The epoxidation of a series of α,β-unsaturated esters by dimethyldioxirane was studied. Second order rate constants were determined under pseudo first order conditions. The epoxide of each ester upon full conversion was found to be the only isolable product. Second order rate constants for the cis-like ethyl tiglate showed a 4 fold increase over that of trans-like angelic methyl ester. The ester substituent was found to have little effect on overall rate constants. A comparison of a relatively strained cyclopentene carboxylate to the cyclohexene carboxylate showed a 2 fold increase in selectivity for the former. Ethyl methacrylate displayed unexpected reactivity toward dioxirane; undergoing reaction faster than more substituted electron rich alkenes. Computer modeling studies using the AM-1 and density functional approaches were carried out to gain insights into the mechanistic aspects of the reaction. The esters in general favored the S-cis conformation or were evenly distributed among S-cis and S-trans except for the ethyl methacrylate case. The AM-1 approach did not predict the reactivity of open chain esters. The density functional approach predicted the relative reactivity of seven of the nine esters but could not predict the reactivity when the R1 group was substituted. One possible explanation is that the computer model predicts the methyl groups of the dioxirane to be positioned over the R1 group in the lowest energy of all other esters, but steric clash prevents this for angelic methyl ester and ethyl 3,3 dimethyl acrylate.

The virtual worlds of Computer Graphics are populated by geometric objects, called models. Researchers have addressed the problem of synthesizing models automatically. Traditional modeling approaches often require a user to guide the synthesis process and to look after the geometry being synthesized, but user attention is expensive, and reducing user interaction is therefore desirable. I present a scheme for the automatic creation of geometry by deforming surfaces. My scheme includes a novel surface representation; it is an explicit representation consisting of points and edges, but it is not a traditional polygonal mesh. The novel surface representation is paired with a resampling policy to control the surface density and its evolution during deformation. The surface deforms with velocities assigned to its points through a set of deformation operators. Deformation operators avoid the manual computation and assignment of velocities, the operators allow a user to interactively assign velocities with minimal effort. Additionally, Petri nets are used to automatically deform a surface by mimicking a user assigning deformation operators. Furthermore, I present an algorithm to translate from the novel surface representations to a polygonal mesh. I demonstrate the utility of my model generation scheme with a gallery of models created automatically. The scheme's surface representation and resampling policy enables a surface to deform without requiring a user to control the deformation; self-intersections and hole creation are automatically prevented. The generated models show that my scheme is well suited to create organic-like models, whose surfaces have smooth transitions between surface features, but can also produce other kinds of models. My scheme allows a user to automatically generate varied instances of richly detailed models with minimal user interaction.

Tissue engineering is an emerging area with an aim to create artificial tissues or organs by employing methods of biology, engineering and material science. In tissue engineering, scaffolds are three-dimensional (3D) structure made from biomaterials with highly interconnected pore networks or microstructure, and are used to provide the mechanical and biological cues to guide cell differentiation in order to form desired three-dimensional tissues or functional organs. Hence, tissue scaffold plays a critical role in tissue engineering. However, fabrication of such scaffolds has proven to be a challenge task. One important barrier is the inability to fabricate scaffolds with designed pore size and porosity to mimic the microstructure of native tissue. Another issue is the prediction of process-induced cell damage in the cell-involved scaffold fabrication processes. By addressing these key issues involved in the scaffold fabrication, this research work is aimed at developing methods and models to represent the dispensing-based solid free form scaffold fabrication process with and without the presence of living cells.<p> The microstructure of scaffolds, featured by the pore size and porosity, has shown to significantly affect the biological and mechanical properties of formed tissues. As such, during fabrication process the ability to predict and determine scaffold pore size and porosity is of great importance. In the first part of this research, the flow behaviours of the scaffold materials were investigated and a model of the flow rate of material dispensed during the scaffold fabrication was developed. On this basis, the pore size and porosity of the scaffolds fabricated were represented by developing a mathematical model. Scaffold fabrication experiments using colloidal gels with different hydroxylapatite volume fractions were carried out and the results obtained agreed with those from model simulations, indicating the effectiveness of the models developed. The availability of these models makes it possible to control the scaffold fabrication process rigorously, instead of relying upon a trial and error process as previously reported.<p> In the scaffold fabrication process with the presence of living cells, cells are continuously subjected to mechanical forces. If the forces exceed certain level and/or the forces are applied beyond certain time periods, cell damage may result. In the second part of this research, a method to quantify the cell damage in the bio-dispensing process is developed. This method consists of two steps: one step is to establish cell damage models or laws to relate cell damage to the hydrostatic pressure / shear stress that is applied on cells; and the second step is to represent the process-induced forces that cells experience during the bio-dispensing process and then apply the established cell damage law to model the percent cell damage in the process. Based on the developed method, the cell damage percents in the scaffold fabrication processes that employ two types of dispensing needles, i.e., tapered and cylindrical needles, respectively, were investigated and compared. Also, the difference in cell damage under the high and low shear stress conditions was investigated, and a method was developed to establish the cell damage law directly from the bio-dispensing process. To validate the aforementioned methods and models, experiments of fabricating scaffolds incorporating Schwann cells or 3T3 fibroblasts were carried out and the percent cell damage were measured and compared with the simulation results. The validated models allow one to determine of the influence of process parameters, such as the air pressure applied to the process and the needle geometry, on cell damage and then optimize these values to preserve cell viability and/or achieve the desired cell distribution within the scaffolds.

