No / Mass production of components with micro and nano scale surface features is known as micromoulding and is very sensitive to a number of variables that can cause important changes in the surface geometry of the components. The surface itself is regarded as a key element in determining the product's functionality and as such must be subject to thorough quality control procedures. To that end, a number of surface measurement techniques have been employed namely, White Light Interferometry (WLI) and Atomic Force Microscopy (AMF), whose resulting data is given in the form of large and rather unmanageable Cartesian point clouds. This work uses Partial Differential Equations (PDEs) as means for characterizing efficiently the surfaces associated with these data sets. This is carried out by solving the Biharmonic equation subject to a set of boundary conditions describing outer surface contours extracted from the raw measurement data. Design parameters are expressed as a function of the coefficients associated with the analytic solution of the Biharmonic equation and are then compared against the design parameters describing an ideal surface profile. Thus, the technique proposed here offers means for quality assessment using compressed data sets.

Non-wetting surfaces mainly categorized into superhydrophobic (SHS), lubricant-infused (LIS) and solid-infused surfaces (SIS), by virtue of their superior water repellant properties have wide applications in several energy and environmental systems. In this dissertation, the role of non-wetting surfaces toward the enhancement of condensation effectiveness is analyzed by taking into consideration the tube side and shell side individual interfacial energy transport processes namely, drag reduction, convection heat transfer enhancement, fouling mitigation and dropwise condensation heat transfer. First, an analytical solution is developed for effective slip length and, in turn, drag reduction and friction factor on structured non-wetting surfaces. Secondly, by combining the solution for effective slip length on structured non-wetting surfaces and the fractal characterization of generic multiscale rough surfaces, a theoretical analysis of drag reduction, friction factor, and convection heat transfer enhancement is conducted for scalable non-wetting surfaces. Next, fractal representation of rough surfaces is used to theoretical derive the dropwise condensation heat transfer performance on SHS and novel SIS surfaces. The aspect of dynamic fouling mitigation properties of non-wetting surfaces is explored by conducting systematic experiments. Using Taguchi design of experiments, this work for the first time presents a closed formed relationship of fouling mitigation quantified in terms of asymptotic fouling resistance with Reynolds number, foulant concentration and viscosity of the infusion material that represents the different surface types in a unified manner. Furthermore, it was observed that LIS and SIS offer excellent fouling mitigation compared to SHS and conventional smooth surfaces, however only SIS owing to the presence of solid-like infusion materials is observed to be robust for practical applications. / Doctor of Philosophy / Inspired by the naturally occurring water repellant lotus leaf and pitcher plant, metallic surfaces have undergone engineering modifications to their native wetting properties. By generating roughness features ranging from nanometer to micrometer length scales, subjecting them to low surface energy treatments and by choosing an appropriate water repellant infusion material, the water repellant properties seen on lotus leaf and pitcher plant can be engineered. Such water repellant (non-wetting) surface fabrication methods are widely available in the literature however very few are scalable to surface types (e.g. copper, aluminum etc.), surface size (millimeters to meters) and shape (plain, curved, inside of tubes etc.). In this work, considering scalable fabrication methods such as electrodeposition and chemical etching, a systematic analysis is conducted on enhancement of four interfacial processes that are a part of many industrial applications. First, the extent of water repellency by structured non-wetting surfaces for the flow of fluid (water) quantified in terms of effective slip length of flow is analytically derived. Using this theory and a self-similar (fractal) nature of the more generic rough surface designs, a theoretical analysis into the drag reduction, convection heat transfer enhancement on non-wetting surfaces is conducted. Next, using the fractal nature of the rough superhydrophobic surfaces (SHS) a theoretical investigation into dropwise condensation performance is used to derive bounds on condensation heat transfer enhancement. Through systematic experimental investigations, it is shown that a solid-infused surface (SIS) and lubricant-infused surfaces (LIS) which, respectively, incorporate a polymer and a slippery lubricant in the interstitial region of metallic asperities, exhibit superior dynamic mineral fouling mitigation performance compared to SHS and conventional smooth surfaces. In addition, it is demonstrated that SIS is a far robust and durable choice when compared to LIS for use in the long run.

Yes / Direct parameterisation is among the most widely used facial animation techniques but requires complicated ways to animate face models which have complex topology. This paper develops a simple solution by introducing a PDE-based facial animation scheme. Using a PDE face model means we only need to animate a group of boundary curves without using any other conventional surface interpolation algorithms. We describe the basis of the method and show results from a practical implementation. / EPSRC

No description available.

