Laidoudi F., Boubenider F., Mebarki M., Medjili F., Bettine F. «Numerical Investigation of Quasi-Lamb Modes in c–Tilted ZnO/SiC Composite Membrane for High Performance Pressure Micro-Sensor» Акустический журнал, 65, № 3, с. pp. 253-262 (2019)

Using the finite element method, we have studied the Lamb modes characteristics propagation in c tilted ZnO/SiC thin film composite membrane. Phase velocity dispersion curves, electromechanical coupling factors and the mass loading effect on the fundamental quasi Lamb modes are theoretically investigated for different rotating angle (0], τ°, 90°), τ being the angle of rotation, and for different h_ZnO/λ values. To develop high performance pressure micro-sensor based on thin film piezoelectric ZnO on amorphous SiC (range 0.1 to 100 Pa) the anti-symmetric fundamental qA0 mode phase shift is studied for pressure sensing.

Dunai L., Lengua I., Iglesias M., Peris-Fajarnés G. «Buffeting-Noise Evaluation in Passenger Vehicle BMV 530d» Акустический журнал, 65, № 5, с. pp. 578-582 (2019)

In this paper we exhibit the results and evaluation of the buffeting-noise effect in a BMW 530d model vehicle. The buffeting noise was studied in real measurement conditions in an outdoors highway at different speeds. We evaluate different listening positions inside the vehicle to demonstrate that the buffeting-noise effect is independent from the listener position.

Li Baolei, Li Tinghua, Wu Jun, Hui Ming, Yuan Gang, Zhu Yongsheng «An arbitrary-shaped acoustic cloak with merits beyond the internal and external cloaks» Акустический журнал, 63, № 1, с. pp. 45-53 (2017)

Based on transformation acoustics, an arbitrary-shaped acoustic cloak capable of functioning as an information exchange-enabling internal cloak and a movement-allowing external cloak is presented. The general expressions of material parameters for the acoustic cloaks with arbitrarily conformal or non-conformal boundaries are derived, and then the performances of developed cloaks are validated by full-wave simulations. Finally, the different characteristics of the linear and nonlinear transformations-based cloaks are compared and analyzed. The proposed cloak could lead to wider applications beyond that of normal cloaks, since it effectively compensates the insufficiencies of traditional internal and external cloaks. Besides, this work also provides a new method to design bifunctional device and suggests an alternative way to make a large object invisible.

Sun Fei, Guo Shuwei, Li Borui, Liu Yichao, He Sailing «An Acoustic Metamaterial Lens for Acoustic Point-to-Point Communication in Air» Акустический журнал, 65, № 1, с. pp. 1-6 (2019)

Acoustic metamaterials have become a novel and effective way to control sound waves and design acoustic devices. In this study, we design a 3D acoustic metamaterial lens (AML) to achieve point-to-point acoustic communication in air: any acoustic source (a speaker) in air enclosed by such an AML can produce an acoustic image where the acoustic wave is focused (the field intensity is at a maximum, and the listener can receive the information), while the acoustic field at other spatial positions is low enough that listeners can hear almost nothing. Unlike a conventional elliptical reflective mirror, the acoustic source can be moved around inside our proposed AML. Numerical simulations are given to verify the performance of the proposed AML.

Su Ting, Zhang Shi, Li Dayu, Yao Dingjie «Combined Sign Coherent Factor and Delay Multiply and Sum Beamformer for Plane Wave Imaging» Акустический журнал, 64, № 3, с. pp. 379-386 (2018)

Plane wave imaging is a relatively new technique in ultrasound imaging. However, in traditional methods, the coherent information of different emissions and different elements are not considered. In fact, the sign coherent factor (SCF) can improve the lateral resolution of the imaging greatly. In addition, the delay multiply and sum (DMAS) beamformer is mainly based on the spatial correlation of background scattering signals, it has higher contrast and resolution, but suffers from energy loss at great depths. In this paper, combining the advantages of SCF and DMAS, the sign coherent factor delay multiply and sum (SCF-DMAS) beamformer for plane wave imaging is proposed. Unlike the traditional plane wave imaging, the proposed SCF-DMAS beamformer is based on the 2-D echo data set, which improves the imaging speed greatly. Finally, we simulated the point targets and the cyst phantom to evaluate the performance of proposed method. Compared with the traditional plane wave imaging, the lateral resolution of SCF-DMAS beamformer improves greatly for the point targets, and for the cyst phantom the contrast ratio (CR) and contrast-to-noise ratio (CNR) increased by 96.97 and by 79.98% respectively without reducing the frame rate.

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.

