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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.
41

The Study of Reactor Wall Fouling in Gas-solid Fluidized Beds Caused by Electrostatic Charge Generation

Sowinski, Andrew 25 September 2012 (has links)
Electrostatic charge generation is unavoidable in gas-solid fluidized beds due to the repeated particle-particle and particle reactor wall contacts and separations. In industrial operations such as in polyethylene production this phenomenon results in the significant problem of reactor wall fouling, known as “sheeting”. To better understand the underlying charging mechanisms involved in gas-solid fluidized beds in an attempt to eliminate and/or reduce the effect a novel on-line electrostatic charge measurement technique was developed, which concurrently provided information on both the degree of fluidized bed electrification and reactor wall fouling. A Faraday cup replaced the windbox of the fluidized bed while another cup was placed at the top of the column. The distributor plate was uniquely designed for the systematic removal of bed particles and those adhered to the column wall for their charge measurement with the bottom Faraday cup, and the charge of the entrained particles was measured by the top Faraday cup. This is the first study which allowed the charge measurement of particles in the bulk of the bed, particles adhered to the column wall, and those entrained, simultaneously. In addition, this method uniquely permitted the evaluations of the degree of reactor wall fouling under different operating conditions. An experimental program was designed to investigate the influence of bed hydrodynamics (fluidizing gas velocity and particle size), fluidization column wall material, and the addition of different solid additives. Fluidizing particles were polyethylene resin from an industrial reactor. Bi-polar charging was observed where the elutriated particles were oppositely charged compared to those in the bulk of the bed and those adhered to the column wall. Particles within the wall coating were also found to be bi-polarly charged. With the resin tested as received, a certain sized particles (350-575 µm) adhered to the column wall. The specific charge of the particles near the column wall was found not to be a definite indication of the amount of wall fouling. Increasing the gas velocity promoted wall fouling and elevated the charge density of the particles within both bubbling and slugging flow regimes. The effect of solid additive injection was examined with two static drivers known to reduce wall fouling in industrial operations, a deactivated catalyst, and the catalyst support. It was found that the catalyst promoted, while one of the static drivers reduced wall fouling.
42

The strategic role of cultural and heritage tourism in the context of a mega-event : the case of the 2010 Soccer World Cup

Steyn, Tania 04 August 2008 (has links)
Increasingly, tourism marketers and event organisers are acknowledging that the hosting of a mega-event can leave meaningful legacies for the people of the destination that extend far beyond the actual duration of the event. This research study proposes that one way to secure sustainable legacies for a host destination, is to leverage cultural and heritage tourism opportunities within the context of an event. Though, there is an indication that cultural and heritage tourism can play a major role in the event experience, a lack of information in this field currently limits the ability of host destinations to optimally leverage these opportunities. Based on this need for research in the combined field of cultural and heritage tourism and mega-events, the purpose of this qualitative research study was to explore the potential contributions of cultural and heritage tourism within the context of a mega-event. The City of Tshwane, a key host city in the 2010 Soccer World Cup, has been selected as an appropriate case study for this research. During the secondary data collection process, various best-practice mega-event case studies were explored, to determine the contributions of cultural and heritage tourism within each event. Based on this analysis, six cultural and heritage tourism opportunities were identified. Semi-structured, in-depth interviews were then utilised to obtain the views of stakeholders in the City of Tshwane regarding the potential cultural and heritage tourism opportunities in the hosting of the 2010 Soccer World Cup. Based on the findings from international and local best-practice case studies and stakeholder interviews, a model and strategic guidelines were developed to assist host destinations to optimally leverage cultural and heritage tourism opportunities in the hosting of an event. Critical success factors to optimally leverage these opportunities were also highlighted. This research study adds value to the existing body of knowledge in the fields of cultural and heritage tourism and mega-events and also provides additional perspectives in this regard. Finally, the City of Tshwane can become a role model for other host cities in leveraging cultural and heritage tourism opportunities within the context of the 2010 Soccer World Cup. / Dissertation (MCom)--University of Pretoria, 2011. / Tourism Management / unrestricted
43

