Abstract:Aeroengine blades bear the common act of thermal load, centrifugal load and aerodynamic load under conditions of working. These loads will not only change the mechanical performances of the blade material, but also make the natural frequency and mode shapes of the blade different from the stationary ones at room temperature. All the factors are considered accurately by using finite elements analysis (FEA) software ANSYS during modal analysis. The working temperature of blades is obtained from thermal analysis first, and then is coupled to structure elements to calculate the thermal stress of the blade by using structural analysis. After obtaining the thermal stress, the FEA is restarted by applying centrifugal load and aerodynamic load to study multiple stresses of the blade. At last, taking the multiple stresses as prestressing force, natural frequency and mode shapes of the blade are analyzed under conditions of working. The paper synthesizes both temperature and stress influence on blade modal, and a modal analysis method of aeroengine blade is obtained based on thermalstructure coupling prestressing force. And this method has an important theoretical meaning and engineering practical value.

Abstract:The numerical simulation is carried out to investigate the cold fluid field characteristics of small pylonaided gaseous fuel injection with six different port shapes in the supersonic combustion. The result shows that pylon can raise mixing efficiency and fuel penetration height without big total pressure loss. The pylons combined with square, circular and triangle port nearly have the same flow characteristics, but with diamond port and jet of rectangle 10:1 can get remarkable mixing enhancement. A high aspect ratio injector can get the advantages of low pressure and high vertical magnitude depression behind the pylon, which is much better than the no pylon cases. Through the investigation, a better understanding of the characteristics of flow field with pylonaided fuel injection is made, and the investigation supplies optimization of injector with basis.

Abstract:In order to make full use of the scarce spectrum resources, and solve the "black out" problem of near space communication, a nonuniform plasma sheath is built by selecting a Gauss distribution model combined with the millimeter wave atmospheric window with high transmittance in the atmosphere to study the influence on attenuation of millimeter wave atmosphere window in the process of transmittance in the atmosphere on account of frequency changes subjected to the collision between attack angles and plasma sheath on condition that there are additional different intensity magnetic fields and on no condition. The simulation results show that the magnetic field with different intensities added on the plasma sheath can change the attenuation value of the millimeter wave atmospheric window, but can not change the transmission law of the millimeter wave atmospheric window. The external magnetic field does not necessarily improve the transmission performance of the millimeter wave atmospheric window, but also needs to consider the resonance frequency of the plasma sheath and the millimeter wave window. The results provide effective theoretical data support for the establishment of near space communication platform.

Abstract:Aimed at the problems that the maneuvering targets are restricted by some known physical constraints, a multiple model (MM) method is adopted. In accordance with various motion behavior of maneuvering targets, a composed multimodel method is used to approximate. And in the light of the known physical constrains of targets, a moving horizon estimation (MHE) is used to process, and a priori information of state estimation is utilized to promote the precision of estimation. To incorporate the MM method into MHE framework, through an estimation evolution formula and the modified update formula for the estimation covariance matrix, a MMMHE optimization and algorithm are finally nally presented for the tracking problem. The simulation result shows that compared with the adaptive Kalman filter lter (AKF) and the interacting multiple model (IMM) method, this algorithm can perform well a task of tracking maneuvering targets (especially for the physically constrained motion condition)

Abstract:A target assignment method, interaction mechanism of the genetic algorithm (GA) combined with the discrete particle swarm optimization (DPSO) is put forward based on cultural algorithm (CA). According to the characteristics of MAV/UAV target assignment problem, the interaction mechanism between GA and DPSO is established based on the basic framework of CA. The proposed algorithm improves the search ability and overcomes easily to run into partial optimization. The algorithm can solve the MAV/UAV cooperation mission assignment problem effectively. The simulation results show that the proposed algorithm is better than GA and DPSO. The algorithm has a good convergence rate and can find the best assignment scheme fleetly.

Abstract:In order to improve the accuracyof confirmingrunway orientation methodbased on usability factor and eliminate theerrors that exist in the previous calculation method which is based on the wind rose according to wind statistics of velocity and direction,a new model is proposed, in which wind observation data is used directly to calculate the crosswind component suffered by runway and optimal runway orientation is confirmed by comparing wind data with the allowable crosswind componentand counting the number that meets the requirements. Simulation model by MATLAB program language is established and can calculate and confirm runway orientation directly by observation data. Besides, usability factor in certain runway orientation is calculated by modified methodand compared with the results of previous method and other numerical simulation method, then the accuracy and reliability is ascertained.

