Search Results (443)

Climate change-related weather extremes and air pollution have wide-ranging health effects, with emerging evidence suggesting a potential influence on pain. This narrative review explores the relationship between climate-related weather parameters/air pollution with pain across various conditions, including chronic and acute musculoskeletal pain, postoperative pain, headache/migraine, dysmenorrhea, and chest pain. Included studies were published in 2014 or later. Findings indicate that higher humidity/dampness may exacerbate pain in individuals with knee osteoarthritis, while extremes in temperature and humidity are linked to a higher risk of gout arthritis attacks. No clinically meaningful associations were found between weather parameters and acute low-back pain. However, lower barometric pressure, elevated temperatures, and possibly higher humidity may influence postoperative pain levels. Headache and migraine episodes were more frequent during heat waves and periods of high humidity or rainfall, as well as in areas with elevated traffic-related air pollutants and particulate matter. Air pollution exposure was also associated with increased risk of dysmenorrhea, while lower temperatures and higher humidity correlated with more severe menstrual cramps. Temperature extremes were linked to chest pain in patients with asthma and other conditions. Overall, this review highlights the disproportionate pain-related burden of climate change and air pollution on women and emphasizes the need for further research. Full article

The supercritical carbon dioxide (sCO₂) Brayton cycle has advantages such as a compact system and high energy density. Axial turbines, the key component of the cycle, have lower rotational speeds, pressure ratios and engineering difficulties compared to radial turbines. This study focuses on the initial design parameters and the complete design process of a small-scale axial turbine based on nuclear power and utilizing supercritical carbon dioxide. The design objective of this study is a 150 kW single-stage axial turbine. AXIAL software is used for batch calculations in the preliminary turbine design to determine the most reasonable initial design parameters, including back pressure, rotational speed, average radius, and mass flow rate. These initial parameters serve as the starting point for the overall turbine design process. The one-dimensional design results of the turbine show an isentropic efficiency of 77.15%, and numerical simulations validate the accuracy of this efficiency. Full article

To investigate the influence of salt transport in water–steam mixtures on flow and heat transfer and to ensure the operational safety of steam injection boilers, this study simulated the behavior of high-dryness steam carrying salts in U-tubes. The analysis focused on three representative substances—silica, hematite, and calcium carbonate—to evaluate their effects on flow and heat transfer characteristics under varying conditions. The simulation results show that under specified operating conditions, vortices induced by rotational flow lead to complex flow behavior in U-tubes, with transitions from stratified flow to annular flow and back to stratified flow. The effects of salt precipitation on the temperature, velocity, and pressure fields of the boiling flow were also examined. The findings indicate that for pure water, large gradients and multiple vortices adversely affect flow stability, whereas the introduction of small amounts of salts provides localized stabilization in regions of the fluid away from the wall. Full article

The study focuses on the T-shaped tunnel scenario with protective doors, performs explosion tests using aluminized explosives, and investigates the propagation patterns and loading characteristics of explosion shock waves in the straight tunnel, at the T-shaped junction, and within the semi-enclosed space in front of the protective door. It was observed that, in comparison to TNT explosives, the overpressure curve of aluminized explosives in the near-explosion zone exhibited a two- batch characteristic. The second batch presented the maximum overpressure peak. In contrast, in the far zone, the curve displayed a stable triangular waveform. In the main tunnel of the T-shaped opening with protective doors, it was found that the back blast surface located in front of the entrance to the main tunnel experienced the maximum momentum, which could be as high as 12 times greater than that of the reflection area on the blast-facing surface at the entrance of the main tunnel and the shock-wave pressure wave pattern can be divided into four batch. The regularities of each measurement point in multiple tests show consistency, highlighting the influence laws of the geometric structure on the wave pattern and load distribution. In addition, this paper integrates LS-DYNA numerical simulation with aerodynamics theory to reveal that shock waves generate expansion waves and oblique shock waves as they pass through the T-shaped opening. After two reflections off the main tunnel wall and the door, a stable propagation waveform is established. In addition, through dimensional analysis and in combination with the experimental results, the momentum at key positions was analyzed and predicted. This study offers a reference for the design of relevant engineering protection measures. Full article

