Abstract:Situation awareness and identification on the battlefield are the basis of combat decisionmaking, and the development of a combat identification system that adapts to future innovative combat concepts is essential to improving the combat capability of systematic fighting. Based on the original concept of combat identification, this paper proposes a new concept of combat identification suitable for future combat and equipment development. From five perspectives, the characteristics of the future combat identification system are described: information dominance, distributed situation awareness, comprehensive method, standardization and interoperability, and swarm intelligence convergence. The function of the combat identification system supporting future combat is summarized. Based on this, the requirement for combat identification in the air combat field is put forward. The analysis above provides a reference for the development of combat identification systems in the future.

Abstract:Aimed at the problems that being multi-electric/all-electric aircraft and in view of development trend, modern aircraft is heavy in weight in taking off and high at landing speed, a key research direction of anti-skid control of aircraft brake system, all-electric brake, brake material and other advanced technologies is put forward. First, the composition of the aircraft brake system and its basic working principle is introduced, and then its development process and research status from three aspects of brake control system, anti-skid control theory and brake material technology are summarized. Finally, according to the characteristics of modern aircraft braking, the existing problems of the above-mentioned three important technologies are analyzed, and the development direction of aircraft braking system in the future is prospected.

Abstract:X型转子发动机由于具有高功重比和高循环热效率的优势，在小型无人机动力领域具有广阔应用前景。为确定X型转子发动机的最优点火时机，构建了X型转子发动机的CFD仿真模型，探究了在不同点火时机下缸内流动特性、燃烧性能以及污染物排放特性，揭示了点火时机对缸内流场、燃料消耗速度、缸压、缸温以及CO、NOx排放的影响规律。结果表明当点火时机由20° CA BTDC提前至35° CA BTDC时，缸内湍流度增加，燃烧速度加快，峰值压力和峰值温度逐步增高，导致了发动机指示热效率上升，且NOx排放明显上升，CO最终排放量相差较小。然而，点火时机的过度提前会使得着火过早，导致发动机热效率下降。因此，存在最佳点火时机35° CA BTDC，使得瞬时放热率峰值达到最高为1.44 J/(°)，且热效率达到最高为24.49%。

Abstract:Optimal sequencing is important for aircraft departure to reduce runway congestion and improve the efficiency in combat system. In view of such a problem at military aviation double runways, firstly, an optimal sequencing model is established based on the minimum time of aircraft forming “task package” in the predetermined airspace, and then an improved marine predator algorithm based on elite reverse learning strategy and slime fungus foraging behavior（ESMPA）is used to solve it. Finally, through the simulation experiment in comparison with the optimization results of other algorithms, the improved marine predator algorithm makes the “task package”formation time significantly shorter and effectively improves the combat aircraft sortie efficiency.

Abstract:Aimed at the problems that interpretable ability of composite health indicators constructed by deep learning is poor, and the prediction results are difficult to quantify the uncertainty of engine remaining life, an aero-engine remaining life prediction method based on data fusion and gate recurrent unit (GRU) is proposed. Firstly, the one-dimensional composite health index is constructed by weighted fusion of multi-source sensor data. And then, the Bootstrap method is utilized for putting the samples back on the one-dimensional composite health index，obtaining the engine degradation characteristic samples of n groups. Finally, “n+1”remaining life prediction models based on GRU are constructed by using one-dimensional composite health indicators and the n-groups of engine degradation characteristic samples, the prediction interval of engine remaining life is quantified. In order to prove the feasibility and superiority of the proposed method, the turbofan engine degradation dataset (C-MAPSS) is used for the experiment, and the root mean square error obtained is 15.825 4, the score function value is 344.210 5. The results show that this method can not only achieve the better prediction results, but also can effectively solve the defects of deep learning in engine remaining life prediction.

Abstract:In the past, the model of undersea piston engine system can only be obtained by experiment. And based on the power process of piston machine studied by numerical simulation method and in consideration of the influence of overexpansion on the output performance of piston engine, a fitting formula of indicated work is established. Through the output torque of the piston machine derived by the indicated work fitting formula to subtract the torque consumed by the auxiliary machine in combination with the complete gas equation of state, a dynamic system model of the undersea piston engine is obtained. In comparison the designed simulation program by the model with the semi-physical simulation experiment, the maximum error between the simulation results of the mathematical model and the semi-physical simulation experiment results is 5.28%. The results show that the model of the undersea piston power system based on the combination of numerical study and theoretical derivation can be used for the preliminary verification of the undersea power system characteristics instead of the experiment.

Abstract:Meter wave radar is characterized by the natural anti-stealth and anti-radiation missiles, but is wide in pitch dimension beam, there is a possibility of the beam hitting the ground in detecting low altitude targets, and the existence of multipath effect seriously affects the height measurement accuracy of meter wave radar. The classical mirror multipath propagation signal model of uniform linear array meter wave radar is utilized for summarizing three height measurement methods based on generalized multiple signal classification (MUSIC) algorithm, i.e. the height measurement method based on improved generalized MUSIC algorithm, the joint estimation method of low elevation and multipath attenuation coefficients based on generalized MUSIC algorithm, and the Height measurement method of generalized MUSIC algorithm based on reasonable weight. Based on the analysis of the above algorithms, an accurate altitude measurement method is proposed based on synthetic steering vector generalized MUSIC algorithm for horizontally polarized meter wave radar.the simulation experiment is compared with the third height measurement method with the best performance, and a general conclusion is drawn based on the analysis of the influence of target elevation, signal to noise ratio, snapshot number, amplitude phase error, ground reflection coefficient and other factors on the height measurement performance of low altitude targets, which proves the superiority of the new method.

