Stefan Axelsson

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This paper presents a taxonomy of intrusion detection systems that is then used to survey and classify a number of research prototypes. The taxonomy consists of a classification first of the detection principle, and second of certain operational aspects of the intrusion detection system as such. The systems are also grouped according to the increasing(More)
Many different demands can be made of intrusion detection systems. An important requirement is that it be <italic>effective</italic> i.e. that it should detect a substantial percentage of intrusions into the supervised system, while still keeping the <italic>false alarm</italic> rate at an acceptable level. This paper aims to demonstrate that, for a(More)
Many different demands can be made of intrusion detection systems. An important requirement is that an intrusion detection system be <italic>effective</italic>; that is, it should detect a substantial percentage of intrusions into the supervised system, while still keeping the false alarm rate at an acceptable level. This article demonstrates that, for a(More)
The purpose of this study was to establish normative longitudinal cephalometric standards of size and to describe the morphology of the sella turcica in Norwegian males and females between 6 and 21 years of age using standardized lateral radiographic cephalograms. The subjects comprised 35 males and 37 females from the Oslo University Craniofacial Growth(More)
Williams syndrome (WS) is a rare congenital disorder with distinctive craniofacial features, cardiovascular abnormalities, mental retardation, and behaviour characteristics. The purpose of this study was to investigate the size and morphology of the sella turcica on profile cephalograms in a group of individuals with WS. The material consisted of(More)
Even though intrusion detection systems have been studied for a number of years several problems remain; chiefly low detection rates and high false alarm rates. Instead of building automated alarms that trigger when a computer security violation takes place, we propose to visualise the state of the computer system such that the operator himself can(More)