Dissertations / Theses on the topic 'Phase accumulation'

Nous avons étudié l'accumulation des protéines en général, et des glutéines en particulier au cours du dévelopement des grains de différents génotypes de blé tendre. Pour ce faire, nous avons utilisé différentes techniques analytiques (chromatographie liquide haute performance d'exclusion stérique ou phase inversée, électrophorèse capillaire et SDS-PAGE 2D). Dand le cadre de cette étude, nous avons démontré que la déshydratation du grain provoquait l'insolubilisation d'une partie des gluténines. A partir de l'analyse de l'évolution de la composition en sous-unités gluténiques des polymères au cours du développement du grain, nous avons également démontré que le rapport SG-HPM/SG-FPM conditionnait l'état d'association des gluténines (proportion des polymères inextractibles au SDS) à la maturité. Grâce à la mise en oeuvre d'un blocage in vitro et in vivo des groupements SH libres protéiques par le mBBr, nous avons démontré que la perte de solubilité des gluténines au cours de la déshydratation était liée à un phénomène d'oxydation. Dans un deuxième temps, nous avons caractérisé la distribution moléculaire des différents polymères gluténiques. Les masses moléculaires moyennes et les rayons de giration moyens de ces polymères ont été mesurés grâce à l'utilisation couplée de la chromatographie liquide d'expulsion stérique (HPSEC) et de la diffusion de lumière (MALLS). Cette étude a montré que la solubilité des gluténines au SDS est plus liée au degré de compacité (réticulation) de ces polymères qu'à leur masse moléculaire. Enfin, les structures polymériques inextractibles au SDS sont caractérisées par un haut degré d'organisation.

The present research project is carried out at the von Karman Institute for Fluid Dynamics (Rhode-Saint-Genèse, Belgium) with the financial support of the European Space Agency.

The first stage of spacecrafts (e.g. Ariane 5, Vega, Shuttle) generally consists of large solid propellant rocket motors (SRM), which often consist of segmented structure and incorporate a submerged nozzle. During the combustion, the regression of the solid propellant surrounding the nozzle integration part leads to the formation of a cavity around the nozzle lip. The propellant combustion generates liquefied alumina droplets coming from chemical reaction of the aluminum composing the propellant grain. The alumina droplets being carried away by the hot burnt gases are flowing towards the nozzle. Meanwhile the droplets may interact with the internal flow. As a consequence, some of the droplets are entrapped in the cavity forming an alumina puddle (slag) instead of being exhausted through the throat. This slag reduces the performances.

The aim of the present study is to characterize the slag accumulation process in a simplified model of the MPS P230 motor using primarily optical experimental techniques. Therefore, a 2D-like cold-gas model is designed, which represents the main geometrical features of the real motor (presence of an inhibitor, nozzle and cavity) and allows to approximate non-dimensional parameters of the internal two-phase flow (e.g. Stokes number, volume fraction). The model is attached to a wind-tunnel that provides quasi-axial flow (air) injection. A water spray device in the stagnation chamber realizes the models of the alumina droplets, which are accumulating in the aft-end cavity of the motor.

To be able to carry out experimental investigation, at first the the VKI Level Detection and Recording(LeDaR) and Particle Image Velocimetry (PIV) measurement techniques had to be adapted to the two-phase flow condition of the facility.

A parametric liquid accumulation assessment is performed experimentally using the LeDaR technique to identify the influence of various parameters on the liquid deposition rate. The obstacle tip to nozzle tip distance (OT2NT) is identified to be the most relevant, which indicates how much a droplet passing just at the inhibitor tip should deviate transversally to leave through the nozzle and not to be entrapped in the cavity.

As LeDaR gives no indication of the driving mechanisms, the flow field is analysed experimentally, which is supported by numerical simulations to understand the main driving forces of the accumulation process. A single-phase PIV measurement campaign provides detailed information about the statistical and instantaneous flow structures. The flow quantities are successfully compared to an equivalent 3D unsteady LES numerical model.

Two-phase flow CFD simulations suggest the importance of the droplet diameter on the accumulation rate. This observation is confirmed by two-phase flow PIV experiments as well. Accordingly, the droplet entrapment process is described by two mechanisms. The smaller droplets (representing a short characteristic time) appear to follow closely the air-phase. Thus, they may mix with the air-phase of the recirculation region downstream the inhibitor and can be carried into the cavity. On the other hand, the large droplets (representing a long characteristic time) are not able to follow the air-phase motion. Consequently, a large mean velocity difference is found between the droplets and the air-phase using the two-phase flow measurement data. Therefore, due to the inertia of the large droplets, they may fall into the cavity in function of the OT2NT and their velocity vector at the level of the inhibitor tip.

Finally, a third mechanism, dripping is identified as a contributor to the accumulation process. In the current quasi axial 2D-like set-up large drops are dripping from the inhibitor. In this configuration they are the main source of the accumulation process. Therefore, additional numerical simulations are performed to estimate the importance of dripping in more realistic configurations. The preliminary results suggest that dripping is not the main mechanism in the real slag accumulation process. However, it may still lead to a considerable contribution to the final amount of slag.

Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Elevated levels of trace elements in the environment are of great concern because of their persistence, and their high potential to harm living organisms. The exposure of aquatic biota to trace elements can lead to bioaccumulation, and toxicity can result. Furthermore, the transfer of these elements through food chains can result in exposure to human consumers. Sea-fill or coastal fill sites are among the major anthropogenic sources of trace elements to the surrounding marine environment. For example, in the Maldives, Thilafushi Island is a sea-fill site consisting of assorted municipal solid waste, with multiple potential sources of trace elements. However, there is limited data on environmental trace element levels in the Maldives, and although seafood is harvested from close to this site, there is no existing data regarding trace element levels in Maldivian diets. Following the Christchurch earthquakes of 2011,

Etablissement des equations de fonctionnement de chacun des elements du circuit solaire comportant: un champ de collecteurs, un accumulateur de chaleur eau/paraffine ou air paraffine et un habistat. Deux modeles numeriques sont proposes pour caracteriser ces deux types d'accumulateur. La modelisation de l'accumulateur eau/paraffine est basee sur l'etude d'un cylindre de reference compose d'un tube a eau entoure d'un volume cylindrique de paraffine. Le systeme d'equations aux derivees partielles deduit a partir d'un maillage longitudinal et radial a ete resolu par la methode des elements finis. Un logiciel de simulation a ete developpe pour le dimensionnement des installations utilisant ce type de stockage

La determination de ces proprietes de cristaux plastiques de la famille des polyols a debouche sur la selection de trois composes organiques : le pentaerythritol, le pentaglycerine et le neopentylglycol, a partir desquels des melanges de solutions solides stables sont possibles. Le niveau de temperature peut etre choisi dans une gamme allant de 25**(o)c a 95**(o)c et de 165**(o)c a 185**(o)c; les enthalpies de transition sont comprises entre 80 kj/kg et 250 kj/kg. Mise en oeuvre avec incorporation de 80% de resines synthetiques en masse. Resultats

This dissertation covers the application of heat accumulation systems in nuclear power engineering, namely in nuclear power plants. It is mainly a case of passive emergency systems, whose task is to accumulate the heat produced in the reactor’s active zone and in spent fuel pools during DBA (design-basis accidents) or beyond DBA. A particular example of heat accumulation is steam condensation after LOCA (loss of coolant accident). The primary circuit steam leakage increases containment pressure and has to be decreased by the steam condensation. This thesis deals with a theoretical substitute for ice condensers, which are used as a passive safety measure in some nuclear power plants. The substitute involves a choice of an alternative material, whose melting temperature (for heat accumulation) is closer to nuclear power plant operating temperatures. The other part of the dissertation discusses heat accumulation in spent fuel pools in case of all cooling systems failure.

Analyse de l'évolution des materiaux et des techniques ainsi que des consequences induites par celles-ci sur la conception du bati. Importance du concept de masse (ou inertie) quant a son influence sur le comportement thermique du batiment vis a vis du rayonnement solaire. Etat des connaissances sur les materiaux presentant un changement de phase, utilisables dans les parois du batiment. Modelisation physique, experimentation sur modeles reduits et a l'echelle 1; methodes numeriques de traitement du signal

Mestrado em Biotecnologia - Biotecnologia Industrial e Ambiental
Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible biopolymers. PHAs emerge as a possible solution as substitutes of petroleum based plastics, being produced under the Biorefinery concept, in which wastes and by-products of numerous industries may be used as carbon source. This project aimed the isolation and characterization of organisms able to store PHAs from Hardwood Sulphite Spent Liquor (HSSL), a by-product of the pulp and paper industry. Isolation was performed from a Mixed Microbial Culture (MMC) selected under feast and famine conditions, using some components present in HSSL as substrates, such as acetic acid and xylose. Five pure isolates able to produce PHAs resulted from the successive streaking in solid medium containing HSSL. The purity of the isolates was evaluated through Gram staining and FISH analysis and the PHAs accumulation by Nile Blue staining. Two strains were identified as Rhohococcus spp. and three as Pseudomonas spp.. One isolate of each genus was selected and further studied in terms of growth and PHAs accumulation capability from three distinct carbon sources (HSSL, acetic acid and xylose). Both isolates, Rhodococcus spp. and Pseudomonas spp., were able to grow and use the three carbon sources as well as to produce PHAs. However, both strains showed a higher maximum specific growth rate (μmax) when HSSL was used as carbon source, 0.212 ± 0.0219 h-1 and 0.251 ± 0.0526 h-1, respectively. A qualitative evaluation of the PHAs accumulation through Nile Blue staining exhibited a higher accumulation when acetic acid was used as sole carbon source. In an attempt to identify some of the species responsible for PHAs accumulation of the selected MMC, belonging to the dominant class, Alphaproteobacteria, a 16S rDNA clone library was constructed. It was possible to identity Novosphingobium spp., Sphingobium spp. and Pleomorphomonas spp.
Polihidroxialcanoatos (PHAs) são biopolímeros biodegradáveis e biocompatíveis. Os PHAs são considerados uma solução possível como substitutos dos plásticos derivados do petróleo, podendo ser produzidos no âmbito do conceito de Biorefinaria utilizando resíduos como fonte de carbono. Este trabalho teve como objectivo o isolamento e a caracterização de bactérias produtoras de PHAs a partir de licor de cozimento ao sulfito ácido (HSSL), um sub-produto da indústria papeleira. Os isolamentos foram realizados partindo de uma cultura mista seleccionada para a acumulação de PHAs por imposição de ciclos de fome e fartura, utilizando alguns dos componentes do HSSL como substrato, nomeadamente a xilose e o ácido acético. Após repicagens sucessivas em meio sólido contendo HSSL, foi possível obter cinco isolados puros capazes de acumular PHAs. A pureza dos isolados foi avaliada através de coloração de Gram e análise FISH e a capacidade de acumulação de PHAs por coloração de Azul do Nilo. Duas estirpes foram identificadas como Rhohococcus spp. e três como Pseudomonas spp.. Um isolado de cada género foi seleccionado e estudado em termos de crescimento e capacidade de acumulação de PHAs, a partir de três fontes de carbono distintas (HSSL, ácido acético e xilose). Verificou-se que ambos os isolados, Rhodococcus spp. e Pseudomonas spp., foram capzes de crescer nos três meios e produziram PHAs. Contudo, ambas as estirpe apresentaram uma taxa específica de crescimento (μmax) superior com HSSL como fonte de carbono, 0.212 ± 0.0219h-1 e 0.251 ± 0.0526h-1 respectivamente. Uma avaliação qualitativa da acumulação de PHAs utilizando coloração Azul do Nilo mostrou uma acumulação maior nos ensaios em que o ácido acético era a única fonte de carbono. Numa tentativa de identificar algumas das espécies responsáveis pela acumulação de PHAs da cultura mista seleccionada pertencentes à classe dominante, Alfaproteobactéria, recorreu-se à construção de uma biblioteca de clones 16S rDNA. Foram identificadas as espécies Novosphingobium spp., Sphingobium spp e Pleomorphomonas spp.

