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Shot PeeningAMS2430V (Current)11/2/2026
This specification covers the requirements for shot peening of surfaces of parts by impingement of media, including metallic, glass, or ceramic shot.
AMS B Finishes Processes and Fluids Committee
HER-DETR: Lightweight UAV Object Detection Based on High-Frequency Enhancement and Multi-Scale Sparse Fusion2026-99-233610/30/2026
The rapid growth of the low-altitude economy has accelerated the deployment of unmanned aerial vehicle (UAV) technology in a wide range of applications, including power infrastructure inspection and disaster relief operations. These scenarios impose stringent real-time processing demands on onboard vision systems. However, aerial images are characterized by a high density of small and distant targets, which significantly weakens feature representation quality, and current state-of-the-art detection models carry substantial computational overhead that conflicts with the limited hardware resources available on embedded UAV platforms. This paper addresses both challenges simultaneously by proposing a novel lightweight, end-to-end detection framework designated the High-frequency Enhancement Retentive Detection Transformer (HER-DETR). The framework introduces three coordinated technical contributions. First, a lightweight backbone network termed the Cross Stage Partial High-frequency Enhancement Network is constructed. This backbone integrates a cross-stage high-frequency residual enhancement mechanism to alleviate feature attenuation commonly observed in small-target scenarios. Second, a Depthwise Intrascale High-Low Feature Interaction block is designed for intra-scale feature interaction at the highest semantic level, strengthening fine-grained representation through a dual-frequency decoupling strategy. Third, a Retention Feature Fusion module is developed as the core cross-layer feature fusion component, enabling bidirectional multi-scale feature integration via a lightweight sparse attention mechanism. Comprehensive experiments on the VisDrone2019 and HIT-UAV benchmark datasets confirm that HER-DETR achieves state-of-the-art performance. Compared with the RT-DETR-r18 baseline, the proposed framework improves mean average precision at a 0.50 intersection-over-union threshold by 2.0 percentage points on VisDrone2019 and by 1.6 percentage points on HIT-UAV, while simultaneously reducing model parameter count and computational floating-point operations by 41.6% and 35.3%, respectively. These results validate the framework’s capability to balance detection accuracy and computational efficiency for real-time UAV deployment.
Jiao, Minghai, Liang, Yinghan, Zhang, Ende, Kan, Shuang
Prediction of Aero-Engine Exhaust Gas Temperature Using iTransformer2026-99-233510/30/2026
Exhaust gas temperature (EGT) is one of the key parameters for evaluating the thermal state of an aero-engine during flight operations. Precise EGT predictions are important in both managing engine health and optimizing performance. However, the nonlinear interactions among multiple operating parameters pose challenges for conventional prediction methods. An approach to EGT prediction presented in this paper is based on the iTransformer architecture. Unlike conventional time-series models that process temporal observations as tokens, this algorithm works with every single variable like a unique token and encodes the entire historical sequence of each variable. This design enables the model to capture inter-variable dependencies directly, thus increasing its power to capture multivariate time series. Two different datasets were used to validate the proposed approach and compared to various commonly used prediction models. The results indicate that iTransformer gives smaller prediction errors when the same conditions are met with MAE values of 0.5525°R and 0.4539K both on the two datasets. Despite the overall satisfactory performance, some prediction mismatches can be observed under extreme fast changing conditions of the engine operation. These results demonstrate that the proposed method can effectively characterize the complex interactions among engine variables and has potential for practical EGT prediction applications.
Hao, Mengfu, He, Yongbo, Li, Yifan
Geosynchronous Orbit Satellite Maneuver Detection Method Based on Dual-Model Parallel GLRT2026-99-236710/30/2026
Ground-based radar can obtain high-precision radial velocity measurements through coherent integration Doppler processing, providing an important data source for geostationary orbit (GEO) satellite maneuver detection. An orbital maneuver causes a persistent mean shift in radial velocity residuals, whereas attitude motion or tumbling due to malfunction induces velocity scintillation, which manifests as a sudden variance amplification. Since both anomalies cause velocity residuals to deviate significantly from normal levels, a single detection model can easily misclassify one as the other. To address this problem, a maneuver detection method is proposed that combines precise orbit determination with a dual-model parallel Generalized Likelihood Ratio Test (GLRT). A high-accuracy initial state is first obtained through the Gibbs method and weighted least squares. Two detection models are then constructed based on distinct residual characteristics: mean shift for maneuver detection and variance amplification for scintillation detection. An ε-contaminated Gaussian mixture GLRT detector is introduced to suppress the influence of outliers. Combined with Monte Carlo threshold calibration and a maneuver-priority competitive decision strategy, the method effectively distinguishes between the two anomaly types. Simulation results demonstrate that under strict false alarm constraints, the detection probability for both maneuvers and velocity scintillation exceeds 0.9, effectively eliminating mutual misclassification. The method achieves stable detection of weak maneuvers lasting tens of seconds with radial velocity increments of approximately 0.03 m/s, demonstrating strong engineering application potential.
Chen, Xiaoyi, Tang, Fujie, Zhang, Xianbo, Cong, Yang, Gao, Kaili, Chen, Defeng
Investigation on Dynamic Expansion Response and Structural Safety Assessment of Typical Polygonal Fabric Gasbags2026-99-233710/30/2026
The geometric structure of a gas bag has a profound effect on its effectiveness in transferring energy and reliability of its structure when rapidly expanding. Even though there have been considerable improvements in high-performance composite materials such as Kevlar, the transient dynamic reaction and possible rupture mechanisms associated with particular polygon shapes have been greatly unexplored. In this paper, we focus on conventional polygonal gas bags, and perform extensive inflation tests using high-accuracy transient data recorders to monitor the development of the dynamic pressure. In order to overcome the limitations of physical testing, a highly non-linear dynamic finite element model - based upon the application of the *MAT_FABRIC material model in LS-DYNA - is used. This technique allows the systematic examination of how changes in geometric parameters affect the performance of payload dispersion and membrane stress distribution. The results indicate unique ways of deploying depending on their geometry. The circular gas bags are capable of obtaining a velocity of the payload of 4.23 m/s but have high stress concentrations of up to 426 MPa due to the lack of geometric boundaries which make them prone to tearing failure. Rectangular gas bags with very large aspect ratios will experience a tubular expansion deformation that causes energy transfer efficiency to plummet; the release speed of these types of gas bags falls below 2.77 m/s. Ultimately, the optimal structural design is a regular hexagonal shape that optimally balances work performance and structural safety. It can keep good levels of energy transfer efficiency with a final release velocity of 4.12 m/s. Moreover, it successfully stops the continuous hoop tension and reduces the peak stress by around 46 percent through straight edge boundary constraints. This complete research offers an adequate scientific foundation to the anti-burst design of sophisticated polygonal gas bags.
Wang, Jinwei, Shi, Lv, Hou, Jingjing, Li, Yilong, Li, Dailin, Liu, Zhiyi
Study on Heat Transfer Characteristics of Supercritical Aviation Kerosene in a Rectangular Wavy Microchannel2026-99-234710/30/2026
In a conventional turbine-based combined cycle (TBCC) engine, the hot-end components and combustor wall surfaces bear extreme high- temperature thermal loads. To address this issue, researchers have been consistently exploring optimized cooling and heat transfer schemes. Relevant studies have shown that using aviation fuel as a heat sink can achieve effective thermal protection for such aero- engines. This paper carries out a numerical study on the flow and heat transfer characteristics of supercritical RP-3 aviation kerosene in a rectangular wavy microchannel, with a focus on the impacts of the wavelength-to-height ratio on heat transfer performance. The results show that the geometric structure of the wavy microchannel induces intense flow disturbances, which strengthen the internal energy exchange of the fluid and produce both longitudinal and transverse vortices. These vortices break and compress the thermal boundary layer, thus significantly enhancing the intensity of heat transfer. At the same time, the overall heat transfer performance is improved remarkably with relatively low resistance coefficients. Such excellent heat transfer characteristics can effectively mitigate thermal damage to high-temperature components, which is conducive to a notable improvement in their service life and operational safety.
