Dissertations / Theses on the topic 'Field spar'

Cette thèse porte sur la restauration de champs d'ondes sismiques perturbés par trois sources de dégradation. Ces sources sont dues à des trajets de propagation complexes, au dispositif d'acquisition, à des sources liées ou non à l'acquisition, et potentiellement présentes simultanément : des réflexions multiples (ou échos), une dégradation de la réponse impulsionnelle attendue (ou flou) et des perturbations plus aléatoires (ou bruits).Nous avons considéré dans un premier temps le problème des réflexions multiples, réflexions qui se sont réfléchies plusieurs fois sur au moins une interface. Nous nous intéressons ici au filtrage adaptatif de ces réflexions sismiques multiples à partir de modèles approximatifs issus de modélisation sismique. Ce filtrage est réalisé dans un domaine de trames d'ondelettes discrètes, mono- et bidimensionnelles, sous contraintes de parcimonie et de variation lente des filtres adaptatifs. Ceci est intéressant en réflexion sismique, car les méthodes standard peuvent produire des filtres très mal conditionnés, du fait notamment du caractère passe-bande des données sismiques. Dans ce travail, une formulation variationnelle des problèmes de réflexions multiples est proposée. Nous utilisons des algorithmes proximaux, dont la convergence est garantie lorsqu'il s'agit d'optimiser dans un cadre convexe. L'avantage de ces approches est l'utilisation d'une régularisation sophistiquée, permettant de considérer la parcimonie à la fois a) dans le domaine d'ondelettes, b) via des a priori sur les filtres pour lesquels nous avons utilisé différentes fonctions de régularisation (norme l1, l2, mixte l1-2 et nucléaire). Notre méthode vise à étendre et améliorer certains aspects de la méthode proposée par S. Ventosa en collaboration avec CGG en 2012, et testée avec succès sur plusieurs campagnes sismiques. Les résultats que nous avons obtenus démontrent la performance de notre méthode non seulement sur des données synthétiques bruitées mais également sur des données réelles. Nous nous intéressons ensuite au problème de déconvolution aveugle. En géophysique, un modèle simplifié de la Terre souvent utilisé fait l'hypothèse d'un nombre de couches localement parallèles, chacune avec des propriétés constantes. Mais la vitesse, la densité ou les deux peuvent varier d'une couche à l'autre. L'impédance acoustique est calculée pour chaque couche ; puis les coefficients de réflexion pour une incidence normale sont calculés aux endroits où il y a des changements d'impédance acoustique. Chaque changement d'impédance acoustique opère une modification d'amplitude et de polarisation liée aux coefficients de réflexion. Ainsi, la séquence de réflectivité (réponse impulsionnelle) est convoluée avec la forme d'onde descendante pour donner une trace sismique. Ce problème constitue un contexte de déconvolution aveugle où l'on recherche un signal inconnu, convolué avec une forme d'onde elle aussi inconnue en présence de bruit additif. La déconvolution requiert souvent d'introduire des hypothèses complémentaires sous forme de pénalisation, notamment non convexe. L'ambiguïté d'échelle en déconvolution aveugle suggère l'usage de fonctions de contraste invariantes en échelle. Dans cette thèse, nous proposons un algorithme de minimisation alternée, de type explicite-implicite à métrique variable. Il traite une approximation lisse du rapport l1/l2 (SOOT pour "Smoothed One-Over-Two penalty") pour des données réelles signées. Nous étudions les propriétés de convergence de la méthode proposée, basées sur l'inégalité de Kurdyka-Lojasiewicz. Les performances de cette nouvelle approche sont illustrées à travers un exemple en déconvolution aveugle de données sismiques, mais aussi sur des images<br>This thesis deals with two different problems within the framework of convex and non convex optimization. The first one is an application to multiple removal in seismic data with adaptive filters and the second one is an application to blind deconvolution problem that produces characteristics closest to the Earth layers. More precisely : unveiling meaningful geophysical information from seismic data requires to deal with both random and structured “noises”. As their amplitude may be greater than signals of interest (primaries), additional prior information is especially important in performing efficient signal separation. We address here the problem of multiple reflections, caused by wave-field bouncing between layers. Since only approximate models of these phenomena are available, we propose a flexible framework for time-varying adaptive filtering of seismic signals, using sparse representations, based on inaccurate templates. We recast the joint estimation of adaptive filters and primaries in a new convex variational formulation. This approach allows us to incorporate plausible knowledge about noise statistics, datas parsity and slow filter variation in parsimony-promoting wavelet transforms. The designed primal-dual algorithm solves a constrained minimization problem that alleviates standard regularization issues in finding hyper parameters. The approach demonstrates significantly good performance in low signal-to-noise ratio conditions, both for simulatedand real field seismic data. In seismic exploration, a seismic signal (e.g. primary signal) is often represented as the results of a convolution between the “seismic wavelet” and the reflectivity series. The second goal of this thesis is to deconvolve them from the seismic signal which is presented in Chapter 6. The main idea of this work is to use an additional premise that the reflections occur as sparsely restricted, for which a study on the “sparsity measure”is considered. Some well known methods that fall in this category are proposed such as[Sacchi et al., 1994; Sacchi, 1997]. We propose a new penalty based on a smooth approximation of the l1/l2 function that makes a difficult non convex minimization problem. We develop a proximal-based algorithm to solve variational problems involving this function and we derive theoretical convergence results. We demonstrate the effectiveness of our method through a comparison with a recent alternating optimization strategy dealing with the exact l1/l2 term

Latest trend in multi core architectures is to integrate heterogeneouscores on a single chip in order to achieve task and threadlevel parallelism, high performance and energy efficiency. Someexamples of heterogeneous multi cores processors include (Tegraby NVIDIA,Cell by IBM and Fusion by AMD). The goal of this thesis work is to design a heterogeneous (2x2)network on chip which can run different tasks in parallel on allthe four cores in the network. Development steps of heterogeneousnetwork on chip include integration of Leon3 -a soft core processorby AeroFlex Gaisler which conforms with IEEE 1754 (SPARCV8) architecture- at one of the nodes of a homogeneous networkon chip incorporating four NiosII/s cores -soft core processor byAltera.This integration involves replacing a NiosII/s processor fromone of the four nodes of the homogeneous network by Leon3 processor.To translate the signals between the resource to networkinterface of the node and the Leon3 processor an AMBA bus1 toAvalon bus2 signal translation wrapper was designed. All processorsin the network on chip communicate by message passing interface.To exploit the potential of heterogeneous network on chipthree applications including sparse LU factorization, nqueens andFibonacci numbers calculation were run on it. These applicationwere run on Leon3 SPARC which generated a number of tasks thatcan run in parallel on all cores of the network simultaneously. Thisparallel execution of nqueens and fibonacci numbers calculationhas resulted in speed up as compared to the serial execution ofthese applications on Leon3 SPARC only. Because of the limitedsize of the on chip memory available for the Leon3 processor, itwas not possible to run sparse LU factorization for bigger matrixsizes and this constraint has resulted in no speed up in case ofsparse LU factorization.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 111-114).<br>Rare Earth Barium Copper Oxide (REBCO) High Temperature Superconducting (HTS) tapes are being considered for the Toroidal Field (TF) magnets of the highly compact, high-field SPARC Version 0 (V0) reactor design. The V0 design is set to operate at magnetic fields as high as 20 T, and operating temperatures ranging from 10-30 K. Due to the increase in range of operating conditions made available through the HTS-based magnets, a new set of cryogenic fluids are being considered for forced flow cooling. This thesis analyzes the thermophysical properties of helium, hydrogen, and neon, and constructs a numerical model to investigate the forced flow cooling for REBCO HTS tapes under the extreme heating conditions present in the SPARC V0 design. Four design criteria are used to assess each cryogen, including the current sharing temperature, fluid inlet temperature, cable pressure drop ([delta]P), and operating pressure. From the results of the model, neon is removed from consideration due to its high required pressure drop and low temperature margins imposed by the superconductor current sharing limit. Hydrogen provides the highest effective heat transfer rate operating at inlet conditions of 1.5 MPa and 15 K, but is constrained by safety considerations. Helium is also able to meet the current sharing condition, but with higher initial pressure and lower initial temperature. Using the numerical model, an analysis using the four design criteria finds an optimal operating condition for helium of 2.5 MPa and 10 K based on minimizing cable pressure drop ([delta]P) and inlet pressure, while maximizing the fluid's inlet temperature. With a target operating point defined, an experimental cryogenic flow loop is designed with the purpose of verifying the high heat transfer rates required for the high-pressure, supercritical helium flow in the SPARC reactor. The flow loop uses a pressure differential to drive flow at a target mass flow rate of 46 g/s. To simulate a plasma pulse, the fluid flow is subject to heat fluxes up to 45 kW/m² for a minimum duration of ten seconds.<br>Supported by the U.S. Department of Energy, Office of Fusion Energy Science Grant: DE-FC02-93ER54186<br>by Julien Barber.<br>S.M.

