Abstract:Plasma flow control can significantly improve the aerodynamic characteristics of aircraft and power plant through plasma aerodynamic actuation, and this technology has already become a front subject in international aerodynamics and aerothermodynamics fields. Status of overseas plasma flow control research is introduced briefly. Progress of Air Force Engineering University in plasma shock flow control theory, plasma aerodynamic actuation characteristics, plasma based compressor stability extension and shock control is presented. Also, the important problems in future are pointed out.

Abstract:Inter-stage-turbine burner(ITB) with no radial vane cavity and five different kinds of radial vane cavity shapes three-dimensional combustor model on two phase combustion flows are simulated by utilizing a computational fluid dynamics software together with [WTBX]k-ε[WTBZ] model and simplified PDF combustion model. Velocity field, temperature field and overall performance of different kinds of ITB models are compared and analyzed. The result shows that the different radial vane cavity shapes differ on the velocity and temperature field in the radial vane cavity, and then have an influence on the combustion completeness of the rich burn products and outlet temperature. By changing the radial vane cavity shapes, ITB can obtain higher combustion effeciency and outlet temperature, smaller pressure drop and better species concentration standard.

Abstract:Fly-By-Wire (FBW) system is safety-critical system for flight safety. Regarding safety evaluation problem of FBW system, flight risk small probability event evaluation method based on Extreme Value Theory (EVT) after flight control system's failure is proposed. Step of evaluating flight risk based on EVT is summarized. By contrasting the fitting effects under different coordinate transformations, the result shows that double negative exponential is the best method of approaching extreme value distribution of type. Taking flight safety evaluation after execution failure of one aircraft for example, probability of unsuccessfully eliminating the failure for the pilot and the integrated flight risk are calculated. According to flight risk in military standard, this aircraft can satisfy the safety requirements. Then an available method of evaluating safety of aircrafts' flight control system is proposed.

Abstract:To solve the control problem of a general hypersonic vehicle，which is a complex nonlinear uncertain system, a robust adaptive integrator backsetpping control strategy based on wavelet neural network is proposed. Integrator is used to decrease tracking error of the system. The system asymptotically tracks the desired output by means of on-line studying uncertainties and the derivative of virtual item via wavelet neural network, so robustness is enhanced. Robust items are designed to eliminate approximate error of the wavelet network. Theoretical analysis is done to validate Lyapunov stability of the system. The simulation results show that the developed method is effective and can be used to deal with the problem of uncertain parameters preferably.

Abstract:Static balance is the initial condition of catapult launch dynamic analysis, and the foundation of establishing the catapult launch model. Carrier, aircraft and landing gears, etc. are considered as multi-motion bodies that have their own masses, and the coupling relationships within these multi-motion bodies are also analyzed. The six degrees of freedom model of carrier-based aircraft is established in the condition of static balance, with the influences of carrier movement, deck wind and the airflow interference on aircraft considered. This model is applied to calculate and simulate the static balance of aircraft in different situations. The simulation and calculation results are consistent with the actual situation, which lays a foundation of dynamics analysis on carrier-based aircraft catapult launch with the six degrees of freedom model.

Abstract:Based on foil RAE 2822, in order to research the effect of y+ of non-dimensional quantity parameters on computing precision of pneumatic parameters of foil, the computational grids created by ANSYS ICEM and the disperse format of N-S control equations with the method of finite volume method are employed, SST turbulence model is selected, pneumatic parameters of foil are numerically simulated. The relative error is analyzed, and the contour of pressure coefficient is drawn recurring to ANSYS CFX module under different y+. The results show that too large y+ leads to the increase of error, the computing precision is less change nearby the theoretic value 11.63 of y+ and lesser y+ may make the precision further improved, but higher precision couldn't be with too small y+. The impacts of y+ on the computing precision are various in different regions of foil boundary, and y+ selected between 2 to 4 is recommended when pneumatic parameters of foil are simulated.

