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Thesis (Ph.D.)--York University, 2008. Graduate Programme in Mathematics and Statistics. / Typescript. Includes bibliographical references (leaves 81-83). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR39029

Webserver logfiles are an inexpensive, automatically captured text-based recording of user interactions with a website. In this thesis, a tool, ViDLog, was created to take logfiles and reanimate a user session with the purpose of gaining usability insights. To evaluate the effectiveness and value of reanimating user sessions, 10 usability professionals viewed logfile-recorded website usage using ViDLog and were then asked to infer users’ goals, strategies, successes or failures, and proficiencies; and afterwards, rate, ViDLog across multiple dimensions. ViDLog’s logfile reanimation proved successful for gaining usability insights; usability professionals were able to infer users’ goals, strategies, successes or failures, and proficiencies. Participants were able to do this without ViDLog training, without familiarity of the website being evaluated (Orlando), and without domain knowledge of the subject depicted in the user sessions (women’s literature). However, they were only able to infer users’ overarching goal, not specific goal criteria; and were only able to determine relative proficiencies after viewing both user sessions. They also expended a good deal of mental effort when comprehending ambiguous user sessions, and found inefficiencies in ViDLog’s user interface. / Dr. Susan Brown for The Orlando Project

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Lazy replication with snapshot isolation (SI) has emerged as a popular choice for distributed databases. However, lazy replication requires the execution of update transactions at one (master) site so that it is relatively easy for a total SI order to be determined for consistent installation of updates in the lazily replicated system. We propose a set of techniques that support update transaction execution over multiple partitioned sites, thereby allowing the master to scale. Our techniques determine a total SI order for update transactions over multiple master sites without requiring global coordination in the distributed system, and ensure that updates are installed in this order at all sites to provide consistent and scalable replication with SI. We have built our techniques into PostgreSQL and demonstrate their effectiveness through experimental evaluation.

The speed of fuzzy controllers implemented on dedicated hardware is adequate for control of any physical process, but too slow for todays high-complexity data networks. Defuzzification has been the bottleneck for fast implementations due to the large number of computationally expensive multiplication and division operations. In this thesis, we propose a high-speed fuzzy inferential system based on log-domain arithmetic, which only requires addition and subtraction operations. The system is implemented on a Xilinx Virtex-II FPGA with a processing speed of 67.6 MFLIPS having a maximum combinational path delay of 4.2 ns. It is a clear speedup compared to the reported fastest 50 MFLIPS implementation. A pipelined version of the controller is also implemented, which achieves a speed of 248.7 MFLIPS. Although a small approximation error is introduced, software simulation and hardware implementation on FPGA confirm high similarity of the outputs for control surfaces and a number of second-order plants. / Software Engineering and Intelligent Systems

Fachhochsch. für Wirtschaft, Diplomarbeit, 2006--Berlin.

Zugl.: Bremen, Hochsch., Diplomarbeit, 2007

Thesis (Ph. D.)--State University of New York at Binghamton, Mathematical Sciences Department or Field of Study, 2007. / Includes bibliographical references.