Kou, Zhihai, Li, Xiangqiao, Wang, Xingbo
Process and Performance Optimization Design of Metal-3D Braided Composite Joint Structures2026-99-234910/30/2026
The sleeve is the key assembly part of the high-speed internal electric spindle support of the high-precision CNC internal and external grinder, and its machining accuracy directly affects the running state of the spindle. The purpose of this study is to adjust the structural process to improve its bearing capacity in all directions. Combined with the refined mechanical simulation of 3D braided composites, the influence mechanism of joint thickness and surface pretreatment on the connection performance is studied from the aspects of stress distribution characteristics and damage failure mechanism. The overall performance analysis and design of the metal-composite sleeve are carried out. Experiments show that the thickness of the joint has a great influence on its bearing performance, and the effectiveness of the proposed pretreatment process is verified, which provides a reliable technical path for the realization of high-performance metal-3D braided composite connection structure.
Wang, Zijun, Chi, Xinfu, Li, Chengen, Li, Dinghua
Study on the High-Temperature Creep Behavior of Ti-1100 Alloy2026-99-234410/30/2026
This study investigates the creep response of the high-temperature titanium alloy Ti-1100 over a temperature range of 550-700 °C under applied stresses varying from 150 to 450 MPa. Under different combinations of stress and temperature, the creep rate, stress exponent, and activation energy for creep were determined using the Arrhenius relationship, while the corresponding creep characteristics and microstructural changes were examined through optical microscopy (OM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The findings indicate that an alloy is highly sensitive to temperatures and stresses when subjected to long-term creep. At the temperature of 550-700 °C, the Ti-1100 alloy has relatively high creep activation energy when subjected to an applied stress of 300 MPa. For the Ti-1100 alloy, the stress exponent was determined to be 5.33 within the stress interval of 150-450 MPa at 600 °C. When considered alongside the observed microstructural characteristics, this result indicates that dislocation climb serves as the primary mechanism controlling creep during prolonged exposure. Within the investigated temperature and stress window, creep deformation in Ti-1100 gives rise to localized regions with elevated residual stress, and this tendency becomes more pronounced as both temperature and applied stress increase. These areas are likely to grow and evolve into microcracks, thus contributing to the microstructural instability of the alloy.
Yongquan, Yang, Lihui, Yang, Feng, Du, Baohui, Zhu, Xiaochen, Hu, Lihua, Shen, Jianfeng, Li, Shaofu, Kang
Self-Regulation of Force in the Space Truss-Type Deployable Structure Based on Magnetic-Electric Material2026-99-234110/30/2026
Under on-orbit disturbances, large space truss-type deployable structures readily undergo vibration. Such vibration may degrade pointing accuracy and positioning precision. As a countermeasure, an internal-force self-regulation method is proposed using a magnetoelectric self-sensing actuator. This actuator combines Terfenol-D with piezoelectric material, thereby realizing force output and self-sensing. It can be placed at critical truss joints. By exploiting the ΔE and Villari effects of magnetostrictive materials, a resonant-force self-sensing mechanism is established. The actuator model is then integrated into the deployable truss’s dynamic model, and an LQR-based active vibration suppression strategy is derived. Simulation results show that the actuator detects static and dynamic output forces. Over a specific magnetic field range, sensing behavior exhibits an approximately linear dependence on the output force. Control outcomes confirm effective suppression of structural vibration, reduced response amplitudes at key nodes, and enhanced structural stability. Therefore, a novel method for vibration suppression in large deployable truss-type space structures is provided by these findings.
Xie, Dongjian, Ni, Xiaofeng, Cheng, Lei, Cui, Qifeng, Zhang, Yahui
Adaptive Regulation of Micro Closed-Loop Space Station Ecosystems Using Proximal Policy Optimization2026-99-233810/30/2026
Long-term orbital missions require highly independent life-support systems, maintaining ecological stability under limited external support and subsystem attenuation. Conventional strategies are typically based on fixed threshold rules or deterministic mass-balance models and cannot adapt to disturbances or multi-objective trade-offs between resource safety and environmental load. This paper proposes a reinforcement learning framework for managing micro closed-loop ecological systems under reliability decay and environmental constraints. A reinforcement learning controller based on Proximal Policy Optimization (PPO) is trained to learn stable regulation policies with random disturbances. A dynamic state model is constructed to describe the coupled and time-sequential elements, ranging from water storage, oxygen concentration, energy reserve, subsystem reliability to ecological load. Degradation propagation is integrated into the transition dynamics through reliability-dependent recycling efficiency. Simulation experiments demonstrate that the proposed policy maintains all resource variables within the safety margins while reducing ecological imbalance compared with traditional strategies. Consequently, the proposed framework provides an expandable control architecture for independent regulation of space station life-support systems.
Zhang, Heyang, Wu, Meixin, Xie, Junze
Research on Trajectory Planning Based on High-Precision Improved C-W Equation2026-99-232910/30/2026
In today’s space environment, the number of tumbling objects such as abandoned satellites, uncontrolled spacecraft, and space debris has increased dramatically. Therefore, in-orbit services such as maintenance, recovery, and capture of rolling targets is an urgent topic that needs to be explored. In this paper, for the mission of spacecraft approaching the tumbling target at close range, the trajectory planning method is studied by using the high-precision relative equation of motion as the orbital dynamic model. Firstly, the error of the relative equation of motion of the center of mass is analyzed, and a method to improve the accuracy of the C-W (Clohessy-Wiltshire) equation is considered to construct a higher-precision orbital dynamics model. The constraints such as attitude dynamics, line-of-sight range, control ability and keep-out zone are mathematically described, and the optimal control problem of pose synchronization is established. On this basis, this paper takes the traditional C-W equation and the improved C-W equation as the relative motion models of the centroids, and, based on the adaptive pseudospectral method and sequential convex optimization, solves the position and attitude synchronization planning problem. This article focuses on analyzing the errors of the C-W equation before and after improvement, as well as the impact of linearization on these errors, studies the accuracy improvement brought by the improved equation and the safe obstacle avoidance of position and attitude trajectories, and compares the advantages and disadvantages of the two methods. Simulations verify the accuracy and efficiency of this trajectory optimization algorithm and confirm the accuracy improvement of the improved C-W equation. The improved C-W equation has significant application potential in trajectory planning tasks in complex orbital environments with high-precision requirements.
Zhang, Chao, Yao, Zihao, Gou, Jingwen, Zhang, Yumei, Wang, Yuzhi, Li, Shunli
Synergistic Enhancement of Impact Resistance in SiCw-Polymer Composite2026-99-232510/30/2026
Addressing the performance degradation bottleneck of conventional impact-resistant materials under complex operating conditions, and the limitation of existing research focusing primarily on enhancing single properties while neglecting material equilibrium, this study employs silicon carbide whiskers (SiCw) as the reinforcing phase. Through surface modification techniques, SiCw/celluloid and SiCw/polyimide dual-polymer composite systems were constructed and systematically investigated. Surface modification of SiCw was achieved using titanate and silane coupling agents. Through mechanical testing and X-ray photoelectron spectroscopy (XPS) characterisation, the effects of SiCw loading and modification treatments on composite mechanical properties and interfacial bonding were analysed. Results indicate that SiCw introduction significantly enhances the tensile, flexural, and impact strength of the polymer matrix, with optimal addition ratios identified: 6% for the celluloid system and 1.0% for the polyimide system. Surface modification further optimises toughening effects by reducing surface oxide layers and impurities on SiCw particles while strengthening interfacial bonding. This study provides practical guidance for the system design of high-performance impact-resistant composites. The resulting materials hold broad application prospects in sectors demanding high structural impact resistance, such as aerospace and transportation.
Xue, Kaiming
Research on Dynamic Response and Impact Resistance of Airport Pavement Made of Gradient Carbon Fiber Reinforced Composites2026-99-234610/30/2026
Aiming at the engineering problems of easy cracking and insufficient impact resistance of traditional airport concrete pavement under complex dynamic loads, this paper studies the application of functionally graded carbon fiber reinforced polymer ( FG-CFRP) in airport pavement. Based on the modified Halpin-Tsai model and the first-order shear deformation theory, the dynamic finite element control equation is established. Based on the COMSOL Multiphysics platform, the modal characteristics and transient impact response analysis are carried out, and the dynamic response of the aircraft under moving wheel load is simulated. The static bending test of FG- CFRP plate samples made in the laboratory was carried out, and the numerical model was calibrated. The relative error of test-simulation was controlled within 5 %, which verified the accuracy of predicting static response. The carbon fiber volume fraction gradient curve was parametrically studied to reveal the sensitivity of the gradient to impact and stress reduction. The key engineering factors such as long-term environmental durability and life cycle cost of FG-CFRP pavement are discussed, and targeted improvement and optimization strategies are proposed. The results show that the fundamental frequency of the gradient plate is about 1.93 % lower than that of the homogeneous plate, and the vibration mode characteristics are highly consistent. The peak displacement of transient impact is reduced by 9.4 %. Under the action of moving wheel load, the peak Von Mises stress decreased from 5.32 MPa to 2.15 MPa, with a decrease of 60 %. The gradient design realizes efficient load diffusion and impact hardening through the surface high modulus layer, and the gradual change of interlayer wave impedance promotes the dissipation of stress wave, which significantly improves the safety reserve and dynamic stability of pavement structure. This study verifies the application feasibility of FG-CFRP in high-performance airport pavement engineering, and provides innovative material solutions and theoretical support for the development of a new generation of long-life and high-reliability airport pavement.
