Search Results (1,120)

To address the problems of increased bilateral synchronization error, accumulated beam attitude deviation, and degraded operating stability of a dual-motor-driven lifting beam under eccentric loading, this paper proposes a coordinated synchronization–attitude control method based on online eccentric-load estimation and dynamic differential allocation. First, a two-dimensional dynamic model incorporating overall vertical translation and small-angle beam rotation is established. On this basis, the control task is decomposed into trajectory tracking in the common channel and synchronization–attitude regulation in the differential channel. Second, an online equivalent eccentric-load moment estimator is introduced to extract the dominant eccentric-load effect through differential-channel residuals and first-order low-pass filtering. Then, a dynamic differential allocation mechanism jointly driven by the estimated moment and beam attitude is constructed to adaptively adjust the left–right driving-force difference while maintaining the total lifting force. Furthermore, synchronization-error feedback, attitude feedback, and eccentric-load compensation are unified in the differential control law. Finally, comparative simulations and experiments under step and preset eccentric-loading conditions show that, for an additional mass of 10 kg placed 0.45 m from the nominal beam center, the proposed method reduces the experimental tracking RMSE to 4.31 mm, limits the peak tilt angle to 0.64°, and reduces the steady-state synchronization error to 1.48 mm. These results demonstrate improved tracking accuracy, synchronization consistency, attitude stability, and adaptability to persistent eccentric loading. Full article

A tuned mass damper (TMD) is one of the dominant technologies for vibration control in offshore wind turbines (OWT). However, the variation in their vibration mitigation performance across a range of typical load cases throughout the full service life of wind turbines remains to be comprehensively assessed. This paper investigates the vibration mitigation patterns of TMDs on the dynamic responses of OWTs across five typical operational and extreme load cases, namely cut-in wind speed, rated power operation, cut-out wind speed, and two categories of extreme wind conditions. The results demonstrate that TMDs do not exert significant control effects across all load cases and response indicators. Their vibration mitigation effect on nacelle acceleration is the most stable and prominent, with optimal performance achieved under the cut-out wind speed shutdown load case, where the peak fore-aft vibration mitigation rate can reach 60.0%. However, the vibration mitigation rate of tower top displacement under normal operating load cases is significantly lower than that under shutdown conditions; the peak fore-aft displacement mitigation rate under the rated wind speed load case is merely 7.8%. The fore-aft foundation reaction forces achieve limited mitigation from TMD control, with a slight negative vibration mitigation effect even observed under extreme wind conditions. The effect of frequency detuning exhibits pronounced directional heterogeneity. For the side-to-side direction, −20% detuning reduces the mitigation rate from 45.0% to 29.2%, while for the fore-aft direction, +10% detuning increases it from 58.2% to 72.6% under rated operating conditions. Full article

The development of suspension systems for urban micro-mobility vehicles, such as bicycles and e-bikes, requires balancing effective road filtering with structural simplicity. Traditional solutions, such as telescopic forks and rear shock absorbers, face significant challenges related to weight, bulk, and mechanical complexity, which increase production and maintenance costs. The integration of in-wheel motors into wheel hubs further complicates the design by increasing unsprung mass and vertical vibrations, negatively affecting ride comfort. The In-Wheel Suspension (IWS) system offers an innovative solution by incorporating elastic and damping elements directly into the wheel rim, eliminating the need for frame modifications and reducing overall weight. This study proposes an integrated approach to optimising the internal geometries of IWS elastic elements, using structural analyses with LS-Dyna and dynamic simulations in the Simulink environment for comfort assessment. Results demonstrate that optimising the geometry of spokes and rims significantly reduces stiffness variations and self-induced vibrations, with enhancements in ride comfort and resistance to fatigue. The optimized IWS design minimises discomfort peaks at critical speeds and improves vibration attenuation. However, the high average stiffness limits filtering performance at speeds above 10 km/h. While IWS systems represent a promising alternative to traditional suspensions due to their advantages in weight reduction, compactness, and construction simplicity, further improvements—such as the use of composite materials and alternative geometries—are necessary to further increase comfort and to ensure structural resistance to variable loads. Full article

