bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonvolatile logic inverters based on 2D CuInP2S6 ferroelectric field effect transistors
Authors: Qiang Sheng , Pan Xu , Qin Jing-Kai , Yue Lin-Qing , Li Dong , Zhu Cheng-Yi , Hu Zi-Han , Zhen Liang , Xu Cheng-Yan
Published: October 2024

With the capability of in-memory computing, integrated nonvolatile logic devices can mitigate the back-and-forth movement of data between storage and logic units, thus effectively enhancing computational speed and reducing power consumption. In this work, two-dimensional (2D) CuInP2S6, which reveals robust polarization within a few nanometer thicknesses, was utilized as gate dielectric for ferroelectric field effect transistor (FeFET). Device with a ReS2 channel demonstrated a high on/off ratio of current of 105, accompanied by a substantial hysteresis window of 2.8 V. Additionally, ReS2 FETs, gated with an h-BN layer, exhibited a switch ratio of 108 and minimal hysteresis of 61.6 mV at room temperature, attributed to the atomically flat heterointerface with negligible traps. Leveraging the performance of these devices enabled the creation of a nonvolatile logic inverter, wherein the ReS2/h-BN FET acts as the load transistor, and ReS2/h-BN/CIPS FeFET serves as the driving unit. This configuration stably operates with low power consumption of 0.45 μW and outstanding retention exceeding 1000 s. This work presents a viable device architecture for designing nonvolatile logic circuits applicable in in-memory computing.
High Q transparency, strong third harmonic generation, and giant nonlinear chirality driven by toroidal dipole-quasi-BIC
Authors: Cheng Yang , Cai Shijie , Li Junjie , Gong Hanyang , Liu Zhengqi , Chen Jing , Fu Guolan , Liu Xiaoshan , Pan Pingping , Liu Guiqiang
Published: October 2024

Electromagnetically induced transparency (EIT), nonlinearity, and optical chirality hold significant applications in many areas such as optical switches, slow-light devices, chiral harmonic conversion, and optical storage. In this work, we theoretically propose an asymmetric all-dielectric metasurface supporting toroidal dipole-quasi-bound states in the continuum (TD-q-BICs). High quality (Q) EIT, strong third harmonic generation (THG), and giant nonlinear chirality are achieved via the extremely enhanced electric field energy localized in the Si plate by the TD-q-BIC. A huge transition from high Q EIT with transmission of ∼0.99 to strong chirality with circular dichroism (CD) of ∼0.9 is realized by tuning the angle and polarization state of incident light. Strong THG with efficiency of 4.5 × 10−3 under linear polarization light is due to the highly localized electric field supported by the TD-q-BIC and perfect nonlinear CD chirality with theoretically value of ∼1 originates from the large discrepancy in electric field distributions under different circularly polarized light. Our work provides an innovative paradigm to construct TD-q-BICs-governed EIT analogs, THG, and nonlinear chirality for the development of multifunction nanophotonic meta-devices.
COVID-19 vaccine effectiveness monitoring in Australia
Authors: Liu Bette
Published: October 2024

Vaccine effectiveness is a measure of vaccine performance in the population usually estimated after the vaccine has been registered and is being used. With continuing evolution of SARS-CoV-2 and new variant-specific vaccines, as well as changes in uptake of vaccination and incidence of infections in the population, continued assessment of COVID-19 vaccine effectiveness is important to inform programmatic and policy decisions. In Australia, COVID-19 vaccine effectiveness against mortality has been assessed regularly using whole of population health data. These analyses have shown how vaccine boosting with the most up to date variant vaccines has been highly effective in reducing COVID-19 deaths in older adults. However, waning of protection continues to be observed supporting the need for regular boosters in older Australian adults and the need to continue to monitor the effectiveness of the COVID-19 vaccine program.
Abundance, size and biomass of long-spined sea urchins (Centrostephanus rodgersii) and red sea urchins (Heliocidaris tuberculata) in New South Wales, Australia
Authors: Blount C. , Worthington D. G. , Byrne M. , Chick R. C. , Organ K. , Knott N. , Andrew N. L.
Published: October 2024

Context Detailed demographic information for the commercially harvested long-spined sea urchins (Centrostephanus rodgersii) and red sea urchins (Heliocidaris tuberculata) on nearshore reefs of New South Wales is unavailable. Aims This is the first detailed study of abundances and sizes of these sea urchin species on shallow reefs of New South Wales where the fishery operates. Methods Divers counted sea urchins and measured their sizes in transects in the nearshore mosaic habitat and in extensive barrens habitat at 51 sites along ~800 km of coast. Key results Centrostephanus was found at most sites in both habitats, whereas Heliocidaris was found at lower densities and at fewer sites. Heliocidaris was rare in the far south and in barrens habitat. Centrostephanus was, on average, smaller in barrens habitat than in the nearshore mosaic habitat, and size structures shifted towards smaller individuals from north to south. Conclusions Centrostephanus occurred at higher densities than did Heliocidaris and had a broader distribution along the coast and across the nearshore reefs where the fishery operates. Implications This study provides a historical baseline for these commercially and ecologically important species. The small biomass of Heliocidaris (~3% that of Centrostephanus) and its restricted distribution suggest it is vulnerable to overfishing.
The analysis of orientational metaphor of ‘Zhōng’ (中) in Chinese traditional classic The Doctrine of the Mean
Authors: Shan Weijia , Lin Zhengjun
Published: October 2024

