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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

Gestão do risco de falha do preventor anular de BOP multiplexado submarino. / Risk management for annular preventer of multiplexed submarine bop.

Nikolas Lukin 19 May 2016 (has links)
Após o acidente de Macondo (EUA, 2010), cujo prejuízo estimado é da ordem de US$ 42 bilhões, a análise de risco do BOP (Preventor de BlowOut) ganhou grande importância nos projetos de exploração e desenvolvimento de petróleo. O presente trabalho se aprofundou na análise de risco de falha no acionamento do preventor anular de BOP (uma das funções do BOP), mapeando a sensibilidade da manutenção, redundâncias do projeto e da vida útil dos componentes no risco de falha inerente ao seu funcionamento. Este estudo seguiu os fundamentos da inspeção baseada no risco e da manutenção centrada na confiabilidade, a partir das diretrizes das normas ISO 31.000 (gestão do risco) e API 581 (inspeção baseada no risco). Um modelo de confiabilidade foi construído com base na árvore de falhas do equipamento, a qual, por sua vez, foi construída com base no diagrama hidráulico do sistema e do respectivo FMEA (Failure Mode and Effect Analysis). Neste modelo, pressupõe-se uma taxa de falhas constante dos componentes ao longo do tempo para calcular o tempo médio entre falhas do sistema. O trabalho atendeu seus objetivos ao comprovar que o modelo numérico de confiabilidade é aderente às falhas de campo e da literatura. A análise de sensibilidade do modelo por meio da simulação numérica, mostrou que o aumento da qualidade das manutenções preventiva é a melhor estratégia para reduzir o risco de falha do BOP anular. Verificou-se ainda que o aumento da vida útil de alguns componentes é tão relevante quanto o incremento de redundâncias para a confiabilidade do BOP anular. / After Macondo accident (USA, April 2010), with an estimated loss of US $ 42 billion, the failure risk analysis of the BOP (BlowOut Preventor) gained great importance in oil exploration and development projects. This work has deepened in BOP annular preventer (one of BOP functions) failure risk analysis, mapping sensitivity of maintenance of its components in the probability of equipment failure, according to the guidelines of RBI techniques (Risk Based Inspection) and RCM (Reliability Centered Maintenance). Therefore, the methodology used is proposed by API 580 (2009) and API 581 (2008) standards of risk based inspection applied on a reliability model of annular BOP. This reliability model, in turn, was based on fault tree analysis (FTA) and FMEA (Failure Mode and Effect Analysis) over the equipment hydraulic diagram. As hypothesis, it is assumed a constant failure rate of components over time, in order to calculate the mean time between failures. It was proved that reliability calculated by numerical model is coherent to field failures observations and literature data. The sensitivity analysis by numerical simulation shows that improving inspections and preventive maintenance quality in some of BOP components can markedly reduce the risk of failure of annular BOP.
12

A Study of Innovation and Quality in the Automotive Industry

Lin, Liang-Hung 21 December 2004 (has links)
Over the past decade, new approaches to innovation management have become prime drivers of various industries. Considering product quality, product innovation and service innovation in the automotive industry, this study tries to adopt game theory and real option models to analyze competing and consuming behavior among high- quality firms, low-quality firms and rational consumers. With an argument that firms will undertake innovation activities if they produce high-quality products, this study wishes to demonstrate that high quality products will induce both product and service innovations simultaneously. To achieve the research objective, this study divides innovation into product and service innovations, and then, discusses quality¡¦s impacts on product and service innovations separately. Game theory models concerning quality and product innovation indicate that the fixed cost of innovation, the barrier to a firm¡¦s engaging in innovative activities, is overcome only if a firm produces high-quality products. Moreover, another dynamic game also shows the strong relationship between product quality and service innovation. Applying real options models to evaluate service innovations in the automotive industry, including half-price purchase warranty and extended test drive service, also verify that effective service innovations might increase consumer willing-to-buy and enlarge the sales and profits for the innovative firms. Besides quality, this study also reveals that consumer preference to new product or service is another key successful factor for business innovation management. Successful innovation management depends on continuously improving product and service, concerning the status of expected market, and understanding the needs of potential consumers. Even though a general consensus on product and service innovations among different industries remains lacking, this study strongly supports the argument that firms producing high-quality products will be active in innovations. From the broader perspective of process management, total quality management, which increases product quality, undoubtedly supports innovation management.
13

Online Grocery shopping in Sweden : Identifying key factors towards consumer’s inclination to buy food online. Lessons learned from Västerås

