Acoustic Method Research Articles

Acoustic tomographic inversion of 3D temperature fields with mesoscale anomaly in the South China Sea

Acoustic tomographic inversion is based on travel times measured along the transmission paths between all station pairs to reconstruct three-dimensional temperature structures with mesoscale anomalies. In this study, tomographic simulation experiments were designed based on the Hybrid Coordinate Ocean Model (HYCOM) reanalysis data to reconstruct mesoscale phenomena from travel time data obtained from five, seven, and nine stations in the South China Sea over a domain of 100 × 100 km. The travel times for each station pair were calculated in the vertical section using the Bellhop acoustic ray simulation method. Six Empirical orthogonal function (EOF) modes of sound speed along the sound transmission paths in a vertical slice were used to formulate the inversion equations. The horizontal-slice distributions of temperature in the tomography domain were reconstructed using the grid-segmented method for each depth layer. For station-to-station distances greater than 100 km, the performance of inversion was best for the seven-station case rather than for the nine-station case, with the highest horizontal resolution of the three cases. This case study concluded that the seven-station case rather than the nine-station case provided an optimal station number for reconstructing the three-dimensional temperature fields.

A transformer acoustic signal analysis method based on matrix pencil and hybrid deep neural network

Acoustic signal analysis is an important component of transformer online monitoring. Currently, traditional methods have problems such as low spectral resolution, imbalanced sample distribution, and unsatisfactory classification performance. This article first introduces the matrix pencil algorithm for time-frequency spectrum analysis of acoustic signals, and then uses the SMOTE algorithm to expand the imbalanced samples. Then, an ACmix hybrid deep neural network model is constructed to classify 11 types of transformer operation and environmental acoustic signals. Finally, detailed experiments were conducted on the method proposed in this paper, and the experimental results showed that the matrix pencil algorithm has high time-frequency resolution and good noise resistance performance. The SMOTE sample expansion method can significantly improve the recognition accuracy by more than 2%. Overall accuracy of the proposed method in acoustic signal classification tasks reaches 91.81%.

Acoustic Imaging Method for Gas Leak Detection and Localization Using Virtual Ultrasonic Sensor Array.

An acoustic imaging method for detecting and locating gas leaks based on a virtual ultrasonic sensor array is proposed and experimentally demonstrated. A scanning sensor array of only two sensors is used to collect the acoustic signals generated by the leakage hole. The matrix of the leakage signal is processed by the cross-power spectrum method to achieve time consistency, afterward, the location of the leakage source can be calculated by the virtual beamforming method. The influence of the number of sensors and the distance between adjacent sensors on the effect of the proposed method are compared and discussed. To verify the effectiveness and operability of the detection and localization method, several experiments were carried out. Furthermore, a series of experiments were conducted to assess the accuracy and stability of this method. The experimental results demonstrate that the proposed method based on a virtual sensor array can achieve highly accurate localization of gas leaks and performs well regarding stability.

A rigorous real-time acoustic positioning method for ocean bottom seismic exploration

The conventional technique for positioning seafloor geophones in ocean bottom seismic exploration encounters several challenges, including the significant impact of outliers on positioning results, underutilization of high-precision observations, and low efficiency in real-time data processing. These issues inevitably affect the quality of seismic exploration outcomes. To address these challenges and enhance the accuracy of geophone positioning, this paper proposes a rigorous real-time acoustic positioning method for geophones based on sequential adjustment and Baarda's outlier detection approach. The proposed method comprises three key steps: grouping the original acoustic observations, constructing the intra-group acoustic positioning model, and synthesizing the positioning results across the different groups. The validity and practicality of this approach are confirmed through a simulation experiment as well as the field experiment conducted in the Bohai Sea, China. The results demonstrate that the proposed method effectively eliminates outliers in the original observations and maximizes the utilization of high-quality observations. Compared to traditional acoustic positioning methods, it significantly reduces positioning errors from meters to decimeters, and in some cases can achieve centimeter-level precision. When the sound velocity profile in the operating sea area is measured, the method can attain the posterior standard deviation at the millimeter level and positioning errors within 10 cm. When the sound velocity profile is unknown, the method can achieve the posterior standard deviation at centimeter-level and positioning errors of approximately 20 cm.

