This diploma thesis deals the formation of water hammer in pipes and the suppress the nega-tive effects especially for the use of protective devices (surge tank, air chamber, air valve and other). The special attention is paid to the use of the air valve, for which it was developed mathematical model. The solution is based on the use of numerical methods Lax-Wendroff with boundary conditions for the air valve.The numerical results are confronted with the ex-periment in conclusion.

L’incidence de l’ischémie critique est en augmentation depuis ces vingt dernières années. La revascularisation diminue le taux d’amputation. Les plaies ischémiques infectées avec l’exposition des tendons, des os ou des articulations, ne peuvent pas cicatriser avec la revascularisation et le débridement local. La chirurgie, associant un pontage veineux distal ou une recanalisation et un lambeau libre, permet de traiter les pertes de substances et présente un avantage hémodynamique en augmentant le débit du pontage grâce au lit vasculaire ajouté par le lambeau. Nous proposons une nouvelle technique chirurgicale basée sur l’utilisation d’une unité anatomique unique, le lambeau-pontage épiploïque (LPE). Il est composé d’un axe artériel, l’artère gastroépiploïque (AGE), qui procure le greffon, et du grand épiploon, utilisé comme lambeau irrigué par une ou plusieurs branches épiploïques. Le but de ce travail était d’analyser la faisabilité anatomique d’un LPE et de valider le scanner pour l’évaluation préopératoire de l’AGE. Nous avons également évalué les effets hémodynamiques de cette technique et analysé la première expérience clinique. 100 dissections anatomiques ont été réalisées afin de mesurer les diamètres et les longueurs de l’AGE droite et de ses branches, ainsi qu’une radiographie après injection de produit radio-opaque. Pour évaluer la faisabilité préopératoire, nous avons étudié 30 tomodensitométries. Nous avons également exploré les effets hémodynamiques dans le modèle porcin. Notre étude anatomique confirme la faisabilité d’un LPE. La longueur moyenne de l’AGE est de 24,5 cm. Le diamètre proximal moyen est de 3 mm et celui distal est de 1,5 mm. Les données de l’étude radiologique montrent que le scanner peut être utilisé pour le repérage préopératoire de l’AGE et la faisabilité d’un LPE. Les mesures hémodynamiques ont montré que, grâce au lambeau épiploïque, le débit sanguin du pontage augmente et que les résistances distales diminuent. Le LPE est une technique chirurgicale qui doit permettre de repousser les limites de sauvetage de membre dans les conditions de cette pathologie extrême, réalisant une revascularisation distale et une couverture simultanée des pertes de substances chez les patients atteints d’artériopathie. / The incidence of critical limb ischemia increases with the ageing of the population. Often, revascularization decreases the rate of amputation. In some cases, infected wounds with exposure of the tendons, bones or articulations will not heal only with revascularization and local debridement. Surgery combining a distal venous bypass or recanalisation and a free flap can treat those wounds, the vascular bed added by the flap improve the hemodynamic and increases the flow in the bypass. We proposed a new surgical method based on the use of a single anatomical unit, the epiploic flow-through flap (FTF), the gastroepiploic artery (GEA) as the vascular substitute and the greater omentum as the flap. The aim of this work was to analyze the anatomical feasibility of an epiploic BF, and to validate CT scan for preoperative assessment of the suitability of the GEA. We also aimed to evaluate the hemodynamic effects of this technique and to analyze the first clinical experience. 100 anatomical dissections were performed in order to measure the diameters and the lengths of GEA and its branches. An extensive X-ray study was also carried out with injection of a radiopaque product. To evaluate preoperative feasibility of the omental FTF, we studied radiological properties of the GEA on 30 routine CT scans. Finally, we also explored the hemodynamic behavior of this artery and its related flap in porcine models. Our anatomical study confirms the feasibility of a FTF. The average available length of GEA is 245 mm. The average proximal diameter is 3 mm and the distal one is 1.5 mm. Data of radiological study show that CT scan can be used to indicate GEA suitability for an epiploic FTF. The hemodynamic measures showed that thanks to the flap, the blood flow increase in the bypass. Ultimately,we report our first clinical application of the omental FTF for distal lower limb revascularization combined to wound coverage, with successful outcome. Epiploic FTF is a surgical technique, which allows distal revascularization and a simultaneous cover of the limb extremity. This technique can be useful in patients requiring a distal revascularization associated with the coverage of large the wounds