This paper studies the orientational metaphor of zhōng (中, ‘middle’) and its cultural values behind this metaphor in
Chinese Traditional Classic The Doctrine of Mean. It is found that there are three metaphorical meanings for the
orientational metaphor of zhōng (中,
‘middle’), including “an emotion of calm.”; “a moderate degree” and “an ethical standard”. The ethical standard of
zhōng is the judge criteria for the Chinese traditional role schemas jūnzǐ (君子, ‘a person of noble character’) and xiǎorén
(小人,‘a person of petty character’). In addition,
the cultural values of Chinese society revealed by the ethical standard of zhōng (中, ‘middle’) are concluded systematically from the levels of
individual, family and state.
Improved breakdown voltage and dynamic Ron characteristics in normally-off GaN-based HEMTs featuring fully-recessed and bilayer-dielectric gate structure
Authors: Sun Nan , Dai Jianxun , Huang Huolin , Zhang Jiayu , Lei Yun , Wang Ronghua , Tao Pengcheng , Liu Yanhong , Song Shukuan , Ren Yongshuo , Cheng Wanxi , Liang Huinan
Published: October 2024

The degradation of dynamic on-resistance (R
on) is a major challenge in GaN-based high electron mobility transistors, which seriously affects their performance and reliability. The degradation area of dynamic R
on mainly comes from two aspects. One is the region below the gate that also affects the threshold voltage (V
th) of the devices. The other one is the interface region of the gate to drain access. The optimal device exhibits a V
th of 0.97 V, a small V
th hysteresis of only 20 mV, a high current density of 723 mA mm−1, and a breakdown voltage of 810 V which can be further boosted when additional field plate design is employed. It is found that when high voltage drain stress is applied, a positive V
th shift is induced, leading to a decrease in the effective gate driving voltage, and thus the dynamic R
on of the devices is increased. Of particular concern are the effects of dielectric layer and/or interface of the access region on the dynamic R
on degradation, which can be alleviated by removing the dielectric layer from the access region.
An FBG-based method for load measurement of a cylindrical rolling element bearing
Authors: Wang Xin , Liang Xihui , Wu Nan
Published: October 2024

Contact forces between raceways and rolling elements of a bearing stand as crucial operational aspects defining the bearing’s performance. While monitoring bearing load through load cells or strain gauges on the shaft or housing is feasible, it may not precisely reflect the distributed load transmitted by the rollers directly to the raceways. This paper introduces a method to calculate these contact forces, relying on a linear assumption correlating the loads to the measured strains on the outer race of a bearing. In our research, we conducted both static and dynamic tests on cylindrical roller bearings through simulations and experiments. We designed an experimental test rig to conduct both static and dynamic experiments and utilized FBG optical fiber sensors for contact force measurement in bearings due to their multiple advantages, including high sensitivity, resistance to corrosion and magnetic interference, and ease of installation on the bearing outer race due to their shape and size. Our findings indicate a consistent linear relationship between contact forces and strains measured on the bearing’s outer race. Furthermore, we calculated the linear coefficient K values from three test groups: static tests under simulation study, static tests under experimental study, and dynamic tests under experimental study. The K values obtained from static tests (simulation and experimental studies) and dynamic tests (experimental study) align consistently. Following this, we calculated contact forces in both static and dynamic experiments by multiplying the measured strains with K. Our calculations resulted in an error percentage of less than 2% for static tests and below 5% for dynamic tests, highlighting the accuracy of our approach in determining these contact forces.
Improvement of N-type carbon nanotube field effect transistor performance using the combination of yttrium diffusion layer in HfO2 dielectrics and metal contacts
Authors: Hou Zhenfei , Niu Gang , Li Jie , Wu Shengli
Published: October 2024

In this paper, we obtained n-type top-gate carbon nanotube (CNT) thin film field effect transistors (FET) with source/drain extensions structure through dielectrics optimization strategy, combining the yttrium layer with HfO2 dielectric argon annealing process, and metal contacts. The mechanism for enhanced n-type conduction was explained as being due to the vertical diffusion of yttrium to the HfO2 dielectric during argon annealing. This diffusion causes a bending of the energy band, which results in more positive fixed charges, and a reduction in the electron injection barrier between the low work function source/drain Cr electrode and CNT thin film. The optimized technology has great prospects for the low cost, large scale and high performance n-type CNT thin film FET to be used in integrated electronic devices.
Observation of nonthermal electrons further acceleration and long-lasting associated with magnetic reconnection and turbulence bursting in tokamak plasma
Authors: Mai Chaowei , Xu Liqing , Lin Shiyao , Hu Liqun , Chen Yiping , Zhou Tianfu , Feng Xi , Liu Adi , Luo Zhengping , Chao Yan , Quan Haipeng , Zhang Yubo
Published: October 2024