Analysis and development of a mathematical model of the acoustic method for monitoring downhole parameters of the drilling process

Analysis and development of a mathematical model of the acoustic method for monitoring downhole parameters of the drilling process

Mechanical behavior of fiber-glass plastic with hole pattern using digital image correlation and acoustic emission methods

In this paper, tensile tests of specimens with a pattern of holes made of fiber-glass plastic based on combined epoxy and phenol-formaldehyde resins are carried out in order to study the processes of damage accumulation and tension fracture. The Vic-3D video system is used to evaluate damage development and inhomogeneity of strain localization during loading. Continuous recording of acoustic emission signals is carried out during the tests, resulting in obtaining data on fracture mechanisms in the material. Ranges of peak frequencies are identified. Surface analysis of specimens was carried out using a microscope. A significant reduction in strength occurs due to the presence of a circular hole in the material, although additional holes do not exacerbate this effect. Fracture patterns of specimens with a hole pattern have been analyzed, and different "paths" of fracture have been observed. The comparison of strain fields obtained on the basis of application of three-dimensional digital optical system with the configuration of strain fields constructed as a result of numerical modeling by the finite element method has been carried out. It is found that the strain fields for different open hole patterns are quantitatively and qualitatively similar and identical.

Origin analysis of paleo-overpressure in source rocks based on logging response characteristics: a case study of the Chang 7 member in the Triassic Yanchang formation, Longdong area, Ordos Basin, China

The identification of the origins of source rock palaeo-overpressure based on logging response parameters is frequently influenced by the presence of organic matter. To accurately identify the paleo-overpressure origin of source rocks and employ an appropriate method for paleo-pressure calculation, this study proposes a quantitative approach to assess the influence of organic matter content on overpressure analysis. The findings demonstrate that the presence of organic matter in Chang 7 shale leads to an increase in acoustic time difference and a decrease in density. After incorporating the multi-component rock equivalent volume model correction, it is evident that the paleo-overpressure observed in the Chang 7 member is not attributed to undercompaction but rather to fluid expansion mechanisms. In conjunction with the acoustic velocity-density palte method, the paleo-overpressure of the Chang 7 member is attributed to undercompaction and expansion resulting from hydrocarbon generation. The pressure evolution of the Chang 7 member has been reconstructed based on the identification of its paleo-overpressure origin. The distribution characteristics of paleo-pressure recovered based on hydrocarbon generation expansion exhibit a strong correlation with the reservoir. The reliability of the correction method for organic matter influence is demonstrated. The proposed method is not only applicable for the investigation of paleo-pressure, but also holds significant implications for the assessment of pressure within organic-rich intervals.

Design sensitivity analysis of modal frequencies of elastic structures submerged in an infinite fluid domain

SummaryThis paper presents a numerical approach for the design sensitivity analysis of modal frequencies of elastic structures submerged in an unbounded heavy fluid domain. Because the feedback of sound pressure onto the fluid‐loaded structures has to be taken into account in this case, a fully coupled scheme which combines the structural finite element method (FEM) and the acoustic boundary element method (BEM) is employed in the numerical simulation. The resulting nonlinear eigenvalue problem created by the coupled finite element and boundary element (FE‐BE) method is converted into a generalized eigenvalue problem (GEP) of reduced dimension by using a contour integral method. The design sensitivity formulation for non‐repeated eigenvalues is derived based on an adjoint method which uses both the left and right eigenvectors, and a small GEP is formed to calculate the gradients of repeated eigenvalues. The Burton‐Miller formulation is employed to shift the fictitious eigenfrequencies and their derivatives, and the parameter setting which is beneficial to the filtering of fictitious eigenfrequencies is investigated. Numerical examples are given to verify the accuracy and effectiveness of the developed method.

Assessment of the ability for early detection of newly hatched larvae of Hylotrupes bajulus L. using the acoustic emission method in Scots pine wood

The acoustic emission analysis method was used to determine the activity of very young Hylotrupes bajulus larvae in their long-term development. In the laboratory conditions the simulated scenario of a fresh, intense infestation inside the construction wood was evaluated. The sounds generated by the insects during their feeding on the wooden samples were processed by the measurement system, which was able to detect and count the larva-originated sound pulses and calculate related energy. So far, no one has examined possibilities of detecting infant larvae of Hylotrupes bajulus L. This work is a continuation of research on the influence of the insect mass on its AE-based detection. The experiments performed with multiple wood samples analyzed through the period of one year have shown dependency between the mass of the larva and the intensity of the sound generated by them. The moment of the earliest possible detection of infestation in the wooden structure was evaluated. In the appropriate conditions (large number of young larvae inside the wood and optimal temperature) the insects reach the mass of tens of mg, which makes them detectable using the AE method.

