Search Results (456)

To improve the pumping performance of biomimetic flapping-wing devices in small river channels, this study introduces high-frequency disturbances in the heave direction based on traditional pitch–heave motion. A systematic investigation of the forces and hydrodynamic performance is conducted using numerical simulations, with vortex contour analysis to explore the evolution mechanism of the wake vortex structure. The results show that high-frequency disturbances cause the instantaneous thrust to exhibit an amplitude modulation feature, with thrust oscillating approximately f_p/f_b times within one base frequency cycle. As the disturbance frequency increases, the average thrust also increases. There is a significant frequency-dependent difference in performance: at low disturbance frequencies (f_p/f_b ≤ 16), changes in thrust, pressure difference, and flow rate are limited, with little improvement in pumping efficiency; at intermediate frequencies (16 < f_p/f_b ≤ 32), wake coherence and jet momentum flux are significantly enhanced, and both thrust and pumping efficiency reach their maximum (up to 47%); at high disturbance frequencies (f_p/f_b > 32), although the vortex structure is further strengthened, input power increases sharply, leading to a decrease in efficiency. Overall, moderate disturbance frequencies can effectively enhance the thrust and pumping performance of the flapping wing, while excessively high frequencies do not offer an advantage due to the high energy cost. Full article

To clarify how flow-channel configuration and wall spacing govern the hydrodynamic performance of an oscillating-hydrofoil biomimetic pumping device, this study conducted a systematic numerical investigation under confined-flow conditions. Using a finite-volume solver with an overset-grid technique, we compared pumping performance across three channel configurations and a range of channel–wall distances. The results showed that bidirectional-channel confinement suppresses wake deflection and irregular vorticity evolution, enabling symmetric and periodic vortex organization and thereby improving pumping efficiency by approximately 33.6% relative to the single-channel case and by 62.7% relative to the no-channel condition. Wall spacing exhibited a distinctly non-monotonic influence on performance, revealing two high-performance regimes: under extreme confinement (gap ratio $h/c=$ 1.4), the device attains peak pumping and thrust efficiencies of 19.9% and 30.7%, respectively, associated with a strongly guided jet-like transport mode; and under moderate spacing ($h/c=$ 2.2–2.6), both efficiencies remain high due to an improved balance between directional momentum transport and reduced vortex-evolution losses. These findings identify key confinement-driven mechanisms and provide practical guidance for optimizing flow-channel design in ultralow-head oscillating-hydrofoil pumping applications. Full article

In the construction of grouting holes in high-mud-content layers, high-pressure jet cleaning technology effectively cuts and removes soil and sediments from the strata. This research designs the structure of a high-pressure jet cleaning device and establishes a numerical simulation model for the high-pressure jet cleaning nozzle, conducting orthogonal simulation tests. Based on the data from these tests, a Backpropagation (BP) Neural Network-based numerical prediction model for the high-pressure jet cleaning flow field is developed, enabling the prediction of cleaning flow rates and pressures for different nozzle channel structure parameters. Targeting jet fluid velocity and cleaning pressure, parametric shape optimization is performed on the nozzle channel structure: key parameters are identified via Analysis of Variance (ANOVA) and sensitivity analysis; an improved Non-dominated Sorting Genetic Algorithm II (NSGA-II) is adopted to establish a multi-objective optimization model, which exhibits superior convergence speed and solution diversity compared to the traditional algorithm. The optimal jet fluid velocity, cleaning pressure, and fluid structure parameter solution space for the high-pressure jet cleaning nozzle are obtained. Through simulation and experimental verification, it is found that with the same number of nozzles, the optimized design significantly enhances both the average cleaning flow rate and the cleaning pressure. Finally, a high-pressure jet cleaning nozzle and device are prototyped based on the simulation and optimization results and tested in the grouting test area A2W-2-III-6 of the South-to-North Water Diversion Project Xiong’an Storage Reservoir Project. This study provides a scientific basis and technical support for the application of high-pressure jet cleaning technology in complex geological formations. Full article

