Abstract:Euler-Lagrange two-phase flow model is used to simulate the inner flow field of the tail nozzle pipe under the condition of different high accelerations and particle diameters. At the aspect of the calculation of heat transfer and temperature field, the three heat transferring modes and the respects of each interior area of the nozzle was considered, calculate and analyze the temperature field of the nozzle's three-dimensional integral heat structure. The results show that, the change of temperature grads in the nozzle's inner wall is prominence in the nozzle macrocosm; the gas temperature of the nozzle tail is higher than the pure gas phase with particles and high acceleration, but it descend rapidly in the thermal protection layer; the radiation heat temperature of the particle in different diameter and high acceleration is prominence.

Abstract:The current method of runway width design is based on requirement of airplane, and don't consider how to reduce the blockage probability of runway when runway attacked by enemies. So the paper analyses the process of blockage runway by sub-munitions missile, and build model of blockage runway about runway width. Then through analysis the process and model，the major factors that will influence the blockage probability of runway is got. Based on relations between influence factors and blockage probability，the relationship between the blockage probability of runway and runway width is got under special condition。At last, the paper contrasts the economy of adding runway width and reducing the blockage probability of runway, then puts forward the concept applied defense factors in runway design

Abstract:System safety index in aircraft level is analyzed to solve the problem of index selection and quantization in this paper. The flaws of the safety parameter application in system safety analysis are indicated through the analysis and comparison of domestic safety parameters. Based on characteristic of system safety, the requirment and dimensionality of index are proposed. Using the experience on system safety assessment of foreign countries for reference, and considering reliability, methods to select and quantify safety index in aircraft level is started, and one example is given to illustrate when and how to apply safety index. Research shows, combining safety and reliability, selecting indexes having effect on aircraft safety to conduct system safety assessment in aircraft level, can be a practical and reasonable way to solve problems of traditional safety parameters such as the difficulty of quantification and inapplicability.

Abstract:The survivability has been one of the significant technical index formilitary aircraft, and the primary purpose of calculation on vulnerability for aircraft is to evaluate survivability and provide theoretical guidance for enhancement of survivability. This contention about this paper is to be erected power field of focusing warhead, considering demolish of waves for explosions and piercing of global and quadrate devastating element, looking upon static dispersion angle as a design parameter, through simulating flight of the fragment of the focusing warhead in modern airwar. This paper studies vulnerability of multiple hits different devastating elements in power filed of focusing war-head. An example for calculation is showed, compared with conventional warhead that a focusing warhead can make a higher damaging probability for aircraft.

Abstract:Considering the actual during a flight operation that flight flow and airport capacity has dynamic feature, the concept of sliding time window has been used in airport flight flow optimization allocation problem, and puts forward a method of dynamic optimization allocation of airport flow based on sliding time window. The principle of optimization allocation of airport flow based on sliding time window is discussed in this paper, this method use ongoing dynamic optimization allocation instead of static one-time optimization allocation to get optimal flow allocation scheme of current time period in real time, this method could provide decision support for tactic airport flow management. The experimental results shows this method could achieve real time optimization allocation purpose well in dynamic environment, while static method of optimization allocation could not be used in dynamic environment, verified the feasibility and efficiency of this method.

Abstract:Based on the characteristic of aviation nozzle-ejector's wake-flow field,the modeling of study the flow in the nozzle-ejector and wake-flow field is conducted through numerical simulation, the whole flow field’s basic parameter with the model is got.Analyzing the flow field of the nozzle-ejector’s exhaust plane and validating the model through the experiment of certain aero-engine,the result indicates that the model can reflect the wake-flow field practically. At last,the thrust of every nozzle-ejector is calculated by the way of area element and the thrust loss of the lobe nozzle-ejector relative to the 1st nozzle-ejector is got.

Abstract:The template contrast method is abated because of that the difference between different radiant points trails off. From the point of view of engineering application, this paper presents a specific emitter identification method. In order to identify the difference between different radiant points, first the Fisher's discriminate ratio is employed to select the effective features, and then the principle component analysis is done to reduce the feature dimension. Finally, the support vector machine is used to perform the identification. The simulation result shows that the method can give attention to both accuracy and speed of identification simultaneously, and is of better application value in the identification of different radiant points.

