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1
Norris, Andrew, Alexey S. Titovich et Michael Haberman. « Acoustic wave control with cylindrical metamaterial elements in water ». Journal of the Acoustical Society of America 138, no 3 (septembre 2015) : 1733. http://dx.doi.org/10.1121/1.4933459.
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SISOMBAT, Félix, Thibaut DEVAUX, Samuel CALLé et Lionel HAUMESSER. « Acoustic reflector remotely tunable by the acoustic radiation force ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 270, no 4 (4 octobre 2024) : 7893–98. http://dx.doi.org/10.3397/in_2024_4019.
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Specifically structured surface can be used to control acoustic waves reflection enabling wavefront shaping tailored for desired applications such as imaging or cloaking. With the development of metasurfaces, which enable changing the reflection of an incident acoustic wave at an interface using a sub-wavelength structure, it is possible to explore new frontiers of Snell-Descartes laws. However, the control over wave propagation is pre-established when using fixed structures, directing research towards metasurfaces reconfigurable in both time and space. This work proposes a metamaterial architecture using deformations of a fluid interface between two media through the acoustic radiation pressure (ARP). An analytical and numerical study is conducted to assess the phase shift on airborne acoustic wave induced by a unit cell featuring a Helmholtz resonator tuned by the water surface elevation induced by ARP. The possibility to program in real-time the phase shift is successfully tested experimentally for an incident wave of frequency 3400 Hz. The extension to a metasurface is introduced through the juxtaposition of 15 unit cell. A retroreflection effect is then numerically demonstrated, highlighting the effectiveness of the proposed approach. This concept of real-time and non-contact reconfigurable metasurface opens new possibilities for beam deflection, acoustic holography or information encoding.
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He, Jiahuan, Wei Zhang, Dan Zhao, Nong Li, Qiang Kang, Kunpeng Cai, Li Wang et al. « Numerical Simulation Analysis of Control Factors on Acoustic Velocity in Carbonate Reservoirs ». Minerals 14, no 4 (19 avril 2024) : 421. http://dx.doi.org/10.3390/min14040421.
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The conventional Archie formula struggles with the interpretation of water saturation from resistivity well log data due to the increasing complexity of exploration targets. This challenge has prompted researchers to explore alternative physical parameters, such as acoustic characteristics, for breakthroughs. Clarifying the influencing factors of porous media acoustic characteristics is one of the most important approaches to help understanding the mechanism of acoustic characteristics of carbonate reservoirs. The article uses digital rock technology to characterize the pore structure, quantitatively identify fractures and pore structures in carbonate rocks, and establish digital models. Through conventional acoustic testing, the pressure wave (P-wave) and shear wave (S-wave) velocities of rock samples at different water saturations are obtained, and the dynamic elastic modulus is calculated. A finite element calculation model is established using the digital rock computational model to provide a basis for fluid saturation calculation methods. Based on real digital rock models, different combinations of virtual fractures are constructed, and factors affecting acoustic parameters are analyzed. The study finds that as porosity increases, the velocity difference between porous cores and fractured cores also increases. These findings provide important technical support and a theoretical basis for interpreting acoustic well logging data and evaluating carbonate reservoirs with different pore and fracture types.
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Kos̆tial, Pavol. « Surface acoustic wave control of the ion concentration in water ». Applied Acoustics 41, no 2 (1994) : 187–93. http://dx.doi.org/10.1016/0003-682x(94)90068-x.
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Kozaczka, Eugeniusz, Jacek Domagalski, Grażyna Grelowska et Ignacy Gloza. « Identification of hydro-acoustic waves emitted from floating units during mooring tests ». Polish Maritime Research 14, no 4 (1 octobre 2007) : 40–46. http://dx.doi.org/10.2478/v10012-007-0038-5.
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Identification of hydro-acoustic waves emitted from floating units during mooring tests Measurements of hydro-acoustic noise emitted from vessels are a.o. a subject of the tests carried out in the control measurement ranges of the Navy. The measurements are performed both on anchored and floating vessels. Acoustic field of vessels is changing along with their speed changing and is associated with acoustic activity of wave sources installed in vessel's hull (main engines, electric generating sets, reduction gears, pumps, shaft-lines, piping, ventilating ducts etc) as well as hydro-dynamic sources such as screw propellers and water flow around the hull [5, 7]. Vibration energy generated by the onboard devices is transferred through ship structural elements to water where it propagates in the form of hydro-acoustic waves of a wide frequency band.
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Anisimkin, Vladimir, Vladimir Kolesov, Anastasia Kuznetsova, Elizaveta Shamsutdinova et Iren Kuznetsova. « An Analysis of the Water-to-Ice Phase Transition Using Acoustic Plate Waves ». Sensors 21, no 3 (29 janvier 2021) : 919. http://dx.doi.org/10.3390/s21030919.
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It is shown that, in spite of the wave radiation into the adjacent liquid, a large group of Lamb waves are able to propagate along piezoelectric plates (quartz, LiNbO3, LiTaO3) coated with a liquid layer (distilled water H2O). When the layer freezes, most of the group’s waves increase their losses, essentially forming an acoustic response towards water-to-ice transformation. Partial contributions to the responses originating from wave propagation, electro-mechanical transduction, and wave scattering were estimated and compared with the coupling constants, and the vertical displacements of the waves were calculated numerically at the water–plate and ice–plate interfaces. The maximum values of the responses (20–30 dB at 10–100 MHz) are attributed to the total water-to-ice transformation. Time variations in the responses at intermediate temperatures were interpreted in terms of a two-phase system containing both water and ice simultaneously. The results of the paper may turn out to be useful for some applications where the control of ice formation is an important problem (aircraft wings, ship bodies, car roads, etc.).
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Li, Qi, Ke Wu et Mingquan Zhang. « Two-Dimensional Composite Acoustic Metamaterials of Rectangular Unit Cell from Pentamode to Band Gap ». Crystals 11, no 12 (25 novembre 2021) : 1457. http://dx.doi.org/10.3390/cryst11121457.
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Pentamode metamaterials have been receiving an increasing amount of interest due to their water-like properties. In this paper, a two-dimensional composite pentamode metamaterial of rectangular unit cell is proposed. The unit cells can be classified into two groups, one with uniform arms and the other with non-uniform arms. Phononic band structures of the unit cells were calculated to derive their properties. The unit cells can be pentamode metamaterials that permit acoustic wave travelling or have a total band gap that impedes acoustic wave propagation by varying the structures. The influences of geometric parameters and materials of the composed elements on the effective velocities and anisotropy were analyzed. The metamaterials can be used for acoustic wave control under water. Simulations of materials with different unit cells were conducted to verify the calculated properties of the unit cells. The research provides theoretical support for applications of the pentamode metamaterials.
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Knight, Rosemary, Jack Dvorkin et Amos Nur. « Acoustic signatures of partial saturation ». GEOPHYSICS 63, no 1 (janvier 1998) : 132–38. http://dx.doi.org/10.1190/1.1444305.
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The relationship between elastic wave velocities and water saturation in a water/gas reservoir depends strongly on whether saturation is heterogeneous (patchy) or homogeneous. Heterogeneity in saturation may result from lithologic heterogeneity because under conditions of capillary equilibrium, different lithologies within a reservoir can have different saturations, depending on their porosities and permeabilities. We investigate this phenomenon by generating models of a reservoir in which we control the distribution of lithologic units and theoretically determine the corresponding velocity‐saturation relationship. We assume a state of capillary equilibrium in the reservoir and determine the saturation level of each region within the reservoir from the corresponding capillary pressure curve for the lithologic unit at that location. The velocities we calculate for these models show that saturation heterogeneity, caused by lithologic variation, can lead to a distinct dependence of velocity on saturation. In a water‐gas saturated reservoir, a patchy distribution of the different lithologic units is found to cause P-wave velocity to exhibit a noticeable and almost continuous velocity variation across the entire saturation range. This is in distinct contrast to the response of a homogeneous reservoir where there is only a large change in velocity at water saturations close to 100%.
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Memon, Maria Muzamil, Qiong Liu, Ali Manthar, Tao Wang et Wanli Zhang. « Surface Acoustic Wave Humidity Sensor : A Review ». Micromachines 14, no 5 (27 avril 2023) : 945. http://dx.doi.org/10.3390/mi14050945.
