Accurate assessment of road luminance provided by overhead streetlights helps to optimize the visibility of objects on the road and therefore promotes driver safety, while minimizing energy consumption. To calculate road luminance, the road surface reflectivity has to be known. Odyssey Energy Limited has developed a prototype system that has the potential to determine the road reflectivity properties at high speed. In this thesis, an investigation into the prototype system has been conducted and further enhancement and redesign has been done. A portable on-site road surface reflectivity measurement system that complies with the Commission Internationale de I' Eclairage (CIE) standard was developed. The road test of this new system has been carried out on a series of Hamilton city roads. It proved that the new system is capable of measuring the road surface reflectivity and classifying the road into its appropriate R class according to the CIE standards specified in street lighting design criteria. Later the OEL prototype system was calibrated against the new system to find out the correlation between the two systems.

No description available.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

No description available.

This study evaluated the usefulness of a psychophysical model as part of a new ANSI/HFES 100 standard for CRT flicker. A graph based flicker prediction method developed from Farrell, 1987 was evaluated. The Farrell model is based on phosphor persistence, screen luminance, display size, and viewing distance. The graph based method assumes a worse case scenario (i.e. a white display screen shown on a display with P4 phosphor). While the Farrell model requires photometric measurements to be taken using special equipment, the graph based method require a knowledge of the display size, viewing distance, screen luminance, and refresh rate. Ten participants viewed different display sizes from different eccentricities under different levels of illumination and luminance. In each condition the display's refresh rate was manipulated using the Method of Limits to determine the critical flicker frequency (CFF). An Analysis of Variance was used to detirmine significant effects on CFF. CFF increased with increasing luminance and display size. Adequate illumination significantly increased CFF. A viewing eccentricity of 30 degrees (measured horizontally from the center of the screen) produced the highest CFF values. Under the conditions of 30 degrees eccentricity and 250 to 500 lux illumination, observed 50% CFF threshold values exceeded the 90% CFF threshold values predicted by the graph based method. This study demonstates that when tested under the same conditions it was developed under, the Farrell method successfully predicts flicker perception; however, when tested under conditions representative of real world working conditions, the Farrell model fails to predict flicker perception. New parameters for the model are suggested.<INPUT TYPE="hidden" NAME="abstract" VALUE="This study evaluated the usefulness of a psychophysical model as part of a new ANSI/HFES 100 standard for CRT flicker. A graph based flicker prediction method developed from Farrell, 1987 was evaluated. The Farrell model is based on phosphor persistence, screen luminance, display size, and viewing distance. The graph based method assumes a worse case scenario (i.e. a white display screen shown on a display with P4 phosphor). While the Farrell model requires photometric measurements to be taken using special equipment, the graph based method require a knowledge of the display size, viewing distance, screen luminance, and refresh rate. Ten participants viewed different display sizes from different eccentricities under different levels of illumination and luminance. In each condition the display's refresh rate was manipulated using the Method of Limits to determine the critical flicker frequency (CFF). An Analysis of Variance was used to detirmine significant effects on CFF. CFF increased with increasing luminance and display size. Adequate illumination significantly increased CFF. A viewing eccentricity of 30 degrees (measured horizontally from the center of the screen) produced the highest CFF values. Under the conditions of 30 degrees eccentricity and 250 to 500 lux illumination, observed 50% CFF threshold values exceeded the 90% CFF threshold values predicted by the graph based method. This study demonstates that when tested under the same conditions it was developed under, the Farrell method successfully predicts flicker perception; however, when tested under conditions representative of real world working conditions, the Farrell model fails to predict flicker perception. New parameters for the model are suggested." / Master of Science

