In this thesis, the benefits of boundary layer control (BLC) in improving aerodynamic performance and engine stability were examined in a compact, serpentine inlet exhibiting flow separation. A 1/14-scale turbofan engine simulator provided the flow through the inlet. The inlet's mass flow was measured to be 759 scfm (0.939 lbm/s) with an average throat Mach number of 0.23 when the simulator speed was 40 krpm. Boundary layer suction, blowing, and their combination were used to minimize the inlet's flow separation. The effectiveness of the suction alone and the blowing alone was shown to be approximately equivalent, and the effectiveness of the combined use of both was seen to be better than either one by itself. With blowing and suction flowrates around 1% of the simulator's core flow, the inlet's distortion was lowered by 40.5% (from 1.55% to 0.922%) while the pressure recovery was raised by 9.7% (from 87.2% to 95.6%). With its reduction in distortion, BLC was shown to allow the simulator to steadily operate in a range that would have otherwise been unstable. Minimizing the flow separation within the inlet was shown to directly relate to measurements from flush-mounted microphones along the inlet wall: as the exit distortion decreased the microphone spectrum also decreased in magnitude. The strong relationship between the aerodynamic profiles and the microphone signal suggests that microphones may be used in an active flow control scheme, where the BLC effort can be tailored for different engine operating conditions. Unfortunately, the sensing scheme used in this experiment showed the microphone signal to continue to decrease even when the separation is overly compensated; therefore refinements must be made before it would be practical in a real application. / Master of Science

Depuis ces 3 derniers milliards d'années l'eau liquide est extrêmement peu présente sur Mars. Cependant les multiples données disponibles sur la planète montrent des preuves d'une présence importante d'eau liquide depuis l'accrétion de la planète jusqu'à environ 3,7 milliards d'années. L'hypothèse dominante aujourd'hui est que Mars possédait une atmosphère plus dense (possiblement riche en CO2) au début de son histoire. Une grande partie de cette atmosphère et de l'eau auraient été perdu dans l'espace. Une autre hypothèse pour la diminution de la quantité d'eau liquide disponible et pour la diminution de l'atmosphère est le stockage d'eau et de CO2 dans la croûte. La croûte martienne est étudiée via les données de spectro-imagerie CRISM pour caractériser l'altération hydrothermale primitive de la planète. Des détections de serpentine et de carbonates confirment que le stockage d'une partie de l'eau et de l'atmosphère martienne a eu lieu. Des contraintes supplémentaires sont apportées par de la modélisation géochimique de la serpentinisation et de la carbonatation de la croûte martienne via les programme EQ3/6. L'importance de la serpentinisation et de la carbonatation de la croûte martienne est ainsi réévaluée. Les résultats permettent d'ouvrir la réflexion sur le rôle de la serpentinisation et de la carbonatation sur l'évolution de la quantité d'eau liquide disponible et sur l'évolution de l'atmosphère. En outre, les conditions thermodynamiques permettent d'apporter des contraintes sur le potentiel exobiologique de la croûte martienne / Over the last 3 billion years liquid water has an extremely limited presence on Mars. However, the multiple data available on the planet show evidences of a significant presence of liquid water from the accretion of the planet until about 3.7 billion years. The prevailing hypothesis today is that Mars had a denser atmosphere (possibly rich in CO2) early in its history. Much of this atmosphere and water were lost in space. Another possibility for reducing the amount of liquid water available and the reduction of the atmosphere is the water storage of water and CO2 in the crust. The Martian crust is studied via CRISM spectro-imaging data to characterize the early hydrothermal alteration of the planet. Serpentine and carbonates of detections confirm that the storage of a portion of the water and the atmosphere of Mars occurred. Additional constraints are provided by the geochemical modeling of serpentinization and carbonation of the Martian crust through EQ3/6 programs. The importance of serpentinization and carbonation of the Martian crust is thus reassessed. The results allow to open the debate on the role of serpentinization and carbonation on the evolution of the liquid water available and the evolution of the atmosphere. In addition, the thermodynamic conditions help provide constraints on the exobiology potential of the Martian crust

