Российский фонд
фундаментальных
исследований

Физический факультет
МГУ им. М.В.Ломоносова
 

T

Tamoši~-unas M.

 

Jurkonis R., Sakalauskas A., Lukoševičius A., Maciulevičius M., Tamoši~-unas M., Šatkauskas S. «Mapping Microbubble and Ultrasound Spatio-temporal Interaction by M-mode Imaging: The Study of Feasibility» Акустический журнал, 65, № 2, с. pp. 216-225 (2019)

Ultrasound (US) and microbubble (MB) interaction is an important factor in the research of bioacoustics, as well as targeted drug and gene delivery. In this study, we demonstrate the feasibility of pulse–echo M-mode imaging system to be used for the visualization and quantification of US–MB interaction in both spatial and temporal dimensions. The system incorporates an exposure chamber with the cell–MB suspension, a 2.7 MHz focused US transducer, a US pulser–receiver and the customized LabView software. The results of cell and MB interaction obtained after M-mode image analysis have showed the US–MB interaction to be non-uniform in space and non-stationary in time. In order to quantify the spatio-temporal US–MB interaction, we have introduced the time function of spatial homogeneity dynamics. We have observed that the effective duration of interaction can be characterized at the predefined threshold of spatial homogeneity. For example, at the US excitation of 360 kPa peak negative pressure (15 bursts transmitted at 80 Hz pulse repetition frequency), the US–MB interaction persists for more than 5 seconds in the range at 4 mm depth of the exposure chamber with more than 50% of homogeneity. The system proposed in this assay is feasible for the characterization of US–MB interaction and can be exploited to optimize the MB concentration and/or the US excitation parameters.

Акустический журнал, 65, № 2, с. pp. 216-225 (2019) | Рубрика: 13.04

Tang Jun

 

Tang Jun , Petrov P.S., Piao Shengchun , Kozitskiy S.B. «On the Method of Source Images for the Wedge Problem Solution in Ocean Acoustics: Some Corrections and Appendices» Акустический журнал, 64, № 2, с. pp. 225-236 (2018)

In this study the method of source images for the problem of sound propagation in a penetrable wedge [G. Deane and M. Buckingham, J. Acoust. Soc. Am. 93 (1993) 1319-1328] is revisited. This solution is very important three-dimensional (3D) benchmark in computational underwater acoustics, since a wedge bounded from above by the sea surface and overlying a sloping penetrable bottom is the simplest model of a shallow-sea waveguide near the coastline. The corrected formulae for the positions of the source images and bottom images are presented together with the explanation of their derivation. The problem of branch choice in the reflection coefficient is thoroughly discussed, and the corresponding explicit formulae are given. In addition, numerical validation of the proposed branch choice schemes and the resulting wedge problem solutions are presented. Finally, source images solution is computed for a series of examples with different ratios of shear and bulk moduli in the bottom. The interplay between the acoustic-elastic waves coupling and the horizontal refraction in the wedge is demonstrated.

Акустический журнал, 64, № 2, с. pp. 225-236 (2018) | Рубрика: 07.02

Tao C.H.

 

Li H.X., Tao C.H., Goloshubin G., Liu C., Shi S.H., Huang G.N., Zhang H., Zhang J., Zhang X.F. «A Modified Biot/Squirt Model of Sound Propagation in Water-Saturated Sedment» Акустический журнал, 64, № 4, с. pp. 453-458 (2018)

A modified Biot/Squirt flow model was developed. The difference between MBISQ and BISQ models is the expression for the porosity differential. Numerical analysis shows that the acoustic dispersion predicted by MBISQ is much higher than by BISQ. Investigations of the effects of permeability, viscosity, and squirt flow length on velocity and attenuation indicate that the behavior of MBISQ agrees with that of the BISQ model. The result of sediment acoustic inversion based on MBISQ was more reasonable than the result of BISQ model.

Акустический журнал, 64, № 4, с. pp. 453-458 (2018) | Рубрика: 07.14

Tazhibaev I.I.

 

Zakhidov E.A., Kokhkharov A.M., Kuvondikov V.O., Nematov Sh.K., Tazhibaev I.I. «A Low-Frequency Photoacoustic Spectrometer with an RGB Light-Emitting Diode for Evaluating Photosynthetic Activity in Plant Leaves» Акустический журнал, 65, № 1, с. pp. 90-95 (2019)

A photoacoustic spectrometer based on a three-colored light-emitting diode (with peak emission wavelengths of 465, 525, and 640 nm) designed to determine the intensity of photosynthesis in different deep layers of plant leaves is described. The physical properties of the photoacoustic signal were studied at different wavelengths and light modulation frequencies. It was shown that the proposed spectrometer can be employed for quantitative evaluation of heat dissipation and photochemical assimilation of the absorbed light energy in this medium.

