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The article presents the results of studies of bottom landscapes carried out with the use of an echo sounder with a side-scan location function and supplemented by video filming from an underwater vehicle in a bay of one of the islands in the northern skerry area of Lake Ladoga in June 2022. The results of the echo sounding were used to develop a three-dimensional bathymetric model of the examined Haukaisenlahti Bay on Kukhka Island and to identify significant differences in comparison with published navigation maps for Haukaisenlahti Bay. The formation of the bed topography and the state of the shores in both above-water and underwater zones are determined by the specific features of the geological structure of this part of the water area, resulting from the different resistance to weathering processes in different geological formations. Six main types of facies were identified in the underwater landscape of the bay. The outlook and the change of facies are associated with the presence of hard rocky surfaces and hard clastic material followed by loose soils at greater depths. The outlook of the facies is also determined by the specific features of the bathymetric structure of the bay and the predominance of various associations of living organisms, the development of which depends on the type of surface and soil. The study confirmed the prospects of the use of echo sounders with a side-scan location function to study and map underwater landscapes of Lake Ladoga in combination with a remote video recording from an uninhabited vehicle. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Given the pressing need to address the escalating water supply challenges in the coastal regions of southeastern and southern Ukraine, the expansion of methodologies for identifying zones of submarine groundwater discharge (SGD) within the Ukrainian shelf of the Azov-Black Sea basin stands as a paramount task for national marine hydrogeologists and geoecologists. Consequently, the advancement of novel comprehensive methodologies and technologies for locating additional freshwater reservoirs specifically, the segment of groundwater outflow into the Black Sea geo-ecosystem (GES), holds immense potential to broaden the horizons for water provisioning to the populace and other stakeholders (such as agricultural entities, industrial sectors, etc.) across the coastal areas of Ukraine. The article presents theoretical findings on the feasibility of using acoustic methods to detect changes in salinity of the marine aquatic subsystem (MASUS) within geo-ecosystem (GES) of the sea basin, particularly in areas where freshwater discharge from geological aquifers or riverbed runoff is probable. To achieve this objective, we examine the unique characteristics of acoustic signal reflection as it propagates through the MASUS water environment, analyzing variations in sound speed corresponding to changes in salinity within the marine water environment. Theoretical calculations employ methods from statistical physics and quantum mechanics to investigate such phenomena. The comprehensive theoretical insights outlined in this article enable us to propose a practical and cost-effective approach for identifying sources of submarine groundwater discharge. This method combines two acoustic techniques: measuring sound speed within the MASUS water environment and assessing the reflection coefficient of an acoustic signal from the interface between MASUS water and the geological environment of GSUS GES within the marine basin.

Abstract Shielded substations with SF6 gas insulation (GIS) play a critical role in supplying power to urban areas, and it is crucial to quickly identify and isolate faults to restore system operation and meet supply demands. However, locating faults in such substations can involve extensive and time-consuming procedures, such as opening and closing hermetically sealed compartments containing SF6. This paper presents the development of an acoustic test bench that accurately replicates the dynamic characteristics of SF6 shielded substations. By utilizing the traveling wave technique, partial discharges occurring in high-voltage insulation can be detected and precisely located. The method employs various techniques, including the analysis of the arrival time of traveling waves at different points within the substation and triangulation methods. The use of traveling waves in partial discharge detection offers several advantages, such as precise fault location and non-interference with normal substation operations. Additionally, acoustic methods are highly sensitive to other sources of partial discharges, such as moving particles and fluctuating potential discharges. The results demonstrate that the combination of the acoustic test bench and the disturbance localization technique presents an innovative approach to fault location studies in GIS. The acoustic test bench enables controlled simulation of failure conditions, providing accurate data on the acoustic behavior of substations. Through the disturbance location technique, these data can be analyzed and interpreted to pinpoint the exact fault location. This integrated approach enhances the efficiency of the troubleshooting process and reduces the time required to repair GIS.

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.

Stress evolution and related acoustic emission (AE) in modulated 10M martensite are simultaneously studied during compression forced motion of Type I and Type II single twin boundary (TB) resulting in microstructure reorientation and large deformation. The single TB of both types is formed in the same sample and traveled the same volume. The single boundary exhibits random jerky movement and for Type I the stress fluctuation can be directly correlated to AE signal. The AE during the single TB motion is an avalanche‐like process surmounting the obstacles – crystal defects. The amplitudes of AE are approximately five times higher for Type I compared to Type II. The energy amplitudes of AE events follow the universal power law with different coefficients for Type I and Type II TB. The peak rate well correlates with stress fluctuation during TB motion. Large differences observed for the same sample indicate a different mechanism of pinning and ultimately a different mechanism of Type I and Type II TB motion. [ABSTRACT FROM AUTHOR]

