Abstract:Based on the thought that the jet flow from slot outlet can control separation of boundary layer on the suction surface, an improved slot configuration is designed to obtain better flow field characteristics of cascade. The CFD measures are used to analyze the effect of blade slot treatment on performance of cascade. Different slot outlet angles are studied. The results indicate that the improved slot configuration can help obtain better flow field characteristics, higher turning angle and static pressure rise, and lower total pressure loss. Slot outlet angle obviously affects the flow field characteristics of cascade.

Abstract:An algorithmic method of calculating angle precision of remote target by dual-aircraft coordination passive locating way is performed. Firstly, with some proper hypotheses, an analytic equation of dual-aircraft coordination locating remote target based on Direction of Arrival (DOA) is set up. Then the mathematic relationship between azimuth angle and Time Difference of Arrival (TDOA) based on wavepath difference is established. And then, by using the method of Taylor Series, an approximate algorithm of calculating the azimuth angle's probability distribution by calculating TDOA's probability distribution is presented. Finally, the affection of different dual-aircraft's position on angle precision is analyzed through simulation. The feasibility and the validity of the algorithmic method are demonstrated by the experiment.

Abstract:The aviation kerosene is a practical candidate fuel for scram-jet engine in the flight regimes of Mach number less than 8, because of the characteristic of high energy, high density, safety and portable. The key is how to achieve shabbily burning in super combustor. In this paper, the ignition characteristics of a scramjet combustor model fueled by aviation kerosene is experimentally investigated by using the resistance heating direct-connected supersonic combustion facility of Northwestern Polytechnical University. The inflow conditions at the direct-connected combustor entrance are specified as: the nominal Mach of 2, the total temperature of 870-930 K and the total pressure of about 770 kPa. Three combustor performances of different ER are compared and analyzed by applying CFD simulation. The experimental results suggest that the cavity design is a key problem for kerosene successful ignition in the combustor. The choice of appropriate gas-oil ratio can increase the performance of combustor and keep the isolator from being interfered by gas.

Abstract:An adaptive backstepping terminal sliding mode control scheme is proposed for a class of uncertain nonlinear systems in strict-feedback form with unknown nonlinearities. The dynamic surface control is combined with the first steps of backstepping method to design the virtual controller. In the -th step, only one neural network functions approximator is adopted to compensate all the unknown nonlinearities, and a adaptive neural network controller based on global fast terminal sliding mode design is obtained. The proposed controller design approach avoids the explosion of complexity in traditional backstepping design, and improves the convergence rate and steady-state tracking accuracy of the system by introducing approximation errors and adaptive compensation of uncertainty bounds to eliminate the errors of modeling and parameter estimation. By theoretical analysis, all the signals in the closed loop systems are guaranteed to be semi-globally uniformly ultimately bounded. Finally, the simulation results validate the effectiveness of the proposed method.

Abstract:In order to solve the problem of the optimization of highway runway locating, by the way of investigating and consummating the targets of the highway runway locating, the paper has synthetically considered the requirements in four aspects of usability, technicality, economy and environmental protection to establish the system of evaluating targets for the highway runway locating. Each initial target weights are determined respectively based on the entropy method and the improved AHP method in a combination weighting method, by using the method of composing linear weighting all the target weights are ascertained finally. And then the measuring degree based on the Euclid distance for comparing the opposite closing degrees of all schemes is at a distance from perfect point, then the model of optimizing multiple target decision is established for selecting the best highway runway locating spared schemes. In combination with the living example of highway runway locating, the model of optimizing multiple target decision is tested effectively and practically.

Abstract:In order to solve the problem that the aero-gas turbine may cost too long time when starting on plateau ground, adjustment schemes were searched to shorten the starting time based on theory analysis. And then an engine-starting experiment was carried out on a plateau airport. To test the feasibility of adjustment schemes and further to get the optimal one, the scheme of oxygen supply was used in the experiment and the scheme of hydraulic load control was used on the base of the first scheme. After theory analysis and experimental investigation, a synthesized adjustment scheme, oxygen supply at the beginning of engine start together with hydraulic load control during engine start, was got. The results do show that the adjustment scheme can improve the residual power of the engine at the beginning of starting and shorten the starting time about 18%. The maximum discharge temperature during starting is reduced a little. Therefore, the adjustment scheme can improve the engine-starting performance on plateau ground effectively.

