Nextjet anser att de har ett ofördelaktigt beställnings- och lagerhållningssystem av reservdelar, och mest problem är det med o-ringarna och skruvarna. Beställning sker oftast först när ett behov uppstår vilket ibland kan leda till att plan blir stående och därmed att potentiella intäkter uteblir. I denna studie har en lagerstyrningsstrategi framställts för o-ringarna och skruvarna i Nextjets reservdelslager. Under studiens gång genomfördes en artikelklassificering av o-ringarna och skruvarna på grund av att många av artiklarna hade en liknande karaktäristik. En lagerstyrningsmetod har sedan upprättats för vardera grupp som uppstått. De metoder som använts var beställningspunkt, återfyllnadsnivå och lot-for-lot. Resultatet av lagerstyrningsstrategierna har lett till att både kapitalbindningen och lagernivåerna har minskat i jämfört med nuläget samtidigt som risken för brist har minskat drastiskt. Lagernivåerna minskar med drygt 1000 artiklar och den maximala kapitalbindningen minskar med nästan 100 000 SEK i jämförelse med vad den är i nuläget.

O objetivo que fundamenta esta dissertação é a investigação de práticas artísticas latinoamericanas vinculadas aos distintos usos do real nas criações contemporâneas. Com base na perspectiva de autores como Michel Foucault, Gilles Deleuze e Giorgio Agamben, o real é aqui abordado como dispositivo potencializador de experimentos indisciplinares. A pesquisa se dedica à análise dos projetos interdisciplinares do argentino Emilio García Wehbi, dos colombianos Heidi e Rolf Abderhalden, e do peruano Carlos Cueva. Através da poética destes criadores, pretende-se reconhecer as interlocuções entre tais práticas com os estudos teóricos sobre as presenças do real na arte contemporânea desenvolvidos por pesquisadores como José Antonio Sánchez, Maryvonne Saison e Hal Foster. Por meio deste repertório prático e teórico, busca-se averiguar as co-relações e as motivações que possibilitaram, em distintas linguagens, a tensão para a noção de representação a partir da apropriação das diferentes dimensões do real. Este percurso deseja problematizar em que medida a experiência com o real afeta o fenômeno teatral, e de que modo o experimento com a realidade, como ação ética e estética, reconfigura as vivências artísticas no contexto específico da América Latina. / The objective underlying this thesis is the investigation of related Latin American artistic practices in the different uses of the real in contemporary creations. From the perspective of authors such as Michel Foucault, Gilles Deleuze and Giorgio Agamben, the real is here approached as enhancer device of indisciplinares experiments. This research is devoted to the analysis of interdisciplinary projects from the Argentine Emilio García Wehbi, the Colombians Heidi and Rolf Abderhalden, and the Peruvian Carlos Cueva. Through the poetics of these creators, it is intended to recognize the dialogues between such practices with the theoretical studies of the presence of the real in contemporary art developed by researchers like José Antonio Sánchez, Maryvonne Saison and Hal Foster. Through this practical and theoretical repertoire, it is sought to ascertain the co-relationships and motivations that made it possible, in different languages, the tension to the notion of representation from the ownership of the different dimensions of the real. This path wants to discuss to what extent the experience with real affects the theatrical phenomenon, and how the experiment with reality, as ethics and aesthetics action, reconfigures the artistic experiences in the specific context of Latin America.

