Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1900. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed October 27, 2008)

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Os modelos de programação e controle Constant Work-In-Process (CONWIP) e Drum-Buffer-Rope (DBR) são mecanismos bastante conhecidos na literatura de Planejamento e Controle da Produção, especialmente, pela robustez e bom desempenho. Esses modelos já foram comparados, sobretudo, em ambientes do tipo flow shop. Há muitos trabalhos que apontam o DBR como superior, outros que sugerem equivalência entre ambos e, em menor proporção, casos onde o CONWIP foi melhor. Contudo, estudos comparativos em ambientes mais complexos, como sistemas com montagem, ainda são escassos na literatura. Diante do exposto, a presente tese visa comparar o CONWIP e o DBR em um ambiente de montagem (assembly flow shop) contra pedido. Para tanto, foram desenvolvidos dois modelos de simulação por eventos discretos e um experimento hierárquico-cruzado, com os seguintes fatores: modelo de programação e controle, posição do gargalo, severidade do gargalo e limite de buffer. Os mecanismos foram avaliados quanto aos indicadores tempo médio de fluxo, lead time médio, utilização do gargalo, percentual de ordens atrasadas e atraso médio. Os resultados demonstraram que, para o ambiente em análise, os modelos se mostraram estatisticamente semelhantes, havendo diferenças significativas apenas para a variável tempo médio de fluxo, o que ratifica e estende conclusões de estudos anteriores. Há evidências de que o CONWIP realiza um controle mais efetivo do estoque em processo e não é significativamente afetado pelas diferentes posições do gargalo. Para o CONWIP, os melhores resultados foram identificados quando a restrição estava no início do sistema, enquanto que para o DBR os melhores resultados foram quando o gargalo estava na última estação da linha de fabricação (operação anterior a montagem). / The Constant Work-In-Process (CONWIP) and Drum-Buffer-Rope (DBR) scheduling and control models are well known mechanisms in the Production Planning and Control literature, especially for robustness and good performance. These models have already been compared, especially, to flow shop environments. There are many papers that point to DBR as superior, others that suggest equivalence between both and, less often, cases were CONWIP was better. However, comparative studies in more complex environments, such as assembly systems, are still rare in the literature. Therefore, this thesis aims to compare CONWIP and DBR in a make-to-order assembly flow shop environment. For that, two models of discrete event simulation and a crossed and nested experiment were developed, with the following factors: scheduling and control model, bottleneck position, bottleneck severity and buffer limit. The mechanisms were evaluated with respect to the indicators mean flow time, mean lead time, bottleneck utilization, percentage tardy and mean tardiness. The results showed that, for the environment under analysis, the models were statistically similar, with significant differences only for the variable mean flow time, which ratifies and extends the conclusions from previous studies. There is evidence that CONWIP performs more effective control of order release and is not significantly affected by the different bottleneck positions. For the CONWIP, the best results were identified when the constraint was at the beginning of the system, while for the DBR the best results were when the bottleneck was at the last station of the manufacturing line (before assembly operation).

In this thesis, a real world application of the constant work in process (Conwip) system in an electronics company is realized. The aim of the application is to reduce the work in process (WIP) inventory while maintaining the same throughput level. A model is developed to determine the constant work in process level of the Conwip system for the production lines in this company. The approximated mean value analysis approach is used for the solution. Real system data are collected before and after the Conwip application. Hypothesis tests are used to compare the WIP and the throughput levels of the Conwip system with the existing push control system for a pilot production line. Results of the hypothesis tests show that the Conwip production control system can signinifcantly reduce the WIP while maintaining the same throughput rate.

Orientador: Regina Aparecida Polo Muller, Graziela Estela Fonseca Rodrigues / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-07T01:15:22Z (GMT). No. of bitstreams: 1 Lyra_LucianadeFatimaRochaPereirade_M.pdf: 1332252 bytes, checksum: b45917f98f3c8decf0c034b89486c115 (MD5) Previous issue date: 2005 / Resumo: A presente pesquisa visa explicitar o processo de criação de uma poética em performance, cujo roteiro apóia-se na mitologia pessoal - por intermédio da persona Joana d¿Arc -, e no percurso artístico autoral, o qual se fundamenta em dois pólos: o da incursão na polifonia cênica - proposta pela Arte de Performance ­¿ e o de vivência identitária no espetáculo de Cavalo Marinho pernambucano (Bumba-meu-boi). Na trajetória desta investigação processual, foram desveladas intersecções entre as duas expressões cênicas acima mencionadas, incluindo-se aí a presença do mythos em ambas as vertentes de Performance Cultural, como são conceituadas, ressaltando-o como aquele que dá enlevo à criação espetacular e à atuação. É a partir da articulação entre o mito, enquanto narrativa intertextual, e a linguagem interseccional (Performance-Cavalo Marinho), que se aponta a Poética do Teatro Rasgado, calcada na seguinte tríade de matrizes cênicas: sacralidade (mito), ancestralidade (memória) e ludicidade (jogo) / Abstract: This research aims to present the creation process of the performance , in which the main guideline is based on the personal mythology - presented through the persona of Joan of Arc - and in the author's artistic process - this one based on two different paths: the scene polyphony - a caracteristics of performing arts - and the cultural identities showed in a Cavalo marinho (bumba-meu-boi) show, a play created in the Brazilian State of Pernambuco. In this work - in- process investigation were revealed common points between the theatrical expressions mentioned above, especially including the mythos in the definitions of both cultural performances. The mythos is responsible for  the spectacular caracteristics of both kinds of performances and for the acting. It is from this link between the mythos, as an intertextual narrative, and the interacting language (performing arts - cavalo Marinho), that the poetic quality of Teatro Rasgado (Torn Theatre) is defined, based on the following scene directions: sacrality (myth), ancestrality (memory), ludism (play) / Mestrado / Mestre em Artes

