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During the forming of aramid paper honeycomb sandwich component of aircraft composites in the autoclave, the structure bears thermo-mechanical coupling case, and it may exist the phenomenon of the honeycomb crack during the forming. The tensile, compressive, shear and thermal properties of aramid paper honeycomb core are obtained by testing. Meanwhile, the numerical simulation of thermo-mechanical sequential coupling of the whole honeycomb sandwich component and the local core area are 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, but gas pressure will. The difference value 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. The pressure difference required for the adhesive layer′s complete destruction is decreased with the increase of the number of loaded cells.

Different phenolic resins have a direct impact on the properties of aramid paper honeycombs. It is important to study the relationship between phenolic resin and honeycomb properties. Two different phenolic resins are used to prepare aramid paper honeycomb core materials, and the compression properties, shear properties, flame retardancy and dielectric properties of the prepared honeycomb core material are tested. Combining the observation of resin end face resin distribution and contact angle measurement, the reasons for the difference in performance of honeycomb core materials prepared by two kinds of resins are analyzed. The results show that the temperature resistance of the resin itself directly affects the temperature resistance of the honeycomb and the volatilization rate of solvent water in the resin and the surface tension between the resin and the aramid paper affect the resin distribution of the resin on the honeycomb wall. When the content of the honeycomb core resin is the same, the resin rubber column at the end of the joint is beneficial to increase the compressive strength of the honeycomb core material, but the accumulation of the resin at the end of the node reduces the wall thickness of the honeycomb, resulting in a decrease in the shear strength and modulus of the honeycomb.

Aperture-type and patch-type frequency selective surfaces (FSS) were prepared by using carbon fiber paper containing carbon fiber. Using honeycomb as the matching dielectric layer, microscopic characterization of carbon fiber distribution in carbon fiber paper was performed by stereo microscope, the reflectivity of the composite FSS structure was tested by a vector network analyzer. The influences of unit shape, carbon fiber content in carbon fibre paper and carbon fiber length on the wave absorbing performance of aperture type FSS and patch type FSS were studied with the same matrix area ratio of carbon fiber paper. The results show that in the range of 2-18 GHz, the absorbing properties of aperture-type FSS and patch-type FSS are related to the content and length of carbon fiber in carbon fiber paper, and has nothing to do with the shape of the unit. At 6-18 GHz, with the same the ratio of the matrix area of carbon fiber paper, the shape of unit, the length and content of carbon fiber in the carbon fiber paper, the absorbing properties of aperture-type FSS are better than that of patch-type FSS.

Considering the rapid time-varying channel conditions and large Doppler frequency fluctuations caused by high-speed movement of unmanned aerial vehicles, this paper proposes a non-stationary channel emulation scheme for Unmanned Aerial Vehicles(UAVs) using a field-programmable gate array platform. The proposed scheme adopts the sum of frequency modulation method to generate non-stationary channel fading and proposes a real-time algorithm for generating channel parameters to improve the real-time performance of channel emulation and ensure the real-time updating of channel status. In addition, to address the issue of power random fluctuation caused by large Doppler frequency fluctuations, this paper designs an adaptive power equalization module that ensures the stability of fading power by limiting the maximum fluctuation to only 1.13%. Finally, the results of hardware resource consumption analysis demonstrate that the proposed approach in this study significantly reduces the utilization of storage resources compared to replay-based and pre-stored solutions, with reductions of 52.44% and 9.31%, respectively. This makes the proposed approach well-suited for simulating long-duration non-stationary channel fading in UAV scenarios. Additionally, the measured analysis results demon-strate that the channel characteristics output by the proposed hardware emulation scheme, such as path loss and Doppler power spectrum density,closely align with theoretical results when compared to the emulation scheme without the equalizer. This research can be applied to the design and optimization of UAVs communication systems.

Target assignment is the core part in the command and control process, and the optimization of the allocation mode is of great significance for improving the air defense and anti-missile combat capability. In order to improve the robustness, applicability, game antagonism and other combat performance of air defense and anti-missile target allocation, so as to cope with the current complex and changeable battlefield environment, this paper proposes the target allocation architecture establishment of multi-mode fusion, and adaptively improve the commercial order-type service mode. The improvement of three kinds of dispatching models, that are “dispatching order” “grabbing order” and “dispatching- grabbing order fusion”, are defined as military models. By using the US department of defense architecture framework (DoDAF) to establish a new target allocation architecture of “other allocation” “self-allocation”and “combination of other allocation and self-allocation”. With the introduction of Perti net model, the reachable map of Petri net model is constructed and analyzed. Through the simulation experiment platform, the complex combat scenario is constructed to verify the feasibility of the distribution strategy mechanism. The results show that each of the three strategies has its own advantages. The multi-strategy combination designed in this paper has greater advantages than the traditional single strategy in matching time, success rate and utility value.

Target tracking is to predict the state of the current target according to the target context information of video sequence. Deep learning is gradually widely used in the field of target tracking. This paper elaborates on the development background of target tracking algorithms and deep learning, and reviews traditional target tracking. Based on different network task functions, target tracking algorithms based deep learning is divided into: deep learning target tracking algorithm based classification, deep learning target tracking algorithm based regression, and target tracking algorithm based on the combination of regression and classification. This paper selects representative target tracking algorithm for experiments, compares the characteristics of different algorithms. Finally, this paper analyzes the problems of current target tracking algorithms based on deep learning, and prospects the future development direction. The experimental results show that deep Siamese tracking networks are superior in accuracy and speed, which is becoming the mainstream tracking algorithm framework at present.