Dans l'optique de produire des agro‐carburants, le sorgho sucré est aujourd'hui proposé comme une alternative à d'autres espèces cultivées à grande échelle comme la canne à sucre et le maïs car il présente plusieurs avantages : le sorgho est résistant à la sécheresse et à la chaleur, il nécessite peu d'intrants, a en moyenne un cycle de culture relativement court (3‐4 mois) comparé à la canne à sucre. Il offre une grande diversité génétique à explorer et exploiter, tout en étant génétiquement moins complexe que la canne à sucre. Finalement, il peut être cultivé pour un double usage, le grain pouvant être utilisé comme source d'alimentation pour l'homme ou le bétail (à partir du grain) et le jus sucré contenu par les tiges comme source d'agrocarburant. Cette polyvalence en fait une culture idéale pour lutter contre la compétition entre cultures énergétiques et cultures vivrières et assurer des rendements dans des environnements de culture sujets au stress hydrique et thermique comme c'est le cas en Afrique de l'Ouest. Cependant, le caractère sucré du sorgho est complexe, car sous l'influence d'interactions Génotype X Environnement (GxE). Aussi, les mécanismes métaboliques, morphologiques ou phénologiques constituant la cinétique d'accumulation des glucides dans la tige et son éventuelle compétition avec le remplissage des grains restent mal connus ou très controversés dans la littérature. La présente thèse, réalisée dans le cadre du projet européen Sweetfuel, vise à comprendre ces mécanismes, afin de contribuer à la définition d'idéotypes de sorgho double usage, pour les environnements soudano‐sahéliens.Sur la base d'études expérimentales au champ au Mali et en serre en France, il a pu être démontré que les glucides sont accumulés dans les entrenoeuds des tiges par un jeu d'activités enzymatiques (favorisant l'accumulation d'hexoses puis de saccharose) dès le début de leur élongation, donc potentiellement avant la floraison. Au Mali, l'étude au champ de 14 génotypes adaptés aux conditions locales, plus ou moins sensibles à la photopériode et semés à trois dates différentes, a démontré le bénéfice d'un rallongement de la phase végétative sur la quantité de sucre accumulée dans les tiges de la plante à floraison, du fait d'un plus grand nombre d'entrenoeuds allongés et du temps à leur disposition pour accumuler des glucides avant ce stade. Ce bénéfice était cependant plus lié à la plus grande quantité de biomasse accumulée (taille des tiges) qu'à la concentration en sucre dans les entrenoeuds (plutôt stable entre dates de semis).Ainsi, la durée de la phase végétative et la sensibilité à la photopériode sont proposés comme des paramètres clés favorisant la quantité de glucides accumulée dans les tiges de la plante à floraison. D'autre part, il a été montré que la quantité de glucides présente à maturité dans les tiges des mêmes génotypes ne différait pas ou peu de celle à floraison, une éventuelle réduction pour quelques génotypes n'étant généralement pas significative et évitable par l'allongement du cycle. De plus, cette quantité de glucides dans les tiges à maturité n'a tiré aucun bénéfice de l'ablation de la panicule à floraison chez les mêmes génotypes. Ces résultats suggèrent que la compétition entre le remplissage du grain et la production de sucre est faible chez le sorgho, d'autant plus faible que la plante présente de grandes tiges et donc un grand compartiment de stockage des glucides, tamponnant cette éventuelle compétition. D'ailleurs, à une échelle plus fine, aucune différence n'a pu être mise en évidence en termes d'activité des principales enzymes du métabolisme carboné dans la tige d'un génotype dans sa version stérile (pas de remplissage du grain) et fertile.Ce travail a démontré le potentiel du sorgho pour une double utilisation dans un contexte soudano‐sahélien et la pertinence d'exploiter la diversité génétique de cette espèce pour cette objectif de sélection. Les résultats ob
Sweet sorghum offers many advantages as an alternative to widely cultivated crops such as corn and sugarcane to produce biofuels: it is resistant to water stress, it requires few inputs; it has a shorter growth cycle compared to sugarcane in particular. Sorghum also exhibits a great genetic diversity and is genetically less complex than sugarcane. Finally, sorghum can be cultivated for dual‐purpose uses, using grains for food or feed and sweet juice for biofuel production. Hence, sorghum is a promising option to reduce the competition for land and (water) resource use between food and fuel, in particular in cropping environments with high drought and heat stress frequency, as in West Africa. However, stem sweetness is a complex trait prone to genotype x environment interactions (GxE). The metabolic, morphological and phenological mechanisms involved in the kinetic of stem sugar accumulation and its possible competition with grain filling are largely unknown or controversial in the literature. The present work is part of the European project Sweetfuel and aims at better understanding these mechanisms and contributing to define dual‐purpose sorghum ideotypes for soudano‐sahelian conditions.Based on field and greenhouse experiments respectively in Mali and France, it was found that sugars start accumulating in stem internodes at the onset of their elongation, i.e. potentially soon before the plant flowers. The successive accumulation of hexose and then sucrose in internodes could be dynamically explained by changes in the activity of key enzymes related to sucrose metabolism. In Mali, a field experiment performed on 14 genotypes, contrasted for photoperiod sensitivity and sown at three planting dates, highlighted the interest of increasing vegetative phase duration to increase sugar yield. This was explained first of all by the higher number of internodes that could expand during a longer vegetative phase, and thus, by the higher production of stem biomass, and, to a minor extent, by the longer time for internodes to mature and accumulate sugar (sugar concentration in the stem was however fairly stable across sowing dates). Also, vegetative phase duration and photoperiod sensitivity can be considered as two key parameters promoting stem sugar content before grain filling. In the same time, it was shown that stem sugar content kept remarkably constant between anthesis and maturity in most of studied genotypes and that the reduction observed for some genotypes was overcome with an early sowing. Moreover, sugar accumulation in the stem between flowering and maturity did not benefit from panicle pruning. These results together suggest that the competition for carbohydrates between stem sugar reserves and grain filling is weak; it is even weaker for big/large stem genotypes with huge sugar reserves in the stem that would buffer a post‐flowering allocation of sugar from the stem to the grains if required. This low competition was confirmed at a finer scale, as no differences were observed in the activity of key enzymes of sucrose metabolism between the sterile and the fertile line of a same genotype.This work demonstrates the potential of sorghum for dual‐purpose in particular for soudano‐sahelian cropping conditions and the interest of using its genetic diversity for this breeding purpose. It provides further knowledge for revisiting the phenotyping strategies to be adopted to investigate the genetic basis of sugar and grain production and their combination. The results are also currently used to improve the way the source‐sink relationships underlying this dual production are formalized in crop and plant models at CIRAD. Such models will be then useful to assist sorghum ideotype exploration for dual purpose

