Search Results (1,034)

Severe longitudinal vibrations and abnormal tension fluctuations in hoisting ropes pose significant threats to the safe and stable operation of mine hoisting systems. To address these issues, this paper proposes a semi-active vibration-suppression strategy combining a magnetorheological damper (MRD) with output-feedback adaptive sliding-mode control (ASMC). A dynamic model of the MRD-equipped hoisting system is developed using Hamilton’s principle. The nonlinear hysteresis of the MRD is described by a simplified extended hyperbolic tangent function model (SEHTFM), and an inverse model converts the desired control force into a feasible real-time current command. Using only displacement and velocity measurements at the conveyance–rope connection, the ASMC compensates for matched uncertainties, including boundary excitation, modeling and truncation errors, and force-realization errors. Numerical simulations compare an optimized passive viscous damper benchmark, SMC–MRD, and ASMC–MRD responses under varying payloads, accelerations, and hoisting speeds. During constant-speed operation, ASMC–MRD achieves peak reduction rates of 82.8% in dynamic displacement and 77.6% in dynamic tension relative to the optimized passive benchmark. The results demonstrate accurate force realization with small bounded tracking errors and improved robustness under variable operating conditions. Full article

Modeling a user’s evolving goals, values, and affect over time is central to perspective-aware AI, yet progress is bottlenecked by the lack of longitudinal data with ground-truth labels for the latent identity state. We introduce PAiNT (Perspective-Aware AI Identity and Narrative Toolkit), a generative framework that simulates long-horizon persona trajectories and emits corresponding multimodal artifacts with ontology-aligned labels of the latent identity state that produced them. PAiNT decouples identity dynamics from artifact generation via a typed Persona Matrix and Situation Graph, coordinated through a multi-agent loop with validation-gated transitions and bounded-window history conditioning. Across four personality archetypes, four backbone LLMs, and three architectural ablations, evaluated with a nine-metric suite calibrated on published longitudinal data, we find that (i) persona initialization produces a durable identity signal that persists above stochastic event noise; (ii) multi-agent orchestration and history conditioning govern distinct quality dimensions, with removal of either causing different failure modes; and (iii) a coherence frontier constrains the trade-off between temporal resolution and horizon, with substantial penalties at daily granularity. We release PAiNT and PAi-Bench, a human-validated benchmark of 1200 labeled multimodal artifacts. Full article

Distributed-drive all-wheel steering (AWS) six-axle vehicles possess distinct advantages in power performance, maneuverability, and environmental adaptability. However, when navigating tight curves under sudden low-friction road conditions, their inherent long wheelbase and strong inter-axle coupling typically lead to compromised spatial maneuverability, trajectory decoupling between the vehicle nose and tail, and lateral dynamic instability. To resolve these critical issues, this paper proposes a geometry–dynamics coupled lateral control scheme with adaptive speed planning for six-axle vehicles under confined spatial and low-friction conditions by seamlessly fusing a dual-point preview mechanism with multi-mode steering mappings. First, a three-degree-of-freedom nonlinear vehicle dynamic model incorporating longitudinal, lateral, and yaw motions is constructed, alongside the formulation of extended Ackermann kinematic steering manifolds for three distinct modes: rear-axle steering, center steering, and crab steering. To rectify the kinematic under-constrained deficiency inherent in conventional single-point preview path-tracking architectures, a joint front-and-rear dual-point preview constraint mechanism is established. This framework permits the quantitative derivation of a spatial geometric reconstruction method for the instantaneous center of rotation (ICR), which algebraically maps the ideal ICR trajectory requirements onto the physical constraints of the selected steering modes. Consequently, complete geometric constraints on both the front and rear trajectories are achieved, enabling active compression of the vehicle’s turning radius. Furthermore, to handle sudden low-friction disturbances, road adhesion limits and vehicle lateral stability boundaries are explicitly incorporated to design a multi-scale adaptive preview distance dynamic scaling mechanism driven by dynamic safety margin corrections. By adaptively scaling the spatial constraint at the geometric layer, this mechanism proactively mitigates nonlinear tire sideslip force saturation via feedforward action, thereby preventing tracking divergence and catastrophic sideslip instability under physical adhesion limits. Co-simulations based on the high-fidelity TruckSim-Simulink platform demonstrate that, in standard curves, the proposed dual-point preview manifold fusion strategy reduces the minimum turning radius by 9.6–10.1% and shortens the cornering transit time by 7.5% compared with the traditional single-point preview mechanism. By actively constraining the front and rear trajectories, the trajectory decoupling between the vehicle nose and tail is effectively resolved. Under narrow-lane scenarios, the maximum lateral error is restricted within 0.78 m, representing a 37.6% reduction relative to the single-point preview, while the maximum steering angle of the front axle is compressed by approximately 18%, thereby significantly improving spatial passability and preventing intermediate body interference. Most notably, under low-friction surface disturbances, the dynamic-margin-corrected adaptive preview adjustment mechanism exhibits remarkable robustness, constraining the maximum lateral tracking error to within 0.68 m. The proposed geometry–dynamics coupled lateral control strategy successfully elevates the tight-curve maneuverability of heavy transport vehicles while concurrently reinforcing their lateral dynamic stability under limit combined spatial and adhesion constraints. Full article