In the process of conducting the atmospheric waveguide transmission characteristic test in the sea area, it is found that whether the over-the-horizon ships can be detected by the Automatic Identification System (AIS) has a great correlation with the strength of the atmospheric waveguide. Therefore, this paper proposes a real-time detection method of the atmospheric waveguide based on AIS. This method can detect whether there is an atmospheric waveguide between two points beyond the horizon in real time, which effectively makes up for the defect that the current atmospheric waveguide detection method can only detect the current area. This paper also gives the calculation method of atmospheric waveguide transmission loss based on AIS and a visualization method of atmospheric waveguide detection results. The comparison between the experimental data and the simulation results shows that the method in this paper has high accuracy and certain practical value.

With the refinement of civil aircraft technology and the enhancement of product complexity, civil aircraft design has changed from traditional text-based system engineering to model-based system engineering, the expression of the system has also transformed from text-centered to model-centered. To further improve the model quality and correctness of aircraft system modeling, this paper explores the applicability of model-driven and verification-oriented system engineering methods in the field of civil aircraft design, and establishes the system engineering practice framework of civil aircraft design, which can ensure the rapid design and efficient delivery of civil aircraft. Firstly, starting from the Harmony SE modeling method, the workflow and modeling ideas of system are introduced; then the noticeable problems in the practice of civil aircraft system engineering are analyzed, and the system engineering practice of civil aircraft design is established with the support of the applicability of the Harmony SE method; finally, the fuel tank pressurization component is taken as the research object of the practice system in component-level. The results show that the system engineering practice framework of civil aircraft design and method proposed in this paper can correctly and reasonably allocate design requirements and establish a complete system model, which is helpful to improve the efficiency and accuracy of civil aircraft design at this stage.

Compared with the traditional source radiated power estimation method, the matched-field source radiated power estimation method can obtain more accurate estimation results. However, its performance is greatly influenced by environmental mismatch. This paper defines the impact factor of environmental mismatch to quantify the impact of environmental mismatch on the acoustic transfer function and the matched-field source radiated power estimation method. It determines that the key to improve the robustness of environmental mismatch is to accurately estimate the acoustic transfer function. In the traditional matched-field source radiated power estimation method, the search domain of the acoustic transfer function is a distance-depth two-dimensional plane and does not contain the true acoustic transfer function when the environment is mismatched. Therefore, the estimation results of the acoustic transfer function are bound to deviate from those of the true acoustic transfer function. The paper expands the search domain dimension to a three-dimensional search domain that contains distance, depth and uncertain parameter sets. The true acoustic transfer function is included in the search domain. Thus the optimal alternative acoustic transfer function is equal to the true acoustic transfer function. The objective function for the three-dimensional search domain is constructed. The smaller the absolute value of the objective function, the less the acoustic transfer function estimation deviates from the true acoustic transfer function. The source radiated power is estimated more accurately when the alternative acoustic transfer function estimation corresponding to the minimum absolute value of the objective function. The simulation results verify the theoretical analysis results.

The replenishment of water resources in a space station is essential for achieving an astronaut's long-term and on-orbit residence. Recycling his or her urine is one of important and major ways of wastewater recovery. However, traditional urine treatment methods have the disadvantages of equipment that takes large space, complex procedures and low atomic utilization. Therefore, this paper designs a novel wastewater reuse system that treats urine based on urea electrooxidation technology, introduces methane fuel cell coupled with the Sabatier reactor and hydrogen-oxygen fuel cell to further utilize urine treatment products and to allocate water resources precisely in the space station through designing grading treatment and dynamic control systems. The wastewater reuse system designed in the paper contributes to saving valuable space and reducing energy consumption during urine treatment, thus improving water recovery rate and optimizing resource allocation.

The airport collaborative decision making can effectively improve the operational efficiency of airports， so as to improve the operational efficiency of the whole civil aviation transportation network. The relevant standards，policy files and research papers of collaborative decision making are compiled in this paper. The development history of in airports and the current situation of research and application on collaborative decision making in academia and industry，both in China and abroad are collated. The future development trend of collaborative decision making in airports and the challenges faced by collaborative decision making in the current period are discussed and analyzed. Some suggestions for the development of collaborative decision making in airports based on the actual situation in China are given. The theoretical support and basis for improving the operational efficiency and economic benefits of airports and the whole air transportation network are summarized. The study in this paper can provide theoretical support and basis for operational efficiency and economic efficiency of the whole air traffic network.

The development of digital technology and artificial intelligence technology hastens the progress in the field of digital security. As the latest technology in the field of natural language processing, ChatGPT has become the focus of attention around the world since its birth, and also has a significant impact on the field of digital security. This paper reviews the basic situation of ChatGPT, summarizes and combs the basic concepts of digital security, and then examines and analyzes ChatGPT from the perspective of digital security. It analyzes and sorts out the impact of ChatGPT from six aspects: ChatGPT’s own security, intellectual property security, network security, information security, social security and cognitive security to clarify twenty specific digital security risks. On this basis, the impact of ChatGPT on the fields of equipment intelligence analysis, equipment production and development, and equipment logistics support is analyzed. Finally, this paper provides countermeasures and suggestions from the perspectives of ChatGPT industry development, regulatory construction, false information disposal, and equipment intelligence development.