SiCp/Al composites (Silicon Carbide Particle-Reinforced Aluminum Matrix Composites), due to their light weight, high strength, and superior wear resistance, are extensively utilized in aerospace and other sectors; nonetheless, they are susceptible to tool wear and surface imperfections during machining, which negatively impact overall machining performance. Supercritical carbon dioxide minimal quantity lubrication (SCCO₂-MQL) is an environmentally friendly and efficient lubrication method that significantly improves interfacial lubricity and thermal stability. Nonetheless, current lubrication models are predominantly constrained to gas–liquid two-phase scenarios, hindering the characterization of the three-phase lubrication mechanism influenced by the combined impacts of SCCO₂ phase transition and ultrasonic vibration. This study formulates a lubricant film thickness model that incorporates droplet atomization, capillary permeation, shear spreading, and three-phase modulation while introducing a pseudophase enhancement factor β_ps(p,T) to characterize the phase fluctuation effect of CO₂ in the critical region. Simulation analysis indicates that, with an ultrasonic vibration factor Af = 1200 μm·kHz, a lubricant flow rate Q_f = 16 mL/h, and a pressure gradient Δp_tot = 6.0 × 10⁵ Pa/m, the lubricant film thickness attains its optimal value, with Δp_tot having the most pronounced effect on the film thickness (normalized sensitivity S = 0.488). The model results align with the experimental trends, validating its accuracy and further elucidating the nonlinear regulation of the film-forming process by various parameters within the three-phase synergistic lubrication mechanism. This research offers theoretical backing for the enhancement of performance and the expansion of modeling in SCCO₂-MQL lubrication systems. Full article

A physics-based vehicle–track coupled dynamic model embedding a hydraulic electromechanical regenerative damper (HERD) is developed to quantify electrical power recovery and wear depth in high-speed service. The HERD subsystem resolves compressible hydraulics, hydraulic rectification, line losses, a hydraulic motor with a permanent-magnet generator, an accumulator, and a controllable; co-simulation links SIMPACK with MATLAB/Simulink. Wheel–rail contact is computed with Hertz theory and FASTSIM, and wear depth is advanced with the Archard law using a pressure–velocity coefficient map. Both HERD power regeneration and wear depth predictions have been validated against independent measurements of regenerated power and wear degradation in previous studies. Parametric studies over speed, curve radius, mileage and braking show that increasing speed raises input and output power while recovery efficiency remains 49–50%, with instantaneous electrical peaks up to 425 W and weak sensitivity to curvature and mileage. Under braking from 350 to 150 km/h, force transients are bounded and do not change the lateral wear pattern. Installing HERD lowers peak wear in the wheel tread region; combining HERD with flexible wheelsets further reduces wear depth and slows down degradation relative to rigid wheelsets and matches measured wear more closely. The HERD electrical load provides a physically grounded tuning parameter that sets hydraulic back pressure and effective damping, which improves model accuracy and supports calibration and updating of digital twins for maintenance planning. Full article

In the V-cycle of distributed electric wheel loaders (DEWLs), transport accounts for about 70% of the cycle, making energy saving urgent, while shovel-stage slip limits traction stability. This paper proposes a two-module control framework: (i) a preferred-motor transport strategy that reduces parasitic losses and concentrates operation in high-efficiency regions; and (ii) a load-ratio-based front–rear torque distribution for shoveling that allocates tractive effort according to instantaneous axle vertical loads so that each axle’s torque respects its available adhesion. For observability, we deploy a pre-calibrated lookup-table (LUT) mapping from bucket cylinder pressure to the front-axle load ratio, derived offline from a back-propagation neural network (BP-NN) fit. Tests on a newly developed DEWL show that, compared with dual-motor fixed-ratio control, transport-stage mechanical and electrical power drop by 18–37%, and drive-system efficiency rises by 6–13%. During shoveling, the strategy reduces the peak inter-axle slip from 22–35% to 13–15% and lowers the mean slip to 2.6–5.9%, suppressing sawtooth-like wheel-speed oscillations without sacrificing peak capacity. The method reduces parasitic energy flow, improves traction utilization, and is readily deployable. Full article

