In this thesis, we consider second-order fully nonlinear partial differential equations of elliptic type. Our aim is to develop computational methods using convergent difference schemes for stationary Hamilton-Jacobi equations with Dirichlet and Neumann type boundary conditions in arbitrary two-dimensional domains. First, we introduce the notion of viscosity solutions in both continuous and discontinuous frameworks. Next, we review Barles-Souganidis approach using monotone, consistent, and stable schemes. In particular, we show that these schemes converge locally uniformly to the unique viscosity solution of the first-order Hamilton-Jacobi equations under mild assumptions. To solve the scheme numerically, we use Euler map with some initial guess. This iterative method gives the viscosity solution as a limit. Moreover, we illustrate our numerical approach in several two-dimensional examples.

The main topic of the thesis was to examine the hydrophobicity of labeling adhesives in the state before drying, it means their resistance against condensated moisture. The problem was solved by measuremensts of contact angle between the drop of water and glue. Measurements of dynamic viscosity and wet tack were also performed for the sake of complex characterization of the glue properties. Comparison of properties among single-component adhesives based on the acrylic copolymers alkalised with various agents was made. The impact of starches and industrial additives on glues was determined by the analysis of primary physical and chemical parameters. The purpose of the measurements was to develop a formula of the glue with enhanced atmospheric moisture resistance, that also would have the required parameters in the equilibrium. Finally, some selected glue samples were practically tested for condensation water resistance. These tests were performed in a climatic chamber with water condensating conditions.

Lubricants additives are inseparable component of modern high-tech lubricants. Viscosity index improvers additives play uncoverable role in a branch of boundary lubrication. They are designed to ensure sufficient oil film thickness in low speeds of frictional surfaces motion. This thesis deal with effect of specific viscosity index improvers additives on boundary lubrication film formation in elliptical contact. The purpose of this work is also checking the effect of concentration changing these additives on lubricantion film thickness formation.

The characterization of the vibromixer principles, in particular FUNDAMIX® technology produced by the Swiss company Dr.Mueller AG, is the focus of this study. Tests varying the vibration’s frequencies and amplitudes, as well as the mixing plate geometry, in terms of number of holes and their diameter, are done. Interesting results regarding these parameters are obtained, proving problem complexity and previous experience. Higher amplitudes and frequencies result in a better fluid dynamic performance of the vibromixer, i.e. flow rate formed due to pumping capacity of the plate and creating the liquid recirculation. The available total area of the holes should be limited too. Different fluid viscosities (up to 1212mPa/s) are tested and possible carbon fiber improvements in the shaft production briefly discussed. Finally, a Computational Fluid Dynamic approach is done and possible further researches are covered. / Blandningsegenskaperna hos en vibreringsblandare av med FUNDAMIX®-teknik har undersökt och resultaten beskrivs här. Experiment utfördes där frekvens och amplitud hos vibrationen tillsammans med blandningsplattans geometri i termer av antal hål och deras diameter varierades. Primärt uppmättes tiden för en inblandad komponent att nå vätskeytan från stillastående på botten av blandningskärlet. Resultaten visar att blandningsproblemet är komplext. Högre amplitud och frekvens resulterade i en bättre fluidmekaniska prestanda hos vibreringsblandaren, d.v.s. flödeshastighet och pumpkapaciteten hos plattan förbättrades. Den totala ytan hos hålen bör också begränsas för bättre prestanda. Olika viskositeter(upp till 1212 mPa/s) hos mediet testades. Slutligen togs en numerisk modell för strömningssimuleringar fram och spänningar i kärlet och stång skattades med avseende på plasticering i kärlet och instabilitet hos stången. Överskattning av lasterna visade att befintlig konstruktion är strukturellt konservativ.

