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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

"Bottoming for Dummies"

Davis, James Phillip 05 1900 (has links)
This book is a guide to bottoming. There are more ways to do it than you might think. Bottoming may be read as passive and intransitive today, but for most of its nearly six hundred years as a verb, "to bottom" has been active and transitive. One goal of this guide is to activate the passive sense of bottoming by connecting it to a wider linguistic history. If the bottom so wishes, their bottoming may be as transitive as bottoming has ever been. A bottom may bottom their top, not merely for their top. The top may be objectified by its want of a bottom. Another proposition: the top, by topping, is bottoming, too. He must be. By outfitting himself with a bottom, he bottoms himself. This guide proposes a marriage of active and passive, bumming and bottoming, sexual and nonsexual bottoms. It embraces the versatility inherent in "bottom" and seeks enlightenment through the vast, ever-expanding network this word has woven through our language. It aims to bottom you, the reader, around its thesis (i.e., its bottom): Everybody bottoms. Or at least, everybody should.
2

Examining The Influences Of The Bottoming Out Experience And The Turning Point On The Early Recovery Process From Substance Dependence Using Structural Equation Modeling

DePue, Kristina M 01 January 2013 (has links)
Considering the prevalence of addiction issues within the U.S., this study focused on the topic of recovery from drug and alcohol dependence in order to add to current literature. Prevention and recovery services are two of the most common ways of combating the addiction issue, and counselors are at the forefront of both movements. The bottoming out experience (BOE) and the turning point (TTP) are two common lay terms of factors within changing addictive behaviors, yet the connection of these constructs to recovery remains unstudied and unknown. The current study tested a model that levels of the BOE and the TTP are predictive of early recovery (ER). The data from this study was obtained from a national dataset previously collected from 230 grant-funded addiction treatment centers that utilize the Global Assessment of Individual Needs (GAIN) assessment instrument. A review of the literature gaps, coupled with available data, influenced decisions on research design and statistical analysis procedures. As clear definitions of the BOE, TTP, and ER have not been discovered through research, a descriptive, correlational research design was chosen in order to understand not only what constitutes a BOE, TTP, and ER, but also to discover the relationships between the BOE, TTP, and ER in their natural state. The purpose of correlational studies is to investigate the relationship between two or more variables without researcher manipulation and such designs are common in the counseling and counselor education research field (Heppner, et al., 2008). Because correlational research is exploratory in nature, structural equation modeling (SEM) was utilized to understand the components of each construct and was used to test the hypothesis of the relationships iv between the BOE, TTP and ER. Although SEM is a confirmatory technique, it is frequently used in an exploratory manner because it combines elements of confirmatory factor analysis and multiple regressions and allows for various possibilities of the relationships between constructs and variables (Schrieber, et al., 2006). The literature on ER, BOE, and TTP provides enough evidence to test a theoretical model, which is the purpose of SEM. The hypothesized model assessed data at intake for the BOE, TTP and ER. Once constructs were delineated through measurement models/CFA, SEM path analysis was used to understand how the constructs related to one another. The first three hypotheses were rejected in the study, and measurement model modifications were conducted, which yielded good fit indices. Results from Hypothesis One indicated that hypothesized factors did not load on the BOE, and instead, the BOE at the intake level was a measurement of mental health severity. Results from Hypothesis Two indicated that hypothesized factors did not load on TTP; however, TTP did resulting factor structure created through model modification contained factors of awareness, motivation, and support. Results from Hypothesis Three also indicated that hypothesized indicators did not load into ER; however the resulting factor structure contained indicators of abstinence and environmental support. Lastly, Hypothesis Four yielded three resulting models, all of which had good fit indices. Therefore, hypothesis four was accepted. It is noteworthy that direct effects were not all significant, and the p value in all final models was significant. There was not a significant relationship between the BOE and ER at the intake level; however, there was a significant relationship between the BOE and TTP, as well as TTP and ER at the intake level. The direct v effects between the BOE and ER may have had a role in the significant p values, as well as the large sample size. Within the three resulting models, the BOE had significant relationships with TTP, spiritual support, and motivation. Both spiritual support and motivation also had significant relationships with ER. Therefore, the results from the current study support that there are existing relationships between the BOE and TTP; however, the relationship between the BOE and ER at the intake level was not significant.
3

Advanced power cycles with mixture as the working fluid

Jonsson, Maria January 2003 (has links)
The world demand for electrical power increasescontinuously, requiring efficient and low-cost methods forpower generation. This thesis investigates two advanced powercycles with mixtures as the working fluid: the Kalina cycle,alternatively called the ammonia-water cycle, and theevaporative gas turbine cycle. These cycles have the potentialof improved performance regarding electrical efficiency,specific power output, specific investment cost and cost ofelectricity compared with the conventional technology, sincethe mixture working fluids enable efficient energyrecovery. This thesis shows that the ammonia-water cycle has a betterthermodynamic performance than the steam Rankine cycle as abottoming process for natural gas-fired gas and gas-dieselengines, since the majority of the ammonia-water cycleconfigurations investigated generated more power than steamcycles. The best ammonia-water cycle produced approximately40-50 % more power than a single-pressure steam cycle and 20-24% more power than a dual-pressure steam cycle. The investmentcost for an ammonia-water bottoming cycle is probably higherthan for a steam cycle; however, the specific investment costmay be lower due to the higher power output. A comparison between combined cycles with ammonia-waterbottoming processes and evaporative gas turbine cycles showedthat the ammonia-water cycle could recover the exhaust gasenergy of a high pressure ratio gas turbine more efficientlythan a part-flow evaporative gas turbine cycle. For a mediumpressure ratio gas turbine, the situation was the opposite,except when a complex ammonia-water cycle configuration withreheat was used. An exergy analysis showed that evaporativecycles with part-flow humidification could recover energy asefficiently as, or more efficiently than, full-flow cycles. Aneconomic analysis confirmed that the specific investment costfor part-flow cycles was lower than for full-flow cycles, sincepart-flow humidification reduces the heat exchanger area andhumidification tower volume. In addition, the part-flow cycleshad lower or similar costs of electricity compared with thefull-flow cycles. Compared with combined cycles, the part-flowevaporative cycles had significantly lower total and specificinvestment costs and lower or almost equal costs ofelectricity; thus, part-flow evaporative cycles could competewith the combined cycle for mid-size power generation. <b>Keywords:</b>power cycle, mixture working fluid, Kalinacycle, ammonia-water mixture, reciprocating internal combustionengine, bottoming cycle, gas turbine, evaporative gas turbine,air-water mixture, exergy
4

