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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.
291

Laboratory investigation of low-tension-gas (LTG) flooding for tertiary oil recovery in tight formations

Szlendak, Stefan Michael 04 April 2014 (has links)
This paper establishes Low-Tension-Gas (LTG) as a method for sub-miscible tertiary recovery in tight sandstone and carbonate reservoirs. The LTG process involves the use of a low foam quality surfactant-gas solution to mobilize and then displace residual crude after waterflood. It replicates the existing Alkali-Surfactant-Polymer (ASP) process in its creation of an ultra-low oil-water interfacial tension (IFT) environment for oil mobilization, but instead supplements the use of foam over polymer for mobility control. By replacing polymer with foam, chemical Enhanced Oil Recovery (EOR) methods can be expanded into sub-30 mD formations where polymer is impractical due to plugging, shear, or the requirement to use a low molecular weight polymer. Overall results indicate favorable mobilization and displacement of residual crude oil in both tight carbonate and tight sandstone reservoirs. Tertiary recovery of 75-95% ROIP was achieved for cores with 2-15 mD permeability, with similar oil bank and other ASP analogous process attributes observed. Moreover, similar recovery was achieved during testing at high initial oil saturation (56%), indicating high process tolerance to oil saturation and potential application for implementation at secondary recovery. In addition, a number of tools and relations were developed to improve the predictive relationship between observed coreflood properties and actual mobilization or displacement mechanisms which impact reservoir-scale flooding. These relations include qualitative dispersion comparison and calculation of in-situ gas saturation, macroscopic mobility ratio at the displacement fronts, and apparent viscosity of injected fluids. These tools were validated through use of reference gas and surfactant floods and indicate that stable macroscopic displacement can be achieved through LTG flooding in tight formations. Furthermore, to better reflect actual reservoir conditions where localized fractional flow of gas can vary substantially depending on mixing or gravity phenomenon, two additional sets of data were developed to empirically model behavior. Through testing of LTG co-injection at a number of discrete fractional flow values over a wide range, recovery was shown to achieve a relative maximum at 50% gas fractional flow which also corresponded with optimal observed mobility control as measured by the previously established tools. Likewise, through testing of surfactant-alternating-gas (SAG) injection cycling, displacement and overall recovery were shown to be improved versus reference co-injection flooding. Finally, by comparing the observed displacement and mobility data among co-injection and surfactant-alternating-gas floods, a new displacement mechanism is introduced to better relate actual displacement conditions with observed macroscopic mobility data. This mechanism emphasizes the role of liquid rate in actual displacement processes and a mostly static gas saturation (independent of gas rate) in altering liquid relative permeability and diverting injected liquid into lower permeability zones. / text
292

Adolescents' experiences of undergoing scoliosis surgery : psychological aspects and patterns of pain