Abstract:A novel planar transmission-line style of left-handed metamaterial is proposed, and its electromagnetic characteristics are investigated. The dispersion curve of the proposed structure has been derived by using Bloch-Floquet theory and the CRLH TL is proved. Then the equivalent circuit model of the CRLH TL unit is provided, the parameters of the equivalent circuit model are extracted under balanced and unbalanced conditions by optimizing and synthesizing. The model is validated by comparing the circuit result with the simulator result. The novel planar transmission-line style of the left-handed metamaterial does not need defected ground structure, so it can be easily designed and fabricated.

Abstract:The main mission of early warning system of LEO is to detect and track the midcourse missile, so the problem of the staring sensors coverage of LEO is researched in the article. Firstly, the models of staring sensors in different space altitudes are built based on their operating range and turning of lens. Secondly, according to the limitation of the grid analysis method, the rule of grid partition is improved and the function relation of the latitude and longitude alternation、the grid precision of grid partition in the different latitudes is set up, the computing process of coverage analysis is put forward based on the typical coverage performance index. Finally, some space coverage performance of a typical constellation is educed through simulation, and the result shows that the coverage models and the improved grid method are available and effective.

Abstract:In this paper. a SIW three apertures directional coupler is designed by the theory of rectangular waveguide multi-aperture directional coupler and the equivalent relation between SIW and rectangular waveguide. Then, a new three apertures directional coupler is proposed through opening a dumbbell-shaped slot on the metallic surface of coupling aperture. The experiment result shows that the performance of the directional coupler is greatly enhanced. Within the frequency range of 8.6 GHz-10.6 GHz, the reflection coefficient of the input and transmission coefficient of the isolated port are both below -15 dB, and the relative bandwidth is 20%. Transmissions of the straight port and coupled port in the pass-band are between -8.2 dB and -3.3 dB. This coupler's coupling is about 6 dB, and the isolation is over 15 dB.

Abstract:The micro-motion feature extraction for micro-motion target has attracted great attention in recent years. The micro-Doppler (m-D) effect of rotating target is introduced in the netted radar techniques in the paper. The m-D effects are separately analyzed and the parameterized expressions are deduced in the netted radars that transmit different forms of signals. Making use of the multi-view of netted radar, the parameters of the radars' different forms of echo signals those come from different locations are extracted, the three-dimensional micro-motion features are obtained by solving nonlinear multivariable equation systems. Simulation results validate the effectiveness of the proposed algorithm.

Abstract:A novel CPW-fed circular disc ultra-wideband antenna with dual band-notched characteristics, which can meet the demand of communication of the day is designed in this paper. With the antenna fed by CPW, good ultra-wideband impedance match can be achieved. Meanwhile, to obtain the notched bands at the frequency range of WLAN and WiMAX, two C-shaped slots are embedded into the radiating patch, then, electromagnetic compatibility is achieved. Through comparison, the theoretical、simulated and measured results are coincident, which shows that the antenna has a good radiating characteristic with the return loss under -10 dB and the radiation patterns matching within the transmission band. The gains of the antenna within the notched bands have been reduced separately by 3.2 dB and 7.5 dB, thus effectively reducing the radiation.

Abstract:The advances in the research of adaptive C2 organization is surveyed from two aspects in this paper, which are the methods of organization adaptive adjusting and the methods of organization testing. The methods of organization adaptive adjusting include the methodology based on three-phase organizational design, the methodology based on granular computing and the methodology based on layered method of organization structure. And the methods of organization testing include the methodology based on DDD-III, the methodology based on Extend and the methodology based on dummy closed loop. The advantages and the disadvantages of these methods are analyzed respectively. Finally, the future research trends of adaptive C2 organization are presented.