This paper explores an informal acoustic method developed by a group of industrial geologists working in geothermal energy landscapes in the southwest of Iceland. Through a series of ethnographic descriptions, this paper renders the work these geologists carry out in sonic terms, emphasizing how they use their bodies as sonic detectors in the production of geological evidence. Sound, the paper argues, is what allows geologists to make the intractable problem of volcanic cooling doable. It does this by differentiating two forms of evidence. Primary evidence, which ends up as data in geological reports, and secondary sonic evidence, which is what establishes that this primary evidence is, in fact, evidence. The paper introduces the concept data echoes as a way to think about how sound articulates between these evidential protocols. As echo, sound works as an outside, which, while remaining external to official protocols of knowledge production, nevertheless helps to constitute distinctions that are meaningful to the production of those categories. As data echoes through the various moments of data capture, analysis, and model building, sound's temporal form helps to predict the time frame of volcanic cooling, as it affects both the immediate energy production scenarios and the long durée of volcanic time. [ABSTRACT FROM AUTHOR]

Sound is produced by many geomorphic and hydrological processes, such as rockfalls and landslides, ocean waves, fluvial flood flows and collisions among moving bedload clasts. In these and other areas of study, acoustic methods have found useful application to detect and quantify the operation of important landscape processes. In some, such as the recording of river discharge, the occurrence of rare events such as exfoliation or the presence and movement of dust devils (willy-willies), the use of acoustic methods is still in a relatively early stage of development and testing. The use of acoustic methods in the recording of rainfall occurrence and intensity is also developing and has the capacity to yield data with higher temporal resolution than can be achieved using conventional rain gauges. Novel acoustic methods include the analysis of the sound recorded by security cameras, which potentially form a vast network of observing stations. The frequencies of sound generated by land-surface processes include audible sound, ultrasound and infrasound at frequencies below the human hearing range. All appear to provide opportunities for further development of useful research tools and methodologies. [ABSTRACT FROM AUTHOR]

Corona discharges are a concern in high-voltage applications. It is of utmost importance to detect and locate the discharges at an early stage using simple methods for this purpose. This paper evaluates and compares the sensitivity of two methods for detecting and locating the source of discharges, which are based on a digital single-lens reflex (DSLR) camera and a portable wideband sonic camera incorporating a matrix of micro-electromechanical systems (MEMS) microphones. Both cameras can generate an image of the studied area where the discharge sites are identified. The study is carried out with different electrode geometries, 50 Hz alternating current (ac) and positive and negative direct current (dc) supplies, and the effect of the distance between the sensor and the discharge sites is also analyzed. The presented results show that the sonic camera enables fast, simple, and sensitive detection and localization of the source of corona discharges even at a very early stage in daylight conditions, regardless of the type of power supply, that is, ac or positive/negative dc, and at distance of several meters from the discharge source. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM), or 3D printing, processes depend on a user-defined set of optimized process parameters to create a component. Monitoring and control of AM processes in real-time can help achieve process stability and repeatability to produce high quality parts. By applying in-situ monitoring methods to the AM process, defects in the printed parts can be detected. In this review, application of both imaging and acoustic methods for the detection of sub-surface and internal defects is discussed. Imaging methods consist of visual and thermal monitoring techniques, such as optical cameras, infrared (IR) cameras, and X-ray imaging. Many studies have been conducted that prove the reliability of imaging methods in monitoring the printing process and build area, as well as detecting defects. Acoustic methods rely on acoustic sensing technologies and signal processing methods to acquire and analyze acoustic signals, respectively. Raw acoustic emission signals can correlate to particular defect mechanisms using methods of feature extraction. In this review, representation and analysis of the acquired in-situ data from both imaging and acoustic methods is discussed, as well as the means of data processing. Ex-situ testing techniques are introduced as methods for verification of results gained from in-situ monitoring data.

The influence of the surface pre-deformation on jerky flow caused by the Portevin-Le Chatelier (PLC) effect was investigated using flat tensile specimens of an Al-Mg alloy. Although jerky flow represents a macroscopic plastic instability, the underlying mechanisms stem from self-organization of dislocations, which pertains to deformation processes at mesoscopic scales. To provide a comprehensive approach, the investigation was carried out by coupling tensile tests, digital image correlation and acoustic emission techniques, each targeting a particular range of scales. Thin superficial layers were pre-deformed using surface mechanical attrition technique (SMAT). It was found that the observed effects depend on which surfaces are processed. Overall, the treated samples exhibited an enhanced yield strength without deterioration of ductility in comparison with the initial material. These changes in the general mechanical behavior are likely to be correlated with the changes in jerky flow. Using digital image correlation, a tendency to delocalization of bursts of plastic flow was found for both the PLC bands and smaller-scale strain heterogeneities outside the bands, the latter having been little studied so far. Unexpectedly, SMAT occurred to modify plastic flow drastically at this scale. In addition to clarification of the role played by the surface in the PLC effect, these findings provide new insights into relationships between deformation processes at distinct scales. [Display omitted] [ABSTRACT FROM AUTHOR]

