Search Results (490)

As mineral resource extraction progressively extends to greater depths, the complex deep underground environment poses severe corrosion-induced deterioration risks to anchoring structures such as rock bolts. Anchorage failure has thus become a critical safety concern constraining the stability of deep roadways. To address the failure mechanisms of anchoring systems under multi-physical field coupling effects, this study conducts numerical simulations of multi-field corrosion processes and ultrasonic nondestructive testing (NDT) based on a numerical modeling platform. The influence of temperature on corrosion rate and current density is systematically analyzed, and interface response characteristics are extracted and interpreted for defects of varying dimensions. A spatial complementary mechanism under different corrosion defect configurations is revealed, and a health diagnosis system incorporating multiple critical indicators is established. The results indicate that elevated temperature significantly accelerates bolt corrosion: the rise in temperature shifts the equilibrium potential negatively and exponentially increases the reaction rate constant, both of which synergistically promote anodic dissolution. In ultrasonic testing, monitoring points along the main axis are positioned within the transmission-focused zone, where defects induce acoustic wave diffraction and superposition such that even minor defects cause a multiplication of the dominant frequency. Lateral monitoring points lie in the reflection–interference zone, where small defects preferentially attenuate energy, while larger defects manifest as amplitude reduction and first-arrival wave lag; all characteristic indices increase monotonically with defect size. Based on the numerical simulation outcomes, a four-level grading diagnosis standard and a “bottom–lateral” detection scheme are proposed as simulation-based reference indicators. The model effectively reproduces both corrosion deterioration and acoustic wave propagation characteristics, thereby providing a quantitative basis for the assessment of anchoring structures in high-temperature deep underground environments. Full article

To exploit ultra-low power logic and architectural design techniques for bio-sensors in the human body, wireless ultrasonic techniques have emerged as a strong candidate for intra-body power transmission, thanks to lower medium attenuation and higher permitted safe intensity levels. When sub-100 $\mathsf{\mu }$m dimensions are considered for the bio-sensor, most devices struggle to guarantee a suitable voltage and power for digital electronics due to additional scaling requirements. This study investigates three alternative piezoelectric micromachined ultrasonic transducers in aluminum nitride doped with scandium, as reported in the literature, operating in the range 1–10 MHz. Their respective advantages and limitations with regard to energy harvesting and signal transmission performance are analyzed. It is shown that devices with footprints of less than 100 × 100 $\mathsf{\mu }$m² can achieve voltage outputs of over 150 mV and average power greater than 100 nW. Full article

High-frequency ultrasonic transducers are pivotal for detecting minute defects, offering distinct advantages in terms of non-destructive evaluation, non-invasiveness, and superior spatial resolution. However, achieving effective focusing and efficient acoustic transmission for ultra-high-frequency ultrasonic transducers is a significant challenge. To address this challenge, a mass–spring acoustic matching layer is designed for a transducer based on a half-concave LiNbO₃ piezoelectric element at 100 MHz. The proposed mass–spring stack, comprising a 0.25 μm Au layer and a 2.5 μm Parylene-C layer, operates within a deposition-friendly thickness range ideal for curved substrates, while a conventional quarter-wavelength Parylene-C layer would necessitate a thickness of 6.0 μm at this frequency. The transducer is modeled in COMSOL Multiphysics 6.1, coupling solid mechanics, electrostatics with piezoelectric effects, and pressure acoustics for the water load. Using a fixed concave geometry (curvature radius is 1 mm, which means the focal length is also 1 mm), a frequency sweep from 50 MHz to 150 MHz is conducted to evaluate performance. Analysis of the pressure distribution in the focal plane reveals that the focal length and the −6 dB beamwidth are predominantly governed by aperture diffraction and exhibit minimal variation upon incorporation of a matching layer. The focal length is approximately 1.02 mm within the excitation frequency range of 70 MHz–150 MHz, and the beamwidth decreases markedly with increasing frequency. At 100 MHz, the measured −6 dB beamwidth is approximately 31.6 μm without a matching layer, 32.3 μm with a quarter-wavelength matching layer, and 31.0 μm with a mass–spring matching layer. Crucially, quantitative comparisons reveal that this design yields a systematically higher focal pressure; near the 100 MHz design frequency, the acoustic pressure amplitude achieved with the mass–spring configuration is 1.5 times greater than that obtained using the quarter-wavelength reference. These research results provide a theoretical basis for the application of ultra-high-frequency ultrasound in the detection of tiny defects. Full article

