Transmission Of Acoustic Waves Research Articles

Nonreciprocal transmission of surface acoustic waves induced by magneotoelastic coupling with an anti-magnetostrictive bilayer

In this study, we report giant nonreciprocal transmission of shear-horizontal surface acoustic waves (SH-SAWs) in a ferromagnetic bilayer structure with negative–positive magnetostriction configuration. Although the directions of magnetization in the neighboring layers are parallel, SH-SAWs can excite optical-mode spin waves (SWs) via magnetoelastic coupling at relatively low frequencies, which is much stronger than acoustic-mode SWs at high frequencies. The measured magnitude nonreciprocity or isolation of SH-SAWs exceeds 40 dB (or 80 dB/mm) at 2.333 GHz. In addition, maximum nonreciprocal phase accumulation reaches 188° (376°/mm). Our theoretical model and calculations provide an insight into the observed phenomena and demonstrate a pathway for further improving nonreciprocal acoustic devices toward highly compact microwave isolators and circulators.

Multiband topological acoustic waveguide with multistage toroidal resonant cavities

In recent years, there has been significant development in acoustic waveguides through the introduction of topological phase correlation concepts in acoustics. Many studies have shown the properties of acoustic unidirectional transmission. This paper presents a new ring-shaped acoustic topological insulator that is multi-band, unlike previous structures. The structure improves internal space utilization with the same dimensions, reducing acoustic wave conduction frequency in air environments. Additionally, the introduction of a multistage ring-shaped resonant cavity enables the conduction of acoustic waves in multiple frequency bands. This paper employs the rotational scattering mechanism to invert the topological phase of the lattice. This allows for the construction of two crystals with opposite phases, which can be used to create a topological channel for the transmission of acoustic waves. At the topological interface, the acoustic transmission losses within the four bands are small. Furthermore, this paper verifies by simulation that the defects have little effect on acoustic transmission. The paper's research offers potential for multiband acoustic control.

Exploring acoustic wave transmission in micropolar plate in air

This study explores the behavior of sound wave propagation across a micropolar plate at diverse incident angles, specifically crafted from expanded polystyrene. Through a blend of theoretical formulations and practical experimentation, we scrutinize the alterations in transmission coefficients within the frequency spectrum, shedding light on the dynamic shifts in various vibrational modes. Utilizing a comprehensive setup comprising a loudspeaker, microphone, and National Instruments acquisition system, we meticulously discerned the initial trio of longitudinal vibration modes across a broad frequency span extending up to 70 kHz. Notably, despite the plate's inherent dispersion and attenuation traits, this experimental setup proved effective. A distinctive facet of our approach lies in the deliberate incorporation of multiple incident angles, which yielded crucial insights. Notable is the identification, within the experiments, of a critical angle, marking a transitional zone. Below this threshold, distinct Lamb modes dominate, while beyond it, the emergence of micropolar modes becomes apparent. These empirically validated findings, in alignment with theoretical projections, substantially enrich our comprehension of these materials' engineering applications.

Observation of micropolar modes in the transmission of acoustic waves at oblique incidence by polystyrene plates.

This study investigates micropolar plates through the analysis of transmitted acoustic waves at various incident angles. Using a combined theoretical and experimental approach, we explore the non-classical elasto-dynamic behavior of these materials. Theoretical transmission coefficients are tailored to highlight generalized Lamb modes and a new type of vibration mode called micropolar modes, considering the constant thickness of the plate and the effects of material micropolarity on linear elasticity. Overlaying diverse transmission coefficients for different angles provides insight into micropolar behavior, aiding in the understanding of mode evolution in the frequency domain and the estimation of the critical angle. We employ two types of low-density closed-cell foams made from polystyrene (expanded in one case, extruded in the other), covering a frequency range from 4 to 60 kHz using a tweeter loudspeaker and a microphone integrated with a National Instruments acquisition system. Identification of the first vibration mode of the plates is facilitated by the frequency range rich in low frequencies. Additionally, all responses exhibit supersonic velocities with substantial attenuations. The originality of this paper is twofold: it provides theoretical predictions of micropolar modes, along with their experimental observations above a critical angle of incidence. Consequently, this research enriches our understanding of micropolar materials and their potential contribution to effective noise reduction strategies in acoustic engineering.

