar group contributions. Hundreds of polymers of known chemical compositions have been tested to date, providing over 40 different empirical molar group contributions to the heat‐release capacity. Measured and calculated heat‐release capacities for over 80 polymers agree to within ±15%, suggesting a new capability for predicting flammability from the polymer chemical structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 548–563, 2003

Earth-abundant nickel is a typical non-noble-metal cocatalyst used for photocatalytic hydrogen evolution (PHE). Ni nanoparticles, however, tend to aggregate during the hydrogen production process, significantly lowering their PHE activity. To avoid aggregation, we used single atom form Ni and anchored them on vacancies in nitrogen-doped graphene (Ni-NG) as a cocatalyst for PHE. We demonstrated that Ni-NG is a robust and highly active cocatalyst for PHE from water. With only 0.0013 wt % of Ni loading, the PHE activity of composite Ni-NG/CdS photocatalyst improves by 3.4 times compared to that of NG/CdS, and it does not decay even after 10 rounds of 5-hour running. The quantum efficiency of Ni-NG/CdS for PHE reaches 48.2% at 420 nm, one of the highest efficiencies for non-noble-metal-based cocatalysts reported in the literature. Photoluminescence spectral analyses and electrochemical examinations indicated that Ni-NG coupled to CdS serves not only as an electron storage medium to suppress electron–hole recombination but also as an active catalyst for proton reduction reaction. Density functional theory calculations show that the high activity of Ni-NG/CdS composite results from the single Ni atoms trapped in NG vacancies, which significantly reduces the activation energy barrier of the hydrogen evolution reaction. This research may be valuable for developing robust and highly active noble metal free cocatalysts for solar hydrogen production.

Brockner and Adsit (1986) found that satisfaction with an exchange relationship was more strongly related to perceptions of equity among men than women. Kahn (1972) reported that men were more likely than women to distribute outcomes to individuals in direct proportion to their input. We evaluated potential gender differences among 12,979 personnel in 30 different organizational systems in (a) correlations between fairness and job satisfaction scores and (b) standardized group differences in the perceived amounts of pay and promotion fairness and expressed levels of facet and global job satisfaction. The fairness-satisfaction relationship was not higher for men, and there were no practical differences in fairness perceptions and job satisfaction between men and women.

Abstract The statistical properties of turbulence at upper levels in the atmosphere [upper troposphere and lower stratosphere (UTLS)] are still not well known, partly because of the lack of adequate routine observations. This is despite the obvious benefit that such observations would have for alerting aircraft of potentially hazardous conditions, either in real time or for route planning. To address this deficiency, a research project sponsored by the Federal Aviation Administration has developed a software package that automatically estimates and reports atmospheric turbulence intensity levels (as EDR ≡ ε 1/3 , where ε is the energy or eddy dissipation rate). The package has been tested and evaluated on commercial aircraft. The amount of turbulence data gathered from these in situ reports is unprecedented. As of January 2014, there are ~200 aircraft outfitted with this system, contributing to over 137 million archived records of EDR values through 2013, most of which were taken at cruise levels of commercial aircraft, that is, in the UTLS. In this paper, techniques used for estimating EDR are outlined and comparisons with pilot reports from the same or nearby aircraft are presented. These reports allow calibration of EDR in terms of traditionally reported intensity categories (“light,” “moderate,” or “severe”). The results of some statistical analyses of EDR values are also presented. These analyses are restricted to the United States for now, but, as this program is expanded to international carriers, such data will begin to become available over other areas of the globe.

Abstract : A theory of boundary layer transition is presented which includes the effects of free-stream turbulence and pressure gradient. The basic notion underlying the development concerns the remoteness of the boundary layer vorticity from the surface. The theory agrees well with experimental data. The laminar boundary layer solutions of Pohlhausen and Falkner-Skan are used to calculate the effect of pressure gradient on transition. Engineering formulas are presented and one example is calculated showing the application of the theory to a body of revolution. The theory can also indicate the effects of Mach number and heat transfer. (Author)

Spontaneous pupillary movements in darkness were recorded in \n1.healthy subjects of different ages when they were rested or fatigued, \n2.chronically tired subjects without known neurological defects, and \n3.patients with various neurological lesions. \n\nIn some of the experiments, local or systemic drugs were used. While the pupils are large and quiet in darkness when the subject is alert, they oscillate under the influence of tiredness. Waves of spontaneous pupillary contraction and dilation accompany periods of increasing sleepiness and spontaneous arousal until, at the moment immediately preceding sleep, the pupils become very small. The mechanism of these movements was analyzed and a simple test described which allows the objective determination of the degree of acute fatigue in a given subject at a given time. In the light of these results, the concepts of 'normal' and of 'pathologic' fatigue were discussed. \n\n

Following work on organizational citizenship behaviors (cf. Organ, 1988). the present study examined job satisfaction, perceptions of organizational support, and organizational commitment as predictors of organizational citizenship behaviors. Regression analyses on data collected from workers in a small tooling plant indicated that exchange ideology moderated the relationships between ratings of OCB's and organizational support scores. For tool workers whose attitudes and behaviors were more dependent on organization reinforcement, OCB ratings were positively related to organizational support. However, for those whose attitudes and behaviors were more independent of organization reinforcement. OCB ratings were considerably less related to organizational support scores. The pattern was similar for OCB ratings and job satisfaction scores. These data are consistent with those reported previously (e.g., Eisenberger. Huntington. Hutchinson, & Sowa, 1986) and suggest that the salience of job attitudes in the decision to manifest organizational citizenship behaviors may be influenced by the individual's exchange ideology.

