Thesis (doctoral)--Universitate Friderica Guilelma, 1864. / Vita.

No description available.

Precomputation has been previously used as a means to get global illumination effects in real-time on consumer hardware of the day. Our work uses Sloan’s 2002 PRT method as a starting point, and builds on it with two new ideas. We first explore an alternative representation for PRT data. “Cpherical harmonics” (CH) are introduced as an alternative to spherical harmonics, by substituting the Chebyshev polynomial in the place of the Legendre polynomial as the orthogonal polynomial in the spherical harmonics definition. We show that CH can be used instead of SH for PRT with near-equivalent performance. “Vector occluders” (VO) are introduced as a novel, precomputed, real-time, empirical technique for adding global illumination effects including shadows, caustics and interreflections to a locally illuminated scene on static geometry. VO encodes PRT data as simple vectors instead of using SH. VO can handle point lights, whereas a standard SH implementation cannot. / UOIT

No description available.

[pt] Em [23] são apresentadas igualdades e desigualdades isoperimétricas relacionadas à Cáustica de Wigner (CW) e ao Conjunto de Medida de Largura Constante (CMLC). Neste trabalho nós estendemos estes resultados para planos normados com bolas unitárias quadraticamente convexas ou bolas unitárias poligonais. Estes conjuntos CW e CMLC estão fortemente relacionados às ciclóides, que são curvas cujas funções suporte generalizam a base de Fourier ( [6], [7]). Uma característica importante deste trabalho é a analogia direta entre os casos contínuo e discreto. / [en] In [23], some isoperimetric equalities and inequalities related to the Wigner Caustic (WC) and the Constant Width Measure Set (CWMS) are proved. In this work, we generalize these results to normed planes with quadratically convex unitary ball or polygonal unitary balls. The WC and CWMS are closely related to cycloids, which are curves whose support functions generalize the Fourier basis ( [6], [7]). An important aspect of our work is the direct analogy between the smooth and discrete cases.

The present study utilizes the ultrasonic travel time technique to diagnose grid generated turbulence. Ultrasonic flow metering technology relies on the measurement and computation of small perturbations in the travel time of acoustic ultrasonic waves through the dynamic medium. The statistics of the travel time variations of ultrasonic waves that are caused by turbulence probably affect the performance of ultrasonic flow meters. Motivation for the study stems from the large travel time variations observed in typical ultrasonic flow and circulation meters. Turbulent flow data was collected downstream of a grid introduced in a uniform flow in the wind tunnel using ultrasonic techniques. Grid turbulence is well defined in literature, and is nearly homogeneous and isotropic. The experimental investigation was performed under well-controlled laboratory conditions. The grid mesh sizes varied from 0.25-0.5in, and flow velocities from 0-20m/s. The ultrasonic transducers were of 100 kHz working frequency; and all of the data was collected with them oriented perpendicular to the mean flow. Path lengths were increased from 2-10in; and the data acquisition and control system featured a very high speed data acquisition card with an analog to digital converter that enabled excellent resolution of ultrasonic signals. Experimental data was validated by comparison to other studies. The work aims to investigate the influence of the grid-generated turbulent flow on acoustic wave propagation, in terms of the variance of the travel time. The effect of turbulence on acoustic wave propagation was observed. The experimental data was used to compute average travel times, acoustic travel time variances, and standard deviation amplitude fluctuations. The data was collected in the region estimated to be homogeneous and isotropic. Average travel time data support the assumption that only the large (as compared to the wavelength ) turbulent inhomogeneities influence acoustic wave propagation. Variance data confirm the presence of a non-linear trend in the acoustic travel times with increasing path length. Amplitude fluctuations data confirm a correlation between areas of caustic formation and large amplitude fluctuations.

Gravitational microlenses are stellar- or planetary-mass objects which cause a transient amplification when passing in the foreground of a distant source. We study microlenses that consist of three point masses. Such a model can represent a triple star, a binary star with a planet, a star with two planets, or a star + planet + moon system. Up to date, four planetary systems have been discovered in triple-lens microlensing events. We aim to expand the theory of triple lenses in order to simplify the interpretation of observed data and enable correct analysis in more complex cases. We focus mainly on the classification of triple-lens models with respect to their caustics. For a given source trajectory, the caustic determines prominent features on the light curve and thus its knowledge is essential for the analysis of microlensing events. We map the topology of the critical curve (the main caustic image) and the number of cusps of the caustic in the lens-model parameter space. We introduce methods for the classification of general $n$-point-mass microlenses. The methods are then demonstrated on four two- parameter and three three-parameter models. Furthermore, we study amplification maps for both point sources and extended sources, with an emphasis on new features appearing in triple and general $n$-point-mass...

