In this thesis, PN simulations of drying are compared with experimentally obtained data fromdrying of a representative 2D microfluidic network in SiO2 under varying thermal conditions withthe aim to identify governing physical pore scale effects. Gravity and viscous effects aredisregarded in this thesis. Instead drying with slight local temperature variation and drying withimposed thermal gradients are studied. Based on this investigation, a powerful non-isothermalPNM is developed. This model incorporates i) the phenomena associated with the temperaturedependency of pore scale invasion, namely thermally affected capillary invasion and vapor flow aswell as ii) the secondary effects induced by wetting liquid films of different morphology. This studyclearly evidences that the macroscopic drying behavior is fundamentally dictated by thetemperature gradient imposed on the PN and moreover by the secondary capillary invasion aswell. In agreement with literature, invasion patterns as in invasion percolation with progressiveevaporation of single clusters are observed in drying with negligible local temperature variation;gradients with temperature decreasing from the surface (negative temperature gradient) canstabilize the drying front, evolving between the invading gas phase and the receding liquid phase,whereas temperature increasing from the surface (positive temperature gradient) leads todestabilization of the liquid phase with early breakthrough of a gas branch and initiation of asecond invasion front migrating in opposite direction to the evaporation front receding from theopen surface of the PN. Special attention is paid on the distinct drying regimes found in thesituation of a positive gradient because they are associated with different pore scale invasionprocesses. More precisely, temperature dependency of surface tension dictates the order ofinvasion as long as the liquid phase is connected in a main liquid cluster (usually found during thefirst period of drying). In contrast to this, detailed study of the vapor transfer mechanismsemphasizes that vapor diffusion through the partially saturated region can control the pore leveldistributions of liquid and gas phase during the period of drying when the liquid phase isdisconnected into small clusters. This is also related to the cluster growth induced by partialcondensation of vapor. It is shown and discussed in detail in this thesis that this effect not onlydepends on direction and height of the temperature gradient for a given pore size distribution butthat moreover the overall evaporation rate influences the cluster growth mechanism. This indicatesthat liquid migration during drying of porous media might be controlled by the interplay of thermalgradients and drying rate. In summary, the study of thermally affected drying of the 2-dimensionalPN reveals complex pore scale mechanisms, usually also expected in drying of real porous media.This leads to the development of a strong mathematical pore scale model based on experimentalfindings. It is demonstrated how this model might be applied to understand and develop moderndrying processes based on the simulation of thermally affected pore scale mass transfer

One of the impacts of the rising demand for community health services, primarily used by seniors, is that hospitals are often faced with the challenge of having patients finish the acute phase of their treatment and yet are unable to discharge them due to the lack of a bed in a more appropriate community care setting. The frequency of this challenge has led to the designation of “alternative level of care” (ALC) being ascribed to patients who remain in the hospitals due to insufficient capacity downstream. The thesis focuses on a model that seeks to address patient flow through the community care network (CCN) and finding capacity allocation policies for the different facilities that resolves the ALC challenge using scenario analysis. A queuing network model with general routings and nodes’ blocking has been developed and a heuristic approximation method has been employed for solving the model. Blocking probabilities and the number of blocked patients are derived as performance metrics of the CCN. We test the accuracy of the queuing model through a simulation model and the behaviours of the system in different scenarios are investigated in the simulation model and our policy insights and conclusions are provided.

One of the impacts of the rising demand for community health services, primarily used by seniors, is that hospitals are often faced with the challenge of having patients finish the acute phase of their treatment and yet are unable to discharge them due to the lack of a bed in a more appropriate community care setting. The frequency of this challenge has led to the designation of “alternative level of care” (ALC) being ascribed to patients who remain in the hospitals due to insufficient capacity downstream. The thesis focuses on a model that seeks to address patient flow through the community care network (CCN) and finding capacity allocation policies for the different facilities that resolves the ALC challenge using scenario analysis. A queuing network model with general routings and nodes’ blocking has been developed and a heuristic approximation method has been employed for solving the model. Blocking probabilities and the number of blocked patients are derived as performance metrics of the CCN. We test the accuracy of the queuing model through a simulation model and the behaviours of the system in different scenarios are investigated in the simulation model and our policy insights and conclusions are provided.

