Abstract:Aiming at the problem that fracture of blade exists in the aeroengine compressor, this paper proposes a testing methodology by using composite bending-torsional resonance of the square plate testing specimen, and researches on nonlinearity vibration characteristic and vibration fatigue testing method of the specimen. The results show that simulated testing specimens have quite complicated nonlinearity characteristics of softening and hardening to seriously impact on vibration fatigue testing of the specimen. And the phenomenon of amplitude jumping is obvious because of nonlinearity, driving frequency must be slightly less than peak frequency to maintain vibration stability. In order to accurately determine testing specimen crack appearing node, crack criterion is developed. Fatigue strength can be accurately determined by the developed crack criterion, and the test and the verification show that the crack criterion is valid and feasible.

Abstract:Small silica particles may be inhaled into the engine when helicopters and other aircraft are in the process of takeoff or landing on the gravel ground. The particles collide with engine blades at a relative speed more than 200 m/s, thus eroding the blades seriously. The particle velocity is hard to reach 200 m/s with straight-wall nozzle when total pressure is 0-6 MPa. So supersonic convergentdivergent nozzle is designed to increase the particle velocity. Particles motion in and out of the nozzle and throat optimization are studied by twophase simulations. The research shows that particles are speeded up mainly in the divergent part of the nozzle, and the acceleration of particles not only depends on the relative speed of gas and particles, but also the gas density. The throat radius is optimized, and the particles can be accelerated to 218 m/s by the nozzle with 0-001 6 m throat radius.

Abstract:In order to analyze the influence of pylon’s length, width, height to flow characteristics in the supersonic combustion, orthogonal experimental design method has been carried out to design different combinations of pylon size. By numerical simulation, the differences between different examples’ mixing efficiency, total pressure loss ratio, penetration depth has been contrastive analyzed. By intuitive method and ANOVA, it shows that height is the greatest influence on mixing efficiency, then the width, length is the worst. The size of pylon dose not have significant association with total pressure loss and penetration depth. The mixing efficiency of The optimized case(0-712439) is higher than any cases of this paper, and its total pressure loss(0-1303) lose 2％ for improving 37％ mixing, and penetration depth(10-023) lose 1％ for improving 9％ mixing. This paper provides a method reference for the designing and improvement of pylon.

Abstract:Small-sized UAVs are increasing more and more rapidly in urban circumstance in recent years. However, the traditional path planning methods always threaten simplification, and fail to solve the problem of path-planning in the circumstance efficiently Therefore, cell is introduced to define the flying space, digital cellular map and path cost function are defined. At the same time by using ant colony algorithm this paper plans the path for UAVs, thus avoiding any kinds of irregular obstacles. The simulation results show that the proposed method can avoid obstacles logically under condition of the obstacle model without simplification. By doing so, this plans a safe flyable path in urban building areas for UAVs.

Abstract:Multi UCAV Cooperative Path Planning is an important part of multi UCAV cooperative combat, and the results of collaborative operations have many guiding roles. Multi UCAV cooperative path planning belongs to multi peak function optimization problem, and the solution stability is relatively poor. In order to solve this problem, first, on the basis of analysis under condition of multi Aircraft Cooperative limitations, and combined with the core index of single track planning, the paper builds up multi UCAV cooperative route optimization function. Then, the paper utilizes the characteristics of stability of multi swarm algorithm with the gray wolf Lee(MP-GWO) in solving multi peak optimization problems on the function to solve it. Finally, the paper compares the MP-GWO with the GWO algorithm, EA algorithm and solution in the new threat environment superior to verify the feasibility of the algorithm. The simulation results show that the MP-GWO algorithm has the stability of the multi peak problem in solving environment, and adapts to unexpected threat circumstances.

Abstract:Aimed at the problems that the traditional evaluation methods are low in evaluation precision, complex in structure of the model, and is not available in the real-time dynamic threat assessment, an air combat threat assessment method based on least squares support vector machine (LSSVM) is proposed. Firstly, the threat index of air combat characteristic data is analyzed, and the expert evaluation is used to build the threat assessment sample base. Then, cross hybridization chaos quantum particle swarm optimization(CHCQPSO) algorithm is used to optimize the regularization parameter and kernel function parameter in LSSVM, and the results are compared with those of the classical PSO, BP neural networks and mesh models. Finally, the optimized LSSVM model is used to realize the real-time dynamic threat assessment of air combat targets. The simulation results show that the proposed method is high in accuracy and short in time required, thus providing a new idea for evaluating the threat of air combat targets.

Abstract:Aimed at both sides’ maneuver decision problems in air combat that changes of angle, distance, velocity and altitude dominant function are considered to make maximum air combat superiority expectation as target, the Monte Carlo tree search method is introduced. The search strategy is used by the mini-max search algorithm. Against the confrontation between the two aircraft, the simulation results of air combat situation and advantage change curves show that our fighter is in the dominant position for the most part in the whole process in air combat by using MCTS method. At the same time, the realtime performance of the algorithm is simulated. The results show that the model time of the algorithm computing maneuver action is located at 50～100 ms range to meet the needs of real-time.