Advances in Respiratory Monitoring: A Comprehensive Review of Wearable and Remote Technologies.

This article explores the importance of wearable and remote technologies in healthcare. The focus highlights its potential in continuous monitoring, examines the specificity of the issue, and offers a view of proactive healthcare. Our research describes a wide range of device types and scientific methodologies, starting from traditional chest belts to their modern alternatives and cutting-edge bioamplifiers that distinguish breathing from chest impedance variations. We also investigated innovative technologies such as the monitoring of thorax micromovements based on the principles of seismocardiography, ballistocardiography, remote camera recordings, deployment of integrated optical fibers, or extraction of respiration from cardiovascular variables. Our review is extended to include acoustic methods and breath and blood gas analysis, providing a comprehensive overview of different approaches to respiratory monitoring. The topic of monitoring respiration with wearable and remote electronics is currently the center of attention of researchers, which is also reflected by the growing number of publications. In our manuscript, we offer an overview of the most interesting ones.

In-plane shear damages consideration of hoop wound composite cylinders using acoustic emission method

The objective of this study was to examine the in-plane shear properties of filament-wound composite cylinders and assess the associated damage mechanisms using acoustic emission techniques. Two distinct composite materials, namely carbon/epoxy and glass epoxy, were manufactured for this purpose. The cylinders were subjected to torsion load conditions in accordance with ASTM D5448. Throughout the testing process, various parameters such as torque, angle of torsion, and strain were meticulously recorded. Additionally, the acoustic emission sensors were utilized to capture signals indicating the occurrence of damages. The findings of the study indicate that the in-plane shear strength and shear modulus of the carbon/epoxy specimens surpass those of the glass/epoxy counterparts. The results from acoustic emission testing indicated that in the CFRP specimens, there were no instances of fiber/matrix debonding. Instead, the main mode of damage observed was fiber breakage, accounting for approximately 71% of the total damage detected. On the other hand, in the GFRP specimens, the primary damage mechanism was found to be fiber/matrix debonding, making up approximately 50% of the overall damage recorded.

Detecting bulbar amyotrophic lateral sclerosis (ALS) using automatic acoustic analysis

Automatic speech assessments have the potential to dramatically improve ALS clinical practice and facilitate patient stratification for ALS clinical trials. Acoustic speech analysis has demonstrated the ability to capture a variety of relevant speech motor impairments, but implementation has been hindered by both the nature of lab-based assessments (requiring travel and time for patients) and also by the opacity of some acoustic feature analysis methods. These challenges and others have obscured the ability to distinguish different ALS disease stages/severities. Validation of automated acoustic analysis tools could enable detection of early signs of ALS, and these tools could be deployed to screen and monitor patients without requiring clinic visits. Here, we sought to determine whether acoustic features gathered using an automated assessment app could detect ALS as well as different levels of speech impairment severity resulting from ALS. Speech samples (readings of a standardized, 99-word passage) from 119 ALS patients with varying degrees of disease severity as well as 22 neurologically healthy participants were analyzed, and 53 acoustic features were extracted. Patients were stratified into early and late stages of disease (ALS-early/ALS-E and ALS-late/ALS-L) based on the ALS Functional Ratings Scale-Revised bulbar score (FRS-bulb) (median [interquartile range] of FRS-bulbar scores: 11[3]). The data were analyzed using a sparse Bayesian logistic regression classifier. It was determined that the current relatively small set of acoustic features could distinguish between ALS and controls well (area under receiver-operating characteristic curve/AUROC = 0.85), that the ALS-E patients could be separated well from control participants (AUROC = 0.78), and that ALS-E and ALS-L patients could be reasonably separated (AUROC = 0.70). These results highlight the potential for automated acoustic analyses to detect and stratify ALS.

A study on the fusion of musical theme landscape and soundscape in Hefei Feicui Lake scenic spot, China

The health of the urban public can be promoted by shaping ecological landscapes and reducing noise. Visual landscapes and soundscape, considered as important components of sustainable urban development, are becoming increasingly concerned. In this study, Hefei Feicui Lake scenic spot in China was regarded as an example. By using questionnaire survey, soundwalks and acoustic monitoring methods, which aimed to understand people’s sense of identification with musical theme landscape and soundscape in the area, and further explored the effects of the interaction between musical theme landscape and soundscape on the perceived soundscape restoration of visitors. The results showed that musical theme landscape and soundscape could affect people’s emotions on the individual level and their behaviours, such as staying (viewing the scenery or rest) on the social level. On this basis, a strategy for creating urban public space inspired by the art of music was proposed as the topic of this study.