Li Hui «Streamline Computation Study on Rotation Aerodynamic Noise Prediction of Cross-flow Fan» Акустический журнал, 65, № 4, с. pp. 418-431 (2019)

The approach of resolving analysis the cross-flow relative motion streamline on the cross-flow straight blade is presented to predict the rotation aerodynamic noise performance of cross-flow fan by solving the dipole source term of Ffowcs Williams and Hawkings equation, while the cross-flow fan is applied in the indoor unit of split-type air-conditioner and operated in the rated condition. The calculating results of the method are respectively drawn by programming in Matlab computational language, and compared with the results of CAA numerical simulation and noise experiment. There are some differences in the distribution condition of aerodynamic force fluctuation amplitude on the blade surface, and sound pressure in the related frequency on the indoor unit casing, or on the sphere far field, between the streamline computation approach and numerical simulation. The orders of magnitudes of these calculating results solved by the analyzing streamline method are similar with that attained by the numerical simulation. The resolving analysis approach has the characteristics of decreasing the computing cost and not constructing the acoustics grid model of fan, compared with the numerical simulation. The error between the result of numerical simulation and noise test is larger than that between the result of theoretical calculation and noise test, so the approach could be used for the rotation aerodynamic noise analysis of the cross-flow fan.

Li J., Liu C.J., Zhang W.J. «Pressure potential and stability analysis in an acoustical noncontact transportation» Акустический журнал, 63, № 1, с. pp. 125-131 (2017)

Near field acoustic traveling wave is one of the most popular principles in noncontact manipulations and transportations. The stability behavior is a key factor in the industrial applications of acoustical noncontact transportation. We present here an in-depth analysis of the transportation stability of a planar object levitated in near field acoustic traveling waves. To more accurately describe the pressure distributions on the radiation surface, a 3D nonlinear traveling wave model is presented. A closed form solution is derived based on the pressure potential to quantitatively calculate the restoring forces and moments under small disturbances. The physical explanations of the effects of fluid inertia and the effects of non-uniform pressure distributions are provided in detail. It is found that a vibration rail with tapered cross section provides more stable transportation than a rail with rectangular cross section. The present study sheds light on the issue of quantitative evaluation of stability in acoustic traveling waves and proposes three main factors that influence the stability: (a) vibration shape, (b) pressure distribution and (c) restoring force/moment. It helps to provide a better understanding of the physics behind the near field acoustic transportation and provide useful design and optimization tools for industrial applications.

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.

Gu Xinzhong, Li Shunming «Convolution Quadrature Time-Domain Boundary Element Method for Two-Dimensional Aeroacoustic Noise Prediction» Акустический журнал, 64, № 6, с. pp. 731-741 (2018)

The computation of a compressible flow for aeroacoustic prediction is a challengeable work insofar as the fluctuation is usually very small in a sound field compared with the flow field. For the low Mach number considered in this study, a discrete vortex method in conjunction with fast multipole time-domain boundary element method is developed and applied to predict far-field sound resulting from a 2D vortex dominated flow. The flow field is simulated employing the classical discrete vortex method. The sound field scattered by solid bodies is determined by using a time-domain boundary element method combined with the convolution quadrature approach, by means of which the convolution integral is approximated by a quadrature formula utilizing a Laplace-domain fundamental solution. In addition, the fast multipole method is applied to improve the computational efficiency. Finally, several examples are presented to check the applicability and accuracy of the method. Numerical results indicate that the noise predicted by the present method agrees well with the experimental results, and the sound pressure levels of the cylinder models have a dipole-like directivity at vortex shedding frequency.

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.

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.

Li Baolei, Li Tinghua, Wu Jun, Hui Ming, Yuan Gang, Zhu Yongsheng «An arbitrary-shaped acoustic cloak with merits beyond the internal and external cloaks» Акустический журнал, 63, № 1, с. pp. 45-53 (2017)

Based on transformation acoustics, an arbitrary-shaped acoustic cloak capable of functioning as an information exchange-enabling internal cloak and a movement-allowing external cloak is presented. The general expressions of material parameters for the acoustic cloaks with arbitrarily conformal or non-conformal boundaries are derived, and then the performances of developed cloaks are validated by full-wave simulations. Finally, the different characteristics of the linear and nonlinear transformations-based cloaks are compared and analyzed. The proposed cloak could lead to wider applications beyond that of normal cloaks, since it effectively compensates the insufficiencies of traditional internal and external cloaks. Besides, this work also provides a new method to design bifunctional device and suggests an alternative way to make a large object invisible.