Abstract:This paper proposes a strategy of three-point collinear active defense in three-dimensional space. Firstly, taking the kinetic characteristics of fighter, defending missile, and offensive missile as a king, an induce capture aircraftdefending missile synergy active defense method is put forward in transforming the complex air war confront problem between fighter and defending missile and offensive missile into a simple trajectory problem of fighter. Secondly, in light of the implementation process of active defense strategy, a process performance index during the implementation process of active defense strategy is put forward and the different between process performance index and traditional performance index is analyzed. Lastly, pointing at the problem of the QPSO’s result in the whole process can`t be able to be evaluate. So the method of RHC (receding horizon control) is used to maintain process performance index as the optimization index of every receding optimization window, which rise its real-time. Simulation shows that the process performance index could be converging rapidly into desired values, the control commands’ values of fighter and two others were in a small amplitude oscillation, so the active defense process was achieved, besides the effectiveness of strategy and the accuracy of arithmetic were proved.

Abstract:Topology of UAV ad hoc networks is more dynamic due to fast movement of nodes compared with other traditional ones. The performance of traditional routing algorithms is not able to satisfy efficient communication for multi-UAVs carrying out missions, and this paper proposes an on-demand routing algorithm based on link quality prediction. The link quality is chosen as a standard to choose route and calculated by sensing the stability of a link and the congestion level of a link. Meanwhile, relevant parameters are predicted by Grey-WNN prediction model, and then they are used to estimate the stability of a link and the congestion level of a link. After that, the link quality can be evaluated in advance. The process of routing discovery and routing maintenance is optimized according to the predicted link quality, thus avoiding the negative influence on swarm network caused by the high-dynamic characteristics of UAVs. The simulation results show that the algorithm improves the network performance obviously, decreases the number of route fracture, reduces the route overhead and average delay increases the packet delivery ratio when nodes are moving at a high speed.

Abstract:The temperature rising rate of carbon fiber reinforced concrete pavement slab has relations with many factors. In order to study the significance of influence of three factors, i. e. the working current intensity, the heating wire buried depth and spacing, on the temperature rising rate of the concrete, this paper uses ANSYS to modeling to test and obtains data by adopting orthogonal method and response surface methodology to analyze, and uses field test to verify. The F value of buried depth, spacing and temperature obtained by orthogonal method is respectively 13.634, 25.605 and 14.431. The P value of three factors obtained by response surface methodology is respectively 0.0375, 0.0126 and 0.0150. The analysis shows that these three factors have a significant effect on the temperature rising rate of concrete, and the order is B heating wire spacing> C working current intensity> A heating wire buried depth. The fitting equation of temperature rising rate obtained by DX is:α=2.73-0.077A-0.099B+0.096C+0.008AB+0.013AC+0.01BC-0.097A2+0.028B2-0.063C2, thus it can also be obtained that the spacing of heating wire is 80 mm, buried depth is 50～90 mm, working current intensity is 0.5～1.0 A, and the temperature rising rate meets the requirements of pavement slab deicing and snow melting.

Abstract:Aimed at the problem that energy efficiency of spectrum sensing is low in cognitive radio (CR) system, a joint optimization algorithm based on bisection and iteration is proposed. This algorithm sharply raises the energy efficiency of CR system by jointing transmitting power and sensing slot to reach the optimization. And in the process of optimizing parameter ξ, the methods of bisection and iteration are jointed to reach the optimization. Through theoretical analysis, compared to other algorithms, this algorithm is faster at optimization speed, lower in complexity, faster at function convergence speed and larger in space for extension in application. The results of numerical simulation show that under condition of provided detection performance, the proposed algorithm can deal with the optimization of energy efficiency well. Under conditions of the constant detection probability of P^d=0.9 and P^d=0.7, energy consumption of the proposed algorithm is lower than that of others, and the algorithm in system throughput is superior to others. This provides a theory support to CR system development, and is more in line with the energy-saving trend for CR system development in the future.

Abstract:According to the characteristics of heterogeneity, instantaneity, and high integration of physics and cyber in CPS, an event logic-based component coordination algebra model is built. Firstly, a temporal-spatial event interface based on component formal expression is defined. and an Event-Driven based component coordination behavior model is proposed. Then, according to the coordination modes between components, logical relationships between events are analyzed. Finally, taking the illegal invasion into smart home as an example, the paper uses the coordination algebra model to describe the process of event-driven component condult. The analysis show that event logic-based component coordination model can realize interaction between components and integration between physical process and computational process, shield the heterogeneity between components, and provides a novel method for formal modeling of CPS.

