Desenvolvimento de um jogo de simulação do sistema de produção Lean ferramentas: balanceamento da linha, VSM e SMED

Uma grande parte do tempo de uma organização é despendida em atividades que não criam qualquer tipo de valor. Este tipo de atividades são consideradas como desperdícios, pois consomem recursos e tempo, como é o caso de deslocações, controlos, ajustes, armazenamento de materiais, resolução de problemas, entre tantos outros, levando a um elevado custo dos produtos disponibilizados. Em 1996 a designação de Lean Thinking foi usada, pela primeira vez, por Womack e Jones, onde é falada como uma filosofia de gestão, que tem como principal objetivo reduzir os desperdícios num processo produtivo. Reduzindo os desperdícios aumenta-se a qualidade e diminui-se os tempos de processamento e, consequentemente, os custos de produção. É nesta base que assenta o documento aqui presente, que tem o objetivo de criar e desenvolver um jogo de simulação onde seja possível aplicar várias ferramentas Lean. O jogo de simulação é uma continuação de uma pesquisa e estudo teórico de um aluno de erasmus e faz parte de um projeto internacional do Lean Learning Academy (LLA). Criou-se um processo produtivo de montagem de canetas que fosse o mais semelhante ao que se encontram nas empresas, com todos os acessórios para o pleno funcionamento da simulação, como é o caso de instruções de montagem, procedimentos de controlo e ordens de produção, para assim posteriormente ser possível analisar os dados e as dificuldades encontradas, de modo a aplicar-se as ferramentas Lean. Apesar de serem abordadas várias ferramentas Lean neste trabalho, foram trabalhadas mais detalhadamente as seguintes: - Value Stream Mapping (VSM); - Single Minute Exchange of Dies (SMED); - Balanceamento da linha. De modo a ser percetível o conteúdo e as vantagens das três ferramentas Lean mencionadas no trabalho, estas foram aplicadas e simuladas, de forma a existir uma componente prática no seu estudo, para mais fácil compreensão e rápida aprendizagem.

Zinc oxide as an ozone sensor

Journal of Applied Physics, Vol. 96, nº3

An overview of the higher level classification of Pucciniomycotina based on combined analyses of nuclear large and small subunit rDNA sequences

Mycologia, Vol. 98, nº6

Cálculo mental – um estudo sobre as estratégias utilizadas por alunos do 3.º ano na adição e subtração

Relatório de Estágio apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino do 1.º e do 2.º Ciclo do Ensino Básico

Fractional central differences and derivatives

Journal of Vibration and Control, 14(9–10): 1255–1266, 2008

Laser-induced diffusion decomposition in Fe-V thin-film alloys

We investigate the origin of ferromagnetism induced in thin-film (similar to 20 nm) Fe-V alloys by their irradiation with subpicosecond laser pulses. We find with Rutherford backscattering that the magnetic modifications follow a thermally stimulated process of diffusion decomposition, with formation of a-few-nm-thick Fe enriched layer inside the film. Surprisingly, similar transformations in the samples were also found after their long-time (similar to 10(3) s) thermal annealing. However, the laser action provides much higher diffusion coefficients (similar to 4 orders of magnitude) than those obtained under standard heat treatments. We get a hint that this ultrafast diffusion decomposition occurs in the metallic glassy state achievable in laser-quenched samples. This vitrification is thought to be a prerequisite for the laser-induced onset of ferromagnetism that we observe. 2014 Elsevier B.V. All rights reserved.

