Abstract:The integrated missile-aircraft has the characteristics of long-term cruise and high-speed penetration, which can be used for target reconnaissance and attack. In order to give full play to the advantages of cluster attack, it is of great significance to break through the guidance and control technology for cooperative attack in complex environments. The basic ideas of exploring multi-UAVs cooperative control with spatio-temporal constraints are from single drone control to cluster dynamic coordination and from single constraint to space-time comprehensive control. This paper introduces the application background of swarm attack, and analyzes the status of multi-UAVs coordinated strike system. Key technologies such as impact time control guidance(ITCG), impact angle control guidance(IACG), and cluster cooperative control with spatio-temporal constraints are explored. The shortcomings of current UAV cooperative application are summarized, and the future research directions are prospected. The research of this paper has certain significance for the application of swarm attack operations and the design of multi-UAVs cooperative controllers.

Abstract:Borescope is currently the most applied non-destructive testing method in the process of aero-engine inspections and is the only way to obtain borescope images. In recent years, artificial intelligence methods such as deep learning have been applied to aero-engine damage classification and detection, some effective methods are proposed to achieve intelligent inspection of aero engines which have significant value for industrial applications. Summarizes the benefits and the disadvantages of aero-engine borescope inspection and its development, the progress in the application of artificial intelligence methods such as expert system and machine learning to engine borescope detection images, and some of the challenges in achieving intelligent aero-engine borescope inspection.

Abstract:With the diversification of UAV application scenarios, many scholars have studied UAV path planning algorithms. This paper summarizes the UAV path planning algorithms commonly used by scholars in recent years, summarizes the principles, applicable scenarios, advantages and disadvantages of the algorithm, and makes a prospect of UAV path planning algorithms based on the development status of UAVs.

Abstract:Sonic boom suppression is a key technology that must be broken through in the development of a new generation of supersonic civil aircraft. The reasonable optimization of configuration parameters can make the aircraft have good sonic boom characteristics. In order to break through the bottleneck of evolutionary algorithm in optimizing large-scale design variables, a hierarchical optimization method based on data mining is proposed, the decesion tree algorithm in data mining is used to extract the design knowledge, obtain the hierarchical information of design variables, and guide the configuration optimization of low sonic boom aircraft. For a low boom supersonic aircraft, five configuration parameters, including sweep angle, aspect ratio, taper ratio, dihedral angle and fuselage slenderness ratio, are selected as design variables, carry out numerical experiments of hierarchical optimization, and compare with the integrated optimization. Because the optimization process of evolutionary algorithm is random, 100 numerical experiments are carried out to obtain statistical results.The results shows that the hierarchical optimization can obtain the optimal solution consistent with the integrated optimization, and the convergence speed of hierarchical optimization is significantly faster than that of integrated optimization, and the performance of different optimization processes is more robust.

Abstract:In order to avoid the problem that the support points selected by the traditional single absolute error criterion are not interpolated accurately when the heat flux is small when the radial basis function is used for hypersonic heat flux interpolation. In this paper, a radial basis function interpolation procedure with double error criterion is proposed. In this process, the absolute error criterion is used to select a certain number of support points, and then the relative error criterion is used to select another part of points. The numerical experiments show that the double error criterion can ensure the interpolation accuracy at both large and small heat flux and can avoid the problem of negative heat flux which is easy to appear in the interpolation results caused by the traditional single absolute error criterion.

Abstract:Tire stiffness is one of the important parameters of tire dynamics model. The influence of tire stiffness on the shimmy of large civil aircraft nose landing gear can provide reference for the anti-shimmy design of large civil aircraft nose landing gear from the perspective of tire design. The nonlinear mathematical model of the front landing gear shimmy was established, and the shimmy region diagram of different tire torsional stiffness and tire side bending stiffness was calculated by using Matlab/Matcont software. The influence law of tire torsional stiffness and tire side bending stiffness on the shimmy of the front landing gear was studied, and the sensitivity of the two on the shimmy of the front landing gear was compared. The results show that the sensitivity of tire torsional stiffness to the impact of nose landing gear shimmy is greater than that of tire lateral bending stiffness. When the positive torque coefficient decreases by 1%, the maximum critical damping of torsional shimmy decreases by 0.88%, and the minimum critical damping of lateral shimmy increases by 33.87%. Reducing the torsional stiffness of tire and increasing the lateral stiffness of tire are beneficial to restrain the yaw of large civil aircraft nose landing gear.

