Abstract:The impact of military activities and other special events on flight can easily trigger a large area of airspace congestion, flight conflict, flight delay and other issues, and induce huge social and economic losses, which in turn seriously affects the efficiency and quality of military training. In view of the urgent need to improve the utilization rate of airspace resources, the important strategy to alleviate the shortage of airspace resourcesdiversion path planning is reviewed systematically from four aspects of influencing factors of diversion path planning, flight restricted zoning, rerouting path planning model and optimization solution method. the development history, research progress and the advantages and disadvantages of the existing methods and strategies are also discussed, and it looks forward to the future development direction of centralized and unified coordination and management, nonindependent multiflight route planning, dynamic planning under uncertain conditions and intelligent route planning, so as to provide systematic support for improving the utilization rate of airspace resources.

Abstract:In view of the accurate use of airfield clearance rules in the evaluation of airfield clearance condition, and the impact of the longitudinal slope configuration of runway on obstacle limitation surfaces according to the regulations, concepts of ideal model and application model for airfield clearance zone are put forward. In order to analyze the influence of the two models on airfield clearance condition evaluation, airfield clearance zone of threedimensional space enclosed by the plane of obstacle limitation surfaces and the corresponding limiting requirement of height is of consideration. An evaluation model of airfield clearance condition is proposed, calculating the limiting range of height and plane of threedimensional lump. Referring to this method, the coordinates of the slope restraining points in runway strip and the points where transitional surface beside two sides of runway strip intersect inner horizontal surface are analyzed and confirmed, and then the calculation models of threedimensional lump of clearance for runway strip, terminal clearance zone and side clearance zone are established. Thus, the procedure of airport clearance condition evaluation is written and applied to an example. The comparison of the results after evaluating airfield clearance condition can be seen: ideal model is a special case of application model, in which one can be selected based on the life cycle of the airport. The application model must be used after entering the stage of airport feasibility study. What’s more, there is a certain regularity to merit attention about the difference of obstacle limitation height caused by different height at both ends of the runway in application model.

Abstract:Relying on its advantages of flexible combination of casing pipes, the structure of Aviation Metallic Casing Pipes (AMCPs) is widely applied to the important equipment in the field of aviation and spaceflight, enhancing the safety and stability of aviation pipeline service. In order to further guarantee the longterm safety and structural integrity, it is indispensable to periodically inspect AMCPs and evaluate defects via effective Nondestructive Evaluation (NDE) techniques. In light of this, this paper intensively explores the testing mechanism and probe optimization of Remote Field Pulsed Eddy Current (RFPEC) evaluation of a typical AMCPs structure which includes stainlesssteel and carbonsteel casing pipes. The distributions of Poynting vectors and magnetic field within the internal and external regions of AMCPs are analyzed by fast finiteelement modeling. Based on this, a method for localization of remote field is proposed. Following this, the Electromagnetic Shielding Structure (EMSS) for probe optimization is intensively investigated. Parallel to the simulations, a series of experiments for evaluation of wallthinning defects in ACMPs are carried out by using the builtup testing system. The recognition method is valid.

Abstract:In order to study the influence of the interference on the mechanical performance of the bolt connection structure, research work is made by adopting the finite element analysis method based on the experimental verification taking the model of bolt interference connection structure of aircraft wing commonly used in the aviation engineering as an object of study. Firstly, the built model is verified by the test based on the reliability of the threedimensional elasticplastic finite element analysis model of bolted connection structure. Secondly, a parameter analysis model of bolt connection structure of aircraft wing under six different interference quantities is established. The influence of different interference quantities on the stress distribution, initial stiffness and bearing capacity of bolt connection structure is systematically analyzed and compared. Finally, the results show that the stress distribution and the stress concentration of the bolt connection structure can be improved obviously by using the appropriate interference fit. In the selected interference range (0~2.5%), with the increase of the interference amount, the peak stress of the hole edge structure is farther away from the hole edge. When the interference amount is 1.5%, the peak stress of the hole edge is the smallest. At the same time, when the interference amount is 1.5%, the initial stiffness and bearing capacity increase by 14.1% and 9.33% respectively.

