Th. doct.-ing.--Méc. des fluides--Toulouse--I.N.P., 1980. N°: 109.

This research is motivated by the need for considering lot sizing while accepting customer orders in a make-to-order (MTO) environment, in which each customer order must be delivered by its due date. Job shop is the typical operation model used in an MTO operation, where the production planner must make three concurrent decisions; they are order selection, lot size, and job schedule. These decisions are usually treated separately in the literature and are mostly led to heuristic solutions. The first phase of the study is focused on a formal definition of the problem. Mathematical programming techniques are applied to modeling this problem in terms of its objective, decision variables, and constraints. A commercial solver, CPLEX is applied to solve the resulting mixed-integer linear programming model with small instances to validate the mathematical formulation. The computational result shows it is not practical for solving problems of industrial size, using a commercial solver. The second phase of this study is focused on development of an effective solution approach to this problem of large scale. The proposed solution approach is an iterative process involving three sequential decision steps of order selection, lot sizing, and lot scheduling. A range of simple sequencing rules are identified for each of the three sub-problems. Using computer simulation as the tool, an experiment is designed to evaluate their performance against a set of system parameters. For order selection, the proposed weighted most profit rule performs the best. The shifting bottleneck and the earliest operation finish time both are the best scheduling rules. For lot sizing, the proposed minimum cost increase heuristic, based on the Dixon-Silver method performs the best, when the demand-to-capacity ratio at the bottleneck machine is high. The proposed minimum cost heuristic, based on the Wagner-Whitin algorithm is the best lot-sizing heuristic for shops of a low demand-to-capacity ratio. The proposed heuristic is applied to an industrial case to further evaluate its performance. The result shows it can improve an average of total profit by 16.62%. This research contributes to the production planning research community with a complete mathematical definition of the problem and an effective solution approach to solving the problem of industry scale.

Segundo uma pesquisa recente realizada junto ao setor de fundições, uma importante preocupação do setor é melhorar seu planejamento de produção. Um plano de produção em uma fundição envolve duas etapas interdependentes: a determinação das ligas a serem fundidas e dos lotes que serão produzidos. Neste trabalho, estudamos o problema de dimensionamento de lotes para fundições de pequeno porte, cujo objetivo é determinar um plano de produção de mínimo custo. Como sugerido na literatura, a heurística proposta trata as etapas do problema de forma hierárquica: inicialmente são definidas as ligas e, posteriormente, os lotes que são produzidos a partir delas. Para a solução do problema, propomos um algoritmo genético que explora um conjunto de possibilidades para a determinação das ligas e utiliza uma heurística baseada em relaxação lagrangiana para determinação dos itens a serem produzidos. Além disso, uma abordagem para o mesmo problema é proposta utilizando o problema da mochila para determinar os itens a serem produzidos. Bons resultados foram obtidos pelos métodos propostos / According to a recent research made by the foundry sector, one of the most concern of the industry is to improve its production planning. A foundry production plan involves two independent stages: the determination of alloys to be merged and the lots that will be produced. In this work, we studied the lot-sizing problem for small foundries, whose purpose is to determine a plan of minimum production cost. As suggested in the literature, the heuristic proposed addresses the problem stages in a hierarchical way: rst we dene the alloys and, subsequently, the lots that are produced from them. We propose a genetic algorithm that explores some possible sets of alloys produced and uses a Lagrangian heuristic to determine the items to be produced. Also, we propose one approach to the same problem that uses the knapsack problem to determine the items to be produced. Good results were obtained by the methods proposed

