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1
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Numerical Errors - Numerical Uncertainty - in the Identification and Estimation of Vibroacoustic Processes

100%
Batko W.
Acta Physica Polonica A
|
2010
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vol. 118
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issue 1
7-10
EN
Problems of numerical errors in the identification and estimation procedures of vibroacoustic phenomena are discussed in the hereby paper. The main attention is focussed on problems of errors generated by different algebras governing experimentally recognisable vibroacoustic effects and the algebra applied in the utilisation of procedures of their processing. Assessment of errors for elementary operations: adding, subtracting, multiplying and raising to a power - is derived. The problem of their presence in the current model solutions as well as in the implications for processes: cognitive, experimental (testing conditions) and their implementation is discussed. The postulate of the necessity of supplementing assessments of the measurement uncertainty in vibroacoustic examinations with assessments of the numerical uncertainty - are formulated. Various ways of looking for solving this problem are outlined. References to Author's and co-authors' own investigations - in this field - are also done.
2
Content available remote

Analytical Solution of the Problem of Vibration of Plates with Piezoelectric Actuators with Arbitrary Shape in Distribution Formulation

63%
Wiciak M.
Acta Physica Polonica A
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2012
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vol. 121
|
issue 1A
A-142-A-147
EN
This paper is concerned with mathematical aspects of modelling vibration of a plate with piezoelectric actuators. Particularly, a thin Kirchhoff-Love plate with arbitrary shaped actuators (e.g. triangles, parallelograms, discs) is considered. The moments that act upon a structure and are induced by piezoelectric actuators, are described by the generalized tensor product of a distribution and distribution-valued function. Finally, the formula for the solution of the Cauchy problem in the class of absolutely continuous tempered distribution-valued functions is derived.
3
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Numerical Analysis of the Effectiveness of Two-part Piezoactuators in Vibration Reduction of Plates

63%
Wiciak M., Trojanowski R.
Acta Physica Polonica A
|
2014
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vol. 125
|
issue 4A
A-183-A-189
EN
This paper is concerned with application of piezoelements with a step change of material properties occurring in the element's plane. Each part of an element may be controlled independently. Analytical models for different shape and location of the inner part of a two-part piezoactuator are developed. Finally, results of numerical simulations concerning effectiveness in vibration reduction of piezoactuators constructed this way are presented.
4
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Modeling of a Circular Plate with Piezoelectric Actuators of Arbitrary Shape

63%
Wiciak M., Trojanowski R.
Acta Physica Polonica A
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2013
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vol. 123
|
issue 6
1048-1053
EN
This paper is concerned with mathematical aspects and numerical modeling of vibration of a circular plate with piezoelectric actuators. Particularly, a thin Kirchhoff-Love plate with arbitrary shaped actuators (e.g. pie-shaped, trapezoid, disc, and rectangular) is considered. In the theoretical model, the moments that act upon a structure and are induced by piezoelectric actuators are described by the generalized tensor product of a distribution and distribution-valued function. Numerical computations utilize the FEM approach supported by Ansys software.
5
Content available remote

The Influence of Alarm Siren Structure Parameters on Output Sound Pressure Level

51%
Wiciak J., Dąbrowski K.
Acta Physica Polonica A
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2012
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vol. 121
|
issue 1A
A-136-A-141
EN
The paper is a discussion of the construction of an alarm siren based on the active piezoelectric element. The influence of various parameters on the loudness of the siren was investigated. Efforts to increase the efficiency of selected design were made. The simulations carried out based on an ANSYS. Individual dimensions of a piezoelectric transducer were selected as well as a collaborate diaphragm. The possibility of using different piezoelectric materials was also analyzed. All tasks and computer simulations were aimed at receiving a siren structure able to obtain the highest sound pressure level at selected frequency.
6
Content available remote

Analysis of Vibro-Acoustic Signals Generated during Operation of Micro Wind Turbines

51%
Wotzka D., Boczar T., Malec T., Pierzga R.
Acta Physica Polonica A
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2013
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vol. 124
|
issue 3
595-597
EN
Results of a measurement and analysis of vibro-acoustic signals generated by two low power vertical-axis wind turbines that are installed on the roof of the Electric Power Institute at Opole University of Technology are presented in the paper. The study considers a Darrieus and a Savonius type wind turbines of rated power 1 kW each. For registration of the vibrations of the turbine mast three uniaxial accelerometers and a measurement equipment from Brüel & Kjær were applied. The measurement setup is presented in the paper. A comparative analysis of the registered data in the time and time-frequency domains was performed. Results depict changes in the recorded signals in time and frequency under different meteorological conditions, i.e. for different wind speed values. Based on the achieved results significant differences in the mast vibrations of the two kinds of wind turbines were stated.
7
Content available remote

Nonlinear dynamics of mechanical system with external excitation

38%
Ryczek B.
Open Physics
|
2005
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vol. 3
|
issue 1
35-46
EN
This paper attends to the problem of vibration of a self-excited mechanical system with a relatively complicated, history dependent dry friction model. The experimentally identified friction model allows description of various cases of stationary and transient motion. The system is composed of a lumped mass that interacts with a belt by means of dry friction. The system is additionally subjected to an external harmonic excitation through elastic element. The main objective of the experimental research has been focused on the analysis of the system behaviour for various values of the excitation frequency. This paper includes also computer simulation of the vibration of the considered system and comparison between the results of experimental and theoretical analysis. The comparison enables the assumed friction model for steel-polyester pair to be verified. It was another goal of the investigations.
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