ORCID ID: 0000-0001-5462-524X (J.P.).Dicot leaves are composed of a heterogeneous mosaic of jigsaw puzzle piece-shaped pavement cells that vary greatly in size and the complexity of their shape. Given the importance of the epidermis and this particular cell type for leaf expansion, there is a strong need to understand how pavement cells morph from a simple polyhedral shape into highly lobed and interdigitated cells. At present, it is still unclear how and when the patterns of lobing are initiated in pavement cells, and one major technological bottleneck to addressing the problem is the lack of a robust and objective methodology to identify and track lobing events during the transition from simple cell geometry to lobed cells. We developed a convex hull-based algorithm termed LobeFinder to identify lobes, quantify geometric properties, and create a useful graphical output of cell coordinates for further analysis. The algorithm was validated against manually curated images of pavement cells of widely varying sizes and shapes. The ability to objectively count and detect new lobe initiation events provides an improved quantitative framework to analyze mutant phenotypes, detect symmetry-breaking events in time-lapse image data, and quantify the time-dependent correlation between cell shape change and intracellular factors that may play a role in the morphogenesis process.
A consortium of government, industry and academia is currently working to establish minimum operational performance standards for Detect and Avoid (DAA) and Control and Communications (C2) systems in order to enable broader integration of Unmanned Aircraft Systems (UAS) into the National Airspace System (NAS). One subset of these performance standards will need to address the DAA display requirements that support an acceptable level of pilot performance. From a pilot's perspective, the DAA task is the maintenance of self separation and collision avoidance from other aircraft, utilizing the available information and controls within the Ground Control Station (GCS), including the DAA display. The pilot-in-the-loop DAA task requires the pilot to carry out three major functions: 1) detect a potential threat, 2) determine an appropriate resolution maneuver, and 3) execute that resolution maneuver via the GCS control and navigation interface(s). The purpose of the present study was to examine two main questions with respect to DAA display considerations that could impact pilots' ability to maintain well clear from other aircraft. First, what is the effect of a minimum (or basic) information display compared to an advanced information display on pilot performance? Second, what is the effect of display location on UAS pilot performance? Two levels of information level (basic, advanced) were compared across two levels of display location (standalone, integrated), for a total of four displays. The authors propose an eight-stage pilot-DAA interaction timeline from which several pilot response time metrics can be extracted. These metrics were compared across the four display conditions. The results indicate that the advanced displays had faster overall response times compared to the basic displays, however, there were no significant differences between the standalone and integrated displays. Implications of the findings on understanding pilot performance on the DAA task, the development of DAA display performance standards, as well as the need for future research are discussed.
Unmanned aerial systems (UAS) are starting to access manned airspace today and this trend will grow substantially as the number of UAS and their associated missions expand.A key challenge to safely integrating UAS into the National Airspace System (NAS) is providing a reliable means for UAS to sense and avoid (SAA) other aircraft. The US Air Force is addressing this challenge through the Common Airborne Sense and Avoid (C-ABSAA) program. C-ABSAA is developing a sophisticated "sense-and-avoid" capability that will be integrated onboard larger UAS. This paper summarizes human factors activities associated with enabling this revolutionary capability. Existing knowledge was reviewed and crosschecked to formulate a first draft set of minimum information requirements for SAA tasks. A gap analysis spawned an intruder depiction study and an operator requirements survey. Finally, operator interface prototypes were designed to support: 1) a minimum information set for SAA, as well as 2) the availability of several advanced situation assessment and maneuver guidance aids. Through collaboration with NASA's UAS in the NAS project, these concepts were incorporated into a UAS ground control station for formal evaluation through a high fidelity human-in-the-loop simulation.
The desire for Unmanned Aerial Systems (UAS) to routinely access manned airspace has grown substantially due to the proliferation of UAS and their associated applications. A key challenge to safely integrating UAS into the National Airspace System (NAS) is providing a reliable means for UAS to sense and avoid (SAA) other aircraft. The US Air Force is addressing this challenge through the Common Airborne Sense and Avoid (C-ABSAA) program. C-ABSAA is developing a sophisticated SAA capability that will be integrated onboard larger UAS. This paper summarizes key human factors efforts to develop a SAA traffic display with the appropriate level of information needed to aid the pilot in successfully maintaining self-separation and collision avoidance from other aircraft. The present study examined performance differences between candidate SAA displays as well as the most efficient manner to communicate recommended maneuvers. Fifteen Class 3-5 UAS military pilots compared five stand-alone SAA displays across two weather constraint levels (no weather, weather). Results indicated that the Banding Display tended to be most effective in aiding pilot performance during a SAA situation, with faster response times, less change in response time between weather conditions, no collision avoidance alert violations, and favorable subjective feedback. Implications of these findings on determining the acceptable level of information needed on a SAA display to aid pilot performance are discussed.
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