Ziel der Arbeit war eine möglichst umfassende Analyse der Nahrungsbedingungen von D. galeata unter Berücksichtigung der damit verbundenen Strategien der Daphnien zur Optimierung des Nahrungserwerbs, um den Einfluß dieser Faktoren bezüglich des Auftretens einer Sommerdepression der Daphnien zu beurteilen. Aufbauend auf den bereits vorhandenen Kenntnissen aus der Literatur sollte dazu im Rahmen der Arbeit festgestellt werden, ob morphologische Veränderungen des Filtrationsapparates der Daphnien (Ausbildung großer, hydrodynamisch dichter Filter), die als Reaktion auf die geringen Nahrungsmengen im Klarwasserstadium auftreten, bei einer drastischen Erhöhung der Nahrungskonzentration zu einer "Überlastung" der Filterbeine der Daphnien, zu hohen Energieausgaben und schließlich zu erhöhter Mortalität (Sommerdepression) führen können. Hauptziel war dabei die Klärung der Frage, ob bottom-up gesteuerte schnelle Veränderungen im Nahrungsangebot, wie sie für geringe bottom-up Limitation (Hypertrophie) typisch sind, eine erhöhte Mortalität bei Daphnien hervorrufen können. Die Beantwortung dieser Fragestellung ist wichtig, um die Effizienz der top-down Steuerung (Biomanipulation) als ökotechnologische Maßnahme zur Gewässersanierung zu erhöhen. Dazu wurden in der biomanipulierten Talsperre Bautzen in drei Untersuchungsjahren (1997 - 1999) wichtige bottom-up wirkende Steuerfaktoren der Daphnienentwicklung sowie morphologische Charakteristika der Filterkämme und physiologische Leistungskriterien von D. galeata vor und während der Zeit des potentiellen Auftretens einer Sommerdepression untersucht. Aus den Ergebnissen ließ sich ableiten, daß das Zusammenspiel der vielfältigen Anpassungsmöglichkeiten der Daphnien in einem bestimmten Variationsbereich der Steuerfaktoren eine erfolgreiche Strategie zur Optimierung der Nahrungsaufnahme darstellen kann. Werden jedoch bestimmte Schwellenwerte über- oder unterschritten, ist eine Kompensation durch die Anpassungsstrategien nicht oder nur bedingt möglich. Dabei kann durch verschiedene Ursachen der gleiche Effekt (Mortalität adulter Daphnien) auftreten, was die Interpretation erschwert. Dieser Effekt wird besonders bei adulten Daphnien durch die gegenüber juvenilen Daphnien höheren Filterwiderstände und die damit verringerte effektive Energieaufnahme begünstigt. Erst wenn ungünstige Nahrungsbedingungen und die am Ende der Klarwasserphase beobachteten ungünstigen Konstellationen der Filterkämme zusammentreffen (timing), tritt die erhöhte Mortalität adulter Daphnien auf. Die Ergebnisse der Untersuchungen unterstreichen damit die Bedeutung von Ganzsee-Experimenten und die möglichst simultane Erfassung verschiedener Zustandsgrößen, um eine umfassende Kausalanalyse der Sommerdepression der Daphnien zu ermöglichen, zu der die vorliegende Arbeit einen Beitrag liefert. Für den Erfolg der Biomanipulation konnte daher geschlußfolgert werden, daß eine nachhaltige Wirkung nur dann erreicht werden kann, wenn zusätzlich zur top-down Steuerung des Nahrungsnetzes gleichzeitig eine erfolgreiche Kontrolle der bottom-up Prozesse im Gewässer realisiert wird, indem starke Schwankungen von bottom-up Faktoren vermieden werden und damit das System insgesamt stabilisiert wird. / The occurrence of midsummer declines of daphnids is often related to poor food conditions or fish predation. In this three-year-study on the midsummer decline of Daphnia galeata field investigations in the highly eutrophic biomanipulated Bautzen reservoir were combined with flow-through experiments in the laboratory. The following hypothesis was tested: The inability of adult Daphnia to reduce the filtering area of their feeding appendages in response to fast increasing food levels after a clear-water phase enhances adult mortality. During the clear-water phase daphnids develop large and dense filtercombs to optimise their filter feeding. When food concentrations increase, however, this adaptation to low-food situation may be inappropriate due to too high energy consumtion. As adult daphnids cannot reduce the size of their feeding appendages, the filtration process may be hindered when seston concentrations rise, resulting in reduced fitness and increasing adult mortality. Indeed, adult survival in the laboratory (predation excluded) drastically decreased exactly at that time when the Daphnia galeata population in Bautzen reservoir declined. However, enhanced mortality was found irrespective of different food conditions offered during the experiments. It is concluded that increased mortality of adult daphnids is not an direct effect of their inability to adapt the morphology of their filtercombs to high seston concentrations. Furthermore daphnids are able to compensate unfavorable food conditions within a certain range by different kinds of adaptation mechanisms. Therefore the timing of the changes of food conditions and the adaptations of daphnids is most important to the efficiency of energy gain of the daphnids. Concerning the success of biomanipulation it is concluded that in addition to the regulation of top-down mechanisms there is an urgent need for control of bottom-up processes in order to stabilize the ecosystem.

