In concept, online communities allow people to access the wide range of knowledge and abilities of a heterogeneous group of users. In reality, current implementations of various online communities suffer from a lack of participation by the most qualified users. The participation of qualified users, or experts, is crucial to the social welfare and widespread adoption of such systems. This research proposes techniques for identifying the most valuable contributors to several classes of online communities, including question and answer (QA) forums and other content-oriented social networks. Once these target users are identified, content recommendation and novel quantitative incentives can be used to encourage their participation. This research represents an in-depth investigation into QA systems, while the major findings are widely applicable to online communities in general. An algorithm for recommending content in a QA forum is introduced which can route questions to the most appropriate responders. This increases the efficiency of the system and reduces the time investment of an expert responder by eliminating the need to search for potential questions to answer. This recommender is analyzed using real data captured from Yahoo! Answers. Additionally, an incentive mechanism for QA systems based on a novel class of incentives is developed. This mechanism relies on systemic rewards, or rewards that have tangible value within the framework of the online community. This research shows that human users have a strong preference for reciprocal systemic rewards over traditional rewards, and a simulation of a QA system based on an incentive that utilizes these reciprocal rewards outperforms a leading incentive mechanism according to expert participation. An architecture is developed for a QA system built upon content recommendation and this novel incentive mechanism. This research shows that it is possible to identify the most valuable contributors to an online community and motivate their participation through a novel incentive mechanism based on meaningful rewards. / text

In my teaching and software development practice, I realized that most applications with human-computer interaction do not respond to users’ emotional needs. The dualism of reason and emotion as two fairly opposite entities that dominated Western philosophy was also reflected in software design. Computing was originally intended to provide applications for military and industrial activities and was primarily associated with cognition and rationality. Today, more and more computer applications interact with users in very complex and sophisticated ways. In human-computer interaction, attention is given to issues of usability and user modeling, but techniques to emotionally engage users or respond to their emotional needs have not been fully developed, even as specialists like Klein, Norman and Picard argued that machines that recognize and express emotions respond better and more appropriately to user interaction (Picard, 1997; Picard & Klein, 2002; Norman, 2004). This study investigated emotion from designers’ perspectives and tentatively concludes that there is little awareness and involvement in emotional design in the IT community. By contrast, participants in this study (36 IT specialists from various fields) strongly supported the idea of emotional design and confirmed the need for methodologies and theoretical models to research emotional design. Based on a review of theory, surveys and interviews, I identified a set of themes for heuristics of emotional design and recommended future research directions. Attention was given to consequences; participants in this study raised issues of manipulation, ethical responsibilities of designers, and the need for regulations, and recommended that emotional design should carry standard ethical guidelines for games and any other applications. The research design utilized a mixed QUAN-qual methodological model proposed by Creswell (2003) and Gay, Mills, and Airasian (2006), which was modified to equally emphasize both quantitative and qualitative stages. An instrument in the form of a questionnaire was designed, tested and piloted in this study and will be improved and used in future research.

Doctor of Philosophy / Department of Computer Science / William H. Hsu / Current research in the field of recommender systems takes into consideration the interaction between users and items; we call this the homogeneous setting. In most real world systems, however these interactions are heterogeneous, i.e., apart from users and items there are other types of entities present within the system, and the interaction between the users and items occurs in multiple contexts and scenarios. The presence of multiple types of entities within a heterogeneous information network, opens up new interaction modalities for generating recommendations to the users. The key contribution of the proposed dissertation is representation learning in heterogeneous information networks for the recommendations task. Query-based information retrieval is one of the primary ways in which meaningful nuggets of information is retrieved from large amounts of data. Here the query is represented as a user's information need. In a homogeneous setting, in the absence of type and contextual side information, the retrieval context for a user boils down to the user's preferences over observed items. In a heterogeneous setting, information regarding entity types and preference context is available. Thus query-based contextual recommendations are possible in a heterogeneous network. The contextual query could be type-based (e.g., directors, actors, movies, books etc.) or value-based (e.g., based on tag values, genre values such as ``Comedy", ``Romance") or a combination of Types and Values. Exemplar-based information retrieval is another technique for of filtering information, where the objective is to retrieve similar entities based on a set of examples. This dissertation proposes approaches for recommendation tasks in heterogeneous networks, based on these retrieval mechanisms present in traditional information retrieval domain.