Rullander, Anna-Clara January 2015 (has links)
Background: Adolescent idiopathic scoliosis (AIS) affects 1 – 3% of all children aged 10 – 16 years; of these approximately 80% are girls. Scoliosis surgery is a major (one of the most extensive) elective paediatric orthopaedic procedure and is known to cause severe and excruciating pain that requires advanced postoperative pain management. Until now, scoliosis surgery has mainly been studied in terms of corrective surgical outcomes, and techniques for surgery and pain management. Adolescents’ narratives and experiences of recovery after scoliosis surgery, as well as psychological aspects in correlation to postoperative pain have seldom been studied. Aim: The overall aim of this thesis was to explore adolescents’ experiences of undergoing scoliosis surgery, experiences and self-reporting of pain, and psychological consequences. Methods: This thesis comprises four studies. The participants in Studies I and II belonged to the same cohort, all of whom underwent corrective surgery in the period from 2004 to 2007. In Study I there was a cohort of 87 adolescents and young adults with different types of scoliosis, some of whom had impaired verbal communication. The patients and their parents/caregivers were asked to complete a survey with questions regarding experienced pain, nausea and overall satisfaction with the hospital stay. Study II was a qualitative study in which six adolescents from the cohort in Study I were interviewed. The adolescents included in Study II had idiopathic scoliosis, and the interviews took place about two years after they had undergone surgery. Study III, which included 37 adolescents, was a prospective study of adolescents with idiopathic scoliosis (AIS) from four spine centres in Sweden. They completed two psychometric instruments and one structured interview both before surgery and about six months afterward. They also self-measured pain on the third postoperative day. In Study IV the adolescents included belonged to the same cohort as in Study III. In this prospective, mixed-method study, the participants self-reported pain before surgery, every four hours for the first five days after surgery, once a day for the first fourteen days at home after discharge from the hospital, and finally at the six-month follow-up. They were also asked to keep a diary during the first two weeks at home after discharge from the hospital. At the six-month follow-up they were interviewed about the overall experience of undergoing scoliosis surgery: how they experienced the time before surgery, during the hospital stay and the recovery period up through the date of the interview. iv Results: Study I showed that the patients experienced severe pain and nausea postoperatively during the hospital stay. The parents/caregivers felt helpless and sometimes lacked confidence in the nurses. Despite this, overall satisfaction with the hospital stay was rated as good. Study II showed that the adolescents experienced nervousness and fear before surgery, severe pain and postoperative nausea and vomiting (PONV) during the hospital stay, had problems with the scars and experienced social difficulties during recovery. Nightmares were reported for up to two years after surgery. In Study III, the ratings of stress symptoms were higher before surgery than after. There were significant correlations between stress symptoms before surgery and levels of postoperative pain. There were also significant correlations between levels of postoperative pain and stress symptoms at the six-month follow-up. In Study IV, postoperative pain ratings showed great individual variation, and in the analysis of drop-outs it was found that those who did not keep a diary at home self-reported higher levels of pain at the six-month follow-up as well as higher levels of stress symptoms and internalizing symptoms. The participants described experiences of severe pain at the hospital and also during recovery. Nausea, constipation and lack of energy emerged from the narratives - but so did the desire to get back to school, sports and friends. The adolescents described how they were hovering between suffering and control and also striving towards normality. Conclusion: The results indicate a need for interventions among adolescent patients to reduce stress symptoms before major surgery. Nurses need to identify adolescents with stress symptoms, use stress-reduction techniques, and support adolescent patients with coping strategies aimed at reducing preoperative stress and managing postoperative pain. Postoperative pain management needs to be improved, both as regards pain assessment and pharmacological and non-pharmacological pain management. Nurses need to improve their medical technical skills in order to optimize pain treatment. After discharge from the hospital adolescents have to struggle with difficulties at home such as pain, nausea, constipation, mobilization and a lack of energy. An intervention with follow-up telephone calls during the second week at home could reduce stress and help resolve difficulties. Since this study indicates stress symptoms at the six-month follow-up, there should also be a nurse interview to check on well-being and to see if any further intervention is needed at that time. If preoperative stress can be reduced, postoperative pain management optimized and the recovery period better supported, the overall experience of going through scoliosis surgery should improve.
293

Living well with aphasia : spousal involvement as an integral component in stroke recovery

McCabe, Kathryn Rose 21 July 2011 (has links)
Stroke has the ability to chronically alter both a person’s understanding and or use of language. Aphasia is a term that represents the loss or impairment of language function as a consequence of brain damage caused by a stroke and current data reveal that at least 25% of all strokes result in aphasia. Spouses often play a pivotal role in a stroke patient’s journey towards recovery. For this reason, there is a dire need for increased knowledge regarding spousal psychosocial welfare and increased insight into the experiences of these individual’s altered life situations. This paper considers aphasia, by nature of its deficits, a family disorder. Additionally, the contents of this paper explore the significance of caregiver coping strategies and ongoing caregiver involvement in recovery as a mechanism towards increased well being. Evidence to confirm the effects of stroke on spouses, as well as to support involvement of spouses in speech-language treatment to facilitate living well with aphasia, was obtained through primary and secondary research. Primary research was compiled through a telephone interview with the spouse of a 62-year-old male with aphasia while secondary research was conducted through an extensive literature search from 2000 to 2011. / text
294

Effectiveness of Backup and Disaster Recovery in Cloud : A Comparative study on Disk and Cloud based Backup and Disaster Recovery