Abstract:The traditional Analytic Hierarchy Process (AHP) is always adopting 1~9 criterion quantitativeability to judge matrix. By so doing, the criterion is poor in consistency, and strong in manmade subjective. This paper proposes an index scale to improve AHP, and establishes a fuzzy comprehensive evaluation model to evaluate the jamming effectiveness on radar seeker. The paper builds up an evaluation index system suitable to the radar seeker according to the work principle and function features. The membership function is defined with fuzzy comprehensive evaluation, and the weight vector is fixed with AHP of index system. Finally, noise jamming is chosen as an example to verity the effectiveness of the model. The results show that the consistency ratio of fuzzy Analytic Hierarchy Process with index scale is zero, thus reducing the influence of subjective factor and increasing veracity and reliability of effectiveness evaluation.

Abstract:Aimed at the shortcomings of the airborne radar's stealth performance evaluation from the Schleher interception factor, this paper, in two aspects of the stealth performances of radar radiation signals and radiation strategies, analyzes in detail eight factors which affect the radar RF stealth performance, and constructs an evaluation index system of the RF stealth performance of airborne radars. In the light of the problems of uncertainty and ambiguity existing in some indexes, the index system is comprehensively and quantitatively assessed by using a gray analytic hierarchy process (GAHP) method, and the stealth performances of three types of airborne radars are evaluated. The simulation results show that the method can evaluate the RF stealth performance of airborne radars effectively.

Abstract:Aimed at the different response of the main and auxiliary antennas to the Crosspolarized interference in SLB，a new question that releasing mainlobe Crosspolarized interference to the radar system with SLB may arouse SLB system works and the target must be hidden is proposed. The model is set up and the effect of the interference is analyzed. The simulation results show that whether deceptive jamming or blanket jamming to the main antenna, mainlobe Crosspolarized interference can change the responses of signals from main and auxiliary antennas. The energy received by the main antenna decreases rapidly, and the energy received by the auxiliary antenna is stronger than that of the main antenna, thus triggering off SLB system to work. And simultaneously the main antenna channel closes and the target vanishes.

Abstract:MIMOOFDM system channel estimation is a key of coherent demodulation for signal receiver. Aimed at the fact that MIMOOFDM system is faced with a nongauss noise, combined with the improved proposal distribution, an improved hybrid annealed particle filter algorithm is used to estimate the MIMOOFDM channel. On the basis of building the statespace model of system and analyzing the proposal distribution of hybrid annealed, the fuzzy inference system is used to get dynamic hybrid annealed parameters, and the improved hybrid annealed particle filter algorithm is obtained. The improved hybrid annealed particle filter algorithm is used to estimate the channel of the MIMOOFDM system. In this process, the bit error rate (BER), the normalized mean square error (NMSE) and the algorithm complexity of the channel estimation are simulated. The simulation results show that compared with the extended Kalman filter, the particle filter and hybrid annealed particle filter algorithm, the improved hybrid annealed particle filter algorithm can reduce effectively the bite error rate of system in nongauss channel, and at the same time, this can also improve the performance of system by using a small amount of sampled particles.

Abstract:Compared with the standard BP decoding, the BP decoding based on LLR reduces the computation burden, but is still complex. As a result, this may consume lots of hardware resources. To solve this problem, this article proposes an improved LLRBP decoding algorithm with dynamic bit node selection. According to the recursion of extrinsic messages and the satisfaction of parity equation, the part of nodes whose belief is the lowest is selected dynamically to participate in next iteration and update their extrinsic message. At the same time, the other variable nodes don't need to update their extrinsic messages in next iteration. The simulation result shows that the loss of the performance of advanced algorithm in signaltonoise is 0.1 dB and 0.07 dB compared with standard LLRBP decoding algorithm, when the codelength is 1 024 and 2 048 at 104 biterror rate and at 0.5 code rate.

Abstract:Aimed at the problems that spectrum allocation based on traditional ant colony algorithm in cognitive radio is long in search time and is low in efficiency on pheromone update，a new cognitive radio allocation scheme based on polymorphic ant colony algorithm is proposed in this paper. The scheme changes the regulation mechanism of the single pheromone in the traditional ant colony algorithm, introduces scouts to the algorithm, and marks information in higher benefit value path. And the scheme takes benefit value as a standard to set the index of polymorphic ant colony algorithm. In addition, the polymorphism rule is applied in path selecting and pheromone updating. Finally, Polymorphic Ant Colony Algorithm (PACA) is compared with traditional Ant Colony Algorithm (ACA) on MaxSumReward and MaxProportionalFair. The experiment results show that the proposed spectrum allocation algorithm has a high efficiency and superiority.