In this thesis, two important thermo-physical properties of nanofluids: thermal conductivity and viscosity together with shelf stability of them are investigated. Nanofluids are defined as colloidal suspension of solid particles with the size of lower than 100 nanometer. Thermal conductivity, viscosity and stability of nanofluids were measured by means of TPS method, rotational method and sedimentation balance method, respectively. TPS analyzer and viscometer were calibrated in the early stage and all measured data were in the reasonable range. Effect of some parameters including temperature, concentration, size, shape, alcohol addition and sonication time has been studied on thermal conductivity and viscosity of nanofluids. It has been concluded that increasing temperature, concentration and sonication time can lead to thermal conductivity enhancement while increasing amount of alcohol can decrease thermal conductivity of nanofluids. Generally, tests relating viscosity of nanofluids revealed that increasing concentration increases viscosity; however, increasing other investigated parameters such as temperature, sonication time and amount of alcohol decrease viscosity. In both cases, increasing size of nanofluid results in thermal conductivity and viscosity reduction up to specific size (250 nm) while big particle size (800 nm) increases thermal conductivity and viscosity, drastically. In addition, silver nanofluid with fiber shaped nanoparticles showed higher thermal conductivity and viscosity compared to one with spherical shape nanoparticles. Furthermore, effect of concentration and sonication time have been inspected on stability of nanofluids. Test results indicated that increasing concentration speeds up sedimentation of nanoparticles while bath sonication of nanofluid brings about lower weight for settled particles. Considering relative thermal conductivity to relative viscosity of some nanofluids exposes that ascending or descending behavior of graph can result in some preliminary evaluation regarding applicability of nanofluids as coolant. It can be stated that ascending trend shows better applicability of the sample in higher temperatures while it is opposite for descending trend. Meanwhile, it can be declared that higher value for this factor shows more applicable nanofluid with higher thermal conductivity and less viscosity. Finally, it has been shown that sedimentation causes reduction of thermal conductivity as well as viscosity. For further research activities, it would be suggested to focus more on microscopic investigation regarding behavior of nanofluids besides macroscopic study.

The characterization of the vibromixer principles, in particular FUNDAMIX® technology produced bythe Swiss company Dr.Mueller AG, is the focus of this study. Tests varying the vibration’s frequencies andamplitudes, as well as the mixing plate geometry, in terms of number of holes and their diameter, are done.Interesting results regarding these parameters are obtained, proving problem complexity and previousexperience. Higher amplitudes and frequencies result in a better fluid dynamic performance of thevibromixer, i.e. flow rate formed due to pumping capacity of the plate and creating the liquid recirculation.The available total area of the holes should be limited too. Different fluid viscosities (up to 1212mPa/s) aretested and possible carbon fiber improvements in the shaft production briefly discussed. Finally, aComputational Fluid Dynamic approach is done and possible further researches are covered.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23228号 / 工博第4872号 / 新制||工||1760(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 山子 茂, 教授 大内 誠, 教授 中村 正治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, for the degree of Master of Science. School of Computer Science and Applied Mathematics. November 7, 2016. / The equations for the flow of a thin lm of molten glass on a bath of molten tin are extended to the case in which the viscosity of the molten glass depends on the temperature. The continuity equation for an incompressible fluid, the Navier-Stokes equation and the energy balance equation are written in the lubrication (thin fluid lm) approximation. The kinematic boundary condition and the boundary conditions for the normal and tangential stress and the normal heat flux are derived on the upper and lower surfaces of the glass ribbon. It is found for the lubrication approximation that only one equation is obtained for four unknowns which are the two horizontal velocity components, the absolute temperature difference and the thickness of the molten glass rib- bon. The remaining three equations are obtained by taking the calculation to the next order in the square of the ratio of the thickness to length of the glass ribbon. The kinematic edge condition and the edge conditions for the normal and tangential stress and the normal heat flux are derived. The four edge conditions and the boundary conditions at the inlet and outlet give the boundary conditions for the four partial differential equations. It is not the aim of the dissertation to solve the boundary value problem which has been derived, either numerically or analytically. / LG2017

This study deals with the effects of branching in some high polymers on viscosity behaviour and on the rela­tionship between intrinsic viscosity and molecular weight. First, the preparation of branched polymers by means of graft polymerization is described. Evidence for the occurrence of grafting, which would result in the growth of polystyrene branches on a min, or backbone, chain com­posed of polystyrene or a copolymer of styrene and li-vinyl-cyclohexene-1, is reviewed, Next, the design, construction, and calibration of a flexible light scattering photometer is described. The performance of this instrument is shown to bs adequate for the determination of the molecular weight and size, as well as the second virial coefficient, of a high polymer in solu­tion. Finally, properties of the graft polymers in solu­tion are compared, with the corresponding properties of linear polystyrene. The relationships found between intrin­sic viscosity and molecular weight, as well as the values obtained for the second virial coefficient, confirm the ex­istence of branching in the graft polymers. On the other hand, it is shown that the viscosity slope constant, Huggins' k', the of which, is often used as an indication of branching, is not affected significantly by the branching present in the graft polymers. / Thesis / Doctor of Philosophy (PhD)

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