Theses

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  • Triply Coupled Bending-Bending-Torsion Vibrational Analysis of Rotating Beams Using Fem and Dynamic Finite Element Formulation
    Triply Coupled Bending-Bending-Torsion Vibrational Analysis of Rotating Beams Using Fem and Dynamic Finite Element Formulation
    This research presents the numerical analysis of the triply coupled flap-wise, cord-wise and torsional vibrations of flexible rotating blades. Euler-Bernoulli bending and St. Venant torsion beam theories are considered to derive the governing differential equations of motion. Based on Finite Element Methodology (FEM), the cubic "Hermite" shape functions are implemented where the solution of the equations results in a linear engine problem. Then, the Dynamic (frequency dependent) Trigonometric Shape Functions (DISF's) for beam's uncoupled displacements are derived. The application of the Dynamic Finite Element (DFE) approach to the solution of the governing equations is then presented. The DFE formulation, based on the weighted residual method and the DTSF's results in a nonlinear engine problem representing eigenvalues and engine modes of the system. The applicability of the DFE method is then demonstrated by illustrative examples, where a Wittrick-Williams root counting technique is used to find the system's natural frequencies. The DFE approach, an intermediate method between FEM and "Exact" formulation, is characterized by higher convergence rates, and can be advantageously used when multiple natural frequencies and/or higher modes of beam-like structures are to be evaluated.
    Truck stability on different types of horizontal curves combined with vertical alignments
    Truck stability on different types of horizontal curves combined with vertical alignments
    The combination of horizontal curves with vertical alignments is commonly used in different classifications of highways; either on highway mainstream or on highway interchange ramps. The horizontal curves, combined with vertical alignments, may be single, compound or reverse horizontal curves. The current design guidelines do not adequately investigate vehicle stability on such three-dimensional (3D) alignments. Computer software that simulates vehicle behaviour on different geometrical alignments was employed to investigate vehicle stability on such 3D alignments. It was found that vehicle safety is questionable, especially for larger vehicles on reverse curves associated with vertical alignments. The critical speed, where the vehicle starts to rollover or skid, was found to be close to design speed for those 3D alignments. Design aids were then developed to address the recommended solutions to maintain the margin of safety required.
    Trust management in opportunisitic networks: a semantic web-based approach
    Trust management in opportunisitic networks: a semantic web-based approach
    The need for having a mechanism to automatically interpret content available on the Web without a human intervention has lead to the development of a new vision for the next generation of the Web, known as the Semantic Web. This new paradigm advocates the use of ontologies to achieve a common language for communication among humans, computers, and programs. In this thesis, a novel Semantic Web-based solution called SCOW-Q (Semantic Capability Discovery With QoS) model, is proposed, which provides an architectural basis for representing trust and trust management in Opportunistic Networks. The model is validated by means of a Use Case Scenario using a well-defined Semantic Web Service framework.
    Trust-enhanced secure multipath routing for mobile ad hoc networks
    Trust-enhanced secure multipath routing for mobile ad hoc networks
    Due to recent advances in computing and communication technologies, Mobile Ad hoc Networks (MANETs) are becoming networks of choice for various applications such as emergencies [sic] preparedness and response, military and crisis management, and healthcare, to name a few. The main reason for this is that in MANET, information exchange between nodes can happen dynamically without pre-exisiting fixed network infrastructure with designated centralized access points. However, this privilege also comes with some security drawbacks, especially from a message security viewpoint because the implementation of hard-cryptographic security now becomes a challenging prospect.In this thesis, we improve a recently proposed method of message security in MANET (so called benchmark scheme, also referred to as trust-based multipath DSR routing scheme), by introducing a trust model that makes multi-path routing flexible enough to avoid non-trusted routes that may use brute force attacks to decrypt messages travelling through the network en route to their destinations. Simulation results, coupled with theoretical justification, affirm that the proposed solution is much more secured than the above-mentioned benchmark method and traditional multi-path routing algorithms.
    Truth to Nature: Pre-Raphaelite Dress in Nineteenth-Century Visual Culture
    Truth to Nature: Pre-Raphaelite Dress in Nineteenth-Century Visual Culture
    The Pre-Raphaelites were a group of artists in mid-nineteenth century England who disliked popular art, design, and fashion. They devised an oppositional, artistic type of dress. This major research project (MRP) endeavours to define, contextualize, and interpret the special kind of dress depicted in Pre-Raphaelite paintings and worn by women in the Pre-Raphaelite circle. Qualitative, interdisciplinary historical methods were used in my research method, and visual media (both primary and secondary sources) were used throughout the project. Outcomes include a new analysis of Pre-Raphaelite dress and its formal qualities along with a socio-cultural analysis of why the Pre-Raphaelites chose to dress in an eclectic way. The paintings reveal the diverse sources the Pre-Raphaelites used to create original garments in their illustrated works. The original garments the Pre-Raphaelites wore influenced other artistic, dress, and design reform movements such as the Aesthetic Dress movement and the Arts and Craft movement.