Although it has long been recognized that genetic variation in spear yield in asparagus (Asparagus officinalis L.) is related to the amount of storage carbohydrate reserve in the storage roots, which in turn is linked to photoassimilate production in the previous season, the physiological basis for this variation is not known. In this study, diurnal and seasonal changes in photosynthetic parameters, carbon partitioning parameters and carbon utilization in developing spears were investigated in two asparagus cultivars with contrasting yield. The purpose of the investigations described in this thesis was to characterize the physiological characters underlying cultivar differences in spear yield of asparagus, with the emphasis on carbon assimilation, partitioning, utilization and sucrose metabolism during an annual cycle. Seasonal patterns in photosynthetic parameters were strongly dependent on cladophyll developmental stage in both cultivars. The greatest photosynthetic rates (A) of 8.94 ± 0.54 /µmol m-2 s-1 for the high-yielding cultivar (ASP-69) and 6.50 ± 0.38 /µmol m-2 s-1 for the low-yielding cultivar (ASP-03) were observed in fully expanded cladophyll tissue measured in mid-summer (February) when both photon flux density (PFD) and temperature were at a maximum. A significant decline in A was measured in April. This was accompanied by a significant decrease in both stomatal conductance (gs) and ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activity. A close correlation between A and gs (r = 0.84) was observed. Although a correlation between A and total rubisco activity did not exist, both in vivo and fully activated rubisco activities in ASP-69 were significantly greater than in ASP-03, indicating the important role of this enzyme to cultivar differences in photosynthetic capacity. The difference in photosynthetic capacity between the two cultivars was related to significant differences in cladophyll thickness and specific leaf weight (SLW). Maximum photosynthetic rate (Amax) was positively correlated with sucrose phosphate synthase (SPS) activity (r = 0.86). ASP-69 exhibited greater SPS activity and sucrose content than ASP-03 in fully expanded and mature cladophyll tissue. ASP-69 also displayed a higher percentage of soluble sugar in stem cell sap than did ASP-03. These results suggest that carbon translocation rate in ASP-69 is higher than in ASP- 03. Sucrose synthase (SS) activity in storage roots in ASP-69 was significantly greater than in ASP-03 during fern growth season. Total non-structural carbohydrate (TNC) concentration in storage roots did not differ in the two cultivars. Biomass analysis revealed that ASP-69 had a greater root/shoot ratio than in ASP-03, suggesting that the total carbohydrate storage pool rather than carbohydrate concentration is an important determinant of asparagus yield. Rates of assimilate export estimated from A and dry mass changes were highest at midday and coincided with maximum assimilation rate in both cultivars. A positive correlation was found between A and assimilate export rate (r = 0.87) and this relationship did not differ between the two cultivars studied. The greater carbon export rate per unit cladophyll area measured in ASP-69 was associated with significantly higher A and sucrose concentration in the cladophyll tissue in comparison to ASP-03. Biochemical evidence indicated that the greater A and sucrose accumulation in ASP-69 were associated with a significantly higher SPS activity (P < 0.05). Phloem 14C exudate analysis confirmed the results estimated by dry mass changes and revealed that 14C flux out of cladophyll tissue in ASP-69 was significantly greater than in ASP-03. The greater spear elongation rate measured in ASP-69 was associated with a significantly higher hexose accumulation (P < 0.05) in spear tissue in comparison to ASP-03. However, sucrose content was similar in the two cultivars, suggesting more efficient machinery for transport and catalysis of carbohydrate in spears of ASP-69. Biochemical evidence indicated that the greater elongation rate in ASP-69 was associated with a significantly higher acid invertase (AI) activity (P < 0.05) in the elongation zone, whereas SS activity was not significantly different between the two cultivars. There was little neutral invertase (NI) activity detected in either cultivar. These results strongly suggest that it is AI and not SS or NI that is an important determinant of the difference in sucrose metabolism between the two asparagus cultivars in metabolising imported sucrose in the elongation region, which in turn plays a part in regulating the import of sucrose into spear tissue. The profile of sucrose cleaving enzyme activities along spear sections indicated that SS was the dominant enzyme in both tip and base of spears, whereas AI was the dominant enzyme in the elongation zone. Overall the data substantiate the conclusion that changes in activities of sucrose cleaving enzymes are correlated with sink functions in developing spears. The results obtained from this study are consistent with a feed-forward relationship among photosynthesis, sucrose synthesis and assimilate export in the cladophyll tissue. Both metabolic and anatomical factors appear to play significant roles in determining differences in photosynthetic capacity between the two asparagus cultivars studied. For the role of carbohydrate storage roots, it is the pool of total carbohydrate storage rather than carbohydrate concentration that is an important determinant of asparagus yield. This was indicated by the fact that high-yielding cultivar (ASP-69) exhibited a high percentage of young roots to the total biomass than the low-yielding cultivar (ASP-03). This difference was related to a great SS activity in ASP-69. In developing spears, ASP-69 displayed great sucrose cleaving enzyme activities than in ASP-03, indicating that carbohydrate demand in the sink tissue is an important determinant of spear development. The overall results substantiate the conclusion that spear yield is influenced by both source and sink properties, in which spear elongation is closely related to spear ability to import carbon and the overall yield is determined by the available carbohydrate reserve accumulated in the carbohydrate storage pool, which in turn is linked to assimilate production.

In der SLUB Dresden wird durch die DFG u. a. das Sondersammelgebiet „Zeitgenössische Kunst seit 1945“ gefördert. Ende Juli haben sich mehrere StudentInnen zu einem Workshop angemeldet: „Dem teuersten Gemälde der Welt auf der Spur“. Bei diesem Workshop werden von den Teilnehmern Kataloge und Datenbanken auf Informationen zu Jackson Pollock und zu dem sensationellen Verkauf seines Bildes abgefragt. Vor allem soll geprüft werden, wie zeitaufwändig die Suche in verschiedenen Datenbanken und Katalogen ist.

From past experiments conducted with high intensity lasers, it has been known for some time that laser matter interactions result in the emission of short, transient electromagnetic pulses. Previous investigations into laser generated electromagnetic pulses provide basic information regarding frequencies where such pulses may be present, along with the time duration of the pulses. Such investigations have also demonstrated a number of measurement techniques in which basic information on the pulses may be obtained. The purpose of this current investigation is to obtain a more thorough description and understands of electromagnetic pulses generated for laser matter interaction. To this end, spatial radiation patterns emanating from various laser excited matter sources was predicted using antenna theory for far field radiators. Experimentally, it is the intention of this investigation to gather comprehensive time and frequency domain data on laser matter generated electromagnetic pulses using a number of specific laser targets. Radiation detection techniques using broadband, calibrated EMC horn antennas were devised. A unique measurement system known as an inverse superhetereodyne receiver was designed, tested and demonstrated. An experimental setup using such instrumentation was established. Using the above instrumentation and experimental setup should yield comprehensive time and frequency domain data over a spectra range of 1-40 GHz and with a time resolution of 50 ps. Because the experimental system employed is calibrated, measurements can be corresponded to incident electromagnetic fields. Several tests were conducted to ensure the proper operation of experimental apparatus. A modulation test was conducted on the inverse superhetereodyne receiver to ensure that the experimentally observed signals appeared when and where predicted within the receiver's bandwidth. The experimental setup was used to measure radiation emitted from an electrostatic discharge source of known distance and discharge voltage. Frequency domain data from the discharges were collected and compiled using a Matlab application ultimately intended to measure laser matter interaction generated electromagnetic pulses, resulting in a compiled frequency domain description comprising 1-17 GHz. The inverse Fourier transform was used to retrieve the time domain response from the compiled data. The discharge gaps characteristics where systematically altered as to allow a parametric study of the compiled data. The discharge measurements demonstrate the measurement system's ability to analyze unknown, short duration; broadband microwave signals.<br>M.S.<br>Department of Physics<br>Arts and Sciences<br>Physics

In the first part of the thesis I present a theoretical and experimental work due to develop a performing configuration for gas-sensing through the employ of Surface Plasmon Resonance effect. Different sensing layers have been studied and tested on our optical bench assembly. Metallic (Au) and bimetallic (Ag/Au) layers have been properly designed through simulations and then have been realized through electron-beam evaporation. TiO2 and TiO2 - Au doped layers have been deposited on the top of some of the metallic samples. These layers were prepared by the sol gel route. In the second part I focused on the development of an experimental set-up able to study the local field at an interface between two dielectrics. An approach based on photo-thermal-deflection has been used. Chromophores have been used as probes of the local field<br>Nella prima parte della mia tesi presento un lavoro teorico e sperimentale atto a sviluppare una configurazione adatta alla sensoristica, sfruttando il fenomeno della risonanza plasmonica di superficie. Diferse configurazioni dello strato sensibile sono state testate sul set-up da banco ottico, costruito a tale scopo. Nella seconda parte mi sono concentrata sullo sviluppo di un metodo sperimentale per lo studio del campo elettrico all'interfaccia tra due dielettrici. Si è usato un approccio basato su photo-thermal-deflection. Come sonde del campo locale sono state utilizzate delle molecole cromofore

Ultra high temperature ceramics (UHTC) are candidate materials for high temperature applications such as leading edges for hypersonic flight vehicles, thermal protection systems for spacecraft, and rocket nozzle throat inserts due to their extremely high melting points. Tantalum and Niobium Carbide (TaC and NbC), with melting points of 3950°C and 3600°C, respectively, have high resistivity to chemical attack, making them ideal candidates for the harsh environments UHTCs are to be used in. The major setbacks to the implementation of UHTC materials for these applications are the difficulty in consolidating to full density as well as their low fracture toughness. In this study, small amounts of sintering additive were used to enhance the densification and Graphene Nanoplatelets (GNP) were dispersed in the ceramic composites to enhance the fracture toughness. While the mechanisms of toughening of GNP addition to ceramics have been previously documented, this study focused on the anisotropy of the mechanisms. Spark plasma sintering was used to consolidate both bulk GNP pellets and near full relative density TaC-NbC ceramic composites with the addition of both sintering aid and GNP and resulted in an aligned GNP orientation perpendicular to the SPS pressing axis that allowed the anisotropy to be studied. In situ high load indentation was performed that allowed real time viewing of the deformation mechanisms for enhanced analysis. The total energy dissipation when indenting the bulk GNP pellet in the in-plane GNP direction was found to be 270% greater than in the out-of-plane orientation due to the resulting deformation mechanisms that occurred. In GNP reinforced TaC-NbC composites, the projected residual damaged area as a result of indentation was 89% greater when indenting on the surface of the sintered compact (out-of-plane GNP orientation) than when indenting in the orthogonal direction (in-plane GNP orientation) which is further evidence to the anisotropy of the GNP reinforcement.

