Przeglądaj wg Autor "Wasilewski, Grzegorz"
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Pozycja Experimental and numerical investigations of a pendulum driven by a low-powered DC motor.(Politechnika Łódzka. Wydział Mechaniczny. Katedra Automatyki, Biomechaniki i Mechatroniki., 2015) Wasilewski, Grzegorz; Kudra, Grzegorz; Awrejcewicz, Jan; Kaźmierczak, Maciej; Tyborowski, Mateusz; Kaźmierczak, MarekThe work is a continuation of numerical and experimental investigations of a system consisting of a single pendulum with the joint horizontally driven by the use of a crank-slider mechanism and DC motor. The power supplied to the DC motor is relatively small when compared with our earlier investigations, which results in clear return influence of the pendulum dynamics on the DC motor angular velocity and much more rich bifurcation dynamics of the whole system, including regions of chaotic behaviour. In the experiments, the motor is supplied by the use of different but constant in time voltages. A series of experiments allow for accurate estimation of the model parameters and, in the further step, for prediction of the real system behaviour, also for other functions representing input voltage, including the time-varying ones.Pozycja Nonlinear Dynamics of Forced Oscillator Subjected to a Magnetic Interaction(Wydawnictwo Politechniki Łódzkiej, 2021) Skurativskyi, Sergii; Kudra, Grzegorz; Witkowski, Krzysztof; Wasilewski, Grzegorz; Awrejcewicz, JanIt is considered the system composed of a cart moving along a linear rolling bearing with harmonic excitation produced by a stepper motor with an unbalanced disk. The magnetic field is generated by a pair of non-point neodymium magnets, one of which is mounted on the cart, whereas another one is fixed on the guide out of the axis of oscillations. The mathematical model for the cart dynamics is derived where the scaled point dipoles approximation of magnetic interaction is used. The numerical and bifurcation analysis of the model presented is carried out and compared to the experimental results.Pozycja Numerical investigation of deformations of planar flexoelectric nematic layers containing ions(Wydawnictwo Politechniki Łódzkiej, 2008) Buczkowska, Mariola; Wasilewski, GrzegorzDeformations of planar nematic layers of conducting nematic liquid crystal possessing flexoelectric properties and subjected to external d.c. voltage were studied numerically. Various kinds of electrodes, from strongly blocking to well conducting, were assumed. The calculations were performed for nematic material characterized by positive dielectric anisotropy and by positive sum of flexoelectric coefficients. The threshold voltages for deformations were computed for various ion concentrations and for several rates of electrode processes. The enhancement as well as reduction of the threshold were observed. Well defined dependence of layer behaviour on the kind of electrodes and on the ion concentration was found. These effects are due to interactions between flexoelectric polarization and strong electric field of high gradient.