This paper proposes the use of aperture sharing synergistic operation in the structure of the metalens, together with the rational selection of the scattering unit size according to the linear relationship between the output phase and frequency of the scattering unit, and the selection of the slope of the phase variation with frequency, combined with the modulation of the phase change material Ge2Sb2Te5 crystallization rate m value, in the set wavelength band, for different wavelengths of incident light through the metasurface can produce a uniform phase distribution. The method is used to achieve a polarization-insensitive achromatic metalens in the 9.5-13 μm continuous wavelength band by adjusting the m value of the phase transition material Ge2Sb2Te5 crystallization rate and producing a phase distribution with a uniform focal length for different wavelengths of incident light passing through the metasurface. The simulation results show that the focal length of the achromatic metasurface varies by 3.57 μm in the working band, with an error of about 4.3% from the set focal length, and the full width of the half-peak of the focal point at all wavelengths of incidence reaches the diffraction limit, and the focusing efficiency exceeds 60%. The achromatic metalens proposed in this paper provides a new idea for the design of achromatic metasurfaces and promotes the research of phase change materials in broadband achromatic metasurfaces.

The precise detection of military targets under complex conditions is a key factor to enhance the ability of war situation generation and prediction. The current technology can not overcome the problems of smoke and occlusion interference, target height change, and different scales in aerial video. In this paper, a multi feature cross fusion and cross layer cascade aerial military target detection algorithm (YOLOv5-MFLC) is proposed. Firstly, aiming at the high confidentiality of the military targets and the shortage of battlefield aerial image resources, a real scene based aerial military target dataset is constructed, and the methods of random splicing and random extraction embedding are used for data enhancement in order to improve the diversity and generalization of targets. Secondly, aiming at the problem of complex background interference, a multi feature cross fusion attention mechanism is constructed to enhance the available information of target features. Finally, for the multi-scale problem of targets in aerial images, a cross layer cascaded multi-scale feature fusion pyramid is designed to improve the detection accuracy of cross scale targets. The experimental results show that, comparing with the existing advanced detection models, the detection accuracy of the algorithm in this paper has been greatly improved. The average accuracy of the algorithm can reach 81.0%, which is 5.2% higher than the original network. In particular, it has reached 55.9% in the smaller target category "person", which is 9.4% higher. And the experimental results further show the usefulness of the improved algorithm for small target detection. At the same time, the detection rate of this algorithm can reach 56 frame/s, which can effectively achieve accurate and fast detection of battlefield targets, and has certain experience value for guiding complex modern wars.

With the increase of satellite power, the current-carrying and heat dissipation of power cable is increasing significantly and the thermal safety problem becomes prominent. Therefore, the need for accurate modeling and fine design of power cable becomes increasingly urgent. In this paper, the thermal analysis modeling method for high-power cable bundle is proposed based on ground test data, and the heat transfer parameters at the installation and bundling points are obtained. At the same time, the thermal effect of cable bundling is quantitatively analyzed by simulating the splitting and binding power cable bundle. The result indicates that enhancing the radiation heat transfer between cables and the surrounding environment is the most effective means to improve the heat dissipation condition of cable bundles. The thermal model of high-power satellite power cable proposed in this paper can be used as an important basis for the prediction of on-orbit temperature and fine laying design of the power cable.

Electromagnetic metamaterial is an artificial composite composed of periodic subwavelength microstructure，which has a strong conduction regulation or absorption effect on electromagnetic wave，and it has been widely studied in the field of stealth design of aviation weapons and equipment. In this paper，the concept of electromagnetic metamaterial is introduced firstly，and the latest research progresses of electromagnetic control metamaterial，electromagnetic absorbing metamaterial，active tunable metamaterial and intelligent metamaterial are reviewed. Then，the stealth mechanism and the application research status of electromagnetic deflection metamaterial，electromagnetic absorbing metamaterial and frequency selective metamaterial are introduced. It is analyzed that the rich stealth mechanism and the strong designability are the main advantages of electromagnetic metamaterials as distinct from the traditional absorbing materials. For the development of electromagnetic metamaterial，this paper puts forward three suggestions from expanding the absorbing spectrum，enhancing the absorbing performance，and smart tunable of absorbing ability，specifically including the expansion of absorbing spectrum to infrared，laser and ultraviolet band，further improving the broadband absorbing ability，and intelligent adjusting the absorbing frequency band.

Based on the military net evaluation report published by Rand Corporation, this paper independently explores the combat effectiveness evaluation theory driven by the analytical model of the US military, and studies in detail the analysis and evaluation method of precision guided weapons attacking the airbase in the joint integrated contingency model (JICM), also carries out the deduction and calculation. The results show that the air force aircraft sorties ability is greatly affected by the damage of the airbase, which plays a vital role in the fight for air control. This paper has positive theoretical significance for the in-depth understanding and application of modern combat simulation deduction and evaluation.

In the large-scale satellite constellation technology, the establishment of satellite internal network is the top priority. As the network capacity of the constellation continues to expand and the number of satellite nodes continues to increase, the previous multiple access technology can no longer meet the network capacity requirements of large-scale constellations. In order to meet the requirements of massive connections of satellite nodes in large-scale constellation for new networking communication methods, this paper establishes a sparse spread spectrum inter-satellite communication system with sparse code multiple access (SCMA) as the core. At the same time, the channel characteristics of large-scale constellation are analyzed and the corresponding inter satellite channel model is established in MATLAB. Based on this channel model, the performance of the system is simulated. The simulation results show that under the same signal energy to noise ratio, the sparse spread spectrum inter-satellite communication system established in this paper has better BER characteristics compared with orthogonal frequency division multiple access (OFDMA) and code division multiple access (CDMA). In addition, the threshold signal energy to noise ratio of the system is more than 2 dB better than that of CDMA technology, and the utilization rate of time-frequency resources is 50% higher than that of OFDMA technology.

