In Next Generation Air Transportation System (NextGen) operations, we expect that the demand-capacity balance can be achieved by selectively managing the airspace capacity in conjunction with managing the traffic demand. In Flexible Airspace Management (FAM), the airspace complexity can be assessed a few hours ahead in order to identify sectors that could exceed their defined traffic threshold as well as sectors that are under-utilized. Using various airspace optimization algorithms, airspace can be reconfigured to manage the existing traffic demand without moving aircraft away from their original user-preferred routes. A human-in-the-loop simulation study was conducted in 2009 to assess the impact of airspace reconfiguration on the controllers. The results from the objective data found that the acceptability of the boundary change and the associated workload were mainly affected by airspace volume change and aircraft that changed ownership. However, observations and subjective feedback have suggested that other cognitively-driven factors, such as spatial relationships between upstream/downstream sectors, may also play a role, especially in traffic situations where the airspace has only a few aircraft that change ownership but still has a high degree of airspace complexity associated with the reconfiguration. In this paper, we identify these factors and discuss the human factors issues that should be considered in designing the airspace and airspace transitions.
An exploratory human-in-the-loop study was conducted to better understand the impact of Dynamic Airspace Configuration (DAC) on air traffic controllers. To do so, a range of three progressively more aggressive algorithmic approaches to sectorizations were chosen. Sectorizations from these algorithms were used to test and quantify the range of impact on the controller and traffic. Results show that traffic count was more equitably distributed between the four test sectors and duration of counts over MAP were progressively lower as the magnitude of boundary change increased. However, taskload and workload were also shown to increase with the increase in aggressiveness and acceptability of the boundary changes decreased. Overall, simulated operations of the DAC concept did not appear to compromise safety. Feedback from the participants highlighted the importance of limiting some aspects of boundary changes such as amount of volume gained or lost and the extent of change relative to the initial airspace design.
The thermoelectric properties of sub-stoichiometric TiO2−x deposits produced by cascaded-plasma spray process are investigated from room-temperature to 750 K. Sub-stoichiometric TiO2−x deposits are formed through in-situ reaction of the TiO1.9 within the high temperature plasma flame and manipulated through introduction of varying amounts of hydrogen in the plasma. Although the TiO2−x particles experience reduction within plasma, it can also re-oxidize through interaction with the surrounding ambient atmosphere, resulting in a complex interplay between process conditions and stoichiometry. The deposits predominantly contain rutile phase with presence of Magneli phases especially under significantly reducing plasma conditions. The resultant deposits show sensitivity to thermoelectric properties and under certain optimal conditions repeatedly show Seebeck coefficients reaching values of −230 μV K−1 at temperatures of 750 K while providing an electrical conductivity of 5.48 × 103 S m−1, relatively low thermal conductivity in the range of 1.5 to 2 W m−1 K−1 resulting in power factor of 2.9 μW cm−1 K−2. The resultant maximum thermoelectric figure of merit value reached 0.132 under these optimal conditions. The results point to a potential pathway for a large-scale fabrication of low-cost oxide based thermoelectric with potential applicability at moderate to high temperatures.
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