Faculdade de Engenharia Mecânica - FEM/ITEC
URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2551
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Item Acesso aberto (Open Access) Modelagem do tempo de execução de obras civis: estudo de caso na Universidade Federal do Pará(2012-03) COUTINHO, Lêda Sílvia de Aguiar Lédo; DUARTE, André Augusto Azevedo Montenegro; NEVES, Renato Martins das; COUTINHO NETO, Benedito; MANESCHY, Carlos Edilson de Almeida; PINHEIRO, Ana Maria Guerra SeráficoThis article proposes the adoption of a numerical prognosis model to estimate the variable "execution time" for public projects in an objective way. The field work consisted of the application of statistical methods for analyzing data from projects that were bid and contracted by the Federal University of Pará (UFPA) between 2006 and 2009. Data analysis involved linear regression and transformed functions. After the stratification and initial treatment of the data, the evidence adopted for the construction of the final model was limited to 102 out of the 225 projects originally investigated, resulting in the following statistical parameters: correlation coefficient (R) of 0.899, coefficient of determination (R2) of 0.808, adjusted coefficient of determination (adjusted R2) of 0.796, and standard error (Se) of 0.41. These parameters show a strong linear correlation between the variables, indicating that 79.60% of the variability of the execution of a public project is jointly caused by variations in the gross floor area, the estimated cost, the operational technical capacity of the client organization; the operational capacity of the company; the type of service, and the season.Item Acesso aberto (Open Access) Production and evaluation of recycled polymers from açaí fibers(2010-06) CASTRO, Clívia Danúbia Pinho da Costa; DIAS, Carmen Gilda Barroso Tavares; FARIA, José de Assis FonsecaThe possibility of recycling and the favorable mechanical properties of the products have encouraged the study and production of thermoplastic composites from natural fibrous waste. Açaí (cabbage palm) fiber, which is removed from the seed, has been slightly investigated, as compared to what is already known about the fruit pulp. In this study, the influence of açaí fiber as an element of reinforcement in recycled everyday usage thermoplastics using simple, low cost methodology was evaluated. Recycled matrixes of high impact polystyrene and polypropylene were molded by hot compression from which the fiber composites were obtained. The FTIR technique showed that the process was efficient in preventing degradation of the açaí fibers. The influence of the fiber on the mechanical behavior of the recycled matrixes was investigated by microscopic images of compression and impact tests. The results showed better impact performance for the fiber combined with the polymeric matrixes.