Texte remanié de: Th.--Zurich--Faculté des lettres de l'Université de Zurich, 1997-1998. / Bibliogr. p. 139-152. Notes bibliogr.

Thesis (M.Sc.), Memorial University of Newfoundland, 2000. / Bibliography: p. 100-106.

Thermogravimetry, coupled with a mass spectrometer (TG-MS) was used to investigate the catalytic effect potassium carbonate (K2CO3) and potassium chloride (KCl), on the char conversion and the product gas composition of chars derived from a South African inertinite-rich bituminous coal. Sequential leaching of the coal with HCl-HF-HCl was performed to reduce the mineral matter present in the coal. This was done in order to reduce possible undesirable interactions between the minerals and inorganic compounds in the coal during heat treatments. The leaching process substantially reduced the ash content from 21.5% to less than 3%. K2CO3 and KCl [0.5, 1, 3, 5 K-wt %] were loaded to the demineralized coal, raw coal and demineralized coal with added mineral mixture prior to charring. The mineral mixture was made up of kaolinite, quartz, pyrite, siderite, calcite, anastase and hydromagnesite. The ‘doped’ coal samples were then subjected to heat treatments in a CO2 atmosphere up to 1200 °C. The results obtained showed that both K2CO3 and KCl exhibit a catalytic effect on the char conversion during heat treatments in CO2 atmosphere and the char conversion was increased with increasing loadings up to 5 K-wt% of K2CO3 and KCl. The temperature ranges at which conversion occurred were found to be lower for K2CO3 than for KCl. Subsequently, char conversion occurred over a relatively narrower temperature range for K2CO3 than observed for KCl. The catalytic behaviour of K2CO3 and KCl was confirmed by the results obtained. The results also indicated that the catalytic influence of K2CO3 is greater than that of KCl and that KCl is more susceptible to deactivation by minerals and inorganic compounds present in the coal than K2CO3. Different analytical techniques (XRF and XRD) were used to determine the extent of interaction of the catalysts used with the char material in the 5 K-wt% ‘doped’ coal samples. From the XRF results, it was observed that the K2O content was reduced after heat treatments in CO2, however, no potassium crystalline phases were observed in the XRD results after heat treatments in CO2. The reduced K2O content may be attributed to the potassium been taken up in other mineral matter during char reaction with CO2, forming new amorphous inorganic complex compounds. Thus the potassium retained in the sample after heat treatment, indicated by the XRF results, may be in an amorphous phase. Mass spectrometry (MS) indicated that temperatures at which the maximum rate of evolution of gaseous species occurred were relatively lower for K2CO3 loaded char samples iv than observed for KCl loaded samples. In addition, no mass-to-charge ratio (m/z) peak at 39 atomic mass unit (amu) from the MS results was observed, indicating that no potassium was detected in the gaseous phases for all the char samples. The undetected potassium in the gaseous phase may be due to the detection limit of the MS equipment. The MS results also indicated that addition of the catalyst facilitates the evolution of H2 from the coal char samples. Addition of the catalysts to the samples lowered the temperature at which maximum H2 was given off. The shift to lower temperatures was observed with increased catalyst loadings for both K2CO3 and KCl loaded samples. / Thesis (MSc (Chemistry))--North-West University, Potchefstroom Campus, 201

Thermogravimetry, coupled with a mass spectrometer (TG-MS) was used to investigate the catalytic effect potassium carbonate (K2CO3) and potassium chloride (KCl), on the char conversion and the product gas composition of chars derived from a South African inertinite-rich bituminous coal. Sequential leaching of the coal with HCl-HF-HCl was performed to reduce the mineral matter present in the coal. This was done in order to reduce possible undesirable interactions between the minerals and inorganic compounds in the coal during heat treatments. The leaching process substantially reduced the ash content from 21.5% to less than 3%. K2CO3 and KCl [0.5, 1, 3, 5 K-wt %] were loaded to the demineralized coal, raw coal and demineralized coal with added mineral mixture prior to charring. The mineral mixture was made up of kaolinite, quartz, pyrite, siderite, calcite, anastase and hydromagnesite. The ‘doped’ coal samples were then subjected to heat treatments in a CO2 atmosphere up to 1200 °C. The results obtained showed that both K2CO3 and KCl exhibit a catalytic effect on the char conversion during heat treatments in CO2 atmosphere and the char conversion was increased with increasing loadings up to 5 K-wt% of K2CO3 and KCl. The temperature ranges at which conversion occurred were found to be lower for K2CO3 than for KCl. Subsequently, char conversion occurred over a relatively narrower temperature range for K2CO3 than observed for KCl. The catalytic behaviour of K2CO3 and KCl was confirmed by the results obtained. The results also indicated that the catalytic influence of K2CO3 is greater than that of KCl and that KCl is more susceptible to deactivation by minerals and inorganic compounds present in the coal than K2CO3. Different analytical techniques (XRF and XRD) were used to determine the extent of interaction of the catalysts used with the char material in the 5 K-wt% ‘doped’ coal samples. From the XRF results, it was observed that the K2O content was reduced after heat treatments in CO2, however, no potassium crystalline phases were observed in the XRD results after heat treatments in CO2. The reduced K2O content may be attributed to the potassium been taken up in other mineral matter during char reaction with CO2, forming new amorphous inorganic complex compounds. Thus the potassium retained in the sample after heat treatment, indicated by the XRF results, may be in an amorphous phase. Mass spectrometry (MS) indicated that temperatures at which the maximum rate of evolution of gaseous species occurred were relatively lower for K2CO3 loaded char samples iv than observed for KCl loaded samples. In addition, no mass-to-charge ratio (m/z) peak at 39 atomic mass unit (amu) from the MS results was observed, indicating that no potassium was detected in the gaseous phases for all the char samples. The undetected potassium in the gaseous phase may be due to the detection limit of the MS equipment. The MS results also indicated that addition of the catalyst facilitates the evolution of H2 from the coal char samples. Addition of the catalysts to the samples lowered the temperature at which maximum H2 was given off. The shift to lower temperatures was observed with increased catalyst loadings for both K2CO3 and KCl loaded samples. / Thesis (MSc (Chemistry))--North-West University, Potchefstroom Campus, 201

