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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.
31

Projeto e construcao de uma estrutura aceleradora de eletrons de onda continua

TAKAHASHI, JIRO 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:42:40Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:48Z (GMT). No. of bitstreams: 1 05030.pdf: 6618082 bytes, checksum: b37bbbe1087da50e0aecf20762c5f711 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
32

Estudo do perfil vertical de aerossóis na troposfera utilizando a técnica de LIDAR

SOUZA, RENATA F. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:25:48Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:33Z (GMT). No. of bitstreams: 1 11315.pdf: 4284842 bytes, checksum: 94ad34802b7652ff6ef2b3584c12f794 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP / FAPESP:01/07304-8
33

Projeto e implementacao do sistema de controle do acelerador microtron / Project and implementation of the control system for the microtron accelerator

MALAFRONTE, ALEXANDRE A. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:55:12Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:01Z (GMT). No. of bitstreams: 0 / O acelerador de elétrons recirculado do tipo microtron, que está sendo construído no Instituto de Física da Universidade de São Paulo, possui algumas centenas de parâmetros a serem monitorados e controlados. Estes parâmetros pertencem a vários subsistemas, tais como: transporte; vácuo; RF; e diagnóstico. Para diminuir a carga cognitiva do operador e auxiliá-lo no controle da máquina, foi construído um sistema de controle computadorizado, capaz de permear os diversos subsistemas e que permite ao operador medir e alterar os parâmetros de interesse, além de alertá-lo quando algum destes parâmetros exceder um valor pré-determinado. Este sistema de controle foi construído usando-se a metodologia do modelo das três camadas lógicas, a saber: camada dos dispositivos de entrada e saída; camada dos servidores de dispositivos; e camada da interface com o usuário. Na camada dos dispositivos de entrada e saída foram utilizados vários equipamentos, comerciais ou construídos no Laboratório do Acelerador Linear (LAL), possuindo interfaces de comunicação diversas. Na camada dos servidores de dispositivos foram utilizados PCs industriais. A camada da interface com o usuário utiliza um PC convencional executando uma interface humano-computador construída com o auxílio do software LabWindows/CVI (National Instruments). O sistema de controle deve apresentar características associadas à flexibilidade, escalabilidade e custo, para que seja passível de utilização durante todo o tempo de vida útil do acelerador e suporte manutenção pela equipe do próprio LAL. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
34

Poluição ambiental dos campos eletromagnéticos de estações de rádio, televisão e estações de radiobase da telefonia celular em de Manaus, AM

Santarém, Emerson Wladi Porto 29 May 2012 (has links)
Made available in DSpace on 2015-04-11T13:54:08Z (GMT). No. of bitstreams: 1 emerson wlad.pdf: 1261480 bytes, checksum: 1136b68b57d0c3703e174c92f893dd9b (MD5) Previous issue date: 2012-05-29 / O presente trabalho fomenta uma reflexão sobre os graves efeitos causados pela poluição ambiental oriunda de fontes de radiações eletromagnéticas do sistema de comunicação via rádio, televisão e telefonia celular. A ausência de estudos conclusivos a respeito dos reais efeitos causados pela radiação eletromagnética aos seres vivos, aliada ao exponencial crescimento dos sistemas de comunicação via rádio, assegura a relevância do presente estudo, alem de revelar um assunto altamente instigante. Sendo assim, objetivou-se analisar os potenciais riscos à saúde pública decorrentes da exposição humana a campos eletromagnéticos das Estações de Rádio e Televisão e Estações de Radiobase ERB da telefonia celular na cidade de Manaus. Foram monitorados os níveis de radiação emitidos por 34 (trinta e quatro) Estações de Radiobase da telefonia celular, localizadas no perímetro urbano da Cidade de Manaus. Foram também evidenciados os níveis de radiação em locais de grande adensamento de estações de rádio e televisão. De acordo com os resultados obtidos, os níveis de radiação medidos estão todos abaixo dos valores máximos permitidos pela legislação que regula esta atividade. Porém, há risco potencial à saúde humana, causada pela radiação eletromagnética mesmo em intensidade inferior àquela permitida na legislação. Foi constatado ausência de exigibilidade legal pelos órgãos licenciadores quanto ao cumprimento dos níveis de radiação eletromagnética nos empreendimentos com expressiva ocupação humana. O estudo aponta ainda para a necessidade de se adotar o princípio da precaução para se normatizar os empreendimentos que utilizam radiação eletromagnética como meio de comunicação, uma vez que existem controvérsias quanto aos níveis de radiação seguros à população.
35

