Otimização de uma cadeia de logística interna

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.

Caracterização da ocupação do solo com recurso à aplicação de modelos de misturas espectrais em séries multi-temporais de imagens MODIS

Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Ciência e Sistemas de Informação Geográfica

Cartografia multi-escala de alterações do coberto florestal com imagens de satélite

Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Ciência e Sistemas de Informação Geográfica

Development of procedures for the simulation of atmospheric flows over complex terrain, using OpenFOAM

The main purpose of this work was the development of procedures for the simulation of atmospheric ows over complex terrain, using OpenFOAM. For this aim, tools and procedures were developed apart from this code for the preprocessing and data extraction, which were thereafter applied in the simulation of a real case. For the generation of the computational domain, a systematic method able to translate the terrain elevation model to a native OpenFOAM format (blockMeshDict) was developed. The outcome was a structured mesh, in which the user has the ability to de ne the number of control volumes and its dimensions. With this procedure, the di culties of case set up and the high computation computational e ort reported in literature associated to the use of snappyHexMesh, the OpenFOAM resource explored until then for the accomplishment of this task, were considered to be overwhelmed. Developed procedures for the generation of boundary conditions allowed for the automatic creation of idealized inlet vertical pro les, de nition of wall functions boundary conditions and the calculation of internal eld rst guesses for the iterative solution process, having as input experimental data supplied by the user. The applicability of the generated boundary conditions was limited to the simulation of turbulent, steady-state, incompressible and neutrally strati ed atmospheric ows, always recurring to RaNS (Reynolds-averaged Navier-Stokes) models. For the modelling of terrain roughness, the developed procedure allowed to the user the de nition of idealized conditions, like an uniform aerodynamic roughness length or making its value variable as a function of topography characteristic values, or the using of real site data, and it was complemented by the development of techniques for the visual inspection of generated roughness maps. The absence and the non inclusion of a forest canopy model limited the applicability of this procedure to low aerodynamic roughness lengths. The developed tools and procedures were then applied in the simulation of a neutrally strati ed atmospheric ow over the Askervein hill. In the performed simulations was evaluated the solution sensibility to di erent convection schemes, mesh dimensions, ground roughness and formulations of the k - ε and k - ω models. When compared to experimental data, calculated values showed a good agreement of speed-up in hill top and lee side, with a relative error of less than 10% at a height of 10 m above ground level. Turbulent kinetic energy was considered to be well simulated in the hill windward and hill top, and grossly predicted in the lee side, where a zone of ow separation was also identi ed. Despite the need of more work to evaluate the importance of the downstream recirculation zone in the quality of gathered results, the agreement between the calculated and experimental values and the OpenFOAM sensibility to the tested parameters were considered to be generally in line with the simulations presented in the reviewed bibliographic sources.

A multiplying-by-two CMOS amplifier for high-speed ADCs based on parametric amplification

15th International Conference on Mixed Design of Integrated Circuits and Systems, pp. 177 – 180, Poznan, Polónia

Optimization of multi-stage amplifiers in deep-submicron CMOS using a distributed/parallel genetic algorithm

IEEE International Symposium on Circuits and Systems, pp. 724 – 727, Seattle, EUA

Multi-bit sigma-delta modulators with enhanced dynamic-range using non-linear DAC for hearing aids

15th IEEE International Conference on Electronics, Circuits and Systems, Malta

Context-aware multi-factor authentication

Trabalho apresentado no âmbito do Mestrado em Engenharia Informática, como requisito parcial para obtenção do grau de Mestre em Engenharia Informática

Experimental assessment of pressure drop in air stripping columns

One important step in the design of air stripping operations for the removal of VOC is the choice of operating conditions, which are based in the phase ratio. This parameter sets on directly the stripping factor and the efficiency of the operation. Its value has an upper limit determined by the flooding regime, which is previewed using empirical correlations, namely the one developed by Eckert. This type of approach is not suitable for the development of algorithms. Using a pilot scale column and a convenient solution, the pressure drop was determined in different operating conditions and the experimental values were compared with the estimations. This particular research will be incorporated in a global model for simulating the dynamics of air stripping using a multi variable distributed parameter system.

