bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-contact Non-linear Impact Resonance Acoustic Spectroscopy for thermal damage characterization on mortar samples
Authors: Gosálbez J. , Carrión A. , Gallardo C. , Madrigal J.
Published: October 2024

The high sensitivity of the nonlinear terms of the elastic response of materials to the incipient appearance of damage has led to the appearance of the Non-linear Elastic Wave Spectroscopy methods (NEWS). Particularly, the Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) technique detects changes in the resonance of a material (frequency, damping factor, etc.) as a function of the intensity of the impact. Traditionally, mechanical waves have been monitored using an external sensor in contact with the material. Currently, alternative technologies are capable of capturing mechanical waves without direct contact or with embedded sensors in the material itself from its manufacture. This helps the automation process or the continuous monitoring of the material. Mortar is the most used composite material in construction. In this work, thermal damage on mortar samples is characterized by NIRAS tests using different sensing techniques. Accelerometers have been used as the reference technique, while laser interferometer and Fiber Bragg Grating (FBG) have been used as non-contact and embedded sensor techniques respectively. Two levels of damage are presented: sound samples and 400ºC damage. The different techniques offer similar results, showing the capability of the proposed techniques (FBG and laser interferometry) to be an accurate alternative to traditional contact techniques for NIRAS testing.
An approximation method to determine the travel time in total focusing imaging of carbon fiber-reinforced laminates
Authors: Cao Ziyi , Shi Fangfang
Published: October 2024

It is critical to accurately determine the propagation time in testing objects for ultrasonic array imaging using the Total Focusing Method (TFM). However, it poses challenges for the calculation of wave propagation time in carbon fiber reinforced polymer (CFRP) laminates because of the material anisotropy and inhomogeneity. This paper introduces a novel approach for computing ultrasonic wave travel time to enhance the TFM image of CFRP laminates. This method, termed the layer-by-layer acoustic travel time approximation (L-L TravelTimeAppro), considers the anisotropy within each monolayer and the heterogeneity of CFRP. It approximates the propagation path as straight throughout the material and computes the wave propagation duration utilizing the group velocity in each ply. The application of this method to TFM imaging is referred to as TravelTimeAppro-TFM. Experiments were conducted in a specially designed CFRP laminate. Subsequently, TFM imaging was processed by using propagation time calculated by isotropic, Dijkstra, and L-L TravelTimeAppro methods, respectively. The results indicate that TravelTimeAppro-TFM outperforms isotropic-TFM in terms of imaging amplitude gain with a maximum gain of 4.67 dB. Furthermore, it offers superior computational efficiency compared to Dijkstra-TFM.
Solving the Scattering and Reflecting Properties of Guided Waves in CFRP under Arbitrary Oblique Incidence Based on Spectral Method
Authors: Gao Lei , Feng FeiLong
Published: October 2024

In this paper, the Chebyshev allocation point was used to sample the plate thickness and the spectral method was used to solve the differential characteristic equation of obliquely incident-guided waves in CFRP plates, which was transformed into a matrix equation. After obtaining the mode solutions of obliquely incident guided waves, the spectral method was also used to solve the integral equations required for mode matching of guided waves at the end and step-change positions of the CFRP plate. Numerical results show that the spectral method can accurately calculate the dispersion curve of complex wave number guided waves, and compared with commonly used finite element simulation schemes, this method can quickly and accurately calculate the scattering solutions of plane-guided waves at these transverse defect positions.
Dispersion and Attenuation Estimation of Ultrasonic Guided Waves using Multi-Subarrays Matrix Pencil Method
Authors: Zheng Shuhang , Xu Kailiang , Tran Tho N.H.T. , Minonzio Jean-Gabriel
Published: October 2024

Dispersion and attenuation estimation of ultrasonic guided waves is important for waveguide characterization. Matrix pencil (MP) method has been proposed for multimode complex wavenumber estimation, but its performance highly depends on the signal to noise ratio (SNR), which still brings challenges for high attenuation waveguide evaluation. In addition, the model order, i.e., matrix size in MP method, significantly impacts the dispersion curve extraction. In this study, to avoid the model order interference and compensate the SNR sensitivity of the classical MP algorithm, a multi-subarrays MP method is proposed for accurate dispersion and attenuation estimation. Considering with different Hankel matrix sizes, the multi-subarrays MP method estimates the complex wavenumbers from each pair of submatrices to filter uncertain results. A soft threshold strategy is applied to compensate the noise sensitivity of the estimation. Simulated results prove the proposed method can improve the dispersion and attenuation curve estimation.
Estimation of temperature-dependent piezoelectric material parameters using ring-shaped specimens
Authors: Friesen O , Claes L , Scheidemann C , Feldmann N , Hemsel T , Henning B
Published: October 2024