Vital to magnetized plasma performance, the acceleration of nonthermal electrons significantly influences the current drive of radio frequency (RF) waves in plasma. In Experimental Advanced Superconducting Tokamak (EAST), we observed nonthermal electrons initially <215 keV in energy, being locally accelerated to 600 keV within 100 milliseconds, which corresponds to the total growth time of the magnetic island. Surprisingly, these fast electrons (FEs) lasted for 1.4 s, several times longer than the estimated relaxation time of 0.26 s, and exceeded 1/10 of the discharge length. Turbulence generation at island’s X point is attributed to the unexpected confinement and repopulation of FEs. This phenomenon may have positive implications for the steady-state long pulse H mode operation in EAST, especially regarding non-inductive current sustainment. For future RF electron heating-dominant devices, the mechanisms elucidated in this study have immediate implications for optimizing RF current drive efficiency.
Full-waveform ultrasonic imaging for bone
Authors: Xu Lexiu , Li Yifang , Shi Qinzhen , Zhang Yunyun , Ta Dean
Published: October 2024

This paper suggests a full-waveform ultrasonic imaging strategy for bone. A novel forward wavefield propagation is performed in the frequency-domain. To improve the efficiency of full-waveform inversion bone imaging, all relative computations are also conducted in the frequency-domain. Additionally, a conjugate gradient algorithm is employed in the inversion procedure to accelerate the reconstruction of the bone acoustic velocity. Eventually, numerical experiments on different bone models are carried out to demonstrate the effectiveness of explored imaging strategy.
Sound speed imaging of cortical bone and soft tissue based on frequency-domain ultrasound waveform tomography
Authors: Zhou Chenchen , Xu Kailiang
Published: October 2024

As one of the ultrasound computed tomography (UCT) algorithms, full-waveform inversion (FWI) can recover clear and detailed internal structures of bones by iteratively minimizing the misfit between observed and numerical data. However, time domain full-waveform inversion (TDFWI) often lacks sufficient low-frequency information, and the computation of full-time data imposes a significant computational burden. Besides, there are few studies on whole-medium reconstruction that jointly invert the bone and surrounding soft tissues. In this study, an FWI-based frequency-domain UCT (FD-UCT) is utilized for simultaneously imaging the sound speed of bones and soft tissues, which facilitates the inversion efficiency while ensuring the existence of low-frequency information. Simulated studies show that the FD-UCT can both reconstruct bones with large acoustic impedance and distinguish subtle impedance differences within soft tissues to reveal lesions.
In vitro experimental study on interventional ultrasound-mediated microbubble cavitation lithotripsy
Authors: Zhou Honglei , Wang Muyao , Chen Junjian , Zheng Xianhua , Chen Yiju , Wang Zhiyong
Published: October 2024

Ultrasound-mediated microbubble cavitation lithotripsy as a new minimally invasive approach has received great attention for the treatment of urinary stones. However, the attenuation of ultrasonic waves in human tissues and stone displacement during lithotripsy are two key issues limiting the development of this technology. In this paper, a method of interventional ultrasound-mediated microbubble cavitation lithotripsy is proposed, which can realize the in-situ delivery of ultrasonic waves and microbubbles. A piezoelectric ultrasound transducer with the center frequency of 461 kHz and output peak to peak acoustic pressures of 3.2 MPa is fabricated, and microbubbles with the concentration of 1.33×109/ml are synthesized. An extracorporeal experiment platform is built and in vitro tests of ultrasound mediated microbubble cavitation lithotripsy are conducted by using microbubbles with different concentrations and water. The results show that the proposed interventional ultrasound-mediated microbubble cavitation lithotripsy is an efficient method for the fragmentation of ureteral stones. The maximum mass reduction of the stone is 9.4 mg within 30 minutes of treatment under the combined action of ultrasound with the peak-negative pressure of 1.6 MPa and center frequency of 461 kHz and microbubbles with the concentration of 3.325×107/ml. The research results will provide a technical basis for further optimization of subsequent tentative schemes, in vivo experiments with animals and future clinical applications.
Wave mode variation of multi-wavelength photoacoustic guided waves in cortical bone
Authors: Chen Honglei , Li Ying , Tran Tho Nht , Sun Shuxin , Xu Kailiang
Published: October 2024

Photoacoustic guided waves (PAGWs), excited based on the optical-thermo-mechanical coupling mechanism, have the potential to non-invasion assess the optical properties which associates tissue composition of bones. This study investigates the wave mode variation of PAGWs with the optical transmissivity in a 2mm-thick cortical bone plate. Multi-wavelength PAGWs were generated by lasers of different wavelength with a tunable pulsed laser system; Two piezoelectric transducers with the centre frequency of 500 kHz, symmetrically sticked on the bone surfaces, were used to acquire the signals. The symmetric (S) mode and anti-symmetric (A) mode were extracted by adding and subtracting the signals received by different transducers, respectively. The relative amplitude ratio of A mode and S mode was found to have an inverse relationship with the optical transmissivity of the bone. For the 750 nm laser with high transmissivity, the waves are mainly S mode; the relative amplitude of A mode wave increases with the laser wavelength. The amplitude ratio of A- and S- modes is in exponential attenuation with the transmissivity. The research results suggest that the wave mode variation in signal amplitude is suitable for evaluating the optical properties of bones, which is benefit for the development of quantitative ultrasound assessment of long cortical bone.
Improved subarray coherence factor beamformer for ultrasound plane-wave imaging
Authors: Guan Huchang , Jiang Chen , Xu Kailiang , Ta Dean
Published: October 2024

