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Ao longo dos últimos anos tem aumentado o interesse da comunidade científica no desenvolvimento de estruturas de borato de magnésio. Geralmente, o borato de magnésio é utilizado em conjunto com outros materiais como metais, polímeros, cerâmicas ou macromoléculas formando compósitos. Este borato tem sido largamente utilizado para reduzir o coeficiente de fricção e aprimorar as propriedades mecânicas de compósitos, atuando como material anti-desgaste e inibidos de corrosão. Dentre as fases de borato de magnésio, o Mg2B2O5 se destaca por apresentar potencial para aplicações tais como catalisador para conversão de hidrocarbonetos, agente para tratamento eletrocondutivo, semicondutor e material luminescente para aplicação em tubos de raios catódicos. Acredita-se que ao reduzir as dimensões do bulk de borato de magnésio a dimensões nanométricas, pode-se oferecer excelentes características para desenvolver e melhorar as potenciais aplicações acima mencionadas. Em geral, estruturas em nanoescala como tubos, fios, rods, cintos e whiskers têm sido o foco de intensiva pesquisa. Buscando a compreensão dos mecanismos para produção de nanoestruturas de boratos de magnésio, este trabalho está focado no desenvolvimento de uma rota de síntese de nanorods de Mg2B2O5 que permita a produção de um material com elevada pureza e homegeneidade estrutural a fim de possibilitar uma futura aplicação em dispositivos nanotecnológicos. Os nanorods foram sintetizados utilizando como precursor B2O3 e Mg metálico em um reator de CVD. Foi analisado o emprego de diferentes atmosferas para a reação, partindo de H2, Ar e acetonitrila (CH3CN). Foi estudado também a influência da temperatura na morfologia e composição dos nanorods. As propriedades físico-químicas das estruturas desenvolvidas foram caracterizadas por FTIR e DRX. A estrutura morfológica foi analisada por MEV e MET e as propriedades óticas por DRS. De acordo com os resultados, os nanorods foram obtidos com alto grau de pureza e homogeneidade morfológica utilizando uma atmosfera redutora composta por H2 e CH3CN. / Over the last few years the interest of the scientific community has increased in the development of magnesium borate structures. Borato has been widely used to reduce the coefficient of friction and improve the mechanical properties of composite materials such as anti-wear and corrosion. Generally, the magnesium borate is used together with other materials such as metals, polymers, ceramics and macromolecules to form compounds. Among the borate magnesium phases, Mg2B2O5 contrasts for presenting potential for applications such as acting as a catalyst for hydrocarbon conversion, as an agent for electroconductive treatment, as a semiconductor and luminescent material for application in cathode ray tubes. It is believed that by reducing the borate magnesium bulk dimensions to dimensions of nanostructures, it can provide excellent characteristics to develop and improve the potential applications mentioned above. In general, nanoscale structures such as tubes, wires, rods, belts and whiskers have been the focus of intensive research. Seeking to understand the mechanisms for production of magnesium borate nanostructures, this work is focused on the development of a synthesis method for Mg2B2O5 nanorods, enabling the production of a material with high purity and structural homogeneity to enable future application in nanotechnological devices. The physicochemical properties of the structures developed were characterized by FTIR and XRD. The morphological structure was examined by SEM and TEM and the optical properties by DRS. According to the results, high purity and morphological uniform nanorods were obtained using a H2 and CH3CN reducing atmosphere.

