Abstract:In order to investigate the influence mechanism of oxygenrich condition and particle concentration on the ablation behavior of silicone rubber insulation, the ablation test of a certain type of silicone rubber based insulation material is carried out based on the selfdeveloped oxygenkerosene ablation test system. A total of 0％, 5％, 9％, 15％ and 20％ of the oxygenrich conditions are designed, and each group is set with 4％, 6％, 8％ and 10％ particle concentration. The ablation rate of each sample is measured and the ablation rate, oxygenrich condition and particle concentration are plotted. At the same time, the microstructure of the sample is analyzed by scanning electron microscopy (SEM). The results show that the ablation rate of the two kinds of materials increases with the increase of the particle concentration when the oxygenrich condition is constant. When the concentration of particles is constant, the ablation rate of materials increases first and then decreases with the increase of oxygenrich condition and reaches the extreme at around 9％ of the oxygenrich condition; Particle concentration directly affects the mechanical stress of the surface of the material. The oxygenrich condition affects the formation rate of SiO2 in the material. Under conditions of low degree of oxygenrich, the amount of SiO2 could not be encapsulated in the protective fiber, resulting in a slight increase in ablation rate. And under conditions of high degree of oxygenrich, the generated SiO2 adhered to the surface of the filament, strengthens the erosion resistance and slows down the particle destruction. The effect of the particle concentration on the ablation behavior of the material is greater than that of the oxygenrich condition on the ablation behavior of the material, which is about 5 times the degree of the influence of oxygenrich condition under conditions of the experiments.

Abstract:The milling speed affects its surface integrity whenTB6 titanium alloy is being machined. The experimental results show that the surface roughness decreases first and then increases, the work hardening increases, and the residual stress value decreases respectively with the increase of milling speed when the cutting is at a low speed from 20 to 60 m/min; And the surface roughness, the work hardening and the residual stress value decrease respectively when cutting is at a high speed from 100 to 300 m/min. With the depth of residual stress profile being “spoon” pattern, the deposited materials or the pitting corrosions are observed on machined surface samples.

Abstract:A sliding mode controller based on fuzzyPID approaching law for aeroengine with strong nonlinearity is designed, PID approaching law enables 3 parameters to set the approaching process into different parts to control, and enhance the approaching speed and suppress chattering. The fuzzy theory realizes PID approaching law’s three parameters of dynamic adaptive adjustment, further improves chattering reduction effect. H response time of fuzzyPID approaching law controller is 0.92 s less than that of the constant speed approaching law, and is 0.11 s more than that of the fixedPID approaching law, and the steadystate error reduce by 6.89×10-5and 1.68×10-5respectively compared to other two kinds of controller respectively.πT response time of fuzzyPID approaching law controller is 0.56 s less than that of the constant speed approaching law, and is 0.23 s more than that of the fixedPID approaching law, and the steadystate error reduces by 6.38×10-6and 6.11×10-7respectively compared to other two kinds of controller respectively. By contrast, the sliding mode controller based on fuzzyPID approaching law for aeroengine is better in suppressing chattering than other controller, the impact of quickness is not large, and proving the validity of this controller.

Abstract:In order to study the runway length of military aircraft landing, this paper proposes a calculation method of runway length’s safety coefficient based on safety. The paper mainly analyzes some environmental factors affected by landing quality, wind speed, pressure, temperature, surface friction or longitudinal slope. The paper utilizes Monte Carlo method for simulating the safety landing runway length value and security coefficient which is taking as the ratio of landing runway length and landing running distance. The results show that the safety coefficient of runway length decreases with the increase of landing quality and the higher the safety requirement of the aircraft, the greater the safety factor, but the safety factor will have a marginal value. Under conditions of taking a certain type of military aircraft as an example and setting the environmental factors of the airport, the paper simulates the length of the runway to meet the needs of actual requirements. If the aircraft lands in the maximum quality, when the safety is 99.99％, the safety factor will be 1.40 and the safety factor will be 1.98 in the wet condition of the road surface. The maximum marginal value of the safety factor is 1.43 and 2.02 respectively.

Abstract:Aimed at the problems that the security is not high and the interception is easy, this paper proposes a new kind of satellite antiinterception communication system based on weightedtype fractional Fourier transform (WFRFT) and Multiple Input Multiple Output (MIMO) technology. The system is to modulate the signal by adopting multiple layer WFRFT. The number of WFRFT layers and the transmit antennas is the same. The modulation parameter of each WFRFT layer is different. The original signal subject to WFRFT modulation is characterized as time and frequency domain, can effectively resist the parameter scanning, and MIMO can effectively improve the spectrum utilization and system capacity. By theoretical analysis, the WFRFTMIMO communication system can be used to restore the original signal efficiently, and the eavesdropper can’t intercept the signal. Taking twotransmission and onereception antennas as an example, the results of the contrast of bit error rate (BER) performance between legal receiver and eavesdropper and relationship between receiving performance and WFRFT order deviation are simulated respectively. When the modulation order error of the eavesdropper is 0.1, and the signaltonoise ratio is 20 dB, the BER of eavesdropper is 10-3, which is more than the legal receiver 4 dB. The performance between different receiving performance and transmitting antennas groups is simulated, when the signal to noise ratio (SNR) is 10 dB, the performance of the three transmit four receive antennas is higher than that of the two transmit one receive antennas, which increases the 4.5 dB.