Introdução: Narrow-Band Imaging (NBI) é uma das mais recentes técnicas de processamento de imagem, que consiste na utilização de filtros para dissociação das bandas do espectro da luz, resultando em aumento de contraste da superfície epitelial e da vascularização. Em combinação com a magnificação de imagem, pode-se diferenciar os tipos epiteliais e identificar áreas de padrão vascular decorrente de processos inflamatórios ou de neoplasias superficiais. A utilização da endoscopia associada à cromoscopia com solução de Lugol já é método consagrado na detecção de lesões superficiais em pacientes de alto risco, sendo largamente utilizado na prática diária. Objetivo: avaliar a aplicabilidade clínica da técnica de NBI na detecção e avaliação de neoplasias de esôfago em pacientes portadores de estenose do esôfago por agente corrosivo, comparando-a com a cromoscopia com solução de Lugol. Pacientes e Métodos: foram submetidos à avaliação com NBI 38 pacientes, sendo 22 e 16, com idade entre 28 84a (média M 56). O equipamento empregado é da linha de processadora Olympus, série EVIS II 180, Gastroscópio Olympus, série 180 GIF Type N180 slimsight ,com diâmetro 4.9mm, propiciando conforto ao paciente, sem a necessidade de dilatação da estenose. O exame iniciava-se com a remoção de resíduos e secreções do esôfago com irrigação vigorosa de soro fisiológico e N-acetil cisteína; após avaliação completa e constatando-se a ausência de lesões detectáveis sem auxílio de cromoscopia, era realizada a avaliação por meio por meio da técnica do NBI e cromoscopia com solução de Lugol, seguido de biópsia dirigida das eventuais lesões ou do anel estenótico. Resultados: lesões suspeitas pelo NBI totalizaram 9, e pelo teste de Lugol, (14), evidenciando uma sensibilidade e especificidade para o teste do NBI de 100% e 80.56% respectivamente; e a mesma relação de 100% e 66.67%, para o teste com a solução de Lugol 5 (13%) lesões suspeitas apresentaram-se positivas pelo NBI e pelo Lugol; destas, 2 (40%) foram confirmadas no anatomopatológico como carcinoma. Discussão: o NBI aumenta o contraste entre os vasos e a mucosa. Os vasos aparecem de cor marrom escura e a mucosa, azul claro. No exame normal os padrões vasculares e de mucosa são regulares e bem distribuídos. Se qualquer crescimento anormal ocorre (inflamatório, displásico ou neoplásico) a imagem muda, se torna mais escura (marrom), destacando-se da superfície azulada da mucosa. Com a ajuda da magnificação de imagem a identificação de possíveis lesões suspeitas se torna mais fácil. Esses achados determinam o local mais adequado para biópsia, aumentando as chances de diagnóstico de lesões displásicas e neoplásicas. Esse estudo revelou que a mucosa esofágica após lesão cáustica se torna esbranquiçada com pequenos pontilhados azulados, quando examinada com a técnica de NBI. Conclusão: o emprego da técnica de cromoscopia óptica (NBI) surge como opção na avaliação da estenose do esôfago por ingestão de agente corrosivo, para pesquisa de tumor. / Introduction: The Narrow Band Imaging system is a new method of endoscopic imaging. It´s based in the use of optical filters to dissociate bands of light spectrum, emphasizing certain live imaging features such as capillary and mucosal patterns. The upper GI endoscopy associated with Lugol´s solution chromoscopy is a well know method for detecting superficial lesions in high risk patients. Objetive: determinate the clinical applicability of the NBI technique for detection of esophagus cancer in patients with caustic lesion/corrosive agent stenosis and compare it to Lugol´s solution chromoscopy. Patients and Methods: 38 patients ( 22 female and 16 male ), aging between 28-84 (M 56) were enrolled to this study and examined by both NBI technique and Lugol´s solution chromoscopy. The instrument used in this study was a Olympus EVIS II-180, slimsight, with 4,9mm diameter, promoting the exam of the stenotic ring or segment without the need of dilation. The exam started with the removal of esophageal residues with N-Acetilcystein and physiologic solution. Followed the full routine exam of the esophagus. Next, the NBI was performed and any lesion detected was marked for later biopsy. After that, the Lugol´s solution crhomoscopy was performed and biopsies were taken if necessary. Patients who had normal findings at the routine, NBI or Lugol´s solution chromoscopy exam had their stenotic ring biopsed. Results: suspicious lesions with NBI were 9, and with the Lugol\'s chromoscopy 14. The sensibility and specificity of the NBI was 100% and 80.56%, and of the Lugol´s chromoscopy 100% and 66.67%, respectively. 5 (13%) suspicious lesions were detected both with NBI and Lugol\'s chropmoscopy, 2 (40%) of these lesions were confirmed carcinoma in the anatomopatholic exam. Discussion: the advantage of the NBI is enhance the contrast between vessels and the mucosa. The vessels appear as dark-brownish lines and the mucosa as light brownish color. In a normal exam, the vascular and mucosal patterns are regular and well distributed. If any abnormal growth takes place (inflammatory, displasic or neoplasic) the image changes into areas of darker brownish color and with the help of magnification, irregular or distorced vascular or mucosal pattern can be identified. These findings guide the exact site to be biopsed, increasing the chances of detecting possible displasic or neoplasic lesions. This study observed that the esophageal mucosa previously injured by corrosive agents had a whitish color, spoted by light blue areas, when examined with NBI technique. Conclusion: the NBI system is an option applicable to detect and evaluate cancer in patients with caustic lesion/corrosive stenosis compared to the Lugol´s solution chromoscopy.