Ao longo dos últimos anos tem aumentado o interesse da comunidade científica no desenvolvimento de estruturas de borato de magnésio. Geralmente, o borato de magnésio é utilizado em conjunto com outros materiais como metais, polímeros, cerâmicas ou macromoléculas formando compósitos. Este borato tem sido largamente utilizado para reduzir o coeficiente de fricção e aprimorar as propriedades mecânicas de compósitos, atuando como material anti-desgaste e inibidos de corrosão. Dentre as fases de borato de magnésio, o Mg2B2O5 se destaca por apresentar potencial para aplicações tais como catalisador para conversão de hidrocarbonetos, agente para tratamento eletrocondutivo, semicondutor e material luminescente para aplicação em tubos de raios catódicos. Acredita-se que ao reduzir as dimensões do bulk de borato de magnésio a dimensões nanométricas, pode-se oferecer excelentes características para desenvolver e melhorar as potenciais aplicações acima mencionadas. Em geral, estruturas em nanoescala como tubos, fios, rods, cintos e whiskers têm sido o foco de intensiva pesquisa. Buscando a compreensão dos mecanismos para produção de nanoestruturas de boratos de magnésio, este trabalho está focado no desenvolvimento de uma rota de síntese de nanorods de Mg2B2O5 que permita a produção de um material com elevada pureza e homegeneidade estrutural a fim de possibilitar uma futura aplicação em dispositivos nanotecnológicos. Os nanorods foram sintetizados utilizando como precursor B2O3 e Mg metálico em um reator de CVD. Foi analisado o emprego de diferentes atmosferas para a reação, partindo de H2, Ar e acetonitrila (CH3CN). Foi estudado também a influência da temperatura na morfologia e composição dos nanorods. As propriedades físico-químicas das estruturas desenvolvidas foram caracterizadas por FTIR e DRX. A estrutura morfológica foi analisada por MEV e MET e as propriedades óticas por DRS. De acordo com os resultados, os nanorods foram obtidos com alto grau de pureza e homogeneidade morfológica utilizando uma atmosfera redutora composta por H2 e CH3CN. / Over the last few years the interest of the scientific community has increased in the development of magnesium borate structures. Borato has been widely used to reduce the coefficient of friction and improve the mechanical properties of composite materials such as anti-wear and corrosion. Generally, the magnesium borate is used together with other materials such as metals, polymers, ceramics and macromolecules to form compounds. Among the borate magnesium phases, Mg2B2O5 contrasts for presenting potential for applications such as acting as a catalyst for hydrocarbon conversion, as an agent for electroconductive treatment, as a semiconductor and luminescent material for application in cathode ray tubes. It is believed that by reducing the borate magnesium bulk dimensions to dimensions of nanostructures, it can provide excellent characteristics to develop and improve the potential applications mentioned above. In general, nanoscale structures such as tubes, wires, rods, belts and whiskers have been the focus of intensive research. Seeking to understand the mechanisms for production of magnesium borate nanostructures, this work is focused on the development of a synthesis method for Mg2B2O5 nanorods, enabling the production of a material with high purity and structural homogeneity to enable future application in nanotechnological devices. The physicochemical properties of the structures developed were characterized by FTIR and XRD. The morphological structure was examined by SEM and TEM and the optical properties by DRS. According to the results, high purity and morphological uniform nanorods were obtained using a H2 and CH3CN reducing atmosphere.

Ao longo dos últimos anos tem aumentado o interesse da comunidade científica no desenvolvimento de estruturas de borato de magnésio. Geralmente, o borato de magnésio é utilizado em conjunto com outros materiais como metais, polímeros, cerâmicas ou macromoléculas formando compósitos. Este borato tem sido largamente utilizado para reduzir o coeficiente de fricção e aprimorar as propriedades mecânicas de compósitos, atuando como material anti-desgaste e inibidos de corrosão. Dentre as fases de borato de magnésio, o Mg2B2O5 se destaca por apresentar potencial para aplicações tais como catalisador para conversão de hidrocarbonetos, agente para tratamento eletrocondutivo, semicondutor e material luminescente para aplicação em tubos de raios catódicos. Acredita-se que ao reduzir as dimensões do bulk de borato de magnésio a dimensões nanométricas, pode-se oferecer excelentes características para desenvolver e melhorar as potenciais aplicações acima mencionadas. Em geral, estruturas em nanoescala como tubos, fios, rods, cintos e whiskers têm sido o foco de intensiva pesquisa. Buscando a compreensão dos mecanismos para produção de nanoestruturas de boratos de magnésio, este trabalho está focado no desenvolvimento de uma rota de síntese de nanorods de Mg2B2O5 que permita a produção de um material com elevada pureza e homegeneidade estrutural a fim de possibilitar uma futura aplicação em dispositivos nanotecnológicos. Os nanorods foram sintetizados utilizando como precursor B2O3 e Mg metálico em um reator de CVD. Foi analisado o emprego de diferentes atmosferas para a reação, partindo de H2, Ar e acetonitrila (CH3CN). Foi estudado também a influência da temperatura na morfologia e composição dos nanorods. As propriedades físico-químicas das estruturas desenvolvidas foram caracterizadas por FTIR e DRX. A estrutura morfológica foi analisada por MEV e MET e as propriedades óticas por DRS. De acordo com os resultados, os nanorods foram obtidos com alto grau de pureza e homogeneidade morfológica utilizando uma atmosfera redutora composta por H2 e CH3CN. / Over the last few years the interest of the scientific community has increased in the development of magnesium borate structures. Borato has been widely used to reduce the coefficient of friction and improve the mechanical properties of composite materials such as anti-wear and corrosion. Generally, the magnesium borate is used together with other materials such as metals, polymers, ceramics and macromolecules to form compounds. Among the borate magnesium phases, Mg2B2O5 contrasts for presenting potential for applications such as acting as a catalyst for hydrocarbon conversion, as an agent for electroconductive treatment, as a semiconductor and luminescent material for application in cathode ray tubes. It is believed that by reducing the borate magnesium bulk dimensions to dimensions of nanostructures, it can provide excellent characteristics to develop and improve the potential applications mentioned above. In general, nanoscale structures such as tubes, wires, rods, belts and whiskers have been the focus of intensive research. Seeking to understand the mechanisms for production of magnesium borate nanostructures, this work is focused on the development of a synthesis method for Mg2B2O5 nanorods, enabling the production of a material with high purity and structural homogeneity to enable future application in nanotechnological devices. The physicochemical properties of the structures developed were characterized by FTIR and XRD. The morphological structure was examined by SEM and TEM and the optical properties by DRS. According to the results, high purity and morphological uniform nanorods were obtained using a H2 and CH3CN reducing atmosphere.

