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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.
31

The Performance of Serial Acquirers : Evidence from the Nordic market

Gionis, Mattias, Stugemo, Jesper January 2022 (has links)
This thesis examines the performance of serial acquirers in the Nordic market between 2006-2016. We investigate how serial acquirers perform in the short-term and long-term and if serial acquirers are affected by hubris, or if they learn by experience. The payment method is examined to determine if cash-financed deals outperform equity-financed deals. The short-term performance study is measured by the Cumulative Abnormal Return (CAR) and the long-term performance study is measured by the Calendar-Time Portfolio (CTP) combined with the Fama-French Four-Factor model. The main findings show that serial acquirers underperform relative to single acquirers only in the short term. No significant results are found for the hubris and learning hypotheses. In addition, we find that acquirer size and the deal size have a significant effect on the short-term post-M&A performance.
32

Microstructure Changes In Solid Oxide Fuel Cell Anodes After Operation, Observed Using Three-Dimensional Reconstruction And Microchemical Analysis

Parikh, Harshil R. 09 February 2015 (has links)
No description available.
33

The role of organisational resilience in maintaining long term performance, especially after undergoing major organisational changes : a consideration of the critical success factors involved

Otulana, Oluwatosin January 2011 (has links)
A lot has been said about change. For example, it is widely recognised that the only constant is change (Heraclitus, 470 BC). As such, no sensible decision can be made any longer without taking into account not only the world as it is, but the world as it will be (Isaac Asimov). As regards this, a bulk of existing researches have been aimed at understanding the triggers for change and the extent or degree to which individuals, organisations, systems or entities have to change. Generally, results from such studies vary. With specific relations to organisations, organisations are advised of the need to develop added adaptive and dynamic capabilities. One of such added adaptive and dynamic capabilities is organisational resilience. In the literature, organisational resilience has been successful linked with organisations ability to maintain long term performance. Hence, the research is not about re-examining the relationship between organisational resilience and organisations ability to maintain long term performance. This research focuses on exploring the critical success factors required to maintain long term performance and building adequate resilience into systems undergoing changes. The investigation was conducted in three phases, namely: (a) the exploratory phase; (b) the descriptive phase; and the empirical phase. The exploratory phase involved identifying the critical factors essential to maintain long term performance and at the same time build resilience into their systems after undergoing organisation-wide changes. In order to make out these critical, a pilot study was conducted. 21 persons occupying senior managerial positions in different organisations were interviewed. The interview data were transcribed, coded and analysed using coding and thematic analysis to identify five common themes, namely (a) employees readiness to support ongoing organisation-wide changes; (b) development of targeted organisational adaptive capacity; (c) the provision of individualised and social support; (d) the use of stress coping mechanisms; and (e) the existence of organisational resilience strategies. The second phase of the research entailed conducting case study research with the intention of describing the identified critical success factors. The final phase entailed conducting empirical analyses and cross case analysis. Results from the cross case study analyses indicated that both resilience building at the individual level and organisational level is needed for organisations to build in resilience into their systems especially after undergoing organisation-wide changes. Three factors (i.e. employees readiness to support ongoing organisation-wide changes, the provision of individualised and social support and the use of stress coping mechanisms) were found to be more pronounced at the individual level. The remaining two factors namely development of targeted organisational adaptive capacity and the existence of organisational resilience strategies are essentially carried out at the organisational level. The research has contributed to the current body of knowledge on how organisations can strive to maintain long term performance, especially for a country like Nigeria where there still remains a dearth of such related studies. Each of the research hypotheses were either confirmed or non confirmed. This will give the practitioners, academicians and managers of Nigerian organisations the opportunity to understand how each of the sub factors of the five critical success factors can influence on attempts to build organisational resilience. In addition, specific actions that managers can follow over the life of an organisation-wide change project that will improve the resilience of systems undergoing change. In addition, differences in how varied control factors can influence resilience building in organisations were explored and validated based on the results of the Mann Whitney test results. At the end of the thesis, recommendations for future practice and research were made. One of such is that resilience building at both levels be done concurrently and given equal prominence.
34

Modelagem descritiva do comportamento do cimento Portland em ambiente de repositório para rejeitos radioativos / Descriptive modeling of Portland cement behavior in a repository environment for radioactive waste