Task assignment algorithms for two-type heterogeneous multiprocessors

Consider the problem of assigning implicit-deadline sporadic tasks on a heterogeneous multiprocessor platform comprising two different types of processors—such a platform is referred to as two-type platform. We present two low degree polynomial time-complexity algorithms, SA and SA-P, each providing the following guarantee. For a given two-type platform and a task set, if there exists a task assignment such that tasks can be scheduled to meet deadlines by allowing them to migrate only between processors of the same type (intra-migrative), then (i) using SA, it is guaranteed to find such an assignment where the same restriction on task migration applies but given a platform in which processors are 1+α/2 times faster and (ii) SA-P succeeds in finding a task assignment where tasks are not allowed to migrate between processors (non-migrative) but given a platform in which processors are 1+α times faster. The parameter 0<α≤1 is a property of the task set; it is the maximum of all the task utilizations that are no greater than 1. We evaluate average-case performance of both the algorithms by generating task sets randomly and measuring how much faster processors the algorithms need (which is upper bounded by 1+α/2 for SA and 1+α for SA-P) in order to output a feasible task assignment (intra-migrative for SA and non-migrative for SA-P). In our evaluations, for the vast majority of task sets, these algorithms require significantly smaller processor speedup than indicated by their theoretical bounds. Finally, we consider a special case where no task utilization in the given task set can exceed one and for this case, we (re-)prove the performance guarantees of SA and SA-P. We show, for both of the algorithms, that changing the adversary from intra-migrative to a more powerful one, namely fully-migrative, in which tasks can migrate between processors of any type, does not deteriorate the performance guarantees. For this special case, we compare the average-case performance of SA-P and a state-of-the-art algorithm by generating task sets randomly. In our evaluations, SA-P outperforms the state-of-the-art by requiring much smaller processor speedup and by running orders of magnitude faster.

On derivatives and norms of generalized matrix functions and respective symmetric powers

In recent papers, the authors obtained formulas for directional derivatives of all orders, of the immanant and of the m-th xi-symmetric tensor power of an operator and a matrix, when xi is a character of the full symmetric group. The operator norm of these derivatives was also calculated. In this paper, similar results are established for generalized matrix functions and for every symmetric tensor power.

Orbital forcing of stratal patterns in an inner platform carbonate sucession: an example from an Upper Hauterivian series of the Lusitanian Basin, Portugal

With an example taken from a late-Hauterivian series of the Lusitanian Basin (Portugal), we will demonstrate the sedimentary record of orbital pattern variations and, consequently, climate variations in an inner platform environment with patterns and isolation changes, allows us to establish 4 major orders of periodicity related to orbital components:- The large cycles ob bed thickness variation, constituted by 31-32 beds, recording the 400 ky eccentricity cycle component;- The medium cycles, represented by byndles of 8-9 beds, related to the 100 ky eccentricity cycle component; - The small cycles, of 3-5 beds, recording the 41 ky obliquity components;- The very small cycles, of 2 beds, related to the 22 ky and 26 ky precession components. The mean duration of each bed is around 11.8 ky, a number very close to that of the precession hemi-cycle. Climatic control on qualitative production is confirmed by the close relation between the bed thickness variations, the insolation variability and the variation of micritized elements concentrations.

Otimização da atividade de picking num armazém de peças – um caso de estudo

Mestrado em Engenharia Mecânica – Gestão Industrial

Aplicação do multi-layer stream mapping para a gestão da eficiência de recursos e produtividade de um sistema de produção

Mestrado em Engenharia Mecânica – Especialização Gestão Industrial

Vertex component analysis: a geometric-based approach to unmix hyperspectral data