Simulation-driven design processes of piezoelectric actuators and sensors necessitate precise material parameter knowledge. Historically, the IEEE standard on piezoelectricity is used for this purpose, which proposes an analytical method for material parameter identification based on resonance frequency evaluations. This method requires different impedance measurements on differently shaped and processed samples, which yields inconsistent material parameter sets due to processing effects on material properties. Previous studies show that an inverse procedure using a single disc-shaped specimen with some adaptations can be used to identify a full set of parameters. As high-power actuators often use ring-shaped components, this method needs adaptation for this kind of specimen. Furthermore, the dependence of the material parameters on temperature needs to be considered to characterise the temperature effects and the associated non-linear effects of the specimens. For this purpose, samples with different geometrical dimensions at a range of different temperatures are examined in this study. Material parameters are then estimated using an inverse approach utilising the measurement data in conjunction with a numerical FEM simulation model. The observed temperature dependence of the estimated material parameters is examined and presented in this contribution.
A Method of Ship Target Modulation Feature Enhancement Based on Phase Information
Authors: Zhang Xin , Shang Jintao , Ye Simao , Yang Liu
Published: October 2024

Ship modulation features are commonly used in underwater acoustic target recognition, which contains propeller parameter information of the target. The basis processing of modulation spectrum is demodulation. Traditional envelope demodulation methods only consider amplitude information and make little use of phase information, which can fully characterize the dynamic characteristics of radiated noise. In this paper, a modulation feature enhancement method based on phase information is proposed, which takes full account of the phase information of the target signal. It uses the modified group delay function to demodulate the target signal, and utilizes the phase stability characteristics of the modulated line spectrum to enhance the modulation features of the ship target by weighted phase features. Simulation and sea trial data verification show that the proposed method can effectively enhance the energy of the line spectrum, suppress the background noise, and improve the signal-to-noise ratio of the modulation line spectrum, which lays a good foundation for further using the modulation line spectrum to carry out the estimation of modulation parameters, and has a good application prospect in the field of underwater acoustic target recognition.
Bio-inspired target detection method of active sonar based on multi-ping perception
Authors: Wang Qingcui , Wang Fangyong , Du Shuanping , Lin Yuxin
Published: October 2024

The performance of the active sonar may degrade severely in real ocean environments, influenced by strong reverberation and multiple clutters. Inspired by the observation that dolphins always utilize a train of clicks when detecting underwater, we proposed an active target detection method by making full use of the multi-ping echo information which encompasses the differences between targets and reverberation/clutters. The detection performance of the click trains with different parameters were analysed first to give an insight on signal choice. Then we achieved apparent reverberation/clutter suppression result by utilizing the correlations and differences between multi-ping echoes. Further, the relative motion status between the target and the sonar platform could be perceived within multiple echoes, which strengthened the detection ability of weak target. We proposed two weighting strategies for multi-ping co-utilization. Either equal weights or unequal weights based on the different envelopes of dolphin echolocation click trains were exerted on multiple echoes, which can achieve different perception results for the relative target motion status. Both simulation and lake trials were conducted to verify the performance of the proposed method. The proposed method effectively suppress reveberaton and noise background by around 2-3 dB and achieve bionic detection of weak targets compared to traditional active sonar signal processing method.
Research on SNR enhancement method of underwater airgun impulse signal
Authors: Ma Siyu , Zhang Yuxiang , Xie Zhinan
Published: October 2024

Seismic airgun blasting is nowadays widely employed for ocean exploration and marine geophysical study. Being powerful acoustic source showing excellent repeatability and consistency, it’s potentially applicable for long-distance underwater acoustic communication. Given the sound generating mechanism of airguns, the generated signals cannot be modulated compared with sources signals that are more commonly used for communications purposes. Thus the use of time delay shift coding system, which is both necessary and advantageous under such circumstances. The detection of the impulsive signal from airgun blasting and accurate estimation of its arrival time at the receiving end is paramount for carrying out a time delay shift coding communication. Consequentially, augmentation of the signal-to-noise ratio (SNR) of received signal through enhancement is the most direct and effective approach. This manuscript presents an enhancement method of the airgun blasting signals: A recursive wavelet modulus maxima denoising method is introduced, by separating the raw signals into noise components and signal components iteratively, details information that is erroneously erased by conventional wavelet modulus maxima denoising method can thus been preserved. Coupled with the proposed use of a loop coefficient of determination, automatic balancing between denoising effectiveness and distortion of valid signals is acrhieved.
Functional-analytical solution of ocean acoustic tomography problem
Authors: Shurup A.S.
Published: October 2024

A three-dimensional scheme of mode adiabatic tomography of sound speed inhomogeneity in a shallow sea based on a two-dimensional functional-analytic algorithm is proposed and numerically investigated. To reconstruct three-dimensional scatterers from two-dimensional functions recovered by solving inverse problems for individual modes, Karhunen-Loeve functions are used, which allows to reduce the number of unknowns in solving the inverse problem. It is shown that the proposed scheme has a high resolution in horizontal plane when recovering high-contrast inhomogeneities. The solution of coupled Lippmann-Schwinger equations describing the effects of multichannel mode scattering is numerically implemented to model the scattering data. The presented numerical results illustrate possibility of achieving acceptable noise immunity of the regarded scheme using a broadband sensing regime and a series of repeated experiments.
Study on ultrasonic lamb wave testing technology of honeycomb sandwich structures
Authors: Wang Du , Cai Suyang , Wang Hongyuan , Chen Zhenhua , Huang Hui , Chen Dingyue , Wu Caibao
Published: October 2024