Coherent plane-wave compounding (CPWC) has gained significant traction in medical ultrasound imaging. The coherence factor (CF) weighting algorithm, a classical adaptive beamforming strategy, aims to enhance the CPWC imaging lateral resolution, but it also noticeably compromises the speckle patterns, particularly.at a low signal-to-noise ratio (SNR). Delay multiply and sum (DMAS) has been proposed to reduce side lobes. However, the reconstructed image quality with DMAS is limited in terms of resolution and speckle level. In the present study, an improved subarray coherence factor (ISCF) algorithm is introduced by combining CF with DMAS strategies, aiming to improve the contrast and resolution while preserving the speckle level. The performance of the proposed algorithm is evaluated using simulation and phantom datasets. Results indicate that the resolution and the contrast of ISCF can be improved by 41.6% and 79.4%, respectively; compared with delay and sum (DAS) algorithm. Additionally, the resolution and the speckle level of ISCF can be improved by 10.6% and 35.7% compared with CF algorithm, respectively. The proposed ISCF algorithm outperforms CF in terms of resolution, contrast, and speckle preservation.
Hadamard Coded Multiplane Wave based Ultrafast Doppler for Rat Brain Imaging
Authors: Yan Shaoyuan , Fu Yapeng , Xu Kailiang
Published: October 2024

This study explores the application of Hadamard multiplane-wave coding in ultrafast power and color Doppler imaging for enhanced visualization of rat brain vasculature. By implementing an 8-order Hadamard matrix, an approximate 10 dB improvement in signal-to-noise ratio was significantly achieved, particularly in deep brain regions and the hippocampus. The enhanced imaging technique, compared to classical plane wave coherent compounding, demonstrates its potential for applications requiring deep penetration and high sensitivity to small blood flow without compromising the ultrafast frame rate.
A Study of Mechanical Scanning High-frequency Ultrasonic Color Flow Imaging
Authors: Heng Jiaming , Wang Qing , Li Chengxi , Chu Tianxiang , Gao Feng , Jian Xiaohua
Published: October 2024

High-frequency Ultrasonic imaging can promote high-resolution images and detailed diagnostic information, which has great clinical application prospects. However, due to the difficulty and high cost of high-frequency multi-channel ultrasound systems and multi-array element transducers, it is not conducive to popularization. Mechanical scanning high-frequency ultrasound imaging system is an alternative and low-cost method. However, current mechanical scanning systems cannot perform ultrasound flow imaging, and hemodynamic information is clinically important. Therefore, an improved high-frequency, miniaturized mechanical scanning system for color flow imaging was designed and developed. The system uses a crank linkage structure to drive a miniature transducer with a center frequency of 12 MHz for reciprocating scanning imaging within a range of 15 mm. By optimizing the clutter filter and dynamic domain flow imaging process, two methods are realized: real-time rapid ultrasound imaging and highly sensitive ultrasound flow imaging. The two optimized methods used power Doppler and color flow Doppler for flow phantom imaging, and the final measured blood flow error was less than 5%, which indicates that the mechanical scanning high-frequency ultrasonic color flow imaging system has a good application prospect.
Ultrasonic visualization of destruction processes in nonwoven polymeric matrix for regenerative medicine
Authors: Morokov E , Tubaeva P , Zykova A
Published: October 2024

The paper depicts the tensile behaviour of a random oriented nonwoven polymer matrix based on poly-3-hydroxybutyrate. The process of alignment, orientation and stretching of polymer fibers in a water filled condition mimicked presence in a living organism was revealed using acoustic microscopy. To describe the micromechanics of electrospun mats the mechanism of ultrasound contrast of small-sized single cylindrical scatterer was described.
An integrated dual-frequency IVUS system with interleaved sampling and parallel signal processing based on FPGA
Authors: Xiao Xin , Can Yu , Wang Zhuochen
Published: October 2024

Due to the lack of high voltage and low frequency pulse transmission channels, commercial high frequency IVUS imaging system cannot meet the hardware requirements of ultrasound angiography. Therefore, it is of great research significance to develop a dual-frequency IVUS rotary imaging system with high integration, high sampling rate and sampling accuracy. In this work, an integrated dual-frequency IVUS system with interleaved sampling and parallel signal processing based on FPGA was developed. The central frequency of low-frequency channel is up to 10MHz, and the peak voltage range is 80-200V. The central frequency of the high-frequency channel is up to 60MHz, and the voltage peak-to-peak range is 40-80V. The acquisition channel is 500MHz and 12bit, which is realized by interleaved sampling of two ADC. The motor controlled ultrasonic transducer acquires 400-800 lines per turn, and eventually form a 360-degree IVUS hybrid imaging successfully.
The Feasibility Study of Bone Fracture Assessment Based on Photoacoustic Time-of-Flight Method
Authors: Fang Yousong , Feng Ting , Ni Chenyin , Liu Chengcheng , Cheng Qian
Published: October 2024

