Abstract:Aimed at the problems that matching speed is slow and matching accuracy is low in airborne miniaturized RF power supply in plasma stealth. Through analyzing rf circuit impedance matching process, an optimization objective function is put forward. According to the characteristic curve of circuit output active power and matching capacitance, the peak value of objective function is founded. An improved terminal sliding mode extremum search algorithm is designed by combining switching links with terminal sliding mode control, the optimal values of L shape matching network and the maximum power output for rf source are obtained. Moreover, the stability of this control method is proved. Based on the optimization of the sliding mode extremum, the threshold function is set when switching between mode 2 and mode 3 is made, and the terminal sliding mode surface is added at the sliding mode oscillation stage to reduce the steadystate error of the system, reducing the steadystate oscillation amplitude of the system, increasing the convergence speed and simplifying the computational complexity of the system. Compared with the traditional sliding mode method, the simulation results show that the proposed method is valid.

Abstract:In order to determine the flight boundary of unknown aircraft, a method of analyzing the aerodynamic characteristics through reverse 3d modeling and establishing a basic flight envelope is proposed, providing a technical support for the flight safety and air combat simulation of the aircraft with unknown aerodynamic parameters. Firstly, the 3d reconstruction of aircraft geometry is made by means of light and dark restoration image and engineering map reconstruction. And then the longitudinal aerodynamic characteristics are calculated and analyzed by numerical simulation. Finally, the basic flight envelope of the aircraft is calculated and verified by comparison. The results show that this complete technical approach is in support of studying the flight performance of foreign aircraft under conditions of lack of aerodynamic parameters, and the calculated flight envelope has a good reliability and can reflect the flight performance of aircraft.

Abstract:In view of the shortcomings of airspace representation being characterized by using latitude and longitude coordinates, a method of airspace raster is proposed based on GeoSOT grid. Firstly, the airspace raster representation being concise, good in efficiency, and easy in coordination and report, some typical grid systems of the U.S. Army are analyzed. Secondly, combined with the general flight rules and flight interval regulations, a division scheme and a coding structure of grid reference system for airspace representation are designed. Finally, according to the principle of minimum grid and precision correspondence, the detailed raster representation flow of point, line and area airspace is given, and the application analysis of airspace representation scenario is carried out on grid platform. This provides a new technical means and practical ideas for the airspace representation.

Abstract:The face/core debonding is the most common damage to composite honeycomb sandwich structure, and analysis of vibration is of scientific value and engineering significance worthy. Based on the mesostructure of honeycomb core, the finite element model of composite honeycomb sandwich structure is established by using ANSYS to study the influence of size and location of debonding on vibration characteristics. The results show that the debonding makes the natural frequency of honeycomb sandwich structure lower. The larger the damage size, the lower the natural frequency. The fourthorder natural frequency is the lowest when the damage is located in the middle, and the other natural frequencies become lower while the damage approaches the fixed end. The damage size and location change with difference of influence on the vibration modes of different orders. The research methods and conclusions provide a necessary reference for damage detection, damage tolerance design and analysis of composite honeycomb sandwich structure.

Abstract:Lithium ion battery is widely used in weapon systems. The evaluation for its health status to lithium ion is of great significance to ensure the operational effectiveness of weapon systems. Aimed at the problems that building a physical model is comparatively difficult in the degradation process of lithium ion battery, simultaneously the process is very hard to be described accurately due to the uncertainty and incomplete data by the pure datadriven method. Being the extended belief rule base model combined with the characteristics of the knowledge structure and evidence reasoning, the uncertainty and incompleteness of data may be quantitatively described, but the parameters of the original model had a greater influence on the choice of its performance. In view of the mentioned above problems, an extended belief rule base (EBRB) model of center decenter particle swarm optimization is proposed, and the model is applied in the lithium ion battery health status evaluation. The EBRB based on the optimization of the CDPSO converts the rule set into rules in a datadriven way, the initial parameters with CDPSO are trained, and finally, the validity of the model with the test data set is tested. By comparing with the traditional method, the validity of the proposed method is verified.

Abstract:Aimed at the problems that the dynamic network topology and the limited link capacity lead to frequent network link congestion phenomenon in the process of updating, and the network update process is easy to cause network congestion, reducing the network update success rate, this paper proposes a softwaredefined network update strategy based on congestion avoidance. Firstly, the initial update operation sequence of each data stream is calculated by the mixed update strategy, and then a congestion link sensing algorithm is proposed to realize the potential congestion link sensing in the update process. Finally, a new algorithm based on congestion avoidance is proposed to calculate the congestion free update operation constraint according to the initial operation sequence of each data stream and the perceived potential congestion link state, and to realize the maximum congestion free update of the network. The simulation results show that compared with the existing network updating strategy, the proposed updating strategy can effectively avoid the network congestion of the softwaredefined airborne network during the network updating process and improve the success rate of network updating.