A new aeroservoelastic modeling and analysis methodology is presented for an aircraft with multiple control surface freeplay nonlinearities using the fictitious mass approach. The model incorporates freeplay in the right and left ailerons and the elevator, and is developed by combining linear aeroelastic models in an external simulation environment. State-space, time-domain simulations are performed to investigate both single and multiple freeplay configurations and their effects on limit cycle oscillation (LCO) characteristics, while a flight control algorithm maintains overall stability of the aircraft. The results show that, for elevator dynamics, LCO boundary decreases when combined aileron–elevator freeplay is present compared to the case with elevator freeplay alone. In contrast, for the same combined configuration, the aileron LCO onset occurs at a lower speed, while the flutter boundary shifts to a higher velocity relative to the aileron-only freeplay case. These findings demonstrate the strong coupling between longitudinal and lateral dynamics in the presence of multiple freeplay nonlinearities. The results further suggest that multiple freeplay can alter the dominant instability mode and delay the onset of sustained oscillations. Full article

As the foundational sensing element for AI-driven structural health monitoring systems, piezoelectric ceramic (PZT) is widely adopted in civil engineering to capture high-fidelity physical responses. Distinct from existing studies focusing on the actuation mode or static/quasi-static sensing conditions, this study specifically investigates the dynamic strain transfer behavior of surface-bonded PZT sensors in sensing mode by establishing a three-layer analytical model incorporating the adhesive shear lag effect, validated by finite element simulations. Accordingly, a dual-regime dynamic calibration strategy is proposed: employing a single sensitivity value for low-frequency global structural vibrations and frequency-dependent correction for high-frequency elastic wave applications. Parametric analyses on PZT thickness, adhesive thickness, and shear modulus quantitatively demonstrate that reducing PZT/adhesive thicknesses and increasing adhesive shear modulus extend the compensation-negligible frequency range (defined by a 10% strain ratio deviation threshold) and elevate the first-order longitudinal natural frequency; practical sensor fabrication guidelines are further derived from these findings. Additionally, the system’s first-order longitudinal natural frequency stabilizes when the host-to-PZT area ratio (A_s/A_p) exceeds a critical threshold. These findings provide a theoretical basis for the optimal design, dynamic calibration, and engineering application of bonded PZT sensors. Full article

Offshore drilling operations face the critical challenge of maintaining precise weight-on-bit (WOB) control during automatic drilling feed while subjected to vessel heave disturbances. This study investigates an integrated closed-circuit hydraulic cylinder lifting system that combines full-stroke drill string compensation with potential energy recovery capabilities, addressing the control coupling problem inherent in traditional split-design systems. A longitudinal vibration model of the drill string is established using lumped mass, stiffness, and damping principles incorporating the Rayleigh method. A co-simulation model implementing nested PID control logic is developed on the AMESim platform to evaluate automatic drilling feed performance under both passive and semi-active compensation modes. Simulation results demonstrate that the proposed integrated control strategy effectively mitigates bottom-hole WOB fluctuations, with top drive velocity accurately tracking set drilling feed rates (0.01–0.02 m/s) within a response time of approximately 10 s. The system maintains operational stability under sea conditions up to Grade 6 (heave wave height ≤ 4.578 m, period 14 s), beyond which accumulator piston limit-stroke collision risks emerge. These findings validate the feasibility of integrated hoisting-compensation design and establish quantitative operational limits, providing theoretical foundations for next-generation marine drilling systems targeting ultra-deepwater and natural gas hydrate exploitation. Full article

