A new progressive lossy-to-lossless coding method for arbitrarily-connected triangle mesh models of bivariate functions is proposed. The algorithm employs a novel representation of a mesh dataset called a bivariate-function description (BFD) tree, and codes the tree in an efficient manner. The proposed coder yields a particularly compact description of the mesh connectivity by only coding the constrained edges that are not locally preferred Delaunay (locally PD). Experimental results show our method to be vastly superior to previously-proposed coding frameworks for both lossless and progressive coding performance. For lossless coding performance, the proposed method produces the coded bitstreams that are 27.3% and 68.1% smaller than those generated by the Edgebreaker and Wavemesh methods, respectively. The progressive coding performance is measured in terms of the PSNR of function reconstructions generated from the meshes decoded at intermediate stages. The experimental results show that the function approximations obtained with the proposed approach are vastly superior to those yielded with the image tree (IT) method, the scattered data coding (SDC) method, the average-difference image tree (ADIT) method, and the Wavemesh method with an average improvement of 4.70 dB, 10.06 dB, 2.92 dB, and 10.19 dB in PSNR, respectively. The proposed coding approach can also be combined with a mesh generator to form a highly effective mesh-based image coding system, which is evaluated by comparing to the popular JPEG2000 codec for images that are nearly piecewise smooth. The images are compressed with the mesh-based image coder and the JPEG2000 codec at the fixed compression rates and the quality of the resulting reconstructions are measured in terms of PSNR. The images obtained with our method are shown to have a better quality than those produced by the JPEG2000 codec, with an average improvement of 3.46 dB. / Graduate