COMPARATIVE ANALYSIS OF SWAT CUP AND SWATSHARE FOR CALIBRATING SWAT MODELS

Kuan Hung Lin (9179471) 29 July 2020 (has links)
<p>Soil and water assessment tool model (SWAT model) is a widely used model when dealing with large and complex watershed simulations. To correctly predict runoff of a watershed, auto-calibration methods are applied. Among all the platforms, SWAT CUP is widely used in the SWAT model community. The new web-based calibration platform: SWATShare is also gaining its popularity due to the benefits of user-friendly interface, access to high-performance computing resources, and collaborative interface. While the algorithm implemented in SWAT CUP is Sequential Uncertainty Fitting version 2 (SUFI2), Sorting Genetic Algorithm II (NSGA-II) is the algorithm employed by SWATShare. There is a limited amount of research comparing the model performance between these two calibration algorithms and platforms. </p> <p> </p> <p>This study aims to examine whether the performances of calibrated models are providing equally reliable results. Thirty US watersheds are studied in this research, SWAT models were calibrated using seven years of rainfall data and outflow observations from 2001 to 2007, and then the models were validated using three years of historical records from 2008 to 2010. Inconsistency exists between different algorithms calibrated parameter sets, and the percentage difference between parameter values ranges from 8.7% to 331.5%. However, in two-thirds of the study basins, there is no significant difference between objective function values in two algorithms calibrated models. Correlations are examined using values of parameters and watershed features. Among all the features and parameters, Length of reach and GW_DELAY, CH_N2 and ALPHA_BF, climate zone and GWQMN, SFTMP and NSE have medium correlation exist in both SWATShare and SWAT CUP calibrated models among 30 watersheds. The correlation coefficient difference between them are less than 0.1. When visualizing results by Ecoregions, KGE and NSE are similar in calibrated models from both tools. </p> <p> </p> <p>The initial parameter range used for SWAT CUP calibration could lead to satisfactory results with greater than 0.5 objective function values. However, the parameter values of the calibrated model might not be presenting a real physical condition since they are out of the realistic range. The inaccurate parameter values might lead to lower objective function values in the validation. The objective function values can be improved by setting the range of parameter values to match the realistic values. </p> <p> </p> <p> </p> <p>By comparing two tools, SWATShare accurately calibrates parameter values to a realistic range using default range in most cases. For those models with an unsatisfactory result from SWATShare, the objective function values could be improved after specifying the parameters to the best-fit range given by SWAT CUP results. Also, for those watersheds which have similar satisfactory calibrated objective values from both tools, constraining the parameter to a reasonable range could generate a new calibrated model that performs as well as the original one. Using the approach to constrain parameter values to a realistic range gradually can exclude some statistically satisfactory but physically meaningless models. Comparing two auto-calibration software, SWATShare accurately calibrates parameter values to a realistic range using default range in most cases. Also, in some of the ecoregions, the best parameter sets in SWATShare fall in a more physically meaningful range. Overall, the newly emerged platform, SWATShare, is found to have the capability of conducting good SWAT model calibration. </p>
44

Self-Formation of Optic Cups and Storable Stratified Neural Retina from Human ESCs / ヒトES細胞からの眼杯および保存可能な多層網膜組織の自己組織化

Nakano, Tokushige 23 January 2014 (has links)
京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12800号 / 論医博第2072号 / 新制||医||1001(附属図書館) / 80844 / (主査)教授 髙橋 淳, 教授 吉村 長久, 教授 江藤 浩之 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM
45

