Search Results (1,573)

Flexible pressure sensors with porous structures are essential for wearable electronics and robotic perception. However, traditional porous flexible sensors suffer from poor stability and long recovery times. To address these challenges, a strategy integrating bionic architectures inspired by the rigid–flexible coupling structure of Bambusa textilis and the micro-protrusion structure of Salvia plebeia R.Br. is proposed. An aluminum sheet serves as the support layer, and the sensing layer is prepared through mold replication, material impregnation, and layer-by-layer assembly, offering a simple and scalable fabrication route. The sensor exhibits a broad effective pressure range of 0–31.5 kPa, with a minimum resolvable force of 0.2 N, and within its operating range (0–23.5 kPa), the relationship between resistance and pressure exhibits a trend that can be fitted to a quadratic term, with a coefficient of determination of 0.9986. It achieves a minimum response time of 350 ms and maintains stable signals under dynamic loading at different frequencies, indicating reliable detection of low-frequency weak pressures. After 5000 loading–unloading cycles, the device shows no obvious performance degradation. When mounted on a robotic foot, the sensor successfully distinguishes land, sponge, sand, and pebbles surfaces, demonstrating its potential for intelligent environmental perception. Full article

This study combines experimental conditioning and numerical simulations to evaluate water-induced degradation of swimming-goggle gaskets and their mechanical response under representative loading conditions. Two gasket geometries were modeled, with the flatter profile serving as a reference and the more anatomically representative variant analyzed using finite-element analysis for neoprene, silicone, and SEBS materials of different Shore A hardness under prescribed periorbital pressure distributions. Commercial gaskets were conditioned by static immersion in chlorinated, distilled, and saline water for 20, 30, and 40 days, followed by measurements of Shore A hardness, breaking force, and elongation at break. The numerical results showed that gasket geometry substantially influences the predicted deformation patterns relevant to facial conformability, despite similar overall deformation magnitudes. Prolonged water exposure caused considerable material degradation. The breaking force decreases by approximately 48% after 20 days and by about 50% after 40 days of conditioning, irrespective of the environment. Elongation at break changed by approximately 3–4% in chlorinated and distilled water, whereas saline water caused reductions of approximately 11% after 20 days and 36% after 40 days. Additionally, the hardness of the material drops by about 10–13% after 20 days and subsequently remains almost constant. In the adopted cyclic loading–recovery simulation, silicone exhibited substantially lower residual deformation than SEBS. Overall, the results demonstrate the importance of material selection and geometry optimization and provide a comparative basis for further studies combining environmental conditioning with experimentally calibrated numerical models. Full article

Food waste digestate is a high-moisture organic residue that requires effective stabilization before resource recovery or land application. This engineering-scale study compared high aeration (HA, 0.30 L·min⁻¹·kg⁻¹ dry matter), low aeration (LA, 0.15 L·min⁻¹·kg⁻¹ dry matter), and turning without forced bottom aeration (TG) during a 30-day food waste digestate–corn straw co-composting experiment. One engineering-scale pile was operated for each treatment. Physicochemical trajectories, bacterial succession, predicted functional potential, and microbial co-occurrence patterns were evaluated. All treatments rapidly entered the thermophilic phase. HA reached the highest temperature (63.70 °C) and remained above 55 °C for 340.8 h, but it also had the lowest final moisture reading (18.62%). LA achieved the greatest organic matter (OM) reduction (17.47%), compared with 13.47% in HA and 7.44% in TG, while retaining more moisture than HA at day 30. Bacillota became dominant in all treatments, although the intensity of thermophilic filtering and the pattern of late-stage succession differed among treatments. Functional predictions indicated the highest late-stage ureolysis potential in LA, whereas TG showed greater predicted representation of several nitrogen-transformation-related groups and the densest co-occurrence network. These findings suggest that engineering-scale composting performance depends on the balance among oxygen supply, heat accumulation, moisture conservation, and microbial organization rather than on thermophilic intensity alone. Under the tested conditions, LA provided the most favorable balance, particularly in terms of OM reduction and moisture retention. Full article

