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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Regularization for MRI Diffusion Inverse Problem

Almabruk, Tahani 17 June 2008 (has links)
In this thesis, we introduce a novel method of reconstructing fibre directions from diffusion images. By modelling the Principal Diffusion Direction PDD (the fibre direction) directly, we are able to apply regularization to the fibre direction explicitly, which was not possible before. Diffusion Tensor Imaging (DTI) is a technique which extracts information from multiple Magnetic Resonance Images about the amount and orientation of diffusion within the body. It is commonly used for brain connectivity studies, providing information about the white matter structure. Many methods have been represented in the literature for estimating diffusion tensors with and without regularization. Previous methods of regularization applied to the source images or diffusion tensors. The process of extracting PDDs therefore required two or three numerical procedures, in which regularization (including filtering) is applied in earlier steps before the PDD is extracted. Such methods require and/or impose smoothness on all components of the signal, which is inherently less efficient than using regularizing terms that penalize non-smoothness in the principal diffusion direction directly. Our model can be interpreted as a restriction of the diffusion tensor model, in which the principal eigenvalue of the diffusion tensor is a model variable and not a derived quantity. We test the model using a numerical phantom designed to test many fibre orientations in parallel, and process a set of thigh muscle diffusion-weighted images. / Thesis / Master of Science (MSc)
12

Le discours didascalique et ses enjeux dans le théâtre de F. G. Lorca / Stage directions as speech in F. Garcia Lorca's plays : significance and purpose

Garnero, Sandra 13 July 2015 (has links)
L’objet de notre étude est l’analyse du discours didascalique du poète et dramaturge espagnol, Federico García Lorca. Trois pièces constituent notre champ d’investigation : Bodas de sangre, Yerma et La casa de Bernarda Alba. Les didascalies, en tant que discours émanant de la voix auctoriale, ont fait l’objet de nombreuses recherches et publications depuis l’essor de la linguistique de l’énonciation et de l’analyse du discours dramatique. Ce travail propose une poétique singulière des didascalies et démontre qu’elles forment un code sémiotique particulier, stratégique et poétique au sein du discours théâtral lorquien : loin de ne constituer qu’un péritexte fonctionnel qui se limite à accompagner et à préciser les conditions de mise en scène du discours entre personnages, elles représentent le véritable centre névralgique du théâtre poétique de Lorca. Elles participent pleinement de la construction du sens profond de l’œuvre et livrent des clés interprétatives essentielles fonctionnant à différents niveaux de lecture et de réception théâtrale. La lecture de certaines didascalies représente un véritable plaisir pour le spectalecteur. Elles peuvent être considérées dans une perspective poétique et interprétées dans la matérialité même de leur signe linguistique comme des supports textuels et phoniques. Elles demeurent dans la plupart des cas l’apanage du lecteur car, renversement paradoxal, le metteur en scène est souvent dans l’impossibilité de les représenter totalement sur scène. Ces didascalies correspondent à la première phase de ce travail et sont nommées didascalire. D’autres