Medieval tales of father-daughter incest depict more than offensively dominant fathers and voiceless, victimized young women: these stories often contain moments of surprising counternarrative. My analysis of incest narratives foregrounds striking instances of feminine resistance, where daughters act independently, speak unrestrainedly, adopt masculine behaviors, and invert masculine gazes. I argue that daughters of incestuous fathers participate in a complex back-and-forth of attraction and rejection that thrusts the fraught nature of the incest into sharp relief, revealing the ways in which medieval families--as well as the medieval church and state--constructed and deconstructed identities and sexualities. Extending Judith Butler's insights on how incest tales interrogate state and kinship networks, I show how the liminal position of daughters in the family destabilizes the sex/gender system as it functioned in both the family and the larger world, secular and sacred. My dissertation thus relocates daughters from the periphery to the center of the medieval family. Christian thematics likewise provide a key framework for both my argument and medieval audiences: biblical translations and retellings, saints' lives, and moral exempla offered familiar points of reference. By revealing how authors and artists employed well-known religious stories to impart political readings of sexuality and of the family, the four chapters of my dissertation assert daughters' key role in medieval Christian culture. I examine both Anglo-Saxon texts--the biblical epic Genesis A and the prose Life of Euphrosyne--as well as the late medieval poem Cursor mundi and Chaucer's Clerk's Tale. My readings are enhanced by recourse to the medieval visual record offered by three manuscripts that illustrate the Lot story--British Library MS Cotton Claudius B.iv, the Old English Hexateuch, and Oxford Bodleian Library MSS Junius 11(the Genesis A manuscript) and Bodley 270b, a Biblé moralisée. Artistic renderings of father-daughter incest are no less unsettled than their literary counterparts, and demonstrate that the position of daughters was so fundamentally unstable that it often varied not only within an era, but also within a single manuscript. I argue that authors and artists radically reimagined the fundamental texts of the Middle Ages, including the Old Testament, to establish new narratives of sin and salvation, self and other, and power and submission.

A new multipurpose town house has been designed into a vacant lot on Křížová street in Brno. Currently, Staré Brno is a territory without a clear concept, with high traffic load, and fragmented and often unsatisfactory development. The project therefore assumes and takes into account urban adjustments in this locality; in particular it anticipates traffic reduction in close proximity of the building and also decrease in noise load. The given location has some special features – its vastness allows it to form a whole street front; it shapes and closes a block which has a long history, its position is exceptional considering its closeness to Mendel square. The proposed building helps shape the appearance of Křížová street into which it opens with an urban-shaping facade. On the other hand, it distances itself from the inside yard which is unusable due to its unsatisfactory technical and aesthetic state. The building thus bears, within its own capacity, all the functional and spatial variety that the relation to the inside yard could offer. The result is a self-sufficient urban balcony-type building with a parquet circle designated to business and higher floors to living. There are 35 smaller flats projected for living, intended esp. for young families, couples or singles. The project assumes that the tenants will lead active and social lives, so it offers flexible outdoor areas that are both covered and open, surfaces that are both green and cemented and spaces that are both private and common.

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In this dissertation, we investigate the use of lot streaming in a two-stage assembly system and a two-stage hybrid flow shop in order to improve system performance. Lot streaming accelerates the flow of a production lot through a production process by splitting it into sublots, and then, processing these sublots in an overlapping fashion over the machines, thereby reducing work-in-process and cycle-time. Traditionally, lot streaming has been applied to problems in various flow shop machine configurations. It has also been applied to machine environments of job shop, open shop, and parallel machines. Its application to assembly system is relatively new. The two-stage assembly system that we consider consists of multiple suppliers at Stage 1 with each supplier producing one type of a subassembly (or a component), and one or more assembly locations at Stage 2, where the subassemblies are then put together. Lot-attached and sublot-attached setup time and cost are encountered on the machines at both the stages, and sublot-attached time and cost are encountered for the transfer of sublots from Stage 1 to Stage 2. Mass customization is an example of such a system in which the final assembly of a product is postponed to capture specific customer demands. Dell Computer constitutes a real-life example of this system. A customer picks his/her computer processor, memory, storage, and other equipment, on Dell's web site. Dell's supply chain is configured to obtain subassemblies from suppliers (stage 1), and then, to assemble the requisite systems in different market areas (stage 2). This enables a reduction in operating cost while improving responsiveness to customers. The problem that we address is as follows: Given a maximum number of sublots of each lot, determine the number of sublots to use (assuming equal sublot sizes), and also, the sequence in which to process the lots, in order to minimize two criteria, namely, makespan, total cost. We propose two column generation-based methods that rely on different decomposition schemes. The results of our computational investigation conducted by using randomly generated data sets reveal that the proposed column generation methods obtain solutions in a few seconds of CPU time while the direct solution by CPLEX of a mixed integer programming model of the problem requires much larger CPU times. For the hybrid flow shop lot streaming problem, the machine configuration that we consider consists of one machine at Stage 1 and two machines at Stage 2 (designated as 1+2 system). A single lot is to be processed in the system, and the objective is to minimize the makespan. A removal time is associated with each sublot at Stage 1. We present a mixed integer programming model for this problem to determine optimal number of sublots and sublot sizes. First, we consider the case of a given number of sublots for which we develop closed-form expressions to obtain optimal, continuous sublot sizes. Then, we consider determination of optimal number of sublots in addition to their sizes. We develop an upper bound on optimal number of sublots, and use a simple search procedure in conjunction with the closed-form expressions for sublot sizes to obtain an optimal solution. We also consider the problem of determining integer sublot sizes, and propose a heuristic method that directly solves the mixed integer programming model after having fixed values of appropriate variables. The results of our numerical experimentation reveal the efficacy of the proposed method to obtain optimal, continuous sublot sizes, and also, that of the proposed heuristic method to obtain integer sublot sizes, which are within 0.2% of optimal solutions for the testbed of data used, each obtained within a few seconds of CPU time. The last problem that we address is an extension of the single-lot lot streaming problem for a $1+2$ hybrid flow shop considered above to the case of multiple lots, where each lot contains items of a unique product type. We consider two objectives: minimize makespan, and minimize the sum of the completion times for all the lots. The consideration of multiple lots introduces a complicating issue of sequencing the lots. We use the results derived for the single-lot problem and develop effective heuristic methods for this problem. The results of our computational investigation on the use of different heuristic methods reveal their efficacy in solving this problem. / Ph. D.

