5 resultados para generative and performative modeling

em Brock University, Canada


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This thesis describes the synthesis and use of an N-substituted ferrocene bearing a proline-derived chiral directing group and diastereoselective lithiation-electrophile quench of the pro-Sp hydrogen of the ferrocene to give planar chiral products in >95:5 dr. The auxiliary group is found to be stable to lithium bases of types RLi and R2NLi giving the same diastereoselectivity. The anti- epimer of the previously mentioned syn auxiliary induces lithiation of pro Rp rather than pro Sp hydrogen in >95:5 dr. Upon electrophile quench and elimination, the enantiomer of the syn-derived planar chiral imidazolone is obtained. Hence, this method provides a practical way to prepare planar chiral enantiomers in this series without the use of a more expensive D-proline derived starting material. The syn and anti epimers have β, γ-stereogenic centers and the origin of stereoselectivity in lithiation appears to be driven by the conformational bias exerted by the β-silyloxy moiety in each chiral auxiliary. In the thesis, this conclusion is supported using insensitivity of lithiation selectivity to the bulkiness of the base, comparison of enantiomers, deuteration experiments, nOe difference studies and computational modeling of the ground states and lithiation transition states for both substrates. The products are then converted to ligand precursors to make iridium and rhodium complexes. Among them, one of the cationic iridium complex is found to be effective in the asymmetric hydrogenation of 2-substituted quinolines with enantioselectivities up to 80% at pressures as low as 5 atm.

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This project is a deconstructive discourse analysis of smart girlhood. From a feminist post structural framework, with a focus on discourse and performative identity, I scrutinize three dominant discourses of smartness that are prevalent and academic and popular press. These constructions frame smart girls as being either Losers, Have-It-All Girls, or Imposters. By conducting semi-structured group interviews with six self-identified smart girls, I explore the question of how smart girls perform their smart girl identities in their current sociocultural context. After analyzing the data from the group interviews, I outline five themes that seem to be prevalent in the stories told by the smart girls in this thesis. Finally, I discuss how the performative identities of the smart girls in my thesis appear to be much more complex, multiple and rhizomatic than the discourses under review allow.

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This study has two main objectives. First, the phlebotomy process at the St. Catharines Site of the Niagara Health System is investigated, which starts when an order for a blood test is placed, and ends when the specimen arrives at the lab. The performance measurement is the flow time of the process, which reflects concerns and interests of both the hospital and the patients. Three popular operational methodologies are applied to reduce the flow time and improve the process: DMAIC from Six Sigma, lean principles and simulation modeling. Potential suggestions are provided for the St. Catharines Site, which could result in an average of seven minutes reduction in the flow time. The second objective addresses the fact that these three methodologies have not been combined before in a process improvement effort. A structured framework combining them is developed to benefit future study of phlebotomy and other hospital processes.

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As the complexity of evolutionary design problems grow, so too must the quality of solutions scale to that complexity. In this research, we develop a genetic programming system with individuals encoded as tree-based generative representations to address scalability. This system is capable of multi-objective evaluation using a ranked sum scoring strategy. We examine Hornby's features and measures of modularity, reuse and hierarchy in evolutionary design problems. Experiments are carried out, using the system to generate three-dimensional forms, and analyses of feature characteristics such as modularity, reuse and hierarchy were performed. This work expands on that of Hornby's, by examining a new and more difficult problem domain. The results from these experiments show that individuals encoded with those three features performed best overall. It is also seen, that the measures of complexity conform to the results of Hornby. Moving forward with only this best performing encoding, the system was applied to the generation of three-dimensional external building architecture. One objective considered was passive solar performance, in which the system was challenged with generating forms that optimize exposure to the Sun. The results from these and other experiments satisfied the requirements. The system was shown to scale well to the architectural problems studied.

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This paper develops a model of short-range ballistic missile defense and uses it to study the performance of Israel’s Iron Dome system. The deterministic base model allows for inaccurate missiles, unsuccessful interceptions, and civil defense. Model enhancements consider the trade-offs in attacking the interception system, the difficulties faced by militants in assembling large salvos, and the effects of imperfect missile classification by the defender. A stochastic model is also developed. Analysis shows that system performance can be highly sensitive to the missile salvo size, and that systems with higher interception rates are more “fragile” when overloaded. The model is calibrated using publically available data about Iron Dome’s use during Operation Pillar of Defense in November 2012. If the systems performed as claimed, they saved Israel an estimated 1778 casualties and $80 million in property damage, and thereby made preemptive strikes on Gaza about 8 times less valuable to Israel. Gaza militants could have inflicted far more damage by grouping their rockets into large salvos, but this may have been difficult given Israel’s suppression efforts. Counter-battery fire by the militants is unlikely to be worthwhile unless they can obtain much more accurate missiles.