Global ETD Search

1	Investigating erythemal UV exposure and vitamin D production in the urban canyon McKinley, Alex R. January 2008 (has links) Exposure to ultraviolet radiation (UV) results in both damaging and beneficial health outcomes. Excessive UV exposure has been linked to many skin and eye problems, but moderate exposure induces vitamin D production. It has been reported that humans receive 90-95% of their vitamin D from production that starts after UV exposure. Although it is possible to acquire vitamin D through dietary supplementation, the average person receives very little in this manner. Therefore, since most people acquire their vitamin D from synthesis after exposure to UV from sunlight, it is very important to understand the different environments in which people encounter UV. This project measured UV radiation and in-vitro vitamin D production in the urban canyon and at a nearby suburban location. The urban canyon is an environment consisting of tall buildings and tropospheric air pollution, which have an attenuating effect on UV. Typically, UV measurements are collected in areas outside the urban canyon, meaning that at times studies and public recommendations do not accurately represent the amount of UV reaching street-level in highly urbanized areas. Understanding of UV exposure in urban canyons becomes increasingly important as the number of people working and living in large cities steadily increases worldwide. This study was conducted in the central business district (CBD) of Brisbane, Australia, which models the urban canyons of large cities around the world in that it boasts a great number of tall buildings, including many skyscrapers, meaning that most areas only see a small amount of direct sunlight each day. During the winter of 2007 measurements of UV radiation and in-vitro vitamin D production were collected in the CBD and at a suburban site approximately 2.5km outside the CBD. Air pollution data was obtained from a central CBD measurement site. Data analysis showed that urban canyon measurements of both UV radiation and in-vitro vitamin D production were significantly lower than those collected at the suburban site. These results will aid both future researchers and policy makers in better understanding human UV exposure in Brisbane’s CBD and other urban canyons around the world.
2	GIS and Satellite Visibility: Viewsheds from Space Germroth, Matthew Ryan 24 May 2005 (has links) The Global Positioning System (GPS) has recently become the significant mapping tool for millions of customers worldwide, providing its users with accurate terrestrial positions almost instantaneously. The functionality of a GPS receiver depends on the number of satellites to which it can establish an unobstructed line of sight. Current satellite availability prediction tools perform satellite visibility predictions without considering terrain or structures that block GPS signals, a major issue in mountainous and urban areas. This paper describes a new Geographic Information Systems (GIS) tool, a customization of ArcGIS named Satellite Viewsheds, which predicts satellite visibility for any place and time while considering line of sight obstructions. Satellite Viewsheds requires a raster surface model, the test date and time, and the orbital properties of the satellites. It produces grids depicting the number of visible satellites and optimal viewing time for every cell in the grid. Satellite Viewsheds allows users to avoid areas of signal loss and choose the best time to map using their GPS receivers. The field test of Satellite Viewsheds proved that the tool performs satellite visibility predictions consistently and accurately. The research outlined in this paper indicates that Satellite Viewsheds is the first tool of its kind. / Master of Science viewshed satellite urban canyon visibility hillshade GIS GPS
3	GNSS Timing Receiver Performance in Urban Canyons Fu, Xiangcheng January 2019 (has links) Time synchronization is critical for the operation of radio base stations (RBS) in telecommunication companies. Global navigation satellite system (GNSS) is an existing technology to provide precise timing information to distributed RBSs. GNSS timing receiver is used for providing higher timing accuracy than normal GNSS receiver in this synchronization domain.In this thesis, an experiment method for GNSS timing receiver performance in urban canyon has been designed and implemented to evaluate information and the quality of the one pulse per second (1PPS) signal generated by two different GNSS timing receivers. Multi-path signals and the gathered satellite geometry caused by poor sky visibility is identified as the main influential factors to the performance of the GNSS timing receivers. A mathematical model has been built for estimating the multi-path effect. GNSS planning tools are used to simulate the number of line-of-sight (LOS) satellites and Dilution of Precision (DOP) value.Sentinel is a 1PPS signal analyzing equipment from Calnex. Sentinel has an embedded rubidium clock, GNSS antenna, and receiver, and it can produce 1PPS signals to be used as a reference. In this report, we installed our GNSS antenna of Sentinel on the roof and