<p>In some roundabouts, just relying on the "right of way" regulations results in long queues forming along the approaches. This usually happens when a roundabout suffers from unbalanced flow patterns (one or two of the approaches convey much heavier traffic compared to the others). There is an idea that signalization of roundabouts can be useful as a countermeasure for such a problem, especially during peak hours. In that case, signal operation can come in many forms, including full-time control, part-time control, or metering. One problem that seems to be facing engineers when signalizing roundabouts is lacking a general set of patterns or guidelines to choose an appropriate form of signalization and apply it efficiently in different situations. There is also a need for a comprehensive review over the available literature concerning signalization of roundabouts. In this thesis, a review of literature regarding signalization of roundabouts is carried out. Moreover, a roundabout in Stavanger with unbalanced traffic flows is studied in order to find an appropriate signalization scenario which can improve the traffic situation. The network is modeled and simulated in AIMSUN.</p>

Shape description is an important problem in computer vision because most vision tasks that require comparing or matching visual entities rely on shape descriptors. In this thesis, two novel shape descriptors are proposed, namely Intersection Consistency Histogram (ICH) and Global Binary Patterns (GBP). The former is based on a local regularity measure called Intersection Consistency (IC), which determines whether edge pixels in an image patch point towards the center or not. The second method, called Global Binary Patterns, represents the shape in binary along horizontal, vertical, diagonal or principal directions. These two methods are extensively analyzed on several databases, and retrieval and running time performances are presented. Moreover, these methods are compared with methods such as Shape Context, Histograms of Oriented Gradients, Local Binary Patterns and Fourier Descriptors. We report that our descriptors perform comparable to these methods.

Pourquoi certains dispositifs participatifs brésiliens réunissent-ils surtout des acteurs habituellement peu participants ? Cette thèse rend compte d'une participation " improbable " à partir de l'étude des conférences municipales des femmes de Recife et de Londrina. A la différence des analyses " institutionnelles " qui placent les procédures en facteur explicatif des pratiques de participation, notre approche vise à mettre en évidence l'ancrage social des dispositifs et l'intrication entre les jeux sociaux et participatifs. L'hypothèse principale est que la mobilisation des déshéritées dans les conférences des femmes dépend principalement des enjeux propres à l'espace des quartiers populaires et, plus précisément, des luttes pour la représentation en leur sein. Cette thèse repose sur la combinaison de deux niveaux d'analyse : une approche micro-sociologique, centrée sur les trajectoires et les pratiques de participation des habitantes ; une approche méso-sociologique ensuite, visant à retracer l'émergence de la démocratie participative au Brésil. Ces deux niveaux permettent de montrer que la participation des plus démuni(e)s est le résultat d'une part d'une histoire singulière, au cours de laquelle la notion de participation a été associée aux quartiers populaires, et de l'autre des dynamiques individuelles et collectives de construction des porte-parole légitimes de ces territoires.

Transit agencies seeking to improve transit service delivery are increasingly considering the deployment of transit signal priority (TSP). However, the impact of TSP on transit service and on the general traffic stream is a function of many factors, including intersection geometry, signal timings, traffic demands, TSP strategies and parameters, transit vehicle headways, timing when transit vehicles arrive at the intersection, etc. Previous studies have shown that depending on these factors, the net impact of TSP in terms of vehicle or person delay can be positive or negative. Furthermore, due to financial constraints, transit agencies are often able to deploy TSP at only a portion of all of the candidate intersections. Consequently, there is a need to estimate the impact of TSP prior to implementation in order to assist in determining at which intersections TSP should be deployed. Currently, the impacts of TSP are often estimated using microscopic simulation models. However, the application of these models is resource intensive and requires specialized expertise that is often not available in-house to transit agencies. In this thesis, an analytical model was proposed for estimating the delay impacts of green extension and early green (red truncation) TSP strategies. The proposed model is validated with analytical model reported in the literature and microscopic simulation model. This is followed by model sensitivity analysis. A software module is developed using the proposed model. The usefulness of the model is illustrated through its application to estimate the TSP performance. Finally, a prioritization is conducted on sixteen intersections with different geometric and operational traffic strategies. The overall results indicate that the proposed model is suitable for both estimating the pre-deployment and post-deployment TSP performance. The proposed model is suitable for implementation within a spreadsheet and requires considerably less effort, and less technical expertise, to apply than a typical micro-simulation model and therefore is a more suitable tool for transit agencies to use for prioritising TSP deployment.

No description available.

