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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.
11

Toyota production system

Vyas, Kewalkumar Chandrakant 07 November 2011 (has links)
Background: There are various manufacturing methods and systems in automobile industries throughout the world. Of these, many practice lean manufacturing methods. The most effective and influential to all of these methods is the “Toyota Production System” (TPS). The TPS was invented by Toyota's founding fathers in 1930 in Japan. The TPS continuously evolves making it a benchmark for the manufacturing, product development or any other sector of industry. It is fully based on “Socio-Technical” systems in a continuously changing manufacturing environment. It is about learn through doing and also about tacit knowledge and not explicit procedural knowledge. Outcome: The Toyota Production System is called “The Toyota Way” and it actually gives you a roadmap or more of a compass to set your direction and helps you steer your own course. Toyota has internally developed simple but effective tools and consistently trains their team members to implement those in all aspects of manufacturing and designing their vehicle. For example, Toyota has developed Kaizen or continuous improvement through which they eliminate waste that adds cost without adding value no matter how small it is. Toyota is known for the quality of their products. Not surprisingly their product is made at a significantly lower price within a given segment of the auto market. It is a result of hard work, innovation, and a Japanese work culture of generations at Toyota all across the world. Conclusions: Through theoretical analysis backed by my personal observations as an employee and from the sales figures of Toyota automobiles, I firmly believe that Toyota backs up its philosophy of long term benefits over short term financial goals. The right processes will produce right results. It is also one of the top companies among their group of long term suppliers as Toyota challenges them and helps them to improve. Initial quality and customer satisfaction surveys of J.D.Powers and Associates for Toyota and Lexus vehicles have won numerous awards since 2001. / text
12

Lean Produktion inom prefabindustrin / Lean production in precast industry

Andersson, Oskar, Bylow, Jacob January 2015 (has links)
Examensarbetet utfördes på Kynningsrud Prefab AB i Uddevalla som tillverkar prefabricerade betongelement till byggindustrin. I dagsläget är företaget inte helt tillfredsställt med material-, produkt-, information- eller kommunikationsflödet i verksamheten. Kynningsrud vill därmed skapa ett eget produktionssystem, KPS, för en fortsatt expansion.   Genom diskussion med företaget beslutades att arbetet skulle fokusera på tillverkningen av väggelement. Syftet med arbetet är att analysera och identifiera förbättringsmöjligheter samt ta fram förbättringsförslag med förhållningssättet lean produktion.   För att eliminera icke värdeadderad tid, standardisering av arbetsmoment samt informationsspridning valdes de sju slöserierna+en och 5S verktyget som teoretiskt ramverk. Information om verksamheten samlades in genom observationer, intervjuer och deltagande. Genom en nulägesbeskrivning av väggproduktionen med tillhörande stödprocesser beskrevs  arbetsmoment i processerna. Beskrivningen analyserades sedan efter det teoretiska ramverket.   Analysen resulterade i åtta förbättringsförslag som tillsammans skulle eliminera slöserier med en total tidsåtgång på ungefär 12 timmar om dagen. Det innebar en kostnadsreduktion på cirka 3,500 kr per dag. Sammanställning av den insamlade informationen åskådliggjordes genom en GAP-analys.   Vid tid- och kostandsberäkningar används den lägst uppskattade tidsåtgången från observationer och intervjuer med personalen som därmed kan innehålla mörkertal. Det gör att de beräkningar som redovisas är i teorin lägsta besparingen som kan genomföras. Kostnadsreduceringen kan i verkligheten vara större vid  en implementering av förbättringsförslagen. / The thesis was executed at Kynningsrud Prefab AB in Uddevalla. The company produces precast elements within the construction industry.  Currently, the company is not fully satisfied with the internal communication or the flow of material or finished products. Thus, Kynningsrud is planning to create a production system, KPS, in order to keep in pace with their current sales expansion. Through deliberations and discussions regarding the issue together with the company, a decision was made to focus on the manufacturing of the concrete walls. The conclusion came down to the purpose of the thesis would be to analyze and identify opportunities of improvement and to develop proposals targeted lean production. To eliminate non-value adding time as well as working to standardize operations and make the internal communication more efficient the two theories The seven wastes+one and the 5S tool was elected as theoretical framework. The necessary information about each step of the manufacturing process was collected by observing, interviewing and participation in the working process. The information was assembled to six current state descriptions of the production and describes every operation in each step of the processes. Finally, the description was analyzed according to the theoretical framework. The analysis resulted in eight improvement proposals that together would eliminate waste with a total time of approximately 12 hours a day for all analyzed operations combined. It meant a cost reduction of about 3,500 Swedish crowns per day. The compilation of the information collected was illustrated through a gap analysis. The time duration that was used for the saving calculations were estimated values ​​through observations and interviews with staff members. When calculating the time possible to save the lowest estimated time duration were used and the results may therefore contain numbers of unknown cases. It makes the calculations the theoretically lowest savings that can be made. In reality, the cost reduction could be greater if the improvement proposals were implemented.
13