Materials requirements planning (MRP) is a widely used method for production planning and scheduling. Planned lead-time (PLT) and lot size are two of the input parameters for MRP systems, which determine planned order release dates. Presently, planned lead-time and lot size are estimated using independent methodologies. No existing PLT estimation methods consider factors such as machine breakdown, scrap-rate, etc. Moreover, they do not consider the capacity of a shop, which changes dynamically, because the available capacity at any given time is determined by the loading of the shop at that time. The absence of such factors in calculations leads to a huge lead-time difference between the actual lead-time and PLT, i.e., lead-time error. Altering the size of a lot will have an effect not only on the lead-time of that lot but also on that of other lots. The estimation of lot size and lead-time using independent methodologies currently does not completely capture the inter-dependent nature of lead-time and lot size. In this research, a lot-sizing model is modified in such a way that it minimizes the combination of setup cost, holding cost and work-in-process cost. This proposed approach embeds an optimization routine, which is based on dynamic programming on a manufacturing system model, which is based on open queuing network theory. Then, it optimizes lot size by using realistic estimates of WIP and the lead-time of different lots simultaneously for single-product, single-level bills of material. Experiments are conducted to compare the performance of the production plans generated by applying both conventional and the proposed methods. The results show that the proposed method has great potential and it can save up to 38% of total cost and minimize lead-time error up to 72%. / Master of Science

Synsam started the Synsam Group's Production and Innovation Center (SPIC) on Frösön in the summer of 2022 as part of their sustainability work. The factory locating in Sweden contributes to shorter lead times, reduced carbon footprint, and more environmentally friendly transportation. Synsam has its own collections, called \textit{House Brands}, where some are produced at the newly established production facility in Sweden, while others are outsourced for production in Asia. The outsourced production has longer lead time compared to the SPIC-flow, larger minimum order quantities, and greater risks in transport delays. The aim of the project was to compare production at SPIC, with the purchasing process from Asia, the Asia-flow. This to investigate the challenges and opportunities posed by establishing in Sweden, particularly concerning costs, risk, and logistics. The focus was on how the two flows tie up capital in finished goods inventory and inventory for components and materials, as well as the size of inventory holding costs. With the aim as a starting point, the project's first phase was initiated: a preliminary study with a literature review and informal interviews. Subsequently, the second and third phases involved data collection and processing. The fourth phase involved modeling, where optimization of the procurement and production processes was carried out entailed on selected parameters. Lastly, the fifth phase involved scenario analysis. Throughout all phases, verification and validation have been conducted. The project's conclusion shows that product groupings where the products are expensive or have low demand tie up less capital in the SPIC-flow compared to the Asia-flow. This is mainly because SPIC can produce smaller batches, thereby reducing the number of products in inventory since production can be more precisely aligned with demand. Another conclusion from the project is that in the event of a sudden decreased demand, the SPIC-flow has fewer products that need to be recycled compared to the Asia-flow, resulting in less capital tied up. The work concludes by presenting recommendations and suggestions for further work.