Le procédé de flottation est une technique de séparation de minerais basée sur la différence d’hydrophobicité des espèces minérales introduites dans des cellules dans le but de séparer les espèces minérales en fonction de ce critère. L’étude de la mouillabilité d’une surface de minerai devient alors un concept intéressant dans une optique d’optimisation de procédé. Les technologies standards qui permettent l’étude de ce facteur sont souvent imprécises due à la morphologie, aux défauts de surface ainsi qu’à la chimie variable des particules présentes au sein d’un même échantillon. Ayant pour but d’évaluer ce paramètre et permettant d’avoir des échantillons suffisants pour effectuer différents tests chimiques et minéralogiques, un nouveau montage basé sur la flottation de surface a été développé. Des tests comparatifs entre des technologies standards de flottation de laboratoire ainsi que la flottation de surface ont été réalisés en utilisant une matrice minérale composée de graphite et de quartz, dans le but de comparer leur efficacité de séparation. Les différents tests montrent, pour la flottation de surface, une séparation sélective similaire à celle obtenue en cellule Denver en plus d’être plus reproductible. Ensuite, des tests de flottation de surface avec de la sphalérite et des moussants confirment la compatibilité du montage avec des échantillons de minerais complexes et exposent les changements de la flottabilité des particules causés par la présence de surfactants. Un modèle par régression logistique sur la minéralogie des échantillons démontre une influence significative de la part des agents moussants sur la probabilité qu’une particule flotte ou au contraire coule. Le montage de flottation de surface est donc un outil de caractérisation robuste et polyvalent pour l’analyse de la mouillabilité d’un échantillon en reproduisant, de façon isolée, l’étape de collision entre une bulle d’air et une particule. / The flotation process is a separation technique based on the wettability difference of minerals’ surface introduced in the flotation cell to concentrate different mineral species according to this criterion. In the optics of optimizing the process, studying the wettability property of a mineral surface becomes interesting. The standard technologies used to assess this parameter are sometimes inaccurate for complex minerals due to their irregular morphology, their surface defects and their surface’s chemical heterogeneity which can bias the results. To study the wettability of mineral samples, a new surface flotation apparatus has been developed keeping in mind the necessity of obtaining a sufficient amount of separated minerals in both the overflow and underflow allowing chemical and mineralogical analyses. Comparative tests have been conducted with the new surface flotation design and two standard laboratory flotation methods using a mineral matrix composed of graphite and quartz to compare their separation efficiency. The results proved that the new design of the surface flotation generates a separation similar to the one in a Denver Cell with a lower standard deviation and using a substantially lower amount of minerals. Following the proof of concept using a simple mineral matrix, an experimental plan has been carried out with the surface flotation device testing copper zinc sulphide ore samples and frother agents. The results confirmed the compatibility of the new methods with sulphur minerals, as well as the impacts of frothers on the wettability of particles at the liquid-gas interface. A binary logistic regression using mineralogical data demonstrates a significant impact from the frothers on the probability of a particle to sink or float at the interface. In brief, the new surface flotation apparatus simulates the collision step of the flotation process without hydrodynamic influence as in conventional cells and allows the assessment of the wettability for different types of mineral samples.