Inhomogeneous fan-shaped surface state induced by isolated Weyl points in acoustic crystals and the associated multi-frequency sound-wave filters

The nontrivial surface states excited by isolated Weyl points (IWPs) have been scarcely studied to date, primarily due to their circumvention from the Nielsen-Ninomiya no-go theorem. In a groundbreaking study on this topic [Adv. Sci., 10, 2207508 (2023)], we discovered that IWPs can generate a novel nontrivial surface state, namely the multi-fold fan-shaped surface state, which we named. Here, we report another type of fan-shaped surface state generated by an IWP surrounded by a closed Weyl nodal wall (WNW). Unlike previous findings, the fan-shaped surface state discovered here exhibits inhomogeneous in spatial distribution, with significantly varying sizes of the fan blades. Moreover, this surface state can be generated by a charge-four IWP protected by the rotation symmetries {C31+|000}, {C2z|12012}, {C2x|01212} and the time-reversal symmetry in the space group (SG) No. 198. Importantly, our simulation results of the acoustic crystals in this SG revel that the inhomogeneous fan-shaped surface state can provide multiple channels for acoustic wave transmission without energy dissipation, demonstrating that this kind of nontrivial surface state offers an effective mechanism for designing multi-frequency acoustic wave filters and selectors.

Potential of acoustic sensors for real-time monitoring of physicochemical properties of milk protein concentrate during ultrafiltration

Ultrafiltration (UF) is the step for concentrating protein in milk and whey prior to evaporation and drying in dairy ingredient production, e.g. milk protein concentrate (MPC). To optimize UF process, it is important to monitor changes in product/process parameters. Two in-line sensors with outputs: 1. bulk acoustic wave (BAW), acoustic viscosity (AV); 2. surface acoustic wave (SAW), acoustic impedance (AI) and acoustic transmission (AT), were evaluated to measure MPC physicochemical properties (total solids (TS), density, protein and apparent viscosity) during UF. Trials were quintuplicated in a UF membrane pilot-plant, to concentrate feed (TS 11.36–19.10%). Models for predicting MPC physicochemical properties developed by acoustic parameters performed well, especially by AI and AT, with R2 > 0.963, SEP <1.076 to predict apparent viscosity, and R2 > 0.980, SEP <0.627 for all other properties’ prediction. This study demonstrated the potential of both acoustic sensors for UF process monitoring.

Multi-scale fusion and efficient feature extraction for enhanced sonar image object detection

Sonar imaging is an underwater detection technology that relies on the transmission and reception of acoustic pulse waves. This technique plays a crucial role in various domains including underwater archaeology, energy exploration, and oceanographic surveying. A primary challenge in sonar imaging is the low signal-to-noise ratio and significant noise interference, issues that are influenced by the constraints of equipment performance and the underwater environment. Traditional object detection techniques have been inadequate in effectively extracting deep features from sonar images possessing targets with complex structures and have also demonstrated shortcomings in the fusion processing of target features at multiple scales, thereby affecting the robustness and accuracy of object detection. To improve the performance of sonar image object detection, we propose an advanced detection framework that integrates efficient feature extraction with multi-scale feature fusion. We employ EfficientNet as the backbone network. EfficientNet exhibits excellent feature extraction capabilities through comprehensive adjustments of depth, width, and resolution. We introduce a dual-channel attention module that blends Squeeze-and-Excitation (SE) and Efficient Channel Attention (ECA) mechanisms to amplify the expression of crucial feature channels and suppress the lesser ones. Additionally, we utilize a modified bidirectional feature pyramid network (BiFPN) to strengthen the integration of features across different layers. Employing these methods, we amalgamate the features into a shared weights classification network and bounding box prediction network for accurate target class discernment and localization. The experimental outcomes provide evidence of the notable superlative nature of the proposed framework in sonar image object detection, effectively ameliorating detection performance amidst noise interference.

