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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.
541

Multiphase flow measurement using gamma-based techniques

Arubi, Isaac Marcus Tesi January 2011 (has links)
The oil and gas industry need for high performing and low cost multiphase meters is ever more justified given the rapid depletion of conventional oil reserves. This has led oil companies to develop smaller/marginal fields and reservoirs in remote locations and deep offshore, thereby placing great demands for compact and more cost effective soluti8ons of on-line continuous multiphase flow measurement. The pattern recognition approach for clamp-on multiphase measurement employed in this research study provides one means for meeting this need. Cont/d.
542

INSTITUTIONAL LENDING MODELS, MISSION DRIFT, AND MICROFINANCE INSTITUTIONS

Paris, Bethany L 01 January 2013 (has links)
Microfinance is a development tool used to reduce poverty among extremely poor households. Impoverished households can access lines of credit through microfinance institutions (MFIs), in order to create a new business, smooth household consumption, fund medical emergencies, etc. Many authors postulate that MFIs are drifting from a welfarist to an institutionalist approach to lending. Using MIXMarket data on specific MFIs in 118 countries between 1995 and 2011, the average loan balance of these organizations will be regressed against measure of outreach and sustainability of these institutions by charter type through a series of four, fixed effects models. The main research question is: given that a positive, overall shift in average loan balance indicates an institutionalist shift in mission, how does this impact microfinance institutions and the demographics they target on the intensive and extensive margins? These analyses will test the theory that MFIs with larger average loan balances serve households closer to the subsistence poverty level, a manifestation of mission drift toward the institutionalist philosophy of lending. The phenomenon of mission drift directly impacts the outcomes of microfinance institutions and the target demographic of the organization. The results of this study indicate that the mission of these organizations is drifting toward the institutionalist philosophy of lending. With this general result, mission drift can be observed within both the internal and external margins of the microfinance industry, which influences the chosen target market, profit generated, and structure of MFIs, as determined by the mission of the organization.
543

La mise au point de méthodes thermiques et spectrométriques pour la caractérisation des catalyseurs pour le stockage de CO2

Benevides Ferreira, José Flavio 02 July 2013 (has links) (PDF)
La capture de CO2 par adsorption sur des solides poreux (adsorbants) est une alternative prometteuse en raison de sa sélectivité et de sa faible consommation d'énergie. Nous avons étudié l'adsorption in-situ de CO2 sur des adsorbants solides en combinant la spectroscopie infrarouge par réflexion diffuse (DRIFT) avec la thermographie infrarouge afin de mieux comprendre les mécanismes d'interaction CO2-adsorbant et ainsi optimiser sa captation dans des procédés de capture en post-combustion. La thermographie IR est utilisée pour détecter la source de chaleur transitoire provenant de la surface de l'adsorbant au cours de l'adsorption de CO2. Un modèle de transfert de chaleur a été développé afin d'estimer les chaleurs d'adsorption. Un mini réacteur conçu pour la DRIFT nous a permis d'identifier les espèces adsorbées et d'étudier leur évolution sur la surface de l'adsorbant selon la température et l'atmosphère environnante. Enfin, le couplage d'informations provenant des deux approches nous a permis l'investigation haut-débit des paramètres clefs pour le choix des adsorbants les plus performants.
544

