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Quantitative Analysis of Phase Trajectory as the Information about Technical Condition of the Object

100%
Majkut L.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1A
A-168-A-173
EN
The paper aims to describe the potential use of phase trajectory for damage detection of structural components. The attractor of the examined trajectory is a static equilibrium point of the element being diagnosed. Two different damage indices are proposed to evaluate the severity of damage in the diagnosed component. The first one refers to distance between a point on a trajectory and the point which is the attractor of the trajectory. The other one relates to linearity of the Poincaré map. Effectiveness of the proposed method was evaluated on: a simple model with two degrees of freedom, data from the finite element method model of a cantilever beam with a crack, and experimental data for a cracked plate. With the proposed method, the damage can be quickly and effectively detected. By comparing the current trajectory with that from the previous diagnostic test, it is possible to establish if the nature of crack is either propagating or stationary.
2
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Acoustic Eigenanalysis with Radial Basis Functions

63%
Majkut L., Olszewski R.
Acta Physica Polonica A
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2014
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vol. 125
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issue 4A
A-77-A-83
EN
The paper concerns the eigenanalysis of acoustic cavities with the use of radial basis functions (RBF). The Kansa collocation method was used for determination of the natural frequencies and eigenvectors of 1D, 2D and 3D acoustic fields. Due to validation analysis of the proposed method, in simple examples like 1D, 2D rectangle and 3D rectangular parallelepiped all calculated eigenferquency and eigenvectors were compared with exact (analytical) results. All results indicate that using of multiquadric radial basis functions provide a results with very high accuracy in comparison to analytical results. In the paper a new method for determining the shape parameter of the multiquadric radial basis functions is described.
3
Content available remote

Acoustic Field Distortions Caused by Helium-Filled Balloons

51%
Majkut L., Olszewski R., Pluta M.
Acta Physica Polonica A
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2014
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vol. 125
|
issue 4A
A-84-A-87
EN
In this paper, an automated measurement system was proposed that uses a probe hung below a remotely controlled balloon to measure parameters of the acoustic field in the whole volume of a room. The study was conducted to estimate distortions that such system may cause in the acoustic field at the measurement point. The most significant source of the distortions will be the buoyancy element - one large balloon or a number of smaller ones. This paper considers different spatial configurations of spherical balloons with regards to alterations they cause in the acoustic pressure levels measured below them. Interior of a room without and with a group of spherical balloons was modeled using the boundary element method. Using a larger number of smaller spheres instead of a single large one did not significantly reduce the related distortions. However, using two spheres slightly decreased distortions when the distance between the balloons and the recording point was relatively small.
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