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The Growing demands for humidity detection in commercial and industrial applications led to the rapid development of humidity sensors based on different techniques. Surface acoustic wave (SAW) technology is one of these methods that has been found to provide a powerful platform for humidity sensing owing to its intrinsic features, including small size, high sensitivity, and simple operational mechanism. Similar to other techniques, the principle of humidity sensing in SAW devices is also realized by an overlaid sensitive film, which serves as the core element whose interaction with water molecules is responsible for overall performance. Therefore, most researchers are focused on exploring different sensing materials to achieve optimum performance characteristics. This article reviews sensing materials used to develop SAW humidity sensors and their responses based on theoretical aspects and experimental outcomes. Herein the influence of overlaid sensing film on the performance parameters of the SAW device, such as quality factor, signal amplitude, insertion loss, etc., is also highlighted. Lastly, a recommendation to minimize the significant change in device characteristics is presented, which we believe will be a good step for the future development of SAW humidity sensors.
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M’zoughi, Fares, Izaskun Garrido, Aitor J. Garrido et Manuel De La Sen. « Rotational Speed Control Using ANN-Based MPPT for OWC Based on Surface Elevation Measurements ». Applied Sciences 10, no 24 (16 décembre 2020) : 8975. http://dx.doi.org/10.3390/app10248975.
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This paper presents an ANN-based rotational speed control to avoid the stalling behavior in Oscillating Water Columns composed of a Doubly Fed Induction Generator driven by a Wells turbine. This control strategy uses rotational speed reference provided by an ANN-based Maximum Power Point Tracking. The ANN-based MPPT predicts the optimal rotational speed reference from wave amplitude and period. The neural network has been trained and uses wave surface elevation measurements gathered by an acoustic Doppler current profiler. The implemented ANN-based rotational speed control has been tested with two different wave conditions and results prove the effectiveness of avoiding the stall effect which improved the power generation.
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Xue, Xufeng, Baile Cui, Xianping Chen, Wen Wang, Mingchen Sun et Yong Liang. « Thermal Stress Analysis and Control Method for Surface Acoustic Wave Atomizer ». Sensors 23, no 21 (26 octobre 2023) : 8748. http://dx.doi.org/10.3390/s23218748.
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To prevent the potential failure of the surface acoustic wave (SAW) atomizer caused by the concentration of thermal stresses, this study investigates the thermal elevation process inherent to the operation of the surface wave atomizer. Subsequently, a method for temperature regulation is proposed. By collecting the temperature rise data of SAW atomizers with water, olive oil, and glycerol at 5/6/7 Watts (W) of power, the temperature curves of the atomizer surface under different conditions are obtained, and the stress changes in the working process are simulated additionally. The results indicate that although the stress generated by surface acoustic wave atomizers varies for different media, there is always a problem of rapid heating during the initial working stage in all cases. To address the above issues, this study analyzed the time when the maximum stress occurred and proposed control methods based on experimental data. The simulation results show that by controlling the driving power within 4 s after the start of atomization, the problem of excessive stress during the heating stage can be avoided. Finally, the feasibility of the control method was verified through a simple power control method (limiting the driving power to 3 W in the first 2 s), proving that this method can effectively reduce the thermal stress during the working process of the atomizer and prevent the atomizer from cracking.
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Pouya, C., K. Hoggard, S. H. Gossage, H. R. Peter, T. Poole et G. R. Nash. « Frequency dependence of surface acoustic wave swimming ». Journal of The Royal Society Interface 16, no 155 (juin 2019) : 20190113. http://dx.doi.org/10.1098/rsif.2019.0113.
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Surface acoustic waves (SAWs) are elastic waves that can be excited directly on the surface of piezoelectric crystals using a transducer, leading to their exploitation for numerous technological applications, including for example microfluidics. Recently, the concept of SAW streaming, which underpins SAW microfluidics, was extended to make the first experimental demonstration of ‘SAW swimming’, where instead of moving water droplets on the surface of a device, SAWs are used as a propulsion mechanism. Using theoretical analysis and experiments, we show that the SAW swimming force can be controlled directly by changing the SAW frequency, due to attenuation and changing force distributions within each SAW streaming jet. Additionally, an optimum frequency exists which generates a maximum SAW swimming force. The SAW frequency can therefore be used to control the efficiency and forward force of these SAW swimming devices. The SAW swimming propulsion mechanism also mimics that used by many microorganisms, where propulsion is produced by a cyclic distortion of the body shape. This improved understanding of SAW swimming provides a test-bed for exploring the science of microorganism swimming, and could bring new insight to the evolutionary significance for the length and beating frequency of swimming microbial flagella.
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Bu, Qingtao, Tongju Xing, Chengfeng Li, Jinhuan Zhao, Changling Liu, Zihao Wang, Wengao Zhao, Jiale Kang, Qingguo Meng et Gaowei Hu. « Effect of Hydrate Microscopic Distribution on Acoustic Characteristics during Hydrate Dissociation : An Insight from Combined Acoustic-CT Detection Study ». Journal of Marine Science and Engineering 10, no 8 (9 août 2022) : 1089. http://dx.doi.org/10.3390/jmse10081089.
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Geophysical detection techniques are important methods in marine gas hydrate exploration and monitoring, because the small-scale distribution of hydrates has a large impact on the wave velocity. The acoustic response characteristics of hydrate micro-distributions have strong significance for monitoring the hydrate dissociation process. In this paper, experiments simulating the hydrate dissociation process were carried out in a self-developed experimental device combining X-ray computed tomography (X-CT) scanning and ultrasonic detection, which allowed the acoustic wave characteristics and X-CT scanning results to be simultaneously obtained during the hydrate dissociation process. This study found that the hydrate dissociation stage is divided into three stages. The hydrate begins to dissociate at spots where it comes into touch with sand particles early in the dissociation process. The main factor affecting the acoustic wave velocity of hydrates in this stage is changes in the microscopic distribution of hydrate. In the middle stage, a large amount of hydrate decomposes, and the main factor affecting the acoustic wave velocity of hydrate in this stage is the change in hydrate content. In the later stage of hydrate dissociation, the hydrate distribution pattern consists mainly of the pore-filling type, and the hydrate micro-distribution at this stage is the main factor affecting the acoustic wave velocity. This study will be of great significance for understanding the microscopic control mechanism of hydrate reservoir geophysical exploration.
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Xiao, Yan, et Xuesong Zhang. « Method for Establishing a Traveling Wave Sound Field with Adaptive Control in a Water-Filled Sound Tube ». Applied Sciences 11, no 13 (22 juin 2021) : 5785. http://dx.doi.org/10.3390/app11135785.
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The transfer function method is a common method for establishing a traveling wave field in a sound tube to measure the reflection and transmission coefficient of underwater material. The voltage applied to the secondary sound source can be calculated in accordance with the transfer matrix between the sound sources and hydrophones, then a traveling wave field can be established in the sound tube. However, the transfer function must be remeasured when the measurement frequency needs to be changed. A checking procedure of the traveling wave field in the sound tube is essential before measuring underwater acoustic material. If it is not an accurate traveling wave field, the secondary sound source signal should be corrected until the traveling wave field meets the requirements. To address these problems, an adaptive control method for generating plane traveling waves is proposed. The phase difference of sound pressures measured using the two hydrophones between the secondary sound source and the sample is used as the objective function in the adaptive algorithm, and the amplitude and phase of the secondary sound source can be obtained using the adaptive control system in the frequency domain. When a traveling wave field is formed, the reflection and transmission coefficient of the sample can be measured at the same time. With this method, the procedure of testing the traveling wave field is omitted. If the state of the primary sound source changes, the signal form of the secondary sound source can be changed immediately. Therefore, the efficiency of material measurement is improved. Theoretically, this method can obtain the most matching signal form of the secondary sound source, such that the accuracy of this method is remarkably high. Simulation and experimental results in this paper show that the measurement accuracy is reliable within the frequency range of 100–2500 Hz.
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Zhu, Ping. « The Microfluid-Driven Control by Forced Wave ». Key Engineering Materials 503 (février 2012) : 341–47. http://dx.doi.org/10.4028/www.scientific.net/kem.503.341.
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The commutation of pressure, electro-osmosis and acoustic methods is usually adopted to realize the drive of microfluid in microsystem. However, the above methods do not have a very ideal controllability. In view of the above situation, the paper proposes a kind of microfluid-driven method according to physical mechanism of wave-vortex interaction. In the method the microfluid-driven control is realized sympathetic vibration between forced wave and unstable wave in the vortex layer to intensify or destroy nonlinear stability of vortex or to regulate quasi-vortex energy flow in the boundary layer, in which the forced wave is produced by applying tangential simple harmonic motion with specific frequency and amplitude to the outside of flowing passage or flowing body. The paper demonstrates the method theoretically, and then uses an experiment to prove its availability. By using de-ionized water, straight round glass with the diameter of Φ18~Φ20μm, the experiment of separation is carried out successfully. The method has very broad applying prospect for the activity retention in the process of cell injection and transfer in the biomedical field and the fuel transfer in the micro propeller.
