This paper proposes an enhanced external store safe separation evaluation process that integrates multi-fidelity analysis methods (empirical, CFD, and test data) with criteria from MIL-HDBK-1763 to support the evaluation and compliance of external store separations. Safe separation criteria are reviewed across multiple standards and handbooks, including MIL-HDBK-1763, MIL-HDBK-244A, AGARD-AG-202, and AGARD-AG-300 to tailor appropriate limits for typical aircraft and store configurations. The enhanced separation analysis (ESA) constructs vertical and horizontal safe zones using these multi-fidelity methods. To validate the process, the GBU-31 bomb released from an F-16 aircraft is analyzed. Evaluation criteria are based on airborne weapon compatibility and safety standards. CFD simulations are conducted to predict the trajectory of the GBU-31 under aerodynamic effects caused by the F-16 fuselage, an external fuel tank, and an adjacent AIM-9M missile. The simulations use accurate input derived from wind tunnel experiments and static test data of the ejection unit. The enhanced evaluation identifies motion trends and potential collision risks by tracking critical points on the GBU-31. These critical points must remain within defined vertical and lateral safe boundaries to ensure a collision-free release. The proposed evaluation method proves to be effective and reliable in analyzing complex separation phenomena. It enhances understanding of weapon-aircraft interactions and reduces the need for extensive flight testing during the development of new or upgraded munitions by leveraging tailored criteria and high-fidelity simulations.
Covalent organic frameworks (COFs) are an emerging kind of photocatalysts which convert CO2 to value-added fuels. However, COFs usually exhibit lower catalytic efficiency without using metal, sacrificial reagent, or photosensitizer due to their easy electron-hole recombination. Herein, a series of imine-linked COFs with different asymmetric linkage structures have been synthesized to enhance the separation efficiency of photoexcited electron-hole pairs in the COFs by tuning the intramolecular built-in electric-field strength. The OH-COF exhibits a high CO production rate of 616 mu mol g(-1) in the 4 h reaction with similar to 100% selectivity, which surpasses most of the metal-free COF photocatalysts reported in the literature. This reveals that the higher polarity of OH-COF with an asymmetric linkage structure leads to a stronger built-in electric-field strength and a faster charge-transfer rate and thus more efficient photocatalytic performance. This work would provide some insights into the built-in electric-field design of COFs for efficient CO2 photoreduction.
Accurate six-degree-of-freedom (6-DOF) calibration of pose measurement equipment is essential for large-scale metrology applications, as measurement precision directly affects downstream processes such as assembly operations. Conventional calibration methods, which typically rely on static multi-point measurements or stepwise fusion strategies, often suffer from complex procedures, low efficiency, and insufficient robustness when faced with intricate object motions. To address these limitations, we propose a high-precision 6-DOF calibration method based on optimized trajectory of a parallel mechanism. A Stewart–Gough platform is employed as the reference system, leveraging its superior repeatability and positioning accuracy to generate precise 6-DOF spatial trajectories. An optimization framework integrating extended B-spline interpolation with an Improved Grey Wolf Optimization algorithm is developed to refine the trajectory design. Leveraging the inherent characteristics of parallel mechanisms, we further develop a decoupling-equivalent calibration strategy and establish a comprehensive pose error identification model for systematic parameter compensation. Extensive experimental validation demonstrates that the proposed method substantially enhances the accuracy of pose measurement equipment, confirming its feasibility and effectiveness in complex motion scenarios. This work provides a promising pathway toward high-precision 6-DOF calibration in aerospace engineering and large-scale equipment manufacturing.