Accurate and fast random error estimation is essential to improve satellite control. In this paper, the random error of the satellite being launched into orbit is explored. According to the uncertainty matrix of six satellite orbit parameters associated with the project, the uncertainty of the orbit position in the three axes of the geocentric inertial frame of reference is calculated via the propagation rate of the covariance matrix. Then, the random error probability density of the satellite position is constructed for normal distribution. The surface of the error with the same probability density is approximated as an ellipsoid, the size is deduced along with the ellipsoid's shape and direction, and the satellite's spatial position probability is obtained. Monte Carlo method and STK software were employed to simulate low-earth orbit micro-nano satellite launching into the same orbital position. It is confirmed that the results obtained via the theoretical model are in line with practice. Therefore, the ellipsoid theory proposed in this paper can be used to describe the satellite random position error.

Cooperative guidance is an important research direction in the field of missile guidance in recent years. Based on the classification criteria such as mission requirements, communication structure, constraints, etc., this paper classifies and summarizes the current multi-missile cooperative terminal guidance strategies, and combs the research status of time cooperative guidance law, spatial cooperative guidance law, and spatial-time cooperative guidance law. It analyzes the key issues for cooperative guidance at this stage, such as the estimation problem of remaining flight time, the cooperative interception problem of maneuvering targets, the information registration problem of closed-loop cooperative guidance, the communication problem of closed-loop cooperative missile, etc. Finally, this paper proposes four research directions of the future multi-missile cooperative terminal guidance technologies: cooperative interception technology for large maneuvering targets, robust cooperative guidance technology for real scenes, intelligent autonomous cooperative guidance technology, and parallel interactive design technology for cooperative operations.

This paper gives a full description of development of foreign air-to-air missiles in 2022. It pre-sents the latest advancement of AIM-9X, AIM-120, Modular Advanced Missile, ASRAAM, IRIS-T, FCAAM, Meteor, innovative missile technologies, R-37M, Astra BVRAAM, Turkish new air-to-air missiles. In the end, the paper summarizes the new development features of air-to-air missiles.

With the development of weapons equipment, operational concepts, and communication technology, data link technology is updated constantly. Data link plays an important role in the trend of "no link, no missile" no missile, no war" in air combat. Hypersonic vehicles have become the commanding heights in the air combat system due to their unique characteristics, such as high speed and cross-domain. Data link technology provides support for maximizing the operational effectiveness of hypersonic vehicles. Conversely, the development of hypersonic vehicles broadened the boundaries of data link technology, and the requirements for index parameters (such as transmission rate, throughput, packet loss rate, and delay) vary in different combat missions. In recent years, the rapid development of emerging technologies such as 5G, the Internet of Things, cloud computing, and artificial intelligence has accelerated the continuous advancement of battlefield situational awareness from physical domains, and information domains to cognitive domains. Based on a review of the development of data links, this paper analyzes the challenges faced by hypersonic aircraft data links, which have the characteristics of large envelope flight. This paper discusses the top-level requirements and key technologies of the hypersonic vehicle data link.

2.5D woven composite has great application prospect in high bypass ratio commercial turbofan engine fan blades due to its comprehensive advantages in mechanical properties and complex component forming. For the aero-engine fan blades, vibration fatigue is a working condition that can not be ignored. At present, the research on vibration fatigue behavior of 2.5D woven composite is limited, and there is a lack of numerical model for vibration fatigue behavior simulation. In this paper, a multi-scale model for the first-order flexural vibration fatigue behavior of a 2.5D woven composite cantilever beam simulating the root of engine blade was established. Adopting the fatigue loading simulation method which adopted the fixed cycle jumping strategy, and the damage initiation criterion and fatigue stiffness degradation model based on the leading fatigue failure mechanism, the vibration fatigue test processes of the wrap and weft specimens were simulated respectively. With the established multi-scale model, the stress field in the unit cell of the dangerous part of the specimen was analyzed, and the damage state of the specimen after the vibration fatigue test was predicted. The numerical simulation results are consistent with the observed fracture morphology after the test, which verifies the validity of the proposed multi-scale prediction model for vibration fatigue of 2.5D woven composite materials. In addition, based on the multi-scale prediction model of vibration fatigue proposed in this paper, the damage states in the unit cell at the working section of the wrap specimen with the accumulation of fatigue loading cycles simulated, which is helpful to understand the evolutionary mechanism of vibration fatigue damage of 2.5D woven composite materials.

It is significant to efficiently and accurately determine the flutter boundary of various aircraft configura-tions in the aircraft design. In this paper, the linear unsteady aerodynamic method and nonlinear unsteady aerody-namic method are adopted for the subsonic and transonic areas, respectively. In the nonlinear method, the transonic small disturbance equation based on the accuracy steady CFD results is used as inputs. The g method is used in all flutter solutions for different Mach areas. The flutter analysis is used for an beam and reduced stiffness FEM model of the whole aircraft including empty aircraft and three special fuel cases for choosing the typical altitudes and Mach number covering the flight envelope and determine the flutter envelopes for the four aircraft configuration. Results show that the flutter boundary of the aircraft is consistent with flight flutter test. Compared with other analysis meth-ods, the efficiency is obviously improved, especially for a variety of aircraft configurations. Therefore, the method adopted in this paper is an efficient and accurate method for predicting flutter boundary of large aircraft, which is suitable for engineering at present.