Kaveti, Akash January 2015 (has links)
Context: Definitive information is what makes enterprises in the contemporary world continuously move up the ladder in today’s world. Hence they need to be always up to date with the latest advancements. A key point in the enterprise structure is Backup and Disaster Recovery, DR system and this has very high scope for development since it can be integrated with a lot of our daily requirements. On account of this, it has a lot of applicability in future for development of technology. Due to this, we have chosen a Fast Moving Consumer Goods Company, FMCG to conduct experimentation on their Backup and DR system. Objectives: In every organization, Backup and DR plays a crucial role in Business Continuity Planning. This work relates to associate backup and recovery plan with an organizational view. And thereby work on its association with Recovery Time Objective, Recovery Point Objective, time taken for backup, time take for recovery and Total Cost of Ownership. Methods: Literature study is the first step to understand present scenario of trending technologies. Hence our understanding led us to conduct an experimental setup where we compared data that was collected in a case study and evaluated its performance of Backup and DR problems that are faced in today’s technology dominated world. Results: In our research, we took various parameters into consideration, which affect performance of an enterprise Backup and DR system. This drove us to assess disk-based and cloud-based Backup and DR plans in the FMCG environment. Conclusions: In conclusion, we summate that even though there have been a lot of theories and research on how Backup and DR is vital, we still lag behind in research work on which the organizations can rely upon to shift towards advanced technologies without risking their competence. With sufficient research on the entrepreneurial environment, we can improve performance enterprises and improve our present knowledge about cloud Backup and DR thereby improving its conventional usage in the present world.
295

Tillväxt utan nyanställningar

Wirenstål, Mats, Olsson, Marcus January 2006 (has links)
När IT-kraschen inträffade under 2001 fick den påtagliga konsekvenser för svensk ekonomi. Tillväxten, som tidigare varit hög, fick negativa värden och sysselsättningsökningen avstannade. När sedan tillväxten återhämtade sig, efter knappt ett år, förblev sysselsättningsnivån oförändrad. Ännu idag (dec 2005) har sysselsättningen inte visat några markanta förbättringar. Vi vill med vår uppsats närmare kartlägga var denna tillväxt utan nyanställningar uppkommer. Detta har vi gjort genom att skapa oss en överblick över hela arbetsmarknaden och därefter analyserat vilka sektorer som markant ökat sin produktion per anställd utan att nyanställa. Vi har även använt oss av en analys för hela tillverkningsindustrin där vi undersökt om det skett en arbetskraftomfördelning inom sektorn som lett till en produktionsökning. Vi fann att den enda riktigt tydliga tillväxten utan nyanställningar har skett i sektorn ”fastigheter och företagstjänster”. Arbetskraftsförflyttning mellan branscherna inom tillverkningsindustrin har inte påverkat produktiviteten nämnvärt.
296

Constructing hope in challenging spaces: narratives by health professionals on issues of solvent use

De Boer, Tracy 28 March 2013 (has links)
The process of recovery from addiction is a multifaceted process that involves the efforts of clients, professionals and the broader community. Additional challenges to recovery are present for individuals who use solvents. This study investigates how professionals, involved in the provision of services to clientele who use solvents, understand the process of healing in their collaborative work. Using a narrative methodology, semi-­‐structured interviews were conducted with professionals employed in providing recovery-based services to individuals who use volatile solvents. The stories of these professionals demonstrate how they view their clients as “just like everyone else” despite what the dominant cultural story says about their possibilities for recovery. The professionals told stories which are in extreme opposition to the story of dominant culture and involved groupings of “us” (professionals) versus “them” (others). These stories, and how they were told, are discussed in relation to hope for professionals who provide health and housing services.
297

Seismic Amplitude Recovery with Curvelets

Moghaddam, Peyman P., Herrmann, Felix J., Stolk, Christiaan C. January 2007 (has links)
A non-linear singularity-preserving solution to the least-squares seismic imaging problem with sparseness and continuity constraints is proposed. The applied formalism explores curvelets as a directional frame that, by their sparsity on the image, and their invariance under the imaging operators, allows for a stable recovery of the amplitudes. Our method is based on the estimation of the normal operator in the form of an ’eigenvalue’ decomposition with curvelets as the ’eigenvectors’. Subsequently, we propose an inversion method that derives from estimation of the normal operator and is formulated as a convex optimization problem. Sparsity in the curvelet domain as well as continuity along the reflectors in the image domain are promoted as part of this optimization. Our method is tested with a reverse-time ’wave-equation’ migration code simulating the acoustic wave equation.
298

Marine Mammal Population Recoveries and Critical Factors

Magera, Anna M. 01 April 2011 (has links)
Of all the marine taxa, marine mammals seem to have benefited the most from a paradigm shift from exploitation to conservation. This thesis provides the first quantitative assessment for marine mammals of (1) global, publicly available population-level abundance data, (2) abundance trends, (3) the relationship between decline and recovery, and (4) critical factors to recovery. I compiled a database of 143 population abundance time series. Using robust linear regression, I found approximately one third (35%) were significantly increasing and recovering. For populations with historical estimates (n=47), I also found a negative relationship between decline and recovery. With the significant population trends (n=43), I used a variety of modeling approaches—classification trees, generalized linear models (GLMs) and generalized additive models (GAMs) —to assess the relationship between hypothesized intrinsic and extrinsic critical factors and recovery. The results suggest the ongoing importance of wildlife proximity and accessibility to humans in determining population recovery.
299

