$($a$)$ Draw a Bond graph model for a hydraulic piston$-$cylinder system. Account for inertia of the piston, leakage, and, friction between piston and cylinder lining. Indicate effort and flow on every bond of your model. Explain the parameters used with each element in the model. Derive the system equations from the bond graph model. $($b$)$ Prepare Bond graph models for a positive displacement fluid pump and motor. Indicate effort and flow on every bond. Explain each model briefly.