Carbon dioxide water-alternating-gas (CO₂-WAG) flooding simultaneously enables carbon emission mitigation, improved oil displacement efficiency, and expanded gas sweep coverage. Nevertheless, the field performance of this technology remains significantly constrained by gravity override effects, especially in ultra-thick oil reservoirs. In this work, a synthetic heterogeneous dipping mechanistic reservoir model is constructed. Using a quantitative metric for gravity override index in WAG processes, the variation patterns of gravity override under various operational factors are systematically analyzed. Furthermore, the eXtreme Gradient Boosting (XGBoost) machine learning algorithm is employed to conduct feature importance analysis of the controlling factors, identifying parameters with the most substantial impacts. The results indicate that well spacing, oil production rate, WAG injection strategy, and WAG slug duration all exert pronounced effects on both gravity override index and oil recovery factor. Gravity override is confirmed as the dominant factor governing the production performance of WAG flooding in ultra-thick reservoirs. In addition, an optimal combination of operational parameters exists that counterbalances the adverse effects of gravitational and viscous forces, thereby maximizing gas sweep efficiency, delaying gas breakthrough, and enhancing oil recovery. This study provides valuable insights and technical guidance for gas channeling mitigation, vertical gas sweep improvement, and efficient development of analogous ultra-thick reservoirs. Full article

Micro curved-surface parts are widely used in the aerospace, defense, biomedical, and automotive industries, and their growing adoption imposes increasingly stringent performance requirements. Five-axis micro-milling can achieve precision machining of parts with complex shapes. In the micro-milling process, the cutting force is a critical parameter, as it is the main factor causing machining deformation, vibration, and tool wear. Therefore, this study develops a prediction model for five-axis micro-milling forces in the machining of micro complex curved-surface parts. First, four coordinate systems were established for the five-axis milling process, and the transformation relationships among them were derived. A cutter–workpiece engagement (CWE) extraction method based on solid modeling was also introduced. Then, an instantaneous undeformed chip thickness (IUCT) model was established, taking into account tool runout, elastic recovery of the machined surface, minimum chip thickness, and the local radius of the micro ball-end mill. On this basis, a five-axis micro-milling force prediction model was developed. Finally, five-axis micro-milling experiments were conducted on a micro-impeller and a micro-spherical part, and the cutting forces at different cutter location (CL) points were measured. For the micro-impeller blade, the average percentage errors in the X, Y, and Z directions at all selected CL points were below 11.2%; for the micro-spherical part, the corresponding errors were below 14.4%. These results show good agreement between the predicted and measured values, verifying the effectiveness of the proposed model. Full article

Dynamic Movement Primitives (DMPs) are widely used for robot skill reproduction from demonstrations, but pose trajectory reproduction for continuous manipulation tasks remains challenging because translational and rotational motions must be represented consistently while maintaining accuracy, disturbance recovery, and terminal smoothness. Existing screw-displacement pose DMPs provide a geometrically consistent formulation on SE(3); however, their isotropic fixed-gain feedback limits direction-dependent correction, and deterministic forcing terms do not provide an explicit estimate of prediction reliability, which may cause over-shaping and high terminal jerk. This paper proposes a direction-adaptive and uncertainty-weighted pose DMP framework for robot skill reproduction from pose trajectories obtained from demonstrations. A Riemannian Motion Policy (RMP)-inspired direction-adaptive feedback mechanism is introduced to adjust recovery and damping according to the current pose error directions and magnitudes, improving trajectory-level correction and disturbance recovery. In addition, a Sparse Spectrum Gaussian Process (SSGP) is used to model the forcing term probabilistically, and its predictive variance is combined with a phase-dependent gate to attenuate low-confidence forcing contributions, particularly near the terminal phase. Simulation studies on RoboMimic trajectories show that the RMP-inspired feedback primarily improves pose reproduction accuracy and disturbance recovery, whereas the SSGP-based weighting substantially reduces terminal translational and rotational jerk, with a slight accuracy compromise relative to RMP-DMP. A papermaking robot case study further demonstrates the deployment feasibility of the generated pose trajectories on a real continuous-operation platform. Full article

