Navegando por Data de Publicação, começando com "2022-03-23"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 6 de 6

Atomização a gás do aço ferramenta A2: efeito dos parâmetros de processo nas características do pó
(Universidade Federal de São Carlos, 2022-03-23) Mathias, Laura Emi Tavoni; Gargarella, Piter; https://lattes.cnpq.br/4641435644243916; https://lattes.cnpq.br/6497697599064366
Gas atomization is the main method in powder metallurgy to produce powders for additive manufacturing (AM). The gas atomization process allows generally spherical and very fine metallic powders with great yield on the particle size range for AM applications. Moreover, this is a rapid solidification process that ensures chemical homogeneity and a high degree of microstructural refinement. Iron-based alloys have wide properties range and low cost, in which tool steels are especially important for industrial applications. This project produced A2 tool steel powders by gas atomization and evaluated the influence of the process parameters on the characteristics of the powders. No systematic study has been carried out on atomization and AM of this tool steel. Thus, analyzing the gas atomization process of this material is important to ensure the production of powders with proper characteristics. The statistical tool of design of experimental (DOE) was applied, and the atomization pressure and melt superheat process parameters were analyzed. The response variables analyzed were morphology, median particle size, particle size distribution, density and flowability. The powder characterization was done by laser diffraction, sieving, scanning electron microscopy, chemical analyses by EDS, flowability by Hall and Carney Flowmeter Funnel, density by helium pycnometry and apparent density. This study showed that the gas atomization process of the A2 tool steel was suitable for the production of powders for applications in AM. The model proposed by Lubanska, which formulate the mass median particle diameter, was also validated. Furthermore, the process with the lowest pressure level (20Bar) and the highest melt superheat (300K) has the lowest gas/metal ratio and mean particle size (D50) and particle size distribution similar to the other powders produced.
Influência da morfologia no comportamento magnético em aglomerado de CoTPP
(Universidade Federal de São Carlos, 2022-03-23) Rocha, Alberto José Moreira; Souza, Ernesto Chaves Pereira de; https://lattes.cnpq.br/1505400360366643; Oliveira, Adilson Jesus Aparecido de; https://lattes.cnpq.br/4640148190073166; https://lattes.cnpq.br/1350050841034770
The study of magnetic properties in organic molecules with transition metals has been intense in recent decades, mainly due to the ease of changing their magnetic behavior, either through the introduction of different types of atoms or through changes due to proximity effects with other materials. This thesis we presents the investigation of the magnetic behavior of samples of Cobalt 5-10-15-20-meso-tetraphenylporphyrin (CoTPP) deposited on SiO2 surface. The results showed high values of magnetic moment which as a consequence, led to the appearance of superparamagnetism in samples with a morphological aspect a few deposit, which suggest an interdependence between the morphology and the magnetic response. With aid of morphological techniques, it was possible to suggest the causes magnetic response. These results indicate the possibility of altering the magnetic behavior from changes in the morphology of the samples.
Engajamento de crianças com Transtorno do Espectro Autista nas rotinas da educação infantil
(Universidade Federal de São Carlos, 2022-03-23) Morais, Giovana Cássia de; Elias, Carina Sousa; https://lattes.cnpq.br/0070734946202776; Della Barba, Patrícia Carla de Souza; https://lattes.cnpq.br/6448489426438006; https://lattes.cnpq.br/1380564219031076
Child development monitoring is increasingly essential for identifying potential and difficulties in learning. Engagement in routines is one of the factors that can contribute to the achievement of children's goals in a variety of areas, whether they have typical or atypical development. The beginning of the school life of children with Autism Spectrum Disorder (ASD) can be a challenge for quality participation in Early Childhood Education routines. In this way, understanding the functioning and profile of engagement in school routines can make an important contribution, both to the educators and family members, and also to the gain of academic knowledge. Therefore, the present study aimed to identify how the engagement of children aged 3 to 5 years old with a diagnosis of ASD in the routines of Early Childhood Education occurred, from the point of view of educators. The research was carried out in the national territory and the method was quantitative and descriptive, without manipulation of variables. Data collection and analysis took place under the following structure: response to an online form via “Google Forms” by each child's educator, with questions of the ClaMEISR’s instrument - Classroom Measure of Engagement, Independence, and Social Relationships. The objective of the protocol is to help the school team and the family in the evaluation of the routines of children aged between 3 and 5 years old. The score was obtained through questions about activities carried out by the children during a day at school, making it possible to assess how engaged the child was in each of their routines, so this could be monitored and worked on. As a result, it was found that the children with ASD did not show sophisticated engagement in the analyzed routines, demonstrating the need for curricular adaptations as something fundamental for expanding engagement in the educational context for students who are part of school inclusion programs. In the conclusion there is the suggestion of future studies to cover different age groups, in order to understand the impacts of engagement in the scholar context, and also how the environmental factors may favor or limit it.