Abstract:In order to improve the loading performance of UAV, a new type aerodynamic configuration of joined wing with twinfuselage is designed, and a basic and improved layout model is established. The aerodynamic characteristics of the two configurations are studied in detail by FLUENT. The simulation results show that the joinedwing with twinfuselage layout is good in aerodynamic performance, its lifttodrag ratio in cruise can reach more than 16. With the improvements such as blended wingbody, nose modification and connection procession at front and rear wings, its liftdrag performance greatly improves. When the angle of attack (AOA) is at 2°, the lift coefficient and lifttodrag ratio of improved configuration increase by 1.8% and 9.1% respectivly, the drag coefficient is reduced by 6.7%, and the stall performance is higher. Besides, compared with the basic configuration, the pressure distribution in nose and wingbody connection of improved configuration is effectively reduced with AOA of 2°, the significantly separation doesn’t occur at rear wing of improved configuration at the AOA of 12°. The preliminary flight test shows that both configurations possess excellent flight performance, and there is hope of an application in military and civilian transportation, rescue, reconnaissance and other fields.

Abstract:In accordance with the icing problem of helicopter rotor blade, the aerodynamic characteristics of threedimensional rotor blade before and after iceup are studied. Based on the multiple reference frame model, a threedimensional numerical simulation method of rotor blade icing is established. The air flow field calculation, droplet impact characteristics calculation, ice accretion calculation and geometric model reconstruction are introduced among them. Taking CT rotor blade as a model, the influence of icing on the aerodynamic characteristics of CT rotor blade is calculated and analyzed. The results show that the lift of rotor blade decreases, the drag increases, and the hovering performance decreases obviously after iceup. The ice accretion damage to the original aerodynamic shape of the blade section results in the generation of vortices and the deterioration of aerodynamic characteristics.

Abstract:A certain type of transport aircraft encountered gusts in flight and caused serious turbulence of the aircraft is introduced, and the autopilot parameters, engine parameters and aircraft longitudinal parameters during turbulence are analyzed. The results show that the response hysteresis of flight parameters such as altitude, indicated airspeed, angle of attack, pitch angle and normal overload is different when the aircraft encounters gust. At the same time, the relative lift (the ratio of the lift to the lift when the aircraft is flying steadily before bumping) and the vertical wind speed are calculated, and their extreme values are 0.25 m/s and -11.58m/s respectively in appearing when the aircraft is seriously bumped (the maximum normal overload increment is 0.52). The analysis results are only for reference to studying gust response and gust load mitigation of transport aircraft.

Abstract:For aircraft with more fuel quantity in the wing tank, imbalance of fuel delivery between left and right wing tanks affects control and even flight safety of aircraft. Aimed at the problems that ground crew generally have lack of fault diagnosis methods of wing tank transportation imbalance in aircraft maintenance, the fault diagnosis methods based on fuel quantity interval estimation are studied. The regression equation between the left and the right wing tanks fuel quantity is obtained by using the existing flight data, and the estimation interval of the individual value of wing tanks fuel quantity is obtained, which is used as the normal distribution interval of the wing tanks fuel quantity and fault detection method after being modified. By setting reasonable fault judgment conditions, the fuel delivery imbalance fault of left and right wing tanks can be realized effectively. The results show that the method can accurately detect the imbalance fuel delivery fault of aircraft’s wing tanks and reduce the failure rate when flying again. At the same time, the method is easy to realize without adding software and hardware, can be quickly used among ground crew, and has a certain application prospect.

