987 resultados para continuous production


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Thesis for the Degree of Master of Science in Biotechnology Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

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Atualmente qualquer organização que se queira manter no ativo, tem que obrigatoriamente inovar, reduzir o desperdício associado ao processo produtivo e simultaneamente simplificar as tarefas diárias dos seus colaboradores. E é sobre estes princípios que este trabalho é baseado, ou seja, pretende-se através da aplicação de ferramentas Lean, a melhoria contínua do processo de produção da Schmitt Elevadores. Numa fase inicial foi necessário um estudo dos diferentes fluxos de materiais, que permitiu a conceção do VSM (Value Stream Mapping). O VSM juntamente com o diagrama de Spaghetti permitiram a identificação de algumas das fontes de desperdício, relacionadas essencialmente com o excesso de movimentações. Considerando o âmbito do estágio, logística interna, e reunidas as causas de desperdício verificadas nesta área, procedeu-se à criação de um ciclo de entrega de materiais, por parte do operador logístico, baseado no conceito de milk run. Verificaram-se também problemas ao nível da gestão de stocks, pelo que também foi necessária intervenção nesta área. A aplicação das medidas mencionadas anteriormente irá traduzir-se em ganhos para o processo produtivo, nomeadamente, na criação de rotinas para os operadores logísticos; evitar deslocações por parte dos operadores de cada processo e manter em supermercado a quantidade suficiente de cada artigo, para fazer face à variabilidade da procura.

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores

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A realização deste trabalho teve como principal objectivo proceder ao projecto e realização de dois sistemas de produção de perfis pultrudidos híbridos a acoplar aos equipamentos de pultrusão já instalados na ALTO – PERFIS PULTRUDIDOS, Lda. A realização de perfis pultrudidos híbridos visa melhorar as características de isolamento térmico e acústico dos tubos habitualmente feitos por pultrusão, incrementando simultaneamente a sua resistência, através da melhoria do momento de inércia do perfil, sem que haja um aumento significativo do peso do conjunto. O projecto teve como base de trabalho dois sistemas de produção completamente distintos: (a) a existência de barras de cortiça e de poliuretano (pré-formas) sobre as quais se vai efectuar a pultrusão de um tubo que abraça as barras e (b) o uso de resíduos de pultrusão como forma de enchimento dos tubos, durante o seu processo produtivo. Estes equipamentos foram projectados e parcialmente fabricados, antevendo-se que os mesmos entrem em funcionamento muito brevemente.

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica

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Trabalho Final de mestrado para obtenção do grau de Mestre em Engenharia Mecânica perfil Manutenção e Produção

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica Perfil de Manutenção e Produção

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In this study, the added value resultant from the incorporation of pultrusion production waste into polymer based concretes was assessed. For this purpose, different types of thermoset composite scrap material, proceeding from GFRP pultrusion manufacturing process, were mechanical shredded and milled into a fibrous-powdered material. Resultant GFRP recyclates, with two different size gradings, were added to polyester based mortars as fine aggregate and filler replacements, at various load contents between 4% up to 12% in weight of total mass. Flexural and compressive loading capacities were evaluated and found better than those of unmodified polymer mortars. Obtained results highlight the high potential of recycled GFRP pultrusion waste materials as efficient and sustainable admixtures for concrete and mortar-polymer composites, constituting an emergent waste management solution.

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Manufacturing processes need permanently to innovate and optimize because any can be susceptible to continuous improvement. Innovation and commitment to the development of these new solutions resulting from existing expertise and the continuing need to increase productivity, flexibility and ensuring the necessary quality of the manufactured products. To increase flexibility, it is necessary to significantly reduce set-up times and lead time in order to ensure the delivery of products ever faster. This objective can be achieved through a normalization of the pultrusion line elements. Implicitly, there is an increase of productivity by this way. This work is intended to optimize the pultrusion process of structural profiles. We consider all elements of the system from the storehouse of the fibers (rack) to the pultrusion die. Particular attention was devoted to (a) the guidance system of the fibers and webs, (b) the resin container where the fibers are impregnated, (c) standard plates positioning of the fibers towards the entrance to the spinneret and also (d) reviewed the whole process of assembling and fixing the die as well as its the heating system. With the implementation of these new systems was achieved a significant saving of time set-up and were clearly reduced the unit costs of production. Quality assurance was also increased.

