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Performance improvement of the Rover 1S/60 Gas Turbine CompressorLuiten, Ruben Vincent 03 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The use of gas turbines in central receiver solar power plant cycles has become
an increasingly popular research topic. This has led to the need to
investigate and analyse the effect of the solar receiver on the gas turbine
cycle. The aim of this thesis is to construct an experimental gas turbine
setup to accommodate further research on utilizing solar energy to power
gas turbines. The gas turbine under consideration is the Rover Gas Turbines
1S/60. The focus of this investigation is the centrifugal compressor of the
gas turbine. An increase in static pressure is required for the gas turbine
to cope with anticipated pressure drops in the central receiver that will be
part of the gas turbine cycle. The standard compressor design is analysed
by means of 3-D (CFD) analysis using CFX® and experimental data. The
new centrifugal compressor is designed by means of 1-D and 3-D (CFD)
analysis using CompAero and CFX®. The aim is to design a compressor
that maximizes the total-to-static pressure ratio. The size of the compressor
is highly constrained by the geometry parameters of the gas turbine.
Since the turbine rotor will remain unchanged, the power input, mass flow
rate and rotational speed must stay the same. The experimental setup was
build and the numerical results of the standard compressor were validated
against the experimental results. A new centrifugal compressor was designed.
The total-to-static pressure ratio was increased from 2.50 to 3.30
at an operating speed of 46 krpm. The efficiency of the compressor was
improved from 63.8% to 85.6%. The input power of the new compressor
design deviated 1.6% from the set benchmark, and 1.3% from the numerical
data of the standard compressor. / AFRIKAANSE OPSOMMING: Die gebruik van gasturbines in sonkragstasiesiklusse met ’n sentrale ontvanger
het gegroei tot ’n gewilde navorsingsonderwerp. Dit het gelei tot
die behoefte om die effek van die sonontvanger op die gasturbinesiklus te
ondersoek en te analiseer. Die doel van hierdie tesis is om ’n eksperimentele
gasturbine opstelling te bou vir verdere navorsing oor die benutting
van sonenergie om ’n gasturbine aan te dryf. Die gasturbine in oorweging
is die Rover Gas Turbines 1S/60. Die fokus van hierdie ondersoek is die
sentrifugale kompressor van die gasturbine. ’n Toename in statiese druk
word benodig vir die gasturbine om die verwagte drukverlies in die sentrale
ontvanger, wat deel uit maak van die gasturbinesiklus, te hanteer. Die
standaard kompressor ontwerp is geanaliseer deur middel van 3-D Berekenings
Vloeimeganika (BVM) analises met behulp van CFX® en eksperimentele
data. Die nuwe sentrifugale kompressor is ontwerp deur middel van
1-D en 3-D BVM analises met behulp van CompAero en CFX®. Die doel
is om ’n kompressor te ontwerp wat die totale-tot-statiese drukverhouding
maksimeer. Die grootte van die kompressor is beperk deur die geometrie
van die gasturbine omhulsel. Aangesien die turbinerotor onveranderd sal
bly, moet die insetdrywing, massa-vloeitempo en rotasiespoed dieselfde bly.
Die eksperimentele opstelling is gebou en die numeriese resultate van die
standaard kompressor is teenoor die eksperimentele resultate gevalideer.
’n Nuwe sentrifugale kompressor is ontwerp. Die totale-tot-statiese drukverhouding
is verhoog van 2.50 tot 3.30 teen ’n rotasiespoed van 46 000
omwentelings per minuut. Die doeltreffendheid van die kompressor is verbeter
van 63.8% tot 85.6%. Die insetdrywing van die nuwe kompressor ontwerp
het met 1.6% afgewyk van die vasgestelde maatstaf, en met 1.3% van
die numeriese data van die standaard kompressor.
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Excitonic Analysis of Many-Body Effects on the 1s−2p Intraband Transition in Semiconductor SystemsPARKS, Andrew Marshall 06 June 2011 (has links)
I present a detailed study of many-body effects associated with the interband 1s transition and intraband 1s-2p transition in two- and three-dimensional photo-excited semiconductors. I employ a previously developed excitonic model to treat effects of exchange and phase space filling. I extend the scope of the model to include static free-carrier screening. I also develop a factorization scheme to obtain a consistent set of excitonic dynamical equations. The exciton transition energies are renormalized by many-body interactions, and the excitonic dynamical equations provide simple expressions for the individual contributions of screening, phase space filling and exchange.
The effects of exchange and phase space filling are quantified by a set of excitonic coefficients. I first calculate these coefficients analytically by omitting screening effects. In contrast, the screened coefficients involve multi-dimensional integrals which must be evaluated numerically. I present a detailed discussion of the numerical methods used to evaluate these integrals, which include a novel algorithm for segmenting multi-dimensional integration regions.
