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A aprendizagem de polinômios através da resolução de problemas por meio de um ensino contextualizado
(Universidade Federal de São Carlos, 2008-03-20) Morais, Rosilda dos Santos; Hartwing, Dácio Rodney; https://lattes.cnpq.br/8411023309452408
The objective of this study was to verify how learning of polynomials took place using problem solving in a contextualized learning situation. Thus, the present research was developed in the context of polynomials, based on the construction of cardboard boxes, using students previous knowledge. Based on a bibliographic review of studies on the theme, we defined the categories of comprehension of the concepts: Contextualization, Previous knowledge, and Mathematics teaching-learning-evaluation through problem solving. Since the phenomenon of interest in the study is related to the school, specifically the study of polynomials, it constitutes an intervention of a qualitative nature in a specific situation: a long-term case study. Based on Problem Solving as a teaching-learning method in the classroom, we sought to give students the opportunity to do hands-on mathematics , i.e. develop the content of polynomial in a way that students could collect, experiment, and analyze, in a real-world context, subjacent mathematical patterns. All the work was developed in an interactive situation, with the students divided into groups. This research was carried out over the course of two projects: Project I, conducted with 6th graders in the context of constructing cardboard boxes Polynomials and the operations defined by them (2006); and Project II, conducted with same students one year later, in 8th grade Appropriation of concepts constructed in Project I, and the exploration, based on this work, of the important algebraic concept known as Function . Analyzing the work carried out, we found that the development of the concept polynomial , followed by the concept function , using the manipulation of concrete materials, resulted in more meaningful learning for the students. Starting with a concrete situation, followed by generalization and abstraction in a higher stage of learning, the students, as co-constructors of knowledge, were able to establish relations between the themes addressed throughout the work, within a broader system, where meanings and conventions were being established.
Conformação viscoplástica por rolos a frio e caracterização de substratos de alumina
(Universidade Federal de São Carlos, 2008-03-20) Koshimizu, Laís; Morelli, Márcio Raymundo; https://lattes.cnpq.br/0172837599844991; https://lattes.cnpq.br/8051781707103248
Alumina ceramic substrates were conformed by viscoplastic conformation by cold roll pressing in a range of thickness between 100 and 200 µm, which one presents a great technology interesting for eletro-eletronic applications. Among all the techniques of ceramic conformation the viscoplastic processing shows great advantages, allowing the conformation oh ceramic bodies with superior mechanical properties, when compared to the bodies conformed by traditional techniques, such as extrusion, or more complex as tape casting. In this scope, the objective of this work was to verify the potential of viscoplastic conformation by cold roll pressing as a technique to obtain thin substrates, from a high alumina plastic mass prepared in a sigma mixer and extruded by vacuum. In this way, parameters process such as the speed of the rollers and the thickness of the substrates were evaluated, as well as the stages of shrinkage and firing. The final samples were characterized by determination of the microstructure, apparent density and porosity, volume retraction, penetrating liquid and surface roughness. The results showed that the speed of rollers around 15 and 18 rpm provided substrates without the presence of macro defects. Moreover, there s no correlation between the thickness of the substrates and the final characteristics after sinterization, and there s no preferential orientation of the particles when the mass of submitted to plastic deformation. Density superior to 95% of theoretical density were achieved, producing translucent samples and a great homogeneity of the grain size. After the establishment of best conditions for preparation of alumina substrates, they have been applied in the preparation of zirconia substrates with reproducibility of the results, showing that the viscoplastic processing by roll pressing can be an alternative process for the manufacture of ceramic substrates.