bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the intercultural potential of picturebooks in early secondary EFL classrooms in Austria
Authors: Peskoller Jasmin , Bader Caroline
Published: October 2024

Intercultural education has constituted an interdisciplinary teaching principle in Austrian upper and lower
secondary curricula since 1992 and was reinforced by a decree in 2017. Literary texts have been identified as promising resources
and valuable tools for initiating intercultural learning through their frequently inherent multi-perspectivity encouraging
students to empathize with characters, consider different perspectives, contrast viewpoints, relate stories to personal
experiences, and reflect on diverse ideas. However, research on the implementation of intercultural teaching and learning using
literature in foreign language classrooms has so far mostly focused on upper secondary education and has frequently related to
using postcolonial fiction writings. To counter the knowledge gap on the implementation of intercultural learning in lower
educational levels, this study adopts a literary science approach to explore the potential of picturebooks in early secondary EFL
classrooms. Using The Little Green Jacket (Dee, 2020), it specifically
examines perspective-taking as a key dimension of intercultural learning. Through written learner reflections, the research study
assesses whether students in two Austrian EFL classrooms (n = 35) can adopt a different viewpoint. The findings
show that most students are successful, or at least partly successful, in perspective-taking and mostly describe emotions of
sadness but also hopefulness in their reflective writings. Thus, the study suggests that picturebooks have the potential to
facilitate perspective-taking as an essential dimension of intercultural education among young EFL learners with low language
proficiency, highlighting their largely untapped potential in early language education.
Exploitation of Biobased Co-Product Streams; Contributing to European Protein Demands Using Ethanol Plant Derived Co-Products
Authors: Williams Peter E.V. , Burton Emily
Published: October 2024

Europe is short of high-quality protein for animal feed, being only 29% self-sufficient in high-quality protein and relies heavily on imported proteins. But consumer demand is shifting towards more sustainable, home-grown sources of plant-based protein. This presents a significant challenge for the animal feed industry. Establishing a new plant protein crop for Europe would take a decade to create elite, geographically adapted varieties, adopt new agronomic practices, and establish appropriate supply chains. Approximately 9 million tons of European non-GM grains (maize, wheat, barley and rye) are converted annually by fermentation into bioethanol, a renewable fuel. The residue of the grain is currently used as medium-quality protein animal feed (distillers dried grains and solubles (DDGS; approx. 30% crude protein). Mechanically processing to separate the protein from the fibre fraction produces a Super-Pro (>50%crude protein concentration). The process produces commercially viable quantities of high-quality, non-GM grain protein, that can be used as an alternative to imported soybean products, in a time frame significantly ahead of establishing alternative agronomies or developing alternative novel proteins. Processing technology can transform low-quality co-product steams into high-quality alternative animal feed products and merits further investigation as a means of producing sustainable animal feed. Re-engineering grain bioethanol plants into biorefineries allows them to produce a super high protein (>50% crude protein) feed material concurrently with bioethanol, a renewable fuel.

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A study of self-similar vector fields in bianchi type III spacetime via Rif tree approach
Authors: Shakeel Mehnaz , Khan Jamshed , Rezapour Shahram , Akhtar Sumaira Saleem , Zahir Hina , Inc Mustafa
Published: October 2024

In this study, we use the Rif tree approach to explore self-similar vector fields in Bianchi type III spacetime. This work adopt a computer-based method to transform symmetry equations into an involutive form that is simplified and divides the integration problem into multiple cases, each represented as a tree structure. In some cases, the metric functions are subject to particular constraints. These conditions allow one to solve the system of equations governing self-similar symmetries and provide explicit formulations for the metrics and their corresponding self-similar vector fields. This approach is novel in that it covers not only the analysis of the direct integration strategy but also some metrics that are practically relevant. For a detailed investigation of the created models, stability and physical importance are also considered.
A wideband circularly polarized four port microstrip MIMO antenna with high gain and enhanced isolation for 5G millimeter frequency applications
Authors: Elalaouy Ouafae , El Ghzaoui Mohammed , Das Sudipta , Jackson Beulah , Madhav BTP , Foshi Jaouad
Published: October 2024

