Browsing by Subject "Densification"
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Item Film deposition and mechanical properties of silver produced by impaction of nanoparticles(2012-12) Noiseau, Guillaume Jack Nicolas; Kovar, Desiderio; Becker, Michael FNanocrystalline films are promising in various fields such as microelectronics. Low temperature deposition techniques are desirable since they would enable the use of new substrates that are temperature sensitive, leading to a wide range of new applications. This thesis explores nanocrystalline silver film deposition by impacting nanoparticles (NP) onto a substrate, a technique that enables low process temperatures. This work aims at better understanding the physical parameters governing the sticking probability of NP upon impaction. To achieve this, various substrate materials have been used (metallic and non metallic) and the influence of the impacted substrate temperature has been studied, among other experiments. These parameters showed a significant influence on the collection efficiency of NPs. These experimental results are analyzed in light of published computer simulations studies predicting the behavior of impacting NP to deposit nanostructured films. Secondly, a study of the mechanical properties of the deposited films has been attempted. Compression tests have been carried out varying the applied load, loading time and process temperature. The produced films are nanocrystalline and porous (~70% relative density). Densification has been observed even at room temperature, and the goal of this study is to understand which mechanisms cause the densification to occur. The experimental densification data are compared with a model describing the densification of microparticles compacts by hot pressing that has been adapted to nanocrystalline silver, and the mechanisms leading to densification are discussed.Item Housing access and governance : the case of densification efforts in Mexico City, 2001-2012(2013-05) Reyes Ruiz Del Cueto, Laura Alejandra; Dooling, SarahLack of access to adequate housing in Mexico City's urban core and sprawling settlement patterns have led to numerous social and environmental issues. Current development patterns sharpen social fragmentation and segregation, create imbalances in the provision of infrastructure and services, and encourage human occupation of high-risk and environmentally susceptible areas. Furthermore, expansive urbanization has become increasingly expensive, both at the individual and collective level. This has happened because private interests often overshadow public ones; economic growth rather than equitable and sustainable development has been the mark of success. Thus, commercial uses have displaced residential uses, particularly low-income housing, to remote areas of the metropolitan region. Local government efforts, albeit significant in comparison to other parts of the country, have been unable to adequately address this issue. Government inefficiency, lack of inter-institutional coordination, corruption, and lack of resources, among other factors, have hindered the success of housing and densification projects. The present research evaluates recent densification efforts and their goals to increase housing access and repopulate the urban core. Some of the individual benefits enjoyed by residents of densification projects, such as access to infrastructure and services, as well as some of the difficulties experienced by them in the process of obtaining government credits and access to housing are also identified. The conclusion is that only the rigorous integration of environmental and social planning agendas and the renegotiation of concepts of spatial justice will lead to more effective policies and housing programs, and a just, accessible, and sustainable city, region and country.