A MEMS-based micro-electro-discharge machining technique that is enabled by the actuation of micromachined planar electrodes defined on the surfaces of the workpiece is developed that eliminates the need of numerical control machines. First, the planar electrodes actuated by hydrodynamic force is developed. The electrode structures are defined by patterning l8-µm-thick copper foil laminated on the stainless steel workpiece through an intermediate photoresist layer and released by sacrificial etching of the resist layer. The planer electrodes are constructed to be single layer structures without particular features underneath. All the patterning and sacrificial etching steps are performed using dry-film photoresists towards achieving high scalability of the machining technique to large-area applications. A DC voltage of 80-140 V is applied between the electrode and the workpiece through a resistance-capacitance circuit that controls the pulse energy and timing of spark discharges. The parasitic capacitance of the electrode structure is used to form a resistance capacitance circuit for the generation of pulsed spark discharge between the electrode and the workpiece. The suspended electrodes are actuated towards the workpiece using the downflow of dielectric machining fluid, initiating and sustaining the machining process. Micromachining of stainless steel is experimentally demonstrated with the machining voltage of 90V and continuous flow of the fluid at the velocity of 3.4-3.9 m/s, providing removal depth of 20 µm. The experimental results of the electrode actuation match well with the theoretical estimations. Second, the planar electrodes are electrostatically actuated towards workpiece for machining. In addition to the single-layer, this effort uses double-layer structures defined on the bottom surface of the electrode to create custom designed patterns on the workpiece material. The suspended electrode is electrostatically actuated towards the wafer based on the pull-in, resulting in a breakdown, or spark discharge. This instantly lowers the gap voltage, releasing the electrode, and the gap value recovers as the capacitor is charged up through the resistor. Sequential pulses are produced through the self-regulated discharging-charging cycle. Micromachining of the stainless-steel wafer is demonstrated using the electrodes with single-layer and double-layer structures. The experimental results of the dynamic built-capacitance and mechanical behavior of the electrode devices are also analyzed. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Recent tsunami disasters caused devastating damages to well-engineered coastal infrastructures. In fact, the current design guidelines are not able to provide realistic estimations of tsunami loads in order to design structures to withstand tsunamis. Tsunami hydrodynamic forces are estimated using the drag coefficient. This coefficient is traditionally calculated based on a steady flow analogy. However, tsunami bores behave like unsteady flows. The present work aims at investigating the tsunami forces for different structure geometries to provide realistic guidelines to estimate drag coefficients considering unsteady flows. In the present paper, the dam-break approach is used to investigate the tsunami-like bore interaction with structures. A three-dimensional multiphase numerical model is implemented to study the tsunami induced forces on rectangular shape structures with various aspect ratios (width/depth) and orientations. The numerical model results are validated using measured forces and bore surface elevations of the physical experiments. A scaled-up domain is modeled in order to eliminate the effects of domain sidewalls in the simulation results. The drag coefficient relations with structure geometries and bore depths are provided. The obtained hydrodynamic forces and drag coefficients are compared with existing data in the literature and design codes. For the second topic, a multi-phase three-dimensional numerical reproduction of a large scale laboratory experiment of tsunami-like bores interaction with a surface-piercing circular column is presented. The numerical simulation is conducted in OpenFOAM. The dam-break mechanism is implemented in order to generate tsunami-like bores. The numerical model is validated using the experimental results performed at Canadian Hydraulics Center of the National Research Council (NRC-CHC) in Ottawa. The unsteady Reynolds Averaged Navier-Stokes equations (RANS) are used in order to treat the turbulence effects. The Shear Stress Transport (SST) k-ω turbulence model showed high level of accuracy in replication of the bore-structure interaction. Further, a scaled-up domain is used to investigate the influence of the bed condition in terms of various downstream depths and roughness. Finally, a broad investigation on the bore propagation characteristics is performed. The resulting stream-wise forces exerted on the structural column as well as the bore velocity are compared and analyzed for smooth, rough, dry and wet beds with varying depths.