Les aides à la conduite sont des systèmes qui aident le conducteur à mieux appréhender la tâche de conduite en situation difficile. Parmi les différents capteurs qu'utilisent ces ADAS, des caméras sont embarquées et délivrent des images de la scène routière qui sont traitées et analysées de manière à informer le conducteur des dangers éventuels ou enclencher des systèmes d'urgence. Les caméras issues de ces ADAS capturent l'environnement routier d'une manière qui est loin d'être représentative de la perception qu'aurait un conducteur. Une des conséquences éventuelles est que ces ADAS soient contre-productives en déclenchant inopinément des systèmes d'alerte et d'action à l'encontre du conducteur. De manière à remplir complétement la vocation de ces ADAS, il est primordial de disposer d'une carte de la perception de l'environnement routier du point de vue du conducteur de manière à ajuster l'aide dont il pourrait avoir besoin. Nous proposons d'estimer par traitement d'image, la visibilité routière du point de vue du conducteur en utilisant un algorithme bio-inspiré simulant la sensibilité au contraste de l'œil humain. Dans un premier temps, nous étendons un modèle de CSF (Contrast Sensitivity Function) de manière à prendre en compte des taux de détection cohérents avec la sécurité routière, l'orientation, la couleur et l'âge du conducteur. Dans un second temps, nous modélisons notre modèle de CSF par un filtrage spatial et en calculons la visibilité en chaque pixel de l'image. Nous appliquons cette carte de visibilité sur une carte de contours issue de notre détecteur de contour bio-inspiré. Ainsi, nous considérons les contours des objets routiers présents dans l'image plutôt que leurs caractéristiques de manière à éviter toute hypothèse. Ces contours sont associés à un niveau de visibilité indiquant s'ils sont visibles ou pas par l'observateur. Nous validons le procédé en le comparant à des performances visuelles d'observateurs, en condition de laboratoire, pour une détection de cible et en situation de conduite simulée en conduite de nuit. Dans un deuxième temps, nous associons ces niveaux de visibilité en deux unités facilement compréhensibles pour des ADAS: un temps de réaction et une distance perçue. En premier lieu, nous proposons un modèle d'estimation du temps de perception du conducteur en fonction de la visibilité en nous inspirant de la loi de Piéron sur des données expérimentales de détection de cibles sur des images routières de synthèse pour une certaine densité de brouillard de jour. Les études ont montré que les conducteurs auraient tendance à se rapprocher du véhicule devant eux de manière à ne pas les perdre de vue. Ce constat nous renseigne sur le fait que le conducteur ne dispose pas suffisamment de visibilité à ses yeux dans cette configuration de conduite. Nous montrons l'intérêt des méthodes de restauration d'images en termes de gain de temps de réaction et de performance visuelle comme le taux de détection du véhicule devant lui. Dans un second temps, nous estimons une distance par rapport au véhicule précédent du point de vue du conducteur en nous inspirant de la détection des feux arrière du véhicule situé devant le conducteur. Les résultats ont montré que les conducteurs estimaient mal les distances sur obstacles lointains en comparaison des aides à la conduite basées sur des imageurs optique, radar ou lidar pour une conduite de nuit. D'après ce constat, les ADAS jouent un rôle fondamental pour prévenir le conducteur de sa conduite inadaptée. Enfin, nous délimitons les limites de nos modèles de CSF et de visibilité et proposons plusieurs perspectives. Pour des applications routières, une des perspectives qui a été concrétisée partiellement est l'évaluation objective des systèmes d'éclairage par notre modèle de visibilité et sa cohérence avec une expertise subjective / The driver assistance systems are systems that help the driver to better understand the plight driving task. Among the various sensors used by these ADAS, cameras are shipped and deliver images of the road scene which are processed and analyzed to inform the driver of potential hazards or switch of emergency systems. The cameras capture from these ADAS is far from representative of perception would have a driver. One of the possible consequences is that these ADAS can be counter productive in triggering warning and action against the driver. In order to completely fulfill the objectives of such ADAS, it is essential to have a map of the perception of the road environment from the perspective of the driver to adjust the help they might need. We propose to estimate by image processing, road visibility from the driver's perspective using a bio-inspired algorithm simulating the contrast sensitivity of the human eye. First, we extend a model of CSF (Contrast Sensitivity Function) to consider coherent detection rate with road safety, orientation, color and age of the driver. In a second step, we model our CSF spatial filtering and calculate the visibility for each pixel of the image. We apply this visibility map on a map of contours of our bio-inspired edge detector. Thus, we consider the contours of the road objects in the image rather than the characteristics in order to avoid assumptions. These contours are associated with a level of visibility as to whether or not they are visible by the observer. We validate the method by comparing it with the visual performance of observers in laboratory conditions for target detection and simulated driving situation in night driving. Secondly, we combine these two levels of visibility in easily understandable units for ADAS: a reaction time and a target distance. First, we propose a model to estimate the driver's reaction time depending on the visibility (inspired by Piéron's law of target detection) with experimental data on road synthetic images for some daylight fog density. Studies have shown that drivers would tend toget closer to the vehicle in front of them in order not to lose sight of them. This observation tells us that the driver does not have enough visibility in that configuration. We show the interest of the image restoration methods in terms of reaction time and gain in visual performance as well as vehicle detection rate. In a second step, we estimate a distance from the point of view of the driver taking inspiration from the detection of the rear lights of the vehicle in front of the driver. The results showed that drivers were bad about the distance evaluation of distant obstacles compared to driving aids based on optical imaging, radar or lidar for night driving. Based on this observation, the ADAS may play a fundamental role in preventing the driver from his inappropriate behavior. Finally, we outline the limits of our models CSF and visibility and offer several perspectives for road applications, one of which was the objective evaluation of lighting systems by our model of visibility and consistency with a subjective expertise

The role of a roof on any building is to separate the interior environment of the building from the exterior environment, thereby making it a crucial component of the building design. Metal roof edges are the first line of defense against wind-induced loads on the roof system; however, data on the nature of these loads acting on the roof edge system is scarce. Previous studies with field measurements of wind pressure acting on the roof edge reported that metal flashings experienced negative pressure. These findings suggest that current building codes in North America (i.e. NBCC and ASCE codes) do not accurately identify wind design loads acting on roof edge systems. The Roof Edge Systems and Technologies (REST) project is a consortium of academia, government and roof industries, which was created to develop testing protocols and design guidelines for roof edges. The work presented in this thesis contributes to the collection and analysis of wind loads acting on metal roof edges, which were installed on the Canada Post building in Vancouver, Canada. The thesis presents the findings and analysis of the measured wind-induced pressure acting on all surfaces of three different edge configurations, namely the Anchor Clip Configuration (ACC), Continuous Cleat Configuration (CCC) and Discontinuous Cleat Configuration (DCC). The analysis showed the presence of negative pressure acting on all three faces of the configurations, in which the type of configuration had minimum effect on the magnitude and nature of the wind-induced loads. Furthermore, the top face of the edge configurations was found to experience the highest suction, and the front face of the edge coping was subjected to a net outward suction force due to the combination of the suction experienced by the coping front face and the positive pressure acting on the cleat. Comparison of these results with current NBCC and ASCE building codes highlight a need to update these codes in order to adequately design metal roof edges against wind action.

