592 research outputs found
Pilotsâ visual scan pattern and situation awareness in flight operations
Introduction: Situation awareness (SA) is considered an essential prerequisite for safe flying. If the impact of visual scanning patterns on a pilotâs situation awareness could be identified in flight operations, then eye-tracking tools could be integrated with flight simulators to improve training efficiency. Method: Participating in this research were 18 qualified, mission-ready fighter pilots. The equipment included high-fidelity and fixed-base type flight simulators and mobile head-mounted eye-tracking devices to record a subjectâs eye movements and SA while performing air-to-surface tasks. Results: There were significant differences in pilotsâ percentage of fixation in three operating phases: preparation (M = 46.09, SD = 14.79), aiming (M = 24.24, SD = 11.03), and release and break-away (M = 33.98, SD = 14.46). Also, there were significant differences in pilotsâ pupil sizes, which were largest in the aiming phase (M = 27,621, SD = 6390.8), followed by release and break-away (M = 27,173, SD = 5830.46), then preparation (M = 25,710, SD = 6078.79), which was the smallest. Furthermore, pilots with better SA performance showed lower perceived workload (M = 30.60, SD = 17.86), and pilots with poor SA performance showed higher perceived workload (M = 60.77, SD = 12.72). Pilotsâ percentage of fixation and average fixation duration among five different areas of interest showed significant differences as well. Discussion: Eye-tracking devices can aid in capturing pilotsâ visual scan patterns and SA performance, unlike traditional flight simulators. Therefore, integrating eye-tracking devices into the simulator may be a useful method for promoting SA training in flight operations, and can provide in-depth understanding of the mechanism of visual scan patterns and information processing to improve training effectiveness in aviation
Pilotsâ visual scan pattern and attention distribution during the pursuit of a dynamic target
Introduction: The current research is investigating pilotsâ visual
scan patterns in order to assess attention distribution during
air-to-air manoeuvers. Method: A total of thirty qualified
mission-ready fighter pilots participated in this research. Eye
movement data were collected by a portable head-mounted eye-tracking
device, combined with a jet fighter simulator. To complete the task,
pilots have to search for, pursue, and lock-on a moving target whilst
performing air-to-air tasks. Results: There were significant
differences in pilotsâ saccade duration (msec) in three operating
phases including searching (M=241, SD=332), pursuing (M=311, SD=392),
and lock-on (M=191, SD=226). Also, there were significant differences
in pilotsâ pupil sizes (pixel2) of which lock-on phase was the largest
(M=27237, SD=6457), followed by pursuing (M=26232, SD=6070), then
searching (M=25858, SD=6137). Furthermore, there were significant
differences between expert and novice pilots on the percentage of
fixation on the HUD, time spent looking outside the cockpit, and the
performance of situational awareness (SA). Discussion: Experienced
pilots have better SA performance and paid more attention to the HUD
but focused less outside the cockpit when compared with novice pilots.
Furthermore, pilots with better SA performance exhibited a smaller
pupil size during the operational phase of lock-on whilst pursuing
a dynamic target. Understanding pilotsâ visual scan patterns and
attention distribution are beneficial to the design of interface
displays in the cockpit and in developing human factors training
syllabi to improve safety of flight operations
The impact of alerting designs on air traffic controller's eye movement patterns and situation awareness
This research investigated controllerâ situation awareness by comparing COOPANSâs acoustic alerts with newly designed semantic alerts. The results demonstrate that ATCOsâ visual scan patterns had significant differences between acoustic and semantic designs. ATCOs established different eye movement patterns on fixations number, fixation duration and saccade velocity. Effective decision support systems require human-centred design with effective stimuli to direct ATCOâs attention to critical events. It is necessary to provide ATCOs with specific alerting information to reflect the nature of of the critical situation in order to minimize the side-effects of startle and inattentional deafness. Consequently, the design of a semantic alert can significantly reduce ATCOsâ response time, therefore providing valuable extra time in a time-limited situation to formulate and execute resolution strategies in critical air safety events. The findings of this research indicate that the context-specified design of semantic alerts could improve ATCOâs situational awareness and significantly reduce response time in the event of Short Term Conflict Alert activation which alerts to two aircraft having less than the required lateral or vertical separation
Pilotâs attention distributions between chasing a moving target and a stationary target
Introduction: Attention plays a central role in cognitive processing; ineffective attention may induce accidents in flight operations. The objective of current research was to examine military pilotsâ attention distributions between chasing a moving target and a stationary target.
Method: Thirty-seven mission-ready F-16 pilots participated in the current research. Subjectsâ eye movements were collected by a portable head-mounted eye-tracker during tactical training in a flight simulator. The scenarios of chasing a moving target (air-to-air) and a stationary target (air-to-surface) consist of three operational phases; searching, aiming and lock-on to the targets.
Results: The findings demonstrated significant differences in pilotsâ percentage of fixation during searching phase between air-to-air (M=37.57, SD=5.72) and air-to-surface (M=33.54, SD=4.68). Fixation duration can indicate pilotsâ sustained attention to the trajectory of a dynamic target during dog-fight manoeuvers. Aiming for the stationary target with larger pupil size (M=27105 pixel2, SD=6565 pixel2) reflects higher cognitive loading than aiming to the dynamic target (M=23864 pixel2, SD=8762 pixel2).
