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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.
101

Leveraged Plans for Measurement System Assessment

Browne, Ryan January 2009 (has links)
In manufacturing, measurement systems are used to control processes and inspect parts with the goal of producing high quality product for the customer. Modern Quality Systems require the periodic assessment of key measurement systems to ensure that they are functioning as expected. Estimating the proportion of the process variation due to the measurement system is an important part of these assessments. The measurement system may be simple, for example, with one gauge automatically measuring a single characteristic on every part or complex with multiple characteristics, gauges, operators etc. Traditional assessment plans involve selecting a random sample of parts and then repeatedly measuring each part under a variety of conditions that depend on the complexity of the measurement system. In this thesis, we propose new plans for assessing the measurement system variation based on the concept of leveraging. In a leveraged plan, we select parts (non-randomly) with extreme initial values to measure repeatedly. Depending on the context, parts with initial measurements may be available from regular production or from a specially conducted baseline study. We use the term leveraging because of the re-use of parts with extreme values. The term leverage has been used by the  proponents of the problem solving system initially proposed by Dorian  Shainin. Parts with relatively large and small values of the response  are compared to identify the major causes of the variation. There is no discussion of the theory of leveraging in the literature or its application to measurement system  assessment. In this thesis, we provide motivation for why leveraging  is valuable and apply it to measurement system  assessments. We consider three common contexts in the thesis: Simple measurement systems with one gauge, no operator effects and no external information about the process performance; Measurement systems, as stated above, where we have external information, as would be the case, for example, if the measurement system was used for 100% inspection; Measurement systems with multiple operators. For each of these contexts, we develop new leveraged assessment plans and show that these plans are substantially more efficient than traditional plans in estimating the proportion of the process variation due to the measurement system. In each case, we also provide methodology for planning the leveraged study and for analysing the data generated. We then develop another new application of leveraging in the assessment of a measurement system used for 100% inspection. A common practice is to re-measure all parts with a first  measurement outside of inspection limits. We propose using these repeated measurements to assess the variation in the measurement system. Here the system itself does the leveraging since we have repeated measurements only on relatively large or small parts. We recommend using maximum likelihood estimation but we show that the ANOVA estimator, although  biased, is comparable to the MLE when the measurement system is reliable.  We also provide guidelines on how to schedule such assessments. To outline the thesis, in the first two chapters, we review the contexts described above. For each context, we discuss how to characterize the measurement system performance, the common assessment plans and their analysis. In Chapter 3, we introduce the concept of leveraging and provide motivation for why it is effective. Chapters 4 to 7 contain the bulk of the new results in the thesis. In Chapters 4, 5 and 6, which correspond to the three contexts described above, we provide new leveraged plans, show their superiority to the standard plans and provide a methodology to help design leveraged plans. In Chapter 7, we show how to assess an inspection system using repeated measurements on initially rejected parts. In the final chapter, we discuss other potential applications of leveraging to other measurement system assessment problems and to a problem in genetics.
102

Leveraged Plans for Measurement System Assessment

Browne, Ryan January 2009 (has links)
In manufacturing, measurement systems are used to control processes and inspect parts with the goal of producing high quality product for the customer. Modern Quality Systems require the periodic assessment of key measurement systems to ensure that they are functioning as expected. Estimating the proportion of the process variation due to the measurement system is an important part of these assessments. The measurement system may be simple, for example, with one gauge automatically measuring a single characteristic on every part or complex with multiple characteristics, gauges, operators etc. Traditional assessment plans involve selecting a random sample of parts and then repeatedly measuring each part under a variety of conditions that depend on the complexity of the measurement system. In this thesis, we propose new plans for assessing the measurement system variation based on the concept of leveraging. In a leveraged plan, we select parts (non-randomly) with extreme initial values to measure repeatedly. Depending on the context, parts with initial measurements may be available from regular production or from a specially conducted baseline study. We use the term leveraging because of the re-use of parts with extreme values. The term leverage has been used by the  proponents of the problem solving system initially proposed by Dorian  Shainin. Parts with relatively large and small values of the response  are compared to identify the major causes of the variation. There is no discussion of the theory of leveraging in the literature or its application to measurement system  assessment. In this thesis, we provide motivation for why leveraging  is valuable and apply it to measurement system  assessments. We consider three common contexts in the thesis: Simple measurement systems with one gauge, no operator effects and no external information about the process performance; Measurement systems, as stated above, where we have external information, as would be the case, for example, if the measurement system was used for 100% inspection; Measurement systems with multiple operators. For each of these contexts, we develop new leveraged assessment plans and show that these plans are substantially more efficient than traditional plans in estimating the proportion of the process variation due to the measurement system. In each case, we also provide methodology for planning the leveraged study and for analysing the data generated. We then develop another new application of leveraging in the assessment of a measurement system used for 100% inspection. A common practice is to re-measure all parts with a first  measurement outside of inspection limits. We propose using these repeated measurements to assess the variation in the measurement system. Here the system itself does the leveraging since we have repeated measurements only on relatively large or small parts. We recommend using maximum likelihood estimation but we show that the ANOVA estimator, although  biased, is comparable to the MLE when the measurement system is reliable.  We also provide guidelines on how to schedule such assessments. To outline the thesis, in the first two chapters, we review the contexts described above. For each context, we discuss how to characterize the measurement system performance, the common assessment plans and their analysis. In Chapter 3, we introduce the concept of leveraging and provide motivation for why it is effective. Chapters 4 to 7 contain the bulk of the new results in the thesis. In Chapters 4, 5 and 6, which correspond to the three contexts described above, we provide new leveraged plans, show their superiority to the standard plans and provide a methodology to help design leveraged plans. In Chapter 7, we show how to assess an inspection system using repeated measurements on initially rejected parts. In the final chapter, we discuss other potential applications of leveraging to other measurement system assessment problems and to a problem in genetics.
103

