Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: E. Glynn Harmon. Vita. Includes bibliographical references (leaves 141-147) Also available from UMI.

Privacy, including the right to privacy of correspondence, is a human right. Privacy-enhancing technologies, such as the Tor anonymity network, help maintain this right. The increasing use of Tor from mobile devices raises new challenges for the continued effectiveness of this low-latency anonymity network. Mobile Tor users may access the Internet from a range of wireless networks and service providers. Whenever a wireless network hands-off a mobile device’s connection from one access point to another, its external Internet Protocol (IP) address changes, and the connection to the Tor network is dropped. Every dropped connection requires the Tor circuit to be rebuilt. The time required to rebuild the circuit negatively impacts client performance. This research is the first to highlight this negative impact and to investigate the likely extent of the impact for typical usage scenarios and mobility models. The increased network churn caused by circuit rebuilding also negatively impacts anonymity. A novel metric (q-factor) is proposed here to measure the trade-off between anonymity and performance over the duration of a communication session. Two new solutions to the problems of managing mobility in a low-latency anonymity network are proposed in this thesis. The first solution relies on adaptive client throttling, based on a Kaplan-Meier estimator of the likelihood of a mobile network hand-off. The second solution relies on the use of a static bridge relay (mBridge) that acts as a persistent ‘home’ for a mobile Tor connection, so avoiding the need to recreate the Tor circuit whenever the mobile device is handed-off. The effectiveness of these solutions has been measured using the new q-factor metric. Both solutions provide better performance for mobile Tor clients than the standard Tor client implementation, although some performance reduction by comparison with static Tor clients remains. The bridge relay solution (mBridge) has been shown to offer better performance than client throttling, but is more vulnerable to certain types of attack. A strength of both solutions is that changes are restricted to client devices, the existing algorithms and protocols of the interior Tor network are unaffected.

Made available in DSpace on 2015-04-16T15:23:18Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1112772 bytes, checksum: 88c5be93fb55192b6f614c00a101fd75 (MD5) Previous issue date: 2012-03-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This research describes the profile of scientific production of the Graduate Program in Science of Information of Federal University of Paraiba, whose objective was to analyse thematic tendencies, the theoretical authors and the methods of research used in thesis produced in the period between 2008 and 2010, by students of this Graduate Program, taking into account the existent research lines: Ethics, Managing and Politics of Information and Memory, Organization, Access and Use of Information. It is a descriptive research, of a quantitative nature, developed with the bibliographical and bibliometric methods, whose studied universe was of 30 thesis. From the data obtained with this research, it is evident that the production of thesis, when compared to the objectives of the existing research lines in the Graduate Program referred, presents coherence between the studied themes and the interests of the research lines. It is important to point out the hole of CAPES which has contributed with the performance of Graduate Programs of Brazil with its evaluation criteria. So, when the results of this research were confronted with the requirements established by evaluations made by CAPES, they revealed a good level of quality of the thesis produced by the students of this program. Thus, through this research, one can conclude that, this program has a scientific production of quality which contributes to the consolidation of the Science of Information in Brazil. / Esta pesquisa descreve o perfil da produção científica do Programa de Pós-Graduação em Ciência da Informação da Universidade Federal da Paraíba PPGCI/UFPB, cujo objetivo foi analisar as tendências temáticas, os teóricos e os métodos de pesquisa utilizados nas dissertações produzidas no período compreendido entre os anos de 2008 a 2010, pelos discentes pertencentes ao PPGCI/UFPB, levando-se em consideração as linhas pesquisas existentes: Ética, Gestão e Políticas de Informação e Memória, Organização, Acesso e Uso da Informação. Trata-se de uma pesquisa descritiva, de natureza quantitativa, desenvolvida através dos métodos bibliográfico e bibliométrico, cujo universo estudado foi constituído por 30 dissertações. A partir dos dados obtidos nesta pesquisa, evidenciou-se que a produção das dissertações, quando comparadas aos objetivos das linhas de pesquisa existentes no referido Programa, apresenta coerência entre os temas estudados e os interesses das linhas. É importante ressaltar a atuação da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior CAPES, a qual tem contribuído com o desempenho dos Programas de Pós-Graduação do Brasil a partir de seus critérios de avaliações. Sendo assim, quando os resultados desta pesquisa foram confrontados com as exigências estabelecidas pelas avaliações realizadas pela CAPES, eles revelaram um bom nível de qualidade das dissertações produzidas pelos discentes do PPGCI/UFPB. Assim, através desta pesquisa conclui-se que o PPGCI/UFPB possui uma produção discente de qualidade, envidando esforços para a manutenção da mesma, contribuindo, assim, para a consolidação da Pós-Graduação em Ciência da Informação no Brasil.