Divers’ navigation heavily depends on their experience and physical condition, and accidents caused by failure to return occur every year. To address this issue, we developed a navigation system for divers. This navigation system leverages Raspberry Pi and low-cost sensors, including an accelerometer, gyro sensor, geomagnetic sensor, and pressure gauge, to guide divers along predefined routes back to their starting point. The system employs a 20 Hz sampling frequency and applies high-pass filtering (HPF) to acceleration signals to eliminate gravitational interference. Velocity integration errors are corrected using the rate of pressure change, while impulse noise in accelerometer and geomagnetic sensors is removed via the Robust Kalman Filter (RKF). A time-varying system noise covariance matrix enhances accuracy during rotational states. Quaternion-based attitude avoids gimbal lock, with the Kalman Filter (KF) fusion of accelerometer/geomagnetic data mitigating gyro sensor drift. Forced oscillator trials achieved pitch/roll RMS errors of ±1.23° and ±0.26°. In Kanagawa, Japan, divers successfully navigated 44 waypoints (<5 m spacing) along a route with obstacles (30 m rope, Authors, reefs), with a start/end GNSS positioning error of 6.67 m. Full article

Emergency surfacing acts as the final line of defense in preserving the operational viability of submarines, playing a crucial role in their safety. To investigate the dynamic characteristics of submarine emergency surfacing, utilizing whole moving mesh technology, a method for coupled simulation of high-pressure air blowing out water tanks and emergency surfacing motion of submarines is proposed, enhancing the simulation’s fidelity to real-world dynamics. Based on meeting the requirements for simulation accuracy, utilizing the coupled simulation model, this study explored the effects of varying expulsion pressures on submarine motion parameters including depth, roll, pitch, and yaw angles. The findings indicate that the hull emerges slightly earlier and reaches a marginally higher point when coupling effects are accounted for compared to scenarios where these effects are neglected. At consistent expulsion pressures, as the pitch and roll angles increase and the back pressure decreases, the expulsion rate from the ballast tank accelerates. Higher expulsion pressures result in quicker surfacing of the hull, smaller amplitude of pitch angles, and larger amplitudes of roll angles, while the changes in yaw angle displayed no clear pattern. The methodologies and conclusions of this study offer valuable insights for the design and operational strategies of actual submarines. Full article

In order to solve a certain type of Electro-Hydrostatic Actuators (EHA) hydraulic cylinder small cavity buffer end impact problem, based on AMESim to establish a hydraulic cylinder small cavity buffer machine–hydraulic joint simulation model. First, four important structural parameters, namely, the fitting clearance G of the buffer sleeve and buffer hole, the fixed orifice D, the wedge face angle $\theta$, and the wedge face length L₁ were selected to analyze their influence on the pressure of the buffer chamber and the end speed of the piston. Second, enhanced Social Behavior Optimization (SBO) was used to optimize the back-propagation neural network (BP) model to construct a prediction model for the buffer time T of the small chamber of the hydraulic cylinder, the end-piston speed V_e, the rate of change of the end-piston speed V_r, and the return speed of the hydraulic oil V_h. The SBO–BP model performed well in several key performance evaluation metrics, showing better prediction accuracy and generalization performance. Finally, the multi-objective Non-dominated Sorting Genetic Algorithm II (NSGA-II) was used to optimize the hydraulic cylinder small-cavity buffer structure using the multi-objective NSGA-II with the objectives of the shortest buffer time, the minimum end-piston speed, the minimum change rate of the end-piston speed, and the minimum hydraulic oil reflux speed. The optimized design reduced the piston end speed from 0.060 m/s to 0.032 m/s, corresponding to a 46.7% improvement. The findings demonstrate that the proposed hybrid optimization approach effectively alleviates the end-impact problem of EHA small-cavity buffers and provides a novel methodology for achieving high-performance and reliable actuator designs. Full article

