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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.
1

Estudo morfometrico da região orbitaria humana atraves da reconstrução tridimensional computadorizada de imagens tomograficas

Cardoso, Luiz Antonio Athayde 19 July 2018 (has links)
Orientadores: Cassio Menezes Raposo do Amaral, Roberto de Alencar Lotufo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-07-19T20:13:13Z (GMT). No. of bitstreams: 1 Cardoso_LuizAntonioAthayde_M.pdf: 3601281 bytes, checksum: 693ad10713ea494053115882c7853b4a (MD5) Previous issue date: 1995 / Resumo: Foi efetuado um estudo moriométrico empregando cinco cabeças de cadáveres humanos com região orbitária íntegra, obtidas no Departamento e Anatomia do Instituto de Biologia da Universidade Estadual de Campinas (UNICAMP) e que foram submetidos ao exame de tomografia computadorizada no Setor de Radiologia do Hospital das Clínicas. A partir dos cortes tomográficos distanciados "entre si de 1,5mm , realizou-se a reconstrução tridimensional de imagens utilizando o programa de computador 3DViewnix em equipamento de computação de médio porte, no Laboratório de Engenharia de Computação e Automação Industrial da Faculdade de Engenharia Elétrica. Selecionaram-se cinco tipos de medidas lineares e dois tipos de medidas volumétricas da região orbitária. As medidas obtidas da dissecção anatômica , foram confrontadas com as da análise computadorizada para estudo estatístico (dados pareados e regressão linear). A análise dos resultados mostrou não haver diferenças estatisticamente significantes entre todas as medidas, e haver correlação linear adequada. Neste estudo é apresentada uma metodologia para realização deste exame com os equipamentos disponíveis na UNICAMP / Abstract: A morphometric study was conducted in five humans cadaver heads with preserved orbital region , obtained from the Departament of Human Anatomy in I the Institute of Biology of the State University of Campinas (UNICAMP). The heads were scanned by a computer tomograph in the Radiology Departament of the Clinics Hospital. Three dimensional reconstructions were performed from tomographic slices separated by 1,5mm using the 3DViewnix program in a computer workstation, on the Laboratory of Computator Engineering and Industrial Automation of the Faculty of Electrical Engineery. It were selected five types of linear measurements as well as two types of volumetric ones from orbital region. The values obtained from anatomic dissection were matched against the measures from computer analysis for statistical evaluation ( paired observations, and linear regression). The results showed no statistically significant differences, and a sactisfactory linear correlation between the anatomical and computer measures. In this study was developed a protocol to obtain the examinations with the equipments available in UNICAMP / Mestrado / Cirurgia / Mestre em Cirurgia
2

Lower eyelid complications associated with transconjunctival versus subciliary approaches to orbital floor fractures

Sirintawat, Nattapong 30 August 2016 (has links) (PDF)
Subciliary and transconjunctival approaches are commonly used to enter the orbital floor. Although both surgical approaches have been used for decades, there is no consensus regarding the most appropriate incision to prevent postoperative lower eyelid complications. The aim of this study was to compare the frequencies of lower eyelid complications after subciliary versus transconjunctival approaches to orbital floor fractures. The investigator implemented a retrospective cohort study and enrolled a sample consisting of subjects who had orbital floor repair. The predictor variable was two different surgical methods, subciliary or transconjunctival approch. The primary outcome variable was postoperative lower eyelid complications (ectropion, entropion, and eyelid retraction). Other variables were demographic backgrounds, anatomical consideration, or time to surgery. The samples were composed of 346 patients (98 [28.3%] females; 225 [65%] underwent a subciliary approach) with a mean age of 42.7 ± 21.1 years. The subciliary approach was significantly linked to the higher rates of ectropion and the lower rates of entropion at 7 days and 6 months postoperatively. There was no statistically significant difference in the frequency of eyelid retraction between both groups. In the setting of orbital floor fractures, these results suggest that the use of the subciliary approach increases the frequency of ectropion, while the transconjunctival approach increases the frequency of entropion. Consequently, the selection should be based on an individual patient basis and surgeon’s preference.
3

Existência de soluções periódicas em alguns problemas não-lineares. / Existence of periodic solutions on some nonlinear problems.

Cruz, German Jesus Lozada 29 February 2000 (has links)
O propósito deste trabalho é estudar a existência de solução periódica para problemas de oscilação não linear de barras submetidas a forças periódicas. Estudaremos concretamente dois problemas, que serão interpretados como equações diferenciais abstratas de segunda ordem cuja classe foi considerada em Ceron e Lopes [1]. Para garantir a existência de solução periódica dos problemas considerados, mostraremos que a aplicação de Poincaré S é limitada dissipativa e alfa-contração. Isso garante a existência de um atrator invariante compacto e a existência de um ponto fixo de S, o que é equivalente a existência da solução periódica. / Our aim in this work is to study the existence of periodic solution to oscillation in nonlinear problems of beams submitted to periodic forcing. We will study concretely two problems, which can be interpreted as an abstract second order diferential equation studied by Ceron and Lopes [1]. Our intention is to prove the existence of periodic solution to these problems. To this end, we will show that the Poincaré map S is uniform ultimately bounded and alpha-contraction. Thus we have the existence of invariant compact attractor, therefore S have a fixed point, which is equivalent the existence of a periodic solution.
4

Existência de soluções periódicas em alguns problemas não-lineares. / Existence of periodic solutions on some nonlinear problems.