Thesis (MScSportSc)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: There is a lack of research in the sport of field hockey, specifically where monitoring of fatigue and recovery is concerned. The primary aim of the study was thus to monitor the accumulative fatigue and recovery state of elite field hockey players during the different phases of a competitive season. The specific objectives of the study were to determine the changes in heart rate recovery of elite hockey players; to determine the changes in perceptual fatigue; to determine the relationship between players’ perceptions of recovery and stress; and to determine the relationship between the objective and subjective measures of recovery and fatigue over different phases during a competitive season. Elite female hockey players (n = 15) from Stellenbosch University were monitored over 23 weeks. This group comprised of players from the first team (Maties) and second team (VICS) of the club. The following tests were administered: the Heart rate Interval Monitoring System (HIMS) test with the use of SUUNTO heart rate monitors and SUUNTO Team Manager, the Perceptual Fatigue questionnaire (on a weekly basis), and the Recovery-Stress Questionnaire for Athletes (RESTQ-Sport 76) (during each phase of their normal competition cycle). There were a number of significant findings (p<0.05) relating to the aim and objectives of the study. One of the main findings was that there were significant differences between the phases with regard to the measured variables. Players experienced significantly more Fatigue, Lack of Energy and Pressure during the first Competition phase. With regard to the HIMS, players performed the best during the second Competition phase, following the university holidays. Even though not all the differences were statistically significant, collectively the results indicate that these monitoring tools can be used for teams. An added advantage with all three monitoring tools is that each person can be used as their own baseline. In a team setting it gives the coach and support team the opportunity to individualise training programmes and recovery methods.
AFRIKAANSE OPSOMMING: Daar is ‘n tekort aan navorsing in hokkie, en spesifiek in die monitering van vermoeienis en herstel by spelers. Die hoofdoel van die studie was dus om akkumulerende vermoeienis en die hersteltoestand van elite hokkiespelers gedurende verskillende fases van die kompetisie seisoen te monitor. Die spesifieke doelwitte van die studie was om die verandering in hartspoed herstel van die hoë vlak spelers te bepaal; om veranderinge in perseptuele vermoeienis te bepaal; om die verwantskap tussen die spelers se persepsies van herstel en stress te bepaal; om die verwantskap tussen die objektiewe en subjektiewe van herstel en vermoeienis oor die verskillende fases tydens die kompetisie seisoen te bepaal. Elite vroue hokkie spelers (n = 15) van Stellenbosch was oor 23 weke gemonitor. Hierdie groep het uit spelers van die eerste span (Maties) en die tweede span (VICS) van die klub bestaan. Die volgende toetse was uitgevoer: Die Hartspoed Interval Monitering Sisteem (HIMS) toets met behulp van die SUUNTO hartspoed monitors en die SUUNTO span administrasie sisteem; en die Perseptuele Vermoeienis vraelys was op ‘n weeklikse basis voltooi, terwyl die Herstel Stres vraelys vir Sportmense (RESTQ-Sport 76) gedurende elke fase van hul oefensiklus voltooi is. Daar was ‘n aantal betekenisvolle bevindings (p<0.05) wat verband hou met die doel en doelwitte van die studie. Een van die hoof bevindings was dat daar betekenisvolle verskille tussen die fases was met betrekking tot die veranderlikes. Spelers het beduidend meer Vermoeienis, Gebrek aan Energie en Druk gedurende die eerste Kompetisie fase ervaar. Met betrekking tot die HIMS het spelers die beste presteer gedurende die tweede Kompetisie fase, na afloop van ‘n rus periode gedurende die universiteitsvakansie. Hoewel al die verskille nie statisties beduidend was nie, is daar aangedui dat die moniterings instrumente geskik is vir gebruik by spanne. ‘n Verdere voordeel by al drie moniterings instrumente is dat elke persoon as sy eie basislyn kan dien. In ‘n spanopset bied dit aan die afrigter en ondersteuningspan die geleentheid om oefening en herstelmetodes te individualiseer.

