Search Results (498)

Tendon-cable transmission can reduce distal-limb inertia in full-size humanoids, but its elasticity, hysteresis, backlash, and multi-joint coupling introduce state-dependent joint-to-motor discrepancies. We present a hierarchical whole-body tracking framework for the 28-DoF Droid X3 that separates high-level motion learning from transmission compensation. A reference-residual policy is trained in simulation by single-stage proximal policy optimization (PPO) using a unified robot-space motion representation, globally anchored tracking rewards, hierarchical hard-example sampling, and tendon-oriented domain randomization. In simulation checkpoint evaluation, more than 90% of 12,674 tested reference motions are completed. Independently, a state-conditioned mapper is trained offline through a differentiable motor–joint forward model identified from physical motor-excitation data and connected in series between the frozen policy and the low-level motor controller. Randomized repeated Mapping-OFF/ON trials are conducted on two nominally identical Droid X3 units. Within every robot–motion block, the frozen PPO checkpoint, reference trajectory, controller settings, safety bounds, and frozen mapper weights are held fixed; complete trials are the statistical units. OFF converts desired joint positions with the robot-specific fixed static calibration, whereas ON feeds the complete policy-level desired-joint vector and measured plant state to the frozen mapper, which directly outputs the complete motor-position command. Across the complete physical trials, the aggregate action-completion rate is 68% with Mapping OFF and 79% with Mapping ON, an increase of 11 percentage points. Representative walk, squat, and dance trajectories illustrate lower tracking errors under Mapping ON, while individual frames and selected temporal fragments are used only for visualization. Full article

Tensegrity structures, due to their lightweight and self-equilibrating characteristics, have found extensive applications across various engineering fields. The introduction of equal cable length as an additional geometric constraint enables a high degree of geometric symmetry, resulting in uniform internal force distribution and predictable mechanical responses. However, existing stiffness matrix assembly methods predominantly rely on conventional node-element topological connectivity matrices confined to classical one-to-one force-displacement systems, struggling to exploit the geometric regularities inherent in equal-length constraints and highly symmetric configurations. To address this, the paper proposes a stiffness matrix modeling method tailored for equal-cable-length tensegrity structures within the linear stiffness framework. A generalized connectivity matrix is introduced to unify the topological description of struts and cables while integrating displacement compatibility, internal equilibrium, and geometric constraints into a cohesive algebraic system. Leveraging symmetry properties and member categorization by loading type, the method embeds equal-length and symmetry grouping information directly into assembly, significantly reducing independent variables and construction complexity. A finite element model is established for numerical implementation, and experiments on a three-bar tensegrity structure validate the theoretical model, with minor deviations confirming its reliability. Full article

This paper presents a comprehensive wind tunnel investigation on the wind-induced vibration characteristics of a novel four-cable-supported photovoltaic (PV) structure. The proposed structure system integrates two adjacent dual-cable rows through rigid connecting rods to form a collaborative load-bearing framework, aiming to enhance overall stiffness and mitigate wind-induced vibrations. A 1:15-scale aeroelastic model was tested in a boundary-layer wind tunnel for both single-row and five-row configurations. Wind-induced displacements were measured using a non-contact high-definition camera system capable of real-time, multi-point monitoring across multiple rows, while cable tension forces were simultaneously recorded with load cells—a combined measurement approach rarely reported in existing studies. The effects of wind speed and wind direction angle on the vibration responses were systematically examined. Results reveal that vertical vibrations dominate, with mid-span displacements reaching maximum values. The shielding effect among multiple rows is pronounced: the windward first row consistently exhibits the largest displacements and cable forces under both wind pressure and suction. Wind directions of 0° and 180° are identified as the most unfavorable for pressure and suction, respectively. Cable forces under pressure exceed those under suction, and within each row, windward cables sustain greater forces than leeward cables. These findings provide essential experimental reference data for the wind-resistant design of multi-row cable-supported PV support structures. Full article