The rise of biomimetic unmanned aerial vehicle (UAV) cluster has brought new challenges for radar target tracking and identification. Different cluster flight modes will have different impacts on radar data processing and cluster target identification. For analyzing the influence mechanism of the cluster on radar tracking and identification, this paper models the flight process of UAV cluster based on three kinds of species: geese, wolves and bees, which respectively simulated the large-scale transport, close-in rounding attack and robust information communication of UAV cluster. Secondly, it discusses the influence mechanism of different cluster modes on several algorithms of tracking: track initiation, data association and tracking filter. Finally, combined with the characteristics of three biological movements, it designs the identification methods of cluster event pattern based on clustering in detail, and gives the judgment rules. The simulation results show that there is the suitable combination of radar data processing algorithms for different clustering modes. The optimized tracking algorithm combination based on different clustering modes can effectively improve the tracking accuracy of the radar cluster target, and can reduce the time cost. Moreover, the method proposed in this paper can realize the identification of different cluster patterns to the judgment of target intention and provide the subsequent processing.

Unmanned aerial vehicle (UAV), which is one of the significant means of maritime and aviation reconnaissance, is recognized as the main reconnaissance force to obtain information control and air control in the future sea battlefield. By combing the models and attribute characteristics of foreign small and medium-sized UAVs on the sea, this paper studies the application mode and application advantages of small and medium-sized ISR UAVs in the sea battlefield, and discusses their problems faced by the application, then analyzes the key technologies, such as launch and recovery, autonomous control, mission load, communication link, platform design, finally looks forward to their development trend. This paper provides reference and ideas for the popularization, application and planning development of small and medium-sized ISR UAVs in the field of maritime.

The aircraft AC power generation system is the main source of power for the whole aircraft, so a complete safety analysis is required. Traditionally safety analysis pays less attention to the security problems caused by nonlinear interaction between system components. Especially when the support data of the developed model is insufficient, there is a risk of analysis omission. According to the basic characteristics of the power supply conversion process of AC power generation system, this paper constructs a safety control structure chart and identify unsafe control action(UCA) based on the STPA method, and introduces the failure model and effect analysis(FMEA) of similar system to analyse the UCA cause factor and cause scenario. Using formal tool of timed automata theory, the system modeling and verification are carried out. The correctness of this methods is confirmed by expert evaluation and accident comparison. The result shows that the introduction of STPA based on traditional safety analysis methods can effectively identify unsafety control action and the causes of accident, which can be an effective supplement to the traditional method.

For near space unmanned aerial vehicles(NSUAVs), efficient power type is the key to support their long flights. It is considered that the "airborne liquid hydrogen storage + hydrogen fuel cell" scheme is in line with the trend of NSUAVs' greater endurance and larger payloads. In allusion to this scheme, the technology status of hydrogen supply processes, airborne hydrogen tanks, air supply processes and water/heat management for fuel cells are summarized in this paper. Technical analysis and summaries are carried out on hydrogen delivery methods, structures and materials of airborne hydrogen tanks, as well as the influences of low pressure environment on the suction performance of air compressors and heat dissipation performance of fuel cells. The development direction of relevant technologies is also discussed, providing reference for later studies.

The resistance characteristics of aero-engine high-altitude ice crystal particles will affect the movement of ice crystals. In order to explore the influence of different shapes of ice crystals on the drag coefficient, the paper adopts the method of high-speed camera tracking to investigate the drag coefficient of spherical particles and nonspherical particles(long cylinder, short cylinder and disk). The Reynolds number and drag coefficient of different particles are obtained according to the velocity of particles at uniform velocity, and the correlation formula for calculating drag coefficient of different particles in the working condition range is obtained by fitting experimental data.Finally, the correlation formula is verified by using experimental data other than fitting data. The results show that the Reynolds number ranges from 3 961 to 24 144. The average relative error between the calculated and experimental values of the four particle resistance coefficients is less than 5%.

The environmental qualification test of civil aircraft airborne equipment is to demonstrate that the equipment meets the applicable environmental standards, and further meets the technical standards order(TSO), which is of great significance to the airworthiness certification of airborne equipment. At present, the environmental qualification test of civil aircraft airborne equipment in domestic is still in the continuous improvement stage. This paper takes the environmental qualification test of certain airborne equipment as an example, introduces a set of workflow for the environmental qualification test, including three stages: environmental qualification test plan development, environmental test procedure development, and qualification testing. Then combined with the minimum operational performance standard(MOPS) applicable to the equipment and the DO-160 standard(Environmental Conditions and Test Procedures for Airborne Equipment), it describes in detail about the work content and focus of each stage in the workflow, as well as the planning of airworthiness liaison and suggestions. This equipment has got the TSO approval, indicating that this workflow can be effectively applied to the environmental qualification test of airborne equipment and support for the airworthiness certification, and can also provide reference for the environmental qualification test of subsequent airborne equipment.

