Resonant Level
Mostrando 1-12 de 35 artigos, teses e dissertações.
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1. Variations of Compact Rectangular Microstrip Antennas Using Defected Ground Plane Structure
Abstract The defects in the form of slots have been employed in microstrip antenna either on the patch or the ground plane to yield frequency reduction. However, the reported work does not provide any comparative study that highlight upon the frequency and cross-polar level reduction achieved using these various shape slot/defects. This paper provides a thor
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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2. The Surface Treatment of Niobium Superconducting Reentrant Cavities by Means of High Temperature Nitrogen Plasma Based Ion Implantation
High Temperature Nitrogen Plasma Based Ion Implantation (HT-NPBII) has been used to treat the surface of niobium superconducting reentrant cavities, which are part of parametric transducers in a resonant-mass gravitational wave detector. The aim is to enhance the corresponding electrical quality factors (Q-factors) which are closely related with the increase
Mat. Res.. Publicado em: 13/12/2019
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3. Multi-walled carbon nanotube reinforced polymer as a bonded repair for Al 2024-T3 fatigue crack growth
ABSTRACT The influence on multi walled carbon nanotubes (MWCNT, or simply CNT) as a reinforcement material in an epoxy resin in order to decrease the fatigue crack propagation rate in the 2024 T3 aeronautical Al alloy was studied. CT samples were pre-cracked in a resonant fatigue machine until a 4 mm pre-crack length. Four groups of samples were considered:
Matéria (Rio J.). Publicado em: 06/12/2018
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4. Wave propagation in cellular locally resonant metamaterials
Abstract Locally resonant acoustic metamaterials have recently attracted a great interest due to their dynamic behaviour, characterized by a band gap at relatively low frequencies. This paper provides a numerical study, by means of finite element modal analyses, of the dynamic properties of 1D mass-in-mass and 2D cellular locally resonant metamaterials. The
Lat. Am. j. solids struct.. Publicado em: 04/06/2018
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5. Multiband FSS with Fractal Characteristic Based on Jerusalem Cross Geometry
Abstract This paper proposes a new Frequency Selective Surface (FSS) with modifications on the Jerusalem Cross (JC) geometry to provide a multiband response. Fractal levels are created by introducing concentric self-similar JC copies in the original unit cell. This modification results in new dipoles at the structure which allows for the appearance of new ba
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2017-12
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6. Single-line-to-earth fault limitation through the setting of Petersen coil in power transformer neutral / Limitação de correntes de falta fase-terra por meio do ajuste de bobina de petersen em neutro de transformadores de potência
The Petersen coil insertion on the neutral of the electrical distribution power system transformers has been a technical strategy adopted for several electrical utilities, in many countries with the purpose to reduce the earth-fault current intensities, enabling circuit disconnect decrease for intermittent faults and so to improve the electrical power qualit
Publicado em: 2009
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7. Processos litográficos em filmes epitaxiais de compostos IV-VI para medidas Hall e o estudo da dopagem do telureto de chumbo com flureto de bário / Lithographic processes in epitaxial films of IV-VI compounds for Hall measurements and the study of lead telluride doping with barium flouride
The first part of the work dealt with the application of lithographical techniques to fabricate Hall geometry of IV-VI films grown on (111) BaF_2 substrates. A previous study of In diffusion in PbTe films confirmed the viability of using In as a metallic contact. During the lithographic process, some solutions were implemented to resolve the problems generat
Publicado em: 2009
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8. Ruído ambiental e seus efeitos: o ruído aeronáutico no entorno do Aeroporto Internacional de Brasília
The noise is the more evident environmental impact generated by the aviation in the neighborhood of the airports, could cause considerable damages to the life quality and the health of the affected population. This work had as main objective to evaluate the indisposition provoked by the aeronautical noise in close resident communities to the International Ai
Publicado em: 2008
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9. INVERSORES ZCZVT COM ACOPLAMENTO MAGNÉTICO: SÍNTESE E ANÁLISE.
This Ph. D. Thesis presents a in deep study of the mechanism of resonant transition soft-switching techniques. By means of the principles that rules the PWM resonant transition converters, a novel tool for analysis and synthesis have been developed. This novel tool also permit to be verified some of the main factors that made possible to he ZVT technique to
Publicado em: 2008
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10. Efeitos coerentes no acoplamento dos lasers de fentosegundo e de diodo em vapor de rubÃdio
Mode-locked, phase-stabilized femtosecond (fs) lasers with high-repetition rate produce a frequency standard composed by a great number of narrow modes, known as frequency comb. The interaction of inhomogeneously broadened two-level systems with a train of fs pulses, for the case in which the atomic relaxation times are longer than the laser repetition perio
Publicado em: 2008
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11. Modeling and optimization of piezoelectric shunts apply to passive vibration control / Modelagem numérica e otimização de shunts piezelétricos aplicados ao controle passivo de vibrações
Due to the development of new technologies, industrial structures are now made of lighter materials and work at higher operation speeds producing an increasing vibration and noise level generation. As a result, different techniques of active and passive control have been developed and are continuously being improved. Among the passive control techniques, the
Publicado em: 2007
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12. Environmental factors influence evaluation on the structure, dynamics and optical properties of the aquatic humic substances form the "Rio Negro" - Amazonas / Avaliação da influência de fatores ambientais na estrutura, dinâmica e propriedades ópticas das substâncias húmicas aquáticas do Rio Negro
Nowadays, one of the major world concerning is focused in the increasing of the damaging ultraviolet (UV) radiation and its impact on the aquatic ecosystems. In addition, the Rio Negro, one of the principal tributaries of the Amazon Basin, is an appropriate site for studying the influence of the UV radiation in the dissolved organic matter (DOM) biogeochemis
Publicado em: 2007