Abstract:Life of aircraft is determined by the life of aircraft structures，and the durability life and safety life of aircraft structure are the foundations for the safety in service. On the basis of deeply analyzing about the effect of key factors on structure service life in the process of design, manufacture and service, this paper is going to focus on the prediction method of structure residual life and the life expansion technology based on the “safe life envelope”. The research category of the aircraft structure life control technology and the adjust method of aircraft service plan are elaborated. The aircraft structural life control technology in this paper can transform the aircraft structure life management measure from the traditional “fixed consumption” model to the “active control” model.

Abstract:In order to find out the interaction mechanism, influence law and the lift augmentation efficiency of the plasma circulation control on airfoil aerodynamic characteristics,the influence law of different trailing-edgeradius, single actuator position and arrangement mode of doubleactuators on the airfoil aerodynamic characteristics and flow field characteristics is investigated, by adding the equivalent volume force to the Reynolds-averaged Navier-Stokes equations. The result shows that the lift augmentation efficiency improves markedly by using the optimized medium trailing-edge radius model and applying two groups of plasma actuators reversely arranged on the upper and lower surface. The research shows that the profile with medium trailing-edge radius is comparatively good in lift enhancement effect because its centrifugal force and pressure gradient are balaced ,and the plasma actuation jet drives the upper surface outflow deflected by guiding the couple of shed vortex moving to lower surface.The optimized double plasma actuators can make plasma actuation jets cascade , guide the couple of shed vortices moving to lower surface, and push the separation point down,thus causing the obvious behavior of profile’s circulation and lift enhancement. The results provide a theoretical basis for subsequent experimental study.

Abstract:The aerodynamic design of new generation aircraft and engine has an important need for active flow control technology. The advantages of plasma flow control are fast in response, wide in frequency band, and simple in structure. Dielectric barrier discharge (DBD) plasma aerodynamic actuator is the most popular form of actuators. However, in the international work, its life characteristics is almost in a state of neglect, thus seriously restricting the development and application of plasma flow control technology. In the light of solving the scientific problem, the experimental study of PI / nanocomposite PI-based plasma aerodynamic actuator is carried out. The results show that the nanocomposite has the advantage of improving the thermal conductivity of the actuator, and the maximum temperature is 10%-20% lower than that of the traditional actuator; the self-healing phenomenon of the nanocomposite PI-based actuators is found; nanocomposite actuators inhibit structural damage, thereby preventing rapid increase in discharge power and surface temperature; after the aging of the PI surface, a large number of holes, trenches and ablation traces are formed on the surface of the PI, and a large number of white spherical nanoparticle clusters appeare on the surface of the nanocomposite PI after aging, reducing the damage of the insulating material.

Abstract:In view of influence of multi-control surfaces on static aeroelasticity of two-dimensional wing, the model used in this paper is based on two dimensional wing with leading- and trailing-edge control surfaces and the location of elastic axis at the back. Based on the CFD/CSD loose coupling static aeroelasticity numerical calculation method, the aerodynamic characteristics and torsional deformation of two-dimensional wing with different deflection modes of control surfaces are calculated and analyzed under condition of Ma=0.3. The results indicate that when leading- and trailing-edge control surface deflect clockwise, the aerodynamic characteristics is bad while torsional deformation characteristics is good, and peak of torsional angle(θmax)decreases about 43.32% ~ 62.92% compared with the basic wing. When leading-edge control surface deflects anticlockwise , the situation is contrary, the maximum of lift coefficient(Clmax) increases about 42.96% ~ 57.58% and stall angle of attack decreases about . The study can provide reference for the application of multi-control surfaces on active control of aeroelasticity of forward swept wing.