Non-Synchronous Measurements Acoustic Imaging Method Based on Capped Nuclear Norm Minimization

In this work, the difference convex function based on capped nuclear norm minimization (CNNM-DC) method, a cross-spectral matrix (CSM) completion iterative algorithm with excellent noise immunity, is proposed to realize acoustic imaging of non-synchronous measurements (NSM) under the condition of low signal-to-noise ratio (SNR). Compared with the CSM completion algorithm based on the nuclear norm minimization (NNM) model, the truncated nuclear norm regularization (TNNR) model, and the weighted nuclear norm minimization (WNNM) model, the proposed method can obtain the acoustic image with narrow main lobes and no sidelobe under the condition of low SNR. The simulation results show that, under conditions of low SNR, the proposed method effectively reduces the width of the main lobe, suppresses the side lobes, and achieves more accurate imaging results than the previous method. Finally, experiments were conducted to verify the feasibility of CNNM-DC. The experimental results show that the proposed method is an accurate acoustic imaging algorithm for NSM under low SNR, which lays a foundation for acoustic imaging in industrial occasions with strong background noise interference.

Phase Correction of the Channels of a Fully Populated Randomized Multielement Therapeutic Array Using the Acoustic Holography Method

The acoustic holography method was used to characterize a therapeutic focused fully populated 256-element ultrasonic transducer array. Elements of the array with the shape of equal area polygons are densely arranged in an irregular pattern on a spherically concave surface with a radius of curvature of 150 mm and a diameter of 200 mm. The array has a central frequency of 1.2 MHz and is designed to operate in water. The performance of individual array elements was studied based on the holographically reconstructed normal velocity distribution over the array surface. It was shown that with the same electrical signals applied to the elements, their acoustic responses had a phase deviation relative to the nominal values, which can be caused either by the asphericity of the array surface, or by the introduction of additional phase delays by the electrical matching network. To compensate for the detected parasitic phase shifts of the elements and restore the effective sphericity of the radiating surface, the Verasonics V-1 control system was used. The hologram measured after making the correction, as well as the shape of the focal region and acoustic pressure magnitude at the focus, separately measured by a hydrophone, showed that the proposed method reconstructed the nominal operating parameters of the array with high accuracy.

Comparisons between the disturbances in chemiluminescence and heat release rate from acoustically perturbed partially premixed and diffusion flames

Heat release rate is a critical parameter in the combustion process, yet its quantification can be challenging to obtain experimentally. In this study, an acoustical measurement system based on the Rijke tube was established to investigate the heat release rate perturbations of 25 propane/air flames under different mixing conditions. For premixed flames, perturbations in CH* and OH* chemiluminescence were consistent with the heat release rate disturbances determined using the acoustical method, thereby validating the proposed acoustical method and platform. Based on these, a comprehensive analysis was carried out on the chemiluminescence results and heat release rate perturbations of flames under different fuel–air mixing conditions, revealing the condition where the chemiluminescence method no longer reliably indicates the heat release rate. The research also investigated the chemiluminescence structure of flames under different fuel–air mixing conditions, identifying a difference in the distribution of CH* and OH* chemiluminescence at higher equivalence ratios (approaching diffusion flame conditions). In fully diffusion flames, the perturbation of OH* chemiluminescence was primarily observed near the base of the flame, while the peak perturbation of CH* chemiluminescence resides within the soot reaction zone downstream of the flame front.

