Application of Artificial Immune System in Structural Health Monitoring

Table 1

A comparison between some terminologies used in both the BIS and the AIS.

Terminology	Definition in the BIS	Definition in the AIS for SHM
Antigen	A molecular pattern that can cause the reaction of the immune system, which is usually harmful to the human body.	A data structure that consists of some related information about a structural-health-condition.
Antibody	A portion of a receptor molecule that can bind with a specific molecular pattern.	A data structure that consists of some related information about a structural-health-condition. This structure is generated mathematically by the AIS.
Affinity	A measurement of the binding strength between an antigen and an antibody.	A criterion defined to scale the relationship between the feature vector of an antigen and the one of an antibody.
Memory cell	An immune cell that contains information about previously invading antigens. It stays in the immune system and will initiate a secondary-immune-response if it recognizes known antigens.	A member in a database of AIS, which stores the data structures of previous invading antigens. This database is used by the AIS to recognize unknown structural-health-conditions.
Immune response	The process taken by the immune system to neutralize invading antigens.	The recognition process performed by the AIS to determine unknown structural-health-conditions.