Mestrado em Engenharia Mecânica (EMC)
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Navegando Mestrado em Engenharia Mecânica (EMC) por Por Orientador "Fagundes Neto, Marlipe Garcia"
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Item Estudo experimental do leiaute de disposição dos materiais de absorção sonora em uma sala de aula(Universidade Federal de Goiás, 2023-02-16) Assis, Leandro Neves de; Fagundes Neto, Marlipe Garcia; http://lattes.cnpq.br/6303674803792521; Fagundes Neto, Marlipe Garcia; Nunes, Maria Alzira de Araújo; Badan, Marco Aurélio Brazão CostaClassrooms have the function of promoting learning through oral communication and listening. Thus, one of the main characteristics that determine the success of this function is the acoustic quality of classrooms. Speech intelligibility is one of the most relevant parameters and can be improved by minimizing external noise and reducing reverberation. One tactic to decrease the reverberation of a room is to dampen sound energy by using absorbent materials such as: padded chairs, curtains, carpets, and sound absorbing panels (SAP). However, the influence of the positioning of the elements, especially the SAP, is little studied. For the experiments of the positions with the SAP, Room 108 was used, which is located in the Mechanical Engineering building, campus II of UFG and, based on ISO 3382-2, 2 distinct points were selected for the sound source and 6 distinct points for the receptor. The data obtained was analyzed by the analysis of variance technique, aiming at identifying the most significant factors for the acoustic performance of the environment, since the following work has the general objective of investigating the arrangement of sound absorption materials in classrooms, through the acoustic parameters obtained, such as Reverberation Time, Brightness, Bass Ratio, Clarity and Definition. The results showed that the higher frequencies provided better responses in all parameters. Furthermore, in general, it was observed that the configuration with slabs placed closer to the frame and further back in the room stood out as having the best acoustic performance for the room studied. On the other hand, the configuration with slabs only closer to the board showed the worst responses, thus being characterized as the worst layout for the same room.Item Utilização de inteligência artificial para análise modal de uma viga engastada sob escoamento em túnel de vento(Universidade Federal de Goiás, 2023-02-04) Rodrigues, Pedro Augusto Dias; Kitatani Junior, Sigeo; http://lattes.cnpq.br/9419723461067210; Fagundes Neto, Marlipe Garcia; http://lattes.cnpq.br/6303674803792521; Fagundes Neto, Marlipe Garcia; Pena, José Luiz Oliveira; Colherinhas, Gino Bertollucci; Kitatani Júnior, SigeoWind turbines suffer severe damage due to excessive wind loads or inadequate maintenance conditions, and catastrophic failures often occur causing huge losses. A structure, such as a wind turbine, can be monitored and evaluated through its modal characteristics, where natural frequencies, for example, are characteristics that are independent of operating conditions. They change only in case of damage, i.e. when stiffness and mass change. However, for the application of modal analysis, several sensors distributed in the structure are required, which involves high instrumentation costs. In view of this, it is proposed the use of modal analysis techniques integrated with virtual sensors, which, unlike real/physical sensors, are obtained through models. In this work, the virtual sensors are determined by using an artificial intelligence of the neural network type, which together with the modal analysis allows to obtain the modal characteristics: natural frequencies, modal shapes and damping. For this purpose, it is proposed to study a fixed Euler Bernoulli beam, an approximation model of a wind turbine, where the flow loads are generated through a wind tunnel with a speed controller. The flow velocities analyzed over the beam ranged from 10 to 20 m/s. The virtual sensor for operational modal analysis was modeled using a dynamic neural network where configurations of delay number and number of neurons in the hidden layer were investigated. In sequence, the modal characteristics of the Euler Bernoulli beam are compared using experimental modal analysis, situation in which the input is known and measured, and operational modal analysis, configuration where the input is unknown and not measured. For comparative analysis, the natural frequencies obtained in the different configurations and modal techniques showed good results when compared with the values of the Euler Bernoulli beam. For the modes, the Modal Assurance Criterion (MAC) was used, where when analyzing each independent result, the MAC returns excellent modal results, but when performing a comparative analysis of the different configurations and techniques, the MAC showed low correlation. Finally, the damping ratio showed an increase for higher flow velocities, but further investigations should be carried out in future works using other operational modal analysis techniques.