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published_or_final_version / abstract / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

Storage of granular solids in silos has been the practice for many years. Engineers have been faced with the problem of making the silos empty more efficiently and minimising the forces acting on the walls of the silo during material discharge. To this end the anti-dynamic tube was invented. The tube has a smaller diameter than the silo and consists of several portholes along its height and around its circumference. When the discharge gate of the silo is opened the granular material enters the tube through the portholes, flows down the inside of the tube and exits the silo through the discharge gate. Most tubes have been installed such that there was sufficient space between the base of the tube and silo bottom for the granular material to flow simultaneously through the discharge gate. The flowing material causes a down drag on the tube from the friction of the granular material on the walls of the tube. Previous research has underestimated the magnitude of these frictional forces resulting in catastrophic buckling failure of the tubes, blocking the discharge gate of the silo. A blockage of the discharge gate requires top emptying of the silo resulting in financial losses and down time of equipment. A steel model silo with an anti-dynamic tube was set up in the laboratory to measure the friction on the tube during material flow. From the results of these experiments, an equation has been derived to estimate the magnitude of the down-drag force. Furthermore, an empirical expression was developed for the effects of the speed of the flowing material on the magnitude of the down-drag force. To keep construction costs down, it is necessary to optimise the wall thickness of the tube. There is currently no theory for the buckling capacity of a thin walled cylindrical shell with multiple perforations around its height and circumference. Therefore additional experiments were undertaken on a cylindrical shell with multiple perforations subjected to a combination of an axial as well as an external lateral pressure. Following on from the experiments, finite element analyses were undertaken to compare with the experimental results. For each finite element analysis an out-of-roundness was introduced as an initial wall imperfection. From these analyses and the cylinder experiments, a method of producing interaction curves for tubes with varying ratios of open area has been developed.

Thesis (Ph.D.)--University of Western Australia, 2003.

No Brasil a geração de energia elétrica é predominantemente baseada no uso de fontes renováveis e obtida por meio de centrais hidroelétricas. Ainda assim é necessária a diversificação das fontes de suprimento de energia para a geração de eletricidade quando o recurso hídrico for escasso. Uma alternativa é utilizar gás natural como combustível para as usinas termoelétricas, como vem sendo introduzido na matriz energética de outros países, permitindo a diversificação das fontes energéticas dos mesmos. A indústria do gás natural, assim como outras atividades industriais, não está isenta de acidentes que podem provocar graves consequências à integridade das pessoas e das propriedades. Por este motivo, é necessário desenvolver estudos para determinar quais são as possíveis causas que poderiam ocasionar estes acidentes, e quais são os possíveis cenários associados a estas falhas especificamente na área do transporte de GNL (Gás Natural Liquefeito). É neste contexto que este trabalho de pesquisa tem por objetivo desenvolver um método, baseado nas técnicas de análise de risco, que permita identificar os principais cenários de falha associados à ocorrência de um vazamento de GNL ou de boil-off durante as operações de carga e/ou descarga de navios. Neste cenário, considera-se a presença das barreiras de proteção destinadas a conter esse evento iniciador de perigo no sistema de carga e descarga do navio transportador de GNL, quando o navio está atracado no porto. Adicionalmente à apresentação do método, e como resultado do trabalho, são identificados quais os componentes que pertencem ao circuito de carga e descarga de GNL, e que tenham uma categoria de risco denominada como Crítica (C), Moderada (M) ou Não Crítica (NC). Finalmente, a implantação do método propõe medidas que ajudam a diminuir o nível de risco associado aos componentes denominados críticos, a fim de garantir uma operação segura e livre de acidentes que ponham em risco a integridade dos operadores, dos equipamentos e do ambiente. / Although the electricity generation in Brazil is predominantly based on renewable sources and obtained by means of hydroelectric power plants, it is still necessary to diversify sources of energy supply to generate electricity when the water resource is scarce. An alternative is the use natural gas as fuel for power plants, once it has been introduced in the energy matrix of other countries, allowing the diversification of their energy sources. The natural gas industry, as well as other industrial activities, is not free from accidents, which can cause serious consequences to the integrity of people and properties. For this reason, it is necessary to develop studies to determine what are the possible causes that could lead to serious accidents and what are the possible scenarios of these faults specifically in the area of LNG (Liquefied Natural Gas) transportation. In this context, this research aims to develop a method based on risk analysis concepts which identifies the main failure scenarios given the occurrence of LNG or boil-off leakage during ship loading and unloading operations, considering the presence of containment barriers designed to hold this hazard initiator event in loading and unloading system of the LNG carrier when the ship is in harbor. In addition to the method presentation this research identifies which are the components of LNG loading and unloading circuit, which have a risk category classified as Critical (C), Moderate (M) and NonCritical (NC). Finally, the method implementation allows the proposal of safety and maintenance measures to help reducing the risk level in order to ensure safe operation, free of accidents that endanger the integrity of the operators, the equipment and the environment.

