Acoustic System Research Articles

Experimental application of heterogeneous gliders communication system in South China Sea

This study presents an underwater acoustic communication system based on heterogeneous gliders. The system consists of an underwater unit integrated into an underwater glider and a surface unit integrated into a surface wave glider. This setup enables real-time information exchange across different media. This study details the adaptive integration method and information exchange protocol of the underwater acoustic communication system implemented on the heterogeneous glider. To validate the feasibility of this integration, sea trials are conducted in the South China Sea. Additionally, the communication performance of the heterogeneous glider integrated with the underwater acoustic communication system is analyzed thoroughly. This allows for information communication between underwater, surface, space-based, and shore-based components. The results of this study lay a strong foundation for the development cooperative network intelligent monitoring of heterogeneous gliders.

Parametric Doppler correction for wayside array acoustic signal via short-time reconstruction

The trackside acoustic detection system (TADS) plays a vital role in vehicle bearings condition monitoring. However, the inevitable Doppler distortion embedded in collected data will bring considerable difficulties to defect inspection and diagnosis in the system. The distortion elimination approaches mainly achieve spectrum recovery based on time-domain interpolation resampling (TIR) in a data-driven way. These will be further limited by the requirement to signal to noise ratio (SNR) or calculation speed. Considering the principle of wayside acoustic physical model and the benefits of array acoustic in practice, this study proposes an adaptive parametric Doppler correction (PDC) scheme based on short-time reconstruction (STR), including perception modeling, inverse perception optimization and Doppler correction. Firstly, mathematical modeling with multiple perception operators, including acoustic amplitude modulation operator, frequency modulation operator and array time delay operator, a wayside acoustic physical model based on array sensing is established. Secondly, through the corresponding inverse multiple perception operators, a transition signal with frequency-domain energy concentrated is obtained for the optimal moving parameters searching. Thirdly, within short-time sequence segments of the sound source, the real-time position recovery is realized via the proposed STR with formulaic propagation delay compensation. Theoretically, it can be seen that the proposed PDC scheme can simultaneously recover the amplitude, frequency distribution and phase of the Doppler signal, which can be applicable to all wayside acoustic diagnosis scenarios. With the correction analysis of simulation and experimental array defect signals, it can be confirmed that the proposed STR-based PDC scheme is effective for Doppler signal recovery in high fidelity, and has great potential to the real-time diagnosis of TADS.

Block-flexure toppling in an anaclinal rock slope based on multi-field monitoring

Toppling is a widespread failure mode in natural and excavated anaclinal rock slopes and threatens the construction and operation of important infrastructure such as hydropower and transportation corridors in southwest China. Therefore, comprehending the mechanisms underlying toppling is essential for relevant landslide prediction and prevention. In this study, we developed a physical model of an anaclinal rock slope using the Linda landslide as a site case. Based on field monitoring using Gopro cameras, high-speed cameras, strain sensors, stress sensors, and acoustic emission systems, the evolution of the anaclinal rock slope model was analysed. The reliability of the physical model test was verified by comparing the deformation characteristics of the landslide site with those of the slope model. The monitoring results suggested that the slope deformation process could be divided into five stages: an initial interlayer dislocation stage, a deformation initiation stage, a crack generation and propagation stage, a crack penetration stage, and a failure stage. The rock mass could be categorised into four deformation zones: the fresh zone, weakly toppled zone, moderately toppled zone and highly toppled zone. Acoustic emission sensors deployed near the failure-prone region held the potential to serve as early warning indicators for landslides on anaclinal rock slopes. Valley incision played a significant role in the formation of sliding surfaces in anaclinal rock slopes. Furthermore, the model experiment observed multiple failure surfaces and the failure behaviour of the landslide rock mass, shedding light on their connection to the deformation process and the stress state in the model. The study revealed the deformation and failure mechanism of an anaclinal rock slope from many perspectives and deepened our understanding of toppling type of landslides.