This paper presents a low-profile wideband in-phase-fed microstrip patch antenna (MPA) operating with TM₆₀, TM₀₄, TM₆₂, TM₂₄, TM₄₄, TM₈₂, and TM₈₀ modes. First, a rectangular in-phase-fed MPA is theoretically analyzed to clarify how these seven modes can be effectively utilized for bandwidth enhancement. Then, a transverse slot is incorporated into the patch to progressively move the resonance of the TM₀₄, TM₂₄, and TM₄₄ modes toward that of the TM₆₀ mode. Afterward, a pair of longitudinal slots is further employed to bring the TM₆₂, TM₈₂, and TM₈₀ modes closer to the TM₆₀ mode. In addition, another pair of longitudinal slots is introduced to improve the impedance matching performance. In this way, the seven modes are properly redistributed and grouped within the desired frequency range, thereby enabling broadband operation. Finally, an antenna prototype is manufactured and tested. The experimental results demonstrate that the antenna provides an impedance bandwidth covering 4.4–6.9 GHz while maintaining stable radiation performance, which is about 25 times wider than that of the conventional counterpart. More importantly, the antenna profile is as low as approximately 0.056λ₀. Full article

This paper proposes an integrated formation control framework with a finite-time nonlinear disturbance observer (FT-NDO) for automated guided vehicles (AGVs) operating in port environments, where constrained workspace, narrow formation spacing, and complex external disturbances pose significant challenges. An adaptive leader–follower formation strategy with dynamic inter-vehicle spacing is developed to enhance maneuverability during turning. Within a hierarchical control structure that decouples lateral and longitudinal dynamics, two sliding mode controllers (SMCs) are designed: (a) a lateral SMC that prioritizes heading accuracy, limiting yaw angle error to within ±2°; and (b) a nonsingular terminal SMC (NTSMC) for longitudinal control, improving error convergence speed compared to conventional SMC. An FT-NDO is further incorporated into both control loops to estimate and compensate for external disturbances in real time, achieving a disturbance estimation accuracy of over 95% and significantly attenuating the impact of environmental disturbances. Validation through simulation and physical experiment of a dual-AGV formation in a realistic port scenario demonstrates that the proposed approach restricts formation deviation to 0.015 m and maintains stable operation under various disturbance conditions. This study provides a practical solution for dual-AGV collaborative transportation in spatially constrained and dynamically disturbed environments, with direct implications for improving operational efficiency and safety in port logistics. Full article

Under low-temperature and humid conditions, icing on airfoil surfaces, such as wind turbine blades, deteriorates the aerodynamic performance and decreases the power generation efficiency. To shorten the de-icing time and reduce the de-icing energy consumption, an ultrasonic de-icing method was used by coupling the longitudinal vibration of a piezoelectric transducer and the bending deformation of an iced plate. The simulation method was used to investigate the distributions and the variations of the stresses at the bond interface. An experimental system for ultrasonic de-icing tests was developed and built, and the de-icing experiments were carried out. The experimental results showed that the present ultrasonic de-icing method had a short de-icing time and low de-icing energy consumption, and the de-icing processes agreed with the simulation results. In the present research, the ice layer with a diameter of 20 mm was removed in the shortest de-icing time and the lowest energy consumption because its diameter was close to that of the transducer, which resulted in the highest shear stress at the bond interface. The present study provides theoretical and experimental foundations for deep research on the surface anti- and de-icing method with ultrasonic techniques. Full article