Utformning av sidoområden med hänsyn till vägens livscykelkostnad

Sandercock, Alexander January 2013 (has links)
Single vehicle accidents are one of the most common types of accidents that occur on the Swedish road network. Depending on the design of the road, the presence of a crash barrier and embankment on the roadside, the outcome of a roadside collision can lead to serious injuries and even deaths.The aim of this project is to investigate the possibility of improving road safety by designing the optimal roadside area based on the results of a life cycle cost analysis (LCC).The questions that have been answered during the duration of this project are: 1) Describe the current technical solutions for roadside area design and the various barrier types used in Sweden.2) Complete an existing mathematical model that has been developed by Hawzheen Karim, for calculating life-cycle costs for various roadside areas.3) Calculate and compare the life cycle costs for the side area with a barrier and without a barrier. By performing an analysis of the documentation on the current guidelines and rules for shaping the roadside, was it possible to describe the current technical solutions for the formation the roadside as well as the current roadside barriers in use today. A mathematical model for calculating the life cycle costs of different barrier types had already been developed by Hawzheen Karim. This model was supplemented so that it could calculate life-cycle costs of the roadside region with and without a barrier. After the model was completed, an analysis was performed to obtain life-cycle costs of a roadside with and without a barrier.The result showed that there is a clear relationship between the slope inclination, fill height, and the rate at which the costs rise. This breakpoint is highly dependent on several factors such as the price of land, the presence of bedrock in the construction process and if the ballast material needs to be treated. A flatter slope causes an increase in both the volume of material and the area of land that needs to be obtained, while a steep slope with a barrier may result in higher costs to society due to fatal collisions with the barrier and higher operating and maintenance costs. / Singelolyckor är en av de vanligaste olyckstyperna som förekommer på det svenska vägnätet. Beroende på utformningen av vägen, förekomsten av vägräcke och slänten på sidoområdet kan förloppet av en avkörningsolycka leda till svåra skador och även dödsfall. Syftet med detta projektet är att undersöka möjligheten att öka trafiksäkerheten genom att utforma det optimala sidoområdet baserat på en livscykelkostnadsanalys (LCC-analys).De frågeställningar som har besvarats under projektets utförande är: 1) Beskriv de nuvarande tekniska lösningar för sidoområdets utformning och de olika typer av räcken som används i Sverige.2) Komplettera en befintlig matematisk modell som har tagits fram av Hawzheen Karim, för beräkningar av livscykelkostnader för olika sidoområden.3) Beräkna och jämför livscykelkostnader för sidoområdet med räcken och utan räcken. Genom att utföra en dokumentanalys på de nuvarande riktlinjer och bestämmelser kunde alla nuvarande tekniska lösningar för sidområdets utformning och olika räckestyper beskrivas. De nuvarande tekniska lösningar som finns för att utforma sidoområden är både enkla och mycket effektiva, och riktlinjerna som finns för utformning av sidoområden är också omfattande och lätta att förstå.En matematisk modell för beräkning av livscykelkostnader av olika räckestyper hade redan tagits fram av Hawzheen Karim. Denna model kompletterades för att kunna användas både på sidoområdet med och utan räcken. För att få fram de samhällsekonomiska kostnaderna var det nödvändigt att använda STRADA (Swedish Traffic Accident Data Acquisition) för att räkna ut hur ofta avkörnings- och påkörningsolyckor i räcken leder till skador och dödsfall vilket blir stora kostnader för samhället. Efter att modellen kompletterats kunde en analys utföras för att få fram livscykelkostnader för ett sidoområde med och utan räcken. Resultatet redovisades grafiskt och skärningspunkterna visade den fyllnadhöjd då det blev mer lönsamt att installera vägräcken med en brant slänt istället för att bygga en flackare slänt. Resultatet visade att det finns ett tydligt samband mellan släntens lutning, fyllnadshöjden och graden till vilken kostnaderna stiger. Denna brytpunkt är mycket beroende på en rad faktorer så som markpriset, förekomsten av berggrund i området och om friktionsmaterial behöver behandlas. En flackare slänt medför en ökning av både volymerna av material samt area mark som behöver inlösas, medans en brant slänt med räcken kan medföra högre samhällsekonomiska kostnader på grund av påkörningsolyckor med räcken samt högre drift-och underhållskostnader.
545

Developing a system resilience approach to the improvement of patient safety in NHS hospitals