With the rapid development of intelligent connected vehicles and autonomous driving, real-time and accurate road condition perception has become increasingly critical. Aiming at the limitations of traditional direct and indirect detection methods, this paper proposes an ultrasonic-based real-time detection system for road roughness. Most urban roads today feature asphalt pavements; therefore, this system focuses its research on asphalt pavements. Under the same pavement type (asphalt roads), there is a strong correlation between pavement roughness and the friction coefficient. By measuring the roughness of different pavements, the friction coefficient is estimated using the fuzzy processing method. Then the system through measuring ultrasonic echo amplitude and sensor–road distance, combined with software digital filtering, dual-parameter compensation (distance and temperature–humidity), probabilistic statistical analysis, and fuzzy inference, the mapping relationship among echo signals, road roughness and friction coefficient is established. The system mainly includes an ultrasonic transceiver module, a hardware signal conditioning module, and an MCU-based data processing, display and transmission module. Both simulated experiments and real asphalt pavement tests are carried out for verification. The results show that the system can effectively suppress noise, compensate distance attenuation and environmental interference, and achieve accurate real-time detection of road roughness, with a relative error less than 10% compared with the reference value. The proposed system can provide reliable data support for vehicle active safety systems and autonomous driving applications. Full article

Galloping of iced transmission lines under complex microclimates poses a severe threat to power grid security, whereas traditional full-span de-icing strategies suffer from excessive energy redundancy and limited spatial precision. To address the spatial uncertainty of actual ice accretion, a three-dimensional nonlinear aeroelastic finite element model is established by considering geometric nonlinearity and eccentric ice-induced added stiffness. A state-space Monte Carlo framework is then used to evaluate the galloping probability under different wind speed regimes and spatially non-uniform ice distributions. The results reveal a distinct non-monotonic instability characteristic: the galloping probability decreases to 33.0% at 8.0 m/s, forming a clear probability trough and indicating an aerodynamic self-stabilization effect associated with the shift in the baseline effective angle of attack. To map spatial ice heterogeneity to global dynamic instability, a galloping sensitivity index (GSI) based on the Spearman rank correlation coefficient is proposed to identify the dominant sensitive sections responsible for inducing galloping-prone responses. Based on this index, a GSI-guided targeted ultrasonic de-icing decision strategy is constructed. Under the assumption of identical rated power for each section, the proposed strategy activates only 40% of the physical sections and reduces the number of activated sections, as well as the associated operational energy demand, by 60% compared with the full-span de-icing strategy. This framework provides a quantitative basis for linking stochastic ice distribution, galloping probability evaluation, and energy-efficient targeted de-icing decisions. Full article

With the continuous advancement of ocean exploration and development, energy supply for underwater electronic equipment has become a key bottleneck restricting long-term operation. Traditional wired power supply and battery-powered operation suffer from corrosion, high maintenance costs, limited endurance, and replacement difficulties. Underwater ultrasonic wireless power transfer (UUWPT) achieves contactless electric–acoustic–electric conversion via piezoelectric transducers. It offers unique advantages, including insensitivity to electromagnetic interference, metal-penetration capability, excellent directivity, and medium-to-long-distance transmission. This paper systematically reviews the technical principles and development history of UUWPT. We trace its evolution from early feasibility verification, through theoretical improvements, to current system engineering and industrialization. Key frontier research directions are highlighted, such as MIMO/MISO arrays, simultaneous wireless power and data transfer (SWPDT), adaptive tuning, and novel transducer structures. Application prospects in marine monitoring, AUV endurance replenishment, marine energy development, and the Internet of Underwater Things are also analyzed. Finally, we discuss remaining challenges, including the trade-off between transmission efficiency and distance, insufficient adaptability to complex marine environments, and the lack of standardized system frameworks. Future research should prioritize high-efficiency long-distance power transfer, system reliability, and engineering applications. Full article