Evaluation des algorithmes de calcul de dose pour les faisceaux d’électrons utilisés en radiothérapie : comparaison aux mesures par films radiochromiques / Evaluation des algorithmes de calcul de dose pour les faisceaux d’électrons utilisés en radiothérapie : comparaison aux mesures par films radiochromiques

El Barouky, Jad 25 January 2011 (has links)
La précision du calcul de dose est cruciale pour la qualité de la planification et de la réalisation des traitements en radiothérapie. L’objectif de ce travail était d’évaluer la qualité des algorithmes de calcul de dose des faisceaux d’électrons pour des conditions particulières proches des situations cliniques rencontrées. Une méthodologie spécifique de dosimétrie par films radiochromiques des faisceaux d’électrons a été développée et validée, y compris pour des situations difficiles avec une précision de 3.1% en dose absolue et 2.6% en dose relative. Cette technique a permis de développer des tests de Contrôle Qualité généralistes rapides et efficaces qui servent de base de données mesurées en cas de changement de version du système de planification de traitement et/ou d’algorithme de calcul de dose. Les mesures par films ont été comparées avec les calculs de deux algorithmes de calcul de dose Pencil Beam et Monte Carlo. Les deuxcodes ont donné des résultats similaires dans les tests d’obliquité, d’irrégularité et de DSP étendue. En revanche, les calculs Monte Carlo sont plus précis en présence d’hétérogénéités. D’autre part, cette méthode de dosimétrie par films radiochromiques a permis de développer un nouveau mode d’évaluation des plans de traitement avec des films découpés et insérés dans des fantômes anthropomorphiques (de type thorax et tête) de manière à obtenir la distribution de dose en 2D dans un plan transversal donné ; ces tests cliniques pouvant aussi être utilisés dans le cadre d’un Contrôle de Qualité interne adapté à l’activité clinique du service. La comparaison des mesures avec les calculs a montré une meilleure précision dans les calculs Monte Carlo par rapport aux calculs Pencil Beam au niveau des hétérogénéités, notamment dans les poumons, les cavités et les os. / In radiotherapy, the dose calculation accuracy is crucial for the quality and the outcome of the treatments. The purpose of our study was to evaluate the accuracy of dose calculation algorithms for electron beams in situations close to clinical conditions. A new practical approach of radiochromic film dosimetry was developed and validated especially for difficult situations. An accuracy of 3.1% and 2.6% was achieved for absolute and relative dosimetry respectively. Using this technique a measured database of dose distributions was developed to form the basis of several fast and efficient QualityAssurance tests. Such tests are intended to be used also when the dose calculation algorithm is changed or the Treatment Planning System replaced. Pencil Beam and Monte Carlo dose calculations were compared to the measured data for simple geometrical phantom setups. They both gave similar results for obliquity, surface irregularity and extended SSD tests but the Monte Carlo calculation was more accurate in presence of heterogeneities. The same radiochromic film dosimetry method was applied to film cuts inserted into anthropomorphic phantoms providing a 2D dose distribution for any transverse plan. This allowed us to develop clinical test that can be also used for internal Quality Assurance purposes. As for simpler geometries, the Monte Carlo calculations showed better agreement with the measured data than the Pencil Beam calculation, especially in presence of heterogeneities such as lungs, cavities and bones.
14

Etude des relations structure-propriétés de matériaux à base d'amidon : effet d'orientation et d'irradiation sous faisceau d'électrons / Structure-properties relations of starch-based materials : impact of orientation and electron beam irradiation.