Honeycomb sandwich composite panels have complex structures, large sizes, many types of defects, and significant sound attenuation, which lead to low efficiency and poor sensitivity of ultrasonic non-destructive testing. In the study, a non-linear ultrasonic lamb wave testing technique for honeycomb sandwich composite panels is proposed. Firstly, the anisotropic propagation characteristics and modal structure of lamb waves in honeycomb sandwich composite panels are analyzed, and the lamb wave modes with non-linear ultrasonic accumulation are excited. Secondly, the data extraction method and imaging algorithm of non-linear ultrasonic lamb wave imaging testing are proposed. Finally, an enhanced imaging algorithm is proposed to improve image quality based on the sliding window algorithm. Based on the comparative analysis of air-coupled ultrasonic testing images and metallographic tests, it can be seen that non-linear ultrasonic lamb wave testing signals can be used to characterize the damage distribution characteristics of honeycomb sandwich composite panels, display debonding and weak debonding defects, and have the advantages of being able to perform on the same side testing and high efficiency, which can be used for non-destructive testing of honeycomb sandwich composite panels.
Ultrasonic testing method for impeller brazing defects with refraction wave perpendicular to brazing surface and angle amplitude compensation
Authors: Zhou Shiyuan , Cao Yuxin , Du Peicheng , Liu Luhang , Zheng Chong
Published: October 2024

There are blind areas in ultrasonic brazing defect detection, due to the non-parallel brazing surface and outer surface for many components including impeller. In this paper an oblique incident ultrasonic testing method with a refraction wave perpendicular to brazing surface is proposed. Meanwhile, an incident angle amplitude compensation is implemented to decrease the influence of the defect echo amplitude difference caused by oblique incidence and unify the sensitivity of different scanning positions. The compensation curve based on the theoretical curve of echo energy at different incident angles is optimized with iteration of actual measured defect echo amplitude. In order to prove the need for ultrasonic testing method with a refraction wave perpendicular to brazing surface, bottom surface echo test for conical samples is operated. In addition, with the method proposed in this paper, scanning image of impeller sample with the same detection sensitivity is obtained successfully. Testing results suggest that in relation to old method with incident wave perpendicular to the outer surface, the method proposed in this paper can solve the blind area problem effectively.
Acoustic Metasurfaces for Efficient Modulation and Demodulation of OAM Multiplexed Signals in Acoustic Communication
Authors: Liu Zhi , Huang Baolin , Lin Wei
Published: October 2024

Orbital angular momentum (OAM) multiplexing has been suggested as a potential solution to increase the data capacity of acoustic communication systems. A method of modulation and demodulation of OAM multiplexed signals using acoustic metasurfaces is proposed in this manuscript. The amplitude and phase of independent acoustic orbital angular momentum (AOAM) multiplexed signal provide orthogonal degrees of freedom. By designing appropriate acoustic metasurfaces and combining them with binary differential phase coding techniques, we demonstrated that efficient modulation and fast demodulation of AOAM multiplexed signals can be achieved. Orthogonal acoustic spiral modes prevent mode coupling and crosstalk, enhancing acoustic multiplexing. The resonance-based structure provides signal frequency selectivity, boosting efficiency and simplifying terminal equipment for practical applications, which leads to the creation of high-capacity acoustic communication systems.
Two-step scattering theory method for designing metamaterials
Authors: Dmitriev K V , Smirnykh D V
Published: October 2024

A two-step method for designing an acoustic metamaterial with desired properties is proposed. At the first step, the scattering matrices of its elements are calculated using the Lippmann-Schwinger type equation. For scatterers of small wave size, the problem is reduced to determining the phases of several scattering coefficients. At the second step, the particular design of metamaterial elements is determined. This problem can be considered an inverse scattering problem or a problem of optimizing the geometric parameters of a metamaterial element. The second approach turns out to be more practically applicable. As an example, a metamaterial in the form of a reflective layer with a narrow waveguide channel is considered, and the design of its elements is determined with the proposed method.
Nonlinear dynamics of a bubble cluster in liquid cavity wrapped by elastic medium
Authors: Zhang X M , Zuo X Y , Li W N , Wang C H
Published: October 2024

According to the modified nucleation theory, gas nuclei can generate and grow into cavitation bubbles when’s the liquid pressure exceeds a threshold in a cavity. Based on the modified nucleation theory, the growth process of the gas nuclei in a liquid cavity can be simplified to two “events”, and the full confinement effects of the surrounding elastic medium of the cavity was considered by including the bulk modulus in the equation of state. The dynamical equations were derived to model the nonlinear oscillation of the multi-bubble system in the cavity. The effects of acoustic parameters, the initial radius and the total number of bubbles on bubble dynamics were investigated numerically. It is found that bubble behaviors are sensitive to the acoustic field. In the low frequency region (f <1MHz), bubble oscillation exhibits a modulated waveform, and fundamental, subharmonic and harmonic modes can be found in the acoustic response curve. The oscillations of confined bubbles diminish with increasing frequency. In the high frequency region (f >1MHz), the confinement state affects the acoustic response of the gas nuclei, and the growth rate differ by a factor of 5 difference in the presence of shelled or unbounded elastic confinement of the cavity. Therefore, the suppression or enhancement of cavitation growth and collapse in confined cavity can be modulated by a variety of factors, such as the total number of nuclei, cavity size, acoustic frequency and amplitude, negative pressure, and elastic medium, which have a synergistic influence on the confined cavitation process.
The velocity fields around aspherical bubbles
Authors: Wu Y R , Wang C H
Published: October 2024