Downbursts generate strong and transient near-surface winds that significantly influence wind flows over complex terrains. In this study, two downburst models—the impinging jet model representing the near-field region and the wall jet model representing the fully developed outflow—were experimentally investigated. The study examined the characteristics of mountain wind fields within the fully developed region, considering variations in mountain height, slope, shape, and radial position. Results show that mountain height and shape exert only minor influences on the mountain speed-up ratio, whereas slope and radial position play dominant roles: the acceleration ratio decreases with increasing radial distance and with steeper slopes. The near-surface flow is mainly affected within a vertical range of approximately 1.5 times the mountain height and a radial distance of about four times the height. By explicitly comparing the two models, this study provides the quantitative experimental relationship linking the vertical position of maximum horizontal velocity between impinging jet and wall jet flows. The comparison of mountain wind fields under equivalent positions demonstrated consistent speed-up ratios, confirming that the wall jet model can effectively reproduce the fully developed stage of downburst winds over mountainous terrain. Thus, this work offers new experimental evidence and a validated modeling framework for studying mountain wind effects under downburst conditions. Full article

Background: Patients undergoing maintenance hemodialysis (HD) have a high risk of developing cardiovascular diseases due to calcification of the heart valves and coronary arteries, which results in a high mortality rate. In particular, aortic stenosis (AS) is an independent risk factor for heart failure-related mortality in patients undergoing HD. Recently, the analysis of digitized heart sounds using artificial intelligence (AI) has promoted the automation of cardiac disease detection and technological advances in diagnostic algorithms. Methods: We retrospectively investigated the 203 consecutive patients receiving HD who had undergone visualized phonocardiography using a regulatory-approved medical device (Japan) between January and May 2025 to detect AS. The usefulness of this phonocardiogram device, which utilizes acoustic analysis and an AI-based automatic diagnostic algorithm named the “Super Stethoscope”, was evaluated for the screening of AS in patients undergoing HD based on comparisons with findings obtained from echocardiography. Results: The results showed a significant correlation between the severity of systolic murmurs determined by the AI-based approach and the peak aortic jet velocity measured in 19 patients diagnosed with AS using transthoracic echocardiography (r = 0.578, p < 0.05). Additionally, for the AI-based diagnosis of AS based on systolic murmurs, the sensitivity and specificity in detecting moderate or severe AS were 0.90 and 0.70, respectively, among the patients undergoing HD. Conclusions: The AI-based diagnostic approach using the ECG-gated phonocardiogram “Super Stethoscope” could be a promising tool for AS screening. Transthoracic echocardiography is recommended in cases classified as grade B or higher by AI-based assessment. Full article

ZnO thin-film ultraviolet photodetectors are widely used in the military, space, environmental protection, medicine, and other fields. Accurate printing of ZnO photoelectric-sensitive films plays a key role in the detection results. Therefore, obtaining printing technology with a simple process and high precision has become a challenge for ZnO photoelectrically sensitive films. By adjusting the distance between the nozzle and the collecting plate, the jet is atomized in a straight line and deposited directly on the collecting plate, which effectively improves the stability and controllability of the jet spraying and deposition processes. ZnO thin films with a uniform distribution of nanoparticles, significantly improved density, and controllable deposition area linewidth were successfully prepared. The effects of different ZnO film structures on the performance of ultraviolet photodetectors were tested. When the ultraviolet light intensity is 500, 1000, and 2500 mW/cm², the $I_{light}$ of the photodetector is 4.62, 9.38, 14.67 mA, The on/off ratio ($I_{light}$/$I_{dark}$) is 20.7, 42.1, 65.8, implying satisfactory photoelectric performance as well as high stability and repeatability, providing an effective technical means for the precise printing application of micro-nano functional devices. Full article