The transportation and automotive industries are slowly integrating biocomposite materials into products where the economics make sense; this typically means a short manufacturing cycle time, not using expensive prepreg, and with little waste generated from the process. In a previous investigation into the use of biocomposites for electric bus seats and backs, three different material systems (hemp, flax, and pure cellulosic fibers, each paired with a high-bio-content epoxy) and two manufacturing processes (wet layup followed by compression molding, vacuum-assisted resin transfer molding) were investigated, but neither process proved to be viable. In this paper, a relatively obscure process called Wet Compression Molding (WCM) is considered for economical production of the biocomposite bus seats using the same three material systems. Darcy’s law predictions of full impregnation time for a nominally 3.5 mm thick part using experimentally determined permeability values are all less than 2 s. Furthermore, prepreg is not used, and net-shape parts without excess resin show potential. Important design details of the WCM mold set, used in the manufacturing of flat test panels from each material system, that are generally not discussed in the literature include a high-pressure O-ring seal, and semi-permeable membranes covering injection pins and vacuum vents (evacuates trapped air) to prevent resin ingress. Biocomposite laminate specimens are fabricated using the mold set in a thermal press and a vacuum pump. Part characterization includes fiber volume fraction estimates and measurements of thickness, density, flexural modulus, and outer fiber maximum stress at failure. Due to its rapid impregnation with just enough resin, WCM should be considered for the economical manufacture of parts similar in shape and size to electric bus seats and backs. Full article

High-speed propulsion systems require supersonic inlets for operation; however, these inlets lose efficiency when the flight speed range is wide. Fixed-geometry inlets designed for particular conditions encounter operational difficulties when running at supercritical speeds, including shockwave instabilities and pressure reduction, limiting their operational speed and altitude range. Increasing inlet flexibility is a critical requirement for aerospace systems that need multivariable propulsion capabilities for civilian and military operations. This study, based on a supersonic inlet whose design flight Mach number is 2.2, determines its operational performance when operating at a speed of Mach 3 and then investigates modifications for expanding its operational boundaries with variable geometry components. This study used computational fluid dynamics in ANSYS Fluent with the k-ω SST turbulence model for airflow analysis. The methodology starts with Mach 2.2 baseline validation before proceeding to the Mach 3 investigation at different upward cowl-lip deflection angles ranging from 5° to 16°. This study conducted tests with a bleed slot and a 6 mm semi-conical bump to practically diminish unstart occurrences and treatment of shock–boundary-layer interactions. The results showed that a lip deflection angle of 15° upward delivers maximum operational efficiency on Mach 3 in terms of compression efficiency, flow deceleration, and flow uniformity at the inlet exit, as it generates an exit Mach number of 1.9, identical to that of the unmodified baseline operating at Mach 2.2, while a 5° deflection upward has shown the best values for total pressure recovery. Bleed slot implementation with the bump shape decreased unstart effects at a backpressure 30 times bigger than ambient pressure and produced stable flow despite a total pressure recovery drop of 8.5%. At Mach 3, with 15 km altitude, these modifications allow the system to operate with similar effectiveness as the baseline design at lower speeds. This study introduces a method for modifying a fixed-geometry inlet and extending its limitations, offering a pathway for adaptable supersonic inlets. The findings contribute to propulsion systems design by introducing a simple method for applying geometrical variations with less mechanical complexity compared to traditional variable geometry inlets. They change the entire throat area, supporting the design of supersonic vehicles and sustainable supersonic travel. Full article

Background: Sleep plays a crucial role in the health of older adults, and its quality is influenced by multiple physiological and functional factors. However, the relationship between sleep quality and physical fitness, body composition, and metabolic markers remains unclear. This exploratory study aimed to investigate the associations between sleep quality and physical, metabolic, and body composition variables in older adults, and to evaluate the preliminary performance of a logistic regression model in classifying sleep quality. Methods: A total of 32 subjects participated in this study, with a mean age of 69. The resting arterial pressure (systolic and diastolic), resting heart rate, anthropometrics (high waist girth), body composition (by bioimpedance), and physical fitness (Functional Fitness Test) and sleep quality (Pitsburg sleep-quality index) were evaluated. Group comparisons, associative analysis and logistic regression with 5-fold stratified cross-validation was used to classify sleep quality based on selected non-sleep-related predictors. Results: Individuals with good sleep quality showed significantly better back stretch (t = 2.592; p = 0.015; η² = 0.239), lower limb strength (5TSTS; t = 2.564; p = 0.016; η² = 0.476), and longer total sleep time (t = 6.882; p < 0.001; η² = 0.675). Exploratory correlations showed that poor sleep quality was moderately associated with reduced lower-limb strength and mobility. The logistic regression model including 5TSTS and TUG achieved a mean accuracy of 0.76 ± 0.15, precision of 0.79 ± 0.18, recall of 0.83 ± 0.21, and AUC of 0.74 ± 0.16 across cross-validation folds. Conclusions: These preliminary findings suggest that physical fitness and clinical variables significantly influence sleep quality in older adults. Sleep-quality-dependent patterns suggest that interventions to improve lower limb strength may promote better sleep outcomes. Full article