Ellagic acid (EA) possesses various biological activities, including anti-inflammatory, whitening, and antioxidant properties. Its practical application is limited by poor aqueous solubility and susceptibility to degradation. To overcome these limitations, this study prepared EA liposomes using the thin-film hydration–ultrasonication method, followed by surface modification with low-molecular-weight chitosan (LM-CS) and medium-molecular-weight chitosan (MM-CS), yielding EA liposomes modified with LM-CS (EA-L-LC) and MM-CS (EA-L-MC), respectively. The formulation and preparation process were optimized using a Box–Behnken design combined with response surface methodology. Under optimal conditions, the mean particle size (MPS), polydispersity index (PDI), Zeta-potential, and encapsulation efficiency (EE) of the different liposomes (unmodified EA-L, EA-L-LC, and EA-L-MC) were determined. Morphological observation and functional group characterization were conducted via transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR), respectively. The stability of the various liposomes was compared under different environmental conditions, and their stability and the released amount of EA were evaluated during in vitro digestion. The in vitro antioxidant activity and tyrosinase inhibitory effects of the different liposomes were investigated. After process optimization, the encapsulation efficiency of EA liposomes was effectively enhanced following modification with chitosan of different molecular weights. TEM and FTIR results confirmed that EA was effectively encapsulated, and chitosan was successfully coated onto the outer layer of the liposomes. Compared to unmodified EA liposomes (EA-L), the chitosan-modified liposomes (EA-L-LC and EA-L-MC) exhibited enhanced in vitro antioxidant activity and sustained, slow-release tyrosinase inhibitory effects, along with superior stability across multiple conditions. In vitro digestion experiments demonstrated that EA-L-MC and EA-L-LC achieved slower release rates in simulated gastric fluid compared to EA-L, thereby improving the digestive stability of EA. Full article

Laser-induced acoustic communication is a highly adaptable cross-medium technique that combines the advantages of optical transmission through air and acoustic transmission underwater. However, poor signal stability at high repetition frequencies currently hinders its widespread application. To address this, this paper proposes an innovative scanning focal-point method to enhance stability. Traditional methods such as beam scanning, focus control, and distributed interaction are primarily aimed at enhancing sound pressure in a specific direction, achieving near-field/far-field focusing, or improving the signal-to-noise ratio through coherent synthesis of ultrasonic intensity. In contrast, the method proposed in this paper is intended to avoid the interference of droplets and vapor generated by single-point breakdown under high repetition frequencies, which would otherwise degrade the laser-acoustic conversion efficiency. It is therefore an active defense strategy specifically targeting the stability of laser-induced acoustic communication. First, optical simulation software was used to analyze the effects of surface ripples and bubbles on focal spot displacement and size. Next, a single-pulse experimental system was developed to measure the range and duration of surface depressions caused by optical breakdown. Finally, a scanning focal-point system was constructed for comparative experiments, with results recorded via hydrophones and high-speed cameras. The maximum laser-induced acoustic signal generated by the scanning focal-point method is 7.4 times that produced by single-point breakdown. The experimental results demonstrate that the scanning focal-point method can effectively avoid the influence of water surface disturbance and steam on the optoacoustic conversion efficiency and significantly improve the amplitude and stability of the laser-induced acoustic signal. Full article

To investigate changes in seismic wave propagation in different types of igneous rocks under dry and water-saturated conditions, this study employed CT scanning to characterize the microstructural development of three distinct igneous rock types. Laboratory measurements were then performed to determine the density, porosity, permeability, and compressional and shear wave travel times of the rock cores in both dry and water-saturated states. The results show that water content significantly affects the waveforms in both the time and frequency domains. For rocks with developed pores and fractures, the propagation of seismic wave energy is impeded under water-saturated conditions, causing faster attenuation of ultrasonic waves while high-frequency components are retained. For dense rocks, the amplitude of the initial wave segment decreases, the middle-segment amplitude increases, and the tail wave undergoes significant attenuation under saturated conditions, with frequency components in the 50–100 kHz range being filtered out. Furthermore, higher water content leads to lower shear-wave amplitudes and more severe attenuation. These findings contribute to the proper use of acoustic logging data for understanding the microstructure and water content characteristics of igneous rock reservoirs. Full article