Li, Zhenyue
Optimization of Airport Surface Operations for Multiple Flight-Test Aircraft Based on a Wolf Pack Algorithm2026-99-235710/30/2026
To improve the efficiency of airport surface operations involving multiple aircraft types and multiple flight-test aircraft at the same airport, this study investigates the taxi-route optimization problem for flight-test aircraft. First, a runway-exit-time optimization model is established by modeling the landing rollout process, with minimum runway-occupancy time as the objective, so as to determine the optimal rapid-exit taxiway. Second, a multi-aircraft taxi-route optimization model is formulated by incorporating taxi-conflict constraints and is solved using an improved wolf pack algorithm. The case study shows that the proposed method can effectively reduce the total taxi time of multiple flight-test aircraft and shorten the runway-occupancy time of arriving aircraft, thereby demonstrating good feasibility and practical engineering value.
Wang, Tong
Research on an EPHM Methodology Based on Gas Path Performance Parameters2026-99-230510/30/2026
Gas path faults in aero-engines are a major factor affecting flight safety and maintenance costs. To achieve the transition from time-based maintenance to condition-based maintenance and enhance fault prediction and health management capabilities, this paper conducts research on intelligent diagnostic methods based on performance parameters for engine gas path components. Firstly, a component-level nonlinear steady-state model of a dual-spool turbofan engine is established, employing a variable specific heat capacity method to improve computational accuracy and provide a healthy baseline for diagnosis. Secondly, addressing the strong nonlinearity and measurement underdeterminacy in fault diagnosis, a diagnostic framework integrating a multi-population genetic algorithm and multi-operating-point analysis is proposed. The multi-population genetic algorithm effectively enhances global optimization capability and solution stability through parallel evolution, migration operators, and an elite population strategy; multi-operating-point data increases information content and strengthens fault isolation capability. Finally, simulation experiments under ground test conditions are conducted to validate the diagnosis of single-component faults in the low-pressure compressor, high-pressure compressor, high-pressure turbine, and low-pressure turbine. The results show that the proposed method can accurately invert component performance degradation, with a high fault identification accuracy rate, verifying the effectiveness of the proposed model and algorithm. This research provides a feasible technical solution for intelligent condition monitoring and precise diagnosis of aero-engines.
Cai, Na, Li, Ming, Li, BianJiang, Yu, GuangHui, Ma, ZhongYuan
Evaluation of Low-Altitude Aircraft Operation Status Based on Fuzzy Reasoning and D-S Evidence Theory2026-99-230210/30/2026
To provide auxiliary verification for the technical evaluation of low-altitude aircraft operation status and address the limited effectiveness of uncertainty handling, this paper proposes an evaluation method based on fuzzy reasoning and D-S evidence theory. Firstly, the relevant knowledge of D-S evidence theory and fuzzy reasoning is introduced. Secondly, the aircraft operation status levels are constructed, and an intuitionistic fuzzy reasoning system is established based on Gaussian membership functions. The initial basic probability assignments (BPA) are obtained through defuzzification using the intuitionistic fuzzy centroid method. The conflict between evidences is measured by the weighted average of Jensen-Shannon (J-S) evidence distance and conflict coefficient k, followed by multi-cycle discount correction and fusion. Finally, experimental verification proves the rationality of the proposed method, which can provide a reference for related research.
Niu, Xiaowei, Shen, Di, Yu, Fuping, Guo, Yiduo, An, Xiangyu, Xuan, Haoli
Trajectory Optimization for Non-Cooperative Target Spacecraft Based on Sequential Convex Programming2026-99-233010/30/2026
Autonomous operations near space targets that do not cooperate present great challenges because position and attitude planning must be linked. A target of this type lacks navigation aids or communication systems, which makes relative motion planning much more difficult. Although methods based on convex optimization work well for problems with three degrees of freedom, like planetary landing, their use in integrated operations with six degrees of freedom is limited by constraints that are not convex. To solve this problem, this paper proposes a new framework for servicing spacecraft using sequential convex programming. The primary contribution is the extension of convex methods to high dimensional trajectory planning while adding a robust trust region constraint based on trajectory deviation. This mechanism reduces the chance of finding no solution during convex approximations. It improves reliability and convergence when solving complex problems. The approach first creates a continuous optimal control problem with an index that balances energy use and the angle of the line of sight. Nonlinear dynamics are simplified using first order Taylor expansions. Constraints for the field of view and collision avoidance are modeled using spherical and ellipsoidal regions. The non convex problem is changed into a sequence of discrete convex subproblems and solved through iterations. Numerical simulations show that the servicing spacecraft can safely approach the target with stable attitude while meeting all physical limits. The method using sequential convex programming with a trust region demonstrates great potential in optimizing computational efficiency alongside strong numerical stability, laying a solid foundation for future real-time autonomous trajectory generation in complex orbital environments.
Wang, Yuzhi, Yao, Zihao, Wang, Qian, Han, Ziwen, Zhang, Chao, Zhang, Yumei, Li, Shunli
Study on Fatigue Crack Growth of Sandwich Composite Panels with Opening2026-99-232710/30/2026
Owing to their remarkable specific strength and stiffness, coupled with superior impact resistance and thermal/acoustic insulation, sandwich composite panels are extensively utilized in marine, aerospace, and transportation sectors. In contrast to conventional monolithic structures, the multi-layered architecture of sandwich panels introduces complex fatigue failure mechanisms that are not yet fully understood. This study experimentally investigates a U-shaped core sandwich panel featuring a rectangular hatch opening under uniaxial tensile fatigue loading, aiming to characterize its crack initiation and propagation behavior. Subsequently, a custom three- dimensional fatigue crack growth simulation code is developed, grounded in linear elastic fracture mechanics and the extended finite element method (XFEM). A comparison with experimental measurements reveals that the maximum relative error between the predicted and observed fatigue life is 15.7%. The findings offer a theoretical foundation and a technical reference for the fatigue design and life assessment of such sandwich structures.
Chen, Siyu, Xu, Yunze, Liu, Gang
Research on Failure Mode Verification of Civil Aircraft Based on Reliability Data2026-99-231410/30/2026
To verify the accuracy and completeness of FMEA and FTA, this paper proposes a comprehensive failure mode verification method based on reliability data. This method collects multi-source reliability data and identify actual failure modes occurring in equipment during operation firstly, thereby compiling a list of actual failure modes. Next, this list is compared with the FMEA report from the design phase to verify the failure modes themselves. A deeper qualitative verification of the causes, mechanisms, and impacts of the failures is then conducted, leading to the correction and updating of the FTA logical structure to ensure consistency between the safety analysis model and the actual failure logic.Building upon the qualitative verification, the method proceeds to quantitative verification. A comparative analysis is conducted between the actual failure rates of the failure modes and the estimated values in the FMEA. Using the validated failure rate data, the probability of the FTA top event is recalculated and compared against the safety target probability specified in airworthiness regulations to achieve quantitative verification of the failure condition probability. As a core innovation and enhancement of the method, this paper introduces sensitivity analysis. Through tools such as calculating Birnbaum importance and plotting tornado plots, it quantitatively assesses the sensitivity and impact of uncertainties in the failure rate parameters of each bottom event on the probability of failure condition, thereby identifying the key failure modes. The research findings provide theoretical support and a practical engineering foundation for evaluating the actual reliability level of the aircraft fleet, improving the accuracy of safety analysis during the design phase, and guiding preventive maintenance and design improvements.