Abstract:Aimed at the advantages that UAV ammunition damage to the airport runway is of zero damage and zero death, this paper proposes a kind of damaging and combating model on penetration and explosion of airport runway in the UAV small blockade ammunition based on Autodyn. A huge losses of aircraft and personnel damaging airport runway is avoided. By depending on the Design-Model tool, this paper builds up a 10:1 model of BM100 light anti-runway bomb, and performs a simulation under conditions of Autodyn environments. The cycle process of penetration and explosion and key Gauges point waveform chart and damaging cloud chart are obtained for 10:1 model. The result shows that BM100 read depth and radius of blasting pit are 500mm and 400mm based on geometric similarity model. The hollow phenomenon is appeared in the lower part of blasting pit. this caused great difficulties to repair the airport and more difficult to repair than blasting pit.

Abstract:Based on the theory of planar array scattering and the idea of antenna shared aperture, this paper proposes a design of shared aperture metasurface (SA-MS) composed by perfect metamaterial absorber (PMA) and artificial magnetic conductor (AMC) in stagger arrangement. The SA-MS not only can achieve wave-absorbing, but also has the function of phase counteraction. The simulation results indicate that the SA-MS can achieve broadband radar cross section (RCS) reduction compared with the surface of perfect electronic conductor (PEC), PMA and PEC-AMC due to cascade connection of frequency band between PMA and AMC . Then the SA-MS and waveguide slot antenna are integrated and fabricated. The simulation and measured results show that the gain of proposed antenna increases by 3.3dB compared with the reference antenna. At the same time, the RCS of SA-MS antenna is reduced by more than 6dB at the range of 5.52-7.51GHz, and the relative bandwidth is 30.5%. The largest RCS reduction reaches 20.5dB and 20.2dB on the condition of x polarization and y polarization respectively. The SA-MS can improve both the radiation and scattering performance of the antenna.

Abstract:In view of the RF stealth performance evaluation problems, this paper presents a method for fuzzy evaluating the RF stealth performance of the airborne radar system. Through analyzing the factors that radar radiation source influences the performance of the airborne radar system in the polarization domain, wave domain and energy domain, the RF stealth index of the waveform domain , polarization domain and the energy domain are constructed, a RF stealth evaluation method of the traditional "radiation reception" model is broken, the fuzzy evaluation method of radio frequency stealth based on the working state and working parameters of airborne radar system is established. Finally, the simulation evaluation of different airborne radar system is carried out. The results show that the method can correctly reflect the RF stealth performance of airborne radar system.

Abstract:In the light of low angle target direction of arrival (DOA) estimation problem of MIMO radar under condition of multipath, a DOA estimation algorithm with sample multiplexing at low angle multi-path target of MIMO radar based on FBSS (Forward-Backward with spatial smoothing) is proposed. In consideration of the difference between the coherent signal and multi-path signal DOA estimation of MIMO radar, four path model of MIMO radar echo signal is adopted by algorithm to obtain the virtual array by the matched filter according to the Waveform diversity of MIMO radar, and to reuse the virtual array by rows and columns for FBSS, thus effectively improving the low angle target DOA estimation accuracy on the condition of low signal-to-noise ratio. The simulation results show that the RMSE of the proposed algorithm is reduced by an average of 1 degree compared with the M-SSMUSIC when the SNR less than -12dB.

Abstract:In the light of realizing the self-learning operation mode recognition of air borne fire control radar, an optimized LSSVM algorithm based on grid search and K-fold verification is proposed. First, this paper extracts feature parameters from non-cooperative radar signals and establishes library base of radar signal as training sample in LSSVM model. Next, the paper applies grid search method in parameter optimization to realize model adjustment under the circumstance of uncertain sample range. In the sequel, the paper utilizes K-fold cross validation for realizing performance evaluation and reducing model error caused by sample randomness to improve generalization ability. The simulation results show that the recognition accuracy of VS/RWS/TWS/STT modes reaches 97%, thus having a good recognition performance and practical value of proposed method.