This paper studies the simplest system, which can possess the left-right symmetrical and asymmetrical surroundings, three bubbles in a line. Assuming that the deformations are small, the surfaces of bubbles are described by a combination of the first three Legendre polynomials, that is, spherical symmetrical mode P0, antisymmetrical mode P1 and symmetrical mode P2. Based on the dynamics of three-bubble system, this paper further studies the velocity fields distribution around them. It can be seen from the contour distribution of the velocity field that the velocity component always decreases with the increase of the distance r. When three identical bubbles are separated uniformly, the velocity field around the central bubble is always in a symmetric, while there are asymmetric velocity fields around two side bubbles.
Angular spectrum method for acoustic beam in anisotropic media and structures
Authors: Xu Wei-Jiang , Zhang Jin-Ying , Wu Xian-Mei , Cheng Qian , Dupont Samul
Published: October 2024

The Angular Spectrum (AS) method is commonly used to calculate the propagation of scalar wave fields. This study extends the application of AS to vector wave propagation, specifically addressing acoustic waves in anisotropic media. The approach involves using plane wave spectra to express all possible mode waves, namely one q-P wave and two q-S waves, that propagate in various directions in the medium. These AS are determined by applying boundary conditions at the source surface where the vector waves are generated and the modes waves are coupled. AS decomposition of waves requires the determination of complex wavenumber vectors (or slownesses) through the Christoffel equation, including both propagating and evanescent waves. The determination of the acoustic beam profile in TeO2 crystals is presented as an application example of AS.
High Sensitivity Performance of Piezoelectric Micromachined Ultrasonic Transducer Employing Sc-Doped AlN Thin Film
Authors: Liu Xiaonan , Zhang Qiaozhen , Chen Mingzhu , Zhao Xiangyong
Published: October 2024

Aluminum Nitride (AlN) based piezoelectric micromachined ultrasonic transducers (PMUTs) have been the prime choice in acoustic imaging, because it has advantages of high frequency and thus high resolution. However, low piezoelectric constants of AlN gives rises to limitation in transmitting sensitivity. Scandium (Sc) doping method for AlN can be used to improve its piezoelectricity. In this paper, single element PMUT based on ScAlN thin film was proposed and modeled by performing finite element method (FEM). Influence of different electrode configurations on PMUT performance were studied. The results show that, compared with other electrode configurations, PMUT has the best overall performance when the upper electrode is platinum (Pt) and the lower electrode is molybdenum (Mo). In addition, the acoustic field characteristics and its dynamic analysis of PMUT based on ScAlN in water were studied. The investigation results demonstrated that the relative pulse-echo sensitivity level M of PMUT is significantly improved with the increase of Sc doping concentration in AlN thin film. When the Sc concentration is 40%, the M reaches -44 dB, which is 20 dB higher than that without Sc (-64 dB). The PMUT based on the high Sc-doped AlN thin film has a larger effective electromechanical coupling coefficient and sensitivity, which is beneficial to the application in high sensitivity ultrasound imaging.
Acousto-optic femtosecond laser beam shaping for bottle-beam generation
Authors: Obydennov Dmitry , Yushkov Konstantin , Molchanov Vladimir
Published: October 2024

This study explores the properties of a laser beam shaping system comprising an acousto-optic dispersive delay line (AODDL) and an acousto-optic tunable filter (AOTF) for ultrashort laser pulse shaping. The system demonstrates the AODDL’s ability to generate signals with arbitrarily positioned transmission windows and investigates the impact of spectral width on field distributions. The AOTF’s frequency scanning and simultaneous control of two and three spectral components are presented. The experimental setup utilizes femtosecond laser radiation, and the results highlight the system’s versatility for programmable spectral and spatial filtering, offering potential applications in advanced optical manipulation.
A pulse-echo measurement setup to determine viscoelastic material parameters
Authors: Dreiling Dmitrij , Itner Dominik , Hetkämper Tim , Birk Carolin , Gravenkamp Hauke , Henning Bernd
Published: October 2024

Due to their versatility, the application of polymers in research and industry continues to increase. Since the majority of design processes are simulation-aided, precise material parameters are required to obtain realistic results. The quasi-statically and destructively measured material parameters provided by manufacturers for this purpose are usually insufficient. An acoustic method is generally capable of measuring the frequency-dependent viscoelastic material parameters in a non-destructive manner. In particular, an ultrasonic transmission measurement setup for determining these parameters has already been presented in previous publications. However, this approach has several drawbacks, including a low sensitivity to shear parameters. To increase the sensitivity to shear parameters, a measurement setup using a pulse-echo method with a corresponding inverse approach is presented to obtain viscoelastic material parameters of polymers. A brief comparison is made between the transmission and pulse-echo methods.
Enhancement in performance of SAW resonator on LN/SiC substrate by take slowness asymmetry into account
Authors: Liu H L , Zhang Q Z , Sun H , Yang Y , Gu Y D , Wang N
Published: October 2024