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Wang, Su, Yifan Shao, Jinsheng Duan, Huaidong He et Qingqing Xiao. « Effects of Sound Wave and Water Management on Growth and Cd Accumulation by Water Spinach (Ipomoea aquatica Forsk.) ». Agronomy 12, no 10 (21 septembre 2022) : 2257. http://dx.doi.org/10.3390/agronomy12102257.
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Vegetable contamination by cadmium (Cd) is of great concern. Water spinach (Ipomoea aquatica) is a common leafy vegetable in many countries and has a strong ability to accumulate Cd. The work was conducted to study the effects of sound wave, water management, and their combination on Cd accumulation and growth of water spinach, using the following three experiments: a hydroponic trial with the treatment of a plant acoustic frequency technology (PAFT) generator in test sheds, a hydroponic trial with three music treatments (electronic music (EM), rock music (RM), and classical music (CM)) in artificial climate boxes, and a soil pot trial with treatments of PAFT and EM under non-flooded and flooded conditions. The results showed that the hydroponic treatments of PAFT and EM significantly reduced the Cd concentrations in roots and shoots (edible parts) of water spinach by 22.01–36.50% compared with the control, possibly due to sound waves decreasing the root tip number per unit area and increasing average root diameter, root surface area, and total root length. Sound wave treatments clearly enhanced water spinach biomass by 28.27–38.32% in the hydroponic experiments. In the soil experiment, the flooded treatment significantly reduced the Cd concentrations in roots and shoots by 43.75–63.75%, compared with the non-flooded treatment. The Cd decrease and the biomass increase were further driven by the PAFT supplement under the flooding condition, likely related to the alteration in root porosity, rates of radial oxygen loss, extractable soil Cd, soil Eh, and soil pH. Our results indicate that the co-application of plant acoustic frequency technology and flooded management may be an effective approach to reduce Cd accumulation in water spinach.
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Zhang, Naiqing, Yue Wen et James Friend. « MHz-Order Surface Acoustic Wave Thruster for Underwater Silent Propulsion ». Micromachines 11, no 4 (16 avril 2020) : 419. http://dx.doi.org/10.3390/mi11040419.
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High frequency (MHz-order) surface acoustic waves (SAW) are able to generate intense fluid flow from the attenuation of acoustic radiation in viscous fluids as acoustic streaming. Though such flows are known to produce a force upon the fluid and an equivalent and opposing force upon the object producing the acoustic radiation, there is no convenient method for measuring this force. We describe a new method to accomplish this aim, noting the potential of these devices in providing essentially silent underwater propulsion by virtue of their use of the sound itself to generate fluid momentum flux. Our example employs a 40 MHz SAW device as a pendulum bob while immersed in a fluid, measuring a 1.5 mN propulsion force from an input power of 5 W power to the SAW device. Supporting details regarding the acoustic streaming profile via particle image velocimetry and an associated theoretical model are provided to aid in the determination of the propulsion force knowing the applied power and fluid characteristics. Finally, a simple model is provided to aid the selection of the acoustic device size to maximize the propulsion force per unit device area, a key figure of merit in underwater propulsion devices. Using this model, a maximum force of approximately 10 mN/cm 2 was obtained from 1 W input power using 40 MHz SAW in water and producing a power efficiency of approximately 50%. Given the advantages of this technology in silent propulsion with such large efficiency and propulsion force per unit volume, it seems likely this method will be beneficial in propelling small autonomous submersibles.
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Manikandan, M., et A. Rajiv Kannan. « Provisioning Intelligent Water Wave Optimization Approach for Underwater Acoustic Wireless Sensor Networks ». Computer Systems Science and Engineering 43, no 2 (2022) : 625–41. http://dx.doi.org/10.32604/csse.2022.022662.
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Nazarchuk, Z. T., T. I. Voronyak, O. G. Kuts, I. V. Stasyshyn et I. B. Ivasenko. « Using of acoustic resonance for detection and identification of hidden defects in polymer layered composites ». Information extraction and processing 2022, no 50 (19 décembre 2022) : 46–53. http://dx.doi.org/10.15407/vidbir2022.50.046.
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A method of non-destructive testing is proposed, which combines the acoustic load of the object of inspection and interferometric control of its surface displacements, formed as a result of an acoustic wave resonance in a hidden defect. The method is aimed at solving the problem of detection and identification of subsurface defects formed in structural elements made of polymer layered composite materials or contain protective paint coatings. At the same time, the defect is considered as an acoustic resonator filled with a medium in which only a longitudinal acoustic wave propagates. Usually such media are air or water. The novelty of the method is that it allows us not only to detect a hidden defect and establish its location, but also to determi¬ne its dimensions. The scheme of the experimental installation is given and the method is described. The research of the detection and identification of subsurface defects that most often occur in practice was conducted with the help of the model of the experimental installation. In products made of polymer layered composites, such defects are unbounded areas between layers during construction, internal damages such as cracks and areas of crumpling during its operation. The results of the experiments proved the effectiveness of the proposed method. The described method is also suitable for detection and identification of blistering of protective paint coatings, provided that they are filled with liquids or gases in which transverse acoustic waves do not propagate.
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Sun, Fei, Tingfeng Ma, Pengfei Kang, Yuming Yao, Ning Gan, Lili Yuan, Wenhui Hu, Iren Kuznetsova et Ilya Nedospasov. « Pure- and Pseudo-Lateral-Field-Excitation Characteristics of Relaxor Ferroelectric Single Crystal PMN-PT ». Micromachines 14, no 6 (28 mai 2023) : 1136. http://dx.doi.org/10.3390/mi14061136.
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The relaxor ferroelectric single crystal (1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) has high piezoelectric constants, and thus has a good application prospect in the field of highly sensitive piezoelectric sensors. In this paper, for relaxor ferroelectric single crystal PMN-PT, the bulk acoustic wave characteristics on pure- and pseudo-lateral-field-excitation (pure- and pseudo-LFE) modes are investigated. LFE piezoelectric coupling coefficients and acoustic wave phase velocities for PMN-PT crystals in different cuts and electric field directions are calculated. On this basis, the optimal cuts of pure-LFE and pseudo-LFE modes of relaxor ferroelectric single crystal PMN-PT are obtained, namely, (zxt)45° and (zxtl)90°/90°, respectively. Finally, finite element simulations are carried out to verify the cuts of pure-LFE and pseudo-LFE modes. The simulation results show that the PMN-PT acoustic wave devices in pure-LFE mode have good energy-trapping effects. For PMN-PT acoustic wave devices in pseudo-LFE mode, when the device is in air, no obvious energy-trapping emerges; when the water (as a virtual electrode) is added to the surface of the crystal plate, an obvious resonance peak and the energy-trapping effect appears. Therefore, the PMN-PT pure-LFE device is suitable for gas-phase detections. While the PMN-PT pseudo-LFE device is suitable for liquid-phase detections. The above results verify the correctness of the cuts of the two modes. The research results provide an important basis for the development of highly sensitive LFE piezoelectric sensors based on relaxor ferroelectric single crystal PMN-PT.
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Liu, Tao, Jian Gan Wang et Si Guang Zong. « Experimental Investigation on Underwater Opto-Acoustic Communication ». Applied Mechanics and Materials 143-144 (décembre 2011) : 653–57. http://dx.doi.org/10.4028/www.scientific.net/amm.143-144.653.
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The underwater opto-acoustic communication system for directional acoustic communication between an in-air platform and a submerged platform operating is important. The paper presents a new method to solve this problem with opto-acoustic technology, which combines high-energy laser, the opto-acoustic transmitter that optical energy is converted to acoustic energy at the water surface. The laser-based transmitter provides a versatile method for generating underwater sound. The acoustic pressure is linearly proportional to the laser power. The paper designed an experimental measurement system for the opto-acoustic communication. It made experiments for study on the waveform and spectrum characteristics of opto-acoustic signals. The paper also discuss the acoustic wave after optical breakdown in water with Nd:YAG laser pulses. The opto-acoustic signals can controll by adjusting the laser's parameters. The conclusion is that the opto-acoustic communication has some technical advantages. This system presents a change in the way communicational from the air.
