Selection of intrusion detection system threshold bounds for effective sensor fusion

The motivation behind the fusion of Intrusion Detection Systems was the realization that with the increasing traffic and increasing complexity of attacks, none of the present day stand-alone Intrusion Detection Systems can meet the high demand for a very high detection rate and an extremely low false positive rate. Multi-sensor fusion can be used to meet these requirements by a refinement of the combined response of different Intrusion Detection Systems. In this paper, we show the design technique of sensor fusion to best utilize the useful response from multiple sensors by an appropriate adjustment of the fusion threshold. The threshold is generally chosen according to the past experiences or by an expert system. In this paper, we show that the choice of the threshold bounds according to the Chebyshev inequality principle performs better. This approach also helps to solve the problem of scalability and has the advantage of failsafe capability. This paper theoretically models the fusion of Intrusion Detection Systems for the purpose of proving the improvement in performance, supplemented with the empirical evaluation. The combination of complementary sensors is shown to detect more attacks than the individual components. Since the individual sensors chosen detect sufficiently different attacks, their result can be merged for improved performance. The combination is done in different ways like (i) taking all the alarms from each system and avoiding duplications, (ii) taking alarms from each system by fixing threshold bounds, and (iii) rule-based fusion with a priori knowledge of the individual sensor performance. A number of evaluation metrics are used, and the results indicate that there is an overall enhancement in the performance of the combined detector using sensor fusion incorporating the threshold bounds and significantly better performance using simple rule-based fusion.

The Culture of Women's Housework : A Case Study of Bihar, India

This study examines gendered housework in India, particularly in Bihar. The perspective adopted in the study was in part derived from the data but also from sociological literature published both in Western countries and in India. The primary attention is therefore paid to modern and traditional aspects in housework. The aim is not to compare Indian practices to those of Western societies, but rather to use Western studies as a fruitful reference point. In that light, Indian housework practices appear to be traditional. Consequently, traditions are given a more significant role than is usually the case in studies on gendered housework, particularly in Western countries. The study approaches the topic mainly from the socio-cultural perspective; this provides the best means to understand the persistence of traditional habits in India. To get a wide enough picture of the division of labour, three methods were applied in the study: detailed time-use data, questionnaire and theme interviews. The data were collected in 1988 in two districts of Bihar, one rural and the other urban. The different data complement each other well but also bring to light contradictory findings: on a general level Biharian people express surprisingly modern views on gender equality but when talking in more detail (theme interviews) the interviewees told about how traditional housework practices still were in 1988. In the analysis of the data set four principal themes are discussed. Responsibility is the concept by which the study aims at understanding the logic of the argumentation on which the persistence of traditional housework practices is grounded. Contrary to the Western style, Biharian respondents appealed not to the principle of choice but to their responsibility to do what has to be done. The power of tradition, the early socialization of children to the traditional division of labour and the elusive nature of modernity are all discussed separately. In addition to the principle of responsibility, housework was also seen as an expression of affection. This was connected to housework in general but also to traditional practices. The purity principle was the third element that made Biharian interviewees favour housework in general, but as in the case of affection it too was interwoven with traditional practices. It seems to be so that if housework is in general preferred, this leads to preferring the traditional division of labour, too. The same came out when examining economic imperatives. However, the arguments concerning them proved to be rational. In analysing them it became clear that the significance of traditions is also much dependent on the economics: as far as the average income in India is very low, the prevalence of traditional practices in housework will continue. However, to make this work, cultural arguments are required: their role is to mediate more smoothly the iron rules of the economy. Key words: family, gendered housework, division of labour, responsibility, family togetherness, emotion, economy of housework, modernity, traditionality