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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Optimization of the Cab Production Sequence : A simulation-based study at Volvo Group Trucks' cab plant in Umeå / Optimering av produktionssekvensen : En simuleringsbaserad studie vid Volvokoncernens hyttfabrik i Umeå

Jonsson, Hanna, Sjöström, Emmy January 2016 (has links)
Volvo Group’s cab plant in Umeå produces cab bodies and consists of three operating areas; the Stamping and parts production, the Body in White and the Paint shop. Today the plant produces around XXX cabs/week, but the goal is to reach the invested capacity of XXX cabs/week. In order to increase the production capacity, the efficiency of both the manual and the automated processes need to be improved. Unlike the manual processes in where the capacity can be increased by enlarged workforce, the automated processes need to be optimized. Today the cabs are produced in the same order as the orders are received. The cab plant wants to investigate if the capacity of the automated segment in the Body in White unit can be increased by changing the order in the production sequence. This culminates in the following problem definition:  Is there untapped potential of the Body in White that can be achieved by an optimization of the production sequence? If so, how can Volvo Group’s cab plant in Umeå utilize this knowledge in the production planning process? The objective of the project was achieved by combining discrete event simulation with a heuristic optimization approach. The results shows that long batches in the production sequence limit the throughput of the system. By spreading the unfavorable subsequences of batches evenly over the production sequence, the total throughput of the Body in White can be increased by 52 cabs/week. / Volvokoncernens hyttfabrik i Umeå producerar förarhytter och är uppdelad i tre driftsområden; pressning och detaljtillverkning, hyttsammansättning och ytbehandling. Idag producerar fabriken ca XXX hytter/vecka, men möjlighet finns att nå upp till den investerade kapaciteten på XXX hytter/vecka. För att kunna öka produktionskapaciteten behöver både de manuella och de automatiserade processerna effektiviseras. Till skillnad från de manuella processerna, där kapaciteten kan ökas genom att öka antalet operatörer, behöver de automatiserade processerna optimeras. Idag produceras hytterna i samma ordning som beställningarna kommer in. Hyttfabriken vill undersöka om det finns en möjlighet att öka kapaciteten för den automatiserade processen i Body in White genom att optimera produktionssekvensen. Detta leder fram till följande problemformulering: Finns det outnyttjad potential i Body in White som kan uppnås genom att optimera produktionssekvensen? Hur kan Volvokoncernens hyttfabrik i Umeå utnyttja denna kunskap vid planering av produktionen? Målet med projektet har uppnåtts genom att kombinera diskret händelsesimulering med optimering genom heuristiker. Resultatet visar att stora batcher av samma variant i produktionen begränsar genomströmningen i processen. Genom att bland annat sprida ut de ogynnsamma delsekvenserna jämnt över produktionssekvensen kan den totala genomströmningen i Body in White ökas med 52 hytter/vecka.
2

Simulační verifikace komplexního technologického projektu / Simulated verification of complex technology project

Varjan, Matúš Unknown Date (has links)
In the introduction, doctoral thesis as a complex technological project uses the summary title Stability of production. Stability of production is defined as a maintaining the required properties of the system over a given time period. Stability of production, based on the literature study included: – generally known systems and concepts, for example Process Stability, System Stability, Toyota Production System, Lean Manufacturing, etc. – less-known systems and concepts, for example Maintaining the fidelity of the production program, Stable order-sequence concept. The practical part of the doctoral thesis is focused on the less-known concept: Stable order-sequence. The task of the Stable order-sequence is to follow the sequence of orders given by the planned production program in the course of the production and at the end of production. Maintaining the sequence of the orders has a positive experience in the logistics activities between the final producer and its suppliers. As it was found by the planned experiment for a full factory plan, the sequence of orders in the material flow of original equipment manufacturer is influenced mainly by: – the cause of the removing orders from material flow, – the effect of the causes LIFO stack vs. branched material flow, – the effect of the causes LIFO stack vs. branched material flow vs. the removing from the material flow. By the analysis of Stable order-sequence, it was found that the methodology of the concept contains deficiencies. It does not state how to choose for example the size of the time period, time interval, data editing etc. By this lack, the subject can skew the results in the evaluation of the indicator PFT0 up to 4 %. Or by using of suitable adjustment, the value of the indicator PFT0 can be improved more than 50 %. To test the concept of a Stable order-sequence in practice has been designed technological project with the support of discrete-event simulation. It was about the implementation of new management logic to the stack behind the welding of original equipment manufacturer. The new logic of management was designed with an emphasis on Stable order-sequence concept, to arrange the orders in process according to the planned sequence. On the base of the functionality verification of the new stack logic, it was found that the logic affects the sequence of the orders, but not fundamentally. In tracking the hourly intervals for 25th calendar week 2013, the value of PFT0 was not improved in 37 cases, the value remains in 30 cases and the value was improved by the value of the median 18,68 % in 30 cases orders.
3