About 60% of the territory of the Russian Federation is covered by permafrost. Additionally, a large share of the country's mineral and hydrocarbon deposits are located in the Arctic. Climate change that has been happening over the past few decades has had a serious impact on the conditions in which permafrost soils are found. Changes in temperatures in permafrost regions, along with the human impact from mining and processing, have led to an increase in accidents caused by the degradation of permafrost foundations. In this situation, timely detection of the degradation of permafrost foundations plays a pivotal role in ensuring the safe operation of buildings and structures. This article contains a theoretical review and describes the results of an experimental study of whether it is possible to use acoustic testing in solving problems associated with monitoring the state of permafrost foundations. In the course of the study, the relationships between the acoustic characteristics and the deformation and strength characteristics of permafrost soils were analysed. The results of the study made it possible to draw a preliminary conclusion that acoustic testing can be used to solve problems associated with condition monitoring of permafrost foundations. [ABSTRACT FROM AUTHOR]

We consider the procedure of ultrasonic quality control of weld seams in thin-walled titanium-alloy shells with a thickness of 0.6 mm. Publications devoted to the excitation and propagation of Lamb waves and practical problems of ultrasonic inspection of thin-walled products are reviewed. The problem of detecting adhesions (areas of a weld seam with lack of penetration that conduct ultrasonic waves well but do not provide mechanical strength) is solved. It is proposed to use a corner groove as an indicator of lack of penetration in the weld. The propagation of different modes of Lamb waves in the material is analyzed, and the optimal testing parameters are selected. High information content of the signal is achieved using wavelet analysis and fine-pitch precision digital filters. Defectograms of a weld containing defective and defect-free areas are analyzed. The results of ultrasound scanning are compared with metallography data. [ABSTRACT FROM AUTHOR]

About 60% of the territory of the Russian Federation is covered by permafrost. Additionally, a large share of the country’s mineral and hydrocarbon deposits are located in the Arctic. Climate change that has been happening over the past few decades has had a serious impact on the conditions in which permafrost soils are found. Changes in temperatures in permafrost regions, along with the human impact from mining and processing, have led to an increase in accidents caused by the degradation of permafrost foundations. In this situation, timely detection of the degradation of permafrost foundations plays a pivotal role in ensuring the safe operation of buildings and structures. This article contains a theoretical review and describes the results of an experimental study of whether it is possible to use acoustic testing in solving problems associated with monitoring the state of permafrost foundations. In the course of the study, the relationships between the acoustic characteristics and the deformation and strength characteristics of permafrost soils were analysed. The results of the study made it possible to draw a preliminary conclusion that acoustic testing can be used to solve problems associated with condition monitoring of permafrost foundations.

Abstract Background Late-onset Pompe disease (LOPD) is a metabolic myopathy disorder characterized by progressive muscle damage and among others dysfunction of the voice apparatus, which affects speech and – above all – voice quality. Symptoms include dysphonia, instability, glottic insufficiency, and tense voice. The aim of this study was to evaluate and compare voice quality disorder in a group of 15 LOPD patients who were first examined in 2014 and then re-examined in 2017. Methods In both 2014 and 2017, the same 15 LOPD patients, ranging in age from 15 to 57, from 10 different families, underwent the following examinations: perceptual assessment of voice quality on the RBH scale, electroglottographic recordings, and acoustic recordings. All the patients were on enzyme replacement therapy (ERT). Results Three years after the 2014 study, the LOPD patients demonstrated a deterioration in voice quality. A statistically significant increase in glottic insufficiency (p = 0.0399) and a shift towards tense voice (p = 0.0417) were observed. Two patients – out of three who had received presymptomatic treatment – demonstrated stable voice quality compared with 2014. Conclusions The results suggest increased muscle weakness and progression of LOPD. The parameters Closed Quotient (calculated on the basis of an electroglottographic signal) and Peak Slope (calculated on the basis of an acoustic signal) proved to be the most sensitive.

The problem solution of the definition of the beams inhomogeneous rheological properties on the basis of the acoustic method and the analysis of amplitude-frequency dependences is presented. The operator equations linking required and prescribed functions are presented. The iterative process is constructed, computational experiments results of the definition of the beams inhomogeneous rheological properties for various laws of distribution of required features are presented.

The rheology of non‐Newtonian slurries is measured in a recirculating pipe loop using an acoustic velocimetry‐pressure drop technique at very low flow rates and variable solids loadings. The technique avoids (a) settling at low solids concentration, a shortcoming of bench rheometry, by using a vertical test section, and (b) physical sampling, providing greater safety. Speed of sound in the suspensions is also modeled. In‐line and off‐line data are used to assess the suitability of several non‐Newtonian models to describe observed flow behavior. Measured and predicted values of the friction factor are compared with the Madlener et al Herschel–Bulkley extended model found to be superior. The dependence of yield stress and viscosity on solids loading and particle size is investigated, showing complexities from aggregation on the particle size distribution require more interpretation than the choice of rheological or friction‐factor model. [ABSTRACT FROM AUTHOR]

UAV-supported instrumental diagnostics system for remote acoustic investigation and monitoring of lungs for managing patients within the framework of telemedicine has been developed. The system includes a user set of control and measuring equipment and a UAV carrier for delivery and organization of the patient testing procedure. [ABSTRACT FROM AUTHOR]