Abstract:Antistatic coating of aircraft fuel tank is soaked in solution of diethylene glycol methyl ether (DiEGME) to examine the physical and antistatic properties changes of the coating in different proportion such as color, pencil hardness, adhesive force, impact strength, flexibility and surface resistance of the coating tested with different methods, and the FTIR, SEM and EDS are also used to check the molecular structure, surface morphology and element composition of the coating. The results show that with the increase of DiEGME concentration, the mechanical and the electrostatic properties of the coating are on the decrease to a different extent at experiment period. When the concentration of the DiEGME in the water reaches to 20%, the electrostatic conductivity property of the coating is failed, and when the concentration is to 60%, the mechanical property is failed too. When the concentration of the DiEGME in the NO.3 Jet Fuel reaches to 0.4%, the electrostatic conductivity property of the coating is failed, and when the concentration is to 0.6%, the mechanical property is failed too. It is the conclusion that the DiEGME has a poor effect on the mechanical and electrostatic conductivity properties under a certain condition and even makes the coating peeled off under special condition.

Abstract:In recent years, the atomic norm minimization (ANM) algorithm has become an important tool in the field of DOA estimation. Aimed at the problem that the DANM is only suitable for single snapshot, an improved decoupled atomic norm minimization algorithm is proposed for both single snapshot and multiple snapshots models. Firstly, through changing the primal optimized model structure in the DANM algorithm, the traditional twodimensional ANM algorithm based on vectorization is further decoupled into two onedimensional ANM solution models to make it suitable for multiple snapshots models. Secondly, in order to avoid the highdimensional calculations brought by the large snapshot, the covariance matrix of the received data and the covariance matrix of the transpose of the received data are used as the calculation data of the two 1D ANM solution model for model solving, so that the size of the dimension of ANM model is limited to the number of sensors. Finally, the DOA of each dimension are obtained by multiple signal classification algorithm, and the 2D DOA estimation is obtained by a simple 2D pairing method. The proposed algorithm maintains the estimation performance advantages of ANM algorithms. Compared with the DANM algorithm, this algorithm improves the estimation accuracy and sparse recovery ability. And compared with the dualitybased 2D ANM algorithm, the CPU time is significantly shortened. The algorithm is valid.

Abstract:Spacetime adaptive processing (STAP) is widely used in airborne early warning radar. For this, the study of its interference is of great significance. A jamming method based on clutter is proposed. Being easy to be detected by using a mainlobe to mainlobe way to intercept radar signals by conventional coherent jamming methods, a jammer is located in the sidelobe of the radar to intercept the clutter signal rather than the direct signal as the source of the coherent jamming signal. The jamming is carried out by scattering to realize the main lobe jamming. The calculation formulas of radar direct wave power and radar clutter power received by the jammer are derived. A clutter signal model and a jamming signal model are established. Through simulation, the power of radar direct wave and radar clutter received by the jammer are compared, and the feasibility of clutter signal interception is verified, and compared with pseudo clutter jamming through simulation. The simulation results show that compared with the pseudo clutter jamming, the proposed method has a lower requirement for the accuracy of the prior information of the target, is feasible, and effective to the false targets formed in both azimuth and Doppler frequency after jamming.

Abstract:Aimed at the problem that estimation accuracy reduces when square root cubature Kalman filter (SRCKF) faces measurement abnormalities and model mismatch in maneuvering target tracking, a robust adaptive algorithm based on feedback decision is proposed. The algorithm is to utilize the Huber function for processing the observation residual sequence to obtain a weight vector to correct the measurement covariance, and enhance the algorithm’s robustness to overcome measurement anomalies, and at the same time, multiple fading factors are introduced into the adjustable prediction error covariance, changing the filter gain, and enhancing the adaptability of the algorithm to solve the problem of model mismatch. Finally, according to the Mahalanobis distance, the abnormal error discrimination factor is constructed to realize the reasonable switching of the two processing methods by the feedback decision. As compared with the existing algorithms, the proposed algorithm can effectively deal with errors caused by measurement anomalies and model inaccuracy, and is good in the robustness and the adaptability.