Layered structures comprising high-coupling lithium niobate (LiNbO3, LN) piezoelectric thin plates bonded to high-velocity SiC substrates have attracted much attention of high-performance surface acoustic wave (SAW) devices. However, such these layered structures exhibit severe Rayleigh mode spurious responses that degrade the performances of SAW devices. This paper explores the generation mechanism of spurious modes on LN/SiC layered structure, and proposes an optimized layered structure with suppressed Rayleigh spurious modes. The investigation involves deriving the Euler angle range of LN by analysing the slowness surface of both LN and SiC. In addition, it is worth noting that slowness surface overlaps at some Euler angle ranges, which will cause coupling between different modes, thus generating spurious mode. Simulation result shows the frequency characteristics of SAW resonator at resonant and anti-resonant frequencies of 4.3 GHz and 4.88 GHz of SH mode, achieving a K
2 of up to 26.5% and a quality factor Q of 828. It is proved that the optimization structure offering larger K
2, higher velocity and improved Q values and Rayleigh spurious mode suppression, which is favourable for wideband and high frequency SAW devices applications.
Defect Recognition and Classification Using Ultrasonic Scattered Signals Based on Convolutional Neural Network
Authors: Chen Yuanyuan , Shi Fangfang , Kong Chao
Published: October 2024

Carbon Fiber Reinforced Polymer (CFRP) is widely used in the aerospace, aircraft, and railway industries because of its remarkable advantages, such as its lightweight and high strength. Detecting and identifying defects in CFRP is crucial for ensuring its secure and efficient use. Ultrasonic non-destructive testing is one of the most practical and effective methods for defect detection and identification. The ultrasonic scattered signals of defects, which contain abundant defect feature information, are advantageous for defect recognition and classification. However, the anisotropy and inhomogeneity of CFRP, which lead to a low signal-to-noise ratio and poor image quality, pose challenges in flaw recognition. To address the issue, this paper proposes using Convolutional Neural Networks (CNN) methods for defect classification, which can adequately extract information from ultrasonic scattered signals directly. The scattering signals from various types of defects in CFRP, including the different sizes of holes and folds, were selected as inputs for CNN models. Different network models combining Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) with 1D-CNN were employed to classify and identify defect signals. To generate sufficient input sample signals, the data sets were further enlarged by incorporating noise into the original signals. The experimental results showed that using the 1D-LSTM-CNN and 1D-GRU-CNN network models can reduce computational resources while ensuring the accuracy of defect recognition.
Numerical simulation of scattering of TWIPS by underwater air bubble
Authors: Li Feishan , Zhang Yuxiang , Sheng Xueli , Zhang Jiangyi
Published: October 2024

The interaction of water with the subsurface of sea-ice leads to the generation of air bubbles. This heterogeneity results in additional challenges for unmanned underwater vehicles (UUV) conducting active detection in the upper water column of the Arctic Ocean. Under excitation by a high-amplitude acoustic source, asymmetric oscillations of the bubble are generated due to the high compressibility of gas, which further leads to acoustic scattering showing nonlinear characteristics. The corresponding signals may interfere with or even mask the echoes from potential targets, which are often linear scatterers, ultimately impairing the UUV’s active sensing capabilities under the sea-ice. Twin Inverted Pulse Sonar (TWIPS) is an underwater detection technique consisting of sending two pulse signals of equal amplitude but with opposing phases, benefiting from the difference in the responses of the bubble and target and the resulting echo signals for the eventual distinguishing. In this study, a numerical modeling of underwater bubbles for the acoustic study is developed by making use of both multiphysics and moving mesh features of Comsol. Numerical simulations were conducted to investigate the nonlinear feature of acoustic scattering from air bubbles. These results are then compared with analytical results for verification. Monochromatic signals and TWIPS at different frequencies are used as excitation signals, and the response of spherical air bubbles and the resulting scattered wave field are calculated, compared, and analyzed.
Defect recognition and classification from ultrasonic phased array total focusing method imaging based on domain adaption
Authors: Wang Haibin , Cheng Jingwei , Chen Wei , Li Rui , Wang Zhe , Bu Yangguang , Tang Jian , Yan Chang , Ji Tian , Li Kang , Liu Jiapeng
Published: October 2024

With the rapid development of China’s economy, the demand for oil and gas resources is continuously increasing, leading to the expansion of the scale of oil and gas long-distance pipelines. Consequently, the risk of safety incidents in oil and gas pipelines is on the rise. Welding defects are identified as one of the significant factors contributing to safety incidents in long-distance oil and gas pipelines. In comparison to traditional conventional ultrasonic detection techniques, which exhibit low efficiency and accuracy, ultrasonic phased array detection technology has the capability to accurately detect welding defects in oil and gas long-distance pipelines. This is particularly true with the development of total focusing method imaging technology, enabling quantitative defect analysis and localization in oil and gas long-distance pipelines.However, in the current scenario, analyzing the types of defects in massive data from long-distance pipelines requires human intervention, leading to low detection efficiency and subjective influence on result analysis. Addressing challenges such as low efficiency in human evaluation of defects in ultrasonic phased array detection, low accuracy in traditional image recognition methods, strong subjectivity in manually extracting features, and the absence of a standardized industrial dataset for ultrasonic phased array detection defects, especially in the case of limited data on ultrasonic phased array detection of welding defects, this study focuses on small sample defects in phased array detection images. The study proposes an improved ResNet50 algorithm through domain adaptation in a deep neural network, trained on a large-scale model data, and then applied to ultrasonic phased array detection data. This approach achieves accurate identification and classification of typical volumetric defects (such as pores) and typical area defects (such as cracks) in the phased array detection of welding defects, laying the foundation for intelligent recognition of defects in long-distance oil and gas pipelines.
An integrated multichannel system for air-coupled CMUT array imaging and guided wave detection applications
Authors: Wang Junjie , Li Shaojie , Zhang Hui , Wang Zhuochen
Published: October 2024

