Reliable thermal-to-visible localization requires verifying whether geometrically consistent matches identify the correct map region. We present Provenance-Isolated Verification of Observation Transport (PIVOT), a predictive verifier that selects among direct, temporally transported, and fused correspondence sources. All occurrences of each persistent map-point identity are assigned to the same fold. Candidate poses are fitted on complementary folds and assessed on held-out observations using a marginalized inlier–outlier likelihood, followed by an all-observation refit of the selected source. On 898 aerial Multi-View Thermal–Visible (MTV) queries, PIVOT achieves 67.82% success at 0.02d/5°, improving direct localization by 5.68 percentage points and unconditional fusion by 3.90 points. It also exceeds the tested transport-aware bundle-adjustment control using the same transported map points. On 300 disjoint Vision for Visibility Dataset (ViViD++) queries, the predeclared PIVOT-Seq obtains 63 successes at 10 m/5°, compared with 61 for direct localization and 62 for fusion. The exploratory core analysis also obtains 63 primary successes, numerically exceeding fusion. The MTV improvement is obtained through per-frame source selection without temporal decoding or scene-specific selector training. The in-sample MTV selector reaches 628 primary successes, so cross-fitting protects against identity reuse rather than maximizing the measured accuracy. The demonstrated gains and the small exploratory external advantage warrant further independent aerial and sensor validation.
Lateral intakes generate distorted inflow and complex swirl structures upstream of axial fans. Steady and unsteady numerical simulations were performed to investigate the coupled flow field between a lateral intake and an axial-fan rotor. The local normalized axial mass-flux factor φ, together with swirl descriptors, was employed to characterize the flow structure. The results show that swirl distortion at the aerodynamic interface plane (AIP) exhibits distinct radial stratification and circumferential non-uniformity, and that these characteristics vary with operating conditions. The circumferential non-uniformity is associated with the lateral-intake inflow, whereas the pronounced near-tip variation is consistent with an increasing influence of rotor-related tip flow structures at lower flow rates. In the unsteady analysis, periodic fluctuations of φ, SD, and SI vary with spanwise and circumferential location and are strongest near the blade tip. A non-zero frequency component between the rotational frequency and blade-passing frequency is identified in φ, SD, and SI over the entire blade span rather than being confined to the tip region. It indicates that the component is likely associated with the interaction between the circumferentially non-uniform intake flow and the rotor motion. These findings provide a basis for further investigation of rotor aerodynamic loading under distorted inflow conditions.
Free-floating space manipulators exhibit strong dynamic coupling between the robotic system and its spacecraft base, where configuration transitions may generate significant base-attitude disturbances. This paper proposes a constrained trajectory-planning framework using eighth-order Bézier curves, in which boundary conditions of position, velocity, and acceleration are analytically satisfied through endpoint control points, while intermediate control points are optimized under joint constraints. To solve the resulting nonlinear constrained optimization problem, a Position–Velocity Hierarchical Command Cone Search Optimizer (PV-HCCSO) is developed. The proposed optimizer integrates a hierarchical search architecture, representative-guided multi-region exploration, adaptive cone search, position–velocity cooperation, and stagnation-aware diversity-restoration mechanisms. Numerical simulations of a 7-DOF free-floating space manipulator demonstrate that the generated trajectories satisfy all kinematic constraints while effectively suppressing terminal base-attitude disturbances. Compared with WCA, PSO, and CPO, PV-HCCSO achieves reductions of 93.89%, 85.31%, and 81.96% in the mean final fitness value, respectively. Statistical analysis over 40 independent trials confirms significant performance improvements (F = 33.705, p < 0.001). Furthermore, evaluations on the 20-dimensional CEC2022 benchmark suite show superior optimization capability with an average rank of 1.28. The results demonstrate the effectiveness and robustness of PV-HCCSO for constrained trajectory planning of free-floating space manipulators.
The flowpath configuration of a scramjet combustor decisively governs its combustion performance. Scramjet combustors are generally classified into rectangular and circular cross-section types. For circular cross-section combustors, numerous flowpath configurations have been proposed worldwide, accompanied by extensive numerical simulations and experimental investigations. This paper systematically reviews proper flowpath configurations for circular cross-section scramjet combustors. It first discusses wall configurations, then examines cavity flameholders, strut flameholders, and other flowpath arrangements. Key geometrical parameters, including wall shape, cavity geometry, strut layout, and their coupling effects, are considered. The influences of these configurations on combustor performance are briefly analyzed, with particular attention to fuel mixing, flame stabilization, and combustion efficiency. Finally, the current research status of circular scramjet combustor geometric design is summarized, and future development prospects are outlined. By consolidating existing knowledge and identifying remaining challenges, this review aims to provide a useful reference for the optimal design of circular cross-section scramjet combustors and to support further advances in high-performance propulsion systems.
This study develops a graded-compliance, metal-packaged fiber Bragg grating (FBG) strain sensor for cryogenic structural health monitoring of metallic propellant tanks and pipelines on reusable launch vehicles (RLVs). The serially connected frame enables customizable sensitivity and expands the effective measurement range via strain desensitization for large-magnitude cryogenic strains. This design reduces interfacial shear stress and improves long-term stability under cyclic cryogenic loads, while glass brazing fixation avoids the failures associated with organic adhesives. The ground characterizations down to 77 K show high linearity (R2 > 0.998) over −4000 to 6000 με. The tensile sensitivity decreases by approximately 4.3% from room temperature to 77 K, with a tension–compression sensitivity discrepancy of 2.4% under cryogenic conditions. The limited sensitivity drift across 77 K–123 K and favorable batch consistency support a unified full-temperature-range sensitivity calculation method, reducing the onboard computational burden. Within the cryogenic operating range of 77 K–123 K, the maximum full-scale error is ±1.01%. Batch-produced sensors have passed environmental qualification tests, and units from different batches were deployed in three independent RLV flight campaigns in 2024, 2025, and 2026. Continuous and stable strain signals were obtained during ground propellant loading and in-flight phases under severe thermo-mechanical loads, consistent with the theoretical predictions.