The aim of this thesis was to develop a new energy model that predicts the energy infrastructure required to maintain the oil production in the Oil Sands operation at minimum cost. Previous studies in this area have focused on the energy infrastructure for fixed energy demands, i.e., the production schemes that produce synthetic crude oil (SCO) and commercial diluted bitumen remained fixed in the optimal infrastructure calculation. The key novelty of this work is that the model searches simultaneously for the most suitable set of oil production schemes and the corresponding energy infrastructures that satisfy the total production demands under environmental constraints, i.e., CO2 emissions targets. The proposed modeling tool was validated using historical data and previous simulations studies for the Oil Sands operation in 2003. Likewise, the proposed model was used to study the 2020 Oil Sands operations under three different production scenarios. Also, the 2020 case study was used to show the effect of CO2 capture constraints on the oil production schemes and the energy producers. The results show that the proposed model is a practical tool to determine the production costs for the Oil Sands operations, evaluate future production schemes and energy demands scenarios, and identify the key parameters that affect the Oil Sands operation

Worldwide, multiple countries are investing a great deal of time and energy towards developing a new class of technologically advanced nuclear reactors. These new reactors have come to be known as the Generation IV (Gen IV) class of nuclear reactors. Similarly to the other designs, the Gas Fast Reactor (GFR) has many advantages, such as electricity production at high efficiency, hydrogen production, minor actinide burning capabilities, etc. However, there are currently no immediate plans to build a GFR due to uncertainties regarding safety issues. The study conducted herein contains input techniques for the development of new neutronic and thermal hydraulic input decks for the United States (US) Department of Energy (DOE) GFR design. The Monte Carlo N-Particle (MCNP) and MELCOR codes are used to model neutronic and thermal hydraulic characteristics, respectively. These codes are used with the intention of gaining further insight into GFR design and steady state operating characteristics of the US DOE GFR. Descriptions of inputs for all input decks, along with the results of the execution of both input decks can be found in this thesis. Although many alterations are made to original design specifications, results found in this thesis support the design modifications that have been made. Results suggest that steady-state operation of the GFR is a plausible possibility, given the right conditions. The lack of design criteria for both the reflector and borated shield regions imposes a necessity of invention upon all those who seek to clarify design criteria for the US DOE GFR. Furthermore, resulting temperature profiles for the fuel, cladding and coolant give rise to the possibility of the design of a system, based on thermionic principles, that converts core thermal energy directly to electricity. Such a system is envisioned to provide electricity to a decay heat removal system and possibly increase plant efficiency.

Tillage erosion is a major contributor to the total soil erosion in cultivated topographically complex lands. No study has been carried out on tillage erosion associated with cereal-based production systems in the Canadian Prairies, and there is a need to examine tillage erosivity of secondary tillage and seeding implements and the effect of slope curvature on tillage translocation. With both tillage and water erosion occurring in a cultivated topographically complex landscape, it is valuable to investigate the relative contributions of and the possible linkage and interactions between these two erosion processes. Tillage translocation causes the mixture of subsoil into the till-layer, which may considerably affect soil properties and therefore the related biophysical processes. In this study, using plot tracers, we examined tillage translocation caused by four tillage implements: air-seeder, spring-tooth-harrow, light-cultivator and deep-tiller in southern Manitoba, Canada. We determined that secondary tillage and seeding implements could be as erosive as primary tillage implements in a cereal-based production system. In the majority of cases, tillage translocation could be explained by slope gradient alone; however, slope curvature also significantly affected tillage translocation. In two field sites in the North America Great Plains (NAGP), measured 137Cs inventories were converted into total soil erosion rates. Tillage and water erosion rates were estimated using models. The comparisons of the model estimates to 137Cs estimates showed that both tillage and water erosion significantly contributed to the total soil erosion in undulating slopes while tillage erosion was the predominant erosion process in hummocky hilltops. The contributions of and the linkage and interactions between water and tillage erosion showed predictable patterns in different landform elements, with the knowledge of which, landscape segmentation could be used to assess the potential of soil erosion. Further investigation of tillage translocation was demonstrated with four hypothetic landscapes: plane slope, symmetric hill, asymmetric hill and irregular hill, and is tested against field data. A Visual Basic coded program (TillTM) was developed to simulate the redistribution of soil constituents and soil mass. We determined that the pattern of soil mass redistribution was dependent on topography, while the pattern of soil constituent redistribution was affect by topographic features, tillage patterns and temporal scales. / February 2007