In this article, a MIMO antenna system featuring wide bandwidth, high gain, and circular polarization for 5G communication networks is presented. The proposed antenna enabled high data rates, enhanced signal reliability, and improved performance in dynamic and challenging 5G environments. Wide bandwidth ensures compatibility with various 5G frequency bands, while circular polarization allows for better signal propagation and reception, particularly in non-line-of-sight scenarios. In that regard, the present paper addresses an enhanced bandwidth 4-port circularly polarized MIMO antenna to encounter polarization mismatch along with high data rates. The suggested MIMO antenna comprises four identical patches strategically positioned in orthogonal orientations in such a way as to provide the circular polarization direction. Meanwhile, the bandwidth is extended by inserting straightforward defected ground structure (DGS) and L slots. The MIMO antenna offers an impedance bandwidth covering from 24 GHz to 28.8 GHz and an axial ratio bandwidth of 62% within the overall band. It demonstrates excellent performance with a high peak gain of approximately 14.84 dBi. Additionally, it exhibits strong isolation of more than 20 dB among the closely packed antennas, ensuring reliable communication and minimizing interference. The combination of these features in a MIMO antenna system is crucial for meeting the demanding requirements of 5G communication, including increased data capacity, low latency, and reliable connectivity. The simulated and measured outcomes exhibit robust concurrence, signifying a high level of accuracy. Consequently, the suggested MIMO antenna appears well-suited for the 5G bands designated for deployment in the USA (27.50–28.35 GHz) and Europe (24.25–27.5 GHz).
Odd-even mass differences of well and rigidly deformed nuclei in the rare earth region: Test of a newly proposed fit for average pairing matrix elements*
Authors: Hao T. V. Nhan , Nguyen N. N. Bao , Tam D. Quang , Quentin P. , Bonneau L. , Koh 辜 Meng-Hock 明福
Published: October 2024

We present an analysis of a recent approach for determining the average pairing matrix elements within a specified interval of single-particle (sp) states around the Fermi level, denoted as λ. This method, known as the uniform gap method (UGM), highlights the critical importance of the averaged sp level density

. The pairing matrix elements within the UGM approach are deduced from microscopically calculated values of

and gaps obtained from analytical formulae of a semi-classical nature. Two effects generally ignored in similar fits are addressed: (a) a correction for a systematic bias introduced by fitting pairing gaps corresponding to equilibrium deformation solutions, as discussed by Möller and Nix [Nucl. Phys. A 476, 1 (1992)], and (b) a correction for a systematic spurious enhancement of

for protons in the vicinity of λ, caused by the local Slater approximation commonly employed in treating Coulomb exchange terms (e.g., [Phys. Rev. C 84, 014310 (2011)]). This approach has demonstrated significant efficiency when applied to Hartree-Fock + Bardeen-Cooper-Schrieffer (BCS) calculations (including the seniority force and self-consistent blocking for odd nuclei) of a large sample of well and rigidly deformed even-even rare-earth nuclei. The experimental moments of inertia for these nuclei were reproduced with an accuracy comparable to that achieved through direct fitting of the data [Phys. Rev. C 99, 064306 (2019)]. In this study, we extended the evaluation of our method to the reproduction of three-point odd-even mass differences centered on odd-N or odd-Z nuclei in the same region. The agreement with experimental data was found to be comparable to that obtained through direct fitting, as reported in [Phys. Rev. C 99, 064306 (2019)].
Anchoring temporal convolutional networks for epileptic seizure prediction
Authors: Rao Songhui , Liu Miaomiao , Huang Yin , Yang Hongye , Liang Jiarui , Lu Jiayu , Niu Yan , Wang Bin
Published: October 2024

Objective. Accurate and timely prediction of epileptic seizures is crucial for empowering patients to mitigate their impact or prevent them altogether. Current studies predominantly focus on short-term seizure predictions, which causes the prediction time to be shorter than the onset of antiepileptic, thus failing to prevent seizures. However, longer epilepsy prediction faces the problem that as the preictal period lengthens, it increasingly resembles the interictal period, complicating differentiation. Approach. To address these issues, we employ the sample entropy method for feature extraction from electroencephalography (EEG) signals. Subsequently, we introduce the anchoring temporal convolutional networks (ATCN) model for longer-term, patient-specific epilepsy prediction. ATCN utilizes dilated causal convolutional networks to learn time-dependent features from previous data, capturing temporal causal correlations within and between samples. Additionally, the model also incorporates anchoring data to enhance the performance of epilepsy prediction further. Finally, we proposed a multilayer sliding window prediction algorithm for seizure alarms. Main results. Evaluation on the Freiburg intracranial EEG dataset shows our approach achieves 100% sensitivity, a false prediction rate (FPR) of 0.09 per hour, and an average prediction time (APT) of 98.92 min. Using the CHB-MIT scalp EEG dataset, we achieve 97.44% sensitivity, a FPR of 0.12 per hour, and an APT of 93.54 min. Significance. These results demonstrate that our approach is adequate for seizure prediction over a more extended prediction range on intracranial and scalp EEG datasets. The APT of our approach exceeds the typical onset time of antiepileptic. This approach is particularly beneficial for patients who need to take medication at regular intervals, as they may only need to take their medication when our method issues an alarm. This capability has the potential to prevent seizures, which will greatly improve patients’ quality of life.
Reconstruction of sound speed and absorption coefficient of soft biological tissues by ultrasound tomography
Authors: Zotov D I , Dmitriev K V , Rumyantseva O D
Published: October 2024

The problem of reconstructing the internal structure of an object under study with high resolution is considered. The structure is described by spatial distributions of sound speed and ultrasound absorption coefficient. These acoustic characteristics are reconstructed in the form of quantitative values. Such a problem set is typical for the inverse problems of tomographic type. Special algorithms for processing experimental data have been developed for this purpose. High resolution of reconstructed images is ensured thanks to multi-view information about the object under study and taking into account the processes of multiple scattering of acoustic waves.
Numerical investigation of the number of excitation elements-dependent acoustic field characteristics of a histotripter
Authors: Xiong Jiupeng , Xing Baicheng , Zhou Yufeng , Li Faqi
Published: October 2024

