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The approximate nearest neighbor(ANN) search over high dimensional data has become an unavoidable service for online applications. Fast and high-quality results of unknown queries are the largest challenge that most algorithms faced with. Locality Sensitive Hashing(LSH) is a well-known ANN search algorithm while suffers from inefficient index structure, poor accuracy in distributed scheme. The traditional index structures have most significant bits(MSB) problem, which is their indexing strategies have an implicit assumption that the bits from one direction in the hash value have higher priority. In this thesis, we propose a new content-based index called Random Draw Forest(RDF), which not only uses an adaptive tree structure by applying the dynamic length of compound hash functions to meet the different cardinality of data, but also applies the shuffling permutations to solve the MSB problem in the traditional LSH-based index. To raise the accuracy in the distributed scheme, we design a variable steps lookup strategy to search the multiple step sub-indexes which are most likely to hold the mistakenly partitioned similar objects. By analyzing the index, we show that RDF has a higher probability to retrieve the similar objects compare to the original index structure. In the experiment, we first learn the performance of different hash functions, then we show the effect of parameters in RDF and the performance of RDF compared with other LSH-based methods to meet the ANN search. / Thesis / Master of Science (MSc)

Yes / Aim To explore the challenges of engaging men with penile cancer in qualitative interview research. Background Qualitative interviewing offers an ideal tool for exploring men’s experiences of illness, complementing and providing context to gendered health inequalities identified in epidemiological research on men. But conducting interviews with men can be challenging and embarking on a qualitative interview study with males can feel like a daunting task, given the limited amount of practical, gender-sensitive guidance for researchers. Reflecting on a researcher’s experience of conducting qualitative research on men with penile cancer, this paper explores the potential challenges of interviewing this group, but also documents how engagement and data collection were achieved. Review methods This is a reflective paper, informed by the experiences of a male researcher (KW) with no nurse training, who conducted 28 interviews with men who had been treated for penile cancer. The researcher’s experiences are reported in chronological order, from the methodological challenges of recruitment to those of conducting the interview. Implications for practice/research The paper offers a resource for the novice researcher, highlighting some advantages and disadvantages of conducting qualitative interview research as a nurse researcher, as well as recommendations on how to overcome challenges. Conclusion Engaging men with penile cancer in qualitative interview raises practical, methodological, ethical and emotional challenges for the researcher. However, when these challenges are met, men will talk about their health. Methodological procedures must enable an open and ongoing dialogue with clinical gatekeepers and potential participants to promote engagement. Support from colleagues is essential for any interviewer, no matter how experienced the researcher is.

A numerical analysis of the loop tack test is presented to study the behavior of the strip and the influence of several factors, and the results are compared with experimental ones. The numerical results can be applied to model the performance of a pressure sensitive adhesive (PSA). Since the simulation of the loop tack test includes geometrical and material nonlinearities, it is solved numerically by the finite element method. The finite element program ABAQUS is used throughout the research. As the teardrop shaped loop is pushed down onto the adhesive and then pulled up, the variation of the loop behavior is investigated using two-dimensional (2D) and three-dimensional (3D) models. A bilinear elastic-plastic constitutive law is used for the strip. The deformation of the pressure sensitive adhesive is approximated as uniaxial extension of independent adhesive strands. A Winkler-type nonlinear elastic foundation and a viscoelastic foundation are used to model the PSA. A nonlinear elastic spring function is used, which is composed of a compression region for the bonding phase and a tension region for the debonding phase. A debonding failure criterion is assumed, in which an adhesive strand will debond when it reaches a certain length. During the bonding phase, it is assumed that the loop is perfectly bonded, and the contact time is not included. Curves of the pulling force versus the top displacement (i.e., tack curves) are obtained throughout the simulation. A parametric study is made with respect to the nonlinear spring function parameters, experimental uncertainties, and strip thickness. Anticlastic bending behavior is shown in the 3D analysis, and the contact patterns are presented. The effects of the elasticity modulus of the PSA for the elastic foundation and the displacement rate for the viscoelastic model are investigated. / Ph. D.

How might computer scientists work with communities in facilitating meaningful social change? In this project, we make a case for an approach that builds upon what the individuals and community already have---their assets---rather than emphasizing "user's needs" as typically postulated by human-centered design. We present details of our four-year-long assets-based engagement with an anti-trafficking organization in Nepal and the sex trafficking survivors supported by the organization. We explored the potential role that socio-technical systems and technology designers can play in assisting the survivors to build on their existing assets towards their vision of "dignified reintegration". The research involves three fieldwork and a remote study, each one leveraging carefully tailored socio-technical systems to investigate a design proposition. We present an operationalizable definition of assets and a framework of action to leverage assets in realizing change at an individual and institutional level. We describe the conditions that influenced the possibilities for our interventions and the factors that guided the design of the socio-technical systems. We further highlight how we adapted our methods to the local resources and practices in order to foster a space that promoted comfort and control to the study participants. The detailed account of our approach aims to provide a justification for undertaking slow, incremental steps with the community. / Doctor of Philosophy / Human trafficking survivors face a myriad of challenges in their reintegration journey. Working with an anti-trafficking organization in Nepal, I explored the potential role that technology and technology designers can play in assisting the survivors in their reintegration journey. The research involved three forays into fieldwork and a remote study, each one leveraging carefully tailored activities to investigate the possibilities for the survivors to be in a position of power once they leave the shelter home. The activities included technology such as a specifically tailored web application contextualized around the survivors' existing strengths but also involved non-digital components such as collectively envisioning broader possibilities and alternative futures and discussing ways in which the survivors could engage with local actors to mitigate societal problems they had seen near their homes. In all these activities, I adapted local practices and materials to promote a safe space for the survivors to participate from within their realm of comfort. This dissertation illuminates a potential pathway to engage in long-term community-based research with vulnerable populations. In particular, it makes a case for an approach that builds upon what the individuals and community already have, that is, their assets. The work illuminates ways to identify and build upon assets to support the survivors. Using the work, we make a case for undertaking slow, incremental steps as part of assets-based engagement with communities. The work emphasizes the need for technology developers to understand their responsibilities and carefully contemplate what elements of a situation or design allow ethical intervention. Finally, the work emphasizes the need for developers to be cognizant of how design of technology is tied up with the larger, multi-level system in which technology use is embedded.