test GNSS antenna in two specified positions representing urban canyon and rooftop. Recorded NMEA messages from GNSS receiver can help us to study the number of visible satellites, PDOP value and multi-path signals in realistic situations.The results show how the noise and time phase of 1PPS signals will be influenced in urban canyons. Since, the geometry of used satellites is similar to the rooftop situation, the multi-path effect of signals is identified as the main reason of this difference.This information is useful when telecommunication companies want to install their radio base station in urban canyons. It will help Ericsson to understand how their GNSS timing receiver is working and how the urban canyon will influence its performance. / Tidssynkronisering är kritisk för driften av radiobasstationer (RBS) i telekommunikationsföretag. Global Navigation Satellite System (GNSS) är en befintlig teknik för att ge exakt tidsinformation till distribuerade basstationer. GNSS-baserade tidsmottagare används för att ge högre timing-noggrannhet än vanlig GNSS mottagare i denna synkroniseringsdomän. I denna avhandling har en experimentmetod för GNSS-timingmottagarnas prestanda i urban canyon utformats och implementerats för att utvärdera den genererade informationen och kvaliteten på en puls per sekund-signal (1PPS). Flervägssignaler och den samlade satellitgeometrin som orsakas av dålig himmelsynlighet identifieras som de mest inflytelserika faktorerna för GNSS-tidsmottagarnas prestanda. En matematisk modell har donstruerats för att estimera multi-path-effekten. GNSS-planeringsverktyg används för att simulera antalet LOS-satelliter och DOP-värde (Dilution of Precision). Sentinel är en 1PPS signalanalysutrustning från Calnex. Sentinel har en inbyggd rubidiumklocka, GNSS-antenn och mottagare, och den kan producera 1PPS-signaler som ska användas som referens. I den här rapporten installerade vi vår GNSS-antenn på Sentinel på taket och GNSS-testantennen i två angivna positioner som representerar urban canyon och tak. Inspelade NMEA-meddelanden från GNSS-mottagare kan hjälpa oss att studera antalet synliga satelliter, PDOP-värde och flervägssignaler i realistiska scenarier. Resultatet visar att ljud- och tidsfasen för 1PPS-signaler påverkas i urban canyons. Eftersom satellitgeometrin liknar den för antenner placerade på taket, så är identifieras flervägsutbredningen som huvudorsak för denna skillnad. Denna information är användbar när telekommunikationsföretag vill installera sina radiobasstationer i urban canyons. Det kommer att hjälpa Ericsson att förstå hur deras GNSS-timingmottagare arbetar och hur urban canyon påverkar dess prestanda. GNSS Timing Receiver 1PPS Synchronization Urban Canyon Engineering and Technology Teknik och teknologier
4	Réalisation d'un micro-robot autonome, inspiré du contrôle de vistesse et d'évitement d'obstacles observés chez l'abeille. / Design of an autonomous micro-robot inspired from the speed control and obstacle avoidance observed on honeybees Roubieu, Frederic 16 July 2013 (has links) Cette thèse présente l'implémentation d'une stratégie visuelle bio-inspirée sur un aéroglisseur miniature totalement actionné, qui lui permet de naviguer dans le plan horizontal d'un tunnel inconnu. L'élaboration de ce pilote automatique, nommé LORA, fait suite aux études éthologiques menées sur l'abeille depuis ces dernières décennies et nous ont amené à énoncer le principe de la régulation du flux optique pour le contrôle du vol de croisière. Ce pilote automatique est un double régulateur de flux optique latéral constitué de deux boucles visuo-motrices interdépendantes contrôlant conjointement la vitesse d'avance et la position du robot par rapport aux obstacles sans avoir à mesurer ou estimer aucun de ces paramètres. La clé de voûte de ce système de guidage est une troisième boucle destinée à maintenir le cap grâce à un micro-gyromètre et un micro-compas magnétique permettant au robot d'effectuer des mouvements de translation qui génèrent sur son œil composé artificiel du flux optique de translation, seul dépendant du ratio vitesse/distance aux obstacles. Cet œil estime le flux optique grâce à ses deux ou quatre Détecteurs élémentaires de mouvement (total de 4 ou 8 pixels). L'aéroglisseur est alors capable de franchir sans collision, à la manière d'une abeille, divers tunnels : droit, fuselé ou présentant une pente, un virage, une absence de texture sur un mur ou même une zone non-stationnaire. Cette stratégie visuelle bio-inspirée fournit non seulement une solution de navigation élégante à destination de robots totalement actionnés mais elle permet aussi d'expliquer comment une abeille de 100mg peut naviguer sans l'aide de SONAR, RADAR, LIDAR, ou GPS. / In this work, we present for the first time a bio-inspired motion vision-based navigation strategy embedded on a miniature fully-actuated hovercraft allowing it to navigate safely on the horizontal plane of an unknown corridor. The design of this autopilot, called LORA, follows the ethological findings made on honeybees these last decades, which led us to elaborate the principle of the optic flow regulation which might be used by insects to control their flight. The bee-inspired LORA