Este trabalho apresenta uma análise a respeito das restrições técnicas e comportamentais que dificultam a disseminação dos serviços móveis, tais como portais WAP. A análise foca na restrição relacionada à usabilidade das aplicações. Considerando que há um consenso de que a adaptação das aplicações móveis, em função de variáveis de contexto como: perfil do usuário, ambiente de uso e características do terminal e da rede, é uma possível solução para melhorar a usabilidade destas aplicações, analisam-se estas técnicas, concentrando-se na Modelagem do Usuário (MU) como mecanismo para a adaptação e personalização. Pretende-se analisar e testar em que medida esta abordagem de adaptação venha a melhorar a usabilidade destas aplicações móveis. Propõe-se teste de serviço móvel, baseado em uma página WAP, implementada com técnicas que permitam a adaptação. Este serviço permitirá acesso às informações de trâmites e pendências de processos burocráticos da Superintendência Regional do INCRA no Rio Grande do Sul. / This paper presents an analysis about the technical and behavioural restrictions that hinder the dissemination of mobile services, such as WAP portals. The analysis focuses on the restriction related to the usability of applications. Whereas there is a consensus that the adjustment of mobile applications depending on context, user profile, environment of conditions and use the network, characteristics a possible solution to improve the usability of these applications is to analyse these techniques focusing on modeling the User as a mechanism for adaptation and customization. The aim is to examine and test if this approach to adaptation improve the usability of these mobile applications. It is proposed to test mobile service, based on a WAP page, implemented with techniques that allow the adjustment. This service will provide access to the information and outstanding manner of bureaucratic processes of the Superintendência Regional do INCRA in Rio Grande do Sul.

Este trabalho apresenta uma análise a respeito das restrições técnicas e comportamentais que dificultam a disseminação dos serviços móveis, tais como portais WAP. A análise foca na restrição relacionada à usabilidade das aplicações. Considerando que há um consenso de que a adaptação das aplicações móveis, em função de variáveis de contexto como: perfil do usuário, ambiente de uso e características do terminal e da rede, é uma possível solução para melhorar a usabilidade destas aplicações, analisam-se estas técnicas, concentrando-se na Modelagem do Usuário (MU) como mecanismo para a adaptação e personalização. Pretende-se analisar e testar em que medida esta abordagem de adaptação venha a melhorar a usabilidade destas aplicações móveis. Propõe-se teste de serviço móvel, baseado em uma página WAP, implementada com técnicas que permitam a adaptação. Este serviço permitirá acesso às informações de trâmites e pendências de processos burocráticos da Superintendência Regional do INCRA no Rio Grande do Sul. / This paper presents an analysis about the technical and behavioural restrictions that hinder the dissemination of mobile services, such as WAP portals. The analysis focuses on the restriction related to the usability of applications. Whereas there is a consensus that the adjustment of mobile applications depending on context, user profile, environment of conditions and use the network, characteristics a possible solution to improve the usability of these applications is to analyse these techniques focusing on modeling the User as a mechanism for adaptation and customization. The aim is to examine and test if this approach to adaptation improve the usability of these mobile applications. It is proposed to test mobile service, based on a WAP page, implemented with techniques that allow the adjustment. This service will provide access to the information and outstanding manner of bureaucratic processes of the Superintendência Regional do INCRA in Rio Grande do Sul.

Este trabalho apresenta uma análise a respeito das restrições técnicas e comportamentais que dificultam a disseminação dos serviços móveis, tais como portais WAP. A análise foca na restrição relacionada à usabilidade das aplicações. Considerando que há um consenso de que a adaptação das aplicações móveis, em função de variáveis de contexto como: perfil do usuário, ambiente de uso e características do terminal e da rede, é uma possível solução para melhorar a usabilidade destas aplicações, analisam-se estas técnicas, concentrando-se na Modelagem do Usuário (MU) como mecanismo para a adaptação e personalização. Pretende-se analisar e testar em que medida esta abordagem de adaptação venha a melhorar a usabilidade destas aplicações móveis. Propõe-se teste de serviço móvel, baseado em uma página WAP, implementada com técnicas que permitam a adaptação. Este serviço permitirá acesso às informações de trâmites e pendências de processos burocráticos da Superintendência Regional do INCRA no Rio Grande do Sul. / This paper presents an analysis about the technical and behavioural restrictions that hinder the dissemination of mobile services, such as WAP portals. The analysis focuses on the restriction related to the usability of applications. Whereas there is a consensus that the adjustment of mobile applications depending on context, user profile, environment of conditions and use the network, characteristics a possible solution to improve the usability of these applications is to analyse these techniques focusing on modeling the User as a mechanism for adaptation and customization. The aim is to examine and test if this approach to adaptation improve the usability of these mobile applications. It is proposed to test mobile service, based on a WAP page, implemented with techniques that allow the adjustment. This service will provide access to the information and outstanding manner of bureaucratic processes of the Superintendência Regional do INCRA in Rio Grande do Sul.

