Perceptual factors that influence use of computer enhanced visual displays

This document is the final report for the NASA/Langley contract entitled 'Perceptual Factors that Influence Use of Computer Enhanced Visual Displays.' The document consists of two parts. The first part contains a discussion of the problem to which the grant was addressed, a brief discussion of work performed under the grant, and several issues suggested for follow-on work. The second part, presented as Appendix I, contains the annual report produced by Dr. Ann Fulop, the Postdoctoral Research Associate who worked on-site in this project. The main focus of this project was to investigate perceptual factors that might affect a pilot's ability to use computer generated information that is projected into the same visual space that contains information about real world objects. For example, computer generated visual information can identify the type of an attacking aircraft, or its likely trajectory. Such computer generated information must not be so bright that it adversely affects a pilot's ability to perceive other potential threats in the same volume of space. Or, perceptual attributes of computer generated and real display components should not contradict each other in ways that lead to problems of accommodation and, thus, distance judgments. The purpose of the research carried out under this contract was to begin to explore the perceptual factors that contribute to effective use of these displays

Strain Concentrations in Polyethylene Geomembranes Adjacent to Seams and Scratches

abstract: Laboratory testing was conducted to quantify strain concentrations adjacent to seams and scratches in high density polyethylene (HDPE) geomembranes. The tensile strain profile of remnants meeting the ASTM criteria for wide-width tensile testing from samples of field seams recovered for construction quality assurance testing was evaluated using digital image correlation (DIC). Strains adjacent to scratches on laboratory prepared samples loaded in tension were also measured using DIC. The tensile strain in the zone adjacent to a seam and the tensile strain adjacent to a scratch were compared to the tensile strains calculated using theoretical strain concentration factors. The relationship between the maximum tensile strain adjacent to a seam and the global nominal strain in the sample was quantified for textured and smooth geomembranes of common thicknesses. Using statistical analysis of the data, bounds were developed for the allowable nominal tensile strain expected to induce maximum tensile strains adjacent to the seam less than or equal to the typical yield strain of HDPE geomembranes, at several confidence levels. Where nominal strain is the global or average strain applied to the sample and maximum strain is the largest tensile strain induced in the sample. The reduction in the nominal yield strain due to a scratch in a HDPE geomembrane was also quantified. The yield strain was approximately the same as predicted using theoretical strain concentration factors. The difference in the average measured maximum strains adjacent to the seams of textured and smooth HDPE geomembranes was found to be statistically insignificant. However, maximum strains adjacent to extrusion welded seams were somewhat greater than adjacent to fusion welded seams for nominal strains on the order of 3% to 4%. The results of the testing program suggest that the nominal tensile strain should be limited to 4% around dual hot wedge seams and 3% around extrusion fillet seams to avoid maximum strains equal to 11%, a typical yield strain for HDPE geomembranes.Dissertation/ThesisMasters Thesis Civil Engineering 201

Evaluating the effects of bilingual traffic signs on driver performance and safety

Variable Message Signs (VMS) can provide immediate and relevant information to road users and bilingual VMS can provide great flexibility in countries where a significant proportion of the population speak an alternative language to the majority. The study reported here evaluates the effect of various bilingual VMS configurations on driver behaviour and safety. The aim of the study was to determine whether or not the visual distraction associated with bilingual VMS signs of different configurations (length, complexity) impacted on driving performance. A driving simulator was used to allow full control over the scenarios, road environment and sign configuration and both longitudinal and lateral driver performance was assessed. Drivers were able to read one and two-line monolingual signs and two-line bilingual signs without disruption to their driving behaviour. However, drivers significantly reduced their speed in order to read four-line monolingual and four-line bilingual signs, accompanied by an increase in headway to the vehicle in front. This implies that drivers are possibly reading the irrelevant text on the bilingual sign and various methods for reducing this effect are discussed

Safety implications of a pedestrian protection system - the driver's point of view

Pedestrians can sustain fatal injuries, even in low-speed collisions. Active pedestrian protection systems, such as an Active Bonnet, have been shown to mitigate the outcome of a collision. The study reported here aimed to discover whether such a system could have any negative impacts on the driver. One of the characteristics of the Active Bonnet is that, when deployed, it partially occludes the driver’s visual field. This driving simulator study quantified the amount of disruption to normal driving when the system is deployed, for drivers of three different heights. Curved and straight sections of road were simulated and occlusion time varied between 0.5 seconds and 4 seconds. In general, drivers’ reaction to the deployment of the bonnet was to decrease their speed; this was most noticeable for drivers at the lowest eye-height both in the straight and curved sections of road. On straight sections of road, drivers were able to maintain vehicle speed and lateral control for up to three seconds of partial occlusion of the visual field. For curved sections, this upper threshold was found to be only two seconds, reflecting the higher workload in the curved sections. When occlusion was lifted, drivers tended to then deviate in lane – a possible “panic” effect. As drivers became more familiar with the system, they applied the brakes less. In conclusion, according to the scenarios tested in this study, drivers appear to be able to cope with partial occlusions of two seconds or less and there is some evidence that a panic reaction can be lessened by familiarisation

OAST space research and technology applications: Technology transfer successes

The ultimate measure of success in the Space Research and Technology Program is the incorporation of a technology into an operational mission. Charts are presented that describe technology products which OAST has helped support that (1) have been used in a space mission, (2) have been incorporated into the baseline design of a flight system in the development phase, or (3) have been picked up by a commercial or other non-NASA user. We hope that these examples will demonstrate the value of investment in technology. Pictured on the charts are illustrations of the technology product, the mission or user which has incorporated the technology, and where appropriate, results from the mission itself

A spatial framework for prioritizing biochar application to arable land: A case study for Sweden

The biochar-agriculture nexus can potentially generate several benefits ranging from soil carbon sequestration to the reduction in nutrient leaching from arable soils. However, leveraging these benefits requires spatially-explicit information on suitable locations for biochar application. This study provides a flexible multicriteria framework that delivers spatial indications on biochar prioritization through a biochar use indication map (BUIM). The framework was exemplified as a case study for Swedish arable land through three different prioritization narratives. The BUIM for all the narratives revealed that a significant fraction of the Swedish arable land could potentially benefit from biochar application. Furthermore, arable land that scored high for a given narrative did not necessarily score high in the others, thus indicating that biochar application schemes can be adjusted to various objectives and local needs. The framework presented here aims to promote the exploration of different avenues for deploying biochar in the agricultural sector

A spatial framework for prioritizing biochar application to arable land: A case study for Sweden

The biochar-agriculture nexus can potentially generate several benefits ranging from soil carbon sequestration to the reduction in nutrient leaching from arable soils. However, leveraging these benefits requires spatially-explicit information on suitable locations for biochar application. This study provides a flexible multicriteria framework that delivers spatial indications on biochar prioritization through a biochar use indication map (BUIM). The framework was exemplified as a case study for Swedish arable land through three different prioritization narratives. The BUIM for all the narratives revealed that a significant fraction of the Swedish arable land could potentially benefit from biochar application. Furthermore, arable land that scored high for a given narrative did not necessarily score high in the others, thus indicating that biochar application schemes can be adjusted to various objectives and local needs. The framework presented here aims to promote the exploration of different avenues for deploying biochar in the agricultural sector