Mathematical Modeling of Multi-Physics Phenomena in Smart Materials and Structures

Smart materials and buildings show interesting multi-physics effects, where the interaction of different physical fields like mechanics, electromagnetics, thermodynamics, and sound is very important. This essay gives an in-depth look at different mathematical modeling methods used to understand and predict how smart materials and buildings will behave in various situations. At its core, the modeling framework combines guiding equations from various physical fields. This calls for a comprehensive method that takes into account how these events interact with each other in complex ways. The basis is mechanics, which includes fundamental equations that show how materials react to mechanical forces, including elasticity, viscoelasticity, and flexibility. Electromagnetic effects are very important in materials like magnetostrictives and piezoelectrics, where the way electrical and mechanical fields combine determines how they work. To correctly describe this electrical connection, Maxwell's equations are linked to mechanical equations. This lets devices like sensors, motors, and energy harvesters be designed and improved. Thermodynamics is used for shape memory metals and phase change materials, whose behavior is controlled by changes in temperature. Adding heat transfer equations to mechanical and electromagnetic equations helps us fully understand how these materials interact with heat, motion, and electricity, which is important for many uses, from medical devices to spacecraft structures. Structures with active shaking control systems that use piezoelectric materials have interesting acoustic effects. With the help of mechanical and electrical algorithms and acoustic wave transmission models, it is possible to study and create smart structures that can reduce noise and shocks while also improving their performance and integrity. The study also talks about numerical methods, like finite element methods and multiphysics modeling tools, that can be used to quickly solve the linked equations. These tools help us learn more about how complicated materials behave in various working situations.

Effects of factors from practical workpieces on ultrasonic LCR method stress measurement

The non-destructive stress measurement method is the main trend in residual stress analysis. The ultrasonic method, which utilizes the acoustoelastic effect of the longitudinal critically refracted (LCR) wave, is one of the time-saving measurement techniques. During the practical stress measurement on a workpiece, various external factors may impact the transmission of acoustic waves and the resulting stress value. This study revealed and discussed the effects of four factors on the LCR wave: surface roughness of the examined material, temperature of the material, external mechanical vibration, and surface paint. The stress coefficient was determined by comparing the offset time of the acoustic wave with the stress measured by X-ray analyzer in the zero-stress specimens, which had undergone annealing and deep cryogenic treatment. The test results indicated that the surface roughness did not affect the transition time of the acoustic wave, but it did decrease the intensity of the signal. The increase in temperature and the transition time of the acoustic wave were in a linear relationship. Mechanical vibrations from the environment would not affect the transition time or signal intensity of the acoustic wave, whereas the application of surface paint increased the transition time. Although the effect of paint on the actual workpiece could not be easily modified during stress measurement, the ultrasonic method was still suitable for monitoring the stress of a specific position of the workpiece throughout its operational lifetime. The experiment data in this study were applied to measuring the residual stress of an aluminum ship component, and the result showed a good correspondence with X-ray stress analyzer results.

Preparation of Fibrous Three-Dimensional Porous Materials and Their Research Progress in the Field of Stealth Protection.

Intelligent and diversified development of modern detection technology greatly affects the battlefield survivability of military targets, especially infrared, acoustic wave, and radar detection expose targets by capturing their unavoidable infrared radiation, acoustic wave, and electromagnetic wave information, greatly affecting their battlefield survival and penetration capabilities. Therefore, there is an urgent need to develop stealth-protective materials that can suppress infrared radiation, reduce acoustic characteristics, and weaken electromagnetic signals. Fibrous three-dimensional porous materials, with their high porosity, excellent structural adjustability, and superior mechanical properties, possess strong potential for development in the field of stealth protection. This article introduced and reviewed the characteristics and development process of fibrous three-dimensional porous materials at both the micrometer and nanometer scales. Then, the process and characteristics of preparing fibrous three-dimensional porous materials through vacuum forming, gel solidification, freeze-casting, and impregnation stacking methods were analyzed and discussed. Meanwhile, their current application status in infrared, acoustic wave, and radar stealth fields was summarized and their existing problems and development trends in these areas from the perspectives of preparation processes and applicability were analyzed. Finally, several prospects for the current challenges faced by fibrous three-dimensional porous materials were proposed as follows: functionally modifying fibers to enhance their applicability through self-cross-linking; establishing theoretical models for the transmission of thermal energy, acoustic waves, and electromagnetic waves within fibrous porous materials; constructing fibrous porous materials resistant to impact, shear, and fracture to meet the needs of practical applications; developing multifunctional stealth fibrous porous materials to confer full-spectrum broadband stealth capability; and exploring the relationship between material size and mechanical properties as a basis for preparing large-scale samples that meet the application's requirement. This review is very timely and aims to focus researchers' attention on the importance and research progress of fibrous porous materials in the field of stealth protection, so as to solve the problems and challenges of fibrous porous materials in the field of stealth protection and to promote the further innovation of fibrous porous materials in terms of structure and function.