Skin breakdown occurs commonly within patients with lower-limb prostheses where the current clinical practice to diagnose skin breakdown is visual inspection by a clinician. Thermal imaging and optical coherence tomography angiography (OCT-A) have been proposed as early detection methods for skin breakdown and hold great promise. OCT-A is a noninvasive imaging modality that outputs a near-infrared optical signal and captures the reflective depth signal. The recorded transient behavior of the vessel area density (VAD), after repetitive dermal loading conditions, has been correlated to skin breakdown. Thermal imaging tracks the temperature profile of the skin surface after repetitive loading conditions and utilizes the temperature time-to-peak (TTP) as a metric of dermal health like VAD. Both methods are sensitive to imaging artifacts, and current resolutions are presented in this work, along with a discussion of the need to standardize data collection and advance image processing methods. Current approaches typically rely on thresholding that produces varying results based on user-selected limits followed by smoothing without any basis of the underlying physics. This review paper presents a need for a constitutive expression that captures the expected physics, thereby strengthening confidence in the use of either thermography or OCT-A, and enabling true clinical applications to aid patient health. Full article

This work characterizes oil film evolution and predicts the hydrostatic-to-hydrodynamic dominance transition in low-speed heavy-duty journal bearings under starved lubrication induced by insufficient inlet pressure, accounting for the thermo-viscous coupling effect. A thermo-viscous coupling model (TVCM) based on the Vogel equation is established and compared with the conventional constant viscosity model (CVM). Analyses are conducted with VG460, VG680, and VG1000 lubricants at rotational speeds of 10–50 rpm. Results show that the CVM systematically overestimates temperature rise and effective viscosity by neglecting the negative feedback among temperature rise, viscosity attenuation, and reduced heat generation, with deviations increasing with rotational speed and lubricant viscosity. Under insufficient oil supply, load-carrying capacity rises rapidly then stabilizes, reflecting the hydrostatic-to-hydrodynamic dominance transition. In the hydrodynamic-dominated stage, a dominance shift between hydrodynamic enhancement and thermal softening is identified: the peak load point marks the switching of dominant factors, and the corresponding critical speed decreases with rising lubricant viscosity. This transition is accompanied by a failure mode shift from global oil film breakdown to localized high-temperature adhesive wear and fatigue spalling. These findings provide a theoretical basis for formulating emergency speed limits and safe operation strategies for journal bearings under insufficient oil supply. Full article

Campylobacter jejuni and C. coli are leading causes of bacterial gastroenteritis worldwide, commonly linked to undercooked poultry. Within a One Health perspective, understanding their dissemination from farm-to-slaughterhouse is essential. This study aimed to detect Campylobacter spp. in intensively reared broiler chickens at critical points along the production chain and to assess antimicrobial resistance genes. Two production cycles, November to December 2024 and July to August 2025, were monitored weekly across three Portuguese poultry farms and a shared slaughterhouse. In total, 2164 samples were collected, including farm, transport, and slaughterhouse samples. Detection followed ISO 10272-1:2017 and 10272-2:2017 standards. Campylobacter prevalence peaked during weeks 3 and 4 on farms (9.4% cloacal, 23.5% litter). Transport crates showed contamination before/after loading (15.0%). At the slaughterhouse, contamination was low (8.3%) in process waters but high in neck skin samples (76.7%), with 15.2% exceeding the 1000 CFU/g limit (EU Regulation 2017/1495). Among 56 confirmed isolates, C. jejuni was most prevalent (46.4%), followed by C. coli (32.1%). The tetO gene was detected in most isolates (69.4%), while bla_OXA-61 was less frequent (30.6%). Findings highlight the need for integrated control strategies, including improved biosecurity, crate sanitation, optimized processing procedures, systematic monitoring, and responsible antimicrobial use to enhance food safety and public health. Full article

Traditional crack monitoring methods, relying on discrete point sensors, cannot capture the full spatiotemporal evolution of cracks. To address this limitation, this paper presents a distributed online monitoring approach using ultra-weak Fiber Bragg Grating (UWFBG) array sensing technology. A 16 m full-scale π-beam was instrumented with a grating array strain sensing system and tested under progressive mid-span loading until failure. The array successfully detected crack initiation at 848.7 kN (0.9P1) and tracked the transformation from L-shaped to U-shaped cracks, yielding a final crack count of 90 with a maximum width of 1.21 mm and length of 246.5 cm at 1791.7 kN. The strain–load curves exhibited a clear linear-to-nonlinear transition and continuous slope increase, closely matching manual observations. Quantitative correlation analysis further established a strong linear relationship between UWFBG peak strains and manually measured crack widths, with the fitting equation $\mathsf{\epsilon }=7918·\mathrm{w}-110$ and a coefficient of determination R² = 0.971, providing a specimen-specific basis for strain-based crack severity estimation that requires in-situ calibration before field application. The UWFBG array maintained stable signal acquisition throughout the entire loading process, offering superior data continuity and measurement range compared to resistive strain gauges, which suffered progressive data loss after cracking. The results demonstrate that the proposed method can provide real-time, full-field strain mapping and quantitative crack evolution monitoring, offering a powerful tool for bridge health assessment. Full article

