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Experimental research chaos and his visualization
Kratochvíl, Ctirad ; Koláčný, J. ; Houfek, Lubomír ; Houfek, Martin ; Švéda, P.
Theory chaos like of science discipline unreel approximately from halves sixtieth years last century. Most washing is but till this time devoted theoretic aspects hereof prodigy and their investigation pursues as a rule on modelling systems with small number degree of freedom - concerning technical application. In his benefit put to record simulator studies chaotic phenomenon, which were gained with utilization, chaos modulus on mock - ups nonlinear dynamic systems. K visualization achieved results then use memory oscilloscope.
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Analýza stability rovnovážné polohy a odezvy rotorů uložených v kapalinných ložiskách a majících kotouč ponořený v nesmáčivé kapalině
Zapoměl, Jaroslav
In a number of technological applications the rotors supported by fluid film bearings have the discs submerged in various liquids. Lateral vibration of such rotors is significantly influenced by their interaction with the medium in the surrounding space. A computer modelling method represents an important tool for investigation of their behaviour. The approach to analysis of vibration of small amplitudes of structures submerged in liquids is based on modification of the Navier Stokes equations leading to the Laplace one. The fluid film bearings are usually implemented into the computational models by means of nonlinear force couplings. The pressure distribution in the full oil film is governed by a Reynolds equation and in cavitated areas the pressure remains constant. The motion of a rotor supported by short hydrodynamic bearings, excited by imbalance forces, and having a disc submerged in inwettable liquid was investigated.
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Postup pro zkoumání stability rovnovážné polohy a nelineární odezvy rotoru uloženého v kapalinných ložiskách a majícím kotouč ponořený v neviskózní, nesmáčivé kapalině
Zapoměl, Jaroslav
Lateral vibration of rotors is significantly influenced by their supports and by their interaction with the medium in the ambient space. If the disc of the rotor is submerged in a liquid and if it vibrates, the pressure field is induced and the liquid acts by a force on the wall of the disc. It is assumed that the disc performs oscillations only with small amplitudes and it enables to describe the produced pressure field by a Laplace's equation and by the relation for the boundary conditions. The liquid is inwettable and it means that it does not lean to the disc surface and therefore no tangential forces acting on the disc are produced. The resulting force is obtained by integration of the pressure distribution around the circumference and along the height of the submerged part of the disc. Its components are proportional to the disc accelerations and it implies that the negatively taken coefficients of proportionality can be considered as additional masses.
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Chaotické kmitání rázové soustavy s měkkým zdrojem energie
Půst, Ladislav
Influence of weak source of exciting on the vibrations of mechanical system with elastic stop is investigated. Level of hard energy source changes damping of oscillating system and influences origine of quasi periodic and chaotic oscillations. Weak source of excitation increases of motion and suppresses dangerous chaotic motions.
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Systém s rázy buzený zdrojem omezeného výkonu
Půst, Ladislav
Electromechanical system with one degree of freedom in mechanical oscillating part and other degrees in rotation a electrical subsystems is investigated by means of numerical solution of derived equations in dimensionless form. The most important nonlinearities are impacts of the main body on the stiff but deformable stop. Other nonlinear effects are introduced into system by the force transformation from unbalance exciter with limited power into the oscillating subsystem and also by nonlinear magnetic flux in the driving electromotor. Presented numerical simulation was focused on the study of the influence of exciting unbalance level on the time histories of caused oscillations and of phase trajectories. The various responses were shown and discussed in examples.
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Komplexní problémy řešení pohonových soustav
Kratochvíl, Ctirad ; Heriban, P. ; Houfek, Lubomír ; Houfek, Martin
Today the drive system is considered mainly as interactive system containing a range of subsystems with different physical nature: mechanical – the basic ones, electrical and hydraulic,pneumatic and also electronic – control ones. Models of those complex systems can then be characterized as so called purpose build and partially structured. The models of those partial subsystems have their typical signs and properties, which can often essentially influence the dynamic properties and global system models behaviour. The aim is to keep so called functional model purpose – in comparison with the real system, which does not necessarily mean that the model must contain all the function and signs. By contrast we suppose that those functions have their carrier, which in limit case can be represented by black box. The control of such systems then more and more often require use of intelligent control algorithms, based for example on genetic algorithms and artificial neural networks.
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Vazba kmitajícího systému a zdroje energie
Půst, Ladislav
Majority of publications on mechanical vibrations are based on the assumption that the external excitation is produced by an ideal source of power with prescribed frequency. But in reality, the excitation sources are non-ideal with limited power, limited inertia and their frequency fluctuates according the instantaneous state of oscillating system. The paper presents on overview of systems and results gained during the several dozens of years on this interaction problem. The most characteristic properties of systems excited by source of limited power and limited inertia are variation of revolution, distortion of harmonic motion, instability and non-uniform passage through resonance zone.
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