L'etat de vie ralentie caracterise la semence orthodoxe des spermaphytes. Cet etat, induit au cours de la maturation, est leve pendant la germination. La biotine est une molecule necessaire a toute forme de vie. Le mecanisme moleculaire determinant l'etat de vie ralentie est encore inconnu. La biotine peut-elle intervenir dans ce phenomene biologique ? cette these tend a le demontrer. La biotine est decrite comme etant le cofacteur d'enzymes catalysant des reactions de carboxylations. Or, dans les cellules de tous les organes de la plante et a tout moment de son cycle, la biotine libre est en exces par rapport a la biotine liee aux carboxylases. La semence mature est l'unique exception. Deuxieme caracteristique de la semence: elle contient une proteine biotinylee specifique, liant la biotine de maniere covalente. Sa masse moleculaire apparente est de 65 kda, d'ou sa denomination de sbp65 pour seed biotinyl protein (proteine de semence). Depourvue d'activite enzymatique a biotine, sa cinetique d'accumulation au cours de la maturation est concomitante avec l'epuisement de la biotine libre des cellules embryonnaires. Elle est localisee dans le cytoplasme, lieu de synthese de la biotine (baldet, 1993). Tout se passe comme si la sequestration de la biotine par sbp65 de maniere physiologique en fin de maturation chez le pois reproduisait le phenotype du mutant bio1 de l'arabette (shellammer et meinke, 1990). Cette mutation letale correspond a une deficience de synthese de biotine qui entraine une interruption precoce du developpement embryonnaire. Ceci suggere que la regulation du niveau de biotine libre, i. E. Celle disponible pour les carboxylases a biotine indispensables a un metabolisme normal, est un mecanisme de modulation de l'activite metabolique globale. D'ou les observations suivantes: sbp65 est degradee aussitot que le metabolisme reprend au cours de la germination et son gene n'est jamais exprime en dehors de l'embryon en fin de maturation. Sbp65 a son equivalent dans les especes agronomique. Au niveau moleculaire, elle presente deux caracteristiques: elle est tres hydrophile et possede plusieurs motifs repetes, ce qui l'apparente au groupe des proteines lea (late embryogenesis abundant i. E. Abondante en fin d'embryogenese). D'autre part, la structure primaire de sa region biotinylee est radicalement differente de celle de toutes les autres proteines a biotine d'ou son absence d'activite enzymatique

Les superalliages monocristallins base Ni sont utilisés pour la conception des aubes de turbines en raison de leur excellente durabilité à haute température. Lors de la production d'une aube de turbine, une déformation plastique (DP)inattendue peut être introduite dans le matériau. Dans cette étude, les matériaux monocristallins ont été pré-déformés entre les traitements thermiques de mise en solution et de revenu pour simuler la DP pouvant être rencontrée lors des étapes de production. Des tests mécaniques sur les matériaux pré-déformés ont été effectués pour comprendre l'effet de cette DP.Au cours des traitements thermiques de revenu du superalliage monocristallin AM1 pré-déformé, un grossissement des précipités γ′ plus rapide et une nucléation accélérée de pores ont été observés à proximité des bandes de glissement introduites lors de la DP à température ambiante. Au cours de la déformation par fluage de l’AM1 pré-déformé dans des conditions de haute température/basse contrainte (≥ 950 °C), les bandes à microstructure grossière sont des sites préférentiels d’accumulation du dommage de fluage induit par diffusion, induisant de la recristallisation et une réduction drastique des propriétés de fluage. Dans des conditions de basse température/haute contrainte (≤ 850 °C), le cisaillement de la microstructure est facilité dans les bandes à microstructure grossière et il réduit également les propriétés de fluage.La recristallisation n'est pas été observée dans des ces conditions de fluage à basse température car les mécanismes diffusifs sont ralentis. Ces résultats ont été confirmés via des essais de fluage sur des matériaux pré-déformés suivant différent chemin de pré-déformation (température, position de la DP dans le cycle thermique…). Le superalliage monocristallin CMSX-4 Plus a été testé de manière similaire à l'AM1 pour comprendre l'effet de la composition chimique. L'effet de la DP sur la microstructure de l'alliage est plus limité pour cet alliage par rapport à celui sur l’AM1. Par conséquent, la pré-déformation n'a pas montré de chute de la durée de vie pour le CMSX-4 Plus à des températures inférieures à 1050 °C. Par contre, pendant le fluage de CMSX-4 Plus à 1150 °C, la pré-déformation a montré un impact spectaculaire sur la durée de vie et la ductilité via les mêmes mécanismes que ceux observés pourl’AM1 à 1050 °C.Afin de régénérer les propriétés des superalliages monocristallins pré-déformés, un traitement thermique de restauration a été ajouté après la DP. Le traitement de restauration a permis de restaurer la microstructure après la DP à température ambiante avec succès, et les propriétés de fluage des matériaux restaurés sont équivalentes à celles de l'AM1 et duCMSX-4 Plus vierges de pré-déformation
Ni-based single crystal (SX) superalloys are used for turbine blade applications because of their high-temperature durability. During the production of a turbine blade, unexpected plastic deformation (PD) can be introduced to the material. In this study, SX materials were pre-deformed in between solution and aging heat treatments to mimic PD during production. Mechanical tests on the pre-deformed materials have been performed to understand the effect of the prior PD.During aging treatments of pre-deformed AM1 SX superalloy, faster coarsening of γ′ precipitates and enhanced void nucleation were observed in the vicinity of slip bands which were introduced by PD at room-temperature. During creep deformation of pre-deformed AM1 at high temperature/low stress conditions (≥ 950 °C), the microstructure coarsened bands act as diffusion induced creep damage accumulating paths, further triggering recrystallization and resulting in drastic reduction of creep properties. At low temperature/high stress conditions (≤ 850 °C), microstructure shearing was facilitated in the microstructure coarsened band and it decreased creep properties. Recrystallization was not observed at lower temperature creep because the diffusion damage was suppressed. These relationships have been explained by creep tests on pre-deformed materials prepared by different pre-deformation temperatures and heat treatment procedures.CMSX-4 Plus SX superalloy was tested similarly to AM1 to understand the effect of the chemical composition. Effect of pre-deformation on alloy’s microstructure was mild in CMSX-4 Plus compared to that in AM1. Therefore, the predeformation did no exhibit large creep life debit in CMSX-4 Plus at temperatures lower than 1050 °C. However, during creep of CMSX-4 Plus at 1150 °C, pre-deformation presented huge impact on creep life and ductility by the same mechanisms as the ones observed for AM1 at 1050 °C.In order to restore properties of pre-deformed SX superalloys, rejuvenation heat treatment was added after PD.Rejuvenation treatment successfully restored microstructure after PD at room-temperature, and creep properties of rejuvenated specimens were shown to be equivalent to that of original AM1 and CMSX-4 Plus without PD

This work deals with frequency generators based on the direct digital synthesis method DDS. Basic principles and attributes of the frequency generator DDS are explained. The text describes parameters influencing and defining a quality of the generated signal. The list of available integrated circuits realizing the direct digital synthesis is mentioned. A construction of the DDS generator with a device AD9954 and the generator control are described. At the end of the work, the function and parameters of the designed generator are verified.