This study investigates an IPS-type Metglas/PMN-PT laminated magnetoelectric composite and its feasibility as a reciprocal mechanical magnetoelectric antenna for low-frequency transmission and reception. Finite-element simulations under quasi-static and frequency-domain conditions reveal strong magnetoelectric coupling under an optimal DC bias field, with both the direct magnetoelectric effect (DME) and converse magnetoelectric effect (CME) exhibiting pronounced resonance near 14.5 kHz, governed by the same longitudinal extensional vibration mode. Five IPS samples were fabricated and experimentally characterized. All devices showed resonant frequencies within 14.1–14.5 kHz, peak DME coefficients of 3.0 × 10⁶ to 3.9 × 10⁶ pC/Oe, and peak CME coefficients of 12.0~15.8 Oe·cm/V, confirming good fabrication consistency, transmit–receive reciprocity, and array-integration potential. The parallel IPS antenna generated a magnetic flux density of 37 nT at 1 m, and exhibited an equivalent magnetic noise of 63 fT/Hz^1/2 at 14.45 kHz. These results demonstrate that the proposed IPS structure combines high-sensitivity reception with efficient low-frequency transmission, showing strong potential for miniaturized, low-power, and long-range magnetic communication and underwater communication applications. Full article

Geopolymeric concrete beams are gaining increasing attention as sustainable structural members. The paper presents an experimental investigation on the deflection and cracking behavior of geopolymeric recycled aggregate concrete (GRAC) beams, with emphasis on effects of the longitudinal reinforcement ratio and the recycled aggregate (RA) replacement ratio. Using digital image correlation (DIC) technology, the failure modes, load–deflection curves, deflection characteristics, stiffness, and cracking behavior were systematically analyzed. The results indicated that increasing the reinforcement ratio leads to the same trend in GRAC beams as that observed in ordinary reinforced concrete beams. At 50% RA replacement, GRAC beams exhibit improved cracking resistance, 13.41% higher cracking stiffness, 6.93% lower deflection, and enhanced ductility compared to specimens without RA, attributed to the enhanced RA–matrix interface. However, a further increase in the RA replacement ratio leads to poorer flexural performance of the GRAC beams. In addition, predictive models for cracking moment, stiffness, deflection, and maximum crack width of GRAC beams were proposed based on the experimental results, incorporating the plastic influence coefficient, the comprehensive coefficient for the average strain at the extreme compression zone of concrete and the maximum crack width correction factor. The calculated values agreed well with the test data, offering a basis for structural design and engineering application. Full article

This study aims to identify the optimal aging regime that balances strength and intergranular corrosion (IGC) resistance in a 2060 Al–Li alloy under T8 temper. The evolution of microstructure, mechanical properties, and IGC behavior was systematically investigated across various aging conditions. The most relevant results show that the optimal regime for the 3% pre-stretched alloy is 150 °C for 32–48 h. At the peak-aged state (150 °C/48 h), the alloy achieves a yield strength (YS) of 521 MPa and ultimate tensile strength (UTS) of 541 MPa in the longitudinal (L) direction, and 486 MPa and 548 MPa in the long-transverse (LT) direction, with elongations of 11.1% and 12.2%, respectively. Under this condition, the corrosion mode shifts from IGC to pitting, with a maximum pitting depth of 98.6 μm. Microstructural analyses confirm that the T₁ (Al₂CuLi) phase is the primary strengthening precipitate. Critically, as aging temperature and time increase, T₁ plates extensively nucleate and grow within grain interiors, while their distribution at grain boundaries (GBs) becomes discontinuous. This discontinuous GB precipitate morphology interrupts continuous anodic dissolution channels, thereby significantly enhancing localized corrosion resistance. Notably, these findings can offer practical guidance for industrial heat treatments of third-generation Al–Li alloys, particularly for safety-critical aerospace components where both strength and corrosion resistance are mandatory. Full article

Background: While region-based models have informed pain neuroscience, chronic pain is now increasingly conceptualized as a network disorder. This narrative review aimed to critically examine the conceptual evolution of chronic pain models from region-based representations toward large-scale functional network frameworks across adult and pediatric populations while exploring how emerging artificial intelligence (AI)-driven approaches may support future precision pain medicine. Methods: A structured literature search was performed in PubMed, Scopus, and Web of Science, focusing on the scientific output addressing adult and pediatric chronic pain, pain-related neuroplasticity, functional network alterations, neuromodulation, and AI-based applications in pain medicine. Results: The reviewed literature supports a progressive conceptual shift from region-based representations of pain toward network-oriented models involving dysfunctional interactions among the salience, default mode, central executive, and sensorimotor networks. Although emerging evidence suggests developmental network alterations in pediatric chronic pain, current conclusions remain limited by the relative scarcity of longitudinal neuroimaging studies. Emerging AI applications demonstrate promising potential for objective pain assessment, trajectory prediction, and personalized therapeutic decision-making. Conclusions: The transition from the pain matrix to functional network models represents one of the most important conceptual advances in contemporary pain neuroscience. A network-based perspective may accelerate AI-enabled pain biomarkers and individualized interventions. Full article