Mikus, Pierre-Yves 22 November 2011 (has links)
Ce travail s'inscrit dans la démarche générale de compréhension et d'amélioration des propriétés mécaniques des matériaux thermoplastiques amylacés, en proposant une nouvelle démarche originale de modification structurale de l'amidon thermoplastique s’appuyant sur la combinaison de deux techniques: la réticulation de l'amidon sous faisceau d’électrons et l'orientation macromoléculaire issue du procédé de transformation par extrusion. La première partie du manuscrit est consacrée aux propriétés thermomécaniques de l’amidon plastifié et propose notamment une mise à jour de la courbe maitresse contrainte-allongement mettant en évidence le phénomène d’antiplastification mais aussi de surplastification grâce notamment à l’étude des propriétés à Tg équivalentes. L’évolution des températures de transition β (Tβ) des matériaux a pu être reliée aux différentes étapes de la plastification et des analyses ATG ont mises en évidence les phénomènes de sorption et désorption du plastifiant. Les mécanismes d’endommagement de l’amidon plastifié ont également été explorés à l’aide de la technologie de vidéotraction. Le second chapitre du document est consacré à l’étude de la réticulation de l’amidon thermoplastique à l’état solide sous faisceau d’électrons. De nombreux facteurs ont été étudiés comme la dose absorbée, la teneur en eau, la teneur en plastifiant, le type et la teneur en réactif introduit, ainsi que l’impact du taux de réticulation sur le mécanisme de rétrogradation. Le troisième et dernier chapitre traite du mécanisme d’orientation moléculaire particulier de l’amidon thermoplastique, et de son impact sur les propriétés mécaniques. Le couplage de l’orientation et de l’irradiation sous faisceau d’électrons a également été appréhendé. / This work is part of the general approach aiming to understand and improving the mechanical properties of thermoplastics starch materials by proposing a new and original approach to the structural modification of thermoplastic starch through the combination of two techniques: radiation crosslinking and macromolecular orientation. The first part of the thesis focuses on the thermo-mechanical properties of plasticized starch and proposes an update to the master Stress-strain curve highlighting “antiplasticization” and “overplasticization” phenomena thanks to the study of properties at equivalent Tg. The evolution of materials β transition temperature (Tβ) could also be linked to the different plasticization stages and TGA results highlighted the sorption and desorption phenomenon of the plasticizer. The damage and fracture mechanisms of plasticized starch were also explored with videotraction technology. The second chapter of the document is devoted to the study of crosslinking of thermoplastic starch at solid state under an electron beam radiation. Many factors were explored like the absorbed dose, water content, plasticizer content, nature and amount of crosslinking agents introduced, and their impact on curing mechanisms and retrogradation of the plasticized starch. The third and final chapter deals with the specific mechanism of molecular orientation of the thermoplastic starch and its impact on mechanical properties. The coupling of orientation and irradiation under an electron beam was also investigated.
15

Material replenishment system

Andersson, Stefan, Elfvenfrost, Johan January 2016 (has links)
This thesis work has been written both for and in co-operation with the company IAC Group Gothenburg. The main purpose of the report is to find a new alternative material replenishment system which will improve the internal material flow and eliminate unnecessary work activities such as manual call offs. The aim is to find a new system to reduce the incidental costs incurred and improve customer service in quality and performance. Observations and interviews were conducted and an analysis of the current situation was made. Waste was identified in the form of unnecessary transport, specifically in milk runs, where time was spent looking for materials to be loaded. This creates uncertainty and may contribute to increased costs and poor customer service. Three different options for a new replenishment system were developed which were compared with the theory and present situation. The proposal was evaluated with respect to cost, available support, complexity and future compatibility. The analysis of the theory and current state shows the importance of a long-term solution with few risks of waste. The solution that best cope with this is an e-Kanban system that automates the replenishment system and would make manual material call offs disappear completely. The conclusion is that an e-Kanban system is the best long term option for a manufacturing company like IAC because it is highly adaptable to change, and can be integrated in the company’s ERP system. The recommendation is to implement a new e-Kanban system. First, it should be tested on a pilot station and then introduced to the whole production process.
16

Preparação e caracterização de amidos termoplásticos / Preparation and characterization of termoplastic starches