It is well known that there are several vertical flight phases for the aircraft in the flight. The cruise flight phase takes most of the flight time, flight distance and fuel consumption, so it is important and necessary to develop the flight management system(FMS) vertical trajectory prediction algorithm for the cruise flight phase, aiming to improve the economy, comfort and safety of the flight. In order to meet the versatility of the vertical trajectory prediction algorithm between different types of aircraft in the cruise phase and improve the accuracy and reliability of the vertical trajectory prediction, the algorithm of vertical trajectory prediction for cruise flight phase is proposed in this paper. Firstly, the cruise speed profile is calculated, and the realistic atmospheric model of prediction is constructed. Then the cruise fuel flow data is calculated based on the aircraft model of first-principles, and the vertical trajectory prediction for the cruise phase is given by designing the vertical trajectory prediction algorithm logic. Finally, the effectiveness and accuracy of the algorithm are verified by ground simulation and air flight test. The results show that the vertical trajectory prediction algorithm of FMS cruise phase based on the aircraft model of firstprinciples can predict the cruise trajectory of the aircraft, and the prediction accuracy error is less than 1%.

As the complexity of modern aircraft systems continues to grow, traditional development methods become increasingly challenging in terms of management and maintenance. Firstly, the development process of aviation flight control system is evaluated in the current system engineering practice, and the shortcomings of traditional development methods and the core principles and advantages of model-based system engineering(MBSE) are expounded, as well as the tools and methods commonly used in implementation. Then, it shows how MBSE supports the process of specification, design, analysis, verification and validation of complex systems by using models in flight control system development. Finally, the future research directions are proposed, including the development of advanced MBSE tools and methods, the prospect of MBSE combined with agile development, and the need to improve interoperability and standardization of MBSE practices. The study in this paper can provide the resources and ideas for aerospace industry professionals and systems engineers interested in using MBSE methodology and tools to improve the design, development, and performance of flight control systems.

The ground vibration test of full-scale aircraft has the characteristics of multiple coordination units, complex system, long implementation time and high risk. Facing the need of efficient development of advance aircraft, it is necessary to improve the capability of the test by introducing the digital means. In this paper, the flow of ground vibration test in traditional mode is summarized, the elements of digital test are analyzed, and the digital test programme is constructed preliminarily. It is pointed that the current digital collaboration model has significant benefits in reducing experimental risks and improving experimental efficiency. In the future, it is necessary to further promote the integration of digital and real simulation and application platform development to promote the mature implementation of digitalization.

Xinjiang is an important area linking China with Central Asia and Europe, and is a vital land pivot point of China's "One Belt, One Road". As the number of flights increases year by year, the control pressure in Xinjiang control area increases year by year, and the problems of uneven load distribution and increasing conflict points in the sector are becoming more and more serious. In this paper, the traffic growth of the Xinjiang control region in 2035is predicted in the light of the development requirements of China's "One Belt, One Road" and "Air Silk Road", and then a capacity assessment of the current sector classification scheme is conducted based on the controllers' workload. Finally, computer simulation technology is used to evaluate the sector designation scheme in 2035. The results show that the new sector division can effectively reduce peak day traffic and peak hour traffic. Through reasonable division of sectors with high controller load, the control pressure has also been significantly alleviated.

In recent years, with the rapid development of civil aviation transportation, the research of aircraft maintenance routing has been paid more and more attention. In order to explore the research status, hot spots and frontier trends of the aircraft maintenance routing problem, this paper takes the domestic and foreign literatures on aircraft maintenance routing collected in the core databases of China National Knowledge Network(CNKI) and Web of Science from 2000 to 2022 as the analysis data. The CiteSpace V software is used as a auxiliary research tool to analyze the scholars, institutions and cooperative relationships in the field of aircraft maintenance routing. Combining the knowledge maps and literature content, the hot spots and frontiers of research in this field are summarized.Considering the domestic aircraft maintenance routing research, research suggestions are put forward for the research trend and focused research content in this field in China, and the reference is provided for future aircraft maintenance routing research scholars.

Aviation industry is one of the eight key industries of carbon emission. The carbon emission of aviation industry is mainly affected by the carbon emission of aero-engine. Therefore, it is urgent to carry out the research on the measurement method of aero-engine carbon emission. The life cycle assessment is used as a quantitative method for the carbon footprint of aero-engines. The life cycle carbon emissions of aero-engines are divided into fuel cycle carbon emissions and material cycle carbon emissions, and statistics are carried out separately. The aero-engine system boundary is divided, the data collection that should be carried out in each stage is proposed, and the data is required. A relatively complete set of aero-engine carbon emission measurement method is obtained. The method obtained in this paper can comprehensively evaluate the carbon emissions of aeroengines from the perspective of life cycle, which can provide guidance for the measurement of carbon emissions of aeroengines throughout the life cycle, and provide a theoretical basis for emission reduction from the perspective of fuel and material.

The bird-swallowing ability of engine must meet the requirements of the national military standard and airworthiness. It is necessary to propose a reliable method to assess the bird-swallowing ability of the engine before bird-swallowing tests, the test risk can be reduced and the test success rate can be increased. Based on the birdswallowing capability simulation and verification project of a turbofan, a method for evaluating the bird-swallowing capability of an engine is proposed in this paper based on simulation analysis, momentum analogy and contact stress analogy. According to the relevant standards and specifications, the test requirements are determined, and the birdswallowing test is carried out for four times. It is verified that the method is accurate. The test results and assessment methods can provide reference for the development of other turbofan models.