The process of froth flotation relies on using air bubbles to collect desired mineral particles dispersed in aqueous media on the surface, while leaving undesirous mineral particles behind. For a particle to be collected on the surface of a bubble, the thin liquid films (or wetting films) of water formed in between must rupture. According to the Frumkin-Derjaguin isotherm, it is necessary that wetting films can rupture when the disjoining pressures are negative. However, the negative disjoining pressures are difficult to measure due to the instability and short lifetimes of the films. In the present work, two new methods of determining negative disjoining pressures have been developed. One is to use the modified thin film pressure balance (TFPB) technique, and the other is to directly determine the interaction forces using the force apparatus for deformable surfaces (FADS) developed in the present work. The former is designed to obtain spatiotemporal profiles of unstable wetting films by recording the optical interference patterns. The kinetic information derived from the spatiotemporal profiles were then used to determine the disjoining pressures using an analytical expression derived in the present work on the basis of the Reynolds lubrication theory. The technique has been used to study the effects of surface hydrophobicity, electrolyte (Al3+ ions) concentration, and bubble size on the stability of wetting films. Further, the geometric mean combining rule has been tested to see if the disjoining pressures of the wetting films can be predicted from the disjoining pressures of the colloid films formed between two hydrophobic surfaces and the disjoining pressures of the foam films formed between two air bubbles. The FADS is capable of directly measuring the interaction forces between air bubble and solid surface, and simultaneously monitoring the bubble deformation. The results were analyzed using the Reynolds lubrication theory and the extended DLVO theory to determine both the hydrodynamic and disjoining pressures. The FADS was used to study the effects of surface hydrophobicity and approach speeds. The results show that hydrophobic force is the major driving force for the bubble-particle interactions occurring in flotation. / Ph. D.

In this dissertation, an approach for determining parameters for a nonlinear Lagrangian mechanical system model of a submerged vessel maneuvering near waves is presented. The nonlinear model with determined parameters is capable of capturing nonlinear effects neglected by other linear models, and therefore can be applied to improve maneuvering performance and expand the operating envelope for submerged vessels operating in elevated sea states. To begin, a first principles Lagrangian nonlinear maneuvering (LNM) model for a surface-affected submerged vessel derived by using Lagrangian mechanics cite{BattistaPhD2018} is reformulated to allow the application of data from a medium fidelity potential flow code. In the reformulation process, the order of integration and differentiation in the integro-differential parameters are switched and partial derivatives of the Lagrangian function are computed with readily available data from the panel code solution. As a result, all model parameters can be computed individually using the panel code, wherein the need for additional numerical discretization is circumvented in the computation process through use of solutions already performed by the basic panel code, enabling higher accuracy and lower computational cost. Furthermore, incident wave effects are incorporated into the reformulated LNM model to yield a Lagrangian nonlinear maneuvering and seakeeping (LNMS) model. The LNMS model is numerically validated by confirming the proposed methods and by comparing steady and unsteady hydrodynamic force calculations from the LNMS model against panel code computations for various vessel motions in calm water and in plane progressive waves. Finally, methods for computing physically intuitive components of the model parameters, as well as methods for making approximations of the terms accounting for memory effects are presented, leading to a model formulation amenable to control design. By applying the methods proposed in this dissertation, each and every parameter of the Lagrangian mechanical system model of a submerged vessel maneuvering in waves can be obtained accurately and with computational efficiency by using a potential flow panel code. The resulting nonlinear motion model provides higher model fidelity than existing unified maneuvering and seakeeping models, especially in applications such as nonlinear control design and simulation. / Doctor of Philosophy / A unified maneuvering and seakeeping model for a submerged vessel maneuvering near waves describes mathematically the relationship between input values to the dynamical system, such as thrust from the propulsors, and output values from the system, such as the position and orientation of the vessel. This unified model has a wide range of applications, ranging from vessel hull form optimization in the early design phase to motion controller tuning after the vessel has been constructed. In order for a unified model to make accurate predictions, for instance, for a submerged vessel making a rapid turn near large waves, nonlinear effects have to be included in the model formulation. To that end, a nonlinear motion model for a marine craft affected by a free surface has been developed using Lagrangian mechanics. This dissertation describes an approach for determining the parameters of the nonlinear motion model using a potential flow panel code, which is originally designed to determine flow velocity of the fluid and pressure distribution over marine vessels. The nonlinear motion model is reformulated and the software implementation is modified to support parameter computations. In addition, the methods are numerically validated by comparing computations using the model against solutions output by the panel code. Compared to traditional parameter estimation approaches, the proposed methods allow for a more accurate and efficient determination of parameters of the nonlinear potential flow model for a submerged vessel operating near waves. The resulting Lagrangian nonlinear maneuvering and seakeeping (LNMS) model with determined parameters is able to capture critical nonlinear effects and has applications such as nonlinear control design, rapid design optimization and training simulator development.