Abstract:Temperature is one of the important characteristic parameters of civil aircraft hydraulic system performance. To effectively realize the temperature monitoring of hydraulic system, the method of Kriging model based on atomic search (ASOKM) is proposed based on Kriging model and atomic search algorithm (ASO). Firstly, the temperature fault causes of hydraulic system are analyzed, and fault logic diagram is established to clarify the characteristic parameters affecting the hydraulic system temperature. Then, combined with the quick access recorder (QAR) data, the modeling principle of ASOKM method is discussed. Finally, the effectiveness of the proposed ASOKM method is verified by the temperature monitoring analysis of domestic civil aircraft hydraulic systems. The results show that the training and monitoring average absolute errors of the ASOKM method are lower than the response surface method (RSM), Kriging, and back-propagation-artificial neural network (BP-ANN) models, and have higher accuracy, efficiency, and robustness. The proposed ASOKM method can provide a reference for reliability analysis, fault diagnosis, and predictive maintenance of the hydraulic system.

Abstract:Aiming at the characteristics of complex degradation trend of aero-engine, this work presents a dilatated convolution network based on multi-feature attention model to predict the remaining useful life (RUL) of aero-engine. In this model，dilated convolution is used to enhance the ability to extract temporal features of sequence data and residual connections are established to improve the problem of gradient disappearance in traditional convolutional networks. Firstly, the raw input data are reconstructed by sliding time window of fixed length to intercept data along the time dimension. Then the dilated convolutional networks extract the temporal features of corresponding to each feature respectively. In the end, the feature attention mechanism is used to calculate the relative importance of features. Experimental results demonstrate that proposed algorithm has better accuracy of RUL estimation than the other comparative models.

Abstract:During flight, pilots need to receive a large amount of information in a short time and make correct judgments and decisions. The cognitive processes such as perception, judgment and decision-making will be affected by excessive cognitive load and affect flight safety. Firstly, the physiological data of flight cadets during different flight missions were obtained through flight simulation experiments; Then, the characteristics of RESP and ECG signals were extracted by time-domain and frequency-domain analysis, and the indexes that can reflect the level of cognitive load are selected by statistical methods. Finally, in the light of ensemble learning algorithm, combined with support vector machine, k-nearest neighbor, artistic neural network and other methods, a cognitive load evaluation model is established based on multiple physiological signals. Furthermore, it is compared with single models. The results show that the pilot cognitive load evaluation model established in this paper has a high accuracy rate and can better reflect the pilot’s cognitive load level.

Abstract:The civil aircraft flight deck door system is installed in the aircraft cabin to block the cockpit area and cabin area. In addition to providing normal access to the cockpit, it must have bullet proof and intrusion prevention functions to prevent non-crew members from seizing control of the aircraft and provide safety protection for crew members. This paper starts with the interpretation of the airworthiness provisions for the flight deck door system to resist penetration, studies and interprets the airworthiness certification requirements, raises a evaluation method of civil aircraft flight deck door to resist penetration, gives the test implementation details and requirements such as bullet selection, dangerous trajectory confirmation, shooting point screening, test piece configuration preparation, and verifies it based on the development of a civil aircraft flight deck door system and the airworthiness certification for resisting penetration, The results show that the method is effective and can show the compliance of the clauses. The research content of this paper can provide reference for aircraft flight deck door design and development, airworthiness compliance analysis and verification, and airworthiness certification of relevant clauses.

Abstract:During the forming of aramid paper honeycomb sandwich component of aircraft composites in the autoclave, the adhesive layer between honeycomb cells will crack or even be damaged, which will affect the mechanical properties of the parts. The tensile properties, compressive properties, shear properties and thermal properties of aramid paper honeycomb core were obtained by testing. Meanwhile, numerical simulation of thermo-mechanical sequential coupling of the whole honeycomb sandwich component and mechanical simulation of the local core area were carried out by combining the finite element analysis method and the inversion method. The results show that the thermal stress during the forming process will not cause the adhesive layer between honeycomb cells to crack; The difference of pressure difference between honeycomb cells required for adhesive layer’s slight destruction and complete destruction is positively related to the initial normal fracture stress of adhesive layer; When the number of loaded honeycomb cells is less than 20, the pressure difference required for the adhesive layer’s slightly destruction is independent of the number of honeycomb cells, but the pressure difference required for the the adhesive layer’s complete destruction decreases with the increase of the number of loaded cells.

