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Browsing by Issue Date, starting with "2020-02-07"

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  • Analysis of nickel-copper metallic foam supercapacitor for electric vehicles with hybrid battery-supercapacitor energy storage system
    Publication . Malburg, Leonardo Corrêa; Pereira, Rita Marcos Fontes Murta; Silva, Maria Teresa Oliveira de Moura e
    For centuries, the indicators of CO2 had never been so higher than past half century indicators, accounting for an increase rate of 1,5 ppm/year. This is the direct reflect of global warming, a problem that has motivated researchers on developing adequate alternatives for a variety of human needs, which is the case of transitioning from fossil fuels to renewable electrical powering sources, such as Electric Vehicles trending. This dissertation concerns one of the most delicate aspect about electric vehicles (EVs) design, the Energy Storage System, which regarding autonomy, is the key to overcome the current transportation electric energy sources limitations. Among the numerous known devices, Batteries and Supercapacitors are the main technologies in which electric vehicles energy storage relies on. However, batteries because of their chemical nature can be environmentally harmful when considering disposal aspects, concern which has motivated the energetic development and improvement of greener technologies, such as supercapacitos. This dissertation presents a proposition for the development procedure of a positive electrode nickel-copper hybrid supercapacitor theoretical cell, which was simulated, and the resulting data analyzed and discussed. Therefore, the hybridization of both technologies was subjected to computational simulations in order to test the hypothesis that a direct parallel connection between both technologies could interact collaborating to extend battery’s lifespan, hence, reducing its environmental impact. The simulations have shown that such interaction results in reduced current demand, causing the state of charge wave period to increase, thus, extending the lifespan of batteries.
    2020-02-07Master thesis Open access Show more
  • Modelling and analysis of piezoelectric energy harvester
    Publication . Nbokassem, Mohammad Waleed; Pereira, Rita Marcos Fontes Murta
    Energy harvesting based on piezoelectric harvesters became a subject of interest in recent years, mainly due to its applications in low power devices such as wireless sensors. The harvested energy applied into piezoelectric sensors does not only depends on vibration input level but also depends on piezoelectric material properties. A description of working principle of vibration piezoelectric energy harvester is presented, starting with piezoelectric effect the discovery, type of the piezoelectric sensor and piezoelectric sensor materials. A mathematical model of piezoelectric film is addressed and implemented in simulation software in order to simulate the QP20W piezo film sensor considered in this study. The EFM32 Giant Gecko Starter Kit and Simplicity Studio® software, are used to validate the developed model and an analysis of macro-scale of piezoelectric energy harvester system is performed. A laboratorial implementation of a vibration on off switch based on piezoelectric sensor is accomplished in order to demonstrate a simple application of piezoelectric sensors.
    2020-02-07Master thesis Open access Show more