Nonlinear Systems Theory,Hu Jiangping,School of Automation Engineering,University of Electronic Science and Technology of China,E-mail: hjp_,Topic 5 Passivity,5.1. Memoryless functions,5.2. State model,5.3. Positive real transfer function,5.4. L2 and Lyapunov stability,5.5. Feedback systems: passivity theorems,