Hyperspectral remote sensing exploits the electromagnetic scattering patterns of the different materials at specific wavelengths [2, 3]. Hyperspectral sensors have been developed to sample the scattered portion of the electromagnetic spectrum extending from the visible region through the near-infrared and mid-infrared, in hundreds of narrow contiguous bands [4, 5]. The number and variety of potential civilian and military applications of hyperspectral remote sensing is enormous [6, 7]. Very often, the resolution cell corresponding to a single pixel in an image contains several substances (endmembers) [4]. In this situation, the scattered energy is a mixing of the endmember spectra. A challenging task underlying many hyperspectral imagery applications is then decomposing a mixed pixel into a collection of reflectance spectra, called endmember signatures, and the corresponding abundance fractions [8–10]. Depending on the mixing scales at each pixel, the observed mixture is either linear or nonlinear [11, 12]. Linear mixing model holds approximately when the mixing scale is macroscopic [13] and there is negligible interaction among distinct endmembers [3, 14]. If, however, the mixing scale is microscopic (or intimate mixtures) [15, 16] and the incident solar radiation is scattered by the scene through multiple bounces involving several endmembers [17], the linear model is no longer accurate. Linear spectral unmixing has been intensively researched in the last years [9, 10, 12, 18–21]. It considers that a mixed pixel is a linear combination of endmember signatures weighted by the correspondent abundance fractions. Under this model, and assuming that the number of substances and their reflectance spectra are known, hyperspectral unmixing is a linear problem for which many solutions have been proposed (e.g., maximum likelihood estimation [8], spectral signature matching [22], spectral angle mapper [23], subspace projection methods [24,25], and constrained least squares [26]). In most cases, the number of substances and their reflectances are not known and, then, hyperspectral unmixing falls into the class of blind source separation problems [27]. Independent component analysis (ICA) has recently been proposed as a tool to blindly unmix hyperspectral data [28–31]. ICA is based on the assumption of mutually independent sources (abundance fractions), which is not the case of hyperspectral data, since the sum of abundance fractions is constant, implying statistical dependence among them. This dependence compromises ICA applicability to hyperspectral images as shown in Refs. [21, 32]. In fact, ICA finds the endmember signatures by multiplying the spectral vectors with an unmixing matrix, which minimizes the mutual information among sources. If sources are independent, ICA provides the correct unmixing, since the minimum of the mutual information is obtained only when sources are independent. This is no longer true for dependent abundance fractions. Nevertheless, some endmembers may be approximately unmixed. These aspects are addressed in Ref. [33]. Under the linear mixing model, the observations from a scene are in a simplex whose vertices correspond to the endmembers. Several approaches [34–36] have exploited this geometric feature of hyperspectral mixtures [35]. Minimum volume transform (MVT) algorithm [36] determines the simplex of minimum volume containing the data. The method presented in Ref. [37] is also of MVT type but, by introducing the notion of bundles, it takes into account the endmember variability usually present in hyperspectral mixtures. The MVT type approaches are complex from the computational point of view. Usually, these algorithms find in the first place the convex hull defined by the observed data and then fit a minimum volume simplex to it. For example, the gift wrapping algorithm [38] computes the convex hull of n data points in a d-dimensional space with a computational complexity of O(nbd=2cþ1), where bxc is the highest integer lower or equal than x and n is the number of samples. The complexity of the method presented in Ref. [37] is even higher, since the temperature of the simulated annealing algorithm used shall follow a log( ) law [39] to assure convergence (in probability) to the desired solution. Aiming at a lower computational complexity, some algorithms such as the pixel purity index (PPI) [35] and the N-FINDR [40] still find the minimum volume simplex containing the data cloud, but they assume the presence of at least one pure pixel of each endmember in the data. This is a strong requisite that may not hold in some data sets. In any case, these algorithms find the set of most pure pixels in the data. PPI algorithm uses the minimum noise fraction (MNF) [41] as a preprocessing step to reduce dimensionality and to improve the signal-to-noise ratio (SNR). The algorithm then projects every spectral vector onto skewers (large number of random vectors) [35, 42,43]. The points corresponding to extremes, for each skewer direction, are stored. A cumulative account records the number of times each pixel (i.e., a given spectral vector) is found to be an extreme. The pixels with the highest scores are the purest ones. N-FINDR algorithm [40] is based on the fact that in p spectral dimensions, the p-volume defined by a simplex formed by the purest pixels is larger than any other volume defined by any other combination of pixels. This algorithm finds the set of pixels defining the largest volume by inflating a simplex inside the data. ORA SIS [44, 45] is a hyperspectral framework developed by the U.S. Naval Research Laboratory consisting of several algorithms organized in six modules: exemplar selector, adaptative learner, demixer, knowledge base or spectral library, and spatial postrocessor. The first step consists in flat-fielding the spectra. Next, the exemplar selection module is used to select spectral vectors that best represent the smaller convex cone containing the data. The other pixels are rejected when the spectral angle distance (SAD) is less than a given thresh old. The procedure finds the basis for a subspace of a lower dimension using a modified Gram–Schmidt orthogonalizati on. The selected vectors are then projected onto this subspace and a simplex is found by an MV T pro cess. ORA SIS is oriented to real-time target detection from uncrewed air vehicles using hyperspectral data [46]. In this chapter we develop a new algorithm to unmix linear mixtures of endmember spectra. First, the algorithm determines the number of endmembers and the signal subspace using a newly developed concept [47, 48]. Second, the algorithm extracts the most pure pixels present in the data. Unlike other methods, this algorithm is completely automatic and unsupervised. To estimate the number of endmembers and the signal subspace in hyperspectral linear mixtures, the proposed scheme begins by estimating sign al and noise correlation matrices. The latter is based on multiple regression theory. The signal subspace is then identified by selectin g the set of signal eigenvalue s that best represents the data, in the least-square sense [48,49 ], we note, however, that VCA works with projected and with unprojected data. The extraction of the end members exploits two facts: (1) the endmembers are the vertices of a simplex and (2) the affine transformation of a simplex is also a simplex. As PPI and N-FIND R algorithms, VCA also assumes the presence of pure pixels in the data. The algorithm iteratively projects data on to a direction orthogonal to the subspace spanned by the endmembers already determined. The new end member signature corresponds to the extreme of the projection. The algorithm iterates until all end members are exhausted. VCA performs much better than PPI and better than or comparable to N-FI NDR; yet it has a computational complexity between on e and two orders of magnitude lower than N-FINDR. The chapter is structure d as follows. Section 19.2 describes the fundamentals of the proposed method. Section 19.3 and Section 19.4 evaluate the proposed algorithm using simulated and real data, respectively. Section 19.5 presents some concluding remarks.

