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Investigação da formação da fase óxido e estudo da influência da microestrutura e morfologia nas propriedades eletrocrômicas de filmes finos de Nb2O5
(Universidade Federal de São Carlos, 2002-08-30) Rosário, Adriane Viana do; Souza, Ernesto Chaves Pereira de; https://lattes.cnpq.br/1505400360366643
Nb2O5 is known by your capacity of optical absorption variation, which it happens due to reduction and small ions intercalation, such as Li+, double process. In this work, Nb2O5 electrochromic films were produced by Pechini method and deposited by dip-coating. Firstly, the composition variables effect of the oxide precursor solution it was investigated by thermal analysis measure. TG and DSC techniques were used to monitoring the organic part degradation process until to the oxide formation. It was observed that both variables, citric acid concentration and niobium concentration, to exercise great influence in the polymeric precursor complex. The composition variables and the calcination temperature effects were studied by different techniques, such as: cyclic voltammetry in LiClO4/CH3CN solution, in situ UV-Vis spectrophotometry, MEV and XRD. This study was realized based to Factorial Design methodology, and us allowed to direction the following stages of work. It was observed that changes in the variables, leads to important changes in the morphological and structural properties and, consequently, in the Nb2O5 films electro-optical properties. The variable that showed largest effect was the citric acid/ethylene glycol molar ratio, which is responsible for the polymeric net formation. The film crystallinity influence was investigated in more details and one was observed the relationship between the crystalline structure and the Li+ intercalation/extraction process reversibility. A great decrease of electrochemical answer was observed in function of the cyclicality for films treated to 400 ºC and 450ºC. However, with the calcination temperature increases this effect practically does not occur. XRD studies showed that to 400ºC the material is amorphous, evolving to hexagonal phase (500ºC), and, to 600ºC the ortorrhombic phase prevails. The transmittance variation, as well as, the coloration efficiency increases with the temperature increase. Another important stage of this work was the study of addition of different dopants effect on film electrochromic properties. Nb2O5 was doped with TiO2, SnO2, ZrO2 and CeO2 in concentrations between 0.1 and 10 mol%. In all cases, it was observed an increase of electrochemical and optical properties. However, for higher dopant concentration, it should probably happen the segregation of a second phase, once the intercalation charges and coloration efficiency values decrease. ZrO2 showed be the best dopant in 2.0 mol% concentration.
Implementação dos serviços de comunicação e monitoração em um ambiente para desenvolvimento de sistemas distribuídos
(Universidade Federal de São Carlos, 2002-08-30) Góis, Lourival Aparecido de; Moron, Célio Estevan; https://lattes.cnpq.br/8635476812779360
The TEV (Teaching Environment for Virtuoso) environment is a set of teaching tools that support the phases of analysis, design, implementation, depuration and test of real-time applications which are executed using the Virtuoso (Virtual Single Processor Programming System) kernel. This environment allows the application designer to graphically define the application data structures through an editor, write the C language code of the tasks and functions of the application and, finally, generate the necessary files to compile the application. These facilities solve most of the problems while generating of real-time applications, however, they do not support distributed applications. This master research aims at modeling and implementing an API (Application Programming Interface), based on TCP/IP protocols, to be used together with the TEV environment in order to provide some functionality related to real-time application generation on a network structure as well as to deal with some problems related to transparency in the communication between the protocols and the application processes. Based on this API, a generator, called AGAD, was developed to be used in the implementation and monitoring of the tasks involved with the communication. This work presents the API modeling, its utilization on the creation of the AGAD and the integration of the with TEV.