Angular Dependence
Mostrando 1-12 de 52 artigos, teses e dissertações.
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1. Piezoelectricity from Elastic and Dielectric Measurements on Unpoled Ferroelectrics
A method is described to assess the piezoelectric response of ferroelectric materials from the temperature dependence of the elastic moduli and dielectric constant of unpoled samples. The limits and advantages over the traditional methods on poled samples are discussed. A quantitative check is made by comparing the piezoelectric softening measured below the
Mat. Res.. Publicado em: 07/06/2018
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2. CARACTERIZAÇÃO DE DISPOSITIVOS ELETRÔNICOS PARA DOSIMETRIA EM TOMOGRAFIA COMPUTADORIZADA. / CHARACTERIZATION OF ELECTRONIC DEVICES FOR DOSIMETRY IN COMPUTED TOMOGRAPHY.
Computed tomography (CT) is an examination of high diagnostic capability that delivers high doses of radiation compared with other diagnostic radiological examinations. The current CT dosimetry is mainly made by using a 100 mm long ionization chamber. However, it was verified that this extension, which is intended to collect all scattered radiation of the si
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 12/03/2012
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3. Caracterização e aplicação de duas câmaras de extrapolação em feixes padronizados de radiação X / Characterization and application of two extrapolation chambers in standard X radiation beams
The extrapolation chambers are ionization chambers with variable volume, and they are mainly utilized as beta radiation detectors. In this work two extrapolation chambers were characterized, a commercial PTW extrapolation chamber and another extrapolation chamber developed at the Calibration Laboratory of IPEN, for application as reference systems in mammogr
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 31/03/2011
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4. Determinação e análise da influência angular e eletrônica nas constantes de acoplamento nJCH em 2-X-4-t-butilcicloexanonas e 2-X-4-t-butilcicloexanóis (X=H, Me, F, Cl, Br) / Determination of NMR nJCH spin-spin coupling constants and analysis of their angular and electronic dependence in 2-X-4-t-butylcycloexanonas and 2-X-4-t-butylcycloexanols (X=H, Me, F, Cl, Br)
A dissertação consiste de uma parte introdutória que versa sobre constantes de acoplamento JXH que seguem ou não uma relação de estrita dependência com o ângulo diedro, proposta por Karplus para JHH e por Aydin e Günther para JCH; apresentando como as interações hiperconjugativas afetam os valores das mesmas. Seguindo a estrutura da dissertação
Publicado em: 2011
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5. Comparison of computed amplitudes of magnetoresistance in spin-valve structures with wafer probe measurements
A code has been developed based on the semi-classical theory of giant magnetoresistance of Camley and Barnas [l]. It computes the sheet conductance and magnetoresistance of spin-valve structures. The input parameters are phenomenological transport parameters (mean-free paths and reflection/transmission coefficients at interfaces). These parameters are fairly
Publicado em: 2011
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6. Estudo da resposta de monitores de radioproteção em feixes padronizados de radiação X, gama e beta. / Study of radiation detectors response in standard X, gamma and beta radiation beams
Foram estudadas as respostas de 76 detectores Geiger-Müller, 4 detectores semicondutores e 34 câmaras de ionização. Muitos deles foram calibrados em feixes de radiação gama (37Cs e 60Co) e alguns foram testados em feixes de radiação beta (90Sr+90Y e 204Tl) e X (N-60, N-80, N-100, N-150). Para os três tipos de radiação, foram obtidos os fatores de
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 24/05/2010
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7. Influência da condutividade e permissividade do solo em função da frequência no cálculo da impedância longitudinal e admitância transversal de linhas aéreas de transmissão / Influence of earth´s conductivity and permittivity frequency dependence on longitudinal impedance and transversal admittance transmission line´s parameters calculation
This thesis aims to propose more accurate models for calculating the electrical parameters of overhead power transmission lines. The influence of earth s conductivity and permittivity frequency dependence is evaluated when calculating transversal and longitudinal transmission lines parameters in the frequency range 0 to 2 MHz. This frequency range covers the
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 22/04/2010
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8. Ultrafine grained structure development in steel with different initial structure by severe plastic deformation
The present work deals with grain refinement of medium carbon steel, having different initial microstructure, modified by either thermal and/or thermomechanical treatment (TM) prior severe plastic deformation. In case of TM treated steel, structure refinement was conducted in two steps. Preliminary structure refinement has been achieved due to multistep open
Matéria (Rio de Janeiro). Publicado em: 2010
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9. Espalhamento de Férmions sob Influencia da Violação de Lorentz no Setor Fotônico / Scattering of Fermions under Influence of Violation Lorentz Sector Photonic
The standard model extension is a theoretical framework which includes the possibility of Lorentz symmetry violation in the Standard Model of elementary interactions. In electrodynamics, this possibility is represented by the term, KμFμF, that violates Lorentz symmetry without jeopardizing CPT symmetry, and the term "μvAμ@A, which violate
Publicado em: 2010
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10. Estudo de Interações Hiperfinas em Óxidos RCoO3 (R= Gd e Tb) e Filmes Finos de HfO2 por Meio da Técnica de Espectrospia de Correlação Angular Gama- Gama Perturbada / Hyper¯ne Interaction Study in RCoO3 (R = Gd and Tb) and HfO2 thin ¯lm oxides by Perturbed Angular Correlation Technique
In the present work, the Perturbed Angular Gamma-Gamma Correlation technique (PAC) was used to measure the Electric Field Gradient (EFG) in two oxide systems: RCoO3 (R = Gd, Tb) perovskite oxide and HfO2 in order to study the behavior of the EFG as a function of temperature. Electric quadrupole hyper¯ne interaction measure- ments were carried out using 111I
Publicado em: 2009
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11. Ferromagnetic resonance study of the anisotropies uniaxial and unidirectional magnetic bilayer and tricamadas / Estudo por ressonância ferromagnética das anisotropias uniaxial e unidirecional em bicamadas e tricamadas magnéticas
The Ferromagnetic Resonance (FMR) technique at the X-band (~ 9.70 GHz) and Q-band (~ 34.0 GHz) was used to study the magnetic properties of NiO/Co, NiO/Py and Py/FeMn bilayers, and Co/NiO/Co trilayers with different thicknesses, deposited by dc magnetron sputtering technique in the presence of a 400 Oe magnetic field. The FMR experiments were all done at roo
Publicado em: 2009
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12. Abordagens analíticas para problemas de transporte de radiação com dependência espectral / Analytical approaches to problems of transport of radiation with spectral dependence
Neste trabalho são apresentadas soluções de caráter analítico, em forma fechada, para o problema de transporte para fótons, com dependência espectral, considerando o núcleo de Klein-Nishina para espalhamento Compton, o qual tem particular aplicação no cálculo de doses em tratamentos de radioterapia. Foram propostas duas abordagens: no caso 1, a va
Publicado em: 2009