Abstract:An effective location algorithm for near space radar network based on angle information is discussed in this paper. The location model is established according to the geometric relationship between target and radar station. The nonlinear equations about azimuth and elevation are transformed into linear equations. Least square algorithm is used to get the initial value of the target location. Then the location issue is transformed into a non-constrained optimization issue by the maximum likelihood method. Believable field method is used to solve the optimization issue. The detailed process of the algorithm is also presented. The location accuracy of the algorithm is analyzed and the geometric dilution of precision (GDOP) is obtained. The simulation results show that the use of the algorithm can effectively improve the location precision of angle information and the performance of the proposed method is better than that of the least square method. The research result of this paper provides a theoretical basis for the detecting and tracking of the near space radar network.

Abstract:Aimed at the problems that the ballistic missile is quick in speed, the RCS of radar is small and it is very difficult for the early-warning radar to track the whole early-warning course, the improved GM (1, 1) model is advanced to predict the position information of the ballistic missile. The smooth degree of original date sequence, the conformation method of background value and the beginning condition are improved in the new model, at the same time, an improved new model is built and the modeling steps are put forward. The simulation result shows that compared with the traditional GM (1,1) model, the prediction precision of the improved model is greatly improved and the application area is extended, so it can be used to predict the position information of the ballistic missile.

Abstract:Aimed at the defect that radar detection performance can't be fully displayed by using surface rendering, an algorithm of radar detection probability visualization using directive volume rendering technique based on 3D texture is proposed. According to the characteristics of radar detection data such as uneven distribution and inconsistent significance, design principles of the transfer function is given, and then the analytical formula is presented based on the principles. 3D radar volumetric data is calculated based on the advanced propagation model, and the probability is classified by assigning optical imaging parameters through color transfer function. The angle on the condition of the worst visual effect is computed through mathematic model, and experiments have validated that method that replaces real-time slicing calculation by prepared three schemes is feasible. Simulation results show that, compared with the surface rendering, the display of radar detection whole coverage by new version is clear and the internal data can be easily exhibited by cutaway view.

Abstract:By statistically analyzing the information of PHM items which have been already accomplished in various countries, the original data of the technology readiness level and comparative schedule delay are gained. By the method of translation into linear regression, the regress functions of technology readiness level with average comparative schedule delay, and technology readiness level with maximal comparative schedule delay are established. On the assumption that the comparative schedule delay is obedient to normal distribution, the probability relationship of schedule risk with technology readiness level is established. Then, the relational graph of schedule risk and schedule allowance with technology readiness level is drawn. The research shows that when PHM technology readiness level achieves seventh grade, the schedule risk is within twenty percent, which is of an acceptable range.

Abstract:The dimension of probe and the exciting parameters have an obvious influence on the result of pulsed eddy current (PEC) nondestructive testing, the capability of the PEC inspection system can be improved by optimizing these parameters. Based on the analysis of the principle of PEC, the PEC model is established by ANSYS finite element simulation software to analyze the influence of the variation of probe dimension on the eddy current decay law and that of the change of exciting frequency and duty cycle on the detecting sensitivity. The simulation results show that the attenuation of the eddy current slows down with the increase of exciting coil length, and the attenuation of the eddy current quickens with the increase of exciting coil width and highness. The influence of exciting frequency and duty cycle on the detecting sensitivity of defect has a relationship with the specimen thickness, the exciting frequency should be appropriately decreased and the duty cycle increased in inspecting thick specimen. Finally, the results of simulation are testified by experiment methods, the agreement between simulation and experiment shows the correctness of simulation.