Histotripsy is an emerging ultrasound technology for disintegrating various soft tissues noninvasively and accureately. However, it is difficult to characterize the acoustic field of a histotripter using the existing measurement methods (i.e., hydrophones) because of the damage potential of bubble cavitation on the sensing element under such high irradiation power. In this work, according to a quantitative relationship between the acoustic pressure and ultrasonic focusing gain G, nonlinearity β, attenuation coefficient α, a numerical reconstruction method is proposed to accurately and reliably estimate the acoustic field of a histotripter. The k-Wave toolbox was used to calculate the acoustic field produced from identical sectors on a common concave surface by gradually increasing the number of excitation elements (i.e., up to 256 that cover the whole surface). The excitation frequency is 0.8 MHz, and the initial pressure at the transducer surface is 0.4 MPa. The focusing gains, peak positive and negative pressure, positive to negative peak acoustic pressure ratio, and harmonic distributions in the focal region under different numbers of excited elements were analysed. It is found that when about a quarter of the transducer surface is excited (64 elements), the nonlinear effect becomes obvious, resulting in significant peak pressures and harmonics. Furthermore, the relationship between the positive and negative pressure peaks (p
+ and p
¬) and the number of excited elements fits a quadratic curve function quite well (R = 0.999). Altogether, the proposed method can be applied to estimate the acoustic pressure at an extremely high intensity that exceeds the range of current measurement apparatus. Acoustic pressures using a low number of excited elements are measured first and then extrapolated to the full surface coverage using the built-in regression models. In the near future, the field calculation scheme for the therapeutic focused transducers with higher irradiation power and larger dimensions, as well as experimental work, will be done to further validate our model.
The deterioration of microstructure and biochemical components in cancellous bone characterizing by the photoacoustic microscopy imaging
Authors: Xie Qiang , Li Boyi , Zhou Tianhua , Liu Xin , Han Shuai , Liu Chengcheng , Yang Chunshan , Li Ying , Li Dan , Ta Dean
Published: October 2024

Background/Objective: Osteoporosis is mainly characterized by a deterioration of microstructure and a loss of biochemical components in bone tissues. Developing an imaging technique for measuring bone tissue microstructure and the biochemical components is of great significance for the early diagnosis of osteoporosis. Photoacoustic microscopy (PAM) has the advantage of high optical resolution and the potential to diagnose osteoporosis. In this study, we investigated the feasibility of the photoacoustic microscopy (PAM) technique for bone tissue imaging, and the deterioration of microstructure and biochemical components in cancellous bone was characterized by the PAM. Statement of Contribution/Methods: We performed the optical-resolution photoacoustic microscopy (OR-PAM) for bone tissue imaging and the trabecular microstructure and hydroxyapatite (HAP) were degraded by immersion in JYBL-I solution. The PAM imaging method was developed for the measurement of the surface and subsurface of cancellous bone with a high resolution. Specifically, a 532 nm pulse laser was used to excite the PA signal from the bone. The PA signal sampling frequency was 80 MHz. A motor rotated a 15 MHz central frequency transducer to receive 1000 × 1000 × 250 points data. The envelope of the signal was obtained using the Hilbert transform for reconstruction. Then, the JYBL-I solution was used to reduce the HAP component in the bone. The PAM imaging was performed after different immersion times, (i.e., at 0, 5, and 10 mins). In the PAM measurement of the cancellous bone, the imaging area was a cylinder with an 8 mm diameter and an 8 μm/pixel resolution. Results/Discussion: The results showed that the trabecular microstructure could be imaged with a relatively high quality using the PAM technique. With the different extent of HAP degradation by immersion in JYBL-I solution, some trabecular bone disappeared corresponding with PA signals decreased significantly in amplitude. Conclusion: These results indicate that the PA technique has potential application in the characterization of bone microstructure and biochemical components with a high resolution.
Dual-mode photoacoustic and ultrasonic quantitative evaluation of cancellous bone
Authors: Zhou Tianhua , Li Boyi , Liu Xin , Ta Dean
Published: October 2024

Bone diseases, especially osteoporosis, is highly prevalent, and the chronic consequences often have debilitating effects on patients. Early diagnosis and intervention are desired, but existing bone assessment methods do not allow for regular screening as required for such early detection. We were inspired to explore the potential of photoacoustic (PA) imaging for bone assessment due to its molecular imaging capabilities and its shared advantages with ultrasonics (US). In this study, an experimental system was constructed for PA/US dual-mode imaging of cancellous bone, and the resulting images were analysed based on a new quantitative framework. The results from the quantitative analysis clearly differentiated cancellous bones with varying apparent densities, demonstrating the potential of such a method for efficient bone assessment.
3D computational modeling of multispectral photoacoustic microscopy: Simulations aiding systematic optimization and data acquisition
Authors: Gao Yang , Feng Ting , Zuo Chao , Ma Haigang
Published: October 2024

