Smoothed Particle Hydrodynamics (SPH) is a Lagrangian-based numerical method used for simulating problems in fluid and solid mechanics. In this thesis, a basic introduction to particle and Smoothed Particle (SP) approximations is given first. Application of SP approximations to Euler and Navier-Stokes equations is discussed, followed by an improvement to restore first order consistency in SPH. Then, simulations of 2D free-surface waves in a weakly incompressible fluid are conducted. If the artificial viscosity used is small, results indicate that the accuracy of SPH scheme is reasonably good; however, a low artificial viscosity leads to a rugged air-water interface. Furthermore, application of the LES filter has negligible effects. It is also observed that the use of Renormalized SPH (R-SPH) increases diffusivity but does not increase accuracy significantly. Hence, for 2D surface waves in weakly incompressible fluids, basic SPH formulation without any modification is as good as the R-SPH or LES-SPH methods.

Surface tension of a polymer melt in a supercritical fluid is a principal factor in determining cell nucleation and growth in polymer microcellular foaming. Previous work has presented the surface tension of the amorphous polymer, polystyrene (PS), in supercritical CO2 determined by Axisymmetric Drop Shape Analysis-Profile (ADSA-P), together with theoretical calculations for a corresponding system. The dependences of the surface tension on temperature, pressure and polymer molecular weight were discussed and the physical mechanisms for three main experimental trends were explained using Self Consistent Field Theory (SCFT). This thesis introduces recent work on the surface tension measurement of the crystalline polymer, high density polyethylene (HDPE), in supercritical N2 under various temperatures and pressures. The surface tension was determined by ADSA-P and the results were compared with those of the amorphous polymer PS. The dependence of the surface tension on temperature and pressure, at temperatures above the HDPE melting point, ~125°C, was found to be similar to that of PS; that is, the surface tension decreased with increasing temperature and pressure. Below 125°C and above 100°C, HDPE underwent a process of crystallization, where the surface tension dependence on temperature was different from that above the melting point, i.e., decreased with decreasing temperature. Differential Scanning Calorimetry (DSC) characterization of the polymer was carried out to reveal the process of HDPE crystallization and relate this to the surface tension behavior. It was found that the amount of the decrease in surface tension was related to the rate of temperature change and hence the extent of polymer crystallization. In the second part of the thesis, surface tension dependences on temperature, pressure and clay concentrations were studied for HDPE nano-clay composites (HNC) and compared with pure HDPE. It was found the trends with temperature and pressure were the same with PS in CO2 and HDPE in N2; that is, the surface tension decreased with increasing temperature and pressure. In all nanocomposite samples, the surface tension decreased compared with pure HDPE. This could be a good explanation for the better polymer foaming quality with the addition of clay in the polymer. A minimum surface tension was found with the sample at ~3% concentration of clay. The degree of crystallinity of HNC was analyzed by Differential Scanning Calorimetry (DSC) at different clay concentrations. A minimumz crystallinity was also found at the clay concentration of 3%. The possible relationship between surface tension and polymer crystallinity was discussed.

Current understanding of sensitivity and sensation experienced across the ocular surface remains limited. This project explored the regional variation of corneal sensitivity and transducer function, interaction of sensory and autonomic nerves in the lacrimal functional unit, and the ocular surface sensitivity in Dry Eye and with silicone hydrogel (SH) lens wear. Experiments were undertaken, using Belmonte esthesiometer to deliver pneumatic mechanical, chemical and thermal stimuli and Cochet-Bonnet esthesiometer for tactile stimuli, to the cornea and conjunctiva. Psychophysical methods were used to determine the thresholds of stimulus detection, and the magnitude of sensations to suprathreshold stimulation was estimated assuming Steven’s power law. Additionally, tear secretion in response to corneal sensory input was determined by tear meniscus height measured using Optical Coherence Tomography. Sensitivity to pneumatic cool and mechanical stimuli varied slightly across the cornea while chemical sensitivity was not different between regions. The transducer function was also similar between central and peripheral cornea but different between stimulus modalities. In comparison, the reflex tearing response to suprathreshold stimuli was greater with central corneal stimulation. Also, corneal and conjunctival hypersensitivity was found in the dry eye symptomatic group, and it appeared to be associated with symptom severity, tear film stability and corneal epitheliopathy. Refitting with SH lenses after an initial no-lens interval led to increased conjunctival pneumatic mechanical sensitivity, while corneal tactile sensitivity showed a decrease. In addition, corneal staining induced by certain lens-solution combination appeared to be accompanied by increased corneal and conjunctival sensitivity. In conclusion, the position-invariant corneal sensitivity to pneumatic mechanical, chemical and thermal stimuli suggests that the distribution of human corneal sensory fibres may be more homogeneous than previously hypothesised. The mechanisms mediating the sensory aspect of corneal nociception may be similar across the cornea, while, perhaps due to the importance of the visual axis, the tear reflex response to central and peripheral cornea seems to be driven by different neural circuitry, perhaps at the higher levels of the sensory processing pathway. It appears that alteration in sensory processing of the ocular surface occurs in Dry Eye and accompanies SH lens-solution-induced corneal staining. This altered sensitivity seems to be more prominent in the conjunctiva than in the cornea.

