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Abstract

We consider the concept of statistical complexity to write the quasiperiodical damped systems applying the snapshot attractors. This allows us to understand the behaviour of these dynamical systems by the probability distribution of the time series making a difference between the regular, random and structural complexity on finite measurements. We interpreted the statistical complexity on snapshot attractor and determined it on the quasiperiodical forced pendulum.

Abstract

The control systems for the objects of industry, power generation, transport, etc. are extremely complicated; functional efficiency of these systems determines to a great extent the safe and non-polluting operation as well as convenience of service and repair of such objects. The authors consider the possibility to improve the efficiency of systems for damping oscillations in transport using a combination of electrical (generators of rotational and linear types) and hydraulic means. Better efficiency of functioning is achieved through automatic control over the operational conditions of such a system in order to make it adaptive to variations in the road profile and ambient temperature; besides, it is possible to produce additional electric energy.

Abstract

The problem of active vibration control of weakly damped mechanical structures is potentially unstable modes of vibrations due to the positive feedback for some vibration modes. The paper will discuss the change of positive feedback on the negative one using all-pass discrete-time filters. These filters can be arranged in a cascade to stabilize many potentially unstable modes. The piezoelectric actuator as a source of force is used to damp vibration.

Abstract

This paper discusses the concept of a hybrid damper made from a combination of two dissipative devices. A passive hysteretic device like steel Buckling Restrained Brace (BRB) can be combined with a magneto-rheological (MR) Fluid Damper in order to obtain a hybrid dissipative system. This system can work either as a semi-active system, if the control unit is available, or as a passive system, tuned for working according to performance based seismic engineering (PBSE) scale of reference parameters (i.e. interstory drift).

Abstract

The publication presents the results of research on the statistically significant impact of the number of layers on vibration damping properties of vibroacoustic mats. The research was carried out on the author’s research stand. The research was carried out on sandwich systems made of polyurethane foam. The impact force of the analyzed variables was determined on the basis of constructed multiple regression models, the so-called multifactor models and determination of the standardized value β. The research was carried out using the PQStat software. In the models being built, the significance level was p < 0.05.

Three statistically significant linear multivariate models for one-third frequencies were constructed:

• 0-20000 Hz – a model for the entire frequency spectrum analysed during the tests,

• 0-400 Hz – a model for frequencies generating construction vibrations that may affect the worker as general vibrations,

• 50-20000 Hz – a model for frequencies that generate construction vibrations that can cause auditory sensations (noise).

It was found: positive correlation of the number of layers in vibration damping systems with a third octave frequency of up to 400 Hz; negative correlation of the number of layers in vibration damping systems with a third octave frequency of 50 to 20000 Hz.

References [1] Caughey, T. K., O’Kelly, M. E. J.: Classical Normal Modes in Damped Linear Dynamic System. Transaction of the ASME. Journal of Applied Mechanics 32, 1965. pp:583-588. [2] Caughey, T. K.: Classical Normal Modes in Damped Linear Dynamic System. Transaction of the ASME. Journal of Applied Mechanics June. 1960. pp:269-271. [3] Fawzy, T. K.: A Theorem on the Free Vibration of Damped System. Transaction of the ASME. Journal of Applied Mechanics Marc. 1977. pp:132-134. [4] Sas, P., Ward, H., Lammens, S.: Modal Analysis Theory and Testing. Katholike

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[18] Tewari, A. “Modern Control Design with Matlab and Simulink”, John Willey & Sons, West Sussex, England, 2002 . ISBN 0-471-496790 [19] Balátě, J. “Automatické řízení”, BEN - technická literatura, Praha, Czech Republic, 2003 . ISBN 80-7300-0202 [20] Grosinger, P., Šolek, P. “Crane Control with Pole Placement Method and with PID Controller”, presented at ERIN, Častá, Slovakia, May, 2018 . [21] Tůma, J., Šuránek, P., Žiaran, S. “All-Pass Filters in the Systems of Active Vibration Control of Weakly-Damped Systems”, Strojnícky časopis – Journal of Mechanical

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