To ensure the normal operation of turbine blades Facing continuously increasing turbine inlet temperatures， the development of more efficient cooling technologies has become particularly urgent. Ceramic matrix composite （CMC） transpiration cooling technology combines the excellent high-temperature resistance of CMC with the efficient heat dissipation potential of transpiration cooling， showing broad application prospects in future thermal protection of turbine blades. However， the strong anisotropy of CMC materials and their complex internal porous structure pose significant challenges for the thermal analysis of the transpiration cooling process， and the underlying flow and heat transfer mechanisms remain unclear. This review summarized recent research progress on the anisotropic thermal conductivity and microporous seepage characteristics of CMC， analyzed key existing problems and challenges in current studies， and offerd suggestions for establishing a comprehensive design framework for CMC turbine blade transpiration cooling structures.
To investigate the influence of assembly deviations on pipeline sealing performance， a finite element model was established based on the torque-tension relationship. The influence of three assembly deviations （axial，radial， and angular） acting individually on the sealing performance of pipeline connectors was analyzed， and the coupling influence of these three assembly deviations on the sealing performance of pipeline connectors was studied through orthogonal experiment. The results indicate that under single deviation conditions， negative axial deviation，radial deviation，and angular deviationall reduce pipeline sealing performance. When the three assembly deviations are coupled， the sealing performance decreases. Negative axial deviation and angular deviation have significant influences on pipeline sealing performance， while the influence of radial deviation is relatively small. Therefore， in practical engineering， negative axial deviation and angular deviation should be strictly controlled， and positive axial deviation and radial deviation should be minimized as much as possible.
To systematically investigate the mechanisms of thermal degradation and damping effects on panel flutter boundaries and responses， an aeroelastic model incorporating thermal degradation and damping terms was developed， followed by a sensitivity analysis of key parameters based on stability criteria. Firstly， based on the von Kármán plate large deformation theory， the Kelvin damping model， and the first-order piston theory， a two-dimensional supersonic panel dynamic equation was established. This equation considered thermal degradation and damping effects. Spatial discretization was achieved using the Galerkin method. Next， the Lyapunov indirect method and the Routh-Hurwitz criterion were used to obtain stability region diagrams for various degrees of thermal degradation. This identified the number and stability of equilibrium points in each region. Finally， the nonlinear ordinary differential equations were solved using the fourth-order Runge-Kutta method to determine the panel’s nonlinear aeroelastic response. This response was analyzed using nonlinear dynamic tools， such as time history plots， phase trajectory diagrams， and bifurcation diagrams. The results indicate that both thermal degradation and material damping significantly reduce the stability region of the panel. Panel thickness also influences the stability region. An increase in the thermal degradation coefficient not only amplifies the panel’s vibration amplitude but also causes the bifurcation points to appear earlier， accelerating the bifurcation evolution process. Furthermore， thermal degradation significantly increases the diversity of panel response types and their sensitivity to system parameters. In addition， material damping effectively suppresses the panel’s quasi-periodic and chaotic vibrations responses.
In response to the need for rapid iteration in the conceptual design stage of propeller aircraft， low-fidelity aerodynamic evaluation methods， such as the vortex lattice method was a more suitable choice. In order to obtain suitable computation parameters and quantitative errors， the NASA OpenVSP unsteady vortex lattice method （UVLM） was studied using the propeller standard model， and the computation characteristics of the multiple reference frame quasi-steady vortex lattice method （MRF-VLM） were presented for the first time. The computational convergence and error characteristics were analyzed using the APC electric-propeller standard model， and the grid/iterative parameter settings that take into account both computational stability and efficiency were obtained. The comparison with experimental data shows that with appropriate grid and iterative parameters， the computation errors for the propulsion efficiency of the above two methods are within 6.1% and 3.6% respectively， under conditions of low pitch angle and medium advance ratio. The accuracy meets the requirements of the conceptual design stage， and the MRF-VLM computation with 4-thread parallel processing takes only 4 minutes， which is more efficient. The case of NACA 5868-9 propeller standard model further verify the computational reliability of the MRF-VLM method. The above research results can provide a reference for the reliable engineering application of OpenVSP VLM. However， due to the limitations of the linearized potential flow theory of the VLM， the above two methods can not accurately simulate the strong flow nonlinearity under high pitch angle and high/low advance ratio， and the computation accuracy needs to be improved.
To improve the calculation accuracy of the overall performance model， a overall performance modeling method for aero-engines with primary and secondary flow integration was investigated. Through research on principles for aero-engine performance calculation， the influencing factors of secondary flow on the primary flow thermodynamic cycle were comprehensively identified. Their mechanisms of action were clarified. A characteristic model of the impact of secondary flow on the primary flow thermodynamic cycle was constructed. Based on the traditional modeling framework， this method innovatively introduced a coupling calculation mechanism for secondary flow rate， energy， and mixing terms with the primary flow thermodynamic cycle. Using this method， an overall performance calculation model was developed for a specific aero-engine. The results show that， compared to traditional models， the proposed method achieves a 1.4% improvement in thrust calculation accuracy， a 1.33% enhancement in fuel consumption rate prediction， and a 2.7% increase in turbine inlet temperature estimation accuracy， significantly optimizing the precision of the overall performance calculation model for aero-engines.