Han, Bing, Li, Haiwei
Study on Interface Design and Functional Tolerance of Structured Composites for Zero Thermal Expansion Performance2026-99-232310/30/2026
Structured zero thermal expansion composites demonstrate significant application potential in thermal deformation control for high-end equipment, particularly aerospace precision instruments, due to their unique ultra-low thermal expansion properties. However, during the transition from theoretical design models to manufacturing models, uncertainties at connection interfaces and manufacturing errors alter the thermal deformation coordination between heterogeneous components within the material, leading to significant degradation of its zero thermal expansion performance. To address this issue, this study focuses on lattice-structured zero thermal expansion composites derived from topology optimization. First, the connection interface design between heterogeneous lattice components was completed. Subsequently, two typical manufacturing errors—dimensional errors and assembly tolerances—were incorporated into the manufacturability model. Using Monte Carlo random sampling, a mapping relationship was established between the random and discrete manufacturing errors and the composite's equivalent thermal expansion performance. Building upon this foundation, a yield rate metric based on functional tolerance concepts was introduced. This metric was used to evaluate how different interface configurations affect the stability of zero thermal expansion performance. The results demonstrate that, under identical manufacturing precision conditions, different interface configurations exhibit significantly varying thermal expansion stability in response to manufacturing errors characterized by structural parameter dispersion. This research provides valuable insights for translating theoretical designs of such functional materials into manufacturable solutions that meet thermal expansion performance requirements.
Yan, Shaojie, Yang, Zihao, Zhang, Yongcun
Aging Behavior of Double-Base Propellants under Negative Pressure Conditions2026-99-232010/30/2026
To investigate the effect of negative pressure environment on the aging behavior of solid propellants, a 60-day negative pressure accelerated aging test was carried out on SG-2 propellant with five working conditions: atmospheric pressure at room temperature, atmospheric pressure at 80°C, and negative pressure at 40°C/60°C/80°C. Combined with Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC), the functional group evolution law and thermal decomposition kinetic characteristics of the periphery zone and core zone of the propellant were analyzed. The results show that the propellant exhibits significant inhomogeneous aging characteristics under negative pressure aging. The functional group structure in the periphery zone is more stable in the early aging stage; in the middle stage, components such as DNT and C2 in the core zone migrate to the periphery zone; in the late stage, the undegraded components in the core zone continuously supplement the periphery zone, making the functional group integrity of the periphery zone better than that of the core zone. DSC tests combined with Kissinger and Ozawa methods show that the thermal decomposition activation energy of the propellant decreases continuously with the increase of aging temperature under negative pressure environment, and the activation energy drops to 428.91 kJ/mol after aging at negative pressure 80°C. High temperature accelerates the volatilization of NG, the cross- linking of NC molecular chains and the consumption of stabilizer, leading to the easy breakage of O-NO₂ groups and the significant deterioration of thermal stability. This study clarifies that the aging mechanism of the propellant under negative pressure environment is the synergistic effect of component migration and diffusion, functional group decomposition and molecular chain cross-linking, which provides a theoretical basis for the storage and application of solid propellants in negative pressure service scenarios such as deep space exploration.
Gao, Peizhe, Deng, Hanyu, Tang, Yuqing, Yuan, Yichao, Shen, Nianyu
High-Temperature Sealed Disc Spring Compression Load-Holding Performance Testing and Material Parameter Calibration2026-99-232210/30/2026
In high-temperature sealed assemblies, disc springs provide sustained preload to suppress leakage. However, at elevated temperatures, material creep and stress relaxation may reduce elastic recovery and accumulate permanent deformation, thereby degrading sealing reliability. Because the material properties of commercially procured disc springs vary with suppliers and production batches, they are difficult to apply directly in the analysis of high-temperature components. This study investigates Inconel-800 disc springs. Sustained compression tests were conducted at 600–900 °C to systematically obtain load–time responses and the temperature dependence of permanent deformation. The results show that, as temperature increases, the rate of force decay accelerates significantly and the residual load decreases markedly. At 800 °C and 900 °C, the permanent deformation approaches the compression limit, indicating that time-dependent material deformation becomes the dominant factor. Based on these results, a finite-element model consistent with the test conditions was established. Material creep parameters were calibrated from component-level compression data by minimizing the discrepancy between simulated and experimental curves. The identified parameters were validated under different temperature conditions and loading cases. The simulation results agree well overall with the experiments, and the errors remain within engineeringly acceptable limits. This study provides baseline data and an engineering method for obtaining material parameters to support material selection and structural optimization of high-temperature sealed disc springs.
Yang, Yuyao, Cai, Xianhui
ME-YOLO: Aircraft Corrosion Defect Detection Model Based on Multi-Directional Edge Perception and Multi-Scale Feature Fusion2026-99-232110/30/2026
Detecting surface defects on aircraft is critical to safety in the aerospace field. The current detection methods suffer from low efficiency, high false positive rate and poor adaptability to complex environment. Although the existing target detection algorithms have achieved notable performance in this field, at present, many models in this field still face considerable challenges. For example, due to the constraints of hardware platforms, machines that can be deployed on edge devices such as UAVs and robots need lightweight and easy-to-deploy models, but lightweight designs often a certain degree of accuracy degradation. At the same time, most of the surface defects of the aircraft are small targets, which impose higher demands on the model. In order to solve these limitations, this paper proposes an improved YOLO model ME-YOLO (multi directional edge fusion YOLO) based on edge enhancement and multi-scale fusion. Firstly, the EdgePyramid module is designed, which uses the rich edge responses extracted by the Multi Orientation Attention Sobel (MOAS) module and through the three-layer cascade pool structure to construct the three-scale edge features aligned with the backbone network. Then, the EdgeEnhance module is introduced to adaptively fuse the conventional convolution features and edge features at the corresponding resolution, effectively enhancing the sensitivity of the model to the corrosion boundary. Experimental results show that, compared with the baseline YOLOv11, ME-YOLO improves mAP@0.5 by 2.7% and simultaneously increases Recall by 2.3%, which helps reduce missed detections of corrosion targets. Although the introduction of multi-directional edge priors brings a slight increase in parameters (+3.66M) and a minor decrease in inference speed (--8.6%), the model still maintains a real-time detection capability of 97.54 FPS, meeting the deployment requirements for edge devices such as UAVs. This strategy of trading a modest computational overhead for improved detection rates in safety-critical tasks offers a potentially practical and robust alternative for intelligent operation and maintenance of aviation equipment.
Zhou, Xing, Li, Yuan
Comparative Numerical Study of Different Turbulence Modeling Approaches for Civil Aircraft Inlet Flows under Crosswind Conditions2026-99-233110/30/2026
This study constructs and validates a high-efficiency and high-fidelity adaptive Very Large Eddy Simulation (VLES) strategy based on user defined function(UDF) secondary development to investigate the complex and unsteady flow characteristics of civil aircraft intakes under crosswind conditions, conducting a comparative study of turbulence simulation methods across different hierarchies. Initially, the performance of traditional RANS turbulence models, including S-A, BSL k-ω, and SST k-ω, in simulating large-scale flow separation within intakes under crosswind conditions is evaluated, revealing that their applicability is limited. However, the predictive accuracy of RANS models can be improved to some extent by incorporating Explicit Algebraic Reynolds Stress Models (EARSM) and non-linear constitutive corrections. Under the maximum crosswind mass-flow condition, for complex flows dominated by shock and boundary-layer interaction, the SST model, high-resolution Large Eddy Simulation (LES), and the developed VLES model are compared. Furthermore, under variable crosswind mass-flow conditions, a comparative study on separation characteristics between the VLES and SST models is carried out. Finally, the simulation performance of the VLES model under installed nacelle conditions is verified. Research results indicate that the VLES model achieves superior near-wall boundary layer resolution while effectively mitigating the over-prediction of separation zone extent typically associated with LES, demonstrating higher accuracy without a significant increase in computational cost. Through verification via independent nacelle calculations, the VLES method shows a high degree of consistency with experimental data and non-linear SST model results in predicting separation characteristics under varying mass-flow rates, accurately reproducing the processes of shock-induced separation and boundary-layer reattachment. This research establishes the superiority of the VLES method in handling complex intake flow separation, laying a theoretical and technical foundation for its engineering application in the aerodynamic assessment of actual installed nacelles.
