
Expanding the Irreducible Element n 113
Consequently, the service density function is made up of two components,
φ(s) = φ*(s; ∆,λ) + χ(∆,λ)⋅δ(s – 1) (7.10)
and we will call χ the spike, so that when s = 1, the system is “in the spike.” Also, let
us call the event that s becomes 1 a strike, that is, the QoS “strikes the spike.”
e distribution function φ(s) is not a simple function that can be expressed
in closed form, but it can be evaluated by simulating system operation, stepping
through time unit by unit. At each step, element failures may or may not take
place, and the calculation accounts for up to two element failures per unit time. ...