Phytoextraction du nickel dans les sols ultramafiques d’Albanie La phytoextraction minière est un procédé de récupération des métaux des sols minéralisés naturels ou pollués à l’aide de plantes hyperaccumulatrices. Elle est une alternative à l’agriculture vivrière des zones ultramafiques. L’objectif de la thèse est le développement d’une technologie de phytoextraction extensive du Ni avec Alyssum murale sur les Vertisols ultramafiques. Pour cela, il s’agissait : i) d’identifier les plantes hyperaccumulatrices les plus efficaces dans le prélèvement du Ni et comprendre les relations entre le prélèvement du métal et sa biodisponibilité, ii) de déterminer les types de sols adaptés à la phytoextraction du Ni et iii) de définir et optimiser un itinéraire agronomique adapté pour l’espèce retenue et pour les conditions édaphiques. Dans ce but, des prospections géobotaniques ont été conduites en Albanie et en Grèce. Puis une étude in situ des facteurs qui influencent la biodisponibilité du Ni et le comportement des plantes sur une toposéquence ultramafique a été mise en place. Enfin un essai agronomique de quatre années sur un site ultramafique d’Albanie (Pojske) a permis de tester la fertilisation, le contrôle des adventices par herbicide et la date de récolte pour optimiser le rendement d’extraction du Ni. Les résultats montrent que parmi l’ensemble des espèces présentes naturellement sur les serpentines des Balkans, A. markgrafii et A. murale ont le plus fort taux d’accumulation du Ni. Les Vertisols ultramafiques présentent une disponibilité élevée du Ni favorable à la phytoextraction minière. La biomasse d’A murale est augmentée de 0,2 t ha-1 à 6,0 t ha-1 à partir des traitements agronomiques et le rendement de phytoextraction de Ni par A. murale est de 23 à 69 kg ha-1. Alyssum murale peut être envisagée comme une culture pérenne et la fertilisation permet d’augmenter la compétitivité de la plante sans affecter les concentrations de Ni dans les parties récoltées / Phytomining is a process for recovering metals with hyperaccumulating plants from natural or polluted soils. It is an alternative to conventional farming in ultramafic areas. The aim of the thesis is the development of an extensive phytoextraction technology with Alyssum murale on ultramafic Vertisols. Therefore, work was conducted to i) identify the most effective Ni hyperaccumulators, and understand the relationship between metal uptake and bioavailability, ii) identify soil types suitable for phytoextraction, and iii) define and optimize agronomic practices adapted to the plant species and the edaphic conditions. Hence, geobotanical surveys were conducted in Albania and Greece. Then an in situ study was run on an ultramafic toposequence to assess the factors that influence Ni bioavailability and behavior of plants. Finally a four-year field trial was carried out on an ultramafic site in Albania (Pojske) where fertilization, weed control by herbicide, and harvest date were tested to optimize the efficiency of Ni extraction. The results showed that A. markgrafii and A. murale exhibit the highest rate of Ni accumulation among all species of Balkan serpentines. The ultramafic Vertisols have a high Ni availability phytoextraction and are favourable for phytomining. A. murale biomass increased from 0.2 t ha-1 to 6.0 t ha-1 due to optimization of agronomic treatments, and performance of phytoextraction from 23 to 69 kg ha-1. Alyssum murale can be seen as a perennial crop, and fertilization increases the competitiveness of the plant without affecting the Ni concentrations in the harvested parts

Esta dissertação tem como foco central o estudo de edifícios pavilhões e sua relação com a produção tridimensional - entendida como instalação e escultura. Para tanto, articula-se o conceito de \"campo ampliado\", elaborado por Rosalind Krauss em texto de 1979 para abarcar as transformações da escultura a partir dos anos 60, com seu recente deslocamento, para o âmbito da arquitetura por parte de alguns autores, nomeadamente Antony Vidler. A pesquisa não se resume apenas a uma investigação da contribuição do espaço arquitetônico para a escultura ou da escultura para a arquitetura, mas foca especialmente a linha que as separa, visto que a tendência de convergência das duas disciplinas faz com que seu elo de reciprocidade se dissolva numa produção intersticial, realizada por artistas, arquitetos ou mesmo por ambos em colaboração. O pavilhão sempre foi entendido como um campo experimental para os arquitetos, especialmente ao longo do século XX quando ajudou a consolidar as premissas da arquitetura moderna. Hoje, apresenta grande visibilidade através de diversos programas que oferecem condições únicas de encomenda e concepção pressupondo uma arquitetura singular, que configura uma produção desvinculada do binômio forma-função e cujo assunto autorreferente é a própria arquitetura. Do ponto de vista das artes o pavilhão representa uma expansão da instalação para um todo espacial que passa a envolver também o edifício e, quando tomado como meta arquitetura, opera também como plataforma de afrontamento crítico. O embate teórico acerca dos desdobramentos do \"campo ampliado\", bem como a investigação sobre aspectos essenciais do termo \"pavilhão\", de natureza maleável, são confrontados com uma análise crítica de casos selecionados em três instituições com características bem distintas- Bienal de Veneza, Instituto de Arte Contemporânea do Inhotim e Serpentine Gallery -, e possibilitam alinhavar conclusões sobre esta produção contemporânea no limiar dessas duas disciplinas. / This dissertation is focused on the study of pavilions and their relationship with the three-dimensional production - understood as installation and sculpture. Therefore, the concept of \"expanded field\", elaborated by Rosalind Krauss in the 1979 essay to encompass the transformation of sculpture from the 60\'s, is articulated with the recent shift of this same concept into the realm of architecture by some authors, namely Antony Vidler. The research is not just an investigation on the contribution of the architectural space for sculpture or, on the other hand, from sculpture to architecture, but focuses especially the line that separates them, understood as a disposition of convergence by the two disciplines which dissolves the reciprocal bonds in a interstitial production, performed by artists, architects or even both together. The pavilion has always been understood as an experimental field for architects, especially during the twentieth century when it helped consolidate the assumptions of modern architecture. Today it has gained great visibility through several programs that offer specific conditions by commissioning and assuming a unique architecture design that sets up a production untied from the binomial form-function, resulting in a self referent building whose subject is the architecture itself. From the point of view of the arts, it represents an expansion of the installation configuring a spatial whole that also implicate the building and, when taken as meta architecture, also operates as a platform for critical confrontation. The opposition on theory about the ramifications of the expanded field, as well as a research on the essential characteristics to a malleable term, are faced with a critical analysis of selected cases in three institutions gathering rather distinct characteristics - the Venice Biennale, the Institute of Contemporary Art Inhotim and the Serpentine Gallery -, and allow conclusions on this contemporary production in a disciplinary threshold.

