My neighbourhood: Studying perceptions of urban space and neighbourhood with moblogging

We describe a novel methodology that examines perceptions of urban space, and present a study using this methodology that explores people’s perceptions of their neighbourhood. Previous studies of spatial cues have involved a variety of tasks such as pointing and sketching to externalise participants’ internal spatial maps. Our methodology extends these approaches by introducing mobile technologies alongside traditional materials and tasks. Participants use mobile phones to carry out self-guided neighbourhood tours. We collected rich qualitative data from 15 participants during two workshops and a self-directed neighbourhood tour. Our study highlights the use of public and private landmarks, differences in spatial maps of rural versus urban dwellers, and individual variance in orientation strategies. These themes suggest guidelines for the design of technologies with personalised spatial profiles.     

Efficiently finding unusual shapes in large image databases

Among the visual features of multimedia content, shape is of particular interest because humans can often recognize objects solely on the basis of shape. Over the past three decades, there has been a great deal of research on shape analysis, focusing mostly on shape indexing, clustering, and classification. In this work, we introduce the new problem of finding shape discords, the most unusual shapes in a collection. We motivate the problem by considering the utility of shape discords in diverse domains including zoology, microscopy, anthropology, and medicine. While the brute force search algorithm has quadratic time complexity, we avoid this untenable lethargy by using locality-sensitive hashing to estimate similarity between shapes which enables us to reorder the search more efficiently and thus extract the maximum benefit from an admissible pruning strategy we introduce. An extensive experimental evaluation demonstrates that our approach is empirically linear in time. A primary version of this work appears in ICDM 2006.     

Understanding and measuring the urban pervasive infrastructure

The increasing popularity of mobile computing devices has allowed for new research and application areas. Specifically, urban areas exhibit an elevated concentration of such devices enabling potential ad-hoc co-operation and sharing of resources among citizens. Here, we argue that people, architecture and technology together provide the infrastructure for these applications and an understanding of this infrastructure is important for effective design and development. We focus on describing the metrics for describing this infrastructure and elaborate on a set of observation, analysis and simulation methods for capturing, deriving and utilising those metrics.

Can we do without GUIs? Gesture and speech interaction with a patient information system

We have developed a gesture input system that provides a common interaction technique across mobile, wearable and ubiquitous computing devices of diverse form factors. In this paper, we combine our gestural input technique with speech output and test whether or not the absence of a visual display impairs usability in this kind of multimodal interaction. This is of particular relevance to mobile, wearable and ubiquitous systems where visual displays may be restricted or unavailable. We conducted the evaluation using a prototype for a system combining gesture input and speech output to provide information to patients in a hospital Accident and Emergency Department. A group of participants was instructed to access various services using gestural inputs. The services were delivered by automated speech output. Throughout their tasks, these participants could see a visual display on which a GUI presented the available services and their corresponding gestures. Another group of participants performed the same tasks but without this visual display. It was predicted that the participants without the visual display would make more incorrect gestures and take longer to perform correct gestures than the participants with the visual display. We found no significant difference in the number of incorrect gestures made. We also found that participants with the visual display took longer than participants without it. It was suggested that for a small set of semantically distinct services with memorable and distinct gestures, the absence of a GUI visual display does not impair the usability of a system with gesture input and speech output.     

Disk aware discord discovery: finding unusual time series in terabyte sized datasets

The problem of finding unusual time series has recently attracted much attention, and several promising methods are now in the literature. However, virtually all proposed methods assume that the data reside in main memory. For many real-world problems this is not be the case. For example, in astronomy, multi-terabyte time series datasets are the norm. Most current algorithms faced with data which cannot fit in main memory resort to multiple scans of the disk /tape and are thus intractable. In this work we show how one particular definition of unusual time series, the time series discord, can be discovered with a disk aware algorithm. The proposed algorithm is exact and requires only two linear scans of the disk with a tiny buffer of main memory. Furthermore, it is very simple to implement. We use the algorithm to provide further evidence of the effectiveness of the discord definition in areas as diverse as astronomy, web query mining, video surveillance, etc., and show the efficiency of our method on datasets which are many orders of magnitude larger than anything else attempted in the literature.

Predicting gate oxide reliability from statistical process control nodes in integrated circuit manufacturing — a case study

This paper investigates the possibility of transferring the concepts developed for SPC into reliability control of integrated circuits. It employs Taguchi methods and response surface methodology to predict the reliability of a 20 nm gate oxide process using selected critical in line parameters. A Taguchi L₁₂ design was used as a screening experiment to determine the most critical factors which effect the reliability of the gate oxide dielectric. From this three parameters were selected for use in a central composite face centred array to model their effect on the oxide dielectric reliability using response surface methodology. The reliability of the oxide dielectric was measured using time-dependent dielectric breakdown testing, and the calculations were based on the time to 0⋅1 per cent cumulative failure, as this is the time on which industry standard reliability predictions are based. The results show that using a test chip the intrinsic reliability of the oxide can be modelled using the values obtained from critical nodes within a wafer fabrication facility and that this is a viable approach to predict oxide reliability. © 1997 John Wiley & Sons, Ltd.