    Tubular lysosome biogenesis in innate immune cells
    Tubular lysosome biogenesis in innate immune cells
    Lysosomes are essential organelles required for breakdown of endocytic and biosynthetic cargo, pathogen killing and autophagy. In most cells, lysosomes are typically small punctate structures. By contrast, innate immune cells like macrophages and dendeitic cells that have been exposed to bacterial lipopolysaccharids (LPS) exhibit strikingly tubular lysosomes (TLs) and lysosome-related major histocompatility class II (MHCII) compartments (MIIC), respectively. TLs are suggested to play a role in phagosome maturation and retention of fluid-phase endocytic uptake in activated macrophages. In addition, the dendritic cell tubular MIIC (tMIIC) may be involved in antigen presentation. Since remarkably little was known about how tubular lysosomes form, I took to investigate the molecular requirements for this process in macrophages and dendritic cells and present my findings in this thesis. Here I confirm that microtubules are necessary as a template for lysosome tabulation, along with dynein and kinesin microtubule-dependendent motors. We were first to identify molecular components necessary for lysosome tabulation; TL biogenesis required the concerted action of the Ar18b GTPasem along with its effector SKIP, a kinesin adaptor proteins for dynein and kinesin, respectively. Importantly, we observed that TLs are highly dynamic structures whereas punctate lysosomes are conspicuously more static. I also present evidence that mTOR, a lysosomal protein kinase, is required for LPS-induced TL biogenesis and cell surface delivery of MHCII in macrophages and dendritic cells. First, I show that the MyD88-P13K-Akt-mTOR signaling pathway regulates LPS-induced lysosome tabulation. Second, I demonstrate that mTOR is required for anterograde lysosomal transport suggesting that this kinase may regulate tabulation and antigen presentation by modulating the microtubule-based motor activity of lysosomes. Finally I present preliminary data on the properties of tubular lysosomes compare to punctate lysosomes in an effort to characterize these organelles. Among the data presented is evidence that total lysosomal volume increases significantly upon tabulation, which may have important underlying implications in antigen sampling and processing. Overall, my work has expanded on our knowledge on our knowledge of how morphology and trafficking of lysosomes is modulated in immune cells, which may alter cell function.
    Twenty years of unnecessary forward slashes: towards a post-ontological critique of Tim Berners-Lee's evolving aspirations for the Web and the World Wide Web Consortium from the cultural studies  perspective
    Twenty years of unnecessary forward slashes: towards a post-ontological critique of Tim Berners-Lee's evolving aspirations for the Web and the World Wide Web Consortium from the cultural studies perspective
    Since it was first formally proposed in 1990 (and since the first website was launched in 1991), the World Wide Web has evolved from a collection of linked hypertext documents residing on the Internet, to a "meta-medium" featuring platforms that older media have leveraged to reach their publics through alternative means. However, this pathway towards the modernization of the Web has not been entirely linear, nor will it proceed as such. Accordingly, this paper problematizes the notion of "progress" as it relates to the online realm by illuminating two distinct perspectives on the realized and proposed evolution of the Web, both of which can be grounded in the broader debate concerning technological determinism versus the social construction of technology: on the one hand, the centralized and ontology-driven shift from a human-centred "Web of Documents" to a machine-understandable "Web of Data" or "Semantic Web", which is supported by the Web's inventor, Tim Berners-Lee, and the organization he heads, the World Wide Web Consortium (W3C); on the other, the decentralized and folksonomy-driven mechanisms through which individuals and collectives exert control over the online environment (e.g. through the social networking applications that have come to characterize the contemporary period of "Web 2.0"). Methodologically, the above is accomplished through a sustained exploration of theory derived from communication and cultural studies, which discursively weaves these two viewpoints together with a technical history of recent W3C projects. As a case study, it is asserted that the forward slashes contained in a Uniform Resource Identifier (URI) were a social construct that was eventually rendered extraneous by the end-user community. By focusing On the context of the technology itself, it is anticipated that this paper will contribute to the broader debate concerning the future of the Web and its need to move beyond a determinant "modernization paradigm" or over-arching ontology, as well as advance the potential connections that can be cultivated with cognate disciplines.
    Twinning and texture development in an extruded AM30 magnesium alloy during compressive deformation
    Twinning and texture development in an extruded AM30 magnesium alloy during compressive deformation
    This study was aimed at evaluating the microstructure, mechanical behavior and texture response of extruded AM30 magnesium alloy in uniaxial compression with special attention to the effect of compressive strain amount, sample orientation, loading direction, compressive prestrain, and annealing. Compressive deformation along the extrusion direction (ED) resulted in sigmoidal true stress-true strain behavior together with three distinct stages of strain hardening, due to the presence of two sets of basal textures {0001}<2110> and {0001}<1010>, with caxes aligned nearly parallel to the normal direction (ND) of the extruded plate which facilitated the occurrence of {1012} extension twinning. The effect of in-plane loading direction, i.e., 0°,15°, 30°, 45° from the ED on the compressive flow behavior was investigated, which revealed nearly constant yield and ultimate compressive strengths but with a remarkable increase of fracture strain compared to the ED sample. The effect of pre-strain along the ED on the formation of twinning and texture was investigated during re-compression along the ED, transverse direction (TD) and ND. In the two-step ED-ED compression, the disappearance of twin boundaries or the coalescence of twins via twin growth was observed. After pre-strain along the ED, re-compression along the TD showed two seemingly opposite phenomena, i.e., the formation of new twins and de-twinning to be coexistent due to the presence of multiple sets of textures after the first-step pre-straining. The de-twinning activity decreased and the texture weakening was achieved with increasing pre-strain in the ED while doing recompression along the ND at a constant strain amount. Texture measurements revealed that the c-axes of hcp unit cells were always rotated towards the compression direction, regardless of compression in the ED, TD or ND. The annealing temperature and time also had a pronounced effect on microstructure and texture evolution. With increasing annealing time, the twins in the pre-compressed samples were observed to disappear gradually, as demonstrated by a decreased volume fraction of twins and weakened texture which became more randomly distributed. As a result, during re-compression along the ED, fewer twin formation and less intense texture were observed, resulting in a significant increase of ductility.