Advanced power cycles with mixture as the working fluid

Jonsson, Maria January 2003 (has links)
<p>The world demand for electrical power increasescontinuously, requiring efficient and low-cost methods forpower generation. This thesis investigates two advanced powercycles with mixtures as the working fluid: the Kalina cycle,alternatively called the ammonia-water cycle, and theevaporative gas turbine cycle. These cycles have the potentialof improved performance regarding electrical efficiency,specific power output, specific investment cost and cost ofelectricity compared with the conventional technology, sincethe mixture working fluids enable efficient energyrecovery.</p><p>This thesis shows that the ammonia-water cycle has a betterthermodynamic performance than the steam Rankine cycle as abottoming process for natural gas-fired gas and gas-dieselengines, since the majority of the ammonia-water cycleconfigurations investigated generated more power than steamcycles. The best ammonia-water cycle produced approximately40-50 % more power than a single-pressure steam cycle and 20-24% more power than a dual-pressure steam cycle. The investmentcost for an ammonia-water bottoming cycle is probably higherthan for a steam cycle; however, the specific investment costmay be lower due to the higher power output.</p><p>A comparison between combined cycles with ammonia-waterbottoming processes and evaporative gas turbine cycles showedthat the ammonia-water cycle could recover the exhaust gasenergy of a high pressure ratio gas turbine more efficientlythan a part-flow evaporative gas turbine cycle. For a mediumpressure ratio gas turbine, the situation was the opposite,except when a complex ammonia-water cycle configuration withreheat was used. An exergy analysis showed that evaporativecycles with part-flow humidification could recover energy asefficiently as, or more efficiently than, full-flow cycles. Aneconomic analysis confirmed that the specific investment costfor part-flow cycles was lower than for full-flow cycles, sincepart-flow humidification reduces the heat exchanger area andhumidification tower volume. In addition, the part-flow cycleshad lower or similar costs of electricity compared with thefull-flow cycles. Compared with combined cycles, the part-flowevaporative cycles had significantly lower total and specificinvestment costs and lower or almost equal costs ofelectricity; thus, part-flow evaporative cycles could competewith the combined cycle for mid-size power generation.</p><p><b>Keywords:</b>power cycle, mixture working fluid, Kalinacycle, ammonia-water mixture, reciprocating internal combustionengine, bottoming cycle, gas turbine, evaporative gas turbine,air-water mixture, exergy</p>
5

Exhaust system energy management of internal combustion engines

Wijewardane, M. Anusha January 2012 (has links)
Today, the investigation of fuel economy improvements in internal combustion engines (ICEs) has become the most significant research interest among the automobile manufacturers and researchers. The scarcity of natural resources, progressively increasing oil prices, carbon dioxide taxation and stringent emission regulations all make fuel economy research relevant and compelling. The enhancement of engine performance solely using incylinder techniques is proving increasingly difficult and as a consequence the concept of exhaust energy recovery has emerged as an area of considerable interest. Three main energy recovery systems have been identified that are at various stages of investigation. Vapour power bottoming cycles and turbo-compounding devices have already been applied in commercially available marine engines and automobiles. Although the fuel economy benefits are substantial, system design implications have limited their adaptation due to the additional components and the complexity of the resulting system. In this context, thermo-electric (TE) generation systems, though still in their infancy for vehicle applications have been identified as attractive, promising and solid state candidates of low complexity. The performance of these devices is limited to the relative infancy of materials investigations and module architectures. There is great potential to be explored. The initial modelling work reported in this study shows that with current materials and construction technology, thermo-electric devices could be produced to displace the alternator of the light duty vehicles, providing the fuel economy benefits of 3.9%-4.7% for passenger cars and 7.4% for passenger buses. More efficient thermo-electric materials could increase the fuel economy significantly resulting in a substantially improved business case. The dynamic behaviour of the thermo-electric generator (TEG) applied in both, main exhaust gas stream and exhaust gas recirculation (EGR) path of light duty and heavy duty engines were studied through a series of experimental and modelling programs. The analyses of the thermo-electric generation systems have highlighted the need for advanced heat exchanger design as well as the improved materials to enhance the performance of these systems. These research requirements led to the need for a systems evaluation technique typified by hardware-in-the-loop (HIL) testing method to evaluate heat exchange and materials options. HIL methods have been used during this study to estimate both the output power and the exhaust back pressure created by the device. The work has established the feasibility of a new approach to heat exchange devices for thermo-electric systems. Based on design projections and the predicted performance of new materials, the potential to match the performance of established heat recovery methods has been demonstrated.

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