Search Results (3,781)

The surface quality and production efficiency of continuous-casting steel slabs are predominantly determined by the performance of the mold. To address slab corner defects and enhance operational stability, this study systematically optimized two key components: the broad-face clamping mechanism and the narrow-face copper plate. A disk spring–hydraulic composite clamping mechanism was designed and subjected to mechanical analysis to ensure sufficient and reliable clamping force under high-load casting conditions. Meanwhile, based on the principle of solidification shrinkage, an external chamfer structure for the narrow-face copper plate was proposed to improve heat transfer uniformity at the slab corner. Engineering design calculations and practical application in an export-oriented wide-and-heavy slab continuous-casting project (specification: 250 mm × 2500 mm) demonstrated that the optimized clamping mechanism provides enhanced structural rigidity, while the new narrow-face copper plate effectively mitigates corner cracks and reduces wear. This integrated design approach significantly improves slab surface quality and extends component service life, yielding substantial economic benefits. Full article

Low-frequency acoustic fields—common in ventilation ducts, building façades, and industrial infrastructure—remain an underutilized source for ambient energy harvesting, particularly in humid environments where conventional contact-based or mechanically resonant harvesters may degrade over time. This study introduces a theoretical framework for converting acoustic pressure oscillations into electrical power through acoustic–electrokinetic coupling and proposes the Acoustic Baroionic Harvester (ABH) as a solid-state concept combining a Helmholtz resonator with a charged nanoporous membrane. The model is derived from coupled electrokinetic and fluid-mechanical governing relations, leading to closed-form expressions for the open-circuit voltage, internal electrokinetic resistance, and maximum deliverable power as functions of membrane surface charge, electrolyte properties, pore geometry, and resonance-induced pressure amplification. Numerical simulations are performed to validate the analytical scaling laws and to determine operating regimes that maximize power transfer to an external load. Under representative low-frequency acoustic excitation, the ABH predicts open-circuit voltages on the order of tens of millivolts and maximum power densities in the sub-microwatt-per-square-centimeter range. A compact CAD conceptual design tuned to approximately 120 Hz with a moderate resonance quality factor supports the feasibility of practical integration. The proposed approach enables micro-power generation from persistent low-frequency acoustic sources and provides a physically grounded pathway for self-powered sensing applications in built and industrial environments. Full article

This study investigates the quasi-static and fatigue strength of copper-brazed 316L stainless steel. Quasi-static and fatigue tests were conducted at room temperature (20 °C) using a Zwick/Roell Vibrophore 100 testing machine and specially designed copper-brazed specimens. Two types of specimens were prepared—tensile and shear specimens—to obtain the stress–strain relationships (σ–ε and τ–ε) and the fatigue life (S–N) curves. Based on the experimental results, the quasi-static and fatigue strengths of the copper-brazed joints under external tensile and shear loading were evaluated. The fatigue tests reveal that the shear fatigue strength is significantly lower than the tensile fatigue strength. Furthermore, a comprehensive investigation was conducted, focusing on the metallographic characterisation of the brazed joint and fractographic analyses of fracture surfaces obtained under quasi-static and fatigue loading, with particular emphasis on the shear strength of the investigated brazed joint. The experimental results obtained may be crucial for designing engineering structures (e.g., plate heat exchangers), where copper-brazed joints are the weakest members of the structure. Full article

Urban curbside loading and unloading zones are increasingly affected by competing non-logistics uses, such as outdoor terraces or resident parking, leading to reductions in effective curbside length. These design decisions can significantly alter service capacity and generate environmental externalities in urban freight operations that are rarely quantified. This study introduces the Factor of Occupancy (F_o) as a space–time design indicator for curbside unloading zones, defined as the product of effective curbside length and the maximum authorised dwell time. Using direct observational data from an urban block in Zaragoza (Spain), the analysis focuses on a loading and unloading zone whose effective length was reduced by approximately 6 m due to the installation of a restaurant terrace. Two curbside configurations are compared: a reduced configuration (8 m) and a restored configuration (14 m), keeping demand and temporal constraints constant. F_o is integrated into a loss-based queueing model (M/M/1/1) to estimate blocking probabilities and the number of served and rejected freight operations. To capture the environmental implications of curbside capacity loss, the paper proposes the Hidden Carbon Emissions (HCE) indicator, which quantifies the additional CO₂ emissions generated by rejected vehicles through block recirculation and idling during illegal occupancy, based on observed behaviour and publicly available emission factors. The results show that restoring curbside length substantially increases effective service capacity and reduces rejected vehicles, leading to a marked decrease in hidden CO₂ emissions per operation. The findings highlight that minor curbside design decisions can produce measurable impacts on both urban freight efficiency and environmental performance. Full article