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In this thesis, we study both dynamic and distributed facility layout problems, where the demand for product mix changes over time. We propose a new simulated annealing algorithm, SALAB, for the dynamic facility layout problem. Four variants of SALAB find the best known solution for 20 of the 48 benchmark problems from the literature, improving upon the best known solutions of 18 problems. We modify SALAB to obtain DSALAB, solving the dynamic distributed facility layout problem with the objective of minimizing relocation cost and total (full and empty) travel cost of the material handling system. We simulate DSALAB solutions of randomly generated problems to study the tradeoff between total cost and congestion in the system. Our experimental results indicate that distributing the department duplicates throughout the facility reduces the total cost with diminishing returns and causes increasing congestion. Therefore, distribution beyond a certain level is not justified.

In a constantly increasing and more demanding global market, companies must continuously improve and develop in order to stay competitive. A manufacturing company can have several goals in order to succeed in this, both strategically and internally within the production. Unfortunately, many goals conflict with each other due to the interrelationship between them. Decisions must be taken whether to focus on maximizing delivery precision, minimizing costs of tied-up capital, or minimizing production costs, which means that trade-offs are necessary to be made. At Gnutti Carlo Sweden in Alvesta, this is their present reality, where a completely new production line is currently being installed. This is planned to start producing in the beginning of 2016, with successively increased volumes until reaching full production in 2018. Due to process constraints, inventories must be placed within the process in order to keep these utilized to the highest extent possible. On one hand, sufficient inventory must be kept in order to prevent waiting time in the constraining work station, and on the other hand, inventories within the process should be kept as small as possible, this in order to minimize holding costs and required space. This conflict formed the purpose of the study, which was to achieve a suitable balance between minimizing waiting times in the constraining station and the level of inventories within the process, with main focus on waiting times. In order to fulfill the purpose, the problem was approached using simulation as the main methodology. In addition to simulation, the study included elements of case studies, experimental methods and action research, which were present at different stages of the project. A nine-step simulation methodology was the inspiration in how the study was conducted, which included necessary mile-stones for reaching qualitative simulation results from a real system, meaning that the approach had a high focus on validation. By creating a conceptual model, which is a reflection of the current state, a simulation model that represented the process was possible to create. By applying different aspects from existing philosophies and concepts, such as Lean production, Theory of Constraints, and other production concepts, it was possible to form a set of scenarios that corresponded to different potential approaches that were believed to fulfill the study purpose. Using the simulation model, several experiments were conducted, testing the effects from applying the different scenarios, which mainly consisted of different batching strategies to use in a non-constraining work station located prior to the inventory in the process. The results showed that using smaller batches of similar sizes in the non-constraining work station, prior to the supermarket, is significantly decreasing inventory levels, this while not negatively affecting the waiting time in the constraint. The results showed decreased inventories up to approximately 50% when testing certain scenarios, however not considering some parameters that may affect the process. Important to consider is that the excess capacity of the process is what is controlling the minimum size of the batches, thus also the inventory size needed. Recommendations included to use different batching strategies for non-constraining stations, as well as to further investigate the process before production start, as some parts of the process are excluded in the study. / I en ständigt växande och mer krävande global marknad måste företag kontinuerligt förbättras och utvecklas för att fortsatt vara konkurrenskraftiga. Ett tillverkningsföretag kan ha olika mål för att lyckas med detta, både strategiska och interna inom produktionen. Tyvärr verkar flera mål mot varandra på grund av ett inbördes förhållande. Beslut måste tas gällande att antingen fokusera på att maximera leveransprecisionen, minimera kostnaden för bundet kapital eller minimera produktionskostnaderna, vilket betyder att kompromisser måste tillämpas. På Gnutti Carlo Sweden i Alvesta är detta deras nuvarande verklighet, där en helt ny produktionslinje för närvarande installeras. Denna är planerad att börja producera i början av 2016, med succesivt ökande volymer fram tills 2018, då full produktion nås. På grund av processbegränsningar måste lager placeras i processen för att upprätthålla en högsta möjlig utnyttjandegrad för dessa. Å ena sidan måste tillräckliga lager hållas för att undvika väntetider i den begränsande arbetsstationen, å andra sidan bör lagernivåerna hållas så låga som möjligt, detta för att minimera lagerkostnader och lagerutrymme. Denna konflikt var grunden till syftet till studien, vilket var att uppnå en passande balans mellan minimering av väntetider i den begränsande arbetsstationen och lagernivåerna i processen, med huvudfokus på väntetider. För att kunna uppfylla syftet var problemet angripet med hjälp av simulering som huvudsaklig metod. Utöver simulering innehöll studien element av fallstudier, experimentella metoder och aktionsforskning, vilka var aktiva under olika faser av projektet. En nio steg lång simuleringsmetod tjänade som inspiration för hur studien genomfördes, vilken innefattade nödvändiga milstolpar för att lyckas nå kvalitativa simuleringsresultat från ett verkligt system, vilket innebar att metodiken fokuserade mycket på validering. Genom att skapa en konceptuell modell, vilket är en avspegling av nuläget, kunde en simuleringsmodell som representerade processen att skapas. Genom applicering av olika aspekter från existerande filosofier och koncept, exempelvis Lean production, Begränsningsteorin samt andra produktionskoncept, möjliggjordes bildandet av en samling scenarier som motsvarade olika, potentiella, tillvägagångssätt som ansågs kunna uppfylla studiens syfte. Genom simuleringsmodellen utfördes flera experiment, vilka testade effekterna från appliceringen av de olika scenarierna, som huvudsakligen bestod av olika strategier gällande partierna i en icke-begränsande arbetsstation, vilken är placerad innan lagret i processen. Resultatet visade att, genom applicering av mindre partistorlekar i den icke-begränsande arbetsstationen före lagret i processen, kan lagernivåerna minskas avsevärt, detta utan att negativt påverka väntetiderna i begränsningen. Resultatet visade minskade lager med upp till 50% för vissa scenarier, detta dock utan hänsyn tagen till vissa parametrar som kan påverka processen. Viktigt att beakta är att överskott av kapaciteten i processen är vad som kontrollerar minimistorleken på partierna, därför också lagerstorleken som krävs. Rekommendationerna innefattade införandet av olika strategier gällande partierna i icke-begränsande arbetsstationer samt att fortsatt undersöka processen, detta på grund av att vissa delar av processen är exkluderade i studien.