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Proceedings of tile 1" R.C.A.N.S. Congress, Lisboa, October 1992

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Four Cynara cardunculus clones, two from Portugal and two from Spain were studied for biomass production and their lignin was characterized. The clones differed in biomass partitioning: Spanish clones produced more capitula (54.5% vs. 43.9%), and Portuguese clones more stalks (37.2% vs. 25.6%). The heating values (HHV0) of the stalks were similar, ranging from 17.1 to 18.4 MJ/kg. Lignin was studied by analytical pyrolysis (Py-GC/MS(FID)), separately in depithed stalks (stalksDP) and pith. StalksDP had in average higher relative proportions of lignin derived compounds than pith (23.9% vs. 21.8%) with slightly different lignin monomeric composition: pith samples were richer in syringyl units as compared to stalksDP (64% vs. 53%), with S/G ratios of 2.1 and 1.3, respectively. The H:G:S composition was 7:40:53 in stalksDP and 7:29:64 in pith. The lignin content ranged from 18.8% to 25.5%, enabling a differentiation between clones and provenances. © 2015 Elsevier Ltd. All rights reserved.

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This paper describes preliminary work on the generation of synthesis gas from water electrolysis using graphite electrodes without the separation of the generated gases. This is an innovative process, that has no similar work been done earlier. Preliminary tests allowed to establish correlations between the applied current to the electrolyser and flow rate and composition of the generated syngas, as well as a characterisation of generated carbon nanoparticles. The obtained syngas can further be used to produce synthetic liquid fuels, for example, methane, methanol or DME (dimethyl ether) in a catalytic reactor, in further stages of a present ongoing project, using the ELECTROFUEL® concept. The main competitive advantage of this project lies in the built-in of an innovative technology product, from RE (renewable energy) power in remote locations, for example, islands, villages in mountains as an alternative for energy storage for mobility constraints.

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The proper disposal of the several types of wastes produced in industrial activities increases production costs. As a consequence, it is common to develop strategies to reuse these wastes in the same process and in different processes or to transform them for use in other processes. This work combines the needs for new synthesis methods of nanomaterials and the reduction of production cost using wastes from citrine juice (orange, lime, lemon and mandarin) to produce a new added value product, green zero-valent iron nanoparticles that can be used in several applications, including environmental remediation. The results indicate that extracts of the tested fruit wastes (peel, albedo and pulp fractions) can be used to produce zero-valent iron nanoparticles (nZVIs). This shows that these wastes can be an added value product. The resulting nZVIs had sizes ranging from 3 up to 300 nm and distinct reactivities (pulp > peel > albedo extracts). All the studied nanoparticles did not present a significant agglomeration/settling tendency when compared to similar nanoparticles, which indicates that they remain in suspension and retain their reactivity.

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Within a large set of renewable energies being explored to tackle energy sourcing problems, bioenergy can represent an attractive solution if effectively managed. The supply chain design supported by mathematical programming can be used as a decision support tool to the successful bioenergy production systems establishment. This strategic decision problem is addressed in this paper where we intent to study the design of the residual forestry biomass to bioelectricity production in the Portuguese context. In order to contribute to attain better solutions a mixed integer linear programming (MILP) model is developed and applied in order to optimize the design and planning of the bioenergy supply chain. While minimizing the total supply chain cost the production energy facilities capacity and location are defined. The model also includes the optimal selection of biomass amounts and sources, the transportation modes selection, and links that must be established for biomass transportation and products delivers to markets. Results illustrate the positive contribution of the mathematical programming approach to achieve viable economic solutions. Sensitivity analysis on the most uncertain parameters was performed: biomass availability, transportation costs, fixed operating costs and investment costs. (C) 2015 Elsevier Ltd. All rights reserved.

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Siderophore production by Bacillus megaterium was detected, in an iron-deficient culture medium, during the exponential growth phase, prior to the sporulation, in the presence of glucose; these results suggested that the onset of siderophore production did not require glucose depletion and was not related with the sporulation. The siderophore production by B. megaterium was affected by the carbon source used. The growth on glycerol promoted the very high siderophore production (1,182 μmol g−1 dry weight biomass); the opposite effect was observed in the presence of mannose (251 μmol g−1 dry weight biomass). The growth in the presence of fructose, galactose, glucose, lactose, maltose or sucrose, originated similar concentrations of siderophore (546–842 μmol g−1 dry weight biomass). Aeration had a positive effect on the production of siderophore. Incubation of B. megaterium under static conditions delayed and reduced the growth and the production of siderophore, compared with the incubation in stirred conditions.