Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 63-66). Also available via the Internet.

Cette thèse s'inscrit dans le cadre de la détection de marquages pour un véhicule autonome. Notre objectif est la réalisation d'un algorithme capable de détecter les différents marquages routiers liés aux voies de circulation à l'aide d'une caméra. Pour ce faire, nous avons proposé une approche fondée sur un système multi-agents avec des agents réactifs. Cette approche permet de faire évoluer les agents dans la direction des zones ayant des similitudes avec un marquage routier ainsi qu'une forte intensité lumineuse. Cette approche procède par propagation du bas vers le haut de l'image à l'inverse de la majorité des méthodes rencontrées dans la littérature. La trace de chaque agent est ensuite lissée grâce à des splines de lissages cubiques pondérées par les niveaux de confiance associés aux pixels parcourus par ces derniers. On obtient ainsi les estimations des marquages routiers. Une seconde partie du travail consiste à identifier les tirets de marquages routiers et à les suivre temporellement afin de rendre plus robuste le processus de détection ainsi que de catégoriser les marquages routiers. Cette méthode nous permet ainsi de supprimer toutes les parties incohérentes des traces des agents ainsi que de détecter et de réagir en conséquence aux décrochages de l'agent au marquage. Enfin, des expérimentations sur des données réelles et artificielles ont été réalisées afin de comparer l'approche proposée avec des travaux de recherche et des prototypes industriels. Ces expérimentations prouvent l'efficacité des méthodes par propagation en général, et de l'approche proposée en particulier. / This thesis is part of the road marking detection for autonomous vehicle.Our objective is the realisation of an algorithm that detects road markings linked to lanes with a video camera. In order to achieve this, we proposed an approach based on a multi-agents system, with active agents. In this system, agents evolve in the direction of bright areas with similarities to a road marking. This approach proceeds by the propagation from bottom to top of the image in contrast to the majority of methods found in literature.The track of each agent is then (smoothed) (fitted) by smoothing cubic splines weighted by the confidence levels associated to the pixels traveled (by them). That way, the estimation of road markings is obtained for each lane. A second part of the work is to identify lane markers of each line and to track them over time in order to improve the robustness of the detection process and to categorize the road markings. This method allows us to remove all incoherent parts of the agents tracks and to detect and to react accordingly when the agent goes out of the road line marking. Finally, experiments on real and artificial data were conducted to compare the proposed approach with research algorithm and industrial prototypes. These experiments demonstrate the effectiveness of propagation methods in general and also our specific approach.

Reproduction de : Thèse de doctorat : mathematiques appliquees : Grenoble 1 : 1990. / Titre provenant de l'écran-titre. Bibliogr. p. 97-104.

No description available.

Thèses (M.Sc.)--Université de Sherbrooke (Canada), 1999. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Spline smoothers as implemented in common mixed model software provide a familiar framework for estimating semi-parametric and non-parametric models. Following a review of literature on splines and mixed models, details for implementing mixed model splines are presented. The examples use an experiment in the health sciences to demonstrate how to use mixed models to generate the smoothers. The first example takes a simple one-group case, while the second example fits an expanded model using three groups simultaneously. The second example also demonstrates how to fit confidence bands to the three-group model. The examples use mixed model software as implemented in lme() in R. Following the examples a discussion of the method is presented.

No description available.

One day fully autonomous AUV's will no longer require human interactions to complete its missions. To make this a reality, the AUV must be able to safely navigate in unfamiliar environments with unknown obstacles. This thesis builds on previous work conducted at NPS's Center for AUV Research to improve the autonomy of the REMUS class of AUVs with an implemented FLS. The first part of this thesis deals with accurate path following with the use of look-ahead pitch calculations. With the use of a SIMULINK model, constraints surrounding obstacle avoidance path planning are then explored, focusing on optimal sensor orientation issues. Two path planning methods are developed to address the issues of a limited sonar field of view and uncertainties brought on by an occlusion area. The first approach utilizes a pop-up maneuver to increase the field of view and minimize the occlusion area, while the second approach creates a path with the addition of a spline. Comparing the two methods, it was concluded that spline addition planner provided a robust optimal obstacle avoidance path and along with the look-ahead pitch controller completes the design of a "back-seat driver" to improve REMUS's survivability in an unknown environment. / US Navy (USN) author.

Made available in DSpace on 2014-06-12T17:37:51Z (GMT). No. of bitstreams: 2 arquivo3321_1.pdf: 6871250 bytes, checksum: 97728d447c4216ee1df930d2bc6e730c (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Fundação de Amparo a Pesquisa do Estado de Alagoas / O concreto, sob um campo de tensões, está suscetível ao aumento das deformações ao longo do tempo causado pelo fenômeno denominado de Fluência. Este fenômeno, diretamente relacionado com a estrutura interna do concreto, está condicionado a diversos fatores como: resistência à compressão, idade de aplicação dos carregamentos, condições de cura, temperatura ambiente e materiais empregados na dosagem do concreto como o tipo de cimento e agregado, aditivos e fator água/cimento. O comportamento reológico do concreto também está relacionado com o modo de aplicação do carregamento (repentinamente ou gradativamente ao longo do tempo). É bastante comum encontrar na literatura técnica especializada estudos sobre o concreto submetido a tensão de compressão uniaxial, todavia, vale ressaltar que este fenômeno também ocorre sob estados de tensão multiaxial. Em vigas de concreto armado, o estudo da fluência é importante quando se pretende estimar a deflexão final. Em vigas de concreto protendido, o estudo da fluência é importante para determinar as perdas de protensão (afrouxamento dos da armadura ativa) ao longo da vida útil da estrutura. O presente estudo analisa vigas de seção celular (vigas caixão) através da evolução das tensões e máximas deflexões ao longo do tempo. Neste estudo é empregada uma modelagem computacional no ambiente MATLAB e utilizando o Método das Faixas Finitas com interpolação B3 Splines, tal método permite efetuar uma interpolação cúbica entre dois nós da malha de Elementos Finitos, acarretando um menor custo computacional. O cabo protendido é considerado como uma poligonal que se desenvolve dentro da viga e no espaço tridimensional (caso mais geral). A formulação aqui desenvolvida considera tanto as perdas iniciais (atrito, escorregamento da ancoragem e encurtamento elástico do concreto) quanto as perdas progressivas (fluência, retração e relaxação da armadura ativa)

In this thesis a method for direct evaluation of Generalized B-splines (GB-splines) via the representation of these curves as piecewise functions is presented. A local structure is introduced that makes the GB-spline curves more amenable to the integration used in constructing bases of higher degree. This basis is used to perform direct computation of piecewise representation of GB-spline bases and curves. Algorithms for refinement using these local structures are also developed.