A critical step in mounting an immune response is antigen recognition by T cells. This step proceeds by productive interactions between T cell receptors (TCR) on the surface of T cells and foreign antigen, in the form of peptide-major-histocompatibility-complexes (pMHC), on the surface of antigen-presenting-cells (APC). Antigen recognition is exceedingly difficult to understand because the vast majority of pMHC on APCs are derived from self-proteins. Nevertheless, T cells have been shown to be exquisitely sensitive, responding to as few as 10 antigenic pMHC in an ocean of tens of thousands of self pMHC. In addition, T cells are extremely specific and respond only to a small subset of pMHC by virtue of their specific TCR. To explain the sensitivity of T cells to pMHC it has been proposed that a single pMHC may serially bind multiple TCRs. Integrating present knowledge on the spatial-temporal dynamics of TCR/pMHC in the T cell-APC contact interface, we have constructed mathematical models to investigate the degree of TCR serial engagements by pMHC. In addition to reactions within clusters, the models capture the formation and mobility of TCR clusters. We find that a single pMHC serially binds a substantial number of TCRs in a TCR cluster only if the TCR/pMHC bond is stabilized by coreceptors and/or pMHC dimerization. In a separate study we propose that serial engagements can explain T cell specificity. Using Monte Carlo simulations, we show that the stochastic nature of TCR/pMHC interactions means that multiple binding events are needed for accurate detection of foreign pMHC. Critical to our studies are estimates of TCR/pMHC reaction rates and mobilities. In the second half of the thesis, we show that Fluorescence Recovery After Photobleaching (FRAP) experiments can reveal effective diffusion coefficients. We then show, using asymptotic analysis and model fitting, that FRAP experiments can be used to estimate reaction rates between cell surface proteins, like TCR/pMHC. Lastly, we use FRAP experiments to investigate how the actin cytoskeleton modulates TCR mobility and report effective reaction rates between TCR and the cytoskeleton.

Patterns are used as building blocks for design and construction in many fields such as architecture, music, literature, etc. Researchers and practitioners in the information systems area have been exploring patterns and using them in system analysis and design. Patterns found in the analysis stage, when analysts create conceptual models to abstractly represent domain reality, are call business patterns or analysis patterns. Although various business patterns were proposed in previous studies, we found that business semantics were missing in these patterns. These business patterns failed to show functionalities that is essential to patterns in general. Most of these patterns were also not capable of describing business activities, the dynamic aspect of business. This study is conducted to address these issues. In this thesis, we provide a brief literature review on business patterns, and discuss the major problems we found in these studies. Then we introduce our research approach and the major outcomes. We propose a new definition of business patterns with business semantics, which enables us to recover the missing functionality in business patterns. We suggest the key elements to represent business patterns, and propose a two-level template (functional and operational) to describe these elements. Based on theR²M approach, we propose a modeling method with graphical notations to describe the operational level of patterns, where business activities can be modeled. Examples and a case study are provided in this thesis to demonstrate how to use the modeling method and how to use business patterns in practice.

No description available.

Energy consumption has been increasing rapidly over the last few decades. In 2003, Ontario’s energy needs were in the order of 155.1 TWh and are expected to increase to 168.9 TWh by 2014. This will create an increased demand for power generation, electricity distribution, resources, as well as the generation of pollution. Thus, there is a requirement for infrastructure renewal and expansion within a sustainable energy management framework. With respect to stationary power requirements, there are many solutions available such as consumption reduction and overall energy efficient. Demand side management and energy conservation will mitigate the problem, is it likely that more power generation will be required. A distributed generation system is most desirable as there is relief for the electricity distribution grid. Key to this study is the examination of the potential for the distributed energy system to produce electricity for the facility while also producing hydrogen to support a small fleet of vehicles for use at the facility, demonstrating an integrated energy system. The results for the fleet of vehicles are preliminary only, while most of the focus was put into the energy system of the facility. The application of this distributed system will be in the commercial/industrial sector where a technology center will be the primary load while supplying power to the grid when excess power is generated. There are many sources of distributed energy available to be used in distributed generation systems ranging from diesel generators to wind turbines, the various green generation technologies have been evaluated during this study. The evaluation takes into account cost, efficiency, size, and availability. This study has shown that such a facility can produce emissions free distributed electricity in a Net Zero manner with an electrical grid connection, as well as economically support refuelling a fleet of hydrogen fuel cell vehicles. The selected systems have been modeled and sized to demonstrate operating conditions and assess the energy/power flow. Different scenarios were simulated to show how the system will react to intermittent environmental conditions, such as wind speed.