Photoacoustic imaging (PAI) technology combines the advantages of acoustic resolution and optical contrast imaging within deep tissue. The commonly clinically used bone fracture detection and evaluation method is X-ray based imaging techniques. In order to study the feasibility of human radius fractures detection in non-radiation and non-invasive way, this study combined the time-of-flight (TOF) method commonly used in industrial nondestructive testing with photoacoustic technology for the detection and location of bone fractures. Firstly, the bone fracture information carried by PA signal was studied by simulating the bone models with different locations of bone fractures. The finite difference time domain (FDTD) method was used to simulate the propagation process of photoacoustic signal in bone tissue. Secondly, the PATOF diagrams formed by PA signals at different locations is obtained by using laser fixed and ultrasonic detector motion detection method. Finally, the PATOF diagrams are further analyzed and quantified. The results show that the photoacoustic bone detection method based on TOF method can effectively locate the fracture location. This study confirms the feasibility of combining PAI technique with TOF method to detect bone fractures, which indicates that PAI technique has great application prospect in bone detection field.
Multi-focus Image Fusion via Blind Deconvolution and Registration based on Photoacoustic Microscopy
Authors: Li Hang , Ma Haigang , Zuo Chao , Feng Ting
Published: October 2024

Optical resolution photoacoustic microscopy (OR-PAM), which can present the microstructure of biological tissues is useful in the disease diagnosis. However, conventional OR-PAM can only obtain images with high resolution in a narrow range of depths around the focal plane. In this study, we proposed a multi-focus photoacoustic image fusion method based on the blind deconvolution. This method is divided into two steps. First, we used the method of blind deconvolution to obtain an approximate point spread function (PSF) for each photoacoustic images obtained from multiple layers, and then got the corresponding deblurred photoacoustic images. Second, we used the method of multi-focus images registration and fusion to accurately align the multi-focus photoacoustic images and effectively fuse the features of different images. Finally, the proposed method was applied to process the photoacoustic images obtained from photoacoustic imaging experiments on ants with irregular morphology using fast controllable confocal focus PAM (FC-PAM). The results show that our method improves the quality of photoacoustic images, and can quickly obtain multi-focus fused photoacoustic images with high resolution. It indicates that the proposed multi-focus photoacoustic image fusion method based on FC-PAM has great potential in fast imaging of living biological tissues at multiple imaging depths.
Feasibility of Prostatitis Evaluation Based on Photoacoustic Microscopy
Authors: Wang Chong , Li Ying , Li Boyi , Zhu Yunkai , Chen Yaqing
Published: October 2024

This study aims to investigate the feasibility of using photoacoustic microscopy for the diagnosis of prostatitis. We induced inflammation in rats to establish a model of prostatitis using Freund’s Complete Adjuvant (FCA). Prostate tissues from both the model and control groups were extracted and processed into histological sections. We explored the photoacoustic microscopy imaging results of unstained sections, consistent with the histological detection results using HE staining. Inflammation was found to enhance the photoacoustic signals. Subsequently, we conducted photoacoustic microscopy imaging on all samples, and the detection results were nearly consistent with the diagnoses made by medical professionals. Finally, we quantified the collected photoacoustic signals to classify the severity of prostatitis.
Super-resolution based on frequency dependence of echo phase rotation in 3D ultrasound imaging by spatially encoded transmit/receive
Authors: Syaryadhi M , Zheng J , Tagawa N , Yang M
Published: October 2024

Currently, we are investigating the ultrasound imaging of a single transmitter/receiver system for a puncture microscopy application. The proposed model, consisting of an encoding mask layer with irregular thickness attached to the surface of the transducer, was carried out by a finite element method simulator. To increase the number of measurements, the device was rotated for several rotations. The image for each rotation was constructed separately by numerically solving the linear equation of the image model. In this paper, we introduce a super resolution method (SCM) based on an eigenvalue analysis in order to improve the poor resolution. It was assigned as weights and multiplied by the current image. The simple averaging and coherence factor were applied to compound over a number of rotations to obtain the final image. The results show that the image has a better image resolution and also suppresses the unwanted signals as well.
Estimation method of the Homodyned K-distribution based on the Improved Shuffled Frog Leaping Algorithm for ultrasound tissue characterization
Authors: Wu Keyan , Zeng Xiuhua , Zhao ChuanLiang , Xu Xinggui , Jiang Rong , Wang Kun
Published: October 2024

Aiming at promoting the accuracy of the integral value of the probability distribution function (PDF) of Homodyned K-distribution (HK), a new maximum likelihood estimation method for HK distribution parameters is proposed by using the improved shuffled frog leaping algorithm (ADM-SFLA) and Newton-Raphson iterative algorithm (NR). To improve the accuracy of the global search of the traditional SFLA, two variation factors of Gauss and Cauchy are first used to find the global optimal solution in a convergence state. Secondly, to obtain the integral node with optimal segmentation, the ADM-SFLA is used to perform the non-equidistant adaptive segmentation of the integral interval. Then, the PDF of the HK distribution is calculated between each numerical integration cell based on Simpson integral formula. Subsequently, the integral value of the PDF for HK distribution is obtained by summing the integration values from each numerical integration cell. Finally, the optimal estimation of HK distribution parameters is obtained based on NR algorithm. The performance of the proposed method is evaluated and compared through simulated data as well as the envelope signals obtained from the ultrasonic simulation model with different scattering components. The results show that the ADM-SFLA based method can improve the estimation accuracy of HK distribution parameters effectively.
Application of distributed acoustic sensing technology in deep shale gas exploration
Authors: Zhou Anfu , Cheng Xiaoyan , Xie Wei , Qiu Xunxi , Chen Yuanzhong , Wang Yu , Li Qifeng , Zhao Jilong , Tan Fengyu
Published: October 2024