When something is not attended to by a person, even when it is right before them, they won't perceive it. This is known as inattentional blindness (Mack & Rock, 1998). Sometimes information missed due to inattentional blindness is trivial but inattentional blindness can become a problem when it hinders people from responding to something appropriately when a response is needed. When a visual cue is missed there can be an impact on decision-making. Variations in color luminance may also be a factor in one's ability to attend to something. For example, if a person is attending to a number of objects that are one color shade (for instance, dark green), it may be possible that this person might not see an additional object appear in their field of view (FOV) if it is the same color and shade. Conversely, the opposite might be true that a person is more likely to attend to the additional object if it is the same dark green color, opposed to an object that is colored a lighter green. This research investigated whether some variations of luminance of the same color (for example, dark green to light green) can affect one's ability to attend an additional object entering one's FOV. A scenario was presented to tank gunners that required them to observe objects of one color (dark green) while an additional object was briefly presented to them colored either dark green or light green. In this between-subjects study, 48 participants observed four dark green and four light green enemy tanks moving about the battlefield. Each was given a task that involved monitoring the dark green tanks only. During their monitoring, an additional vehicle (M981A3 FIST-V) briefly entered and exited their FOV. The additional vehicle was presented to 24 participants colored dark green. For the other 24, it was presented colored light green. This research addressed whether there was an association between color luminance, FOV, or focused attention and detection of the FIST-V. The results did not indicate an association between FOV and detection of the FIST-V [÷2(1, N = 48) = 0.08, p = 1.0]. Nor was there an association between focused attention and detection of the FIST-V using the following self-reporting questionnaires for determining levels of focused attention: ETAS [÷2(1, N = 48) = 2.06, p = 0.20], the CFQ [÷2(1, N = 48) = 0.75, p = 0.56], and the DAPI [÷2(1, N = 47) = 1.39, p = 0.75]. In the same manner, there was also no association between field dependence and detection of the FIST-V [÷2(1, N = 43) = 0.34, p = 0.75]. There was, however, an association between color luminance and detection of the FIST-V [÷2(1, N = 48) = 36.80, p < 1.0e-8]. / Master of Science

No / Image gradients - smooth changes in color and luminance - may be caused by intrinsic surface reflectance properties or extrinsic illumination phenomena, including shading, shadowing, and inter-reflections. In turn, image gradients may provide the visual system with information concerning the origin of these factors, such as the orientation of surfaces with respect to the light source. Color gradients induced by mutual illumination (MI) may play a similar role to that of luminance gradients in shape-from-shading algorithms; it has been shown that 3D shape perception modulates the influence of MI on surface color perception (M. G. Bloj, D. Kersten, & A. C. Hurlbert, 1999). In this study, we assess human sensitivity to changes in color and luminance gradients that arise from changes in the light source position, within a complex scene. In Experiment 1, we tested whether observers were able to discriminate between gradients due to different light source positions. We found that observers reliably detected a change in the gradient information when the light source position differed by only 4 deg from the reference scene. This sensitivity was mainly based on the luminance information in the gradient (Experiments 2 and 3). Some observers make use of the spatial distribution of chromaticity and luminance values within gradients when discriminating between them (Experiment 4). The high sensitivity to gradient differences supports the notion that gradients contain information that may assist in the recovery of 3D shape and scene configuration properties.

No / We investigated the brightness (i.e., perceived luminance) of isolated L- and M-cone pulses to seek a perceptual correlate of our previous reports that M-on electroretinograms resemble L-off responses, implying the operation of post-receptoral opponent processing. Using triple silent substitutions, cone increments were generated in a 4-primary ganzfeld, masked by random positive or negative luminance bias. The results show that M-cone increments decrease in brightness, while L-cone increments increase. These differences became smaller as field size reduced; this was not eccentricity or area dependent. We speculate about early retinal input into brightness perception.