Commercial alkaline accumulators with positive electrode based on nickel hydroxide generally comprise beta modification of the active material at present due to its excellent stabilization of performance during electrochemical cycling. This dissertation refers to a research work accomplished by author, which has been aimed to utilization of alpha nickel hydroxide in alkaline batteries including exploration of possibilities to attain its stability in strong alkali medium of the electrolyte. I have focused my effort to elucidate reasons for its transformation tendency and to find way of their suppression.

Dual-phase (DP) sheet steels are a class of advanced high strength steels which boast a desirable combination of properties for the forming of automotive components, including: high strength, continuous yielding behaviour, and a high initial work hardening rate. The higher strength of DP steels relative to predecessors used to form automotive components allows for a reduction in part gauge, translating to the potential for reduced automobile weight, emissions, and fuel consumption. However, a form of premature failure during component forming known as `shear fracture' has become a prominent challenge to manufacturers' adoption of DP steels. Martensite particles in DP steel microstructures act as nucleation sites for the development of void damage during deformation, resulting in a deleterious effect upon formability and thought to contribute to the observed shear fractures. This dissertation contributes to the overall goal of offering guidance for the improvement of DP steel microstructures for more desirable fracture behaviour. Specifically, the role of non-ferritic phase/constituent (NFP) volume percent and spatial distribution in the accumulation of void damage in DP steels was investigated. Void damage accumulation in ten DP steel microstructural variants tested to failure under near plane-strain deformation was qualified and quantified in three dimensions using an X-ray micro-computed tomography technique. These results were correlated to the microstructural parameters of the variants, which clearly indicated the detrimental effects of NFP banding in DP steels. It was observed that DP microstructures with increased severity of NFP banding (generally aligned in the sheet rolling direction) incurred a reduced strain to failure. Often, microstructural variants with NFP bands aligned transverse to the major loading direction incurred a reduced strain to failure, accumulated a greater number of voids, and exhibited a larger void volume percent than a specimen with oppositely oriented NFP bands. Void damage spatial distribution was generally reflective of the spatial distribution of the most coarse NFP bands through the sheet thickness. In microstructural variants with NFP bands aligned transverse to the major loading direction, accumulated void damage was often observed to be highly elongated in the direction of NFP banding.
Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2011-09-30 11:49:18.645

碩士
國立成功大學
電機工程學系
106
This paper presents a noise tolerable method for FMCW radar systems to detect vital sign under strong reflected interference signals of stationary clutter. By using phase accumulated demodulation, vital sign detection can be demodulated clearly even under existence of strong clutters influence, and noise can be decreased so that the delay-line can be reduced for the compact system implementation. Moreover, the maximum likelihood estimation used to decrease the influence of the clutter. From the measurement results, the measured absolute range has 4.69% error from 0.5 m to 3.05 m in average. Moreover, the vital sign is 2.25% and 1.49% error with stationary clutter interferer 0.75 m and 1.3 m behind the human target.

This thesis presents the analysis, design and characterization of an integrated high-frequency phase-locked loop (PLL) frequency multiplier. The frequency multiplier is novel in its use of a low multiplication factor of 4 and a fully differential topology for rejection of common mode interference signals. The PLL is composed of a voltage controlled oscillator (VCO), injection-locked frequency divider (ILFD) for the first divide-by-two stage, a static master-slave flip-flop (MSFF) divider for the second divide-by-two stage and a Gilbert cell mixer phase detector (PD). The circuit has been fabricated using a standard CMOS 0.18-um process based on its relatively low cost and ready availability. The PLL frequency multiplier generates an output signal at 26 GHz and is the highest operational frequency PLL in the technology node reported to date. Time domain phase plane analysis is used for prediction of PLL locking range based on initial conditions of phase and frequency offsets. Tracking range of the PLL is limited by the inherent narrow locking range of the ILFD, and is confirmed via experimental results. The performance benefits of the fully differential PLL are experimentally confirmed by the injection of differential- and common-mode interfering signals at the VCO control lines. A comparison of the common- and differential-mode modulation indices reveals that a common mode rejection ratio (CMRR) of greater than 20 dB is possible for carrier offset frequencies of less than 1 MHz. Closed-loop frequency domain transfer functions are used for prediction of the PLL phase noise response, with the PLL being dominated by the reference and VCO phase noise contributions. Regions of dominant phase noise contributions are presented and correlated to the overall PLL phase noise performance. Experimental verifications display good agreement and confirm the usefulness of the techniques for PLL performance prediction. The PLL clock multiplier has an operational output frequency of 26.204 to 26.796 GHz and a maximum output frequency step of 16 MHz. Measured phase noise at 1 MHz offset from the carrier is -103.9 dBc/Hz. The PLL clock multiplier core circuit (VCO/ILFD/MSFF Divider/PD) consumes 186 mW of combined power from 2.8 and 4.3 V DC rails.
Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2009-04-24 11:31:35.384

碩士
國立中正大學
電機工程研究所
105
The radar-based positioning technology designed for the minimally invasive surgical instrument guiding is presented in this thesis. It is designed using the frequency modulation continuous wave radar system with a newly proposed algorithm to achieve the mm-scale positioning accuracy. According to the traditional FMCW radar theory, the range resoulation is limited by frequency sweeping bandwidth. This study focuses on a new theory of phase segmentation accumulation to overcome this issue. In order to achieve multi-target positioning, the binary phase shift keying (BPSK) is applied in tag modulation. Further mahthematical analysis of BPSK is also given in this work. The proposed radar system consists of a commercial 24 GHz programmable millimeter wave transceiver module and a frequency modulation PLL module, An extrenalit power amplifier is added to increase the signal power as well as the detecting range. The signal acquisition and signal processing is performed using NI – LabVIEW. In the experimental demonstrations, both metal plane and BPSK tag are employed as the targets. The results show that the range resoulation can be dramatically improved from 18.75 cm (limited by to 400MHz sweeping bandwidth) to 17.3 μm.