didascalies concernent d’une façon plus concrète et pratique les détails de la future mise en scène et possèdent une fonction performative et conative. Elles ne sont plus textuelles : le message originel se transforme en d’autres systèmes de signes. Elles font l’objet de la seconde phase de cette étude et sont appelées didascascène. Les parties liminaires (titres – sous-titres et dramatis personae par exemples), les nuances chromatiques et les indications spatio-temporelles, sont revêtues d’une valeur prophétique et d’une portée métathéâtrale : elles portent en germe tous les éléments de l’œuvre et élaborent une réflexion sur le théâtre lui-même. Lorca, dans cette partition didascalique compose une poétique du silence révélant les sentiments profonds des différents personnages de la trilogie. Les didascalies sont le souffle et la respiration du texte qui prend corps et vie devant nos yeux : leur déchiffrement permet d’accéder aux arcanes de l’œuvre. / The aim of this study is to analyse Garcia Lorca's poetic and dramatic use of stage directions with special reference to three plays : Bodas de Sangre , Yerma and La casa de Bernada Alba .There is no denying that since the birth of enunciative linguistics and drama speech analysis, a lot of in-depth research publications have been devoted to stage directions as reverberations of the author's voice . This study will offer a poetic reading of Lorca's stage directions and aim at demonstrating that the latter contribute to creating a specific semiotic code with both a strategic and poetic intent within Lorca's dramatic speech. Far from being a mere functional peritext only meant to organise and set up the staging of discourse between the characters, Lorca's stage directions embody the nerve centre of his poetic drama. They play an active part in building up the innermost meaning of his works, and offer essential keys for interpretation at various levels of reading and theatrical reception. Reading some of these stage directions is a source of enjoyment for the viewer-reader . If we consider them as mere linguistic signs, they can indeed be interpreted in a poetical perspective as text aids through their sound effects when spoken aloud. Yet ,they are restricted to the reader's exclusive benefit as , paradoxically enough, the stage director is very often unable to stage them in their entirety , even by summoning all the senses . These stage directions, analysed in the first phase of this study, can be labelled as 'reading directions '. The other kind of stage directions consists of the more concrete and physical details that can help organise the futur staging of the play. They have an action-inducing and conative function and , as such, are not textual - the author's original message being coded into another system of signs - These 'staging directions' are the focus of the second part of this study. The preliminary parts ( titles, subtitles and dramatis personae for instance), the varied hues, space and time indications are endowed with a metadrama and prophetical value. Indeed, they carry the seeds of all the main characteristics of Lorca's works and weave thoughts about the very essence of drama. By turning his stage directions into a real musical score, Lorca composes a poetry of silence revealing the innermost feelings of the various characters present in the trilogy. The stage directions breathe life into the text , which takes on flesh and blood under our eyes. Deciphering them enables the reader to lift the veil on the mysteries of Lorca's works.
13