O objetivo que fundamenta esta dissertação é a investigação de práticas artísticas latinoamericanas vinculadas aos distintos usos do real nas criações contemporâneas. Com base na perspectiva de autores como Michel Foucault, Gilles Deleuze e Giorgio Agamben, o real é aqui abordado como dispositivo potencializador de experimentos indisciplinares. A pesquisa se dedica à análise dos projetos interdisciplinares do argentino Emilio García Wehbi, dos colombianos Heidi e Rolf Abderhalden, e do peruano Carlos Cueva. Através da poética destes criadores, pretende-se reconhecer as interlocuções entre tais práticas com os estudos teóricos sobre as presenças do real na arte contemporânea desenvolvidos por pesquisadores como José Antonio Sánchez, Maryvonne Saison e Hal Foster. Por meio deste repertório prático e teórico, busca-se averiguar as co-relações e as motivações que possibilitaram, em distintas linguagens, a tensão para a noção de representação a partir da apropriação das diferentes dimensões do real. Este percurso deseja problematizar em que medida a experiência com o real afeta o fenômeno teatral, e de que modo o experimento com a realidade, como ação ética e estética, reconfigura as vivências artísticas no contexto específico da América Latina. / The objective underlying this thesis is the investigation of related Latin American artistic practices in the different uses of the real in contemporary creations. From the perspective of authors such as Michel Foucault, Gilles Deleuze and Giorgio Agamben, the real is here approached as enhancer device of indisciplinares experiments. This research is devoted to the analysis of interdisciplinary projects from the Argentine Emilio García Wehbi, the Colombians Heidi and Rolf Abderhalden, and the Peruvian Carlos Cueva. Through the poetics of these creators, it is intended to recognize the dialogues between such practices with the theoretical studies of the presence of the real in contemporary art developed by researchers like José Antonio Sánchez, Maryvonne Saison and Hal Foster. Through this practical and theoretical repertoire, it is sought to ascertain the co-relationships and motivations that made it possible, in different languages, the tension to the notion of representation from the ownership of the different dimensions of the real. This path wants to discuss to what extent the experience with real affects the theatrical phenomenon, and how the experiment with reality, as ethics and aesthetics action, reconfigures the artistic experiences in the specific context of Latin America.

Dans cette thèse, nous étudions deux problèmes de planification de production motivés par des applications du monde réel. Tout d'abord, un problème de planification de production pour un projet de fabrication de vêtements est étudié et un outil d'optimisation est développé pour le résoudre. Deuxièmement, une version restreinte du problème de dimensionnement du lot de capacité avec des configurations dépendantes de la séquence est explorée. Diverses formulations mathématiques sont développées et une analyse de complexité est effectuée pour donner une première analyse du problème. / In this thesis, we study two production planning problems motivated by challenging real-world applications. First, a production planning problem for an apparel manufacturing project is studied and an optimization tool is developed to tackle it. Second, a restricted version of the capacitated lot sizing problem with sequence dependent setups is explored. Various mathematical formulations are developed and complexity analysis is performed to offer a first glance to the problem.

This research is concerned with the development of efficient solutions to various problems that arise in the flow-shop environments which utilize lot-streaming. Lot streaming is a commonly used process of splitting production lots into sublots and, then, of scheduling the sublots in an overlapping fashion on the machines, so as to expedite the progress of orders in production and to improve the overall performance of the production system. The different lot-streaming problems that arise in various flow-shop environments have been divided into two categories, single-lot problems and multiple-lot problems. Further classification of the multiple-lot problems into the lot streaming sequencing problem (LSSP) and the flow-shop lot-streaming (FSLS) problem is made in this work. This classification is motivated by the occurrence of these problems in the industry. Several variants of these problems are addressed in this research. In agreement with numerous practical applications, we assume sublots of equal sizes. It turns out that this restriction paves the way to the relaxation of several typical limitations of current lot-streaming models, such as assumption of negligible transfer and setup times or consideration of only the makespan criterion. For the single-lot problem, a goal programming (GP) approach is utilized to solve the problem for a unified cost objective function comprising of the makespan, the mean flow time, the average work-in-process (WIP), and the setup and handling related costs. A very fast optimal solution algorithm is proposed for finding the optimal number of sublots (and, consequently, the sublot size) for this unified cost objective function in a general m-machine flow shop. For the more complicated multiple-lot problem, a near-optimal heuristic for the solution of the LSSP is developed. This proposed heuristic procedure, referred to as the Bottleneck Minimal Idleness (BMI) heuristic, identifies and employs certain properties of the problem that are irregular in traditional flow-shop problems, particularly the fact that the sublot sizes eminating from the same lot type and their processing times (on the same machines) are identical. The BMI heuristic attempts to maximize the time buffer prior to the bottleneck machine, thereby minimizing potential bottleneck idleness, while also looking-ahead to sequence the lots with large remaining process time earlier in the schedule. A detailed experimental study is performed to show that the BMI heuristic outperforms the Fast Insertion Heuristic (the best known heuristic for flow-shop scheduling), when modified for Lot Streaming (FIHLS) and applied to the problem on hand. For the FSLS problem, several algorithms are developed. For the two-machine FSLS problem with an identical sublot-size for all the lots, an optimal pseudo-polynomial solution algorithm is proposed. For all practical purposes (i.e., even for very large lot sizes), this algorithm is very fast. For the case in which the sublot-sizes are lot-based, optimal and heuristic procedures are developed. The heuristic procedure is developed to reduce the complexity of the optimal solution algorithm. It consists of a construction phase and an improvement phase. In the construction phase, it attempts to find a near-optimal sequence for the lots and then, in the improvement phase, given the sequence, it attempts to optimize the lot-based sublot-sizes of each of the lots. Extensions of the solution procedures are proposed for the general m-machine FSLS problem. A comprehensive simulation study of a flow shop system under lot streaming is conducted to support the validity of the results and to demonstrate the effectiveness of the heuristic procedures. This study clearly indicates that, even in dynamic practical situations, the BMI rule, which is based on the proposed BMI heuristic, outperforms existing WIP rules, commonly used in industry, in scheduling a flow-shop that utilizes lot streaming. With respect to the primary performance measure - cycle time (or MFT) - the BMI rule demonstrates a clear improvement over other WIP rules. It is further shown that it also outperforms other WIP rules with respect to the output variability measure, another important measure in flow-shop systems. The effects of several other factors, namely system randomness, system loading, and bottleneck-related (location and number), in a flow-shop under lot streaming, are also reported. / Ph. D.

Les travaux de cette thèse s'inscrivent dans le contexte de la coordination des décisions de planification survenant dans une chaîne logistique à deux acteurs: un fournisseur et un producteur souhaitant chacun diminuer leur propre coût. Les décisions de planification prises de manière indépendante par chaque acteur peuvent amener à une mauvaise performance de la chaîne logistique en terme de coûts, d'où la nécessité d'une coordination. Nous étudions des mécanismes de partage de coûts entre des acteurs en définissant des stratégies de coordination entre les acteurs par la mise en place de contrats. Nous considérons le cas où le producteur (resp. fournisseur) peut imposer son plan de production optimal au fournisseur (resp. distributeur). Différentes hypothèses de partage de coûts, ainsi que la problématique d'asymétrie d'information sont prises en compte dans ces travaux. Nous effectuons également des analyses expérimentales mesurant la diminution du coût de la chaîne logistique obtenue quand les acteurs coopèrent. Ce contexte nous amène à étudier de nouveaux problèmes de lot-sizing pour lesquels nous proposons une analyse de complexité et des algorithmes de programmation dynamique pour les résoudre. Nous proposons également une étude théorique des problèmes de lot-sizing à deux niveaux avec une capacité de stockage limitée. / This thesis focus on the coordination of planning decisions in a two-level supply chain composed of one supplier and one retailer. Each actor wants to minimize his own cost. The planning decisions independently took by the actors can lead to a poor performance in terms of costs, hence the necessity of coordination. We study cost sharing mechanisms between the actors by designing contracts. In this work, we consider the case where the retailer (resp. supplier) can impose his optimal production plan to the supplier (resp. retailer). Different cost sharing hypothesis, as well as the asymmetric information problem are taking into account in this thesis. We also perform an experimental analysis in order to evaluate the decrease of the supply chain cost obtained when the actors cooperate. This context leads us to study new lot-sizing problems for which we propose a complexity analysis and dynamic programming algorithms in order to solve them. We also propose a theoritical study of two-level lot-sizing problems with inventory bounds.