autopilot is a dual optic flow regulator which consists in two intertwined visuomotor feedback loops which control jointly the forward speed of the robot and its clearance to the obstacles. The keystone of this bio-inspired guidance system is a heading-lock system enabling the robot to move in translations and therefore experience a purely translational optic flow which depends only on the ratio speed/clearance to obstacles thanks to a micro-gyrometer and a micro-magnetic compass. The estimation of optic flow is made by a minimalist compound eye, made of two or four Elementary Motion Detectors (only 4 or 8 pixels). The hovercraft is therefore able to cross without crashing a straight or a tapered corridor, presenting a frontal sloping terrain, a bend, a textureless wall, or even a non-stationary section by automatically adapting both its forward speed and its clearance to the walls imitating the honeybee. This bio-inspired visual strategy not only provides an elegant navigation solution in an unknown environment aimed to equip fully-actuated miniature vehicles but also to explain how a 100mg honeybee can navigate with few computational ressources, i.e., without any SONAR, RADAR, LIDAR or GPS. Bio-inspiration Flux optique Pilote automatique Évitement d'obstacles Navigation en canyon urbain Aéroglisseur Bio-inspiration Optic flow Autonomous guidance Collision avoidance Urban canyon navigation Hovercraft 796
5	Mesure et modélisation de la lumière naturelle dans les canyons urbains / Daylight measurement and modelling in urban canyons Patriarche, Manolis 08 September 2014 (has links) L’augmentation de la population mondiale et l’urbanisation croissante conduisent à une densification urbaine qui menace l’accès des habitants des villes au soleil et à la lumière naturelle. Cet accès est lié à des problématiques de consommation d’énergie, de santé et de bien-être ; il peut être limité par plusieurs caractéristiques du tissu urbain telles que la largeur des rues, la hauteur des bâtiments, la clarté des façades et de la chaussée. Nous avons étudié l’influence des caractéristiques les plus importantes d’un canyon urbain sur la disponibilité de la lumière naturelle à l’intérieur du canyon sous des conditions climatiques réelles. Nous avons fabriqué dans ce but, le modèle réduit d’un canyon urbain, la représentation simplifiée d’une rue. Cette maquette est modifiable, le rapport d’aspect H/W (Hauteur/Largeur) du canyon peut être modifié et les façades sont interchangeables. Durant une année, les éclairements lumineux y ont été mesurés sur le sol et à plusieurs hauteurs des façades, au pas de la minute, sous des conditions de ciel réelles. Au total, 12 configurations sont représentées dans la base de données obtenue, avec 3 rapports d’aspect : H/W=0,5, 1 et 2, et 4 types de façades de facteur de réflexion lumineux différent. Les revêtements de façade utilisés sont : noir, blanc, crépi et crépi avec des parties vitrées. Nous étudions l’influence de ces paramètres en fonction des types de ciel définis par la CIE pour un canyon orienté nord/sud. Nous utilisons aussi ces données pour étudier l’usage, la performance et la précision de trois logiciels de modélisation du rayonnement solaire en milieu urbain : Citysim, Daysim et Heliodon. Ces trois logiciels offrant différents niveaux de simplification. Enfin, nous avons mené une campagne de mesure dans les rues de Lyon. Cela nous a permis de nous confronter à la réalité des données de terrain, juger des difficultés à les recueillir et à modéliser le rayonnement solaire dans l'espace réel. Nous avons aussi évalué une nouvelle méthode de mesure des éclairements lumineux d’une façade. Cette méthode se base sur des cartes de luminances obtenues à partir de photos fisheye avec un appareil photo numérique étalonné en luminances. La comparaison de ces mesures avec celles de la maquette permet d’évaluer l’erreur commise en utilisant un revêtement simplifié. En utilisant les données récoltées sur la maquette, le rapport d’aspect H/W=1 permet d’obtenir le meilleur accès à la lumière naturelle dans le canyon, il correspond à un bon compromis entre la contribution des façades et du ciel. Pour chaque ville, une configuration optimale peut être déterminée en fonction du climat local, qui peut être représenté par la fréquence d’observation des différents types de ciel CIE. Nous avons évalué la capacité des logiciels choisis à prendre en compte le climat. Avec Heliodon, il est possible d’obtenir des éclairements lumineux proches de ceux mesurés sur la maquette, pour des ciels sans nuages. Puisque le climat varie tout au long de l’année, la prise en compte des 15 types de ciel CIE doit être préférée à l’utilisation d’un ciel uniquement sans nuages, ou couvert comme cela est souvent le cas. Les logiciels Citysim et Daysim sont capables de prendre en compte le climat réel et produisent de bonnes corrélations avec les mesures effectuées sur la maquette pour tous les types de ciel. / As the world population and the urbanization increase, cities become denser, thus reducing access to daylight and sunlight for city dwellers. This access is linked to some issues such as energy consumption, health and comfort; it can be limited by