A mixture of artificial and biological sounds improves the effective range of an acoustic repellent for an invasive lizard species

AbstractFurther range expansion of invasive animal species can be prevented by controlling their behavior. Acoustic repellent is a promising approach to deter problematic animals from ecologically sensitive areas. To develop an acoustic repellent system for a green anole that was introduced to the Ogasawara islands in Japan, this study evaluated the deterrent effect of (1) a pattern sound of machine noise and (2) a mixture of artificial and biologically relevant sounds. We created a sound level gradient inside a small experimental cage in a laboratory setting and measured whether green anoles avoided the vicinity of a speaker. In approximately 80% of cases, both the pattern machine sound and the mixture sounds prevented green anoles from stepping into the vicinity of a speaker (<24 cm). The mixture sounds maintained the deterrent effect at a middle distance from a speaker (<72 cm), whereas the pattern machine sound did not work as a strong acoustic repellent at this distance. These results imply that the mixing of biotic and abiotic sounds can improve the effective range of acoustic repellent for green anoles. However, several shortcomings of the acoustic repellent system were also highlighted. Since a green anole is an insectivore predator, our findings will contribute to protecting endangered native insect fauna from the predation of non‐native lizard species.

Turning the tide: understanding estuarine detection range variability via structural equation models

Insight into the detection range of acoustic telemetry systems is crucial for both sampling design and data interpretation. The detection range is highly dependent on the environmental conditions and can consequently be substantially different among aquatic systems. Also within systems, temporal variability can be significant. The number of studies to assess the detection range in different systems has been growing, though there remains a knowledge gap in estuarine habitats. In this study, a 2-month experimental set-up was used to assess the detection range variability and affecting environmental factors of an estuary. Given the expected complex interplay of different factors and the difficulties it entails for interpretation, a structural equation modelling (pSEM) approach is proposed. The detection range of this estuarine study was relatively low and variable (average 50% detectability of 106 m and ranging between 72 and 229 m) compared to studies of riverine and marine systems. The structural equation models revealed a clear, yet complex, tidal pattern in detection range variability which was mainly affected by water speed (via ambient noise and tilt of the receivers), water depth and wind speed. The negative effect of ambient noise and positive effect of water depth became more pronounced at larger distances. Ambient noise was not only affected by water speed, but also by water depth, precipitation, tilt angle and wind speed. Although the tilt was affected by water speed, water depth and wind speed, most of the variability in tilt could be traced back to the receiver locations. Similarly, the receiver locations seemed to explain a considerable portion of the detection range variability. Retrospective power analyses indicated that for most factors only a minor gain in explanatory power was achieved after more than two days of data collecting. Redirecting some of the sampling effort towards more spatially extensive measurements seems to be a relevant manner to improve the insights in the performance of telemetry systems in estuarine environments. Since the low and variable detection range in estuaries can seriously hamper ecological inferences, range tests with sound sampling designs and appropriate modelling techniques are paramount.

Dimensionless Groups by Entropic Similarity: II-Wave Phenomena and Information-Theoretic Flow Regimes.

The aim of this study is to explore the insights of the information-theoretic definition of similarity for a multitude of flow systems with wave propagation. This provides dimensionless groups of the form Πinfo=U/c, where U is a characteristic flow velocity and c is a signal velocity or wave celerity, to distinguish different information-theoretic flow regimes. Traditionally, dimensionless groups in science and engineering are defined by geometric similarity, based on ratios of length scales; kinematic similarity, based on ratios of velocities or accelerations; and dynamic similarity, based on ratios of forces. In Part I, an additional category of entropic similarity was proposed based on ratios of (i) entropy production terms; (ii) entropy flow rates or fluxes; or (iii) information flow rates or fluxes. In this Part II, the information-theoretic definition is applied to a number of flow systems with wave phenomena, including acoustic waves, blast waves, pressure waves, surface or internal gravity waves, capillary waves, inertial waves and electromagnetic waves. These are used to define the appropriate Mach, Euler, Froude, Rossby or other dimensionless number(s)-including new groups for internal gravity, inertial and electromagnetic waves-to classify their flow regimes. For flows with wave dispersion, the coexistence of different celerities for individual waves and wave groups-each with a distinct information-theoretic group-is shown to imply the existence of more than two information-theoretic flow regimes, including for some acoustic wave systems (subsonic/mesosonic/supersonic flow) and most systems with gravity, capillary or inertial waves (subcritical/mesocritical/supercritical flow). For electromagnetic wave systems, the additional vacuum celerity implies the existence of four regimes (subluminal/mesoluminal/transluminal/superluminal flow). In addition, entropic analyses are shown to provide a more complete understanding of frictional behavior and sharp transitions in compressible and open channel flows, as well as the transport of entropy by electromagnetic radiation. The analyses significantly extend the applications of entropic similarity for the analysis of flow systems with wave propagation.