Abstract:Aimed at the problems that tracking failure remains in visual tracking, being caused by complex scenes such as scale changes and occlusion, a target scale estimation algorithm with adaptive change of scale aspect ratio is proposed. An aspect ratio estimation of the target is realized by adopting 35×35 scale factors in the algorithm. In order to reduce the amount of calculation, the twodimensional scale sampling factor is selected by hierarchical scale estimation. By so doing, not only the optimal scale of the target is determined, but also the algorithm is improved. In order to further improve the robustness of the tracking algorithm, the Euclidean distance of the response vector between two adjacent frames is used as the criterion for judging whether the template is updated. The scale estimation and template update module proposed in this paper are introduced into the current three excellent correlation filtering algorithms DSST, HCF and OSA. The experiment results show that compared with the original algorithm, the tracking success rate and accuracy are improved significantly by using the new algorithm. On the OTB100 dataset, the success rate increases by 1.3% ,1.4% and 1.4% respectively compared with the above three original algorithms. The accuracy increases by 1.2%, 1.3% and 1.0% respectively, especially in complex scenes such as scale changes and target occlusion. The new algorithm is advantageous to the visual tracking.

Abstract:Aimed at the problems that efficiency is low in optimization and there are defects easy to fall into local optimum in Bayesian network structure learning, a new Bayesian network structure learning algorithm based on hybrid improved Bird swarm algorithm is proposed. Firstly, the initial network is constrained by Mutual information. Secondly, the Bird swarm algorithm is improved by adding adaptive inertia weight. With the increase of the number of iterations, the adaptive inertia weight is adjusted to dynamically adjust the search space of algorithm and change the convergence speed. Finally, taking the improved Bird swarm algorithm as a search strategy, optimization is given to the structure of Bayesian network. The experimental results show that the proposed algorithm is not only good in accuracy and fast at convergence speed, but also good in global optimization ability.

Abstract:Aimed at the problem that the conflict resolution effect under high load conditions is still not ideal, and the network performance cannot meet the requirements of cooperative attacks, this paper draws on the idea of using the power difference of NOMA technology to multiplex signals simultaneously, and introduces the power domain on the basis of the SPMA protocol time and frequency domain. For this, the paper proposes a strategy for improving the performance of the SPMA protocol in the joint power domain, expanding the channel resources of the data link network and achieving the goal of reducing further the probability of information collision. The results show that the improved strategy makes not only the data link network carry more business traffic, but also effectively improves network throughput and reduces network delay.

Abstract:With the continuous development of infrared interference means, its more and more important to establish a set of scientific, reasonable and concise infrared anti-interference evaluation index system. Aimed at the problems that redundant phenomenon is in existence in infrared antiinterference evaluation index system and there is lacking in rationality, firstly, the evaluation index system of infrared antijamming is constructed from the inherent performance index, antijamming performance index and missile tactical performance index, and then through the infrared anti-interference experiment simulation platform, set up corresponding disturbance variable is set up, huge amounts of data preprocessing are obtained. Next, the FPGrowth algorithm in data mining is used to mine and analyze the antiinterference experimental simulation data, and the association rules between disturbance variable and indexes are obtained. Finally, the index system is simplified through the strength of these association rules. As a result, the redundant items are removed for the index contracted and the core indexes are in existence.

Abstract:Aimed at the problems that battlefield environments are complex, reconnaissance party is difficult to obtain complete information of target emitter, and the traditional radiation source threat assessment algorithms are not suitable for the case of data loss, an Induction Ordered Weighted Average operator null value estimation algorithm is introduced in combination with Technique for Order Preference by similarity to an Ideal Solution method weighted by CV correctionG1 method to construct the radiator threat assessment model based on IOWATOPSIS under conditions of missing data. Firstly, IOWA operator is utilized for estimating the null value to solve the problem of incomplete data. Then, the improved G1 method based on coefficient of variation method is used to realize the combination weight of each attribute. Finally, the threat degree of radiation sources is sorted by TOPSIS algorithm. The effectiveness of the algorithm is verified by simulation. The method expands the application range of TOPSIS algorithm, and realizes the emitter threat assessment in the case of missing data.