Abstract:An efficient joint transmit and receive antenna selection method is proposed for rank-deficient MIMO channels. The capacity performance of the rank-deficient channel matrix is analyzed and the conclusion is reached that a judicious selection of transmit antennas can even increase the system capacity. To retrieve the full-rank channel matrix from the original rank-deficient channel matrix and to maintain the channel capacity as much as possible, the transmit antenna selection is then completed first. The orthogonal subspace projection of the original rank-deficient channel matrix is exploited to reduce the computational complexity of the transmit antenna selection. For the receive antenna selection, the recently proposed maximal-volume-based fast receive antenna selection algorithm is used and extended to achieve a joint transmit and receive antenna selection， in which the maximum-volume sub-matrix of the original channel matrix is directly and rapidly searched. Due to its global-search capability, a better capacity performance is realized under the condition of moderate to high SNRs than using the existing 'local-search' and greedy antenna selection methods and almost the same capacity performance as the optimal selection method based on a 2D exhaustive search is attained. Furthermore, due to the use of the rank-one updating procedure combined with a reduced number of iteration steps, the computational load of our joint transmit and receive antenna selection method fits for real-time applications. Numerical results are presented to verify the validity of the proposed method.

Abstract:Design of an effective detection scheme for high-speed frequency-hopping signal is the groundwork for Link-16 signal detection. This paper presents a detection scheme based on multichannel radiometer structure. The communication mechanism and high-speed FH characteristic of Link-16 are analyzed in detail. Then, to surmount the deficiencies caused by directly applying multichannel radiometer in Link-16, this paper designs a new adaptive threshold algorithm and a new judicative rule, presents a feasible modification rule for the channel detection results and finally based on multichannel radiometer achieves the Link-16 signal detection. The simulation results of this scheme show that the threshold algorithm of this detection scheme has a good adaptability to the amplitude of input signal, which can be used to effectively solve the problem of Link-16 signal detection under low SNR and to make the channel detection results independent of the background noise.

Abstract:Telecommunication Engineering Institute, Air Force Engineering University, Xi′an 710077, China

Abstract:Airborne Multiple-Input Multiple-out (MIMO) SAR system can be used for achieving the image with high resolution, but the inevitable problem of motion compensation must be solved. The MIMO-SAR system with several sub-bands is studied here. Firstly, a model of motion error for MIMO-SAR system is established and a detailed analysis of it is presented. Then an extended MIMO-SAR Range Migration Algorithm (RMA) integrating with motion compensation is proposed. Range Cell Migration Correction (RCMC) and azimuth focus are separated by improved Stolt-mapping, and the motion error is corrected through two steps of compensation. Finally, sub-bands are combined into a whole band in spatial-frequency domain to obtain a high range resolution. Imaging simulations for point-targets and plane-targets with this algorithm are performed to verify the validity of such algorithm.

Abstract:Aimed at the characteristics of cognitive Ad hoc network, a corresponding network model is established and a distributed power control algorithm based on convex optimization theory is proposed. Based on the analysis of system interference, by taking the network utility maximization as the target and transmit power of cognitive user as the solution object, a general math optimized model is formulated. Under the guidance of convex optimization theory, the model is transformed into a convex optimized model by introducing auxiliary variable and substituting variables. Lagrangian dual decomposition technique is used to solve the convex optimized model and the distributed power iterative algorithm is obtained. The simulation shows that under the premise of meeting the system constraints, the use of the proposed algorithm can obtain better system performances than that of other algorithms.

Abstract:The positions of dot light source of incident spherical wave and reference spherical wave are directly related to the selection of CCD, optics, analysis of interferogram and the evaluate accuracy of a testing system for aspheric surface. In order to predefine the best position of sources of incident spherical wave and reference spherical wave, a new method is adopted to fix dot light source of spherical wave by calculating and analyzing the fringe density. By using the above method, the best source position of spherical wave not only can be predefined but also the interferogram be fully analyzed, simultaneously the specific strategies of selecting CCD and optics can be determined. The results of the research also can be used as a theoretical guidance debugging in the process of testing aspheric surface.

Abstract:The support cost is the main part of LCC(life cycle cost) of weapon equipment, For the purpose of reasonably forecasting the support cost of weapon equipment, the paper analyses the constitution of equipment support cost and its affecting factors. Given the limitation, complexity and nonlinearity of date quantity of equipment support cost, the forecasting precision of single model is low. So the paper puts forward a combined forecasting model based on grey system theory and BP neural network model to forecast the support cost which are based on nonlinear time series, which put the advantage that grey system theory can easily do the small sample data together with the advantage that BP neural network model can solve the complex and nonlinear problem. A simulation example proves that the total error of the combined model's forecasting result is smaller than that of single model's forecasting result. This can largely improve the forecasting precision of equipment support cost.