The synthesis and characterization of some new unsaturated polymers

The thesis describes investigations into three novel synthetic routes for the preparation of totally conjugated polymers. The first route involved the attempted photoreductive step-growth polymerization of aromatic diketones with aromatic diols as the first step of a route to poly(arylene vinylene)s. These reactions failed to yield sufficiently high molecular weight polypinacols to merit a continuation of the investigation. The second route examined used the ground state reductive coupling of aromatic diketones utilizing the McMurry reaction. This approach was successful and gave good samples of poly(arylene vinylene)s. The third approach was the thermal and photochemically induced isomerisation of metathesis produced polymers of bicyclofulvenes. Work completed on this project suggests that the products were conjugated polymers. The products of these syntheses were characterized and electrical conductivity and doping studies were carried out on the new polyconjugated materials

Computer architectures for functional and logic languages

PhD ThesisIn recent years interest in functional and logic languages has grown considerably. Both classes of language offer advantages for programming and have an influential group of people promoting them. As yet no consensus has formed as to which class is best, and such a consensus may never form. Future general-purpose computer architectures may well be required to support both classes of language efficiently. Novel architectures designed to support both classes of languages could even add impetus to the area of hybrid functional/logic languages. Treleaven et al[68] have proposed a classification of computational mechanisms which they believe underly several types of novel computer architecture (i.e. control flow, data flow and reduction). The classification partitions novel general-purpose architectures into the following classes: control driven - where a statement is executed when it is selected by flow(s) of control, data driven - where a statement is executed when some combination of its arguments are available, and demand driven - where a statement is executed when the result it produces is needed by another, already active instruction. This thesis investigates the efficient support of both functional and logic languages using an architecture that attempts to be general purpose by embodying all the mechanisms that underly the above classification. A novel packet communication architecture is presented which intergrates the control driven, data driven and demand driven computational mechanisms. A software emulator for the machine was used as the basis for separate implementations of functional and logic languages, which were in turn used to evaluate the effectiveness of the computational mechanisms described in the classification. These mechanisms allowed functional languages to be implemented wi th ease, but caused severe problems when used to support logic languages. The difficulties with these mechanisms are taken as signifying that they do not provide adequate support for logic languages. The problems encountered led to the development of a novel implementation technique for logic languages, which also proved to be a good basis for a combined functional and logic model. This model is believed to provide a sound foundation for a parallel computer system that would support functional and logic languages with equal elegance and efficiency, and would therefore also support hybrid languages. The design for such a computer is described at the end of this thesis.the Science and Engineering Research Council, Great Britain

Collapse Safety Assessment of Steel Multi-storey Buildings with Friction Sliding Braced Frames and Backup Moment Resisting Frames as a Dual System

In the early 1980’s, Concordia University’s library building saw the first application of cross-braced Pall friction dampers (PFD). Although PFDs have evolved and improved, including the friction material used, development of the design procedure has been limited. Using a recently proposed force-based design method and considering detailed computational and modeling techniques, three types of seismic force resisting systems are presented herein: the bare Friction Sliding Braced Frame (FSBF), Friction Sliding Braced Frame with Continuous Columns including gravity columns (FSBF-CC) and Dual FSBF system (D-FSBF). Installing backup MRFs in parallel with a primary FSBF can provide the structure with load path redundancy and elastic-frame action, while taking advantage of the large energy dissipation capacity of PFDs. The objectives of this research are three-fold: 1) to develop an accurate nonlinear model for PFD that is capable of bearing and failure, 2) to quantify the ductility-related force modification factor, Rd, for the proposed seismic force resisting systems: bare FSBF, FSBF-CC, and D-FSBF and 3) assess fragility and collapse safety of low-rise and middle-rise buildings braced with the proposed seismic force resisting systems subjected to crustal and subduction ground motions. These objectives are carried out using 2-D numerical models developed in OpenSees for 4- and 8-storey prototype buildings located on Site class C in Vancouver, B.C. A force-based design method was developed in line with NBCC 2015 and CSA/S16-14 standard requirements. Considering the similarity with buckling restrained braced frames (BRBF), design was conducted for RdRo=4 and RdRo=5. All buildings were subjected to short duration crustal and long duration subduction ground motions, and a discussion regarding the slip length demand of PFD was provided. From nonlinear response history analysis of 4 and 8-storey FSBF buildings (RdR0=4), it was found that the bare FSBF was structurally unstable and reached collapse prior to design level under the ground motion suites. Therefore, using the bare FSBF is not recommended. The 4-storey FSBF-CC building (RdR0=4) prevented collapse at design level, however experienced excessive residual drift, while the 8-storey FSBF-CC building reached collapse at design level under both crustal and subduction ground motions. Thus, the FSBF-CC system can be used only for low-rise buildings, but caution should be taken. Using the Dual FSBF system composed of FSBF and a backup MRF, designed for an additional 25% base shear and two sets of RdR0 =4 and 5, it resulted that both 4-storey and 8-storey D-FSBF buildings showed sufficient margin of safety under both ground motion suites. Subsequently, when increasing the building height (e.g. the 8-storey building), the ductility-related force modification factor, Rd = 4 is recommended. The Dual FSBF system is recommended to brace low-rise and middle-rise buildings located in subduction zone, as Cascadia subduction zone, where megathrust earthquakes could occur