Eosinophil levels in the acute phase of experimental chagas' disease

Eosinophil dynamics, in bone marrow, blood and peritoneal exudate, of resistant C57B1/6 (C57) and susceptible A/Snell (A/Sn) mice was comparatively studied during the acute phase of infection by Trypanosoma cruzi Y strain. A decline was observed in bone marrow eosinophil levels in A/Sn, but not in C57 mice, soon after infection, those of the former remaining significantly below those of the latter up to the 4th day of infection. Bone marrow eosinophil levels of C57 mice declined subsequently to levels comparable to those of A/Sn mice, the number of these cells in this compartment remaining 50% those of non infected controls, in both strains, up to the end of the experiment on the 14th day of infection. The fluctuations in eosinophil levels in blood and peritoneal space were similar in both mice strains studied. Concomitantly with depletion of eosinophils in the marrow, depletion in blood and a marked rise of these cells in the peritoneal space, initial site of infection, occurred in both strains. The difference in eosinophil bone marrow levels, between C57 and A/Sn mice, observed in the first four days of infection, suggests a higher eosinopoiesis capacity of the former in this period, which might contribute to their higher resistance to T. cruzi infection.

A New Approach in the Design of Air Stripping Columns for the Treatment of Groundwater Contaminated With Volatile Organic Compounds

Volatile organic compounds are a common source of groundwater contamination that can be easily removed by air stripping in columns with random packing and using a counter-current flow between the phases. This work proposes a new methodology for column design for any type of packing and contaminant which avoids the necessity of an arbitrary chosen diameter. It also avoids the employment of the usual graphical Eckert correlations for pressure drop. The hydraulic features are previously chosen as a project criterion. The design procedure was translated into a convenient algorithm in C++ language. A column was built in order to test the design, the theoretical steady-state and dynamic behaviour. The experiments were conducted using a solution of chloroform in distilled water. The results allowed for a correction in the theoretical global mass transfer coefficient previously estimated by the Onda correlations, which depend on several parameters that are not easy to control in experiments. For best describe the column behaviour in stationary and dynamic conditions, an original mathematical model was developed. It consists in a system of two partial non linear differential equations (distributed parameters). Nevertheless, when flows are steady, the system became linear, although there is not an evident solution in analytical terms. In steady state the resulting ODE can be solved by analytical methods, and in dynamic state the discretization of the PDE by finite differences allows for the overcoming of this difficulty. To estimate the contaminant concentrations in both phases in the column, a numerical algorithm was used. The high number of resulting algebraic equations and the impossibility of generating a recursive procedure did not allow the construction of a generalized programme. But an iterative procedure developed in an electronic worksheet allowed for the simulation. The solution is stable only for similar discretizations values. If different values for time/space discretization parameters are used, the solution easily becomes unstable. The system dynamic behaviour was simulated for the common liquid phase perturbations: step, impulse, rectangular pulse and sinusoidal. The final results do not configure strange or non-predictable behaviours.

Gestão de multi-projeto no processo de desenvolvimento de produto

No âmbito da unidade curricular Dissertação/Projeto/Estágio do 2º ano do Mestrado em Engenharia mecânica – Ramo Gestão Industrial do Instituto Superior de Engenharia do Porto, o presente trabalho de dissertação foi enquadrado num projeto de desenvolvimento de ferramentas de apoio à gestão de projetos. O projeto foi desenvolvido no Instituto de Engenharia Mecânica e Gestão Industrial (INEGI) na unidade de Desenvolvimento de Produto e Sistemas (DPS). A realização deste projeto teve como objetivo o desenvolvimento e adequação de ferramentas de apoio à gestão de multi-projeto no processo de desenvolvimento de produto na organização em estudo – o INEGI – DPS. A gestão de projetos tem hoje uma grande importância nos resultados das empresas essencialmente em virtude da necessidade de estas competirem num mundo em grande mudança com concorrentes ferozes, em que a capacidade de responder às mudanças a tempo e de uma forma integrada se torna cada vez mais importante. A atividade levada a cabo pela DPS impõe a necessidade de uma gestão de projetos mais eficaz e eficiente suportada numa gestão de informação centralizada. O presente projeto de investigação teve, numa primeira fase, uma adaptação à organização em estudo. De seguida, foi conduzida uma revisão da literatura com o objetivo de se obter a fundamentação teórica necessária ao desenvolvimento de ferramentas com base nas metodologias lean. Prosseguiu com o levantamento da situação inicial da organização e com a identificação dos problemas existentes na gestão de projetos. Incluiu também uma revisão e análise das ferramentas existentes na unidade em estudo. Este conhecimento permitiu delinear uma visão para guiar o desenvolvimento das ferramentas. Após a definição da visão foi, então, realizado o desenvolvimento das ferramentas de auxílio à gestão multi-projeto na organização. A concretização deste trabalho resultou no desenvolvimento de três ferramentas de auxílio à gestão multi-projeto na unidade. Estas ferramentas tornam o processo de gestão de projetos mais simples e fácil de assimilar, requerendo apenas alguns inputs por parte dos colaboradores. Estas ferramentas estão apoiadas nos pilares do lean, e deste modo estão vocacionadas para reduzir o desperdício, promover a melhoria contínua, aumentar o desempenho global dos vários atores nos projetos de modo a entregar mais valor e qualidade superior com menores custos. Acima de tudo, valorizar o trabalho dos colaboradores, tornando-os mais eficientes, eficazes, motivados e comprometidos com a organização.