Capacitive micromachined ultrasonic transducers (CMUTs) made by MEMS process have become a new choice for air-coupled ultrasonic transducers due to their high sensitivity, low acoustic impedance and easy arraying. At present, in the air coupling application of CMUT transducer, due to the weak signal strength of single element, the CMUT array usually works in a whole piece, limiting the advantage of the array. Therefore, a multi-channel air-coupled CMUT imaging system with high-voltage DC bias and low-noise high-gain current signal amplification is designed to realize the electronic scanning of our CMUT arrays. The imaging system has 16 transmit and receive channels, and each channel consists of pulse transmitting circuit, AC/DC coupling circuit, impedance matching circuit, low-noise transimpedance amplification circuit, controllable gain amplification circuit and AD circuit. The imaging chain and element control method of our CMUT array were developed to realize the electronic scanning imaging of air-coupled ultrasound. The feasibility of the system for non-destructive testing was also verified via the Lamb wave detection in a metal plate.…
A High Q Lamb Wave Resonator with Dummy Toes Based on 20% ScAlN Film
Authors: Yang Sijie , Liu Wenjuan , Wen Zhiwei , Cai Yao , Liu Yan , Sun Chengliang
Published: October 2024

The lamb wave resonator (LWR) based on aluminum nitride (AlN) films are preferred strategy for high-frequency filters in 5G communication due to the tunable electromechanical coupling and high Q value. However, since the low electromechanical coupling and piezoelectric coefficient of AlN films, conventional lamb filters are difficult to meet the requirements of high bandwidth and low loss. This work proposes a lamb wave resonator with dummy toes (DT-LWR) based on scandium-doped aluminum nitride (ScAlN) film to improve the quality factor(Q) meanwhile suppress the spurious modes. The processed DT-LWR was tested using a vector network analyser (VNA, Keysight N5222B), and the MBVD model was used to fit the Z parameters. The Q value of DT-LWR is 1437.23, while that of LWR is 1250.09. It is increased by 14.97%. The enhancements make the DT-IWR as an ideal for filters with minimal insertion loss.
Writing and Work
Authors: Rembis Michael
Published: October 2024

In a nineteenth-century world where madness was social and biological, open and fluid, and rooted in relationships, work played a central role in mad people’s lives and in the writing of former asylum inmates. The state, physicians, journalists, and mad writers considered the ability to perform certain forms of gendered labor a powerful measure of madness, and each offered different, often competing, perspectives on the relationship between madness and work. Mad writing was also a form of work that, to date, has not been explored by historians. Both women and men had to secure the resources, cultivate the relationships, and make the time necessary to write. For women, who faced limited social and economic options after asylum commitment, writing and speaking in public could be their only form of work.
Navigating dementia feeding decisions in Asia: a mixed methods study of caregivers
Authors: Andres Ellie B , Chaudhry Isha , Balasubramanian Ishwarya , Poco Louisa , Yap Philip , Malhotra Chetna ,   PISCES study group, Seow Dennis , Tan Lay Ling , Tham Weng Yew , Vaingankar Janhavi , Foo Jason , Tan Boon Yeow , Tong Kamun , Ng Wai Chong , Allen John Carson , Malhotra Rahul , Wee Weng Mooi Tan Shiou Liang , Ng Li Ling , Goveas Richard , Mok Vanessa , Sim Alisson , Ng Wei Fern , Wong Hon Khuan , Balasundaram Bharathi , Tan Rui Qi , Ong Pui Sim , Cheong Chin Yee , Yee Alethea , Pheng Chung , Tiong Christina , Hum Allyn , Lee Angel , Finkelstein Eric A
Published: October 2024

Background

Tube feeding is discouraged among older adults with advanced dementia; nevertheless, caregivers often find feeding decisions challenging to navigate.

Aim

This study aims to gain a comprehensive understanding of tube feeding among community-dwelling older adults with advanced dementia in Singapore and its relationship to older adult quality of life (QoL) and caregiver psychological distress.

Methods

We use a convergent mixed-methods design, synthesising analysis of qualitative caregiver interviews (n = 25) and two-year prospective, longitudinal cohort survey data (n = 215, 1018 observations).

