Dans un contexte de fort développement des biotechnologies, de plus en plus de composés sont extraits, généralement par l'utilisation d'un solvant, à partir de bio-ressources renouvelables. L'éthanol (parfois en mélange avec de l'eau) est un des solvants utilisés car il permet de solubiliser des molécules polaires moyennement hydrophobes et peut être, lui-même, produit par fermentation à partir de bio-ressources renouvelables. Après l'étape d'extraction, les procédés baro-membranaires, et en particulier l'ultrafiltration (UF), peuvent être des solutions pertinentes en vue d'un fractionnement plus fin des constituants de l'extrait. Cependant, à ce jour, si ce procédé est largement développé en milieu aqueux, peu d'études portent sur l'UF en milieu hydro-alcoolique à des teneurs supérieures à 15% en éthanol. Le but de ces travaux est d'étudier l'impact du changement de solvant sur les mécanismes de transfert en UF. Pour cela, une étude systématique de l'UF a été réalisée dans des mélanges eau/éthanol de composition variable allant jusqu'à 30% d'éthanol en volume. L'UF a été conduite en utilisant une protéine modèle, le lysozyme, choisie en raison simultanément de sa bonne stabilité dans les milieux filtrés et de la variation de sa charge en fonction de son environnement physico-chimique (pH, force ionique). L'ajout de sels (NaCl, KH2PO4) aux milieux hydro-alcooliques a permis de montrer l'impact de la modulation des interactions électrostatiques, connues pour jouer un rôle important sur les performances de rétention en UF en milieu aqueux. Les rétentions expérimentales, obtenues au moyen d'une membrane en oxyde de zirconium, ont été interprétés à l'aide du modèle CDE (convection – diffusion – migration électrophorétique) précédemment développé à l'ISCR pour les milieux aqueux et contribuent ainsi à l'extension du domaine d'application de ce modèle. / In the context of the rapid growth of the biotechnological sector, more and more molecules are extracted from renewable resources using solvent extraction. Ethanol (alone or in mixture with water) is one of the most used solvent as it allows solubilizing polar molecules exhibiting moderately hydrophobic nature. Furthermore, it can be itself produced by fermentation using renewable bioresources as a substrate. Following the extraction step, pressure-driven membrane processes, and ultrafiltration (UF) in particular, can be used for further fractionation of the alcoholic extract. However, to date, UF is widely studied in aqueous solution but only few studies deal with its application to the filtration of hydro-alcoholic medium for ethanol concentration above 15%. The objective of this work is thus to study the consequences of the solvent modification on UF transfer mechanisms. To this end, a systematic study of UF in water/ethanol mixture of variable composition up to 30 % (v/v) has been carried out. Lysozyme has been chosen as the model solute due to its high stability in the tested conditions and its surface charge modification according to the physicochemical environment (pH, ionic strength). Thereby, electrostatic interactions known to play a key role in aqueous UF, where modulated by salt addition (NaCl, KH2PO4) to the hydro-alcoholic mixtures. Experimental results obtained using a zirconium oxide membrane were analyzed using the CDE (convection, diffusion and electrophoretic migration) model previously developed in our group for aqueous filtration. The range of application of the CDE model is thus enlarged to the case of water/ethanol mixtures.

Nowadays, catalysis lies at the heart of economy growth mainly in the petroleum industry. Catalysis can offer real and potential solutions to the current challenges for a long-term sustainable energy, green chemistry, and environmental protection. In this context, one of the most important and future prosperity promising catalytic applications in the petrochemical field is hydrocarbons metathesis; it consists on the conversion of both renewable and non-petroleum fossil carbon sources to transportation fuels. Olefin metathesis has become one of the standard methodologies for constructing C-C bonds in many organic transformation reactions. This owed to the numerous types of metathesis reactions that have been developed, for example, enyne, ring-opening and closing, self and cross metathesis, etc. But the one step conversion of olefin to alkanes has not been studied much. Recently, only one such a work has been published for the hydro-metathesis of propylene by tantalum hydride supported on KCC-1 in dynamic reactor. With this knowledge, we thought to study the hydro-metathesis using liquid olefin (1-decene). Another aspect of using 1-decene comes from our previous experience on metathesis of n-decane where the first step is the conversion of decane to 1-decene and subsequently to different chain length alkanes with W-alkyl/alkylidene catalyst. In this way, it would be easy for us to use different catalysts and compare them with parent catalyst concerning TON. We found 100% conversion with TON of 1010 using supported WMe6 onto SiO2-700 [(≡Si-O-)WMe5] against the previous results for n-decane showing 20% conversion and TON of 153. In this work, we disclose the hydro-metathesis reaction of 1-decene using well-defined silica supported W(VI), Mo(VI) and Ta(V) alkyl catalysts in batch reactor condition. This work is divided into three major sections; first chapter contains an introduction to the field of catalysis and surface organometallic chemistry. In second chapter, we describe all the experimental procedures of the catalysts. The third chapter is devoted to the characterization and interpretation followed by catalytic reactions. Finally, a brief conclusion of the present study is given.

