O objetivo desta dissertação é realizar e comparar a aplicação da modelagem dinâmica de sistemas (MDS) e do activity based costing (ABC) para mensurar os custos em manufatura celular. Nesse sentido, foi realizada uma simulação utilizando os conceitos de MDS para obter os custos de produção de quatro produtos, em um ambiente de manufatura celular, considerando o método ABC e a comparação desses valores com a técnica de custeio tradicional ou absorção. Quanto à metodologia de pesquisa, esse trabalho é de enfoque quantitativo no qual o tipo de pesquisa é exploratório sem estabelecimento de hipóteses, porém, guiada pelos seus objetivos. Os resultados obtidos demonstram que a aplicação do ABC juntamente com a MDS é muito satisfatória quando comparada com a técnica tradicional. Finalmente, a aplicação do ABC com a MDS pode ser utilizada eficientemente como um método alternativo para custeio em manufaturas celulares. / The aim of this dissertation is to apply and to compare the modeling system dynamics (MDS) and activity based costing (ABC) to measure the costs in cellular manufacture. Taking this into account, a simulation was accomplished using the concepts of MDS to obtain the costs of production of four products, in an environment of cellular manufacture, considering ABC method and the comparison of those values with the technique of traditional costing. As for the research methodology, this dissertation is of quantitative focus in which the research type is exploratory without establishment of hypotheses, however guided by their objectives. The obtained results demonstrate that the application of ABC together with MDS it is very satisfactory when compared with the traditional technique. In conclusion, it can be observed that the application of ABC with MDS can be used efficiently as an alternative method to costing in cellular manufacture.

Reliability and redundancy of safety-critical network systems is a paramount issue in system engineering. Be it in evaluating existing network systems or solving optimization problems for designing network systems, it is important to consider reliability and redundancy. This dissertation is in collaboration with AIRBUS Group, France, and they are very interest in the optimal design of safety-critical aircraft architecture systems which have to consider reliability and redundancy. To address the problem of optimally designing such systems, we chose to focus on one specific aircraft architecture system the door management system. It checks if all doors are properly closed and the cabin has the correct pressure. It is a safety-critical system since it is part of the pressurization system of an aircraft. To optimally design the DMS while considering reliability, a suitable reliability evaluation algorithm is necessary. In this dissertation, we begin by proposing a suitable reliability evaluation algorithm for a type of non series-parallel network system which includes the DMS and which can be used in an optimization model. The reliability evaluation algorithm is based on a simplification of the probability principle of inclusion-exclusion formula for intersections of unions. The simplification exploits the presence of many repeated events and has many fewer terms, which significantly reduces the number of operations needed. We compare its computational efficiency against the sum of disjoint products method KDH88 for a simple artificial example and for the DMS. Afterwards, we introduce the first MILP model for the DMS with k-redundancy. As the model is too difficult to be solved efficiently by standard MILP solvers, we discuss the issues of solving the model with general solving methods such as branch-and-bound and branch-and-price. We introduce specialized branching rules and new heuristics to solve the DMS problem with k-redundancy more efficiently and show results of computational tests which compare the specialized solving algorithms with general solving algorithms for example instances of the DMS problem. Lastly, we discuss the problems of considering reliability in MI(N)LP models for the DMS and how the new reliability evaluation algorithm can be used. In this discussion, we give different MI(N)LP models for the DMS problem with redundancy and reliability. Moreover, we propose a new heuristic for the DMS problem with redundancy and reliability. It is based on branch-and-bound, the Dantzig-Wolfe decomposition and on the new reliability evaluation algorithm. We show results of computational tests of the new heuristic for example instances of the DMS problem and discuss its validity.

Estágio realizado na Hidromac e orientado pelo Eng.º Celso Cavadas / Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 2008

Tese de mestrado. Engenharia Informática. Faculdade de Engenharia. Universidade do Porto. 2005