Róz, Alessandra Luzia da 21 December 2004 (has links)
Este trabalho teve como objetivo estudar o processo de plasticização do amido via mistura física e por reação química para a produção de novos materiais. A plasticização via mistura física foi realizada empregando-se como agentes plasticização diferentes compostos hidroxilados. Os amidos termoplásticos (TPS) foram processadas em misturador intensivo a 150°C, a partir de misturas contendo de 15 a 40% de agente plasticizante. A plasticização via reação química foi realizada com isocianatos monofuncionais e difuncionais, os quais levaram a obtenção de produtos de enxertia e entrecruzamento, respectivamente. Os produtos obtidos foram caracterizados por difração de Raios X, Calorimetria Exploratória Diferencial (DSC), Termogravimetria (TG), Análise Dinâmico-Mecânica (DMA), Microscopia Eletrônica de Varredura (SEM) e Cromatografia de Permeação em Gel (HPSEC). O estudo dos diferentes plasticizantes propiciou a determinação das características que estas substâncias devem possuir para a preparação de amidos termoplásticos. O cisalhamento desenvolvido durante o processamento em misturador intensivo levou à perda da estrutura cristalina e à desestruturação dos grânulos de amido. O processamento do TPS em misturador intensivo não provoca mudanças significativas na massa molar do amido termoplasticizado. Os amidos termoplasticizados com sorbitol foram aqueles que apresentaram menores valores de absorção de água. Os valores de módulo de Young das amostras plasticizadas com propilenoglicol aumentaram com o aumento do conteúdo de plasticizante. Para as amostras plasticizadas com etilenoglicol o módulo aumenta até 30% de conteúdo de plasticizante, quando ocorre uma diminuição do valor do módulo. Os TPS plasticizados com propilenoglicol, 1, 4-butanodiol, sorbitol e dietilenoglicol apresentaram um aumento da temperatura de transição vítrea com o aumento do tero de plasticizante. Os diferentes TPS obtidos via mistura física apresentaram estabilidade térmica similares à exibida pelo amido in natura. As propriedades mecânicas destes materiais variaram de acordo com o tipo e a quantidade de plasticizante empregado. A análise dos produtos obtidos via reação química (amidos enxertados e entrecruzados) revelou que estas reações promoveram a desestruturação dos grânulos de amido e, independentemente do regente empregado, a modificação produziu derivados mais hidrofóbicos que o amido in natura. A reação do amido com o oligômero de poli-óxido de propileno tolueno di-isocianato permitiu a obtenção de um derivado com propriedades de material elastomérico e elevada capacidade de intumescimento. Os derivados enxertados ou entrecruzados apresentaram perda de cristalinidade, redução do caráter hidrofílico e estabilidades térmicas semelhantes à apresentada pelo amido in natura. / This main of this work was to study of the cornstarch granules plasticization by means of physical or chemical treatments in order to prepare new materials. The plasticization by physical processing was performed in an intensive mixer at 150°C using ditferent hydroxylated compounds as plasticizers. The production of thermoplastic starch (TPS) by chemical reaction was carried out using mono and di-isocyanates to obtain grafted and cross linked derivatives, respectively. All the products were characterized by X Ray Diffraction, Ditferential Scanning Calorimetry (DSC), Thermogravimetry (TG), Dynamical Mechanical Analysis (DMA), Scanning Electron Microscopy (SEM), High Pressure Size Exclusion Chromatography (HPSEC). The utilization of ditferent plasticizer permitted determining which characteristics the substances must present to be used in the TPS preparation. The shear developed in the processing step lead to the loss of crystalline pattern and disruption of the starch granules. The utilization of intensive mixer does not produce significant changes in the molar mass of the thermoplastic starch. TPS produced using sorbitol as plasticizer presented the lowest level of water uptake. The valous of Young modulus for TPS produced with propylene glycol increased with the content of plasticizer. To samples produced with ethylene glycol the values of Young modulus increased until 30% and after the modulus decrease. TPS prepared with propylene glycol, 1, 4-butanediol, sorbitol and diethyleneglycol showed an increase in the glass transition temperature with the increase in the plasticizer content. The ditferent TPS produced by physical mixture shoed thermal stabilities similar to the one exhibited by in natura starch. The mechanical properties of these materials were dependent of the type and amount of plasticizer. The analysis of the derivatives obtained by chemical reaction (grafted and cross linked) revealed the occurrence of disruption of the starch granules and, independent1y of isocyanate, the products presented higher hydrophobic character than that one presented by in natura starch. By reaction starch with propylene toluene polyoxide oligomer, it was obtained a derivative with elastomeric properties and high swelling capability. The grafted or cross linked derivatives showed loss of crystallinity, decrease in hydrophilic character, and thermal stability similar to the one exhibited by in natura starch.
17

An Experimental Investigation of the STOL Performance of Cal Poly's AMELIA in the NFAC