Accurate and reliable groundwater-level monitoring in deep observation wells remains difficult for conventional non-contact ultrasonic systems because narrow tubular geometries intensify multipath reflections, signal attenuation, and echo ambiguity. This study proposes a dual-signal direct time-of-flight (ToF) method that combines radiofrequency (RF) synchronization with one-way airborne ultrasonic propagation to a floating receiver located at the groundwater surface. In the proposed architecture, the RF signal provides a near-instantaneous time reference, whereas the ultrasonic signal defines the propagation delay, thereby eliminating dependence on echo-based ranging. The system integrates a wellhead surface unit for synchronized transmission and control, a floating unit for ToF acquisition and embedded processing, and an optional reference channel for in situ estimation of the effective sound speed. A duty-cycled power architecture is used to support low-power long-term deployment, while a multi-shot acquisition strategy with a median-like estimator improves robustness against startup transients, timing jitters, and false detections. Field validation was conducted over a 12-month period under actual groundwater-monitoring conditions, during which the groundwater depth varied between 14 m and 30 m below the wellhead datum. Within this field-validation interval, the proposed system achieved a mean absolute error of 0.048 m, a maximum absolute error of 0.050 m, and an overall valid detection rate of 99.4% over 358 valid cycles out of 360 scheduled cycles. In addition, a separate range-dependent confined-tubular propagation test was conducted to evaluate the extended detection capability of the RF-synchronized one-way ultrasonic ToF architecture. This test demonstrated stable acoustic-link ToF detection up to 300 m inside the tested 170 mm confined plastic pipeline. Therefore, the 300 m result should be interpreted as a range-dependent valid-detection result rather than as a 12-month groundwater-depth validation over the full 300 m interval. These results demonstrate that the proposed direct-ToF method provides an RF-synchronized one-way ultrasonic ToF framework with a floating receiver for groundwater-level monitoring in deep observation wells, while remaining compatible with low-power and IoT-based environmental monitoring systems. Full article

Extracting hydrocarbons from complex, ultra-deepwater and high-pressure/high-temperature wells requires precise control of hydrostatic pressure to avoid well control problems. Among these, a gas kick is one of the most serious events, as it can quickly develop into a blowout with severe consequences for both safety and project cost. Traditionally, the industry has depended on reactive surface-based indicators, such as pit volume and delta flow, for early kick detection (EKD). However, these methods are often limited by data transmission delays and frequent false alarms. This review goes beyond a conventional summary by critically examining the key weaknesses of current EKD technologies. In particular, it highlights major challenges in modern sensor systems, including the difficulty of interpreting ultrasonic signals in multiphase flow and the way formation leakage can hide or distort kick indicators. It also provides a detailed and original link between specific Artificial Intelligence (AI) models and the drilling signals they are designed to analyze. Although recent studies have shown progress in downhole sensing and predictive algorithms, a significant gap still exists between theoretical models and the highly dynamic, multiphase conditions found in real wellbores. This makes it necessary to evaluate EKD technologies considering actual field demands rather than idealized assumptions. To address these limitations, this review proposes several practical directions for future work. These include the development of dynamic, multiphase, acoustic computational fluid dynamics (CFD) models to improve ultrasonic signal interpretation, the standardization of unsupervised AI models supported by synthetic data generation, the integration of unified leakage detection frameworks, the mechanical standardization of Managed Pressure Drilling (MPD) systems, and the adoption of rig-based edge computing to enable faster and more reliable real-time decision-making. Full article

The aim of this review is to clarify the mechanism and influencing factors of flow-assisted corrosion in multi-medium transmission pipelines for pipeline safety management, along with the progress in nondestructive testing in this vein. Such pipelines undergo severe flow-assisted corrosion under multiphase-flow, high-temperature, high-pressure, and complex chemical conditions, threatening structural integrity and operational safety. This study summarizes the dominating roles of aqueous wetting, mass transfer, and flow-induced shear stress in corrosion evolution and analyzes the coupling effects of hydrodynamics, medium chemistry, and material properties on corrosion deterioration. The applicational advantages and limitations of ultrasonic guided-wave, magnetic flux leakage, and eddy current testing in corrosion detection are systematically concluded. Future development trends combining artificial intelligence, machine learning, and digital twins are projected, providing a reference for intelligent detection and full-life-cycle integrity management of transmission pipelines. Full article