Abstract:To cope with the problem that the acquisition probability of jamming signals in the TACAN receiver is too low, a new jamming model based on the denial environment is proposed in this paper. Firstly, the influence of noise on the computed results is studied. Secondly, the deception jamming power changed along with distance between the airborne and the jammer is analyzed. Then, the relative acquisition probability of the deception signals changed along with the JSR (jam to signal ratio) is analyzed. Finally, the effectiveness of the jamming model is proved by simulation.

Abstract:Aimed at the NPhard problem in the optimal test selection (OTS), this paper proposes to utilize the genetic simulated annealing algorithm for solving. To solve the problems that the large timeconsuming of searching process and the inefficient crossover operation exist in GASA algorithm, the paper firstly uses a nonlinear accelerating fitness function to improve the searching speed, and simultaneously compares genes before crossover operation to reject the invalid cross operation, so the effectiveness of the algorithm is improved. And the proposed algorithm is applied in the superheterodyne receiver system. The simulation results show that the iterative numbers of convergence are less 13.3% in OGASA than that in GASA. Meanwhile, the OGASA algorithm can meet the acquirements of testability and fault isolation rate. The testing cost of the algorithm is less than that of others. So the OGASA algorithm is more effective in solving OTS problem.

Abstract:Aimed at some problems that the resource allocation and task with high priority are distributed with assets first, and task with low priority fails to get enough resource to accomplish a task, a matching strategy is proposed. This new method has two parts. One is a Nbest algorithm based on decision space partitioning theory, and this can provide decision makers with several alternative plans to overcome the limit of a single plan. The other is a tradeoff strategy combined with N best plans to get the best solution, thus realizing the whole situation's optimization. The experiment results show that the Nbest based strategy can improve the whole situation's task accuracy.

Abstract:Some properties on primary automata are studied in this paper. Firstly, the endomorphism of the primary automaton is dealt with. The paper proves that if all the primary automata are S(orG)automaton, so is . Secondly, the union of the strongly connected automata is proved to be Gautomaton. Finally, the definition of canonical automata is extent to finite automata by the minimal generated set. Also, the definition of generalized canonical automata is given and the sufficient conditions are provided.

Abstract:Aimed at the problem that conflict coefficient K fails to effectively measure the degree of conflict between evidences in classical evidence theory, a new evidence conflict representation method is proposed. The use of the new method is as follows: Through the introduction of pignistic distance, and taking the probability of conflict coefficient K as a point on the plane rectangular coordinate system, the distance from this point to the original point on coordinates is a measurement standard for degrees of conflict between evidences. On the basis of the new measurement method, an improved combination rule is given. This algorithm is utilized to take the new conflict coefficient as a correction factor to revise the combination result when there is in conflict with evidence, and to perform the composition of results by adopting the composition rules of DS when there is in nonconflict with evidence. The simulation results show that the new measurement method and the improved combination rule are effective.

Abstract:Aimed at the problems that at present the anomaly detection and the residual useful lifetime (RUL) prediction exist in the integrated study, a RUL prediction model, i.e. a dynamic transition of the degradation model,is presented based on IMM algorithm. The presented model overcomes the disadvantages of the tradition models that the anomaly points at single stage are on no consideration by the prediction model, and can predict the RUL in real time. The numeric results show that the presented model can detect anomaly accurately, can reduce the uncertainty of RUL probability distribution, can improve the precision in RUL prediction, and can provide a basis for a decision making in completing maintenance work in accordance with the concret conditions.

Abstract:A chargedparticle threedimensional momentum mapping analyzer is proposed in this paper. The characteristics are as follows: An axial uniform magnetic field is introduced to constraint the lateral divergence of the charged particles in the system, thus making an analyzer have a comparatively larger angle of particles collection. Positionsensitive detector (PSD) serves as the charged particle receiver, recording both the position and time information of the charged particles. Based on the motion equation of electron in magnetic field, the operating principle is analyzed, and the mapping reconstruction relation among the initial threedimensional momentum information and the position and time information of the charged particles on the detector is given. The superiority over the magneticfieldfree technique is also discussed, and simultaneously the optimum setting of the introduced axial magnetic field is given.

Abstract:In the light of the shortcomings that particle swarm optimization (PSO) algorithm is poor in locally searching ability in the process of optimization, and/or is slow in speed of convergence in later period, a sequential quadratic programming (SQP) integrated particle swarm optimization algorithm (PSOSQP) is presented. The proposed method not only keeps the characteristics of globally converging of PSO, but also compensates SQP for the effective local search ability, and simultaneously obtains the global optimal result quickly. The method applied to the classic test function can get the optimal solution of high precision. An optimization design of structural reliability for gear reducer is made，and its mathematical model is built up based on PSOSQP. The results show that this method is reasonable and effective in solving the problems of reliability optimal design．