r-critical points and Taylor expansion of the exponential map, for smooth immersions in Rk+n

García Monera, María 29 May 2015 (has links)
[EN] Classically, the study of the contact with hyperplanes and hyperspheres has been realized by using the family of height and distance squared functions. On the first part of the thesis, we analyze the Taylor expansion of the exponential map up to order three of a submanifold $M$ immersed in $\r n.$ Our main goal is to show its usefulness for the description of special contacts of the submanifolds with geometrical models. As we analyze the contacts of high order, the complexity of the calculations increases. In this work, through the Taylor expansion of the exponential map, we characterize the geometry of order higher than $3$ in terms of invariants of the immersion, so that the effective computations in specific cases become more affordable. It allows also to get new geometric insights. On the second part of the thesis, we introduce the concept of critical point of a smooth map between submanifolds. If we consider a differentiable $k$-dimensional manifold $M$ immersed in $\r{k+n},$ we know that its focal set can also be interpreted as the image of the critical points of the {\it normal map} $\nu(m,u): NM\to \r{k+n}$ defined by $\nu(m,u)=\pi_N(m,u)+ u,$ for $m\in M$ and $u\in N_mM,$ where $\pi_N:NM\to M$ denotes the normal bundle. In the same way, the parabolic set of a differential submanifold is given through the analysis of the singularities of the height functions over the submanifold. If we consider a differentiable $k$-dimensional manifold $M$ immersed in $\r{k+n},$ we know that its parabolic set can also be interpreted as the image of the critical points of the {\it generalized Gauss map} $\psi(m,u): NM\to \r{k+n}$ defined by $\psi(m,u)= u,$ for $u\in N_mM.$ Finally, we characterize the asymptotic directions as the tangent set of a $k$-dimensional manifold $M$ immersed in $\r{k+n}$ throughout the study of the singularities of the tangent map $\Omega(m,y): TM\to \r{k+n}$ defined by $\Omega(m,y)=\pi(m,y)+y,$ for $y\in T_mM,$ where $\pi:TM\to M$ denotes the tangent bundle. We describe first the focal set and its geometrical relation to the Veronese of curvature for $k$-dimensional immersions in $\r{k+n}.$ Then we define the $r$-critical points of a differential map $f:H \to K$ between two differential manifolds and characterize the $2$ and $3$-critical points of the normal map and generalized Gauss map. The number of these critical points at $m\in M$ may depend on the degeneration of the curvature ellipse and we calculate those numbers in the particular case that $M$ is an immersed surface in $\r{4}$ for the normal map and $\r{5}$ for the generalized Gauss map. / [ES] En general, el estudio del contacto con hiperplanos e hiperesferas se ha llevado a cabo usando la familia de funciones altura y la función distancia al cuadrado. En la primera parte de la tesis analizamos el desarrollo de Taylor de la aplicación exponencial hasta orden 3 de una subvariedad $M$ inmersa en $\r n.$ Nuestro principal objetivo es mostrar su utilidad en el estudio de contactos especiales de subvariedades con modelos geométricos. A medida que analizamos los contactos de orden mayor, la complejidad de las cuentas aumenta. En este trabajo, a través del desarrollo de Taylor de la aplicación exponencial, caracterizamos la geometría de orden mayor que $3$ en términos de invariantes geométricos de la inmersión, por lo que el trabajo con las cuentas en casos especiales se convierte en más manejable. Esto nos permite también obtener nuevos resultados geométricos. En la segunda parte de la tesis se introduce el concepto de punto crítico de una aplicación regular entre subvariedades. Si consideramos una variedad diferenciable $M$ de dimensión $k$ e inmersa en $\r{k+n},$ sabemos que su conjunto focal puede ser interpretado como la imagen de los puntos críticos de la {\it aplicación normal} $\nu(m,u): NM\to \r{k+n}$ definida por $\nu(m,u)=\pi_N(m,u)+ u,$ para $m\in M$ y $u\in N_mM,$ donde $\pi_N:NM\to M$ denota el fibrado normal. De la misma manera, el conjunto parabólico de una subvariedad diferencial viene dado por el análisis de las singularidades de la función altura sobre la subvariedad. Si consideramos una subvariedad $M$ de dimensión $k$ e inmersa en $\r{k+n},$ sabemos que su conjunto parabólico puede ser interpretado como la imagen de los puntos críticos de la {\it aplicación generalizada de Gauss} $\psi(m,u): NM\to \r{k+n}$ definida por $\psi(m,u)= u,$ donde $u\in N_mM.