To recognize the contact received by anti-submarine patrol aircraft in search using sonobuoys, the model was set up for contacting situation analysis of the sonobuoy array.Based on this model, two kinds of methods for contacting recognition with the aid of sonobuoys were given.The principles and requirements for deploying the intercepting-mode sonobuoy array were put forward, and the deterministic model for the sonobuoy array deployment was built.Practical conclusions were drawn through simulation calculation, which supplied a theoretical and methodological basis for practical operations.

The missile radar seeker in reentry section was taken as the research object for studying the point target echo model of it in the reentry high-speed flight mode.Based on the principle of Delaunay triangulation, the digital elevation terrain was divided into a number of triangular scatter grids by the interpolation algorithm of Lawson.After that, the altimeter echo model of the single pulse chirp signal radar under complex terrain in the reentry section of missile was established by using the principle of power superposition.And the rough surface average impulse response model proposed by BROWN was used to carry out simulation under the same condition, which verified the applicability of the echo model proposed in this paper.

To solve the problems of nonlinear system control of the hypersonic morphing vehicle in consideration of the compound disturbances caused by the morphing vehicle, the influence of model uncertainties and unknown outside disturbances, and the “differential expansion” of virtual signals, a robust adaptive dynamic surface control strategy based on back-stepping is proposed.Firstly, the aerodynamic parameters of the morphing vehicle are obtained by curve-fitted approximation, and an accurate longitudinal model is built for the purpose of control design in the hypersonic flight.Secondly, according to the characteristics of the state variables of the aircraft, the speed and height are controlled separately, and the control signals are obtained by using the back-stepping method.The RBF neural network is used to approximate the unknown disturbances, and the parameters are updated in real time to realize the robust adaptive performance.Dynamic surface control is added to solve the problems of derivation and differential expansion of virtual control signals.Finally, Lyapunov function is used to prove that the method can guarantee the semi-global stability of the system, and the simulation results show that the controller has good tracking performance and high robustness.

Aiming at the imaging characteristics of the water bodies of synthetic aperture radar images, and to solve the problem of blurred edges, a water body target extraction method based on region growing and Markov Random Field (MRF) was proposed.Firstly, considering that the water surface in SAR image is a uniform and low-intensity region, we used watershed method for segmentation, and defined the blocks with large area as the seeded region of water body.Then, region growing was carried out using the statistical characteristics of the region, and the initial water body targets were obtained.Finally, the precise water bodies were extracted from the initially segmented images by the MRF model that combines the local uniformity characteristics of observed image.The experimental results show that the proposed method can accurately extract the water body targets in SAR images and accurately locate the target edges.

To implement collision-avoidance path planning for 2 fixed-wing UAVs flying at the same altitude with obstacles, as well as to solve the problem that the flight performance constraints are not taken into consideration in the path generated by grid-based A* algorithm, we proposed a Dubins-path based A* algorithm.Effective nodes were firstly found by Dubins path.By applying A* heuristic search, the shortest path constructed by Dubins path was obtained offline for each UAV.For two UAVs flying at the same altitude, the relative motion was analyzed and “Vector Sharing Resolution” was used for online path replanning, thus the collision-avoidance paths were obtained.Simulation results show the proposed method can generate a shorter path more effectively for single UAV and feasible and safe paths for 2 UAVs through online replanning.

A 3D path planning algorithm based on the improved artificial bee colony algorithm and a trajectory tracking control strategy based on linear active disturbance rejection control are proposed for the quadrotor, so as to improve its ability of autonomous flight in the city area. In practical applications, UAV's autonomous flight should take its flight dynamics into consideration. Firstly, the flight dynamical model of the quadrotor is deduced by using Newton-Euler equation. Meanwhile, the obstacle model and the cost function of the flight path are set up.Then, the artificial bee colony algorithm is introduced to deal with the 3D path planning of the quadrotor. The adaptive search strategy, a novel probability selection strategy and the cubic chaotic searching operator are adopted to improve the performance of the original algorithm. Lastly, the dynamical model of the quadrotor is divided into the position loop and the attitude loop according to the time scale principle, and the second-order linear active disturbance rejection controller is designed to realize its trajectory tracking. The simulation result indicates that the proposed method can work out a smooth path for the quadrotor, effectively compensate for external disturbances, and realize the steady control of state variables of each control loop.