Abstract:Aimed at the problems that visual tracking is loss caused by insufficient appearance feature representation under complex backgrounds in combination with the motion features estimated by deep optical flow network, a visual tracking algorithm is proposed based on adaptive fusion of temporal information and spatial information. On the basis of correlation filtering tracking framework, the Recurrent All Pairs Field Transforms (RAFT) deep network is utilized for estimating the optical flow to obtain the timing information of the target, and extract the CN feature and HOG feature to obtain spatial information, and fuse the target timing information and spatial information to enhance the characterization ability of the target's temporal and spatial characteristics, and then a mechanism for discriminating the reliability of tracking results is established, and the weight of time sequence information in the fusion process is adjusted in real time, effectively improving the generalization ability of the algorithm in a complex dynamic environment. In order to evaluate the effectiveness of the algorithm in this paper, the tests are carried out on two data sets, OTB100 and VOT2019 respectively. The experimental results show that compared with the mainstream visual tracking algorithms in recent years, the tracking performance is improved by the algorithm, especially in motion blur, fast motion and other attributes of the video. And this algorithm has obvious advantages.

Abstract:In majority target tracking methods, the measurement noise is generally assumed to be known Gaussian distributed or asymmetric Heavy-tail distributed. However, this assumption is very limited and often does not satisfy the needs of the work in practical application. A variable inference robust cubature Kalman filter is proposed for the nonlinear target tracking with unknown time-varying asymmetric Heavy-tailed noise. The asymmetric Heavy-tailed noise is modeled by Skew-T distribution. In the process of the numerical calculation of cubature Kalman filter, the system state and measurement noise parameter are jointly estimated recursively by the variable inference. The system model and unknown asymmetric heavy tailed measurement noise parameters are obtained by variable iteration of an approximate posterior probability density function. The simulation results show that the proposed algorithm is higher than the variable Bayesian extended Kalman filter algorithm in filtering accuracy.

Abstract:Aimed at the problems that the output voltage overshot is high, the power factor is low, the convergence is difficult while the system parameters change, and interference with ac input current of Vienna rectifier by using traditional PI control is heavy, a global fast terminal sliding mode control strategy based on neural network is proposed. In view of the perturbation of the system parameters and the external disturbances in the actual environment, an uncertainty model of the system is reconstructed, the uncertainties are combined with the total disturbance, and the adaptive neural network is utilized for estimating it, and the Lyapunov theorem is used to prove that the nonlinear control system can achieve bounded stability under the perturbation of the system parameters and the external disturbances.The simulation results show that the proposed method can improve the power factor of Vienna rectifier, overcome the problem of output voltage overshot and effectively reduce the harmonic pollution of the system. Finally, a physical prototype is built, and the experimental results show that the above conclusions are correct.The method presented in this paper has no overshoot, and the steadystate response time, switching load voltage fluctuation, dynamic response time and harmonic content are reduced by 69%, 87%, 84% and 68% respectively.

Abstract:The algorithm of Gravity matching is one of the key technologies in realizing the gravity aided the inertial navigation. However, the defects of the traditional gravity matching method being high in complexity and narrow in application scope, it is difficult to achieve accurate and fast matching effect. Under the certain condition of abnormal accuracy, the use of the improved ant colony optimization algorithm in the process of gravity matching can reduce the mismatch rate in putting the velocity information provided by Doppler speedometer as constraints. The results of simulation show that the algorithm is high in matching rate, and can achieve precise and fast matching location, realizing the gravity aided navigation.

Abstract:Future combats being extremely complex, and challenge to decision\|makers taken by significant cognitive overload due to the massive input of visual information, an evaluation method with key visual information characteristics, i.e. hue, saturation, value and image gradient as independent variables is proposed by the relevant theories of human visual perception and visual saliency mechanism. A quantitative model of visual search efficiency is constructed via a target search task over a complicated image map, and the visual search response time is used as a dependent variable. Three landforms (city, ocean, and plateau) consisting of 441 image maps with different contrast and brightness are tested in the psychology experiment, and the model result show that the R2 is equal to 0.232, p< 001. And the results have practical guiding evaluation and optimization to complex interfaces under different scenarios.

Abstract:Wireless transmission being open in channel and broadcast in signals, there is a possibility to make legal users eavesdropped by illegal users in serving. In view of this question, the source code blocks are encoded with random linear network coding technology as inner codes in combination with network coding and polar-code technologies. Depending on Bhattacharyya-parameters, the channels are classified and the secure bit-channels are selected to structure secure a polar-code as outer codes to transmit internal codes, and a scheme of channel coding is adopted， carrying out concatenation of outer codes and inner codes. The simulation results show that when the SNR of the main channel is 10 dB, both of the proposed method and the traditional secure polar-code method can provide reliable communication service for the legitimate receiver. With this method adopting 8 bit finite field,only by degrading into 2.5 dB for the SNR of the eavesdropping channels can the block error rate of the eavesdropping channel approximate to 1,whereas the traditional polarization code method requires that the SNR of the eavesdropping channel degrades by 4 dB. Compared with the traditional method, the proposed method can further resist eavesdropping transmission.

Abstract:Dynamic Mechanical Properties of Fly Ash-Slag Based Geopolymer Concrete at Different Ages