Simulační verifikace komplexního technologického projektu / Simulated Verification of Complex Technology Project

Varjan, Matúš January 2016 (has links)
In the introduction, doctoral thesis as a complex technological project uses the summary title Stability of production. Stability of production is defined as a maintaining the required properties of the system over a given time period. Stability of production, based on the literature study included: – generally known systems and concepts, for example Process Stability, System Stability, Toyota Production System, Lean Manufacturing, etc. – less-known systems and concepts, for example Maintaining the fidelity of the production program, Stable order-sequence concept. The practical part of the doctoral thesis is focused on the less-known concept: Stable order-sequence. The task of the Stable order-sequence is to follow the sequence of orders given by the planned production program in the course of the production and at the end of production. Maintaining the sequence of the orders has a positive experience in the logistics activities between the final producer and its suppliers. As it was found by the planned experiment for a full factory plan, the sequence of orders in the material flow of original equipment manufacturer is influenced mainly by: – the cause of the removing orders from material flow, – the effect of the causes LIFO stack vs. branched material flow, – the effect of the causes LIFO stack vs. branched material flow vs. the removing from the material flow. By the analysis of Stable order-sequence, it was found that the methodology of the concept contains deficiencies. It does not state how to choose for example the size of the time period, time interval, data editing etc. By this lack, the subject can skew the results in the evaluation of the indicator PFT0 up to 4 %. Or by using of suitable adjustment, the value of the indicator PFT0 can be improved more than 50 %. To test the concept of a Stable order-sequence in practice has been designed technological project with the support of discrete-event simulation. It was about the implementation of new management logic to the stack behind the welding of original equipment manufacturer. The new logic of management was designed with an emphasis on Stable order-sequence concept, to arrange the orders in process according to the planned sequence. On the base of the functionality verification of the new stack logic, it was found that the logic affects the sequence of the orders, but not fundamentally. In tracking the hourly intervals for 25th calendar week 2013, the value of PFT0 was not improved in 37 cases, the value remains in 30 cases and the value was improved by the value of the median 18,68 % in 30 cases orders.
4

Flödesoptimering vid Umeå mejeri : Optimering av produktionssekvens via genetisk sökalgoritm

Forssén, Clara, Swedin, Jesper Yarp January 2021 (has links)
Norrmejerier’s supply of raw material fluctuates during different periods of the year. During the months where the company receives the most milk there is a need of an increase in cheese production in order to refine the milk in a more value creating way. To enable an increase in the production the process of the cheese department in Umeå is mapped. To determine the critical parts of the process a month’s production is simulated in a discrete event system.  Today the department produces eight different cheese types of which they aim to carry a constant partition. All process times except the one for the last process step are independent on the cheese type produced. The process time for the last leg differs with up to 70% depending on the cheese type. Hence the total production volume depends on the order in which the different types of cheese are produced, the production sequence.  In this thesis we optimize the production sequence with a genetic search algorithm. Given the predetermined distribution of cheese types a set of production sequences is created which are tested against a model imitating the process. The set of sequences is gradually improved through the genetic algorithm to finally reach a solution considered good enough. This enables us to derive the maximum capacity of the process and determine its bottlenecks.  This study concludes that a production increase of 16,6% can be achieved by additional staff, adjusted work routines and an optimized production sequence. To further increase the production, an increased capacity of the first part of the process is required, that being the pasteurization step. Given an increase in the pasteurization step the next bottleneck would appear in the last part of the process, where the cheese is placed in a salt brine. / Norrmejerier har under året en fluktuerande invägning av råvara som vid toppar ger upphov till ett råvaruöverskott. För att förädla råvaran på ett mer värdeskapande vis finns ett behov av en kapacitetsökning av osttillverkning under de perioder då invägningen är som störst. För att möjliggöra en ökad produktion av ost kartläggs processen på ysteriavdelningen i Umeå. Avdelningen producerar åtta osttyper och önskar bibehålla en förutbestämd fördelning av dessa. Givet fördelningen simuleras en månads produktion i ett diskret händelsesystem där kritiska delar i processen identifieras.  Beläggningstiden för processdelarna på ysteriavdelningen är mer eller mindre oberoende av vilken osttyp som produceras med undantag för det sista processteget där beläggningstiden varierar med upp till 70%. Detta leder till att den totala produktionsvolymen är beroende av i vilken ordning de olika osttyperna produceras.  I denna studie optimerar vi denna ordningsföljd, benämnd produktionssekvens, med en genetisk sökalgoritm. Givet den förutbestämda fördelningen av osttyper skapar vi en mängd produktionssekvenser som testas mot en modell som imiterar processen. Mängden produktionssekvenser utvecklas successivt via den genetiska algoritmen för att kulminera i en tillräckligt bra lösning. Genom att göra detta kan processens flaskhals identifieras och en maxkapacitet härledas.  Studien fastställer att förändringar i bemanning, arbetssätt och en optimerad produk- tionssekvens kan ge en ökad produktion om 16,6%. För ytterligare förbättringar krävs ökad kapacitet på den första processdelen där mjölken pastöriseras. Om kapaciteten utökas uppstår nästa flaskhals i det sista processteget, saltlaken.
5