Williams, Michael Dermot Andrew January 2011 (has links)
The objective of this thesis is to explore how a systems approach can be used to provide an insight into patient safety in NHS hospitals in England. Healthcare delivers considerable benefits yet there remains a relatively high rate of harm and death for patients through adverse events occurring during the process of treatment. The extant patient safety literature acknowledges the influence of organisational or system factors on patient safety. However, the literature is weak in explaining how system factors affect patient safety. To provide an insight into the interactions within healthcare systems, this research explores the characteristics of NHS hospitals, regarded as complex socio-technical systems, using concepts from resilience, systems, accident and social theory. A theoretical Safe Working Envelope (SWE) model (Rasmussen, 1997) is developed and contextualised for use in the NHS. The case study field work was carried out in two NHS hospitals during consecutive winter months at times of high demand for inpatient services. A third case study uses secondary data about patient safety failures in the Mid Staffordshire NHS Foundation Trust. The original SWE model has three failure boundaries. The model is developed by introducing an additional boundary to take account of Government targets. Social theory and system dynamics are used to include the dialectic feedback of social actors and the dynamics of workload. The model depicts the competing pressures, constraints and the workload associated with the need to meet the financial, target, staff workload and patient safety requirements. Three interacting construct sets are explored. These are the constraints within which the system operates, the pressures from the context, and the system dynamics of demand, capacity and decision making. Insights into system behaviours of the hospitals are derived from examining the construct set interactions. The proposition is made that there are five system behaviour archetypes which create the conditions that influence patient safety. The archetypes are derived from the system dynamics and in particular the relationship between reinforcing and balancing feedback loops. The five archetypes are safe practice, drift, tip, collapse and transition towards failure. As hospitals become overcrowded the complexity increases and the reinforcing feedback loops dominate the system and potentially increase the risk to patients. An element of risk arises from staff normalising to the drift in standards of care.
546

Optimal Sequential Decisions in Hidden-State Models

Vaicenavicius, Juozas January 2017 (has links)
This doctoral thesis consists of five research articles on the general topic of optimal decision making under uncertainty in a Bayesian framework. The papers are preceded by three introductory chapters. Papers I and II are dedicated to the problem of finding an optimal stopping strategy to liquidate an asset with unknown drift. In Paper I, the price is modelled by the classical Black-Scholes model with unknown drift. The first passage time of the posterior mean below a monotone boundary is shown to be optimal. The boundary is characterised as the unique solution to a nonlinear integral equation. Paper II solves the same optimal liquidation problem, but in a more general model with stochastic regime-switching volatility. An optimal liquidation strategy and various structural properties of the problem are determined. In Paper III, the problem of sequentially testing the sign of the drift of an arithmetic Brownian motion with the 0-1 loss function and a constant cost of observation per unit of time is studied from a Bayesian perspective. Optimal decision strategies for arbitrary prior distributions are determined and investigated. The strategies consist of two monotone stopping boundaries, which we characterise in terms of integral equations. In Paper IV, the problem of stopping a Brownian bridge with an unknown pinning point to maximise the expected value at the stopping time is studied. Besides a few general properties established, structural properties of an optimal strategy are shown to be sensitive to the prior. A general condition for a one-sided optimal stopping region is provided. Paper V deals with the problem of detecting a drift change of a Brownian motion under various extensions of the classical Wiener disorder problem. Monotonicity properties of the solution with respect to various model parameters are studied. Also, effects of a possible misspecification of the underlying model are explored.
547

Salmonid behaviour under winter conditions

Watz, Johan January 2015 (has links)
Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams. Stream salmonids are relatively active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. In this doctoral thesis, I report the results from experimental field and laboratory studies on the behavioural ecology of juvenile salmonids under winter conditions. My results from the field show that salmonids grow more and use a broader range of habitats in the presence of surface ice than in its absence. Results from the laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions. These laboratory results may explain the positive effects of ice cover on growth that was found in the field experiment. Moreover, I show that drift-feeding ability is reduced at low temperatures, and that nocturnal drift foraging under winter conditions has a low efficiency. / Vinterförhållanden kan spela en avgörande roll för förekomsten av fisk i våra vattendrag. Laxfiskar, som till exempel lax, öring och harr, är vinteraktiva och måste därför anpassa sin fysiologi och sitt beteende till en miljö som karakteriseras av låga och föränderliga vattenflöden, liten tillgång på föda, kallt vatten, is och mörker. Trots att dessa anpassningar är avgörande för chansen att överleva vintern, vet man relativt lite om laxfiskars vinterbeteende, speciellt i vattendrag som täcks av is. I denna avhandling presenterar jag resultat från fält- och laboratoriestudier av laxfiskars beteende under vinterförhållanden och resultaten visar att närvaron av yttäckande is ökar tillväxt och födointag, minskar stress samt påverkar var fiskar uppehåller sig och hur fiskarna interagerar med varandra. Jag har också undersökt hur laxfiskars beteende i rinnande vatten påverkas av ljusintensitet och vattentemperatur i samband med födointag. Resultaten visar att den minskade dagaktiviteten som laxfiskar uppvisar på vintern medför en kostnad i form av försämrad förmåga att fånga byten. / Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams. Stream salmonids are active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. This doctoral thesis focuses on the behavioural ecology of salmonids under winter conditions, and results from field and laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions, with effects on growth and habitat use. Moreover, drift-feeding ability is reduced at low temperatures, and nocturnal drift foraging under winter conditions has a low efficiency. / <p>Artikel 1 i avhandlingen som manuskript. Nu publicerad.</p>
548

