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A dynamic system is stable if the displacements under small perturbation are bounded; it is unstable if the displacements of the system are amplified
A dynamic system is stable if the displacements under small perturbation are bounded; it is unstable if the displacements of the system are amplified with time. The critical pressure is defined as the minimum pressure at which the displacement is amplified with time. For each given pulse pressure, the mean pressure is gradually increased until the displacement becomes unstable. In this project, solve Eq. (1) numerically to determine the critical pressures (pairs of mean pressure po and pulse pressure p.) that will cause the artery to lose stability. The simulation step can be taken as below: First, set the pulse pressure p. =0, increase the mean pressure po from 0. For each po, solve and check if the displacement (t) is amplified with time; if not, continue increasing po until reach a value that will cause the displacement to amplify with time (loss of stability). To do so, check the displacement for 2000 time steps (may plot the displacement vs. time), may assume the system loses stability if the displacement > 0.05. This pressure po is the critical mean pressure corresponding to the pulse pressure pa=0. Next, we can set the mean pressure p, 0, calculate the pulse pressure p, that is increasing from 0 till a value that will lead to unstable, which is the critical pulse pressure p, corresponding to mean pressure p=0. Continue the above step for non-zero values of pulse pressure p.. we can find the corresponding critical mean pressures po. Set the increment of the pulse pressure p, and mean pressure po to 2 mmHg (-266.6 Pa). Use mmHg in your plot but Pa in the calculation (since all other parameter are in standard SI units). Submit your Matlab programs and the simulation results using following parameter values. Show results by plotting the critical values of pe vs. p, as y- and x-axis. Parameter values are given as below (all units are SI units) axial force N-162.5 x 10' N, artery lumen radius r, -2.7546e-3 m; outer radius re-3.28298e-3 m; artery lumen area Amr; cross sectional area A=(-) artery original length L-22 e-3 m, stretch ratio=1.5, and the length /=*L; bending rigidity EI = 1.378e-6; density of the arterial wall p. 1.05e3, blood density py 1.06e3 kg/m is calculated by o2nf, where f is the frequency of the pulsatile pressure, for the simulation, use f=1.5 Hz and 3.5 Hz respectively. Initial conditions are f(0)=0.01, df(0)/dt=0 100 80 60 40 f=1.5 Hz of=3.5 Hz
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