The excitonic model correctly predicts the blue shift and bleaching of the 1s exciton resonance due to exchange and phase space filling. Free-carrier screening is found to enhance these effects by lowering the exciton binding energy. In contrast, the effects of free-carrier screening on the 1s-2p transition energy are more subtle. In the absence of free-carrier screening, exchange and phase space filling lead to a blue shift of the transition energy. However, screening decreases the 1s binding energy faster than the 2p binding energy, which in turn decreases the transition energy. Thus, screening effects oppose exchange and phase space filling, and the overall magnitude and sign of the 1s-2p transition energy shift depends on the free-carrier density. Specifically, for low-moderate excitation densities exchange and phase space filling can be dominated by screening, leading to a net red shift of the transition energy. The results for two- and three-dimensional systems are qualitatively similar, although the magnitudes of the shifts are much smaller in three dimensions. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2011-05-31 15:58:27.222
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Utilisation d'un peigne de fréquences optiques pour la spectroscopie de l'hydrogèneOlivier, Arnoult 08 November 2006 (has links) (PDF)
L'objet de cette thèse est une mesure absolue de la fréquence de la transition 1S-3S dans l'atome d'hydrogène, afin d'améliorer la connaissance de la constante de Rydberg et du déplacement de Lamb. Expérimentalement, un laser Ti :Sa continu à 820 nm est quadruplé en fréquence dans des cristaux de LBO et BBO. La transition à deux photons de 205 nm est réalisée dans une cavité optique colinéaire au jet atomique. L'effet Doppler du second ordre est compensé par l'action d'un champ magnétique statique. Un peigne de fréquences optiques sert à comparer directement la fréquence absolue du Ti :Sa à l'étalon primaire de fréquence. La détection de la fluorescence à 656 nm est assurée par une caméra CCD. L'ajustement des données expérimentales par les formes de raie calculées conduit à une valeur de l'effet Doppler du second ordre incompatible avec les prévisions approximatives de la fréquence absolue 1S-3S, suggérant l'existence d'un effet systématique tel qu'un champ électrique parasite.
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Measurement of Upsilon (1S) Production at BaBarSo, Rocky Yat Cheung 05 1900 (has links)
BABAR is a particle physics experiment at the Stanford Linear Accelerator Center (SLAC). The purpose of BABAR is to study matter-antimatter asymmetry in the bottom quark system. At SLAC, electons and positrons collide, which annihilate and decay into a variety of daughters. An Upsilon(4S) meson is one of the possible daughters. An Upsilon(4S) decays into a B meson and an anti-B meson more than 96% of the time. A B meson has an anti-bottom quark and an anti-B meson has a bottom quark. The purpose of this thesis is to measure how many Upsilon(1S) originated from Upsilon(4S) in the entire BABAR data set. This thesis compares on-peak data and off-peak data. On-peak data was taken at center of mass energy 10.58GeV. One of the possible interactions is e+e− -> Upsilon(4S) since the mass of Upsilon(4S) is 10.58GeV/c^2. On-peak data, taken at center of mass energy 10.54GeV, is not enough to have any BB pairs because 10.54GeV is less than the mass of an Upsilon(4S). This
thesis can be useful for BABAR physicist because it helps set an upper limit on how many BB pairs there are in the entire BABAR data set. In other words, it sets an upper limit on how much more than 96% does Upsilon(4S) decay to BB. Measurement of the decay of Upsilon(4S) -> Upsilon(1S) + X give evidence for non-BB decays of the Upsilon(4S). The final results of this study show that there were (110 +- 3) × 10^5 Upsilon(1S) on-peak, of which (10 +- 9) × 10^5 originated from an Upsilon(4S). Increasing the centre of mass energy from 10.54GeV to 10.58GeV increases the Upsilon(1S) production by (10 +- 8)%.