Flow simulation of Body In White : Optimization of the production sequence and identification of bottlenecks at Volvo Trucks plant in Umeå / Flödessimulering av Body In White : Optimering av produktionssekvensen och identifiering av flaskhalsar vid Volvokoncernens hyttfabrik i Umeå

Lundberg, Mattias, Söderlund, Johan January 2017 (has links)
In this study, a discrete event model was created and used in combination with an optimization method to find the optimal production sequence at Volvo Group’s cab plant in Umeå. The optimization was performed with a heuristic approach combined with a genetic search algorithm. The result provides an optimized production sequence with an increased production performance. Potential improvements in the production flow were identified to significantly increase the throughput. Volvo Group Trucks Operations plant in Umeå is a part of Volvo Group AB and is one of the world’s largest manufacturers of heavy duty trucks. The plant in Umeå produces cab bodies and consists of Stamping and Part production, Body In White and the Paint Shop. As of today, the plant produces about XXX produced cabs per week with the goal to achieve the invested capacity of 1666 produced cabs per week. The production is structured with a daily scheduling of the cab production. Today cabs are produced in the same sequence as the orders are received. There has been an investigation regarding the production capacity in the past but further investigation was required due to insufficient data available at the time. Volvo wants to investigate the potential improvements in the BIW unit, increase the production rate and reach the level of invested capacity. Therefore, this project was introduced which led to the following problem definition: “What is the optimal production sequence in the BIW unit?” To further find potential improvements, a secondary problem definition got formulated: “How would the production sequence be affected if the current biggest bottleneck were removed?” The objective was achieved with Discrete Event Simulation, where heuristic based sequences were optimized in a genetic search algorithm. This resulted in identified sequence patterns, which were used to improve the production sequence. When analyzing the model, the floor subflow was identified as the biggest bottleneck in the production. A general suggestion would be to avoid large batches due to significant risk of limiting the throughput. Results suggest that sequences should be in cycles of 3FH-1FM with segments of batches as long as the floor buffer does not run out of parts. This resulted in a potential increased throughput of 3.2-3.7% for the Body In White. If the biggest bottleneck were to be removed, there would be a potential production increase by roughly 10% compared to the production today. / I den här studien skapades en diskret händelsestyrd modell som användes i kombination med en optimeringsmetod för att ta reda på den optimala produktionssekvensen i Volvokoncernens hyttfabrik i Umeå. Optimeringen utfördes genom heuristiker i kombination med en genetisk sökalgoritm. Detta resulterade i en optimerad produktionssekvens med en ökad takt gentemot dagsläget. Potentiella förbättringar i produktionsflödet kunde identifieras för att signifikant öka genomströmningen av hytter. Volvo Group Trucks Operations hyttfabrik i Umeå är en del av Volvo Group AB och är en världsledande tillverkare av tunga lastbilar. Fabriken i Umeå tillverkar lastbilshytter med plåtbearbetning, presshall, sammansättning och måleri. I dagsläget producerar fabriken ungefär XXX hytter i veckan med målsättningen att komma upp i den investerade kapaciteten: 1666 producerade hytter i veckan. Produktionen är upplagd med planering av hyttproduktion på daglig basis. Idag produceras hytterna inte i någon specifik sekvens utan produceras enligt samma ordning som ingående orderkö. En studie kring produktionskapaciteten har tidigare utförts, dock finns behovet av ytterligare undersökning då tillgängligheten av väsentlig data för att kunna utföra studien varit begränsad vid tidigare skeden. Av den anledningen vill Volvo utföra en undersökning för att hitta potentiella förbättringar i BIW enheten, för att således uppnå den investerade kapaciteten. Därav introducerades detta projekt med följande problemdefinition: “Vad är den optimala produktionssekvensen i BIW enheten?” För att hitta ytterligare förbättringar, så formulerades en sekundär problemdefinition: “Hur skulle produktionssekvensen påverkas om den största flaskhalsen eliminerades?” Målet nåddes med diskret händelsestyrd simulering, där optimering utfördes genom heuristiskt baserade sekvenser tillsammans med en genetisk sökalgoritm. Identifierade mönster användes sedan för att förbättra produktionssekvensen. Vid analysering av modellen identifierades floor-flödet som den största flaskhalsen i produktionen. Ett generellt förslag är att undvika stora batcher då detta innebär en signifikant risk att begränsa genomströmningen av hytter. Resultatet indikerar att sekvenser bör bestå av cykler om 3FH-1FM, med segment av batcher så länge floor-buffrarna inte är tomma. Detta resulterade i en potentiellt ökad genomströmning med 3,2-3,7% per vecka för BIW enheten. Om den största flaskhalsen i floor-flödet skulle elimineras så kan produktionen potentiellt öka med 10% jämfört mot dagens produktionstakt.
6