An acoustic method for a quantitative assessment of the volume content of a polymeric matrix in CFRPs is proposed and realized experimentally. For this purpose, a laser-ultrasonic method based on the thermo-optical excitation of broadband pulses of longitudinal acoustic waves is used. A formula for calculating the volume content of the polymeric matrix in a CFRP from experimentally measured phase velocities of longitudinal acoustic waves in this material is proposed. Distributions of the volume content of the matrix in a control CFRP specimen and in a CFRP structure made under similar conditions are obtained. It is shown that the laser-ultrasonic method allows one to detect the areas with excess and deficient matrix content in CFRP specimens and areas of CFRP constructions and to quantitatively assess the spread of matrix content. The spread between the maximum and minimum matrix content observed depends on the shape of the investigated area of the structure. This method can be used for the quality control of composite structures before their exploitation. [ABSTRACT FROM AUTHOR]

To impart the optimal structure to a powder material and promote high mechanical properties, the production process is to be monitored at each step using nondestructive methods. Acoustic methods are believed to be promising in this respect. The parameters of acoustic fields are influenced by many factors that determine the structure and properties of powder materials. A relevant task is to improve acoustic methods for the identification and use of this influence. A model material is taken as an example to show the capabilities of a nondestructive acoustic method relying on integrated measurement of the propagation velocities of longitudinal, transverse, and rod elastic waves in studying the patterns peculiar to the powder structurization at the molding and sintering stages. The following problems that can be solved using this method are considered and experimentally confirmed: identify how the properties of the starting powders influence the characteristics of the final material, monitor the compaction and contact formation processes in the material, and identify features of these processes, which are manifested as uneven distribution of properties over the material and aftereffects and are stepwise. Additional criteria are proposed to increase the reliability and descriptiveness of the results. Analysis of the experimental data shows that the propagation velocities of bulk and rod elastic waves in different ways reflect the compaction and contact formation in powder materials. The differences are explained by the peculiarities of acoustic fields generated by various types of elastic waves. [ABSTRACT FROM AUTHOR]

This work presents the first observation of ultrasound and eddy currents coupling with Portevin–Le Chatelier serrations during tensile straining of aluminium-magnesium alloy small-size samples, of a gauge section 5.0 × 0.8 × 0.6 mm3. Significant changes in serration characteristics were detected and quantified using Fast Fourier Transform analyses in the 120–160 MPa stress range under the influence of 2.5 and 5.0 MHz ultrasound, and a 60 kHz eddy current. Digital Image Correlation measurements showed that the change in singular slip bands movement is surprisingly regular all along the sample gauge sections accompanied with a reduction in the serrations' frequency. Unlabelled Image [ABSTRACT FROM AUTHOR]

The possibility of rapid adjustment of mass production of systems for acoustic pulmonary monitoring and symptomatic assistance to those affected by COVID-19 in the most difficult situation of the pandemic is considered. [ABSTRACT FROM AUTHOR]

Abstract This letter presents a systematic study of serrated flow of the FeAlCrMo medium-entropy alloy in compression, first observed at 400 °C and a strain rate of ~10−4 s−1. In this work, these parameters were varied in order to evaluate how they affect the deformation behavior. Compression curves together with the acoustic emission data suggest that dynamic strain aging (the Portevin-Le Châtelier effect) is responsible for the jerky flow. Furthermore, at certain conditions, peculiar periodic serrations appeared, which possessed bimodal distribution of drop magnitudes. In this multicomponent material, this effect likely originates in complex dislocation-solutes interactions at the atomic scale. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Elastic deformation of surfaces and piezo-viscous effect of lubricant make EHL a very complex lubrication regime. Elastohydrodynamic Lubrication becomes much more complex when conditions like rough surfaces, non-newtonian behavior of lubricant and temperature dependent flow are considered. The present paper takes the task of reviewing experimental methods applied till date for measuring film thickness and pressure. The paper has been divided into many sections and sub-sections to deal with these techniques in a lucid manner. Experimental methods have been categorized into Electrical, Optical and Acoustic methods. The difference of 8-10% between theoretical and experimental results are witnessed using Electrical methods. Whereas, this difference is less than 1% using Optical methods. Among all optical methods, Relative Optical Interference Intensity Technique is the most effective technique with an ability to measure the film thickness as small as 1 nm or less. The last section of the paper deals with the scope of improvement in measurement techniques in future to understand EHL in more detail. [ABSTRACT FROM AUTHOR]

Insulation degradation is one of the prime reasons for failures in power transformers. Partial discharge (PD) is considered as one of the primary causes of initiation of insulation degradation. Thus, monitoring of PD in a power transformer at a preliminary stage is the most important task to prevent any catastrophic failure. This paper presents a brief introduction of PD phenomena along with the causes and effects. Various topics of contemporary research related to PD, such as modelling, detection, measurement, and classification, are grouped under different headings with exhaustive up-to-date bibliography. The paper outlines distinctive sensors and technologies based on acoustic, ultra-high-frequency, electric, and hybrid methods. The techniques are compared, and their advantages and limitations are pointed out. The techniques of denoising of PD signal based on signal processing, artificial intelligence, and statistical analysis are summarised. The challenges and trends in future PD research are also discussed. This paper would provide immense help for the researchers, academicians, and service engineers working in the field of PD in power transformers. [ABSTRACT FROM AUTHOR]