A new design synthesis method for articulated heavy vehicles (AHVs) with an active trailer steering (ATS) system is examined and evaluated. Due to their heavy weights, large sizes, and complex configurations, AHVs have poor maneuverability at low speeds, and low lateral stability at high speeds. Various passive trailer steering and ATS systems have been developed for improving the low-speed maneuverability. However, they often have detrimental effects on the high-speed stability. To date, no systematic design synthesis method has been developed to coordinate the opposing design goals of AHVs. In this thesis, a new automated design synthesis approach, called a Single Design Loop (SDL) method, is proposed and investigated. The SDL method has the following distinguished features: 1) the optimal active design variables of ATS systems and the optimal passive vehicle design variables are searched in a single design loop; 2) in the design process, to evaluate the vehicle performance measures, a driver model is developed and it „drives‟ the vehicle model based on the well-defined testing specifications; and 3) the ATS controller derived from this method has two operational modes: one for improving the lateral stability at high speeds and the other for enhancing path-following at low speeds. To demonstrate the effectiveness of the new SDL method, it is applied to the design of an ATS system for an AHV with a tractor/full-trailer. In comparison to a conventional design approach, the SDL method can search through solutions in a much larger design space, and consequently it provides a more comprehensive set of optimal designs.. / UOIT

Rapid prototyping (RP) can be used to make complex shapes with very little or even no constraint on the form of the parts. New design methods are needed for parts that can take advantage of the unique capabilities of RP. Although current synthesis methods can successfully solve simple design problems, practical applications with thousands to millions elements are prohibitive to generate solution for. Two factors are considered. One is the number of design variables; the other is the optimization method. To reduce the number of design variables, parametric approach is introduced. Control diameters are used to control all strut size across the entire structure by utilizing a concept similar to control vertices and Bezier surface. This operation allows the number of design variables to change from the number of elements to a small set of coefficients. In lattice structure design, global optimization methods are popular and widely used. These methods use heuristic strategies to search the design space and thus perform, as oppose to traditional mathematical programming (MP) methods, a better global search. This work propose that although traditional MP methods find local optimum near starting point, given a quick convergence rate, it will be more efficient to perform such method multiple times to integrate global search than using a global optimization method. Particle Swarm Optimization and Levenburg-Marquardt are chosen to perform the experiments.

<p> Hierarchical Interface-based Supervisory Control (HISC) decomposes a discrete-event system (DES) into a high-level subsystem which communicates with n ≥ 1 low-level subsystems, through separate interfaces which restrict the interaction of the subsystems. It provides a set of local conditions that can be used to verify global conditions such as nonblocking and controllability. As each clause of the definition can be verified using a single subsystem, the complete system model never needs to be stored in memory, offering potentially significant savings in computational resources.</p> <p> Currently, a designer must create the supervisors for a HISC system himself, and then verify that they satisfy the HISC conditions. In this thesis, we develop a synthesis method that respects the HISC hierarchical structure. We replace the supervisor for each level by a corresponding specification DES. We then do a per level synthesis to construct for each level a maximally permissive supervisor that satisfies the corresponding HISC conditions.</p> <p> We define a set of language based fixpoint operators and show that they compute the required level-wise supremal languages. We then present algorithms that implement the fixpoint operators. We present a complexity analysis for the algorithms and show that they potentially offer significant improvement over the monolithic approach.</p> <p> A large manufacturing system example (estimated worst case state space on the order of 10^22) extended from the AIP example is discussed. A software tool for synthesis and verification of HISC systems using our approach was also developed.</p> / Thesis / Master of Applied Science (MASc)