The presented study investigates the structural behavior of reinforced concrete (RC) columns strengthened using an external steel cage and an additional concrete infill layer. An experimental program was conducted on short RC columns subjected to axial compressive force. A total of eleven columns were tested, including five plain RC and six strengthened specimens. The objective of the research was to evaluate the load-bearing capacity, failure mechanisms, and composite interaction between the steel cage, the infill concrete, and the original RC column. Two different distances between battens were considered in order to evaluate whether the number of batten plates significantly influences the efficiency of strengthening. The experimental results show that the proposed strengthening technique leads to an increase in axial capacity compared to unstrengthened specimens. Also, the variation in batten spacing within the investigated range has a negligible effect on the ultimate load. Failure was governed by cracking and bond deterioration in the infill layer, followed by progressive loss of composite action. The results indicate that the strengthening performance is primarily controlled by the properties of the infill concrete and the confinement mechanism, rather than by the spacing of the steel battens. The application of EN 1994-1-1 and EN 1998-3 in predicting the axial capacity of strengthened columns showed a good relation between experimental results and code calculations. Full article

Coaches in professional football need to estimate how many minutes a player can tolerate in a match before relevant fatigue occurs. This study aimed to develop a framework to translate monitoring information into individualised, minute-based fatigue thresholds. Over four seasons in an elite club, external load (total distance, high-speed running, mechanical work) and heart rate were collected in training. Machine-learning-derived fitness and fatigue indices were computed and combined with 7- and 28-day load variables in a Random Forest regression model predicting match minutes. The trained model was then used to simulate four fatigue conditions by fixing the match-day fatigue index (z-FA_match = 0, −1, −2, −3). In an independent test season, the model showed a mean absolute error of 22.5 min and R² = 0.17 for playing time prediction, with z-FA_match as the most influential predictor. Simulated fatigue thresholds occurred in an ordered way (0 = 57.1, −1 = 64.9, −2 = 84.8, −3 = 84.4) and differed across season period, playing position, overall seasonal minutes, and return-to-play status. Integrating external load with fitness and fatigue indices via machine learning can provide individualised estimates of when players are likely to reach fatigue states, supporting decisions on selection, substitutions, and return-to-play management. Full article

Background: Water inertia load training using equipment such as water vests provides unstable resistance that enhances trunk muscle activation. However, practical methods for prescribing exercise intensity without expensive electromyography (EMG) equipment remain limited. This pilot study aimed to develop prediction models for estimating trunk muscle activation using rating of perceived exertion (RPE) during water inertia load exercises. Methods: Seventeen healthy adults (20.45 ± 2.02 years) performed lateral trunk flexion exercises wearing a water vest at five progressive loads (8–16 kg in 2 kg increments). Surface EMG was recorded from four trunk muscles (rectus abdominis, external oblique, internal oblique, erector spinae) and normalized to maximal voluntary isometric contraction (%MVIC). Rating of perceived exertion (RPE) was assessed using the Borg CR-10 scale. Load-dependent changes in muscle activation were examined using repeated-measures ANOVA, and relationships between RPE and EMG were analyzed using regression and linear mixed-effects models. Results: All trunk muscles showed significant increases in activation with increasing load (all p < 0.001, ηp² = 0.381). RPE demonstrated significant positive correlations with all abdominal muscles (r = 0.37–0.46, p < 0.001). Simple regression analyses indicated predictive accuracy (R² = 0.267), representing a 29% increase compared with the strongest individual muscle model. Linear mixed-effects modeling confirmed RPE as a significant predictor after accounting for inter-individual variability. Conclusions: This pilot study provides preliminary evidence that RPE can be used to estimate trunk muscle activation during water inertia load exercise. The proposed composite activation index enhances prescription when EMG measurement is not feasible. Full article