Ferreira, Eduardo Gurzoni Alvares 29 September 2017 (has links)
A deposição de rejeitos radioativos em repositórios geológicos profundos vem sendo estudada nos últimos anos em diversos países. Materiais à base de cimento são utilizados nesses repositórios como material estrutural, matriz de imobilização de rejeitos ou material de preenchimento. Compreender o desempenho desse material é essencial para garantir a segurança da instalação durante o seu tempo de vida útil (de milhares a centenas de milhares de anos, dependendo do tipo de rejeito). Este trabalho objetiva modelar o comportamento em longo prazo do cimento Portland e estudar a influência de diversos fatores na hidratação e na evolução desse material. A modelagem descritiva abordou a hidratação do cimento nas condições ambientais esperadas no repositório e os efeitos desses fatores em propriedades mecânicas, mineralógicas e morfológicas do cimento. Os fatores ambientais considerados relevantes neste trabalho foram: alta temperatura e pressão, penetração de água subterrânea contendo íons quimicamente agressivos ao cimento e a presença do campo de radiação proveniente dos rejeitos. Ensaios acelerados de degradação também foram realizados para corroborar com o modelo descrito. Observou-se uma sinergia entre diversos fatores na degradação do cimento, como a influência da temperatura e da radiação em reações deletérias ao material. O resultado da modelagem apontou três principais possíveis causas de falha nas barreiras artificiais: a) a formação de um caminho preferencial; b) a perda de resistência e coesão do material; e c) o aumento na corrosão das estruturas metálicas. A descrição do modelo apresentada é a base para a modelagem matemática e a análise de segurança dos repositórios estudados no Brasil. / The radioactive waste disposal in deep geological repositories has been studied for many countries in the last years. Cementitious materials are used in these repositories as structural material, immobilization matrix and as backfill material. The understanding of the performance of these materials is essential to ensure the safety of the installation during its life time (from thousand to hundreds of thousands of years, depending on the type of waste). This works aims at modeling the long-term performance of Portland cement and study the influence of many environmental factors in the hydration and evolution of this material. The modeling approached the cement hydration in the conditions expected in the repository and the effects of these factors on cement mechanical, mineralogical and morphological properties. The environmental factors considered relevant was: high temperature and pressure, the penetration of groundwater containing aggressive chemical ions, and a radiation field from the waste. Degradation accelerated tests were done to corroborate with the descriptive model. It was observed a synergism between some factors on the cement degradation, as the influence of temperature and radiation field in some deleterious reactions in the material. The results of modeling pointed to three main causes of engineered barrier failure: a) the formation of a preferential pathway; b) loss of resistance and cohesion in the material; and c) the increase in the metallic structures corrosion process. The descriptive model is the basis for a mathematical modeling and to perform the safety assessment of the repositories studied in Brazil.
35

Modelagem descritiva do comportamento do cimento Portland em ambiente de repositório para rejeitos radioativos / Descriptive modeling of Portland cement behavior in a repository environment for radioactive waste

Eduardo Gurzoni Alvares Ferreira 29 September 2017 (has links)
A deposição de rejeitos radioativos em repositórios geológicos profundos vem sendo estudada nos últimos anos em diversos países. Materiais à base de cimento são utilizados nesses repositórios como material estrutural, matriz de imobilização de rejeitos ou material de preenchimento. Compreender o desempenho desse material é essencial para garantir a segurança da instalação durante o seu tempo de vida útil (de milhares a centenas de milhares de anos, dependendo do tipo de rejeito). Este trabalho objetiva modelar o comportamento em longo prazo do cimento Portland e estudar a influência de diversos fatores na hidratação e na evolução desse material. A modelagem descritiva abordou a hidratação do cimento nas condições ambientais esperadas no repositório e os efeitos desses fatores em propriedades mecânicas, mineralógicas e morfológicas do cimento. Os fatores ambientais considerados relevantes neste trabalho foram: alta temperatura e pressão, penetração de água subterrânea contendo íons quimicamente agressivos ao cimento e a presença do campo de radiação proveniente dos rejeitos. Ensaios acelerados de degradação também foram realizados para corroborar com o modelo descrito. Observou-se uma sinergia entre diversos fatores na degradação do cimento, como a influência da temperatura e da radiação em reações deletérias ao material. O resultado da modelagem apontou três principais possíveis causas de falha nas barreiras artificiais: a) a formação de um caminho preferencial; b) a perda de resistência e coesão do material; e c) o aumento na corrosão das estruturas metálicas. A descrição do modelo apresentada é a base para a modelagem matemática e a análise de segurança dos repositórios estudados no Brasil. / The radioactive waste disposal in deep geological repositories has been studied for many countries in the last years. Cementitious materials are used in these repositories as structural material, immobilization matrix and as backfill material. The understanding of the performance of these materials is essential to ensure the safety of the installation during its life time (from thousand to hundreds of thousands of years, depending on the type of waste). This works aims at modeling the long-term performance of Portland cement and study the influence of many environmental factors in the hydration and evolution of this material. The modeling approached the cement hydration in the conditions expected in the repository and the effects of these factors on cement mechanical, mineralogical and morphological properties. The environmental factors considered relevant was: high temperature and pressure, the penetration of groundwater containing aggressive chemical ions, and a radiation field from the waste. Degradation accelerated tests were done to corroborate with the descriptive model. It was observed a synergism between some factors on the cement degradation, as the influence of temperature and radiation field in some deleterious reactions in the material. The results of modeling pointed to three main causes of engineered barrier failure: a) the formation of a preferential pathway; b) loss of resistance and cohesion in the material; and c) the increase in the metallic structures corrosion process. The descriptive model is the basis for a mathematical modeling and to perform the safety assessment of the repositories studied in Brazil.
36