several urban fabric features such as street width, building height, façade and road coating. We have evaluated the influence of the most important features of an urban canyon regarding daylight availability inside the canyon under real sky conditions.To that end, we have built a scale model of an urban canyon, the simplest representation of a street. This scale model can be modified: the aspect ratio H/W (Height/Width) can be changed as well as the type of façade. During one year, outdoor illuminances have been measured every minute on the ground and at different heights of the façades. Hence, we created a database containing twelve combinations of an urban canyon with the following parameters: three aspect ratios (H/W=2, 1 and 0.5) and four types of façades with different reflection factors. The different coatings of the façades are: black, white, roughcast and roughcast with windows. We evaluate the influence of these parameters for each type of sky defined according to the CIE for a north/south orientated canyon.We also use this database in order to evaluate the ease of use, performance and precision of three software tools for the estimation of solar radiation in urban context: Citysim, Daysim and Heliodon, each having different simplification levels.Finally, we have carried a measuring campaign in the streets of the French city of Lyons. This campaign allowed us to realize the difficulty of collecting data in the field and modelling solar radiation of a real street. We have also assessed a new method for measuring illuminances of a whole façade. This method is based on a luminance map generated from a calibrated digital camera equipped with a fisheye lens. A comparison between these illuminances with illuminances measured on the scale model with regular sensors allows us to estimate the bias of using a simplified coating.Based on illuminances measured on the scale model, a canyon with an aspect ratio H/W=1 has a better access to daylight, it represents a good compromise between contributions of the sky and the opposing façade. Every city has an optimal canyon shape according to its local climate that could be defined as the frequency of occurrence of the CIE types of sky. We have evaluated the ability of the selected software tools to take into account the climate. For clear skies, Heliodon is able to produce illuminances close to those measured on the scale model. Because the weather changes throughout the year, one would rather take into account the 15 CIE types of sky instead of using either a clear sky or an overcast sky as many studies do. Citysim and Daysim are able to take into account the climate and correlate well with scale model measurements for each type of sky. The method for measuring illuminances using a fisheye lens camera has been validated based on the measurements in real streets of Lyons. This method could produce more accurate values using a reflection factor map of the façade. Illuminances measured on the scale models didn’t correlate well with illuminances measured in real streets because of the complexity of the streets compared to the simplicity of the idealized canyon of the scale model. The use of simplified models of streets can lead to bad results, for instance, with studies estimating the energy consumption of buildings for lighting at district or urban scale. The density of urban areas must decrease in order to improve access to daylight. That would provide other advantages such as the reduction of exposure to vehicles pollution or reduction of the urban heat island. The calculation of an ideal aspect ratio could be achieved using tools evaluated in this thesis. Lumière naturelle Canyon urbain Modèle réduit Simulations Mesures sur site Facteur de réflexion lumineux Reflection factor Daylight Urban canyon Scale model Simulations On-site measurements
6	Accurate Positioning in Urban Canyons with Multi-frequency Satellite Navigation Ollander, Simon 07 December 2020 (has links) No description available. 510 GNSS Satellite Navigation GPS Navigation Positioning Multi-frequency Multipath Urban Canyon NLOS Reflection Dual-frequency Triple-frequency Detection Mitigation Simulation Raytracing Accurate Positioning Informatik (PPN619939052)
7	Stephen Poliakoff: Another Icon of Contemporary British Drama Idrissi, Nizar 01 February 2008 (has links) This thesis is an attempt to portray the birth of British modern drama and the most important figures breaking its new ground; more to the point, to shed light on the second generation of British dramatists breaking what G.B. Shaw used to call ‘middle-class morality’. The focal point here is fixed on Stephen Poliakoff, one of the distinctive dramatists in contemporary British theatre, his work and the dramatic tinge he adds to the new drama. European Plays Urban Canyon Plays Political Theatre Stephen Poliakoff Look Back in Anger John Osborne Bertolt Brecht The Berliner Ensemble Lord Chamberlain's Censorship System English Stage Company Theatre Workshop Company George Devine Joan Littlewood Shout Across the River Breaking the Silence Modern Drama In Yer Face Movement
