Wyniki wyszukiwania - Biblioteka Nauki

1

Acoustic pressure of circular plate vibrating in a finite baffle with fluid loading

100%

Leniowska L.

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tom Vol. 1

311--316

EN

In this paper the problem of calculating the acoustic pressure around a thin circular plate is analysed. It was assumed that the plate was clamped at the circumference of the planar finite baffle and radiated into a lossless homogeneous medium. A model of the plate included internal dissipation in the plate's material and the influence of the acoustic wave radiated by the plate on its vibrations. The vibrations of the plate were forced by time-harmonic external pressure. The acoustic pressure was calculated on the basis of the known distribution of vibration velocity in a series of eigenfunctions, using properties of the oblate spheroidal coordinates. The result was obtained as a single series of spheroidal function products. The number of terms ensuring a required accuracy could be determined numerically.

2

Active Vibration Control of the Circular Plate with Simply-Supported Boundary Condition

100%

Leniowska L.

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2003

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tom Vol. 24

109-124

EN

This paper presents the problem of the active vibration control of a simply-supported circular plate. The plate is excited by an uniform force over the bottom surface generated by a lodspeaker. The axially-symmtrical vibrations of the plate are measured by the application of the four accelometers located along the plate radius. The mathematical model of the plate was obtained by using analytical methods, as well as, on a base of regisrtation of a system response on a fixed excitation (a parametric system identification procedure has been employed). Firstly, a modal model for the vibration of the considered structure is presented and the state realisation of the model is given. Secondly. the OE (Output Error) identification method is used to derive the reduced linear model in the form of a transfer function of the second order. The obtained model is used to develop the linear feedback control algorithm for the cancellation of vibration by using the point force provided by a shaker (SIMO system). Finally, the laboratory results obtained for the considered plate are presented. The results show that in the chosen low-frequency limit the designed structure of a closed-loop system provides a substantial vibration suppression.

3

Effect of plate vibration control by the use of piezoelectric actuators on its sound radiation attenuation

100%

Leniowska L.

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tom Vol. 22

215--221

4

Influence of phase correction on the acoustic impedance of circular planar sources

63%

Kos P. , Leniowska L.

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tom Vol. 32, No. 4

895--901

EN

In this work, the influence of velocity distribution phase correction on the acoustic impedance of a circular source located in an infinite baffle is analyzed. It has been observed that by turning back a velocity distribution phase by modifying the radiating surface shape in a special way, obtaining a more coherent acoustic radiation is possible. This problem has been analyzed during earlier investigations, with attention focused on the directivity of some acoustic sources [1]. The aim of this paper is to calculate the acoustic impedance which allows the examination of such a "phase correction" effect on the acoustic radiation of the considered sound sources. The result was achieved by numerical calculation with the use of Hankel representation of the acoustic impedance.

5

Mathematical model of a multi-link surgical manipulator joint with an antiseptic coating

63%

Leniowski R. , Leniowska L.

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tom Vol. 5, No. 3

21-26

EN

We present a synthesis of the mathematical model of a joint of a new generation multi-link surgical micromanipulator. A design of such a device involves finding solutions for several difficult problems which do not appear in classical 'large' robots.Aprototype in development has six links, and it is driven by brushless servomotors with planetary and worm gears, for which the total transmission ratio is above 10000:1. Most importantly, whole construction is covered by an antiseptic coating which substantially changes manipulator's dynamics. Because of the complicated form of the drive model with three-stage planetary gearings and coating interactions, control of such system is significantly different from control of a typical industrial robot. This paper presents a synthesis of the model of the joint, which can be used to design the control system. In this work the derived model is used to examine joint's properties and characteristics. Results are presented graphically and discussed.

6

Pomiary parametrów akustycznych małej komory bezechowej przeznaczonej do badania pola akustycznego płyt

63%

Zamorski T. , Leniowska L.