An integrated approach to the analysis of environmental factors that influence male reproductive health

Adams, Jessica Alice January 2016 (has links)
At least 30 million men are infertile around the world, identifying male factor infertility as a global health issue. In the past 70 years, evidence of a significant general decline in sperm quality has been reported, prompting concerns about the implications for reproductive health. Over the same period, there have been substantial changes in human lifestyles. New technologies, such as mobile phones and wi-fi, have been proposed to have a negative impact on a range of health outcomes, from an increased risk of cancer to a decrease in fertility. However, these links remain controversial. Over the last 30 years, the introduction of assisted reproductive technologies (ART) has offered infertile patients, particularly men with severe male factor infertility, a successful treatment option. However, miscarriage rates associated with fertility treatment can be as high as 30% and how this risk had changed over time was unclear. In addition, there are natural fluctuations in human health, including seasonal changes to birth rates. However, the clinical implications of these fluctuations need to be established. In this thesis, using an integrated approach that combined epidemiological research with laboratory investigations, I show that sperm quality is negatively affected by exposure to RF-EMR from mobile phones and wi-fi. I also identified a seasonal summer increase in sperm motility and morphology that followed patterns of seasonality in birth rates and in the success of assisted conception cycles. I showed that although the number of successful conceptions from ART has increased over time, there has been an equal increase in miscarriage rates. Male reproductive health continues to be under-researched when compared with the female, this inequality needs to be addressed in order to understand the causes of the decline in male fertility and the relationship this has with subsequent reproductive success.
36

Experimentální studium rozptylu světla na površích solárních článků / Experimental study of light scattering from solar cells surfaces

Nádaský, Pavel January 2012 (has links)
This thesis deals with experimental measurement of angular distribution of electromagnetic radiation scattered from solar cells surfaces. The measuring apparatus is the second genaration of a scattermeter. This apparatus has been put into operation within the framework of this thesis. Results of the thesis are materials for numerical simulations aforementioned scattering and quantitative evaluation of scattering of electromagnetic waves from given surfaces.
37

Optimalizace procedury měření optického záření rozptýleného pevnými tělesy prováděného scattermeterem / Optimizing measurement procedure of the optical radiation scattered by solid surface performed by the scattermeter

Klus, Jakub January 2013 (has links)
Tato práce se zabývá optimalizací procedury měření optického záření rozptýleného pevnými tělesy prováděného pomocí scatterometru. V práci je popsáno několik metod použitelných k nalezení souboru pozic nepřekrývajících se kruhových detektorů na povrchu polokoule (i koule). Výsledky práce jsou aplikovány na samotný meřicí přístroj a je ukázána shoda experimentálních výsledku získaných před i po optimalizaci. Výhodu nového uspořádání lze nalézt především v převedení dřívejšího způsobu měření na soubor nezávislých měření, což má význam pro matematické zpracování výsledků.
38

Elektromagnetické vlny v disperzních a refraktivních relativistických systémech / Electromagnetic Waves in Dispersiveand Refractive Relativistic Systems

Bezděková, Barbora January 2019 (has links)
Study of light rays (light world lines) plays a significant role in many of astro- physical applications. Light rays are mainly studied in terms of so-called grav- itational lensing. However, the majority of studies are mainly focused on light propagation in vacuum. If the refractive and dispersive medium characterised by refractive index n is considered, effects occurring due to the medium presence need to be taken into account, which significantly complicates the problem. In the present thesis, rays propagating through simple refractive and dispersive systems, such as plane differentially sheared medium, are studied. In order to simplify the problem, the Hamiltonian equations of motion are used. The ray trajectories in the vicinity of Kerr black hole as well as accessible regions for the rays are also studied. Radial variation of the medium velocity is considered. Due to the recent increase of publications focused on the gravitational lensing in plasma, a detailed review summarizing the results obtained recently is included. 1
39