Phoosangthong, Nakkarin, Cimana, Emmanuel January 2013 (has links)
The purpose of this master thesis is to identify factors influencing consumer’s intention to use Internet when buying food online. The focal aspects of the study will be service and product quality in order to assess their influence on the consumer’s intention to buy food online.
14

Strategies for Utilization of By-product Resources as Ruminant Feeds / 反芻家畜用飼料としての副産物資材の利用方策

Ishida, Kyohei 23 March 2020 (has links)
京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13338号 / 論農博第2881号 / 新制||農||1079(附属図書館) / 学位論文||R2||N5245(農学部図書室) / (主査)教授 廣岡 博之, 教授 松井 徹, 准教授 熊谷 元 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
15

Buyer-supplier commitment and competitive performance among small and medium enterprises in Southern Gauteng

Nwele, Uju Kingsley January 2020 (has links)
M. Tech. (Department of Logistics Management, Faculty of Management Sciences), Vaal University of Technology. / Economic growth, job creation and improved standard of living have resulted to focus mostly on small and medium enterprises (SMEs) across the world. Hence, establishing and maintaining relationships with partners across the supply chain has become a prerequisite for achieving long-term competitive benefits in the present business competitive environment. For this reason, buyer-supplier commitment is deemed an important long-term business relationship strategy towards achieving competitive performance. Although buyer-supplier commitments can serve as the basis for the development of relational standards, unbalanced commitments, on the other hand, may become a harbinger of opportunistic behaviours. This development is inimical to continued business relationship and its consequential benefits for the SMEs’ supply chain collaborators. Guided by the theoretical lens of the social exchange theory (SET), this study examines the influence of communication, product quality, flexibility, and buyer-supplier commitments on SMEs competitive performance in southern Gauteng. Using a convenience sampling technique, the study quantitatively analysed the 396 returned questionnaires. Data analysis was conducted using the statistical package for social sciences (SPSS) version 25.0 and AMOS 25.0 for the confirmatory factor analysis and the structural equation modelling (SEM) respectively. The SEM analysis helped to confirm the suitability of the model fit as well as the positive and significant relationships of the proposed hypotheses. The analysis revealed that communication, product quality and flexibility are important variables in predicting buyer-supplier commitment as they displayed positive association with buyer-supplier commitment and the latter is significant in a firm’s effort towards achieving competitive performance. The study recommends the anchoring of SMEs strategies on commitment inorder for partners to efficiently and effectively enjoy competitive benefits. This research contributes new knowledge to the body of literature by developing a research framework on SME’s business growth and competitive performance and offered recommendations based on the study, which if implemented, could improve the economy. The study also revealed a higher relationship among the baseline constructs (communication, product quality and flexibility) which have received little or no conceptualisation in literature.
16

A holistic approach to injection moulding optimisation for product quality and cost through the characterisation of reprocessed polymeric materials and process monitoring : experimental evaluations and statistical analysis of multiple reprocessing of unfilled and short glass fibre filled polypropylene materials : an optimised methodology to realise minimum product cost at an acceptable product quality