Abstract:The networked command information system has become an important and necessary part of modern war. The evaluation of its effectiveness has become more and more concerned．To weight value of importance of each index, an improved analytical hierarchy process (AHP) based on the optimal transfer matrix is used．In the model，every index is quantitatively analyzed and the value of grey cluster of each subset effectiveness is calculated based on the grey cluster method and the result of experts．As a result，a quantitative evaluation of the effectiveness is achieved．Finally，as an example，the model is used to evaluate the effectiveness of a system，and the result shows that the model is of some practical value．

Abstract:To solve the problem that how to improve the performance of STAP in the environment of complex active jamming, an improved adaptive beams formed method based on the part space adaptive array processing is put forward .The method is presented, which is a method of special anti-jamming technique in series with filtering clutter using STAP technique. At first, MUSIC method is used to estimate DOA of the active jamming, then, multi-beams are formed on the anticipant and interfered directions. Finally STAP technique is used to suppress clutter after anti-interference filtering in the space. The result of simulation demonstrates that the use of this method can effectively estimates active jamming's orientation, and maintains the performance of clutter suppression in the environment of interference. Using adaptive filter in the beam domain can reduce the required computations. The efficiency of the method is demonstrated by simulation.

Abstract:The use of the existing Loss Differentiation Algorithms (LDA) cannot get prior knowledge from actual networks, so the algorithms can hardly be generalized to various environments. To solve this problem, a new LDA is proposed by enhancing the Fuzzy One-class Support Vector Machine (FOCSVM). The new LDA converts the differentiation packet loss between congestion and bit error on wireless links into judging that whether the loss is because of bit error. The training set consists of only the in-sequence packets received by the receiver, so the classification model can be got and updated during the session, without the prior knowledge about the two types of loss, which makes the LDA have fine generalization. Simulation results show that the proposed LDA has good differentiation accuracy and can enhance the utilization of resources in wireless networks.

Abstract:Aimed at the energy efficiency problem with discrete power in actual wireless sensor networks, minimum energy routing algorithm is studied. Based on the typical energy consuming model, the ideal minimum energy routing is presented. Ideal minimum energy routing is a linear programming problem, and a minimum energy routing algorithm which is close to the ideal minimum energy routing algorithm--proximate optimal-point routing (POPR), is proposed. POPR is based on geographical location information and with the character of distributed and easy to be implemented in real life. The simulation results show that the performance of POPR becomes better when the node density is high.

Abstract:Evidence classification strategy can resolve the conflict evidence combination problem. To classify the evidences and make sure of the uniformity of the evidences in one class, this paper gives the definitions of evidence-attribute support degree、classification threshold、evidence believe degree. When a series of beliefs are available, D-S rule in inner class is adopted, and the weights of every class according to the number of evidence in each class and the uncertainty of evidences are obtained, then all the combination results are integrated with weight rule to form the final results

Abstract:Aimed at the problem of metal magnetic memory that the microcosmic cracks cannot be evaluated quantitatively by the metal magnetic memory testing method at present, the numerical value relation between the magnetic conductivity and stress is derived based on the analysis of the metal magnetic memory testing mechanism by using the theory of Jiles, who discussed the physical mechanism of the stress-magnetization effect. The finite element analysis of stress-magnetization effect is done on steel plate specimen with a microcosmic crack using ANSYS. Through the analysis, using an applicable magneto-elastic coupling model and distilling the peak value's distance and peak value of metal magnetic memory can evaluate the breadth and deepness of microcosmic cracks quantitatively.

Abstract:This paper studies the effects of A-site non-stoichiometry on polarization degree of K0.5Na0.5NbO3 -AgNbO3 lead-free piezoelectric ceramics. In the research, through the preparation of Lead-free piezoelectric 0.96K0.5+xNa0.5+xNbO3-0.04LiSbO3 ceramics by solid state reaction and the building of polarization models of perovskite structure, effects of electric fields and different temperatures on the polarization and piezoelectric properties of ceramics are studied when x is at different values. Results show that the ceramics sample with the properly excessive A-site ions is not highly dependent on polarization temperature and electric field, which can realize effective polarization and improve the piezoelectric properties. On the contrary, the ceramics sample with normal A-site stoichiometry is sensitive to polarization temperature and electric field, easy to be broken down, resulting in ineffective polarization and lowered piezoelectric properties.