Articles — Recent

A presentation about Statistical Linguistics.

Part 3 Project Plan Nov 2013 Topology is the study of shapes and spaces. It is fundamental in the study of Mathematics and its influence can be seen across many other areas of study. It is often known as the "mathematics of continuity". Topology like many areas of Mathematics is axiomatic...

Bluetooth is a short range communication protocol. Bluetooth-enabled devices can be detected using road-side equipment, and each detected device reports a unique identifier. These unique identifiers can be used to track vehicles through road networks over time. The focus of this paper is on reconstructing the paths of vehicles through a road network using Bluetooth detection data. A method is proposed that uses Hidden Markov Models, which are a well-known tool for statistical pattern recognition. The proposed method is evaluated on a mixture of real and synthetic Bluetooth data with GPS ground truth, and it outperforms a simple deterministic strategy by a large margin (30%-50%) in this case.

Digital publishing unarguably has brought about many advantages for the dissemination of research findings. The distribution of research papers --- a format which has been used to present original data during the past 350 years --- has become faster, more affordable, longer lasting and content can be customised by the reader as publications can be assessed individually. Yet, these are incremental innovations --- a pdf remains a linear narrative, contextualised in a manner that demands human interpretation. This fundamental and largely unchanged workflow often leads to suboptimal presentation of data within publications or even omission of making data publicly available. In addition, the unique potentials of digital technologies in terms of enhancing, curating and commenting content are barely being tapped. We will discuss the impact of collaborative and dynamic authoring and publishing technologies and contemplate on what we think of as scholarly output of individual researchers. At the same time we will embark on our own collaborative authoring project and produce live session notes using writelatex.com --- everyone’s input is more than welcome!

Personal Rapid Transit (PRT) is an emerging urban transport mode. A PRT system operates much like a conventional hackney taxi system, except that the vehicles are driven by computer (no human driver) between stations in a dedicated network of guideways. The world's first two PRT systems began operating in 2010 and 2011. In both PRT and taxi systems, passengers request immediate service; they do not book ahead. Perfect information about future requests is therefore not available, but statistical information about future requests is available from historical data. If the system does not use this statistical information to position empty vehicles in anticipation of future requests, long passenger waiting times result, which makes the system less attractive to passengers, but using it gives rise to a difficult stochastic optimisation problem. This paper develops three lower bounds on achievable mean passenger waiting time, one based on queuing theory, one based on the static problem, in which it is assumed that perfect information is available, and one based on a Markov Decision Process model. An evaluation of these lower bounds, together with a practical heuristic developed previously, in simulation shows that these lower bounds can often be nearly attained, particularly when the fleet size is large. The results also show that low waiting times and high utilisation can be simultaneously obtained when the fleet size is large, which suggests important economies of scale.