Jiang, Jintao, Han, Xingsi, Liu, Hao, Guo, Jin, Yu, Fan, Xu, Xiao
Feature Fusion and CNN-Based Acoustic-Emission Diagnosis for Aero-Engine Initial Damage2026-99-231610/30/2026
Acoustic emission (AE) signals generated by incipient aero-engine damage are usually weak, intermittent, and highly dependent on sensor position, which makes diagnosis based on a single channel unreliable. To address this issue, this paper develops a multi-sensor AE diagnosis framework that combines entropy-guided feature fusion with a convolutional neural network (CNN). Time-domain and frequency-domain descriptors are first extracted from AE waveforms collected by multiple sensors. The consistency of each feature type across channels is then evaluated using feature entropy. Features with lower entropy are considered more informative for damage discrimination and are therefore retained for fusion. Based on the normalized channel contributions of these selected features, an adaptive weighted fusion matrix is constructed and used as the input to the CNN. The method is validated on a self-built aero-engine structural test rig equipped with 12 AE sensors. Fifteen representative initial-damage cases are designed, including signal excitation, crack-like excitation simulated by pencil-lead break (PLB), and impact-induced micro-deformation cases. Experimental results show that the proposed framework achieves a best average classification accuracy of 96.80% and provides more balanced class-wise performance than conventional machine-learning and deep-learning baselines. Additional noise-injection tests further indicate that the method maintains good robustness over a wide signal-to-noise-ratio range. These results suggest that entropy-guided multi-sensor AE fusion is a practical solution for intelligent diagnosis of aero-engine initial damage.
Jin, Yucheng, Han, Cong, Zhang, Leixuan, Yang, Guoan
Practical Predefined-Time Observer for Hypersonic Vehicle Attitude Control2026-99-232810/30/2026
This article proposes a practical predefined-time observer for hypersonic vehicle attitude control. To improve the convergence performance, a practical predefined-time condition is introduced into the observer. This design provides high flexibility and allows for a precise prediction of the maximum settling time, which does not depend on initial conditions. Moreover, the actual settling time can be adjusted by modifying the preset parameters. Numerical simulations are carried out to confirm the theoretical properties and to illustrate the observer’s effectiveness.
Zhang, Yufei, Yang, Hua, Chen, Weifang
A Spacecraft Targeting Method Based on 3D Imaging and Point Cloud Alignment2026-99-230110/30/2026
Spacecraft are now required to possess all-weather, zero-window, and support-independent launch capabilities. Consequently, research on spacecraft targeting must continue to focus on improving convenience and efficiency. In this paper, a spacecraft targeting method based on point cloud alignment is proposed. Firstly, external Triple Self-targeting Inertial Measurement Units are utilized to complete self-targeting. Secondly, the 3D point cloud of the spacecraft is obtained by binocular imaging technology, and an attitude transformation matrix is obtained by aligning the measured point cloud with the standard point cloud. Finally, the installation relationships between the binocular camera and the Triple Self-targeting Inertial Measurement Units, as well as between the guidance system and the spacecraft body, are determined. Combining these installation relationships with the attitude transformation matrix, the targeting results from the Triple Self-targeting Inertial Measurement Units are transferred to the spacecraft guidance system. In the simulation experiment, the maximum standard deviation of the three directions after multiple targetings is 9′9″, which can meet the requirements of spacecraft targeting. The method proposed in this paper fully retains the self-targeting advantages of the Triple Self-targeting Inertial Measurement Units without external support, while making spacecraft targeting more flexible and rapid. If applied to actual equipment, it will effectively enhance the adaptability of spacecraft equipment to environments.
Wu, Bingjie, Wang, Xiaozi, Zhang, Wei, Li, Mingrun
PINNs-Based Parameter Estimation for Gradient Descent2026-99-230310/30/2026
To address the joint estimation of state and parameters for fixed-wing aircraft in wind gradient environments, this paper proposes a high-precision identification method based on a physics-informed neural network. By integrating wind gradient models with flight dynamics equations, a multi-objective optimization framework combining data-driven approaches with physical constraints is established. Employing polynomial time embedding and a dual-branch network architecture, coupled with a dynamic training strategy, simultaneous estimation of flight state and wind gradient parameters is achieved. Experimental results demonstrate that this method achieves approximately 7% parameter estimation error while accurately reconstructing unobserved attitude information. Requiring only four-dimensional observation data, this approach provides an effective solution for wind gradient glide navigation in low-cost aircraft.
Wu, Ting, Bai, Zhuoyue, Gao, Xianzhong
2026 2nd International Conference on Aerospace Engineering and Materials Technology2026-99-230010/30/2026
TOC
Tobolski, Sue
Vibration–Acoustic Emission Fusion and STFT–MFDCNN for Fault Diagnosis of Bearings in the Aero-Engine2026-99-231510/30/2026
Rolling bearings are key components of aero-engine rotor systems, and their degradation can trigger abnormal dynamics and safety risks. Unplanned bearing failures increase downtime and inspection cost; early detection enables condition-based maintenance and reduces conservative replacement. Early faults are weak, intermittent, and often masked by operating variability, so diagnosis based on a single sensing modality is usually incomplete. Vibration signals describe global dynamic behavior and resonance responses, whereas acoustic emission (AE) captures micro-damage processes and short impulsive events. Given the differences in bandwidth and noise sources, combining vibration and AE can provide a fuller description of bearing states. This study proposes an STFT–MFDCNN framework for bearing fault diagnosis using fused vibration–AE information. First, synchronized vibration and AE signals are converted into time– frequency images via the short-time Fourier transform (STFT), preserving spectral content and temporal non-stationarity in a unified representation. Second, a dual-branch multi-scale feature dense convolutional neural network (MFDCNN) is constructed. In each branch, parallel convolutions with different kernel sizes capture fault patterns across receptive fields, and dense concatenation connects all preceding feature maps to improve feature reuse and gradient flow. Third, global average pooling generates compact feature vectors for both branches, which are concatenated in a fusion head and classified by a Softmax layer. Experiments on a vibration–AE dataset built in this work show that the proposed method reaches 97.78% identification accuracy. Compared with dual-branch fusion baselines based on AlexNet, ResNet, and a shallow CNN, accuracy increases by 3.34%, 4.45%, and 5.00%, respectively. Compared with single- modality models (Only-AE and Only-Vib), accuracy improves by 14.71% and 6.77%.
Li, Zhichuang, Wang, Xingfeng, Zhang, Yanpu, Yang, Guoan
Research on Fault Diagnosis of Civil Aircraft Engine Thrust Reverser Deployment Overspeed with Small Samples Based on Semi-Supervised Learning2026-99-231910/30/2026
Civil aircraft engine thrust reversers are easy to have overspeed faults when they are being deployed, therefore this condition is very important for flight safety and maintenance work efficiency. The low sampling frequency, about 1Hz, of onboard data recording systems, for example WQAR, together with external environment interferences such as sudden strong winds, therefore causes a quite large number of wrong and missed alarms in fault data. Therefore, the labeled data that can be obtained are not only few in number but also have low quality. In this article, a fault diagnosis framework which is based on semi-supervised learning is put forward to solve the problems of high labeling expenses and fault diagnosis under the condition of small samples. This framework makes use of a small amount of labeled data and a large amount of unlabeled data. It uses Semi-Supervised Support Vector Machines, Semi-Supervised Neural Networks, and Semi-Supervised Random Forests for dynamic self- training to realize classification of three kinds of states: “Normal State,” “Low-Speed Thrust Reverser Deployment Exceedance,” and “Medium-Speed Thrust Reverser Deployment Exceedance”. The experiment outcomes show that the Semi-Supervised Neural Network model which uses self-training method has the highest classification accuracy on the test set, achieving 94.8%. Further robustness analysis, such as label noise and feature noise disturbance experiments, indicates that this model displays the smallest performance lowering under noisy environments, hence it represents the best overall performance. This research gives an effective method for the diagnosis of engine thrust reverser function problems in an effective and strong way.
Yuan, Xiaojiang, Liu, Nan
Multiscale MD-FEA Investigation on Large-Deformation Mechanical Behaviors of Hydrogels Modified with Ionic Liquids2026-99-230610/30/2026
Hydrogels incorporated with ionic liquids (ILs) demonstrate broad application prospects in the fields of wearable flexible sensors and human physiological monitoring. Nevertheless, the intrinsic correlation between microscale intermolecular interactions and macroscale nonlinear mechanical responses under large tensile deformation has not yet been fully clarified. In this work, a coupled numerical framework integrating molecular dynamics (MD) and finite element method (FEM) was adopted to explore the mechanical behaviors of poly(acrylic acid)/N,N’-bis(acryloyl)cystamine/ionic liquid (PAA/NB/IL) hydrogels under large deformation. A series of molecular models with graded IL doping levels were established to characterize the structural rearrangement and energy change characteristics during uniaxial tension. Numerical results from MD simulations reveal that the addition of ILs strengthens non-covalent interactions such as van der Waals forces and electrostatic attractions, and further drives covalent bond stretching and angular deformation to bear external loads under high-strain conditions. Meanwhile, a generalized Maxwell constitutive model, whose Prony-series parameters were fitted by experimental stress-relaxation data, was introduced into FEM numerical calculations. The simulated quasi-static tensile properties are highly consistent with experimental measurements. Comprehensive analysis demonstrates that the mechanical enhancement induced by ILs stems from the synergistic effect of covalent structural deformation and the reconstruction of non-covalent interactions, which offers valuable theoretical guidance for the development of hydrogel materials applied in large-deformation engineering scenarios.