The research presented in this thesis was undertaken in order to develop an understanding of the biology of Perna canaliculus sufficient to allow for commercial hatchery based production of Greenshell™ mussel spat. Hatchery production is an alternative to unreliable and inconsistent wild spat collection. In a Perna canaliculus population followed for one year spawning occurred in early spring and late summer. Three quantitative histological measures of gonad maturity utilising image analysis technology and a qualitative classification system were compared. Measuring the relative surface area comprised of gametes on histological sections was found to be the most reliable method. A practical gonad visual index to determine the reproductive condition of adults for the selection of broodstock was developed and found to be highly effective as a means of predicting induced spawning success. Serotonin was not effective for inducing spawning of Perna canaliculus. Temperature shock and the use of stripped gametes was however found to be a reliable spawning induction method. Relative gamete concentration, gamete age, temperature, sperm half life and gamete contact times were all found to have effects on fertilisation success for Perna canaliculus. Sperm concentration and the conditions of sperm aging were particularly important. Fertilisation kinetics of Perna canaliculus gametes modelled using the Vogel-Czihak-Chang-Wolf method suggested that 5% of sperm-egg contacts lead to successful fertilisation. Broodstock management protocols that could be used to condition the adult of Perna canaliculus were investigated in order to enhance and prolong the natural reproductive season. Research suggested that for successful broodstock conditioning animals should already have begun gametogenesis at the time conditioning is commenced. Successful conditioning of Perna canaliculus was achieved at temperatures between l0 and 16°C over a period of about 50 days. A diet ration above 2-3% of the dry meat mass per day is suggested. A trial examining non-algal diet supplements suggest a mixture of yeast and lipid emulsion may have some potential value. Photoperiod manipulation did not effect the reproductive condition of Perna canaliculus. The yield of veliger larvae was significantly enhanced if embryo culture water was treated with 1.0 mg/l EDTA. Veliger yield was not significantly affected at densities below 50 embryos/ml. Perna canaliculus larvae grew most rapidly and survived well at the salinity of 35 ppt. Larvae grew most rapidly when cultured at low densities. Experiments suggest that early larvae can be cultured at 5-10/ml, however late stage larvae grew most rapidly when cultured at l/ml. Perna canaliculus larvae displayed best growth and good survival if fed a mixed flagellate-diatom diet comprising Isochrysis galbana (T-Iso) and Chaetoceros calcitrans. The optimal diet ration, as a function of larval size, increased from about 20 cells/μl Isochrysis galbana (T-Iso) to around 150 cells/μl through the larval development period. Thyroxine between the concentrations of l0-5 and l0-8 M did not have an observable effect on larval developmental rate or eye spot development. Down welling settlement systems were found to be generally successful for Perna canaliculus lanrae. L-DOPA was also demonstrated to enhance the settlement and metamorphosis of Perna canaliculus pediveligers.

Spark plasma sintering (SPS) is a powder consolidation technique used to rapidly densify a variety of material systems. SPS is capable of precisely controlling material microstructures and achieving non-equilibrium phases due to rapid heating and cooling rates through the simultaneous application of pressure and direct current. Due to these characteristics, SPS is an ideal processing technique for high temperature ceramics which require processing at temperatures greater than 1500°C. Due to the desirable properties obtained on small diameter materials processed by SPS, larger and more complex geometries are desired while maintaining sample microstructures. In order to accurately scale ceramics produced by SPS, a finite element model must be developed that can be used as a predictive tool. My research focuses on developing a finite element model for the spark plasma sintering furnace at the University of Arizona and validating modeled results using experimentally obtained data. Electrical and thermal conductivity as functions of temperature vary widely among different grades of commercially available electrode grade graphite at constant density. Modeled material properties are optimized in order to calibrate modeled results to experimentally obtained data (i.e. measured current, voltage, and temperature distributions). Sensitivity analysis is performed on the model to better understand model physics and predictions. A calibrated model is presented for 20mm ZrB2 and Si3N4 discs. Sample temperature gradients are experimentally confirmed using grain size and β-Si3N4 phase composition. The model is used to investigate scale up from 20mm to 30mm discs and 30mm rings as well as effects of processing conditions on β-Si3N4 content.

Currently environmental concerns are driving internal combustion engine manufacturers to seek greater fuel efficiency, more refinement and lower emissions. Cyclic variation is a known obstacle to achieving the greatest potential against these goals and therefore an understanding of how to reduce these is sought. It is widely accepted that cyclic variation in in-cylinder flow motions is a key contributor to overall cyclic variation and therefore the characterisation of factors affecting these is an important step in the process of achieving a better understanding and ultimately control of cyclic variation. This thesis reports the development of a novel optical engine research facility in which high speed digital particle image velocimetry (HSDPIV) has been applied to the study of flow field behaviour within a direct injection spark ignition (DISI) engine. This study investigates the spatial and temporal development of flow structures over and within many engine cycles. Flow field PIV measurements have been captured with a high spatial resolution and temporal frequencies up to 5 kHz from a number of measurement locations at a large range of crank angles. The major contributions from this work have included the use of the novel measurement technique to investigate spatial and temporal flow field development in the intake runner, valve jet, in-cylinder tumble and swirl planes and the pent roof. The gathered data have been used to investigate cycle by cycle variations in both high and low frequency flow structures. Major findings of this work have included the observation of highly varying flow fields throughout the engine cycle. Frequency analysis of these flows has allowed the low frequency bulk motions and higher frequency turbulent components to be studied. The low frequency flow field components are shown to create varying flow field interactions within the cylinder that also affect the manner in which the flow develops over the course of the cycle. The intensity of the turbulence fluctuations, u , has been calculated based upon the high frequency components within the flow and variations within this are shown to correlate with pressure related combustion parameters.

This research presents the first use of side-polished Panda fiber in the fabrication of slab-coupled optical sensors (SCOS). It is determined that the Panda SCOS provides a sensor that is comparable to the D-fiber SCOS in cases of electric field sensing. It exhibits greater power transfer and higher bandwidth than a typical D-SCOS. The Panda SCOS is also less costly and easier to splice than the D-fiber alternative. This comes at a cost of slightly decreased sensitivity and a more fragile fabrication process. This research also demonstrates the use of the Panda-SCOS as means of voltage characterization across both the spark gap of an ignition coil circuit along with the spark gap of an automobile. This paper demonstrates the use of a Panda SCOS to measure the voltages and time delays across the spark gaps at different stages of a Marx generator setup .

Au cours de la dernière décennie, la popularité incomparable des réseaux sociaux numériques s’est traduite par l’omniprésence des spammeurs sur ces plateformes. Cette présence a commencé par se manifester sous la forme de messages de publicité et d’arnaques traditionnels simples à identifier. Pourtant, elle s’est métamorphosée durant les dernières années, et couvre dorénavant de larges tentatives de manipulation qui sont assez importantes et beaucoup plus préoccupantes. Cet abus ciblé et largement automatisé des réseaux sociaux numériques réduit la crédibilité et l’utilitédes informations diffusées sur ces plateformes. Le problème de détection du spam social a été traditionnellement modélisé comme un problème de classification supervisée où l’objectif est de classer les comptes sociaux individuellement. Ce choix est problématique pour deux raisons. Tout d’abord, la nature dynamique du spam social rend les performances des systèmes supervisés difficiles à maintenir. En outre, la modélisation basée sur les caractéristiques (features) des comptes sociaux individuels ne prend pas en compte le contexte collusoire dans lequel les attaques sur les réseaux sociaux sont menées. Pour maximiser leur efficacité et la visibilité de leur contenu, les spammeurs actent d’une manière qu’on peut décrire comme “synchronisée”. Ainsi, même lorsqueles spammeurs changent de caractéristiques, ils continuent à agir de manière collusoire, créant des liens entre les comptes complices. Ceci constitue un signal non supervisé qui est relativement facile à maintenir et difficile à contourner. Il est donc avantageux de trouver une mesure de similarité adaptée qui soit capable de capturer ce comportement collusoire. Dans ce travail, nous proposons d’exprimer le problème de détection de spam social en termes probabilistes en utilisant le cadre des modèles graphiques non dirigés. Au lieu du paradigme de détection individuelle qui est couramment utilisé dans la littérature, nous cherchons à modéliser la tâche de classification comme une tâche d’inférence sur la probabilité jointe d’un graphe de variables. Dans ce contexte, les comptes sont représentés comme des variables aléatoires et la dépendance entre ces variables est représentée par un graphe. Cette expression probabiliste permet de modéliser l’incertitude inhérente aux systèmes de classification. Le graphe permet aussi d’exploiter la dépendance qui découle de la similitude induite par le comportement collusoire des spammeurs. Nous proposons deux modèles graphiques: le Champs Aléatoire de Markov où l’inférence est effctuée par l’algorithme de Propagation des Convictions à Boucle, et le Champs Aléatoire Conditionnel, où on choisit d’utiliser l’algorithme du Tree Reweighted Message Passing pour l’inférence et une fonction de perte qui minimise le risque empirique. Les deux modèles, évalués sur Twitter, montrent une augmentation des performances de classification par rapport aux classifieurs supervisés de la littérature. Le Champ Aléatoire Conditionnel offre de meilleures performances de classification par rapport au Champs Aléatoire de Markov. Il est aussi plus robuste face aux changements dans la distribution des caractéristiques des spammeurs<br>Over the last decade, the growing popularity of Online Social Networks has attracted a pervasive presence of social spammers. While this presence has started with spam advertising and common scams, the recent years have seen this escalate to the far more concerning mass manipulation attempts. This targeted and largely automated abuse of social platforms is risking the credibility and usefulness of the information disseminated on these platforms. The social spam detection problem has been traditionally modeled as a supervised problem where the goal is to classify individual social accounts. This common choice is problematic for two reasons. First, the dynamic and adversarial nature of social spam makes the performance achieved by features-based supervised systems hard to maintain. Second, features-based modeling of individual social accounts discards the collusive context in which social attacks are increasingly undertaken. Acting synchronously allows spammers to gain greater exposure and efficiently disseminate their content. Thus, even when spammers change their characteristics, they continue to act collusively, inevitably creating links between collusive spammingaccounts. This constitutes an unsupervised signal that is relatively easy to maintain and hard to evade. It is therefore beneficial to find a suitable similarity measure that captures this collusive behavior. Accordingly, we propose in this work to cast the social spam detection problem in probabilistic terms using the undirected graphical models framework. Instead of the individual detection paradigm that is commonly used in the literature, we aim to model the classi_cation task as one of joint inference. In this context, accounts are represented as random variables and the dependency between these variables is encoded in a graphical structure. This probabilistic setting allows to model theuncertainty that is inherent to classification systems while simultaneously leveraging the dependency that _ows from the similarity induced by the spammers collusive behavior. We propose two graphical models: the Markov Random Field with inference performed via Loopy Belief Propagation, and the Conditional Random Field with a setting that is more adapted to the classification problem, namely by adopting the Tree Reweighted message passing algorithm for inference and a loss that minimizes theempirical risk. Both models, evaluated on Twitter, demonstrate an increase in classification performance compared to state-of-the-art supervised classifiers. Compared to the Markov Random Field, the proposed Conditional Random Field framework offers a better classification performance and a higher robustness to changes in spammers input distribution