No description available.

No description available.

Orientadores: Peter Alexander Bleinroth Schulz, Ana Luiza Cardoso Pereira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-18T12:03:32Z (GMT). No. of bitstreams: 1 BahamonArdila_DarioAndres_D.pdf: 15568018 bytes, checksum: 6b550b7e0291945e86b0152735b9ea2c (MD5) Previous issue date: 2011 / Resumo: Neste trabalho analisamos os efeitos das bordas nas propriedades eletrônicas e de transporte em estruturas finitas de grafeno, como nanofitas, pontos quânticos e anéis quânticos de grafeno. Nós focamos essencialmente no acoplamento entre os estados localizados nas bordas externas e estados localizados nas bordas internas, tais como as bordas internas dos anéis, vacâncias ou defeitos estendidos gerados pelas fronteiras de grão. Os cálculos são abordados no formalismo tight-binding para a rede hexagonal do grafeno. Para calcular as propriedades de transporte utilizamos o formalismo de Landauer-Buttiker e as funções de Green da rede. Para anéis quânticos observamos que a evolução dos estados localizados nas bordas internas, em função do campo magnético é oposta à dos estados localizados nas bordas externas. Tanto para anéis quânticos quanto para nanofitas, quando a magnitude do campo magnético gera um comprimento magnético maior do que a metade da separação entre as bordas internas e externas, os estados se acoplam levando à criação de gaps no espectro de auto-energias e ressonâncias de Fano na condutância. Este cenário é enriquecido pelo fato do grafeno ter duas sub-redes (novo grau de liberdade), identi cando que uma mudança na sub-rede dos átomos mais externos ou mais internos dos braços vizinhos de um anel muda a distribuição de carga e que a sub-rede de uma vacância fortemente modifica a forma de linha da condutância em uma nanofita. O mapeamento da densidade local de estados, diferenciada por sub-rede, nos leva a propor uma possível imagem experimental da força de acoplamento, que caracteriza a forma de linha das ressonâncias Fano. Quando consideramos um defeito estendido na rede do grafeno (defeito linear como os recentemente observados experimentalmente) foi encontrado que ele age como uma borda interna, que adiciona um novo canal para elétrons de baixa energia, e que tem aplicações promissórias como um o metálico quântico. Todos os nossos resultados são robustos quando a desordem nas bordas é incluído / Abstract: This work is concerned with the effects of the edges in the electronic and transport properties of nite structures of graphene, such as quantum dots, quantum rings and graphene nanoribbons. We primarily focus on the coupling between states located at the outer edges and states located at the inner edges, as internal edges of rings, vacancies or extended defects generated by the grain boundaries. The calculations are addressed within the tight-binding formalism for the hexagonal lattice. To calculate the transport properties we use the Landauer-B uttiker formalism and the recursive lattice Green's functions. For quantum rings we observed that the evolution of the states located at the inner edges, as a function of magnetic eld is opposite to that of the states located on the outer edges. For quantum rings as well as graphene nanoribbons when the magnitude of the magnetic eld creates a magnetic length larger than a half of the separation between the inner and outer edges, the states are coupled creating gaps in the self-energy spectrum and Fano resonances in the conductance of the graphene nanoribbons. This scenario is enriched when the sublattice is added as a new degree of freedom, identifying that a change in sublattice of the most external or most internal atoms of neighboring arms of a ring changes the charge distribution and the sublattice of a vacancy strongly modify the lineshape of the conductance. Sublattice differentiated Local density of states mapping for different lineshapes leading us to propose a possible experimental imaging of the coupling strength, which characterizes the lineshape of the Fano resonances. When we considered the recently experimentally observed extended defect, we found that it acts as an internal edge, which adds a new channel for low energy electrons, and would have promissory applications as metallic wire. All of our results are robust when edge disorder is included / Doutorado / Física da Matéria Condensada / Doutor em Ciências