German Jesus Lozada Cruz 29 February 2000 (has links)
O propósito deste trabalho é estudar a existência de solução periódica para problemas de oscilação não linear de barras submetidas a forças periódicas. Estudaremos concretamente dois problemas, que serão interpretados como equações diferenciais abstratas de segunda ordem cuja classe foi considerada em Ceron e Lopes [1]. Para garantir a existência de solução periódica dos problemas considerados, mostraremos que a aplicação de Poincaré S é limitada dissipativa e alfa-contração. Isso garante a existência de um atrator invariante compacto e a existência de um ponto fixo de S, o que é equivalente a existência da solução periódica. / Our aim in this work is to study the existence of periodic solution to oscillation in nonlinear problems of beams submitted to periodic forcing. We will study concretely two problems, which can be interpreted as an abstract second order diferential equation studied by Ceron and Lopes [1]. Our intention is to prove the existence of periodic solution to these problems. To this end, we will show that the Poincaré map S is uniform ultimately bounded and alpha-contraction. Thus we have the existence of invariant compact attractor, therefore S have a fixed point, which is equivalent the existence of a periodic solution.
5

Lower eyelid complications associated with transconjunctival versus subciliary approaches to orbital floor fractures

Sirintawat, Nattapong 04 July 2016 (has links)
Subciliary and transconjunctival approaches are commonly used to enter the orbital floor. Although both surgical approaches have been used for decades, there is no consensus regarding the most appropriate incision to prevent postoperative lower eyelid complications. The aim of this study was to compare the frequencies of lower eyelid complications after subciliary versus transconjunctival approaches to orbital floor fractures. The investigator implemented a retrospective cohort study and enrolled a sample consisting of subjects who had orbital floor repair. The predictor variable was two different surgical methods, subciliary or transconjunctival approch. The primary outcome variable was postoperative lower eyelid complications (ectropion, entropion, and eyelid retraction). Other variables were demographic backgrounds, anatomical consideration, or time to surgery. The samples were composed of 346 patients (98 [28.3%] females; 225 [65%] underwent a subciliary approach) with a mean age of 42.7 ± 21.1 years. The subciliary approach was significantly linked to the higher rates of ectropion and the lower rates of entropion at 7 days and 6 months postoperatively. There was no statistically significant difference in the frequency of eyelid retraction between both groups. In the setting of orbital floor fractures, these results suggest that the use of the subciliary approach increases the frequency of ectropion, while the transconjunctival approach increases the frequency of entropion. Consequently, the selection should be based on an individual patient basis and surgeon’s preference.
6

Antenas de Rádio Frequência para o VORSat

Ferreira, Serafim Correia January 2012 (has links)
Tese de mestrado. Mestrado Integrado em Engenharia Eletrotécnica e de Computadores - Major Telecomunicações. Faculdade de Engenharia. Universidade do Porto. 2012
7

Sonographische und kernspintomographische Untersuchungen intraokulärer und orbitaler Erkrankungen bei Hund und Katze

Krosigk, Frauke von 05 June 2009 (has links) (PDF)
Das Ziel der vorliegenden Arbeit war es, den klinischen Nutzen der Sonographie und der Magnetresonanztomographie bei intraokulären und orbitalen Erkrankungen bei Hunden und Katzen einzuschätzen und die diagnostische Wertigkeit der bildgebenden Verfahren zu analysieren. Weiterhin wurden charakteristische Befunde einzelner intraokulärer und retrobulbärer Erkrankungen in den bildgebenden Verfahren dargestellt. Die nach der Bildgebung gestellte Diagnose konnte in 67,2% der Fälle durch eine zytologische Untersuchung bestätigt werden. In den restlichen 19,7% der Fälle fand die Diagnose durch die Bildgebung im Zusammenhang mit der Anamnese, Symptomatologie und Therapie statt.
8

[en] EFFICIENT USE OF THE GEOESTATIONARY SATELLITE ORBIT THROUGH THE OPTIMIZATION OF ORBITAL LOCATIONS / [pt] USO EFICIENTE DA ÓRBITA DE SATÉLITES GEOESTACIONÁRIOS ATRAVÉS DA OTIMIZAÇÃO DE POSIÇÕES ORBITAIS