Utah Lake is a large, shallow, highly eutrophic system that is naturally rich in phosphorus (P) and is prone to harmful algal blooms (HABs). While ongoing regulatory efforts often focus on reducing external anthropogenic P loads, particularly from wastewater treatment plants (WWTPs), accumulating evidence suggests that internal sediment P cycling and atmospheric deposition (AD) govern water column P concentrations and are the primary drivers of the lake’s trophic state. We synthesize the existing literature and present new data to demonstrate that (1) the lake’s P-rich, geologic sediments buffer the water column, rendering it largely insensitive to major changes in anthropogenic P inputs due to sorption dynamics, and (2) AD alone provides sufficient P to sustain the lake’s eutrophic status. New analyses on previous AD measurements combined with new active dust sampling data reinforce these conclusions by demonstrating no attenuation of dust deposition to the interior of Utah Lake. We conclude that efforts focused solely on limiting P inputs will have minimal impact on lowering the water column P concentration or improving the lake’s water quality, and that alternative physical and biological restoration methods, such as carp removal and shoreline restoration, are likely to be far more effective. Full article

This research aims to establish design guidelines for a cantilever triple-layer piezoelectric harvester (CTLPH) with tip mass and tip excitation, operating under resonance conditions. The guideline is derived by combining constitutive equations with Euler–Bernoulli beam theory to identify the effective parameters of the CTLPH and, subsequently, the storage voltage after rectification using a germanium diode bridge. The analysis shows that excitation frequency, piezoelectric coefficients, geometrical dimensions, and the mechanical properties of the layers all significantly influence CTLPH performance. The effects of storage capacitance and excitation frequency were experimentally validated through the design, fabrication, and testing of a prototype. Furthermore, the LTC3588 energy storage module was employed to store the generated charge from resonance motion. An advanced non-contact optical method was employed to determine the bending stiffness of the CTLPH. The output power after the energy storage module was measured across a range of resistive loads at frequencies near the resonance condition (f = 65 Hz). Results demonstrate that both excitation frequency and external resistance affect the maximum harvested power. The developed CTLPH achieved an optimum output power of 46.18 ± 0.98 μW at an external resistance of 3 kΩ, which is sufficient to supply micropower sensors. Full article

This paper proposes an integrated finite-time relative-threshold event-triggered control (FTRTETC) framework for unmanned surface vehicle (USV) formations under input saturation and unknown time-varying external disturbances. Firstly, a scheme of USV formation control based on signed graph theory is proposed. Next, a Gaussian error function is used to handle input saturation and simplify the backstepping design. Then, a finite-time formation controller is developed based on the active disturbance rejection control (ADRC) method with extended state observers (ESOs) and tracking differentiators (TDs). Also, a relative-threshold event-triggered mechanism is designed to reduce the frequency of control execution and communication load. By Lyapunov’s stability theory, the proposed controller is proven to achieve finite-time convergence, ensuring all closed-loop signals achieve global uniform ultimate boundedness (GUUB) and the system is without Zeno behaviour. Finally, numerical simulation examples are presented to validate the effectiveness and robustness of the proposed controller. Full article

Submarine cables are critical components for power transmission in offshore wind farms, making their condition monitoring paramount for ensuring operational reliability. Addressing unclear strain transfer and underdeveloped Brillouin optical time-domain reflectometry (BOTDR) sensing models for three-core fiber-optic composite submarine cables, this study investigated a 66 kV cable and clarified a BOTDR monitoring principle based on the three-layer mechanical structure. Using the external optical unit’s average Brillouin shift for temperature compensation, four characteristic parameters ($\Delta v_{\mathrm{y}}$, $\Delta v_{\mathrm{p}}$, $v_{\mathrm{m}}$, $v_{\mathrm{F}}$) were analyzed. The results show the optical unit’s tensile strain-induced Brillouin shift exhibits periodic distribution along the cable. The stable average peak $v_{\mathrm{F}}$ achieved a correlation coefficient of 0.98 with tensile load F_i. A dual-threshold sensing model was established: no shift response below F₀ = 90 kN (7.84% Rated Tensile Strength (RTS)); strong linear correlation between $v_{\mathrm{F}}$ and F_i beyond F_m = 110 kN (9.58% RTS) with a tensile sensitivity coefficient of 0.03788 MHz/kN. This study provides key BOTDR technical support for submarine cable tensile monitoring in complex marine environments. Full article

3 × 3 basketball is a high-intensity intermittent sport practiced by both professional and recreational athletes. However, the use of predefined absolute thresholds to quantify external load may overlook meaningful inter-individual differences in movement intensity. This study examined internal and external load demands during official 3 × 3 match play using individualized, performance-based load zones. Seventeen male players were monitored across 38 valid match observations during a two-day tournament. External load was collected via inertial measurement units, while internal load was assessed through continuous heart-rate monitoring. Raw triaxial accelerometer data were processed in Python to remove gravitational components and reconstruct speed–acceleration profiles, allowing identification of individual acceleration, deceleration, and jump events. Statistical analyses were conducted using linear mixed-effects models with Bonferroni-adjusted post hoc comparisons to evaluate differences between absolute and individualized zones. Players sustained high physiological strain, operating at approximately 85–90% of HRmax, and performed frequent high-intensity mechanical actions. Individualized acceleration, deceleration, and jump zones yielded a more even dispersion of events across low-, moderate-, and high-intensity categories. In contrast, predefined absolute thresholds classified over 90% of events as low intensity, masking meaningful variability. These findings highlight substantial inter-individual differences in 3 × 3 match demands and support the use of individualized load profiling for accurate monitoring, performance evaluation, and training prescription. Full article