[pt] Tradicionalmente, os testes de formação em poços de petróleo buscam caracterizar o campo de permeabilidades a partir da interpretação dos transientes de pressão (PTA) nos períodos de fluxo e estática baseados em modelos isotérmicos de escoamento em meios porosos. Com o avanço da instrumentação dos testes, registros mais precisos de temperatura passaram a estar disponíveis e fomentaram a pesquisa baseada em modelos não isotérmicos que possibilitaram a análise a partir dos transientes de temperatura (TTA). Além da caracterização de parâmetros do reservatório como permeabilidade e porosidade com a interpretação dos transientes de temperatura, os dados de pressão obtidos a partir de um modelo não isotérmico representa de forma mais fidedigna o fenômeno físico sobretudo quando os testes são submetidos a maiores diferenciais de pressão. Este trabalho consiste no desenvolvimento de um simulador para teste de formação que considera a modelagem não isotérmica de reservatório unidimensional radial acoplado a um poço produtor e na utilização deste simulador, associado a métodos de otimização multivariável, para resolução do problema inverso da caracterização de parâmetros do reservatório. Alguns métodos de otimização foram testados e o algoritmo do Simplex de Nelder-Mead apresentou melhor eficácia. Foram estabelecidos três tipos de problemas e utilizados em três casos hipotéticos considerando inclusive a imposição artificial de ruídos nos sinais de pressão e temperatura utilizados para resolução do problema inverso. / [en] Traditionally, oil well formation tests aim to characterize the reservoir permeability field from pressure transient analysis (PTA) of drawdown and build up based on isothermal flow models in porous media. With the advancement of well test instrumentation, more accurate temperature records became available and have encouraged researches based on non-isothermal models that made possible the temperature transient analysis (TTA). In addition to the characterization of reservoir parameters such as permeability and porosity by TTA, the pressure data obtained from a non-isothermal model represent better the physical phenomenon, especially when the tests are subjected to greater drawdowns. This work consists in the development of a simulator for formation test that considers non-isothermal modeling of a unidimensional radial reservoir coupled to a production well and in the use of this simulator, associated with multivariable optimization methods, to solve the inverse problem of reservoir parameters characterization. Some optimization methods were tested and the Nelder-Mead Simplex algorithm presented better efficiency. Three types of problems were established and used in three hypothetical cases, including artificially imposed noise in pressure and temperature signals used to solve the inverse problem.

No description available.

No description available.