The potential for life to control its environment was first suggested by Lovelock (1972). Charlson et al (1987) proposed a role for marine planktonic ecosystems in global climate regulation via the production and ventilation to the atmosphere of dimethylsulphide (DMS), a by-product of phytoplankton metabolism. Once in the atmosphere DMS contributes to the formation of cloud condensation nuclei, and increases the amount and brightness of cloud. This affects the albedo of the planet, reflecting more incident sunlight back into space, and cooling the earth. In common with many other 'hypotheses' regarding complex adaptive systems, the hypothesis proposed by Charlson et al (1987) is not experimentally testable. The production and ventilation to the atmosphere of DMS is the result of complex interactions between biological, chemical and physical processes. Consequently, increasing use is being made of mathematical models that simulate these processes to advance understanding of it (Archer et al. 2002). This study examines one of the fundamental mechanisms proposed by the Charlson et al (1987) hypothesis, that increasing global temperatures will lead to increased ventilation of DMS from the ocean to the atmosphere. The study develops one-dimensional biogeochemical models of DMS production by upper ocean ecosystems, based on the model proposed by Gabric et al. (1993b). The models are examined to elucidate their fundamental mathematical properties, and are subjected to sensitivity analysis to identify important processes and parameters. These investigations identify a simpler model that can reproduce the predictions of the Gabric et al. (1993b) model. Predictions derived from model simulations forced by climatologies of measured physical data are compared to a global database of measurements of sea surface DMS concentrations, and to observed depth profiles of DMS in the upper ocean. These comparisons confirm that all models are in good qualitative agreement with measured data. The fifteen global climate prediction models currently in use around the globe all predict substantial warming effects from the ventilation of anthropogenic carbon dioxide to the atmosphere. A simplified DMS model is calibrated to climatologies of Antarctic chlorophyll and DMS data and reproduces the data with great precision. The calibrated model is applied in global warming scenarios to 'test' the efficacy of the mechanism proposed by the Charlson et al (1987) hypothesis. This simulation provides evidence that the response predicted by the hypothesis is indeed feasible, and that substantial increases (up to 45%) in the ventilation of DMS to the atmosphere could be possible in some circumstances. The results of the modelling study provide impetus for further examination of field data. If couplings between marine biota and atmosphere are feasible, then they may be operating contemporarily, and may be detectable. Atmospheric DMS is oxidised to form aerosols (Miller et al. 2002) that influence the aerosol optical depth of the atmosphere. Archives of remote sensed ocean chlorophyll a concentration and aerosol optical depth are examined for evidence of the biologically mediated couplings. A clear coupling between aeolian dust and marine phytoplankton is evident from this analysis, suggesting that the deposition of dust from the atmosphere is a major factor controlling phytoplankton growth in many parts of the ocean. A second coupling between marine phytoplankton and atmospheric aerosols is also detected. This coupling is apparently not related to dust and is symmetrical about the equator, despite the substantial differences in the atmospheres and oceans of each hemisphere. It is speculated that this coupling may reflect the influence of the ventilation of DMS produced by marine phytoplankton on the atmosphere. This thesis provides new evidence supporting the important role of marine ecosystems in global climate regulation by the production of DMS. This evidence is principally obtained from a biogeochemical modelling approach, but is supported by analyses of empirical data. The concordance of results obtained from different approaches suggests that the contribution of marine ecosystems to global climate regulation is real, important and currently active.

Active work to increase the efficiency of energy use is taking place in Sweden and throughout all of Europe. Electricity is an important part in our society’s energy system which means that the electrical grid operators and associated therewith has a central role in this work. Monitoring and controlling the electrical grids are managed from the distribution system operator’s DC, dispatch center. The aim of this report is to examine how the operations in a typical DC on the Swedish electricity distribution network will look like in five to ten years. The report focuses on DC’s that operate electrical grids at low- and medium voltage level. For a concrete way to determine how the DC will change over time the different operational processes that constitute the ope- ration of a DC were defined. Subsequently the changes that will affect the Swedish electrical grids within five to ten years were investigated and also in which way these changes will implicate the operational processes in a DC. The analysis shows that the DC’s will undergo a series of transformations in five to ten years. By integrating the various IT-systems in the dispatch center the main operation will be manageable from a single HMI, such as a DMS-system. This means that business processes such as monitoring, ope- rational order processing and error handling will be possible from a single system in the future. But the increasing communication between IT systems will also lead to increased demands for security because any intrusion in one of the systems could result in major damage.