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Master of Science / Department of Electrical and Computer Engineering / Caterina Maria Scoglio / Japanese Encephalitis (JE) is a vector-borne disease transmitted by mosquitoes and maintained in birds and pigs. An interconnected network model is proposed to examine the possible epidemiology of JE in the USA. Proposed JE model is an individual-level network model that explicitly considers the feral pig population and implicitly considers mosquitoes and birds in specific areas of Florida, North Carolina, and South Carolina. The virus transmission among feral pigs within a small geographic area (<60 sq mi areas) are modeled using two network topologies— fully connected and Erdos-Renyi networks. Connections between locations situated in different states (interstate links) are created with limited probability and based on fall and spring bird migration patterns. Simulation results obtained from the network models support the use of the Erdos-Renyi network because maximum incidence occurs during the fall migration period which is similar to the peak incidence of the closely related West Nile virus (WNV), another virus in the Japanese Encephalitis group (Flaviviridae) that is transmitted by both birds and mosquitoes. Simulation analysis suggested two important mitigation strategies: for low mosquito vectorial capacity, insecticidal spraying of infected areas reduces transmission and limits the outbreak to a single geographic area. Alternatively, in high mosquito vectorial capacity areas, birds rather than mosquitoes need to be removed/controlled.

International container shipping is a complex system of interlocked stakeholders. Obtaining reliable data can be difficult and the data for specific routes and container terminals change over time. Intermodal transportation has increased in importance over the years. A relational database model was developed as a tool for stakeholders interested in analyzing specific paths. The database uses data on transportation time, variance of transportation time, transportation cost and green house gas emissions. The user can specify their own set of locations, movements, containers, items and transportation modes. The total logistics cost of a specific importing strategy can be calculated for any path defined by the user. A Floyd-Warshall algorithm was implemented to allow for the shortest path between locations to be determined, based on the preferences of the user for either cost, time or CO2 emissions. In order to illustrate the capabilities of our model and because of our interest in the port of Halifax, we created a dataset from the distances between important locations within the international container shipping system. Using this dataset, some example calculations indicate that the port of Halifax and the port of Montreal could consider cooperating to form a hub-and-spoke relationship for European imports. In another example, the port of Halifax provides the fastest route for imports using the Suez Canal intending to reach Toronto but the cheapest total logistics cost route involves using the port of NY/NJ. By using both the total logistics cost algorithms and the shortest path algorithms, the examples illustrate how stakeholders in the container transportation industry can analyze various routes, terminals and make informed decisions.

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<p> An existing transient network model for wicked heat pipes was extended to incorporate the effects of axial heat transfer along the wall and wick, heat transfer in the surrounding media, and non-condensable gases in the vapour region. The thermal resistance of the different components was broken down into a larger number of smaller resistances in both axial and radial directions to account for the axial conduction and to handle non-uniform boundary conditions. Two sets of experiments were performed on copper-water wicked heat pipes to evaluate the effect of non-condensable gases, axial conduction, surrounding media and non-uniform boundary conditions. In the first set of experiments, the heat pipes were electrically heated at one end and cooled on the other end using a water jacket. This set of experiments was used to investigate the effect of non-condensable gases, axial conduction and surrounding media on the steady state and transient performance. The effect of the surrounding media was investigated by heating the heat pipe through two different sized aluminum blocks mounted around then heat pipe evaporator section. In the second set of experiments, the effect of using a finned condenser on the steady state performance of the heat pipes were tested in a wind tunnel. The condenser section of the heat pipes in this case was mounted in the test section of the wind tunnel and cooled at different air velocities. Three fin densities were tested along with a heat pipe with no fins. The model predictions of the steady and transient response of the vapour and wall temperature of the heat pipes were in good agreement with the experimental results. </p> <p> The presence of non-condensable gases inside the heat pipe increased the overall thermal resistance of the heat pipe. While the non-condensable gases did not notably affect the transient response during the heat-up phase, it significantly slows down the cool-down phase. The axial conduction through the pipe wall and the wick structure decreases the overall thermal resistance of the heat pipe. The axial conduction did not have a great influence on the time response during the heat-up phase, but was very important in the cooldown phase, especially with the presence of non-condensable gases. The wick structure was found to be the most dominant component in the transient performance of the heat pipe. The evaporator block was the dominant capacitance in the overall conjugate system, and significantly affects the transient response. The experimental results from the finned condenser study showed that the internal resistance increased slightly with the fin density. There was some nonuniformity in the condenser surface temperature at the locations of the fins. However, this non-uniformity did not propagate to other parts of the heat pipe. </p> / Thesis / Master of Applied Science (MASc)

In this thesis, we look at evidence accumulated on the prefrontal cortical and hippocampal regions of the brain and review theories about the possible roles each structure has on human memory and behaviour. Aspects of these theories are tested via a self-reinforcing computational network model. We propose this model may simulate the underlying mechanisms or processes of the prefrontal-hippocampal interaction during performance of memory tasks that require intact prefrontal and hippocampal structures. / Thesis / Master of Science (MSc)