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1

Ultradźwięki w zastosowaniach medycznych – nowe możliwości pomiarowe Zakładu Mechaniki i Akustyki

Dobrowolska Danuta, Falińska Katarzyna

Metrologia i Probiernictwo : biuletyn Głównego Urzędu Miar

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2022

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nr 1 (28)

37--42

PL

Artykuł przedstawia aparaturę pomiarową do wzorcowań i badań w dziedzinie ultradźwięków w zastosowaniach medycznych, zakupioną dla Głównego Urzędu Miar w 2021 roku i jej możliwości pod kątem zapewnienia w Polsce spójności pomiarowej w tej dziedzinie. Przedstawia też stan badań nad wdrożeniem w GUM metod realizowanych za pomocą zakupionych systemów pomiarowych oraz wskazuje perspektywy rozwoju.

EN

The article presents measuring equipment for calibration and testing in the field of medical ultrasound, purchased for the Central Office of Measures in 2021, and its capabilities in terms of assuring measurement traceability in this area in Poland. It also presents the state of research on the implementation of the methods implemented in the GUM with the use of purchased measurement systems and indicates development prospects.

2

Optical fiber marine seismic exploration system feasibility study

Wang Xiangchun, Li Xueliang, Zhang Haibing, Hao Xiaozhu, Yu Kaiben

Acta Geophysica

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2019

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Vol. 67, no. 5

1403--1411

EN

The signal-to-noise ratio (SNR), vertical resolution and fdelity of marine seismic data are closely related to the characteristics of hydrophones, namely the sensitivity and the frequency band range. In this article, we analyzed and processed seismic data collected in 2017 from a towed marine streamer equipped with optical fiber cable and hydrophones. Results from a pre-stack time migration section revealed that the optical fiber seismic data yielded high SNR, vertical resolution and fdelity. For validation purpose, a comparison of these data with those acquired by classic piezoelectric hydrophones along a migration section located in a very close location was carried out. This comparison showed that the SNR, fdelity and vertical resolution from the two means of measurements were comparable.

3

Influence of protective hydrophone housing on its receiving sensitivity

Kula S., Józwiak R.

Hydroacoustics

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2017

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Vol. 20

99--104

EN

The purpose of the carried-out examinations was to verify the receiving sensitivity of the hydrophone placed inside a protective housing. In order to increase resistance to damage, the hydrophone Reson TC4032 has been adapted to work in difficult environmental conditions. Using a comparative method, we analyzed the receiving sensitivity within a predetermined frequency band. The experiment was carried with two hydrophones: the examined one, and a reference one. An underwater speaker with a function generator was used as the sound source. The studies have been conducted in a water tank under laboratory conditions. In situ studies have determined the decrease of the receiving sensitivity of the hydrophone equipped with the protective housing.

4

Laboratory to measure directivity characteristics of arrays

Grelowska G., Szymczak W., Buszman K.

Hydroacoustics

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2008

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Vol. 11

381-388

EN

The paper presents the laboratory station to measure directivity characteristics of narrow beam sonar's and echo sounder's antennas. It will be describe method of collecting samples from surface, unit used to precise positioning receiving hydrophone, construction and use of rack to direct main beam in exact direction. Additionally we show station to measure drift of the sea bottom impedance.

5

Computing and measuring nonlinear and linear propagation by two independent methods

Filipczyński L., Kujawska T., Secomski W., Tymkiewicz R., Wójcik J.

Archives of Acoustics

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1999

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Vol. 24, no. 3

269-288

EN

Nonlinear effects, caused by propagation of ultrasonic pulses with finite amplitudes, were computed and measured in water in the case of pulses with pressures up to 1.5MPapp used in diagnostic devices. An electronic transmitter generated high (280Vpp) and low (47Vpp) voltages, applied to a plane PZT transducer causing in this way nonlinear and linear propagation effects. The carrier frequency of the pulse was 2MHz, while its time duration was 2.5\,ms. The measurements were carried out by means of a typical calibrated PVDF membrane hydrophone and by an electromagnetic (EM) hydrophone, prepared for this study. The pulse measurements by means of the PVDF hydrophone showed a higher number of spectral components than those by means of the EM hydrophone. This effect was explained by sensitivity characteristics that increased in the PVDF and decreased in the EM hydrophone as a function of frequency. Previously, it was shown that the effective frequency band used in measurements by means of the PVDF hydrophone is situated below the resonance, on the increasing slope of the resonanse curve. The properties of the EM hydrophone were analysed on the basis of the plane wave assumption. A procedure was developed to correct distortions of the pulse spectrum and its pressure measured by PVDF and EM hydrophones. In the first case the maximum peak-to-peak pulse pressure should be decreased by 27%, while in the second case it should be increased by only 0.7%, and by 3% if an additional amplifier was used. The sensitivities of PVDF and EM hydrohones were very different and equal for the frequency of 2MHz to 28mV/MPa and 0.10mV/MPa, respectively. The calibration of the EM hydrophone was carried out by means of only two simple: electrical and magnetic independent measurements, although in the EM hydrophone there occured external interferring signals. For the theoretic-numerical detemination of the acoustic fields and their spectra generated in the case of nonlinear and linear propagation the numerical procedure called the WJ Code was applied. It was developed recently by the last-named author of this paper. In calculations absorption in water was taken into account. The critical distance, where distortions caused by nonlinear propagation in water were maximum, was determined by a number of computations of the ultrasonic field as a function of the distance from the transducer. A good agreement between computed results and those measured by two different methods, showing the pulse pressure distribution along the whole beam axis, was confirmed. In this case it was shown that the ?/4 matching layer covering the transducer surface influenced the edge wave radiated by the transducer.

6

Podstawy teorii i techniki łączności podwodnej

Katulski J., Kosiński A., Pawłowski W., Studański R.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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1998

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nr 9

621-629

PL

W artykule przedstawiono podstawowe zagadnienia dotyczące systemu łączności z zanurzonym okrętem podwodnym. Przeanalizowano uwarunkowania propagacyjne. Omówiono problematykę rozchodzenia się fal radiowych nad powierzchnią wody oraz mechanizm ich wnikania w środowisko wodne. Przedstawiono zasadę działania oraz budowę podwodnego urządzenia antenowego oraz rozwiązania odbiornika radiowego. Omówiono także realizację łączności podwodnej przy użyciu fal akustycznych.

EN

The subject of this paper are the main principles of the underwater communication theory and techniques. First, the radiowaves propagation conditions in the air and the water are analysed. The different structures of the underwater antenna system are described. The problem of the application of an acustic underwater telephone is analysed too.