To meet the requirements of high-efficiency thermal management without external power in long-distance and distributed multi-heat source scenarios, this paper proposes a dual compensation chamber multi-evaporator loop heat pipe system (DCCME-LHP). The system uses a capillary pump to provide capillary driving force, and through the step-by-step advancement of multiple condenser-evaporator combination, it achieves heat transfer and long-distance transportation among multi-heat sources. The experimental system investigates the effects of working fluid charge ratio, time interval, and heat load on the system’s hydrodynamic stability and heat transfer limit. The results show the optimal comprehensive performance of startup and steady state can be achieved with the charge ratio of 75% and a time interval of 8–10 min. The system operates stably under a total heat load of 270 W (90 W for the capillary pump and 60 W for each of the three evaporators). When the heat load of a single-stage evaporator rises to 70 W, the system enters the operation failure zone, and the steady-state temperature plateau jumps. This study provides a theoretical basis and experimental support for the design and stable operation strategy of long-distance multi-heat source thermal control systems. Full article

To mitigate the significant impact of system nonlinearities, time-varying parameters, and external load disturbances on the output force of hydraulic servo systems in active hydraulic suspensions for engineering vehicles, this study proposes a beetle swarm optimization (BSO)-optimized extended state observer (ESO)-based sliding mode control (SMC) strategy. A comprehensive mathematical model of the hydraulic servo system is established, and an ESO-based SMC controller is designed, taking into account the coupled effects of chamber pressure dynamics and external loads on the uncertain output force. The stability of the closed-loop system is rigorously analyzed and verified using Lyapunov stability theory. The effectiveness of the proposed control strategy is verified through both numerical simulations and experimental tests. For step inputs of 5000 N and 8000 N, overshoot is significantly reduced compared with the conventional proportional–integral–derivative control and the standard extended state observer-based sliding mode control, while the settling time is shortened by more than 65% in simulations and up to 75% in experiments. Under sinusoidal force excitations at frequencies of 0.5 Hz, 1 Hz, and 2 Hz, the maximum tracking error, mean error, and standard deviation of the tracking error are substantially reduced, with the maximum error reduction exceeding 90%. These results demonstrate that the proposed method achieves high-precision force tracking under external disturbances and pronounced system uncertainties, providing an effective solution for force control of hydraulic servo systems in active suspension applications for engineering vehicles. Full article

Hatching eggs possess multiple physical and chemical barriers that limit microbial invasion; however, the role of the eggshell membrane in shaping late-stage embryonic and early post-hatch gastrointestinal (GI) microbiota remains poorly understood. This study aimed to (i) validate a reproducible eggshell membrane extraction method, (ii) assess whether microbial loads differ between nest- and floor-laid eggs, (iii) examine relationships between eggshell membrane-associated microbiota and embryonic intestinal microbiota, and (iv) determine whether microbial blooms align with key stages of the hatching process. In a preliminary experiment using White Leghorn hatching eggs, no significant differences were observed in aerobic, anaerobic, or fungal membrane counts between nest- and floor-laid eggs. In a commercial hatchery study using Ross 708 broiler eggs, membrane and GI microbial populations were evaluated across days 18–20 of incubation, corresponding to pre-pipping, internal pipping, and external pipping/post-hatch stages. Significant, day-dependent shifts in microbial counts were observed, with strong interactions between sampling day and location (membrane vs. GI) for most bacterial groups. Enterococci and anaerobic bacteria were enriched in the GI tract prior to hatch, whereas aerobic, Gram-negative, and Staphylococcus populations were more abundant on membranes during late incubation. Post-hatch chicks exhibited markedly higher GI microbial loads compared to embryos, indicating rapid colonization during the hatch transition. Collectively, these findings demonstrate that the pipping and hatching process represents a critical window for microbial redistribution from eggshell membranes to the developing chick gut, highlighting the hatchery as a key control point for early-life microbial exposure and intervention strategies. Full article