Abstract:Aimed at the problems that a lot of problems remains to be solved by cubature Kalman filter in nonlinear target tracking when the noise covariance is uncertain, an optimized adaptive cubature Kalman filter is proposed. First, the noise covariance is obtained by the linear matrix equation derived from the innovation sequence and the residual sequence, a new process noise covariance [WTHX]Q[WT] estimation method is derived based on the correlation between the innovation sequence and the residual sequence, and then the estimation of the measured noise covariance is made by adopting the residual sequence, and the weighting factors are utilized for combining the current noise covariance matrix and the estimated value into a new measurement noise covariance matrix [WTHX]R[WT], thus avoiding effectively the limitations of inaccurate state estimation. The simulation results show that under conditions of timevarying noise covariance, the tracking accuracy is improving obviously by the proposed adaptive algorithm cubature Kalman filter.

Abstract:In order to realize the secure communication of physical layer in any desired direction in free space, a directional modulation method is proposed based on multiobjective function genetic simulated annealing algorithm. In this paper, two genetic objective functions are established based on the BER performance of communication signals and the degree of constellation distortion in combination with simulated annealing algorithm to avoid genetic algorithm from falling into local optimum. The transmitted signal is the same as the expected constellation in the legal user direction, while the constellation map in the eavesdropping user direction produces a great degree of distortion. The simulation results show that the directional modulation method proposed is narrower in BER beam width compared with the existing directional modulation methods, genetic algorithm, particle swarm algorithm and multiobjective genetic algorithm. The proposed multitarget directional modulation physical layer secure communication signal has stronger antieavesdropping performance.

Abstract:In order to quickly find an optimal frequency point in the HF frequency band, a HF bidirectional detection frequency selection algorithm based on the variable Neighborhood particle swarm search (VNSPSO) is proposed in combination with the broadband spectrum sensing technology. The existing detection frequency selection algorithms are difficult to meet the needs of realtime frequency selection because they are mainly based on the average signaltonoise ratio of the frequency points to evaluate and select the best, and the smallscale random fading characteristics of the shortwave channel is left out of consideration. According to the correlation characteristics of largescale fading, the initial detection frequency set is obtained by the maximum separation method to divide the correlation neighborhood. According to the characteristics of mass selective fading of neighborhood internal frequency points, particle swarm optimization algorithm is used to search neighborhood internal frequency points and to obtain the local optimal solution. The global optimal solution is obtained by transforming the neighborhood. The simulation experiment shows that when “The fastest speed” is used to build the chain, compared with VNSRS, AASS and RSS, MTOBC of the VNSPSO algorithm reduces by 17.1%, 18% and 85.5% respectively. When the CPOS=0.9, the chain building time decreases by 2.5%, 42.6% and 81.7% respectively, the time for establishing a passable link is shortened. When “optimal frequency point” is used to build the chain, the MTOBC of VNSPSO algorithm reduces by 11%, 12.5%, and 45% respectively, compared with VNSRS, AASS, and RSS algorithms. When the CPOS=0.9, the chain building time reduces by 22.2%, 22.4%, and 444% respectively, and the optimal frequency point can be found in a short time.

Abstract:As for multi-sensor systems with correlated noises, eventtriggered sequential and distributed fusion state estimation algorithms are studied, whereas measurement noises of different sensors are correlated with each other at the same time step and also correlated with the process noise at the previous time step. In order to save communication energy, an eventtriggered transmission mechanism is adopted based on observations at current instant and the latest triggered instant of each sensor. Sequential fusion and distributed fusion estimation algorithms are proposed in the sense of linear minimum variance under condition of eventtriggered situation. The data processing can be made by the proposed sequential fusion algorithm in real time in accordance with the order of measurements of sensors arriving at the fusion center, and the algorithms have a little burden to computation. The proposed distributed fusion algorithm can process in parallel measurements of sensors, and has a good reliability. The two kinds of algorithms are as good in estimation accuracy as the eventtriggered centralized fusion estimator. The simulation result shows that the proposed algorithms are valid.

Abstract:Taking public Internet security requirements as a background, the study of network cooperative defense is based on community structure. First, according to the logical structure and node function of the network, the target network is divided into several network communities, and a basic communication model of cooperative defense architecture is designed according to the distributed cooperative control mode. On this basis, a cooperative network defense architecture based on community structure is proposed by integrating information honeypot and honeynet, cooperative defense strategy library, and firewall based on the node trust value management. A cooperative mechanism is designed by using the experience of concept of network ecosystem operation for reference. Through the collective activities as situation awareness, the situation analysis, the action decision and the regulation feedback, the network defense abilities, such as virus detection, rapid response and emergency recovery, can be improved respectively. Finally, taking the latent virus defense as an example, the cooperative network defense flow is given as well as numerical performance simulations. Compared with the noncooperative defense network, the network cooperative defense based on community structure can inhibit the spread of latent virus and enhance network security with less communication loss.