In the past decade, the exploration and development of deep shale gas usually adopted geophone acquisition for vertical seismic profile (VSP) to improve the accuracy and resolution of seismic data. However, it’s very hard to use the 10-20m level spacing geophones to meet the resolution of 2-5m thin reservoir. Distributed acoustic sensing (DAS) technology has been widely used in the oil and gas field due to its advantages of high density and high efficiency acquisition, especially in vertical seismic profile and dynamic monitoring. We have acquired zero offset VSP by DAS and geophone for the first time in deep shale gas wells at home, and successfully overcome the coupling problem in open-hole sections. Vibrators are used as sources for multiple stacking to improve the signal-to-noise ratio (SNR) of DAS VSP. The records show DAS has significant advantages in frequency, SNR and wavelet consistency. After data processing, the layer velocity characteristics of DAS VSP are more obvious. DAS VSP corridor stack has a high degree of consistency with the synthetic record and seismic profile, and the resolution of the reservoir was higher than geophone.
Shear wave measurement in slow formations for eccentric monopole acoustic logging while drilling
Authors: Ji Y J , Wang H
Published: October 2024

The use of a logging-while-drilling (LWD) monopole tool to directly measure shear (S) wave velocity in slow formations has been proven feasible under certain conditions. However, S-wave signals received in the borehole are fairly weak, which limits the application range of this measurement method. To find ways to enhance shear waves, we first explore factors sensitive to the S-wave excitation. Simulation results indicate that four parameters including the receiver-source distance, the radial distance from receiver to borehole wall, the formation S-wave velocity and source frequency, primarily influence the S-wave excitation. Shear waves can be enhanced by judiciously optimizing these parameters during tool design. We also investigate borehole wavefields with an eccentric LWD tool in both commonly slow and ultra-slow formations. Results reveal that tool eccentricity can amplify shear waves and improve its measurement accuracy, provided that waveforms received in the direction of tool movement are used. We successfully extracted the S-wave velocity of an ultra-slow formation under conditions of large eccentricity, while similar actions originally failed with a centralized instrument.
Reflection and Transmission of Plane Waves at the Interface of Fluid and Porous Media with Seismoelectric Effect
Authors: Gao Wenyang , Zhang Yan , Zhao Zhiming , Cui Zhiwen
Published: October 2024

The relationship between energy flux reflection and transmission coefficient of seismoelectric plane waves in plane layered media and incident angle and frequency is studied. Pride equations is adopted to describe the coupling phenomenon between elastic waves and electromagnetic fields in subsurface fluid-saturated porous media. The Helmholtz decomposition is used to derive the energy flux expression for seismoelectric plane waves propagating in fluid-saturated porous media. It shows that the impermeable interface conditions have a great influence on the reflection and transmission coefficient of seismoelectirc waves. The transmission coefficient of slow longitudinal waves under impermeable interface is much smaller than that of permeable interface conditions Reflection coefficient of longitudinal wave, transmission coefficients of the fast longitudinal waves and transverse waves are all larger under impermeable interface conditions than that of permeable cases. And the reflection coefficient of electromagnetic wave under impermeable interface conditions is almost one order of magnitude smaller than that permeable case.
Coupled vibration characteristics and optimization design of the cylindrical-exponential ultrasonic concentrator
Authors: Xu Jie , Wang Guozhang , Lin Jiyan
Published: October 2024

In this study, the vibrations of cylindrical-exponential ultrasonic concentrators are investigated, with the objective of improving energy transfer efficiency. Traditional analyses, often one-dimensional, have been found to inadequately consider the effects of height on vibration behaviour. To address this gap, the equivalent elasticity method is employed to provide a more comprehensive understanding of vibrational phenomena. The coupled vibration of the concentrator is regarded as an interaction between a longitudinal vibration and a plane radial vibration. A mechanical coupling coefficient is introduced, establishing a link between these vibrational modes. Equivalent circuits for radial and longitudinal vibrations are derived, and input impedances are presented as functions of resonance frequency and mechanical coupling coefficient. These analyses enable an exploration of the impact of geometric dimensions on the vibrational characteristics. To validate our theoretical model, the finite element method is used to simulate the coupled vibration and the results confirm the efficacy of the approach.
Research on Frequency of Radial Vibration of Elastic Thin Spherical Shell
Authors: Haidao Zhang , Long Xu , Fengming Li
Published: October 2024

The ultrasonic frequency radial vibration of an elastic thin spherical shell composed of isotropic materials is studied, the frequency equation of its vibration is deduced, and the equivalent circuit is obtained. The finite element software COMSOL is used to verify the obtained analytical theory, and the calculated results are basically consistent with the theoretical calculated values. The relevant conclusions provide references for the application of spherical shell structure in related fields.
Open-slit circular tube piezoelectric ultrasonic transducer with longitudinal bending mode conversion
Authors: Li Fengming , Liu Shiqing , Xu Long , Zhang Haidao , Zeng Xiaomei , Chen Zhaojiang
Published: October 2024