Results

Findings from the qualitative interviews revealed caregivers’ expectations of reduced QoL for older adults with feeding tubes and their own distress related to making feeding decisions and fears prompting plans to tube-feed. Sixteen percent of community-dwelling older adults with advanced dementia relied on feeding tubes during the two-year study period. Adjusting for potential confounding and using instrumental variables estimation, tube feeding was associated with reduced older adult QoL (P < .05) and increased caregiver anxiety and depression (P < .10).

Conclusion

Consistent with expert guidelines, we found that tube feeding was associated with significantly reduced QOL among older adults living with dementia and increased distress among caregivers relative to those of older adults without feeding tubes. Despite caregivers’ recognition of reduced QOL associated with older adult use of feeding tubes, many expressed angst related to feeding choices. Our findings suggest the need for decision tools to support caregivers in making informed decisions concordant with their values.
Global longitudinal strain measurement in the modern era - is artificial intelligence the answer ?
Authors: Botan R , Winkler A , Dindane Z , Alothman G , Sveric K , Linke A
Published: October 2024

Background

Global longitudinal strain (GLS) enhances the assessment of left ventricular (LV) function beyond ejection fraction (EF) in 2D echocardiography (Echo). However, manual GLS measurement, the most common technique, is operator dependent. A novel vendor-independent artificial intelligence (AI)-based software streamlines automated 2D-Echo exam evaluation and GLS calculation.

Purpose

We sought to evaluate the ability of the AI to automatically identify LV 4-, 2-, and 3-chamber views (CV) from 2D-Echo exams and to validate GLS against the conventional manual method.

Methods

540 patients underwent standard 2D-Echo exams. The server-based AI recognized the optimal LV CVs from 2D-Echo exams and automatically calculated triplane GLS by endocardial delineation (n=489, 91%). Manual LV GLS was performed independently by accredited cardiologists. Pearson’s correlation (R) and Bland-Altman analysis were performed to assess bias and limits of agreement (LOA) for GLS. Multivariate between-method regression was performed using ordinary least squares to disclose possible sources of possible bias. Significance was defined as a 2-tailed P value < 0.05.

Results

Patients’ median age was 70 years [18-93], 59% were males. The 2D-Echo indications were coronary artery disease (36%), valvular heart disease (15%), non-ischemic heart failure (15%) and others (34%). The feasibility of the AI to calculate GLS was 91% (n=489) due to endocardial border delineation issues. AI correctly classified all CVs. An excellent correlation (r=0.92, p<0.001) was observed between AI and manual GLS, with low bias (0.5%) and narrow LOAs (-3.1 and +4.2%) (Figure 1, top row). We identified LV end-diastolic volume and EF as statistically significant confounders (p < 0.05) with only small effect as depicted in Figure 1 (bottom row). Neither sex, age, acoustic window, body mass index, nor heart rate, along with the interaction with sex, end-diastolic volume, or EF, were significant (p > 0.23).

Conclusion

AI-based LV GLS calculation in 2D-Echo shows promising feasibility and accuracy. Strong agreement between AI-derived GLS and manual measurements supports its reliability. The AI's ability to identify optimal LV views underscores its robustness. Further validation and refinement are warranted, highlighting the transformative potential of AI in advancing cardiovascular diagnostics.
Evaluating the performance of automatic wave speed estimators of natural shear waves to assess myocardial stiffness
Authors: Araujo Andrade Sousa A , Orlowska M , Wouters L , Youssef A , Caenen A , Duchenne J , D'hooge J , Voigt J U
Published: October 2024

Introduction

Cardiac Shear Wave Elastography is an emerging non-invasive technique using ultrafast echocardiographic imaging. Natural shear waves (SW) occur after mitral valve closure (MVC) and aortic valve closure (AVC), and their propagation velocities are directly related to myocardial stiffness. However, the current assessment of SW velocities lacks a gold standard method, and relies on manual measurements with their inherent variability.

Purpose

To explore new automated methods for shear wave velocity estimates, aiming to achieve greater accuracy, less variability, and high feasibility.

Methods

To visualize shear waves, anatomical M-modes were drawn (4±1 cm) along ventricular septum in parasternal long axis views (PLAX), acquired with high-frame-rate echocardiography (1055±159 Hz). M-modes were colour coded for tissue acceleration. SWs appear as tilted green bands after MVC & AVC, the slope of which represents the SW propagation velocity. One hundred-twenty different slopes from healthy volunteers (n=67) and patients (n=53) were measured manually and with 9 different automatic methods. All automatic methods were initiated by indicating the approximate position of the shear wave in the M-mode with a mouse click of the user. Measurements were repeated three times to assess measurement reproducibility. (figure 1, A). In order to determine the influence of display settings, three different acceleration colour scales were tested (0.5, 1, 2 m/s²). (Figure 1, B). Failure of correctly identifying shear waves was counted to assess feasibility. Due to the lack of a gold standard, manual measurements of an experienced reader served as reference.

Results

Three of nine automatic methods: Radon Transformation (RT), Regression Segmentation Maximum value (RM), Regression Segmentation Weighted Maximum (RMW), revealed the least variability with repeated measurements (0.0±0.0 m/s for all) and colour scales (0.0±0.0, 0.1±0.2 and 0.1±0.2 m/s, resp.). Those three methods showed moderate to good agreement (r=0.66, ICC 0.77 [CI 0.64- 0.85]; r= 0.67, ICC 0.75 [CI 0.50 -0.86]; and r= 0.77, ICC 0.85 [CI 0.73-0.90], resp.) with manual measurements (r=0.96, ICC 0.98 [CI 0.97- 0.99] (figure 2).

