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Novel S-transform information fusion for filtering ultrasonic pulse-echo signals

Kubinyi M., Kreibich O., Neuzil J., Smid R.

Przegląd Elektrotechniczny

2011

R. 87, nr 1

290-295

Direct evaluation of ultrasonic signals requires data analyses with an acceptable level of noise. Ultrasonic signals represent a specific category of time domain signals to be analyzed. In order to increase a difference between the level of noise and the amplitude of the ultrasonic pulse a suitable method for signal filtering has to be used. Within this article we discuss and evaluate a novel signal denoising method. The S-transform for signal analysis and processing was used. This transformation has been recently introduced for ultrasonic echo analyses. Proposed transformation represents an intermediate stage between the Fourier transform analysis and the wavelet transform analysis. In order to filter ultrasonic signals from the Electromagnetic Acoustic Transducer (EMAT) with a high level of noise, new, different approach in signal filtering was developed based on an information fusion. Suggested method is able to process the pulse-echo signal in its full complexity. Proposed method offers good results in studied ultrasonic signals in comparison to digital filter or wavelet denoising.

Bezpośrednia ocean sygnału ultradźwiękowego wymaga analizy danych obciążonych szumami. W celu zwiększenia różnicy między amplitudą sygnału a szumami użyto specjalnej metody filtrowania. Zastosowano transformatę S do analizy ultradźwiękowego sygnału echa. Tego typu transformata jest metodą pośrednia między transformatą Fouriera a transformatą falkową. Użyto nowej metody bazującej na fuzji informacji. Testy potwierdziły że nowa metoda może być skuteczniejsza niż filtrowanie cyfrowe czy odszumianie falkowe.

Determination of interfacial parameters of horizontal two-phase plug flow using a high speed pulse-echo ultrasonic technique

Masala T., Harvel G., Su J., Chang J.

Transactions of the Institute of Fluid-Flow Machinery

2010

nr 122

61-76

This paper presents a high-speed, multiple-transducers, pulse-echo ultrasonic technique for the measurement of interfacial parameters of horizontal two-phase intermittent flow regimes. The ultrasonic system consisted of an ultrasonic driver, a multiplexer with 4 transducers, and a microcomputer equipped with a data acquisition card, a motion controller card and the Winspect Data Acquisition software. Two transducers were mounted on the top of a 2.1 cm inner diameter circular pipe, while the other two transducers were mounted on the bottom of the pipe. Using instantaneous liquid level measurements from multiple transducers, two-phase flow interfacial parameters in plug were determined, such as the lengths and the velocities of liquid plugs and bubbles, the shape of the gas-liquid interface, and hence instantaneous and cross sectional averaged void fraction and interfacial area. The results showed that the liquid plug velocities as well as the elongated bubble velocity increases with increasing superficial liquid and gas velocities. An experimental correlation for liquid plug velocity was proposed based on the present results. The results also showed that the time and cross-sectional averaged void fraction in the plug flow regime was only slightly influenced by the superficial gas velocity but was not influenced by the superficial liquid velocity.