Gas-assisted coaxial electrospinning (GACES), a simple and versatile technique for the large-scale fabrication of coaxial nanofiber membranes, possesses significant industrial potential across advanced manufacturing sectors including semiconductors—particularly for fabricating high-precision dielectric layers, high-uniformity encapsulation materials, and flexible semiconductor substrates requiring tailored core-shell architectures. However, there is still a lack of relevant studies on the effective regulation of the core-shell structures of coaxial fibers based on GACES, which greatly limits the batch preparation and wide application of coaxial fibers. Finite element simulation analysis of the flow field and development of the coaxial jet mechanics model with a gas-driven flow field—two key methodologies in this study—successfully uncovered the influence mechanism of gas-assisted flow fields on the core-shell structures of coaxial nanofibers. By adjusting the gas-assisted flow fields parameters, we reduced the total diameter of coaxial fibers by 47.33% (average fiber diameter: 334.12 ± 16.29 nm → 175.98 ± 1.18 nm), decreased the shell thickness by 72.98%, increased the core-shell ratio by 289% (core-shell ratio: 0.49 → 1.91), and improved the uniformity of the total diameter distribution of coaxial fibers by 30.64%. This study delivers a practical conceptual framework and robust experimental underpinnings for the scalable fabrication of coaxial nanofiber membranes with controllable core-shell structures, thereby promoting their practical application in semiconductor devices such as ultra-thin dielectric layers, precisely structured encapsulation materials, and high-uniformity templates for nanoscale circuit patterning. Full article

Mechanical amplifiers can enhance the travel range of piezoelectric actuators, thereby expanding the applications of these actuators. Various amplification mechanisms have been proposed for piezoelectric actuators with different design requirements. For instance, rhombus- and bridge-type amplification mechanisms are compact and can therefore be applied in many applications with size restrictions. However, the amplification ratio of a single-stage rhombus- or bridge-type mechanism is limited. In this study, a novel three-stage amplifier was developed to achieve a high amplification ratio while keeping the device compact. A piezoelectric actuator integrated with this amplifier had a travel range of 207.5 μm, an amplification ratio of 13.7, and dimensions of 33.5 mm × 34.2 mm × 10 mm. Moreover, this actuator was used to construct a compact jetting dispenser with dimensions of 69 mm × 72 mm × 20 mm. Experimental results suggested that this dispenser can generate uniform and stable droplets, confirming the practical utility of the developed piezoelectric actuator. Full article

Background and Objectives: Airway management and ventilation during laryngotracheal surgery represent some of the most challenging tasks in anesthesiology. The shared airway between the surgeon and anesthesiologist requires continuous coordination to ensure optimal oxygenation while maintaining an unobstructed surgical field. Materials and Methods: This narrative review is based on a comprehensive literature search of PubMed, Embase, Scopus, and Google Scholar, covering all publications from inception to 30 June 2025. The literature search was performed using a defined Boolean strategy and explicit inclusion/exclusion criteria, focusing on adult human subjects. The search included combinations of the terms “laryngotracheal surgery,” “airway management,” “ventilation strategies,” “jet ventilation,” “Tritube,” and “Flow Controlled Ventilation.” Only English-language studies focused on human subjects were included. Results: Traditional ventilation strategies, such as apneic oxygenation and jet ventilation, remain widely used but present limitations in terms of gas exchange efficiency, risk of barotrauma, and surgical interference. In recent years, new devices and ventilation modes—particularly the Tritube^® combined with Flow-Controlled Ventilation—have emerged as promising alternatives. These approaches allow continuous ventilation with minimal airway diameter, improving surgical access and patient safety. FCV’s potential to optimize gas exchange and reduce mechanical power is physiologically compelling, but its supporting evidence remains limited and heterogeneous, primarily consisting of small, single-center studies and case series. Conclusions: Optimal airway and ventilation management in laryngotracheal surgery requires individualized planning, technical expertise, and close interdisciplinary communication. This approach must integrate objective neuromuscular monitoring to ensure patient safety and include a comprehensive strategy for safe postoperative airway management and extubation. While emerging technologies have significantly expanded available options, their successful application depends on training, experience, and appropriate case selection. Further high-quality clinical studies are needed to standardize protocols and validate long-term outcomes of these innovative ventilation strategies. Full article