Th. Ph.D.--Literature--Minneapolis (Minn.)--University of Minnesota, 1988.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains v, 126 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 59-69).

Zugl.: München, Univ., Diss., 2007.

De nombreuses études se sont déjà intéressées aux questions techniques et tactiques liées au char dans l’Orient ancien, y compris en égyptologie. Le véhicule fut à l’origine de profonds changements sociaux et culturels, et ce dans toutes les civilisations qui l’adoptèrent. L’Egypte en particulier en fit un emblème incontournable du pouvoir royal au Nouvel Empire et participa pleinement à une « culture du char » commune à tout l’Orient de l’Âge du Bronze Récent. L’objectif de cette thèse, au-delà de l’importance du char dans l’histoire militaire ou l’histoire des techniques, est d’étudier la place qu’occupe le véhicule dans la pensée égyptienne. Le volume principal de cette thèse se découpe en cinq parties. La première partie, comprenant trois chapitres, revient d’une part sur les travaux antérieurs menés sur le char et les chevaux dans l’Egypte ancienne, puis présente succinctement les sources à disposition sur le sujet. Suivent deux chapitres revenant respectivement sur la question du char en Orient et sur celle du char en Egypte. La deuxième partie est consacrée à la réception linguistique du véhicule. La troisième partie s’intéresse à la place du char dans l’idéologie royale et des élites. Les deux premiers chapitres sont dédiés au roi en char et au char du roi. Une attention particulière est accordée ensuite à la problématique du char à l’époque amarnienne. Le quatrième chapitre se concentre quant à lui sur le char en tant que véhicule de l’élite. Il est suivi d’une étude portant sur les représentations humoristiques impliquant le char. La quatrième partie concerne la réception religieuse du véhicule. Un premier chapitre s’intéresse à la place du char dans le monde funéraire, puis est évoqué le lien entre certaines divinités, le char et les chevaux. Le troisième chapitre s’intéresse particulièrement l’iconographie d’Horus-Ched en char, puis un dernier chapitre interroge la notion de « char solaire » en Egypte. La cinquième et dernière partie est une étude sur la réception littéraire du char, s’intéressant particulièrement à l’Hymne au roi en char, un poème qui place le véhicule au centre de sa composition, traduit et commenté en compagnie d’autres textes littéraires. / There are already many studies about technical and tactical questions linked to the chariot in Ancient Near East, even in Egyptology. This vehicle had been behind deep cultural and social changes in every civilisation which used it. In Egypt particularly it was an emblem of royal power in New Empire, and in a common « chariot’s culture » during the Late Bronze Age in Ancient Near East. Beyond the importance of the chariot in military or technical history, this thesis’ purpose is to study the place of this vehicle in Egyptian’s mind. The thesis is divided in five parts. The first part, divided in three chapters, explains both previous researches about the chariot and horses in Ancient Egypt, then presents briefly the available sources about this subject. The two following chapters respectively focus on the chariot in Near East and in Egypt. The second part focuses on the vehicle’s linguistic reception. The third part is interested in the chariot’s place in royal and elites’ ideology. The two first chapters are both dedicated to the king in his chariot and the king’s vehicle. A special attention is given to question of the chariot during Armanian Period. The forth chapter focuses about the chariot as the elite’s vehicle. It is followed by a study about satirical representations including the chariot. The forth part is related to the vehicle’s religious reception. A first chapter is about the place of the chariot in funerary practices, then the link between some gods, chariots and horses is studied. The third chapter details the particular case of Horus-Shed’s iconography on his chariot. The last chapter questions the notion of « solar chariot » in Ancient Egypt. The last and fifth part is a study about the chariot’s literary reception, studying especially a poem which places the vehicle in the center of its composition called Hymn to the King on his Chariot, translated and commentated on, as well as other literary texts.

No description available.

As advances in solid rocket technology push rocket motors to more extreme operating speeds and temperatures, it becomes increasingly important to have well-designed material systems capable of surviving these harsh conditions. One common component in these systems is the use of a fiber- and particle-reinforced EPDM insulation layer between the motor casing and the solid fuel to shield the casing from the temperatures of the burning fuel and from the high velocity of gas particles traveling within the motor. This work studies several insulation materials to determine which exhibits the highest shear strength after being charred. Double-notch shear test specimens of three materials, ARI-2718, ARI-2719, and ARI-2750, were charred and tested to measure the failure strength of each charred material. The ARI-2750 showed the highest shear strength when loaded along the material orientation, but the ARI-2719 was strongest when transversely loaded. The strength measurements for ARI-2750 were highly sensitive to loading direction, unlike ARI-2718 and ARI-2719. Extensive scanning electron microscopy to identify correlations between shear strength and microstructure revealed that the amount of fiber orientation and amount of residual matrix material may have significant impacts on charred shear strength in these materials. / Master of Science