Cette étude introduit une nouvelle approche appelée Bivariate 2D-EMD pour séparer le mouvement organisé à grande échelle, soit la composante basse fréquence de l’écoulement des fluctuations turbulentes, soit la composante haute fréquence dans un champ de vitesse instantané bidimensionnel.Cette séparation nécessite un seul champ de vitesse instantané contrairement aux autres méthodes plus couramment utilisées en mécanique des fluides, comme le POD. La méthode proposée durant cette thèse est tout à fait appropriée à l’analyse des écoulements qui sont intrinsèquement instationnaires et non linéaires comme l'écoulement dans le cylindre lorsque le moteur fonctionne dans des conditions transitoires. Bivariate 2D-EMD est validé à travers différents cas test, sur un écoulement turbulent homogène et isotrope (THI) expérimental, qui a été perturbé par un tourbillon synthétique de type Lamb-Ossen, qui simule le mouvement organisé dans le cylindre. Enfin, Il est appliqué sur un écoulement expérimental obtenu dans un cylindre et les résultats de la séparation d'écoulement sont comparés à ceux basés sur l'analyse POD. L’évolution d’écoulement dans le cylindre pendant le fonctionnement du moteur transitoire, c’est à dire une accélération du régime moteur de 1000 à 2000tr/min en différentes rampes, sont mesurée en utilisant de PIV 2D-2C haute cadence. Les champs de vitesse sont obtenus dans le plan de tumble dans un moteur un moteur GDI mono-cylindre transparent et forment une base de données nécessaire pour valider les résultats de simulation numérique<br>This study introduces a new approach called Bivariate 2D-EMD to separate large-scale organizedmotion i.e., flow low frequency component from random turbulent fluctuations i.e., high frequency onein a given in-cylinder instantaneous 2D velocity field. This signal processing method needs only oneinstantaneous velocity field contrary to the other methods commonly used in fluid mechanics, as POD.The proposed method is quite appropriate to analyze the flows intrinsically both unsteady and nonlinearflows as in in-cylinder. The Bivariate 2D-EMD is validated through different test cases, by optimize itand apply it on an experimental homogeneous and isotropic turbulent flow (HIT), perturbed by asynthetic Lamb-Ossen vortex, to simulate the feature of in-cylinder flows. Furthermore, it applies onexperimental in-cylinder flows. The results obtained by EMD and POD analysis are compared. Theevolution of in-cylinder flow during transient engine working mode, i.e., engine speed acceleration from1000 to 2000 rpm with different time periods, was obtained by High speed PIV 2D-2C. The velocityfields are obtained within tumble plane in a transparent mono-cylinder DISI engine and provide a database to validate CFD

Le LNCMI-Toulouse produit les champs magnétiques non-destructifs pulsés parmi les plus puissants du monde (98,8 T). Les fils conducteurs utilisés dans les bobines qui génèrent ces champs magnétiques nécessitent une contrainte à la rupture élevée afin de résister aux forces de Lorentz. De plus, pour obtenir une durée d'impulsion la plus longue possible, ces conducteurs doivent avoir une résistivité électrique la plus proche possible de celle du Cu pur. Le LNCMI et le CIRIMAT explorent la conception et la préparation de fils nano-composites à matrice Cu par une combinaison de métallurgie des poudres, de frittage SPS et de tréfilage. Les poudres composites à faibles teneurs en Ag (&lt; 10 % vol. Ag) sont préparées en dispersant des microfils d'Ag (diamètre 200 nm, longueur 30 µm) synthétisés au CIRIMAT dans une poudre commerciale de Cu sphérique (diamètre 0,5-1 µm). Les poudres ainsi obtenues sont consolidées par SPS sous forme de barreaux. Ceux-ci sont étirés sans rupture, jusqu'à l'obtention de fils fins (diamètre 1 - 0,2 mm) dont la microstructure est sous la forme de grains ultrafins de Cu (200 - 400 nm) allongés sur plusieurs micromètres dans le sens de l'étirage. Les microfils d'Ag sont dispersés le long des joints de grains du Cu. La mesure de la résistivité électrique et de la contrainte à la rupture des fils (à 293 K et 77 K) a permis de déterminer que les fils contenants seulement 1 % vol. Ag présentent le meilleur compromis contrainte à la rupture / résistivité (1100 MPa / 0,49 µÔmega.cm à 77 K). La formation d'un alliage Cu/Ag lors du frittage SPS a pour conséquence une augmentation notable de la résistivité électrique des fils et doit donc être évitée. Une matrice de Cu avec une distribution bimodale de la taille des grains permet de réduire la résistivité électrique tout en conservant une haute contrainte à la rupture (1080 MPa / 0,45 µÔmega.cm à 77 K). Les fils nano-composites Ag-Cu présentent une contrainte à la rupture équivalente à celle des fils d'alliage Cu/Ag contenant environ 20 fois plus d'Ag élaborés par fusion et solidification, mais présentent une résistivité électrique environ 1,5 fois plus faible<br>LNCMI-Toulouse produces some of the most intense non-destructive pulsed magnetic fields in the world (98.8 T). The wires used in coils which generate these magnetic fields require high ultimate tensile strength (UTS) in order to resist the Lorentz forces. Moreover, to obtain the longest possible pulse duration, these wires must have an electrical resistivity closest to that of pure Cu. LNCMI and CIRIMAT explore the design and preparation of Cu-based nanocomposite wires obtained by a combination of powder metallurgy, Spark Plasma Sintering (SPS) and wire-drawing. Composite powders with low Ag contents (&lt; 10 % vol. Ag) are prepared by dispersing Ag microwires (diameter 200 nm, length 30 µm) synthesized at CIRIMAT in a commercial spherical Cu powder (diameter 0.5-1 µm). The so-obtained composite powders are consolidated by SPS in the form of cylinders. These cylinders are drawn, without breaking, in the form of fine wires (1 - 0.2 mm). The microstructure of the wires is made up of Cu ultrafine grains (200 - 400 nm) elongated over several micrometers in the drawing direction. Ag microwires are dispersed along the grain boundaries of Cu. The measurement of the electrical resistivity and the UTS of the wires (at 293 K and 77 K) shows that the wires containing only 1 vol. % Ag present the best compromise between high UTS and low electrical resistivity (1100 MPa / 0.49 µÔmega.cm at 77 K). The formation of Cu/Ag alloys during the SPS cycle significantly increases the resistivity of the wires and thus must be avoided. A Cu matrix with a bimodal grain size distribution makes it possible to reduce the electrical resistivity of the wires while keeping high UTS (1080 MPa / 0.45 µÔmega.cm at 77 K). Ag-Cu nanocomposite wires present high UTS, equivalent to that of Cu/Ag alloy wires containing about 20 times more Ag produced by melting and solidification, but their electrical resistivity is about 1.5 times lower

Techniky rychlého slinování jako „Spark Plasma Sintering (SPS)“, „Flash Sintering“ (FS), „Selective Laser Sintering“ (SLS), „Induction Sintering“ (IS) a „Microwave Sintering“ (MS) jsou navrženy tak, aby účinně a předvídatelně kontrolovaly mikrostrukturu během slinovací proces. Spark Plasma Sintering jako jedna z nejmodernějších technik rychlého slinování a byla studována po celá desetiletí. V SPS má tři hlavní rysy: přímý ohřev elektrickým proudem, pulzní stejnosměrný elektrický proud a mechanický tlak. Mechanismy působení faktorů během SPS procesu však nejsou zatím jasně objasněny. Tato práce byla inspirována zvýšeným zájmem o techniky rychlého slinování a snahou o objasnění působení hlavních faktorů. Tato studie je rozdělena do čtyř částí: efekt elektromagnetického pole, efekt pulzního vzoru, tlakový efekt a přímý Joulův ohřev. Výsledky ukázaly, že elektromagnetické pole v SPS může být ignorováno, jak ukázaly simulace, a rovněž během experimentů nebyl nalezen žádný „efekt pole“. Na druhou stranu účinek pulzního vzoru byl významný, prášek TiO2 byl slinován pulzními vzory 12:2 a 10:9 s konstantním příkonem. Po aplikaci pulzního vzoru 10:9 došlo ke zvýšení velikosti zrna o jeden řád a ke zvýšení hustoty o 8%, zatímco množství spotřebované energie zůstalo konstantní. Při zahřátí s různými vzory pulzů se mění účinný výkon a kontaktní odpor indukovaný mechanickým pulsem, což jsou dva hlavní důvody, které vysvětlují měnící se energetickou účinnost. Vliv tlaku byl také významný, výsledky ukázaly, že použití tlaku při 900 ° C přineslo vysokou hustotu a malou velikost zrn, což vedlo k nejvyšší tvrdosti měřenou podle Vickerse. Interakce mezi tlakem a parami, vedoucí k rozdílné rychlosti přenosu páry v prvním slinovacím stupni, je považována za důvod pro rozdíly v mikrostruktuře, jako jsou mikropóry. Načasování mechanického tlaku může také podporovat difúzní mechanismy zhutňování během druhého slinovacího stupně, jako je difúze na hranicích zrn a mřížková difúze. Přímý ohřev, kdy se vede elektrický proud přímo skrz vzorek, vede k nízké měřené teplotě při slinování karbidu boru a jeho kompozitů, avšak teplota uvnitř vzorku je podstatně vyšší. Přidání slitiny titanu a křemíku do B4C významně zvýšilo finální hustotu, což byl hlavní důvod ovlivnění mechanických vlastností. Vzorek B4C + 1.0Ti (1 obj. % Ti slitiny) dosáhl nejvyšší tvrdosti 3628.5 ± 452.6 HV1 (16.2% vyšší než čistý B4C) s lomovou houževnatostí 2.11 ± 0.25 MPa m0.5. Zatímco při dopování křemíkem dosáhl vzorek B4C + 0.5Si (0.5 obj. % křemíku) nejvyšší tvrdosti 3524.6 ± 207.8 HV1 (o 13.0% vyšší než čistý B4C), vzorek B4C + 1.0Si dosáhl nejvyšší lomové houževnatosti 2.97 ± 0.03 MPa m0.5 (o 15.6% vyšší než čistý B4C). Velikost zrn kompozitů dotovaných titanem se oproti čistému karbidu boru byla o něco větší a mikrostruktura více nehomogenní. Naproti tomu se velikost zrn vzorků dotovaných křemíkem příliš nezměnila ve srovnání s velikostí zrn čistého karbidu boru. Sekundární fáze karbid křemíku byla dobře spojena s matricí karbidu boru a vykazovala pozitivní účinek jak na tvrdost, tak na lomovou houževnatost. Tato práce zkoumala vliv různých kontroverzních a nepopsaných aspektů na slinování keramických materiálů metodou Spark Plasma Sintering, což vedlo k lepšímu pochopení této techniky slinování.

