The thesis focuses on the social web and on the analysis of social networks with particular emphasis on their temporal aspects. Social networks are represented here by Time Varying Graphs (TVG), a general model for dynamic graphs borrowed from distributed computing. In the first part of the thesis we focus on the temporal aspects of social networks. We develop various temporal centrality measures for TVGs including betweenness, closeness, and eigenvector centralities, which are well known in the context of static graphs. Unfortunately the computational complexities of these temporal centrality metrics are not comparable with their static counterparts. For example, the computation of betweenness becomes intractable in the dynamic setting. For this reason, approximation techniques will also be considered. We apply these temporal measures to two very different datasets, one in the context of knowledge mobilization in a small community of university researchers, the other in the context of Facebook commenting activities among a large number of web users. In both settings, we perform a temporal analysis so to understand the importance of the temporal factors in the dynamics of those networks and to detect nodes that act as “accelerators”. In the second part of the thesis, we focus on a more standard static graph representation. We conduct a propagation study on YouTube datasets to understand and compare the propagation dynamics of two different types of users: subscribers and friends. Finally, we conclude the thesis with the proposal of a general framework to present, in a comprehensive model, the influence of the social web on e-commerce decision making.

En esta investigación se analiza la viabilidad de un negocio enfocado a brindar un servicio de reparación de amortiguadores de impacto, orientado a las compañías mineras de tajo abierto durante su fase de producción. Siendo una alternativa para las empresas mineras de reponer los amortiguadores de impacto a bajo costo operativo, lo reemplazan por nuevos en lugar de recuperarlos, generando altos costos de reposición. La industria minera es un sector muy relevante para la economía nacional, teniendo un aporte del 10% del PBI la última década, por lo que el negocio, propone una alternativa que permita a las compañías mineras tener un adecuado indicador de costo/rendimiento en los amortiguadores de impacto. La propuesta se enfoca en reparar las dos marcas de amortiguadores más utilizadas del mercado nacional, Foremost y Utex (King Cobra), a un bajo costo operativo y en un tiempo adecuado para las compañías mineras. Se ha estimado que las compañías mineras de tajo abierto utilizan un aproximado de 126 amortiguadores de impacto anualmente, siendo este una cantidad atractiva en el sector pues significa un monto de 1.5 millones de dólares por año. Por ello, se ha desarrollado un plan operativo que permita enfocarse en bajos costos operativos y una reparación oportuna, alineado a lo que los clientes valoran. Finalmente, nuestro plan financiero muestra que el proyecto obtiene indicadores positivos, VAN de 10,527 y TIR de 22 % en escenario esperado y una VAN de 86,736 y TIR de 60% en escenario optimista, durante un periodo de 5 años. / This research analyzes the viability of a business focused on providing a shock absorber repair service, aimed at open pit mining companies during their production phase. Being an alternative for mining companies to replace shock absorbers at a low operating cost, they replace it with new ones instead of recovering them, generating high replacement costs. The mining industry is a very relevant sector for the national economy, having a contribution of 10% of GDP in the last decade, so the business proposes an alternative that allows mining companies to have an adequate cost / performance indicator in the shock absorbers. The proposal focuses on repairing the two most used shock absorber brands in the national market, Foremost and Utex (King Cobra), at a low operating cost and in an adequate time for mining companies. It has been estimated that open pit mining companies use approximately 126 shock absorbers annually, this being an attractive amount in the sector since it means an amount of 1.5 million dollars per year. For this reason, an operating plan has been developed that allows focusing on low operating costs and timely repair, aligned with what customers value. Finally, our financial plan shows that the project obtains positive indicators, NPV of 10,527 and IRR of 22% in the expected scenario and a NPV of 86,736 and IRR of 60% in the optimistic scenario, during a period of 5 years. / Trabajo de investigación