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tom z. 22 [192]

273-280

PL

Komora bezechowa to specjalistyczne pomieszczenie umożliwiające prowadzenie badań parametrów akustycznych w warunkach tzw. pola swobodnego. Celem pracy jest udzielenie odpowiedzi na pytanie, czy znajdująca się w Instytucie Fizyki Uniwersytetu Rzeszowskiego komora bezechowa nadaje się do pomiaru pola akustycznego drgających płyt. Zbadano rozkład pola akustycznego w komorze, zmierzono poziom ciśnienia akustycznego tła komory oraz określono jej częstotliwość graniczną, a otrzymane wartości porównano z obowiązującymi w tym zakresie normami.

EN

Anechoic chambers have to fulfill anechoic conditions to ensure that the measurements are taken in a perfect free field. The aim of this work is to investigate, if the anechoic room, located at Institute of Physics of Rzeszow University, can be used for research in the thin plate sound field. In order to answer this question the necessary acoustic parameters of the considered chamber have been measured and compared with the appropriate PN and ISO norms.

7

MFC Sensors and Actuators in Active Vibration Control of the Circular Plate

63%

Leniowska L. , Mazan D.

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2015

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tom Vol. 40, No. 2

257--265

EN

In this paper, the MFC sensor and actuators are applied to suppress circular plate vibrations. It is assumed that the system to be regulated is unknown. The mathematical model of the plate was obtained on the base of registration of a system response on a fixed excitation. For the estimation of the system’s behaviour the ARX identification method was used to derive the linear model in the form of a transfer function of the order nine. The obtained model is then used to develop the linear feedback control algorithm for the cancellation of vibration by using the MFC star-shaped actuator (SIMO system). The MFC elements location is dealt with in this study with the use of a laser scanning vibrometer. The control schemes presented have the ability to compute the control effort and to apply it to the actuator within one sampling period. This control scheme is then illustrated through some numerical examples with simulations modelling the designed controller. The paper also describes the experimental results of the designed control system. Finally, the results obtained for the considered plate show that in the chosen frequency limit the designed structure of a closed-loop system with MFC elements provides a substantial vibration suppression.

8

Application of Prediction Methods for Plate Vibration Suppression

63%

Leniowska L. , Leniowski R.

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tom Vol. 25

159-175

EN

In this paper, predictive feedback control is used to suppress circular plate vibrations. It is assumed that the system to be regulated is unknown. The plate is excited by a uniform force over the bottom surface generated by a loudspeaker. The axially-symmetrical vibrations of the plate are measured by the application of the strain sensors located along the plate radius and two centrally placed piezoceramic discs are used to cancel the plate vibrations. The control schemes presented in this work have the ability to predict the error sensor signals, to compute the control effort and to apply it to the actuator within one sampling period. For precise estimation of system behaviour the modified Runge-Kutta-3/8 neural network algorithm has been applied and tested. This control scheme is then illustrated through some numerical examples with simulations modeling the fuzzy predictive P-PI-PD controller and the improvement gained by incorporating a feed-forward path into the controller is demonstrated.

9

Active Vibration Control of a Circular Plate with Clamped Boundary Condidtion

63%

Leniowska L. , Leniowski R.

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2001

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tom Vol. 22

145-156

EN

The paper presents a system identification and simulation of active vibration control for a clamped circular plate as well as its expermental implementation. The model is based upon the geometry and properties of an experimental set-up consisting of a hard-walled cylinder ith a thin plate at one end. The primary excitation is provided by a low frequency loudpeaker installed centraly at the bottom of the cylinder. Vibrations of the plate are measured by the application of several pairs of strain sensors located along the plate radius. The derived control action is applied to the plate by one shaker attached pointwise in its middle (SIMO system). In particular, obtained numerical values and structure of dynamical model are used to develop the P-PID control algorithm for vibration cancellation. Finally, the laboratory results obtained for the considered plate are presented.