Abstract:The Multiple-Input Multiple-Output (MIMO) radar imaging with OFD-LEM has an important and practical value for non-cooperative moving targets detection and recognition. Some researches on the problem about moving target high-resolution range profile (HRRP) synthesizing method for MIMO radar with OFD-LFM signal are carried out in this paper. First of all, the imaging geometric figure of MIMO high-resolution radar with OFD-LFM signal is established. On the basis of that, a new moving target HRRP synthesizing method based on phase compensation for MIMO radar with OFD-LFM signal is proposed via strictly theoretical deduction and detailed principle demonstration. The moving target HRRP can be synthesized effectively by using the proposed method, because the orthogonality among the different sub-pulses is utilized. What's more, the condition of unwrapped HRRP is also obtained successfully. The simulation results validate the effectiveness of the proposed method.

Abstract:Aimed at the precision and real-time quality of the track association problem for High-speed aerospace vehicle, by using the link of coarse association and precision association, an improved fuzzy inference algorithm is proposed, in which both attribute parameters and location parameters are considered. This algorithm is better than the traditional algorithm based on statistical theory in the speed of track association processing. The simulation result shows the validity of the algorithm.

Abstract:TBM intercepting effect assessment is an important and complex job in the TBMD. In order to comprehensively consider the influence of various factors on the intercepting effect assessment in TBM intercepting combat, the assessment system is analyzed based on infrared imaging, ISAR imaging and maneuvering target tracking methods. In view of Neural Network' advantage in dealing with the complex problems, an assessment model with BP Neural Network is built, and the building process is discussed in detail. The standard BP algorithm with the problems that the convergence speed is slow and local minimum points are easily formed, is improved through adding momentum top and adjusting factors timely. Finally, the improved BP algorithm is simulated through living example and analyzed, the result shows that the improved algorithm is better in convergence speed and accuracy, and simultaneously verifies the validity and reliability of the model in TBM intercepting effect assessment.

Abstract:In order to decrease the influence resulted from the fluctuation of moving targets RCS in the flight process, this paper gives several common target RCS fluctuation models based on the analysis of RCS characteristics, then builds a proper model considering the concrete circumstances of virtual targets, and makes a detailed analysis of the effect that the long dwell signal combats fluctuating targets. Compared with the conventional radar signal, the long dwell signal could smooth the RCS of fast fluctuating targets under certain fluctuant frequency range and decrease a series of influence resulted from fluctuating targets through analyzing the results of long dwell signal sampling. Finally, the long dwell signal could implement stable tracking effectively in the perspective of analyzing stable tracking range. The simulation results also show that the long dwell signal has a good property in anti-target fluctuation.

Abstract:Based on the motion characteristics of near space hypersonic targets，a moving model for the near space hypersonic targets is built. According to the current statistical model, using the function relationship of range and acceleration, a new adaptive maneuvering target tracking algorithm, called ADE-IMM is presented. The use of this algorithm can improve the tracking accuracy of tracking the hypersonic targets in near space. Simulation shows that this algorithm simultaneously has the advantages of both Singer-IMM and CS-IMM algorithms in tracking the hypersonic targets in near space.

Abstract:The domestic autonomy Linux operating system is currently difficult to popularize for little application and unfamiliar operation, so a Linux operating system specially developed for compatible with Windows application is presented, to solve the problem, which named KgdLinux. A hierarchical architecture for KgdLinux operating system is brought forward, which consists of the application layer, compatibility layer and core layer. The application layer is made up of the Windows and Linux application, the core layer is composed of Linux kernel and various program share libraries, and for the compatibility layer the method of kernel virtualization in user space for running Windows application on the KgdLinux is used. The compatibility layer provides the function of loading executives with PE format and Windows virtualization environment, and simulates the function of Windows API. Finally the performance of KgdLinux for running Windows programs is tested by using a variety of benchmark and common applications. The experimental results show that, compared with the Windows programs running on VMware Workstation and Longene, the Windows programs running on KgdLinux are better in performance, and close to the performance of the programs running on the native Windows XP.

Abstract:One of the tasks of the research on the complex network invulnerability is to optimize the topology structure of network. Based on the analysis of the invulnerability of common complex networks, the natural connectivity is used to measure the invulnerability of complex networks, and the topology structure optimization model is established. Because of the good performance of ADMPDE algorithm, the improved algorithm is applied to solving the topology structure optimization model. According to the simulation analysis, it is verified that the topology structure optimization model of the complex networks and the improved algorithm are reasonable and feasible, the essential rules of the topology structure optimization are obtained, and the invulnerabilities of the primary and the optimized complex networks are analyzed with the random attack, the intentional attack.