With the rise of the low-altitude economy, there is growing demand for performance and safety evaluation of logistics drones and urban aircraft operating in complex turbulent environments. Conventional wind tunnels, however, face challenges in simulating the non-uniform wind fields characteristic of urban low-altitude conditions, such as building wake flows, street canyon winds, and tornadoes. To address this gap, this study proposes a novel simulation device for low-altitude complex wind fields, which utilizes multi-fan coordinated control technology integrated with jet fan arrays, pressure-stabilizing chambers, and swirl fan systems to dynamically replicate horizontal flows, vertical flows, and specialized wind patterns. Numerical simulations using Ansys Icepak validate the effectiveness of the design: the optimized horizontal flow field achieves a wind speed of 83 m/s with a turbulence intensity ranging from 5% to 20%; the gust mode attains rapid response within 3 s; and high-fidelity simulations are achieved for wind shear, tornadoes (with a maximum tangential wind speed of 50 m/s), and downbursts (with a central vertical jet velocity of 40 m/s). Furthermore, for typical urban wind environments such as alley winds and intersection flows, the study elucidates the characteristics of abrupt wind speed variations and vortex dynamics induced by building obstructions. This research provides a new perspective and a potential technical pathway for testing low-altitude aircraft, assessing urban wind environments, and supporting related studies, thereby contributing to the advancement of complex wind field simulation technologies. Full article

This study designed a novel coherent tuyere device capable of adjusting the core length of the jet flow. Physical experiments were first conducted to investigate how the number of secondary nozzles in the coherent tuyere affects the gas–solid two-phase flow behavior within the raceway during the blasting process. Subsequently, the Computational Fluid Dynamics (CFD) method was employed to examine the influence of structural parameters on jet morphology in coherent tuyere. Finally, computational fluid dynamics and discrete phase method (CFD-DPM) was adopted, and the velocity, temperature, and composition distribution patterns within the raceway were analyzed following the injection of hydrogen-rich gas through the coherent tuyere. The results of the physics experiment indicate that increasing the number of secondary nozzles in the coherent tuyere can significantly enlarge the raceway size and broaden the particle kinematic zone, thereby enhancing particle fluidization at the periphery of the raceway. CFD numerical simulation results indicate that increasing the number of secondary nozzles of the tuyere can effectively extend the length of the velocity jet core region. Compared with conventional tuyeres, a six-nozzle coherent tuyere can increase the core length of the blast velocity by about 40%. When the diameter of the secondary nozzles in the coherent tuyere is doubled, the core length of the blast velocity increases by 10%. The results of the CFD-DPM coupled simulation show that unburned carbon particles flow and combust along the periphery of the raceway with the hot air, leading to the formation of a high-temperature region in this area. After the injection of hydrogen-rich gas through the coherent tuyere, the temperature in the raceway decreased significantly. A high-concentration region of H₂ appeared at the periphery of the raceway, while the high-concentration CO region increased in concentration and gradually extended toward the upper part of the raceway. This research achievement is of significant importance for optimizing blast furnace blast kinetic energy and hydrogen-rich gas injection. Full article

The jet pump, a device that entrains and transports fluids using high-speed fluid, is characterized by its simple structure, lack of moving parts, and ease of maintenance. However, its low energy transfer efficiency hinders broader promotion and application. To enhance the entrainment efficiency of the gas–liquid jet pump, this study focuses on optimizing the performance of the liquid–gas jet pump using response surface methodology and numerical simulation. Four key performance parameters—throat length, Nozzle-throat Distance, area ratio, and diffuser angle—are selected for optimization. Computational fluid dynamics (CFD) is utilized for numerical simulation and single-factor optimization analysis is conducted to assess the impact of each parameter on the pump’s performance and to determine each approximate optimal range. Based on these findings, response surface methodology is applied for multi-factor joint optimization. A quadratic polynomial numerical model correlating the factors with the entrainment flow rate is developed through regression analysis, achieving a fitting accuracy of 99.43%. The optimized structural parameters of the gas–liquid jet pump, as predicted by this model, result in a 3.13% increase in peak velocity at the nozzle exit compared to the original design. Additionally, upon ejection, a constant high-speed region of 18 mm is generated at the throat inlet, which constitutes 12.13% of the total throat length. This feature is notably absent in the original design. This leads to a 190.66% increase in the entrainment flow rate, reaching 7.129 m³/h. The significant enhancement in the entrainment performance of the gas–liquid jet pump provides a theoretical foundation for its optimized design. Full article