Feasibility of glucose recovery from municipal sewage sludges as feedstocks using acid hydrolysis

Wang, Xue 28 July 2008 (has links)
In light of rising costs in fossil fuels and petroleum, as well as the strain on this largely non-renewable resource, the conversion of biomass, in this case waste biomass, to value-added products is becoming more attractive. In this study, municipal sewage sludge and biosolids were used to determine their potential for glucose recovery. This research focused on three pretreatment processes including drying/grinding, as well as acid and alkaline pretreatments, followed by acid hydrolysis on primary sludge, activated sludge and biosolids. After each pretreatment under specified conditions, the residues remaining from the sludges and biosolids underwent a 2 % H2SO4 acid hydrolysis at 120oC for 1 hr. Compared with activated sludge and biosolids, primary sludge was found to demonstrate the highest potential for glucose recovery in this study. Primary sludge with 1.0 N HCl pretreatment over a 24 hour contact period yielded the highest glucose conversion result as 5.67±0.24%. The best KOH pretreatment condition for primary sludge was a 0.5 N KOH concentration for a 0.5 hour contact period. However, no consistent glucose recovery trend as a function of reagent concentration or contact time was identified for any of the sludges or biosolids in this study. Drying and grinding were also found to efficiently improve the acid hydrolysis results. Fibre content analysis was also performed on the sludge and biomass feedstocks and their residues following pretreatment and acid hydrolysis during this study, to better understand the conversion of these waste biomass feedstock. The Van Soest methods for neutral-detergent, acid-detergent and acid insoluble lignin analysis and the Weende crude fibre analysis were applied to the sewage sludge and biosolids samples prior to and after acid hydrolysis to determine the fibre content including cellulose, hemicellulose and lignin. A modification to the Weende crude fibre analysis was introduced, where a centrifuge step was added prior to the second filtration after the alkaline digestion of the procedure to reduce filter clogging problems. The centrifuge modification effectively reduced the filtering time from one day to 30 minutes; however, there was an average loss of 46% in crude fibre with the addition of this centrifugation step. It was found that most of cellulose content in the feedstock samples was hydrolyzed to glucose after the acid hydrolysis process and most hemicellulose content was likely to have been solubilized and washed away during acid and alkaline pretreatments and acid hydrolysis. The lignin content did not appear to be affected by the pretreatments applied nor the acid hydrolysis. / Thesis (Master, Civil Engineering) -- Queen's University, 2008-07-25 16:10:42.518
300

Hybrid Turboexpander and Fuel Cell System for Power Recovery at Natural Gas Pressure Reduction Stations

HOWARD, CLIFFORD 13 November 2009 (has links)
This study investigates the performance of a hybrid turboexpander and fuel cell (HTEFC) system for power recovery at natural gas pressure reduction stations. Simulations were created to predict the performance of various system configurations. Natural gas is transported at high pressure across large distances. The pressure of the natural gas must be reduced before it is delivered to the consumer. Natural gas pressure reduction is typically achieved using pressure reduction throttling valves. In a limited number of cases pressure reduction is achieved using a turboexpander. This method has the added bonus of power generation. There is a considerable temperature drop associated with the turboexpander process. Preheating is required in many cases to avoid undesirable effects of a low outlet temperature. This preheating is typically done using gas fired boilers. The hybrid system developed by Enbridge and Fuel Cell Energy is a new approach to this problem. In this system a Molten Carbonate Fuel Cell (MCFC) running on natural gas is used in conjunction with the turbine to preheat the gas and provide additional low emission electrical power Various system configurations were simulated and factors affecting the overall performance of the systems were investigated. Power outputs, fuel requirements and efficiencies of various system configurations were found using typical gas flow variation data. The simulation was performed using input data from the current city gate pressure reduction station operated by Utilities Kingston. Using the data provided by Utilities Kingston the performance of various potential HTEFC system configurations were compared. This thesis illustrates the benefits of using this type of analysis in a feasibility study of future HTEFC systems for power recovery at natural gas pressure reduction stations. Improvements could be made to the accuracy of the simulation results by increasing the complexity of the individual component models. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-11-12 18:35:30.266

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