Kinectics of the pulmonary phase of Schistosoma mansoni in mice treated with dexamethasone

In the experimental schistosomiasis mansoni glucocorticoids cause a reduction in the worm burden when administered in the week of infection or, the longest, at the next week. In order to determinate the probable(s) site(s) of reduction of the worm burden, mice were infected with cercariae of LE strain of S. mansoni and dexamethasone was administered daily (50 mg/kg, subcutaneously) starting 1 hour before infection until the eighth day. Mice were sacrificed daily starting on the third day after infection until the ninth day, and schistosomula from lungs were collected. Six weeks after infection, the remaining mice were sacrificed and perfused for adult worm recovery. Analysis of the results showed that the non-treated mice presented larger numbers of lung larvae than the treated ones, and this difference was also found later in the worm burden in the portal system. This difference may reflect the early death of larvae in treated animals, before or after reaching the lungs.

POST-PROCESSING TECHNIQUES SUITABILITY FOR MESOLEVEL FREE BOUNDARY FLOWS

Reliable flow simulation software is inevitable to determine an optimal injection strategy in Liquid Composite Molding processes. Several methodologies can be implemented into standard software in order to reduce CPU time. Post-processing techniques might be one of them. Post-processing a finite element solution is a well-known procedure, which consists in a recalculation of the originally obtained quantities such that the rate of convergence increases without the need for expensive remeshing techniques. Post-processing is especially effective in problems where better accuracy is required for derivatives of nodal variables in regions where Dirichlet essential boundary condition is imposed strongly. In previous works influence of smoothness of non-homogeneous Dirichlet condition, imposed on smooth front was examined. However, usually quite a non-smooth boundary is obtained at each time step of the infiltration process due to discretization. Then direct application of post-processing techniques does not improve final results as expected. The new contribution of this paper lies in improvement of the standard methodology. Improved results clearly show that the recalculated flow front is closer to the ”exact” one, is smoother that the previous one and it improves local disturbances of the “exact” solution.

DOT-ELISA for detection of anti-Cysticercus cellulosae antibodies in human cerebrospinal fluid using a new solid-phase (resin-treated polyester fabrics): preliminary report

A dot enzyme-linked immunosorbent assay (DOT-ELISA) was developed to detect specific antibodies in cerebrospinal fluid (CSF) for human neurocysticercosis immunodiagnosis, with Cysticercus cellulosae antigen dotted on a new solid-phase. This was represented by sheets of a synthetic polyester fabric impregnated with a polymerized resin (N-methylol-acrylamide). A very stable preparation was thus obtained, the antigen being covalently bound by cross-linking with free N-methylol groups on the resin. Since robust, no special care was necessary for handling the solid-phase. The test could be performed at room-temperature. From 30 CSF samples assayed, 14 were positive, from a group of 15 cases of neurocysticercosis, with titers from 1 to 128; 15 other samples, from normals or other neurological diseases, were all negative. Test characteristics seem to indicate it as adequate for epidemiological surveys. A more detailed study on sensitivity, specificity, reproducibility and the use in serum samples is being conducted.