To address the issue of cooperative route planning for multiple Unmanned Aerial Vehicles (UAVs) to avoid collision, an improved Artificial Potential Field (APF) method combined with Bezier curve is proposed to increase the self-repulsion field of UAVs.Firstly, the general artificial APF that has virtual impact on the UAV is given.In order to prevent inter-UAV collision, the repulsive potential field generated by the UAV itself is defined.The repulsion function produced by the repulsion field is sectionallycontinuous, and thus the occurrence of frequent large angle flight and sharp turning can be effectively avoided while preventing inter-UAV collision.Secondly, to address the problem of APF local optimum, a method based on virtual obstacle is designed to avoid local optimum.Finally, a sectional Bezier curve smoothing algorithm is proposed to smooth and optimize the UAV flight path online in real time.The smoothness of the curve is guaranteed at the joint of the two sectional Bezier curves, and the path oscillation in the route planning is eliminated.The simulation results have proved the effectiveness of the proposed method.

To solve the existing safety problems in the encryption algorithm of the single chaotic system and the low-dimension chaotic system, a composite digital image encryption algorithm based on 2D hyper chaotic system and 3D chaotic system was proposed.Firstly, Kawakami hyper chaotic sequences were generated by iteration, which were used for pixel shuffling. Secondly, the initial conditions and iteration parameters of LV system were controlled by plaintext pixel values to generate LV chaotic sequences, which were used for substituting and diffusing the images.The generation of initial values and pre-iteration times of the chaotic system was associated with the sum of plaintext pixel values and single pixel value. The whole process enhanced the complexity of the relationship between plaintext and cryptograph, and enlarged the cipher space. The experimental results show that the proposed algorithm has high encrypting efficiency and can achieve a satisfying encryption effect with only two rounds of encryption. Furthermore, it has a desirable ability to resist different kinds of attacks.

Compared with the traditional PID control method, the Auto Disturbance Rejection Control (ADRC) strategy has many advantages and is applied to various areas.In this paper, the ADRC strategy is used to control the fine tracking part of the optical communication APT system. Firstly, the effect of linear auto disturbance rejection parameters on the perturbation of the APT system is analyzed.Then, the ADRC strategy is applied to the experimental simulation, a real-time estimation of the perturbation of the APT system is made, and the perturbation is compensated by the loop in the control quantity. Finally, the ADRC parameters are set to improve the noise suppression effect of the fine tracking part and the tracking accuracy of the APT system. The experimental results show that applying the ADRC strategy to the fine tracking part of the optical communication APT system can reduce the tracking error of the system, improve the system's fastness, enhance the robustness of the system, which meets the requirements of high control accuracy and noise suppression of the spatial optical communication APT system.

In order to solve the problem of UAV penetration under networked threat against maneuvering fire, a cooperative operation method based on “the task vehicle and the bait vehicle” is proposed to realize the penetration through fire coverage area.According to the task requirements on our part, the mathematical model of the relative motion between the bait vehicle and the fire threat is built.On this basis, the impact of the changes in the speed and direction of the bait vehicle when detecting the threat on the moving distance and time of the fire threat is analyzed, and the principles of the synergy between the task vehicle and the bait vehicle are determined.The simulation results show that the proposed method can effectively deal with the networked threat and be applied to the cooperative operation of the manned aircraft and UAV.

A technology of shared aperture with multiple interleaved sub-arrays based on simulated annealing algorithm was proposed.Different beam frequencies were taken as the constraint condition, the grid spacing of the antenna array and the position of the array element were used as the optimal variables, and the peak side lobe level of the two sub-arrays was used as the objective function.Firstly, the grid spacing of the array element was constrained by setting a minimum spacing and a maximum spacing.The grid distance of the array element was calculated after determining the distribution of the array elements.Then, the simulated annealing algorithm was used to optimize the grid spacing and distribution of the array elements, and the value of the objective function was calculated and preserved.Finally, two beams with different frequencies and orientations were generated.The simulation results show that the proposed algorithm can effectively reduce the peak side lobe level of the two sub-arrays, and the two beam patterns with different frequencies are similar in performance.