A new type of longitudinal bending mode conversion ultrasonic transducer is designed by compounding a sandwich type piezoelectric ultrasonic transducer, amplitude transformer and Open-slit circular tube radiator. The radiator is made of a circular tube cut into a number of curved plates along the axis, and the two ends are thin disc end caps. The electromechanical equivalent circuit model of the transducer is established and its frequency equation is derived. The vibration performance of the transducer is studied by using the equivalent circuit method and the finite element method. The results show that: the new structure design and the longitudinal vibration sandwich piezoelectric ultrasonic transducer can effectively stimulate the two ends of the slit circular tube radiator to produce first-order bending vibration, and the curved plate to produce high-order bending vibration, so as to achieve high efficiency, uniform and all-round ultrasonic radiation. The research results are expected to be applied in ultrasonic treatment of large volume liquid such as ultrasonic wastewater treatment, ultrasonic algae removal and ultrasonic chemical reaction.
Application of optical fiber distributed acoustic sensing system in ultrasonic detection
Authors: Xiao Yanbo , Ran Zengling , Yi Jicai , Chen Qiaoling , Chen Ziqiang , Zhu Qingqiang , Cui Jianxin , Rao Yunjiang , Wang Ximing , An Shujie , Chen Yuanzhong , Wu Junjun
Published: October 2024

The optical fiber distributed acoustic sensing system can continuously detect acoustic signals along the optical fiber, with the characteristics of wide response frequency band, large capacity, anti-electromagnetic interference and so on. An ultra-sensitive distributed optical fiber acoustic sensing system (uDAS) was produced with a high response frequency up to 100 kHz and thousands of sensing points. The arrayed ultrasonic detection can be realized by the distributed characteristics of the system. For verifying its ultrasonic detection ability, it is applied to ultrasonic nondestructive testing of structural defects. 20 optical fiber ultrasonic detection units were constructed. Each one is a fiber ring with a diameter of about 1.5 cm and a length of 2 meters. Two cubic cement structures with a side length of 30 cm were manufactured for experiment, one of which had an artificial internal defect. The optical fiber array was attached to the surface of the cement structure, and the ultrasonic signal with a frequency of 40 kHz was excited at a single point on the opposite side. The ultrasonic propagation speed changes on account of the defects such as holes and loose texture in the propagation path. The defects in the structure are identified and located by analyzing the difference of arrival time of waves. It is expected that such sensing system could found important applications in structure defect detection.
A novel theoretical analysis method for the longitudinal cascaded piezoelectric transducer based on equivalent circuit
Authors: Li Guo , Lei Ming , Xu Huan , Han Shuyang , Zeng Yan , Li Yujiao
Published: October 2024

High power ultrasonic transducers are widely used in the fields of ultrasonic cleaning, ultrasonic welding and therapeutic ultrasound. To further improve the ultrasonic intensity and power of piezoelectric transducers for power ultrasound applications, the cascaded piezoelectric transducer have received tons of attention. The electromechanical equivalent circuit, as a classical transducer analysis method, translates the structural and mechanical parameters into the corresponding circuit parameters and helps us to better understand and analyze the performance characteristics of the transducer, which is of great significance for the design and optimization of the transducer. In this paper, a new theoretical analysis method based on the equivalent circuit is proposed for cascaded piezoelectric transducer. In this method, the equivalent circuit of each component of the longitudinal piezoelectric transducer is cascaded, and equivalent circuit is analyzed using the Kirchhoff’s law to obtain the frequency resonance equation of the piezoelectric transducer. This analysis method avoids the complex equivalent transformation of the equivalent circuit including multiple excitation sources and also obtains the vibration velocity of the piezoelectric transducer radiation surfaces, more information on the vibration characteristics of the transducer was gained from the theoretical aspect. Finally, the theoretical analysis results are compared with the finite element simulation analysis and the traditional analysis results for verification.
The Effect of the Movement of a Passive Reflector on the Atomization of a Levitating Drop
Authors: Meneses-Díaz J. , Cancino-Jaque E. , Carrión-Acuña M. , Vargas-Hernández Y. , Gaete-Garretón L.
Published: October 2024

This study investigates the instability of distilled water drops under acoustic levitation induced by the movement of a reflector toward the transducer. The experimental setup consisted of a passive concave reflector and a Langevin transducer in a uniaxial-resonance configuration. The experiment consists of achieving a stable levitation of the droplet and then moving the reflector constantly toward the transducer, shortening the distance h between them (reflector-transducer). All experiments were recorded using a high-speed camera to analyze the drop’s behavior. The results revealed three distinct instabilities: radial atomization occurred when the drop volume (VD
) was ≤ 3.74 μl, beyond which central atomization was observed. A third instability is observed when a low reflector velocity (Vr
< 0.67 mm/s) is used, where the droplet exhibited modes of oscillation with pulsed central atomization.
A 2D Ultrasonic Phased Array Optimization Framework Enabled by Reconfigurable Laser Induced Phased Arrays
Authors: Lukacs Peter , Davis Geo , Pieris Don , Stratoudaki Theodosia
Published: October 2024