Lichtwardt, Jonathan Andrew 01 April 2013 (has links)
Results from Cal Poly's recent wind tunnel test, during the Winter of 2011-2012, in the 40- by 80-foot test section at the National Full-Scale Aerodynamics Complex (NFAC) at NASA Ames Research Center are presented. AMELIA, the Advanced Model for Extreme Lift and Improved Aeroacoustics, is the first full-span, cruise efficient, short take-off and landing (CESTOL) model incorporating leading- and trailing-edge blowing wing circulation control and over-the-wing mounted turbine propulsion simulators (TPS) to date. Testing of the 10 foot span model proved successful and was the result of a 5 year NASA Fundamental Aeronautics Program Research Announcement. The test generated extensive low-speed experimental aerodynamic and acoustic measurements. All of the results associated with Cal Poly's effort will be available in an open-source validation database with the goal of advancing the state-of-the-art in prediction capabilities for modeling aircraft with next generation technologies, focusing on NASA's N+2 generation goals. The model's modular design allowed for testing of 4 major configurations. Results from all configurations are presented. Out of a total of 292 data runs, 14 repeat run configurations were obtained. Overall repeatability of test data are good. Factors contributing to non-repeatability in the test data were assessed and showed high pressure air line temperature to be a primary factor. Test data shows drastic improvements in performance are obtained when incorporating leading edge blowing: wing stall can be delayed to more than 25 degrees angle-of-attack at lift coefficients exceeding six. Without the introduction of leading edge blowing to increase boundary layer momentum and maintain flow attachment around the leading edge, STOL performance suffers. Similar runs for isolated trailing edge blowing show a reduction in maximum lift coefficient to three with stall occurring at zero angle-of-attack. Testing at two engine pylon heights allowed for the highly coupled propulsion and flow control system to be characterized.
18

Ständiga förbättringar och praktisk problemlösning : en explorativ studie på Saab Automobile AB

Sefton, Martin January 2009 (has links)
<p>Continuous improvement is one of five principles in General Motors – Global Manufacturing System (GM-GMS). GM-GMS has been used by Saab Automobile AB since 2003 and is a central component for realisation of GM’s vision. Internal audits have discovered problems with one of the tools, practical problem solving (PPS), which needs to be improved. The department manufacturing of press and body (PK) wants to survey the problems and initiate a process of improvement. The purpose of this thesis work is to develop a foundation for future re-designs of the PPS process. Employees have been interviewed and observed in order to explore possible difference theoretical and practical problem solving with PPS. The result of the investigation shows 4 different and interrelated problem categories. 1. Information transfer, PPS hand over to product quality engineers (PQE) department cause problem when general assemblies (GA) are excluded from the improvement work. General assemblies do not get any feedback information from (PQE) about planed countermeasures. 2. Problem solving, team leaders has difficulties with identifying the true problem. Using “five-why” during the analysis work causes problem, since team leaders do not have the knowledge of how to use the tool in a proper way. 3. Documentation of PPS, the content in the PPS-form is a problem according to team leaders. Lack of knowledge and understanding of how to use the PPS-document leads to incomplete and incorrect analysis. 4. Coordination of involved people, support and help are missing from the management and quality engineer according team leaders. PPS from Global Costumer Audit are imposing time stress according to team leaders. Recommendations for further work is to investigate the opportunities with a web based PPS and process to improve information transfer and documentation of PPS. A second recommendation is to train and coach team leaders in problem solving and improve coordination of involved people and skills in problem solving.</p>
19

Ständiga förbättringar och praktisk problemlösning : en explorativ studie på Saab Automobile AB

Sefton, Martin January 2009 (has links)
Continuous improvement is one of five principles in General Motors – Global Manufacturing System (GM-GMS). GM-GMS has been used by Saab Automobile AB since 2003 and is a central component for realisation of GM’s vision. Internal audits have discovered problems with one of the tools, practical problem solving (PPS), which needs to be improved. The department manufacturing of press and body (PK) wants to survey the problems and initiate a process of improvement. The purpose of this thesis work is to develop a foundation for future re-designs of the PPS process. Employees have been interviewed and observed in order to explore possible difference theoretical and practical problem solving with PPS. The result of the investigation shows 4 different and interrelated problem categories. 1. Information transfer, PPS hand over to product quality engineers (PQE) department cause problem when general assemblies (GA) are excluded from the improvement work. General assemblies do not get any feedback information from (PQE) about planed countermeasures. 2. Problem solving, team leaders has difficulties with identifying the true problem. Using “five-why” during the analysis work causes problem, since team leaders do not have the knowledge of how to use the tool in a proper way. 3. Documentation of PPS, the content in the PPS-form is a problem according to team leaders. Lack of knowledge and understanding of how to use the PPS-document leads to incomplete and incorrect analysis. 4. Coordination of involved people, support and help are missing from the management and quality engineer according team leaders. PPS from Global Costumer Audit are imposing time stress according to team leaders. Recommendations for further work is to investigate the opportunities with a web based PPS and process to improve information transfer and documentation of PPS. A second recommendation is to train and coach team leaders in problem solving and improve coordination of involved people and skills in problem solving.
20

Lean : En fallstudie om Lean på Statoil

Choukeir, Tarek, Papadopoulos, Alexandra January 2011 (has links)
No description available.

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