Elsheikhi, Salah A. January 2011 (has links)
The plastics industry is one of the fastest growing major industries in the world. There is an increase in the amount of plastic used for all types of products due to its light weight and ability to reprocess. For this reason, the reprocessing of thermoplastics and the usability of reprocessed materials are gaining significance, and it is important to produce and consume plastic materials in an environmentally friendly way. In addition, rising raw material cost linked to the increased oil prices encouraged for reusing of the plastic materials. The aim of this research was to study and optimize the injection moulding process parameters to achieve a trade-off between the product cost and product quality, measured through mechanical properties and geometry, based on using regrind ratios. The work was underpinned by a comprehensive study of multiple reprocessing effects in order to evaluate the effect of process parameters, material behaviour, reprocessing effects and possible links between the processing parameters and key properties. Experimental investigations were carried out, in particular, focused on the melt preparation phase to identify key process parameters and settings. Multiple reprocessing stages were carried out; using two types of PP material: unfilled and short glass filled. A series of tests were used to examine product quality (mass, colour and shrinkage) and physical properties (density, crystallinity, thermal stability, fibre length, molecular weight, in-line and off-line viscosity, tensile strength, modulus of elasticity, elongation (%) and flexural strength). This investigation showed that the mouldability of the filled and unfilled PP materials, through the successive reprocessing stages (using 100 % regrind), was observed to be relatively consistent. Given the link between the processing parameters and key product and material properties, it is possible to manufacture products with minimal loss to part quality and mechanical properties. The final phase of the work focused on process optimisation study for short glass fibre filled PP material and the identified key process parameters (melt temperature, screw rotational speed, holding pressure, holding time and injection rate). A response surface experiment was planned and carried out for three reprocessing stages (0 %, 25 % and 50 % regrind). The fitted response surface models were utilised to carry out the trade-off analysis between the operating cost (material cost, energy cost and labour cost) and product quality (dimensions and tensile strength) Based on the optimal moulding conditions, the operating cost was reduced (from stage I as a reference), by 24% and 30 % for stage II and stage III respectively. A small, perhaps undetectable, change in product dimensions was noted. In addition, a small reduction in tensile strength was noted (from stage I as a reference), by 0.4% and 0.1 % for stage II and stage III respectively. The same data was applied in other countries (Australia, USA, Brazil, Libya and China) to manufacture the same product; and it was observed that the cost was reduced with increasing of regrind ratio. But the significant reduction of the cost, essentially, depended on those countries which have low wage rates (e.g. Brazil, Libya and China). For example, the cost of moulded product manufactured in China is £ 0.025 (using 50% of regrind), while the cost of the same product produced in Australia is £ 0.12, hence giving a total saving of 79 % and making it a valuable issue to be considered in industry.
17

Can Competition Keep the Restrooms Clean? Price, Quality and Spatial Competition

Pennerstorfer, Dieter 05 1900 (has links) (PDF)
This article investigates the influence of competition on price and product quality among Austrian camping sites, a market characterized by both horizontal (spatial) and vertical product differentiation. Theoretically, the effect of competition on quality is ambiguous and depends on the degree of cost substitutability between output and quality. Estimating a system of equations shows that intense competition has a positive impact on product quality and a negative effect on prices (conditional on quality). As high quality is associated with high prices, the total effect of competition on prices is rather small.
18

Proposition d’une méthodologie d’évaluation de l’évolution de la qualité en conception de systèmes complexes / Proposal of a methodology to evaluate quality evolution in complex system design

Gitto, Jean-Philippe 02 February 2018 (has links)
La maîtrise de la qualité est aujourd’hui indispensable pour satisfaire les exigences des clients. Bien qu’il existe différentes méthodes et outils spécialement développés pour manager la qualité des systèmes ou des processus au sein des entreprises, il est difficile d’établir le lien entre la maîtrise des nombreux processus d’une entreprise et la qualité produit pour un système en service. Dans ce contexte, une thèse CIFRE a été menée au sein de MBDA, entreprise qui conçoit, développe et produit des systèmes d’armes. La problématique de cette thèse est de développer une méthodologie permettant de produire une définition de la qualité produit d’un système complexe qui soit valable tout au long de son cycle de vie, et permettant la construction de modèles de prévision de la qualité produit en utilisation lors du développement et de la production. Notre contribution consiste en une méthodologie en deux phases. La première phase permet d’établir une définition de la qualité produit des systèmes complexes du point de vue du client adaptée au contexte industriel en définissant plusieurs facteurs qualité produit qui soit valable pour toutes les phases du cycle de vie des systèmes. La deuxième phase permet de construire des modèles de prévision de la qualité produit qui permettent d’obtenir une évaluation de la qualité tout au long du cycle de vie des systèmes et d’établir une prévision de ce que sera la qualité en utilisation. Les deux phases de la méthodologie reposent sur l’exploitation d’avis d’experts afin de permettre son utilisation sans disposer d’une quantité importante de données. Les modèles construits ont été testés pour des systèmes développés par MBDA. / Today, quality control is essential to satisfy customer requirements. Although there are different methods and tools specially developed to manage the quality of systems or processes within companies, it is difficult to establish the link between management of a company's many processes and product quality for a system in service. In this context, a CIFRE thesis was conducted within MBDA, a company that designs, develops and produces weapons systems. The problem of this thesis is to develop a methodology allowing to produce a definition of the product quality of a complex system which is valid throughout its life cycle, and allowing the construction of models to predict the product quality in use during development and production. Our contribution consists of a two-phase methodology. The first phase makes it possible to establish a definition of the product quality of complex systems from the customer's point of view adapted to the industrial context by defining several product quality factors that are relevant for all phases of the systems life cycle. The second phase builds product quality prediction models that provide a life-cycle quality assessment of the systems and a forecast of what the quality will be in use. Both phases of the methodology rely on the use of experts' judgement to enable its use without a significant amount of data. The models built have been tested for systems developed by MBDA.
19