Background: Large surface area burn injuries compromise skin integrity and are associated with significant morbidity and mortality. Skin autografts are essential for wound healing but are limited in patients with extensive burns due to insufficient donor site availability, resulting in delays in wound coverage. Cultured epidermal autograft (CEA) provides burn wound coverage in patients with extremely limited donor sites, but its success is limited by fragility, lack of basement membrane–anchoring cells, and susceptibility to shear and pressure, particularly over the lower extremities. Methods: We present two adult patients with total body surface area burns greater than 80% who underwent treatment with CEA and external fixation of the lower extremities. Burn wounds were excised and temporarily covered with allograft skin prior to CEA application. A triplanar external fixation device was used to suspend the lower extremities off the bed surface to minimize shear and pressure on CEA-treated areas. Results: Following application, both patients demonstrated near-perfect graft adherence, with wounds healing within four weeks and durable epithelial coverage at 12 weeks. No complications related to external fixation were observed. The use of external fixation to suspend the lower extremities reduced shear forces and improved CEA take. This approach provided stable wound healing, facilitated wound care, and demonstrated excellent functional recovery. Conclusions: External fixation may serve as a valuable adjunct in improving outcomes of CEA in patients with extensive burn injuries involving the lower extremities. Full article

Ensuring continuous load supply under N-1 contingencies poses a significant challenge for active distribution networks. Traditional fault recovery relies on mechanical tie switches for network reconfiguration; however, such rigid interconnections often fail due to severe terminal voltage drops during long-distance load transfers, leading to forced load shedding. To address this, this paper proposes an optimal planning framework for Electric Energy Routers (EERs) to secure load supply, aiming to maximize load preservation within investment budget constraints. First, a bi-level robust optimization model is constructed: the upper level determines the optimal EER configuration to minimize load shedding in the worst-case N-1 scenarios, while the lower level evaluates the optimal restoration strategies via mixed-integer second-order cone programming. To handle the inherent complexity of discrete–continuous variable coupling and the computational burden of the bi-level structure, a novel topological manifold evolution algorithm based on Wasserstein geometric flow is developed. By embedding the electrical topology into a sensitivity-driven Riemannian metric field, the algorithm effectively enhances global optimization capabilities. Case studies on the IEEE 33-node system demonstrate that the integration of EERs facilitates a transition from rigid to flexible interconnection, circumventing power transfer bottlenecks caused by low voltage through controllable power flow. Compared with baseline schemes, the optimal EER scheme reduces load shedding in the worst-case scenario by 60.3%, providing a robust and economical solution for high-resilience distribution network planning. Full article

Self-centering rocking systems redistribute seismic demand as contact conditions at structural interfaces change during excitation. Conventional peak-response measures, global-response model calibration, and system-identification summaries can obscure the transient redistribution among diaphragms, wall couplings, and restoring components. This study addresses that gap with a phase-resolved analysis of heterogeneous measurements from fourteen full-scale shake-table tests of a two-story mass-timber building with post-tensioned cross-laminated timber rocking walls. Acceleration, strain, post-tensioning-force, and wall-uplift records were aligned, screened, and placed on a common analysis grid; uplift-defined operating phases were then evaluated using normalized subsystem activity, entropy, effective participation, conditional directed predictability, and dimensional force-uplift work. Median effective participation increased from 2.7 subsystems in the closed state to approximately 5.8 during rocking. The median closed-to-rocking Jensen–Shannon divergence was 0.195, the median post-recontact recovery index was 0.813, and restoring work was 4.6–10.7% greater on the south wall line. Rocking-phase floor-diaphragm activity co-varied with south restoring work (Spearman ρ = 0.873, p < 0.001). The new scientific result is that wall uplift reorganizes the composition of measured subsystem activity rather than simply scaling a fixed response pattern. The proposed indicators therefore provide complementary, phase-conditioned targets for experimental comparison and nonlinear-model validation, while remaining distinct from equilibrium force fractions, damage indices, or unrestricted causal measures. Full article