$ Finalmente, caracterizamos las direcciones asintóticas como el conjunto de direcciones del tangente de una subvariedad $M$ de dimensión $k$ e inmersa en $\r{k+n}$ a través del estudio de las singularidades de la aplicación tangente $\Omega(m,y): TM\to \r{k+n}$ definida por $\Omega(m,y)=\pi(m,y)+y,$ para $y\in T_mM,$ donde $\pi:TM\to M$ denota el fibrado tangente. Describimos primero el conjunto focal y su relación geométrica con la Veronese de curvatura para una variedad $k$ dimensional inmersa en $\r{k+n}.$ Entonces, definimos los puntos $r$-críticos de una aplicación $f:H \to K$ entre dos subvariedades y caracterizamos los puntos $2$ y $3$ críticos de la aplicación normal y la aplicación generalizada de Gauss. El número de estos puntos críticos en $m\in M$ depende de la degeneración de la elipse de curvatura y calculamos ese número en el caso particular de una superficie inmersa en $\r{4}$ para la aplicación normal y $\r{5}$ para la aplicación generalizada de Gauss. / [CAT] En general, l'estudi del contacte amb hiperplans i hiperesferes s'ha dut a terme utilitzant la família de funcions altura i la funció distància al quadrat. A la primera part de la tesi analitzem el desenvolupament de Taylor de l'aplicació exponencial fins a ordre 3 d'una subvarietat $M$ immersa en $\r n.$ El nostre principal objectiu és mostrar la seua utilitat en l'estudi de contactes especials de subvarietats amb models geomètrics. A mesura que analitzem els contactes d'ordre major, la complexitat dels comptes augmenta. En aquest treball, a través del desenvolupament de Taylor de l'aplicació exponencial, caracteritzem la geometria d'ordre major que $ 3 $ en termes d'invariants geomètrics de la immersió, de manera que el treball amb els comptes en casos especials es converteix en més manejable. Això ens permet també obtenir nous resultats geomètrics. A la segona part de la tesi s'introdueix el concepte de punt crític d'una aplicació regular entre subvarietats. Si considerem una varietat diferenciable $ M $ de dimensió $ k $ i immersa en $ \r {k + n}, $ sabem que el seu conjunt focal pot ser interpretat com la imatge dels punts crítics de la {\it aplicació normal} $ \nu (m, u): NM \to \r {k + n} $ definida per $ \nu (m, u) = \pi_N (m, u) + o, $ per $ m \in M $ i $ u \in N_mM, $ on $ \pi_N: NM \to M $ denota el fibrat normal. De la mateixa manera, el conjunt parabòlic d'una subvarietat diferencial ve donat per l'anàlisi de les singularitats de la funció altura sobre la subvarietat. Si considerem una subvarietat $ M $ de dimensió $ k $ i immersa en $ \r {k + n}, $ sabem que el seu conjunt parabòlic pot ser interpretat com la imatge dels punts crítics de la {\it aplicació generalitzada de Gauss} $ \psi (m, u): NM \to \r{k + n} $ definida per $ \psi (m, u) = u, $ on $ u \in N_mM. $ Finalment, caracteritzem les direccions asimptòtiques com el conjunt de direccions del tangent d'una subvarietat $ M $ de dimensió $ k $ i immersa en $ \r{k + n} $ a través de l'estudi de les singularitats de l'aplicació tangent $ \Omega (m, y): TM \to \r {k + n} $ definida per $ \Omega (m, y) = \pi (m, y) + y, $ per $ y \in T_mM, $ on $ \pi: TM \to M $ denota el fibrat tangent. Descrivim primer el conjunt focal i la seva relació geomètrica amb la Veronese de curvatura per a una varietat $ k $ dimensional immersa en $ \r{k + n}. $ Llavors, definim els punts $ r $-crítics d'una aplicació $ f: H \to K $ entre dues subvarietats i caracteritzem els punts $ 2 $ i $ 3 $ crítics de l'aplicació normal i l'aplicació generalitzada de Gauss. El nombre d'aquests punts crítics en $ m \in M $ depèn de la degeneració de l'el·lipse de curvatura i calculem aquest nombre en el cas particular d'una superfície immersa en $ \r{4} $ per a l'aplicació normal i $ \r{5} $ per a l'aplicació generalitzada de Gauss. / García Monera, M. (2015). r-critical points and Taylor expansion of the exponential map, for smooth immersions in Rk+n [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/50935 / TESIS
14