Understanding movement capabilities of individuals within a landscape is essential to identifying the effects of habitat boundaries on species abundances, ranges, and spread rates. Movement barriers due to habitat fragmentation may reduce mate-finding ability in some species, particularly in heterogeneous landscapes containing low-density populations. This study focuses on the effects of habitat type and edge on mate-finding in an invasive defoliator, the European gypsy moth. Adult European gypsy moth males locate mates by following pheromones released by flightless females. Reduced mate-finding was expected in fields and near forest edges based on geographic variation in invasion rates and pheromone plume dynamics. A male release-recapture experiment using female-baited traps in fields, at forest edges, and in the forest interior showed that mate-finding was highest at forest edges, reduced in fields, and lowest within the forest interior. This suggests that forest edges and moderate habitat fragmentation enhance mate-finding in the gypsy moth.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 144-148. / by David Scott Greeley. / Ph.D.

Boundary-layer flows near leading edges of generally curved obstacles have been studied for a long time. Apart from having many practical applications, the theory and approaches prevailing in this area stimulate development of a variety of computational tools and form a ground for testing them. The specific aim of this work is to study two-dimensional laminar boundary layer flows near the leading edges of airfoils and other elongated bodies, and to explore geometries for which boundary layer separation can be avoided. This class of problems is relevant to optimal design of wings, aircraft and projectile noses, laminar flow control methods and adaptive wing technology. One of the findings of this work suggests that local modifications to parabolic wing noses can yield up to 11% increase in the unseparated angle of attack. Another result obtained here is the set of shortest possible generalised elliptic noses of long symmetric bodies which allow unseparated flow. Methods adopted in this work are based on the combined use of numerically solved Prandtl equations written in Gortler variables, and inviscid solutions obtained semi-analytically by the conformal mapping method. The resulting technique being reliable, fast and computationally inexpensive, can complement or test the results obtained using a comprehensive CFD approach. / Thesis (Ph.D.)--School of Mathematical Sciences, 2002.

CETTE THÈSE INTRODUIT UNE CLASSE DES TRANSFORMÉS MULTI­ ÉCHELLES BIDIMENSIONNELLES ADAPTÉES AUX CONTOURS. CELLES-CI SONT DIFFÉ­RENTES DES TRANSFORMÉES EN ONDELETTES BIDIMENSIONNELLES, CAR ELLES SONT BASÉES SUR DES OPÉRATEURS NONLINÉAIRES DEPENDENTS DES DONNÉES. CES OPÉRATEURS SONT INSPIRÉS DES OPÉRATEURS D'INTERPOLATION ENO INTRODUITS PAR HARTEN ET OSHER DANS LE CONTEXTE DE LA SIMULATION NUMÉRIQUES DES ONDES DE CHOC. LE BUT EST D'INCLURE DANS LA TRANSFORMÉE UN TRAITEMENT SPECIFIC DES CONTOURS QUI, EN TENANT COMPTE DE LEURS RÉGULARITÉ GEOMETRIQUE, PERMETTRAS D'OBTENIR DES REPRÉSENTATIONS PLUS CREUSES ET DONC DES MEILLEU­RES PROPRIÉTÉS D'APPROXIMATIONS. D'UN POINT DE VUE THÉORIQUE ON S'INTERESSE À LA CONSERVATION DES MÊME PROPRIÉTÉS DE CONCENTRATION POUR LES ESPACES FONCTIONNELS CLASSIQUES (BESOV ET $BV$), ET ON S'INTERROGE AUSSI SUR LA STABILITÉ DE CES DÉ­COMPOSITIONS. CE PROBLÈME EST LOIN D'ÊTRE AUSSI SIMPLE QUE DANS LE CAS DES REPRÉ­SENTATIONS LINÉAIRES. NOUS ABORDONS DANS CETTE THÈSE CHACUNE DE CES DIFFICULTÉS, ET NOUS Y APPORTONS DES ÉLÉMENTS DE RÉPONSE, AINSI QUE DES TESTS NUMÉRIQUES VISANT À ÉVALUER CONCRÈTEMENT LES PERFORMANCES DES MÉTHODES PROPOSÉES.