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None. / Arts, Faculty of / Music, School of / Additional material: 1 video cassette (Koerner Library). / Graduate

None. / Arts, Faculty of / Music, School of / Additional material: 1 video (Koerner Library). / Graduate

No description available.

The widespread use of high temperature superconductors through improved understanding of their underlying physics is in part dependent on the synthesis of large, high quality single crystals for physical research. Crucible corrosion is an important factor hindering the routine synthesis of large, high purity rare-earth barium cuprate superconductor single crystals. Molten BaCuO2-CuO fluxes required for the growth of such crystals are highly corrosive to substrate materials, and corrosion products may lead to chemical contamination of crystals and other practical difficulties. BaZrO3 is known to be inert to BaCuO2-CuO melts, but its use has remained restricted to a very small number of laboratories worldwide because it is very sensitive to the effects of off- stoichiometric or residual secondary phases which degrade its performance. BaZrO3 suitable for sustained melt containment is difficult to produce due to kinetic limitations of phase purity, difficulty in sintering to adequate density, and very narrow stoichiometry tolerances of finished ceramics. The existing literature provided a guide to the production of high quality BaZrO3, but was not sufficiently complete to readily allow production of crucibles suitable for this application. The two basic aims of this project were: To provide a comprehensive and quantitative description of the necessary attributes of crucibles for barium cuprate melt processing and to expand the knowledge of solid-state BaZrO3 processing to encourage its widespread application to crucible manufacture; To explore the application of solution chemical processes whose potential benefits could lead to routine application of BaZrO3 through improved ceramic quality and processing properties. / Based primarily on solid-state processing research, the optimal stoichiometry for corrosion resistant crucibles was observed over the narrow range of 1.003±0.003 Ba : (Zr + Ht) mole ratio. Residual ZrO2 must be strictly avoided even at very low levels because severe localized expansion of Z a grains during reaction with the melt severely reduces corrosion resistance. Although the effect of Ba-rich phases are less severe, their abundance must be suppressed as much as allowed by the production process. Solid-state derived crucibles with a large barium excess were unstable and readily attacked by water. TEM analysis clearly showed residual Zr02 was present as discrete grains and not as grain boundary films, and also the prevalence of intragranular defects in Ba-rich ceramics. Quantitative knowledge of the narrow range of required stoichiometry is critical for developing successful solid-state and solution chemical processes. Reliably achieving the required stoichiometry and phase purity is experimentally challenging and beyond the capability of many processing systems. Systematic investigation revealed sharp changes in physical properties of processed powders across the phase boundary. The resistance of BaZrO3, of the desired stoichiometry to grain growth during powder processing has not previously been reported in the available literature. At the desired stoichiometry for corrosion resistance, powder grain growth resistance combined with very precise control over stoichiometry makes the solid-state process more competitive with solution-based processes than previously acknowledged in the literature. The development of solution processes for BaZr03 precursors is complicated by aqueous chemistry of zirconium compounds. / This project developed the first chemically derived precursor process demonstrated to produce a ceramic of adequate quality for sustained barium cuprate melt containment. The barium acetate / zirconium oxychloride / ammonium oxalate system provided control over stoichiometry without requiring elevated solution temperatures, a large excess of barium reagents, or reagents containing alkalis. Despite showing the capability to supersede the solid-state process, the oxalate process still requires further refinement to more reliably achieve high sintered densities. Although the attributes required for sustained barium cuprate melt containment are now clear, its routine mass production remains reliant on further development of solution chemical techniques or improvements to the kinetics of solid-state processing. This project advanced ceramic design and processing technology in the BaZrO3 system and provided new approaches in meeting the challenging analytical needs of research and process control for high quality production of this compound.

Theory on leadership has emphasised the need for contributing towards leadership in extreme context. Give the rise in crisis, and the study aims to contribute by exploring how crucible moments can contribute towards leader’s development for crisis management. The objective of the study is to use the insights gained from the leader’s journey to develop a framework to contribute towards leadership development for crisis management. A narrative approach is used in this qualitative study and explores the themes identified from the leader's life journey. Semi-structured interviews were conducted with 13 executives in manufacturing organisation within the automotive sector, in the eThekwini region in Kwa-Zulu Natal. The research found that crucible experiences have contributed towards developing leader’s identity through self-awareness and discovering their potential. They learned decision making and allowed for change to occur. Crucible experience is also related to transformational learning, as it provided a trigger for learning. Leaders developed their approach for crisis management through applied experience and stepping up in a crisis. This crucible experience has found to contribute towards the leader's approach to crisis management. / Mini Dissertation (MBA)--University of Pretoria, 2021. / Gordon Institute of Business Science (GIBS) / MBA / Unrestricted

