“…We show that if functions ω 1 and ω 2 are C 2 [0, 1] and not identical, while Ω ω i (ξ) dξ = 0, i = 1, 2, (without loss of generality, we assume that Ω ω i (ξ) dξ = 1), then the function u(t) is identifiable from the measurements z 1 (t), z 2 (t), t ≥ 0 defined by (6). We define,…”