Effekter på smärta och hälsa av akupunkturbehandling hos personer med fibromyalgi : En litteraturstudie

Andersson, Emelie, Lagerbäck, Sandra January 2011 (has links)
I världen lever cirka 3-5 procent av befolkningen med det långvariga smärtsyndromet fibromyalgi. Det är svårt att finna behandlingar mot fibromyalgi då det inte finns någon vetenskap om vad som orsakar syndromet. Syftet med föreliggande litteraturstudie var att beskriva effekterna på smärta och hälsa av akupunkturbehandling hos personer med fibromyalgi samt beskriva kvaliteten av de valda artiklarnas metod. Studien utformades med en deskriptiv design där 11 vetenskapliga artiklar inkluderades och sammanställdes. Litteratursökningarna utfördes i databaserna Medline (PubMed) samt Cinahl. Resultatet visade att akupunktur gav positiva kortsiktiga effekter på smärta och hälsa i kombination med farmakologisk behandling hos personer med fibromyalgi. Däremot var långtidseffekten av akupunktur inte betydande effektiv. Placebo visade sig även ge en god effekt. Akupunktur gav betydande minskning av smärta genom en förhöjd aktivering av endogena opioidreceptorer samt genom ökat blodflöde i hud och muskler. Slutsatsen av studien var att akupunktur med fördel kan användas tillsammans med farmakologisk behandling till personer med fibromyalgi. För att kunna ge en god omvårdnad är det viktigt att få kunskap och förståelse om akupunktur som behandlingsmetod till denna population. För att dra några slutsatser om akupunktur kan ge några långsiktiga effekter behövs mer forskning inom området.
104

Application of kinetic isotope effects and theoretical calculations to interesting reaction mechanisms

Hirschi, Jennifer Sue 15 May 2009 (has links)
A variety of biological and organic reaction mechanisms are studied using powerful tools from experimental and theoretical chemistry. These tools include the precise measurement of kinetic isotope effects (KIEs) and the use of theoretical calculations to predict KIEs as well as determine factors that contribute to reaction acceleration and selectivity. Theoretical analysis of the Swain-Schaad relationship involves the prediction of a large number of isotope effects and establishes the semiclassical boundaries of the relationship. Studies on the mechanism of oxidosqualene cyclase involve the determination of a large number of precise KIEs simultaneously. Transition state models for the Sharpless asymmetric epoxidation have been developed that explain the versatility, high selectivities, and ligand accelerated catalysis of the reaction. Theoretical predictions on the proposed enzymatic mechanism of flavin dependent amine oxidation suggest a hydride transfer mechanism and rules out mechanisms involving covalent intermediates. Finally, a theoretical analysis of Diels-Alder reactions successfully describes the unexpected exo selectivity in some of these reactions.
105

The experimental and theoretical determination of combinatorial kinetic isotope effects for mechanistic analysis

Christian, Chad F. 15 May 2009 (has links)
Unfortunately, chemists can never experimentally unravel a full reaction pathway. Even our ability to define key aspects of mechanisms, such as short-lived intermediates and the even more ephemeral transition states, is quite limited, requiring subtle experiments and subtle interpretations. Arguably the most important knowledge to be gained about the mechanism of a reaction is the structure and geometry of the transition state at the rate-limiting step, as this is where a reaction’s rate and selectivity are generally decided. The Singleton group has developed a methodology for predicting the combinatorial kinetic isotope effects (KIEs) at every atomic position, typically carbon or hydrogen, at natural abundance. A combination of experimental isotope effects and density functional theory (DFT) calculations has greatly aided our ability to predict and understand a reaction’s pathway and transition state geometries. Precise application of this method has allowed for the mechanistic investigation of a myriad of bioorganic, organic, and organometallic reactions. The technique has been applied in the analysis of the catalytic borylation of arenes via C-H bond activation, dynamic effects in the enyne allene cyclization, palladium catalyzed allylic alkylation, the nature of proton transfer in orotate decarboxylase, and the epoxidation of enones with t-butyl hydroperoxide.
106

