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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.
1

Black liquor disposal by vortex incineration : a computational approach

Priprem, Sommai January 1990 (has links)
The important role of black liquor in the pulp and paper industry has, been addressed and a review of conventional and potential alternative technologies has been made. Black liquor combustion properties and its combustion within a conventional recovery boiler, the principle of vortex combustion, and methods of computational fluid dynamics were summarized. In order to use the commercially available computational fluid dynamics package, PHOENICS, to simulate black liquor combustion in a vortex combustor, the black liquor combustion process was simplified and modelled and additional software programs were developed and attached to the commercial package. The developed module is capable of tracking trajectory paths of black liquor particles during combustion. A 250 kW vortex combustor was used for some experimental work. The combustor was first tested with natural gas and kerosene. The - combustion conditions were satisfied and their characteristics were presented. Atomization was the main technical problem in the combustion of black liquor. However, the environmental problem was also severe. The results were presented and discussed. Improvements of the system and further studied were suggested. Selection of a suitable turbulence model was made by comparing experimental data with the simulations from various turbulence models. Prandtl mixing length model gave closer predictions than k-? and k-1 model and therefore, it was used for the entire simulations. Simulations of natural gas combustion in a vortex combustor were made to establish skill and confidence in using the package, PHOENICS, to deal with combustion process. A series of black liquor combustion models were performed afterward using the particle tracking module developed. This led to the suggestion of a potential suitable geometry of a vortex combustor for black liquor incineration. The results were presented and discussed. Further simulation studies are also suggested.
2

Reshaping an Enduring Sense of Self: The Process of Recovery from a First Episode of Schizophrenia

Romano, Donna M. 10 July 2009 (has links)
Although many advances in the treatment of schizophrenia have been made over the past decade, little is known about the process of recovery from a first episode of schizophrenia (FES). To date, the study of recovery in the field of mental health has focused on long-term mental illness. This in depth qualitative study drew upon Charmaz’s (1990) constructivist grounded theory methodology to address the following questions: How do individuals who have experienced a FES describe their process of recovery? How does an identified individual (e.g. friend, family member, teacher, or clinician) describe their role during the participant’s process of recovery, and their perception of the recovery process? Ten primary participants (who self-identified as recovering from a FES) had two interviews; in addition, there was a one-time interview with a secondary participant, for a total of 30 interviews. Data collection sources included participant semi-structured interviews, participant selected personal objects that symbolized their recovery, and clinical records. The results provide a substantive theory of the process of recovery from a FES. The emergent process of recovery model for these participants is comprised of the following phases: ‘Lives prior to the illness’, ‘Lives interrupted: Encountering the illness’, ‘Engaging in services and supports’, ‘Re-engaging in life’, ‘Envisioning the future’; and the core category, ‘Re-shaping an enduring sense of self,’ that occurred through all phases. A prominent distinctive feature of this model is that participants’ enduring sense of self were reshaped versus reconstructed throughout their recovery. The emergent model of recovery from a FES is unique, and as such, provides implications for clinical care, future research, and policy development specifically for these young people and their families.
3

Reshaping an Enduring Sense of Self: The Process of Recovery from a First Episode of Schizophrenia

Romano, Donna M. 10 July 2009 (has links)
Although many advances in the treatment of schizophrenia have been made over the past decade, little is known about the process of recovery from a first episode of schizophrenia (FES). To date, the study of recovery in the field of mental health has focused on long-term mental illness. This in depth qualitative study drew upon Charmaz’s (1990) constructivist grounded theory methodology to address the following questions: How do individuals who have experienced a FES describe their process of recovery? How does an identified individual (e.g. friend, family member, teacher, or clinician) describe their role during the participant’s process of recovery, and their perception of the recovery process? Ten primary participants (who self-identified as recovering from a FES) had two interviews; in addition, there was a one-time interview with a secondary participant, for a total of 30 interviews. Data collection sources included participant semi-structured interviews, participant selected personal objects that symbolized their recovery, and clinical records. The results provide a substantive theory of the process of recovery from a FES. The emergent process of recovery model for these participants is comprised of the following phases: ‘Lives prior to the illness’, ‘Lives interrupted: Encountering the illness’, ‘Engaging in services and supports’, ‘Re-engaging in life’, ‘Envisioning the future’; and the core category, ‘Re-shaping an enduring sense of self,’ that occurred through all phases. A prominent distinctive feature of this model is that participants’ enduring sense of self were reshaped versus reconstructed throughout their recovery. The emergent model of recovery from a FES is unique, and as such, provides implications for clinical care, future research, and policy development specifically for these young people and their families.
4

Production of biosurfactant by fermentation with integral foam fractionation

Winterburn, James January 2011 (has links)
Biosurfactants are naturally occurring amphiphiles with potential for use as alternatives to traditional petrochemical and oleochemical surfactants. The unique properties of biosurfactants, including their biodegradability and tolerance of a wide range of temperature and pH, make their use in a range of novel applications attractive. Currently the wider ultilisation of biosurfactants is hindered by a lack of economically viable production routes, with downstream processing presenting a significant challenge. This thesis presents an investigation into the production of HFBII, a hydrophobin protein, using an adsorptive bubble separation technique called foam fractionation for in situ recovery of the biosurfactant. The effects of foaming on the production of HFBII by fermentation were investigated at two different scales. Foaming behaviour was characterised in standard terms of the product enrichment and recovery achieved. Additional specific attention was given to the rate at which foam, product and biomass overflowed from the fermentation system in order to assess the utility of foam fractionation for HFBII recovery. HFBII was expressed as an extracellular product during fed batch fermentations with a genetically modified strain of Saccharomyces cerevisiae, which were carried out with and without antifoam. In the presence of antifoam HFBII production is shown to be largely unaffected by process scale, with similar yields of HFBII on dry matter obtained. More variation in HFBII yield was observed between fermentations without antifoam. In fermentations without antifoam a maximum HFBII enrichment in the foam phase of 94.7 was measured with an overall enrichment of 54.6 at a recovery of 98.1%, leaving a residual HFBII concentration of 5.3 mg L-1 in the fermenter. It is also shown that uncontrolled foaming reduced the concentration of biomass in the fermenter vessel, affecting total production. This series of fermentation experiments illustrates the potential for the application of foam fractionation for efficient in situ recovery of HFBII, through simultaneous high enrichment and recovery which are greater than those reported for similar systems. After the suitability of foam fractionation was demonstrated a novel apparatus design was developed for continuously recovering extracellular biosurfactants from fermenters. The design allows for the operating conditions of the foam fractionation process, feed rate and airflow rate, to be chosen independently of the fermentation parameters. Optimal conditions can then be established for each process, such as the aeration rate required to meet the biological oxygen demand of the cell population. The recirculating foam fractionation process was tested on HFBII producing fermentations. It is shown that by using foam fractionation to strip HFBII from fermentation broth in situ the amount of uncontrolled overflowing from the fermenter was greatly reduced from 770.0 g to 44.8 g, compared to fermentations without foam fractionation. Through optimisation of the foam column operating conditions the proportion of dry matter retained in the fermenter was increased from 88% to 95%, in contrast to a dry matter retention of 66% for fermentation without the new design. With the integrated foam fractionation process a HFBII recovery of 70% was achieved at an enrichment of 6.6. This work demonstrates the utility of integrated foam fractionation in minimising uncontrolled foaming in fermenters whilst recovering an enriched product. This integrated production and separation process has the potential to facilitate improved biosurfactant production, currently a major barrier to their wider use.

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