Abstract:For a civil transport helicopter, the acquisition of type certificate shall follow requirements specified in CCAR29, among which CAT-A performance is a typical feature of transport helicopter, meanwhile CAT-A performance flight test is the best way to verify its conformity. Based on the relative CAT-A performance airworthiness documents issued by CAAC, this paper analyses the background of CAT-A take-off performance, researches relative clause requirements and compliance method, discusses flight test techniques concerning H-V domain、CAT-A take-off flight path、CAT-A continued take-off、rejected take-off、 and the determination of final take-off decision point, making CAT-A performance take-off decision point flight test risk management and control measures for clear runway. The CAT-A performance take-off decision point flight test method specified in this paper has effectively instructed the CAAC certification flight test toward AC312E, AC313, laying a sound foundation for the fore said helicopters to acquire CAAC type certificates. Research of this paper could provide referential value to CAAC test pilots as well as reference to applicant test pilot.

Abstract:In view of the relaxation and ungrooving of the power rope of the antenna deployment mechanism in the process of antenna deployment and folding, the deployment mechanism of the high precision satellite umbrella antenna is taken an the research object. The working principle of the antenna deployment mechanism ia analyzed. The equation of motion of the deployment mechanism is obtained by analytical method. Combined with the structural parameters of the parts of the antenna deployment mechanism, the relaxation law of the power rope of the deployment mechanism is obtained. Taking the structural parameters of the deployment mechanism as the design variable and minimun relaxation of the power rope as the goal, the structure optimization model of the deployment mechanism is obtained. The structural parameters of the optimized deployment mechanism are obtained by simulated annealing algorithm. The relaxation of the power rope of the optimized deployment mechanism is reduced by 90% compared with that before optimization, and the optimization effect is remarkable.

Abstract:Volume and pre-charge pressure are the key parameters of the gas-filled accumulator, which have a great influence on its dynamic performance (the output performance of pressure and flow under working conditions).To provide a reference for the reasonable calculation and selection of accumulator parameters. , this paper takes the calculation and selection of a certain type of aircraft rudder surface emergency gas accumulator as an example, based on the hydraulic component library in the Hypneu simulation software, combined with the main design parameters of this type of aircraft hydraulic system and the working principle of the emergency accumulator, to establish an accumulator The simulation model of the actuation of the accumulator is established, and the test points are set in Hypneu to record the simulation curve, and the influence of the key parameters of the gas-filled accumulator on its dynamic performance is explored by analyzing the simulation curve. In addition, this paper combines theoretical calculation and simulation analysis to propose a set of Accumulator parameter selection method, and the selection method is verified by experiments. The results show that: the greater the pre-charge pressure of the accumulator, the smaller the effective volume output by the initial accumulator, and the reduction of the pre-charge pressure increases the effective volume at the same time. The output pressure of the accumulator will be reduced, the experimental results are close to the simulation results, and the accumulator selected by this method can meet the actuation requirements.

Abstract:In order to improve the calculation efficiency of the obstacle limited takeoff weight calculation model of a domestic civil transport aircraft, its algorithm was studied in detail, and the reasons for the low calculation efficiency of the model were analyzed. On this basis, an optimized calculation model was established in combination with relevant civil aviation regulations. The obstacle limited weight, acceleration height and calculation time of the optimization model and the original model under different obstacles and different wind speeds were calculated and compared. The results show that the obstacle limited weight and acceleration height calculated by the optimization model are basically the same as those calculated by the original model; The original model uses the maximum acceleration height method to determine the obstacle limited takeoff weight, there are two unknowns: takeoff weight and maximum acceleration height, more iterations and longer calculation time; The optimization model adopts the method of minimum acceleration height, only the takeoff weight is an unknown quantity, which can shorten the calculation time and greatly improve the calculation efficiency on the premise of ensuring the accuracy of the calculation results; While calculating the take-off flight path, judging whether the aircraft can cross the obstacles can reduce the calculation time ; The optimization model also has reference significance for the calculation of obstacle limited takeoff weight of other types of civil transport aircraft.