Heavyweight airdrop of the transport aircraft is an advanced and sophisticated military technology, which has become a research hotspot in the academic field. The research status of the dynamic models and flight control approaches in heavyweight airdrop operations are reviewed in this paper.The advantages, disadvantages as well as the applicability of the integrated modeling method and the separated modeling method are analyzed. The application of such advanced control methods as linear control, dynamic inversion control, sliding mode variable structure control, Backstepping control and model reference adaptive control in the design of heavyweight airdrop controller are studied. The existing problems and challenges in the design of heavyweight airdrop controller are discussed, which is helpful for further research.

In avionics systems, it is a basic requirement for the avionic data bus to provide efficient and reliable real-time communication for airborne electronic equipment, and the transmission line is an important carrier for transferring data over the avionic data bus. The state transition function, spectral characteristics and attenuation characteristics are obtained by analyzing the structure, the distributed parameter and lumped parameter model of the transmission line. The transmission error caused by signal attenuation during transmission is further analyzed considering the electrical characteristics of the transmission line, and the theoretical numerical model of the relationship between the electrical parameter and the bit error rate is obtained. By using the numerical model deduced from the study, the performance of the ARINC429 bus is studied in detail.Meanwhile, the bit error rates of the transmission lines with different diameters are calculated considering the permitted minimum signal-to-noise ratio in transmission. The results show that even slight changes in the diameter of the transmission line may lead to order-of-magnitude changes in the bit error rate of the data bus.The study provides a reference for selecting the transmission line by means of physical data for the aviation data bus.

To solve the problem of poor performance of Space-Time Adaptive Processing (STAP) based on Multiple-Input Multiple-Output (MIMO) radar in complex environment, a method for joint optimization of transmitting the waveform and receiving the weight is proposed to improve the performance of MIMO-STAP detection.After building the MIMO-STAP model, according to the criterion of maximizing the output Signal to Interference plus Noise Ratio (SINR), the joint optimization of transmitting the waveform and receiving the weight is constructed under the constraints of the property of constant modulus of the transmitted waveforms, clutter suppression, and sidelobe reduction to maximize the output SINR, so that the detection performance of MIMO-STAP can be enhanced.To tackle the obtained sophisticated nonlinear issue, an iterative algorithm is proposed.Each step of the proposed algorithm can be transformed into a Semi-Definite Programming (SDP) problem, and hence it can be solved in an efficient way.Numerical simulations have proved that:Compared with the method only considering clutter suppression, the one only concerning sidelobe suppression, and uncorrelated waveforms, the proposed algorithm can significantly improve the detection performance of MIMO-STAP.

To solve the problem of manual selection of regularized parameters in the process of moving target extraction based on iterative tensor High-Order Singular Value Decomposition (HOSVD), Morozov's deviation criterion is used to achieve the adaptive estimation of normalized parameters in moving target detection based on HOSVD. The regularized parameter is selected and adjusted according to the error level, and rapid convergence is realized in the iterative process of the algorithm. Experiments prove that this method greatly reduces the debugging time, and can accurately and completely extract the moving targets.

In order to recognize the operation mode of electronic scanning radar, analysis is made to the working process and mode transition of the electronic scanning radar.The common sequence of two intercepted signal state transition sequences is extracted dynamically by using the score matrix, and the main pattern of the electronic scanning radar is recognized.The experiments demonstrate that:1) The length of the intercepted sequence has little effect on the sequence similarity; and 2) The increasing of types of tracking mode and the decreasing of the rate of the tracking mode are beneficial to the extraction of radar pattern.

Because of the special deployment environment of the WSN system in military field, the node energy is the key factor determining the life of the whole system.Low Energy Adaptive Clustering Hierarchy (LEACH) protocol is a specially designed energy saving hierarchical routing protocol for wireless sensor network, which can prolong the lifetime of the sensor network.By analyzing the selection of cluster head nodes, we proposed to select between the cluster head nodes and ordinary nodes.In view of the node data distribution process, we proposed a multi-hop data distribution mode with comprehensive consideration of the distance between nodes and the quantity of data, and proved mathematically that this distribution mode is more energy-efficient.Finally, Matlab simulation was made to the whole protocol, which proved practically that the improved LEACH protocol is more efficient on energy saving.

