Российский фонд
фундаментальных
исследований

Физический факультет
МГУ им. М.В.Ломоносова
 

C

Cao Yonggang

 

Cao Yonggang, Chen Qian, Zheng Huifeng, Lu Lidong, Wang Yuebing, Zhu Jiang «Study on the Mechanism of Ultrasonic Power Measurement Sensor based on Pyroelectric Effect» Акустический журнал, 64, № 6, с. pp. 789-795 (2018)

PVDF pyroelectric sensor has been widely applied in many fields, such as intruder alarm. Nowadays, this sensor shows a potential for ultrasonic power measurement. However, the transformation mechanism between the acoustic and pyroelectric signals has not been particularly studied until now. In this paper, a physical model was introduced for theoretical study of the mechanism of energy transformations. In addition, a simulation program based on finite-element analysis method was built up for analyzing the ultrasound propagation characteristics and the temperature rise on the PVDF, as well it predicted the waveform and amplitude of the generated pyroelectric signal. Besides that, a PVDF pyroelectric sensor was fabricated and used for acoustic power measurement experiment. Finally, the experiment and simulation results were compared, confirming that the physical model is suitable for pyroelectric sensor characteristics analysis. It can also provide useful suggestions for the design and fabrication of PVDF pyroelectric sensors with high sensitivity.

Акустический журнал, 64, № 6, с. pp. 789-795 (2018) | Рубрика: 06.18

Chegini V.

 

Deldar H., Bidokhti A.A., Chegini V. «An Investigation of the Effects of Internal Waves on Sound Propagation in a Stratified Medium with a Sloping Bed» Акустический журнал, 64, № 1, с. pp. 58-63 (2018)

Internal waves usually cause temporal and spatial changes of density and consequently affect the acoustic wave propagation in the ocean. The purpose of this study is a laboratory investigation of the effects of internal waves generated by oscillation of a cylinder in a large stratified glass tank with a sloping bed on the sound waves propagation. Results showed that sound waves are affected by internal waves that depend on the slope angle to the direction of internal wave propagation angle ratio. When the ratio is subcritical or supercritical, the acoustic signal is much reduced as compared to the case with no sloped bottom. This can be explained in terms of the internal waves energy reaching the sloped bed and their reflections.

Акустический журнал, 64, № 1, с. pp. 58-63 (2018) | Рубрика: 07.03

Chen C.

 

Zhai J.X., Chen C. «Low-loss Floating Electrode Unidirectional Transducer for SAW Sensor» Акустический журнал, 65, № 2, с. pp. 178-184 (2019)

Two types of interdigital transducer (IDT) structures of SAW devices have been investigated; one type consists in a classical single electrode transducer where the unit cell has two electrodes, and the other type has a design of floating electrode unidirectional transducer (FEUDT) where the unit cell has six electrodes per period. By taking the Fourier transform of the corresponding time response, the insertion loss (IL) of the SAW device with FEUDT is calculated as –2.6 (forward) and –20.5 dB (backward). At the same time, the device with conventional IDT exhibits an IL value of –8.4 (forward) and –7.8 dB (backward). It turns out that the design of a novel FEUDT type SAW device can efficiently reduce the insertion loss of the SAW device.

Акустический журнал, 65, № 2, с. pp. 178-184 (2019) | Рубрика: 06.13

Chen Hao

 

Wu Delin, Dai Yuyu, Chen Hao, Zhou Yinqiu, Fu Lin, Wang Xiuming «Mode analysis of trilaminar bender bar transducers using an approximation method» Акустический журнал, 63, № 5, с. pp. 617-624 (2017)

Based on the vibration theory of a thin plate, an analytical treatment of the trilaminar bender bar with piezoelectric elements and inert substrate of various lengths is presented for mode analysis. Resonance frequency and effective electromechanical coupling coefficient are calculated by this method. The impacts of the geometries of the bender bar on the performance of its fundamental and third-order flexural mode are investigated in detail under rigid boundary conditions. It is shown that resonance frequency is extremely sensitive to the thickness of inert substrate. Moreover, the effective electromechanical coupling coefficient has peaks as the length of piezoelectric elements varies. The peaks are achieved when the length of piezoelectric elements equals the length between two nodes having zero strains in the x-direction. The trilaminar bender bar will be effectively excited when the strains on the piezoelectric element are in the same phase, which is important to disclose the vibration mechanisms of this kind of transducer. Also, analytical results are compared with the ones of numerical simulation. The results suggest that effective electromechanical coupling coefficient shares similar patterns with electrical conductance, which can be used to characterize transducer performance to a certain extent. It also demonstrates that the analytical treatment provides an efficient alternative way for optimizing the bender bar transducer design.

