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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Partículas e Cordas em Espaços com Métricas Degeneradas / Particles and Strings in spaces with degenerate metrics

Cabral, Luís Antonio 27 August 1999 (has links)
Neste trabalho estudamos a dinâmica de partículas e cordas num campo gravitacional com métrica degenerada. Utilizamos o formalismo Hamiltoniano para determinar os vínculos da teoria e a dinâmica efetiva do sistema. Classificamos a estrutura dos vínculos de acordo com a forma de métrica e dimensão do espaço (-tempo). Obtemos também a representação das simetrias em termos de isometrias geradas por auto-vetores nulos da métrica. / In this work we stud the dynamics of particles and strings in a gravitational Field with degenerate metric. We use the Hamiltonian formalism to find out the constraints and the effective dynamics of the system. We classify the constraint structure according to the formo the me-tric and the space(time) dimension. We also obtain the representation of the symmetries in terms of the isometries generated by the null eigenvectors of the metric.
2

Partículas e Cordas em Espaços com Métricas Degeneradas / Particles and Strings in spaces with degenerate metrics

Luís Antonio Cabral 27 August 1999 (has links)
Neste trabalho estudamos a dinâmica de partículas e cordas num campo gravitacional com métrica degenerada. Utilizamos o formalismo Hamiltoniano para determinar os vínculos da teoria e a dinâmica efetiva do sistema. Classificamos a estrutura dos vínculos de acordo com a forma de métrica e dimensão do espaço (-tempo). Obtemos também a representação das simetrias em termos de isometrias geradas por auto-vetores nulos da métrica. / In this work we stud the dynamics of particles and strings in a gravitational Field with degenerate metric. We use the Hamiltonian formalism to find out the constraints and the effective dynamics of the system. We classify the constraint structure according to the formo the me-tric and the space(time) dimension. We also obtain the representation of the symmetries in terms of the isometries generated by the null eigenvectors of the metric.
3

Verksamhetsanpassning av IT-baserat finanssystem / Business Configuration of IT-based Treasury System

Fors, Lisa January 2012 (has links)
If P&C Insurance Company faces a challenge when their treasury system needs a new interface to a software as a service application. They need a suggestion for configuration for how the system and the application can work together. The work presented in this report is a suggestion for how you can make business configuration of an IT-based Treasury System in general. The exact configuration for the case received from If is presented as a separate report, found in Appendix A and is called the If-report. The If-report presents the suggested technical set-up of the configuration. It is not company specific but system and application specific. The work made in that report will be a standard in future version of the treasury system. The work made in this report is presented to the Royal Institute of Technology and can work as an example of how to approach a business configuration that needs to be done in an IT-based Treasury System.
4

Combination of Knoevenagel Polycondensation and Water-Assisted Dynamic Michael-Addition-Elimination for the Synthesis of Vinylene-Linked 2D Covalent Organic Frameworks

Xu, Shunqi, Liao, Dr. Zhongquan, Dianat, Arezoo, Park, Sang-Wook, Addicoat, Matthew A., Fu, Yubin, Pastoetter, Dominik L., Fabozzi, Filippo Giovanni, Liu, Yannan, Cuniberti, Gianaurelio, Richter, Marcus, Hecht, Stefan, Feng, Xinliang 22 April 2024 (has links)
Vinylene-linked two-dimensional conjugated covalent organic frameworks (V-2D-COFs), belonging to the class of two-dimensional conjugated polymers, have attracted increasing attention due to their extended π-conjugation over the 2D backbones associated with high chemical stability. The Knoevenagel polycondensation has been demonstrated as a robust synthetic method to provide cyano (CN)-substituted V-2D-COFs with unique optoelectronic, magnetic, and redox properties. Despite the successful synthesis, it remains elusive for the relevant polymerization mechanism, which leads to relatively low crystallinity and poor reproducibility. In this work, we demonstrate the novel synthesis of CN-substituted V-2D-COFs via the combination of Knoevenagel polycondensation and water-assisted dynamic Michael-addition-elimination, abbreviated as KMAE polymerization. The existence of C=C bond exchange between two diphenylacrylonitriles (M1 and M6) is firstly confirmed via in situ high-temperature NMR spectroscopy study of model reactions. Notably, the intermediate M4 synthesized via Michael-addition can proceed the Michael-elimination quantitatively, leading to an efficient C=C bond exchange, unambiguously confirming the dynamic nature of Michael-addition-elimination. Furthermore, the addition of water can significantly promote the reaction rate of Michael-addition-elimination for highly efficient C=C bond exchange within 5 mins. As a result, the KMAE polymerization provides a highly efficient strategy for the synthesis of CN-substituted V-2D-COFs with high crystallinity, as demonstrated by four examples of V-2D-COF-TFPB-PDAN, V-2D-COF-TFPT-PDAN, V-2D-COF-TFPB-BDAN, and V-2D-COF-HATN-BDAN, based on the simulated and experimental powder X-ray diffraction (PXRD) patterns as well as N2-adsorption–desorption measurements. Moreover, high-resolution transmission electron microscopy (HR-TEM) analysis shows crystalline domain sizes ranging from 20 to 100 nm for the newly synthesized V-2D-COFs.

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