To identify the corresponding intrusion events and mitigate false alerts of intrusion detection by represent- ing the relationships between intrusion events is an importantand difficultwork in the field.

Aimed at the problem of frequent false alarms of combustible gas detectors installed in the West to East Gas Transmission Pipeline, the gathered basic data are analyzed to make clear the causes of fa.

CIDF model and a few problems existed in IDS are reseanhed, for example, IDS can not nicely hold up DoS, the real-time performance of IDS is not good and the false alarm rate is rather high, etc.

The technology measure of rejecting synchronous frequency interference and the false alarm aroused by noise are also described.

This paper analyses the working of fire detectors and finds out the causes of false alarming.

In reality,too many alarms and the high false positive rate have already restricted the development of NIDSs.

Analyzes the occurrence of subjective and objective false alerts on board in recent years, in order to prevent similar false alerts.

The relationship among false alarm rate, false dismissal rate and threshold is derived from the viewpoint of theory and practice.

The experimental results show that the model has high detection rate,and which can deduce the false alarm rate effectively.