"Now you see it, now you don't!" Detecting Suspicious Pattern Absences in Continuous Time Series

Given its large applicational potential, time series anomaly detection has become a crucial data mining task. Its goal is to identify periods of a time series where there is a deviation from the expected behavior. Existing approaches focus on analyzing whether the currently observed behavior differs from previously seen, normal behavior. In contrast, this paper tackles the the task where the absence of a previously observed behavior is indicative of an anomaly. In other words, a pattern that is expected to recur in the time series is absent. In real-world use cases, absent patterns can be linked to serious problems. For instance, if a scheduled, regular maintenance operation of a machine does not take place, this can be harmful to the machine at a later time. In this paper, we introduce the task of detecting when a specific pattern is absent in a real-valued time series. We propose a novel technique called FZapPa that can address this task. Empirically, FZapPa outperforms existing anomaly techniques on a benchmark of real-world datasets.status: Published onlin

Decoding television news.

The thesis attempts to develop the field of audience research, by adapting recently developed theoretical approaches to an empirical study of the television audience. The thesis begins by examining two general theoretical areas that provide a framework for the research - semiology and theories of ideology. The work of Louis Aithusser is analysed in a movement towards a semiological theory of ideology. The thesis then examines work on the media that has developed out of this broad tradition - notably cultural studies, textual analysis, discourse analysis and the semiotics of film and T. V. Detailed attention is paid to the theory of encoding and decoding, and, in particular, the work of David Morley. The objective of this examination is to set up the encoding/decoding model within a semiological framework for use in practical research on the T. V. audience. The audience research itself is based upon an exhaustive analysis of fifty in-depth interviews with viewers following a screening of a pre-recorded News at Ten. The aim of the research was not to investigate the views of the fifty decoders, but to establish how and why readings of television programmes are constructed - the process of decoding. The research is presented in three stages. The readings of one item (about British Leyland) are scrutinised in order to establish an appropriate set of variables for understanding the decoding process. These variables are then used to systematically analyse the readings of another single item (about troubles in the West Bank). The points raised during this analysis are then developed in relation to readings of the whole programme. The research reveals a number of problems in the form and character of television news. The thesis therefore ends with a set of recommendations for overcoming these problems