La construction de relations de confiance au sein des équipes-écoles d’établissements en milieu autochtone du Québec selon les perceptions de leur direction

Deschênes, Emilie January 2016 (has links)
Résumé : La gestion des ressources humaines dans les écoles situées au sein de communautés autochtones est marquée par différents enjeux d’ordres social, culturel, ethnoculturel, économique et administratif qui impactent les pratiques de leurs directions. Ceux-ci touchent à tous les aspects de la gestion des écoles et peuvent être révélateurs d’un malaise dans l’encadrement des actrices et des acteurs à travers des structures administratives, juridiques, éducatives ou de gouvernance qui comportent des défis relationnels et interactionnels majeurs. Ce type de malaise peut moduler les actions des actrices et des acteurs des établissements et peut entrainer des impacts dans leurs relations, notamment au niveau de leurs relations de confiance, essentielles à la qualité de leurs actions communes. L’approfondissement de cette problématique porte essentiellement sur les conditions associées à la construction de la confiance qui sont de différents ordres, c’est-à-dire contextuel, institutionnel, organisationnel, relationnel ou individuel. Utilisant une approche qualitative, cette recherche repose sur vingt-trois entrevues semi-dirigées avec des directions d’établissement provenant de dix-sept communautés et de trois nations autochtones différentes. L’analyse est menée à partir d’une approche exploratoire constructiviste et interprétativiste. Les conclusions permettent de dégager que la construction de relations de confiance entre des actrices et des acteurs sont tributaires de conditions dans lesquelles s’inscrivent des dynamiques interactionnelles particulières. Influencées par le contexte autochtone singulier, ces conditions sont préalables aux actrices et aux acteurs ou associées à leurs comportements, attitudes, actions ou pratiques. Il apparait que ces dynamiques s’inscrivent dans une configuration des équipes-écoles se caractérisant par six catégories-types d’individus qui se déclinent selon leur origine et leur appartenance ou leur identité ethnique, à savoir les voyageurs autochtones et allochtones, les étrangers autochtones et allochtones et les natifs autochtones et allochtones. La meilleure compréhension de cette organisation conduit à une conception large de la configuration des dynamiques interactionnelles entre des individus et des groupes et entre des communautés d’individus. Ces individus s’affilient spécifiquement selon des identités ou des appartenances individuelles ou de groupe qui peuvent être de différents ordres soit particulièrement, mais non exclusivement, ethnique, linguistique, familial ou se rapportant à des croyances particulières. / Abstract : This research studies the dynamic of building trust relationships between actors in schools that are located in Aboriginal communities. This dynamic is studied based-on school administrators’ perceptions, according to their observations of their school team and the environment, their professional practices, their professional and life experiences and the meanings that they attach to them. The study can be considered as a global approach in order to provide a better understanding of the context of school management and school administration in an Aboriginal context. In order to conduct this study in this particular environment, a specific focus lied on the examination of the conditions that lead actors to build or not to build trust with others. On the one hand, the concern of this research relied on the particular Aboriginal context that is characterized by social, cultural, ethno-cultural, economic or administrative issues, where the effective execution of the roles, responsibilities and duties of directors and school administrators appears complex. This complexity particularly concerns the impact of these issues on human relations and personnel management. On the other hand, this study was based on the idea that trust between staff members could have the potential to tinge these relationships. Trust might even be considered as key to optimal education management, to a climate that leads to efficient work, and therefore, to the students’ success. Specific research objectives are the better understanding of the dynamics of trust within school teams at schools located in Aboriginal communities, namely: 1) the analysis of interviews with principals of indigenous schools in light of the conceptual framework; 2) a cross-sectional analysis that allows to determine the conditions that contribute to building trust relationships within their school team; and 3) the proposal of models that suggest various elements that help to understanding the dynamics of building relationships of trust, when seen from different perspectives. These objectives led to the choice of a qualitative research methodology with a constructivist and interpretativist epistemological position. This research is also of an exploratory nature, using semi-structured interviews. Twenty-three principals from seventeen communities and three different Nations were interviewed. The thematic data analysis of the collected material permitted to point out that building trustworthy relationships and modulating relationships of mistrust between actors with heterogeneous characteristics depend on various conditions. Under the influence of the singular Aboriginal context, these conditions that determine how trust relationships are built are anterior to the actors, or associated with their behaviors, attitudes, actions or practices. It seems that these dynamics are context-related to a singular organization of school teams. They can be characterized by determining six categories of individuals, according to their origin and their affiliation or their ethnic identity: indigenous and non-indigenous travelers, indigenous and non-indigenous foreigners and indigenous and non-indigenous natives. Providing a better understanding of this organization leads to a broader conception of the possible configurations of the organizational culture of schools in Aboriginal communities: the configuration of interactional dynamics between individuals and groups (intracommunity dynamic of individuals), and between individuals and communities (intercommunity dynamic of individuals). Specific affiliations exist among those individuals, depending on their identities or on individual or group affiliations. In particular, but non-exclusively, these affiliations are ethnic, linguistic, family, or they are related to particular beliefs.
15

Ledarutvecklingens trender - Isomorfism eller innovation?