Акустический журнал, 65, № 1, с. pp. 90-95 (2019) | Рубрика: 06.17

Tong Yunzhe Wei Wang

 

Tong Yunzhe  Wei Wang, Fan Jun, Wang Bin «Acoustic Scattering from a Cylindrical Shell with Double Internal Rigid Plates» Акустический журнал, 65, № 1, с. pp. 7-13 (2019)

The acoustic scattering from an infinite cylindrical shell with double internal rigid plates at normal incidence is studied by theoretical and experimental approaches. The two rigid plates are attached to the shell along lines parallel to the shell axis symmetrically. The dominant feature of frequency-angle spectra is the interference fringes caused by the reflection waves of attachments in the illuminated region and specular reflection. For a cylindrical shell with double internal plates, there may be several attachments in the illuminated region simultaneously. There will be bright spots when two interference fringes caused by two attachments in the illuminated region intersect, while only interference fringes can be observed for one attachment in the illuminated region. Theoretical and experimental results show that the number of attachments in illuminated region can significantly affect the scattering characteristics, and it is a prominent feature to identify the location of internal plates.

Акустический журнал, 65, № 1, с. pp. 7-13 (2019) | Рубрика: 04.04

Turo Diego

 

Guan Shane, Southall Brandon L., Vignola Joseph F., Judge John A., Turo Diego «Sonar inter-ping noise field characterization during cetacean behavioral response studies off Southern California» Акустический журнал, 63, № 2, с. 204-215 (2017)

The potential negative effects of sound, particularly active sonar, on marine mammals has received considerable attention in the past decade. Numerous behavioral response studies are ongoing around the world to examine such direct exposures. However, detailed aspects of the acoustic field (beyond simply exposure level) in the vicinity of sonar operations both during real operations and experimental exposures have not been regularly measured. For instance, while exposures are typically repeated and intermittent, there is likely a gradual decay of the intense sonar ping due to reverberation that has not been well described. However, it is expected that the sound field between successive sonar pings would exceed natural ambient noise within the sonar frequency band if there were no sonar activity. Such elevated sound field between the pings may provide cues to nearby marine mammals on source distances, thus influencing potential behavioral response. Therefore, a good understanding of the noise field in these contexts is important to address marine mammal behavioral response to MFAS exposure. Here we investigate characteristics of the sound field during a behavioral response study off California using drifting acoustic recording buoys. Acoustic data were collected before, during, and after playbacks of simulated mid-frequency active sonar (MFAS). An incremental computational method was developed to quantify the inter-ping sound field during MFAS transmissions. Additionally, comparisons were made between inter-ping sound field and natural background in three distinctive frequency bands: low-frequency (<3 kHz), MFA-frequency (3–4.5 kHz), and high-frequency (>4.5 kHz) bands. Results indicate significantly elevated sound pressure levels (SPLs) in the inter-ping interval of the MFA-frequency band compared to natural background levels before and after playbacks. No difference was observed between inter-ping SPLs and natural background levels in the low- and high-frequency bands. In addition, the duration of elevated inter-ping sound field depends on the MFAS source distance. At a distance of 900–1300 m from the source, inter-ping sound field at the exposure frequency is observed to remain 5 dB above natural background levels for approximately 15 s, or 65%, of the entire inter-ping interval. However, at a distance of 2000 m, the 5 dB elevation of the inter-ping SPLs lasted for just 7 s, or 30% of the inter-ping interval. The prolonged elevation of sound field beyond the brief sonar ping at such large distances is most likely due to volume reverberation of the marine environment, although multipath propagation may also contribute to this.

Акустический журнал, 63, № 2, с. 204-215 (2017) | Рубрика: 13.01

Tyagi Kapil Dev

 

Tyagi Kapil Dev, Kumar Arun, Bahl Rajendar, Singh Karmjeet «Experimental measurement of acoustic properties in snow» Акустический журнал, 63, № 3, с. 297-301 (2017)

This paper presents the results of field experiments done for the measurement of attenuation constant and speed of sound in the snow medium. The field experiments were conducted at two locations corresponding to relatively dry and wet snow. The main objective of our method is to overcome the potential limitations of the other methods. There are two major concerns: one is sound signal leakage and the other is the measurement need to be done within a same layer of snowpack. The ref lections from the boundaries will affect the measurements. In our experiments the transducers are kept far from the snowpack boundaries, so that there will be no likelihood of strong ref lected signals from the boundaries. These issues have not been addressed by the other researchers. This work adds to the measurement results of the attenuation constant and speed of sound in snow that are available in the research literature. It is found that sound signal attenuation greatly depends on the frequency of sound signal and wetness of snow.

Акустический журнал, 63, № 3, с. 297-301 (2017) | Рубрика: 09.02