Abstract:The efficiency of the extracted buildings always is a key in engineering application of LiDAR points. Aimed at the problem that the efficiency of filtering first and then extracting methods, currently in effect is low, a method combining Delaunay TIN models and region growing for extracting buildings from raw LiDAR data is put forward in this paper. Firstly, Delaunay TIN models are built on the original LiDAR points. Edge points of buildings can be extracted by using the normal vector, length of side and point height of triangles where the edge points are located. Then, the extracted edge points are assigned as seed points in order to implement region growing based on triangle network connections which will yield a points set of protrusion. Finally, since the number of non-building points is much smaller than that of the building points, the non-building points set can be deleted while the building points set is reserved. The method in this paper can be used to extract building points set and edge points directly without the operation of filtering and provide foundation for further contour extracting and building reconstruction. The simulation results show that the method has obvious efficiency under the guarantee of accuracy in extraction and has a certain of adaptability.

Abstract:On consideration of the difference between edges in the network, this paper constructs a weighted scale-free network model based on the BA scale-free network model, builds a load reallocation strategy model, analyzes the efforts of local distribution size of network on survivability, determines the optimal load reallocation strategy, and analyzes the influence of network parameters on the network invulnerability under deliberate attack condition and different load reallocation strategies. The simulation results show that the smaller the network weight coefficient and the greater the average degree, the stronger the network survivability, namely the network’s cascading invulnerability becomes stronger while the network is more homogenous and denser, and the network’s invulnerability is always superior to the handy full load reallocation when the handy local load reallocation strategy is adopted. This research can provide a theoretical reference for improving the network invulnerability.

Abstract:This paper studies the localization problem of Wireless Sensor Network (WSN) in Indoor Non Line of Sight (NLOS) environment. Under condition of the optimization estimation framework, an error function to be optimized is firstly proposed, and then based on advanced Multidimensional Scaling-MAP (MDS-MAP) method, the coupling relationship among the unknown variables is analyzed, and finally an optimization localization algorithm based on improved MDS-MAP is designed. Without any prior environmental knowledge, the proposed algorithm can be conducted merely with distance information suitable for WSN in unknown and complex environment. Simultaneously, the algorithm does not need any redundant information (e.g. angle and signal strength), thus possessing the properties of low hardware requirement and low cost. The effectiveness of the proposed algorithm are illustrated through several simulations examples. And the clustering analysis method is adopted to analyze the localization precision with different numbers of basis stations. According to the simulation results, the approximate optimal localization results with low cost are reached in 3-dimensional space when the number of the basis stations is six.

Abstract:Aimed at the problem that serious torque ripples exist in brushless DC motors (BLDCM), this paper proposes a three-phase cooperative modulation to eliminate the commutation torque ripple. During non-commutation, the paper proposes a direct torque control to eliminate torque ripple by adopting hysteresis comparison to follow-up control torque and flux linkage of BLDCM. The paper establishes a relationship between motors torque and input power. The method based on one cycle control enables the system to control input power accurately, even more control torque of BLDCM correctly. The simulated and experimental results show that the method of torque ripple suppression of current and electromagnetic torque waveform is smooth for a motor in speed changes compared with the traditional control method whose current and electromagnetic torque can produce fluctuations. When the torque ripple suppression method is used, the influence of motor speed changes on the influence of winding current is small. Motor electromagnetic torque can relatively stably output. The validity and corrective of the theoretical analysis are verified.

Abstract:Aimed at the problems that the existing network situation awareness cannot acquire on-demand situation information and cannot adjust the network structure according to situational threat of network attacks dynamically, a SDN-based virtual honey-net architecture is proposed on the basis of flexible traffic control principle with the combination of good scalability and manageability of OpenDaylight controller. Through constructing a SDN-based virtual honey-net, the separation between data control layer and data transmission layer is realized. Simultaneously, traffic controlling difficulty and inconvenience of deploying or dynamically adjusting physical machines are solved compared to traditional honey-nets. At last, the paper utilizes Mininet platform for building SDN virtual honey-net. The experiment results show that the SDN-based virtual honey-net can achieve on-demand access to situation information and dynamic adjustment of network structure etc., thus reducing the network attack threat.