Diffusionless isothermal ω transformation is a recently discovered ω transformation that occurs isothermally during aging near room temperature in Ti alloys with a bcc (β -phase) structure. Unlike conventional displacive phase transitions, the diffusionless isothermal ω transformation occurs in locally unstable nanoscale β -phase regions formed by quenched-in statistical compositional fluctuations. In the present study, the effects of Al and oxygen additions in ternary β -phase Ti–V-based alloys on the diffusionless isothermal ω transformation and its attempt process, called dynamic atomic shuffling, were studied. Elastic constant and internal friction measurements for Ti–16.6V–2.1Al and Ti–17.5V–2.5O (at.%) alloy single crystals and analysis of quenched-in compositional fluctuations using the thermodynamic theory of fluctuations indicated that the oxygen addition increases the β -phase stability, and it selectively increases the activation energy of dynamic atomic shuffling in locally unstable Ti-rich regions, which is caused by the strong attractive interaction between Ti and oxygen elements. As a result, oxygen addition suppresses the diffusionless isothermal ω transformation that occurs during aging at 298 K. In contrast, low β -phase stability, which promotes ω -phase nucleation, is retained by Al addition. Furthermore, dynamic atomic shuffling with a low activation energy is retained even though the average activation energy is enhanced by the Al addition, originating from the relatively weak atomic interaction between Ti and Al. Therefore, the diffusionless isothermal ω transformation cannot be suppressed by Al addition. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper aimed at studying the potential of two nondestructive methods to estimate the wood mechanical properties and mass loss due to thermal treatments. In this study, a low-density tropical hardwood species Simarouba amara (marupá) was used. Forty small beams with dimensions of (25 × 25 × 400) mm (width × thickness × length) were cut from this species. Initially, the beams were nondestructively tested using stress wave and ultrasound methods. Stress wave velocity (Swv), ultrasound velocity (VLL), dynamic modulus of elasticity (Ed) and stiffness coefficient (CLL) were longitudinally determined. Afterwards, the beams were thermally treated using a chamber without air circulation under atmospheric pressure. Two schedules were tested: 160 ºC for 180 minutes and 200 ºC for 70 minutes. Mass loss (ML) due to thermal treatment was calculated and the thermally treated material was again nondestructively evaluated. Afterwards, modulus of rupture (fm), modulus of elasticity (EM) and parallel compression strength (fc,0) of treated material were assessed. Backward linear multiple regression analysis was run in order to estimate these properties. Parameters investigated through nondestructive testing (before and after treatment) and derivative variables were used as independent variables, totaling 12 variables. For both treatment schedules, all parameters related to nondestructive techniques were affected by the thermal treatment, thus acoustic velocities and stiffness values were improved. It was found that all evaluated properties of treated material could be modeled at a reasonable level (R2 = 0.392 to 0.874) depending on the nondestructive method and treatment schedule used. Nevertheless, ultrasound method fitted the most suitable models for a large number of properties. The utilization of variables from both methods together yielded better models whose R2 value ranged from 0.466 (fm) to 0.941 (EM). It was found that the most important nondestructive variables which entered into the models were: Swv before and after treatment, VLL after treatment, Ed before treatment and CLL after treatment. Finally, it could be concluded that stress wave and ultrasound nondestructive methods presented great potential to evaluate properties of thermally treated wood material.DOI: http://dx.doi.org/10.5755/j01.ms.20.1.3341

Acoustic techniques have been used for many years to find and locate leaks in buried water distribution systems. Hydrophones and accelerometers are typically used as sensors. Although geophones could be used as well, they are not generally used for leak detection. A simple acoustic model of the pipe and the sensors has been proposed previously by some of the authors of this paper, and their model was used to explain some of the features observed in measurements. However, simultaneous measurements of a leak using all three sensor-types in controlled conditions for plastic pipes has not been reported to-date and hence they have not yet been compared directly. This paper fills that gap in knowledge. A set of measurements was made on a bespoke buried plastic water distribution pipe test rig to validate the previously reported analytical model. There is qualitative agreement between the experimental results and the model predictions in terms of the differing filtering properties of the pipe-sensor systems. A quality measure for the data is also presented, which is the ratio of the bandwidth over which the analysis is carried out divided by the centre frequency of this bandwidth. Based on this metric, the accelerometer was found to be the best sensor to use for the test rig described in this paper. However, for a system in which the distance between the sensors is large or the attenuation factor of the system is high, then it would be advantageous to use hydrophones, even though they are invasive sensors.