As the Army transitions to the Army Force Generation (ARFORGEN) deployment cycle, it must adjust its many operations in support of ARFORGEN. Specifically, the Initial Military Training (IMT) must be able to adjust the scheduling of its classes for newly enlisted service members to finish training such that they fulfill Brigade Combat Team (BCT) requirements within their common due windows. We formulate this problem as a lot streaming problem. Lot streaming splits a batch of jobs into sublots,which are then processed over the machines in an overlapping fashion. To schedule classes for the IMT, there are two stages that must be coordinated: Basic Training (BT) and Advanced Individual Training (AIT). For the Army Force Generation problem, the classes are considered as sublots that are streamed from one stage to the next. For this process, the model formulation must address determination of class sizes and scheduling of soldiers and classes at the two stages such that (1) the start times of the soldiers at Stage 2 are greater than their completion times at Stage 1, and (2) the assignment of requisite number of soldiers is made to each BCT, so as to minimize the total flow time. We propose a decomposition-based approach for the solution of this problem. In an effort to decompose the problem, the original lot streaming problem is reformulated such that the master problem selects an optimal combination of schedules for training classes and assigning soldiers to BCTs. A complete schedule selected in the master problem includes the assignments of soldiers to classes in BT, AIT, and their assignments to the BCTs, so as to minimize the total flow time as well as earliness and tardiness for regular Army units. Earliness and Tardiness are defined as the length of the time a soldier waits before and after the due date, respectively, of the BCT to which he or she is assigned. Our decomposition-based method enables solution of larger problem instances without running out of memory, and it affords CPU time reductions when compared with the CPU times required for these problem instances obtained via direct application of CPLEX 12.1. Our investigation into the structure of the problem has enabled further improvement of the proposed decomposition-based method. This improvement is achieved because of a result, which we show, that the first and second-stage scheduling problems need not be solved as one combined subproblem, but rather, they can be solved sequentially, the first stage problem followed by the second stage problem. The combination of Stage 1 and Stage 2 problems as one subproblem creates several additional enumerations of possible schedules the model must generate. By reducing this number of enumerations, the computational effort involved in solving the model reduces significantly, thereby allowing reductions in CPU time. In the Sequential approach, the completion times of soldiers determined at Stage 1 are passed to Stage 2 as bounds on their completion times at Stage 2. We prove that solving the combined subproblem sequentially as two subproblems is optimal when the first stage has no limit on the batch size and the ready times of the soldiers at Stage 1 are the same. For the Army Force Generation problem, we use unequal ready times, and therefore, solving the scheduling problems for the first two stages as sequential subproblems can lead to suboptimal solutions. Our experimental investigation shows efficacy of solving larger-sized problem instances with this method. We also recommend various potential additions to improve the Sequential approach for application to the overall Army problem. We have also demonstrated the use of our methodology to a real-life problem instance. Our methodology results in schedules for IMT with an estimated 28% reduction in mean flow time for soldiers over what is currently experienced in practice. We apply this Sequential approach to various extensions of the problem on hand that pertain to hybrid flow shop and agile manufacturing environments. Results of our computational investigation show the effectiveness of using the Sequential approach over direct solution by CPLEX from the viewpoint of both optimality gap and the CPU time required. In particular, we consider two different model configurations for a hybrid flow shop and three different model configurations for an agile manufacturing facility. / Ph. D.

L’objectif de ce travail était de tester l’utilisation des radioisotopes naturels à courte période (234Th, 7Be et 210Pb) comme traceurs des transferts des particules dans le bassin versant de la Garonne-Dordogne-Gironde. Dans un premier temps, la faisabilité de la méthode basée sur le 234Th a été testée dans les rivières. Les résultats ont montré qu’une valeur de 5 mBq l-1 correspondant au seuil en 238UD est nécessaire pour l’application du 234Th en rivière. Dans un deuxième temps, le suivi sur deux années (2006-2007) des radioéléments naturels, 234Th, 7Be et 210Pb, et artificiels, 137Cs et 131I, dans le Lot, la Garonne et l’estuaire de la Gironde, a permis de distinguer les différentes étapes du transport des particules en relation avec l’hydrologie. L’atout de l’utilisation de ces traceurs est d’accéder à de premières estimations du temps de résidence des sédiments