With the rapid development of wind power generation, submarine cables have become a critical transmission channel for delivering offshore wind energy to onshore power stations. Because of the difficulty of submarine-cable maintenance, particular attention should be paid to their overvoltage characteristics during operation. Taking a ±200 kV DC submarine-cable project as the research background, this paper establishes a PSCAD/EMTDC model of a two-terminal MMC-HVDC submarine-cable system and compares the conductor-to-ground overvoltages caused by faults at different electrical locations. Among the investigated AC-side cases, single-line-to-ground faults on the valve sides of the connecting transformer and bridge-arm reactor produce relatively high cable overvoltages, with the bridge-arm-reactor valve-side fault reaching a maximum of 2.48 p.u. (496.48 kV). Among all investigated cases, the grounding fault on the valve side of the DC reactor produces the highest overvoltage, reaching 2.93 p.u. (586.18 kV) at approximately 30 km along the cable. After the initial transient associated with the DC-side grounding faults, the healthy-pole conductor-to-ground voltage remains at approximately 2.0 p.u. The results identify the relatively severe fault locations and cable sections requiring particular monitoring attention and provide a case-specific reference for DC submarine-cable monitoring and subsequent project-specific insulation-coordination studies. Full article

To address the severe threats posed by stay cable fractures, this study investigates a fatigue fracture of a fork-eye anchor head induced by excessive cable vibrations on a landscape cable-stayed bridge. A comprehensive methodology integrating field monitoring, theoretical analysis, and finite element simulation is employed to reveal the vibration characteristics, fatigue mechanism, and multi-factor coupled effects. Field tests identify wind-induced vibration and parametric resonance as the primary external triggers for fatigue damage. A simplified mechanical model of the fork-eye anchor head is established to evaluate the stress state under combined axial tension and bending moment. Fatigue analysis using the stress–life method elucidates how vibration-induced alternating stress significantly reduces the fatigue life of the connecting screw. The multi-factor coupled fracture mechanism is revealed, and practical mitigation measures including supplementary dampers and regular inspection are proposed. The findings provide a theoretical basis and engineering guidance for the design, maintenance, and safety assessment of similar landscape cable-stayed bridges. Full article

This study presents the analysis of towed stability and the optimization design method for an underwater towed body, aiming to design a towing system with high stability, good hydrodynamic performance and a high degree of safety and reliability. By proposing analytical models for both the static and dynamic behavior of the towing system, the influence of the structural characteristics on the motion of the towed body were determined. The Computational Fluid Dynamics (CFD) method was employed to conduct hydrodynamic numerical simulations of the towed body, obtaining precise hydrodynamic coefficients. The optimization design of the towed body’s center of gravity and cable connecting point position was carried out. The simulation results systematically revealed the influence of towing speed and cable length on the dynamic behavior of the towed body. With the speed increasing from 4 kN to 20 kN the depth of the towed body reduces from 277.0 m to 90.6 m, the tension of the cable inreases from 11.5 kN to 171.85 kN. At a towing speed of 20 kN, the optimized towed body stay at an averaged pitch angle of ${6.82}^{°}$ with very small roll angles. This research provides theoretical and numerical analyzing approach for the design of high-performance underwater towed bodies. Full article