Background/Objectives: Decreases in hamstring isometric strength have been observed post-competition, but research has currently focused only on soccer players. Therefore, the purpose of the present study was to observe if acute reductions in isometric hamstring force production in elite male lacrosse players occur post-match. Methods: Peak isometric force measurements were collected from ten male outfielders from the British Lacrosse squad (24.6 ± 2.3 years, 1.80 ± 0.08 m, 86.3 ± 4.5 kg) using force plates. The 90:90 isometric assessment was conducted before and after a single sixes lacrosse match to observe changes in hamstring force production. Bayesian paired sample’s t-test and Hedge’s g effect sizes were used to determine the level of evidence and magnitude of fatigue due to sixes lacrosse match play. Results: A strong level of evidence with moderate–large effect sizes for reduced peak force was observed (Bayes factor [BF] = 11.36–12.55; g = 1.18–1.20). Stronger levels of evidence and large magnitude reductions were observed for force at 100 and 200 ms (BF = 18.92–61.85; g = 1.55–1.63). Conclusions: Sixes lacrosse match play results in localized hamstring fatigue, which could explain the high frequency of hamstring strain injuries within elite men’s sixes lacrosse players. The current sixes competition format includes multiple fixtures on a single day; therefore, practitioners need to prioritize recovery. Full article

Anterior cruciate ligament (ACL) injuries represent one of the most common and disruptive conditions in sport. Effective return-to-play (RTP) monitoring requires multidimensional approaches capturing physical, psychological, and sport-specific components rather than reliance on isolated benchmarks. This study aimed to longitudinally examine the RTP process of a female varsity basketball athlete following ACL reconstruction, using a framework integrating physical performance (capacity), biomechanical sport-specific (capability), and psychological (confidence) components relative to pre-injury benchmarks. Data collection included countermovement jump testing with force plates, on-court inertial measurement unit (IMU) monitoring of limb-loading, and psychological questionnaires, analyzed relative to the athlete’s pre-injury baseline, with post-surgical change interpreted against that individualized reference using minimal detectable change thresholds. Pre-injury monitoring indicated stable movement profiles with minor fluctuations. Following ACL reconstruction, jump height recovered within seven weeks of RTP initiation, but notable inter-limb asymmetries persisted in force plate and IMU measures despite high confidence scores. Symmetry improved over time, yet variability in on-court loading remained after clinical clearance. These findings highlight the value of integrated, multidimensional monitoring to detect residual deficits that may be overlooked by traditional outcome-based assessments. This study demonstrates that integrating athlete-specific biomechanical, psychological, and sport-specific assessments relative to pre-injury baselines can support RTP decision-making to enhance individualized recovery trajectories in female athletes. Full article

Tail rotor failure represents a critical emergency in helicopter flight operations. Conventional recovery mandates an immediate engine shutdown and transition to autorotation, significantly compromising both mission survivability and operational flexibility. To achieve stable powered flight, this paper establishes a yaw stability strategy integrating vertical tail side-force control with active main rotor torque suppression. This strategy employs controlled sideslip to generate a yaw-restoring moment from the vertical tail and an increased descent rate to reduce rotor power requirement. These two effects act in concert to counteract the rotor torque. Trim analysis of a representative helicopter in a tail rotor failure condition validates the strategy. Two yaw control architectures are developed for the failure operation: (1) a cascade loop comprising yaw angle, yaw rate, lateral velocity, and roll angle, and (2) the latter omitting lateral velocity. Comparative simulations demonstrate that although Loop (1) yields slower yaw convergence than Loop (2), it delivers enhanced stability. Furthermore, an emergency control trajectory tailored for moderate forward velocity is proposed. The trajectory initiates with a controlled descent-rate increase to arrest yaw divergence. The forward velocity is then augmented to mitigate sideslip, and the descent rate is gradually reduced, ensuring adequate altitude clearance over the landing zone. This study provides a strategy for enabling powered flight under tail rotor failure conditions. Full article

