Navegando por Assunto "Transmission lines"

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Acesso aberto (Open Access)
Acoplamento de modos guiados em cabos de pares trançados utilizando antenas com simetria radial no cenário terabit DSL
(Universidade Federal do Pará, 2020-03-26) SOUSA, Brenda Penedo Tavares de; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
The development of data transmission standards and access technologies has always been linked to the need to supply high data rates. Thus, technologies already implemented, such as the DSL (Digital Subscriber Line) system that uses twisted pairs for transmission, have been adjusting to support this growing data demand. In DSL systems, the twisted pairs are used as a transmission line, using the transverse electromagnetic mode (TEM). However, the physical limitations of the twisted pair as a transmission line prevent the system from achieving higher rates, needed to support fifth generation (5G) applications. Recently, it was proposed to use other transmission modes in the twisted pair, the higher order guided modes, as an alternative for this structure to be able to support transmission rates of the order of Terabits per second, having been termed as the Terabit DSL technology (TDSL). However, one of the challenges for this implementation is the coupling of the guided modes in the twisted pair, since they are not widely explored in the context of the propagation of higher-order guided modes, as simpler waveguides, such as Sommerfeld and Goubau. In this scenario, this dissertation aims to evaluate the coupling of the radiated signal between an antenna with radial propagation and the twisted pair cable, analyzing the electromagnetic behavior of structures. Considering that the twisted pair cable does not have a closed analytical model for the behavior of higher order modes, which propagate along these structures, all the results were obtained from numerical simulations in the software HFSS (High Frequency Structure Simulator).These results are in terms of the scattering parameter of the antenna and the electromagnetic field in the cable, making it possible to evaluate the coupling efficiency, the signal guidance and to predict the transmission rate available to users. The results obtained showed that the coupling between the antenna and the unshielded twisted pair cable reached levels of up to 83.83 % at frequencies of 0.15 THz, demonstrating a high coupling efficiency when compared to simpler scenarios in the literature, reaching levels on average 67 %. It was found that the use of these cables for data transmission is effective, managing to deliver rates of up to 1.737 Tbps in cables of up to 10 meters, while the rate forecasts for the TDSL scenario that consider the 100 % coupling reach levels of 2.013 Tbps.
Acesso aberto (Open Access)
Eletrodeposição e caracterização de revestimento de cobre/nanotubos de carbono dopados com iodo em fios de alumínio liga 1350
(Universidade Federal do Pará, 2023-09-19) RODRIGUES, Fabrício Augusto dos Santos; LEITE, Marcos Allan Reis; http://lattes.cnpq.br/8252507933374637
Nanocomposites based on copper and carbon nanotubes (Cu/NTC) in metallic matrix have been providing improvements in the electrical and thermal properties of materials, presenting great potential for application in areas such as the electrical sector. Great challenges are encountered in the transmission and distribution of electrical energy, such as technical losses, mainly due to the Joule effect, resulting in low efficiency of conventional aluminum (Al) conductors. In this sense, new nanostructured conductors were developed based on functionalized copper/carbon nanotubes and doped with iodine (Cu/NTC-f), as a coating for Al 1350 aluminum wires, using the electrophoretic deposition process in copper sulfate solution, under electrical currents of 1.2 A, 1.5 A and 1.8 A, were investigated for their electrical and mechanical properties. Al@Cu/NTC-f conductors were characterized by scanning electron microscopy; X-ray diffraction; Raman spectroscopy; tensile test, in addition to electrical measurements, at room temperature and under heating, via Kelvin bridge. The results show an increase of approximately 18% of the IACS with good stability under heating compared to the commercial aluminum conductor Al 1350, due to the intrinsic properties of the NTCs, functionalization, good dispersion and the doping effect of iodine, confirmed by Raman spectroscopy with redshifts in the Gint and Gext subbands. The characteristic morphology of the thin films of Cu/NTC-f, presented pyramidal structures, agglomerates, copper structures involved the NTC, as well as NTC homogeneously electrodeposited in the aluminum substrate with good crystallinity, cultivated in the directions (311) and Cu (220), Cu (200), favoring the formation of thin films with good crystallinity. This method of electrodeposition of Cu/NTC-f on the surface of metallic wires shows promise for the production of nanostructured metallic conductors of high ampacity, thermal stability, low density and high performance, applied in electric power transmission lines.
Acesso aberto (Open Access)
Localização de falhas em linhas de transmissão utilizando decomposição harmônica e redes neurais artificiais
(Universidade Federal do Pará, 2006-07-05) GOMES, Cristiane Ruiz; VIEIRA JÚNIOR, Petrônio; http://lattes.cnpq.br/1958791286192330
This work proposes a new methodology for fails location in transmission lines. This methodology consists in using harmonic decomposition of the leakage current and in the application of an Artificial Neural Network (ANN), this is able to recognize patterns of normal and fails conditions of a transmission line. It was developed a Pi model capable to use real data of voltage and current of the three phases. In this model values of capacitance, inductance and resistance can be modified in agreement of weather conditions. Fails were generated in all the towers with different values of capacitance. The input/output data were used to train the neural network. The real voltage and current data acquisition were done by instruments installed in the two terminals of the Guamá-Utinga transmission line belonging to Centrais Elétricas do Norte - ELETRONORTE. The computation of the parameters was made by the well known matricial method and was improved by Finite Element Method. An ANN was developed with Matlab software. For training the ANN it was used the backpropagation resilient algorithm, which presented good performance, been fast and accurate. The ANN was trained by two different sets to analyze differences between outputs. In the two cases results were satisfactory.