Ce travail porte sur l'élaboration et l'analyse du comportement mécanique d'alliages à distribution bimodale de taille de grains. Les applications concernent les aciers inoxydables austénitiques 304L et 316L. Une approche couplée expérience-modélisation est menée pour comprendre les réponses mécaniques macroscopiques et locales de ces nouveaux alliages en se basant notamment sur l'étude des mécanismes de déformation associés. L'utilisation de deux voies d'élaboration et l'optimisation de leurs paramètres a conduit à l'obtention d'un large choix d'échantillons avec différentes distributions bimodales et différentes proportions de chaque famille de taille de grains. L'influence de ces caractéristiques microstructurales sur le comportement a été analysée sur la base d'essais en traction simple sous chargement monotone ou en charges-décharges alternées. Une base de données étendue de propriétés a ainsi été constituée et des éléments de réponse concernant les mécanismes de déformation propres aux alliages bimodaux ont pu être apportés. La présence de grains de taille conventionnelle (Coarse Grain -CG) au sein d'une matrice à grains ultrafins (UltraFine Grain - UFG) semble favoriser la relaxation d'une partie des contraintes internes de la matrice et tend ainsi à retarder l'endommagement des alliages bimodaux en comparaison aux alliages unimodaux à grains ultrafins. Une modélisation à champs complets selon deux lois de plasticité cristalline tenant compte explicitement d'une longueur interne a été proposée. Sa première motivation est de fournir un outil de prédiction du comportement effectif des alliages bimodaux en fonction de leurs caractéristiques microstructurales. Elle donne par ailleurs accès aux champs locaux et permet d'appuyer les analyses expérimentales en partition des contraintes en montrant à la fois une relaxation partielle des contraintes dans la matrice UFG mais aussi des concentrations de contrainte aux interfaces CG/UFG<br>This work is focused on the elaboration and the mechanical behaviour of 304L and 316L austenitic stainless steel alloys with bimodal grain size distribution. The complementary approach between experiments and modelling enables a better understanding of both macroscopic and local mechanical responses and also of the associated deformation mechanisms.The use of two elaboration routes and optimized process parameters results in a wide range of samples with different bimodal grain size distributions. Grain sizes and fractions of each population are modified in order to study the influence of these microstructural characteristics on mechanical behavior. Uniaxial tensile tests are used to realize a database of mechanical properties of bimodal alloys and loading-unloading tests provides valuable informations about deformation mechanisms in these materials. With coarse grains (CG) embedded in an ultrafine grained (UFG) matrix, a relaxation of a part of the internal stresses seems to take place and leads to a delayed embrittlement of bimodal alloys as compared to their unimodal counterparts. Full-field modelling, based on two crystal plasticity laws with an explicit account of an internal length, is proposed. It constitutes a valuable prediction tool of effective properties of bimodal alloys in order, in particular, to study the effect of several microstructural characteristics. An access to local fields is also possible and tend, so far, to show similar results compared to experimental ones : stress relaxation is observed in the UFG matrix as well as stress concentrations at the CG/UFG interfaces

This project is a study of the wastescape - a network of waste - of Bhubaneswar and Cuttack in Odisha, India.  The study incorporates key locations, e.g. landfills, urban wastelands and waste warehouses; major actors in the formal and informal waste sector; and flows of waste through economic and social systems. Drawing from the studies, multiple interventions within the wastescape are proposed for improvement of the economic, ecologic and social situation. An important aspect of the project is the development of an approach for how to, as architects, work with big, complex, contingent networks; how to map and understand such a system; and how to determine where to intervene. To improve the existing wastescape, interventions must consciously and holistically address multiple scales; levels of formal-informal; and phases within the waste cycle. The study includes a vast amount of possible interventions. Some of the interventions are further detailed to show feasibility; impact on the wastescape; and synergies with other interventions within the wastescape.<br>Projektet “Wastescape of Bhubaneswar &amp; Cuttack” är en studie av ett nätverk av skräpflöden genom Bhubaneswar och Cuttack i Odisha, Indien. Studien inkorporerar viktiga platser, t.ex. deponier, urbana ödemarker och lokaler för skräphandel; stora aktörer i den formella och informella skräpsektorn; och flöden av skräp genom ekonomiska och sociala system. Utifrån dessa studier, ett flertal interventioner i “the wastescape” föreslås för att förbättra den ekonomiska, ekologiska och sociala situationen. En viktig aspekt av arbetet är utvecklingen av ett sätt att, som arkitekt, arbeta med storskaliga, komplexa och inter-beroende nätverk; hur sådana system kan kartläggas och förstås; samt hur det går att avgöra vart och hur interventioner passar in i “the wastescape”. För att förbättra “the wastescape”, interventioner måste medvetet och holistiskt adressera multipla skalor; nivåer av formell-informell; och faser i skräpets kretslopp. Studien innehåller ett stort nummer av möjliga interventioner. Några av dessa interventioner är ytterligare detaljerade för att visa på genomförbarhet; påverkan på “the wastescape”; och synergier gentemot andra interventioner i “the wastescape”.