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Uzhansky, Ernst, Maya Friedlender et Izhak Bucher. « Optimizing parametric acoustic arrays for high-fidelity low-frequency signals ». Journal of the Acoustical Society of America 155, no 3_Supplement (1 mars 2024) : A344. http://dx.doi.org/10.1121/10.0027767.
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Parametric acoustic array (PAA) can leverage the nonlinear behavior of sound travelling through the nonlinear medium (e.g., air, water, human tissues) to generate low-frequency broadband high-directivity sound due to the self-demodulation of finite-amplitude modulated ultrasonic waves. However, while propagating, self-demodulated signals (hereon message) interact one with another, leading to message deformation and increase of the total harmonic distortion (THD). This makes it problematic to use powerful PAA to control complex low-frequency signals. This work explores a method for reducing THD by optimizing the input signal using various digital signal processing algorithms. The sustainability of the required spectral components with distance and the spatial boundaries of the operation of the proposed optimization algorithm are also investigated experimentally with a 520-channel hexagonal PAA and numerically. The simulations were done via k-wave acoustic toolbox considering nonlinearities and power law absorption.
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Hasheminejad, S. M., et H. Hosseini. « Radiation Loading of a Cylindrical Source in a Fluid-Filled Cylindrical Cavity Embedded Within a Fluid-Saturated Poroelastic Medium ». Journal of Applied Mechanics 69, no 5 (16 août 2002) : 675–83. http://dx.doi.org/10.1115/1.1488664.
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Radiation loading on a vibrating structure is best described through its radiation impedance. In the present work the modal acoustic radiation impedance load on an infinitely long cylindrical source harmonically excited in circumferentially periodic (axially independent) spatial pattern, while positioned concentrically within a fluid cylinder, which is embedded in a fluid-saturated unbounded elastic porous medium, is computed. This configuration, which is a realistic idealization of an acoustic logging tool suspended in a fluid-filled borehole within a permeable surrounding formation (White, J. E., 1983, Underground Sound Application of Seismic Waves, Elsevier, Amsterdam, Fig. 5.29, p. 183), is of practical importance with a multitude of possible applications in seismo-acoustics and noise control engineering. The formulation utilizes the Biot phenomenological model to represent the behavior of the sound in the porous, fluid-saturated, macroscopically homogeneous and isotropic surrounding medium. Employing the appropriate wave-harmonic field expansions and the pertinent boundary conditions for the given boundary configuration, a closed-form solution in the form of an infinite series is developed and the resistive and reactive components of modal radiation impedances are determined. A numerical example for a cylindrical surface excited in vibrational modes of various order, immersed in a water-filled cavity which is embedded within a water-saturated Ridgefield sandstone environment, is presented and several limiting cases are examined. Effects of porosity, frame stiffness, source size, and the interface permeability condition on the impedance values are presented and discussed.
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Wang, Xiao-Hui, Qiang Xu, Ya-Nan He, Yun-Fei Wang, Yi-Fei Sun, Chang-Yu Sun et Guang-Jin Chen. « The Acoustic Properties of Sandy and Clayey Hydrate-Bearing Sediments ». Energies 12, no 10 (14 mai 2019) : 1825. http://dx.doi.org/10.3390/en12101825.
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Natural gas hydrates samples are rare and difficult to store and transport at in situ pressure and temperature conditions, resulting in difficulty to characterize natural hydrate-bearing sediments and to identify hydrate accumulation position and saturation at the field scale. A new apparatus was designed to study the acoustic properties of seafloor recovered cores with and without hydrate. To protect the natural frames of recovered cores and control hydrate distribution, the addition of water into cores was performed by injecting water vapor. The results show that hydrate saturation and types of host sediments are the two most important factors that govern the elastic properties of hydrate-bearing sediments. When gas hydrate saturation adds approximately to 5–25%, the corresponding P-wave velocity (Vp) increases from 1.94 to 3.93 km/s and S-wave velocity (Vs) increases from 1.14 to 2.23 km/s for sandy specimens; Vp and Vs for clayey samples are 1.72–2.13 km/s and 1.10–1.32 km/s, respectively. The acoustic properties of sandy sediments can be significantly changed by the formation/dissociation of gas hydrate, while these only minorly change for clayey specimens.
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Li, Dekang, Xin Wang, Tian Li, Luying Yang, Yuhong Liu, Fei Wang, Yuwei Xu et Yang Yang. « Research Progress on the Impact of Acoustic Waves on the Agglomeration of Oily Fine Particles in Industrial Oil Mist Environment ». Buildings 13, no 8 (29 juillet 2023) : 1937. http://dx.doi.org/10.3390/buildings13081937.
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Currently, undetectable damage to workers and factory products is caused by the large number of oily fine particles present in the industrial environment. Previous studies have shown that different intensities of sound waves can promote the coalescence of fine particles, and the combination of water vapor condensation can further enhance the effect of acoustic coalescence. However, the research on acoustic coalescence is not extensive enough at present, especially research on the mechanism of the coalescence and growth of oily fine particles under acoustic and water vapor complex fields, which is even less studied. This paper focused on summarizing domestic and foreign research results on the interaction mechanism of acoustic convergence on particles and the agglomeration and growth of particles under the action of acoustic convergence and combined water vapor condensation, so as to explore the technical path of using acoustic convergence and combined water vapor condensation to regulate the size of oily fine particles and improve the purification efficiency in industrial situations. This research has significant scientific significance and application value for industrial environmental control, pollutant emission control, and healthy environment construction.
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Cao, Hiep Xuan, Daewon Jung, Han-Sol Lee, Gwangjun Go, Minghui Nan, Eunpyo Choi, Chang-Sei Kim, Jong-Oh Park et Byungjeon Kang. « Micromotor Manipulation Using Ultrasonic Active Traveling Waves ». Micromachines 12, no 2 (13 février 2021) : 192. http://dx.doi.org/10.3390/mi12020192.
Texte intégralRésumé :
The ability to manipulate therapeutic agents in fluids is of interest to improve the efficiency of targeted drug delivery. Ultrasonic manipulation has great potential in the field of therapeutic applications as it can trap and manipulate micro-scale objects. Recently, several methods of ultrasonic manipulation have been studied through standing wave, traveling wave, and acoustic streaming. Among them, the traveling wave based ultrasonic manipulation is showing more advantage for in vivo environments. In this paper, we present a novel ultrasonic transducer (UT) array with a hemispherical arrangement that generates active traveling waves with phase modulation to manipulate a micromotor in water. The feasibility of the method could be demonstrated by in vitro and ex vivo experiments conducted using a UT array with 16 transducers operating at 1 MHz. The phase of each transducer was controlled independently for generating a twin trap and manipulation of a micromotor in 3D space. This study shows that the ultrasonic manipulation device using active traveling waves is a versatile tool that can be used for precise manipulation of a micromotor inserted in a human body and targeted for drug delivery.
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A, Rajeswari, Duraipandian N, Shanker NR et Betty Elezebeth Samuel. « Improving Packet Delivery Performance in Water Column Variations through LOCAN in Underwater Acoustic Sensor Network ». Journal of Sensors 2020 (20 février 2020) : 1–16. http://dx.doi.org/10.1155/2020/7960654.
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This paper proposes Lion Optimized Cognitive Acoustic Network (LOCAN) to reduce packet delay and packet loss during packet transmission in Underwater Acoustic Sensor Network (UWASN). Packet delay and packet loss in UWASN are because of water column variations such as Doppler effect and geometric spreading (GS). Doppler effect forms due to sensor node’s motion and sea surface variations such as salinity and temperature. Geometric spreading (GS) occurs due to sediment drift wave fronts and frequent changes in node’s location and depth. Water column variations change the amplitude of sound propagation, causing channel coherence and multipath interference, which affect packet transmission. The existing UWASN algorithms focus only on temperature and salinity variations. In LOCAN, channel selection through Lion Optimization Algorithm solves the problems of water column variation and improves the battery life, network lifetime, and throughput. The proposed algorithms show a better result in terms of efficiency, when compared to existing UWASN algorithms.
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Bradley, Stuart, Anna Radionova, Chandra Ghimire, Laura Grundy, Seth Laurenson et Val Snow. « Irrigation Control through Acoustic Proximal Sensing of the Onset of Surface Water ». Remote Sensing 12, no 22 (19 novembre 2020) : 3800. http://dx.doi.org/10.3390/rs12223800.