Effects of Prescribed Fire on Timber Quality and Tree Value in the Central Hardwood Region

David Paul Mann (7471193) 17 October 2019 (has links)
<div>Prescribed fire is one of the most useful tools available to forest managers attempting to maintain oak-hickory forests in the Central Hardwood Region. Prescribed fire can be useful in promoting regeneration of desirable species groups like oak (Quercus spp.) and hickory (Carya spp.) by preparing the seedbed, managing competition, and creating canopy gaps. The use of prescribed fire has been limited by concerns regarding the effect of the practice on standing timber. A perception of strong negative effects to tree-quality and tree-value from fire originated largely from sometimes deleterious effects of wildfire on timber. Less research exists demonstrating the potential effects of controlled, prescribed burning on timber quality and value. Furthermore, most research that exists focuses on individual tree characteristics, and is often focused on a relatively small geographic areas.</div><div><br></div><div>I conducted a regional study on the effects of prescribed fire on timber quality across a gradient of the Central Hardwood Region, ranging from the Missouri Ozarks to the Appalachian foothills. I studied 139 stands in selected prescribed fire units and control sites in Mark Twain National Forest (MO), Hoosier National Forest (IN), Wayne National Forest (OH) and Daniel Boone National Forest (KY). Selected stands were dominated by hardwoods species and had variable prescribed fire histories, ranging from 0 to 6 prescribed fires. </div><div><br></div><div>Measurements were taken concurrently across this plot network for two studies. First, we assessed the estimated effect of prescribed fire on stumpage value, and secondly, we assessed wounding patterns and effects of prescribed fire on tree-quality. Loss in estimated stumpage value from prescribed fire averaged approximately 4.2% across all measured stands. Estimated loss in stumpage value varied significantly by the number of prescribed fires in the last 30 years, with increasing numbers of prescribed fires leading to higher estimated losses in stumpage value. Further, stands in Mark Twain National Forest exhibited higher estimated loss in stumpage value, exceeding 10% on average. Stands in Hoosier, Wayne, and Daniel Boone National Forest only rarely exceed 5% losses in estimated stumpage value, and averaged less than 3%. </div><div><br></div><div>Approximately 25% of trees had at least one wound associated with prescribed fire across all study sites, while approximately 5% of trees experienced a reduction in tree quality (as measured by United States Forest Service tree grade) from prescribed fire. Both the rate of wounding and rate of tree grade reduction increased with increasing numbers of prescribed fires. Stands in the western portion of the Central Hardwood Region (Hoosier and Mark Twain National Forest) exhibiting higher rates of wounding from fire compared to eastern sites (Wayne and Daniel Boone National Forest.)</div><div><br></div><div>Effects of wounding varied significantly by type of wound. Catfaces accounted for far more volume loss and reduction in tree grade than any other wound type. Alternatively, some wound types, like seams and bark slough, caused minimal tree-quality and tree-volume effects. Effects also varied by species, with higher wounding effects on sugar maple and red oak, and relatively low effects on white oak and yellow-poplar. </div><div><br></div>
20

Effects on product quality for probiotic yoghurts caused by long storage times during production

Larsson, Catrine January 2009 (has links)
<p>Recent years there has been a large increase in the worldwide sales of cultured products containing probiotics. The obstacle in the production of fermented products incubated with probiotic strains is its effect on sensory, chemical and physical properties. This Master´s Thesis investigates how extended storage times in fermentation tank as well as buffer tank during production of probiotic yoghurts affect final product quality. Through experimental studies, maximum storage times for probiotic yoghurts were to be recommended. The study includes analyses of pH, viscosity, stability, acetic acid concentration, microbial viability and sensory evaluations.</p><p>Design of experiments (DOE) was used to construct a 3<sup>2</sup>-factorial design for the experiment where different storage times were tested. The analyses showed that:</p><ul><li>pH decreases with both storage time in fermentation tank and buffer tank.</li><li>Viscosity increases with long storage times in fermentation tank, while it decreases with long storage times in buffer tanks.</li><li>Many samples had a sandy/grainy and slimy texture which could be related to high levels of Bifidobacteria or high fermentation temperatures.</li><li>High levels of acetic acid was found in all samples.</li><li>All measurements data where within the specification limits, whereas no recommendation for maximum storage times during production could be given.</li></ul>

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