Shaking tables are critical facilities for simulating seismic effects via ground motion reproduction. However, single-table tests are often constrained by limited platform dimensions and load capacity. While multi-table synchronization partially addresses these limitations, traditional array control methods under rigid connections face challenges, including degraded precision from synchronization errors and experimental interruptions due to output forces exceeding safety limits. To address high-precision synchronization requirements for rigid-connected dual-shaking table arrays, this study proposes an impedance-based internal force coordination control strategy. This approach enhances synchronization accuracy and helps prevent failures from excessive coupling forces. Specifically, a global simulation model and a mechanical model of the dual-shaking table array under rigid connection were established. Through simulation and experimental validation, the impact of synchronization errors was evaluated and the strategy’s efficacy was verified. Results show the strategy significantly reduces peak-force discrepancy between platforms. The method effectively circumvents experimental bottlenecks, such as output force saturation, inherently associated with rigid connections. Full article

Conventional bond-slip models generally represent ribbed GFRP bars as equivalent smooth cylinders, limiting their ability to describe local rib-bearing, interface degradation, and non-uniform stress transfer. This study establishes a three-dimensional finite-element model for helically ribbed GFRP bars embedded in concrete, explicitly incorporating the helical rib geometry, cohesive-frictional interface interaction, and concrete damaged plasticity. Validation against independent pull-out tests yields minor peak bond-stress errors of −0.55% and −2.49% across different bar diameters, with numerical reliability confirmed through mesh and energy checks. The results indicate that bond resistance evolves from cohesive transfer to rib-bearing action, followed by localized concrete damage, frictional sliding, and residual interlocking. Stress transfer is highly non-uniform along the bonded length, and post-peak interface degradation causes the active transfer zone to migrate dynamically away from the loaded end. Parametric analyses reveal conditional main-effect trends within the investigated ranges, demonstrating that rib height has the strongest influence on residual resistance and energy dissipation, whereas the benefit of increasing concrete strength gradually diminishes. Increasing the bonded length or bar diameter raises the total pull-out force but reduces the nominal bond efficiency due to shear lag. Finally, a simplified four-stage bond-slip relationship is proposed, wherein each stage physically aligns with distinct interface degradation phases, to facilitate computationally efficient structural-scale simulations. Full article

This paper presents a dual-output high-step-down buck converter with a resonant charge redistribution output stage using an average-difference regulation (ADR) scheme. The proposed converter combines a double-step-down (DSD) power stage and a resonant switched-capacitor charge redistribution (RCR) output stage to generate two low-voltage outputs from a 12 V input. The DSD stage regulates the intermediate voltage, which determines the sum of the two output voltages, while the RCR output stage controls the voltage difference between the two outputs through phase-shift control. Therefore, the proposed architecture separates output-voltage average regulation and output-voltage balancing, reducing cross regulation under load-imbalance conditions. The converter was designed in a 0.18 $\mathsf{\mu }$m BCD process with an active chip area of $8.29{\mathrm{mm}}^2$, including bonding pads. It supports two output voltages from 0.8 V to 1.2 V with a maximum load current of 2 A per output. Simulation results show an output voltage ripple of 7 mV at 1 V. For a 0.5 A to 2 A load step, the transient output exhibits a 147 mV undershoot, while the cross-regulation voltage is limited to 18 mV. The peak efficiency is 90.1% at a 0.5 A load current per output. Full article