Using interval graphs in an order processing optimization problem

In this paper we address an order processing optimization problem known as minimization of open stacks (MOSP). We present an integer pro gramming model, based on the existence of a perfect elimination scheme in interval graphs, which finds an optimal sequence for the costumers orders.

A mathematical model for supermarket order picking

Order picking consists in retrieving products from storage locations to satisfy independent orders from multiple customers. It is generally recognized as one of the most significant activities in a warehouse (Koster et al, 2007). In fact, order picking accounts up to 50% (Frazelle, 2001) or even 80% (Van den Berg, 1999) of the total warehouse operating costs. The critical issue in today’s business environment is to simultaneously reduce the cost and increase the speed of order picking. In this paper, we address the order picking process in one of the Portuguese largest companies in the grocery business. This problem was proposed at the 92nd European Study Group with Industry (ESGI92). In this setting, each operator steers a trolley on the shop floor in order to select items for multiple customers. The objective is to improve their grocery e-commerce and bring it up to the level of the best international practices. In particular, the company wants to improve the routing tasks in order to decrease distances. For this purpose, a mathematical model for a faster open shop picking was developed. In this paper, we describe the problem, our proposed solution as well as some preliminary results and conclusions.

Os reais hospitais militares em Portugal administrados e fundados pelos Irmãos Hospitaleiros de S. João de Deus 1640-1834

