<p>This thesis examines problems in two related subject areas.</p> <p>The first subject area involves the development orthogonal collocation on finite elements (OCFE) models for stagewise distillation processes for use in steady-state optimization. The OCFE model formulation divides the column sections into smaller subdomains (finite elements) in order to track irregularities in the column profiles. Stages that have feed or sidestreams entering or leaving the column are modeled as discrete equilibrium stages in the OCFE model. An adaptive element breakpoint placement procedure determines an element partition for each column section so that a solution of improved accuracy is obtained. The element partition is based on the equidistribution of the material and energy balances residuals around envelopes in the column. OCFE models converge to the same optimal solution as tray-by-tray models in less computational time, but have similar sensitivity at the optimum with respect to major model parameters.</p> <p>The second area involves the study of parametric sensitivity analysis in process optimization. A sensitivity analysis procedure is developed that calculates the behaviour of the optimal solution for changes in one independent parameter using continuation methods. A procedure is proposed to modify the equation set which allows the study of the effects of multiple simultaneous parameter variations along specified directions in the optimal solution. Special attention is given to the detection and analysis of singularities in the optimal solution path caused by violation of either the strict complementarity, linear independence or second-order optimality conditions. The methodology provides information to determine the range of parameter estimate variation for which the active constraint set or the characteristics of the optimal solution remain unchanged. The adjustment of the independent variables in a multiple unit flowsheet, so that optimality is maintail'ed, is investigated in the presence of model parameter variation.</p> / Doctor of Philosophy (PhD)

<p>This thesis addresses a reactive (closed-loop) scheduling framework for integrated<br />scheduling of process operation and maintenance. Ethylene plant furnace scheduling is<br />chosen as the process example because it is concerned with optimally scheduling the<br />furnace operations and its periodic maintenance shutdowns. The main reason for<br />choosing this example is that it addresses a special class of scheduling problems where<br />the operations and maintenance have strong interactions and so integrated decision<br />making becomes necessary.</p> <p>The major goal of this research was to select an appropriate closed-loop<br />framework and develop a reactive scheduling system. With the rolling horizon approach<br />being the most suitable method for closed-loop schedule implementation, a Model<br />Predictive Control (MPC) framework is chosen in this thesis. The presence of integer<br />variables in the scheduling model made the reactive scheduling systems resemble a<br />hybrid MPC problem.</p> <p>The research was performed in two phases. In the first phase, an open-loop<br />scheduling model was formulated as a Mixed Integer Linear programming problem<br />(MILP) using discrete time representation. To ensure the tractability of the model,<br />tailored formulation methods (disjunctive reactor modelling, constraint reformulation and tightening constraints) and efficient solution heuristics (two-stage temporal<br />decomposition heuristic) were developed in this thesis. In the second phase, the openloop scheduling model was applied in the prototype closed-loop framework to develop a reactive scheduling system to assist engineers make appropriate decisions in a timely manner.</p> <p>The automated scheduling system developed in this thesis was tested for several<br />scenarios and proved to have significant benefits over manual scheduling procedures,<br />confirmed that the scheduling model is tractable and achieved feasible solutions for all<br />the scenarios considered, including large problems with multiple feeds, multiple reactors and a long (90-day) scheduling horizon. We conclude that the technology is appropriate for further improvement and eventual application in the industry.</p> / Master of Applied Science (MASc)

<p>This thesis reports on a method for measuring the molecular weight distributions of polyacrylamide - a water-soluble polymer. The method which is turbidimetric titration involves the incremental addition of non-solvent or precipitant to a solution of polymer and encourages aggregation. At each point of the titration, optimum condition was obtained. The optimum condition was defined by proper application of Mie theory of light scattering functions. These scattering coefficients and scattering functions were further investigated over a broad range of particle size. Broad polymers were investigated, as this polymer-polyacrylamide can only be made via free-radical polymerization. The conditions necessary to satisfy the inherent assumptions were specified and justified by the experimental technique. A very high molecular weight polymer was polymerized by free radical polymerization in the presence of an electrolyte. The influence of electrolyte, and the method of mixing were studied.</p> <p>The quality of the distributions and averages obtained by the method was assessed by GPC measurements and viscosity measurements. The method is capable of giving accurately the molecular weight distributions of any polymer in principle, especially when the weight average molecular weight is greater than five million.</p> / Master of Engineering (ME)