et du pourcentage des fractions anciennes et récentes. Dans le Lot et la Garonne, il existe une rétention des particules (2-89 jours) pendant l’étiage et les débits moyens, et de fortes remises en suspension des sédiments anciens à débits élevés. La moyenne du pourcentage des sédiments récents dans les rivières est d’environ 25 %, ce qui montre que les matériaux en suspension (MES) dans les rivières sont dominés par des sédiments anciens. Dans l’estuaire de la Gironde, le temps de résidence varie en fonction de l’hydrologie des rivières : pendant les périodes de forts débits, le temps de transit des particules de la Réole jusqu’à l’océan est seulement de quelque mois (~150 jours) ; alors que pendant les périodes d’étiage, l’âge des sédiments augmente dans la zone de turbidité maximum atteignant jusqu’à 400 jours. / The main objective of this study was to develop short-lived radioisotopes (234Th, 7Be and 210Pb) as tracers of particle transport in the Garonne-Dordogne-Gironde watershed. Firstly, the possibility to use 234Th/238U pair to study particle residence time in the Gironde fluvial-estuarine system was tested. The results show that dissolved 238U should be greater than 5 mBq l-1 to permit this application in fluvial systems. Secondly, the two years monitoring of natural radioisotopes, 234Th, 7Be and 210Pb, and artificial radioisotopes, 137Cs and 131I, in the Garonne and Lot rivers and in the Gironde Estuary, had allowed to observe the dynamic of particle transport, linked to the river flow. Based on this database, preliminary particle residence times and percentages of the new and old sediments were estimated. In the Lot and Garonne rivers, the particle retention ranges between 2-89 days during low and mean river discharges. The percentage of the new sediments is average 25 %, which indicates that the old resuspended sediments are dominated the suspended particulate matters (SPM). In the Gironde estuary, the particle residence time is mainly controlled by river discharge. The particle residence time during low river discharge is about 400 days. When the river discharge is increasing, the freshwaters are predominant in the estuary, the maximum turbidity zone (TMZ) is dispersed and the old sediments transported toward the ocean. During this period the particle residence time is only few months.

In previous editions of the magical papyri, PGM 50 has been considered as a lot oracle. In this article we propose a reinterpretation of the text as a source for astrology rather than for lot oracles. This reinterpretation is based on PGM 50’s astrological vocabulary. We provide a new translation based on this evidence. We further discover parallels to the second-century C.E. astrologer Vettius Valens in the verso of the text, which emend the original text as given by Wessely and Preisendanz. / In früheren Editionen der magischen Papyri wurde PGM 50 als Losorakel angesehen. In diesem Artikel argumentieren wir jedoch, den Text eher als einen Vertreter der Astrologie denn als ein Losorakel aufzufassen. Diese Neuinterpretation beruht auf dem astrologischen Fachvokabular, das in PGM 50 Anwendung fi ndet. Neben einer Neuübersetzung, basierend auf diesen Erkenntnissen, war es möglich, auf dem Verso des Pergaments Parallelen zum Werk von Vettius Valens (2. Jh. n. Chr.) zu identifi zieren. Dadurch kann die Erstedition von Wessely und die Textausgabe bei Preisendanz emendiert werden.

Cette thèse développe des méthodes d'optimisation pour la gestion de la Supply Chain et a pour thème central la flexibilité définie comme la capacité à fournir un service ou un produit au consommateur dans un environnement incertain. La recherche a été menée dans le cadre d'un partenariat entre Argon Consulting, une société indépendante de conseil en Supply Chain et l'École des Ponts ParisTech. Dans cette thèse, nous développons trois sujets rencontrés par Argon Consulting et ses clients et qui correspondent à trois différents niveaux de décision (long terme, moyen terme et court terme).Lorsque les entreprises élargissent leur portefeuille de produits, elles doivent décider dans quelles usines produire chaque article. Il s'agit d'une décision à long terme, car une fois qu'elle est prise, elle ne peut être facilement modifiée. Plus qu'un problème d'affectation où un article est produit par une seule usine, ce problème consiste à décider si certains articles doivent être produits par plusieurs usines et par lesquelles. Cette interrogation est motivée par la grande incertitude de la demande. En effet, pour satisfaire la demande, l'affectation doit pouvoir équilibrer la charge de travail entre les usines. Nous appelons ce problème le multi-sourcing de la production. Comme il ne s'agit pas d'un problème récurrent, il est essentiel de tenir compte du risque au moment de décider le niveau de multi-sourcing. Nous proposons un modèle générique qui inclut les contraintes techniques du problème et une contrainte d'aversion au risque basée sur des mesures de risque issues de la théorie financière. Nous développons un algorithme et une heuristique basés sur les outils standards de la Recherche Opérationnelle et de l'Optimisation Stochastique pour résoudre le problème du multi-sourcing et nous testons leur efficacité sur des données