Recent field observations suggest that the radiative forcing of aerosol and clouds in the Arctic may be seasonally regulated by the oceanic emissions of the climatically-important biogenic trace gas dimethylsulfide (DMS). However, the validity of the proposed argument is challenged by the limited spatio-temporal coverage of these earlier studies in this difficult-to-access region. In particular, little is known about the pan-Arctic distribution of the oceanic DMS emissions, its temporal variability, and the impacts of sea-ice biogeochemistry on these emissions. In this dissertation, I investigated these unexplored subjects through numerical modelling. Using a one-dimensional (1-D) column modelling framework, I developed a coupled sea ice-ocean biogeochemical model and assessed the impacts of bottom-ice algae ecosystems on the underlying pelagic ecosystems and the associated production and emissions of DMS. The model was calibrated by time-series measurements of snow and melt-pond depth, ice thickness, bottom-ice and under-ice concentrations of chlorophyll-a and dimethylsulfoniopropionate (DMSP), and under-ice irradiance obtained on the first-year landfast sea ice in Resolute Passage during May-June of 2010. Many of the model parameters for the DMSP and DMS production and removal processes were derived from recent field measurements in the Arctic, which is advantageous over the previous Arctic-focused DMS model studies as their model parameters were based on the measurements in extra-polar regions. The impacts of sea-ice biogeochemistry on the DMS production in the underlying water column and its potential emissions into the overlying atmosphere were quantified through sensitivity experiments. To extend the study domain to the pan-Arctic, I implemented the sea-ice ecosystem and the coupled sea ice-pelagic DMS cycling components of the 1-D column model into a three-dimensional (3-D) regional modelling framework. A multi-decadal model simulation was performed over the period 1969-2015 using realistic atmospheric forcing and lateral boundary conditions. The results of the simulation were evaluated by direct comparisons with available data products and reported values based on field and satellite measurements and other model simulations. The decline of Arctic sea ice was successfully simulated by the model. The magnitude of the pan-Arctic sea-ice and pelagic annual primary production and their general spatial patterns were comparable to other model studies. The mean seasonal cycle and the spatial distribution of the model-based surface seawater DMS climatology within the pan-Arctic showed some similarities with in situ measurement- and satellite-based climatologies. However, at the same time, the comparison of the DMS climatologies was challenged by the bias in the measurement-based climatology, emphasizing the need to update this data product, which was created almost a decade ago, by incorporating data acquired during the recent field campaigns. The analysis of the modelled fluxes of DMS at the ice-sea and sea-air interfaces revealed different responses to the accelerated decline of sea ice over the recent decades (1996-2015). There was no trend in the pan-Arctic ice-to-sea DMS flux due to the counteracting effect of vertical thinning and horizontal shrinking of sea ice that drove ice algal production. In contrast, the pan-Arctic sea-to-air DMS flux showed a consistent increase (about 40 % over the last two decades) driven by the reduction of sea ice cover that promoted outgassing and biological productivity. This finding suggests that the climate warming in the Arctic causes an increase in DMS emissions, and encourages further exploration of the biological climate regulation in the Arctic. / Graduate

O objetivo desta dissertação é realizar e comparar a aplicação da modelagem dinâmica de sistemas (MDS) e do activity based costing (ABC) para mensurar os custos em manufatura celular. Nesse sentido, foi realizada uma simulação utilizando os conceitos de MDS para obter os custos de produção de quatro produtos, em um ambiente de manufatura celular, considerando o método ABC e a comparação desses valores com a técnica de custeio tradicional ou absorção. Quanto à metodologia de pesquisa, esse trabalho é de enfoque quantitativo no qual o tipo de pesquisa é exploratório sem estabelecimento de hipóteses, porém, guiada pelos seus objetivos. Os resultados obtidos demonstram que a aplicação do ABC juntamente com a MDS é muito satisfatória quando comparada com a técnica tradicional. Finalmente, a aplicação do ABC com a MDS pode ser utilizada eficientemente como um método alternativo para custeio em manufaturas celulares. / The aim of this dissertation is to apply and to compare the modeling system dynamics (MDS) and activity based costing (ABC) to measure the costs in cellular manufacture. Taking this into account, a simulation was accomplished using the concepts of MDS to obtain the costs of production of four products, in an environment of cellular manufacture, considering ABC method and the comparison of those values with the technique of traditional costing. As for the research methodology, this dissertation is of quantitative focus in which the research type is exploratory without establishment of hypotheses, however guided by their objectives. The obtained results demonstrate that the application of ABC together with MDS it is very satisfactory when compared with the traditional technique. In conclusion, it can be observed that the application of ABC with MDS can be used efficiently as an alternative method to costing in cellular manufacture.