Introdução: Narrow-Band Imaging (NBI) é uma das mais recentes técnicas de processamento de imagem, que consiste na utilização de filtros para dissociação das bandas do espectro da luz, resultando em aumento de contraste da superfície epitelial e da vascularização. Em combinação com a magnificação de imagem, pode-se diferenciar os tipos epiteliais e identificar áreas de padrão vascular decorrente de processos inflamatórios ou de neoplasias superficiais. A utilização da endoscopia associada à cromoscopia com solução de Lugol já é método consagrado na detecção de lesões superficiais em pacientes de alto risco, sendo largamente utilizado na prática diária. Objetivo: avaliar a aplicabilidade clínica da técnica de NBI na detecção e avaliação de neoplasias de esôfago em pacientes portadores de estenose do esôfago por agente corrosivo, comparando-a com a cromoscopia com solução de Lugol. Pacientes e Métodos: foram submetidos à avaliação com NBI 38 pacientes, sendo 22 e 16, com idade entre 28 84a (média M 56). O equipamento empregado é da linha de processadora Olympus, série EVIS II 180, Gastroscópio Olympus, série 180 GIF Type N180 slimsight ,com diâmetro 4.9mm, propiciando conforto ao paciente, sem a necessidade de dilatação da estenose. O exame iniciava-se com a remoção de resíduos e secreções do esôfago com irrigação vigorosa de soro fisiológico e N-acetil cisteína; após avaliação completa e constatando-se a ausência de lesões detectáveis sem auxílio de cromoscopia, era realizada a avaliação por meio por meio da técnica do NBI e cromoscopia com solução de Lugol, seguido de biópsia dirigida das eventuais lesões ou do anel estenótico. Resultados: lesões suspeitas pelo NBI totalizaram 9, e pelo teste de Lugol, (14), evidenciando uma sensibilidade e especificidade para o teste do NBI de 100% e 80.56% respectivamente; e a mesma relação de 100% e 66.67%, para o teste com a solução de Lugol 5 (13%) lesões suspeitas apresentaram-se positivas pelo NBI e pelo Lugol; destas, 2 (40%) foram confirmadas no anatomopatológico como carcinoma. Discussão: o NBI aumenta o contraste entre os vasos e a mucosa. Os vasos aparecem de cor marrom escura e a mucosa, azul claro. No exame normal os padrões vasculares e de mucosa são regulares e bem distribuídos. Se qualquer crescimento anormal ocorre (inflamatório, displásico ou neoplásico) a imagem muda, se torna mais escura (marrom), destacando-se da superfície azulada da mucosa. Com a ajuda da magnificação de imagem a identificação de possíveis lesões suspeitas se torna mais fácil. Esses achados determinam o local mais adequado para biópsia, aumentando as chances de diagnóstico de lesões displásicas e neoplásicas. Esse estudo revelou que a mucosa esofágica após lesão cáustica se torna esbranquiçada com pequenos pontilhados azulados, quando examinada com a técnica de NBI. Conclusão: o emprego da técnica de cromoscopia óptica (NBI) surge como opção na avaliação da estenose do esôfago por ingestão de agente corrosivo, para pesquisa de tumor. / Introduction: The Narrow Band Imaging system is a new method of endoscopic imaging. It´s based in the use of optical filters to dissociate bands of light spectrum, emphasizing certain live imaging features such as capillary and mucosal patterns. The upper GI endoscopy associated with Lugol´s solution chromoscopy is a well know method for detecting superficial lesions in high risk patients. Objetive: determinate the clinical applicability of the NBI technique for detection of esophagus cancer in patients with caustic lesion/corrosive agent stenosis and compare it to Lugol´s solution chromoscopy. Patients and Methods: 38 patients ( 22 female and 16 male ), aging between 28-84 (M 56) were enrolled to this study and examined by both NBI technique and Lugol´s solution chromoscopy. The instrument used in this study was a Olympus EVIS II-180, slimsight, with 4,9mm diameter, promoting the exam of the stenotic ring or segment without the need of dilation. The exam started with the removal of esophageal residues with N-Acetilcystein and physiologic solution. Followed the full routine exam of the esophagus. Next, the NBI was performed and any lesion detected was marked for later biopsy. After that, the Lugol´s solution crhomoscopy was performed and biopsies were taken if necessary. Patients who had normal findings at the routine, NBI or Lugol´s solution chromoscopy exam had their stenotic ring biopsed. Results: suspicious lesions with NBI were 9, and with the Lugol\'s chromoscopy 14. The sensibility and specificity of the NBI was 100% and 80.56%, and of the Lugol´s chromoscopy 100% and 66.67%, respectively. 5 (13%) suspicious lesions were detected both with NBI and Lugol\'s chropmoscopy, 2 (40%) of these lesions were confirmed carcinoma in the anatomopatholic exam. Discussion: the advantage of the NBI is enhance the contrast between vessels and the mucosa. The vessels appear as dark-brownish lines and the mucosa as light brownish color. In a normal exam, the vascular and mucosal patterns are regular and well distributed. If any abnormal growth takes place (inflammatory, displasic or neoplasic) the image changes into areas of darker brownish color and with the help of magnification, irregular or distorced vascular or mucosal pattern can be identified. These findings guide the exact site to be biopsed, increasing the chances of detecting possible displasic or neoplasic lesions. This study observed that the esophageal mucosa previously injured by corrosive agents had a whitish color, spoted by light blue areas, when examined with NBI technique. Conclusion: the NBI system is an option applicable to detect and evaluate cancer in patients with caustic lesion/corrosive stenosis compared to the Lugol´s solution chromoscopy.