Mediated Histories: Representations Of Nineteenth-Century American Life At Greenfield Village And Crossroads Village

Living history museums are a prevalent form of history museum in which periods in history are portrayed through the use of artifacts and structures from the era, as well through the use of interpreters, which demonstrate processes from the past or discuss events with visitors. These sites have been scrutinized in the last few decades due to their constructed nature that often downplays negative aspects of the past. Since history is multi-faceted, it is impossible to present a clear recreation of history, and therefore, the creators of these sites have considerable leeway in how they choose to depict aspects of the past. It is through this license that current issues are often projected onto these sites and therefore the past. I argue this statement by looking at several living history museums created throughout the twentieth-century, specifically Greenfield Village in Dearborn, Michigan and Crossroads Village in Flint, Michigan, which outwardly depict the same theme, but through their construction make statements about the eras in which they were created

Investigating the effect of thermal gradients on stress in solid oxide fuel cell anodes using combined synchrotron radiation and thermal imaging

Thermal gradients can arise within solid oxide fuel cells (SOFCs) due to start-up and shut-down, non-uniform gas distribution, fast cycling and operation under internal reforming conditions. Here, the effects of operationally relevant thermal gradients on Ni/YSZ SOFC anode half cells are investigated using combined synchrotron X-ray diffraction and thermal imaging. The combination of these techniques has identified significant deviation from linear thermal expansion behaviour in a sample exposed to a one dimensional thermal gradient. Stress gradients are identified along isothermal regions due to the presence of a proximate thermal gradient, with tensile stress deviations of up to 75Â MPa being observed across the sample at a constant temperature. Significant strain is also observed due to the presence of thermal gradients when compared to work carried out at isothermal conditions

Effect of reactant gas flow orientation on the current and temperature distribution in self-heating polymer electrolyte fuel cells

Fuel cell polarisation performance is typically reported under controlled/constant temperature conditions, as a sign of robust metrology. However, in practice, fuel cells self-heat as they generate current; which varies the temperature across the polarisation curve and affects performance. More detail regarding the internal cell operation can be gleaned by current and temperature distribution mapping. For the case of an unheated cell, ‘self-heating’ increases the cell temperature and improves performance, resulting in a ‘voltage recovery’ and a more homogeneous current and water distribution. For actively heated cells, a reduced current is observed in regions of high temperature and low humidity. The positioning of the gas manifolds also has a decisive impact on performance by affecting the reactant concentration, humidity and water distribution. Counter- and cross-flow orientations in a self-heating cell were studied, with a counter-flow orientation with air flowing with gravity producing the most uniform temperature distribution

Vacancies, disorder-induced smearing of the electronic structure, and its implications for the superconductivity of anti-perovskite MgC0.93_{0.93}Ni2.85_{2.85}

The anti-perovskite superconductor MgC$_{0.93}$Ni$_{2.85}$ was studied using high-resolution x-ray Compton scattering combined with electronic structure calculations. Compton scattering measurements were used to determine experimentally a Fermi surface that showed good agreement with that of our supercell calculations, establishing the presence of the predicted hole and electron Fermi surface sheets. Our calculations indicate that the Fermi surface is smeared by the disorder due to the presence of vacancies on the C and Ni sites, but does not drastically change shape. The 20\% reduction in the Fermi level density-of-states would lead to a significant ($\sim 70\%$) suppression of the superconducting $T_c$ for pair-forming electron-phonon coupling. However, we ascribe the observed much smaller $T_c$ reduction at our composition (compared to the stoichiometric compound) to the suppression of pair-breaking spin fluctuations.Comment: 11 pages, 3 figure

Design of a miniature flow cell for in situ x-ray imaging of redox flow batteries

Flow batteries represent a possible grid-scale energy storage solution, having many advantages such as scalability, separation of power and energy capabilities, and simple operation. However, they can suffer from degradation during operation and the characteristics of the felt electrodes are little understood in terms of wetting, compression and pressure drops. Presented here is the design of a miniature flow cell that allows the use of x-ray computed tomography (CT) to study carbon felt materials in situ and operando, in both lab-based and synchrotron CT. Through application of the bespoke cell it is possible to observe felt fibres, electrolyte and pore phases and therefore enables non-destructive characterisation of an array of microstructural parameters during the operation of flow batteries. Furthermore, we expect this design can be readily adapted to the study of other electrochemical systems

Measurement of water uptake in thin-film Nafion and anion alkaline exchange membranes using the quartz crystal microbalance

Water uptake, sorption mechanics and swelling characteristics of thin-film Nafion and a commercially available Tokuyama alkaline anion exchange membrane ionomer from the vapour phase is explored using a quartz crystal microbalance (QCM). The water uptake measures the number of water molecules adsorbed by the ionomer per functional group and is determined in-situ using the QCM frequency responses allowing for comparison with nanogram precision. Crystal admittance spectroscopy, along with equivalent circuit fitting, is applied to both thin films for the first time and is used to investigate the ionomer's viscoelastic changes during hydration; to elucidate the mechanisms at play during low, medium and high relative humidities