An improved acoustic transponder system via LCCLC impedance matching network and equalization control strategy

AbstractThe underwater acoustic transducer (UAT) generates a large amount of reactive power during the operation, greatly limiting the output capability of the power amplifier. It is necessary to match the UAT and improve its load characteristics. The conventional design methods are not powerful enough to solve nonlinear or parameter‐sensitive problems, lacking enough convergence ability for the network design problem. This article proposes an optimization design method for LCCLC impedance matching network based on the improved chaos optimization algorithm and the corresponding equalization control strategy. First, the impedance model of the UAT is proposed, and then the matching principle of the LCCLC network is analyzed. Based on these, the optimization design for LCCLC network is described in detail. Then, to solve the problem of the calculation of the command signal, a control method based on the FIR filter principle is proposed. Finally, the proposed methods are verified by an experimental platform. The results show that the proposed design method and its corresponding control strategy successfully solve the matching and emission problems.

Optimization of Aspergillus versicolor Culture and Aerosolization in a Murine Model of Inhalational Fungal Exposure.

Aspergillus versicolor is ubiquitous in the environment and is particularly abundant in damp indoor spaces. Exposure to Aspergillus species, as well as other environmental fungi, has been linked to respiratory health outcomes, including asthma, allergy, and even local or disseminated infection. However, the pulmonary immunological mechanisms associated with repeated exposure to A. versicolor have remained relatively uncharacterized. Here, A. versicolor was cultured and desiccated on rice then placed in an acoustical generator system to achieve aerosolization. Mice were challenged with titrated doses of aerosolized conidia to examine deposition, lymphoproliferative properties, and immunotoxicological response to repeated inhalation exposures. The necessary dose to induce lymphoproliferation was identified, but not infection-like pathology. Further, it was determined that the dose was able to initiate localized immune responses. The data presented in this study demonstrate an optimized and reproducible method for delivering A. versicolor conidia to rodents via nose-only inhalation. Additionally, the feasibility of a long-term repeated exposure study was established. This experimental protocol can be used in future studies to investigate the physiological effects of repeated pulmonary exposure to fungal conidia utilizing a practical and relevant mode of delivery. In total, these data constitute an important foundation for subsequent research in the field.

Multichannel resonant acoustic rheometry system for quantification of coagulation of multiple human plasma samples

Resonant Acoustic Rheometry (RAR), a newly developed ultrasound-based technique for non-contact characterization of soft viscoelastic materials, has shown promise for quantitative viscoelastic assessment of temporally changing soft biomaterials in real time, and may be used to monitor blood coagulation process. Here, we report the development of a novel, multichannel RAR (mRAR) system for simultaneous measurements of multiple temporally evolving samples and demonstration of its use for monitoring the coagulation of multiple small-volume plasma samples. The mRAR system was constructed using an array of 4 custom-designed ultrasound transducers at 5.0 MHz and a novel electronic driving system that controlled the generation of synchronized ultrasound pulses for real time assessment of multiple samples simultaneously. As a proof-of-concept of the operation of the mRAR system, we performed tests using pooled normal human plasma samples and anti-coagulated plasma samples from patients treated with warfarin with a range of International Normalized Ratio (INR) values as well-characterized samples with different coagulation kinetics. Our results show that simultaneous tracking of dynamic changes in 4 plasma samples triggered by either kaolin or tissue factor was achieved for the entire duration of coagulation. The mRAR system captured distinct changes in the samples and identified parameters including the clotting start time and parameters associated with the stiffness of the final clots that were consistent with INR levels. Data from this study demonstrate the feasibility of the mRAR system for efficient characterization of the kinetic coagulation processes of multiple plasma samples.