Abstract:Structural strength is a key concern in fighter"s design and development. Fatigue strength of an aircraft determines important indicators such as safety, durability and reliability of the aircraft. Full-aircraft fatigue test is an important method to verify whether the fatigue strength of aircraft structure meets the design requirements. This paper introduces the development history and current situation of the full-aircraft fatigue test technology at home and abroad, comprehensively analyzes the full-aircraft fatigue test technology in our country, and summarizes the important technical achievements of the full-aircraft fatigue test of a new type of fighter, including aspects of test load spectrum, loading and bearing, boundary simulation, power system, data processing, damage detection, health monitoring, and so on. This paper provides important technical support for other aircraft fatigue tests and proposes the development direction and planning for the full-aircraft fatigue test technology.

Abstract:Facing the future combat scenario with manned and unmanned aerial vehicle cooperation, real-time and accurate air combat decision-making is the basis of winning. Aiming at the above scenarios, this paper abstracts the characteristic model of single agent, and proposes an algorithm based on proximal policy optimization to obtain the air combat decision sequence by using reward and punishment incentive in the real-time interaction with the environment. The simulation results show that the algorithm proposed in this paper can adapt to the complex battlefield situation and get a reasonable decision-making strategy after training and learning.

Abstract:As the development of aircraft demand recently years，new material and new craft are emerging, the test and validation technology of aircraft will also face new challenges. As the key measures of networking and intelligentization, 5G technology will promote the innovation and reform of strength test technology effectively. First, the present situation and development trend of structural strength test technology for full-scale aircraft was introduced briefly, and one new idea of structure strength test for full-scale aircraft based on 5G was proposed through the research of the demand of full-scale aircraft strength test. Second, the incidence matrix of test and 5G technology was formulated through the analysis of advantages and features of 5G for strength test of aircraft，the typical test scenarios based on 5G were planned. Finally, the development and application of inspection and monitor system based on 5G was carried out for fatigue test of one type of aircraft successfully, the results show that the intelligent facilities based on 5G technology will improve the level of test significantly and have significant implication for intelligentization of test.

Abstract:Flight load analysis is a complex and arduous task, and developing a fast analysis method during the conceptual design stage is of great importance to improve the efficiency of flight load calculation. Based on the small disturbance linear analysis theory, the theoretical calculation methods of wing-body load, horizontal tail load, vertical tail load, control surface hinge moment, and the engineering calculation methods of lift, shear and bending moment of lift surface are summarized. A mathematical model of a certain single seat competitive aircraft was established in the Matlab environment, taking the configuration dimension, mass characteristics and aerodynamic derivative as inputs, the response process of aerodynamic load, control surface hinge moment, shear and bending moment are obtained. The results show that the simplified method can quickly get the dynamic parameters with less input data, and the calculation results can be used to satisfy the load requirements of structural design in the conceptual design stage.

Abstract:Stall/spin has always been the most serious safety problem faced by general aviation aircraft in left boundary of flight envelope. The statistics of stall/spin accidents show that, the catastrophic consequences of stall/spin cannot be avoided although the aircraft has the ability to recover from spin. The text explains the concept of "layered defenses", and analyzes the requirements of stall/spin in the new FAR-23 airworthiness standards and the accepted compliance methods based on this concept. The construction method of a multiple defense system for the safety of general aviation aircraft in left boundary of flight envelope are proposed by improving the pilot"s state awareness, enhancing the aircraft"s departure resistance and reducing the damage of loss of control which will help general aviation aircraft better meet the requirements of the stall/spin airworthiness standards, and achieve the purpose of improving flight safety in left boundary of flight envelope.

Abstract:The new generation information technology, such as Big Data, artificial intelligence, has an important role in promoting the digital transformation of the aviation manufacturing industry. In view of the characteristics of multisource and heterogeneity, few samples, and strong correlation of data in the aviation manufacturing industry, utilizing a new generation of knowledge engineering technologies such as knowledge graph with the ability of structured description and efficient management of data, this paper established a technical system and process for aviation data intelligence based on the event graph. The research focused on the technical methods such as ontology modeling, event relationship recognition, event extraction, and event disambiguation for aviation data. With a selection of aviation product quality data for data intelligence technology validation, the research team carried out a series of work pertinent to application and prototype system developments, including classification of quality problem causes, construction of quality event graph, logic knowledge push, etc., to assists the identification of quality problem and the rapid response to quality issues. The results indicated that the technical system and path of using data and knowledge to carry out digital intelligent quality management are feasible, and the quality knowledge extraction algorithm based on event graph has strong practicality, and provided support for promoting the application of digital intelligence in the whole life cycle of aviation manufacturing industry.