Abstract:Aimed at the problem that within a certain time, the non target receiver can still get the parameter of the demodulation parameters effectively through parameter scanning in the 4-WFRFT covert communication system, this paper proposes a satellite covert communication system by using the double layers multiple parameter weighted-type fractional Fourier transform (DL-MPWFRFT) and constellation scrambling is proposed. The paper proposes DL-MPWFRFT based on multi parameter WFRFT. The hiding principle and characteristics are analyzed through the research of constellation. Though increasing the signal concealment, the constellation scrambling phase increases again after DL-MPWFRFT signal conversion. Finally, from two aspects, the comparison of error rate and the number of parameter scans, the anti interception advantages of the proposed system are described qualitatively and quantitatively. By comparing the BER of the system, the result shows that even if the SNR is 15 dB, the BER of the non target receiver is still more than 0.4. The non purpose receiver obtains the correct demodulation parameters by parameter scanning, which needs (M/0.000 5)2 scans.

Abstract:Aimed at the problem that Bias and cycle slips of Carrier Phase measurements will occur because of multipath error, satellite signals blockage, satellite failure and other factors in utilizing differential carrier phase positioning, this paper proposes an integrity monitoring necessarily. The carrier phase integrity monitoring algorithm is researched based on single differential carrier phase measurements. After carrier phase inter ambiguities are determined, test statistic is constructed by using the method of least squares and threshold set according to the false alarm probability and number of observed satellites to test carrier phase measurements. Relationship between vertical protection level, satellite geometry and miss detection probability is analyzed. The experiment results indicate that when the false alarm probability is 10－7, the algorithm in this paper can detect measure bias effectively, and is more effective when the bias is as small as 0.4 cycle. When the missing alarm rate is 10－6 and the vertical protection level is 1.1 m, the algorithm meets the requirements of availability, and the addition of 1 observation satellites can reduce the vertical protection level by about 2 cm.

Abstract:On the basis of 2FSK digital modulation full-duplex systems, the paper finds that technical effect of applying conventional adaptive cancellation is not optimal. Aimed at this problem, the adaptive cancellation performance is identified. In order to analyze correlation property of 2FSK from a theoretical point of view, the paper constructs a full-duplex orthogonal 2FSK systems based on the RF domain self-interference cancellation structure based on the minimum mean square error (MMSE) criterion, which can confirm the influence of signal correlation on the acceptance of Bit Error Rate(BER). Based on the properties of generalized cyclic stationary stochastic processes, the paper derives the relations between signals correlation and BER. Then, the paper inhibits the impact of relevance in the White Gaussian Noise (AWGN) by an effective method. The result shows that the correlation coefficient ρ of the 2FSK signal is the linear sum of the symbol waveform correlation coefficients of the two frequencies. The range of the correlation coefficient is 0 ～ 0.5. After the signal of 2FSK is removed by self-interference, the error performance deteriorates with the increase of correlation coefficient ρ

Abstract:As for the solution of optimal control issues under conditions of complex restrictive conditions, this paper proposes a segmented low-order Gauss pseudospectral method. In this paper, a nonlinear program issue is obtained by the basis of conventional Gauss pseudospectral method and the temporal intervals compartmentalization. During each subinterval, low-order Gauss numerical integration is utilized for discreteness performance of Bolza problem; the property of interpolated type numerical integration is utilized for discreteness of differential state equation; low-order Gauss pseudospectral method is utilized to process complicate constraints. The method overcomes the shortcomings of a higher order of interpolation polynomial and an unstable numerical solution caused by producing Gaussian points at the interval directly under the situation of complex state orbit and control function, thus, having high local algebraic precision and small computation in numerical solution. Ultimately, the method is applied to optimal trajectory planning for air-to-ground operations. The result shows that the algorithm is effective and feasible.

Abstract:Aimed at the problems that the factors of the antierosion capacity influences on the airport ecological slope protection vegetationat the initial stage of growth, this paper performs a direct shear test and antierosion test on the turf of different planting density and protection modes, and obtains an equation on the numbers of plant and the soil cohesion increment in different ecological protection modes. On the basis of laboratory experiments, the antierosion velocity and erosion damage modes are investigated. The influence laws of different planting density and protection modes on slope erosion are analyzed. In addition, the relationship between soil cohesion and turf soil impact velocity is explored, and the conditions and methods of the engineering applicationare given.

Abstract:Aimed at the problem that Baldwin effect in memetic differential evolution is not ripe for application, This paper proposes a Baldwin effect-based memetic differential evolution (BMDE) algorithm. The algorithm takes the simplified Hooke Jeeves as a local search and DE for globe search with Baldwin effect to Differ from other memetic DE algorithms. The proposed algorithm uses a new method to carry out Baldwin effect by enlarging learned probability of individuals with better local search to change the evolution direction and diversify the population. Tested by 30 benchmark functions in CEC2014 and compared with standard DE and 3 state-of-the-art DE algorithms, BMDE performs satisfied convergence ability.