Due to its economical production process polysilicon, or multicrystalline silicon, is widely used to produce solar cell wafers. However, the conversion efficiencies are often lower than equivalent monocrystalline or thin film cells, with the structure and orientation of the silicon grains strongly linked to the efficiency. We present a non-destructive laser ultrasonic inspection technique, capable of characterising large (52 × 76 mm 2 ) photocell's microstructure - measurement times, sample surface preparation and system upgrades for silicon scanning are discussed. This system, known as spatially resolved acoustic spectroscopy (SRAS) could be used to optimise the polysilicon wafer production process and potentially improve efficiency. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review of various techniques of partial discharge (PD) localization. The technologies reviewed are acoustic, ultra-high frequency (UHF), optical, and electrical according to their chronological order of development. The paper outlines the distinctive acoustic and UHF sensors, along with the algorithm for the localization of PD source. Various digital signal processing and statistical techniques applied are likewise discussed. A substantial effort has been given to electrical methods since they represent the most active and current field of PD research. In this paper, the techniques of PD localization used so far are compared, and their advantages and limitations are pointed out. The challenges and trends in future research in PD localizations are also discussed. The review given in this paper will be useful to develop the future technologies for PD localization thereby avoiding insulation damage. Thus, this paper is intended to serve as a guide for the research on the localization of PD inside the transformer winding. [ABSTRACT FROM PUBLISHER]

Room temperature elastic constants of non-modulated (NM) tetragonal martensite of a Mn-rich Ni-Mn-Ga alloy were determined by ultrasonic methods. The results are in good qualitative agreement with ab-initio predictions and confirm that NM martensite exhibits strong elastic anisotropy with shear instability related to the soft acoustic phonons mediating the reverse transition. The geometric arrangement of the softest shearing modes is shown to be identical as for the stress-induced fct martensite of the Fe-31.2 at.%Pd alloy. However, it markedly differs from the arrangement of the soft shearing modes in parent Ni-Mn-Ga austenite phase. [ABSTRACT FROM AUTHOR]

Microcellular open-cell metal foams with pores of 75 or 400 μm in diameter and made of pure Al or Al-2 wt% Mg are tested in compression. The aluminum foam exhibits a typical smooth plastic flow and a positive strain rate sensitivity, whereas plastic instabilities and a negative strain rate sensitivity appear in the stress-strain curves of the Al-2 wt% Mg foams, indicating the presence of the Portevin Le-Châtelier (PLC) effect. The effect is further confirmed by acoustic emission analysis. Taken together, the data indicate that the PLC effect is caused in this material by the sudden collective deformation of many struts across the material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compression experiments were carried out on pristine and irradiated micropillars. • Acoustic emission was recorded concurrently during deformation. • Irradiation induced dislocation loops were found by transmission electron microscopy. • Strain bursts caused by intermittent cooperative dislocation motion were detected. • The detected acoustic events were found to match the strain bursts in both cases. • Irradiation was found to decrease strain burst sizes and acoustic activity. • Interaction of mobile dislocations and loops are undetectable by acoustic emission. Plastic deformation of microsamples is characterised by large intermittent strain bursts caused by dislocation avalanches. Here we investigate how ion irradiation affects this phenomenon during single slip single crystal plasticity. To this end, in situ compression of Zn micropillars oriented for basal slip was carried out in a scanning electron microscope (SEM). The unique experimental setup also allowed the concurrent recording of the acoustic emission (AE) signals emitted from the sample during deformation. It was shown that irradiation introduced a homogeneous distribution of basal dislocation loops that lead to hardening of the sample as well as strain softening due to dislocation channeling at larger strains. Under the loading conditions imposed in the present work, the intensity of strain bursts was found to decrease during channeling. The concurrently recorded AE events were correlated with the strain bursts and their analysis provided additional information of the details of collective dislocation dynamics. It was found that the rate of AE events decreased significantly upon irradiation, however, other statistical properties did not change. This was attributed to the appearance of new type of dislocation avalanches which is dominated by short-range dislocation-obstacle interactions that cannot be detected by AE sensors. [ABSTRACT FROM AUTHOR]

The problem solution of the definition of the beams inhomogeneous rheological properties on the basis of the acoustic method and the analysis of amplitude-frequency dependences is presented. The operator equations linking required and prescribed functions are presented. The iterative process is constructed, computational experiments results of the definition of the beams inhomogeneous rheological properties for various laws of distribution of required features are presented.

