Figure 15

The energy \(E(t)\) of the wave system (1.16)-(1.20) with: a) \(\tau =1\) when \(k=1\), and for different functions \(a(x)\); b) \(\tau =1\), k is positive and when \(a(x)=1\); c) \(\tau =1\), k is negative and when \(a(x)=1\); d) \(\tau =1\), \(a(x)=1\) and \(a(x)=3\), and for numerous values of k; e) \(\tau =1\), \(a(x)=1\) and \(a(x)=3\), and for several values of k; f) different delays when \(a(x)=1\) and for \(k=-0.4\); g) various delays when \(a(x)=1\) and for \(k=0.4\); h) different delays when \(a(x)=1\) and for \(k=1\)