Abstract:By using the Particle Swarm Optimization (PSO), this paper, optimizes main parameters of missile in the view of the problems in mass restricting the overall parameter design of inter air to air missile. Firstly, according to the flight characteristics of air to air missile at different stages, a numerical integration method is used to settle the mass of air to air missile based on the existing model of boost stage and cruise phase. Secondly, taking the minimal takeoff mass as the objective function, the paper optimizes load mass, relation coefficient of projectile body, structure coefficient of engine, wing loading, boost stage and cruise phase specific impulse by Particle Swarm Optimization (PSO) algorithm. In the end, through dissertation comparison of the optimized velocity curve and deceleration time curve with the original, the advantages and the reliability of the model are verified. The results show that the mass of missile can be reduced by optimizing, and the flight performance remains unchanged generally. This is for designing missile reference only.

Abstract:In this paper, a lowprofile Superstratum Microstrip antenna with high gain and low RCS is designed. A metallic square loop loaded with resistors is mounted on the upper surface of the superstratum unit, which can absorb incoming radar wave to realize partly reflection. The integration of superstratum with the AMCbased antenna can greatly reduce the profile due to the partly reflection path of the superstratum and the inphase reflection property of the AMC. Meanwhile, the upper surface of the superstratum and AMC can generate a FabryPérot resonance to improve the radiation performance of the antenna. Through the integrated design of superstratum and the original antenna with the synthetic reflection AMC units on its upper surface, the patch on the upper surface of superstratum can generate a FabryPérot resonance cavity with AMC units on the upper surface of antenna, appliing to improve the radiation and scattering performances while reducing the profile. The simulation and measurement show that the |S11|<-10 dB bandwidth of the lowprofile superstratum microstrip antenna is from 13.8~15.36 GHz, while the gain is higher than that of the original antenna at least 3 dBi from14.40~15.42 GHz and its RCS is reduced significantly from 6 to 17 GHz. The 6 dB RCSreduction bandwidth is from 8.86 to 13.56 GHz and the maximum reduction is 14.8 dB.

Abstract:In view of the importance of topology structure design in directional antenna network topology, this paper takes the maximum node degree, the maximum communication distance, connectivity and other factors into consideration comprehensively, and focuses on the construction of a kconnecting communication network topology thus ensuring the survivability and reliability of the network. For the abovementioned reasons, a network topology model of optimal kconnecting is established The paper presents a new way of connection between the nodes as a fixed template to ensure the communication of the network. On the basis of this template, the genetic algorithm is used to optimize the connection mode, an efficient encoding method is presented, and the ordered cross is adopted to be a crossover. By so doing, individual network connectivity checks are avoided after each crossover operation, the time complexity of the crossover operation is reduced, and in the meantime the good pattern in the chromosome is inherited to the next individual generation. As a result, better topological nodes connection is found out. The result shows that the effectiveness is very satisfied.

Abstract:A novel jamming identification method based on bispectrum and Zernike moment feature is proposed to effectively deal with two new kinds of jamming of smeared spectrum (SMSP) and chopping and interleaving (C＆I). In this method, the bispectrum analysis of received radar signal under three cases is given firstly through a series of dimensionality reduction and normalization, and a threedimensional feature information is turned into twodimensional feature information. Then the twodimensional feature spectrum is transformed into a gray image through a series of image processing, and Zernike moment feature is utilized for extracting image shape feature to constitute feature vector for signal recognition. The result shows that the proposed approach can achieve satisfying recognition. Particularly the method is less affected by SNR and the recognition rate can still reach 90％ under low signal to noise ratio. In comparison with paper［4~6］, this algorithm is the best in the recognition results, and this algorithm is also good in recognition rate under low signaltonoise ratio. The method is feasible in the field of radar jamming signal recognition.

Abstract:In this paper, the composite electromagnetic scattering problem of 3D double cubic above a 2D rough surface is analyzed by the hybrid MOMKA method, which combines the moment(MOM) methods and the Kirchhoff approximation (KA). The composite Electromagnetic scattering model of doubletarget above randomly rough surface is constructed, and the target is divided as MOM region while the rough surface is divided as KA region, the current on the rough surface is obtained through the KA approximation, and construct integral equation on the surface of target so as to get the current on target. The scattering field contains the interaction between the target and the sough surface. The efficiency and the convergence of this hybrid algorithm is numerical validated. By comparing the results with the conventional MOM, the validity and high efficiency of this method are verified. Then the scattering coefficients in different rms of rough surface, the different distance, height and size of target are calculated and discuss in detail.