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Caractérisation des effets antiprolifératifs et pro-inflammatoires associés à une déplétion du coactivateur transcriptionnel PGC-1beta dans le mélanomeLaurin, Karl 05 1900 (has links)
Le mélanome est le cancer de la peau le plus mortel. Il est caractérisé par une grande hétérogénéité et une reprogrammation métabolique importante qui lui confère l’habileté de promouvoir des programmes immunosuppressifs et de développer une résistance aux traitements. Cette capacité permet au mélanome d’agir sur le microenvironnement tumoral et d’échapper à l’immunosurveillance du système immunitaire. La famille des peroxisome-proliferator activated receptor gamma coactivator 1 (PGC-1s) est un joueur clé du métabolisme cellulaire en régulant la biogenèse mitochondriale, la phosphorylation oxydative et la détoxification du stress oxydatif. Des études ont montré que l’expression de PGC-1α module la fonction mitochondriale. Les fonctions de PGC-1β et PRC, les 2 autres membres de cette famille, dans le mélanome restent largement inexplorées. Ce mémoire montre pour la première fois que l’expression des PGC-1s est non seulement associée à l’expression de plusieurs molécules pro-inflammatoires (IL-8, TNF, IL-1), mais aussi à l’expression de molécules immunosuppressives (CD73, PD-L2, Galectin-9) pouvant contrôler la réponse immunitaire. Par l’utilisation d’inhibiteurs ciblant des voies de signalisation de l’immunité innée, nous avons montré que la régulation de ces molécules s’effectue via MEK et IKK dans les cellules déplétées en PGC-1β. La déplétion en PGC-1 altère la fonction mitochondriale, induisant l’expression de p21 et l’arrêt du cycle cellulaire d’une manière soutenue et via un mécanisme indépendant des dérivés réactifs de l’oxygène (ROS). Nos travaux montrent que les PGC-1s possèdent d’importantes fonctions immunitaires dans le mélanome qui peuvent potentiellement dicter la croissance tumorale, l’évasion cellulaire et la réponse aux thérapies anticancéreuses. / Melanoma is the deadliest form of skin cancer. It is defined by great heterogeneity and extensive metabolic reprogramming which gives it the ability to promote immunosuppressive programs and develop therapy resistance. This ability allows melanoma to define the tumor microenvironment and escape the immunosurveillance of the immune system. The peroxisome-proliferator activated receptor gamma coactivator 1 (PGC-1s) family is a key player in cell metabolism by regulating mitochondrial biogenesis, oxidative phosphorylation and oxidative stress detoxification. Studies have shown that the expression of PGC-1α is linked to increased mitochondrial function and the metastatic potential of melanoma. The functions of PGC-1β and PRC, the other 2 members of this family, in melanoma remain largely unexplored. This thesis shows for the first time that the expression of PGC-1s is not only associated with the expression of several pro-inflammatory molecules (IL-8, TNF, IL-1) but also with the expression of immunosuppressive molecules (CD73, PD-L2, Galectin-9) which can control the immune response. Using inhibitors targeting innate immunity signaling pathways, we have shown that the regulation of these molecules occurs via MEK and IKK in PGC-1β depleted melanoma cells. Depletion of PGC-1 impairs mitochondrial function and leads to p21 induction and cell cycle arrest in a sustained manner by a reactive oxygen species (ROS)-independent mechanism. Our work shows that PGC-1s have important immune functions in melanoma that can potentially dictate tumor growth, cell evasion and response to cancer therapies.
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Enantioselective Total Synthesis Of Diverse, Bioactive Natural Products : (+)-1S-Minwanenone, (+)-SCH 642305 And 6-EPI-(-)-Hamigeran BMurlidhar, Shinde Harish 07 1900 (has links)
Natural product synthesis is one of the most creative branch of chemistry in terms of its boundless scope for innovation and has stimulated several generations of synthetic organic chemists. With advancement in the technology, particularly in the isolation and purification techniques, high-field NMR and X-ray crystallography, it has become fairly routine to isolate and assign the structures, high-field NMR and X-ray crystallography, it has become fairly routine to isolate and assign the structures, even to those complex molecules, which are available only in microscopic quantities from natural sources. Concurrently, one has witnessed tremendous advances in the availability of new synthetic methodologies with high region-, stereo-, and enantiocontrol for one or multiple C-C bond formations and rapid generation of molecular complexity. These developments have rekindled interest with total synthesis of natural products as platforms for testing and validating new reactions and strategies. Many natural products exhibit wide range of biological activities and thus provide good leads in drug discovery but quite often such bioactive compounds are obtained only in minute quantities from Nature. Hence, there is need to synthesize them to obtain requisite quantities and build diversity around their scaffold to further explore their therapeutic potential. Thus, natural product synthesis combines both intellectual challenge and possible application for human wellbeing. Our research group is actively engaged in the synthesis of structurally complex, bioactive natural products and as a part of this endeavour, total syntheses of several bioactive compounds have been accomplished in our laboratory in recent past.
The present thesis has also evolved around the ongoing theme directed towards natural product synthesis and is organized under three chapters. Chapter I: Total synthesis of (+)-1S-Minwanenone Chapter II: Enantioselective total synthesis of the bioactive natural product (+)-Sch 642305. Chapter III: Enantiospecific total synthesis of 6-epi-(-)-Hamigeran B.
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Molecular structure studies of (1,2)-2-benzyl-2,3-dihydro-2-(1H-inden-2-yl)-1H-inden-1-olZhang, T., Paluch, Krzysztof J., Scalabrino, G., Frankish, N., Healy, A.M., Sheridan, H. 10 December 2014 (has links)
Yes / The single enantiomer (1S,2S)-2-benzyl-2,3-dihydro-2-(1H-inden-2-yl)-1H-inden-1-ol (2), has recently been synthesized and isolated from its corresponding diastereoisomer (1). The molecular and crystal structures of this novel compound have been fully analyzed. The relative and absolute configurations have been determined by using a combination of analytical tools including X-ray crystallography, X-ray Powder Diffraction (XRPD) analysis and Nuclear Magnetic Resonance (NMR) spectroscopy. / Wellcome Trust
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