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Ce travail porte sur l'étude du comportement rhéologique de fluide en milieu confiné. Pour cela le levier d'un microscope à force atomique (AFM) est utilisé pour sonder les propriétés rhéologiques d'un fluide confiné entre deux surfaces : la surface d'une sphère collée à l'extrémité du levier et une surface plane sur lequel le fluide est déposé. Le dispositif expérimental est constitué du système de mesure d'un AFM et d'un piézoélectrique permettant d'approcher ou d'éloigner de la sphère la surface plane. Un modèle analytique permet d'extraire les propriétés rhéologiques du fluide confiné à partir de la déflexion du levier induite par le pincement du fluide. Cette méthode a été validée pour les fluides newtoniens. Par contre pour les fluides non-newtoniens comme par exemple la solution de polyacrylami de nous avons trouvé que la viscosité dépend de la distance D et que le cisaillement n'est pas le seul paramètre pertinent pour interpréter les propriétés rhéologiques. / This thesis focuses on the study of the rheological behavior of confined fluids. For this purpose, the microcantilever of an atomic force microscope (AFM) is used to probe the rheological properties of a fluid confined between two surfaces, the surface of a sphere glued to the free-end of the AFM microcantilever and a flat solid surface on which the fluid is deposited. The set-up consists of an AFM, an electrical system for the deflection measurement and a piezoelectric device to move the solid surface (approach, oscillation, etc.). An analytical model allows to determine the rheological properties of the confined fluid from the measurement of the microcantilever deflection due to the hydrodynamic force exerted by the fluid on the sphere.This method has been validated for Newtonian fluids. For non-Newtonian fluids, such as polyacrylamide solution, we found that the viscosity depends on the distance D between the sphere and the plane surface and the shear rate is not the only relevant parameter for interpreting the rheological properties.

La nano-organisation de la membrane cellulaire est essentielle à la régulation de certaines fonctions cellulaires. Dans cette thèse, les récepteurs EGF, CPεT et de la transferrine ont été marqués avec des nanoparticules luminescentes et ont été suivis à la fois dans leur environnement local dans la membrane cellulaire vivantes pour de longues durées et sous un flux hydrodynamique. Nous avons alors appliqué des techniques d'inférence bayésienne, d’arbre de décision et de clustering de données extraire des informations quantitatives sur les paramètres caractéristiques du mouvement des récepteurs, notamment la forme de leur confinement dans des microdomaines. L’application d’une force hydrodynamique sur les nanoparticules nous a alors permis de sonder les interactions auxquelles ces récepteurs sont soumis. Nous avons appliqué cette approche in vitro pour favoriser et mesurer la dissociation in vitro de paires récepteur / ligand à haute affinité entre des récepteurs membranaires et leurs ligands pharmaceutiques, telles que HB-EGF et DTR et l’avons ensuite appliqué à l’étude d’interactions à la membrane cellulaire. Nous avons ainsi mis en évidence trois modes différents d'organisation de la membrane et de confinement des récepteurs: le confinement de CPεTR est déterminé par l'interaction entre les récepteurs et les constituants lipidiques / protéiques des microdomaines, le potentiel de confinement de l'EGFR résulte de l'interaction avec les lipides et les protéines de l’environnement du radeau et de l’interaction avec la F-actine; les récepteurs de la transferrine diffusent librement dans la membrane, uniquement limités stériquement par des barrières d’actine, selon le modèle ‘picket-and-fence’. Nous avons de plus montré que les nanodomaines de type radeau sont rattachés au cytoskelette d’actine. Ce travail présente donc à la fois un aperçu quantitatif du récepteur membranaire, des mécanismes d’organisation à l’échelle nanométrique, et établit un cadre méthodologique avec lequel différents types de propriétés membranaires peuvent être étudiés. / In this thesis, EGF, CPεT and transferrin receptors were labeled with luminescent nanoparticles, , and were tracked both in their local environment in the cell membrane and under a hydrodynamic flow. Bayesian inference, Bayesian decision tree, and data clustering techniques can then be applied to obtain quantitative information on the receptor motion parameters. Furthermore, we introduced hydrodynamic force application in vitro to study biomolecule dissociation between membrane receptors and their pharmaceutical ligands in high affinity receptor- ligand pairs, such as HB-EGF and DTR. Finally, three different modes of membrane organization and receptor confinement were revealed: the confinement of CPεTR is determined by the interaction between the receptors and the lipid/protein constituents of the raft; the confining potential of EGFR results from the interaction with lipids and proteins of the raft environment and from the interaction with F-actin; transferrin receptors diffuse freely in the membrane, only sterically limited by actin barriers, according to the “picket-and-fence” model. We moreover showed that all raft nanodomains are attached to the actin cytoskeleton.