The focus of this work is to investigate the dissolution of MW25, a non-radioactive simulant of UK high-level nuclear waste borosilicate glass, and to predict its performance in the near field of a geological repository. A single-pass flow-through (SPFT) experimental system was used to measure the forward dissolution rates of MW25. Experiments were conducted in two parts. Experiment Part 1 considers the dissolution of the waste glass in deionised water at 40 and 90 oC and circum-neutral pH. Experiment Part 2 considers the dissolution of the waste glass in simulant groundwaters, with similar compositions to groundwaters of Callovo-Oxfordian clay (lower-strength sedimentary rock (LSSR)) and Borrowdale Volcanic Group rocks (higher-strength rock (HSR)), at 40 oC and pH 7. The forward dissolution rate measured in deionised water was found to be approximately one order of magnitude higher at 90 oC than at 40 oC. A similar release was observed for Si, Mg and Al at 40 oC and 90 oC, whereas the B, Cs, Na, Li and Mo showed an order of magnitude increase when the temperature was increased from 40 to 90 oC for low q/S values. The activation energy (Ea) of the reactions shows that the dissolution process is a surface phenomenon. At 90 oC the net effect of the processes governing MW25 dissolution led to the preferential release of boron and alkali metals relative to the release of Si during the transient dissolution stage, accompanied by an increase in the concentration of silicic acid. This suggests that the solution activity of silicic acid at a higher temperature has a weak influence on the release of the mobile elements. The forward dissolution rate measured in LSSR simulant groundwater was found to be slightly higher than that measured in HSR simulant groundwater. The dissolution behaviour of MW25 in both groundwaters is consistent with its behaviour in deionised water at 40 oC, with the dissolution rates of elements increasing as flow rates were increased. However, forward dissolution rates measured in the simulant groundwaters were lower than the forward dissolution rates measured in deionised water under these experimental conditions. This is attributable to the interaction of the components of the simulant groundwaters with the glass, as revealed by post-reaction surface analyses, and a consequential lower alkalinity of the leachates collected in the experiments with simulant groundwater than in deionised water. Reactive chemical transport simulations of waste glass dissolution and radionuclide release in a hypothetical near field were conducted over a time span of a million years with GoldSim. The results showed that enclosing the waste glass in a steel canister covered by a copper canister and emplacing the waste package in a granite host rock is optimal for the long-term isolation of the radionuclides. The waste glass was found to play a significant role in the overall performance of the near field. This study features a new method for estimating the surface area of reacted glass powder more accurately than the geometric surface area estimate, which is the preferred standard method among researchers.

In light of increasing harmful algal blooms and the need to protect human health and aquatic resources, proactive management approaches merit further study. For this purpose I conducted field samplings to characterize plankton community composition and laboratory experiments to test some approaches to new management schemes in the lower Rincon Delta. On site measurements and microscopic analysis showed that environmental parameters and plankton community composition varied considerably among sampling stations and sampling dates. A recent modeling study suggested that manipulation of freshwater inflow to estuaries might prevent phytoplankton blooms and enhance secondary productivity. To test this theory I conducted three semi-continuous design and flow-through incubation design experiments using natural plankton assemblages. I investigated the effect of two different pulsing regimes of inflow and nutrient loading on zooplankton densities, and phytoplankton biomass and diversity. Despite differences in zooplankton structure and phytoplankton community composition between the two experiment designs, the results confirmed that pulsed inflows might alter plankton dynamics. My findings showed that 3-day pulse treatments consistently supported greater zooplankton densities and higher phytoplankton species diversity when compared to 1-day pulse treatments. In addition, accumulation of phytoplankton biovolume remained low during 3-day pulse treatments. Differences in zooplankton performance between 3-day pulse and 1-day pulse inflow treatments were likely due to the ability of phytoplankton to uptake and store greater amounts of nutrients under conditions of 3-day pulse inflow. This resulted in food of higher quality for zooplankton, and might have supported greater zooplankton population growth rates. Additionally, in an attempt to understand the mechanisms leading to high biodiversity in aquatic ecosystems, I built a resource-storage model and studied the effects of resource-storage on competition of multiple phytoplankton species on multiple abiotic resources. I compared this model with a well-established multi-species competition model. My results showed that for certain species combinations a resource-storage-based model can generate dissimilar outcomes when compared to a model without resource-storage.

