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Go to Editorial ManagerDistillation columns are among the most critical units in chemical processes, especially in oil refineries. This research aims to develop a mathematical model for a nonlinear multicomponent naphtha distillation column using real experimental data. The naphtha distillation column used in this research consists of a column with a diameter of 2.2 m and a height of 16.6 m, containing 20 trays of type (valve tray). The process currently operates in Al-Dora Refinery as part of the Midland Refinery Company in eastern Baghdad, Iraq. Four manipulated variables (reflux flow rate, reboiler heat duty, light compound fraction in the feed, and feed flow rate) were tested for their impact on four control variables (light compound fraction in the top product, light compound fraction in the bottom product, amount of top product, and amount of bottom product). A 4x4 transfer function is produced by representing the obtained dynamic models for the variables under study using various second-order models (having different damping factors) with dead time.
The modern development in prosthetics field demand the evaluation of the dynamical behavior and automatic control .The key process in the design and implement of these devices is the determination of the model parameters inherited with the transfer function .In such complicated structures it is so difficult to evaluate transfer function analytically ,however experimental approaches can serve as a simple and effective tool for estimating transfer function and model parameters .In this regard computer software such as Matlab is used .System Identification SID refers to the method for estimating the system transfer function from experimental tests by using computer .In the present paper; SID method is employed for analyzing below-knee prosthesis leg .In order to simulate with the practical requirement for design and evaluation ,two phases of human gait are considered ,namely; swing phase and single support of stance phase .The validity of this method is firstly checked by applying it on clamped-clamped beam model where the required parameters are evaluated and compared theoretically (via modal analysis) and experimentally (via System identification) .It is found that ; the error in estimating the transfer function parameter of beam is not exceeded 6% . Then the transfer function of the prosthesis are estimated for two phases of gait cycle .It is found that; the estimated transfer function of the prosthesis leg is highly affected by the phase type of gait cycle , where ;the natural frequency highly increases, the static gain decrease for support phase as compared with the swing phase ,however the damping ratio does not affected .