No Brasil a geração de energia elétrica é predominantemente baseada no uso de fontes renováveis e obtida por meio de centrais hidroelétricas. Ainda assim é necessária a diversificação das fontes de suprimento de energia para a geração de eletricidade quando o recurso hídrico for escasso. Uma alternativa é utilizar gás natural como combustível para as usinas termoelétricas, como vem sendo introduzido na matriz energética de outros países, permitindo a diversificação das fontes energéticas dos mesmos. A indústria do gás natural, assim como outras atividades industriais, não está isenta de acidentes que podem provocar graves consequências à integridade das pessoas e das propriedades. Por este motivo, é necessário desenvolver estudos para determinar quais são as possíveis causas que poderiam ocasionar estes acidentes, e quais são os possíveis cenários associados a estas falhas especificamente na área do transporte de GNL (Gás Natural Liquefeito). É neste contexto que este trabalho de pesquisa tem por objetivo desenvolver um método, baseado nas técnicas de análise de risco, que permita identificar os principais cenários de falha associados à ocorrência de um vazamento de GNL ou de boil-off durante as operações de carga e/ou descarga de navios. Neste cenário, considera-se a presença das barreiras de proteção destinadas a conter esse evento iniciador de perigo no sistema de carga e descarga do navio transportador de GNL, quando o navio está atracado no porto. Adicionalmente à apresentação do método, e como resultado do trabalho, são identificados quais os componentes que pertencem ao circuito de carga e descarga de GNL, e que tenham uma categoria de risco denominada como Crítica (C), Moderada (M) ou Não Crítica (NC). Finalmente, a implantação do método propõe medidas que ajudam a diminuir o nível de risco associado aos componentes denominados críticos, a fim de garantir uma operação segura e livre de acidentes que ponham em risco a integridade dos operadores, dos equipamentos e do ambiente. / Although the electricity generation in Brazil is predominantly based on renewable sources and obtained by means of hydroelectric power plants, it is still necessary to diversify sources of energy supply to generate electricity when the water resource is scarce. An alternative is the use natural gas as fuel for power plants, once it has been introduced in the energy matrix of other countries, allowing the diversification of their energy sources. The natural gas industry, as well as other industrial activities, is not free from accidents, which can cause serious consequences to the integrity of people and properties. For this reason, it is necessary to develop studies to determine what are the possible causes that could lead to serious accidents and what are the possible scenarios of these faults specifically in the area of LNG (Liquefied Natural Gas) transportation. In this context, this research aims to develop a method based on risk analysis concepts which identifies the main failure scenarios given the occurrence of LNG or boil-off leakage during ship loading and unloading operations, considering the presence of containment barriers designed to hold this hazard initiator event in loading and unloading system of the LNG carrier when the ship is in harbor. In addition to the method presentation this research identifies which are the components of LNG loading and unloading circuit, which have a risk category classified as Critical (C), Moderate (M) and NonCritical (NC). Finally, the method implementation allows the proposal of safety and maintenance measures to help reducing the risk level in order to ensure safe operation, free of accidents that endanger the integrity of the operators, the equipment and the environment.

Die Nanoindentation ist ein inzwischen etabliertes Verfahren zur Bestimmung der Materialkennwerte Härte und Elastizitätsmodul in kleinen Größendimensionen. Eine zusätzliche Bestimmung der Fließspannung aus solchen Nanoindentationsexperimenten würde deren Einsatzmöglichkeiten deutlich erweitern und zum Beispiel für die Bauteilauslegung kleiner Strukturen, Schichtcharakterisierung und die Beschaffung von Simulationseingangsdaten einen großen Fortschritt bedeuten. Diese Gründe machen das Thema zu einem aktuellen Forschungsgegenstand. In der vorliegenden Arbeit steht deswegen die Bewertung von Fließspannungsbestimmungsverfahren für Massivmaterialien in der Nanoindentation mittels einer Kombination aus Finite-Elemente-Simulationen und umfangreichen Experimentaldaten im Zentrum. Im Speziellen wird dabei das Konzept des effektiv geformten Indenters mit dem erweiterten Hertzschen Ansatz und dessen Anwendung zur Fließspannungsbestimmung aus Eindringversuchen mit selbstähnlichen Berkovichpyramiden betrachtet. Zur Bearbeitung dieser Aufgabenstellung wurden unter anderem drei Referenzverfahren zur Fließspannungsbestimmung (die Expanding cavity-Modelle, das Loading partial unloading-Verfahren und Minidruckversuche) ausführlich charakterisiert. Damit konnten dann im Weiteren belastbare Referenzfließspannungen für die umfangreiche Experimentaldatenbasis zur Verfügung gestellt werden. Außerdem wurden die untersuchten Materialien auf den Einfluss der Größenabhängigkeit der Fließspannungen, den Indentation size effect, hin untersucht. Dabei wurden die vorliegenden physikalischen Vorgänge in den Proben beschrieben, dahingehende Unterschiede bei den betrachteten Referenzverfahren charakterisiert und den Fließspannungswerten die Fließzonendimensionen zugeordnet. Mit den damit zur Verfügung stehenden Informationen konnte das Konzept des effektiv geformten Indenters in seiner Anwendung zur Fließspannungsbestimmung grundlegend bewertet werden. Alle Untersuchungen wurden dabei stets parallel mit Hilfe von Simulations- und Experimentaldaten durchgeführt, um tiefere Einblicke in die zu Grunde liegende Mechanik der Fließprozesse zu gewinnen.