Three-dimensional (3D) ultrasonic imaging enables the viewing of internal features in a more accurate way than cross-sectional imaging. 3D imaging requires two-dimensional (2D) ultrasonic phased arrays to resolve all three spatial dimensions through beamforming along azimuthal and elevation angles. 2D phased arrays pose a manufacturing and control challenge due to the requirement of large number of elements to satisfy the Nyquist sampling limit. This problem can be alleviated through the use of sparse ultrasonic array designs. The optimization process is critical, as this dictates the efficiency of suppression of grating lobes. The aim of this work is to establish a framework for design of optimized sparse 2D phased arrays. This is enabled by exploiting the reconfigurability of Laser Induced Phased Arrays (LIPAs). LIPAs are synthetic arrays produced by scanning one laser for ultrasound generation and another for ultrasound detection, independently of each other. The reconfigurability and decoupled ultrasonic generation and detection of this systems enables easy and fast implementation of any arbitrary array layout. The framework consists of an analytical model for parametric evaluation of designs. The model performs a parametric sweep on the generation and detection element positions for each array design in order to identify the optimal parameters, based on mean and maximum side-lobe level. In the presented framework, four array designs are utilized for the optimization process: matrix, random, Vernier and a novel array design the Rotated Array (RA).
Quartz enhanced low sampling trace gas detection
Authors: Yang Shangjie , Zhong Yuanxin , Liu Zheng , Dong Huikun , Gao Chunming , Gong Yanli
Published: October 2024

Dectection of the exhaled gas, which can effectively reflect human health status, analyze and predict diseases has become a research focus. Quartz enhanced photoacoustic spectroscopy (QEPAS) technology has the advantages of small volume, low cost, and high sensitivity, exhibiting great potential in exhaled gas detection. In this work, small volume fractions of CO were detected by QEPAS technology. Optimizing the structure based on finite element method and designing circuit, a detection system with adjustable photoacoustic cell pressure was established. Then, the corresponding relationship between gas volume fraction and response signal was calibrated by the detection of multiple volume fractions of CO. The system has shown a volume fraction detection limit of 531.2×10−9, with a normalized noise equivalent absorption coefficient of 2.86×10−8 cm−1/Hz1/2 and an average detection error of less than 0.8%. The results indicate that our QEPAS system could monitor the exhaled CO trace gas, showing broad application prospects.
Design and Characterization of SAW-Based Wireless and Passive Temperature Sensing System
Authors: Zhou Zhixin , Wang Hui , Chen Minkan , Zhang Linwei , Lou Liang
Published: October 2024

The Surface Acoustic Wave (SAW) temperature sensor has received significant attention due to its wirelessly-powered, battery-free, and chipless capabilities. This paper proposes a wireless sensing system comprising a one-port SAW resonator, antennas, and transceiver circuit. The SAW resonator utilized in this system was based on Aluminum Nitride (AlN) thin film, which exhibits high SAW velocity and excellent piezoelectric properties. To completely investigate the performance of the SAW resonator, simulation and experiments were conducted. Upon connecting the SAW sensor to the temperature sensing system via the antenna, the reflection peak of the SAW resonator was clearly observed in the spectrum of the return signal. Additionally, during the temperature tests, the response frequency displayed almost linear behavior as the temperature increased from 30°C to 150°C. The fitted temperature coefficient of frequency (TCF) was 30.68ppm/°C, indicating that the wireless temperature sensing system has high temperature sensitivity.
Numerical studies of one-way Lamb and SH mixing method in composite laminates with transverse-isotropic quadratic nonlinearity
Authors: Liu Xiang , Zhao Youxuan , Deng Mingxi , Hu Ning
Published: October 2024

The resonant behavior of one-way Lamb and SH (shear horizontal) mixing method in composite laminates with transverse-isotropic quadratic nonlinearity is investigated through numerical simulations in this paper. Different from previous studies, the composite constitutive model is combined from orthotropic elasticity and transverse-isotropic quadratic nonlinearity, which is implemented by ABAQUS/VUMAT subroutine. When two fundamental waves (S
0-mode Lamb waves and SH
0 waves) mix in composite laminates with quadratic nonlinearity, the resonant SH
0 waves can be generated with the resonance condition ω

S
0
/ω

SH
0
= 2 κ/(κ + 1). Meanwhile, the relationships between the acoustic nonlinear parameter (ANP) and damage degree, fundamental frequency, frequency deviation, propagation distance are also investigated. Moreover, the method of locating the damage region in composite laminates is proposed and verified by using the resonant wave time-domain signal.
Nonlinear interaction of Lamb waves with fatigue cracks in metal plates under the condition of phase-velocity mismatching
Authors: Sun Di , Zhu Wujun , Xiang Yanxun
Published: October 2024

Nonlinear Lamb waves have been widely acknowledged as an efficient method for evaluating material damage at an early stage. However, due to the dispersive and multimode natures of Lamb waves, nonlinear Lamb waves with exact/approximate phase-velocity matching have been employed in previous research solely for the evaluation of fatigue cracks. Second harmonic Lamb waves can be generated from the contact acoustic nonlinearity (CAN) induced by the “breathing” effect of fatigue cracks. This paper presents a verification of the second harmonic S0 mode Lamb waves due to fatigue crack CAN, despite the mismatch in phase velocity between this mode and the primary S0 mode Lamb waves. This verification is achieved through both simulation and experiment. Consequently, the generation of double-frequency Lamb waves by fatigue cracks under conditions of phase velocity mismatching is validated. Furthermore, the phase-velocity mismatching method is anticipated to exclude material nonlinearity in the detection of fatigue cracks. This method offers a potential for accurate detection and evaluation of fatigue cracks.