Abstract:Because of the influence of the curvature of cylindrical conformal array, the performance will be deteriorated and even become invalid when MUSIC algorithm is used to estimate signal's DOA. The problem that the steering vector and the noise subspace are not orthogonal is efficiently solved by reconstructing the steering vector with directional of array element in consideration of the carrier's block. By contrasting with sub-array divided technique, Monte Carlo simulation and verification are done, and the estimation performance of MUSIC algorithm is analyzed. Finally, by taking the multi-layer column for example, the DOA estimation for four sources from different orientations are simulated and verified. The simulation results show that the method has the advantages of high differentiation and precision, also demonstrate that the proposed scheme is efficient and of high estimation performance.

Abstract:Remote field eddy current (RFEC) technique in combination with the advantages of infinitive from skin effect and ability to detect the inner crack of metal member is characterized by its equal sensitivity to a flaw irrespective to its location in the tube wall, and has a small relationship with the magnetic field from the exciting coil. This paper applies the traditional pipeline RFECT to detection for plate member. In this paper the basis of the principle of RFEC is analyzed, the cylindrical and rectangular exciting coils are designed; the detection effect of plate and the law of magnetic flux density of two sensor models are simulated. The result of simulation shows that rectangular exciting coil can induce the directional magnetic field in the plate and RFECT can be used to detect the crack in plate and perform quantitative determination of the depth and length.

Abstract:In view of miniaturization considerations, in this paper, we present a miniaturized CNSS micro-strip antenna based on high permittivity (permittivity is 16) ceramic substrate. This antenna works at S Band (2 492± 5 MHz, right-handed circularly polarization). Numerical results show that impedance bandwidth (S11<-10 dB)and 3 dB axial ratio bandwidth are about 62 MHz, 15 MHz, and the measured results show that impedance bandwidth (S11<-10 dB)and 3 dB axial ratio bandwidth are about 66 MHz, 12 MHz, respectively. The measured results fit well with the simulation results obtained from HFSS. This antenna can fully meet the requirement of CNSS. In addition, by using high permittivity ceramic as the substrate, the antenna has the same performances but its scale is reduced to 75% compared with the traditional ones. Such advantages make it proper to practical applications.

Abstract:Aimed at the problem that node importance evaluation of communication network is influenced by multi-factors, an evaluation method of node importance based on betweenness influencing matrix is proposed. In order to achieve an impersonal evaluation result, in the method, based on the influence of the topology structure of network on importance, the node betweenness is taken as a basic parameter to describe the controlling capacity of node to the shortest path. And then the influences of multi-factors such as degree, distance, min-path and other factors are put into the process of calculation to describe the difference in location and connecting branch between the nodes. Then, the difference between the direct and indirect influences by the distance attenuation is given. Finally, in combination with the proposed betweenness calculation based on contribution, the calculation of communication network node importance is done on the basis of the betweenness influencing matrix, thus an objective evaluation on node importance is achieved. The simulation result shows that the method is effective and objective without setting any factor weight.

Abstract:Bismuth layer-structured CaBi2Nb2O9 piezoelectric ceramics are prepared by solid state synthetize process. The effects of sintering temperature on the microstructure, morphology, density and dielectric properties of the composite ceramics are investigated. The phase composition, structure and properties for all ceramics are investigated by X-ray diffraction (XRD), Raman spectra analysis, scanning electron microscopy (SEM) and the temperature dependence of the relative dielectric permittivity. The results show that the pure bismuth layer-structured is obtained for all the specimens. The grains are of highly anisotropic plate-like shape, the grain size is increased with the raising of the sintering temperature, and the density of ceramics gradually is first increased and then decreased. The optimum sintering temperature is 1 150 ℃, and the relative dielectric permittivity of CaBi2Nb2O9 ceramic samples shows that the Curie temperature (Tc) is about 943 ℃.

Abstract:Based on the Lyapunov stability theory and nonlinear dynamic theory, a controller is designed, the control of complete synchronization and anti-phase synchronization between 3-dimensional and 4-dimensional chaotic systems with different structures is implemented, and the two kind of synchronization are respectively proved strictly in mathematics. In this paper, taking a new 3D autonomous system for example, hyper-chaotic system is achieved by introducing an additional state variable to the new 3D chaotic system, thus a complete synchronization and anti-phase synchronization between chaotic systems with different structures and dimensions are investigated. Finally, by the Runge-Kutta scheme numerical simulation and from the simulation analysis of the error system between driving and coupled system, the graph of the errors can show that errors will become zero in short time, the numerical simulation shows the validity of the theoretical analysis and the effectiveness of the proposed method.