Li, Sitan
Design and CFD Simulation Analysis of Cross-Medium Aircraft2026-99-231310/30/2026
Composite wing trans-medium aircraft integrate the high-speed cruise efficiency of fixed-wing aircraft with the vertical take-off and landing (VTOL) flexibility of rotary-wing aircraft, boasting significant application potential in marine environmental monitoring and other fields. This paper designs a trans-medium variable tiltrotor aircraft configuration, which adopts a foldable main wing to achieve adaptive adjustment of the aerodynamic profile, equips a rear tiltrotor to satisfy both VTOL and cruise propulsion requirements, and incorporates a T- tail layout to avoid rotor downwash interference. Concurrently, a worm-gear-driven wing morphing mechanism and a servo-driven rotor tilting mechanism are developed to realize reliable multi-mode switching. Computational fluid dynamics (CFD) numerical simulations are performed using ANSYS Fluent software, and a comparative analysis is conducted on the aerodynamic characteristics and flow field features of the two modes at varying speeds and angles of attack. Simulation and test results demonstrate that the lift-drag ratio peaks at an angle of attack of approximately 10° under cruise conditions, exhibiting excellent cruise efficiency. Flow field visualization results indicate that the flow field adheres well to the aircraft main body, and the flow field transition at the fusion zone between the T-tail and fuselage is smooth, which effectively reduces local eddy current interference. Within the high-efficiency angle of attack range, the overall aircraft flow field is uniformly distributed and the evolution of vortex structures is controllable, presenting favorable flow field stability. Additionally, the study reveals that flow separation and vortex structures in the wing-fuselage transition zone are the key factors affecting the stability of the overall aircraft flow field.
Hu, Yajun, Zhou, Liao, Guo, Mingming, Li, Boling, Tang, Wenyi
A Two-Time-Scale Model Predictive Control Framework for Precise Strain Control of Shape Memory Alloys2026-99-230710/30/2026
Precise strain control of Shape Memory Alloys (SMAs) is challenging due to their strong nonlinearity, hysteresis, and thermomechanical coupling. To address the needs of real-time control system design, this paper proposes a two-time-scale decoupling control framework based on Model Predictive Control (MPC). First, a transient physics-based model considering one-dimensional heat conduction and latent heat under electrical excitation is established and then reduced to a lumped-parameter model suitable for controller design. To balance prediction accuracy and computational efficiency posed by the model nonlinearity, an innovative two-time-scale MPC strategy is designed: a fast inner-loop temperature MPC is used for efficient thermal management outside the phase transformation plateau, while it switches to an outer-loop strain MPC for precise trajectory tracking and hysteresis compensation during the critical phase transformation period. Simulations demonstrate that this strategy significantly reduces computational burden while maintaining accuracy. Compared to a single-time-scale MPC, the proposed method reduces the settling time by 26%, the root mean square error by 16%, and the single-step computation time by 19.6% for a step reference strain. This work provides an effective and engineering-friendly solution for high-performance, real-time control of SMA-based actuators.
Ding, Shaozhe, Liu, Longbin, Zhang, Shifeng
Abuse Takeoff Flight Test Technology and Risk Control for Civil Airplane2026-99-231810/30/2026
Abuse takeoff flight test is a necessary subject for airworthiness certification of civil transport airplane, which simulates the safety of the airplane in the event of inadvertent operation during takeoff. It is difficult and risky to test flight, which brings great challenges to the organization and implementation of flight test. Abuse takeoff flight tests include out-of-trim takeoff, early rotation takeoff, over rotation takeoff, early and over rotation takeoff and early and rapid rotation takeoff. Through theoretical calculation and reasonable analysis, the flight test methods and risk control measures of abuse takeoff are studied, the test results are given, and the factors affecting the flight test results are analyzed to ensure that the test results meet the requirements of airworthiness regulations.
Qu, Feizhou
The Statistical Analysis of Commercial Flight Data for Defining the Payload-Range Performance of the Aircraft Conceptual Scheme Design2026-99-231110/30/2026
This research focuses on the application of statistical analysis of commercial flight data in aircraft conceptual scheme design. The payload-range performance of the commercial aircraft should be defined and analyzed by utilizing statistical methods during the conceptual scheme design, as it determines marketability. Statistical analysis is deemed essential due to the complexity and specific requirements of conceptual design. The research paradigm established in this study involves collecting and analyzing flight data of competitor aircrafts operating in the target market, using the OAG database as a foundation. This data is then utilized to build statistical models and conduct trade-off analysis. The results reveal that while the competitor aircraft has good route coverage, the conceptual scheme designed exhibits better payload-range performance, with a potential reduction in structural weight and better aerodynamic performance. Aircraft designers should take the imbalance in flight data between different airports, which is revealed by the application of statistical analysis, into consideration in conceptual scheme design. This study fills the gap between “market data-driven” and “performance modeling” in aircraft conceptual design, providing a reusable paradigm for subsequent research. The process of aircraft scheme design is a multi-disciplinary optimization process. When the range under certain payload of the concept scheme is already sufficient to cover the target market, how to conduct iterative design in conjunction with other indicators such as economy and commercial range is a problem worthy of in-depth study.
Gu, Xiangying, Cheng, Zhiyu
Design Consideration for Field-Loadable Software of Civil Aircraft2026-99-231210/30/2026
With the increasingly widespread application of airborne software in civil aircraft and the continuous growth of its functional complexity, the frequency of software modifications has risen significantly. The traditional factory-return loading mode leads to high operating costs and long maintenance cycles. Focusing on the design of field-loadable software for civil aircraft, this paper proposes a decision-making strategy for determining whether airborne software should be designed as field-loadable software. This strategy classifies airborne software into three categories, platform basic software, functional software, and database software. It puts forward the design principle that field-loadable design is mandatory for database software, preferred for functional software, and not mandatory for platform basic software. In addition, a multi-dimensional design deviation assessment model is constructed for software that cannot meet the above requirements. Functional software that is not designed as field-loadable and has not yet been installed on aircraft shall be evaluated from five dimensions: interconnection complexity, software characteristics, airline operation, commercial off-the-shelf (COTS) attributes, and competitor aircraft models. For functional software that is not designed as field-loadable but has already been installed on aircraft, three additional evaluation dimensions shall be included: the possibility of software modification, difficulty of optimization, and cost of optimization. Meanwhile, this paper analyses the airworthiness requirements to be considered in the design of field-loadable software, as well as the design considerations required to address problems arising in the delivery process, such as configuration identification Issue, granularity issue of field-loadable software packages and format issue of field-loadable software packages. The research provides a systematic reference for the design decision-making, airworthiness compliance and efficient delivery of civil aircraft field-loadable software, helping to shorten aircraft downtime and reduce airline operation costs.
Feng, Chen, Fan, Hui, Luo, Jialu
Experimental Investigation on Flame Characteristic for Civil Aircraft Propulsion System Fireproof Test2026-99-231710/30/2026
In order to meet the airworthiness regulations, the civil aircraft propulsion system needs to carry out the necessary fireproof test. The measurement of the flame temperature is very essential for the certification and validation of fire protection thermal simulation models, and also helps to establish the empirical understanding of complex flame behaviors. In order to investigate the influence of the specimen on the flame temperature distribution, the two dimensional flame temperature distribution of the free burning test and several fireproof tests, including titanium panel fireproof tests, stainless steel panel fireproof tests, composite laminated panel fireproof tests, honeycomb sandwich panel fireproof tests, were experimental investigated in this paper. The test results shows that panel specimens significantly alter the temperature distribution of the standard flame and interfere with radiation heat transfer measured by thermocouple, resulting in a significant reduction in the temperature gradient of the flame and a obvious increment in the temperature of the surrounding non-flame-impinging zone. The central flame-impinging zone exhibits minimal temperature variation compared to the baseline flame at 1093 °C, with temperature elevation restricted to approximately 40 °C (within 4% deviation). Both metal panels and composite panels demonstrate consistent trends in affecting flame temperature distribution. However, compared to metal panels, composite materials induce smaller temperature gradients and more uniform temperature fields. Multiple burning tests on same panel progressively intensify the oxidation on the specimen surface, leading to a gradual decrement in flame temperature. Especially, this temperature reduction becomes statistically significant as early as the second time burning test.