GaAs_1-xN_x/GaAs (001) (0 < x ≤ 0.037) tensile-strained epilayers are of considerable importance in optoelectronics due to their ability to offer large and resilient band structure engineering. Strain causes valence-band splitting, giant bandgap reduction and phonon frequency shifts. Optimum performance of III-V-Ns in long-wavelength lasers, infrared photodetectors, optical modulators, and multi-junction solar cells is contingent on their distinctive vibrational and optical characteristics. We report results of meticulous simulations of GaAs_1-xN_x alloys to validate Fourier transform infrared (FTIR) reflectivity and spectroscopic ellipsometry (SE) data in the far-infrared and ultraviolet regions. The FTIR spectra showed strong reflectivity peaks and dips in the reststrahlen band region, linked to the transverse optical ${\omega }_{\mathrm{T}\mathrm{O}1}$ and longitudinal optical ${\omega }_{\mathrm{L}\mathrm{O}1}$ modes of the Ga-As bond and a high-frequency ${\omega }_{\mathrm{T}\mathrm{O}2}$ local vibrational mode of GaAs:N. Modified dielectric functions of GaAs_1-xN_x/GaAs epilayers are carefully evaluated using an improved Adachi’s semiemperical method to study the x and E-dependent optical constants. Focusing on the electronic band structures at critical points, this approach provided accurate analytical formulation to evaluate complex dielectric $\tilde{\epsilon }$(E) and refractive indices $\tilde{\mathrm{n}}$(E) for simulating reflectance spectra in a wide energy range with good agreement to the SE data. Full article

The seismic fragility of reinforced concrete (RC) bridge piers is critical for urban rail transport systems, as severe pier damage may interrupt post-earthquake operation and threaten network safety. Compared with conventional highway bridge piers, urban rail transport RC solid piers usually have lower axial load ratios, larger cross-sections, and stricter serviceability requirements. However, the combined effects of geometric parameters, reinforcement detailing, and material strength on their cyclic behavior, dynamic response, and seismic fragility remain insufficiently understood. To address this issue, seven 1/4-scale RC solid pier specimens were tested under quasi-static cyclic loading to examine the effects of pier height, transverse reinforcement ratio, and longitudinal reinforcement ratio on damage evolution, hysteretic response, skeleton curves, and energy dissipation. A fiber-based OpenSees model considering bond-slip effects was then established, validated against the tests, and extended to a full-scale prototype pier for parametric analysis. The effects of aspect ratio, axial load ratio, longitudinal reinforcement ratio, stirrup ratio, steel yield strength, and concrete strength were evaluated under cyclic loading and nonlinear dynamic time-history excitations. An incremental dynamic analysis-based probabilistic seismic demand model was further developed using 30 near-fault ground motions, with peak ground acceleration as the intensity measure and displacement ductility as the engineering demand parameter. The results showed that increasing the aspect ratio changed the failure mode from flexure-shear-dominated to flexure-dominated behavior, increasing the ultimate displacement from 122 mm to 155 mm while reducing the peak lateral strength from 263 kN to 248 kN. Increasing the longitudinal reinforcement ratio improved both peak strength and ultimate displacement, from 226 kN to 262 kN and from 120 mm to 160 mm, respectively. The numerical results indicated that aspect ratio, axial load ratio, and longitudinal reinforcement ratio had more pronounced effects on seismic demand and fragility than stirrup ratio. Increasing steel yield strength generally reduced seismic fragility, whereas increasing concrete strength enhanced lateral resistance but did not necessarily improve fragility performance. These findings suggest that the seismic performance of urban rail transport RC solid piers should be evaluated by combining cyclic response, dynamic demand, and fragility-based performance, rather than by maximizing any single design parameter. Full article