This Special Issue presents recent advances in the production, modelling, processing, and characterization of advanced industrial materials, highlighting the diversity and sophistication of contemporary research discussing metallic, polymeric, composite, and nano-structured systems. The collected contributions address key challenges in materials science, ranging from surface quality control, the development of novel machining and fabrication tools, and optimization of thermoplastic composite consolidation, to provide fundamental insights into additive manufacturing, rheology, and constitutive modelling. The showcased studies introduce innovative approaches to metrology, including advanced optical, fluorescence, and X-ray scattering techniques for characterizing nano-particles, microstructures, and thermal properties. The presented research also features investigations into the welding of dissimilar steels, binder jetting of stainless steel, and the influence of heat treatment on functional steel performance, alongside environmentally oriented research on natural-fibre energy devices and bio-based polymer composites. Further research topics include defect structures in doped crystals, low-temperature synthesis of oxide films, and mechanical behaviour of steels under extreme conditions. Collectively, these articles demonstrate the strong synergy between experimental methods, computational modelling, and industrial applications, underscoring the continued progress in materials reliability, surface engineering, and advanced manufacturing technologies. This Special Issue therefore provides a comprehensive overview of current trends and emerging directions, offering valuable methodological and conceptual insights in the field. Full article

Digital printing technologies—including inkjet printing, aerosol jet printing, and electrohydrodynamic jet printing—have emerged as promising strategies for next-generation electronic devices. However, the weak adhesion between printed electrodes and substrates can lead to electrode delamination, thereby compromising device reliability and lifetime. In this study, a dielectric interlayer was introduced to improve the adhesion of silver (Ag) mesh electrodes on glass, polyethersulfone film, and polyimide film substrates. The optimized electrode on PES film achieved an optical transmittance of 83% at 550 nm and line resistance of 0.3 Ω, confirming its suitability as a transparent electrode. The incorporation of the interlayer also enhanced the adhesion and mechanical flexibility across all substrates. Moreover, the printed electrodes exhibited uniform surface heating under an applied bias (≤DC 3 V), and their feasibility as low-power flexible transparent heaters was experimentally demonstrated. These findings present a simple and effective printing strategy for fabricating robust and multifunctional electrodes, offering enormous potential for the realization of future flexible and transparent electronic systems. Full article

This paper presents a novel batch Forward Osmosis (FO) process for hydropower generation. It focuses on analyzing the parameters needed to make the proposed osmotic power plant implementable with currently available technology. Starting from the solution–diffusion model and using flow and mass balance equations, the equations that describe the behavior of the system over time are obtained. Membrane orientation, concentration polarization, reverse solute flux, and membrane fouling are not considered. The equations for calculating the operation time for the charging and discharging stages are obtained. Also, an equation for calculating the required membrane area to make the duration of the two stages the same is obtained. The results indicate that a volume of approximately $30.4 {\mathrm{m}}^3$ discharging through a $0.84 \mathrm{i}\mathrm{n}\mathrm{c}\mathrm{h}$ diameter outflow jet towards a turbine could generate an energy of $25 \mathrm{k}\mathrm{w}·\mathrm{h}.$ The discharging stage would take $12 \mathrm{h}$, and with a membrane with a water permeability constant $A_m=1.763·{10}^{-12} \mathrm{m}/(\mathrm{s}·\mathrm{P}\mathrm{a})$, the charging stage would require a membrane superficial area ${Ar}_m=1·{10}^4 {\mathrm{m}}^2$ to have the same duration. The proposed osmotic power plant, whose working principle is based on volume change over time, contrary to pressure retarded osmosis, whose working principle requires expending energy to extract energy from the salinity gradient, could deliver greater net produced energy with comparatively lower operational costs as it does not require high-pressure pumps or energy recovery devices as are required in pressure-retarded osmosis. The use of several tanks that charge and discharge alternatively can make the system generate energy as if it were a continuous process. Full article