Photoacoustic microscopy (PAM), a fruitful application modality for photoacoustic imaging, is capable of directly measuring optical absorption properties in skin tissue, providing high-contrast, high-resolution medical images as well as functional and pathologic information. However, optical attenuation and unknown optical and acoustic nonuniformities limit its imaging performance in deep tissue regions. New instrumentation, image reconstruction, and artificial intelligence methods are being investigated to overcome these limitations, and a reliable PAM simulation tool is required for the effective implementation of these methods. In this paper, we propose and validate a 3D quantitative computational multispectral PAM imaging model. It provides a theoretical basis for the application of quantitative PAM in skin diagnosis and aids in the development and optimization of PAM devices, as well as the acquisition of deep learning datasets.
Photoacoustic Signal Propagation Modes in Bone Tissue: a Simulation Study
Authors: Liang Shijie , Feng Ting , Liu Chengcheng , Cheng Qian , Sun Ming
Published: October 2024

Photoacoustic (PA) imaging has great potential in brain imaging. However, the strong acoustic attenuation and reverberation caused by the skull bone layers present challenges for PA brain imaging. In this work, we developed a three-dimensional (3D) photoacoustic numerical simulation platform using the finite difference time domain (FDTD) method to study PA signal generation and propagation in the human brain. This platform can simulate not only the propagation of longitudinal waves in soft tissues but also shear and longitudinal waves in hard tissues. Using this numerical simulation platform, we extensively simulated the propagation of PA waves in skull models with varying porosities, The results demonstrate that our 3D PA simulation platform accurately captures the propagation details of PA signals in the skull, including the refraction, reflection, and mode conversion of photoacoustic waves at tissue boundaries. Furthermore, an increase in skull porosity prolongs the duration of the photoacoustic signals and leads to high attenuation of PA signals for high frequency components. We expect that this study will contribute to the understanding of the impact on acoustic propagation of photoacoustic signals in cranial bone photoacoustic imaging.
Ultrasound 3D beam-forming with distributed electrodes and frequency sub-band compounding
Authors: Nakazawah E , Syaryadhi M , Tagawa N
Published: October 2024

Array probes are commonly used in ultrasound equipment. These are transducers arranged in an array. This system requires multiple transmitter and receiver circuits, making it an expensive system; three-dimensional ultrasound imaging requires a two-dimensional array, which is even more expensive and difficult to popularize. We propose an imaging system with a single transducer and a single transmitter/receiver circuit for low-cost implementation of ultrasound imaging. The system uses a distributed electrode, which consists of multiple electrodes on a single transducer. Each electrode is connected to a single transmit/receive circuit. In this paper, we evaluate the performance of the proposed and existing array probe systems and systems by simulation.
Parallel Optimization of Message Passing Interface for 3D Sound Propagation Model BELLHOP3D
Authors: Miao Zihua , Zhou Yiqing , Luo Wenyu , Wu Shuanglin
Published: October 2024

BELLHOP3D is a widely used three-dimensional computational model for acoustic wave propagation in the ocean based on the ray method. Although its computational efficiency is relatively high, there is still significant scope for improvement. This paper presents an optimized version of BELLHOP3D that utilizes the message passing interface (MPI) to parallelize the calculation of azimuth and pitch angles. The parallel algorithm developed in this study exhibits high efficiency and produces stable and reliable results. The current work introduces both the serial and parallel algorithms of BELLHOP3D, and subsequently validates the accuracy of the parallel program via numerical simulations and also evaluates the parallel computing performance. The computation results demonstrate that parallel calculation of both azimuth and pitch angles through the use of the message transfer interface considerably enhances the parallel efficiency of BELLHOP3D.
Design of seismoelectric experiment and logging instrument in full-scale borehole models
Authors: Ma Wanli , Sun Xiangyang , Nie Zaiping , Sun Sheng , Qu Jiasong , Li Zixuan , Yang Yifei , Zhao Haiyan
Published: October 2024

In this work, a full-scale horizontally placed sandstone semi-wellbore borehole model is built for seismoelectric signals measurement experiments. A set of seismoelectric signal-measuring instruments is designed, including excitation and receiving systems. The excitation system is composed of a signal generator, power amplifier, and acoustic-electric transducer, which can generate high-power, frequency-adjustable sound waves to excite seismic signals. The receiving system consists of an antenna array, receiving circuits, and a shield, which can receive, amplify and filter seismoelectric signals at different reception distances. The SNR of the receiving system is improved by using pre-amplification and electromagnetic shielding, it has a sensitivity of 1 μV, a dynamic range of 100dB, and a noise level of 0.75 μV. The instrument has been verified and measured seismoelectric signals in semi-wellbore borehole models.
A method for calculating radiation resistance of the simply supported rectangular radiator
Authors: Li N
Published: October 2024

