Atmospheric Attenuation
Mostrando 1-12 de 13 artigos, teses e dissertações.
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1. Proposta metodológica para elaboração de mapas de ruído em ambiente SIG, segundo norma ISO 9613-2
Noise mapping is a new activity with growing awareness among public officials and communities. This work presents a methodological proposal for the generation of noise maps in a Geographic Information System (GIS), based on ISO 9613-2, which standards the calculus for noise attenuation during propagation outdoors. Besides the definitions of methodological pr
Publicado em: 2011
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2. Contribuições ao estudo comparativo dos efeitos de descargas atmosféricas em sistemas compostos por cabos aéreos e subterrâneos a seco e a óleo
By means of computing simulations, it is presented in this work a comparative study of the effects of electromagnetic transients proceeding from indirect and direct atmospheric discharges in mixed-transmission lines, which consist of aerial and underground parts with oil and dry type isolation. The developed and implemented model in the ATP computing environ
Publicado em: 2009
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3. AVALIAÇÃO EXPERIMENTAL DOS EFEITOS DE CINTILAÇÃO NO CANAL ÓPTICO NO ESPAÇO LIVRE EM 780 NM, 1550 NM E 9100 NM / EXPERIMENTAL EVALUATION OF SCINTILLATION EFFECTS IN FREE SPACE OPTICAL CHANNEL IN 780 NM, 1550 NM AND 9100 NM
Optical laser communication in free space is an area that has been attracting increasing interest in the last years, due to its possible capacity to resolve the problem of information diffusion, giving higher capacity access to users. Wireless optical systems offer speedy installation and initialization procedures and system flexibility, with the equivalent
Publicado em: 2008
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4. A methodology for noise prediction of turbofan engines.
A computional model is developed for prediction of noise emission from na existing or new turbofan engine. This model allows the simulation of noise generation from high bypass ratio turbofan engines, appropriate for use with computational programs for gas turbine performance developed at ITA. Analytical and empirical methods are used for spectrum shape, spe
Publicado em: 2006
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5. Análise da emissão de conversão ascendente de energia do sistema vítreo ZBLAN: Er3+ em baixa temperatura
The upconversion process in rare earth elements (Er, Nd, Pr, Tm and Yb) doped fluoride glasses has received great attention from several researches. The main interest is its use in several technological applications as optical amplifiers and lasers. The fluoride glass (ZBLAN) is an amorphous glass and a good rare earth host material with low multiphonon rela
Publicado em: 2006
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6. Propriedades espectrais das plantas no infravermelho termal (2,5 - 14 um): da química ao dossel. / Spectral properties of plants in the thermal infrared (2.5 - 14 um): from the chemistry to the canopy.
This work explores the thermal infrared spectral properties of plants to evaluate how such data might be used in laboratory, field, and remote sensing studies of ecosystems, and to analyze diverse chemical aspects of plant species. Attenuated total reflectance (ATR) spectra of plant leaves display absorption bands caused by the fundamental molecular vibratio
Publicado em: 2005
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7. DEVELOPMENT OF METHODOLOGY FOR CALIBRATING PIEZOELECTRIC TRANSDUCERS USED IN INTERNAL BALLISTICS FOR TRANSIENT PRESSURE MEASUREMENTS / DESENVOLVIMENTO DE METODOLOGIA DE CALIBRAÇÃO DE TRANSDUTOR PIEZELÉTRICO DE PRESSÃO UTILIZADO EM BALÍSTICA INTERNA
The current research, of armaments industry`s interest, more specifically in the quality control of ammunition lots, is related to the development of methodology for calibrating piezoelectric transducers for transient pressure measurements associated with events whose duration is of the order of milliseconds. As its main contribution, this work presents prop
Publicado em: 2004
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8. Avaliação das imagens do sensor ASTER para discriminação espectral de variações faciológicas no granito Serra Branca, estado de Goiás / Aster sensor images valuation to spectral discrimination of faciologics variations in the Serra Branca granite, Goias state
The objective of this work was to evaluate the potential of ASTER/Terra images, acquired in the visible and near-infrared (VNIR) regions and in the shortwave infrared (SWIR) interval, for the discrimination of faciological variations in the Serra Branca granite massif in the Tin Province of the Goiás. This province is composed of several granitoid bodies th
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 10/10/2003
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9. METROLOGICAL EVALUATION OF OPTICAL EMITTERS AND DETECTORS APPLIED TO THE CHARACTERIZATION OF ATMOSPHERIC PARTICULATES POLLUTANTS / AVALIAÇÃO METROLÓGICA DE EMISSORES E DETECTORES ÓPTICOS APLICADOS À CARACTERIZAÇÃO DE POLUENTES PARTICULADOS ATMOSFÉRICOS
The atmospheric pollution is a latent world-wide problem, and it is harmful to the health, visibility and climate. For these factors, several studies and researches have been developed to characterize the chemical composition of the pollutants, concentration, size of particles, etc, with the objective of constructing adjusted instruments for the control of t
Publicado em: 2003
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10. Aster sensor images valuation to spectral discrimination of faciologics variations in the Serra Branca granite, Goias state / Avaliação das imagens do sensor ASTER para discriminação espectral de variações faciológicas no granito Serra Branca, estado de Goiás
Este trabalho busca avaliar os aspectos relacionados à potencialidade das imagens do sensor Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)/Terra, obtidas na faixa do visível e infravermelho refletido, para discriminação espectral de variações faciológicas no maciço granítico Serra Branca, inserido na Província Estanífera de
Publicado em: 2003
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11. MODELAMENTO DE EFEITOS DE MULTIPERCURSO ATMOSFÉRICO EM ENLACES MICROONDAS EM VISIBILIDADE. / MODELING ATMOSPHERIC MULTIPATH FADING IN LINE-OF-SIGHT MICROWAVE LINKS
Os desvanecimentos por multipercurso atmosférico são a principal causa de degradação do desempenho de enlaces rádio digitais de alta capacidade, acentuando os efeitos do ruído térmico e da interferência intersimbólica na taxa de bits errados. A previsão da distribuição cumulativa de probabilidades destes desvanecimentos em função de parâmetros
Publicado em: 2003
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12. Avaliação da atenuação da vegetação da Mata Atlantica a radiação gama natural emitida pela superficie
Several natural alpha, beta and gamma radionuclides are known. Most of them occur in rock-forming minerals Potassium, uranium and thorium are the main natural gamma radiation producers. This radiation can be measured in the laboratory, field or from aircrafts. In this case, besides atmospheric attenuation, vegetation can absorb substantial amounts of radiati
Publicado em: 1997