Акустический журнал, 63, № 5, с. pp. 617-624 (2017) | Рубрика: 06.14

Chen J.

 

Ding S.S., Jin S.J., Luo Z.B., Chen J., Lin L. «Researches on the ultrasonic scattering attenuation of carbon fibre reinforced plastics with 2D real morphology void model» Акустический журнал, 63, № 4, с. pp. 490-495 (2017)

In order to investigate the ultrasonic propagation in carbon fibre reinforced plastics with complex void morphology, the effective mathematical model needs to be established. The current models are oversimplified on void morphology, leading to the significant inconsistency of theoretical calculation with experimental results. In view of the problem, a real morphology void model (RMVM) was established with the idea of image-based modeling. The void morphology was extracted by digital image processing technology, and the material properties were assigned subsequently. As a result of the complex and random void morphology in RMVMs, a non-unique corresponding relationship was verified between porosity P and ultrasonic attenuation coefficient α. In the scatterplot of simulation, about 66 percent of points were plotted within the ±10% error band of fitting line, while almost all the data located at the ±20% error zone. The simulation results showed good consistency with experiments, and it proved the validity of RMVM. The investigation provides a novel model to explore the ultrasonic scattering mechanism for the composite materials containing random voids.

Акустический журнал, 63, № 4, с. pp. 490-495 (2017) | Рубрика: 06.02

Chen Jiu-Jiu

 

Huo Shao-Yong, Chen Jiu-Jiu, Song Guang-Huang, Han Xu «Asymmetric propagation of the first order antisymmetric lamb wave in a tapered plate based on time domain analysis» Акустический журнал, 63, № 4, с. pp. 393-401 (2017)

The asymmetric propagation of the first order antisymmetric (A1) Lamb wave in a tapered plate respectively carved with sharp bottom corner and round bottom corner is theoretically investigated. Through numerical simulation of A1 Lamb wave in time domain, we find that when the thickness of the waveguide abruptly decreases to below the cut-off thickness, about half of the A1 mode is converted into the fundamental symmetrical S0 and antisymmetrical A0 modes to pass through the defected region. Furthermore, the transmitted modes A0 and S0 are completely apart from each other and can be quantitatively evaluated. Conversely, when the thickness change is very smooth, most of the energy of A1 Lamb wave is reflected back. It is the unique mode conversion behavior that leads to great transmission difference value of A1 Lamb wave along the opposite directions. Finally, the influence of geometrical parameters on the transmission coefficient is also studied. The higher efficiency and proper working frequency range can be realized by adjusting the slope angle τ, height h1 and h2. The simple asymmetric systems will be potentially significant in applications of ultrasound diagnosis and therapy.

Акустический журнал, 63, № 4, с. pp. 393-401 (2017) | Рубрика: 04.15

Chen Qian

 

Cao Yonggang, Chen Qian, Zheng Huifeng, Lu Lidong, Wang Yuebing, Zhu Jiang «Study on the Mechanism of Ultrasonic Power Measurement Sensor based on Pyroelectric Effect» Акустический журнал, 64, № 6, с. pp. 789-795 (2018)

PVDF pyroelectric sensor has been widely applied in many fields, such as intruder alarm. Nowadays, this sensor shows a potential for ultrasonic power measurement. However, the transformation mechanism between the acoustic and pyroelectric signals has not been particularly studied until now. In this paper, a physical model was introduced for theoretical study of the mechanism of energy transformations. In addition, a simulation program based on finite-element analysis method was built up for analyzing the ultrasound propagation characteristics and the temperature rise on the PVDF, as well it predicted the waveform and amplitude of the generated pyroelectric signal. Besides that, a PVDF pyroelectric sensor was fabricated and used for acoustic power measurement experiment. Finally, the experiment and simulation results were compared, confirming that the physical model is suitable for pyroelectric sensor characteristics analysis. It can also provide useful suggestions for the design and fabrication of PVDF pyroelectric sensors with high sensitivity.