Esta dissertação tem como foco central o estudo de edifícios pavilhões e sua relação com a produção tridimensional - entendida como instalação e escultura. Para tanto, articula-se o conceito de \"campo ampliado\", elaborado por Rosalind Krauss em texto de 1979 para abarcar as transformações da escultura a partir dos anos 60, com seu recente deslocamento, para o âmbito da arquitetura por parte de alguns autores, nomeadamente Antony Vidler. A pesquisa não se resume apenas a uma investigação da contribuição do espaço arquitetônico para a escultura ou da escultura para a arquitetura, mas foca especialmente a linha que as separa, visto que a tendência de convergência das duas disciplinas faz com que seu elo de reciprocidade se dissolva numa produção intersticial, realizada por artistas, arquitetos ou mesmo por ambos em colaboração. O pavilhão sempre foi entendido como um campo experimental para os arquitetos, especialmente ao longo do século XX quando ajudou a consolidar as premissas da arquitetura moderna. Hoje, apresenta grande visibilidade através de diversos programas que oferecem condições únicas de encomenda e concepção pressupondo uma arquitetura singular, que configura uma produção desvinculada do binômio forma-função e cujo assunto autorreferente é a própria arquitetura. Do ponto de vista das artes o pavilhão representa uma expansão da instalação para um todo espacial que passa a envolver também o edifício e, quando tomado como meta arquitetura, opera também como plataforma de afrontamento crítico. O embate teórico acerca dos desdobramentos do \"campo ampliado\", bem como a investigação sobre aspectos essenciais do termo \"pavilhão\", de natureza maleável, são confrontados com uma análise crítica de casos selecionados em três instituições com características bem distintas- Bienal de Veneza, Instituto de Arte Contemporânea do Inhotim e Serpentine Gallery -, e possibilitam alinhavar conclusões sobre esta produção contemporânea no limiar dessas duas disciplinas. / This dissertation is focused on the study of pavilions and their relationship with the three-dimensional production - understood as installation and sculpture. Therefore, the concept of \"expanded field\", elaborated by Rosalind Krauss in the 1979 essay to encompass the transformation of sculpture from the 60\'s, is articulated with the recent shift of this same concept into the realm of architecture by some authors, namely Antony Vidler. The research is not just an investigation on the contribution of the architectural space for sculpture or, on the other hand, from sculpture to architecture, but focuses especially the line that separates them, understood as a disposition of convergence by the two disciplines which dissolves the reciprocal bonds in a interstitial production, performed by artists, architects or even both together. The pavilion has always been understood as an experimental field for architects, especially during the twentieth century when it helped consolidate the assumptions of modern architecture. Today it has gained great visibility through several programs that offer specific conditions by commissioning and assuming a unique architecture design that sets up a production untied from the binomial form-function, resulting in a self referent building whose subject is the architecture itself. From the point of view of the arts, it represents an expansion of the installation configuring a spatial whole that also implicate the building and, when taken as meta architecture, also operates as a platform for critical confrontation. The opposition on theory about the ramifications of the expanded field, as well as a research on the essential characteristics to a malleable term, are faced with a critical analysis of selected cases in three institutions gathering rather distinct characteristics - the Venice Biennale, the Institute of Contemporary Art Inhotim and the Serpentine Gallery -, and allow conclusions on this contemporary production in a disciplinary threshold.

Detailed botanical surveys and vegetation ecology studies of serpentine habitats in California are rare (Kruckeberg, 1984). This investigation of Rawhide Hill was intended to provide this type of information.