Preparation and long-term performance of poly(ethylene-co-butyl acrylate) nanocomposites and polyethylene

Nawaz, Sohail January 2012 (has links)
The current study discusses the preparation and long-term performance of polymer composites used for various purposes under different ageing conditions. The first part deals with the preparation and characterization of polymer nanocomposites based on poly(ethylene-co-butyl acrylate) (EBA–13 and EBA–28 with 13 and 28 wt % butyl acrylate, respectively) and 2–12 wt % (0.5–3 vol %) of aluminum oxide nanoparticles (two types with different specific surface areas and different hydroxyl-group concentrations; uncoated and coated with, respectively, octyltriethoxysilane and aminopropyltriethoxysilane). The nanocomposite with EBA–13 showed better overall nanoparticle dispersion while EBA–28 resulted in poor dispersion, probably due to insufficiently high shear forces acting during extrusion mixing which were unable to break down nanoparticle agglomerates. The activity of hindered phenolic antioxidant (0.2 wt%) in all EBA nanocomposites was assessed by determining the oxidation induction time using DSC. The composites containing uncoated aluminium oxide nanoparticles showed a much shorter initial OIT than the pristine polymer with the same initial concentration of antioxidant, indicating adsorption of antioxidant onto the nanoparticle surfaces. Composites containing coated nanoparticles showed a significantly smaller decrease in the initial OIT, suggesting the replacement of hydroxyl groups with organic silane tails, decreasing the concentration of available adsorption sites on the nanoparticle surfaces. The decrease in OIT with increasing ageing time in dry air at 90 °C of the nanocomposites was slower than that of the unfilled pristine polymer, suggesting a slow release of antioxidant from adsorption sites. The EBA nanocomposites exposed to liquid water at 90°C showed faster decrease of OIT than samples exposed to dry or humid air. The migration rate of antioxidant was controlled by the boundary conditions in the case of ageing in humid air and liquid water. The antioxidant diffusivity was lower for the composites containing uncoated ND than for the composites containing ND coated with octyltriethoxysilane or aminopropyltriethoxysilane. The migration and chemical consumption of deltamethrin DM, (synthetic pyrethroid) and synergist piperonyl butoxide from molded polyethylene sheets was also studied. Deltamethrin and piperonyl butoxide are often used for food  storage and insect control purposes. DM showed no signs of crystallization and remained in a liquid state after being cooled to room temperature. Exposure of polyethylene compound sheets to liquid water (at 80 &amp; 95 °C), caused degradation and hydrolysis of the ester bond in the DM, present in the prepared material, and generated species containing hydroxyl groups. Liquid chromatography and infrared spectroscopy showed a significant migration of the active species in liquid water, whereas in air at 80 °C (60 and 80 %RH) the loss of DM and PBO was negligible over 30 days. The long-term performance of medium-density polyethylene stabilized with six different phenolic antioxidants (0.1 wt%) in aqueous chlorinated media at 70 °C was studied. The results were compared with data for previously studied solutions of antioxidants in squalane (a liquid, low molar mass analogue of polyethylene). A linear relationship was established between the time to reach antioxidant depletion in polyethylene tape samples and the time in squalane samples. Infrared spectroscopy and scanning electron microscopy of drawn samples revealed the onset of surface oxidation and surface embrittlement in tape samples exposed beyond the time for antioxidant depletion. / <p>QC 20121109</p> / Cable insulation materials / Loss of deltamethrin and pipronyl butoxide from polyethylene / long-term performance of polyethylene in chlorine dioxide water
37