Chen, Fang, Guo, Junxian, Peng, Sen
A Study on Gust Alleviation Based on Distributed Electric Propulsion2026-99-230410/30/2026
In a distributed electric-propulsion aircraft, multi-motor drive propellers distributed across the wings to provide the aircraft’s primary thrust. The electric control system enables rapid adjustment of propeller speed to control the overall attitude and flight path of the distributed electric propulsion aircraft. Furthermore, by utilizing the wake-induced acceleration effect generated by the propellers to alter the aerodynamic force distribution on the wing surfaces, it achieves gust attenuation. When encountering gusts, the PID control system adjusts the propeller slip to increase lift, thereby mitigating the effects of gusts on distributed electric propulsion aircraft. This paper employs PID control to regulate the steady-state performance of a distributed electric-propulsion aircraft under gusty conditions, with the objective of achieving the fastest return to a steady state. When encountering a headwind and a downdraft, the aircraft’s flight quality are severely disrupted; while airspeed, angle of attack, pitch angle, and rate of climb return to their original states or tend to stabilize, the effect of these forces causes the aircraft to lose height. After PID control is applied, under the influence of a tailwind disturbance, the aircraft’s descent under PID control is significantly less than under open-loop control, and it quickly returns to its original height and remains stable; Under the influence of downdraft turbulence, the aircraft under open-loop control is unable to return to its original height, whereas the aircraft under PID control drops slightly before returning to its original height.
Yang, Wenshuo, Yang, Youxu, Fu, Junquan, Shen, Junhui
Model-Based Flight Test Methodology Research for Transport Category Aircraft Stall2026-99-234010/30/2026
Model-based approaches have brought about a qualitative leap in enhancing flight test safety, improving the efficiency of concurrent engineering, and enabling knowledge reuse and sharing. Focusing closely on the engineering application of model-based methods in the field of stall flight testing, this paper systematically reviews the stall airworthiness certification requirements for transport-category aircraft. It proposes a stall flight test process model based on functional flow models and investigates a model-based design method for stall flight test point matrices. Furthermore, an improved practical approach for multi-disciplinary collaborative modeling, simulation, and compliance data analysis in stall flight testing is presented. Taking a specific aircraft type's stall flight test as an example, this paper provides a detailed description of model-based application cases across the pre-flight, in-flight, and post-flight phases.
Liu, Xu, Ding, Junliang
Numerical Simulation and Geometric Parameter Optimization of Solid Propellant Single-Screw Extrusion2026-99-236010/30/2026
For the single-screw extrusion process of solid propellant, the geometric optimization of the homogenization section faces a core problem: the high coupling between pressure establishment, material transport and energy consumption, and it is difficult to achieve a balance between different performance indicators by traditional empirical methods. Therefore, a numerical optimization framework combining CFD simulation and genetic algorithm is constructed to systematically explore the optimal screw geometric configuration. Propellant slurries are regarded as non-Newtonian fluids and are described by the Arrhenius temperature-dependent Bird-Carreau model, on which the flow field, pressure field and temperature field are solved. The key geometric parameters such as outlet core diameter, pitch, front and rear wedge angle, and thread width are selected as the optimization variables, and the ratio of pump power to shaft power is used as the objective function of energy efficiency to measure the degree of mechanical energy conversion into effective pressure work, and thermal safety constraints are introduced to control the upper limit of propellant temperature. The optimization results show that compared with the initial configuration, the volume flow rate is increased by 123% and the energy efficiency is only slightly reduced under the premise of maintaining a stable pressure drop. The flow field analysis shows that the optimized structure enhances the resistance-led conveying capacity and effectively inhibits the backflow phenomenon. Further analysis shows that the design with a larger pitch and narrower thread can reduce energy consumption while increasing the output, but its pressure accumulation ability is significantly weakened, revealing the inherent trade-off between screw geometry and pressure generation, conveying efficiency and energy consumption. The resulting optimized configuration achieves a good balance between multiple properties, which provides a theoretical reference for the continuous extrusion process of high-performance solid propellants.
Tang, Zhuang, Jiang, Ye, Mei, Mei, Wu, Wei-Tao
Analysis of Dynamic Characteristics in the Tip Near-Stall Flow Field of a Transonic Axial Compressor Based on POD and DMD2026-99-236410/30/2026
Under the pre-stall condition of transonic axial compressors, intense unsteady flow within the tip clearance region acts as the primary mechanism initiating rotating stall and constraining the stable operating range of gas turbine engines. Conventional proper orthogonal decomposition (POD) alone only captures spatially coherent structures with optimal flow-field energy distribution, yet fails to directly characterize modal dynamic evolution and thus cannot fully uncover the inherent onset mechanism of compressor instability. Taking the NASA Rotor 67 transonic compressor rotor as the research object, this work obtains time-resolved unsteady flow-field data in the tip region near stall via high-fidelity numerical simulation. A combined POD and dynamic mode decomposition (DMD) framework is employed to synchronously extract spatial structural features and dynamic evolutionary laws of the flow field for instability mechanism analysis. Results demonstrate that the dominant POD mode corresponds to the tip secondary vortex induced by breakdown of tip leakage vortex, with a dominant frequency of 3495 Hz and its harmonics. DMD identifies a weakly growing dominant mode associated with the tip secondary vortex and a low-frequency mode linked to oscillations of the leakage vortex core; the mutual coupling constitutes the core trigger for flow-field instability.
Li, Wei
Optimization Method for UAV Scheduling Based on Beidou2026-99-235210/30/2026
Currently, UAVs are increasingly used in remote sensing monitoring, logistics and distribution, emergency rescue and recreational aerial photography, etc., which puts higher requirements on wireless networks, i.e., how to allocate limited wireless resources in real-time, efficiently and fairly to ensure that a large number of UAVs can work together in complex environments and maintain high-quality communication services. This paper investigates an optimisation method for UAV scheduling based on the BeiDou satellite navigation system, which improves the accuracy and efficiency of UAV mission execution by utilising the high-precision positioning and time synchronisation services provided by the BeiDou system. The results of the experiment showed that as the number of missions increased from 10 to 50, the average mission completion time increased from 8.3 to 12.5 minutes, the average speed increased from 30 to 34 km/h, the average energy consumption increased from 0.8 to 1.2 kWh, the average distance flown increased from 12 to 22 km, the communication success rate decreased slightly from 99.2 to 98.2%, the resource utilization rate increased from 85.1% to 87.5%. These results show that the method performs well in terms of task completion time, energy consumption, communication success rate and resource utilisation, which provides strong support for the application of UAVs in the fields of logistics and distribution, emergency rescue, and so on.
Ji, Hongbin, Jiang, Kexin, Zhang, Dongxue, Bai, Yanhui, Liu, He, Zhang, Shuangna
Optimization and Validation of a Lumbar Spine Model for Aviation Vertical Impact Simulation Based on THUMS2026-99-237110/30/2026
In assessing lumbar spine injuries of civil aircraft occupants under vertical impact, existing anthropomorphic test devices cannot accurately capture the injury mechanisms. Digital human body models, such as THUMS, are primarily developed for automotive crashes, and their default seated posture differs from that of real civil aircraft occupants. Although the THUMS model can be adjusted to better represent civil aircraft occupants’ seating posture, the mechanical response of the lumbar spine after adjustment has not been sufficiently validated. This limits the model’s reliable use in assessing lumbar spine injuries of civil aircraft occupants. To address this limitation, the THUMS lumbar spine model was modified to reflect aircraft seating posture and physiological lumbar lordosis, and the stiffness of key lumbar ligaments was systematically optimized. Following optimization, the model’s mechanical response curves under flexion, anterior shear, tension, and compression all fell within the post-mortem human subject (PMHS) response corridors, with deviations from the mean PMHS curves significantly reduced. Under the typical 14 g vertical impact specified by FAR 25.562, the optimized lumbar spine exhibited lower peak flexion moments at all lumbar levels, while the axial compressive load and predicted injury risk became more concentrated in the upper lumbar spine. These findings indicate that directly using the original THUMS model may underestimate injury risk in the upper lumbar region while overestimating it in the lower lumbar segments. Posture adjustment, lumbar curvature correction, and ligament stiffness optimization enhance model biofidelity, providing a more reliable basis for the assessment of occupant lumbar injuries.
