Navegando por Data de Publicação, começando com "2013-07-11"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 3 de 3

Comportamento estrutural de vigas mistas de aço e concreto com protensão externa
(Universidade Federal de São Carlos, 2013-07-11) Nelsen, Anna Carolina Haiduk; Souza, Alex Sander Clemente de; https://lattes.cnpq.br/3572504605209699; https://lattes.cnpq.br/5833175927377476
This report investigates the structural behavior, procedures for analysis and design of externally prestressed steel-concrete composite beams. Based upon the requirements outlined in ABNT NRB 8800:2008 for conventional composite beams and in the literature review, a systematic procedure was developed to design of externally prestressed steel-concrete composite beams requested the positive bending moment. Was analyzed the main modes of global collapse, especially the ultimate limit state design (ELU), which may occur in this type of structure. Also, elaborated a parametric study aimed to analyze the influence of variation in the level of prestressing and the eccentricity of tendons, as well as the constructive methodology (pretensioning and posttensioning) adopted for the the prestressing steel profile that makes up the of steel-concrete composite beam. The parametric study showed that in both methods the predominant failure mode occurs in 2nd Stage of construction. In models of composite beams analyzed with application of pretensioned when the tendon is positioned above the bottom flange of the profile steel the failure mode occurred for the combined bending and axial compression .As for the composite beams evaluated with posttensioned, independent of the position of the tendon, the failure mode occurred in function of the bending moment more than the allowable flexural strength. However, it is noted that the level of prestressing can be adequately calculated to ensure that there is no loss of carrying capacity of the structure. It was also observed that regardless of the constructive methodology adopted, higher eccentricities result in higher bearing capacity for the steel beam, as exposed in the literature review. While in Brazil is largely unexplored, there was widespread interest in the international literature on the subject in question and their variances, giving rise to theoretical and experimental. Also been mentioned as potential applications in the design of new structures and the renovation and rehabilitation of existing structures.
Extração automática de relações semânticas a partir de textos escritos em português do Brasil
(Universidade Federal de São Carlos, 2013-07-11) Taba, Leonardo Sameshima; Caseli, Helena de Medeiros; https://lattes.cnpq.br/6608582057810385; https://lattes.cnpq.br/2945193976624030
Information extraction (IE) is one of the many applications in Natural Language Processing (NLP); it focuses on processing texts in order to retrieve specific information about a certain entity or concept. One of its subtasks is the automatic extraction of semantic relations between terms, which is very useful in the construction and improvement of linguistic resources such as ontologies and lexical bases. Moreover, there s a rising demand for semantic knowledge, as many computational NLP systems need that information in their processing. Applications such as information retrieval from web documents and automatic translation to other languages could benefit from that kind of knowledge. However, there aren t sufficient human resources to produce that knowledge at the same rate of its demand. Aiming to solve that semantic data scarcity problem, this work investigates how binary semantic relations can be automatically extracted from Brazilian Portuguese texts. These relations are based on Minsky s (1986) theory and are used to represent common sense knowledge in the Open Mind Common Sense no Brasil (OMCS-Br) project developed at LIA (Laboratório de Interação Avanc¸ada), partner of LaLiC (Laborat´orio de Lingu´ıstica Computacional), where this research was conducted, both in Universidade Federal de São Carlos (UFSCar). The first strategies for this task were based on searching textual patterns in texts, where a certain textual expression indicates that there is a specific relation between two terms in a sentence. This approach has high precision but low recall, which led to the research of methods that use machine learning as their main model, encompassing techniques such as probabilistic and statistical classifiers and also kernel methods, which currently figure among the state of the art. Therefore, this work investigates, implements and evaluates some of these techniques in order to determine how and to which extent they can be applied to the automatic extraction of binary semantic relations in Portuguese texts. In that way, this work is an important step in the advancement of the state of the art in information extraction for the Portuguese language, which still lacks resources in the semantic area, and also advances the Portuguese language NLP scenario as a whole.
Refinamento de superfícies de quadriláteros baseado em templates
(Universidade Federal de São Carlos, 2013-07-11) Nakano, Davi Yoshinori Cangussú; Liziér, Mario Augusto de Souza; https://lattes.cnpq.br/1257131701222446; https://lattes.cnpq.br/8559140526906015
The computational representation of objects by means of polygonal meshes is widely used in various areas such as modeling, simulation, engineering, rendering process and various other CAD (Computer-Aided Design) and CAE (Computer-Aided Engineering) applications. These polygonal meshes are commonly built with triangles and processing these elements is widely studied, making that such techniques are well established and robust. However, there is a growing interest in quadrilateral meshes as they provide important characteristics for applications such as texturing and modeling with splines. With the increasing interest in the study of unstructured quadrilateral surfaces, there is the rise of new processing techniques related to simplification and refinement. This dissertation presents a complete pipeline for indirect generation of quadrilateral surface meshes, proposing a new refinement method of quadrilateral meshes. This new method is a local iterative subdivision process, ensuring the consistency of the mesh at each iteration and has the following main features: ability to guide the quality of generated quadrilaterals; control the number of generated elements; generate a family of models; control quadrilaterals density (adaptivity) and control the alignment of quadrilaterals lines with features lines of the model. The implementation restricts the refinement to homeomorphic models to a sphere. The results presented illustrate the effectiveness of the refinement technique and adaptivity control.