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Irrigation is a useful crop enhancement procedure up to the point where free surface water appears. However, over-irrigation can lead to an accumulation of free water on the soil surface, which in turn results in overland flow and a high risk of contaminant loss. The current work addresses the problem of measuring free water on the surface of agricultural soils by a real-time acoustic remote sensing method. Directional acoustic transmitter and receiver arrays are used to define a “footprint” on the ground from which changes in reflectance are sensed. These arrays are mounted on a moving irrigator. Chirp signals are used to provide along-path resolution and to ensure robustness against unwanted acoustic background noise from farm machinery and the irrigator. Field measurements have been conducted above a well-defined “quadrat” with controlled and measured water content and also with the instrument mounted on an operational irrigator. A structured light camera mounted above the footprint is used to validate surface water fraction. It is found that the areal fraction of free water on the soil surface can be reliably estimated from changes in the amplitude of the reflected sound waves. The mechanism giving rise to the observed acoustic reflectivity changes is discussed and a model is developed which agrees with normalized intensity observations with a coefficient of determination R2 between 0.65 and 0.83. The rms error between model predictions and observations is comparable to the rms variation of the measurements, indicating that there is insignificant error due to the choice of model.
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JAMALUDDIN, A. R., G. J. BALL, C. K. TURANGAN et T. G. LEIGHTON. « The collapse of single bubbles and approximation of the far-field acoustic emissions for cavitation induced by shock wave lithotripsy ». Journal of Fluid Mechanics 677 (27 avril 2011) : 305–41. http://dx.doi.org/10.1017/jfm.2011.85.
Texte intégralRésumé :
Recent clinical trials have shown the efficacy of a passive acoustic device used during shock wave lithotripsy (SWL) treatment. The device uses the far-field acoustic emissions resulting from the interaction of the therapeutic shock waves with the tissue and kidney stone to diagnose the effectiveness of each shock in contributing to stone fragmentation. This paper details simulations that supported the development of that device by extending computational fluid dynamics (CFD) simulations of the flow and near-field pressures associated with shock-induced bubble collapse to allow estimation of those far-field acoustic emissions. This is a required stage in the development of the device, because current computational resources are not sufficient to simulate the far-field emissions to ranges of O(10 cm) using CFD. Similarly, they are insufficient to cover the duration of the entire cavitation event, and here simulate only the first part of the interaction of the bubble with the lithotripter shock wave in order to demonstrate the methods by which the far-field acoustic emissions resulting from the interaction can be estimated. A free-Lagrange method (FLM) is used to simulate the collapse of initially stable air bubbles in water as a result of their interaction with a planar lithotripter shock. To estimate the far-field acoustic emissions from the interaction, this paper developed two numerical codes using the Kirchhoff and Ffowcs William–Hawkings (FW-H) formulations. When coupled to the FLM code, they can be used to estimate the far-field acoustic emissions of cavitation events. The limitation of the technique is that it assumes that no significant nonlinear acoustic propagation occurs outside the control surface. Methods are outlined for ameliorating this problem if, as here, computational resources cannot compute the flow field to sufficient distance, although for the clinical situation discussed, this limitation is tempered by the effect of tissue absorption, which here is incorporated through the standard derating procedure. This approach allowed identification of the sources of, and explanation of trends seen in, the characteristics of the far-field emissions observed in clinic, to an extent that was sufficient for the development of this clinical device.
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Feddersen, Falk. « Quality Controlling Surf Zone Acoustic Doppler Velocimeter Observations to Estimate the Turbulent Dissipation Rate ». Journal of Atmospheric and Oceanic Technology 27, no 12 (1 décembre 2010) : 2039–55. http://dx.doi.org/10.1175/2010jtecho783.1.
Texte intégralRésumé :
Abstract High-quality measurements of the turbulent dissipation rate ε are required to diagnose field surf-zone turbulence budgets. Quality control (QC) methods are presented for estimating surf zone ε with acoustic Doppler velocimeter (ADV) data. Bad ADV velocity data points are diagnosed with both the ADV signal strength (SS) and correlation (CORR). The fraction of bad SS data points (δSS) depends inversely upon the wave-amplitude-normalized transducer distance below the mean sea surface. The fraction of bad CORR data points δCORR can be elevated when δSS is low. The δCORR depends inversely upon the wave-amplitude-normalized sensing volume distance below the mean sea surface, and also increases with increased wave breaking, consistent with turbulence- and bubble-induced Doppler noise. Velocity spectra derived from both “patched” and “interpolated” time series are used to estimate ε. Two QC tests, based upon the properties of a turbulent inertial subrange, are used to reject bad ε data runs. The first test checks that the vertical velocity spectrum’s power-law exponent is near . The second test checks that a ratio R of horizontal and vertical velocity spectra is near 1. Over all δCORR, 70% of the patched and interpolated data runs pass these tests. However, for larger δCORR > 0.1 (locations higher in the water column), 50% more patched than interpolated data runs pass the QC tests. Previous QC methods designed for wave studies are not appropriate for ε QC. The results suggest that ε can be consistently estimated over the lower 60% of the water column and >0.1 m above the bed within a saturated surf zone.
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Jukna, V., S. Albert, C. Millon, B. Mahieu, R. Guillermin, G. Rabau, D. Fattaccioli, A. Mysyrowicz, A. Couairon et A. Houard. « Control of the acoustic waves generated by intense laser filamentation in water ». Optics Express 30, no 6 (3 mars 2022) : 9103. http://dx.doi.org/10.1364/oe.453749.
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Supichayanggoon, Kacharat, Theodore Brockman et Andres H. La Rosa. « Acoustic monitoring humidity effects on the formation of water bridges at sharp contacts ». Journal of Physics : Conference Series 2678, no 1 (1 décembre 2023) : 012010. http://dx.doi.org/10.1088/1742-6596/2678/1/012010.
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Abstract Shear-force Acoustic Near-field Microscopy (SANM) and Whispering Gallery Acoustic Sensing (WGAS) are used to evaluate the role of humidity on the formation and rupture of water meniscus bridges that form between a laterally oscillating tapered probe and a flat substrate. SANM monitors the near-field acoustic wave emitted by the meniscus, while WGAS monitors acoustically the probe’s amplitude of oscillation, as a function of the probe-sample distance. In the instances reported here, the SANM/WGAS measurements are performed in frequency modulation modality, which allows to discriminate the elastic and inelastic components of the probe-fluid-substrate interaction. The response signal traces, acquired when the probe first approaches and then retracts from the sample at 56% relative humidity (or below), revealed absence of hysteresis; this result persists when performing the same experiment a few days later. However, as the humidity increases (different trials from 56% to 67% are included) a notorious hysteresis is observed between the approach and retraction traces. The results indicate that, as the probe approaches the substrate, a higher humidity promotes an increase of stochastic instabilities in the probe-fluid-substrate interactions (reflected in higher damping effects on the probe, and instabilities in the probe-sample distance feedback control). However, the elastic response of the water meniscus prevails over damping effect, as revealed by the greater acoustic emission despite a decrease in the probe’s amplitude. These measurements are relevant to investigations on the dynamic behavior of fluids near hydrophobic/philic substrates, and wetting properties of solids and nanotribology phenomena in general.
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Cardenas, J. I., et C. Vargas-Hernández. « Elastic Module Study of the Radial Section ofGuadua angustifoliaKunth Variety Bicolor ». Advances in Materials Science and Engineering 2014 (2014) : 1–5. http://dx.doi.org/10.1155/2014/935206.
Texte intégralRésumé :
Elastic modulus of the radial section of theGuadua angustifoliaKunth variety Bicolor was studied by technique of propagation of acoustic waves; the signal time delay in the samples was used as the control parameter. The studies were carried out in the culm cross-section in radial direction. The results indicate that the elastic modulus and the propagation velocity of the longitudinal wave in each of the cross-sections varied from2.5×107to1.6×109 Pa and from 1370 to 250 m/s for the inside and outside region of the culm, respectively. This behavior is due to the inhomogeneity, the water concentration, the fiber density, and the silicon concentration. The Raman spectroscopy analysis showed bands associated with hemicellulose, cellulose (carbon-carbon bonds), hydroxides carbon, and lignin. Silicone polymer compounds were identified by gas chromatography/mass spectroscopy.
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Kida, Tomoha, Yuichiro Sueoka, Hiro Shigeyoshi, Yusuke Tsunoda, Yasuhiro Sugimoto et Koichi Osuka. « Verification of Acoustic-Wave-Oriented Simple State Estimation and Application to Swarm Navigation ». Journal of Robotics and Mechatronics 33, no 1 (20 février 2021) : 119–28. http://dx.doi.org/10.20965/jrm.2021.p0119.