El estuario de Bahía Blanca, ubicado al sur de la provincia de Buenos Aires (Argentina), constituye una costa baja con extensas llanuras de marea, islas y una compleja red de canales de diferentes magnitudes. Estos últimos integran un sistema de canales interconectados. El objetivo de este trabajo es establecer la circulación sedimentaria como carga de fondo en un sistema de canales interconectados (Cabeza de Buey, El Alambre, La Lista y Principal) mediante el análisis de los rasgos morfológicos de fondo, utilizando métodos acústicos (ecosonda y sonar lateral). El canal Cabeza de Buey se comunica con el canal La Lista a través del canal El Alambre. Los dos primeros vierten sus aguas en el canal Principal. El canal Cabeza de Buey posee un lecho plano constituido por material pelítico con arena muy fina. En su tramo más interno se presentan dunas medianas compuestas por arena fina, con un perfil asimétrico según el reflujo. Estas formas, continúan su desarrollo ininterrumpidamente hacia el canal El Alambre, donde se originan dunas grandes (altura 1,5 m) formadas por arena muy fina. Sus crestas son sinuosas o barjanoides y poseen su talud hacia la corriente de bajante. En el canal La Lista se determinan dunas asimétricas medianas orientadas según el reflujo y grandes linea-ciones sedimentarias (sand ribbons) sobre un fondo consolidado. El sedimento movilizado por la corriente corresponde a la fracción limo-arena fina. La distribución y configuración de las geoformas evidencian que el transporte sedimentario como carga de fondo se concentra principalmente en el canal La Lista. Es así como en el sistema de canales estudiado, sólo un canal de marea regula la dispersión de arena, transportando un importante volumen hacia el canal de navegación.Bahia Blanca estuary located in the south of Buenos Aires province, Argentina, is characterized by a low coastal area with large tidal plains, islands, and a complex network of tidal channels of different dimensions. The latter form an interconnected tidal channel system. The aim of this study was to determine the net bed load sediment transport in an interconnected channel system (Cabeza de Buey, El Alambre, La Lista, and Principal channels) through an analysis of the morphological features of the bottom using acoustic data (echo sounder and side scan sonar). Cabeza de Buey channel is connected to La Lista channel through El Alambre channel. The first two flow into the Principal channel. Cabeza de Buey channel has a fiat bed of mud with very fine sand and medium-sized dunes of fine sand in its inner sector that display an asymmetrical section according to the ebb flow. These dunes continue to develop uninterrupted towards El Alambre channel, where large dunes (1.5 m high) of very fine sand originate. Their crest lines are either sinuous or barchanoid and they have their lee towards the ebb current In La Lista channel, medium-sized asymmetrical dunes and large sand ribbons form on a rocky bottom according to the ebb flow. The sediment mobilized by the currents is characterized by the fine sand - silt fraction. The distribution and configuration of bed forms reveal that the bed load sediment transport is mainly concentrated in La Lista channel. Thus, only one tidal channel regulates the dispersal of sandy material, transporting a significant volume of sediment towards the shipping channel.

The widespread industrial applications of binary transition metal carbides (TMCs) are closely related to their complex chemical bonds. Owing to the high number of ionic components of chromium carbide (Cr 3 C 2), it is a challenge to accurately estimate its elasticity and mechanical properties. Pure polycrystalline Cr 3 C 2 was synthesized via high pressure and high temperature method, and its sound velocities, elasticity, and mechanical properties were investigated using high-pressure ultrasonic interferometry combined with density functional theory calculations. Furthermore, its bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and Vickers hardness were 319 GPa, 182 GPa, 459 GPa, 0.26, and 24.0 GPa, respectively. The results revealed that Cr 3 C 2 is more ductile than most covalent carbides, and its Vickers hardness is higher than that reported in previous studies. The intrinsic properties of Cr 3 C 2 were obtained, which are relying on the advantages of sintering the pure polycrystalline ceramics. [Display omitted] [ABSTRACT FROM AUTHOR]

A micromechanics-based method (“inverse self-consistent approximation”) that can extract all the independent elastic constants of single crystals from those of polycrystals with crystallographic texture was newly developed. In the developed method, all the elastic constants in an anisotropic polycrystal were measured by resonant ultrasound spectroscopy, and the crystallographic orientations and shapes of the grains were analyzed. Then, the elastic constants of a single crystal, which reproduce those of the polycrystal, were determined on the basis of Eshelby's inclusion theory and the effective-medium approximation, taking into account the elastic interaction between the grains, which reflects their shapes and orientations. The developed method determined the elastic constants of pure Cu and pure Mg single crystals from those of polycrystals quite precisely. The differences between the elastic constants obtained using our method and the values measured using single crystals were only ∼ 1%. In contrast, the application of an inverse Voigt–Reuss–Hill approximation, which cannot consider the effect of the grain shape on the elastic interaction, resulted in a relatively poor evaluation for pure single-crystalline Cu which exhibits strong elastic anisotropy. This indicates that the grain shape clearly affects the elastic interaction between the grains exhibiting high elastic anisotropy and influences the extracted single-crystalline elastic constants. In terms of the actual application of the inverse self-consistent approximation, the single-crystalline elastic constants of AZ31 Mg alloy, whose single crystals cannot be prepared easily, were clarified. [ABSTRACT FROM AUTHOR]

The paper presents the results regarding the identification of the value of the pull-off adhesion between a concrete added layer with a constant thickness and a substrate concrete layer in existing elements. A method of identification, which is based solely on the use of artificial neural networks (ANNs) and two non-destructive acoustic methods: impact-echo and impulse response on the surface of the added layer, was developed. The methodology of identifying the pull-off adhesion between a concrete added layer and a substrate layer in existing elements was developed and presented in the paper and is useful in construction practice. [ABSTRACT FROM AUTHOR]