The innovation of crucible steel, a high-carbon, homogeneous, slag-free steel, is regarded as a milestone in the history of the development of ferrous metallurgy. Associated in popular literature with the making of swords, particularly in the Early Islamic period, crucible steel, also known as wootz, possesses exceptional properties of hardness and strength. While much is now understood about its metallurgical composition and structure, little is known of its origins and spread. Few archaeological sites have been uncovered and to date pre-industrial production of this alloy is only known from Central Asia and South Asia. Previous studies have largely focused on individual sites in isolation from wider regional patterns of ferrous metallurgy. As a refining process of iron, it is argued here that crucible steel has a symbiotic relationship with the smelting technologies that produced the raw material for refining. This thesis explores the value of assessing crucible steel production within its wider landscape, cultural and technological context by presenting the evidence from Northern Telangana, India. Historical sources and recent archaeological field surveys have shown that Telangana has a rich metallurgical past, including the manufacture of crucible steel. Despite this, little archaeological work has been conducted in the region to elucidate the nature, scale and diversity of the metallurgical technologies that underpinned its production. Following a major reconnaissance survey in 2010 by the Pioneering Metallurgy Project, the present study tackled the assessment of the large body of field data and the recording of the technological waste assemblage collected. By combining detailed morphological analyses of the collected materials and contextual information recorded during field survey, a better understanding of the techno-cultural role of crucible steel was gained. Technological variations were identified across the survey area and the inter-relationship between iron smelting and crucible steel was assessed. The study reveals that crucible steel was embedded within a long-established local and regional tradition of iron smelting and concludes that it represented the intensification of a pre-existing iron processing industry. The evidence points to a widespread crucible steel production industry with varying degrees of site specialisation, indicating that it was perhaps more common than the few isolated sites commonly referred to in the literature suggests. The comparison of the material evidence with other production sites in Central and South Asia also revealed close parallels to the latter suggesting that they belonged to the same regional manufacturing tradition.

According to Warren Bennis with Robert J. Thomas Ph.D. research, cultivation of outstanding leadership is blend of past experience and self-conscious order come .This shaping process is called Crucible experiences. As the Manchu Dynasty's senior political and military commander, Zuo is undoubtedly the outstanding leadership representative. He organized Chu military to put down Taiping Heavenly Kingdom; forced in creating Fuzhou Ship Bureau to reinforce navy; lead the army expedition to the Northwest, to recover in Xinjiang; resisted the French army advancing along the southeast coast. Not too long in his political career, accomplished many achievements. How come is his leadership? Are there any points for modern leaders to learn? These are the questions this study to explore. Zuo as object, the study is through original and the results of previous studies for data collection. And then to lead the crucible theory as the framework, by qualitative research in the case studies and narrative research methods, etc. way to sum up the refined process of good leadership and proven crucible experience in the role of Zuo. And further settle objectives and plans which can be practiced of the modern leaders. Crucible experience is divided into three types namely¡§New territory¡¨,¡§Enforced reflection¡¨and¡§Disruption and loss¡¨. The study found that three kinds of crucible experience played key role by Zuo, lead he grown up enough to become good leaders. The three experiences of crucible advance nine life experiences can be deduced:¡§Self-examination¡¨,¡§Know who the next¡¨,¡§Intentions with people¡¨,¡§Overcome the fear¡¨,¡§Convince others¡¨,¡§Assumed the task¡¨,¡§Make difficult decisions¡¨,¡§Keep calm and solve mysteries¡¨, and¡§Organize a team¡¨.Finally, submit a practice checklist for plan to cultivate leadership.

This dissertation reports the development of two new categories of optical fibers. These are the Random Hole Optical Fiber (RHOF) and the Crucible Technique Hybrid Fiber (CTF). The RHOF is a new class of microstructure fiber which possesses air holes which vary in diameter and location along the length of the fiber. Unlike all prior microstructure fibers, these RHOF do not have continuous air holes which extend throughout the fiber. The CTF is a method for incorporating glasses with vastly differing thermal properties into a single optical fiber. Each of these two classes of fiber brings a new set of optical characteristics into being. The RHOF exhibit many of the same guidance properties as the previously researched microstructure fibers, such as reduced mode counts in a large area core. CTF fibers show great promise for integrating core materials with extremely high levels of nonlinearity or gain. The initial goal of this work was to combine the two techniques to form a fiber with exceedingly high efficiency of nonlinear interactions. Numerous methods have been endeavored in the attempt to achieve the fabrication of the RHOF. Some of the methods include the use of sol-gel glass, microbubbles, various silica powders, and silica powders with the incorporation of gas producing agents. Through careful balancing of the competing forces of surface tension and internal pressure it has been possible to produce an optical fiber which guides light successfully. The optical loss of these fibers depends strongly on the geometrical arrangement of the air holes. Fibers with a higher number of smaller holes possess a markedly lower attenuation. RHOF also possess, to at least some degree the reduced mode number which has been extensively reported in the past for ordered hole fibers. Remarkably, the RHOF are also inherently pressure sensitive. When force is applied to an RHOF either isotropically, or on an axis perpendicular to the length of the fiber, a wavelength dependent loss is observed. This loss does not come with a corresponding response to temperature, rendering the RHOF highly anomalous in the area of fiber optic sensing techniques. Furthermore an ordered hole fiber was also tested to determine that this was not merely a hitherto undisclosed property of all microstructure fibers. Crucible technique fibers have also been fabricated by constructing an extremely thick walled silica tube, which is sealed at the bottom. A piece of the glass that is desired for the core (such as Lead Indium Phosphate) is inserted into the hole which is in the center of the tube. The preform is then drawn on an fiber draw tower, resulting in a fiber with a core consisting of a material which has a coefficient of thermal expansion (CTE) or a melting temperature (Tm) which is not commonly compatible with those of silica. / Ph. D.