An accelerated deflation preconditioner for acoustic BEM systems based on subspace recycling

Following a classic Krylov subspace recycling [1] technique in the context of frequency sweep analyses performed with the acoustic BEM [2] might inflict unnecessary overhead costs. To speed up such a procedure, this work employs an accelerated recycling technique that is based on the recently proposed model order reduction framework for BEM systems [3]. Specifically, employing an affine approximation of a BEM system in combination with a Galerkin projection on the deflation basis, the operation of constructing the corresponding deflation based preconditioner is significantly accelerated. The efficiency of the deflation basis for the entire frequency range is guaranteed through an Automatic Krylov subspace Recycling (AKR) [4] algorithm, thus leading to a drastic decrease of the number of iterations required by an iterative solver. The proposed approach is tested on an academic BEM example and achieves significant acceleration of the computed frequency sweep by ensuring fast convergence of the employed iterative solver, avoiding overhead projection costs.

Compact reverse time migration: A real-time approach for full waveform ultrasound imaging for breast.

We present compact reverse time migration (CRTM), a real-time ultrasound imaging method that can exploit the full waveform information of ultrasonic wave records for imaging breast tissue. Conventional reverse time migration (RTM) computes the gradient of the reflective ultrasound data with respect to the perturbation of the velocity model of the soft tissues and the gradient can indicate the interface between different types of body tissue. In contrast to conventional reflection ultrasound (B-mode), which is based on the high-frequency approximation to the wave equation, the RTM algorithm is based on the complete wave equation, and can thus exploit the full waveform (wide-spectrum) information of the data and provide an image with higher resolution. Unfortunately, the computational burden of RTM is noticeably higher than the ray-based B-mode. This precludes real-time applications, one of the most important features of ultrasound imaging. The proposed CRTM algorithm can significantly reduce the computational costs of RTM, such that it can be applied for real-time imaging. We demonstrate the performance of CRTM through a synthetic experiment of ultrasound breast imaging. CRTM can be potentially adapted to related signal-processing fields, such as seismic imaging, acoustic camera systems, and radar imaging.

Оptimization of the parameers of the placement of elements of the acoustic system for orientation of rescuer's equipment

Experimentally determined correction values of the distance to the obstacle depending on the acoustic impedance of the environment for the acoustic device of the rescuer's equipment. The measurement results were obtained using the developed experimental setup, which took into account, in real time, changes in acoustic impedance and temperature of the environment using a two-channel temperature meter and an optical penetration sensor of the environment. The temperature of the environment (in the confined space) varied from 20 C to 60 C, and the optical penetration index from 0 to 100 %, where 100 % corresponds to complete optical opacity of the environment. Dependencies of the propagation of acoustic waves upon changing the optical permeability of the medium and temperature were obtained. The correction value for the distance to the obstacle calculated by the acoustic device at a distance of 1000 mm was (+0,013 m). The relative error during the measurements did not exceed 2 %. It was found that when the wave impedance increases, the indicators of the distance to the obstacle decrease, so the corrective dependence has a positive value. The obtained results make it possible to increase the reliability of the readings of the acoustic device as an additional equipment of the rescuer. The data obtained as a result of the experiment make it possible to display the shape of the obstacle in more detail. Approximating polynomials of the reflection coefficient of acoustic waves depending on the volume content of inclusions at angles of incidence from 0 °С to 30 °С have been determined. The use of the obtained polynomials allows to increase the speed of the program code of the control microcontroller of the acoustic device. The obtained dependencies are taken into account in the calculation algorithm of the program code of the microcontroller of the acoustic device for determining the shape and distance to the obstacle, which makes it possible to increase the efficiency of the rescuer's orientation in conditions of unsatisfactory visual control during emergency rescue operations.