Ma Huayuan, Long Yuan, Zhong Mingshou, Li Xinghua, Xie Quanmin «Study on Ground Vibration Mode of Physical Explosion of High Pressure Natural Gas Pipeline» Акустический журнал, 65, № 5, с. pp. 583-592 (2019)

In this paper, an explosion experiment was carried out on the OD1219mm-X90-12Mpa natural gas pipeline to study the vibration hazard. Based on a series of experiments, the spatial distribution of the vibration energy was studied. The vibration distribution field was drawn by interpolation method based on re-harmonic equation and it was found that the field was non-circular symmetry. Through in-depth research, it was preliminarily proved that the vibration field had interference characteristics, which was caused by the special vibration source of the pipeline explosion. There was a significant difference in the frequency components between the interference strengthened region and the weakened region. The results shown that the strengthening effect of the interference in the 90° and 30° direction should be taken into account when evaluating the damage scope of the explosion accident. Research provided reference for safety design of parallel pipelines and buildings.

Xu Shi-da, Li Yuan-hui, Liu Jian-po «Detection of cracking and damage mechanisms in brittle granites by moment tensor analysis of acoustic emission signals» Акустический журнал, 63, № 3, с. 359-367 (2017)

An acoustic emission (AE) testing of rock cracking was performed under uniaxial loading conditions by precut varisized circular holes in selected brittle granites. Based on AE-source location technique and AE-theory for moment tensor analysis, rules of the temporal–spatial evolution of micro-cracks in different failure mechanisms were explored and types of micro-cracks were analyzed as well. The results revealed that the micro-cracks are uniquely easy to generate in the positions where stress are concentrated. Tensile fractures are easy to form on the roof and floor of a circular hole, while shear fractures are easy to be found on both sides. The locations of initial cracks generated around the holes in the loading process are the direction or vertical direction of maximum principle stress. Macroscopic crack orientation agrees with the direction of maximum principle stress approximately. As the size of circular opening increases and the relative size of pillar decreases, shear cracks are dominant with the percentage more than 45%, tension cracks are fewer, accounted for less than 40% of the total events, and mixed-mode cracks represent a minimum proportion, despite the decrease of percentage of shear cracks. The findings of this work can serve for supporting design of tunnel or roadway to avoid collapse.

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.

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.

Li J., Liu C.J., Zhang W.J. «Pressure potential and stability analysis in an acoustical noncontact transportation» Акустический журнал, 63, № 1, с. pp. 125-131 (2017)

Near field acoustic traveling wave is one of the most popular principles in noncontact manipulations and transportations. The stability behavior is a key factor in the industrial applications of acoustical noncontact transportation. We present here an in-depth analysis of the transportation stability of a planar object levitated in near field acoustic traveling waves. To more accurately describe the pressure distributions on the radiation surface, a 3D nonlinear traveling wave model is presented. A closed form solution is derived based on the pressure potential to quantitatively calculate the restoring forces and moments under small disturbances. The physical explanations of the effects of fluid inertia and the effects of non-uniform pressure distributions are provided in detail. It is found that a vibration rail with tapered cross section provides more stable transportation than a rail with rectangular cross section. The present study sheds light on the issue of quantitative evaluation of stability in acoustic traveling waves and proposes three main factors that influence the stability: (a) vibration shape, (b) pressure distribution and (c) restoring force/moment. It helps to provide a better understanding of the physics behind the near field acoustic transportation and provide useful design and optimization tools for industrial applications.

Zou Ming-Song, Wu You-Sheng, Liu Jian-De, Liu Shu-Xiao «A Mixed Analytical-Numerical Method for the Vibro-Acoustic Analysis of an Underwater Ring-Stiffened Cylindrical Shell Containing Substructures» Акустический журнал, 64, № 5, с. pp. 596-604 (2018)

A new sono-elastic substructure method is proposed in this paper to improve the computational efficiency of the hull-substructure coupled and fluid-structure interacted vibration and acoustic radiation of a submerged cylindrical-shell-type vehicle. The typical part of the vehicle structure is divided into the main hull and the internal substructures. The fluid-structure interaction problem of the main hull is solved by an analytical method based on the simplified model of a single-hull ring-stiffened cylindrical shell simply supported at both ends. Meanwhile, the substructures are numerically modeled through the Finite Element Method, with the condensed dynamic stiffness matrices of them obtained via the Superelement Method of Modal Synthesis. The main hull and the internal substructures are then integrated according to the boundary compatibility conditions at the connecting parts. Thus, a Mixed Analytical-Numerical Substructure (MANS) method is formulated. The applicability of this method is validated by two numerical examples as well as the test results of a large-scale submerged structural model. It is shown that the MANS method is suitable for the prediction of vibration and acoustic radiation of typical cylindrical-shell-type submerged structures in the medium frequency region.

