Wszystkie pola: Schmidt, W. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Measuring the impedance of ultrasonic transducers
Autorzy:: Lis, W.
Schmidt, J.
Powiązania:: https://bibliotekanauki.pl/articles/332169.pdf
Data publikacji:: 2004
Wydawca:: Polskie Towarzystwo Akustyczne
Opis:: For ultrasonic transducers whose impedance is usually highly variable with frequency, impedance measurement is quite difficult. Cheap and easy devices which are currently available are not suitable for this purpose. Expensive scientific devices are known to be used; usually, they are designed for such measurements in a wide frequency band, from acoustic to microwave range. Simpler and cheaper devices with a narrower band are not commercially available. For hydroacoustic applications, the frequency range may be reduced to 1MHz or even 250 kHz in most cases. This article discusses the possibilities of building a simple and cheap automated system of measuring electric impedance of ultrasonic transducers used in hydroacoustics. The presented results are based on the concept of using a digital oscilloscope as the basic tool for measuring the impedance magnitude and phase. The results have been verified in the original measurement system.
Źródło:: Hydroacoustics; 2004, 7; 143-148
1642-1817
Pojawia się w:: Hydroacoustics
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 2.

Tytuł:: High resolution methods of the analysis of acoustic signals in medicine
Autorzy:: Lis, W.
Schmidt, J.
Powiązania:: https://bibliotekanauki.pl/articles/332161.pdf
Data publikacji:: 1999
Wydawca:: Polskie Towarzystwo Akustyczne
Opis:: The paper describes an analysis of the possible parametric methods used to estimate the spectrum of short acoustic signals of law oscillations. These kinds of signals often appear in acoustic waves emitted by the temporomandibular joint as it moves [1-2,5]. There is reason to suppose that the frequency which is characteristic of these oscillations could be an essential parameter confirming the pathology of the joint under examination. The measurement of low oscillations is difficult and not accurate, especially when nonparametric methods are used. The paper presents the results of analysis of a simulated short oscillating pulse using the DFT non-parametric method and the parametric method of linear prediction, using Burg algorithm. Finally, results of patient analysis are given, using the FFT and parametric methods.
Źródło:: Hydroacoustics; 1999, 2; 335-340
1642-1817
Pojawia się w:: Hydroacoustics
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 3.

Tytuł:: Determining the impedance of ultrasonic transducers by the added elements method
Autorzy:: Lis, W.
Schmidt, J.
Wojan, Z.
Powiązania:: https://bibliotekanauki.pl/articles/332719.pdf
Data publikacji:: 2005
Wydawca:: Polskie Towarzystwo Akustyczne
Opis:: There are a number of problems involved in measuring complex electrical impedance of ultrasonic transducers. This is because in the frequency function impedance tends to change values rapidly, in particular where resonances are involved. Measuring impedance using accurate bridge methods is a tedious and time-consuming process. While modern automated systems offer shorter test periods and high accuracy, they are very costly. This is why the project aims to implement new methods for computing impedance without these limitations. The article proposes a new, simplified method for measuring the electrical impedance of ultrasonic transducers. In the method complex impedance is calculated from results of two measurements of the transducer’s impedance magnitude only: with the known reactance and without it. To demonstrate the practicality of this method the authors included in the article the value of complex electrical impedance computed using the method and compared these with the results of measurements taken with an automated typical measurement system.
Źródło:: Hydroacoustics; 2005, 8; 99-104
1642-1817
Pojawia się w:: Hydroacoustics
Dostawca treści:: Biblioteka Nauki

Artykuł

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