To address the weak interfacial transition zone and insufficient mechanical properties of recycled aggregate pervious concrete, this study proposes a dual modification strategy using basalt fibers and ultra-fine mineral powder. The macroscopic mechanical and hydraulic properties of the material were analyzed through orthogonal experiments. Techniques including X-ray diffraction, scanning electron microscopy, and micro-computed tomography were employed to systematically reveal the microstructural evolution and internal pore network topology of the modified system. Based on range analysis of mechanical stiffness and drainage efficiency, the optimal mix proportions were determined as 5–10 mm aggregate, a water–cement ratio of 0.31, and a fiber content of 0.50%. Microscopic tests confirm that the pozzolanic reaction of ultra-fine mineral powder increases matrix density and enhances the shear bond strength between fibers and the cement paste, enabling the physical bridging effect of basalt fibers. The dual modification exhibits a synergistic effect on load-bearing capacity and crack resistance. CT scan results show that the internal pore cross-sectional area follows a unimodal skewed distribution, with the characteristic distribution peak located at 3.5 mm². This homogeneous microporous network limits the critical defect size, optimizing the stress transfer path while ensuring fluid transport. Full article

The morphology of CVD-grown molybdenum disulfide (MoS₂) is sensitive to the local precursor environment, which governs nucleation density, edge stability, and growth kinetics. In this work, we systematically investigate the effect of precursor ratio on the morphological evolution of MoS₂ microstructures synthesized by atmospheric-pressure chemical vapor deposition on SiO₂/Si substrates. By varying the relative amounts of MoO₃ and sulfur precursors, distinct growth regimes were obtained, ranging from compact hexagonal and quasi-circular domains to multilayer hexagonal structures, triangular domains, and dendritic morphologies. At higher MoO₃ loading, growth is dominated by dense nucleation, leading to isolated few-layer hexagonal domains. A moderate reduction in Mo precursor concentration promotes diffusion-assisted growth and secondary nucleation, resulting in multilayer hexagonal structures with aligned or slightly rotated stacked layers. Under sulfur-rich conditions, morphology evolves into triangular domains due to anisotropic edge stabilization, while further increase in sulfur concentration gives rise to branched dendritic structures through kinetically limited, diffusion-dominated growth. Cross-sectional FIB analysis reveals dense vertical stacking and lateral displacement of upper layers in the multilayer hexagonal domains. Raman and photoluminescence measurements confirm strong correlations between morphology, layer thickness, and optical response, with thinner regions exhibiting reduced Raman peak separation, enhanced photoluminescence intensity, and blue-shifted excitonic transitions. The results show that, under fixed APCVD reactor geometry, source positions, temperature profile, carrier-gas flow, and nominal growth duration, the nominal MoO₃ to sulfur source-loading ratio reproducibly correlates with the transition between compact hexagonal, multilayer hexagonal, triangular, and dendritic MoS₂ morphologies on amorphous SiO₂/Si substrates. Because vapor-phase Mo- and S-containing partial pressures were not directly measured, this ratio is treated as a nominal source-inventory descriptor rather than as a direct vapor-phase stoichiometric ratio. The observed trends are interpreted using a qualitative thermodynamic and kinetic framework based on precursor fluence, nucleation density, edge stability, and diffusion-limited growth. Full article

To address the elevated local peak loads, voltage degradation at weak nodes, increased line power flows, and rising operational costs caused by uncoordinated electric vehicle (EV) charging in shopping mall and workplace areas, this paper proposes a coordinated orderly charging method that integrates photovoltaic (PV) generation, an energy storage system (ESS), and EVs based on a two-stage modified bounty hunter optimizer (MIBHO). First, an uncoordinated EV charging load model for the shopping mall and workplace area is constructed using the Monte Carlo method to simulate vehicle arrival times, departure times, initial state of charge (SOC), and target SOC. Next, the mall base load, PV system, ESS, and EV charging station are integrated at node 18 of the IEEE 33-node distribution network, and an orderly charging optimization model is formulated incorporating vehicle time windows, SOC requirements, single-vehicle power limits, and station-level capacity constraints. The proposed MIBHO uses adaptive hierarchical block encoding for coarse search and a refined 24-dimensional hourly search. Without changing daily EV charging energy, it increases peak-PV charging from 52.41% to 69.46%, reduces losses from 4964.0 to 4892.5 kWh, lowers costs from CNY 805.12 to 718.03, and mitigates the evening peak. Classical and CEC2017 tests confirm its competitiveness. Full article