Neue Methoden zur Verkehrsdatenerfassung wie die Fahrzeug-Infrastruktur-Kommunikation, der Floating Car-Ansatz und die Videodetektion eröffnen die Möglichkeit, neue Verfahren zur verkehrsabhängigen Lichtsignalanlagensteuerung zu realisieren. In dem Beitrag wird ein Verfahren beschrieben, das aus diesen Quellen Daten in Form von Fahrzeugverlustzeiten direkt zur Steuerung eines Einzelknotens verwendet. Die robuste Ausgestaltung des Verfahrens sorgt dabei dafür, dass auch mit einer lückenhaften Datenlage, wie z. B. aufgrund geringer Ausstattungsraten kommunikationsfähiger Fahrzeuge, angemessen umgegangen werden kann. Mit Hilfe einer mikroskopischen Simulationsstudie wird nachgewiesen, dass das neue Verfahren bei der Qualität des Verkehrsablaufs das gleiche Niveau wie eine traditionelle Zeitlückensteuerung erreicht oder dieses unter bestimmten Bedingungen sogar übersteigt. Mit abnehmender Ausstattungsrate ergibt sich dabei allerdings ein Qualitätsverlust, der ebenfalls mit Hilfe der mikroskopischen Simulation quantifiziert wird und wichtige Erkenntnisse für einen möglichen Praxistest liefert. / State-of-the-art traffic data sources like Car-to-Infrastructure communication, Floating Car Data and video detection offer great new prospects for vehicle-actuated traffic signal control. Due to this, the article deals with a recent approach which uses vehicles’ delay times for real-time control of traffic signals at an isolated intersection. One of the strengths of the new approach is that it can handle also incomplete data sets, e.g. caused by low penetration rates of vehicles equipped with Car-to-Infrastructure communication technology, in an appropriate manner. Based on a microscopic simulation study the high quality of this innovative approach is demonstrated, which is equal or even outperforms the well-known headway-based control. However, a decreasing penetration rate of equipped vehicles means a reduced quality of signals’ control, which is quantified in the microscopic simulation study, too, and provides useful information for tests in the field.

A narrative analysis of the lived experiences of seven undergraduate African American females at Predominately White Institutions (PWIs) is presented in this study. The purpose of the study was to explore the ways the seven women constructed their identity and self-concept in the context of their PWI environment. Other key purposes of the study included strategies in which the women successfully negotiated their PWI environments and the influence of the intersection of race, gender, and class on the collegiate and life experiences of these African American undergraduate females. The framework which was conceptualized from previous literature portrayed the historical context of the African American woman’s struggle for educational access as both Black and female, her life on campus, tools for success, and the identity development of African American women. Critical Race and Black Feminist theoretical frameworks, were the foundation for the study. Through these theoretical lenses, the study looked closely at the academic, social, and cultural climate on PWI campuses and the impact of these factors on the identity development and self-concept of the women in this study. The research methodology of narrative analysis was used and resulted in the emergence of three key findings in this study. The findings indicate that African American undergraduate females at PWIs engage in negotiating worlds, managing subjectivities, and redefining selves as they make meaning and walk out their individual lived experiences as students on Predominately White campuses.

In indoor environment, the multi-sensor system has been proved to be an efficient solution for target locating process in terms of lower estimation cost. However, the placement of designed multi-sensor has great impact on the location performance in an indoor environment. Based on the time difference of arrival (TDOA), closed-form least-square location methods, including the spherical-interpolation (SI) and the spherical-intersection (SX) methods, are used in the estimation of target locations. The two methods are apart from the usual process of iterative and nonlinear minimization. Consequently, under the influence of noise interference, the performance of the two methods also produce different results. In addition to the above issues, the limitation of these methods will also be examined. The geometric dilution of precision (GDOP) effects of TDOA location on location performance of both inside and outside of the multi-sensor environment in the 2-D scenario have been studied in the past. This thesis aims to further advance the performance of GDOP in 3-D scenarios, analyze the differences, and propose the suitable needs. Programmed 3-D scenario simulations are used in this research, designed according to multiple sensor arrays and the moving latitude of a target. The Setup interprets the degree of multi-sensor separation, and distances from targets to the sensor array. A suitable location algorithm and optimal multi-sensor deployments in an indoor environment were proposed according to the simulation results.

Edge detection is an important step in computer vision since edges are utilized by the successor visual processing stages including many tasks such as motion estimation, stereopsis, shape representation and matching, etc. In this study, we test whether a local consistency measure based on image orientation (which we call Intersection Consistency - IC), which was previously shown to improve detection of junctions, can be used for improving the quality of edge detection of seven different detectors / namely, Canny, Roberts, Prewitt, Sobel, Laplacian of Gaussian (LoG), Intrinsic Dimensionality, Line Segment Detector (LSD). IC works well on images that contain prominent objects which are different in color from their surroundings. IC give good results on natural images that have especially cluttered background. On images involving human made objects, IC leads to good results as well. But, depending on the amount of clutter, the loss of true positives might be more crucial. Through our comprehensive investigation, we show that approximately 21% increase in f-score is obtained whereas some important edges are lost. We conclude from our experiments that IC is suitable for improving the quality of edge detection in some detectors such as Canny, LoG and LSD.