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Cooperative swarming behavior of multiple robots is advantageous for various disaster response activities, such as search and rescue. This study proposes an idea of communication of information between swarm robots, especially for estimating the orientation and direction of each robot, to realize decentralized group behavior. Unlike the conventional camera-based systems, we developed robots equipped with a speaker array system and a microphone system to utilize the time difference of arrival (TDoA). Sound waves outputted by each robot was used to estimate the relative direction and orientation. In addition, we attempt to utilize two characteristics of sound waves in our experiments, namely, diffraction and superposition. This paper also investigates the accuracy of state estimation in cases where the robots output sounds simultaneously and are not visible to each other. Finally, we applied our method to achieve behavioral control of a swarm of five robots, and demonstrated that the leader robot and follower robots exhibit good alignment behavior. Our methodology is useful in scenarios where steps or obstacles are present, in which cases camera-based systems are rendered unusable because they require each robot to be visible to each other in order to collect or share information. Furthermore, camera-based systems require expensive devices and necessitate high-speed image processing. Moreover, our method is applicable for behavioral control of swarm robots in water.
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Gaeta, Maria Gabriella, Massimo Guerrero, Sara Mizar Formentin, Giuseppina Palma et Barbara Zanuttigh. « Non-Intrusive Measurements of Wave-Induced Flow over Dikes by Means of a Combined Ultrasound Doppler Velocimetry and Videography ». Water 12, no 11 (30 octobre 2020) : 3053. http://dx.doi.org/10.3390/w12113053.
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The performance of non-intrusive instruments, such as acoustic profilers and cameras, to describe the wave-induced flow processes over maritime dike crest was investigated in experiments carried out at the University of Bologna. Direct and derived measurements from the acoustic probes deployed along the structure crest were discussed in relation to the observed backscatter rates. Image processing was implemented by means of clustering algorithm, in order to detect the free surface during overtopping events and characterize wave front propagation over the dike crest. UVP data were processed to indirectly derive flow depths and overtopping rates and compare them with the direct measurements in order to assess the measurement reliability and discuss their limits. Individual overtopping volume distribution as obtained by UVP data were estimated and compared with well-consolidated formulations, showing a good agreement. Finally, suggestions for an appropriate use of non-intrusive instruments to characterize a shallow, transient and aerated flow were provided, such as the control of the artificial seeding density, the use of a bi-static UVP configuration and adjustments to light exposure.
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Ruiken, Jan-Paul, Jörn Villwock et Matthias Kraume. « Behaviour of Acoustically Levitated Drops in Mid-Water ». Micromachines 14, no 10 (10 octobre 2023) : 1923. http://dx.doi.org/10.3390/mi14101923.
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A low-impact acoustic levitation system has been developed to study immobilised single drops in liquid–liquid systems. The ability to observe liquid drops several millimetres in diameter for days enables fundamental research into a wide range of mechanisms. Non-invasive optical measurements with excellent optical accessibility are possible. This experimental work provides the basis for mass transfer studies, emphasizing the precise volume determination, signal noise, reproducibility, and the impact of the acoustic field on the drop and its surrounding environment. The setup can be effectively controlled and proves beneficial for research objectives provided that all liquid phases are entirely degassed, and there are no compressible voids present within the liquids. In addition to the precise, uniform, and reliable measurement conditions, we observed no acoustic streaming in the proximity of the drop and there was no significant vibration of the drop. Qualitative observations using rainbow schlieren deflectometry indicate that the nodal or anti-nodal planes of the standing waves can act as barriers to the dispersion of inhomogeneous dissolved substances in the continuous phase.
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Lopes, Rubens M., Claudia Guimarães, Felipe M. Neves, Leandro T. De-La-Cruz, Gelaysi Moreno Vega, Damián Mizrahi et Julio Cesar Adamowski. « The Effect of Ultrasound Waves on the Pre-Settlement Behavior of Barnacle Cyprid Larvae ». Journal of Marine Science and Engineering 12, no 8 (11 août 2024) : 1364. http://dx.doi.org/10.3390/jmse12081364.
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Ultrasound waves have been employed to control marine biofouling but their effects on fouling organisms remain poorly understood. This study investigated the influence of ultrasound waves on barnacle (Tetraclita stalactifera cyprid larvae) pre-settlement behavior. Substrate inspection constituted most of the larval time budget, with a focus on the bottom surface rather than lateral or air–water interfaces. The frequency of substrate inspection decreased at 10 kPa when compared to higher acoustic pressures, while the time spent in the water column had an opposite trend. Various larval swimming modes were observed, including rotating, sinking, walking, and cruising, with rotating being dominant. Barnacle larvae exhibited higher speeds and less complex trajectories when subjected to ultrasound in comparison to controls. The impact of ultrasound waves on barnacle cyprid larvae behavior had a non-linear pattern, with lower acoustic pressure (10 kPa) inducing more effective substrate rejection than higher (15 and 20 kPa) intensities.
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Gimaltdinov, I. K., et A. S. Rodionov. « ON THE EFFECT OF CAPILLARY FORCES ON PULSE DYNAMICS IN A POROUS MEDIUM ». Petroleum Engineering 22, no 6 (24 décembre 2024) : 194–202. https://doi.org/10.17122/ngdelo-2024-6-194-202.
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The study of elastic waves in porous media is of practical importance for the tasks of mineral prospecting, the use of porous screens for damping shock wave effects, studying the structure of the Earth's crust, etc. The elastic properties of a porous medium depend on the velocity of propagation of elastic waves, which, in turn, strongly depends on the degree of consolidation in the porous medium. The main acoustic feature of bulk sand (sand, glass balls, granular materials) media is the low speed of sound, about 100 m/s. Their compaction leads to a slight increase in velocity, and consolidation (sandstone, cementation with gas hydrate) leads to a multiple increase in the velocity of acoustic waves, about 2000-3000 m/s. In the process of hydraulic fracturing, water–gas exposure, treatment of porous formations with various acids to increase the bottom-hole zone of the formation, during the formation and decomposition of gas hydrates, the porous medium is saturated with a gas-liquid - bubble mixture. The morphology of the arrangement of bubbles and particles forming a porous skeleton can be different: the bubbles can be located in a liquid saturating the pores, cover several particles of the skeleton, or the liquid can be in the form of capillary water located in the form of a meniscus between two particles. To monitor the effectiveness of the above-described effects on porous media, acoustic sounding of porous media saturated with a gas-liquid mixture can be used. Therefore, the purpose of this work is to simulate the process of passing shock waves of small amplitude in sand saturated with liquid. The effect of the capillary coupling force on the dynamics of a shock wave pulse in a partially liquid–saturated porous medium is analyzed. A system of equations of mechanics of multiphase media is used for mathematical modeling, including the equation of conservation of mass for gas and solid phase, the equation of pulses and the equation of energy. The skeleton of a porous medium is assumed to be viscoelastic, the gas is calorically perfect; the forces of capillary adhesion between the grains of sand, the forces of viscous friction and the attached masses are taken into account. The control volume method is used for the numerical solution of the presented model.
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Erofeev, V. I., A. V. Ilyahinskii, E. A. Motova, V. M. Rodyushkin et A. V. Shekoyan. « ON THE ACOUSTIC PARAMETERS OF METAL CONSTRUCTIONWHEN DAMAGE IS ACCUMULATED ». Problems of strenght and plasticity 83, no 3 (2021) : 344–53. http://dx.doi.org/10.32326/1814-9146-2021-83-3-344-353.
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In the work with the use of nondestructive control methods, the issues of determining acceptable durability or safe resource are considered. It is shown that the design monitoring procedure can be presented as follows: determines the original state zero zone, where the material of the product was subjected to low operational loads; further, with the use of nondestructive control methods, the acoustic parameter is measured (without disassembling the product)., such as the speed of elastic acoustic waves, nonlinear acoustic parameter, difference of velocities with twofrequency sensing, etc.; acoustic scanning of the product's metal is performed, in areas where there have been significant loads, signoff voltages, leading to an intensive accumulation of damage (the destruction of metal leading to cracks); defined zone “N” where the metal state parameter, for which the value is taken, characterizing the difference of the acoustic parameter (the speed of elastic waves, nonlinear acoustic parameter, the difference in velocity in twofrequency sensing) relative to the same parameter in the zone of zero exceeds the established level. The regularities established in the work linking the presence of plastic deformation with the difference in the delays (velocity) of elastic Rayleigh waves at different sounding frequencies at a fixed base between the emitter and the receiver of elastic waves, as well as the behavior of a nonlinear acoustic parameter during the safe resource time, suggest the possibility of using the observd fact as a principle for controlling the limiting state of the material due to plastic deformations on industrial structures. Based on the proposed approach, an engineering methodology for determining the technical condition of the material of the structures of production facilities is proposed, which allows to establish three stages of operation: the reliable operation mode; the controlled operation mode and the critical operation mode.