8	Stephen Poliakoff: another icon of contemporary British drama Idrissi, Nizar 01 February 2008 (has links) This thesis is an attempt to portray the birth of British modern drama and the most important figures breaking its new ground; more to the point, to shed light on the second generation of British dramatists breaking what G.B. Shaw used to call ‘middle-class morality’. The focal point here is fixed on Stephen Poliakoff, one of the distinctive dramatists in contemporary British theatre, his work and the dramatic tinge he adds to the new drama. / Doctorat en Langues et lettres / info:eu-repo/semantics/nonPublished Sciences humaines Langues et littératures Poliakoff, Stephen (1952-) European Plays Urban Canyon Plays Political Theatre Stephen Poliakoff Look Back in Anger John Osborne Bertolt Brecht The Berliner Ensemble Lord Chamberlain's Censorship System English Stage Company Theatre Workshop Company George Devine Joan Littlewood Shout Across the River Breaking the Silence Modern Drama In Yer Face Movement
9	GIS-based Episode Reconstruction Using GPS Data for Activity Analysis and Route Choice Modeling / GIS-based Episode Reconstruction Using GPS Data Dalumpines, Ron 26 September 2014 (has links) Most transportation problems arise from individual travel decisions. In response, transportation researchers had been studying individual travel behavior – a growing trend that requires activity data at individual level. Global positioning systems (GPS) and geographical information systems (GIS) have been used to capture and process individual activity data, from determining activity locations to mapping routes to these locations. Potential applications of GPS data seem limitless but our tools and methods to make these data usable lags behind. In response to this need, this dissertation presents a GIS-based toolkit to automatically extract activity episodes from GPS data and derive information related to these episodes from additional data (e.g., road network, land use). The major emphasis of this dissertation is the development of a toolkit for extracting information associated with movements of individuals from GPS data. To be effective, the toolkit has been developed around three design principles: transferability, modularity, and scalability. Two substantive chapters focus on selected components of the toolkit (map-matching, mode detection); another for the entire toolkit. Final substantive chapter demonstrates the toolkit’s potential by comparing route choice models of work and shop trips using inputs generated by the toolkit. There are several tools and methods that capitalize on GPS data, developed within different problem domains. This dissertation contributes to that repository of tools and methods by presenting a suite of tools that can extract all possible information that can be derived from GPS data. Unlike existing tools cited in the transportation literature, the toolkit has been designed to be complete (covers preprocessing up to extracting route attributes), and can work with GPS data alone or in combination with additional data. Moreover, this dissertation contributes to our understanding of route choice decisions for work and shop trips by looking into the combined effects of route attributes and individual characteristics. / Dissertation / Doctor of Philosophy (PhD) GPS time use diary episode extraction multinomial logit travel behavior mode detection episode reconstruction GIS map-matching route choice path size logit potential path area scale estimation Python ArcGIS activity analysis trip reconstruction smartphone global positioning system geographic information system toolkit work trip shop trip potential activity location land use activity episode travel episode stop episode transferability scalability modularity scripting big data travel survey respondent burden preprocessing multipath error tracking purpose detection segmentation data filter data smoothing fuzzy logic neural network decision tree rule-based algorithm trajectory point road network network dataset gateway shortest path horizontal dilution of precision HDOP commonality factor mode transfer point Halifax Nova Scotia Space-Time Activity Research variance inflation factor shapefile comma-separated values traveling salesman problem data mining branch-and-bound algorithm pedestrian network alternative route observed route route efficiency route attributes distance time heading bearing duration acceleration latitude longitude coordinate overlay analysis intersect shopping module data logger walk likelihood ratio test classification table path generation kappa statistic degrees data collection transportation research automate framework ArcToolbox spatio-temporal navigation positioning trace path spatial data topology horizontal accuracy SPSS Stata spatial resolution temporal resolution household survey trip reporting proximity analysis DMTI Desktop Mapping Technologies Inc. road intersection route overlap left turn right turn location analysis time geography spatial statistics buffer analysis cycling bus transit public transportation GEOIDE AGILE data need raw data urban canyon endpoint data cleaning elevation satellite outliers automatic processing nearest node classifier classification method short trip multi-point

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