The methodology of digital image correlation of random white light speckle is applied to the measurement of strain in bovine retina tissue which is subjected to uniaxial tension loading.The digital image correlation compares an image of deformed "seeded" retinal tissue to an image of the same tissue in an undeformed state.The correlation of the deformed image with the undeformed image yields both the displacement and strain fields for the area of tissue which is being imaged.The "seeding" of the tissue is accomplished by randomly spreading micron sized steel spheres on the retinal tissue.The results of this study indicate that uniform strain fields are not obtained in simple tension tests of the non -homogeneous retinal tissue as one might assume in the mathematical modelling of such tests. The average strains in a center test section of the retinal strip are correlated and compared with the grip strains. In addition, the digital image correlation methodology is shown to have the capability to make predictions of strain in the proximity of blood vessels and other anomalies in the tissue.This feature of the digital imaging methodology yields valuable information concerning such problems as retinal tearing and separation.The mathematical and physical background of the digital image correlation methodology will be discussed. The limitations of this methodology to measure displacement and strain will be given.The experimental procedure which was used to test the bovine retina will be explained in detail and results from the uniaxial testing of this retina will be presented.
Analyses of aviation accidents ascribe about 75% of all incidents to human (Pilot) behaviour. A strong effort is being made to improve ergonomic cockpit layout, because of dramatic changes in the airspace structure, the increase in air traffic, and larger aircraft. One part of an interdisciplinary research project investigates the potential of stereoscopic flight-guidance displays in order to improve pilots ' situation awareness.This experimental approach, which aims to research and apply ergonomic design recommendations for stereoscopic flight displays, is based upon a new type of perspective flight-guidance display. The examination of existing research regarding stereoscopic flight displays reveals a lack of basic knowledge, as well as a need for further systematic research into cockpit application.Thus the project contains experiments on different levels of abstraction, ranging from classic parameter experiments to flight simulator tests. Both current knowledge and recent discoveries are applied to superimposed 2-D fi ight parameters and to real and synthetic 8-D elements, such as a perspective landscape, other airplanes or flight prediction. The stereoscopic layout takes into consideration specific informational needs within different flight phases and is evaluated by means of pilot performance and pilot strain. Selected symbols of the flight guidance display and actual results are presented as examples of the research approach.
As part of an interdisciplinary research project, sponsored by the German Research Community (DFG), the Darmstadt University of Technology investigates the potential offered by stereoscopic flight guidance displays for improving pilot situation awareness. The research aims to formulate ergonomic design recommendations for this type of display.Recent developments in display technology offer new opportunities to improve human-machine interfaces in the cockpit. The utilization of three-dimensional display symbology, as a depiction of three-dimensional sensor or database information, has become an accepted practice in modern enhanced and synthetic vision systems. Nevertheless, the information is depicted on a conventional two-dimensional screen. This can cause problems and errors during the cognitive process of depth perception. The application of stereoscopic technology can add an additional cue which is intuitively seized by the observer.The project concentrates on stereoscopic perspective flight guidance displays as a head down display. The extension to other display types like navigation or head-up display is possible. Because of the complexity of a modern synthetic vision display, the project contains experiments on different levels of abstraction, ranging from classic parameter experiments to flight simulator tests. The stereoscopic layout takes into consideration specific informational needs within different flight phases and is evaluated by means of pilot performance and pilot strain.
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