La technologie du béton progresse très rapidement, principalement en ce qui concerne l'amélioration de ses propriétés mécaniques. Au cours des dernières années, de grands efforts ont été faits pour améliorer l'apparence de la surface du béton. L'amélioration de la surface du béton améliore non seulement l'aspect esthétique du béton, mais protège également le béton contre les agressions provenant de l'environnement. La surface du béton brut présente généralement de nombreux défauts de surface. Ces défauts sont visibles à l'œil nu par des variations de couleur ou de texture. Selon la littérature, l'ensemble de tous ces défauts est dû à la composition initiale du béton, aux formes de remplissage et enfin, aux conditions de conservation après démoulage. Au travers de ma thèse j'ai travaillé sur l'influence de la composition des matériaux cimentaires sur l'aspect final de la surface une fois durcie, et notamment en analysant le rapport E/C. Les essais ont tous été effectués sur de ciment CEM I. Pour la partie expérimentale, nous avons fabriqué des pâtes de ciment et des mortiers avec différents rapports E/C dans des moules métalliques de 4x4x16 $cm^3$. Nous avons utilisé un spectre colorimètre pour mesurer l'intensité de la lumière réfléchie en termes de luminance et un microscope numérique pour mesurer la rugosité des surfaces en termes de surface développée. A partir de nos résultats, nous avons observé que l'augmentation du rapport E/C engendre l'éclaircissement des surfaces et une diminution de la rugosité de la surface des matériaux cimentaires. Nous avons également effectué des essais rhéologiques sur des pâtes et des mortiers frais. Pour les pâtes, un rhéomètre rotatif de l'IRC (Institut de Recherche en Constructibilité) -ESTP Paris a été utilisé, tandis que pour les mortiers, le rhéomètre de CERIB (à Épernon) a été privilégié. Par nos résultats, nous avons observé que l'augmentation de l'eau dans la composition des matériaux cimentaires engendre considérablement la diminution du seuil de cisaillement et de la viscosité. Les modèles mathématiques pour décrire l'écoulement de matériaux cimentaires utilisés étaient les modèles classiques (Bingham, Herschel Bulkley et Casson) et modifiés par Papanastasiou. A partir de la régression numérique, nous avons observé que la loi de Herschel Bulkley et tous les autres modèles modifiés sont bien adaptés pour décrire le comportement des pâtes de ciment. Pour les mortiers, les modèles Bingham, Herschel Bulkley et tous les modèles modifiés sont bien adaptés pour les mortiers fluides. Enfin, la loi de Bingham-Papanastasiou a été choisie pour modéliser l'écoulement des pâtes de ciment via COMSOL multiphysics. Les résultats numériques sont comparés avec ceux d’expérimentation / This thesis deals with the study of the influence of the water variations in the concrete-formwork interface. The proposed approach is intended to analyze two aspects. • The role of the concrete mixing formulation, and the casting procedures on the finished mortar surface. • The movement of water in concrete formwork interface. Firstly, we search to confirm the phenomenological results on the relationship between the luminance of the concrete surface and its roughness, this last being governed by the local W/C ratio in the formwork interface. This relationship will be established for compositions of modern concrete. After, we will examine the role of operational factors on the granular segregation on the mortar surface and their consequences on the bleeding of the specimens, on the water movements as well as on the color of the surface. Parameters : Formulation parameters : granular composition, G/S, S/G, W/C ratio and admixtures Parameters of implementation: Temperature and relative humidity, vibration, waiting time, type of formwork, release agents. Maturation parameters: temperature, relative humidity, form release deadline and carbonation

Le rayonnement infrarouge thermique (7.5-14 μm) permet de mesurer à distance la température de surfaces géologiques. Les capteurs de type “microbolomètre”, de bas prix et d’utilisation facile, sont de plus en plus utilisés pour cartographier sur le terrain des anomalies de température. Cependant, des phénomènes tels que l’opacité de l’atmosphère et les réflexions de la surface viennent modifier le signal. De plus, les images doivent être ajustées géométriquement pour être cartographiées. Après avoir proposé un protocole de correction géométrique et radiométrique des mesures, et quantifié les incertitudes résiduelles, quelques exemples sont étudiés pour définir les potentiels et les limites de l’infrarouge thermique en sciences de la Terre. Son potentiel pour la détection de la ligne de rivage a été utilisé lors d’une marée montante pour reconstituer le modèle numérique de terrain (MNT) d’une plage de l’Aber Benoît (Bretagne). D’autre part, un modèle informatique a été développé pour mesurer l’influence de la rugosité sur la température de la surface des planètes. Il a été appliqué au calcul de l’inertie thermique de Mars et de l’astéroïde (2867) Šteins. Enfin, les images infrarouges sont utilisées pour quantifier le flux de chaleur d’une zone sub-fumerollienne de la Soufrière. Ainsi, l’imagerie thermique infrarouge montre un fort potentiel, partiellement inexploité par les études actuelles, notamment pour la cartographie quantitative des contrastes de température à haute résolution. A haute fréquence, elle permet d’étudier la dynamique des phénomènes géologiques. / Thermal infrared (7.5-14 μm) enables the measurement of temperature far fromgeological surfaces. Microbolometers devices are increasingly used in the field in order to mapthermal anomalies. However, phenomena such as atmospheric opacity and surface reflections disturb the electromagnetic signal. In addition, images have to be geometrically adjusted to fit with geographical models. A processing chain is here suggested in order to correct the radiometry and the geometry of images, and the uncertainties are computed. Then, its potential and limitations are considered, through a few examples. First, it has been used in order to detect the waterline evolution of a mud shore during a rising tide, which enables to reconstruct a digital elevation model. Then, a computer model has been developed to study the roughness effects on the surface temperature and on the thermal inertial calculation on Mars and on the (2867) Šteins asteroid. Finally the heat flux of a sub-fumarolian zone has been computed in La Soufrière volcano (Guadeloupe, Lesser Antilles).Thus, thermal infrared remote sensing is very useful in quantitatively mapping the temperatures anomalies with a high resolution. High frequency studies should enable the survey of geological phenomena.