Agricultura familiar e crédito via PRONAF: fatores determinantes da utilização nas regiões Serrana, Norte e Noroeste do Rio de Janeiro
(Universidade Federal de São Carlos, 2022-03-23) Almeida, Claudio Cezar; Batalha, Mario Otávio; https://lattes.cnpq.br/1015001063418091; https://lattes.cnpq.br/6717374300414740
Family farming is of great importance to the Brazilian economy, due to its participation in food production and its ability to employ labor. Also, in Rio de Janeiro, family farming is highlighted, especially in the Mountain, Northern and Northwest regions. However, throughout Brazil, family farming faces important challenges to fully exploit its potential. The credit is among these challenges. For family farmers, credit is a vitally important element. With this perspective and aiming to strengthen the granting of credit under conditions consistent with the reality of family farming, the federal government created in 1996 the National Program for Family Agriculture (PRONAF). This program has played an important role in providing credit for family farmers throughout Brazil. In eight months of the 2021/2022 harvest, 1,274 thousand rural credit contracts were financed, corresponding to an amount of R$ 188.4 billion (BRASIL, 2022). However, in some regions it is less used than in others. In the northeast, for example, only 7.3% of family farmers accessed PRONAF in 2016, while in the southern region this percentage reaches 48.8% (IBGE, 2017). This is the case, for example, of the regions studied in this thesis. Without having the objective of making a comparative study between regions of Brazil, it is important to know which factors can best explain the raising of credit, via PRONAF, by farmers in the Mountain, Northern and Northwest regions of the State of Rio de Janeiro. Thus, this work has as main objective to identify determining factors of access to rural credit by family farmers located in the Mountain, North and Northwest regions of the State of Rio de Janeiro. To achieve this objective, were used primary data collected through face-to-face interviews in 499 households, distributed in the three regions. These data were analyzed in a logistic linear regression model, built from a set of hypotheses that are based on a conceptual model built with theoretical elements of the Resource-Based View and the Transaction Cost Theory. The results obtained through the econometric model made it possible to confirm the identification of four factors (marital status of the family farmer, the share of the value of rural production in the total income of the property, the availability of guarantees and access to technical assistance) as determining factors of access to PRONAF credit by family farmers in the state of Rio de Janeiro, in addition to providing subsidies to suggest measures related to rural credit and improvements in the management of properties and production processes of family farmers.
Sistema mecatrônico para identificação automática de filamento polimérico utilizado em processo de Manufatura Aditiva (Impressão 3D)
(Universidade Federal de São Carlos, 2022-03-23) Cardinal, Gabriel Cioffi; Endo, Marcos Tan; https://lattes.cnpq.br/7506367468260024; Aroca, Rafael Vidal; https://lattes.cnpq.br/9262228584082064; https://lattes.cnpq.br/2285129056491976
Technological development and the improvement of manufacturing processes allowed the emergence of new manufacturing techniques over time. 3D printing has become a practical and affordable way to manufacture parts, products and components, whether mechanical or structural. This technology is increasingly common, both in industrial and private environments, due to its versatility and easy interaction with the method. However, in additive manufacturing, it is necessary to know the material that is being used, since the configuration of FDM (Fused Deposition Modeling) 3D printers for a given polymer directly impacts the proper functioning and quality of the manufactured part. In the present work, the construction of a low-cost prototype capable of differentiating Polylactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) filaments was carried out through the indirect measurement of an intrinsic mechanical property of the materials, the hardness. This procedure was possible by building a system, driven by a servo motor linked to a four-bar mechanism, capable of measuring the difference in the penetration depth of a metallic tip in the filaments, through the interaction of a magnet with a Hall effect sensor. It was possible to identify both filaments from the differentiation of hardness, and the results were in line with the references provided by the manufacturer of PLA and ABS filaments.
Modelos para estimativas de propriedades físico- mecânicas de espécies de madeiras tropicais em função da densidade aparente e da frequência de vibração transversal
(Universidade Federal de São Carlos, 2022-03-23) Silva, Larissa Soriani Zanini Ribeiro Soares; Lahr, Francisco Antonio Rocco; https://lattes.cnpq.br/2333091200416653; Christoforo, André Luis; https://lattes.cnpq.br/7623383075429186; https://lattes.cnpq.br/7913802144430798
The wood is an excellent material of constructive application, little inserted to the market of the national construction, but with great potential of exploration. This fact is justified not only by restrictions of a social-historical nature, but also by the ignorance of the species and their properties. The difficulties in characterization the wood, given the amount of test required and the need for specific machinery and specialized labor, contribute even more to the current situation. As an alternative to simplify the knowledge of the properties of wood, this study aims to adopt a new technological solution to estimate the physical-mechanical properties, non- desctrutive characterization, of tropical wood through the combination of apparent density and the natural frequency (first mode) of the transverse vibration test, based on regression models, given the lack of studies, at national and global levels, that use these two tests combined as estimators of all the physical-mechanical properties of wood. For this, 05 species of tropical wood were distributed in the resistance classes (C20 to C60) of the hardwood group. Sixty transverse vibration tests were be carried out on pieces of structural dimensions of square section (12 cm x12 cm) and variable length (2 m to 2.7 m) and another 720 of wood characterization, in specimens standardized according to ABNT NBR 7190:1997, totaling 780 experiments. For each species, and for the grouping, linear regression models were generated as a function of bulk density and transverse vibration frequency, as well as multivariable quadratic regression models using bulk density and vibration frequency as independent variables in order to estimate the physical-mechanical properties of the woods. From the regression models for the species in isolation, with the exception of the class C40 species, little correlation was noted between density and natural frequency with the other properties, resulting in estimates of poor precision. For the set of species, the best adjusted coefficients of determination (R²aj) were obtained when analyzing the quadratic multivariable regression models, obtaining values greater than 70% for 13 models out of the 16 evaluated. It is noteworthy that, for the main mechanical properties of the woods, and of greater importance for the structural calculation (fc0, fv0, fM, Ec0 and EM), the adjusted coefficients of determination were above 80%, indicating models with excellent fits for the prediction of properties.