Essay #1 – Factors influencing the risk of falls in the construction industry: a review of the evidence Falls are a significant public health risk and a leading cause of nonfatal and fatal injuries among construction workers worldwide. A more comprehensive understanding of casual factors leading to fall incidents is essential to prevent falls in the construction industry. However, an extensive overview of causal factors is missing from the literature. In this paper, 536 articles on factors contributing to the risk of falls were retrieved. One hundred twenty-one (121) studies met the criteria for relevance and quality to be coded, and were synthesized to provide an overview. In lieu of the homogeneity needed across studies to conduct a structured meta-analysis, a literature synthesis method based on macro-variables was advanced. This method provides a flexible approach to aggregating previous findings and assessing agreement across those studies. Factors commonly associated with falls included working surfaces and platforms, workers’ safety behaviors and attitudes, and construction structure and facilities. Significant differences across qualitative and quantitative studies were found in terms of focus, and areas with limited agreement in previous research were identified. Findings contribute to research on the causes of falls in construction, developing engineering controls, informing policy and intervention design to reduce the risk of falls, and improving research synthesis methods. Essay #2 – Review of quantitative studies of interventions for responding to infectious disease outbreaks We reviewed the modeling and retrospective literature on responding to outbreaks of infectious diseases in humans and animals. Unlike routine immunization and control efforts, outbreak response activities require rapid reactive actions to address an urgent or emergent situation. We focused our review on characterizing the types of diseases analyzed, the interventions used, and the models employed. Out of the 211 studies identified, we find that the majority focus on a few diseases (influenza, foot and mouth disease, smallpox, measles, and hepatitis). We identified 34 distinct interventions explored in these studies that fall under the general categories of vaccination, prophylaxis, quarantine/isolation, contact restriction, exposure reduction, killing/slaughtering, and surveillance. A large number of studies (141) use simulation/analytical models to analyze outbreak response strategies. We identify key factors contributing to the effectiveness of different interventions that target high-risk individuals, trace infected contacts, or use a ring to delineate geographical boundaries for an intervention. Essay #3 – Development of an individual-based model for polioviruses: implications of the selection of network type and outcome metrics We developed an individual-based (IB) model to explore the stochastic attributes of state transitions, the heterogeneity of the individual interactions, and the impact of different network structure choices on the poliovirus transmission process in the context of understanding the dynamics of outbreaks. We used a previously published differential equation-based model to develop the IB model and inputs. To explore the impact of different types of networks, we implemented a total of 26 variations of six different network structures in the IB model. We found that the choice of network structure plays a critical role in the model estimates of cases and the dynamics of outbreaks. This study provides insights about the potential use of an IB model to support policy analyses related to managing the risks of polioviruses and shows the importance of assumptions about network structure. / Ph. D.

High cycle fatigue (HCF) failure has been studied extensively over the last two decades. Its impact on jet engines is severe enough that may result in engine losses and even life losses. The main requirement for fatigue life predictions is the stress caused by mechanical vibrations. One of the factors which have major impact on the vibratory stresses of bladed disk assemblies is a phenomenon called &ldquo / mistuning&rdquo / which is defined as the vibration localization caused by the loss of cyclic periodicity which is a consequence of inter&amp / #8208 / blade variations in structural properties. In this thesis, component mode synthesis method (CMSM) is combined with nonlinear forced response analysis in modal domain. Newton&amp / #8208 / Raphson and arc length continuation procedures are implemented for the solution. The component mode synthesis method introduces the capability of imposing mistuning on the modal properties of each blade in the assembly. Forced response analysis in modal domain reduces the problem size via mode truncation. The main advantage of the proposed method is that it is capable of calculating nonlinear forced response for all the degrees&amp / #8208 / of&amp / #8208 / freedom at each blade with less computational effort. This makes it possible to make a stress analysis at resonance conditions. The case studies presented in this thesis emphasize the importance of number of modes retained in the reduced order model for both CMSM and nonlinear forced response analysis. Furthermore, the results of the case studies have shown that both nonlinearity and mistuning can cause shifts in resonance frequencies and changes in resonance amplitudes. Despite the changes in resonance conditions, the shape of the blade motion may not be affected.