Atmospheric Turbulence
Mostrando 1-12 de 39 artigos, teses e dissertações.
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1. MGF Methods for Fixed and Gain Saturated Optically Preamplified FSO Links Impaired by Misalignments and Atmospheric Turbulence
Abstract The Gaussian approximation is commonly used to evaluate the performance of free space optical communication systems. However, other performance evaluation methods such as the saddle point approximation, Chernoff bound and the modified Chernoff bound have also been used. This paper investigates the performance of fixed and gain saturated optically pr
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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2. Numerical and experimental evaluation of the thermally stratified atmospheric boundary layer in wind tunnels
Abstract The atmospheric boundary layer (ABL) flow occurs due to the interaction between the Earth’s surface and atmosphere, and it usually happens under thermal stratification. Therefore, in order to emulate this phenomenon, atmospheric wind tunnels need appropriate devices, such as spires and cubical roughness elements, at the entrance of the wind tunnel
REM, Int. Eng. J.. Publicado em: 2021-01
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3. Aerodynamic effects on a high slenderness concrete chimney
Resumo Este trabalho apresenta os resultados da determinação teórico-experimental do comportamento aerodinâmico de uma chaminé esbelta de concreto armado, com 150m de altura e esbeltez 30. Foram construídos dois modelos reduzidos: um rígido para medição das pressões e outro aeroelástico, reproduzindo as principais características dinâmicas da es
Rev. IBRACON Estrut. Mater.. Publicado em: 13/12/2019
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4. Wind Tunnel Investigation of the Wind Patterns in the Launching Pad Area of the Brazilian Alcântara Launch Center
ABSTRACT This paper presents a wind tunnel study of the flow patterns in the main Brazilian Space Port, the Alcântara Launch Center (ALC), located in the Northwest region, over an irregular coastal cliff of 40 m height. In the ALC region, constant winds of strong incidence are very common, which can change the characteristics of the atmospheric boundary lay
J. Aerosp. Technol. Manag.. Publicado em: 14/01/2019
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5. Comparison of In-Flight Measured and Computed Aeroelastic Damping: Modal Identification Procedures and Modeling Approaches
ABSTRACT The Operational Modal Analysis technique is a methodology very often applied for the identification of dynamic systems when the input signal is unknown. The applied methodology is based on a technique to estimate the Frequency Response Functions and extract the modal parameters using only the structural dynamic response data, without assuming the kn
J. Aerosp. Technol. Manag.. Publicado em: 2016-06
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6. Simulations of the Atmospheric Boundary Layer in a Wind Tunnel with Short Test Section
ABSTRACT: This article presents a study of three different passive devices (spires, screens, and a carpet) separately and in various combinations, to simulate the atmospheric boundary layer (ABL) in a wind tunnel with a short test chamber (465×465x1200mm). The influence of distances between these devices on the formation of the ABL is established, and optim
J. Aerosp. Technol. Manag.. Publicado em: 2013-09
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7. PARAMETRIZAÇÃO DO TRANSPORTE DE ENERGIA CINÉTICA TURBULENTA NA CAMADA LIMITE CONVECTIVA / PARAMETERIZATION FOR THE TURBULENT KINETIC ENERGY TRANSPORT IN THE CONVECTIVE BOUNDARY LAYER
Neste trabalho, uma parametrização para os termos de transporte da equação de balanço de energia cinética turbulenta (ECT), válida para uma camada limite convectiva (CLC), é apresentada. Esta é uma tarefa complicada de ser realizada a partir de dados experimentais, especialmente devido a dificuldade associada às medidas das flutuações de pressão
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 15/12/2011
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8. Análise numérica da influência de fatores atmosféricos na esteira aerodinâmica de turbinas eólicas
A evolução do uso da energia eólica nas últimas décadas está diretamente relacionada ao de-senvolvimento da tecnologia empregada na conversão e projeto das instalações. Neste contex-to o presente trabalho apresenta um estudo sobre a influência de fatores atmosféricos, tais como a turbulência e a presença de um perfil de velocidades referentes à
Publicado em: 2011
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9. Atmospheric flow measurements using the PIV and HWA techniques
Abstract: Alcântara Space Center (ASC) is the Brazilian gate to the space where rockets of different sizes are launched. At ASC there is a relative topographical variation, coastal cliff, which modifies the atmospheric boundary layer characteristics and can cause interference for operations of rockets. In the present work, a simplified model (mock-up) was s
J. Aerosp. Technol. Manag.. Publicado em: 2010-08
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10. Synchronization in intermittent turbulence and spatiotemporal chaos in the solar-terrestrial environment / Sincronização em turbulência intermitente e caos espaço-temporal no ambiente solar-terrestre
In this work we analyze synchronization due to multiscale interactions in observations of intermittent turbulence and numerical simulations of spatiotemporal intermittency in neutral fluids and space plasmas. This study is carried out in two parts. First, we apply two distinct nonlinear techniques, kurtosis and phase coherence index, to measure the degree of
Publicado em: 2010
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11. Synchronization in intermittent turbulence and spatiotemporal chaos in the solar-terrestrial environment / Sincronização em turbulência intermitente e caos espaço-temporal no ambiente solar-terrestre
In this work we analyze synchronization due to multiscale interactions in observations of intermittent turbulence and numerical simulations of spatiotemporal intermittency in neutral fluids and space plasmas. This study is carried out in two parts. First, we apply two distinct nonlinear techniques, kurtosis and phase coherence index, to measure the degree of
Publicado em: 2010
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12. Studies using wind tunnel to simulate the Atmospheric Boundary Layer at the Alcântara Space Center
Abstract: The Alcântara Space Center (ASC) region has a peculiar topography due to the existence of a Coastal cliff, which modifies the atmospheric boundary layer characteristic in a way that can affect rocket launching operations. Wind tunnel measurements can be an important tool for the understanding of turbulence and wind flow pattern characteristics in
J. Aerosp. Technol. Manag.. Publicado em: 2009-06