Se desarrolló cinco sistemas automatizados utilizando análisis por inyección secuencial (SIA) y análisis por inyección en flujo multijeringa (MSFIA). Se desarrolló un SI-analizador para la determinación de formaldehído utilizando la reacción de Hantzsch. El analizador fue aplicado a la monitorización en un cultivo de P. pastoris. Se desarrolló un SI-analizador para la determinación de glicerol y sorbitol. Se utilizó periodato para la reacción de Malaprade. El formaldehído generado fue cuantificado con la reacción de Hantzsch. El sistema incluyó la dilución de la muestra y procedimientos seleccionado por decisión inteligente del programa o por el usuario. Se lo aplicó a la monitorización en cultivos de P. pastoris.Se desarrolló un sistema de electroforesis capilar (CE) acoplado a un SIA aplicado a la separación de nitrofenoles. Se acopló por primera vez MSFIA con CE para pre-concentración en fase sólida y separación de nitrofenoles. Ambos sistemas mostraban recuperaciones satisfactorias para aguas ambientales. / Five analytical systems using Sequential Injection Analysis (SIA) and Multisyringe Flow Injection Analysis (MSFIA) were developed and applied with satisfactory analytical performance. A SI-analyzer for formaldehyde was developed automating Hantzsch reaction. It was successfully applied to formaldehyde monitoring in continuous medium filtrate of P. pastoris cultivation. A second SI-analyzer was developed for the determination of glycerol and sorbitol. Periodate was used as additional reagent to carry out Malaprade reaction and formaldehyde generated by polyalcohol oxidation was quantified. The system included automated sample dilution and procedures for two working ranges, selected by smart software decision or user-input. It was applied to monitoring of P. pastoris cultivations.A capillary electrophoresis (CE) system was developed and coupled to SIA. It was applied to the determination of nitrophenols. MSFIA and CE were coupled for the first time. Solid phase concentration and separation of nitrophenols were automated. The systems were applied to environmental water samples.

In light of increasing harmful algal blooms and the need to protect human health and aquatic resources, proactive management approaches merit further study. For this purpose I conducted field samplings to characterize plankton community composition and laboratory experiments to test some approaches to new management schemes in the lower Rincon Delta. On site measurements and microscopic analysis showed that environmental parameters and plankton community composition varied considerably among sampling stations and sampling dates. A recent modeling study suggested that manipulation of freshwater inflow to estuaries might prevent phytoplankton blooms and enhance secondary productivity. To test this theory I conducted three semi-continuous design and flow-through incubation design experiments using natural plankton assemblages. I investigated the effect of two different pulsing regimes of inflow and nutrient loading on zooplankton densities, and phytoplankton biomass and diversity. Despite differences in zooplankton structure and phytoplankton community composition between the two experiment designs, the results confirmed that pulsed inflows might alter plankton dynamics. My findings showed that 3-day pulse treatments consistently supported greater zooplankton densities and higher phytoplankton species diversity when compared to 1-day pulse treatments. In addition, accumulation of phytoplankton biovolume remained low during 3-day pulse treatments. Differences in zooplankton performance between 3-day pulse and 1-day pulse inflow treatments were likely due to the ability of phytoplankton to uptake and store greater amounts of nutrients under conditions of 3-day pulse inflow. This resulted in food of higher quality for zooplankton, and might have supported greater zooplankton population growth rates. Additionally, in an attempt to understand the mechanisms leading to high biodiversity in aquatic ecosystems, I built a resource-storage model and studied the effects of resource-storage on competition of multiple phytoplankton species on multiple abiotic resources. I compared this model with a well-established multi-species competition model. My results showed that for certain species combinations a resource-storage-based model can generate dissimilar outcomes when compared to a model without resource-storage.