Detection of defects in printed circuit boards by the acoustic emission method

Objectives. Defects in the form of layering may occur during lamination in the production of multilayer printed circuit boards (MPCB). These defects cannot be detected by optical and electrical methods of output control. However, they can lead to breaches of the mechanical mode of operation and failures while running radioelectronic devices. In order to detect such defects, the acoustic emission (AE) method is proposed. This is based on the occurrence and propagation of acoustic waves in MPCBs caused by the presence of defects. The aim of this study is to investigate the possibility of using the AE method to detect defects in multilayer printed circuit boards. These defects can occur, in particular, in the lamination process.Methods. A mechanical processes modeling program (for research on the MPCB model) and various samples of two-layer printed circuit boards with pre-introduced defects (for experimental studies) were used to study the propagation of acoustic signals in the MPCB in the presence of defects. A solenoid mounted on the MPCB was used as a source of acoustic signals, while a piezoelectric sensor was used to receive signals. Data processing was carried out by comparing AE signals obtained for a serviceable MPCB sample and for MPCB samples with defects.Results. Simulation of the acoustic signal propagation in MPCBs in serviceable and faulty (with a rectangular defect in the form of delamination) states was carried out to show the difference in the received signals at the sensor installation point. Experimental studies were also conducted to examine the AE method applicability for detecting defects of various sizes and quantities.Conclusions. The studies demonstrated that the AE method allows the presence of defects in MPCB occurring during the lamination process to be detected effectively and reliably. This study proposes a new approach to non-destructive testing of MPCB using the AE method. This method significantly increases the reliability of MPCBs and the efficiency of their production processes.

Acoustic emission diagnostics of a hull structures by a system of integrating fiber-optic sensors for the aircraft and spacecraft safe operation

A variant of aircraft and spacecraft state of hull structures acoustic emission diagnostics method based on a system of distributed fiber-optic sensors is considered. Such systems can be sources of information for a technical means of ensuring safety at aerospace facilities. The Green's function for a single sensor is found, and the features of its operation under the influence of pulsed acoustic emission signals are considered. The capabilities of the sensor system under consideration in estimating the coordinates and parameters of acoustic emission signals are determined. The results of experimental studies demonstrating the possibility of detecting emission signals under conditions of specific interference are reported.

Full-waveform inversion of pure quasi-P waves in titled transversely isotropic media based on different parameterizations

Full-waveform inversion (FWI) builds subsurface parameter models by minimizing the residuals between the modeled and observed data. Accounting for the effects of anisotropy is critical for high-resolution imaging of complex structures. We develop an acoustic anisotropic FWI method based on a pure quasi-P-wave (qP-wave) equation. The equation coefficients and their derivatives with respect to Thomsen’s anisotropy parameters ([Formula: see text] and [Formula: see text]) are estimated by least-squares optimization. We derive and analyze the radiation patterns for six parameter classes: the velocity along the symmetry axis [Formula: see text], [Formula: see text], and [Formula: see text]; the normal moveout velocity [Formula: see text], the anisotropy parameter [Formula: see text], and [Formula: see text]; the horizontal velocity [Formula: see text], [Formula: see text], and [Formula: see text]; [Formula: see text], [Formula: see text], and [Formula: see text]; [Formula: see text], [Formula: see text], and [Formula: see text]; and [Formula: see text], [Formula: see text], and [Formula: see text]. The parameterization [Formula: see text] has significant trade-off between [Formula: see text] and [Formula: see text] at the intermediate and wide scattering angles. The anisotropy parameters [Formula: see text] and [Formula: see text] are resolvable at the short scattering angles for the parameterizations [Formula: see text] and [Formula: see text], respectively. The parameter crosstalk for the parameterizations [Formula: see text] and [Formula: see text] is more serious than that for other types of parameterizations. We perform FWI of pure qP-waves in vertical transversely isotropic (VTI) and titled transversely isotropic (TTI) media. Inversion results on the overthrust VTI model and the modified BP TTI model show that the velocity, anisotropy parameters, and tilt angle can be individually reconstructed when other parameters are sufficiently accurate. The multiparameter FWI cannot obtain reliable tilt angles for each type of parameterization. The inversion with the parameterization [Formula: see text] produces [Formula: see text], [Formula: see text], and [Formula: see text] models with modest accuracy, whereas the parameterization [Formula: see text] helps to improve the accuracy of [Formula: see text] and [Formula: see text] models.

Research of the application of nickel-chrome-silicon bronze BrNHK for the manufacture of helical compression springs

The results of a study of the mechanical characteristics of the BrNHK bronze alloy using the acoustic emission method are presented. The mechanical characteristics of BrNHK-2.5-0.6-0.7 wire were studied after various heat treatment modes. The widespread use of bronze alloy BrKMts3-1 is due to its low price, while the mechanical and operational properties satisfy both consumers and spring manufacturers, since the technology for manufacturing springs from this alloy is not fundamentally different from the technology for manufacturing springs from cold-worked wire. In turn, the BrB2 alloy is considered a scarce alloy and is used only for springs intended for special equipment, since the properties of this alloy after hardening heat treatment are not inferior to cold-worked carbon steels. Given the increased cost of beryllium, work is underway both to reduce the beryllium content and to switch to beryllium-free alloys.