Radiation resistance in general is a key parameter to measure the radiation efficiency of a vibrating radiator. The traditional calculation method of self-radiation resistance of simply supported rectangular radiator needs to be calculated by numerical integration. In this study, a calculation method for the radiation resistance is proposed based on ANSYS. To verify the correctness of the method provided in this paper, several examples are provided. The calculation results show that the radiation resistance of the simply supported rectangular radiator tends to be stable after reaching its peak value, and this is consistent with the results obtained by the traditional calculation method.
Modeling of Scattered Wavefield in Complex Structures Based on Physics-informed Neural Networks
Authors: Wang Linfeng , Wang Hao , Li Jian , Liang Lin , Zeng Zhoumo , Liu Yang
Published: October 2024

The scattered wavefield of complex structures, bearing various information about the medium, serves as an effective basis for structural defect monitoring. The solution of the scattered wavefield has consistently drawn a considerable amount of attention. The commonly used approaches for solving scattered wavefields include analytical methods, numerical methods, and deep learning methods. However, it is well known that analytical methods are complex and computationally demanding, often accompanied by specific assumptions during the solving process. Numerical methods face a contradiction between computational complexity and accuracy. Deep learning methods are relatively dependent on data sets. In this work, we apply physics-informed neural networks (PINNs) to the modeling of scattered wavefield in a 2D plate. Wave equation loss and initial condition losses are represented by automatic differentiation technique, and then weighted together to form the total loss function, which constrains the iteration of the network. We demonstrate the performance of the proposed method in the modeling of scattered wavefield for both single and multiple damage models, and validate the effectiveness through a 3D printed sphere wavefield scanning experiments.
Ultrasonic guided Wave Signal Denoising Method Based on one-dimensional convolution and Full connection Model Fusion Denoising autoencoder
Authors: Yang Yingfeng , Qiu Guangwen , Lin Yizhou , Wang Chao , Wu Jing
Published: October 2024

Ultrasonic guided wave (UGW) detection is widely used in pipeline monitoring but faces challenges from weak flaw echo signals within the detection data, making weak UGW signals difficult to recognize. It is essential to denoise the UGW detection signals to identify weak echo signals. This paper proposes an improved denoising autoencoder (DAE) based on the fusion of one-dimensional convolution neural network (1DCNN) and full connection (FC). The model expands the amount of training data by adding noise in batches and uses 1DCNN to enhance the ability of extracting UGW signal features. The model was validated using Several numerical simulation signals. Numerical simulation results show that the signal-to-noise ratio (SNR) of the UGW signals can be improved from -20 dB to 8 dB; it has a strong improved SNR, and the mean square error is greatly reduced while maintaining the original phase almost unchanged. The improved DAE method has significant advantages in denoising effect, and it can effectively reduce the noise of the UGW detection signal and realize the identification of small defects of the simulation pipeline.
Development of Phased Array Ultrasonic Testing System Using Distributed Architecture
Authors: Wang Kun , Wang Juntao , Mao Jie , Zhang Yicheng , Lian Guoxuan
Published: October 2024

With more rigorous requirements for reliability and safety of structures and materials, high resolution and fast imaging have been urgent needs of Phased Array Ultrasonic Testing (PAUT). In order to improve the detection resolution and efficiency of complex structures and materials such as ultra-thick carbon steel and honeycomb plate, a PAUT system is proposed in this paper. The system uses a distributed architecture, which not only divides hardware resources, improves system performance, but also is scalable. PA, single- and multi-channel conventional UT, and TOFD (Time Of Flight Diffraction) modalities are combined, and PA modality is carried by the fully parallel non-multiplexed 128 PE (Pulse Echo) electronics with independently adjustable emitting and receiving parameters. In addition, the ultrasound analog front-end circuit is designed using discrete devices, providing more powerful analog performance than integrated chips. GTX (Gigabit Transceiver) and PCIe (Peripheral Component Interconnect Express) are applied to high-speed data transmission, providing raw ultrasound data. Characterization and verification results indicate that the system is ideal for challenging inspections in many industries.
Research on Phased Array Ultrasonic Imaging Method Based on Time Reversal Theory
Authors: Xia Yuxiu , Zhang Yifeng , Xue Feng , Jiang Jiansheng , Gao Jiaqi
Published: October 2024

With the wide application of additive manufacturing components and composite materials, it is of great significance to detect defects with non-destructive testing methods in the material manufacturing process and in service. Due to the strong attenuation and inhomogeneity characteristics, it is inefficient and poor imaging results to detect its internal defects by conventional ultrasonic testing methods. To improve the detection accuracy, this paper proposes an improved imaging algorithm with time reversal-total focusing method (TR-TFM) imaging technology to improve the defects detection in strongly attenuating materials. The experimental results show that the amplitude of the defect signal is increased by 8.30 dB, and compared with total focusing method (TFM), the diameter of the detected defect with TR-TFM imaging is increased from 1.20 mm to 1.60 mm, which is more adjacent to the accurate size. Meanwhile, with the sparse matrix based on FMC data, TR-TFM could obtain the same image quality with the approximate time of TFM imaging.
Performance enhancement of SAW based hydrogen sensor employing Pd/Ni alloy thin film
Authors: Cui Baile , Jin Jing , Ren Zixuan , Hu Anyu , Liang Yong , Wang Wen , Cheng Lina
Published: October 2024