Storytelling is a powerful means of communication that has been employed by humankind from the early stages of development. As technology has advanced, the medium through which people tell stories has evolved from verbal, to writing, performing on stage, and more recently television, movies, and video games. A promising medium for the telling of stories in an in-person, one-on-one or one-to-many setting is a digital table—a large, horizontal multi-touch surface—that can provide quick access to visuals and narrative elements at the touch of one’s hands and fingers. In this work, I present the results of an exploratory study on storytellers’ interaction behaviours while working with digital tables, and its physical counterparts of sand and water. My results highlight some of the differences in these media that can both help and hinder a storyteller’s narrative process. I use these findings to present design implications for the design of applications for storytelling on digital multi-touch surfaces.

Today, manual polishing is the most common method to improve the surface finish of mould and dies for e.g. plastic injection moulding, although it is a cumbersome and time-consuming process. Therefore, automated robots are being developed in order to speed up and secure the final result of this important final process. The purpose of this thesis is to find out some clues about the influence of different parameters for the polishing of a steel grade called Mirrax ESR (Uddeholm Tooling AB) using a Design of Experiment. The report starts with a brief description of mechanical polishing (the techniques and polishing mechanisms) and ends up with the optimization of the polishing procedure with a polishing machine, the Strecon RAP-200 made by Strecon A/S. Even if all the runs of the Design of Experiments couldn’t be carried out, the surfaces studied revealed some information about the importance of the previous process (turning marks not removed) and about the link between the aspect of the surfaces and the roughness parameters.

Pressure sensitive adhesive surfaces are often inspired by nature. Miming the toe-surface of gecko, engineered surfaces made of thousands of micro-pillars show promising adhesive properties. This surfaces, covered with cylindrical pillars arranged into a pattern have adhesive properties greatly dependent on the geometrical characteristics. In this thesis, have been studied successively two models of micro-patterned surfaces, one two-dimensional, the other in three-dimensional using a FEM tool. Varying geometry parameters, has been determined optimal geometries to improve adhesive strength on these biomimetic, micropatterned surfaces. This study concludes to the non-adaptability of one-level scale micropatterned surface to large area of adhesion, to the strong advantage from the point of adhesion per contact area for high aspect ratio at each level of the geometry and study the opportunity of hierarchical structures. Some further suggestions of improvements to adhesion properties are discussed in the final chapter.

Cell surface properties are crucial to the mechanisms by which groups of cells organize themselves during embryogenesis, cancer metastases and tissue engineering. Measured surface tension values provide a quantitative basis for predicting a range of cell behaviors including sorting of embryonic cells, self-organization of pancreatic islet cells and invasive potential of tumor cells. Tissue surface tensions are a measurement of the tension that acts along the interface between a cell aggregate and its surrounding media and it is typically measured by compressing an aggregate of cells. In this study a novel apparatus is used to measure the surface tensions of aggregated embryonic chick cells from heart, liver, neural retina and mesencephalon tissues. These surface tension values are consistent with the known engulfment behavior of the cells involved and are in close agreement with measurements made previously by other means. It has been suggested that surface tensions and cell rearrangement patterns are a direct result of adhesion forces between cells arising from cadherins. However, cadherin binding alone is insufficient to account for observed engulfment phenomena and recent experimental evidence suggests that actin dynamics are involved. A cell surface property referred to as interfacial tension or cortical tension takes into account both adhesion forces and forces derived from actin microfilaments and could shed new light on the mechanisms involved in cell interactions. Computer simulations indicate that the interfacial tension between cells can be measured through a modified compression test experiment. In this cell aggregate compression study, cell shapes as well as the aggregate profile are measured in addition to the compression force in attempts to measure cell interfacial tensions.

Since the advent of the industrial era atmospheric concentrations of greenhouse gases have been on the rise leading to increasing global mean temperatures. Through increasing temperatures and changes to distributions of precipitation, climate change will intensify the hydrologic cycle which will directly impact surface water sources while the impacts to groundwater are reflected through changes in recharge to the water table. The IPCC (2001) reports that limited investigations have been conducted regarding the impacts of climate change to groundwater resources. The complexity of evaluating the hydrologic impacts of climate change requires the use of a numerical model. This thesis investigates the state of the science of conjunctive surface-subsurface water modeling with the aim of determining a suitable approach for conducting long-term transient simulations at the watershed scale. As a result of this investigation, a coupled modeling approach is adopted using HELP3 to simulate surface and vadose zone processes and HydroSphere to simulate saturated flow of groundwater. This approach is applied to the Alder Creek Watershed, which is a subwatershed of the Grand River Watershed and located near Kitchener-Waterloo, Ontario. The Alder Creek Watershed is a suitable case study for the evaluation of climate change scenarios as it has been well characterized from previous studies and it is relatively small in size. Two contrasting scenarios of climate change (i.e., drier and wetter futures) are evaluated relative to a reference scenario that is based on the historical climatic record of the region. The simulation results show a strong impact upon the timing of hydrologic processes, shifting the spring snow melt to earlier in the year leading to an overall decrease in runoff and increase in infiltration for both drier and wetter future climate scenarios. Both climate change scenarios showed a marked increase to overall evapotranspiration which is most pronounced in the summer months. The impacts to groundwater are more subdued relative to surface water. This is attributed to the climate forcing perturbations being attenuated by the shift of the spring snow melt and the transient storage effects of the vadose zone, which can be significant given the hummocky terrain of the region. The simulation results show a small overall rise of groundwater elevations resulting from the simulated increase in infiltration for both climate change scenarios.