Hydrothermal carbonization (HTC) of digested dairy manure produces hydrochar and a nitrogen-rich post-liquid. This study evaluated a submerged tubular expanded polytetrafluoroethylene (ePTFE) gas-permeable membrane (GPM) system for ammonia recovery from post-HTC liquid derived from digested dairy manure, focusing on the effects of feed temperature, acid circulation rate, and feed volume-to-membrane surface area ratio (FV/MS). Compared with filtered digested manure, the post-HTC liquid had a similar total ammoniacal nitrogen (TAN) concentration (1151 vs. 1164 mg N L⁻¹) but a slightly higher pH (8.38 vs. 7.94), which favored ammonia transfer. Increasing feed temperature from 20 to 60 °C raised 24 h TAN recovery from 63.5% to 99.6% and average TAN transfer flux from 11.1 to 17.7 g m⁻² d⁻¹, although it also increased water vapor crossover and diluted the acid trapping solution. Increasing acid circulation from 10 to 30 mL min⁻¹ improved 48 h TAN recovery from 85.2% to 94.0%, while a further increase to 50 mL min⁻¹ produced only a small additional gain. In contrast, elevating FV/MS from 0.015 to 0.045 m³ m⁻² reduced 48 h TAN recovery from 94.0% to 59.6% while increasing average TAN transfer flux from 8.2 to 16.2 g m⁻² d⁻¹ because larger feed volumes sustained the concentration driving force for a longer period. Nitrogen mass balance showed that more than 94–99% of the initial TAN was accounted under most conditions, with only a small fraction lost to volatilization. Full article

This paper presents an experimental study of vibration energy recovery from a horizontal seat suspension system in which a brushless direct current (BLDC) motor is used as both an active force actuator and a controllable regenerative braking element. The novelty of the study lies in the experimental validation of an active/regenerative switching strategy for a horizontal seat suspension and in the quantitative comparison of passive, fully active and regenerative operating modes under random vibration excitation and different inertial loads. The proposed system was evaluated using transmissibility functions, seat effective amplitude transmissibility (SEAT) factors, suspension travel, and electrical quantities generated in the braking branch. The results show that the fully active mode provides the highest vibration attenuation, whereas the regenerative mode reduces the SEAT factor compared with the passive suspension while simultaneously producing measurable electrical power in the braking resistor network. The maximum measured electrical power in the braking branch reached 7.692 W for the WN3 excitation signal and an 80 kg load. The obtained results confirm the practical potential of regenerative braking for potentially reducing the net energy demand of active seat suspension systems, while also highlighting the trade-off between vibration attenuation, suspension travel, and recoverable electrical power. Full article

To improve braking energy recovery in pure electric vehicles while maintaining a reasonable braking-force distribution, this study proposes a regenerative braking strategy based on a grey wolf optimizer (GWO)-optimized fuzzy control. A single-motor front-wheel-drive pure electric vehicle is modelled in terms of vehicle longitudinal dynamics, motor characteristics, and battery state of charge (SOC). A front–rear braking-force distribution strategy is developed based on the ideal braking-force distribution I-curve and ECE regulation constraints. A Mamdani fuzzy controller is then designed with braking intensity z and battery SOC as inputs and the front-axle regenerative braking-force distribution coefficient k as the output, enabling coordinated allocation between front-axle regenerative braking and mechanical braking. To reduce the dependence of fuzzy rules on expert experience, the GWO is used to optimize 25 fuzzy rules, and the proposed strategy is verified in MATLAB R2023b under a typical urban driving cycle. The results show that all strategies satisfy the braking demand. Compared with the unoptimized fuzzy control strategy, the optimized strategy reduces SOC consumption by 5.15% and increases recovered braking energy by 59.56%, indicating improved regenerative braking performance. Full article