Abstract:Aimed at the network congestion problem for mobile ad hoc network based on energy aware technology and load balancing combined with congestion control method, this paper proposes an energy-aware multipath load balancing routing algorithm. The algorithm utilizes energy-aware for selecting the node of satisfying the conditions as the routing node to establish multiple effective paths of connection source node and destination node. At the same time, the paper analyzes the number of hops in the paths and the buffer occupancy of the node, selects the optimal path for transmission from the efficient paths, and establishes a model of the load of nodes and paths on the optimal path. When the energy of node, the load of node and the load of the path reach the set threshold, the flow of the optimal path is diverted to other paths. The simulation software NS2 is utilizes for testing this algorithm, QMRB and SMORT in different scenarios. The simulation results show that the proposed algorithm improves the network performance by about twenty percent compared with the other routing algorithms.

Abstract:This paper utilizes a kind of mineral powder and solid activator for paparing a quick setting and early high strength inorganic polymer concrete suitable for airport pavement. Based on the response surface analysis method, the experimental results are modeled by using the Design Expert statistical analysis software. The paper researches the notability degree of variables water-binder ratio, cementitious materialsconsumption, sand ratioand the intermingled influence between them towards inorganic polymer concrete slump, initial setting time and 7d rupture strength.The results show that the notability degree effects of water-binder ratio, cementitious materialsconsumption and sand ratio on inorganic polymer concrete slump, initial setting time and 7d rupture strength are different, and the order of notabilitydegree is cementitious materialsconsumption>water-binder ratio>sand ratio, water-binder ratio>cementitious materialsconsumption>sand ratio, water-binder ratio>sand ratio>cementitious materialsconsumption; In addition, the notabilitydegree of the interaction between any two factors are different. The interaction between water-binder ratio and cementitious materialsconsumption has the most significant effect on slump, and the interaction between cementitious materialsconsumption and sand ratio has the most significant effect on the 7d rupture strength. The interaction between any two factors among the three has no significant effect on initial setting time.

Abstract:Projectile penetration is always a hot research topic, and the prediction of the penetration depth of the rock targets is mainly depended on the empirical equations. The common empirical formulas are summation of the knowledge of the old bombs or the general aviation bombs, they are not suitable for the new development of the earth penetrator weapons, the calculated results of some formulas are far from the actual results, and the empirical formulas, indeed, are necessarily modified. The similarity theory and the dimensional analysis method are used to determine the key parameters affecting penetration depth, and the function relation is established. Then the empirical formula of the earth penetrator weapons penetrating rock targets is fitted through a large number of data. Numerical simulation is carried out on the earth penetrator weapons penetrating rock targets by ANSYS/LS-DYNA. Compared with the results of the fitting formula and the common empirical formulas, the result indicates that the results of the numerical simulation are well consonant with the results of the fitting formula, and the fitting formula can be applied for predicting the depth of earth penetrator weapons penetrating rock targets.

Abstract:In order to build an effective operation system under conditions of information, this paper describes concept of army organization formally from two aspects of organizational entity and organizational structure, and proposes a systematic adaptive design method of army organization. The idea of the proposed method is to resolve such complex problems into four relatively simple sub-problems first, i.e. operation plan design problem, operation plan adjustment problem, command and control (C2) structure design problem and C2 structure adjustment problem, and then to solve these sub-problems for the achievement of construction and dynamic evolution of army organization. The coupled relations among sub-methods used to solve the sub-problems are analyzed in detail and the input/output information of the sub-methods is ruled. On the basis of this, the design method and adjustment method of operation plan are introduced with the comprehensive consideration of task completion time and task completion quality of army organization while the design method and adjustment method of C2 structure are presented with the measurement of load level and load balancing extent of army organization. Finally, the future development of the proposed adaptive design method is given.