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Verifikation of machine component strain
Novák, Tomáš ; Dočkal, Aleš (referee) ; Drápela, Miloslav (advisor)
The thesis deals with a comparative analysis of strain of parts using finite element method (FEM) and measurement of the optical system Pontos. Part was used the reflector of Volkswagen Polo. The subject of comparing were the values of deviations optical shield of reflector which excitation random vibration described power spectral density. The thesis presented describes of experimental measurements to obtain the boundary conditions using optical systems. FEM analysis was performed using software ANSYS Workbench 12.
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Fir Filter Resonance Compensation For Random Vibration Generation
Kunz, Jan
This paper deals with a random vibration generation on vibration shakers using a FIR filter. Every shaker has its resonances and anti-resonances which causes troubles in random vibration generation, for instance in presented shaker the difference between maximum and minimum in frequency characteristic is nearly 50 dB. Therefore, we decided to create a FIR filter with inverse characteristic with respect to the shaker to minimize those differences. To design such a filter a freqeuncy characteristic of the shaker has to be measured, then the characteristic is simplified using Ramer–Douglas–Peucker algorithm. Finally, the characteristic is inverted and FIR filter is designed using Remez algorithm. Using this FIR filter the difference in frequency characteristic drops from 50 dB to less 2 dB.
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Asymmetry of the response probability density of a system with parametric random noises
Náprstek, Jiří ; Fischer, Cyril
Recording of time variable processes is accompanied by various internal disturbing effects as a rule. They influence parameters of the measuring facility, transducer-device transmission, etc. These parasitic processes are usually of the random character and, consequently, they exercise as parametric noises. Moreover, the input signal mostly consists of a useful signal which can be taken as composed from deterministic and random additive part. Various combinations of these noises are the origin of random and also systematic measuring errors which can have under certain circumstances a cumulative character, deteriorate the output signal quality and can lead finally to the stochastic stability loss. These effects can be theoretically described using differential systems with stochastic coefficients and stochastic right hand side considering all input and output processes to be of the Markov type.
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Verifikation of machine component strain
Novák, Tomáš ; Dočkal, Aleš (referee) ; Drápela, Miloslav (advisor)
The thesis deals with a comparative analysis of strain of parts using finite element method (FEM) and measurement of the optical system Pontos. Part was used the reflector of Volkswagen Polo. The subject of comparing were the values of deviations optical shield of reflector which excitation random vibration described power spectral density. The thesis presented describes of experimental measurements to obtain the boundary conditions using optical systems. FEM analysis was performed using software ANSYS Workbench 12.
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Stochastic resonance in a simple duffing equation
Náprstek, Jiří
The response of a dynamic nonlinear single degree of freedom system with cubic characteristic to a combination of additive random Gaussian white noise and external deterministic periodic force is studied. It is coming to light that under certain circumstances the jumping between wells of the bistable elastic potential can occur leading to interwell hopping. The frequency of this hopping can be for certain combination of input parameters nearly constant and corresponding to external periodic force frequency. This state leads to high ratio of periodic component amplitude and intensity of the random component of the response process. In such a case the system can be used as a harmonic selective resonator detecting the useful weak harmonic signal in the high noisy background.
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