<p>The non-isothermal polymerization of styrene under runaway chemically initiated reactions was studied. A system of multiple initiators was used. The experiments were performed in an insulated batch reactor. Experimental temperature and pressure profiles with respect to time were obtained and used to evaluate a mathematical model at high temperatures. Molecular weights and conversion measured by gel-permeation chromatography (GPC) provided further evidence about the adequacy of the model. The behaviour of a non-isothermal polymerization if fully discussed, including such phenomena as depropagation, gel-effect and dead-end polymerization.</p> / Master of Engineering (ME)

<p>The focus of this thesis is the modelling and control of product propelties in gas phase polyethylene reactors. The main product properties of concern are melt index (MI) and density (p), which are related to the molecular weight and composition of the ethylene/a(alpha)-olefm copolymer. A kinetic model is developed which accounts for the effects of gas composition, reactor temperature, and active site distribution of the Ziegler-Natta catalyst on the MI and p of the polymer product. The model predicts the behaviour of MI and p in an industrial reactor , as well as broadened molecular weight distribution and bimodal composition distributions, which are typical for commercial linear polyethylenes.</p> <p>Because measurements of MI and p are not available on-line, a methodology is developed to infer product properties from available measurements. Simple, theoretically-based models are derived which relate MI and p to reactor operating conditions. Parameters in the models are adjusted using off-line measurements, providing an effective means for inferring both MI and p.</p> <p>In a series of three product grade changeovers, dynamic optimization is used to determine optimal profiles for: hydrogen and butene feed rates, the reactor temperature setpoint, the gas bleed flow, the catalyst feed rate, and the bed level setpoint. It is shown that large transitions in MI are hampered by slow hydrogen dynamics, and that the time required for such a transition can be reduced by manipulation of the temperature setpoint and the bleed stream flow. Reduction of the bed level and catalyst feed rates during transitions can significantly decrease the quantity of off-specification polymer produced. In the absence of feedback control, disturbances and model mismatch can result in product property trajectories which differ significantly from the nominal optimal trajectory.</p> <p>A novel nonlinear model-based strategy is developed for on-line product property control. This feedforward/feedback control scheme is capable of both regulating product quality about a given target and of implementing optimal transition policies with feedback. The simplified mass balance model used in the controller design contains four adjustable parameters which are updated using an extended Kalman filter (EKF). The controller and EKF provide excellent regulatory and grade transition control for the range of poleythylene products simulated. The nonlinear controller is superior to an analogous linear time-invariant internal model control (IMC) design. The control system developed in the thesis is both simple and effective, and it has great potential for improving product quality in the polymer industry.</p> / Doctor of Philosophy (PhD)

<p>Most Canadian gold mining facilities utilize the cyanidation process in which cyanide is added to sequester gold from the ore. After zinc addition, gold is precipitated from a gold-cyanide complex. Waste streams from the process generally contain a sufficiently high concentration of cyanide and heavy metals that treatment is essential.</p> <p>The oldest treatment method practiced by Canadian gold mines for cyanide destruction is "natural degradation".</p> <p>Based on the literature review of the previous studies, the most important mechanism in the natural degradation of cyanide was recognized as being volatilization. Among the variables affecting the volatilization process the three most important were selected for this study, namely: temperature, UV light and aeration rate. The experimental pH chosen was 7.0. In order to evaluate the relative importance of these variables a full 2³ factorial design was employed and appropriate experiments conducted over a period of one year.</p> <p>The synthetic solutions examined were simple cyanide (NaCN), four single metallo-cyanide complexes (Cu, Zn, Ni and Fe) and two mixtures - a "low mix" containing a low concentration of metals relative to the total cyanide concentration and a "high mix", saturated with metals.</p> <p>Analysis of the results of the experimental design led to the conclusion that temperature had the largest effect upon reaction kinetics. The rate of aeration together with temperature had a significant effect upon the volatilization rate within the first 48 to 72 hours. Ultraviolet irradiation only had a significant effect upon the decay rate of the iron cyanide complex and low mix.</p> <p>A mathematical model for the degradation of a single metallo-cyanide complex solution was postulated for a batch reactor taking into consideration the law of conservation of mass, and assuming that chemical equilibrimn existed between hydrocyanic acid (HCN) and cyanide ion (CN-). The rate of volatilization of HCN and metal decay rate were the mechanisms assumed to be controlling the cyanide degradation process.</p> <p>The best estimates of the metal decay coefficients from single metallo-cyanide solutions used to simulate the experimental data of the mixed metallo-cyanide solutions are as follows:</p> <p>[Figure Removed]</p> <p>The model fits the data at the 95% confidence level for five of the eight test conditions; however, for the other three it is poorer.</p> <p>The model, calibrated using coefficients from the synthetic solutions, has been applied to actual gold mill effluents. Results show that the model can be used for the basic estimate of the cyanide degradation rate. For a more precise result, a recalibration of the model is necessary as a function of the particular gold mill effluent's metal content.</p> / Master of Engineering (ME)