Cette thèse porte sur la construction de nouveaux exemples de surfaces minimales dérivées de la famille de surfaces de Costa-Hoffman-Meeks. Il s'agit d'une famille de surfaces minimales complètes plongées avec trois bouts et genre k > 0. Soit M_k la surface de Costa_Hoffman_Meeks de genre k. Dans le chapitre 1, j'ai démontré que M_k est non dégénérée pour k > 37. J'ai donc étendu les résultats de S. Nayatani qui assuraient que la surface M_k est non dégénérée seulement pour k=1,...,37. Ce résultat permet de montrer dans les chapitres 2 et 3 l'existence de nouveaux exemples de surfaces minimales de genre g arbitraire à l'aide d'une procédure de collage d'autres surfaces déjà connues (parmi lesquelles y figure la surface M_k). Sans ceci, ces résultats ne seraient valables que pour k < 38. En particulier dans le chapitre 2, j'ai démontré l'existence, dans H^2 x R, (H^2 étant le plan hyperbolique) d'une famille de surfaces minimales plongées inspirées de M_k, pour tout k > 0. Ce résultat peut être censé un cas particulier d'un théorème générale de désingularisation de l'intersection de deux surfaces minimales annoncé par N. Kapouleas et jamais publié. Le chapitre 3 est consacré à la construction de trois familles de surfaces minimales simplement périodiques plongées dans R^3 dont le quotient a genre arbitraire. Les résultats présentés dans ce chapitre (obtenus en collaborations avec L. Hauswirth et M. Rodríguez) généralisent plusieurs anciennes constructions / This thesis is devoted to the construction of new examples of minimal surfaces derived from the family of surfaces if Costa-Hoffman-Meeks. Surfaces in this family are complete embedded with 3 ends and genus k > 0. Let M_k denote the surface of Costa-Hoffman-Meeks of genus k. In chapter 1 I showed M_k is non degenerate for k > 37. So I extended the results of S. Nayatani which insured M_k is non degenerate only for k=1,...,37. That allows to prove in chapters 2 and 3 the existence of new examples of minimal surfaces by a gluing procedure involving already known surfaces (among which figures M_k). Without it theses results would hold only for k < 38. In particular in chapter 2 I showed the existence in H^2 x R (where H^2 denotes the hyperbolic plane) of a family of surfaces inspired to M_k, for all k > 0, which are complete and embedded. This result can be considered as a particular case of a general theorem of desingularization of the intersection of two minimal surfaces announced by N. Kapouleas and never published. Chapter 3 is devoted to the construction of 3 families of singly periodic minimal surfaces, embedded in R^3, whose quotient has an arbitrary value of the genus. The results showed in this chapter (obtained in collaboration with L. Hauswirth and M. Rodríguez) generalize many previous constructions

Many solids have Fermi surfaces which are approximated as ellipsoids. A comprehensive solution for the magnetoconductivity of an ellipsoid is obtained which proves the existence of a relaxation time tensor which can be anisotropic and which is a function of energy only.

This Bachelor's thesis deals with fractals and orbits on Sierpinski carpets. We present the fundamental theory regarding fractals and some illustrative examples together with fractal billiards. In the latter part of the thesis we use elementary methods to present an original proof concerning the closure of some billiard orbits on Sierpinski carpets. A survey of the article Periodic Billiard orbits of self-similar Sierpinski Carpets, see [8], has been done, in which we make a discussion about one open question regarding reflections on the carpet. Furthermore, we state and prove some propositions related to this open question.

We present an optical surface in closed form that can be used to design lenses for controlling relative illumination on a target surface. The optical surface is constructed by rotation of the pedal curve to the ellipse about its minor axis. Three renditions of the surface are provided, namely as an expansion of a base surface, and as combinations of several base surfaces. Examples of the performance of the surfaces are presented for the case of a point light source. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

Pour des systèmes mécaniques fortement sollicités et lubrifiés (en roulement avec ou sans glissement), les performances des lubrifiants se caractérisent par l’évolution de l’usure des surfaces. Celle-ci peut se manifester par un micro-écaillage qui conduit à une dégradation des fonctionnalités des surfaces. Pour quantifier la durabilité du mécanisme, il est donc important de pouvoir caractériser l’usure du contact : quantifiable à l’échelle du composant par la mesure de la perte de masse par exemple. Notre approche tentera de caractériser l’usure des surfaces dans ses premières heures de fonctionnement (phase de rodage) se manifestant par des modifications locales de la rugosité et non par la perte de masse qui est peu significative. Notre étude a pour objectif d’établir une relation entre l’évolution des paramètres surfaciques durant cette phase de rodage et la résistance à l’usure des surfaces. Des paramètres tridimensionnels sont ainsi identifiés, permettant de connaître assez tôt, les performances des lubrifiants la fin de longs essais d’endurance. / For lubricated mechanical systems and working with heavy loading (rolling with or without sliding), the lubricants performances are characterized by the evolution of the wear on surfaces. This wear can take the form of micro-pitting which leads to a functional surface degradation. To quantify the durability of the mechanism, it is thus important to be able to characterize the wear of the contact: quantifiable on the scale of the component by the measure of the loss of mass for example. Our approach stands to characterize the wear of surfaces during the first hours of functioning (running-on phase), showing itself by local modifications of the roughness and not by the loss of mass which insignificant. Our study has for objective to establish a relation between the evolution of the surface parameters during the running-in phase and the wear of the surfaces. Tridimentional parameters are so identified, to know early enough the performances of lubricants, without waiting the end of long endurance tests.