Discussion: Pilotsâ visual behavior is not only closely related to attention distribution, but also significantly associated with task characteristics. Military pilots demonstrated various visual scan patterns for searching and aiming to different types of targets based on the research settings of flight simulator. The findings would facilitate system designersâ understandings of military pilotsâ cognitive processes during tactical operations. It will assist human-centered interface design to improve pilotsâ situational awareness. The application of an eye-tracking device integrated with a flight simulator is a feasible and cost-effective intervention to improve efficiency and safety of tactical training
Interface design on cabin pressurization system affecting pilot's situation awareness: the comparison between digital displays and pointed displays
The fundamental approach to improve pilotsâ situation awareness would be to reorganise and restructure the presentation of information to fit pilotâs cognitive model on the flight deck. This would facilitate pilotsâ perception, understanding, and projection hence making it easier to find the relevant targets. Sixty pilots (30 B-737 pilots; 30 B-777 pilots) participated in this research to investigate pilotsâ situation awareness while interacting with digital displays and moving pointed needle displays on cabin pressurization system. The results have shown significant differences on pilotsâ perception, understanding and overall situation awareness between digital display and pointed display on the flight deck. Pilots significantly preferred the digital design Cabin Pressurization System which is consistent with the proximity compatibility principle, and the position of the display on the centre instrument panel is easily accessible to both pilots and does not require large head movements. There are some recommendations on the cabin pressurization design including the size of outflow valve position indicator which should be significantly increased to provided saliency of information; colour coding should be used on cabin altitude and differential pressure indicator to mark critical cabin altitude; and standard operating procedures shall include cabin altitude and differential pressure reading by pilot monitoring. The final and completed solution to the issues on the cabin pressurization system is to redesign the scattered pointed displays as integrated digital displays to fit the human-centred principle
Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process
One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E(2)(H) mode intensity and increase of E(1)(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods
Current-voltage correlations in interferometers
We investigate correlations of current at contacts and voltage fluctuations
at voltage probes coupled to interferometers. The results are compared with
correlations of current and occupation number fluctuations at dephasing probes.
We use a quantum Langevin approach for the average quantities and their
fluctuations. For higher order correlations we develop a stochastic path
integral approach and find the generating functions of voltage or occupation
number fluctuations. We also derive a generating function for the joint
distribution of voltage or occupation number at the probe and current
fluctuations at a terminal of a conductor. For energy independent scattering we
found earlier that the generating function of current cumulants in
interferometers with a one-channel dephasing or voltage probe are identical.
Nevertheless, the distribution function for voltage and the distribution
function for occupation number fluctuations differ, the latter being broader
than that of former in all examples considered here.Comment: 23 pages, 10 figures, minor changes, additional appendix, added
reference
Spectral filtering of multiple directly modulated channels for WDM access networks by using an FP etalon
[[abstract]]Spectral and waveform reshaping schemes can enhance the transmission distance of fiber links that use directly modulated lasers as transmitters. We prove the feasibility of using a simple FabryâPerot (FP) etalon as the spectral reshaper for applications in wavelength division multiplexing (WDM) access networks. The transient chirp and adiabatic chirp of a directly modulated laser are analyzed in detail by using the time-resolved chirp measurement. The effects of the original extinction ratio and the adiabatic chirp on the spectral reshaping are clarified to obtain the optimal operation conditions. It is shown that placing a single-cavity FP etalon filter after multiple 10 Gbits/s directly modulated lasers can extend their transmission distances from 10 to 50 km in the 1.55 m wavelength window. Due to the limited filtering capability of the etalon, the choice of the original extinction ratio and finesse of the etalon is discussed in detail from the experiments and simulation.[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]çŽæŹ[[booktype]]é»ć
Pervasive brain monitoring and data sharing based on multi-tier distributed computing and linked data technology
EEG-based Brain-computer interfaces (BCI) are facing grant challenges in their real-world applications. The technical difficulties in developing truly wearable multi-modal BCI systems that are capable of making reliable real-time prediction of usersâ cognitive states under dynamic real-life situations may appear at times almost insurmountable. Fortunately, recent advances in miniature sensors, wireless communication and distributed computing technologies offered promising ways to bridge these chasms. In this paper, we report our attempt to develop a pervasive on-line BCI system by employing state-of-art technologies such as multi-tier fog and cloud computing, semantic Linked Data search and adaptive prediction/classification models. To verify our approach, we implement a pilot system using wireless dry-electrode EEG headsets and MEMS motion sensors as the front-end devices, Android mobile phones as the personal user interfaces, compact personal computers as the near-end fog servers and the computer clusters hosted by the Taiwan National Center for High-performance Computing (NCHC) as the far-end cloud servers. We succeeded in conducting synchronous multi-modal global data streaming in March and then running a multi-player on-line BCI game in September, 2013. We are currently working with the ARL Translational Neuroscience Branch and the UCSD Movement Disorder Center to use our system in real-life personal stress and in-home Parkinsonâs disease patient monitoring experiments. We shall proceed to develop a necessary BCI ontology and add automatic semantic annotation and progressive model refinement capability to our system
- âŠ