Örtberg, Annika January 2015 (has links)
Leadership development trends - isomorphism or innovation? This study examines leadership development within organizations, including strategies, objectives and processes that help to shape the organizations leadership development. The study is based on nine in-depth interviews with planners/decision-makers in eight different organizations. A part of the study consists of a web based survey completed by managers/leaders, were the gathered results assist in providing further insight on the topic being studied. The interaction between different players and stakeholders, significant social changes as well as major challenges in the continued leadership development process are highlighted and analysed. The study's most important conclusion is that successful and innovative leadership development is based on constant curiosity, business intelligence, understanding of the individual employee’s needs, as well as and business goals whilst achieving this by constant interaction throughout the organization. The overall trend is that leadership development is being increasingly adapted and renewed. Knowledge, understanding, relationships and values are strengthened and that coaching, personal development and a capability for renewal are provided.
16

A Novel Progressive Lossy-to-Lossless Coding Method for Mesh Models of Images

Feng, Xiao 29 July 2015 (has links)
A novel progressive lossy-to-lossless coding method is proposed for mesh models of images whose underlying triangulations have arbitrary connectivity. For a triangulation T of a set P of points, our proposed method represents the connectivity of T as a sequence of edge flips that maps a uniquely-determined Delaunay triangulation (i.e., preferred-directions Delaunay triangulation) of P to T. The coding efficiency of our method is highest when the underlying triangulation connectivity is close to Delaunay, and slowly degrades as connectivity moves away from being Delaunay. Through experimental results, we show that our proposed coding method is able to significantly outperform a simple baseline coding scheme. Furthermore, our proposed method can outperform traditional connectivity coding methods for meshes that do not deviate too far from Delaunay connectivity. This result is of practical significance since, in many applications, mesh connectivity is often not so far from being Delaunay, due to the good approximation properties of Delaunay triangulations. / Graduate
17

Automated creation of pedestrian route descriptions

Schroder, Catherine Jane January 2013 (has links)
Providing unambiguous, succinct descriptions of routes for pedestrians to follow is very challenging. Route descriptions vary according to many things, such as route length and complexity, availability of easily identifiable landmarks, and personal preferences. It is well known that the inclusion of a variety of landmarks facilitates route following – either at key decision points, or as a confirmatory cue. Many of the existing solutions, however, behave like car navigation systems and do not include references to such landmarks. The broader ambition of this research is the automatic generation of route descriptions that cater specifically to the needs of the pedestrian. More specifically this research describes empirical evidence gathered to identify the information requirements for an automated pedestrian navigation system. The results of three experiments helped to identify the criteria that govern the relative saliency of features of interest within an urban environment. There are a large variety of features of interest (together with their descriptions) that can be used as directional aids within route descriptions (for example buildings, statues, monuments, hills, and roads). A set of variables were developed in order to measure the saliency of the different classes of features. The experiments revealed that the most important measures of saliency included name, size, age, and colour. This empirical work formed the basis of the development of a pedestrian navigation system that incorporated the automatic identification of features of interest using the City of Edinburgh as the study area. Additionally the system supported the calculation of the saliency of a feature of interest, the development of an intervisibility model for the route to be navigated to determine the best feature of interest to use at each decision point along the route. Finally, the pedestrian navigation system was evaluated against route descriptions gathered from a random set of individuals to see how efficiently the system reflected the more natural and richer route description that people typically generate. This work shows that modelling features of interest is the key to the automatic generation of route descriptions that can be readily understood and followed by pedestrians.
18