Research on a Corrosion Detection Method for Oil Tank Bottoms Based on Acoustic Emission Technology.

This paper presents an acoustic emission (AE) detection method for refined oil storage tanks which is aimed towards specialized places such as oil storage tanks with high explosion-proof requirements, such as cave oil tanks and buried oil tanks. The method utilizes an explosion-proof acoustic emission instrument to detect the floor of a refined oil storage tank. By calculating the time difference between the defective acoustic signal and the speed of acoustic wave transmission, a mathematical model is constructed to analyze the detected signals. An independent channel AE detection system is designed, which can store the collected data in a piece of independent explosion-proof equipment, and can analyze and process the data in a safe area after the detection, solving the problems of a short signal acquisition distance and the weak safety protection applied to traditional AE instruments. A location analysis of the AE sources is conducted on the bottom plate of the tank, evaluating its corrosion condition accurately. The consistency between the evaluation and subsequent open-tank tests confirms that using AE technology effectively captures corrosion signals from oil storage tanks' bottoms. The feasibility of carrying out online inspection under the condition of oil storage in vertical steel oil tanks was verified through a comparison with open inspections, which provided a guide for determining the inspection target and opening order of large-scale oil tanks.

Topology optimization of broadband acoustic transition section: a comparison between deterministic and stochastic approaches

This paper focuses on the topology optimization of a broadband acoustic transition section that connects two cylindrical waveguides with different radii. The primary objective is to design a transition section that maximizes the transmission of a planar acoustic wave while ensuring that the transmitted wave exhibits a planar shape. Helmholtz equation is used to model linear wave propagation in the device. We utilize the finite element method to solve the state equation on a structured mesh of square elements. Subsequently, a material distribution topology optimization problem is formulated to optimize the distribution of sound-hard material in the transition section. We employ two different gradient-based approaches to solve the optimization problem: namely, a deterministic approach using the method of moving asymptotes (MMA), and a stochastic approach utilizing both stochastic gradient (SG) and continuous stochastic gradient (CSG) methods. A comparative analysis is provided among these methodologies concerning the design feasibility and the transmission performance of the optimized designs, and the computational efficiency. The outcomes highlight the effectiveness of stochastic techniques in achieving enhanced broadband acoustic performance with reduced computational demands and improved design practicality. The insights from this investigation demonstrate the potential of stochastic approaches in acoustic applications, especially when broadband acoustic performance is desired.

Giant nonreciprocity of surface acoustic waves induced by an anti-magnetostrictive bilayer

Lack of nonreciprocity is one of the major drawbacks of solid-state acoustic devices, which has hindered the development of microwave-frequency acoustic isolators and circulators. Here, we report a giant nonreciprocal transmission of shear-horizontal surface acoustic waves (SH-SAWs) on a LiTaO3 substrate coated with a negative–positive magnetostrictive bilayer structure of Ni/Ti/FeCoSiB. Although the static magnetic moments of two layers are parallel, SH-SAWs can excite optical-mode spin waves much stronger than acoustic-mode ones at relatively low frequencies via magnetoelastic coupling. The measured magnitude nonreciprocity exceeds 40 dB (or 80 dB/mm) at 2.333 GHz. In addition, maximum nonreciprocal phase accumulation reaches 188° (376°/mm), which is desired for an effective SAW circulator. Our theoretical model and calculations provide an insight into the observed phenomena and demonstrate a pathway for further improvement of nonreciprocal acoustic devices.