With intensifying mineral resource extraction, groundwater ingress in large cross-sectional intersection roadways near aquifers is becoming increasingly common. Disturbances from roadway excavation and mining may induce fractures connecting to aquifers and a series of related adverse hydrogeological effects, posing severe challenges to surrounding rock stability control of such excavations. Large-span roadway intersections in water-bearing sandstone–mudstone interbedded weak strata are frequently subjected to severe instability, bringing great challenges to the design of roadway supports. A typical large-section intersection roadway from a mine in Xinjiang is taken as the research object. Systematic research is carried out via field investigation, numerical modeling and field testing. Results show that the original aquiclude structure of sandstone–mudstone interbeds is destroyed by excavation disturbance. Mudstone strength degradation induced by sandstone pore water migration is confirmed as the core cause of surrounding rock instability. Surrounding rock deformation increases rapidly with the rise in mudstone moisture content, and obvious sudden change characteristics are presented when the water content approaches saturation. A collaborative support strategy with waterproofing as the core is proposed. Targeted drainage, high-reliability zoned support and anti-corrosion measures for support components are set as supporting measures. The proposed strategy is verified to perform well in field industrial tests. Waterproof measures, waterproof anchoring agents, anchor cable grouting and high-performance anchor-mesh-cable shotcreting support are integrated in the strategy. Surrounding rock deformation can be effectively controlled and a good application effect is achieved. The proposed support system is also applicable to roadway projects in metal and non-metal mines with similar geological conditions. Full article

Distributed acoustic sensing (DAS) systems capture complex, nonlinear wave propagation across fiber-optic cables. Conventional event classification architectures, constrained by static physical topologies or isolated spatial grids, fail to effectively adapt to the dynamic feature relationships associated with such events, particularly when modeling complex spatiotemporal interactions across sensor arrays. To resolve these structural limitations, we introduce the Spectro-Spatial Dynamic Graph Neural Network (S2-DyGNN), whose architecture couples a two-dimensional frequency–time convolutional front-end with a dual-matrix graph neural network (GNN). First, the convolutional module extracts spectro-temporal features, explicitly capturing localized acoustic dynamics independent of inter-sensor interference. Subsequently, the graph module constructs a dual-matrix topology, fusing a static physical distance prior with a data-driven adjacency matrix that recalculates spatial connections frame by frame from input signals. When evaluated on a highly skewed nine-class DAS field dataset, S2-DyGNN outperformed other conventional models by achieving a peak macro-averaged F1-score of 86.6% and an overall accuracy of 94.0%. The dual-matrix graph topology prevented dominant background features from washing out sparse transient events, improving the minority “openclose” class F1-score to 55.7% compared to the 48.0% ceiling of a static graph topology. These results demonstrate that explicitly coupling localized spectro-temporal representations with physically anchored spatial topologies consistently outperforms models that process these domains in isolation, providing a highly robust and scalable solution for real-world continuous monitoring systems. Full article

This study established a sensor structure and readout circuit for identifying the point of force application within a single cable piezoelectric sensor. The sensor is highly flexible and enables wide-area sensing because it can be fabricated in long, continuous form. To determine the point of force application, the central electrode of the cable sensor was designed to have high resistance, and charge amplifiers were connected to both ends of the cable. The generated charge was divided and measured by the two amplifiers in a proportion corresponding to the point of force application. The position was predicted using a normalized ratio calculated from the charge quantities measured by the two amplifiers. The principle was first verified by accurately identifying the loaded section in a five-segment cable connected through discrete resistors. For cable sensors with a high-resistance central electrode, we predicted the point of force application with a root mean square error of 25 mm by interpolating the relationship between the point of force application and the normalized charge ratio with a smoothing-spline calibration model. Full article