Deep Learning-based drone acoustic event detection system for microphone arrays

Deep Learning-based drone acoustic event detection system for microphone arrays

Self-Interference Cancellation Techniques for In-Band Full-Duplex Wireless Communication Systems: A Review

In-Band Full-Duplex (IBFD) systems have the capability of simultaneously transmitting and receiving signals through the channel and require the same resources as half-duplex systems. Unfortunately, IBFD systems have self-interference (SI) issues that prevent the system from gaining double throughput with respect to half-duplex systems. Therefore, the IBFD system will be more reliable if SI is mitigated more. This contribution will look at SI cancellation in wireless radio and underwater acoustic systems. The reviewed documents cover all types of SI cancellations, including passive, analog, and digital cancellations. In a practical full-duplex system, the SI cancellation for all domains must cancel the SI below the receiver noise floor.

Generation of high-order focused acoustic vortices and multiplexed beams using Dual-Channel metamaterials

Focused vortex beams have attracted considerable research attention due to their unique acoustic properties, and have been explored in medical imaging, biomedical therapy, and particle manipulation. Here, an acoustic metamaterial vortex generator (AMVG) is designed to realize a multiplexed focusing acoustic vortex (MFAV) with multiple-order topological charges (TCs). The proposed AMVG is composed of several fanlike sectors with two high transmission channels per unit, which can flexibly modulate the transmitted phase shift in two separate frequency bands. In contrast to conventional acoustic metamaterial-based vortices, the design strategy provides a new degree of freedom, i.e., frequency, that may extend to the agile tailoring of multi-band independent vortices, significantly enhancing the information encoded in the acoustic metamaterial. Acoustic transmission and phase shift of the dual-channel unit are investigated theoretically and demonstrated in simulations using the finite element method. The focal position and TC of the MFAVs can be modulated by simply adjusting the cavity length of the unit cell and even only the sector order. Furthermore, we implement three-dimensional anechoic experiments to verify the effectiveness of the off-axial MFAVs by the designed AMVG. These multiplexed focusing vortices offer a technical advance to tackle the rising challenges in the fields of acoustic signal processing and communication systems.

Unidirectional Negative Refraction at an Exceptional Point of Acoustic PT-Symmetric Systems

We demonstrate a method to realize unidirectional negative refraction in an acoustic parity-time (PT)-symmetric system, which is composed of a pair of metasurfaces sandwiching an air gap. The pair of metasurfaces possesses loss and gain modulations. The unidirectional negative refraction, which is strictly limited to the case of incident wave imposing on the loss end of the metasurface, is demonstrated at the exception point (EP) in this PT-symmetric system, while the incidence from the other side leads to strong reflection. Based on rigorous calculations, we explicitly show the underlying mechanism of this model to achieve unidirectional wave scatterings around the EP in the parametric space. In addition, the perfect imaging of a point source in the three-dimensional space, as a signature of negative refraction, is simulated to provide a verification of our work. We envision that this work may sharpen the understanding of PT-symmetric structures and inspire more acoustic functional devices.

Mechanical and Acoustic Emission Characteristics of Grouted Reinforcement in Fissure-Containing Rock-like Specimens

In order to study the reinforcing effect of the different grouting materials applied in fissure rock engineering, ultra-fine cement slurry, cement–silicate slurry, and MARITHAN® were used to carry out grouting tests on specimens of fissure-containing rocks. With the help of a uniaxial compression acoustic emission test system, the mechanical characteristics of the grouted specimens were obtained, and the damage process of the specimens was revealed by using the acoustic emission signals. The tested results showed the following: the residual strength of the grouted specimens using the three grouting materials increased by 16.931%, 13.075%, and 39.998%, respectively; the ultra-fine cement grouting and cement–silicate grouting specimens showed damage patterns of shear-slip damage along the original rupture surface; the specimens of MARITHAN® grouting cracked from a position near the end of the specimen with no damage to the grouted body portion; the cumulative acoustic emission energy curves of the grouted specimens showed obvious stage characteristics; and the acoustic emission energy distribution characteristics of the grouted specimens differed depending on the grouting materials.