Conclusion

RT, RM, and RMW showed a good reproducibility while RMW showed the best agreement with manual measurements. Our data suggest, that the RMW method could offer an objective alternative for SW velocity estimations. Further research is needed to explore their applicability in clinical scenarios.
Usefulness of left ventricular mechanical dyssynchrony for predicting atrial fibrillation and adverse outcomes following first atrial fibrillation event
Authors: Alhakak A , Skaarup K G , Lassen M C H , Johansen N D , Jensen G B , Schnohr P , Mogelvang R , Biering-Sorensen T
Published: October 2024

Background

Left ventricular mechanical dyssynchrony (LVMD) has shown to predict many cardiovascular outcomes including ventricular arrhythmias. Our hypothesis is that LVMD can reveal early atrial dysfunction.

Purpose

The aim of this study was to investigate whether LVMD can be used to predict atrial fibrillation (AF) and adverse outcomes following first AF event in individuals from the general population.

Methods

A total of 3785 individuals (mean age 55±17 years, 57% women) from the general population free of AF, heart failure (HF) and prior stroke had an echocardiographic examination performed including two-dimensional speckle tracking echocardiography. LVMD was calculated as the standard deviation of the regional time-to-peak strain from the three apical views. The primary endpoint was AF, and the secondary endpoint was complicated AF as assessed by the occurrence of either stroke or HF after the diagnosis of AF.

Results

During a median follow-up of 5 years (interquartile range, 4.4-6.2 years), 142 (4%) individuals were diagnosed with AF, and of these 22 (15%) individuals developed HF or stroke. LVMD was a univariable predictor of AF (per 10ms increase: HR 1.03; 95% CI (1.02-1.05), p<0.001, Figure). The association remained significant even after multivariable adjustment for age, sex, body mass index, diabetes, hypertension, heart rate, previous ischaemic heart disease, systolic blood pressure, diastolic blood pressure, smoking, left ventricular ejection fraction, global longitudinal strain, left atrial volume index (LAVI), and E/e’ (per 10ms increase: HR 1.02; 95% CI (1.00-1.04), p=0.042). LVMD also predicted complicated AF, and the association remained significant even after multivariable adjustment (per 10ms increase: HR 1.05; 95% CI (1.01-1.09), p=0.026).

Furthermore, LVMD provided incremental prognostic information over the LAVI with regard to predicting AF (Harrell’s C-statistics 0.66 vs. 0.70, p=0.012).

Conclusion

In a low-risk general population, LVMD provides prognostic information on the risk of AF. Additionally, LVMD can identify individuals with complicated AF defined as occurrence of either stroke or HF following the diagnosis of incident AF. Furthermore, LVMD provides incremental prognostic information over the LAVI in predicting AF.
Left atrial strain demonstrates the ability to distinguish patients with pre and post-capillary pulmonary hypertension
Authors: Bauer F , Raitiere O , Artaud Macari E , Besbes B , Si Belkacem N , Saidi N , Savale L
Published: October 2024

Background

The characterization of pulmonary hypertension (PH) patients into pre or postcapillary (pcPH)phenotypes poses a challenge during screening due to the ambiguity surrounding their comorbidities. This distinction is crucial as it influences treatment decisions and prognostication.

Purpose

Investigating Left Atrial Strain as a Discriminant Marker for Distinguishing Pre and Post-Capillary PH.

Methods

Out of 164 patients exhibiting both pre- and post-capillary phenotypes, 97 had optimal left atrial 2D strain. Left atrial 2D strain was performed with a GE Vivid9 ultrasound machine equipped with dedicated software, ensuring meticulous attention to image quality and region of interest thickness restricted to a maximum of 6 mm. Subsequently, the peak left atrial strain during reservoir function was quantified as part of the investigation. To determine the optimal cut-off value, ROC curve analysis was employed.

Results

60 patients had pcPH while 37 had pre-capillary PH. Mean age was 65±12y. Mean pulmonary artery pressure, wedge pressure, cardiac output and pulmonary vascular resistance averaged 40,9±10,7 mm Hg, 15,7±8,7 mm Hg, 5,9±2,0 l/min and 4,7±3,1 WU, respectively. Left atrial 2D strain ranged from +2,5% to 60%, with a mean of +18,2±11,2%. From ROC cure analysis, patients with LA 2D strain > +19,1% had a precapillary phenotype with a sensitivity and a specifity of 93% and 88% respectively (Fig 1). Left atrial 2D strain demonstrates higher sensitivity compared to various parameters, such as scores from the European Society of Respiratory Disease, left ventricular end-diastolic pressure estimation from the American Society of Echocardiography, HFA-PEFF score, and H2FPEF from the AHA.

Conclusion

Left atrial 2D strain demonstrates superior sensitivity in distinguishing between patients with pre and post-capillary pulmonary hypertension compared to other assessment methods.FIG 1:Left atrial 2D strainFig 2:SENS of parameters and scores