Multiphase flows occurring in pipelines with a serpentine configuration is an important phenomenon, which can be encountered in heat exchangers used in a variety of industrial processes. More specifically, in many industrial units such as a large cracking furnace in a refinery, the tubes are arranged in a serpentine manner and are relatively short. As flow negotiates round the 180o bend at the ends of the tubes, the generated centrifugal force could cause flow maldistribution creating local dry spots, where no steady liquid film is formed on the adjacent straight sections of the pipe. As a result, events including coking, cracking and overheating of heat transfer surfaces may occur and lead to frequent shutdown of the facilities. Consequently, this could increase operating costs and reduce production revenue. Thus, it is desirable to know the effect that the bends exert on the flow in the straight part of the pipe. Apart from this, knowledge of the bend effects on the flows in the pipeline could also be important for the design of other pipelines for gas/liquid transport, e.g. offshore gas and oil pipelines. Quite a large number of studies have been found in the literature. The majority of them were for two-phase flow with small diameter pipes (i.d. ≤ 50 mm). However, studies with large diameter pipes (i.d. ≥ 100 mm), have increasingly been considered in recent years as problems related to large diameter vertical pipes are being encountered more and more often in industrial situations. This thesis studies the effect of 180o bends on the characteristics and development of gas-liquid two-phase flows in large diameter downward and upward pipes. The study particularly focuses on the influence of serpentine configuration on flow structure, cross-sectional void distribution and circumferential liquid film profiles and their development along the downward and upward sections. It was found that both the top and bottom bends have considerable impacts on flow behaviour, although to varying degrees. These impacts were highly dependent on the air and water flow rates. For sufficient flow rates, the bends were observed to create flow maldistribution in the adjacent straight section, due to the effects of centrifugal force. The air moved towards the inner zone of the bend and the water towards the outer zone, while a lesser quantity of water was identified on the other surfaces of the pipe. Investigation of the film thickness development in the downward and upward sections showed that, the liquid film behaviour close to the bends was significantly different from those located further away. This can be attributed to the centrifugal force of the bends. Examination of the power spectral density (PSD) along the downward and upward sections showed that, the shape of PSD located in the adjacent section to the bends, was substantially different from those located further away. Furthermore, several flow regime maps were generated which showed that, in addition to bubbly, intermittent and annular flows, unstable flows existed along the upward section, particularly for low gas and water flow rates. In this study it was found that, the lower bend was periodically blocked by the liquid and then blown through by the accumulated air. The data obtained from this study were compared with different theoretical correlations found in the existing literature. Some discrepancy between the results of the current study and those of previous published materials was noted. Updated correlations were presented which provided well results when they applied for the data obtained from the current study and previous studies.

A Thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirement for the degree of Doctor of Philosophy. Johannesburg March 2016 / This study aims to provide a comprehensive description of the Flora, biogeography and diversity of the serpentine outcrops of Barberton Greenstone Belt in Mpumalanga, South Africa in order to set conservation priorities for these areas. About 30 large and many smaller serpentine outcrops form part of the Barberton Greenstone Belt and consist of various combinations of serpentinized minerals. Seven outcrops were selected to be studied in detail. A floristic analysis recorded 744 species and subspecies, 319 genera and 94 families. The flora includes 33 taxa endemic to serpentine soils and six taxa, which are hyperaccumulators of nickel. The endemic taxa make up 41 % of the endemics of the Barberton Centre of Endemism. The serpentine flora was found to be different to the surrounding non-serpentine vegetation in terms of numbers of species per family, the ratios of dicotyledons to monocotyledons and familial composition. The Asteraceae and the Anacardiaceae support a higher number of endemics than expected, which suggests genetic pre-adaptation within these families and specifically within the genera Berkheya, Helichrysum and Ozoroa. Most of the endemic taxa exhibit long-range dispersal suggesting gene flow between populations on different outcrops. The endemics represent a mix of neo-endemics and paleoendemics. Non-parametric species richness estimators used to predict the species richness of each site, indicated that five serpentine outcrops have higher species richness than the surrounding non-serpentine areas. Indices of diversity calculated showed similar patterns to those of the species richness estimates. The Barberton Greenstone Belt serpentine outcrops show relatively high plant diversity when compared to some other serpentine outcrops around the world. Beta diversity calculated for each site was not correlated with altitude and weakly correlated with the size of outcrops. Species turnover between outcrops is high and is positively correlated with the geographical distance between outcrops. Diversity at higher taxonomic levels were calculated, and results suggest that genera have some potential for facilitating the ranking of outcrops in terms of biological richness to select sites for conservation planning. Less than 30% of serpentine outcrops are adequately conserved. Species and genus richness and endemism were used to select five outcrops that have high conservation priority / MT2016

This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).

This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).