Demands for delivering high instantaneous power in a compressed form (pulse shape) have widely increased during recent decades. The flexible shapes with variable pulse specifications offered by pulsed power have made it a practical and effective supply method for an extensive range of applications. In particular, the release of basic subatomic particles (i.e. electron, proton and neutron) in an atom (ionization process) and the synthesizing of molecules to form ions or other molecules are among those reactions that necessitate large amount of instantaneous power. In addition to the decomposition process, there have recently been requests for pulsed power in other areas such as in the combination of molecules (i.e. fusion, material joining), gessoes radiations (i.e. electron beams, laser, and radar), explosions (i.e. concrete recycling), wastewater, exhausted gas, and material surface treatments. These pulses are widely employed in the silent discharge process in all types of materials (including gas, fluid and solid); in some cases, to form the plasma and consequently accelerate the associated process. Due to this fast growing demand for pulsed power in industrial and environmental applications, the exigency of having more efficient and flexible pulse modulators is now receiving greater consideration. Sensitive applications, such as plasma fusion and laser guns also require more precisely produced repetitive pulses with a higher quality. Many research studies are being conducted in different areas that need a flexible pulse modulator to vary pulse features to investigate the influence of these variations on the application. In addition, there is the need to prevent the waste of a considerable amount of energy caused by the arc phenomena that frequently occur after the plasma process. The control over power flow during the supply process is a critical skill that enables the pulse supply to halt the supply process at any stage. Different pulse modulators which utilise different accumulation techniques including Marx Generators (MG), Magnetic Pulse Compressors (MPC), Pulse Forming Networks (PFN) and Multistage Blumlein Lines (MBL) are currently employed to supply a wide range of applications. Gas/Magnetic switching technologies (such as spark gap and hydrogen thyratron) have conventionally been used as switching devices in pulse modulator structures because of their high voltage ratings and considerably low rising times. However, they also suffer from serious drawbacks such as, their low efficiency, reliability and repetition rate, and also their short life span. Being bulky, heavy and expensive are the other disadvantages associated with these devices. Recently developed solid-state switching technology is an appropriate substitution for these switching devices due to the benefits they bring to the pulse supplies. Besides being compact, efficient, reasonable and reliable, and having a long life span, their high frequency switching skill allows repetitive operation of pulsed power supply. The main concerns in using solid-state transistors are the voltage rating and the rising time of available switches that, in some cases, cannot satisfy the application’s requirements. However, there are several power electronics configurations and techniques that make solid-state utilisation feasible for high voltage pulse generation. Therefore, the design and development of novel methods and topologies with higher efficiency and flexibility for pulsed power generators have been considered as the main scope of this research work. This aim is pursued through several innovative proposals that can be classified under the following two principal objectives. • To innovate and develop novel solid-state based topologies for pulsed power generation • To improve available technologies that have the potential to accommodate solid-state technology by revising, reconfiguring and adjusting their structure and control algorithms. The quest to distinguish novel topologies for a proper pulsed power production was begun with a deep and through review of conventional pulse generators and useful power electronics topologies. As a result of this study, it appears that efficiency and flexibility are the most significant demands of plasma applications that have not been met by state-of-the-art methods. Many solid-state based configurations were considered and simulated in order to evaluate their potential to be utilised in the pulsed power area. Parts of this literature review are documented in Chapter 1 of this thesis. Current source topologies demonstrate valuable advantages in supplying the loads with capacitive characteristics such as plasma applications. To investigate the influence of switching transients associated with solid-state devices on rise time of pulses, simulation based studies have been undertaken. A variable current source is considered to pump different current levels to a capacitive load, and it was evident that dissimilar dv/dts are produced at the output. Thereby, transient effects on pulse rising time are denied regarding the evidence acquired from this examination. A detailed report of this study is given in Chapter 6 of this thesis. This study inspired the design of a solid-state based topology that take advantage of both current and voltage sources. A series of switch-resistor-capacitor units at the output splits the produced voltage to lower levels, so it can be shared by the switches. A smart but complicated switching strategy is also designed to discharge the residual energy after each supply cycle. To prevent reverse power flow and to reduce the complexity of the control algorithm in this system, the resistors in common paths of units are substituted with diode rectifiers (switch-diode-capacitor). This modification not only gives the feasibility of stopping the load supply process to the supplier at any stage (and consequently saving energy), but also enables the converter to operate in a two-stroke mode with asymmetrical capacitors. The components’ determination and exchanging energy calculations are accomplished with respect to application specifications and demands. Both topologies were simply modelled and simulation studies have been carried out with the simplified models. Experimental assessments were also executed on implemented hardware and the approaches verified the initial analysis. Reports on details of both converters are thoroughly discussed in Chapters 2 and 3 of the thesis. Conventional MGs have been recently modified to use solid-state transistors (i.e. Insulated gate bipolar transistors) instead of magnetic/gas switching devices. Resistive insulators previously used in their structures are substituted by diode rectifiers to adjust MGs for a proper voltage sharing. However, despite utilizing solid-state technology in MGs configurations, further design and control amendments can still be made to achieve an improved performance with fewer components. Considering a number of charging techniques, resonant phenomenon is adopted in a proposal to charge the capacitors. In addition to charging the capacitors at twice the input voltage, triggering switches at the moment at which the conducted current through switches is zero significantly reduces the switching losses. Another configuration is also introduced in this research for Marx topology based on commutation circuits that use a current source to charge the capacitors. According to this design, diode-capacitor units, each including two Marx stages, are connected in cascade through solid-state devices and aggregate the voltages across the capacitors to produce a high voltage pulse. The polarity of voltage across one capacitor in each unit is reversed in an intermediate mode by connecting the commutation circuit to the capacitor. The insulation of input side from load side is provided in this topology by disconnecting the load from the current source during the supply process. Furthermore, the number of required fast switching devices in both designs is reduced to half of the number used in a conventional MG; they are replaced with slower switches (such as Thyristors) that need simpler driving modules. In addition, the contributing switches in discharging paths are decreased to half; this decrease leads to a reduction in conduction losses. Associated models are simulated, and hardware tests are performed to verify the validity of proposed topologies. Chapters 4, 5 and 7 of the thesis present all relevant analysis and approaches according to these topologies.

The Constitution Truss Spar, operated by Anadarko Petroleum Corporation (APC), is located in Green Canyon Block 679 and 680 in a water depth of 1,500 m. It was installed in October of 2006 and has since weathered multiple hurricanes and other storms. The platform is equipped with an Environmental Platform Response Monitoring System (EPRMS) which records real-time motions, environmental parameters and loads. These measurements were used to hind-cast the platform mooring tensions and estimate fatigue damage index accrued over the short life (install to start of study, July 2010) of the platform. The study found that extreme events such as Hurricane Ike (~100 yr storm) accounted for considerably higher fatigue damage index than the total caused by other small storms likely to occur in the 20 year service life of the vessel. It is therefore a recommendation of this study that a design criterion for fatigue damage accrued during extreme events such as 100 yr hurricanes be considered in the design of station keeping systems in a similar manner to the guidelines found in API RP 2T (2010) for design of tension leg platforms.

碩士<br>中華大學<br>土木與工程資訊學系(所)<br>96<br>ABSTRACT The spur dikes were used at the flow constraint and flow velocity decelerates of river. That could protect the corroded river bank or avert the destruction of river bank which is in front of bulkhead base. The permeable spur dikes will be used in the future. That is difficult to design and complicated to analyze. In this study, we model the models of different permeable spur dikes which included, and use the ANSYS CFX to simulate flow field near spur dikes in river. This software can slow the changes of flow field, flow velocities and pressures at three-dimensional mathematical models. First we will set permeable spur dikes on straight channel bed, and compare the variation of flow and pressures of different collocations. That result will compare with experiment data to check the accuracy of program. We are solved the simple flow field structure and pressure distribution by modeling three-dimensional mathematical models and simulating with ANSYS CFX. The result shows that the ANSYS CFX is accurately at simulating flow field and wall shear stress of permeable spur dikes. It can find out that the area will be deposited and eroded in river. We hope the data of study could be consulted on design of spur dikes and river regulation, and anticipate the variation of flow field in river after dikes construction.That will build the ecological environment for waterbeings with spur dikes structure safety. Keyword：the permeable spur dike、ANSYS CFX、flow field、wall shear stress

碩士<br>國立交通大學<br>土木工程系所<br>102<br>In this study, three-dimensional computational fluid hydrodynamics software, FLUENT, is adopted to simulate the flow passing through two groynes in a channel. By simulation, we find the flow characteristics and the distribution of three-dimensional flow pattern and vorticity in the spur-dike region. The model applies the finite volume discrete control equation, the second-order upwind scheme discretization advection term and the SIMPLE method coupled velocity and pressure to satisfy the mass conservation and momentum conservation. Also, the model uses the K-ε turbulent model and volume of fluid method to simulate the three-dimensional flow and its free surface, respectively. Using mesh preprocessor, the model has a grid system composed of hexahedron and tetrahedron mixed meshes with total number of cells approximate 200 thousand are generated in this study. The model simulates three cases with different conditions of groyne length, groyne spacing and inflow velocity. By regression, we obtain the relational formula between three variables and both vortex length and distribution of velocity around groyne. Using FLUENT model, we can obtain the local phenomenon that is difficult to measure.

碩士<br>雲林科技大學<br>機械工程系碩士班<br>98<br>Non-contact magnetic gears have gained significant attention due to no mechanical fatigue, no lubrication, reduced maintenance, improved reliability, overload protection, physical isolation between input and output shafts, and potential for very high efficiency. The purpose of this work is to study the three-dimensional magnetostatic field analysis of magnetic spur gear pairs. First, a detailed literature review regarding several kinds of magnetic gears for the last three decades is presented. Next, the three-dimensional magnetostatic field analysis of a magnetic spur gear pair is proposed with the aid of the current aheet model. The drag torques of an external magnetic gear pair and an internal magnetic gear pair are further calculated. Finally, the validity of the air gap flux density and the drag torque are verified by the finite-element method.

Vancouver Island, British Columbia, is at the northern extent of natural climate zones conducive for grape growing, making vineyards susceptible to any changing weather patterns and temperature extremes. Grapevine monitoring is an important aspect of the viticulture industry, and remote sensing technologies are a powerful aid in reporting vegetation information for better vineyard management practices. However, the understanding of vine spectral responses as viewed by optical sensors has to be developed further, and was undertaken in this study. Chlorophyll pigments drive photosynthesis, a biochemical process in plants, which contributes to physiological performance and productivity, making it an appropriate leaf characteristic for detailed examination. This study aimed to develop a thorough understanding of the relationship between (i) leaf-level spectral reflectance and transmittance properties and (ii) pigment concentrations, via ground-based sampling. This was achieved through the examination of two ground campaign tools, as well as current spectral data processing techniques and workflow methods. A spectrometer and SPAD chlorophyll meter collected nondestructive measurements during leaf senescence and grape harvest, and wet chemical extraction methods determined chlorophyll content (expressed in terms of unit leaf area and leaf fresh weight). Reflectance indices,first order derivative indices, and a continuum removal approach were used to generate eighteen reflectance-based attributes. This study performed a series of chlorophyll estimation models through iterative ordinary least square regression, followed by two methods of model validation. Performance metrics indicated strong models with high explanatory power; the continuum removed depth normalized total area metric was presented as the optimal nondestructive attribute for accurate chlorophyll estimation for leaf level field campaigns (R2 = 0.93). Chlorophyll expressed in units of fresh weight yielded more consistent models than in units of leaf area. The chlorophyll meter also presented compelling results (R2 ≥ 0.78), and both sensors were determined to be appropriate for field validation campaigns for this vineyard study.<br>Graduate

This study is comprised of two separate parts: (1) modeling thermochemical nonequilibrium processes, and (2) flow field simulations of spark-induced plasma. In the first part, the methodology and literature for modeling thermochemical nonequilibrium processes in partially ionized air is presented and implemented in a zero-dimensional solver, termed as NEQZD. The solver was verified for a purely reacting flow case as well as two thermochemical nonequilibrium flow cases. A three-temperature electron-electronic model for thermochemical nonequilibrium partially ionizing air mixture was implemented and demonstrated the ability to capture additional physics compared to the legacy two-temperature model through the inclusion of electronic energy nonequilibrium. In the second part of this work, full scale axisymmetric simulations of the flow field produced by the abrupt heat release of spark-induced plasma were presented and analyzed for two electrode configurations. The heat release was modeled based on data from experiments and assumed that all electrical power supplied to the electrodes is converted to thermal energy. It was found that steeper electrode walls lead to a greater region of hot gas, a stronger shock front, and slightly larger vortices.