Within user modeling there are various methods for representing targeted users. Persona for example is a user archetype which is given a face and name, and is carefully described in terms of goals, needs, and tasks (Blomquist & Arvola, 2002). Personas are widely used, but have been criticized for often not being based on empirical data (McGinn & Kotamraju, 2008). In this thesis I explore the use of the Repertory grid technique (RGT) in a user modeling context, an approach deriving from George Kelly’s (1955) Personal construct theory, which elicits both idiographic (i.e. the subjective dimensions of one individual) and nomothetic (i.e. a populations behaviours and traits) empirical data from individuals by analysing both qualitative and quantitative data. Furthermore, the possibilities and difficulties that the RGT offers in the context of user modeling are investigated. An online survey is crowdsourced (n = 28) containing five vignettes which are based on structured interviews and are used to elicit the participant’s personal constructs. The results are presented in the form of bertin plots and a biplot along with the Importance (the order of a constructs elicitation), and Dominance (the relative elicitation percentage of a construct) measures. The results suggest that the technique employed could be used in a number of user modelling processes. The weaknesses of RGT when done remotely in a user modelling context are also discussed.

In my teaching and software development practice, I realized that most applications with human-computer interaction do not respond to usersâ emotional needs. The dualism of reason and emotion as two fairly opposite entities that dominated Western philosophy was also reflected in software design. Computing was originally intended to provide applications for military and industrial activities and was primarily associated with cognition and rationality. Today, more and more computer applications interact with users in very complex and sophisticated ways. In human-computer interaction, attention is given to issues of usability and user modeling, but techniques to emotionally engage users or respond to their emotional needs have not been fully developed, even as specialists like Klein, Norman and Picard argued that machines that recognize and express emotions respond better and more appropriately to user interaction (Picard, 1997; Picard & Klein, 2002; Norman, 2004). This study investigated emotion from designersâ perspectives and tentatively concludes that there is little awareness and involvement in emotional design in the IT community. By contrast, participants in this study (36 IT specialists from various fields) strongly supported the idea of emotional design and confirmed the need for methodologies and theoretical models to research emotional design. Based on a review of theory, surveys and interviews, I identified a set of themes for heuristics of emotional design and recommended future research directions. Attention was given to consequences; participants in this study raised issues of manipulation, ethical responsibilities of designers, and the need for regulations, and recommended that emotional design should carry standard ethical guidelines for games and any other applications. The research design utilized a mixed QUAN-qual methodological model proposed by Creswell (2003) and Gay, Mills, and Airasian (2006), which was modified to equally emphasize both quantitative and qualitative stages. An instrument in the form of a questionnaire was designed, tested and piloted in this study and will be improved and used in future research. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

User modeling enables in the computation of the traffic density in a cellular network, which can be used to optimize the placement of base stations and radio network controllers as well as to analyze the performance of resource management algorithms towards meeting the final goal: the calculation and maximization of network capacity and throughput for different data rate services. An analytical model is presented for approximating the user distributions in multi-cell third generation wideband code division multiple access (WCDMA) networks using 2-dimensional Gaussian distributions by determining the means and the standard deviations of the distributions for every cell. This model allows for the calculation of the inter-cell interference and the reverse-link capacity of the network. An analytical model for optimizing capacity in multi-cell WCDMA networks is presented. Capacity is optimized for different spreading factors and for perfect and imperfect power control. Numerical results show that the SIR threshold for the received signals is decreased by 0.5 to 1.5 dB due to the imperfect power control. The results also show that the determined parameters of the 2-dimensional Gaussian model match well with traditional methods for modeling user distribution. A call admission control algorithm is designed that maximizes the throughput in multi-cell WCDMA networks. Numerical results are presented for different spreading factors and for several mobility scenarios. Our methods of optimizing capacity and throughput are computationally efficient, accurate, and can be implemented in large WCDMA networks.

