3,619 research outputs found

    Addressing practical challenges of Bayesian optimisation

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    This thesis focuses on addressing several challenges in applying Bayesian optimisation in real world problems. The contributions of this thesis are new Bayesian optimisation algorithms for three practical problems: finding stable solutions, optimising cascaded processes and privacy-aware optimisation

    Hybrid Cloud-Based Privacy Preserving Clustering as Service for Enterprise Big Data

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    Clustering as service is being offered by many cloud service providers. It helps enterprises to learn hidden patterns and learn knowledge from large, big data generated by enterprises. Though it brings lot of value to enterprises, it also exposes the data to various security and privacy threats. Privacy preserving clustering is being proposed a solution to address this problem. But the privacy preserving clustering as outsourced service model involves too much overhead on querying user, lacks adaptivity to incremental data and involves frequent interaction between service provider and the querying user. There is also a lack of personalization to clustering by the querying user. This work “Locality Sensitive Hashing for Transformed Dataset (LSHTD)” proposes a hybrid cloud-based clustering as service model for streaming data that address the problems in the existing model such as privacy preserving k-means clustering outsourcing under multiple keys (PPCOM) and secure nearest neighbor clustering (SNNC) models, The solution combines hybrid cloud, LSHTD clustering algorithm as outsourced service model. Through experiments, the proposed solution is able is found to reduce the computation cost by 23% and communication cost by 6% and able to provide better clustering accuracy with ARI greater than 4.59% compared to existing works

    Privacy-preserving social network analysis

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    Data privacy in social networks is a growing concern that threatens to limit access to important information contained in these data structures. Analysis of the graph structure of social networks can provide valuable information for revenue generation and social science research, but unfortunately, ensuring this analysis does not violate individual privacy is difficult. Simply removing obvious identifiers from graphs or even releasing only aggregate results of analysis may not provide sufficient protection. Differential privacy is an alternative privacy model, popular in data-mining over tabular data, that uses noise to obscure individuals\u27 contributions to aggregate results and offers a strong mathematical guarantee that individuals\u27 presence in the data-set is hidden. Analyses that were previously vulnerable to identification of individuals and extraction of private data may be safely released under differential-privacy guarantees. However, existing adaptations of differential privacy to social network analysis are often complex and have considerable impact on the utility of the results, making it less likely that they will see widespread adoption in the social network analysis world. In fact, social scientists still often use the weakest form of privacy protection, simple anonymization, in their social network analysis publications. ^ We review the existing work in graph-privatization, including the two existing standards for adapting differential privacy to network data. We then proposecontributor-privacy and partition-privacy , novel standards for differential privacy over network data, and introduce simple, powerful private algorithms using these standards for common network analysis techniques that were infeasible to privatize under previous differential privacy standards. We also ensure that privatized social network analysis does not violate the level of rigor required in social science research, by proposing a method of determining statistical significance for paired samples under differential privacy using the Wilcoxon Signed-Rank Test, which is appropriate for non-normally distributed data. ^ Finally, we return to formally consider the case where differential privacy is not applied to data. Naive, deterministic approaches to privacy protection, including anonymization and aggregation of data, are often used in real world practice. De-anonymization research demonstrates that some naive approaches to privacy are highly vulnerable to reidentification attacks, and none of these approaches offer the robust guarantee of differential privacy. However, we propose that these methods fall across a range of protection: Some are better than others. In cases where adding noise to data is especially problematic, or acceptance and adoption of differential privacy is especially slow, it is critical to have a formal understanding of the alternatives. We define De Facto Privacy, a metric for comparing the relative privacy protection provided by deterministic approaches

    Modeling, Predicting and Capturing Human Mobility

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    Realistic models of human mobility are critical for modern day applications, specifically for recommendation systems, resource planning and process optimization domains. Given the rapid proliferation of mobile devices equipped with Internet connectivity and GPS functionality today, aggregating large sums of individual geolocation data is feasible. The thesis focuses on methodologies to facilitate data-driven mobility modeling by drawing parallels between the inherent nature of mobility trajectories, statistical physics and information theory. On the applied side, the thesis contributions lie in leveraging the formulated mobility models to construct prediction workflows by adopting a privacy-by-design perspective. This enables end users to derive utility from location-based services while preserving their location privacy. Finally, the thesis presents several approaches to generate large-scale synthetic mobility datasets by applying machine learning approaches to facilitate experimental reproducibility
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