Ultra-high strength aluminum alloy has achieved extensive application in the nuclear，aerospace，and aviation industries because of its high specific strength and low density. The fifth generation of ultra-high strength aluminum alloy has been produced，and in comparison to the fourth generation’s 600 MPa level，its ultimate strength has been consistently redefined and increased from 650-700 MPa to 750 MPa or even 800 MPa. This paper reviews the history of the research on aluminum alloys with ultra-high strengths and introduces the current state of development both domestically and internationally. The key issues and recent research development are further explored，including computer simulation，thermal deformation，heat treatment，homogenization，melting，and casting，as well as composition design. Finally，combined with the development needs of future equipment and domestic technology status，it is pointed out that in-depth study of basic theory to solve the problem of comprehensive performance matching，the promotion and application of special materials in specific application scenarios are the development trend and important direction of ultra-high strength aluminum alloy.

With the improvement of thrust-to-weight ratio and other properties of future aero-engine，the high temperature mechanical property and structural stability of titanium alloy components are required. The limitation of traditional experiments in time and space scale has become increasingly prominent，and it is difficult to deeply study the microscopic transient phenomena and mechanisms. Moreover，the molecular dynamics（MD）calculation method takes the atomic/molecular model as the calculation object，on the basis of Newton classical mechanics and empirical parameters，the calculation efficiency is greatly improved compared with the quantum calculation method. Therefore，MD has become an important method to optimize the process parameters and calculate the microstructure properties of aero-engine titanium alloy. Based on an overview of the basic principle of MD computing space and time scale advantages，this paper reviews the relevant domestic and foreign achievements in the study of molding，microstructure characterization and performance testing of aero-engine titanium alloys by MD method in recent years，as well as representative conclusions that contribute to the improvement of high temperature resistance of aero-engine titanium alloys. Finally，the future prospect is discussed based on the demand for MD computing technology for aircraft engine titanium alloys，thus pointing out the challenges faced on the following aspects，including high-throughput composition design based on MD computing method，training molecular force fields for mature titanium alloy systems，and introducing the new ReaxFF（Reactive Force Field）into the study of combustion mechanisms.

Propeller propulsion technology plays an important role in aviation field. Composite materials have the characteristics of high specific strength，high specific modulus，high damping，designability and so on. The use of composite material propeller blades can further improve the performance of propeller in terms of mass reduction efficiency，propulsion efficiency，corrosion resistance，noise reduction. Composite material propeller blades have become the general trend. Based on aircraft propeller blades and rotor blades，this paper aims to perform a brief review of the research achievements of aviation composite propeller blades at home and abroad，classifies and expounds the material systems，structural design and molding processes of aviation propellers. The key technical problems and the simulation research on manufacturing process of propeller at home and abroad are summarized. Finally，the future development direction of domestic composite propellers from the aspects of improving the material system，optimizing the structure design，deepening the process research and strengthening the engineering application of numerical simulation technology are concluded.

Taking the application of artificial intelligence technology in the field of low altitude flight as an breakthrough point, this paper analyzes the challenges of unmanned platform, intelligent control and multi-task of low-altitude aircraft driven by artificial intelligence (AI) technology, which bring about multi-complex control objects, increasing control difficulty and expanding space-time depth. It puts forward the main decision-making methods and development approaches of improving the efficiency of flight examination and approval by pre-practice decision-making, real-time monitoring of flight status by autonomous decision-making, and accurate handling of violations by data-driven decision-making. This paper analyzes the main points, advantages and disadvantages of the application of artificial intelligence technology, soft killing technology and hard damage technology in the construction of management control and emergency treatment.

To effectively monitor the operation state of landing gear, a back propagation neural network-based on multi-strategy cooperative optimization(MSCO-BPNN) is proposed. The multi-strategy optimization algorithm is composed of chaotic mapping strategy, adaptive spiral capture strategy, crossover mutation strategy and whale optimization algorithm(WOA). WOA is applied to find the optimal hyperparameters of back propagation neural network(BPNN). The search efficiency, multi-local search ability and global search performance of model can be improved by using chaotic mapping strategy, adaptive spiral capture strategy and crossover mutation strategy. The BPNN with optimal hyperparameters is introduced to establish the implicit model of input parameters and output responses. Based on quick access recorder(QAR) data, landing gear left side brake temperature is act as the monitoring objective of this paper. The validity and applicability of MSCO-BPNN are verified by compared with WOA-BPNN, particle swarm optimization BPNN and traditional BPNN. The results show that MSCO-BPNN can monitor the operation status of landing gear with high efficiency and accuracy. The efforts of this paper provide a promising insight for the precise condition monitoring of complex structures.

Considering the drag-divergence performance as a constraint, this paper presents a multi-point aero-structural design optimization of wings on a wing-body-tail-engine configuration of long-range dual-aisle civil aircraft by using a gradient-based method based on the discrete adjoint method. Firstly, the accuracy of the coupled aero-structural analysis method used in this paper was validated with DLR-F6 wing-body configuration. Then a wing aero-structural design optimization based on a dual-aisle civil aircraft is offered. The drag coefficient of the optimized configuration in every state decreased, which was reduced by 13.67 counts at the cruise condition, the difference in drag coefficient from Mach 0.85 to Mach 0.87 was decreased from 28.52 counts to 18.98 counts, indicating its drag-divergence performance has been improved undoubtedly. Finally, we compared the performance among the multi-point aero-structural optimized configuration, the single-point aerodynamic optimized configuration and the single-point structural optimized configuration. The results show that the multi-point aero-structural design optimization considering drag-divergence performance has great potential to gain a design configuration with better comprehensive and practical performance compared with a single-point optimization in a single discipline.