Fusion neutrons from high energy density plasmas generated by pulsed laser irradiation of nanoscale atomic clusters have been explored in recent experiments at the University of Texas at Austin. A sufficiently strong (~200 T) magnetic field is expected to produce a magnetized, high temperature (10 keV) plasma with beta [approximately equal to] 1. Such a field along the laser axis may confine the plasma’s radial expansion, thus increasing fusion yield. As part of a multi-stage project to implement this experiment, a scaled (~40 T, ~500 KA) version of the final 200 T, 2.2 MA pulsed power device has been designed and built by Sandia National Laboratories and is now at UT-Austin. This apparatus, named MegaGauss, is meant to serve as a preparation tool for the 200 T system; as such, its current pulse was recorded for analysis, and is compared to a theoretical model to verify its response parameters (e.g. peak current, time to peak). Techniques and results of this comparison are discussed, followed by explanations of basic construction of the 40 T device and current sensing instrumentation. Discussion of MegaGauss is completed with a survey of notable failure modes, and a description of the often severe effects the miniature field-generating Helmholtz coil experiences due to the current pulse and magnetic field. Finally, a novel data archive scheme, structured around the familiar MDSplus archive system, is implemented in Labview and integrated into the main pulsed power control program. Specifically, methods for linking MDSplus’s robust functionality with Labview’s intuitive development environment are realized by means of a specialized software bridge between the two. These methods are used in software that allows MDSplus archives to be written and read exclusively through Labview.<br>text

Tese de mestrado, Ciências Geofísicas (Geofísica Interna), Universidade de Lisboa, Faculdade de Ciências, 2019<br>As margens continentais do tipo rifte são uma das mais complexas entidades geológicas, tendo sido intensivamente estudadas não apenas do ponto de vista académico, mas também pela sua importância económica, devido há ocorrências de recursos geológicos, dos quais o petróleo e o gás natural compõem a grande maioria. Compreender os processos geológicos subjacentes à formação e evolução destes recursos económicos conduziu a academia e a indústria a investigar este tipo de margens. Este estudo tem os seus alicerces nos mais recentes progressos realizados ao nível do conhecimento dos processos de rifting continental e pós-rutura continental da Margem Oeste Ibérica. A aquisição de novos dados de sísmica 3D recolhidos ao largo de Portugal permitiram a descoberta de uma nova e enigmática estrutura geológica localizada a sudoeste do conhecido vulcão de Fontanelas, no promontório submarino, designado por Esporão da Estremadura. Inicialmente, devido à sua assinatura sísmica e semelhanças com o maciço de Sintra, estra estrutura foi associada a uma intrusão magmática de natureza granítica e geometria do tipo batólito. Esta tese propõe a caraterização da natureza magmática e geometria desta intrusão, e do vulcão de Fontanelas, baseada na modelação de dados de campo potencial (isto é, gravimetria e magnetismo) constrangida por dados sísmicos, bem como relacioná-la com o evento magmático pós-rifte do Cretácico Superior. Durante o Mesozóico, a Margem Oeste Ibérica foi pontuada por três ciclos de atividade magmática: 1) ciclo toleítico do Triásico-Jurássico (200-198 Ma), 2) ciclo levemente alcalino do Jurássico-Cretácico (148-140 Ma) e 3) ciclo alcalino do Cretácico Superior (94-69 Ma). Os dois primeiros pulsos magmáticos são associados aos eventos de rifte do Triássico Superior e do Jurássico Superior, respetivamente, sendo, por isso, eventos magmáticos sin-rifte. O último ciclo magmático foi o mais volumoso e generalizado ao longo da Margem Oeste Ibérica, ocorrendo num contexto tectónico pós-rifte. O evento magmático do Cretácico Superior é subdividido em dois pulsos alcalinos, que revelam o papel de uma fonte mantélica sub-listosférica, contrastando com a natureza dos magmas dos ciclos anteriores. As evidências destes dois ciclos magmáticos incluem: 1) sills e diques na região de Lisboa (com cerca de 98 Ma) e 2) o Complexo Vulcânico de Lisboa (72.6 ± 3.1 Ma), os maciços ígneos de Sintra (~79 Ma), Sines (75.4 ± 0.6 Ma) e Monchique (72.7 ± 2.7 Ma). Recentemente, foram também descritos, como parte deste ciclo, o magmatismo associado à montanha submarina Madeira-Tore e à intrusão de Guadalquivir-Portimão, localizada na bacia do Algarve. Este estudo compreende a primeira descrição da intrusão, tendo sido nomeada de acordo com a sua localização, como Intrusão do Esporão da Estremadura (Estremadura Spur Intrusion – ESI). Esta intrusão e o vulcão de Fontanelas são os principais alvos deste trabalho e foram estudados devido à disponibilidade de dados de campo potencial e dados sísmicos recolhidos ao largo de Lisboa, durante duas campanhas sísmicas realizadas em 2008 (2D) e 2010 (3D), respetivamente. Neste estudo, os dados de campo potencial foram constrangidos pela informação dos dados de sísmica 3D. A disponibilidade destes três conjuntos de dados (gravimetria, magnetismo e sísmica) permitiu o acesso a várias fontes de informação, tais como estrutural, pela interpretação dos perfis sísmicos, e física, pela obtenção de valores de densidade e suscetibilidade através da modelação de dados de gravimetria e magnetismo, respetivamente. O uso de dados de campo potencial tem várias vantagens, incluindo o facto de ser um método geofísico passivo e não-destrutivo, a sua aquisição é mais rápida e barato que a maioria dos métodos geofísicos, os dados podem ser adquiridos simultaneamente com outro tipo de aquisições, além das suas múltiplas aplicações, nas quais se incluem, engenharia, ambiental, estudos geotérmicos, entre outros. Por outro lado, a maior desvantagem associada à utilização dos dados de campo potencial está relacionada com a não-unicidade dos resultados, sendo necessárias outras fontes de informação que permitam interpretar e validar os mesmos. Contudo, os dados de campo potencial poderão fornecer uma grande variedade de informação e, pelas suas inúmeras vantagens, serem um dos melhores métodos geofísicos a ser aplicados em áreas conhecidas e desconhecidas. No contexto deste trabalho, a utilização de dados de campo potencial é bastante vantajosa, uma vez que é esperado que os valores de densidade e suscetibilidade das estruturas magmáticas em estudo se destaquem das estruturas de fundo como zonas anómalas, sendo estas facilmente reconhecidas de entre as demais presentes na área de estudo. Numa primeira abordagem, foi realizada uma análise qualitativa dos dados de campo potencial, através de técnicas de processamento do sinal, com o foco na caraterização das principais estruturas geológicas a nível regional. A anomalia da Intrusão do Esporão da Estremadura é representada por uma forma aproximadamente circular, confirmando o contorno obtido pelos dados da sísmica 3D. Por outro lado, o vulcão de Fontanelas exibe uma geometria diferente consoante os dados gravimétricos ou magnéticos. Nos dados gravimétricos a sua geometria é difusa, não expressando uma forma bem definida e espacialmente constrangida, ao contrário dos dados magnéticos, cuja forma é aproximadamente circular. Em ambos os alvos, o sinal geofísico é forte e permite distinguir tanto a ESI como o vulcão de Fontanelas de outras estruturas regionais, revelando a sua importância no contexto da Margem Oeste Ibérica, mas mais importante ainda, na região do Esporão da Estremadura. Subsequentemente, a interpretação regional serviu de base a uma análise local com o objetivo de caraterizar de forma mais detalhada os alvos magmáticos deste estudo. Esta análise foi executada através da modelação 2.5D dos dados de campo potencial, sobre uma linha sísmica que se estende desde o centro da ESI ao flanco sudeste do vulcão de Fontanelas. O principal objetivo da modelação é caraterizar tanto a natureza magmática, como também a geometria de ambas estas estruturas. O vulcão de Fontanelas é caraterizado por uma forma triangular, caraterística dos vulcões, com o flanco sul mais longo e com uma maior extensão em profundidade. Esta estrutura magmática foi subdividida em dois segmentos: uma zona de contacto água-rocha e uma outra zona que se encontra soterrada por sedimentos do Terciário. Os valores de densidade e suscetibilidade determinadas para o setor soterrado (i.e., que não se encontra em contato com a água do mar) permitiram interpretar a sua litologia como um basalto. Por outro lado, o setor que se encontra em contato com a água do mar é caraterizado por valores de densidade e suscetibilidade menores devido à alteração da rocha basáltica original que constitui o vulcão. Esta interpretação corrobora com dados publicados, nos quais se realizou uma dragagem e onde se obtiveram amostras de rocha que permitiram identificar a natureza do vulcão de Fontanelas como um basalto alterado. No que diz respeito à Intrusão do Esporão da Estremadura, a sua geometria foi interpretada como um lacólito (estrutura magmática em forma de folha). Relativamente, à sua afinidade magmática as conclusões não foram tão diretas e claras, no entanto os valores de densidade e suscetibilidade associados à intrusão sugeriram a presença de uma natureza predominantemente gabróica. Os resultados obtidos através da modelação 2.5D, mais concretamente os valores de densidade e suscetibilidade magnética, são semelhantes a corpos magmáticos em onshore (maciços de Sintra e Sines e sill da Foz da Fonte) e offshore da margem do Algarve (intrusão Portimão-Guadalquivir). De acordo com os resultados obtidos neste estudo através da modelação bem como da informação da estratigrafia sísmica e as semelhanças com os análogos presentes na Margem Oeste Ibérica foi possível associar esta intrusão ao evento magmático pós-rifte do Cretácico Superior. Os resultados obtidos têm implicações nos atuais modelos de evolução que descrevem a margem Ibérica, nos modelos magmáticos e respetivos mecanismos de instalação do evento magmático do Cretácico Superior, bem como nos sistemas petrolíferos.<br>Rifted continental margins are one of the most complex geological entities, being intensively studied not only from the academic point of view, but also for their economic importance, due to the occurrence of geological resources, from which oil and natural gas comprise the vast majority. Understanding the geological process that underpin the formation and evolution of these resources led academia and industry, to scrutinize this type of margins. This study is grounded in recent advances in the knowledge of continental rifting and post-breakup of West Iberia, and in the discovery of an enigmatic geological feature located southwest of the Fontanelas volcano. This feature, whose nature and geometry are unknown, was identified based on new 3D seismic data offshore central Portugal, in the Estremadura Spur. Its seismic signature and similarity with the Sintra massif (shape and areal extent), suggest that it might correspond to a magmatic intrusion, with a batholith shape and granitic nature. This feature is described here for the first time therefore it was named as Estremadura Spur Intrusion (ESI). This thesis proposes to characterise the geometry and nature of the Estremadura Spur Intrusion and the Fontanelas volcano, based on potential field data (i.e. gravity and magnetic) modelling supported and constrained by evidence from seismic profiles, and correlate the ESI with the Late Cretaceous post-rift magmatic event. Firstly, a qualitative analysis of potential field data was performed based on signal enhancement techniques, focusing on the characterization of the main regional geological features, in order to frame the area under study. Overall, the gravity and magnetic anomaly associated with the ESI produces a nearly circular shape, confirming its outline from the 3D seismic data. On the other hand, the gravity anomaly of the Fontanelas volcano is more diffuse than the one from the ESI, while its magnetic anomaly it is much better constrained by an approximately circular geometry. Both targets have a strong geophysical signal, being distinguished from other regional features, indicating its importance on the West Iberian Margin and, more significantly, in the Estremadura Spur setting. Subsequently, building on the regional interpretation, a more detailed analysis was performed through 2.5D modelling of potential field data, over a seismic line across the centre of the intrusion and the southeast flank of the Fontanelas volcano, with the aim to characterise both features, including their magmatic nature and geometry. The Fontanelas volcano is characterised by an overall triangular shape, with a longer and deeper southern flank. This magmatic feature was subdivided into two segments: a seawater-rock contact zone and a buried zone, by Tertiary sediments. The density and susceptibility values determined for its buried sector (not in contact with the seawater) were interpreted as basalt. The lower density and susceptibility values associated with the seawater-Fontanelas contact zone are caused by the alteration of its original basaltic rock. This interpretation corroborates with the results of published work on the Fontanelas volcano. Regarding the Estremadura Spur Intrusion, its geometry is interpreted as a laccolith (sheet-like magmatic structure). Although the conclusions regarding its magmatic affinities were not straightforward, the values of density and susceptibility obtained for this magmatic feature suggest the presence of a predominantly gabbroic intrusion, according to similarities, concerning its nature, with outcropping intrusions, such as Sintra and Sines massifs. The seismic stratigraphic interpretation and the similarities between onshore (Sintra and Sines massifs and Foz da Fonte sill) and offshore (Guadalquivir-Portimão intrusion) analogues on the West Iberian Margin, suggest a link between the Estremadura Spur Intrusion and the Late Cretaceous post-rift magmatic event. The results obtained in this thesis may have implications on the current models describing the evolution of the Iberian margin, the existing magmatic models and emplacement mechanisms of the Late Cretaceous magmatic event as well as on petroleum systems.