Acoustic emission with machine learning in fracture of composites: preliminary study

In this paper, preliminary studies on the failure analysis of hybrid composite materials utilizing acoustic emission and machine learning are presented. The main purpose of this study was to analyze the possibilities of using machine learning techniques as a way to better cluster the data obtained from acoustic emission. In this paper, we focus on data preparation, feature extraction (Laplacian score), determination of cluster number (Caliński–Harabasz, Silhouette, and Davies–Bouldin), and testing three clustering techniques, namely K-means, fuzzy C-means, and spectral clustering. The dataset was obtained by testing fiber metal laminates—composites consisting of metal and composite layers. Two experimental tests were realized on pre-cracked rectangular specimens—one with loading in mode I and one with loading in mode II (DCB—double cantilever beam and ENF—end-notch flexural test). Elastic waves were recorded during these tests via an acoustic emission system. Preliminary studies show that the proposed method can be used successfully to cluster data obtained in this way. The obtained dataset was split into 3 clusters (for the ENF test) and 5 clusters (DCB test). In the next stages of the research campaign, based on the presented results, we intend to change the approach to semi-supervised by running additional single-cause damage tests to enhance the achieved results and enable easier damage recognition.

A hybrid energy harvesting framework and graphene‐based supercapacitor for 6G and smart grid networks

SummaryThis paper proposes a novel hybrid energy harvesting framework integrated with a graphene‐based supercapacitor to address the energy demands of 6G communication systems and smart grid networks. To ensure consistent power generation, the proposed framework combines diverse energy harvesting mechanisms, including acoustic, vibration, and radio frequency (RF) energy sources. These harvested energies are then efficiently managed and stored in a proposed graphene‐based supercapacitor compared with existing Li‐ion batteries, due to its high energy density and rapid charge‐discharge capabilities. Smart grids and 6G networks can utilize the energy that hybrid systems harvest. This paper examines the analysis of RF energy extracted from various antenna configurations. In the acoustic energy harvesting system, energy extraction has been achieved by subjecting it to acoustic pressure and impedance. Notably, the inclusion of acoustic impedance has resulted in a greater amount of harvested energy. The vibration energy harvesting analysis with angular frequencies under various force conditions is employed. The magnitude of force applied to the harvesting system significantly influences the efficiency of the harvested energy. The three‐dimensional structure and voltage levels of the graphene‐based supercapacitor have been examined for various electrodes. For maximizing the harvested hybrid energy, convex optimization is formulated due to its ability to efficiently navigate complex design spaces while ensuring reliable and globally optimal solutions. CVX tool in MATLAB is used for validation. The results improve the energy harvesting efficiency and enhance the power availability of all the harvesting sources. Furthermore, the compatibility of the proposed framework with existing network infrastructure highlights its potential for seamless integration into real‐world communication and energy distribution systems.

Tunable bifunctional acoustic logic gates based on topological valley transport

Valley degree of freedom has attracted great interest in the realization of topological edge states in acoustic systems owing to its rich valley-contrasting physics and great potential applications. However, the practice of valley acoustic topological insulators (ATIs) in designing tunable multifunctional devices without changing their structures still remains a great challenge. Here, we show that the antisymmetric and symmetric distribution nature of valley edge states in the valley ATIs with two different domain walls can be utilized to design tunable robust acoustic logic gates (ALGs). We experimentally demonstrate two types of tunable bifunctional ALGs (denoted as ALG-I and ALG-II), in which ALG-I is composed of a single domain wall, and ALG-II is constructed by a bent topological waveguide containing two domain walls. For ALG-I, the functions of logical inclusive OR and logical exclusive OR (denoted as OR and XOR, respectively) can be switched by actively tuning the phases of two input sound sources without changing the structure. For ALG-II, the logic functions OR and XOR can be implemented through the left and right incidences, respectively, of a pair of sound sources. Similarly, the switching of the logic functions OR and XOR on both sides of ALG-II can be realized by simply adjusting the phases of two sound sources. The designed ALGs have the advantages of simple structure, high robustness, as well as active tunability, leading to a wide range of potential applications in integrated acoustics, acoustic communications, and information processing.