ERICSON CARVALHO RIBEIRETE 17 January 2007 (has links)
[pt] Este trabalho está relacionado ao problema da utilização eficiente da órbita de satélite geoestacionários. Neste problema, os satélites devem ser alocados adequadamente na órbita, obedecendo a limites de interferência máxima, de modo a satisfazer os requisitos de desempenho dos sistemas. Algumas técnicas para a determinação das posições orbitais de satélites existentes e planejados são mencionadas. Um novo modelo matemático para a otimização das posições orbitais dos satélites, baseado na minimização de uma função objetivo associada à interferência total que afeta cada um dos sistemas, é proposto. Finalmente, alguns resultados obtidos através da aplicação deste modelo são analisados e comparados a outros resultados disponíveis. / [en] This work is related to the problem of efficiently using the geoestationary satellite orbit in an interference limited environment. Some techniques to determine the orbital positions of existing and planned satellites are mentioned. A new mathematical model for optimizing satellite orbital positions based on the minimization of an objective function associated to the total interference affecting each system is proposed. Finally, results obtained through the application of this model are analysed and compared to other available results.
9

Pologrupy operátorů a jejich orbity / Pologrupy operátorů a jejich orbity

Vršovský, Jan January 2013 (has links)
Title: Semigroups of operators and its orbits Author: Jan Vršovský Department: Institute of Mathematics of the Academy of Sciences of the Czech Republic Supervisor: prof. RNDr. Vladimír Müller, DrSc., Institute of Mathematics of the AS CR Abstract: The orbit of a bounded linear operator T on a Banach space is a se- quence T n x, n = 0, 1, 2, . . ., where x is a fixed vector. The orbits are closely connected to the dynamics of operator semigroups and to the invariant sub- spaces and subsets. The thesis studies the relation between the operator and its orbits. The subject of the first part is the relation between sequences T n x and T n , stability and orbits tending to infinity. The second part deals with dense orbits - hypercyclicity and related notions. In the third part, an ana- logue of reflexive algebras of operators, orbit reflexive operators are defined and studied. Apart from "normal" orbits of a single operator, the weak orbits and orbits of C0-semigroups are also touched. Keywords: operator, semigroup, orbit, hypercyclic, orbit reflexive
10

[en] PROPAGATION EFFECTS IN LOW EARTH ORBIT SATTELITE LINKS / [pt] MODELAMENTO DE EFEITOS DE PROPAGAÇÃO EM ENLACES SATÉLITE DE ÓRBITA BAIXA

MARTA PUDWELL CHAVES DE ALMEIDA 02 December 2003 (has links)
[pt] O efeito da atenuação por chuvas em enlaces satélites que operam em frequências acima de 10 GHz é decisivo no cálculo de desempenho do sistema. A evolução da tecnologia dos sistemas satélite e a necessidade de expansão dos serviços de comunicações móveis pessoais levaram ao uso de sistemas de comunicação com satélites de órbita baixa. Estes sistemas são particularmente interessantes para o oferecimento destes serviços por suas características de pequeno atraso de propagação e uso de potência de transmissão mais baixas que os sistemas geoestacionários. Satélites em órbita baixas (LEO) operam em altitudes de cerca de 1000km e possuem movimento em relação à estação terrena. Esta característica de mobilidade traz novas questões sobre o comportamento da atenuação por chuvas, em particular a necessidade de um modelo de previsão de atenuação para estes enlaces com ângulo de elevação variante no tempo. Neste trabalho um modelo para a previsão de atenuação em enlaces com ângulo de elevação fixo, mais preciso do que os existentes na literatura técnica, foi desenvolvido como primeiro passo para o tratamento do problema de enlaces com ângulo de elevação variável. A seguir foi feita uma simulação de medidas em enlaces LEO a partir do banco de dados de medidas de atenuação em enlaces fixos no Brasil, considerando um modelo de constelação de satélites. Foi implementado um método geral que utiliza o histograma dos ângulos de elevação do satélite como ponderação da distribuição cumulativa de atenuação em cada ângulo. O método foi testado contra os resultados obtidos com simulações para a constelação Globalstar sendo obtida muito boa concordância entre o modelo de predição desenvolvido e a simulação. / [en] Rain attenuation is the most important propagation effect to be taken into account in the performance calculation for satellite systems operation at frequencies above 10 GHz. The technological evolution of such systems and the need for personal communication systems with global coverage lead to the use of low earth orbit communication systems, that not only have shorter propagation delays but also allow the use of lower transmission power than the traditional geostationary systems. Low earth orbit (LEO) satellites have altitudes around 1.000 Km and are in motion relatively to the earth stations. This mobility requires a new approach to the problem of rain attenuation prediction, particularly the need for a prediction model that takes into account the elevation angle variability. In this work, an improved rain attenuation prediction method for the geostationary case has been developed as a starting point for the analysis of the nongeostationary case. Then, the rain attenuation in the a LEO system has been simulated using measured data from fixed system systems and the satellite constellation model. A general method for slant path rain attenuation prediction considering variable elevation angles is proposed. The method uses the histogram of the elevation angles to weight the distributions obtained for fixed elevation. The method has been tested with simulations performed for the Globalstar LEO system and a very good agreement was obtained.

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