This study focuses on determining the optimized design parameters of palladium/nickel (Pd/Ni) thin film coated surface acoustic wave (SAW) hydrogen (H2) sensors with high sensitivity and fast response by modulating the ratio and thickness of Pd/Ni thin film. The Pd/Ni thin films deposited on the wave propagation path of delay-line patterned SAW sensors had Ni content ranging from 0 to 30 at% and thickness ranging from 20 to 400 nm. A phase discrimination circuit was used to collect the signal of SAW H2 sensor. The experimental results indicated that the response sensitivity of the sensor decreased with the increase of Ni content, while the response time gradually accelerated. Besides, the stability of the sensor deteriorated with increasing thickness, and there existed a non-linear relationship between sensitivity and thickness, and the response time slowed down as the thickness increased. To analyze the SAW sensing mechanism, a theoretical simulation model of the Pd/Ni thin film coated SAW H2 sensor was established using perturbation theory, which was well-validated by experimental results. Considering the requirements of fast response, high sensitivity, and stability of the H2 sensor, the optimal thin film structure parameters were determined as Pd9Ni1 thin film with the thickness of 40 nm.
Online ultrasonic monitoring of FDM nozzle temperature based on metamaterial buffer rod
Authors: Li H C , Zhu Q , Wang C , Zhang H Y , Zhang Q Q
Published: October 2024

Fused deposition modeling (FDM) has been widely used for fabricating parts with complex geometries. However, during the printing process the nozzle temperature fluctuates which may cause nozzle blockage, inter-filament delamination, over-melting, etc. Therefore, it is of significance to develop an online and in-situ nozzle monitoring system which could overcome such drawbacks for quality assurance. In this work, a multifunctional system is designed by incorporating a traditional ultrasonic probe and a metamaterial buffer rod to online monitor the nozzle temperature and ensure a correct extrusion force and speed. A parametric simulation model is first constructed implicitly based on thermal-acoustic metamaterial structures for the buffer rod. Secondly, since the high-fidelity calculation is computationally expensive, an efficient surrogate model with kriging approach is constructed based on the dataset drawn from limited trials for rapid prediction. Thirdly, multidisciplinary optimization is performed by the NSGA-III algorithm considering the thermal insulation performance, ultrasonic attenuation and structure integrity. The rod is fabricated according to the best parameters decided. A cross-correlation algorithm is calibrated with thermocouple measurement after waveform recording at different temperatures. The online and in-situ temperature measurement can be realized during 3D printing successfully eventually. This will help to improve the printing quality with potential feedback strategies.
Laser ultrasonic characterization of grains in titanium alloy by the inversion method
Authors: Yang Zhao , Pinghua Yang , Mingzhen Wang , Yifei Cao
Published: October 2024

The polycrystalline materials have been usually described by the average grain size (AGS). This paper provides a nondestructive method for determination of the AGS in titanium alloy from an inversion of experimental ultrasonic attenuation spectrum (UAS). The detailed analyses of the inverse algorithm and sensitivity of UAS to the AGS are presented, and the sensitivity is identified as a criterion for selecting the experimental data of UAS used in inversion. An example of the inverse method and experimental measurement for UAS comparison was given for the titanium alloy specimen with the AGS of 26 μm. The relative error between the AGS determined by the inversion and scanning electron microscope (SEM) observation was found to be about 1.5 %. The provided method demonstrates the feasibility of laser ultrasonic technology used for the non-destructive evaluation of AGS in polycrystalline materials.
PA-LCR: A flexible ultrasonic characterization method
Authors: Li Fengzhong , Jin Shijie , Zhang Song , Wang Hong , Luo Zhongbing
Published: October 2024

Critically refracted longitudinal (LCR) wave is demonstrated to be prominent in the characterization sensitivity of stress or surface/sub-surface defects. According to Snell’s law, however, its excitation seriously relies on the inclined angle of wedge, i.e., the first critical angle (θ
CR). From this, it shows poor adaptability to the variations of wave velocity, especially for elastic anisotropic materials, e.g., carbon fibre reinforced plastic (CFRP) composites. An enhanced strategy based on the phased array ultrasonic, termed PA-LCR, is introduced here. It applies a wide angular distribution of energy to achieve beam steering, and then the beam is targeted at θ
CR. LCR wave is successfully excited both in isotropic steel and anisotropic laminate, and the signal-to-noise ratio (SNR) is as high as 19.0-34.6 dB. With the same delay law, the wave can be excited within a wide wave velocity range about 6000 m/s for the steel, and about 3600 m/s for the CFRP laminate, for -6 dB amplitude. The performance of the LCR technique is strengthened by the proposed PA-LCR method.
Double-side debonding detection of honeycomb sandwich structure based on air-coupled ultrasonic guided waves
Authors: Zong Zhaoyu , Liu Si , Sun Jing , Rui Xiaobo , Hu Cong , Zhang Hui
Published: October 2024