This study is focused on modifying an existing solenoid valve based semi-active hydropneumatic spring-damper system using Magneto-Rheological (MR) fluid. The MR fluid's effective viscosity can be altered by application of a magnetic field. Therefore, using a magnetic/ MR valve makes it possible to change the state of the system by simply changing the applied magnetic field. A prototype MR valve was developed to determine whether a unit small enough for installation was possible. This prototype valve was designed from first principles and properties such as pressure drop over the valve (damping) and flow blocking (for switching between spring characteristics) were measured. The measured pressure drop over the valve was higher than what was design for which was due to an incorrect assumption for the viscosity of the thixotropic MR Fluid. The flow blocking ability of the valve was determined by constant force tests. Results showed that the valve could virtually block the flow of fluid for approximately a quarter of the vehicles weight. With the second prototype, the valve design and magnetic circuit design were improved. Two valves were constructed and implemented on a prototype suspension system. The damping characteristics of the system were lower than expected, however they can be improved by changing the valve geometry. The base spring characteristics are acceptable, however the higher spring characteristics fail when a high force is exerted on the strut that exceeds the valves flow blocking capability. The response time of the valve is not yet sufficient to make the system viable for real world implementation, especially under extreme conditions that can change more rapidly than the current valves. / Dissertation (MEng)--University of Pretoria, 2015. / Mechanical and Aeronautical Engineering / MEng / Unrestricted

This paper studies if the Flagship Namami Gange program of Cleaning the river Ganges in India aligns with the transcendental discourse on the river. Web contents as Facebook, YouTube and Twitter along with Indian English daily newspaper reports are used here as the source of data. The study shows that the program aligns with the transcendental discourse on river Ganges as the Mother Goddess and reaching out to her devotees.

The main goal of this research is to evaluate the behavior of earth pressure profiles in unsaturated soils under transient flow. In the first part, an empirical correlation is proposed to obtain the fitting parameters of Brooks and Corey’s soil-water retention model from Fredlund and Xing’s model. The retention models and the proposed equivalency between the models were assessed for 601 soil samples from the unsaturated soils hydraulic database (UNSODA). In the second part, a coupled one-dimensional hydro-mechanical model is introduced and is implemented into Rankine’s earth-pressure model to represent active and passive earth pressure profiles in unsaturated soils under transient flow. A realistic coupling process of infiltration and deformation in the porous medium is established based on the variation in permeability along with deformation in the soil body. The results showed that ignoring the hydro-mechanical coupling effect can lead to underestimation of earth pressure values, especially for fine-grained soils.

The main objective of this research is to present a robust numerical framework based upon Isogeometric analysis (IGA) for simulation of thermo-hydro-mechanical (THM) processes in variably saturated soils. The proposed platform employs the Bézier extraction operator to connect IGA to the conventional finite element analysis (FEA), allowing to take advantage of features offered by the two methods. In the first part, the formulation and numerical implementation for fully coupled numerical simulation of THM problems in saturated porous media are presented. The results are compared against analytical solutions and experimental tests available in the literature. In the second part, the proposed method is used to study the temperature effect on the hydro-mechanical response of sd supporting hydrocarbon pipelines, an aspect that has been overlooked in the majority of previous studies. The results highlight the need for considering nonisothermal behavior in different analysis and design stages of sd-buried pipelines. In the third part, the proposed IGA-FEA framework is extended to evaluate the nonisothermal elasto-plastic behavior of unsaturated soils. Drucker-Prager yield surface is used as criterion to limit the modified effective stress where the model follows small strain, quasi-static loading conditions. The framework is used to simulate strain localization of unsaturated dense sand subjected to undrained compression loading. In comparison with FEA, the present method smoothly distributes plastic strain over the adjacent elements. The parametric study highlights the importance of considering temperature effects in elasto-plastic analysis of unsaturated soils.

Boats have a rich history, evolving in shape and purpose. From ancient logboats to modern superyachts, their design depends on their intended use. Among personal watercraft, such as yachts and motorboats, there are various types like fishing boats and day cruisers. Runabout boats are popular today for leisure. They are fast, agile, and versatile, originating in the 1920s with wooden bodies. Modern Runabout boats carry 4-8 people, lack a cabin, and are favored by casual boaters.  One of the latest trends within boating is the usage of hydrofoils, a hydrofoil is a wing-like shape that lifts a boat out of the water, reducing drag on the boat. Flighter is a new company intending on creating a new concept for a hydro foiling boat that is meant for transportation. They want a boat that is agile and has some multifunctional aspects allowing it to be used by a wider user group.  The following project is a design project focused on the conceptual interior design of Flighters new boat where the goal is to create an interior that fits with Flighters agenda. The concept developed through the project uses a rail system to create modular seating that allows the user to modify the boat to the current needs. There is also a multifunctional sofa in the back allowing for extra storage and seating if needed.

A project to suggest an alternative to small scale hydro power at the old power plant in Långforsen, Jämtland, Sweden. Using excavation as a tool and raw materials from the site, the aim is to take the visitor into nature by using choreographed movement through the site, close to nature shelters, and a visitor center to tie it all together.

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