Mechanics and Control
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ISSN 2083-6759
e-ISSN: 2300-7079
Issue Date
2010
Volume
Vol. 29
Number
No. 4
Description
Journal Volume
Mechanics and Control
Vol. 29 (2010)
Projects
Pages
Articles
The influence of numerical errors on determining the distribution of values of stochastic impulses forcing an oscillator
(2010) Jabłoński, Marian; Ozga, Agnieszka
The motion of an oscillator excited by a Poisson process is a stochastic process X(t). Knowing the trajectory of the motion we can find all the stochastic moments of X(t) for large t. This, in turn, allows us to find stochastic distribution of the forces exciting an oscillator. In this paper we evaluate the impact of errors in the computations of the moments on computed distribution of the forces exciting an oscillator.
Analysis of the mining torque signal with Continuous Wavelet Transform
(2010) Jonak, Józef; Jedliński, Łukasz; Gajewski, Jakub
This paper presents an analysis of the excavation torgue signal with the use of a Continuous Wavelet Transform. The article also presents results of preliminary research on utilising neural networks to identify excavating cutting tools type used in multi-tool excavating heads of mechanical coal miners. Selected wavelet coefficients were used as data to teach artificial neural network. The research is necessary to identify rock excavating process with a given head, and design adaptation system for control of mining process with such a head. The results of numerical analyses conducted with the use of Neural Networks are presented.
Measurements of parameters of sound reflecting screens
(2010) Kamisiński, Tadeusz; Polaczek, Agata; Rubacha, Jarosław
Sound reflecting panels are commonly used in concert and conference halls in order to transmit reflected sound to the audience and improve hearing conditions among musicians. The main problem is to design these elements properly. In this paper, the frequency limits of a useful sound transmission range and the efficiency of reflecting structures are theoretically estimated and experimentally verified.
In situ studies of sound insulation index of noise barriers
(2010) Piechowicz, Janusz
Outdoor noise barrier is roadside noise reducing device, the primary task of which is the protection of a pre-determined sound protection area against road traffic noise. The examinations of acoustic properties of the ele-ments used for construction of noise barriers are usually carried out in laboratory conditions according to the PN-EN 1793-1,2 standard. These examination procedures cannot be applied to existing installations. Therefore problems that are usually neglected are the problems related to the acoustic properties that essentially depend on a series of factors unrelated to the building elements themselves, namely: barrier dimensions, quality of workman-ship, barrier location and the type and topography of the ground foundation. In the European Research Project 'Adrienne' a methodology has been elaborated for in-situ determination of acoustic parameters of noise barriers. The examination, in which analysis of the system's impulse response after MLS signal actuation and a proper numerical algorithm are applied, leads to determination of airborne sound insulation of the existing constructions as well as the single number sound reflection factors and differences of diffraction properties at the top-edge elements of the barriers. The present paper describes the possibilities of determination of the intrinsic characteristics of airborne sound insulation index for the road traffic noise reducing devices in free field conditions and the determination of single number rating of airborne sound insulation to indicate the performance of the noise barrier.
Numerical tests of the influence of the orientation of stratification on the process of cutting of rocks
(2010) Podgórski, Jerzy; Jonak, Józef
The paper presents results of the numerical simulation of the crack propagation occurring in the course of chip element formation in case of cutting stratified rock material. As a result of the simulation, it was found that a characteristic, rapid increase of the loosening force of the chip element occurs when stratification is directed in relation to the cutting direction at an angle of ca. 160°.