Shi, Xiaopeng, Jiang, Zihao
Target Positioning Method for Unmanned Aerial Vehicle Tracking Based on Beidou2026-99-235310/30/2026
In order to support successful tracking and monitoring tasks in different environments, drones need to quickly and accurately identify targets. This paper studies a drone combat target positioning method, with a focus on the BeiDou satellite navigation system and its performance under different environmental conditions. A complete system has been designed, including flight control system, environmental sensors, data transmission and processing system, aiming to achieve precise positioning and target tracking of unmanned aerial vehicles. This paper uses on-site testing to explain the coverage range and stability positioning accuracy of ranging signals in different environments. Experimental data shows that the BDS system has good positioning error performance for unmanned aerial vehicles, with an average error of 46.52 cm. BDS positioning time is usually short, with a maximum positioning time of 780ms and a minimum positioning time of 224ms. However, the BDS system still needs improvement in terms of dynamic environmental adaptability, multi-target tracking, anti-interference ability, and adaptability to harsh environmental conditions. Future work will focus on algorithm optimization, hardware technology improvement, and data security to enhance system performance.
Tao, Zhiping, Zhang, Chenghao, Hou, Bo, Song, Juan, Yuan, Peng, Liu, Xianyang
Integrated Verification Technology and Application for Aero-Engine Functional Model Design and Simulation2026-99-235910/30/2026
The simulation verification of functional model systems still runs into a familiar set of obstacles: the link to the original design tends to break, models drawn from different sources are hard to unify, and the confidence in the results is often hard to defend. This paper proposes an integrated design-verification technology framework for functional models to address these issues and to provide a basis for application research. The framework rests on three core technologies. The first is an automatic design-simulation connection built on metamodel mapping, which converts a SysML design model into a simulation model and feeds results back in both directions. The second unifies multi-source heterogeneous models under the FMI standard, using a standardized encapsulation process to make multi-domain co-simulation workable. The third performs automatic model correction through multi-objective intelligent optimization, giving the simulation models an automatic calibration loop that raises confidence. The approach was applied to a particular aero-propulsion system: the functional model was built first, multidisciplinary analyses were then integrated, and the result was checked against measured data. The application shows a seamless design-simulation connection, keeps the error of key parameters below 5% in real time, and markedly improves the automation level, integration efficiency, and model accuracy of the simulation process..
Qiao, Youwei, Jin, Hailiang, Xiao, Wei, Huang, Gong, Zhang, Wenzhuo
An Improved ResU-Net for Thermally Grown Oxide Layer Segmentation in Thermal Barrier Coatings2026-99-236110/30/2026
Thermal barrier coatings (TBCs) serve as the critical protective layer for gas turbine components. In complex service environments, the thermally grown oxide (TGO) layer formed between the top coat (TC) and the bond coat (BC), along with the evolution of its microscopic morphology, is a key factor determining the service life of TBCs. To address the complex morphology of TGO layers that challenges conventional segmentation methods, this paper proposes MSF-SA ResU-Net, a multi-scale feature fusion self-attention model based on the ResU-Net architecture, for the image segmentation of thermally grown oxide layers. Building upon residual connections, this model incorporates two key enhancement modules at the bottleneck layer: Multi-Scale Fusion (MSF) and Self-Attention (SA). During the feature processing stage, the MSF module effectively captures the multi-scale morphological features of the TGO layer through receptive fields of different sizes, solving the difficulty of extracting long-strip and irregular morphologies. Subsequently, the SA module recalibrates the fused features by calculating the global dependencies between them, enhancing the network's attention to TGO boundaries and micro-defects. Comprehensive experiments on an in-house dataset of 3,000 SEM images demonstrate that MSF-SA ResU-Net outperforms standard U-Net and contemporary segmentation architectures. Furthermore, due to the feature extraction capability of the ResNet backbone network, the model maintains high accuracy and exhibiting good convergence performance. This makes the architecture an effective solution for the microscopic analysis of thermal barrier coatings.
She, Weicen, Song, Yan
Configuration Design and Implementation of the SuperView Neo 2 Satellite System2026-99-237010/30/2026
With the rapid advancement of spaceborne Synthetic Aperture Radar (SAR) technology, distributed Interferometric SAR (InSAR) has emerged as the definitive method for high-precision global topographic mapping. This study focuses on the SuperView Neo 2 (SVN2) satellite system, developed by China Siwei Surveying and Mapping Technology Co., Ltd., detailing its technical configuration design and operational implementation within the next-generation commercial remote sensing sector. Equipped with X-band high-performance phased-array SAR payloads, the SVN2 system is engineered for the high-efficiency production of global 1:25,000-scale Digital Surface Models (DSM) while providing millimeter-level surface deformation monitoring through Differential InSAR (DInSAR) capabilities. The paper emphasizes a systematic design approach that integrates four coupled elements: mission objectives, system performance, orbit design, and formation geometry. To satisfy the rigorous requirements of interferometric mapping, the system adopts a sun-synchronous, strictly repeating frozen orbit with a 200-meter radius “pipeline” control strategy. By implementing flexible formation configurations for high and low latitudes, SVN2 achieves the triple synchronization of time, space, and phase necessary for sub-meter resolution and high vertical accuracy. Using the SVN2-03/04 cluster as a primary case study, the results demonstrate that through a sequence of over 40 precise orbital maneuvers, the dual-satellite system successfully established a close-range fly-around formation within the 100-meter-level pipeline just seven days after launch. This operational success represents three major technical breakthroughs for Chinese commercial radar satellites: high-precision strictly repeating orbit maintenance, stable close-range formation flying, and fully autonomous inter-satellite cooperative control. The SVN2 constellation provides a robust, all-weather mapping guarantee for the global geographic information framework and supports diverse applications in geological hazard detection and social economic planning.
Tang, Ke, Qiao, Yishi, Huang, Tao, Zhang, Guoliang, Zhao, Di, Zhang, Zhongze
A Comparative Study on Aerodynamic Characteristics and Stability of Twin-Boom UAVs with Typical Tail Configurations Under Propeller Slipstream Interference2026-99-236510/30/2026
The present study concentrates on aerodynamic behavior and static stability characteristics, and propeller slipstream interference of twin- boom unmanned aerial vehicles (UAVs) with three typical tail configurations. This study adopts a coupled VSPAERO approach, which incorporates a VLM-based solving technique and the Actuator Disk Model. Simulation results under the no-slipstream baseline condition reveal that the inverted V-tail layout delivers the highest aerodynamic efficiency. Its lift/drag ratio is considerably superior to those of the U-tail and inverted U-tail designs. While all configurations maintain good stability in longitudinal and directional axes, only the U- tail exhibits lateral static stability. When propeller slipstream is introduced, the lift-to-drag ratio of all layouts decreases noticeably, mainly due to strong local low-pressure regions that substantially increase pressure drag. In addition, the slipstream has little influence on longitudinal static stability, leaving pitching moment characteristics nearly unchanged. Nevertheless, the swirling flow generated by the propeller effectively improves lateral stability. It enhances the stabilizing effect of the U-tail, turns the lateral instability of the inverted U-tail into stable behavior, and reduces the lateral unstable characteristics of the inverted V-tail. In addition, the findings show that the sideslip angle β’s impact on the yawing moment is affected by the angle of attack α. Coupling between α and β, as well as propeller slipstream, should be considered in directional stability analysis. Increasing propeller diameter appropriately improves aerodynamic efficiency and directional static stability, while placing the propeller at or slightly forward of the baseline position minimizes adverse tail interference.
Wen, Jiayi
Hybrid TDOA/AOA Localization and Tracking Method for Multi-Station Cooperative Passive UAV Detection2026-99-236210/30/2026
To address geometric precision degradation and tracking divergence in single TDOA or AOA systems, this paper proposes a multi-station UAV tracking method integrating TDOA/AOA hybrid localization with nonlinear filtering to overcome precision degradation and tracking divergence in single-sensor systems. A Weighted Least Squares (WLS) method via pseudo-linearization provides reliable initial coordinate estimations, followed by an Unscented Kalman Filter (UKF) for continuous trajectory tracking. Simulations demonstrate that the proposed architecture eliminates network blind zones and robustly handles abrupt target maneuvers. Compared to the standard EKF, it rapidly suppresses peak RMSE to ~22 m and achieves a steady-state error of 10-15 m. This approach offers a high-precision, rapidly converging passive tracking solution for urban low-altitude defense.
Shen, Huaming, Wang, Yiting, Lv, Zhenbin, Zhou, Haosu, Lu, Wenbin
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