Exploration vs. Exploitation in the Information Filtering Problem

We consider information filtering, in which we face a stream of items too voluminous to process by hand (e.g., scientific articles, blog posts, emails), and must rely on a computer system to automatically filter out irrelevant items. Such systems face the exploration vs. exploitation tradeoff, in which it may be beneficial to present an item despite a low probability of relevance, just to learn about future items with similar content. We present a Bayesian sequential decision-making model of this problem, show how it may be solved to optimality using a decomposition to a collection of two-armed bandit problems, and show structural results for the optimal policy. We show that the resulting method is especially useful when facing the cold start problem, i.e., when filtering items for new users without a long history of past interactions. We then present an application of this information filtering method to a historical dataset from the arXiv.org repository of scientific articles.Comment: 36 pages, 5 figure

Comparison of alternatives to amplitude thresholding for onset detection of acoustic emission signals

Acoustic Emission (AE) monitoring can be used to detect the presence of damage as well as determine its location in Structural Health Monitoring (SHM) applications. Information on the time difference of the signal generated by the damage event arriving at different sensors in an array is essential in performing localisation. Currently, this is determined using a fixed threshold which is particularly prone to errors when not set to optimal values. This paper presents three new methods for determining the onset of AE signals without the need for a predetermined threshold. The performance of the techniques is evaluated using AE signals generated during fatigue crack growth and compared to the established Akaike Information Criterion (AIC) and fixed threshold methods. It was found that the 1D location accuracy of the new methods was within the range of <1–7.1%<1–7.1% of the monitored region compared to 2.7% for the AIC method and a range of 1.8–9.4% for the conventional Fixed Threshold method at different threshold levels

GoGlobal Rural-Urban

This is a book of edited articles and design projects from five years of collaborative international design projects in developed and developing economies, including China, Thailand, Ghana and Japan. Part One contains articles on initiatives including e-commerce models for developing economies, massclusivity and craft design. Part Two is dedicated to design solutions for China’s rural-urban migration issues, which affect 55 million people a year. The project enhances knowledge about the application of design thinking to national-level issues connecting policy to implementation, extending design activity into large-scale social and economic areas. The book follows an exhibition of design outcomes in London and Beijing (2010). Hall developed his chapter (‘Go Global: Ghana’) from a conference paper given at the ‘International Association of Societies of Design Research Conference’, South Korea (2009) and further expanded as a book chapter (with Barker) entitled ‘e-Artisans: Contemporary design for the global market’ in Global Design History (2011). ‘eArtisans’ researched a proposed e-commerce model linking designer-craftsmen with a global Internet sale and distribution model for African countries. The originality lay in proposing and testing knowledge, through design collaborations, in a combination of e-commerce enterprise models; it was significant in deploying the proposed model in an experimental educational initiative. The research was based on previous experience of design, craft and enterprise projects in Thailand and China, and aligned with a creative economies report by UNESCO (2008). The context was a collaboration at the KNUST, Kumasi, Ghana, where action-based research methods resulted in a case study illustrating cultural transfer. Support and partnership were also provided by Aid To Artisans, the British Council and Africa 53. A vital aspect was the discovery of how an e-commerce model changed design concepts and creative proposals. The GoGlobal project has continued with an edited publication, Designing Social City Experiences (Jin Nam and Hall 2013)

Efficient quantum repeater based on deterministic Rydberg gates

We propose an efficient quantum repeater architecture with mesoscopic atomic ensembles, where the Rydberg blockade is employed for deterministic local entanglement generation, entanglement swapping and entanglement purification. Compared with conventional atomic-ensemble-based quantum repeater, the entanglement distribution rate is improved by up to two orders of magnitude with the help of the deterministic Rydberg gate. This new quantum repeater scheme is robust and fast, and thus opens up a new way for practical long-distance quantum communication.Comment: 5 pages, 2 figure