Abstract
This paper will focus on mathematical models to reduce the possibility of gas distribution net threat attacks, in order to avoid environmental damage caused by the siphoning off gas. These models are based on Markov models and theory of graphs. The article also shows some forms of attacks on gas distribution net. Environmental damage includes thermal influence caused by gas inflammation, terrain disturbance, biochemical processes. Among siphoning off gas indicators are: Interference in gas meter; Documentation noncompliance; Gas distribution off-the-meter; Power counter range discrepancy; Gas meter failure; Expired recalibration interval; Gas siphoning; Other discrepancies.