To address the high dependence on diesel generation, renewable energy variability, and limited demand-side flexibility of remote islanded microgrids, this study develops a low-carbon economic dispatch framework for an islanded photovoltaic–wind–diesel–battery energy storage system with coordinated demand response. The proposed model minimizes the operating cost, pollutant treatment cost, and load-loss penalty cost while satisfying generation-output, battery state-of-charge, charging and discharging, demand-response, and islanded power-balance constraints. To solve the resulting high-dimensional, nonlinear, and strongly constrained optimization problem, a rotation quantum particle swarm optimization algorithm (RQPSO) is proposed. In contrast to the conventional velocity–position update, RQPSO independently encodes each decision variable using a full-dimensional quantum phase representation and performs the search through a shortest-path rotation-guided phase-updating mechanism. Adaptive angular mutation, elite local refinement, and stagnation-aware restart are further incorporated to balance global exploration, local exploitation, and convergence stability. The algorithm is evaluated using nine 30-dimensional benchmark functions and representative 24 h forecasted load and renewable-generation profiles for Island data. Under the reliability-priority scheduling scheme, RQPSO achieves a total scheduling cost of 69,017.69 CNY, diesel fuel consumption of 6636.20 kg, and estimated CO₂ emissions of 18,332.49 kg. Compared with conventional PSO, these three indicators are reduced by 9.34%, 12.25%, and 12.25%, respectively. RQPSO also reduces the total cost by 6.16–27.36% relative to six comparison algorithms. The results demonstrate that the coordination of demand response and battery storage can improve peak–valley regulation, reduce diesel dependence and emissions, and maintain feasible and economical operation under different renewable-generation conditions. Full article

Tendon profile geometry is a structural design variable whose effects on prestressed concrete beams have, until now, been studied separately for shear, ductility, and stiffness response. This paper unifies those threads through a single nonlinear finite element investigation of eight tendon profiles (B0–B7) across two beam depths (300 × 600 mm, L/d = 13.33; and 300 × 900 mm, L/d = 8.48), comprising 16 validation beam models plus an 82-simulation parametric sweep of tendon inclination angle (0–20°). Part A characterizes cracking, yield, and ultimate loads, three-stage stiffness (Ki → Kpc → Ku), ductility index, and deflection serviceability. Ductility is quantified as the peak-displacement-based index μΔ = Δu/Δy; post-peak plateau behavior is additionally quantified through a failure-displacement ductility index (μΔ,f) and an absorbed-energy index (μE), recovered from the full descending load–deflection branch of each model. Key findings: the trapezoidal beveled profile (B6) achieves the highest ductility overall (μΔ = 3.83 in deeper beams, +99.5% over straight); the hybrid parabolic–straight profile (B5) leads ductility in shallow beams (μΔ = 2.16, +14.9%); the five-row distributed trapezoidal profile (B7) achieves the highest post-cracking stiffness in deeper beams (Kpc = 61.93 kN/mm, +7.6%) and highest yield load, but at a ductility cost; and all 16 models satisfy ECP 203-2020 and ACI 318-19 deflection limits at service load. Part B develops and validates a dimensionless shear-inclination efficiency index ηv, calibrated by nonlinear regression on the 82-simulation database: ηv = 1 + 0.14·μps·λps·(d/h)^0.6·θ^0.9, achieving R² = 0.93 and RMSE < 5%, with a mean conservative safety margin of 6% across the 16 validation configurations. Sensitivity analysis identifies inclination angle θ as the dominant variable, ahead of depth ratio d/h and distribution index λps. A step-by-step design procedure with a profile-specific compliance table allows ηv to be applied directly to ACI 318-19 or ECP 203-2020 shear predictions: at a sub-minimum stirrup ratio of 0.14%, ηv enables five of eight profiles in shallow beams and three in deeper beams to achieve full code compliance, numerically indicating potential stirrup savings of up to 40%, pending experimental verification and reliability-based calibration before design use. Read together, the two parts show that tendon geometry simultaneously governs shear efficiency, post-cracking stiffness, and ductility—three previously disconnected performance axes—and that the optimal profile choice is depth-dependent and objective-dependent, a distinction current codes do not address. The finite element procedure is validated against six post-tensioned specimens for the global load–deflection response and peak-load agreement (R² = 0.97 and 0.95, respectively); cracking load, yield point, post-peak plateau behavior, and the shear-governed failure mode of the deeper beams were not independently observed in the same experimental dataset, so the ductility, stiffness-degradation, and shear-governed-failure findings reported here should be read as numerically-derived results requiring further experimental confirmation, distinct from the peak-load response that is directly validated. Full article