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Mostrando 1-12 de 5596 artigos, teses e dissertações.
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1. Synthesis of TiO2/ZnO photoanodes on FTO conductive glass for photovoltaic applications
Abstract For oxide semiconductors for application in dye-sensitized solar cells (DSSCs), titanium dioxide conjugated with zinc oxide thin films was synthesized and characterized. The UV (ultraviolet) spectrum characterization showed a peak of absorbance at around 355 nm, with a band gap of 3.25 eV and reflectance around 85%. Such characteristics allowed the
Cerâmica. Publicado em: 2023
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2. Impact of fuel quantity on luminescence properties of Sr3Al2O6:Eu by combustion synthesis
Abstract The photoluminescent behavior of Eu-doped Sr3Al2O6 obtained by highly efficient solution combustion synthesis is reported. In order to understand the influence of the fuel on the synthesis, the stoichiometric quantity and an excess of fuel were evaluated. By adjusting the amount of fuel, different luminescence responses were obtained, allowing europ
Cerâmica. Publicado em: 2023
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3. A Compact Dual-Band Self-Diplexing MIMO Patch Antenna for ISM and X-Band Communications
Abstract A compact, dual-band, and self-diplexing MIMO patch antenna with a shared aperture is presented for Industrial scientific medical (ISM) band and X-band communications. The structure consists of two orthogonal feed lines and a rectangular slot in a square patch. The size of the FR4 substrate is 50 × 50 × 1.6 mm3. The designed structure operates at
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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4. Integrated Antennas on MnM Interposer for the 60 GHz Band
Abstract In this article, antennas for the 60 GHz ISM band designed to be integrated to a new high-frequency, low-cost interposer technology called Membrane-nanowire-Membrane (MnM) are discussed, manufactured, and measured. Also, an antenna characterization system under development at the Microelectronic Laboratory (LME-USP) is introduced, showing promising
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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5. Design and Implementation of Microwave Dual-Band Pass Interdigital Filter Using an Analytical Approach
Abstract In this paper, benefiting from frequency transformation between the normalized frequency domain of low-pass prototype frequencies and the real frequency domain of the filter, a purely analytical procedure for dual-band filter design is used. The coupling matrix of the filter is analytically extracted, without the need to perform numerical optimizati
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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6. Radiation Efficiency of an Electrically Small Dual-band UHF Microstrip Patch Antenna Using Wheeler Cap Method
Abstract Determining the radiation efficiency of an antenna is a difficult task that becomes challenging when it is about electrically small antennas. This work investigates the applicability of the Wheeler cap method to measure the radiation efficiency of a UHF dual-band compact microstrip patch antenna. An overview of Wheeler method is presented. An adapta
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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7. A High-Gain Hemispherical Dielectric Lens Antenna Operating Simultaneously in Narrowband or Wideband for X-band Applications
Abstract A hemispherical dielectric lens antenna is proposed to provide beam-steering for communication networks operating in X-band. Two different printed antennas are simultaneously used to guarantee high performance and diversity of applications, one a wideband linear polarized antenna, and the other a narrowband circular polarized antenna. To ensure this
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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8. A High-Selectivity Bandpass Filter Using Dual-Mode Coupling Resonator
Abstract In this work, a new model of high selectivity dual-mode bandpass filter is presented. The proposed filter consists of a set of coupled lines with a dual-mode adjustable response in its design process. An improvement in selectivity is presented by combining the dual-mode element with a classic band rejection structure, thus making it possible to intr
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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9. Comparison of the autonomic nervous system dysfunction between different chronic spine disorders: neck pain versus low back pain
SUMMARY OBJECTIVE: This study aims to compare heart rate variability (HRV) between patients with chronic neck pain and patients with chronic low back pain and to correlate the chronic pain variables with heart rate variability indices. METHODS: This is a cross-sectional study. We divided the sample into two groups: neck pain (n=30) and low back pain (n=30)
Revista da Associação Médica Brasileira. Publicado em: 2022
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10. Multiphysics Design of High-Power Microwave Vacuum Window
Abstract This paper presents the Multiphysics Analysis of a High-Power Microwave Window for a Ka-Band Klystron providing 16MW of peak power. After the optimization of the electromagnetic performances, we analyze the effect of RF heating effect and the stress of the pressure on the window. We also analyze the multipactor effect, that is a common cause of wind
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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11. Single Port Multimode Reconfigurable UWB-NB Antenna for Cognitive Radio Applications
Abstract In this paper, a compact, single port, multimode reconfigurable UWB-NB antenna with a novel feeding network is presented. The proposed antenna consists of a pentagonal-shaped monopole radiator, a beveled-shaped partial defected ground plane with a rectangular slot, and a reconfigurable bypass feeding network. The antenna realizes a wideband frequenc
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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12. Synthesis and characterization of α-SnWO4 powders obtained by microwave-assisted hydrothermal method
Abstract The structural, morphological, and optical properties of α-SnWO4 synthesized by microwave-assisted hydrothermal method at 150 °C for different times were investigated. XRD revealed the formation of the orthorhombic phase, without the presence of a secondary phase. The sample processed for 64 min showed a reduction in unit cell volume, suggesting a
Cerâmica. Publicado em: 2022