On-chip topological phononic crystal acoustic waveguide based on lithium niobate thin films

This Letter introduces an on-chip topological phononic crystal (PnC) acoustic waveguide employing lithium niobate thin films. Utilizing a C3v symmetry-breaking mechanism, the topological PnC acoustic waveguide is achieved, operating at frequencies exceeding 430 MHz. A SH0 mode acoustic transceiver is designed, enabling highly efficient on-chip acoustic wave transmission and reception. The fabricated topological PnC waveguide demonstrates a propagation loss of 11.3 dB/mm at the edge mode. An acoustic beam splitter utilizing topological edge mode has been demonstrated, showing the configurability of the topological PnC acoustic waveguide. These results offer significant promise for advancing the development of hybrid phononic circuits tailored for high-frequency acoustic information processing, sensing, and manipulation.

Underwater Low-Frequency Acoustic Wave Detection Based on a High-Q CaF2 Resonator

Whispering gallery mode (WGM) resonators with an ultra-high quality (Q) factor provide a new idea for high-precision underwater acoustic sensing. However, acoustic energy loss due to watertight encapsulation has become an urgent problem for its underwater application. In order to solve this problem, this paper proposes a hollowed-out array structure. The finite element simulation shows that the acoustic wave transmission loss is improved by 30 dB compared with that of the flat plate encapsulation structure. Using a calcium fluoride (CaF2) resonator with a Q factor of 1.2 × 108 as an acoustic sensitive unit, the amplitude and frequency of the loaded acoustic wave are retrieved by means of the dispersion coupling response mechanism. The resonator’s underwater experimental test range is 100 Hz–1 kHz, its acoustic sensing sensitivity level reaches −176.3 dB re 1 V/µPa @ 300 Hz, and its minimum detectable pressure can be up to 0.87 mPa/Hz1/2, which corresponds to a noise-equivalent pressure (NEP) of up to 58 dB re 1 µPa/Hz1/2.

Improved YOLOv7 model for underwater sonar image object detection

Underwater object detection technology for sonar images is widely employed and in high demand for civil and military purposes. However, due to the inhomogeneity of the seawater medium, which causes attenuation and distortion of the acoustic signal, achieving ideal performance for sonar object detection approaches is challenging. Furthermore, the process of acoustic wave transmission is further complicated by floating objects and particles, resulting in increased multipath effects. This study proposes an object detection method named YOLOv7C, which is based on deep learning to address these challenges. An attention mechanism is incorporated into the backbone network of the model to improve its ability to handle complex backgrounds in sonar images and effectively extract features. In addition, to facilitate high-order interaction between key features, the Neck part of the network integrates Multi-GnBlock blocks. Model redundancy pruning is used to substantially reduce the model size while maintaining high detection accuracy, thereby enhancing real-time performance. The proposed YOLOv7C achieves a 1.9% increase in the mean average precision, reduces the model memory by 47.50% after pruning, and enhances the detection speed by nearly 2.5 times compared with the YOLOv7C. These findings indicate that the success rate of multi-object detection is significantly enhanced by the attention mechanism and the new module. Additionally, the model can be controlled within a reasonable size by employing appropriate pruning methods.

Stepless space-regulation of topological acoustic controller with high fault tolerance

In this paper, the stepless space-regulation of topological acoustic transmission channels with high fault tolerance is proposed through introducing structural defect dislocations into a topological acoustic controller. Due to the stability of topological order against local disturbance, the acoustic wave transmission is immune to dislocation boundaries with strong stability, and thus the topological acoustic controller has high fault tolerance. By continuous changing the dislocation, the position relationship between the outgoing and incident acoustic signals no longer limited to the integer multiple distance related to the lattice size, and can realize the efficient acoustic energy transmission without energy loss at the fractional multiple distance, that is, the topological controller can realize lossless acoustic energy transmission and reception in arbitrary position relationship. Furthermore, the coupling relationship between the defect dislocation and the topological acoustic channel is explored, which can realize the stepless space-regulation of the lossless channel in the wide band range. In addition, by further introducing multi-layer continuous dislocations, this high-fault-tolerant topological acoustic controller still has strong stability, and multiple error factors do not affect the transmission results, which greatly reduces the difficulty of manufacturing. Finally, the stepless space-regulation of topological acoustic channels and the high-fault-tolerant topological acoustic controller that are easy to manufacture are verified by our experiments. This research paves the way for the engineering applications of acoustic micro-control, micro-nano fabrication, remote acoustic energy transmission manipulation, acoustic measurement, weak signal processing, acoustic flexible control and other micro-shape and multi-functional acoustic devices, and will bring more inspiration to other classical wave communication fields such as light wave, electromagnetic wave and so on.