Στη διπλωματική αυτή εργασία ορίζουμε δυο νέα μοντέλα τυχαίων γραφημάτων τομής ετικετών και εξετάζονται ως προς ορισμένες σημαντικές γραφοθεωρητικές ιδιότητές τους. Ένα τυχαίο γράφημα τομής ετικετών παράγεται αντιστοιχώντας σε κάθε κορυφή ένα \\\\emph{τυχαίο} υποσύνολο ενός πεπερασμένου) σύμπαντος $M$ από $m$ στοιχεία και βάζοντας μια ακμή μεταξύ δυο κορυφών αν και μόνον εάν τα αντίστοιχα σύνολά τους έχουν μη κενή τομή. Συγκεκριμενοποιώντας την κατανομή που ακολουθεί το τυχαίο υποσύνολο που αντιστοιχείται σε κάθε κορυφή παίρνουμε διαφορετικά μοντέλα τυχαίων γραφημάτων τομής. Στο γενικευμένο μοντέλο τυχαίων γραφημάτων τομής κάθε στοιχείο $i$ του $M$ επιλέγεται ανεξάρτητα από κάθε κορυφή με πιθανότητα $p_i$. Το ομοιόμορφο μοντέλο τυχαίων γραφημάτων τομής ετικετών αποτελεί μια ειδική περίπτωση του γενικευμένου μοντέλου όπου η πιθανότητα επιλογής των στοιχείων του $M$ είναι ίση με $p$, δηλαδή ίδια για όλα τα στοιχεία του $M$. Όπως θα δούμε, για ορισμένες τιμές των παραμέτρων $m$ και $p$, το ομοιόμορφο μοντέλο είναι ισοδύναμο με το μοντέλο $G_{n, \\\\hat{p}}$, δηλαδή με το μοντέλο τυχαίων γραφημάτων στο οποίο κάθε πλευρά εμφανίζεται στοχαστικά ανεξάρτητα με πιθανότητα $\\\\hat{p}$. Τέλος, στο κανονικό μοντέλο τυχαίων γραφημάτων τομής ετικετών το υποσύνολο του $M$ που αντιστοιχείται σε κάθε κορυφή έχει σταθερό αριθμό στοιχείων. Λόγω της στοχαστικής εξάρτησης που υποννοείται για την ύπαρξη πλευρών, τα γραφήματα αυτά θεωρούνται αρκετά ρεαλιστικά μοντέλα (σε σχέση με τα κλασσικά τυχαία γραφήματα) σε πολλές πρακτικές εφαρμογές, ιδιαίτερα σε αλγοριθμικά θέματα δικτύων. Στην εργασία αυτή αρχικά παρουσιάζουμε μερικά χαρακτηριστικά αποτελέσματα από τη σχετική βιβλιογραφία για τα μοντέλα αυτά. Ακόμα, μελετάμε, για πρώτη φορά στη βιβλιογραφία, την ύπαρξη ανεξάρτητων συνόλων κορυφών μεγέθους $k$ στο γενικευμένο μοντέλο τυχαίων γραφημάτων τομής ετικετών, υπολογίζοντας τη μέση τιμή και τη διασπορά του αριθμού τους. Επίσης, προτείνουμε και αναλύουμε τρείς πιθανοτικούς αλγόριθμους που τρέχουν σε μικρό πολυωνυμικό χρόνο (ως προς τον αριθμό των κορυφών και τον αριθμό των στοιχείων του $M$) για την εύρεση αρκετά μεγάλων συνόλων ανεξάρτητων κορυφών. / In this Master thesis we define and analyse two new models of random intersection graphs. A random intersection graph is produced by assigning to each vertex a random subset of a (finite) universe $M$ of $m$ elements and by drawing an edge between two vertices if and only if their corresponding subsets have some elements in common. By specifying the distribution of the subsets assigned to each vertex, we get various models of random intersection graphs. In the generalized random intersection graphs model each element $i$ in $M$ is chosen independently with probability $p_i$. The uniform random intersection graphs model is a special case of the generalized model where the probability of selecting an element of $M$ is $p$, i.e. the same for every element. As we will see, for some range of values of the parameters $m$ and $p$, the uniform model is equivalent in some sense with the model $G_{n, \\\\hat{p}}$, i.e. the random graphs model in which each edge appears independently with probability $\\\\hat{p}$. Finally, in the regular random intersection graphs model, the subset of $M$ assigned to each vertex has a fixed number of elements. Due to the dependence implied in the appearance of edges, these models are considered to be more realistic (than classic random graphs) in many applications. This thesis begins by presenting several important results concearning these models. Also, we study for the first time the existence of independent sets of size $k$ in the generalized random intersection graphs model, and we give exact formulae for the mean and variance of their number. Additionally, we propose three randomized algorithms, that run in small polynomial time (with respect to the number of vertices and the number of elements of $M$), for finding large independent sets of vertices.