A correlational approach to predicting operator status

This paper discusses a research approach for identifying and validating candidate physiological and behavioral parameters which can be used to predict the performance capabilities of aircrew and other system operators. In this methodology, concurrent and advance correlations are computed between predictor values and criterion performance measures. Continuous performance and sleep loss are used as stressors to promote performance variation. Preliminary data are presented which suggest dependence of prediction capability on the resource allocation policy of the operator

On Simulating the Proton-Irradiation of O2_2 and H2_2O Ices Using Astrochemical-type Models, with Implications for Bulk Reactivity

Many astrochemical models today explicitly consider the species that comprise the bulk of interstellar dust grain ice-mantles separately from those in the top few monolayers. Bombardment of these ices by ionizing radiation - whether in the form of cosmic rays, stellar winds, or radionuclide emission - represents an astrochemically viable means of driving a rich chemistry even in the bulk of the ice-mantle, now supported by a large body of work in laboratory astrophysics. In this study, using an existing rate equation-based astrochemical code modified to include a method of considering radiation chemistry recently developed by us, we attempted to simulate two such studies in which (a) pure O$_2$ ice at 5 K and, (b) pure H$_2$O ice at 16 K and 77 K, were bombarded by keV H$^+$ ions. Our aims are twofold: (1) to test the capability of our newly developed method to replicate the results of ice-irradiation experiments, and (2) to determine in such a well-constrained system how bulk chemistry is best handled using the same gas-grain codes that are used to model the interstellar medium (ISM). We find that our modified astrochemical model is able to reproduce both the abundance of O$_3$ in the 5 K pure O$_2$ ice, as well as both the abundance of H$_2$O$_2$ in the 16 K water ice and the previously noted decrease of hydrogen peroxide at higher temperatures. However, these results require the assumption that radicals and other reactive species produced via radiolysis react quickly and non-diffusively with neighbors in the ice.Comment: ApJ, accepted. 30 pages, 5 figure

Metallurgical Effects on Long-Term Creep-Rupture in a New Nickel-Based Alloy

A series of creep-rupture studies were conducted on a new nickel-based alloy, Inconel Alloy 740, for use in Advanced Ultrasupercritical (A-USC) Steam boiler applications. The research quantitatively showed, for the first time, that the formation of a small amount of eta phase during long-term creep testing at 750 degrees Celsius does not degrade the rupture strength or ductility of the alloy. A unique full-scale pressurized tubular creep test was conducted, and a new analysis methodology was developed to evaluate the effect of cold-straining on the creep performance of tube bends made from the alloy. The results showed that 15% cold-work was detrimental to creep strength and ductility in the alloy and lower strain limits should therefore be imposed for typical manufacturing processes. A comprehensive study on the influence of composition and grain size on the alloy was completed. The research focused on creep data analysis, microstructural studies, and computational thermodynamics and showed that grain size, not gamma prime volume fraction or eta phase formation, was the critical parameter influencing creep strength in the alloy. The research also showed that small changes in the aluminum to titanium ratio in the alloy dramatically change the eta phase thermal stability. Results suggests that a large amount of eta phase (above 7 volume %) may reduce creep-rupture ductility (but not strength); however, more research is needed to validate this finding. The accuracy of computational thermodynamics was established for volume fraction and thermal stability of eta phase formation, but deficiencies were noted in kinetic (eta phase precipitation) calculations. In summary, the research shows that provided cold-work and grain size are appropriately controlled, Inconel 740 has predictable creep strength and ductility despite the potential for variations in microstructure. This is most likely due to the formation of gamma prime denuded or precipitate free zones along grain boundaries where creep damage is concentrated

The Case of H2_2C3_3O Isomers, Revisited: Solving the Mystery of the Missing Propadienone

To date, two isomers of H$_2$C$_3$O have been detected, namely, propynal (HCCCHO) and cylclopropenone (c-H$_2$C$_3$O). A third, propadienone (CH$_2$CCO), has thus far eluded observers despite the fact that it is the lowest in energy of the three. This previously noted result is in contradiction of the minimum energy principle, which posits that the abundances of isomers in interstellar environments can be predicted based on their relative stabilities - and suggests, rather, the importance of kinetic over thermodynamic effects in explaining the role of such species. Here, we report results of \textit{ab initio} quantum chemical calculations of the reaction between H and (a) HC$_3$O, (b) H$_2$C$_3$O (both propynal and propadienone), and (c) CH$_2$CHCO. We have found that, among all possible reactions between atomic hydrogen and either propadienone or propynal, only the destruction of propadienone is barrierless and exothermic. That this destruction pathway is indeed behind the non-detection of CH$_2$CCO is further suggested by our finding that the product of this process, the radical CH$_2$CHCO, can subsequently react barrierlessly with H to form propenal (CH$_2$CHCHO) which has, in fact, been detected in regions where the other two H$_2$C$_3$O isomers are observed. Thus, these results not only shed light on a previously unresolved astrochemical mystery, but also further highlight the importance of kinetics in understanding the abundances of interstellar molecules.Comment: ApJ, accepted: 14 pages, 2 figure

Training Characteristics of the Criterion Task Set Workload Assessment Battery

An evaluation of the Criterion Task Set was performed to determine the training requirements for the various tasks. Twenty subjects were divided into four groups. One group trained on all nine tasks in the battery. The other three groups trained on different three-task subsets. All subjects trained for two hours per day on five consecutive days. Response time, accuracy and subjective workload measures were obtained for each trial.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Vigilant Warrior™: A Selection Tool for Vigilance Performance

In this paper, we describe an individual differences model of vigilance performance—the ability to maintain one’s focus of attention and remain alert for prolonged periods of time—and summarize our model evaluation research. Our goal was an automated test battery (Vigilant Warrior™) that could be employed to select personnel with superior abilities for assignment to critical vigilance duties. Thus, we conducted extensive laboratory research to identify an optimal set of vigilance predictors and validate them against a simulated, real-world, electronic-display, battlefieldmonitoring task with high vigilance requirements. The results confirmed that an objective, Short Vigilance Task (SVT), coupled with analytic skill and stress-coping measures, could account for 33% or more of the criterion variance. Moreover, the SVT was the most powerful predictor in the battery. Analytic skill and situational variables contributed to vigilance performance, but to a lesser degree. Vigilant Warrior™ is currently receiving extensive field testing in military settings