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    Volume 1 Number 6 November 2015

    Accurate Solvent – Solvent Densities, Dielectric Constants and Volumes of Mixed N, N-Dimethylformamide (DMF) – Water at 298.15K

    Pages: 108-112
    Authors: Esam A. Gomaa
    In this paper the densities and dielectric constants for mixed (DMF) – water solvents at 298.15K were accurately measured using densimeter DMA-58 and decameter DK-300 respectively. Different volumes (molar volume VM, Van der Waals volume VW, electrostriction volume Ve and crystal volume VC) for mixed (DMF) – H2O solvents were evaluated from density measurements.

    Disturbance Rejection with a Highly Oscillating Second-Order Process, Part II: PD-PI Controller

    Pages: 102-107
    Authors: Galal Ali Hassaan
    This research paper aims at investigating disturbance rejection associated with a highly oscillating second-order process. The PD-PI controller having three parameters are tuned to provide efficient rejection of a step input disturbance input. Controller tuning based on using MATLAB control and optimization toolboxes. Using the suggested tuning technique, it is possible to reduce the maximum time response of the closed loop control system to as low as 0.0095 and obtain time response to the disturbance input having zero settling time. The effect of the proportional gain of the PD-PI controller on the control system dynamics is investigated for a gain ≤ 100. The performance of the control system during disturbance rejection using the PD-PI controller is compared with that using a second-order compensator. The PD-PI controller is superior in dealing with the disturbance rejection associated with the highly oscillating second-order process.