In view of the problem that the display result of air combat situation is not intuitional and not convenient for use, a method for situation display and assistant decision-making based on Sudoku and the three-dimensional combat power field is given.This method uses combat power formula to calculate the power distribution on the situation plane, the improved down-sampling to calculate the average of the situation plane, and the TOPSIS and K nearest neighbor algorithm to calculate the relative threat level.Then, the recommended flight direction is given.Simulation result proved the validity of the method.The result of research shows that using Sudoku is helpful for situation display and assistant decision-making.

Doppler shift is one of the basic measurements of GPS receiver, and the correctness and precision of its solution will directly affect the accuracy and integrity of GPS solution.In GPS spoofing, the synchronization of Doppler shift also has a direct impact on the success rate of spoofing and the complexity of identification.Derived from the formula, Doppler shift depends on the relative geometric distribution of the receiving terminal and the transceiver.The compensation cycle of the decoy device also has influence on the recognition complexity of the decoy process.The simulation analysis shows that, the relative geometric distribution of the GPS spoofing device and its compensation cycle for Doppler shift deviation determine the recognition complexity of the GPS decoy signal generated by the device.It also provides a new method to recognize the GPS spoofing signal from the viewpoint of Doppler shift.

The Spatio-Temporal Context (STC) target tracking algorithm is based on the Bayesian framework and uses the spatio-temporal relationship between the tracked target and its surroundings to achieve the purpose of target tracking.However, it is easy to lose the tracked target when the target is rapidly moving or violently interfered.Therefore, in this paper, the STC target tracking algorithm is combined with Kalman filtering, the position of the target is predicted by using Kalman filter, and the prediction result is corrected by using the STC target tracking algorithm.The target tracking algorithm combining Kalman filtering and STC can realize effective target tracking when the target is occluded or when there is interference targets.The experimental results demonstrate that the accuracy and robustness of the proposed target tracking algorithm are better than that of the original STC target tracking algorithm.

When optimizing the design of the step-up-stress accelerated degradation test based on Monte-Carlo, it is usually supposed that the product life follows the Weibull distribution.To solve the problem, an optimization design algorithm for acceleration degradation test under the premise of logarithmic normal distribution of life was studied.An optimized theoretical framework based on Monte-Carlo was given.Then, the statistical analysis model of step-up-stress degradation accelerated test for the photoelectric coupler was deduced.After the improvement to the existing Monte-Carlo simulation method, an improved Monte-Carlo simulation step-up-stress accelerated degradation test optimization design algorithm was proposed.Through the optimization design of a stepped acceleration degradation test for a certain photoelectric coupler, the effectiveness and feasibility of the improved Monte-Carlo simulation method proposed in this paper were verified.

In order to quicken the response speed and improve the disturbance rejection ability of the photoelectric stabilized platform, a Model-based Linear Active Disturbance Rejection Controller (MLADRC) was proposed.The approximate model of the photoelectric stabilized platform was obtained by using the method of system identification.The acquired model information was added to the design of Extended State Observer (ESO), and then MLADRC was designed.A comparison was conducted with LADRC , designed not using the model information.The simulation results show that MLADRC has better control performance and can effectively improve the response speed and disturbance rejection ability of the photoelectric stabilized platform.

In order to obtain high-power mid-IR laser output with high repetition frequency, the LD side pumping technology and the high-repetition-frequency Q-switching technology are used to obtain 1064 nm laser output with high power, high repetition frequency and narrow pulse width.The 2100 nm laser output with high peak power is produced by the 1064 nm pumped KTP.The ZGP crystal is pumped to obtain the 4200 nm mid-IR laser output of 12 mJ.The 2100 nm laser output of 8.3 W and the 3900 nm laser output of 5.6 W are obtained by pumping PPLT and PPLN respectively through 1064 nm.The test results show that using the Q-switching technology with high repetition frequency and LD side pumping technology can achieve the 1064 nm laser output with high repetition frequency and narrow pulse width, and the high-power mid-IR laser output with high repetition frequency can be obtained by pumping the nonlinear crystal.