DEVELOPEMENT OF A CONTINUOUS MODELLING APPROACH CAPABLE OF EVALUATING SEDIMENT REMOVAL PERFORMANCE OF VEGETATIVE FILTER STRIPS IN WATERSHED SCALE

Seradj, Mani 12 September 2011 (has links)
This study focused on development of a continuous watershed-scale modelling approach capable of evaluating sediment removal performance of vegetative filter strips (VFS). This was done by integrating the single-event hydrologic and sediment transport model AGNPS with the event-based VFS model (VFSMOD) applying the methodology developed by Sebti and Rudra (2010), and also through the development and incorporation of sub-models capable of describing changes in hydrologic conditions between rainfall events into the integrated models. For modeling purposes, the buffer zone is divided to segments called “buffer cells”. The upstream source area corresponding to each buffer cell and the flow-path connecting the area to the stream are identified, and runoff and sediment generated within each area is simulated for each event applying AGNPS. Using VFSMOD, performance analysis of VFS is conducted for each buffer cell. By applying the developed “continuous simulation” sub-models the hydrologic conditions prior to each event were determined.
38

LONG-TERM PERFORMANCE OF HDPE GEOMEMBRANES AS LANDFILL LINERS

ISLAM, MOHAMMAD 02 February 2009 (has links)
High density polyethylene (HDPE) geomembranes are normally used as part of a composite liner for waste containment facilities such as municipal solid waste (MSW) landfills and heap leach pads. Field conditions, which include physical stresses on the geomembrane, elevated operating temperatures, and contact with leachate constituents, have the potential to affect the service life of the HDPE geomembranes. This thesis examined the long-term performance of different HDPE geomembranes based on both conventional laboratory accelerated immersion tests and simulated landfill liner tests. A 1.5mm HDPE geomembrane was immersed in different synthetic leachates at different temperatures in order to evaluate the effects of leachate chemical constituents on the depletion of antioxidants. The results showed that a basic leachate with trace metals, surfactant, and a reducing agent was the most appropriate for evaluating the potential degradation of HDPE geomembranes. A similar immersion test was performed to evaluate the effects of thickness on the ageing of HDPE geomembranes. Three commercially available HDPE geomembranes having nominal thicknesses of 1.5, 2.0, and 2.5mm were immersed in a synthetic leachate at four different temperatures in this experiment. The results showed that a thicker geomembrane may have a longer service life if other things are similar. The depletion of antioxidants from a 1.5mm thick HDPE geomembrane was examined by conducting accelerated ageing tests at 55, 70, and 85oC under simulated landfill liner conditions. The results showed that the antioxidant depletion rate was consistently lower for the simulated landfill liner tests compared to the leachate immersion tests. The effectiveness of the aged HDPE geomembrane on the migration of volatile organic compounds (VOCs) was examined by conducting diffusion and partitioning tests using both unaged and aged HDPE geomembranes. The results showed that the ageing of HDPE geomembranes did not increase diffusive migration of organic contaminants, provided that the geomembrane remained intact. A new method was developed to estimate the service life of the HDPE geomembrane based on the landfill liner temperature history. The service lives of the HDPE geomembranes were calculated to be between 20 and 4700 years, depending on the geomembrane type, exposure conditions, and the time-temperature history examined. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-01-30 09:30:49.135
39

Analysis Methods for Post Occupancy Evaluation of Energy-Use in High Performance Buildings Using Short-Term Monitoring