In this study, the seismic vulnerability of the Ferdowsi School building in Tabriz is investigated. The research began with comprehensive fieldwork, during which exploratory surveys and in-depth technical inspections of all structural components were performed. Experimental testing of prismatic masonry specimens was carried out to evaluate their mechanical characteristics, and the resulting properties were then incorporated as input parameters into the numerical model. The seismic vulnerability assessment was then carried out using nonlinear static (pushover) analysis, applying a lateral load pattern proportional to the first vibration mode of the structure. For numerical simulation, the building was modeled in the ABAQUS finite element software using the macro-modeling technique. The results of the nonlinear static analysis indicated that the building does not possess sufficient load-bearing capacity at the target displacement. Damage was primarily concentrated in the form of cracking in the masonry walls as well as in the dome-shaped sections of the roof, requiring the implementation of a seismic retrofitting scheme to enhance the structure’s seismic performance. To rehabilitate the structure, horizontal and vertical reinforced concrete beams were introduced as confining elements for the masonry walls and subsequently applied in the strengthening project. Furthermore, due to the presence of a domed roof at the first-floor level, it was strengthened using FRP composite materials to enhance tensile capacity and ductility. At the second-floor level, where the roof structure is made of timber elements, a steel cable system was employed to improve its strength and diaphragm action. As for the third-floor timber truss roof, the connections were upgraded and reinforced to provide reliable force transmission and to maintain the overall integrity of the structural system. Following the implementation of the retrofitting measures, the structural model was re-analyzed using nonlinear static analysis. The results demonstrated that the proposed strengthening scheme successfully increased the structural capacity up to the target displacement level and satisfied the intended performance requirements. In the final section of the paper, the implementation details of the retrofitting interventions, as well as the practical experiences gained during the implementation process, are presented and discussed. Full article

The incipient cable fault in active low-resistance-grounded distribution networks is a typical asymmetrical fault and is difficult to locate because the fault current is weak, short-lasting, and easily affected by distributed generation (DG). To address this typical asymmetrical problem, this paper proposes a fault section location method based on multidimensional information correlation analysis. First, an equivalent incipient fault model is established by combining the Kizilcay arc model with an insulation-defect resistance, so that the intermittent arc behavior and the conductive path of degraded insulation can be represented simultaneously. Then, the generalized S-transform is used to extract three features from the transient zero-sequence current, namely the transient current energy index, group phase-angle polarity, and waveform similarity. On this basis, a multidimensional feature vector and a comprehensive similarity coefficient are constructed to identify the fault section, and an auxiliary downstream energy comparison rule is introduced to distinguish the actual fault section from DG-connected pseudo-fault sections. The method is verified in MATLAB/Simulink R2025a under different fault locations, DG access conditions, penetration levels, noise levels, and key parameter variations. The simulation results under the tested conditions indicate that the proposed method can effectively identify asymmetrical incipient cable fault sections in active low-resistance-grounded distribution networks. Full article

Accurate thermal management is crucial for ensuring the safety, longevity, and performance of lithium-ion batteries, especially in compact embedded systems like USB chargers, power banks, and IoT nodes. Despite extensive research on predictive thermal models and intelligent control frameworks, their implementation in resource-constrained microcontroller-class devices has been limited. Existing strategies in the literature, such as threshold-based or PID logic, cloud-enabled analytics, machine learning models, and observer-based estimators, are often reactive, computationally intensive, or dependent on external infrastructure, making them unsuitable for low-power, standalone applications. This study introduces a novel Scalable Embedded Thermal Intelligence architecture designed for real-time battery thermal regulation in locally executable, without cloud dependency, low-cost platforms. Unlike conventional methods, the proposed system operates entirely on-device using closed-form models implemented on an ESP32 microcontroller. It combines two synergistic algorithms: a static preemptive model that calculates a safe C-rate at startup based solely on ambient and initial battery temperature, and a dynamic disturbance-aware model that monitors temperature rise per SOC step and adjusts airflow or current adaptively without requiring high memory, floating-point units, or supervisory control. The architecture achieves sub-second response times, <7% RAM, and <25% Flash usage, and does not need cloud connectivity, simulation backend, or complex thermal-management infrastructures such as liquid cooling circuits, phase-change systems, or cloud-supervised architectures. The significant contribution of this work is not the introduction of a new electrochemical–thermal formulation, but the effective integration and application of previously validated closed-form thermal predictors on low-cost microcontroller-class hardware, designed for anticipatory battery thermal regulation while adhering to strict computational limitations. Compared to traditional battery thermal management systems using PCM, liquid-cooling circuits, or cloud-based predictive estimators, the proposed approach eliminates the need for complex thermal hardware, fluidic systems, external computing infrastructure and resource-efficient edge operation. This makes the system suitable for deployment in real-world embedded applications like USB-C smart charging cables, compact IoT power banks, and portable medical devices, where form factors, energy efficiency, and cost are critical. The proposed SETI framework offers a firmware-integrated architecture and a firmware-integrated solution that provides a lightweight embedded alternative for predictive thermal regulation for distributed energy systems and miniaturized electronics. Full article