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Khaksar, A. « CALIBRATING CORE, LOG AND SEISMIC DATA TO ASSESS EFFECTIVE STRESS AND HYDROCARBON SATURATION, COOPER BASIN, SOUTH AUSTRALIA ». APPEA Journal 40, no 1 (2000) : 314. http://dx.doi.org/10.1071/aj99017.
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Laboratory measurements of acoustic properties of representative rock samples, simulating in-situ effective stress and fluid saturation, provide useful guides for calibrating and interpreting seismic and sonic log data. This paper addresses some of the major implications arising from a petro-acoustic study for the evaluation of reservoir depletion of Cooper Basin gas reservoirs using logs and seismic. Measurement of P- and S-wave velocities on cores under varying pressure conditions reveals that the stress dependency of Cooper Basin rocks is very large, while core porosity remains effectively unchanged.The saturation heterogeneity at pore-scale, which is shown in capillary pressure data, controls the velocity- saturation in partially water-saturated samples. The steady decrease of P-wave velocity as saturation decreases from the high saturation range to near irreducible conditions suggests a simultaneous drainage of water from pores with a variety of high to moderate aspect ratios, while microcracks (low aspect ratio pores) retain water. Closure and degree of saturation of the low aspect ratio pores control the velocity-effective stress and velocity-saturation relationships at low saturation and stress conditions.The velocity dispersion due to frequency difference between ultrasonic laboratory measurements on cores and theoretical low (seismic) frequency is about 1%, and thus laboratory-measured velocities are comparable with sonic log and seismic data in the Cooper Basin. The potential of the velocity ratio (Vp/Vs) for detection of fluid type and the saturation status at in-situ reservoir effective stress, and prediction of Vs from Vp, are demonstrated for the Cooper Basin rocks. Acoustic measurements on cores, wireline data and seismic modelling are used to predict the expected change in seismic response as the reservoir depletes. Synthetic seismic profiles indicate that the zero-offset reflectivity of a shale to reservoir interface decreases by 28% for a 30 MPa pressure depletion in a typical gas expansion drive reservoir. Such changes should be easily measurable between repeated surveys, suggesting that time-lapse seismic for the monitoring of in-situ effective stress and saturation may have application in Cooper Basin reservoirs. Although these findings refer specifically to the Cooper Basin, the methods used and results of this study may be applicable elsewhere.
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Valent, Peter, Roman Výleta et Michaela Danáčová. « A Joint Sedimentation-Flood Retention Assessment of a Small Water Reservoir in Slovakia : A New Hope for Old Reservoirs ? » Geosciences 9, no 4 (3 avril 2019) : 158. http://dx.doi.org/10.3390/geosciences9040158.
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The intensification of agricultural production brings problems related to water erosion, even to the upper parts of river basins. Soil particles that have eroded from unprotected agricultural land are often deposited in small water reservoirs, the efficiency or function of which might be compromised. This study presents an analysis of changes in the retention capacity of a small water reservoir over a period of 8 years. Within the study, a detailed bathymetry of the reservoir was conducted using an acoustic Doppler current profiler. The results, when compared to a 2008 geodetic survey, showed that the retention volume of the reservoir was reduced by only 2%, which was also confirmed by mathematical modeling. The possibility of strengthening the reservoir’s role in flood protection was also investigated. A flood wave with a return period of 100 years was estimated using a design storm approach. A simple numerical model was proposed to transform the flood wave through the reservoir by considering four different scenarios of the elevation of the initial water level. The model, which is based on a water balance equation, uses simple hydraulic relationships to control the discharge through the reservoir’s outflow objects. The results demonstrate that by reducing the initial water level, significant improvements in terms of the flood peak’s attenuation and a longer time to peak values could be achieved.
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Almawgani, Abdulkarem H. M., Hamza Makhlouf Fathy, Ghassan Ahmed Ali, Hussein A. Elsayed et Ahmed Mehaney. « One-Dimensional Phononic Crystals : A Simplified Platform for Effective Detection of Heavy Metals in Water with High Sensitivity ». Micromachines 14, no 1 (13 janvier 2023) : 204. http://dx.doi.org/10.3390/mi14010204.
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Recently, the pollution of fresh water with heavy metals due to technological and industrial breakthroughs has reached record levels. Therefore, monitoring these metals in fresh water has become essentially urgent. Meanwhile, the conventional periodic one-dimensional phononic crystals can provide a novel platform for detecting the pollution of heavy metals in fresh water with high sensitivity. A simplified design of a defective, one-dimensional phononic crystals (1D-PnC) structure is introduced in this paper. The sensor is designed from a lead-epoxy multilayer with a central defect layer filled with an aqueous solution from cadmium bromide (CdBr2). The formation of a resonant peak through the transmittance spectrum is highly expected. This study primarily aims to monitor and detect the concentration of cadmium bromide in pure water based on shifting the position of this resonant peak. Notably, any change in cadmium bromide concentration can affect the acoustic properties of cadmium bromide directly. The transfer matrix method has been used to calculate the transmission spectra of the incident acoustic wave. The numerical findings are mainly based on the optimization of the cadmium bromide layer thickness, lead layer thickness, epoxy layer thickness, and the number of periods to investigate the most optimum sensor performance. The introduced sensor in this study has provided a remarkably high sensitivity (S = 1904.25 Hz) within a concentration range of (0–10,000 ppm). The proposed sensor provides a quality factor (QF), a resolution, and a figure of merit of 1398.51752, 48,875,750 Hz, and 4.12088 × 10−5 (/ppm), respectively. Accordingly, this sensor can be a potentially robust base for a promising platform to detect small concentrations of heavy metal ions in fresh water.
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Miller, Alexander, Boris Miller et Gregory Miller. « Navigation of Underwater Drones and Integration of Acoustic Sensing with Onboard Inertial Navigation System ». Drones 5, no 3 (26 août 2021) : 83. http://dx.doi.org/10.3390/drones5030083.
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The navigation of autonomous underwater vehicles is a major scientific and technological challenge. The principal difficulty is the opacity of the water media for usual types of radiation except for the acoustic waves. Thus, an acoustic transducer (array) composed of an acoustic sonar is the only tool for external measurements of the AUV attitude and position. Another difficulty is the inconstancy of the speed of propagation of acoustic waves, which depends on the temperature, salinity, and pressure. For this reason, only the data fusion of the acoustic measurements with data from other onboard inertial navigation system sensors can provide the necessary estimation quality and robustness. This review presents common approaches to underwater navigation and also one novel method of velocity measurement. The latter is an analog of the well-known Optical Flow method but based on a sequence of sonar array measurements.
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Kottapalli, Shravan, Stijn van Aken, Avraham Hirschberg, Nicholas Waterson, David Smeulders et Gunes Nakiboglu. « Influence of orifice thickness and chamfer on broadband noise in a water circuit ». Acta Acustica 7 (2023) : 66. http://dx.doi.org/10.1051/aacus/2023058.
Texte intégralRésumé :
An incompressible large-eddy simulation (LES) is used to predict broadband noise generation by an orifice in a water circuit. Flow conditions are chosen in order to avoid cavitation. The model’s results are compared to measured wall pressure fluctuations for three orifices: a thin sharp-square-edge orifice, a thick sharp-square-edge orifice and a thick narrower orifice with an upstream chamfer. Reynolds-averaged Navier–Stokes (RANS) and large-eddy simulations (LES) fail to reproduce the steady-flow drag coefficient of the thick sharp-edge orifice and of the upstream-chamfered orifice. Large differences are found in the steady-flow drag coefficient of different samples of the thick orifice. An edge-tone like instability is observed in the near-field pressure fluctuations of one of the thick sharp-square-edge orifices, which does not appear in the other samples and is suppressed by the upstream chamfer. However, there are only minor differences in far-field radiated sound for these thick sharp-edged orifices. A plane-wave model with acoustic source from the LES predicts the power spectral density (PSD) of the acoustic pressures within a factor 3. At low Strouhal numbers (based on the orifice diameter and the cross-sectional averaged velocity in the orifice) the thin orifice behaves similarly to the thicker strongly chamfered orifices, with thin central cylindrical section. At higher Strouhal numbers the measured and predicted acoustic-pressure fluctuations due to these orifices are two orders of magnitude lower than those of thick orifices with sharp square edges. As orifices are used for the control of the flow distribution through complex water-cooling networks, the good results for thick chamfered narrow orifices call for a further study to find shapes that minimize the sound production at constant static pressure drop.