Finite Element Modeling Of Electromagnetic Radiation/scattering Problems By Domain Decomposition

Ozgun, Ozlem 01 April 2007 (has links) (PDF)
The Finite Element Method (FEM) is a powerful numerical method to solve wave propagation problems for open-region electromagnetic radiation/scattering problems involving objects with arbitrary geometry and constitutive parameters. In high-frequency applications, the FEM requires an electrically large computational domain, implying a large number of unknowns, such that the numerical solution of the problem is not feasible even on state-of-the-art computers. An appealing way to solve a large FEM problem is to employ a Domain Decomposition Method (DDM) that allows the decomposition of a large problem into several coupled subproblems which can be solved independently, thus reducing considerably the memory storage requirements. In this thesis, two new domain decomposition algorithms (FB-DDM and ILF-DDM) are implemented for the finite element solution of electromagnetic radiation/scattering problems. For this purpose, a nodal FEM code (FEMS2D) employing triangular elements and a vector FEM code (FEMS3D) employing tetrahedral edge elements have been developed for 2D and 3D problems, respectively. The unbounded domain of the radiation/scattering problem, as well as the boundaries of the subdomains in the DDMs, are truncated by the Perfectly Matched Layer (PML) absorber. The PML is implemented using two new approaches: Locally-conformal PML and Multi-center PML. These approaches are based on a locally-defined complex coordinate transformation which makes possible to handle challenging PML geometries, especially with curvature discontinuities. In order to implement these PML methods, we also introduce the concept of complex space FEM using elements with complex nodal coordinates. The performances of the DDMs and the PML methods are investigated numerically in several applications.
40

Radiolokatoriaus antenų kryptinių diagramų matavimo sistemų tyrimas / RLS antennas radiation pattern measuring systems research

Ogintas, Andrius 29 June 2007 (has links)
Baigiamajame magistro darbe, analitinėje dalyje, pateikta žinomi radiolokatorių antenų elektromagnetinio spinduliavimo kryptinių diagramų matavimo būdai bei svarbiausios matavimo sistemos dalies – imtuvo projektavimo teorija. Eksperimentinėje magistro darbo dalyje panagrinėti būsimi kryptinių diagramų nustatymo būdai, vienas iš jų - panaudojant elektromagnetinių bangų išsibarstymą ore. Pagal žinomus duomenis apie šį efektą sudaryta nauja alternatyvi sistema, kuri leidžia pagreitinti, sumažinti laiko bei materialines sąnaudas atliekant periodinius kryptinių diagramų matavimus ir pateiktos bendros išvados ir rekomendacijos. Darbą sudaro 7 dalys: įvadas, pagrindinės radiolokacinių sistemų techninės charakteristikos, elektroninė matavimo technika, RLS kryptinių diagramų matavimo būdai, bendros išvados ir rekomendacijos, literatūros sąrašas, priedai. / Already known Antennas Radiation Pattern Measuring Systems and theoretical Knowledge, that will help design most important part (Receiver) of measuring system, are presented In my Analysis Part of Master Work. In Experimental part there are new, that still aren’t in practical measuring used, Antennas Radiation Pattern Measuring Systems investigated. One of them is using electromagnetic Wave Scattering from Particles in the Air. Regarding all available Data’s about that effect I made System that allows us to decrease Antenna’s radiation pattern measuring time and expenses. Also made and presented some Advantages, Recommendations and Conclusions. In Master Work is 7 Parts: Introduction, Basic Radiolocation Systems technical Characteristics, Measuring Technique, Radiolocation Systems Antennas radiation patterns Measuring Methods, Conclusions, References, Supplement.

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