碩士
高苑科技大學
化工與生化工程研究所
100
Polyhydroxyalkanoates (PHAs), one of the biodegradable biosynthetic polymers were function as carbon and energy reservoirs in numerous bacteria. They were known to accumulate inside the bacteria usually when carbon source is excess and one else essential growth nutrient is limited. Shift-down, a temporary unbalanced bacteria culture method established by simple dilution culture procedure can equivalently induce the PHAs accumulation. A temporary unbalanced bacteria growth phenomenon established by shift-down culture procedure was applied to screening PHAs accumulating environment bacteria isolates. The culture method was applied to test PHAs accumulating in standard and environment bacteria isolates. Despite the typical limiting nutrient or C/N ratio, PHAs accumulation seems to be common in bacteria applied of the culture method. This result shown that the shift-down culture method is simple and broad spectrum in screening environment bacteria to find new industry available PHAs produced candidates. The products were characterized as PHB in recovery of Pseudomonas sp. and Bacillus sp.0.03 g/L and 0.07g/L respectively.

碩士
國立臺灣大學
生物環境系統工程學研究所
100
The purpose of this study was to determine the distribution and accumulation of arsenic (As) among aqueous, solid, and plant phases in the Guandu Wetland of Taiwan. Chemical compounds and isotopic compositions in porewater samples of dry season and mineral compositions in the sediment samples of wet season were analyzed to characterize the As distribution with depth. Arsenic concentrations in plant samples were analyzed to assess the translocation factor (TF) and bioconcentration factor (BCF), and to understand the distribution and accumulation of As in the plant, solid, and liquid phases. Chemical compounds concentration were applied the factor and cluster analyses in porewater samples to delineate the vertical profile of oxidation zone (shallow layer), buffer zone (mid layer), and reduction zone (deep layer); and to elucidate the mechanism of As possible mobile in each zone. As-bearing minerals were not found in all sediment samples by using X-ray diffraction (XRD). However, the result of As species transformation indicated mild As(V) (arsenate) shifting to As(III) (arsenite) in the deep layer by X-ray absorption near-edge structure (XANES) of X-ray absorption spectra (XAS). The results implicate that reduction gradient was tended to increase with depth in this wetland systems. The cluster analysis was applied to determine the boundary of shallow zone and deep zone using isotopic compositions data of the sediment samples. The high values of sulfur isotope fractionation factor (ε) occurred in deep zone which was caused by the bacterial sulfate reduction. The results of sulfur isotope indicate that the source of water in shallow zone and deep zone are mainly from mixing of the seawater/surface water and Batou groundwater, respectively. Kandelia obovata is one of the most dominant plant species in mangrove ecosystems of the study area. In this study, As concentrations in plants (23.69 mg/kg) were higher than in the surrounding water (0.0018 mg/L) and soils (17.24 mg/kg). The order of arsenic concentration in various plant tissues at maturity was as follows: roots (19.74 mg/kg) > stems (1.76 mg/kg) > leaves (1.71 mg/kg) > seedlings (0.48 mg/kg), suggesting a high accumulation in the roots. The low translocation factors (TFstems/roots= 0.088, TFleaves/roots= 0.088 and TFseedlings/roots= 0.024) indicate that the translocation of As in various plant tissues is extremely low depending on salt tolerance mechanism of K. obovata. The significant tidal effects result in high BCFplant/water that the As concentrations in wetland water is diluted by seawater. A high BCFplant/soil (BCFplant/soil> 1) between plants and soil indicates that the uptake and bioaccumulation of As in K. obovata are significant; therefore, K. obovata is an As accumulator. The uptake mechanism of plants might depend on the formation of As-contained iron oxides in the root zone, causing the uptake of As in plants to be from soil.

Low noise low division 2 GHz RF synthesizer integrated circuits (ICs) are conventionally implemented in some form of HBT process such as SiGe or GaAs. The research in this dissertation differs from convention, with the aim of implementing a synthesizer IC in a more convenient, low-cost Si-based CMOS process. A collection of techniques to push towards the noise and frequency limits of CMOS processes, and possibly other IC processes, is then one of the research outcomes. In a synthesizer low N-divider ratios are important, as high division ratios would amplify in-band phase noise. The design methods deployed as part of this research achieve low division ratios (4 ≤ N ≤ 33) and a high phase comparison frequency (>100 MHz). The synthesizer IC employs a first-order fractional-N topology to achieve increased frequency tuning resolution. The primary N-divider was implemented utilising current mode logic (CML) and the fractional accumulator utilising conventional CMOS. Both a conventional CMOS phase frequency detector (PFD) and a CML PFD were implemented for benchmarking purposes. A custom-built 4.4 GHz synthesizer circuit employing the IC was used to validate the research. In the 4.4 GHz synthesizer circuit, the prototype IC achieved a measured in-band phase noise plateau of L( f ) = -113 dBc/Hz at a 100 kHz frequency offset, which equates to a figure of merit (FOM) of -225 dBc/Hz. The FOM compares well with existing, but expensive, SiGe and GaAs HBT processes. Total IC power dissipation was 710 mW, which is considerably less than commercially available GaAs designs. The complete synthesizer IC was implemented in Austriamicrosystems‟ (AMS) 0.35 μm CMOS process and occupies an area of 3.15 x 2.18 mm2.
Dissertation (MEng)--University of Pretoria, 2010.
Electrical, Electronic and Computer Engineering
unrestricted