Abstract:The distribution model of clutter and its parameter estimation have been the focus of radar signal processing. Compared with other distribution models, the radar clutter model in a state of subjection to the Pareto distribution is more dominant when it is fitted with the real clutter. As for clutters subject to the Pareto distribution, the range of effective estimation of the distributed parameters are restricted by adopting first two order moment or estimation method. Therefore, a novel estimation method based on the is proposed, and the effective estimation interval of the shape parameter is derived as (r,+∞). On the basis of such as these, an estimation method ofis further proposed by using the idea of negative order moment estimation, making the range of effective estimation of shape parameters extend to (0, +∞). The simulation results show that the estimation method of extends the range of effective estimation of shape parameters to the entire range. Compared with other estimators, the estimation method of runs faster and has better estimation performance in the interval (0, 1). And the application scope is more extensive in actual work.

Abstract:Aimed at the problem that wireless communication in the broadcast of the transmission has a threat against the military information on the safe transmission, this paper proposes a selflocating random coded signature mechanism (SRCSM) on the basis of asymmetric encryption technology. The method combines the LR signature algorithm with the random code through defining the receiving right of the physical area while the mobile receiver and the receiving end are communicating by the software logic to prevent the unrelated person or related person from receiving the encrypted information at the nonspecified location and preventing cases of unconscious leakage of a state secret. The paper briefly introduces the basic content of SRCSM, and combines it with asymmetric encryption technology to build a distributed data system with distributed data encryption system, and analyzes its complexity and execution efficiency, and finally analyzes it with data analysis. The experiments show that using SRCSM encrypted transmission, compared to non encrypted transmission, the longest test time increased by 26.67%, total test period 46.67%, CPU utilization rate increased by 50%, the test goes smoothly; when the packet loss rate is low and number of the monitored are large, the possibility of being monitored can be reduced by 5 orders of magnitude.

Abstract:Aimed at the problems that the layered parallel SVM algorithm is to generate subsample sets by completely adopting the random partition method, and the distribution deviation exists in between the subsample sets and the original sample set, this paper proposes a randomoriented partition method based on distributed k-means clustering. Not that the method is used to take a layer of the training results directly as input of the next layer, but that the k-means clustering algorithm is used to cluster into the number of the next layer node clusters. Then, the paper divides each cluster samples into N parts randomly, and takes out one from each cluster reassembled into N subsample sets to next layer of training to ensure the distribution of the subsample sets similar to original sample set. The results show that this method can not only improve learning ability effectively, but also reduce the jitter of training model.

Abstract:In order to utilize spatial feature information for network sorting of the synchronous frequency hopping signal, this paper proposes a FH signal DOA estimation algorithm based on STFD and unitary ESPRI. Firstly, the paper exchanges the received data for time frequency by the WVD and SPWVD combined timefrequency analysis method. Then the effective hop of the frequency hopping signals is extracted and the spacetime frequency matrix (STFD) is established. Finally, the frequency hopping signal DOA is estimated by using the unitary ESPRIT algorithm. This method transforms the covariance matrix from the complex field to the real domain by the unitary transformation to reduce the computational complexity and uses the conjugate information of the data to double the data length to improve the accuracy of the estimate. The simulation results show that the DOA estimation performance of this algorithm is prior to that of ESPRIT when SNR is higher than 2 dB.

Abstract:Aimed at the problems that the universal phenomenon exists in longrange correlation and the spectrum of power law exists in brain science, this paper establishes a class of stochastic nonlinear model, and explores the stochastic resonance effect of fractional Gaussian noise in nonlinear neurons model. In addition, the paper also proves a sufficient condition for subthreshold stochastic resonance in cerebral neuronal ion channel with fractional Gaussian noise (fGn), and so long as the stochastic dynamics satisfing Lipschitz conditions, can somewhat noise intensity guarantee occurrence of subthreshold stochastic resonance (SR). The theoretical and the numerical results show that the fGn can produce maximum value in information capacity of a general discontinuous 0-1 output for nonlinear neural system, and presents unimodal state, producing SR or SSR phenomenon related to the Hurst parameter. The capacity of transmit information of neuron is verified.

Abstract:By using two q2-ary linear codes to satisfy a certain nested relation, this paper gives a combinatorial method of constructing Hermitian selforthogonal codes, and determines the dimensions and the lower bound of dual distances of the new codes through the parameters of each code. By means of the concepts of q2-cyclotomic coset, the constacyclic BCH codes with length n= q2+1are discussed further. The defining sets, design distances, parameters of the two q2-ary constacyclic BCH codes are characterized as a certain nested relation satisfied. Using these constacyclic BCH codes, many q2-ary Hermitian selforthogonal codes with length 2n and new q- ary quantum codes with d>q+1 are constructed without combination of known methods. The methods and results may be employed to construct quantum codes with better parameter and give out the lower bounds of some optimal quantum codes.