January 2011 (has links)
abstract: The green building movement has been an effective catalyst in reducing energy demands of buildings and a large number of `green' certified buildings have been in operation for several years. Whether these buildings are actually performing as intended, and if not, identifying specific causes for this discrepancy falls into the general realm of post-occupancy evaluation (POE). POE involves evaluating building performance in terms of energy-use, indoor environmental quality, acoustics and water-use; the first aspect i.e. energy-use is addressed in this thesis. Normally, a full year or more of energy-use and weather data is required to determine the actual post-occupancy energy-use of buildings. In many cases, either measured building performance data is not available or the time and cost implications may not make it feasible to invest in monitoring the building for a whole year. Knowledge about the minimum amount of measured data needed to accurately capture the behavior of the building over the entire year can be immensely beneficial. This research identifies simple modeling techniques to determine best time of the year to begin in-situ monitoring of building energy-use, and the least amount of data required for generating acceptable long-term predictions. Four analysis procedures are studied. The short-term monitoring for long-term prediction (SMLP) approach and dry-bulb temperature analysis (DBTA) approach allow determining the best time and duration of the year for in-situ monitoring to be performed based only on the ambient temperature data of the location. Multivariate change-point (MCP) modeling uses simulated/monitored data to determine best monitoring period of the year. This is also used to validate the SMLP and DBTA approaches. The hybrid inverse modeling method-1 predicts energy-use by combining a short dataset of monitored internal loads with a year of utility-bills, and hybrid inverse method-2 predicts long term building performance using utility-bills only. The results obtained show that often less than three to four months of monitored data is adequate for estimating the annual building energy use, provided that the monitoring is initiated at the right time, and the seasonal as well as daily variations are adequately captured by the short dataset. The predictive accuracy of the short data-sets is found to be strongly influenced by the closeness of the dataset's mean temperature to the annual average temperature. The analysis methods studied would be very useful for energy professionals involved in POE. / Dissertation/Thesis / M.S. Architecture 2011
40

Börsnotering – träna sprint för ett maraton? : En eventstudie om Private equity-aktörers bestående värdeskapande – bevis från Skandinavien 2002-2013 / IPO – sprinting a marathon? : An event study on Private equity companies’ long-term value creation – evidence from Scandinavia 2002-2013

Lenberg, Jesper, Wihl, Måns January 2017 (has links)
Bakgrund och problem: Private equity-aktörers värdeskapande är ett fenomen som studerats internationellt sedan 80-talet och intensifierats under det senaste årtiondet. Med en mängd forskning angående prestationen under ägandeskapet är utbudet mindre huruvida prestationen är bestående och hur portföljbolagen presterar efter att de avyttrats. Trots detta råder det ingen konsensus kring tidigare studiers resultat. Mot bakgrund av den motstridighet som föreligger i tidigare forskning och den uppmärksammade debatten om riskkapitalisters värdeskapande söker denna studie att studera och undersöka ämnet närmre för den skandinaviska marknaden. Syfte: Studiens syfte är att undersöka hur skandinaviska portföljbolag presterar efter avyttring genom börsintroduktion. Studien ämnar därmed att utreda, kartlägga och skapa bättre förståelse huruvida det föreligger någon skillnad i tidigare PE-ägda portföljbolags prestation gentemot branschkonkurrenter utifrån utvalda nyckeltal. Metod: Studien applicerar en kvantitativ forskningsmetod, vilket är i linje med tidigare forskning och referensstudier som även använder ett parametriskt och ett icke-parametriskt statistiskt test för att utröna om över- eller underprestation föreligger för tidigare PE-ägda portföljbolag. Därefter har studiens resultat analyserats med bakgrund av tidigare forskning och vedertagna teorier inom ämnet. Slutsats: Studiens resultat konstaterar att tidigare PE-ägda portföljbolag som börsnoterats inte överpresterar sina branschkonkurrenter, utan presterar sämre eller endast i linje med dem. Till skillnad från tidigare forskning kan ingen av- eller tilltagande effekt urskiljas, vilket innebär att ägarbytet vid börsnoteringen inte medför några bestående komparativa konkurrensför- eller nackdelar. / Background and problem: Private equity companies’ long-term performance is a phenomena that has been examined internationally since the 80’s, which has intensified over the last decade. With a lot of research focusing on performance during the ownership, the offer is less extensive whether the performance is long-term and how the divested portfolio companies perform after the private equity companies exit. Nevertheless, there is up today no consensus regarding the result of the previous studies. In the light of the contradiction of the previous research and the debate on risk capitalists’ value creation, this study seeks to investigate the phenomena closer on the Scandinavian market. Purpose: The purpose of this study is to investigate how Scandinavian portfolio companies perform after divestment through an IPO. The study thus aims to investigate, plot and create a better understanding of whether there is any difference in past PE-owned portfolio companies’ performance relative industry competitors bases on selected key ratios. Methodology: The study applies a quantitative research method, which in line with previous research and reference studies, uses a statistical parametric and a non-parametric test to determine whether over- or underperformance exists for previous PE-owned portfolio companies. The result of the study have been analyzed in the light of previous research and conventional theories within the field of subject. Conclusions: This study’s findings show that previous private equity owned portfolio companies do not over perform their industry peers, but perform in line or inferior to them. Unlike previous research, no decreasing or increasing effect can be distinguished which means that the change of ownership through the IPO does not bring any long-term comparative competitive advantages or disadvantages.

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