Thesis (M.S. Aero. E.)--University of Notre Dame, 2009.<br>Thesis directed by R. Mark Rennie and Eric J. Jumper for the Department of Aerospace and Mechanical Engineering. "December 2009." Includes bibliographical references (leaves 62-64).

An investigation of cyclic variability in a single-cylinder spark ignition engine fuelled by natural gas was carried out. The effects of combustion chamber shape and compression ratio were examined intensively. Four different combustion chambers were tested and compression ratio was varied in the range of 8.5:1 to 15:1. For each test condition, the in-cylinder pressure data were recorded at each degree of crank angle rotation for a total of two hundred consecutive engine cycles. These pressure-time histories were used for the detailed study of combustion characteristics. The generalized plot of maximum pressure and location at which maximum pressure occurs was demonstrated as an effective means of diagnosing the cyclic variability. It was shown that compression ratio had negligible effect on cyclic variability, but combustion chamber shape had a strong influence. The indicated mean effective pressure proved to be a good index for measuring cyclic variability for a wide range of operating conditions. However, for specific cases in which the variation of indicated mean effective pressure shows poor sensitivity, maximum pressure and maximum rate of pressure rise are useful measures. For high compression ratio engines, a compact combustion chamber arranged around the spark plug has been shown to be superior for reducing cyclic variability. In addition, a study of a model for the small-scale structure of turbulence using the data from these experiments showed good agreement with those from the literature. Alternative assumptions for estimating turbulence length scale were tested and a preferred method is recommended. The study showed that the fast burning combustion chamber is the solution to reduce cyclic variation. However, cyclic variations of maximum pressure and its location in the fast burning condition still exist and continued research to reduce these cyclic variations should concentrate on the variation of characteristics of flame kernel creation and growth from cycle to cycle.

ABSTRACT Few antibiotics are left that are effective against methicillin-resistant Staphylococcus aureus (MRSA) and even strains resistant to these agents have been isolated. Previous studies have identified five distinct MRSA clonotypes, which are present globally. No comprehensive national study has previously been undertaken to investigate the MRSA types in South Africa, and this study was aimed at elucidating the genotypic population structure of South African MRSA isolates. SmaI digested genomic DNA, separated by pulsed-field gel electrophoresis, was used to characterise 349 S. aureus isolates, obtained from various state and private diagnostic laboratories. PFGE results were complemented with those of spa typing and staphylococcal cassette chromosome mec (SCCmec) typing results. Two-hundred-and-five different PFGE patterns were identified, which were grouped into twenty-four clusters. Three were major lineages, containing more than 20% of the isolates with a similarity cut-off of 70%. Only thirty-seven spa types were identified (fourteen novel spa types), which clustered into six spa-Clonal Complexes after BURP analysis. SCCmec types I-IV were identified, including variants of each type. Data suggest that the Archaic clone (RSA05), oldest of the epidemic clones, represents one of the major clones in South Africa. Strains that were part of this complex (n=98 (28.2%); t064; SCCmec type I-pls) clustered together with strain E2125/ATCC BAA-38 (t051; SCCmec type I). Another major complex, RSA16 (n=90 (25.7%); t012; SCCmec type II/IIB) possessed a single-locus variant (SLV) spa type and the same or a SLV SCCmec types as EMRSA-16 (t018; SCCmec type II). The third major complex, RSA03 (n=74 (21.2%); t037; SCCmec type III/IIIE), had similar spa and SCCmec types to control strainANS46 (t037; SCCmec type III). One MRSA and twelve MSSA isolates were also identified as carrying genes for the toxin Panton-Valentine leukocidin, which was confirmed by DNA nucleotide sequencing.

Title: Impact of spa stay on obesity of older school-aged children. Purpose: Principal purpose of this thesis is to find out and assess the impact of spa stay on obesity of older school-aged children. Methodology: 100 children in the age of 11-15 participated in this inquiry (49 boys, 51 girls, average age 13 years). The children went through the 28-day long reduction treatment in spa facility. At the beginning and end of the therapy the following criteria were assessed: body weight, BMI, volume of body fat, volume of muscle mass, abdominal circumference and tests of agility, endurance and strength (Jacik's motoric test and test of walking for 2 km). During the 4-day treatment the children had the adjusted diet to 5000 KJ, respectively 8000 KJ (by age) and they participated every weekday in group exercise classes and guided walk. Results: The outcomes showed that the spa treatment favourably affected all observed criteria. The decrease of the following criteria of the respondents is statistically significant: body weight decrease (on average by 5,76 kg), decrease of volume of fat tissue (on average 3,36 %) and decrease of abdominal circumference (on average 5,62 cm). At the same time the ratio of children in particular categories of obesity and overweight changed, at the end of the stay, 28,6 %...

Studies on asparagus growth in relation to yield were undertaken in environmentally controlled growth cabinets and in greenhouses. Bud production during the annual growth cycle was also investigated in the field. Growth cabinet experiments showed that increasing the temperature had a significant effect on bud break and relative spear growth rate (RSGR), but although prior chilling had a significant effect on the length of time to bud break at 10°C and 15°C, the effect on RSGR was not so clear. The cytokinin-active compound, N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU), and the naturally occurring cytokinin, zeatin riboside (ZR) significantly stimulated spear elongation. However, spear leaf scale removal reduced spear elongation in the absence and presence of CPPU. CPPU only stimulated spear growth when spear leaf scales were present, indicating that other plant hormones may interact with cytokinins in promoting elongation. The importance of spear growth rate to yield was discussed. In greenhouse experiments, CPPU applied as a foliar spray at 10 or 20 mg L-1 was effective in producing longer and thicker cladodes that might be associated with increased photosynthetic rate. However, photosynthetic rate was unaffected by 10 mg L-1 CPPU treatment. Repeated CPPU applications to foliage reduced net assimilation rate (NAR) compared to untreated controls as determined by growth analysis studies. In asparagus plants, it was difficult to collect xylem sap and further experiments were undertaken with Capsicum annuum. The root exudate of CPPU-treated plants significantly decreased hypocotyl length in the lettuce gibberellin bioassay, suggesting that CPPU blocks gibberellin biosynthesis in roots. However, the application of GA3 to shoots did not reverse growth suppression caused by CPPU-treated roots. Bud production, both in growth cabinets and in open field plantings, started to occur during the spear harvest period in contrast to previously accepted views. During harvest three to four additional buds per cluster were produced in cabinet-grown plants and an average of 51 buds per m2 in field plantings. These results confirm that new bud initiation and development starts to occur during spear harvest, as well as during fern growth and establishment.

The study is focused on comparative ecology of three closely related species from Myosotis palustris group. Importance of various functional traits of individual species was evaluated experimentally in the greenhouse (germination experiments), in the pot experiment and in the reciprocal transplant field experiment. Germination, production of clonal structures and response to various environmental conditions (competition, moisture conditions, etc.) were studied. The experimental data are supplemented with an analysis of phytosociological relationships of the studied species.