‘Optical Caustics’ represent some of the most visually striking patterns of the light in nature.They occur when light rays from a source, such as the sun, get refracted, or reflected by curved media so as to bend and alter their path. They are ubiquitous and signify the regions of space in which many rays intersect to form bright singularities along a two-or a three-dimensional surface. The associated 2-D patterns (caustic patterns) could be simple or complex in ‘shape and size’ depending upon the optical arrangement used to produce them. Such patterns exhibit either a static or a dynamic behavior which can be controlled sensitively by the medium or the device used to produce them. The present thesis concerns with a few novel contributions in utilization of such optical caustics for the measurement of small angular rotation/tilt of objects. Utilizing a ‘hollow cylinder’ as a novel device for the generation of the optical caustics, the author proposed and demonstrated three new schemes of realizing a position-dependent-behavior of ‘Optical Caustic Patterns’. The said behavior is investigated both analytically as well as experimentally. The results of the investigation are then utilized to propose and demonstrate three methods of magnifying angular displacement of the hollow cylinder. The salient feature of the principle behind each of the said methods is illustrated in the figures below. The patterns in each of the above pictures correspond to two different positions of the hollow cylinder-the pattern in white color corresponds to the initial position while that in red color corresponds to new angular position of the cylinder. Defining S1 = ƒ (LΔΦ), S2= ƒ(TΔΦ) and S3= ƒ(ξ ΔΦ) as new signals from the proposed methods, it has been shown that each of them represent a magnified measure of the change in the angular position of the cylinder ΔΦ. Further, if a plane mirror is used in place of cylinder in the proposed methods, the corresponding signal S for the same change in the angular position ΔΦis represented by ΔD. For a chosen set of the experimental conditions, it is shown that for unit change in ΔΦ, the values of S1, S2 and S3 change 30, 37 and 62 times faster than ΔD. The investigations clearly demonstrate that hollow cylinders can be advantageously used as position-magnifying angle-sensing devices. The results of the investigations also suggest that in application areas such as auto collimation, torsion pendulum and design of motion control stages, this device is expected to bring in new advances.