O presente trabalho teve como objetivo o acompanhamento e a observação da fenologia de 5 cultivares de oliveiras tradicionais portuguesas: Azeiteira, Blanqueta, Carrasquenha de Elvas, Cobrançosa e Galega vulgar, em olivais situados em Elvas, Campo Maior e Monforte. O estudo decorreu no ano agrícola 2016/2017 e teve por base 7 olivais, cada olival com 5 pontos de observação, 4 árvores por ponto de observação, totalizando 20 árvores por cultivar/olival. O período de floração iniciou-se a 22 de abril na cultivar Azeiteira (Monforte) e teve uma duração de 21 dias. Por sua vez, a ultima cultivar a iniciar a floração foi a Carrasquenha de Elvas, a 5 de maio, com duração de 15 dias. Na caracterização das cultivares em estudo, e tomando o período de acumulação de temperaturas e a duração térmica contabilizados a partir de 1 de janeiro até à primeira observação do estado 75 da escala BBCH, a análise multivariada permitiu dividi-las em 2 grupos. O grupo 1, constituído pela cultivar Cobrançosa em Elvas e em Monforte, e pela cultivar Carrasquenha de Elvas em Campo Maior, evidenciou maiores necessidades de acumulação de graus-dia de crescimento, demonstrando terem um ciclo mais tardio. O grupo 2, formado pelas cultivares Azeiteira (Campo Maior e Monforte), Blanqueta e Galega vulgar, apresentou maior precocidade, tendo registado menores necessidades de acumulação de graus-dia de crescimento. A taxa de vingamento foi mais elevada nas cultivares Cobrançosa (Elvas) e Galega vulgar (Monforte), com valor de 5,7 e mais baixa na cultivar Carrasquenha de Elvas (Campo Maior), com valor de 4,0. Os resultados obtidos demonstram existir variabilidade entre as cultivares em estudo, o que é muito importante para fazer face às alterações climáticas. No entanto, para confirmar o comportamento diferenciado das cultivares usadas neste estudo é necessário repetir por mais campanhas esta avaliação
The goal of this study was to monitor and observe the phenological phases of five cultivars of traditional Portuguese olive trees: Azeiteira, Blanqueta, Carrasquenha of Elvas, Cobrançosa and Galega vulgar, in olive groves located in Elvas, Campo Maior and Monforte. The study was conducted in the agricultural year of 2016/2017 and was based on 7 olive groves, each olive grove with 5 observation points, 4 trees per observation point resulting in 20 trees varieties/olive grove. The flowering period started on april, 22nd, for the Azeiteira cultivar (Monforte) and lasted 21 days, whereas the last cultivar to start flowering was Carrasquenha of Elvas, on May 5th, with a duration of 15 days. Multivariate analysis of the cultivars was performed during the period of accumulation of temperatures/thermal duration. This period initiated on January, 1st, and lasted until the first observation of state 75 of the BBCH scale. Results show 2 significantly different groups. Group 1, constituted by the Cobrançosa cultivar, in Elvas and Monforte, and the cultivar Carrasquenha in Campo Maior, showed plants with greater accumulation needs of growth degree-days demonstrating to have a later cycle. Group 2, formed by cultivars Azeiteira (Campo Maior and Monforte), also Blanqueta and Galega vulgar, presented plants with a higher precocity which had lower accumulation needs of growth degree-days. The persistent fruit rate scale, ranging from 1 to 6, was highest for both Cobrançosa (Elvas) and Galega (Monforte) cultivars, with a value of 5,7 and lowest for Carrasquenha (Campo Maior), with a value of only 4,0. Results show heterogeneity among the cultivars studied, which is very important to cope with climate changes. However, further investigation is necessary in order to confirm these findings and deepen our understandings of each individual behaviour.

Ziel der vorgestellten Arbeit war die Synthese von Nucleolipiden zur Lipophilisierung von Oligonucleotiden sowie deren Untersuchung im Hinblick auf ihre Wechselwirkung und Duplex-Bildung an horizontalen Lipidmembranen und verschiedenen Phasengrenzen zur Entwicklung eines neuartigen Bio-Chips für die RNA/DNA-Analyse. Mit der Synthese N(3)-prenylierter und 2’,3’-O-ketalisierter Pyrimidinbasen Uridin und Methyluridin wurden Nucleolipid-Bausteine dargestellt, die auch als terminale Kopfgruppen eines Oligonucleotid-Dodecamers den lipophilen Charakter dieser Oligonucleotid-Sequenz erhöhten. Für den Einsatz solcher LONs (Lipo-Oligonucleotide) in einer vereinfachten RNA/DNA-Analytik wurde eine Vielzahl von Lipo-Oligonucleotiden mit diversen Nucleolipid-Kopfgruppen synthetisiert und auf ihr Einlagerungsverhalten in künstliche Lipid-Bilayer untersucht. Fluoreszenz-spektroskopische Untersuchungen zeigten, dass alle Lipo-Oligonucleotide in der Lage sind, sich in künstliche Lipid-Bilayer einzulagern. Abhängig von der Struktur, der Länge und der Anzahl der C-Atom-Ketten dieser lipophilen Anker-Bausteine wurden die Geschwindigkeit und die Festigkeit der Verankerung im Lipid-Bilayer beeinflusst. Des Weiteren wurde die Hybridisierung von LONs mit komplementären Oligomeren an Lipidmembranen untersucht. Es konnte gezeigt werden, dass die im Bilayer verankerten Lipo-Oligonucleotide mit komplementären Oligomeren DNA-Duplexe bilden. Die hybridisierte DNA wurde nicht nur über einen kovalent gebundenen Cy5-Fluorophor am Gegenstrang nachgewiesen, sondern auch über den DNA-Interkalator SYBR Green I (SG). Am Beispiel von zwei Lipo-Oligonucleotiden (LON 20 und 23), die sich schnell und fest in der Bilayermembran verankern, konnte eine spontane Akkumulation dieser LONs an CHCl3/H2O sowie H2O/n-Decan Grenzflächen direkt nach der Probenzugabe beobachtet werden. Diese und andere Ergebnisse stützen den Einsatz von Lipo-Oligonucleotiden als Ziel-Oligomere in einem neuartigen RNA/DNA-Nachweisverfahren an Phasengrenzen.