Third party damage from activities such as work carried out by contractors’ poses risks to gas pipelines. Within the UK, emergency plans are drawn up in an attempt to mitigate the significant consequences of any pipeline failure. The Control of Major Accident Hazards 1999 and the Pipeline Safety Regulations 1996 place legislative requirements on UK gas infrastructure providers, to regularly test emergency plans with simulation exercises. The exercises are intended to support the preparation of responders for dealing with incidents of failure. Software simulation is not currently utilised to facilitate the testing of emergency response plans in the UK gas pipeline industry. This project serves to evaluate the user acceptance of a software simulation prototype to enable the testing of emergency response planning strategies in the UK gas industry. Current emergency planning legislation and strategies applied to satisfy legislation within the UK gas industry are reviewed. The adoption and application of software simulation for the development of applied skill in other industries is examined, to determine the potential for use in testing emergency response planning for gas incidents. The Technology Acceptance Model (TAM) is the theoretical framework that underpins the study of user acceptance, of a software simulation prototype designed for running exercises to test emergency response plans. A case study evaluation of the user acceptance of the prototype, by representatives experienced in testing emergency response planning strategies in the gas industry, is presented. The participants in this case study are drawn from the Police, Fire and Rescue Service, Local Authority and Gas infrastructure provider, that perform a range of job roles operating at Operational, Tactical and Strategical levels. The research findings demonstrate that the participants perceive software simulation of emergency response planning processes for gas incidents to be beneficial. The TAM claims that if users perceive a system to be useful they are likely to adopt that system. Furthermore if users don’t perceive a system to be easy to use, according to the TAM, they will still adopt it after the correct training has been provided. Users would be most likely to adopt and use the software to facilitate emergency response planning exercises, if the correct training is provided. Software simulation offers great potential for the testing of emergency plans, it provides a controlled environment where decisions and responses can be audited and mistakes can be made without serious consequence. Software simulation has been shown to enhance, rather than replace, existing emergency response planning processes.

This research aims to develop a realistic solution to enhance the efficiency of a transport logistics operation. The case study in this research is one of the largest agricultural suppliers in Northern Thailand. The cost of logistics in Thailand is relatively high compared to other countries, i.e. 11% of Gross Domestic Product (GDP) in 2007, and is particularly high in agricultural sector. The focus of the study is to enhance and improve transportation activities which typically account for the largest cost in logistics. The research is entitled ‘RFID enabled constraint based scheduling for transport logistics ’ The dissertation studies two important research components: 1) the data acquisition using Radio Frequency Identification Technology (RFID) for monitoring vehicles in a depot and 2) the scheduling by solving Constraint Satisfaction Optimisation Problem (CSOP) using Constraint Programming (CP). The scheduling problem of the research is to compose and schedule a fleet in which both private and subcontracting (outsourcing) vehicles are available, but to minimise the use of subcontractors. Several contributions from this study can be identified at each stage of the study ranging from extensively reviewing the literature, field studies, developing the RFID prototype system for vehicle tracking, modelling and solving the defined scheduling problems using Constraint Programming, developing a RFID-CP based real time scheduling, and validating the proposed methods. A number of validations are also carried out throughout the research. For instance, laboratory based experiments were conducted to measure the performance of the developed RFID tracking system in different configurations. Scenario tests were used to test the correctness of the proposed CP-based scheduling system, and structure interviews were used to collect feedbacks on the developed prototype from the case study company.

This thesis investigates techniques for the automated optimization of quantum circuits. In the first part we develop an exponential time algorithm for synthesizing minimal depth quantum circuits. We combine this with effective heuristics for reducing the search space, and show how it can be extended to different optimization problems. We then use the algorithm to compute circuits over the Clifford group and T gate for many of the commonly used quantum gates, improving upon the former best known circuits in many cases. In the second part, we present a polynomial time algorithm for the re-synthesis of CNOT and T gate circuits while reducing the number of phase gates and parallelizing them. We then describe different methods for expanding this algorithm to optimize circuits over Clifford and T gates.

Thesis (Ph. D.)--Universität Essen, 1996. / Includes bibliographical references.

<p> The Internet, as a digital record of human discourse, provides an opportunity to directly analyze political communicative behavior. The rapid emergence of social online networks augurs a transformation in the quality and quantity of information people have to evaluate their political system. Digital formats instantiate new categories of actors and new capacities to intervene in political discourse. Existing theories of political communication fail to account for the time lag, speed, anonymity and nature of replication inherent in digital formats. To fully investigate the digital record, scholars need a new framework that apprehends the complex density of a multidirectional political discourse that defies traditional time controls. </p><p> Using information and linguistic theory we develop and apply a functional, information flow model that illuminates the conceptual relationships and capacities of people to shape their information environment. Actors are defined in terms of their communicative role in idea exchange and the logic of communication is alloyed with political considerations to examine the scopes of action and immersion scenarios that affect communicants. </p><p> Our modular and scalable theory offers a way to measure signal fidelity, node activation, and message branching. We define signaling and amplification schemes and effects and explore the benefits and disadvantages of amplification devices for speakers and recipients. We show how individual actors are linked by the micro information streams they receive and transmit. We are therefore able to model exposure conditions of a multiple input, noisy spectrum for citizens and provide a counterpoint to the simple, controlled environment of agenda-setting experiments.</p><p> Finally, due to its foundation in information theory, our framework provides a natural platform by which to organize and develop a research program that uses computational linguistics and data mining techniques.</p>

This thesis investigates techniques for the automated optimization of quantum circuits. In the first part we develop an exponential time algorithm for synthesizing minimal depth quantum circuits. We combine this with effective heuristics for reducing the search space, and show how it can be extended to different optimization problems. We then use the algorithm to compute circuits over the Clifford group and T gate for many of the commonly used quantum gates, improving upon the former best known circuits in many cases. In the second part, we present a polynomial time algorithm for the re-synthesis of CNOT and T gate circuits while reducing the number of phase gates and parallelizing them. We then describe different methods for expanding this algorithm to optimize circuits over Clifford and T gates.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 169-179).