Automation trust increases under high-workload multitasking scenarios involving risk

Cognition, Technology & Work - Trust is a critical construct that influences human–automation interaction in multitasking workspaces involving imperfect automation. Karpinsky et al. (Appl...     

Superconductivity in the two-band hubbard model

We present a study of superconducting correlations in a two-band Hubbard model with a wide band strongly hybridized with a narrow band in which an attractive on-site interaction is operating. The narrow band pairs can induce superconducting correlations in the wide band through hybridization interaction. A generalized gap function for the induced wide-band pairing is obtained and its properties in the intermediate interaction region are analysed. Relevance of the results to high-T _c superconductors is briefly discussed.     

The physical and chemical characteristics of the shell of air-entrained bubbles in cement paste

Recent research has suggested that the shell of an air-entrained void is important for resisting coalescence between air-voids and diffusion of gas from the surrounding fluid. The current paper describes the physical and chemical properties of an air-void shell during the first 2 h of hydration and chemical characteristics at 60 days. Results from this research suggest that the air-void shells found in air-entrained paste have varied physical properties and the crystalline material of these shells is largely made up of fine cement particles during the first 2 h of hydration. Observations of paste at 60 days of hydration suggest that the shell is made up of calcium silicate hydrate (C-S-H) with a morphology different from that in the bulk paste.     

An investigation of training strategies to improve alarm reactions

Researchers have suggested that operator training may improve operator reactions; however, researchers have not documented this for alarm reactions. The goal of this research was to train participants to react to alarms using sensor activity patterns. In Experiment 1, 80 undergraduates monitored a simulated security screen while completing a primary word search task. They received spatial, temporal, single sensor, or no training to respond to alarms of differing reliability levels. Analyses revealed more appropriate and quicker reactions when participants were trained and when the alarms were reliable. In Experiment 2, 56 participants practiced time estimation by simple repetition, performance feedback, or performance feedback and temporal subdivision. They then reacted to alarms based on elapsed time between sensor activity and alarm onset. Surprisingly, results indicated that participants did not benefit differentially from temporal interval training, focusing instead on advertised system reliability. Researchers should replicate these findings with realistic tasks and real-world complex task operators.     

An examination of the reactivity of fly ash in cementitious pore solutions

Fly ash is frequently used to replace cement in concrete, but it is difficult to predict performance based only on the oxide composition, which is typically the only compositional information available. In order to better utilize fly ash in concrete, it is important to develop more meaningful characterization methods and correlate these with performance. The research presented here uses a combination of analytical methods, including X-ray powder diffraction, scanning electron microscopy coupled with multispectral image analysis, and solution analysis to determine the compositions of the glassy phases in a specific fly ash and to examine the fly ash’s reactivity in late- and early-age cement pore solutions, ultrapure water, and sodium hydroxide. The dissolution of individual glassy phases in the fly ash was tracked over time and the precipitation of reaction products monitored. A high-calcium aluminosilicate glass was the most reactive, a low-calcium aluminosilicate glass was of intermediate reactivity and a medium-calcium aluminosilicate glass had the lowest reactivity in the solutions tested for a specific fly ash. This result suggests the glass composition has a strong effect on reactivity, but that that there is not a strict correlation between calcium content and glass reactivity.     

Comprehensive phase characterization of crystalline and amorphous phases of a Class F fly ash

A comprehensive approach to qualitative and quantitative characterization of crystalline and amorphous constituent phases of a largely heterogeneous Class F fly ash is presented. Traditionally, fly ash composition is expressed as bulk elemental oxide content, generally determined by X-ray fluorescence spectroscopy. However, such analysis does not discern between relatively inert crystalline phases and highly reactive amorphous phases of similar elemental composition. X-ray diffraction was used to identify the crystalline phases present in the fly ash, and the Rietveld quantitative phase analysis method was applied to determine the relative proportion of each of these phases. A synergistic method of X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and multispectral image analysis was developed to identify and quantify the amorphous phases present in the fly ash.