In structural health monitoring, fast, non-destructive, and non-contact testing has gradually become an important demand. This paper presents a double-side debonding detection method of honeycomb sandwich structure (HSS) based on the air-coupled guided wave. We analyze the dispersion characteristics and propagation law of guided waves in a honeycomb sandwich structure (HSS) using numerical simulation. Moreover, dispersion compensation was employed to reduce the stacking of signals. Finally, the debonding region was imaged. It realizes debonding detection on both upper and lower skins according to the amplitude changes of the direct wave signal and coda wave signal.
FDTD simulation of beamforming shape of a woolly horseshoe bat (Rhinolophus luctus)
Authors: Zhang H Y , Wu J , Li Y F , Yin S X , Guo C T , Zhuang Q
Published: October 2024

The practicality of the Finite-Difference Time-Domain (FDTD) method is employed to calculate the bat biosonar beamforming shape obtained from the three dimensional (3D) digital model of a woolly horseshoe bat (Rhinolophus luctus), as well as to acquire the nearfield sound pressure distribution of the transient sound field. The multiple sound pressure amplitude can be obtained by Fourier transform of the instantaneous sound pressure in the nearfield FDTD region. According to Kirchhoff integral, the far field normalized directivity pattern is obtained. The single point source is positioned at the center of the computational region, which is surrounded by four different number of perfectly matched layer (PML). The FDTD method is utilized to calculate the absorption of waves by the PML. The trustworthiness of the algorithm is authenticated by the outcomes. It demonstrates that FDTD can produce satisfactory outcomes for biosonar calculations on the woolly horseshoe bat.
Study on the effect of the excited area on the vibration characteristics of a thin circular plate
Authors: Han Mingliang , Zhang Guangbin , Zhang Xiaofeng
Published: October 2024

In this paper, the vibration modes and radiated directivity of a thin circular plate excited by a sandwich longitudinal vibration transducer are studied. The finite element model is set up to study the effect of the contact area between the transducer and the circular radiation plate on the vibration modes and the radiation characteristics. The first six vibration modes of the thin vibration plate are analyzed, and the results show that the vibration modes of the area-excited thin circular plate are different from those of the free vibration thin circular plate and the point-excited thin circular plate. Simulation results show that under different contact areas, the thin circular plate vibrates in different modes. With the increase of the excitation area, the frequencies of each mode of the circular plate gradually increase. Moreover, the excited area also affects the radiative directivity. With the increase of the excited area, the main lobe width of the radiative directivity becomes narrower.
EC-QCL-based photoacoustic spectroscopy for simultaneous detection of SF6 and SO2F2
Authors: Wei Qianhe , Li Bincheng , Zhao Binxing
Published: October 2024

In recent years, sulfur hexafluoride (SF6) and sulfuryl fluoride (SO2F2) have been widely used as gas insulating medium and fumigant, respectively, leading to an increase in their emissions. Additionally, SF6 will decompose into SO2F2 in gas-insulated equipment due to overheating and discharge faults. Considering the hazards of SF6 and SO2F2 to the atmosphere and human health, it is essential to develop an accurate measurement system capable of simultaneously monitoring trace amounts of SF6 and SO2F2 in the ambient air at the application site. In the present work, a photoacoustic (PA) system combining an external-cavity quantum cascade laser (EC-QCL) and a differential Helmholtz resonator has been used to realize the detection of SF6 and SO2F2. When the characteristic absorption wavenumbers of SF6 and SO2F2 were 1256.9 cm−1 and 1270.9 cm−1, respectively, the minimum detection limits of 2.3 ppm and 6.3 ppb were achieved. Based on the Allan deviation analysis, the stability of the PA system was evaluated and the detection sensitivity of both SF6 and SO2F2 was improved under the optimal integration time. An analysis of four different mixtures of SF6 and SO2F2 in N2 demonstrated the ability of the PAS apparatus to measure both gases simultaneously.
Characteristic analysis of the vortex excited using the photoacoustic transducer with a spiral light absorption surface
Authors: Yan Shuo , Tang AnQi , Hu JiaKang , Yang Zeru
Published: October 2024

It is proved that the vortex acoustic field can be excited with laser by designing the photoacoustic transducer with a spiral light absorption surface. The generated acoustic field has a spiral phase wavefront, and the pressure on the central axis along its propagation direction is zero. The orbital angular momentum that can be used for positioning and manipulation of particles is formed by the vortex. The characteristics of the generated acoustic vortex at different frequency and detection position are analyzed for 1-5 topological charge. And the influence of the geometric configurations such as the width and size of logarithmic spiral slot are also studied for the achieving the desired vortex field with focused intensity.
Scattering of elastic waves by a cluster of cylindrical inclusions: multiple scattering analysis and equivalent scatterer modeling
Authors: Ito Naoki , Biwa Shiro
Published: October 2024