Cross-cultural effects of casualties on foreign policy decision making: South Korea and the United States

Park, Nam Tae 02 June 2009 (has links)
It is well accepted that casualties incurred as a result of interstate militarized disputes have a significant influence on domestic public opinion and ultimately on foreign policy decision making (FPDM). Although scholars have studied the influence of casualties on FPDM, the major line of research ignores the possibility that different cultural settings may generate different levels of tolerance for human casualties and thereby differentially mediate public reactions. Therefore, I attempt to clarify the impact of cultural factors on interpretation and perception of human casualties in international conflicts by the general public and their implications on consequent foreign policy choices. I specifically examine two socio-cultural factors in the context of two culturally different states, South Korea and the United States. The two cultural factors are (1) the level of individualism vs. collectivism, and (2) the degree of ambiguity intolerance. I argue that the two factors will possibly affect the public’s tolerance of human casualties. I expect that they will affect both the process by which members of the two cultures make decisions and their choices. Cross-national experimental design (in South Korea and the United States) and a comparative case study were employed. Regarding the decision choice, I found that the expected number of casualties were considered in different ways by American students and Korean students. Different from my expectation, the Korean students perceived the expected number of casualties more negatively than the American students. With regard to the process of decision making, the empirical results support the hypotheses that the different levels of intolerance of ambiguity, a cultural factor, will have an impact on the decision process. Specifically, Korean students, who are less tolerant of ambiguity, needed less information to reach a final decision than did American students. Overall, although the results did not completely support cultural accounts, cultural explanation has been proven to be a viable ingredient in explaining the different observed patterns of foreign policy decision making. Specifically, a cultural factor, ambiguity intolerance, had an impact on the process rather than the choice. In addition, this study presents some theoretical implications as well as political implications.
107

The advertising effects of Expriential Marketing--An example of Nike's advertisement

Wu, Yi-hua 03 August 2004 (has links)
NONE
108

Control and Observation of Solution Phase Dye Molecules Aggregation Effects

Hsu, Guo-cheng 29 July 2008 (has links)
Luminescent properties of the dye molecules can be influenced by the environments as well as intermolecular interactions. Suitable control the aggregation can be useful for optoelectronic device applications. In this thesis, we investigate the spectroscopic properties of dye molecule, DiI_C18, in solutions. Solvents and concentrations are used to control the degree of aggregation. Absorption and emission are used to probe the properties. We use water, methanol, and ethylene glycol as key solvents to control the aggregation effects, especially the methanol solution mixing with water. As the concentration increased, the change of the absorption spectra are observed, which is caused by the aggregation between molecules. Two types of aggregations: head-to-tail structure and parallel structure, are proposed. Head-to-tail structure behaves red-shifted spectrum, and a corresponding shorter decay lifetime. On the contrary, parallel structure aggregation exhibits blue-shifted absorption spectrum and a longer fluorescence lifetime. Both structures are observed at different period after mixing. Only monomer exists in the methanol solution, even at high concentration. However, after missing with water, parallel structure aggregates are formed. Head-to-tail structure aggregates are formed after a much longer period, usually several hours after the mixing. These aggregates not only have different photo-physical properties. After high light intensity illumination, parallel structures are easier to turn into non-fluorescent structures, while head-to-tail structures last a longer period. Monomer structures exhibit the longest period. This provides additional evidence for the formation of different structures in the mixing solutions.
109

Receptivity of Boundary Layers under Pressure Gradient

Schrader, Lars-Uve January 2008 (has links)
<p>Boundary-layer flow over bodies such as aircraft wings or turbine blades is characterized by a pressure gradient due to the curved surface of the body. The boundary layer may experience modal and non-modal instability, and the type of dominant instability depends on whether the body is swept with respect to the oncoming flow or not. The growth of these disturbances causes transition of the boundary-layer flow to turbulence. Provided that they are convective in nature, the instabilities will only arise and persist if the boundary layer is continuously exposed to a perturbation environment. This may for example consist of turbulent fluctuations or sound waves in the free stream or of non-uniformities on the surface of the body. In engineering, it is of relevance to understand how susceptive to such perturbations the boundary layer is, and this issue is subject of <em>receptivity analysis</em>.</p><p> </p><p>In this thesis, receptivity of simplified prototypes for flow past a wing is studied. In particular, the three-dimensional swept-plate boundary layer and the boundary layer forming on a flat plate with elliptic leading edge are considered. The response of the boundary layer to vortical free-stream disturbances and surface roughness is analyzed, receptivity mechanisms are identified and their efficiency is quantified.</p> / 76218 VR Receptivity
110

Galvanomagnetic size effects in polycrystalline metal films.

Wong, Wing-hong, January 1973 (has links)
Thesis--Ph. D., University of Hong Kong. / Typewritten.

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