    Two 19th Century Japanese Souvenir Travel Albums At The Art Gallery Of Ontario
    Two 19th Century Japanese Souvenir Travel Albums At The Art Gallery Of Ontario
    This paper analyzes two nineteenth-century Japanese souvenir travel albums from the Art Gallery of Ontario's collection of photography. The project includes: a literature survey discussing sources and researchers of early photography in Japan; contextual research on the introduction of photographic technology in nineteenth-century Japan and the influence that traditional woodblock prints may have had on the genre of commercial souvenir photographs of Japan; and a detailed description of both album with a potential attribution. Furthermore, the applied component of the project, which entailed documentation of both albums in the form of a catalogue of their 100 tinted albumen prints, is included as an appendix. The paper also provides recommendations for the optimal storage and preservation of both albums, as well as a housing solution. The cataloguing and housing of the two albums will enhance accessibility and facilitate future research of these albums.
    Two-photon polymerization using femtosecond laser
    Two-photon polymerization using femtosecond laser
    The demand for microfabrication by laser technology has been the foundation of the new age of three-dimensional micro-structuring processes. One of these new processes that has been established in recent years has been the two-photon polymerization (2PP) technique by femtosecond lasers. Unlike the well known stereo-lithography (SL), this newly developing technology provides simple and rapid fabrication procedures and demonstrates much better quality and structural resolution. In addition, by using computer generated 3D models, this technique can produce any kind of 3D structures that can be then fabricated and integrated into complicated devices. Currently used strategies and methods to produce the smallest possible feature by using 2PP process are acceptable but the[sic] strive for enhanced results is necessary in order to continue the progression of such technique.This thesis proposes a broader knowledge on laser parameters that affect 2PP process and the implementation of such parameters in order to produce the smallest feature size and the highest aspect ratio structure possible. A high repetition rate, high power femtosecond laser is investigated for exceeding the quality demand established by the current market. An experimental study of the proposed laser system and the analysis of control parameters, such as laser power and repetition rate, are presented. The influence of pulse width, laser power, substrate material, and scanning speed on aspect ratio is analyzed in detail. The produced microstructure with the measured aspect ratio indicates the capability of meeting the quality and requirements that have been established by the current market.
    Two-price policy for a newsvendor product supply chain with time and price sensitive demand
    Two-price policy for a newsvendor product supply chain with time and price sensitive demand
    In this study, a dominant manufacturer wholesales a technological product to a retailer. In technology-related industries, the obsolescence of an existing product and/or the appearance of a new product decrease the attractiveness of the existing product. This study also assumes that the market demand is stochastic and price-sensitive, where this price-sensitivity increases by time. Hence, retailers need to decline the retail price during the product life cycle to alleviate the effect of time on the demand. Here, two models/cases are considered. In the first model, the retailer decreases the retail price at midlife without any compensation from the manufacturer. In the second model, the manufacturer gives rebate to the retailer when the retailer declines the retail price at midlife. In addition, the performance of the proposed models is numerically compared with wholesale-price-only and the buyback policies.
    Typha Latifolia response to Oliotrophic and Eutrophic nitrogen and phosphorus loading rates under laboratory conditions
    Typha Latifolia response to Oliotrophic and Eutrophic nitrogen and phosphorus loading rates under laboratory conditions
    Typha latifolia is an aggressive rhizomatous emergent wetland plant that can invade wetlands resulting in near monotypic Typha stands. T. latifolia is also one of the most commonly used macrophyte species in constructed wetlands. The hypothesis that elevated nitrogen and phosphorus concentrations observed in nonpoint source runoff increases T. latifolia fitness and potentially T. latifolia invasiveness was tested under semi-controlled laboratory conditions. A protocol was developed to propagate T. latifolia from seed in low P sediment to simulate an oligotrophic pre-impact reference treatment. Microcosms provided with hypereutrophic levels of P combined with oligotrophic or eutrophic levels of N had significantly greater shoot biomass and maximum leaf height compared to oligotrophic N and P treatment microcosms. These results indicated that high P often found in runoff may contribute to T. latifolia invasion. We recommend that noninvasive species of macrophytes be used in constructed wetlands to prevent impact to ecologically sensitive areas.