Pan-connected interlayers are widely present in oil reservoirs, forming flow channels at different positions. However, conventional profile control agents struggle to plug deep interlayer channels in reservoirs, limiting the swept volume of injected water. Additionally, a clear methodology for physically simulating pan-connected reservoirs with interlayer channels and calculating interchannel flow rates remains lacking. In this study, a physical model of pan-connected interlayer reservoirs was constructed to carry out deformable gel particles (DGPs) plugging experiments on interlayer channels. A mass conservation-based flow rate calculation method for interlayer channels with iterative solution was proposed, revealing the variation law of interlayer channel flow rates during DGP injection and subsequent water flooding. Finally, oil displacement and DGP profile control experiments in pan-connected interlayer reservoirs were conducted. The study shows that during DGP injection, injected water enters the potential layer through interlayer channels in the middle and front of the water-channeling layer and bypasses back to the water-channeling layer through channels near the production well. With the increase in DGP injection volume, the flow rate of each channel increases. During subsequent water flooding, DGP breakage leads to a rapid decline in its along-path plugging capability, so water bypasses back to the water-channeling layer from the potential layer through all interlayer channels. As the DGP injection volume increases, the flow rate of each channel decreases. Large-volume DGPs can regulate interlayer channeling reservoirs in the high water cut stage. Its effectiveness mechanism involves particle migration increasing the interlayer pressure difference, which drives injected water to sweep from the water-channeling layer to the potential layer through interlayer channels, improving oil recovery by 19.74%. The flow characteristics of interlayer channels during DGP injection play a positive role in oil displacement, so the oil recovery degree in this process is greater than that in the subsequent water flooding stage under each injection volume condition. The core objective of this study is to investigate the plugging mechanism of DGPs in pan-connected interlayer channels of high-water-cut reservoirs, establish a method to quantify interlayer flow rates, and reveal how DGPs regulate flow redistribution to enhance oil recovery. Full article

Background: This study aimed to optimize low-intensity extracorporeal shockwave therapy (Li-ESWT) for the treatment of penile indications through the addition of a secondary reflector. The therapeutic potential of Li-ESWT is well-established, but its efficiency is limited by uncontrolled wave propagation and reflection resulting in regions of increased tensile pressures. The objective is to manage and reduce high tensile pressure and enhance treatment efficacy by reflecting applied shockwaves back into the treatment zone using a novel reflector design. Methods: A comprehensive investigation, including numerical modeling and phantom measurements, exploring a range of improvements to traditional shockwave application by reflecting applied therapeutic shockwaves back into the treatment zone. Computational optimization was employed to identify the most suitable secondary reflector shape for potential future clinical use. Subsequent hydrophone phantom reference measurements were extended to volumetric fields using 3D simulations. Results: Traditional treatment resulted in high tensile pressures in the treatment zone, which was mitigated by introducing an impedance-matched layer (IML) while preserving the initial shockwave’s therapeutic function. The addition of the secondary reflector enabled controlled refocusing of the therapeutic shockwave back into the initial focal zone, thus either increasing the treatment volume or achieving a rapid secondary application. Choice of the reflector’s impedance allowed for the secondary refocusing of either a tensile or positive pressure wave. Conclusions: The combined modifications of employing an IML and secondary reflector eliminate uncontrolled tensile waves and reflections, provide better control over consecutive reflections, and enable repeated shockwave signals with a single applicator shot, potentially reducing the number of required shots per session. Full article