Most e-commerce websites that sell technological items provide a simplified Queryby-Example preference elicitation approach to enable users to search for the product that they desire by specifying constraints over criteria and filtering results. Such an interface may be adequate when the technical specification is known. In this work, the usability of an alternative preference elicitation approach, Pairwise Comparisons, that enable users to specify trade-offs between various potentially conflicting criteria, is compared and contrasted to the traditional Query-by-Example approach. This is done by implementing two search tools that implement each preference elicitation approach to collect data about user behaviour. An experiment is carried out to evaluate performance and usability to search for laptops over a web scraped data set for varied tasks. It is found that while Query-by-Example tends to be preferred for cases where the technical specification criteria are precisely specified, the result sets generated for the Pairwise Comparisons approach are preferred when it is less clear what the criteria values should be. As such, the Pairwise Comparisons preference elicitation is deemed to be a worthwhile complementary approach for such e-commerce websites.

The fifth chapter presents all the results obtained for internal flow and the geometrical characterization of the injectors. Chapter six encompass the results obtained when studying the spray from a microscopic point of view at isothermal conditions: velocity and SMD trends are obtained and some empirical equations are estimated in other

Agradeço a Deus por ter me dado penetração para entender, memória para reter, método para aprender e lucidez para interpretar e me expressar durante minha formação acadêmica (oração do estudante). Eu gostaria expressar minha gratidão com meu orientador, Prof. Dr. Fernando José Gomes Landgraf pelo continuo apoio durante meu mestrado. Sua paciência, motivação, conhecimento e orientação foram de imensa ajuda no desenvolvimento do trabalho e minha formação. Por tudo obrigado. A minha família por todo seu carinho, amor, motivação e compreensão, meus pais Claudia Hernández e Jairo Guzmán, meus irmãos, Jair Guzmán e Jose Suarez, minhas tias, Sandra Hernández e Laura Hernández, meus avós, Betty Hernández e Jorge Hernández e meus primos Daniel Vega e Isabel Saltarin e Albina Hernández. A Marina Moretão, Arthur Moretão, e seus pais Neiva e Pedrinho por me receber na sua família durante minha estância no Brasil.