The conventional microstepping driving method suffers from significant periodic speed oscillations under ultra-low-speed conditions, which fail to meet the stringent demand for smooth operation of ultrasonic motors in semiconductor packaging. Most existing theories and simulations of ultrasonic motors adopt a macroscopic mechanical perspective; after extensive linearization and idealization, they can only provide preliminary mechanism analysis and fail to achieve precise quantitative computation. Moreover, they neglect critical factors such as the microstructure of contact surfaces, preload distribution, and vibration mode transmission, making it difficult to reflect the true characteristics of the motor—including strong nonlinearity, multiphysics coupling, and complex interface behavior—resulting in considerable discrepancies between theory and experiment. In this paper, a macro-micro multi-scale finite element model of a traveling-wave ultrasonic motor is established using ADINA and HyperMesh, fully accounting for the strong nonlinearity and multiphysics coupling effects. Based on the ultrasonic friction reduction theory and the beat traveling wave mechanism, the stator deformation, interface zoning characteristics, and torque output of the superimposed pulse driving method and the microstepping driving method are systematically compared. The simulated stator mode shapes are validated by laser scanning vibrometry experiments, and multiple speed tests ranging from 200 to 320 arcsec/s are conducted. Simulation results show that at a target speed of 900 arcsec/s, the superimposed pulse driving method reduces the speed fluctuation rate from 228% to 32%. Experimental results confirm that the speed fluctuation rate of the superimposed pulse driving method is consistently much lower than that of the microstepping driving method across the entire tested speed range. This study reveals the low-speed smooth operation mechanism of the superimposed pulse driving method, characterized by single-peak dominance and smooth alternation between the driving and braking zones, thereby fundamentally overcoming the inherent shortcomings of the traditional microstepping driving method. The proposed model can effectively replace costly direct interface measurements, providing a new method and reference for ultra-low-speed precision control of ultrasonic motors and for investigating the driving mechanisms of similar motors. Full article

In the field of traditional aging state evaluation of paper materials, traditional detection technologies such as ink drop method and chemical analysis have inherent limitations including sample damage, strong subjectivity, and inability to realize large-area detection. To address these problems, a non-contact and non-destructive testing method based on air-coupled ultrasonic technology was developed in this study, to achieve objective and quantitative characterization of paper roughening degree and ink wettability. The system adopted a LabVIEW-based host computer to control scanning and signal acquisition. Based on the propagation and scattering mechanism of ultrasound in the porous fiber structure of paper, the amplitude difference and pixel distribution of C-scan images were extracted as core characteristic parameters. The experimental results show that, with a 400 kHz air-coupled probe and 200 mm/s scanning speed, the roughening degree of paper can be quantitatively characterized by the amplitude difference of ultrasonic transmission signals. The amplitude difference increases significantly with the rise of water content, and the difference in roughening characteristics between newsprint and Xuan paper can be clearly distinguished. The ink wettability can be judged by the pixel distribution of the C-scan image: the higher the proportion of intermediate color pixels, the closer the ink circularity is to 1, and the better the ink wettability. All test results are highly consistent with the national standard GB/T 18739-2008. The constructed air-coupled ultrasonic testing system can provide reliable technical support for quality control and aging evaluation of paper cultural relics and high-grade paper by characterizing both surface roughening and internal porous structure (which are coupled during paper aging), without any contact or damage to the samples. Full article

To investigate the resin infusion molding process for novel dry fiber-reinforced epoxy composite wing skin, dry fiber preforms were fabricated via an automated fiber placement (AFP) system, and the out-of-plane permeability of the preforms at different lay-up speeds was measured using the ultrasonic transmission method to determine the optimal lay-up parameters. A scaled-down composite wing skin structure was modeled and meshed via numerical simulation, and different resin infusion schemes were simulated and analyzed using PAM-RTM software. The optimal infusion scheme was determined by comparing the infusion time, infusion pressure and defect formation during resin flow for different schemes, and the wing skin component was fabricated through the vacuum-assisted resin infusion (VARI) process. Results indicate that the infusion time predicted by PAM-RTM simulation is 3883 s, while the actual measured value in the VARI process is 3611 s with an error of approximately 7% within a reasonable range. Both simulation and actual wing skin fabrication exhibited no significant defects, validating the accuracy of the three-dimensional permeability measurement of dry fiber preforms as well as the reliability of the simulation results. Full article