Aiming to address the limitations of traditional health monitoring methods of hydraulic oil pump truck testbed， such as reliance on periodic physical inspections and maintenance， low levels of informatization， and insufficient production efficiency， an application development architecture for a hydraulic oil pump truck monitoring system was proposed based on digital twin technology. This architecture integrates data， models， and communication to improved the predictive maintenance level and operational efficiency of the equipment. The research enabled real-time data interaction and fusion between the physical equipment and the virtual model by constructing a digital twin virtual model of the equipment and utilizing the TCP/IP protocol and a unified JSON packet format. On this basis， the system could perform simulation， numerical prediction， fault diagnosis， and early warning for the hydraulic oil pump truck testbed， thereby optimizing the equipment’s operation status.Test results show that the system is able to perform health monitoring and fault diagnosis for the hydraulic oil pump truck， showing broad prospects in the application of aviation testbed.
To improve visual tracking precision for friction stir welding under weld seam occlusion and other interference， a weld seam feature tracking algorithm based on the ECO-HC was proposed. A traditional image processing technology was employed to detect the initial weld seam feature point， while enhancing the sensitivity of the algorithm to abnormal disturbances by introducing a dual confidence assessment mechanism comprising similarity calculation and peak to sidelobe ratio on the basis of the ECO-HC algorithm. Additionally， a trajectory prediction method based on curve fitting was proposed to achieve the relocalization of lost target. Experiments were conducted on aluminum alloy weldments of varying thicknesses. The experimental results show that the mean absolute error of the weld seam tracking system proposed can be maintained within 0.051 mm， which fully meets the precision requirement for weld seam tracking and demonstrates the effectiveness of the algorithm proposed.
To address the collaborative search task planning issue for unmanned aerial vehicles （UAV） and unmanned ground vehicles （UGV） in search and rescue scenarios， a method that combines centralized task allocation with independent path planning was proposed. Firstly， tasks were clarified based on requirements and assigned to UAV and UGV. Firstly， the UAV and UGV conducted trajectory planning and path planning independently according to their assigned tasks. For the task allocation problem，a multi-objective area segmentation and allocation model based on task types was proposed，and an adaptive hybrid algorithnm incorporating genetic algorithm and tabu search was developed in solution.For trajectory planning， a “traveling salesman path-area coverage path planning” model was constructed based on the task requirements of the UAV， employing an improved genetic algorithm that introduced an “S”-shaped path as the initial population and designed a fitness function to optimize the selection process. Regarding the path planning for UGV， a method that combines A* algorithm with artificial potential field algorithm was proposed to find the optimal traveling path. Simulation results indicate that the proposed algorithm effectively completes search tasks and shows significant improvements in both task execution efficiency and path planning accuracy compared to commonly used genetic algorithms and A* algorithms.
To solve the problem of high false detection rates in tunnel fire detection caused by the complexity of tunnel environments based on the YOLOv8n network model， an improved tunnel fire detection algorithm was proposed.First， in the backbone network， the FasterNet network was used for replacement while retaining the original SPPF module to achieve more comprehensive feature extraction； Secondly， in order to improve the detection accuracy of the model for irregular targets in the complex background， the D-LKA attention mechanism was introduced in the C2f module； Finally， Focaler-IoU to optimize the model loss function was introduced， which further reducing the problem of false positives or false negatives caused by distractors. The experimental results show that compared with YOLOv5， YOLOv7 and the original models of YOLOv8n， the accuracy of the improved model is increased by 7.6%， 5.6%， and 3.5% respectively， and the average accuracy means are increased by 8.3%， 7.7%， and 5.1% respectively. Compared with other YOLOv8n-based improved algorithms， the mean average precision of our proposed model is increased by 3.3% and 6.4% respectively.
In order to study the influence of obstacle distribution on the flow characteristics of ultrafine dry powder fire extinguishing agent in confined space，a fluent software was used to establish a two-dimensional transient simulation model of gas-solid two-phase flow in the confined space after the release of ultrafine dry powder extinguishing agent， and the spatial flow characteristics of ultrafine dry powder were simulated under the conditions of different layers of obstacles and spatial locations. The results show that both the layer number and distribution of obstacles have a more significant influence on the spatial flow and distribution of ultrafine dry powder. In the early stage of spraying， the concentration of the area under the middle obstacle is significantly lower than that of the other obstacles， while the side obstacles have a more significant influence on the time required to reach the fully submerged fire extinguishing agent in the space. The number of layers of obstacles has a significant influence on the total flooding state of ultrafine dry powder fire extinguishing agent， single-layer obstacles to a certain extent is conducive to speeding up the confined space to achieve the state of total flooding of fire extinguishing agent， while multi-layer obstacles is just the opposite， and with the increase in the number of layers of obstacles， the longer the time required to reach the state of total flooding.