<p>In this thesis two industrially motivated problems, belonging to the same manufacturing process, are solved by mixed-integer linear programming (MILP) techniques. Initially, the problem of determining optimal steady-state buffer levels for minimizing unit failure impacts is examined. Next, a method for achieving an optimal and coordinated production and flexible maintenance schedule is studied under several different optimization goals. The process that is predominantly considered is a continuous processing plant that can be modelled as n units in series separated by (<em>n</em> - 1) buffer tanks.</p> <p>Unit shutdowns due to equipment failure result in adverse economic consequences due to reduced production and costs associated with off-specification product. Mitigation of these effects may be possible if sufficient buffer capacity is available for parts of the plant to continue operation until the affected units are back in operation. A question that arises is what the optimal levels of the buffer storage units should be for use in normal operation, with insight as to what abnormal operating conditions may occur. This is a function of the expected unit failure frequencies and failure lengths, and the process dynamics. In this study, the problem is posed within a multi-period dynamic optimization framework. Historical records are used to determine key unit failure scenarios. The objective function considers the loss of profit associated with downtime, as well as a fixed cost of induced shutdowns due to buffers being either full or empty.</p> <p>Production scheduling in coordination with maintenance scheduling is often completed simply by fixing maintenance and then scheduling production around the maintenance-associated process unit unavailability. While acknowledging that much research has been completed to determine optimal maintenance policies, allowing maintenance events to be scheduled with a small degree of flexibility may significantly improve the resulting makespan. Alternative formulations suited to batch processing and continuous processing are presented; where the key advantage to the latter formulation is the possibility of job-splitting. Flexible maintenance by means of a specified time interval, sequence-dependent cleaning, shared finite intermediate storage, and product deadlines are accounted for in this dynamic optimization problem. Considered objectives include: makespan minimization, throughput maximization, and intermediate inventory minimization.</p> <p>Several case studies are provided for both problems, with the intention of demonstrating the functionality of the formulations as well as to indicate the possible process improvements upon implementation.</p> / Master of Applied Science (MASc)

<p>Production of proteins through <i>in planta</i> transient expression offers an alternative to conventional microbial and mammalian cell culture systems. This platform is particularly appealing because of its rapid and relatively low-cost implementation and its ease of scale-up. Transient expression occurs when a functional gene construct is inserted into a plant cell, where it is expressed over a short period of time without being stably integrated into the plant genome. Large-scale transient expression of recombinant proteins in plants is a relatively new area, and studies are underway to optimize the stages of the process in order to make it economically competitive. One area that has not been examined is the fermentation of <i>A. tumefaciens</i> for agroinfiltration at a large-scale. This research investigated the effects of growth conditions including temperature, pH, and media composition on <i> Agrobacterium</i> growth kinetics and gene transfer capability, with the goal of identifying optimal process conditions for growing <i>Agrobacterium </i> at large scale for use in transient agroinfiltration. Growth temperature was found to affect bacterial growth rate but not gene transfer capability, and a growth temperature of 28&deg;C was selected as optimal. Growth in Lysogeny Broth (LB) and Yeast Extract Peptone (YEP) media was examined and subsequent transient gene expression was measured. A defined media was developed and optimized for growing Agrobacterium and growth and gene transfer capability with this media was found to be comparable to LB and YEP media. Growth of <i> Agrobacterium</i> strain C58C1 pTFS40 in LB, YEP, and defined media resulted in maximum specific growth rates of 0.36 &plusmn; 0.01, 0.37 &plusmn; 0.03, and 0.33 &plusmn;0.01 h^&minus;1 and maximum biomass concentrations of 1.9, 3.6, and 3.9 grams dry cell weight per liter after 12, 16, and 20 hours, respectively. It was demonstrated that direct infiltration with <i> Agrobacterium</i> in diluted growth media was an effective method of inducing transient expression. Batch fermentation of <i>Agrobacterium </i> was scaled up to benchtop (5 L) scale with the three types of media. Finally, production was scaled up to a 100 L working volume reactor. </p>