Background: Pompe disease is a progressive metabolic myopathy. Disease progression is characterized, among other features, by progressive dysfunction of the voice apparatus. The aim of this study was to employ electroglottographic, acoustic and nasalance measurement methods on patients with late-onset Pompe disease in order to provide detailed information on the effect of the disease on voice quality. Voice quality is the key factor for estimating the effectiveness of ERT in late-onset Pompe disease. The study compared clinical phoniatric examination with electroglottographic, acoustic and nasalance measurement methods. The consistency of the aforementioned analyses was assessed.Methods: The study examined 19 patients with late-onset Pompe disease (including 9 with the juvenile form of the disease). Of these, a total of 17 patients underwent otolaryngological examination with detailed phoniatric evaluation of their articulatory organs. Electroglottographic recordings and nasalance measurements (using the nasalance Separator Handle) were obtained from all patients. MATLAB (COVAREP toolkit) was used to analyse voice recording data.Results: Dysphonia observed in patients with late-onset Pompe disease is mainly caused by dysfunction of vocal fold closure and weakness of vocal muscle. However, substantial speech nasality is caused by insufficient closure of the soft palate. Electroglottographic signal analysis, acoustic and nasalance testing methods indicated that more significant changes in the function of the voice apparatus presented in the juvenile form than in the adult form of late-onset Pompe disease.Conclusions: It was found that speech nasality and electroglottographic tests are more repeatable, comparable and versatile than phoniatric examination, allowing for earlier detection of voice pathology in late-onset Pompe disease. These sensitive and non-invasive acoustic and electroglottographic methods allow for the tracking of changes in voice as patients undergo treatment or as the disease progresses. [ABSTRACT FROM AUTHOR]

We studied the acoustic emission (AE) response to AZ31B alloy during cyclic and creep tests. The peak total AE event count appeared at the 400th cycle before material fracture during the compressive–tensile (C–T) cyclic test at a strain amplitude of 0.4%. In the case of 0.75% strain amplitude, the peak AE event count during compressive unloading occurred at approximately the 100th cycle before fracture. In creep tests at 423 and 523 K, the AE event count in the tertiary creep stage involved increased activations of slips and cracks. The AE responses indicated the transition of the deformation mechanism. The results suggest that the fracture of magnesium alloys can be predicted on the basis of in situ AE measurements. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for the non-destructive location and identification of cracks in unilaterally accessible massive concrete walls by means of the state-of-the-art acoustic methods of impulse response and ultrasound tomography. An example of the practical verification of the methodology used to investigate the concrete structure of a hydroelectric power plant is provided. [ABSTRACT FROM AUTHOR]

Tissue-engineered (TE) cartilage constructs tend to develop inhomogeneously, thus, to predict the mechanical performance of the tissue, conventional biomechanical testing, which yields average material properties, is of limited value. Rather, techniques for evaluating regional and depth-dependent properties of TE cartilage, preferably non-destructively, are required. The purpose of this study was to build upon our previous results and to investigate the feasibility of using ultrasound elastography to non-destructively assess the depth-dependent biomechanical characteristics of TE cartilage while in a sterile bioreactor. As a proof-of-concept, and to standardize an assessment protocol, a well-characterized three-layered hydrogel construct was used as a surrogate for TE cartilage, and was studied under controlled incremental compressions. The strain field of the construct predicted by elastography was then validated by comparison with a poroelastic finite-element analysis (FEA). On average, the differences between the strains predicted by elastography and the FEA were within 10%. Subsequently engineered cartilage tissue was evaluated in the same test fixture. Results from these examinations showed internal regions where the local strain was 1-2 orders of magnitude greater than that near the surface. These studies document the feasibility of using ultrasound to evaluate the mechanical behaviors of maturing TE constructs in a sterile environment. [ABSTRACT FROM AUTHOR]

The effects of stacking sequence and short-range ordering of solute atoms on the elastic properties of Mg–Zn–Y alloy single crystals with an 18R- or 10H-type long-period stacking ordered (LPSO) structure were studied. Instead of single crystals, the growth of which can be quite difficult, two directionally solidified (DS) Mg–Zn–Y alloy polycrystals, mainly consisting of 18R- or 10H-type LPSO structure, were prepared. X-ray pole figure analyses revealed that fiber textures, which differed in the two prepared alloys, were formed in the DS polycrystals. For the DS polycrystals, a complete set of elastic constants was measured during cooling from 300 to 7.5 or 5.5 K. By analyzing the elastic stiffness of DS polycrystals on the basis of a newly developed inverse Voigt–Reuss–Hill approximation, in which the detailed crystallographic texture could be taken into account, the elastic stiffness components of the single-crystalline LPSO phases from 300 to 7.5 or 5.5 K were determined. The elastic properties of the 18R- and 10H-LPSO phases were also evaluated by first-principles calculations based on density functional theory. Comparison of the measured elastic properties at 5.5 or 7.5 K with the first-principles calculations revealed that the elastic properties of the LPSO phase were virtually dominated by the stacking sequence of the LPSO structures and the formation energy of short-range ordered solute atom clusters, formed at the four consecutive atomic stacking layers. Importantly, the effects of the formation energy and stacking sequence were significant in the elastic moduli related to the atomic bonding between the stacking layers. [ABSTRACT FROM AUTHOR]