OPTIMAL CONTROL OF THE AC75 SAILBOAT FOR THE AMERICA'S CUP RACE

Rodriguez Nunez, Renato January 2021 (has links)
This research focuses on the development of optimal sailing maneuvers for an AC75 foiling sailboat competing in the America's Cup. The America's Cup is the oldest, most prestigious, and technologically advanced sailboat racing competition in the world. Each iteration brings new and innovative sailboat designs which drastically improve sailing performance but increase complexity in the control of the sailboat system. This added complexity in the design and operation of the AC75 sailboat presents many challenges to the development of optimal sailing maneuvers. These challenges arise from the introduction of extra degrees of freedom and articulations in the boat such as the canting mechanisms (hydrofoils), which result in complex dynamical behaviors. The sailboat system is nonlinear, high-dimensional, and highly unstable. These complex characteristics require the development of high-order models, which are often intractable, or which introduce significant delays making them not well-suited for real-time control. The optimal maneuvers were achieved via the exploration of out-of-the-box solutions through data-driven controls and optimization. We used a high-fidelity sailboat simulator for the data generation process, and data-driven optimization schemes, such as Artificial Neural Networks (ANN), Extremum Seeking Control (ESC), and Jacobian Learning (JL) to optimize the sailing maneuvers. The optimizations were performed separately on various sailing maneuvers including close-hauled, tacking, and takeoff, as well as combinations of these maneuvers as performed during a race. The close-hauled and tacking maneuvers were optimized to achieve maximum Velocity Made Good (VMG) and minimum loss of VMG, respectively. The takeoff maneuver was optimized for maximum VMG and minimum time for the boat's transitions from displacement mode to foiling mode. The optimal solutions are subject to physical constraints and operational constraints enforced by the humans (sailors) in the loop. These maneuvers were developed for various heading angles (True Wind Angle (TWA)) and environmental conditions, such as True Wind Speed (TWS). Additionally, we performed an in-depth analysis of the optimal parameter settings obtained for close-hauled sailing to discern general trends in the parameter space. The trend of optimal parameters versus the wind direction provides a good understanding of the parameter space for varying sailing directions which can help guide the sailor's decisions during a race. The results show how optimization and controls can play a significant role in the development of advisory systems for complex human-operated systems. Lastly, the maneuvers developed in this search serve as performance benchmarks and provide insightful information about the underlying dynamics of the boat. / Mechanical Engineering
46

"I Believe that We Will Win!": American Myth-Making and the World Cup

Burkel, Michael T. 19 June 2015 (has links)
No description available.
47

Attrition Behavior of Oxygen Carrier Particles and Pressure Fluctuations in Chemical Looping Systems

Shah, Vedant Ravindra 15 August 2018 (has links)
No description available.
48

CHARACTERIZATION OF CUP ANEMOMETER DYNAMICS AND CALCULATION OF THE ACOUSTIC NOISE PRODUCED BY A NREL PHASE VI WIND TURBINE BLADE

Chen, Yng-Ru 31 May 2016 (has links)
No description available.
49

An Ugly Side to the Beautiful Game? An Analysis of Broadcast Commentary of FIFA World Cup and FIFA Women's World Cup Final Matches