When interpolating a data mesh using triangular Bézier patches, the requirement of C¹ or G¹ continuity imposes strict constraints on the control points of adjacent patches. However, fulfillment of these continuity constraints cannot guarantee that the resulting surfaces have good shape. This thesis presents an approach to constructing surfaces with approximate C¹/G¹ continuity, where a small amount of discontinuity is allowed between surface normals of adjacent patches. For all the schemes presented in this thesis, although the resulting surface has C¹/G¹ continuity at the data vertices, I only require approximate C¹/G¹ continuity along data triangle boundaries so as to lower the patch degree. For functional data, a cubic interpolating scheme with approximate C¹ continuity is presented. In this scheme, one cubic patch will be constructed for each data triangle and upper bounds are provided for the normal discontinuity across patch boundaries. For a triangular mesh of arbitrary topology, two interpolating parametric schemes are devised. For each data triangle, the first scheme performs a domain split and constructs three cubic micro-patches; the second scheme constructs one quintic patch for each data triangle. To reduce the normal discontinuity, neighboring patches across data triangle boundaries are adjusted to have identical normals at the middle point of the common boundary. The upper bounds for the normal discontinuity between two parametric patches are also derived for the resulting approximate G¹ surface. In most cases, the resulting surfaces with approximate continuity have the same level of visual smoothness and in some cases better shape quality.

The dissociative adsorption of three carboxylic acids (acetic acid, propanoic acid, and acrylic acid), allyl alcohol, and allyl aldehyde on Si(100)2×1 at room temperature has been investigated by X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD), as well as density-functional theory (DFT) calculations. The C 1s features obtained by XPS measurement for acetic acid, propanoic acid, and acrylic acid show that formation of bidentate carboxylate at a low exposure is followed by that of unidentate carboxylate at a higher exposure, with approximately equal population for both adstructures. The signatures of C 1s features attributed to methyl (285.7 eV), ethyl (285.3 eV), ethenyl (285.0 eV), and bidentate carboxyl (286.8 eV) and unidentate carboxyl (289.8-289.3 eV) carbons were observed for the studied carboxylic acids. The results showed that the carboxyl group is more reactive than the alkyl or alkenyl group towards the Si(100)2×1 surface, with O−H dissociation preferred over [2+2] C=C cycloaddition and the other plausible reaction products. This was also supported by our DFT calculation which showed that the bidentate carboxylate adstructure is the most stable configuration among the calculated adstructures for the aforementioned carboxylic acids. The combined temperature-dependent XPS and TPD studies provided strong evidence for the formation of ketene, acetaldehyde and CO from acetic acid, CO and ethylene from propanoic acid, and CO, ethylene, acetylene, and propene from acrylic acid. Furthermore, the TPD results provided further evidence for the preferred structure of the adsorbate from each of the carboxylic acid on the surface. In addition to carboxyl group, reactivity of the hydroxyl and carbonyl functional groups relative to that of ethenyl group was studied by investigating the reaction of allyl alcohol and allyl aldehyde on Si(100)2×1 at room temperature. The C 1s XPS results supported O−H dissociation for allyl alcohol and [2+2] C=O cycloaddition for allyl aldehyde over the [2+2] C=C cycloaddition. The similarity between the observed C 1s features for allyl alcohol and allyl aldehyde helped to identify the structure of the adsorption products of these two molecules on the surface. The presence of the related C 1s feature of C=C for allyl alcohol and allyl aldehyde, and the absence of C 1s feature of C=O for allyl aldehyde provided strong evidence to support that [2+2] C=C cycloaddition does not occur in the presence of hydroxyl or carbonyl groups. Furthermore, by comparing the experimental results and the adsorption energies of the adstructures calculated by DFT, it was concluded that these molecules do not react with the Si dimers through both of their functional groups, while the reaction of only one of the two functional groups is preferred on the surface. Formation of ethylene, acetylene, and propene from allyl alcohol and allyl aldehyde, simultaneously to CO from allyl alcohol, was concluded from the corresponding TPD results, which also confirm the structure of the adsorbates on the surface. The present research shows that reactions involving oxygen-containing functional groups are favoured over the other plausible reactions including [2+2] C=C cycloaddition on the Si(100)2×1. The preference of the surface to react with one of the two functional groups calls for future studies for the selective functionalization of Si(100)2×1 with potential applications in molecular electronics.