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. The complex air environment, transient situation data, and multiple cumbersome combat tasks make coordinated combat with unmanned aerial vehicles a trend in future air combat, replacing single machine combat. However, multi-agent modeling and training processes face difficulties in reward allocation and network convergence. Air combat scenarios for 5v5 manned and unmanned aerial vehicle cooperation, the characteristic model of single agent is abstracted in this paper, and an algorithm based on proximal policy optimization is proposed 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 stable and reasonable decision-making strategy in continuous action space after training and learning.

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, load, boundary simulation, power system, data processing, damage detection, health monitoring, and so on. In this paper, the development plan and suggestions of the whole aircraft fatigue test technology are given. This research can provide important technical support for other aircraft fatigue tests.

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, the background of CAT-A take-off performance is analyzed in this paper, the relative clause requirements and compliance method are researched, the flight test techniques concerning H-V envelope curve, CAT-A take-off flight path, CAT-A continued take-off, aborted take-off, and the determination of final take-off decision point are discussed. The CAT-A performance take-off decision point flight test risk management and control measures for clear runway are made. The CAT-A performance take-off decision point flight test method and flight test risk management and control measures specified in this paper has effectively instructed the CAAC certification flight test toward AC312E, AC313, laying a sound foundation for the above mentioned helicopters to acquire CAAC type certificates.

This paper studies several problems that may exist in the aerodynamic design of low Mach number general aircraft, and discusses the design characteristics of the pressure distribution of some related airfoils while part of the characteristics is verified by a multi-point laminar airfoil design case. Firstly, several issues which exist in the aerodynamic design of low Mach number general aircraft, such as relatively large zero-lift drag coefficient, high stall performance requirements, and large variation range of Reynolds number, are discussed and analyzed. Then, to address these issues, the paper extracts some useful design features that are beneficial to the airfoil aerodynamic performance from the study on the design characteristics of the pressure distribution of several turbulent flow airfoils and laminar flow airfoils that are designed for low Mach number general aircraft. Finally, by considering the typical design conditions of a light multi-purpose single-turboprop-engine general aircraft, including the cruise, climb and stall conditions, a multi-point laminar airfoil optimization is offered by using the GAW-1 airfoil as the baseline. The optimized foil has a 9.6 improvement in the lift-to-drag ratio of the cruise condition, a 16.3 improvement in the lift-to-drag ratio of the climb condition but a 0.115 decrease in the maximum lift coefficient of the stall condition. The results show that the requirements from the cruise, climb and stall conditions are contradictory to some degree in the considering multi-point optimization case, and the designers should deal with this trade-off carefully based on the features of the low Mach number general aircraft.

To address the issue of low brightness, high noise and obscure details of UAV aerial low-light images, this paper proposes an UAV aerial low-light image enhancement algorithm based on dual-path inspired by the dual-path model in human vision system. Firstly, a U-Net network based on residual element is constructed to decompose UAV aerial low-light image into structural path and detail path. Then, an improved generative adversarial network (GAN) is proposed to enhance the structural path, and edge enhancement module is added to enhance the edge information of the image. Secondly, the noise suppression strategy is adopted in detail path to reduce the influence of noise on image. Finally, the output of the two paths is fused to obtain the enhanced image. The experimental results show that the proposed algorithm visually improves the brightness and detail information of the image, and the objective evaluation index is better than the other comparison algorithms. In addition, this paper also verifies the influence of the proposed algorithm on the target detection algorithm under low illumination conditions, and the experimental results show that the proposed algorithm can effectively improve the performance of the target detection algorithm.

Aiming at the problems existing in the current mechanisms of delay guarantee in wireless networks(i.e. poor scalability, coarse granularity for provided service levels, and improving delay performance at the expense of sacrificing some resource utilization), this paper puts forward both the idea of particle access and the corresponding access mechanism. In this paper, a traffic flow is modeled as a group of information particles that carry a certain amount of information and are valid for certain periods of time. Firstly, the definitions of information particles and the group of information particles are given. It is proved that the minimum reachable access bandwidth of an information particle group can be achieved by using the EDF(earliest deadline first) transmission strategy. Moreover, a fine-grained mechanism of delay guarantee based on the idea of particle access is proposed for the dynamic access environment in wireless networks. Extensive simulations are carried out for the application scenario of downlink transmissions, and it is shown that, in the case of heavy traffic loads, comparing with the rapid growth of the average packet delays and the packet loss rates in a legacy access mechanism, the proposed fine-grained access strategy based on the idea of particle access can also achieve the better performance on the average packet delays and the packet loss rates, and hence higher effective throughput is obtained. The research in this paper pave a new way for further improving quality of service (QoS) mechanisms of wireless networks.

Sector partition is an important task of air traffic control, and a reasonable sector partition can improve the utilization rate of airspace and protect the flight safety of aircrafts. Since the sector partition during flat hours is not well suited to the complex air situation, this paper proposes a sector optimization method based on Voronoi diagram and improved K-means. Firstly, a conflict network is constructed based on the air situation, and a comprehensive sector control workload measurement method is proposed by combining aircraft velocity obstacle relationship and complex network theory. Based on the workload value, a cluster center is determined as the generating element of Voronoi diagram by using the improved K-means method, and then the sector is optimized by using the division method of Voronoi diagram. In this paper, the data of Xiamen airspace control sectors are collected as a simulation scenario for calculation and analysis. The simulation results show that the average variance of the optimized sector control workload is reduced by 66.04% during the peak hours and 13.88% during the flat hours compared with the original sector. The method achieves the purpose of balancing the sector workload, verifies the effectiveness of the sector optimization method, and provides a reference basis for the existing sector partition work.