This paper proposes a retractable cable-driven reciprocal truss structure consisting of a cable-truss system with sliding cables and a reciprocal truss system. Adjusting the cable lengths in the cable-truss system drives the opening and closing motion, while the reciprocal truss carries the panel dead loads and live loads. The structure exploits the flexibility of cables by replacing multiple independent cables with continuous cables, thereby reducing the number of driving motors. Additionally, the cables are connected to the inner ring nodes of the triangular truss, thereby modifying the support conditions of the truss. This connection reduces the influence of external loads on structural deformation and consequently lowers the self-weight required to resist deformation, thereby helping to maintain structural stability during opening and closing. A finite element model of the structure is established using ANSYS to analyze the influence of different parameters on its mechanical performance, and the closing process is simulated by adjusting the cable lengths. Numerical results show that the proposed structure meets the design requirements. Full article

Low-frequency alternating current (LFAC) transmission has attracted increasing attention for medium- and long-distance offshore wind power transmission, as this application scenario is typically characterized by long transmission distance and large installed capacity. Converting offshore low-frequency alternating current into onshore power-frequency alternating current requires a dedicated frequency conversion device. Compared with power–electronic converter-based schemes represented by the modular multilevel matrix converter (M3C), grid connection via a motor–generator pair (M-G) enables the renewable energy port to retain intrinsic synchronous-machine characteristics, including inertial support, voltage support, and fault isolation. This paper elaborates the operating principles and mathematical models of the two types of frequency conversion solution for LFAC transmission systems, and systematically analyzes the frequency support, voltage support, and fault-isolation capabilities of the M-G scheme. Simulation results demonstrate that under a sudden increase in onshore active power load, the M-G system can provide strong frequency support by releasing rotor kinetic energy, and a larger inertia time constant mitigates the frequency drop more effectively. Under a sudden increase in onshore reactive power load, the M-G scheme offers a greater reactive power margin benefiting from its strong short-term overcurrent capability. Moreover, increasing the excitation gain on the motor side and installing shunt reactors at both ends of the submarine cable can effectively improve the voltage profile along the cable. Full article

The presence of holes in the crash boxes of vehicle parts is sometimes unavoidable to accommodate connections, cables, and maintenance access. The effect of circular cutouts on the crashworthiness of a Carbon-Fiber Reinforced Polymer (CFRP) rectangular laminate used as a crash box, consisting of identical plies with different stacking sequences, was investigated. Five tubes with different stacking sequences were prepared: an outer ply of 0°/90° twill-woven fiber and inner plies of 0°/0°, ±45°, and 0°/90° unidirectional fibers. A second set of tubes was prepared with circular cutouts of 6 mm diameter in the tube walls. A quasi-static axial crushing test was done on the tubes. Crashworthiness indicators, including initial peak load (P_ip), mean crushing load (P_m), energy absorption (EA), specific energy absorption (SEA), and crushing-force efficiency (CFE), were evaluated and statistically analyzed using ANOVA. The results show that the neat tubes generally exhibit higher energy absorption and more stable progressive crushing than the tubes with circular cutouts. The presence of cutouts reduces the initial P_ip, P_m, EA, and SEA, while also changing the failure mode from progressive splaying-dominated crushing to localized micro-buckling, segmentation, sliding, and slicing. Among the tested configurations, samples with 0°/0° plies in the mid-laminate region showed the best crashworthiness performance in both neat and with cutout tubes. These findings demonstrate that both stacking sequence and geometric discontinuity strongly influence the crash response of CFRP tubes and should be considered together in crashworthy design. Full article