Kandidatuppsats i logistik för Civilekonomprogrammet (15 hp) Linnéuniversitetet, 2FE25E, VT16 Författare: Erik Karlsson, Faton Leku & Jeppe Lindström Handledare: Hana Hulthén Examinator: Åsa Gustavsson Titel: Effektivisering av lager för produkter i arbete Bakgrund: Ett tillverkningsföretag har ofta flera varianter av lager som till exempel färdigvarulager, säkerhetslager och produkter i arbete-lager. Produkter i arbete brukar benämnas som PIA. PIA-lagrets utformning är en viktig del för hur flödet i en verksamhet ser ut och fungerar. Syfte: Syftet är att föreslå en förbättrad hantering av PIA-lager för att bidra till ökad effektivisering av internt materialflöde. Metodval: Studien utgår ifrån en kvalitativ fallstudie. Studien utgår ifrån observationer på fallföretaget samt semistrukturerade intervjuer. Slutsatser: Vi kan efter genomförd studie påvisa att det finns skillnader mellan vad som beskrivs i teorin och hur PIA-lagret på Proton Lighting faktiskt ser ut. Det som har påvisats i jämförelsen mellan dessa är att MTO-artikeln är den som prioriteras före MTS-artikeln. Det innebär att lagringskostnaderna för MTS-artiklar automatiskt blir högre då MTO-artiklarna alltid har företräde i produktionen. Det finns inte heller någon fast artikelplacering i PIA-lagren vilket gör att artikelkomponenterna kan placeras var som helst i PIA-lagren, vilket leder till en ökning av de interna transporterna. Nyckelord: Produkter i arbete, lager, lagerlayout, make-to-order, make-to-stock, artikelplacering / Bachelor thesis, Program of Master of Science in Business and Economics School of Business and Economics at Linnaeus University in Växjö 2FE25E, spring 2016 Authors: Erik Karlsson, Faton Leku and Jeppe Lindström Advisor: Hana Hulthén Examiner: Åsa Gustavsson Title: Improving the efficiency of work in process inventory Background: A manufacturing company often has varieties of inventories, for example inventory of finished products, safety stocks and work in process inventory. The shaping of the WIP inventory is very important for a business since the other activities linked to the WIP inventory are effected of the shaping of the WIP inventory. Purpose: The purpose is to suggest an improved utilization process of WIP inventory in order to support an efficiency of internal flow of materials. Methodology: The study applies a qualitative case study. The study is based on observations at the case company together with semi-structured interviews. Conclusions: After concluded study we can show that there are differences between what is described in the theory and how the actual WIP inventory is constructed at Proton Lighting. What has been shown in the comparison between the theory and the collected data is that the MTO-flow precede the MTS-flow. Automatically the MTS-article gets a higher inventory cost because of the preceding of the MTO-article. There is not a fixed placement for the articles in the WIP inventories which can result in that the articles are placed anywhere in the factories WIP inventories, which leads to an increase of the internal transports. Keywords: Work in process, inventory, inventory layout, make-to-order, make-to-stock, article placement