The induced mean flow of surface, internal and interfacial gravity wave groups

van den Bremer, T. S. January 2014 (has links)
Although the leading-order motion of waves is periodic - in other words backwards and forwards - many types of waves including those driven by gravity induce a mean flow as a higher-order effect. It is the induced mean flow of three types of gravity waves that this thesis examines: surface (part I), internal (part II) and interfacial gravity waves (part III). In particular, this thesis examines wave groups. Because they transport energy, momentum and other tracers, wave-induced mean flows have important consequences for climate, environment, air traffic, fisheries, offshore oil and other industries. In this thesis perturbation methods are used to develop a simplified understanding of the physics of the induced mean flow for each of these three types of gravity wave groups. Leading-order estimates of different transport quantities are developed. For surface gravity wave groups (part I), the induced mean flow consists of two compo- nents: the Stokes drift dominant near the surface and the Eulerian return flow acting in the opposite direction and dominant at depth. By considering subsequent orders in a separation of scales expansion and by comparing to the Fourier-space solutions of Longuet-Higgins and Stewart (1962), this thesis shows that the effects of frequency dis- persion can be ignored for deep-water waves with realistic bandwidths. An approximate depth scale is developed and validated above which the Stokes drift is dominant and below which the return flow wins: the transition depth. Results are extended to include the effects of finite depth and directional spreading. Internal gravity wave groups (part II) do not display Stokes drift, but a quantity analogous to Stokes transport for surface gravity waves can still be developed, termed the “divergent- flux induced flow” herein. The divergent-flux induced flow it itself a divergent flow and induces a response. In a three-dimensional geometry, the divergent-flux induced flow and the return flow form a balanced circulation in the horizontal plane with the former transporting fluid through the centre of the group and the latter acting in the opposite direction around the group. In a two-dimensional geometry, stratification inhibits a balanced circulation and a second type of waves are generated that travel far ahead and in the lee of the wave group. The results in the seminal work of Bretherton (1969b) are thus validated, explicit expressions for the response and return flow are developed and compared to numerical simulations in the two-dimensional case. Finally, for interfacial wave groups (part III) the induced mean flow is shown to behave analogously to the surface wave problem of part I. Exploring both pure interfacial waves in a channel with a closed lid and interacting surface and interfacial waves, expressions for the Stokes drift and return flow are found for different configurations with the mean set-up or set-down of the interface playing an important role.
549

Un nuevo virus A/H1N1, una nueva pandemia: Influenza un riesgo permanente para una humanidad globalizada