Акустический журнал, 64, № 6, с. pp. 789-795 (2018) | Рубрика: 06.18

Chen Tianning

 

Li Suobin, Xi Yanhui, Chen Tianning, Wang Xiaopeng «Modulating Lamb wave band gaps using an elastic metamaterial plate» Акустический журнал, 63, № 5, с. pp. 508-516 (2017)

Modulating band gaps (extending the bandwidths or shifting into a lower frequency range) is a challenging task in phononic crystals. In this paper, elastic metamaterial plates composed of a square array of “hard” stubs or “soft” stubs on both sides of a 2D binary locally resonant plate are proposed, and their band structures are studied. The dispersion relationships and the displacement fields of the eigenmodes are calculated using finite element methods. Numerical results show that the band gaps are shifted to lower frequencies and the bandwidths are enlarged compared to classic elastic metamaterial plates. A conceptual “analogousrigid mode” that includes an “out-of-plane analogous-rigid mode” and an “in-plane analogous-rigid mode” is developed to explain these phenomena. The “out-of-plane analogous-rigid mode” mainly adjusts the band gaps into the lower frequency range, and the “in-plane analogous-rigid mode” mainly enlarges the bandwidth. Furthermore, the band gap effects of composite “hard” stubs and “soft” stubs are investigated. The results show that the location of the band gaps can be modulated into a relatively lower frequency and the bandwidth can be extended by the use of different composite stubs. These elastic wave properties in the proposed structure can be used to optimize band gaps and possibly produce low-frequency filters and waveguides.

Акустический журнал, 63, № 5, с. pp. 508-516 (2017) | Рубрика: 06.15

Li Suobin, Dou Yihua, Chen Tianning, Wan Zhiguo, Ju Luyan, Zhang Fan, Cui Xiao Xiao «Forming Low-Frequency Complete Vibration Bandgaps in a thin Nonmetallic Elastic Metamaterial Plate» Акустический журнал, 65, № 3, с. pp. 322-333 (2019)

Low-frequency vibration-bandgaps in elastic metamaterials open new possibilities to minimize low-frequency vibration and noise. Unfortunately, fabricating a complete vibration bandgap for low frequencies still represents a challenging engineering task. In this paper, a new type of a low-frequency complete vibration bandgap in a thin non-metal elastic metamaterial plate is introduced and investigated numerically. The proposed elastic metamaterial plate consists of decoupling-resonators, which are deposited on a 2D, locally resonant phononic-crystal plate, made of an array of rubber fillers, which are embedded in a nonmetallic plate. The dispersion relationship, the power-transmission spectrum, and the displacement fields for the eigenmode are calculated using the finite element method. It is shown that coupling between the local resonance mode of the decoupling-resonators and the Lamb-wave mode of the epoxy plate, consistent with the modal superposition principle, is responsible for the formation of vibration bandgaps. Moreover, the equivalent spring-mass system for the coupling-resonators can be decoupled by introducing a rubber filler. In addition, both longitudinal and the transverse elastic wave bandgaps can be tuned to the same low-frequency range. As a result, a novel kind of low-frequency complete vibration bandgap, which can damp a low-frequency elastic wave, is produced. Furthermore, the effects of the decoupling-resonators on the vibration bandgap are investigated. It is now possible that an elastic metamaterial plate can be dampen with complete low-frequency vibration bandgaps, which can potentially be used for commercial noise and vibration reduction.

Акустический журнал, 65, № 3, с. pp. 322-333 (2019) | Рубрика: 06.15

Chen X.C.

 

Chen X.C., Liu S.Q., Liu Y. «Влияние флуктуаций заряда пыли на ионно-звуковые волны в плазме с неэкстенсивными электронами» Физика плазмы, 45, № 11, с. 999-1006 (2019)

Получена линейная дисперсия ионно-звуковых волн (IAWs – ion acoustic waves) с учетом эффектов флуктуации заряда пылевых частиц и неэкстенсивности электронов. Показано, что наличие неэкстенсивных электронов изменяет характер флуктуаций заряда, приводя диссипации и неустойчивости для IAWs. Зависимость частоты и инкремента неустойчивости IAWs от параметра неэкстенсивности электронов q определяется плотностью пыли, которая сильно влияет на флуктуации заряда пыли.