OBJECTIVES: Historically, mechanically unstable fractures of the distal femur have been difficult to treat. Problems such as varus collapse, malunion, and nonunion frequently resulted before fixed-angle plates and indirect reduction techniques were popularized. More recently, the Less Invasive Stabilization System, or LISS (Synthes, Paoli, PA), has been designed to combine these 2 approaches with the intended goals of achieving adequate stable fixation and early healing. Early clinical results for the femoral Less Invasive Stabilization System have been promising. The purpose of this study is to evaluate the clinical results of patients with high energy, mechanically unstable fractures of the distal femur treated with the Less Invasive Stabilization System. DESIGN: Retrospective analysis of a treatment protocol, consecutive patient series. SETTING: Busy level II trauma center. PATIENTS /PARTICIPANTS: Twenty-six patients with 27 high-energy AO/OTA types A2, A3, C2, and C3 fractures of the distal femur. INTERVENTION: Treatment with indirect fracture reduction and internal distal femoral fixation using the Less Invasive Stabilization System. MAIN OUTCOME MEASUREMENTS: Clinical and radiographic assessment. RESULTS: Twenty-one patients with 22 fractures were available for evaluation at an average 19 months postinjury (range 12-35 months). The mechanism of injury included 12 motor vehicle collisions, 4 high falls, 5 motorcycle crashes, and 1 bicyclist struck by a car. Twenty patients had associated injuries. Six fractures were open. All fractures were comminuted; according to the AO/OTA fracture classification there were 4 A2, 3 A3, 12 C2, and 3 C3 fractures. All fractures healed without secondary surgeries at a mean of 13 weeks (range 7-16 weeks). There were no cases of failed fixation, implant breakage, or infection. Average joint line orientation relative to the femoral shaft axis (valgus) measured 99 degrees on postoperative radiographs and 99 degrees on final radiographs. A comparison of postoperative to healed final radiographs for each femur demonstrated no case with greater than a 3 degrees difference in either varus or valgus. Complications included 1 mal-union where the fracture was fixed in 8 degrees of valgus and 2 cases of external rotation between 10 degrees and 15 degrees. Painful hardware occurred in 4 patients, of which 3 underwent implant removal. The average knee range of motion was 5 degrees to 114 degrees. CONCLUSIONS: The Less Invasive Stabilization System allows for stable fixation and facilitates early healing in mechanically unstable high-energy fractures of the distal femur. There were no patients with fixation failure, varus collapse, or nonunion in this "at-risk" population. This treatment safely allows for immediate postoperative initiation of joint mobility and the progression of weight bearing with early radiographic signs of healing.

Sleepiness plays an important role in major crashes of commercial vehicles. Because determinants are likely to include inadequate sleep and sleep apnea, we evaluated the role of short sleep durations over 1 wk at home and sleep apnea in subjective sleepiness (Epworth Sleepiness Scale), objective sleepiness (reduced sleep latency as determined by the Multiple Sleep Latency Test), and neurobehavioral functioning (lapses in performance, tracking error in Divided Attention Driving Task) in commercial drivers. Studies were conducted in 247 of 551 drivers at higher risk for apnea and in 159 of 778 drivers at lower risk. A multivariate linear association between the sets of outcomes and risk factors was confirmed (p < 0.0001). Increases in subjective sleepiness were associated with shorter sleep durations but not with increases in severity of apnea. Increases in objective sleepiness and performance lapses, as well as poorer lane tracking, were associated with shorter sleep durations. Associations with sleep apnea severity were not as robust and not strictly monotonic. A significant linear association with sleep apnea was demonstrated only for reduced sleep latency. The effects of severe apnea (apnea-hypopnea index, at least 30 episodes/h), which occurred in 4.7%, and of sleep duration less than 5 h/night, which occurred in 13.5%, were similar in terms of their impact on objective sleepiness. Thus, addressing impairment in commercial drivers requires addressing both insufficient sleep and sleep apnea, the former being more common.

The heats of combustion for 49 commercial and developmental polymers of known chemical structure were determined using an oxygen bomb calorimeter according to standard methods. The experimental results were compared with thermochemical calculations of the net heat of combustion from oxygen consumption and the gross heat of combustion from group additivity of the heats of formation of products and reactants. The polymers examined were thermally stable, char forming thermoplastics and thermoset resins containing a significant degree of aromaticity and heteroatoms including — nitrogen, sulphur, phosphorus, silicon, and oxygen in linear and heterocyclic structures. The gross and net heats of combustion calculated from polymer enthalpies of formation and oxygen consumption thermochemistry were within 5% of the experimental values from oxygen bomb calorimetry. The heat released by combustion per gram of diatomic oxygen consumed in the present study was E=13.10±0.78 kJ/gO2 for polymers tested (n=48). This value is indistinguishable from the universal value E13.1 kJ/gO2 used in oxygen consumption combustion calorimetry. Published in 2000 by John Wiley & Sons Ltd.