Xu Shi-da, Li Yuan-hui, Liu Jian-po «Detection of cracking and damage mechanisms in brittle granites by moment tensor analysis of acoustic emission signals» Акустический журнал, 63, № 3, с. 359-367 (2017)

An acoustic emission (AE) testing of rock cracking was performed under uniaxial loading conditions by precut varisized circular holes in selected brittle granites. Based on AE-source location technique and AE-theory for moment tensor analysis, rules of the temporal–spatial evolution of micro-cracks in different failure mechanisms were explored and types of micro-cracks were analyzed as well. The results revealed that the micro-cracks are uniquely easy to generate in the positions where stress are concentrated. Tensile fractures are easy to form on the roof and floor of a circular hole, while shear fractures are easy to be found on both sides. The locations of initial cracks generated around the holes in the loading process are the direction or vertical direction of maximum principle stress. Macroscopic crack orientation agrees with the direction of maximum principle stress approximately. As the size of circular opening increases and the relative size of pillar decreases, shear cracks are dominant with the percentage more than 45%, tension cracks are fewer, accounted for less than 40% of the total events, and mixed-mode cracks represent a minimum proportion, despite the decrease of percentage of shear cracks. The findings of this work can serve for supporting design of tunnel or roadway to avoid collapse.

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.

Zou Ming-Song, Wu You-Sheng, Liu Jian-De, Liu Shu-Xiao «A Mixed Analytical-Numerical Method for the Vibro-Acoustic Analysis of an Underwater Ring-Stiffened Cylindrical Shell Containing Substructures» Акустический журнал, 64, № 5, с. pp. 596-604 (2018)

A new sono-elastic substructure method is proposed in this paper to improve the computational efficiency of the hull-substructure coupled and fluid-structure interacted vibration and acoustic radiation of a submerged cylindrical-shell-type vehicle. The typical part of the vehicle structure is divided into the main hull and the internal substructures. The fluid-structure interaction problem of the main hull is solved by an analytical method based on the simplified model of a single-hull ring-stiffened cylindrical shell simply supported at both ends. Meanwhile, the substructures are numerically modeled through the Finite Element Method, with the condensed dynamic stiffness matrices of them obtained via the Superelement Method of Modal Synthesis. The main hull and the internal substructures are then integrated according to the boundary compatibility conditions at the connecting parts. Thus, a Mixed Analytical-Numerical Substructure (MANS) method is formulated. The applicability of this method is validated by two numerical examples as well as the test results of a large-scale submerged structural model. It is shown that the MANS method is suitable for the prediction of vibration and acoustic radiation of typical cylindrical-shell-type submerged structures in the medium frequency region.

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.

Sun Fei, Guo Shuwei, Li Borui, Liu Yichao, He Sailing «An Acoustic Metamaterial Lens for Acoustic Point-to-Point Communication in Air» Акустический журнал, 65, № 1, с. pp. 1-6 (2019)

Acoustic metamaterials have become a novel and effective way to control sound waves and design acoustic devices. In this study, we design a 3D acoustic metamaterial lens (AML) to achieve point-to-point acoustic communication in air: any acoustic source (a speaker) in air enclosed by such an AML can produce an acoustic image where the acoustic wave is focused (the field intensity is at a maximum, and the listener can receive the information), while the acoustic field at other spatial positions is low enough that listeners can hear almost nothing. Unlike a conventional elliptical reflective mirror, the acoustic source can be moved around inside our proposed AML. Numerical simulations are given to verify the performance of the proposed AML.

Ma Huayuan, Long Yuan, Zhong Mingshou, Li Xinghua, Xie Quanmin «Study on Ground Vibration Mode of Physical Explosion of High Pressure Natural Gas Pipeline» Акустический журнал, 65, № 5, с. pp. 583-592 (2019)

In this paper, an explosion experiment was carried out on the OD1219mm-X90-12Mpa natural gas pipeline to study the vibration hazard. Based on a series of experiments, the spatial distribution of the vibration energy was studied. The vibration distribution field was drawn by interpolation method based on re-harmonic equation and it was found that the field was non-circular symmetry. Through in-depth research, it was preliminarily proved that the vibration field had interference characteristics, which was caused by the special vibration source of the pipeline explosion. There was a significant difference in the frequency components between the interference strengthened region and the weakened region. The results shown that the strengthening effect of the interference in the 90° and 30° direction should be taken into account when evaluating the damage scope of the explosion accident. Research provided reference for safety design of parallel pipelines and buildings.

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.

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.

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.