Trade liberalization and resultantly globalization has led to the relative free flow of goods, services, capital and people. The transport system in South Africa must be highly reliable and rapid to contribute to economic development. The focus of this research study is on the Port/Rail Interface in the Port of Durban which critically assesses the transfer of goods particularly from rail transport to and from vessels within the port precinct. Some of the major constraints identified in the study related to poor infrastructure, operations and levels of services; lack of maintenance, availability of rolling stock, locomotives and cargo stacking space. Transnet's role is pivotal in providing efficient port and rail operations and is currently upgrading infrastructure, operations and capacity of the port and rail services. One of the main objectives of the study is to present recommendations to Transnet management that arise out of the shortcomings identified during the course of the research study. / Transport Economics / M. Comm.

Trade liberalization and resultantly globalization has led to the relative free flow of goods, services, capital and people. The transport system in South Africa must be highly reliable and rapid to contribute to economic development. The focus of this research study is on the Port/Rail Interface in the Port of Durban which critically assesses the transfer of goods particularly from rail transport to and from vessels within the port precinct. Some of the major constraints identified in the study related to poor infrastructure, operations and levels of services; lack of maintenance, availability of rolling stock, locomotives and cargo stacking space. Transnet's role is pivotal in providing efficient port and rail operations and is currently upgrading infrastructure, operations and capacity of the port and rail services. One of the main objectives of the study is to present recommendations to Transnet management that arise out of the shortcomings identified during the course of the research study. / Transport Economics / M. Comm.

Die Nanoindentation ist ein inzwischen etabliertes Verfahren zur Bestimmung der Materialkennwerte Härte und Elastizitätsmodul in kleinen Größendimensionen. Eine zusätzliche Bestimmung der Fließspannung aus solchen Nanoindentationsexperimenten würde deren Einsatzmöglichkeiten deutlich erweitern und zum Beispiel für die Bauteilauslegung kleiner Strukturen, Schichtcharakterisierung und die Beschaffung von Simulationseingangsdaten einen großen Fortschritt bedeuten. Diese Gründe machen das Thema zu einem aktuellen Forschungsgegenstand. In der vorliegenden Arbeit steht deswegen die Bewertung von Fließspannungsbestimmungsverfahren für Massivmaterialien in der Nanoindentation mittels einer Kombination aus Finite-Elemente-Simulationen und umfangreichen Experimentaldaten im Zentrum. Im Speziellen wird dabei das Konzept des effektiv geformten Indenters mit dem erweiterten Hertzschen Ansatz und dessen Anwendung zur Fließspannungsbestimmung aus Eindringversuchen mit selbstähnlichen Berkovichpyramiden betrachtet. Zur Bearbeitung dieser Aufgabenstellung wurden unter anderem drei Referenzverfahren zur Fließspannungsbestimmung (die Expanding cavity-Modelle, das Loading partial unloading-Verfahren und Minidruckversuche) ausführlich charakterisiert. Damit konnten dann im Weiteren belastbare Referenzfließspannungen für die umfangreiche Experimentaldatenbasis zur Verfügung gestellt werden. Außerdem wurden die untersuchten Materialien auf den Einfluss der Größenabhängigkeit der Fließspannungen, den Indentation size effect, hin untersucht. Dabei wurden die vorliegenden physikalischen Vorgänge in den Proben beschrieben, dahingehende Unterschiede bei den betrachteten Referenzverfahren charakterisiert und den Fließspannungswerten die Fließzonendimensionen zugeordnet. Mit den damit zur Verfügung stehenden Informationen konnte das Konzept des effektiv geformten Indenters in seiner Anwendung zur Fließspannungsbestimmung grundlegend bewertet werden. Alle Untersuchungen wurden dabei stets parallel mit Hilfe von Simulations- und Experimentaldaten durchgeführt, um tiefere Einblicke in die zu Grunde liegende Mechanik der Fließprozesse zu gewinnen.