Social media services have a growing impact in our society. Individuals often rely on social media to get their news, decide which products to buy or to communicate with their friends. As consequence of the widespread adoption of social media, a large volume of data on how users behave is created every day and stored into large databases. Learning how to analyze and extract useful knowledge from this data has a number of potential applications. For instance, a deeper understanding on how legitimate users interact with social media services could be explored to design more accurate spam and fraud detection methods. This PhD research is based on the following hypothesis: data generated by social media users present patterns that can be exploited to improve the effectiveness of tasks such as prediction, forecasting and modeling in the domain of social media. To validate our hypothesis, we focus on designing data mining methods tailored to social media data. The main contributions of this PhD can be divided into three parts. First, we propose Act-M, a mathematical model that describes the timing of users actions. We also show that Act-M can be used to automatically detect bots among social media users based only on the timing (i.e. time-stamp) data. Our second contribution is VnC (Vote-and-Comment), a model that explains how the volume of different types of user interactions evolve over time when a piece of content is submitted to a social media service. In addition to accurately matching real data, VnC is useful, as it can be employed to forecast the number of interactions received by social media content. Finally, our third contribution is the MFS-Map method. MFS-Map automatically provides textual annotations to social media images by efficiently combining visual and metadata features. Our contributions were validated using real data from several social media services. Our experiments show that the Act-M and VnC models provided a more accurate fit to the data than existing models for communication dynamics and information diffusion, respectively. MFS-Map obtained both superior precision and faster speed when compared to other widely employed image annotation methods. / O impacto dos serviços de mídia social em nossa sociedade é crescente. Indivíduos frequentemente utilizam mídias sociais para obter notícias, decidir quais os produtos comprar ou para se comunicar com amigos. Como consequência da adoção generalizada de mídias sociais, um grande volume de dados sobre como os usuários se comportam é gerado diariamente e armazenado em grandes bancos de dados. Aprender a analisar e extrair conhecimentos úteis a partir destes dados tem uma série de potenciais aplicações. Por exemplo, um entendimento mais detalhado sobre como usuários legítimos interagem com serviços de mídia social poderia ser explorado para projetar métodos mais precisos de detecção de spam e fraude. Esta pesquisa de doutorado baseia-se na seguinte hipótese: dados gerados por usuários de mídia social apresentam padrões que podem ser explorados para melhorar a eficácia de tarefas como previsão e modelagem no domínio das mídias sociais. Para validar esta hipótese, foram projetados métodos de mineração de dados adaptados aos dados de mídia social. As principais contribuições desta pesquisa de doutorado podem ser divididas em três partes. Primeiro, foi desenvolvido o Act-M, um modelo matemático que descreve o tempo das ações dos usuários. O autor demonstrou que o Act-M pode ser usado para detectar automaticamente bots entre usuários de mídia social com base apenas nos dados de tempo. A segunda contribuição desta tese é o VnC (Vote-and- Comment), um modelo que explica como o volume de diferentes tipos de interações de usuário evolui ao longo do tempo quando um conteúdo é submetido a um serviço de mídia social. Além de descrever precisamente os dados reais, o VnC é útil, pois pode ser empregado para prever o número de interações recebidas por determinado conteúdo de mídia social. Por fim, nossa terceira contribuição é o método MFS-Map. O MFS-Map fornece automaticamente anotações textuais para imagens de mídias sociais, combinando eficientemente características visuais e de metadados das imagens. As contribuições deste doutorado foram validadas utilizando dados reais de diversos serviços de mídia social. Os experimentos mostraram que os modelos Act-M e VnC forneceram um ajuste mais preciso aos dados quando comparados, respectivamente, a modelos existentes para dinâmica de comunicação e difusão de informação. O MFS-Map obteve precisão superior e tempo de execução reduzido quando comparado com outros métodos amplamente utilizados para anotação de imagens.