Физика плазмы, 45, № 11, с. 999-1006 (2019) | Рубрика: 06.08

Chen Xiaodong

 

Li Jiake, Chen Xiaodong, Wang Yi, Shi Yifeng, Yu Daoyin «Generalized sidelobe canceler beamforming applied to medical ultrasound imaging» Акустический журнал, 63, № 2, с. pp. 229-236 (2017)

A generalized sidelobe canceler (GSC) approach is proposed for medical ultrasound imaging. The approach uses a set of adaptive weights instead of traditional non-adaptive weights, thus suppressing the interference and noise signal of echo data. In order to verify the validity of the proposed approach, Field II is applied to obtain the echo data of synthetic aperture (SA) for 13 scattering points and circular cysts. The performance of GSC is compared with SA using boxcar weights and Hamming weights, and is quantified by the full width at half maximum (FWHM) and peak signal-to-noise ratio (PSNR). Imaging of scattering point utilizing SA, SA (hamming), GSC provides FWHMs of 1.13411, 1.68910, 0.36195 mm and PSNRs of 60.65, 57.51, 66.72 dB, respectively. The simulation results of circular cyst also show that GSC can perform better lateral resolution than non-adaptive beamformers. Finally, an experiment is conducted on the basis of actual echo data of an ultrasound system, the imaging result after SA, SA (hamming), GSC provides PWHMs of 2.55778, 3.66776, 1.01346 mm at z=75.6 mm, and 2.65430, 3.76428, 1.27889 mm at z=77.3 mm, respectively.

Акустический журнал, 63, № 2, с. pp. 229-236 (2017) | Рубрика: 13.04

Chen Y.

 

Wang Q., Zhou B., Chen Y., Quan H. «Subarray Beam-space Adaptive Beamforming Combined with Array Shape Estimation based on Non-Acoustic Sensor» Акустический журнал, 65, № 2, с. pp. 226-233 (2019)

To address the issue of serious decline in performance of the array signal processing caused by the towed array shape distortion during maneuvering, this paper presents a new method of subarray beam-space adaptive beamforming combined with an array shape estimation method based on non-acoustic sensor. Firstly, the array shape through the approximate circular arc structure of the array segment between the adjacent sensor during maneuvering is preliminary calculated. Next, the final estimated array shape through a smooth processing method on the entire array shape by means of a calibration method using spline interpolation technique is achieved. This method is able to estimate the array shape in real time. The array steering vector based on the real-time estimation of the array shape is updated, using a subarray beam-space adaptive beamforming (SBABF) to reduce the demand of the number of the snapshots. And the beam-space covariance matrix converges fast within a few snapshots. The SBABF method combined with array shape estimation (AE-SBABF) was verified by simulation data and sea trial data processing results. During maneuvering, the AE-SBABF can not only improve the array processing gain of the target effectively, but also solve the left/right ambiguity problem well.

Акустический журнал, 65, № 2, с. pp. 226-233 (2019) | Рубрика: 07.19

Cui Xiao Xiao

 

Li Suobin, Dou Yihua, Chen Tianning, Wan Zhiguo, Ju Luyan, Zhang Fan, Cui Xiao Xiao «Forming Low-Frequency Complete Vibration Bandgaps in a thin Nonmetallic Elastic Metamaterial Plate» Акустический журнал, 65, № 3, с. pp. 322-333 (2019)

Low-frequency vibration-bandgaps in elastic metamaterials open new possibilities to minimize low-frequency vibration and noise. Unfortunately, fabricating a complete vibration bandgap for low frequencies still represents a challenging engineering task. In this paper, a new type of a low-frequency complete vibration bandgap in a thin non-metal elastic metamaterial plate is introduced and investigated numerically. The proposed elastic metamaterial plate consists of decoupling-resonators, which are deposited on a 2D, locally resonant phononic-crystal plate, made of an array of rubber fillers, which are embedded in a nonmetallic plate. The dispersion relationship, the power-transmission spectrum, and the displacement fields for the eigenmode are calculated using the finite element method. It is shown that coupling between the local resonance mode of the decoupling-resonators and the Lamb-wave mode of the epoxy plate, consistent with the modal superposition principle, is responsible for the formation of vibration bandgaps. Moreover, the equivalent spring-mass system for the coupling-resonators can be decoupled by introducing a rubber filler. In addition, both longitudinal and the transverse elastic wave bandgaps can be tuned to the same low-frequency range. As a result, a novel kind of low-frequency complete vibration bandgap, which can damp a low-frequency elastic wave, is produced. Furthermore, the effects of the decoupling-resonators on the vibration bandgap are investigated. It is now possible that an elastic metamaterial plate can be dampen with complete low-frequency vibration bandgaps, which can potentially be used for commercial noise and vibration reduction.

Акустический журнал, 65, № 3, с. pp. 322-333 (2019) | Рубрика: 06.15