PSI - Issue 22

10

Jerzy STANIK et al. / Procedia Structural Integrity 22 (2019) 334–344 "Author name" / Structural Integrity Procedia 00 (2019) 000 – 000

343

The IT transition from the state of “current disability” to the “functional usefulness” state can be described by the following mappings: ℱ : ⟶ (26) defined as follows: ℱ ( ) = , , ∈ , ≠ (27) where: - set of acceptable functional configurations before the occurrence of an emergency situation with a number ∈ , - the set of acceptable functional configurations after the occurrence of an emergency situation of number ∈ , The transiti on of IT from the “loss of current security level” to “acceptable security level” can be described by the following mappings: ℱ : ⟶ (28) defined as follows: ℱ ( ) = , , ∈ , ≠ (29) where: - set of acceptable security configurations before the occurrence of an emergency situation with a number ∈ , - a set of acceptable security configurations after the occurrence of an emergency situation with the number ∈ , Mapping is determined at the IT design stage to ensure that the desired features or properties of the IT usefulness are acquired during its operation. Assurance of the desired features or properties of IT usefulness has, in turn, a significant impact on maintaining the acceptable risk level of the IT. The transition of IT from the “lack of the acceptable risk level” to “the acceptable risk level has been achieved” can be described by the following mapping: ℛ ∶ × → ℜ + (30) where ℜ + - is a set of positive real numbers. Generation of the optimal or suboptimal functional configuration or security configuration, from among sets of permissible solutions is implemented on the basis of detailed reconfiguration functions Q , Q , which from the point of view of their essence are criterion functions. Formulating the task of multi-criteria optimization and suggesting a method of its solution is not the subject of this article. Summary Dynamic development of technology and changes in environmental and operational conditions of IT require that each engineering infrastructure should have the following characteristics: 1) constant readiness, i.e. maintaining the required level of current functional reliability and required level of current security as well as acceptable risk regardless of emergency situations,