The two-dimensional scattering of elastic waves by a cluster of aligned circular cylindrical elastic inclusions embedded in a circular cylindrical domain of an infinitely extended elastic medium is analysed numerically. The analysis is based on a semi-analytical method where the scattered waves are expressed as the eigenfunction expansions of the time-harmonic displacement potentials and the expansion coefficients are determined by a numerical collocation technique. The wave fields within and around the cluster are demonstrated for different spatial arrangements of inclusions in the cluster. It is also examined if the scattering characteristics of the cluster can be simulated by a single equivalent scatterer which has the effective homogenized properties of the matrix/inclusion composite. As a result, it is shown that for sufficiently small inclusion radius-wavelength ratios, the scattering characteristics of the cluster are relatively insensitive to the spatial inclusion arrangements therein, and can be reasonably simulated by those of the equivalent scatterer.
Sound Field Visualization of Specified Frequency by Combining Scanning System with Lock-in Amplifier
Authors: Yang Jiahao , Li Pan , Yin Guanjun , Nie Shibo , Tian Ye , Guo Jianzhong
Published: October 2024

Sound field visualization of specified frequency is an essential method for acoustic studies, especially in nonlinear acoustics. In this paper, we designed a sound field visualization system of specified frequency (SVSF). By combining the traditional sound field scanning system with the lock-in amplifier (LIA), the SVSF can visualize the amplitude distribution of multiple arbitrary specified frequencies with only one-time sound field scanning. Further, depending on the SVSF, we analysed the nonlinear acoustic effects around the focus of a spherical coronal ultrasonic transducer array. The excitation signal is a sinusoidal signal at 40 kHz. The results show that the acoustic waves at the focus contain fundamental frequencies at 40 kHz and harmonic frequencies at 80 kHz, 120 kHz, and 160 kHz. Comparing the amplitude distribution of those frequencies, we found that higher harmonics own smaller focus areas as well as lower amplitude, which conforms to the nonlinear acoustic theory. The system is convenient for those similar studies involving the multi-frequency amplitude field comparison.
Characterizing and communicating uncertainty: lessons from NASA’s Carbon Monitoring System
Authors: Kennedy Robert E , Serbin Shawn P , Dietze Michael C , Andersen Hans-Erik , Babcock Chad , Baker David F , Brown Molly E , Davis Kenneth J , Duncanson Laura , Feng Sha , Hudak Andrew T , Liu Junjie , Patterson Paul L , Raczka Brett , Cochrane Mark A , Sepúlveda Carlo Edil A , Vargas Rodrigo
Published: October 2024

Navigating uncertainty is a critical challenge in all fields of science, especially when translating knowledge into real-world policies or management decisions. However, the wide variance in concepts and definitions of uncertainty across scientific fields hinders effective communication. As a microcosm of diverse fields within Earth Science, NASA’s Carbon Monitoring System (CMS) provides a useful crucible in which to identify cross-cutting concepts of uncertainty. The CMS convened the Uncertainty Working Group (UWG), a group of specialists across disciplines, to evaluate and synthesize efforts to characterize uncertainty in CMS projects. This paper represents efforts by the UWG to build a heuristic framework designed to evaluate data products and communicate uncertainty to both scientific and non-scientific end users. We consider four pillars of uncertainty: origins, severity, stochasticity versus incomplete knowledge, and spatial and temporal autocorrelation. Using a common vocabulary and a generalized workflow, the framework introduces a graphical heuristic accompanied by a narrative, exemplified through contrasting case studies. Envisioned as a versatile tool, this framework provides clarity in reporting uncertainty, guiding users and tempering expectations. Beyond CMS, it stands as a simple yet powerful means to communicate uncertainty across diverse scientific communities.
A probabilistic forecast for multi-year ENSO using Bayesian convolutional neural network
Authors: Sreeraj P , Balaji B , Paul Arya , Francis P A
Published: October 2024

A robust El Niño Southern Oscillation (ENSO) prediction is essential for monitoring the global climate, regional monsoons, and weather extremes. Despite dedicated efforts spanning decades, the precise prediction of ENSO events through numerical modeling beyond a couple of seasonal lead times remains a daunting challenge. The advent of deep learning-based approaches marks a transformative era in climate and weather prediction. However, many machine learning-based studies attempting ENSO prediction are confined to singular estimates, lacking adequate quantification of uncertainty in learned parameters and overlooking the crucial need for a nuanced understanding of ENSO prediction confidence. Here, we introduce a deep learning-based Bayesian convolutional neural network model that provides robust probabilistic predictions for ENSO with a lead time of up to 9–10 months across all seasons. The Bayesian layers within the convolutional neural network maintain the capability to predict a distribution of learned parameters. Augmented with bias correction, our model reproduces the amplitude of the Niño 3.4 index with fidelity for lead up to 9–10 months. The inherent capacity for uncertainty modeling enhances the reliability of bayesian neural networks (BNNs), making them particularly valuable in operational services. This research holds substantial socio-economic implications as it enhances our forecasting capabilities and rigorously quantifies forecast uncertainties, providing valuable insights for planning and policymaking.