Fink, Blayne Kathryn 26 June 2019 (has links)
Previous research into sporting events and broadcast commentary have been consistent in showing that there are clear differences in prevalence of commentary topics when a commentator is describing a male athlete and a female athlete. Among these differences are sexualized and ambivalent language towards female athletes, gender marking, and language that suggests male athlete superiority to that of female athletes. Although sporting events such as the Summer and Winter Olympics and NCAA Men's and Women's Basketball Championship games have repeatedly been sites for exploration, the world's largest single-event sporting competition, the World Cup, remains relatively untouched. Keeping this in mind, using a systematic content analysis, this thesis analyzed the broadcast commentary provided by play-by-play and color commentators in FIFA World Cup and FIFA Women's World Cup final matches to discern whether or not the sex of the athlete competing resulted in a difference in the descriptive evaluations employed by commentators. Findings of this study revealed that there were few differences in the prevalence of descriptive evaluations based on the gender of the athletes competing. Implications of the results and recommendations for future research into broadcast commentary and World Cup final matches are addressed. / Master of Arts / Previous research into the role of broadcast commentary in sporting events has shown that not only are there differences in what sports commentators say about male and female athletes, but also in how often specific types of commentary occur. Through the examination of pinnacle athletic competitions, findings have revealed a higher frequency of sexualized and contradictory language towards female athletes, an increase in gender marking, and language that suggests the superiority of male athletes to that of female athletes, among other things. Despite the wide range of athletic competitions that have garnered research attention, one event that has remained relatively ignored is the FIFA World Cup. Because of this, by examining the broadcast commentary provided during FIFA World Cup and FIFA Women’s World Cup final matches, this study looked to discover if the sex of the athlete competing impacted how often certain evaluation types occurred during game action. Findings showed that there were few differences in the prevalence of these evaluations based on the sex of the athlete competing. In addition to discussing the findings of this study, recommendations for future research are also addressed.
50

Carcinoma of Unknown Primary – an Orphan Disease?

Krämer, Alwin, Hübner, Gerdt, Schneeweiss, Andreas, Folprecht, Gunnar, Neben, Kai 05 March 2014 (has links) (PDF)
Carcinoma of unknown primary (CUP) is an intriguing clinical finding that is defined as biopsy-proven metastasis from a malignancy in the absence of an identifiable primary site after a complete clinical work-up. CUP is a relatively common clinical entity, accounting for approximately 3–5% of all cancer diagnoses, and consists of a heterogeneous group of tumors that have acquired the capacity to metastasize before the development of a clinically evident primary lesion. Notable advances have been made over the past years in the treatment of well-defined clinical subgroups of CUP, such as women with peritoneal carcinomatosis and young adults with poorly differentiated carcinomas of midline distribution, but for the majority of patients, the prognosis still remains poor. In this review, we highlight recent advances in the diagnosis and treatment of patients with CUP syndrome, and emphasize the importance of identifying several favorable subsets of CUP, amenable to specific treatment options. In addition, we will point out novel diagnostic and therapeutic approaches which will hopefully improve both our understanding and the prognosis of this more or less neglected disease. / Unter dem Cancer of Unknown Primary (CUP)-Syndrom werden diejenigen Tumorerkrankungen zusammengefasst, bei denen auch nach Abschluss der Diagnostik nur Metastasen, jedoch kein Primärtumor gefunden wird. Das CUP-Syndrom macht ca. 3–5% aller neu diagnostizierten Malignomfälle aus und umfasst eine heterogene Gruppe von Tumoren, die die Fähigkeit zur Metastasierung erlangt haben bevor sich ein klinisch manifester Primärtumor entwickelt hat. Obwohl bemerkenswerte Fortschritte in der Behandlung von Patienten mit bestimmten, gut definierten Erkrankungssubgruppen, wie beispielsweise Frauen mit isolierter Peritonealkarzinose oder jungen Erwachsenen mit gering differenzierten Karzinomen mit Mittellinienverteilung, erzielt werden konnten, ist die Prognose bei der Mehrzahl der Patienten nach wie vor schlecht. Wir berichten im weiteren Verlauf dieser Übersichtsarbeit über Fortschritte in der Diagnostik und Therapie von Patienten mit CUPSyndrom und weisen darauf hin, dass es trotz der immer noch sehr schlechten Prognose von großer Bedeutung ist, Patienten mit bestimmten Subtypen des CUP-Syndroms zu identifizieren, die spezifischen Therapien mit der Option auf Heilung zugeführt werden sollten. Darüber hinaus möchten wir auf neuere diagnostische und therapeutische Bestrebungen aufmerksam machen, die das Verständnis und die Prognose dieses auch in der Onkologie bisher stiefmütterlich behandelten Krankheitsbildes hoffentlich verbessern werden. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

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