RESUMO: Desde 1640 até data extrema de 1834, os Irmãos Hospitaleiros de S. João de Deus foram os responsáveis, directa e indirectamente, pela administração e corpo de enfermagem dos Reais Hospitais Militares em Portugal, actividades que analisamos ao longo dos séculos, desenvolvendo pressupostos temáticos relativamente a sua actuação no tempo e no espaço. É durante o séc. XVII até ao séc. XIX, que vemos os cuidados da corte para com a assistência aos soldados enfermos e doentes, ao publicar inúmera legislação relativamente à complexidade assistencial na área militar, a qual foi por nós compilada para melhor contextualização da importância dos Hospitais Militares em Portugal. Os Regimentos, os Alvarás, os Regulamentos e as Ordens do Dia, constituem um objecto fundamental de pesquisa e análise para caracterizar o quotidiano nesses mesmos locais. Os Hospitais Militares desde a sua fundação, dos primórdios das Guerras da Aclamação em 1640, até ao advento do liberalismo em 1834, eram centros de conhecimento técnico e científico com um corpo assistencial especializado, onde um conjunto pluridisciplinar de profissionais zelava qualitativamente pelos assistidos, e onde os Irmãos Hospitaleiros de S. João de Deus desempenhavam funções de administradores, enfermeiros e capelães. Nesse sentido elaboramos uma listagem cronológica para inter relacionar os Irmãos Hospitaleiros e os Hospitais Militares, pois é impossível separar a Ordem de S. João de Deus da componente assistencial aos enfermos e doentes militares em Portugal. A importância urbana e arquitectónica, que os Reais Hospitais Militares tiveram no contexto orgânico e defensivo nas Praças de Guerra, é realçado pela forma como estes se encontravam implantados e construídos, demarcando-se esteticamente da globalidade edificada, pois constituíam parte integrante dos equipamentos militares, como era teorizado pelos técnicos militares. Assim analisamos a localização dos imóveis, para além do próprio edifício hospitalar, com o meio, ou seja com a urbanidade das Praças de guerra. A sobriedade arquitectónica dos Hospitais Militares, integrada nos grandes ciclos das correntes culturais europeia e nacional, associada à riqueza decorativa e iconoclasta desenvolvida nesses locais, dá-nos uma dimensão da importância científica que esses núcleos assistenciais tiveram, contribuindo para a difusão do culto e circulação da imaginária de S. João de Deus em Portugal e dos Santos venerados nos Hospitais Militares. Desta forma compreendemos o alicerçar devocional que o reino tinha por este Santo, como o fundador do conceito assistencial do hospital moderno. Estando intrinsecamente ligado a este facto vemos o proliferar do culto e da imaginária de S. João de Deus em Portugal, centrando-se a iconografia artística do Santo em torno das localidades onde se enraizaram os Hospitais Militares. Hoje, nos imóveis hospitalares, não é difícil analisar uma lenta evolução da funcionalidade dos seus espaços, gravitando o desenvolvimento estrutural assistencial em torno das enfermarias e salas de cirurgia, mantendo-se perene este arquétipo arquitectónico desde o séc. XVII até meados do séc. XIX, as quais foram levantadas, comparadas e analisadas. Foi com a exclaustração das Ordens Religiosas, pelo Decreto de 29 de Maio de 1834, que acabou a extraordinária e valorosa acção administrativa, tutelar e corpo de enfermagem dos Irmãos Hospitaleiros de S. João de Deus, na área específica da assistência militar em Portugal, extinguindo-se, nalguns casos, os Hospitais Militares, pois o reino não estava preparado para substituir esses profissionais de saúde. O nosso estudo desenvolve-se por cerca de 295 anos, espaço temporal em que os Hospitais Militares foram administrados e fundados pelos Irmãos de S. João de Deus em Portugal.---------ABSTRACT: Since 1640 until 1834 the Hospitaller Brothers of S. John of God were the responsibles, direct and indirectly, for the administration and nursing body of the Royal Military Hospitals in Portugal, activities that we analyse throughout the centuries, developing thematic presuppositions regarding its performance in time and in space. It is during the 17th century until the 19th century, that we see the court’s care with the assistance of the wounded and sick by the publishing of much legislation regarding the assistance complexity in the military area, which was compiled by us in order to achieve a better comprehension of the importance of the Military Hospitals in Portugal. The Regiments, Charters, Regulations and Orders of Day constitute a fundamental object of research and analysis to characterise the quotidian of these locations. The Military Hospitals, since its foundation, in the beginning of the Wars of Acclamation in 1640, until the advent of liberalism in 1834, were centres of technical and scientific knowledge with a specialized assistance body, were a multidisciplinary set of professionals took qualitatively care of the attended, and where the Hospitaller Brothers of S. John of God performed the tasks of administrators, nurses and chaplains. In this perspective, we created a chronological listing in order to relate the Hospitaller Brothers with the Military Hospitals, since it is impossible to separate the Hospitaller Order of S. John of God from the component of assistance to the military sick and wounded in Portugal. The urban and architectural importance that the Royal Military Hospitals had in the organic and defensive context of the War Fortifications is emphasized by the way these were implanted and built and by its architectural demarcation of the edified whole, since they constituted an integrant part of the military equipments, as it was theorized for the military architecture. Therefore we analyse the location of the real estate, analysing not only the hospital building itself, but also its relation with the environment, i. e. with the urbanism of the war fortifications. The architectural sobriety of Military Hospitals, integrated in the big cycles of cultural streams in Europe and Portugal, associated to the decorative and iconoclastic wealth developed in these locations, give us a dimension of the scientific importance that these hospitals had, contributing to the diffusion of the cult and circulation of sculptures and paintings of S. John of God in Portugal and of the Saints revered in the Hospitals. In this way, we understand the consolidation of the devotion that the kingdom had for this Saint, the founder of the assistance concept of the modern hospital. The proliferation of the cult and iconography of S. John of God is intrinsically connected to this fact, the artistic iconography concentrating itself around the localities were the Military Hospitals were built. Today, in the assistance buildings, it is not difficult to analyse a slow evolution of the functionality of its spaces, gravitating the structural assistance development around the infirmaries and surgery rooms, this architectural archetype being perennial from the 17th century until the middle of the 19th century. These infirmaries were pointed out, compared and analysed. It was the expulsion of the Religious Orders, by the Decree of May 29th 1834, that ended with the extraordinary and valorous administrative and tutelary action and nursing body of the Hospitaller Brothers of S. John of God, in the specific area of military assistance in Portugal, extinguishing, in some cases, the Military Hospitals, since the kingdom wasn’t prepared to substitute these health professionals. Our study is developed in a timeframe of 295 years, period in which the Military Hospitals were administrated and founded by the Brothers of S. John of God in Portugal.