Nonreciprocal Intelligent Soundproof Barrier with Active Nonlocal Acoustic Metastructure

Sound insulation is an important issue in daily life and has applications in various scenarios. Conventional acoustic passive metamaterial barriers are designed as a reciprocal sound insulation. However, for some specific application scenarios, unidirectional acoustic insulation is required, which is an enormous challenge for breaking the reciprocity of sound transport with conventional passive metamaterials. Here, a soundproof barrier with nonlocal acoustic metastructure is proposed, which consists of a microcontroller to connect a pair of spatially separated microphones and speakers, to tailoring the acoustic wave transmission for realizing nonreciprocal acoustic insulation. The theoretical calculation and experiment measurement indicated that the active acoustic barrier with a selectable working frequency can realize the suppressive effect in one direction and the enhancive effect in the other direction for an incident acoustic signal. Particularly, the function of an active soundproof barrier can be freely switched to forward, backward, and bidirectional sound insulation by tailoring the nonlocal distance of the digital meta‐atom. Furthermore, this acoustic metastructure is extended from a one‐dimentional waveguide to a two‐dimentional plane to illustrate that it is still valid in an open‐field environment. The proposed customizable nonreciprocal soundproof barriers provide an avenue for many applications in the specific scenarios that require unidirectional sound insulation and high air permeability.

Acoustic vortex filter based on tunable metasurfaces

In this paper, we present an acoustic vortex filter (AVF) based on tunable metasurfaces, which can selectively filter the incident multiplexed vortices that carry different orbital angular momentum (OAM). Our metasurface-based AVF is composed of an upper acoustic metasurface (UAM) and a lower acoustic metasurface, of which the intrinsic topological charge (ITC) can be tuned by mechanically rotating the UAM along its central axis. Due to the critical order of the propagating vortex modes in waveguide, controlling the ITC of the AVF allows for the selective filtering of incoming multiplexed acoustic vortex beams based on the sound vortex diffraction in phase-gradient metasurface, which endows the vortex filter the capability that let the incident vortex of specific OAM pass through it. In the following demonstration, both in theory and experiment, we design the AVF and effectively filter the acoustic vortices with two opposite topological charges by simply altering the orientation angle of the UAM. Based on this, we further demonstrate its application in asymmetric acoustic wave transmission. Our work offers an approach to selectively filter the incident acoustic vortex, which improves the capability to control the acoustic OAM via metasurfaces.

Phase variation of Laguerre-Gaussian vortex beams in a homogeneous atmospheric medium under finite amplitude acoustic wave perturbation

In this article, we have derived the acoustic pressure and medium refractive index expressions in a homogeneous atmospheric medium perturbed by a planar finite amplitude acoustic wave. In a planar finite amplitude acoustic wave perturbation, we developed a Laguerre–Gaussian vortex beam transmission model in a homogeneous atmospheric medium. We investigated the effects of different acoustic source parameters on the phase of the Laguerre–Gaussian vortex beam transmission, considering the atmospheric medium’s viscous effect. The results show that acoustic waves of finite amplitude distort the refractive index distribution of a homogeneous atmospheric medium. At a given distance, the amplitude of the refractive index gradually increases with increasing acoustic wave transmission distance. At the same time, the phase of the Laguerre–Gaussian vortex beam is rotated by the perturbation of the finite-amplitude acoustic wave, and the phase always returns to its initial position. Unlike linear acoustic waves, changes in the homogeneous atmospheric refractive index distribution and the homogeneous phase of the Laguerre–Gaussian vortex light no longer satisfy the periodic variation when perturbed by finite-amplitude acoustic waves. Under the same conditions, the effect of finite-amplitude acoustic waves on the phase of the Laguerre–Gaussian vortex light is stronger than that of linear acoustic waves. Finally, the effects of different acoustic pressure and frequency of the source on the phase of the Laguerre–Gaussian vortex beam transmission are calculated. The results show that different acoustic parameters at the source can be used to achieve phase modulation at different distances and intensities.