réelles.Avant de planifier la production, certains indicateurs macroscopiques doivent être décidés à horizon moyen terme tels la quantité de matières premières à commander ou la taille des lots produits. Certaines entreprises utilisent des modèles de stock en temps continu, mais ces modèles reposent souvent sur un compromis entre les coûts de stock et les coûts de lancement. Ces derniers sont des coûts fixes payés au lancement de la production et sont difficiles à estimer en pratique. En revanche, à horizon moyen terme, la flexibilité des moyens de production est déjà fixée et les entreprises estiment facilement le nombre maximal de lancements. Poussés par cette observation, nous proposons des extensions de certains modèles classiques de stock en temps continu, sans coût de lancement et avec une limite sur le nombre d'installations. Nous avons utilisé les outils standard de l'Optimisation Continue pour calculer les indicateurs macroscopiques optimaux.Enfin, la planification de la production est une décision à court terme qui consiste à décider quels articles doivent être produits par la ligne de production pendant la période en cours. Ce problème appartient à la classe bien étudiée des problèmes de Lot-Sizing. Comme pour les décisions à moyen terme, ces problèmes reposent souvent sur un compromis entre les coûts de stock et les coûts de lancement. Fondant notre modèle sur ces considérations industrielles, nous gardons le même point de vue (aucun coût de lancement et une borne supérieure sur le nombre de lancement) et proposons un nouveau modèle.Bien qu'il s'agisse de décisions à court terme, les décisions de production doivent tenir compte de la demande future, qui demeure incertaine. Nous résolvons notre problème de planification de la production à l'aide d'outils standard de Recherche Opérationnelle et d'Optimisation Stochastique, nous testons l'efficacité sur des données réelles et nous la comparons aux heuristiques utilisées par les clients d'Argon Consulting / This thesis develops optimization methods for Supply Chain Management and is focused on the flexibility defined as the ability to deliver a service or a product to a costumer in an uncertain environment. The research was conducted throughout a partnership between Argon Consulting, which is an independent consulting firm in Supply Chain Operations and the École des Ponts ParisTech. In this thesis, we explore three topics that are encountered by Argon Consulting and its clients and that correspond to three different levels of decision (long-term, mid-term and short-term).When companies expand their product portfolio, they must decide in which plants to produce each item. This is a long-term decision since once it is decided, it cannot be easily changed. More than a assignment problem where one item is produced by a single plant, this problem consists in deciding if some items should be produced on several plants and by which plants. This is motivated by a highly uncertain demand. So, in order to satisfy the demand, the assignment must be able to balance the workload between plants. We call this problem the multi-sourcing of production. Since it is not a repeated problem, it is essential to take into account the risk when making the multi-sourcing decision. We propose a generic model that includes the technical constraints of the assignment and a risk-averse constraint based on risk measures from financial theory. We develop an algorithm and a heuristic based on standard tools from Operations Research and Stochastic Optimization to solve the multi-sourcing problem and we test their efficiency on real datasets.Before planning the production, some macroscopic indicators must be decided at mid-term level such as the quantity of raw materials to order or the size of produced lots. Continuous-time inventory models are used by some companies but these models often rely on a trade-off between holding costs and setups costs. These latters are fixed costs paid when production is launched and are hard to estimate in practice. On the other hand, at mid-term level, flexibility of the means of production is already fixed and companies easily estimate the maximal number of setups. Motivated by this observation, we propose extensions of some classical continuous-time inventory models with no setup costs and with a bound on the number of setups. We used standard tools from Continuous Optimization to compute the optimal macroscopic indicators.Finally, planning the production is a short-term decision consisting in deciding which items must be produced by the assembly line during the current period. This problem belongs to the well-studied class of Lot-Sizing Problems. As for mid-term decisions, these problems often rely on a trade-off between holding and setup costs. Basing our model on industrial considerations, we keep the same point of view (no setup cost and a bound on the number of setups) and propose a new model. Although these are short-term decisions, production decisions must take future demand into account, which remains uncertain. We solve our production planning problem using standard tools from Operations Research and Stochastic Optimization, test the efficiency on real datasets, and compare it to heuristics used by Argon Consulting's clients