Satellites
Mostrando 1-12 de 322 artigos, teses e dissertações.
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1. Assessment of Total Attenuation and Adaptive Scheme for Quality of Service Enhancement in Tropical Weather for Satellite Networks and 5G Applications in Nigeria
Abstract The dynamic weather condition is a major concern for optimum channel utilization in recent times, especially at higher frequencies with larger bandwidth for 5G applications. Over the years, rain-induced attenuation among the hydrometeors has been linked as the major cause of signal impairment especially at the frequency, f ≥ 10 GHz. However, when
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2021-06
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2. ERROR BEHAVIOR OF ATOMIC CLOCKS ABOARD GPS SATELLITES
Abstract: The signal transmission and position quality obtained by GNSS positioning directly depends on the time control. The atomic clocks aboard the satellites are responsible for this control. In this research, the satellites clock errors of GPS are studied, using data from the pseudorange, the satellite semi-major axis and the correction parameters of th
Bol. Ciênc. Geod.. Publicado em: 02/12/2019
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3. Single-Bus and Dual-Bus Architectures of Electrical Power Systems for Small Spacecraft
ABSTRACT Nowadays, it has become possible for universities and new businesses to launch satellites of reduced size and cost fulfilling viable missions. Nevertheless, there is still a considerable failure rate that reduces the expected lifetime of these spacecraft. One of the main causes of failure is the power system. Redundancy is one of the main options to
J. Aerosp. Technol. Manag.. Publicado em: 10/10/2019
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4. SPATIO-TEMPORAL MAPPING OF THE INVASIVE ALIEN SPECIES Pinus SP IN THE NORTHERN AREA OF THE LAGOA DO PEIXE NATIONAL PARK-RS
RESUMO Problema de dimensões globais, a ocupação de áreas por espécies exóticas invasoras é estudada neste trabalho com foco na presença crescente de Pinus sp no Parque Nacional da Lagoa do Peixe/RS. A partir de imagens de satélite e uso de técnicas de sensoriamento remoto e geoprocessamento, o artigo apresenta um mapeamento espaço-temporal da pre
Rev. Árvore. Publicado em: 23/09/2019
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5. REAL TIME PPP APPLIED TO AIRPLANE FLIGTHT TESTS
Abstract The availability in real time of GNSS satellites orbits, clock corrections and code and phase biases provided the possibility of application of Real Time Precise Point Positioning (RTPPP). This paper presents the methodology concerning RTPPP and application to kinematic trajectories of airplane flight tests, but without using the carrier phase bias.
Bol. Ciênc. Geod.. Publicado em: 10/07/2019
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6. Applying the NDVI from satellite images in delimiting management zones for annual crops
ABSTRACT: The utilization of Normalized Difference Vegetation Index (NDVI) data obtained through satellite images can technically improve the process of delimiting management zones (MZ) for annual crops, resulting in socio-economic and environmental benefits. The aim of this study was to compare delimited MZ, using crop productivity data, with delimited MZ u
Sci. agric. (Piracicaba, Braz.). Publicado em: 01/07/2019
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7. Performance of the SSEBop model in the estimation of the actual evapotranspiration of soybean and bean crops
Resumo: O objetivo deste trabalho foi avaliar o desempenho do modelo “operational simplified surface energy balance” (SSEBop) na estimativa da evapotranspiração real (ETa) das culturas de soja e feijão irrigadas por pivô central. As estimativas do modelo foram obtidas de imagens digitais dos satélites Landsat 7 e Landsat 8 e comparadas à ETa obtida
Pesq. agropec. bras.. Publicado em: 27/06/2019
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8. Advances and limitations of using satellites to monitor cyanobacterial harmful algal blooms
Resumo O uso de satélites para o monitoramento de florestas é uma prática conhecida e comum. Entretanto o monitoramento remoto da qualidade da água ainda é escarça. Nos Estados Unidos da América (EUA), o uso deste tipo de dado está começando a ser utilizado para o monitoramento da floração de cianobactérias tóxicas (FCTs). Essa ferramenta podero
Acta Limnol. Bras.. Publicado em: 03/06/2019
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9. Optimizing the Communication Capacity of a Ground Station Network
ABSTRACT: Small satellites are growing in use for educational, scientific, and commercial purposes, usually in Low Earth Orbit (LEO) flights, given their lower costs and associated risks, as well as smaller lead times for assembling and testing. However, the typically short periods of LEO passes bring the need to find ways of optimizing the communication bet
J. Aerosp. Technol. Manag.. Publicado em: 09/05/2019
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10. Influence of Urbanization on the Dynamics of the Urban Vegetation Coverage Index (VCI) in Erechim (RS)
ABSTRACT Vegetation fragments located in urban perimeters provide better environmental conditions for biological diversity and human well-being. The aim of this study was to evaluate the Vegetation Coverage Index (VCI) of the urban perimeter of Erechim, RS, between years 2010 and 2015. Mapping was carried out using World View 2 and Pleiades satellites image
Floresta Ambient.. Publicado em: 04/04/2019
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11. Satellite Inertia Parameters Estimation Based on Extended Kalman Filter
ABSTRACT: The moment of inertia parameters play a critical role in assuring the spacecraft mission throughout its lifetime. However, determination of the moment of inertia is a key challenge in operating satellites. During satellite mission, those parameters can change in orbit for many reasons such as sloshing, fuel consumption, etc. Therefore, the inertia
J. Aerosp. Technol. Manag.. Publicado em: 28/03/2019
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12. Design of Attitude Control Servomechanisms with Fluid Ring and CMG for Rigid Satellite
ABSTRACT: Satellites cover a wide range of space missions as remote sensing. Accomplishment of the mission depends on satellite's stability maintenance and direction. The main task of the attitude control system is to provide stability to the satellite against external disturbances. Such perturbations are caused due to aerodynamic drag, solar radiation and m
J. Aerosp. Technol. Manag.. Publicado em: 08/11/2018