Le choix d'un système de gestion de bases de données (SGBD) et de plateforme d'exécution pour le déploiement est une tâche primordiale pour la satisfaction des besoins non-fonctionnels(comme la performance temporelle et la consommation d'énergie). La difficulté de ce choix explique la multitude de tests pour évaluer la qualité des bases de données (BD) développées.Cette évaluation se base essentiellement sur l'utilisation des métriques associées aux besoins non fonctionnels. En effet, une mine de tests existe couvrant toutes les phases de cycle de vie de conception d'une BD. Les tests et leurs environnements sont généralement publiés dans des articles scientifiques ou dans des sites web dédiés comme le TPC (Transaction Processing Council).Par conséquent, cette thèse contribue à la capitalisation et l'exploitation des tests effectués afin de diminuer la complexité du processus de choix. En analysant finement les tests, nous remarquons que chaque test porte sur les jeux de données utilisés, la plateforme d'exécution, les besoins non fonctionnels, les requêtes, etc. Nous proposons une démarche de conceptualisation et de persistance de toutes .ces dimensions ainsi que les résultats de tests. Cette thèse a donné lieu aux trois contributions. (1) Une conceptualisation basée sur des modélisations descriptive,prescriptive et ontologique pour expliciter les différentes dimensions. (2) Le développement d'un entrepôt de tests multidimensionnel permettant de stocker les environnements de tests et leurs résultats. (3) Le développement d'une méthodologie de prise de décision basée sur un système de recommandation de SGBD et de plateformes. / Choosing appropriate database management systems (DBMS) and/or execution platforms for given database (DB) is complex and tends to be time- and effort-intensive since this choice has an important impact on the satisfaction of non-functional requirements (e.g., temporal performance or energy consumption). lndeed, a large number of tests have been performed for assessing the quality of developed DB. This assessment often involves metrics associated with non-functional requirement. That leads to a mine of tests covering all life-cycle phases of the DB's design. Tests and their environments are usually published in scientific articles or specific websites such as Transaction Processing Council (TPC). Therefore, this thesis bas taken a special interest to the capitalization and the reutilization of performed tests to reduce and mastery the complexity of the DBMS/platforms selection process. By analyzing the test accurately, we identify that tests concem: the data set, the execution platform, the addressed non-functional requirements, the used queries, etc. Thus, we propose an approach of conceptualization and persistence of all dimensions as well as the results of tests. Conseguently, this thesis leads to the following contributions. (1) The design model based on descriptive, prescriptive and ontological concepts to raise the different dimensions. (2) The development of a multidimensional repository to store the test environments and their results. (3) The development of a decision making methodology based on a recommender system for DBMS and platforms selection.

Denhär rapporten är en fristående del inom ett samproduktionsprojekt mellan flerafristående parter. Studien är genomförd som en experimentell fallstudie med ettmetodiskt angreppssätt på en projektgrupp. Syftet med rapporten har varit attutröna och belysa problemen och möjligheterna vid införandet av ettdokumenthanteringssystem. Systemet i fråga är SharePoint som är ensamarbetsplattform för företag. Målgruppen är i första hand beslutsfattare ibegrepp att välja teknikstöd, men även forskare och studenter. Projektgruppenhar deltagare ifrån företag och högskola(Saab, Volvo PV, Autoliv och Chalmers)de använde bara fysiska möten och, e-mail vid dokumenthantering när studien startade.Avgränsningarna har varit att ingen värdering av dokuments innehåll har skett,inte heller har moduler och funktioner annat än de rörande dokument ochdokumenthantering behandlats. Studien har genomförts med enkätundersökning,observation och deltagandeobservation samt en granskning av artiklar inomämnet.  Slutsatser som drogs var att manbör se till att IT-avdelningen säkerställer att alla filer och program sombehövs uppdateras innan start. Att man minskar risken för ”information overload”och ökar enkelheten att publicera dokument samt förbättrar spårbarheten,tillgängligheten och versionshanteringen vid ett införande av ettDMS(SharePoint). / This report is an independent part of a co-productionproject between several independent parties. The studywas conducted as an experimental case study with a methodical approach on aproject group. The report has been about explore and illuminate the problemsand possibilities a introduction of a document management system will have andleads to. The system is SharePoint and it’s a business collaboration platformfor enterprises. The target audience is primarily the decision makers who arein the process of selecting a technology support, but also researchers andstudents. The project has participants from businesses and college (Saab, VolvoCars, Autoliv and Chalmers) when the study started the project group was usingonly the physical meetings and e-mail to distribute the documents. Theboundaries have been that no valuation of the document's content has occurred,nor have the modules and functions other than those related to documents anddocument management. The study was conducted by questionnaire, observation andparticipant observation and a review of several articles on the subject.Conclusions were that for start the IT department ensures that all files andprograms needed for the environment has been updated before first try. It’s away of reducing the risk of 'information overload' and increasing the ease ofpublishing documents, and improves traceability, availability and versioning ofdocuments with an introduction of a DMS (SharePoint).