EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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4 resultados
Resultados da Pesquisa
Item Desenvolvimento de um sensor capacitivo para monitoramento da umidade do minério de ferro em protótipo de vagão de trem em escala reduzida.(2020) Santos, Gabriel Almeida; Rêgo Segundo, Alan Kardek; Monteiro, Paulo Marcos de Barros; Mesquita, Andre Luiz Amarante; Rêgo Segundo, Alan Kardek; Monteiro, Paulo Marcos de Barros; Mesquita, Andre Luiz Amarante; Silva, Sávio Augusto Lopes da; Almeida, Silvia Grasiella MoreiraUmidades elevadas em minério de ferro podem causar instabilidade e até interrupção do carregamento em um navio, enquanto baixas umidades estão relacionadas à emissão de poeira durante transporte ferroviário. Este é um problema econômico e ambiental devido à perda de massa e emissão de particulados nas ferrovias. Neste trabalho, tem-se como objetivo desenvolver um sensor de umidade de minério de ferro, aplicado a um protótipo de vagão de trem em escala reduzida, para realizar a medição da umidade em tempo real e auxiliar o estudo de emissão de particulados. O sensor proposto utiliza um método capacitivo baseado na medição da constante dielétrica. A calibração do sensor foi realizada com amostras de minério de ferro com umidades entre 0% e 13%. Ensaios realizados em um túnel de vento, com simulação de 300 km de ferrovia, obtiveram um erro máximo de umidade de 0,18% e secagem de 1,13%.Item A novel two degrees of freedom system for measuring iron ore water content on a conveyor belt.(2021) Pinto, Érica Silva; Santos, Gabriel Almeida; Magalhães, Paulo Henrique Vieira; Rêgo Segundo, Alan KardekWater content or moisture of materials is a parameter widely used in the industry. In mining, it is an important variable to control in iron ore production. High moistures may cause instability of iron ore piles and may make transport by ship unfeasible. Therefore, this paper presents the development of a system for measuring iron ore moisture on a conveyor belt (laboratory-scale). The structure that supports the sensor has two degrees of freedom, which allow perpendicular and parallel movements. The parallel movement makes the relative velocity between the measurement cell and the ore almost zero. The vertical movement allows the sensor to be placed at different depths in the ore. These sets enable real-time and in situ measurements. The system uses the capacitive method to determine the dielectric constant of the iron ore located between the sensor electrodes and, consequently, the moisture. This system has a measuring range of 0 to 14% on a dry basis and presents an uncertainty up to 0.07 percentage points for a 2-standard-deviation confidence level. In the validation process, the absolute error was less than 0.34 percentage point in the mining interest range of 6 to 14%. The founded results achieve a significant advance in the development of real-time equipment for measuring ore moisture since there is no device capable of doing it with the necessary level of accuracy and precision. For mining, this kind of system represents a big step to take corrective and preventive decisions around iron ore moisture control.Item Capacitive impedance measurement : dual-frequency approach.(2019) Rêgo Segundo, Alan Kardek; Pinto, Érica Silva; Santos, Gabriel Almeida; Monteiro, Paulo Marcos de BarrosThe most widely used technique for measuring capacitive impedances (or complex electrical permittivity) is to apply a frequency signal to the sensor and measure the amplitude and phase of the output signal. The technique, although efficient, involves high-speed circuits for phase measurement, especially when the medium under test has high conductivity. This paper presents a sensor to measure complex electrical permittivity based on an alternative approach to amplitude and phase measurement: The application of two distinct frequencies using a current-to-voltage converter circuit based in a transimpedance amplifier, and an 8-bit microcontroller. Since there is no need for phase measurement and the applied frequency is lower compared to the standard method, the circuit presents less complexity and cost than the traditional technique. The main advance presented in this work is the use of mathematical modeling of the frequency response of the circuit to make it possible for measuring the dielectric constant using a lower frequency than the higher cut-off frequency of the system, even when the medium under test has high conductivity (tested up to 1220 µS/cm). The proposed system caused a maximum error of 0.6% for the measurement of electrical conductivity and 2% for the relative dielectric constant, considering measurement ranges from 0 to 1220 µS/cm and from 1 to 80, respectively.Item Capacitive impedance measurement : dual-frequency approach.(2019) Rêgo Segundo, Alan Kardek; Pinto, Érica Silva; Santos, Gabriel Almeida; Monteiro, Paulo Marcos de BarrosThe most widely used technique for measuring capacitive impedances (or complex electrical permittivity) is to apply a frequency signal to the sensor and measure the amplitude and phase of the output signal. The technique, although efficient, involves high-speed circuits for phase measurement, especially when the medium under test has high conductivity. This paper presents a sensor to measure complex electrical permittivity based on an alternative approach to amplitude and phase measurement: The application of two distinct frequencies using a current-to-voltage converter circuit based in a transimpedance amplifier, and an 8-bit microcontroller. Since there is no need for phase measurement and the applied frequency is lower compared to the standard method, the circuit presents less complexity and cost than the traditional technique. The main advance presented in this work is the use of mathematical modeling of the frequency response of the circuit to make it possible for measuring the dielectric constant using a lower frequency than the higher cut-off frequency of the system, even when the medium under test has high conductivity (tested up to 1220 μS/cm). The proposed system caused a maximum error of 0.6% for the measurement of electrical conductivity and 2% for the relative dielectric constant, considering measurement ranges from 0 to 1220 μS/cm and from 1 to 80, respectively.