To clarify the relationship between offshore floating photovoltaic (FPV) platform motions and mooring loads under combined wind and wave conditions, a numerical model based on three-dimensional potential flow theory was established to study the dynamic responses of a 4 × 4 offshore FPV array. Time-domain statistics and spectral analysis show that higher wind speed increases the mean surge offset. As wind speed rises from 10 to 15 m/s, the maximum and standard deviation (STD) of mooring line tension increase by 59.4% and 117.8%, respectively, while the low-frequency surge response weakens. Higher turbulence intensity increases the low-frequency peaks in the surge and mooring line tension spectra. As the spectral peak period increases, the heave and pitch spectral peaks shift toward lower frequencies. The wave-frequency surge response also becomes more pronounced. Higher significant wave heights amplify heave and pitch motions and mooring line tension, while weakening the low-frequency surge response. Across all cases, the end platforms have larger heave ranges; as surge displacement increases in the wave propagation direction, the wave-facing platform descends slightly and the wave-sheltered platform rises.
The choice between diesel and electric propulsion is an operational decision that requires no additional hardware, yet its effect on the infrared signature of a naval vessel has not been quantified in full-scale sea trials reported in the open literature. This case study compares the infrared radiation intensity of a single naval vessel under diesel and electric propulsion in the mid-wave (MWIR, 3–5 μm) and long-wave (LWIR, 8–12 μm) bands, under solar-exposed and solar-free conditions, with each measurement case recorded by a radiometrically calibrated system during a single continuous 0–360° turn. Under solar exposure, the diesel-to-electric ratio of median intensity was 1.31 in MWIR and 1.15 in LWIR, with a median angular reduction of 22–27% under electric propulsion; the LWIR result was more sensitive to the segmentation threshold than the MWIR result. Without solar exposure, the relationship persisted in MWIR (1.27) but reversed in LWIR (0.87). The solar-exposed and solar-free measurements differed in time of day and ambient conditions, and a sister vessel, measured only under solar exposure and under a different illumination geometry, showed the same overall direction but is used only qualitatively; the results are therefore specific to the observed acquisitions. The effect of propulsion configuration on radiation intensity depended jointly on spectral band and solar condition. Detection range and probability of detection were not assessed; the results nonetheless support further investigation of propulsion configuration as a potential operational variable in naval infrared signature management.
Reconstructing links between basin-margin fan deltas and submarine fans requires evaluating compositional similarities within a depositional framework. This study integrates 3D seismic data, drilling records from 31 wells, and core observations with heavy-mineral data from 89 samples in 17 wells, lithic-fragment counts from 30 samples in 10 wells, and published detrital zircon age spectra from eight wells in the Upper Huangliu Formation, Yinggehai Basin. Three basin-margin belts exhibit spatial differences in heavy-mineral assemblages, heavy-mineral indices, lithic compositions, and zircon age spectra. Several margin-proximal submarine fans retain affinities with adjacent fan deltas, whereas basin-interior samples show both overlap with and departures from these references. Proximity alone therefore cannot explain all preserved compositions. The western gentle-slope configuration involves sediment transfer toward the depression, whereas the eastern slope-break configuration includes slope and slope-foot accumulation. Core and seismic observations support gravity flows as the primary depositional mechanism and suggest possible local bottom-current reworking. However, traction structures and erosional geometries also permit gravity-flow interpretations and do not establish regional sediment redistribution. The resulting qualitative source-to-sink model links basin-margin supply, paleotopographically constrained transport, and intrabasinal accumulation, providing a framework for interpreting submarine-fan composition and sand-body distribution.
Autonomous underwater vehicle (AUV) capture requires a mechanism to accommodate initial impact and then secure the hull through compliant contact. This study implements a rigid-compliant system that combines a hydraulic-buffered guidance dock with an endoskeleton-reinforced compliant locking mechanism. Building on an earlier numerical study of the guidance dock, the present work adds the locking mechanism, comparative component tests, and integrated water-tank experiments. Adams–AMESim co-simulation evaluates guidance and impact response, while Abaqus analysis and component tests assess the reinforcement effect. At 600 kPa, reinforcement increased the measured underwater vertical clamping force from 260 to 410 N, or 57.7%. Nine of ten tank trials established bow–dock contact at measured speeds of 0.76–0.85 m/s and completed guided buffering, pose adjustment, and locking; one trial missed the guidance region. The baseline simulation predicted a 94.8% reduction in peak contact force relative to a constrained unbuffered dock. The results demonstrate a staged capture system in which separate mechanisms accommodate initial impact and develop compliant clamping force, under fixed-platform, operator-supervised conditions.
The real-time monitoring of global sectional loads is crucial for the safety assessment of ship hulls during operation, yet it remains a significant challenge due to the complexity of the structure and the marine environment. Direct measurement of hull global sectional loads remains difficult in practical engineering, whereas local strain responses can be conveniently obtained using strain gauge. This paper presents an analytical physics-driven load conversion framework to reconstruct global sectional load components from limited longitudinal strain measurements for full-scale ship hull structures. A load conversion matrix is established based on a linear superposition of strain components from vertical bending, horizontal bending, axial force, and warping torsion. The method is first validated on a simplified U-shaped beam using finite element analysis, identifying optimal sensor arrangements. It is then extended to a uniform beam with the complex midship section of a 21,000 TEU containership, where its accuracy is further confirmed under both static and dynamic periodic loading conditions. Finally, the proposed method is validated against CFD-FEM coupled simulation results for the containership under regular head waves and oblique short-crested irregular waves. This study provides a feasible analytical tool for reconstructing hull girder sectional loads using sparse local strain monitoring data, which can be used in applications such as full-scale ship structural health monitoring and global strength assessment.