Abstract:In the process of trajectory tracking measurement, the abnormal values of measurement data are in existence inevitably due to the complexity of the environment and the limitation of the measurement mechanism itself. Being ignorance from the influence of data quality on filtering accuracy, the traditional weighted observation fusion estimation algorithms are often directly used to deal with the measurement data from various sensors. For this reason, the robust estimation theory is introduced into the weighted observation fusion algorithm, and the measurement fusion residual vector, the robust weight factor and the equivalent covariance matrix of the fusion observation vector are calculated based on the observation fusion value and the fusion prediction value. The algorithm proposed realizes the realtime separation and correction of abnormal values, and solves the accuracy decreasing problem of the ballistic data fusion estimation due to the pollution of the measurement data. At the same time, the square root filtering idea is introduced, avoiding the filtering divergence problem caused by the nonpositive value of the error covariance matrix in the conventional UKF. The simulation results show that the fusion algorithm is high in estimation accuracy and has a little burden to computation, and can effectively reduce the influence of measurement errors on the accuracy of ballistic orbit determination.

Abstract:Aimed at the problem that conventional moving target detection methods for airborne radar always need many training range samples, there is an adaptation, i.e. transforming the target detection problem into a multiclassification problem. Firstly, the training dataset is constructed based on a small amount of training range samples, and then, a multiclass classifier is constructed based on DenseNet. Finally, the trained classifier is utilized for extracting the characteristics of the received spacetime data for target detection and parameter estimation. The simulation results show that the DenseNetbased airborne radar moving target detection method proposed can detect the target effectively, and estimate its distance, Doppler frequency, and other parameters. Compared with the conventional space time adaptive processing method, the proposed method can significantly reduce the number of needed training range samples. Compared with the existing target detection method based on classification, the proposed method can improve the accuracy of target detection and parameter estimation effectively.

Abstract:With the development of electronic warfare technology and the complex electromagnetic environments of battlefield, the confrontation between the guidance radar and the jammer has become increasingly fierce. Aimed at the problem that performance degrades in the process of confrontation when the guidance radar and the jammer are out of condition to obtain the complete information of the other party during the game, a guidance radar and jamming Bayesian game model is established based on the SINR criterion, and the unknown information is expressed in the form of target probability set through the Harsanyi conversion method. Optimized waveforms of radar and jammer are designed based on game model solution, signal frequency domain energy is distributed based on secondary waterfilling and iterative waterfilling methods, and the existence of Bayesian game Nash equilibrium is studied. Finally, different strategies of radar and jammer are analyzed through simulation. The specific form of the signal verifies the waveform detection performance. The simulation results prove that the detection probability of the iterative waterfilling signal and the second waterfilling signal is up to 15.41% and 12.79% ( higher than that of the chirp signal) respectively, providing a solution for the optimization of the guidance radar signal in the incomplete information game.

Abstract:In order to provide a decisionmaking basis for pavement maintenance managers, a judgment standard system for preventive maintenance of cement concrete pavement is established. Based on the research results of pavement antisliding performance evaluation index and pavement condition index preventive maintenance standard, and according to the basic assumption of the interaction between evenness and dynamic load in the process of cement concrete pavement decay, the judgment standards of friction coefficient, international pavement evenness index, pavement damage index and single index of dominant disease are studied by using the derivative inflection point method and confusion matrix model. This paper analyzes the function and judging principle of each index in the perspective of judging dimension, comprehensive dimension and controlling dimension, forming the judging standard system of preventive maintenance of cement concrete pavement in military airport. The results show that the criteria for preventive maintenance of cement concrete pavement are as follows: Friction coefficient (runway friction test vehicle 95 km/h)≥0.41; Friction coefficient (runway friction test vehicle/65 km•h-1)≥0.50; Friction coefficient (pendulum friction instrument)≥0.51; International flatness index≤3.2 m/km; Pavement damage index (3%, 10%); Corner peeling rate≤35%; Surface peeling rate≤30%; Surface crack rate≤8%; And interplate slip rate≤0.5%. The cement concrete pavement of a military airport can be provided with this scientific basis in determining the best time of preventive maintenance.

Abstract:Microwave deicing is a new way of deicing, because it is characterized by fast heating speed, no pollution to the environments, and low efficiency. Adding carbon fiber to concrete can improve the conductivity and wear resistance of concrete and provide a new composite material for deicing the pavement. The microwave heat absorption efficiency, deicing effect and temperature spatial distribution of carbon fiber concrete are studied. The results show that the temperature at the center of the concrete specimen is the highest, and the farther the distance is from the center, the lower the temperature. With the increase of carbon fiber content, the heating efficiency of concrete specimens increases gradually. When the carbon fiber content is 2‰, the heat absorption efficiency of concrete specimens is the highest. And at the same time, the temperature at the center of the surface of concrete specimens increases gradually.