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Zhu, Shan, Guojun Zhang, Daiyue Wu, Xiaoqi Liang, Yifan Zhang, Ting Lv, Yan Liu, Peng Chen et Wendong Zhang. « Research on Direction of Arrival Estimation Based on Self-Contained MEMS Vector Hydrophone ». Micromachines 13, no 2 (30 janvier 2022) : 236. http://dx.doi.org/10.3390/mi13020236.
Texte intégralRésumé :
A self-contained MEMS vector hydrophone with a scalar–vector integrated design is proposed in this paper. Compared with traditional MEMS vector hydrophones, this design solves the problem of ambiguity in the port and starboard during orientation, and also realizes the self-contained storage of acoustic signals. First, the sensor principle and structural design of the self-contained MEMS hydrophone are introduced, and then the principle of the combined beamforming algorithm is given. In addition to this, the amplitude and phase calibration method based on the self-contained MEMS vector hydrophone is proposed. Then, the sensitivity and phase calibrations of the sensor are carried out in the standing wave tube. The sensitivity of the vector channel is −182.7 dB (0 dB@1 V/μPa) and the sensitivity of the scalar channel is −181.8 dB (0 dB@1 V/μPa). Finally, an outdoor water experiment was carried out. The experimental results show that the self-contained MEMS vector hydrophone can accurately pick up and record underwater acoustics information. It realizes the precise orientation of the target by combining beamforming algorithms. The direction of arrival (DOA) error is within 5° under the outdoor experimental conditions with an SNR of 13.67 dB.
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Pao, Chun-Hung, Jia-Lin Chen, Shih-Feng Su, Yu-Ching Huang, Wen-Hsin Huang et Chien-Hung Kuo. « The Effect of Wave-Induced Current and Coastal Structure on Sediment Transport at the Zengwen River Mouth ». Journal of Marine Science and Engineering 9, no 3 (17 mars 2021) : 333. http://dx.doi.org/10.3390/jmse9030333.
Texte intégralRésumé :
The mechanisms that control estuarine sediment transport are complicated due to the interaction between riverine flows, tidal currents, waves, and wave-driven currents. In the past decade, severe seabed erosion and shoreline retreat along the sandy coast of western Taiwan have raised concerns regarding the sustainability of coastal structures. In this study, ADCPs (Acoustic Doppler Current Profiler) and turbidity meters were deployed at the mouth of the Zengwen river to obtain the time series and the spatial distribution of flow velocities and turbidity during the base flow and flood conditions. A nearshore circulation model, SHORECIRC, has been adapted into a hybrid finite-difference/finite-volume, TVD (Total Variation Diminishing)-type scheme and coupled with the wave-spectrum model Simulating Waves Nearshore (SWAN). Conventional finite-difference schemes often produce unphysical oscillations when modeling coastal processes with abrupt bathymetric changes at river mouths. In contrast, the TVD-type finite volume scheme allows for robust treatment of discontinuities through the shock-capturing mechanism. The model reproduces water levels, waves, currents observed at the mouth of the Zengwen River reasonably well. The simulated residual sediment transport patterns demonstrate that the transport process at the river mouth is dominated by the interaction of the bathymetry and wave-induced currents when the riverine discharge was kept in reservoirs. The offshore residual transport causes erosion at the northern part of the river mouth, and the onshore residual transport causes accretion in the ebb tidal shoals around the center of the river mouth. The simulated morphological evolution displays significant changes on shallower deltas. The location with significant sea bed changes is consistent with the spot in which severe erosion occurred in recent years. Further analysis of morphological evolution is also discussed to identify the role of coastal structures, for example, the extension of the newly constructed groins near the river mouth.
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Cominelli, Sebastiano, et Francesco Braghin. « Optimal design of broadband, low-directivity graded index acoustic lenses for underwater communication ». Journal of the Acoustical Society of America 156, no 3 (1 septembre 2024) : 1952–63. http://dx.doi.org/10.1121/10.0029025.
Texte intégralRésumé :
Manipulating underwater pressure waves is crucial for marine exploration, as electromagnetic signals are strongly absorbed in water. However, the multi-path phenomenon complicates the accurate capture of acoustic waves by receivers. Although graded index lenses, based on metamaterials with smoothly varying properties, successfully focus pressure waves, they tend to have high directivity, which hinders practical application. This work introduces three 2D acoustic lenses made from a metamaterial composed of solid inclusions in water. We propose an optimization scheme where the pressure dynamics is governed by Helmholtz's equation, with control parameters affecting each lens cell's density and bulk modulus. Through an appropriate cost function, the optimization encourages a broadband, low-directivity lens. The large-scale optimization is solved using the Lagrangian approach, which provides an analytical expression for the cost gradient. This scheme avoids the need for a separate discretization step, allowing the design to transition directly from the desired smooth refractive index to a practical lattice structure. As a result, the optimized lens closely aligns with real-world behavior. The homogenized numerical model is validated against finite elements, which considers acoustic-elastic coupling at the microstructure level. When homogenization holds, this approach proves to be an effective design tool for achieving broadband, low-directivity acoustic lenses.
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MARR-LYON, MARK J., DAVID B. THIESSEN et PHILIP L. MARSTON. « Stabilization of a cylindrical capillary bridge far beyond the Rayleigh–Plateau limit using acoustic radiation pressure and active feedback ». Journal of Fluid Mechanics 351 (25 novembre 1997) : 345–57. http://dx.doi.org/10.1017/s002211209700726x.
Texte intégralRésumé :
A novel method of suppressing the Rayleigh–Plateau capillary instability of a cylindrical liquid bridge is demonstrated which uses the radiation pressure of an ultrasonic wave to control the shape of the bridge. The shape of the bridge is optically sensed and the information used to control the spatial distribution of the radiation stress on the surface of the bridge. The feedback is phased so as to suppress the growth of the axisymmetric mode which normally becomes unstable when the slenderness, given by the length to diameter ratio, exceeds π. Stabilization is achieved out to a slenderness of 4.3 for a bridge density matched to the surrounding water bath in a Plateau tank. Breakup of such long bridges was found to produce a satellite drop from the receding thread of liquid. The active stabilization mechanism used may have application to other capillary systems.
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Majnooni, Meysam, Elise Doveri, Jeanne Baldisser, Vincent Long, Julien Houles, Jean-Claude Scimeca, David Momier, Carine Guivier-Curien, Philippe Lasaygues et Cécile Baron. « Anti-reflection cover to control acoustic intensity in in vitro low-intensity ultrasound stimulation of cells ». Acta Acustica 6 (2022) : 11. http://dx.doi.org/10.1051/aacus/2022007.
Texte intégralRésumé :
Low-intensity ultrasound stimulation is a technique used in therapeutic ultrasound for bone regeneration. However, the underlying mechanisms are still poorly understood. In vitro studies on cell cultures are implemented to understand the processes involved. To analyze the effects of ultrasonic waves on cells, the control of the delivered acoustic intensity is essential. However, depending on the insonification protocol chosen, multiple reflections and standing waves that form inside the culture medium strongly hinder the estimates. In this work, we propose the development and the experimental validation of an anti-reflection cover. We demonstrate that this custom-designed device is effective in avoiding multiple reflections and makes it possible to artificially replace the layer of culture medium with a large amount of water. Finally, an analytical study of the acoustic intensity delivered to the cells is proposed.
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Józefczak, A., et R. Wlazło. « Ultrasonic Studies of Emulsion Stability in the Presence of Magnetic Nanoparticles ». Advances in Condensed Matter Physics 2015 (2015) : 1–9. http://dx.doi.org/10.1155/2015/398219.
Texte intégralRésumé :
Pickering emulsions are made of solid particle-stabilized droplets suspended in an immiscible continuous liquid phase. A magnetic emulsion can be obtained using magnetic particles. Solid magnetic nanoparticles are adsorbed strongly at the oil-water interface and are able to stabilize emulsions of oil and water. In this work emulsions stabilized by magnetite nanoparticles were obtained using high-energy ultrasound waves and a cavitation mechanism and, next, their stability in time was tested by means of acoustic waves with a low energy, without affecting the structure. An acoustic study showed high stability in time of magnetic emulsions stabilized by magnetite particles. The study also showed a strong influence of an external magnetic field, which can lead to changes of the emulsion properties. It is possible to control Pickering emulsion stability with the help of an external stimulus—a magnetic field.