Osores Plenge, Fernando, Gómez Benavides, Jorge, Suárez Ognio, Luis, Cabezas Sánchez, César, Alave Rosas, Jorge, Maguiña Vargas, Ciro 16 July 2014 (has links)
La influenza es una enfermedad altamente infectocontagiosa de la cual se tienen registros históricos descriptivos desde la época griega y de certeza etiológica tan solo hace casi ocho décadas atras. Su agente causal es el virus del influenza de los que se conoce exiten tres grandes tipos: A B y C. El tipo A tiene la propiedad de circular por diversos reservorios biológicos, tales como el hombre, los cerdos y las aves, entre otros. Representa además una elevada variabilidad genética lo que le permite continuos cambios o derivas antigénicas menores responsables de la influenza humanas epidémicas y a veces reordenamientos amplios con cambios antigénicos mayores los que originan la temida influenza pandémica. En un mundo cada vez mas globalizado, con una población superior a los seis mil millones de personas, marcado por grandes inequidades sociales y con cambios climáticos evidentes, los virus de la influenza serán un riesgo permanente para la seguridad de la humanidad. La clínica de los diversos subtipos virales pueden balancearce desde las formas inaparentes hasta las formas graves de gripe o influenza, dependiendo de la virulencia del subtipo viral infectante y del huesped. Aunque nuestra tecnología diagnóstica y de inmunización ha avanzado sorprendentemente, la preparación y disposición de los nuevos kits diagnósticos suelen tardar al principio y en el caso de las vacunas estas no están disponibles para el un nuevo subtipo viral pandémico en el momento que se las necesita. El desarrollo de antivirales contra la gripe no es notorio, contándose aprobados para uso humano los amadantanes como la amantadina y la rimantadina y los inhibidores de la neuraminidasa como oseltamivir y sanamivir principalmente. Claramente los más vulnerables en este contexto son los países en vías de desarrollo y en especial aquellos mas pobres, hecho que nos debería llamar a una profunda reflexión. / Influenza is a highly contagious disease. There are some historical descriptions of this condition by ancient Greek physicians, and the etiological agents have been known only for the last eight decades. The causative agent is the influenza virus, which has three main types: A, B, and C. Type A is capable of circulating within many different biological reservoirs, including humans, swine, and birds. It also has high genetic variability, which allows it to have minor antigenic drifts or mutations which are responsible of epidemics in humans. Sometimes changes are quite marked, leading to pandemics. In a globalized world, with more than 6 billion inhabitants, with many social inequities and evident climate changes, influenza viruses are a permanent risk for mankind. Clinical features for the different viral subtypes may vary from subtle infections to full blown and severe, life-threatening forms. Event with the great advances in diagnostics and immunization, the manufacture and distribution of new diagnostic kits may take some time, and new vaccines are not always readily available. Specific therapies against influenza are not well developed. There are two groups of drugs, the so called adamantane derivatives, such as amantadine and rimantadine, and the neuraminidase inhibitors, such as oseltamivir and zanamivir. Most vulnerable areas for the new flu pandemics include developing countries, particularly the poorest ones, so that the greatest effort must be made for helping these areas.
550

Att måla essäistiskt

Wagner, Ulf January 2016 (has links)
Att måla essäistisktDenna uppsats beskriver hur ett konstnärligt samarbetsprojekt utvecklades mellan två konstnärer.Målet med projektet var att komma fram till ett dialogiskt arbetssätt utan att använda det verbalaspråket och beskriver hur arbetet förvandlades från egna monologer till ett måleriskt samtal.Med utgångspunkt i renässansförfattaren Michel de Montaigne och hans arbete med att iessäform reflektera och få kunskap om tillvaron undersöks essäskrivandet både somforskningsmetod och förhållningssätt. Centrala begrepp är Friedrich Nietschzes apollinskt kontradionysiskt och Friedrich Schillers beskrivningar av form-, sinnlig- och lekdrift. Uppsatsen är enmeta-essä med syfte att visa hur ett essäistist arbetssätt kan reflektera och lyfta fram den egna levdapraktiska kunskapen. / Painting essayisticThis essay-form paper depicts the development of an artistic collaboration between two artistswhere the purpose was to come up with a dialogical way of working without using verballanguage. It describes how this work developed from separate monologues to a conversation inpainting.Based in the the renaissance essayist Michel de Montagne and his reflections over andattempts to understand our existence I try to approach the essay as a form that can be utilized asa method as well as an attitude towards this. Central concepts are Friedrich Nietzsche´s »theApollonian» versus »the Dionysian» as well as Friedrich Schiller's descriptions of the formaldrive, the sensuous drive and the play drive. The paper is a “meta essay” about how theessayistic method can be used to reflect over and emphasize personal practical knowledge.Keywords:Essay,

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