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Estudo da transição de fase sólido-vapor e da eficiência de inibidores voláteis de corrosão quando incorporados em matrizes poliméricas
(Universidade Federal de São Carlos, 2005-08-05) Panza, Luciana Paula; Kuri, Sebastião Elias; https://lattes.cnpq.br/6842072916153866; https://lattes.cnpq.br/6443072583987507
In this work it is proposed a potential barrier model between solid and vapor phases. As a consequence of this model it is developed a method to measure vapor pressure as low as 10-5 Pa. A thermodynamic system consisting of a cubic cavity with a small hole is considered (Knudsen cell). The cavity contains a sample, which the partial vapor pressure is desired to evaluate. The pressure in the cavity is proportional to the rate of mass effusion throughout the hole. The equations describing the vapor pressure as a function or the evaporation rate and the rate of mass effusion is developed. These quantities can be easily evaluated experimentally with small errors. This technique is applied to measure the vapor pressure of DICHAN , a commercial volatile corrosion inhibitor (VCI). The model for the vapor pressure requires a model for the phase transition interface between the solid and vapor states. It is assumed a potential barrier separating the vapor from the solid state. Comparing the results obtained in this work, with the vapor pressure obtained by other authors it can be evaluated the potential barrier as a function of the temperature Although VCIs have vapor pressure extremely small, this faint vapor gas is expected to be sensibly related to the efficiency against corrosion. It was studied the inhibitor behavior of an VCI commercialized in Brazil, which vapor pressure and molecular weight are unknown. This inhibitor differs from DICHAN for being free from nitrite ion and its lower cost. So, this study has two main objectives: first, its scientific contribution, with the development of a new method to obtain the vapor pressure of volatile solids; second, the development of a new commercial VCI.
RHeSumaRST: um sumarizador automático de estruturas RST
(Universidade Federal de São Carlos, 2005-08-05) Seno, Eloize Rossi Marques; Rino, Lúcia Helena Machado; https://lattes.cnpq.br/0315640846525832
This work presents an automatic summarization model based on both the Rhetorical Structure Theory RST and the Veins Theory VT. RST allows inter-relating discourse units by means of rhetorical relations. These, in turn, mirror meaning relations between those units. Adding to RST, VT delimits the domain of referential accessibility of each discourse unit of an RST tree, resulting in its vein . A vein signals, thus, the limits of a discourse unit that may enclose its anaphora antecedents. The automatic summarization model also embeds Marcu s model of salience: once a discourse is structured as an RST tree, its units are classified according to their salience by considering the its deep in the tree. The model consists of a set of pruning heuristics that aim at identifying superfluous information in an RST tree of a text. In excluding them, the resulting summary RST tree and, thus, the text summary, should preserve the co-referential chains. In this way, the heuristics are driven by both, specific features of RST relations and constraints on the referential accessibility provided by VT. The main contributions of this work include the proposal of the AS model itself and the availability of a prototype for its automatic exploration.
Método para compressão de imagens digitais fundamentado em procedimentos de Huffman e Wavelets
(Universidade Federal de São Carlos, 2005-08-05) Betetto, Luciana Aparecida de Oliveira; Cruvinel, Paulo Estevão; https://lattes.cnpq.br/7924553462118511
The amount of transmitted, stored and accessed information by computers have been growing exponentially on the last decades. Two factors have contributed to this effect, one is the appearing of the multimedia systems with its variety of applications. The other is all that fact that nowadays computers not only operate texts and numbers but sounds, images, movies and virtual reality. Inside this scenario of new reality, we can also find, the development and the growth of the internet availability (World Wide Web), an interactive and multimedia system based on information, making this information available for a great quantity of users, with stressed interactivity. This work shows the development of a system for digital images Compression with base on Huffman and Wavelets procedures of data storage and transmission in environments using digital images processing. It was developed on the C++ language under Windows environment. For results validation there were used standard images patterns of digital image Processing, as the Lena and Girl image, both on 128x128, 256x256 and 512x512 pixels resolutions, as well as tomographics images of soil and wood sample from tomograph of the Brazilian Agricultural Research Corporation.