Adsorption is an interfacial phenomenon in which intermolecular forces between a molecule and a surface create an adsorbed phase with different properties than the bulk fluid. Variation in the adsorbed phase among different adsorbate and solid adsorbent pairs is the driving force for many gas-phase separations. To efficiently design these separation processes, detailed characterization of the adsorbed phase over a range of operating conditions is required. The two main characteristics of the adsorbed phase that need to be well understood are adsorption equilibria and mass transfer rates, i.e. how much and how fast molecules are adsorbed. The purpose of this work is to use fundamental principles of adsorption to measure and interpret adsorption equilibria and mass transfer rates in various systems of interest. A concentration-swing frequency response (CSFR) method was used to measure mass transfer rates of a series of hydrocarbons in BPL activated carbon. Hydrocarbons with different ring and branched structures were used to test for steric effects on diffusion in the amorphous adsorbent. A correlation between rigid-ring structures and lower diffusivity was found. CSFR was also used to measure diffusion rates of CO2 in large single crystals of Cu-BTC, a metal-organic framework (MOF). Many MOFs have been studied as adsorbents for carbon capture and sequestration, but diffusion rates in the literature are scarce. The single crystal morphology of Cu-BTC allowed accurate measurements of micropore diffusion coefficients. Mass transfer rates were also measured on bidisperse pellets of a highly stable MOF, UiO-66, for CO2 and ethane. Macropore diffusion was determined to be the controlling resistance for both adsorbates. Volumetric methods were used to measure high pressure oxygen isotherms on a series of MOFs. MOFs with coordinatively unsaturated Cu metal sites were found to be promising candidates for oxygen storage, with capacities greater than current state of the art adsorbents. Finally, novel adsorbents were synthesized for a CO2 scrubber in a rebreather apparatus. The challenge for these adsorbents was obtaining high CO2 capacities at ambient temperatures, despite low CO2 partial pressures in water saturated conditions, while preventing mass transfer limitations.

Patients with Tumor Induced Bone Disease (TIBD) arising from several primary cancers including breast, lung, prostate cancer, suffer from extreme pain, bone loss, and frequent fracture which contribute to loss in quality of life and increase in cancer-related deaths. This condition is incurable and managed by palliative interventions, focused on length and quality of life. While the importance of interactions between bone and tumors is well established, the mechanism by which the physical bone microenvironment regulates disease progression is limited by the lack of suitable models. The aim of this work was to develop bone analogue model systems to study TIBD and test the efficacy, efficiency and effectiveness of therapeutics. First, we designed 3D-printed scaffolds with Fused Deposition Modeling (FDM) to investigate how the mechanical and topological properties of the bone microenvironment regulate bone-metastatic gene expression by tumor cells. The expression of specific genes associated with bone metastasis and destruction significantly increased with increasing substrate rigidity, flow rate and decreasing pore size. Importantly, drug response differed remarkably when tumors were cultured on bone-like 3D scaffolds compared to tissue culture well plates. When scaffolds seeded with tumor cells were implanted subcutaneously in mice, infiltration of host-immune cell populations further increased expression of bone-metastatic genes by the transplanted tumor cells. Second, we simulated TIBD progression using a population dynamic model quantified with experimental data. We determined our computational model accurately reflects loss in bone mass, characteristic of TIBD and illustrates how treatment approaches may be investigated. These studies highlight the application of in vitro and in sillico models in investigating tumor and bone interactions and testing inhibitors of TIBD.