Análise de estratégias de execução para edifícios verticais com diferentes sistemas construtivos. / Analyze of production strategies for tall buildings with different construction systems.

Barbosa, Maysa Fontoura 09 September 2005 (has links)
Made available in DSpace on 2016-06-02T20:09:24Z (GMT). No. of bitstreams: 1 DissMFB.pdf: 12924718 bytes, checksum: a2a9aa316f9b1cfca133881538c8d7aa (MD5) Previous issue date: 2005-09-09 / The civil construction management has been taken more attention of civil construction companies in aim alternatives to enhancing theirs management process, main that work with building construction because the growing competition and the exigency of their invest. In this set, the strategic planning is fundamental for the development and success of business because generates data that will guide the balance between the production planning expectation and the necessary costs for concluding a project. The supply of planning data and performances of building construction is get to divide of the simulation of the production strategy. The planning production represents the strategies because its products are some information: schedules, graphs and reports to arrive the execution efficiency. This research presents analyze the conduct of two different construction systems variables of three construction strategies. The construction systems studied were traditional construction system and the external walls in reinforced concrete construction system. The production strategies simulated concentrated in analyse only the tower and were without inversion of services; with partial inversion of services; and with total inversion of services. Like product of this research to claim develop a systematization to value and choose the production strategies to attend by the tall building construction companies. / O gerenciamento em obras de construção civil vem recebendo atenção por parte das empresas na busca de alternativas para melhorar seus processos de gestão da produção. Isso ocorre principalmente em empresas que trabalham com construção de edifícios para o mercado imobiliário, face à competitividade e exigências estabelecidas por seus investidores. Neste contexto, as estratégias de execução são fundamentais para o desenvolvimento e sucesso do negócio , pois delas decorrem a forma de como serão aproveitados os recursos físicos e financeiros disponibilizados. Através de simulações de estratégias de execução são fornecidos diversos dados de planejamento ao subsetor edificações. Tais estratégias são representadas pelo planejamento da produção através da geração de informações: cronogramas, gráficos e relatórios. Dessa forma, este trabalho analisa o comportamento das variáveis de produção de dois sistemas construtivos através da proposição de três diferentes estratégias de execução. Os sistemas estudados foram o sistema construtivo tradicional e o sistema construtivo com paredes externas em concreto moldado in loco . As estratégias de execução simuladas concentraram-se na análise dos serviços da torre do edifício vertical, sendo propostas as seguintes seqüências: sem inversão dos serviços, com inversão total dos serviços e com inversão parcial dos serviços. Os principais resultados desta pesquisa são apresentados na forma de parâmetros e gráficos que facilitam a avaliação e seleção de estratégias de execução a serem seguidas pelas empresas que executam edifícios verticais.

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