By considering the exclusion characteristics of foreign objects in a new intake system with a bypass duct for turboprop engines, two kinds of common rigid foreign objects, the grains and metal pieces, are modeled based on airworthiness standards and reference reports. On the assumption that only a perfect elastic collision occurs without any structural damage to the objects or intake walls, a numerical method based on single high-fidelity Computational Fluid Dynamics (CFD) and dynamic unstructured mesh techniques to simulate the 6DOF motion and impacts of the rigid foreign objects is presented. A practical used intake system with a bypass duct is employed to validate the method. According to the tolerance size of the intake, two spherical grains with the radius of 0.037 m and 0.0555 m and a regular hexahedron aluminum metal piece with the dimension of 0.20 m×0.11 m×0.01 × are built to test the exclusion ability of the intake and analyze their effects on the intake performance. The simulation results indicate that, in the cases of a symmetrical flow field, geometry, and initial states, all the rigid foreign objects will move in the intake without lateral motions. The spherical grains without an initial angular velocity only translate in the intake, and the small one finally enters into the bypass duct after four impacts, while the larger one flies into the inner part of the engine after six impacts. The larger grain can lead to a more apparent loss on the intake performance due to the greater shielding effect on the flow field, and the maximum decrements of the total pressure recovery coefficient and mass flow can reach to 2% and 4.1%, respectively; the total pressure distortion rate increases 116%. A coupled motion of translation and rotation occurs for the regular hexahedron aluminum piece, and after four impacts on the intake, it finally excludes to the outer space of the nacelles from the bypass duct. Compared to the spherical grains, the aluminum piece has more significant actions on the intake performance. The maximum losses of the total pressure recovery coefficient and mass flow can be 2.3% and 1.54%, respectively, while the distortion rate increases 518%. Although the numerical method in this study is simple and ideal, it can help researchers obtain quick and effective evaluation results in the initial design stage of the new intake system with a bypass duct for the turboprop engine to improve the design efficiency and level.

Accurate target recognition of unmanned aerial vehicles (UAVs) in the intelligent warfare mode relies on a highly standardized UAV knowledge base, and thus it is crucial to construct a knowledge graph suitable for UAV multi-source information fusion. However, due to the lack of domain knowledge and the cumbersome and inefficient construction techniques, the intelligent construction approaches of knowledge graphs for UAVs are relatively backward. To this end, this paper proposes a framework for the construction and application of a standardized knowledge graph from large-scale UAV unstructured data. First, UAV concept classes and relations are defined to form specialized ontology, and UAV knowledge extraction triples are labeled. Then, a two-stage knowledge extraction model based on relational attention-based contextual semantic representation (UASR) is designed based on the characteristics of the UAV knowledge extraction corpus. The contextual semantic representation is then applied to the downstream task as a key feature through the Multilayer Perceptron (MLP) attention method, while the relation attention mechanism-based approach is used to calculate the relational-aware contextual representation in the subject–object entity extraction stage. Extensive experiments were carried out on the final annotated dataset, and the model F1 score reached 70.23%. Based on this, visual presentation is achieved based on the UAV knowledge graph, which lays the foundation for the back-end application of the UAV knowledge graph intelligent construction technology.

Several new systematic methods for high fidelity and reliability calculation of static and single dynamic derivatives are proposed in this paper. Angle of attack step response is used to obtain static derivative directly; then translation acceleration dynamic derivative and rotary dynamic derivative can be calculated by employing the step response motion of rate of the angle of attack and unsteady motion of pitching angular velocity step response, respectively. Longitudinal stability derivative calculations of SACCON UCAV are taken as test cases for validation. Numerical results of all cases achieve good agreement with reference values or experiments data from wind tunnel, which indicate that the proposed methods can be considered as new tools in the process of design and production of advanced aircrafts for their high efficiency and precision.