The relative benefit of reliable heading updates on urban wayfinding

Waters, Wilfred January 2010 (has links)
Prior research about wayfinding has found that females tend to employ a single strategy based on landmarks, where males are more versatile, using a dual strategy of landmarks and global orientation information such as cardinal directions (Lawton, 2010). It was proposed that this difference occurs due to males’ better sense of direction, which would deliver more trustworthy indications of current heading. Since males’ versatility has often been linked with better navigation performance (for example Sandstrom, Kaufman, & Huettel, 1998; Saucier et al., 2002) this study sought to contribute to the growing body of literature on methods of training to increase sense of direction (such as Hund and Minarik, 2006; Hund & Nazarczuk, 2009). An experimental procedure was used to investigate the possibility that the provision of reliable cardinal direction heading updates to participants would lead to a dual strategy for orientation in those that usually use a single strategy based on landmarks. This was done in an urban navigation context, with the main dependent variable being level of recall for route structure. Using the Santa Barbara Sense of Direction Scale, the study revealed that males had a higher self-reported sense of direction than females. / Additionally, no sex differences in performance were found on the route structure recall tasks. Rather than being due to females’ use of a dual wayfinding strategy, however, this was interpreted as an artefact of the use of a video in the procedure, which involved watching someone else navigating along a route. This is supported by another finding, that conditions containing cardinal directions or landmark spatial references did not produce higher route structure recall than the control condition. Since the procedure did not require participants to navigate through a real, or virtual, environment, it may not have been perceived as a disorientation threat. Due to this, they may not have employed wayfinding strategies, accounting for the poor influence of the spatial reference conditions and the lack of sex difference. The study is therefore viewed as an ideal candidate for replication by future investigators, who may wish to compare performance using a task where participants are required to deploy wayfinding strategies.
19

Generation and Analysis of Verbal Route Directions for Blind Navigation

Nicholson, John 01 May 2010 (has links)
According to the National Federation of the Blind, there are an estimated 10 million people in the United States who are visually impaired. Of these, 1.3 million are legally blind. Many people with extreme vision loss receive orientation and mobility training in order to help them learn skills that allow them to travel and navigate multiple types of indoor and outdoor environments. Even with this training, a fundamental problem these people face is learning new routes, especially in environments with which they are not familiar. Although the research community has developed a number of localization and navigation aids that are meant to provide navigation assistance, only a handful have reached the marketplace, and the adoption rate for these devices remains low. Most assistive navigation devices take responsibility for the navigation and localization processes, leaving the user only to respond to the devices' commands. This thesis takes a different approach and proposes that because of the high level of navigation ability achieved through years of training and everyday travel, the navigation skills of people with visual impairments should be considered an integral part of the navigation system. People with visual impairments are capable of following natural language instructions similar to those given by a visually impaired person communicating route directions over the phone to another person with visual impairments. Devices based on this premise can be built, delivering only verbal route descriptions. As a result, it is not necessary to install complex sensors in the environment. This thesis has four hypotheses that are addressed by two systems. The first hypothesis is that a navigational assistance system for the blind can leverage the skills and abilities of the visually impaired, and does not necessarily need complex sensors embedded in the environment to succeed. The second hypothesis is that verbal route descriptions are adequate for guiding a person with visual impairments when shopping in a supermarket for products located in aisles on shelves. These two hypotheses are addressed by ShopTalk, a system which helps blind users shop independently in a grocery store using verbal route descriptions. The third hypothesis is that information extraction techniques can be used to extract landmarks from natural language route descriptions. The fourth and final hypothesis is that new natural language route descriptions can be inferred from a set of landmarks and a set of natural language route descriptions whose statements have been tagged with landmarks from the landmark set. These two hypotheses are addressed by the Route Analysis Engine, an information extraction-based system for analyzing natural language route descriptions.
20

Mantis: A Predictive Driving Directions Recommendation System

Hoover, Christopher 01 June 2013 (has links) (PDF)
This thesis presents Mantis, a system designed to evaluate possible driving routes and recommend the optimal route based on current and predicted travel conditions. The system uses the Bing Maps REST service to obtain a set of routes. Traffic data from the California Department of Transportation’s Performance Measurement System (PeMS) is then used to estimate travel times for these routes. In addition to simple travel time estimation based on instantaneous traffic conditions, Mantis can use historic data to predict traffic speeds at future times. This allows Mantis to more effectively account for regularly repeating traffic patterns such as rush hour, increasing the accuracy of its travel time estimates. Mantis is also capable of monitoring traffic incidents reported by the California Highway Patrol and identifying incidents that will be encountered along a route’s path.

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