Abstract:In order to improve the service safety of aircraft, the concepts of Inherent Safety, Service-safety and Safe-service-envelope for aircraft are put forward. And, the architecture and connotation of the Safe-service-envelope for Aircraft (SSEA) are analyzed. The system of SSEA can be divided into Safe-flight Envelope system and Structural Life Envelope system for aircraft. Then the method to establish those envelopes is investigated, and the SSEA is built up. Besides, the application of the SSEA is discussed. The SSEA is a good development of usage restrictions which are incorporated in airworthy standard for aircraft. Utilizing SSEA in every phase of service, the safety of aircraft in missions and life-span can be greatly improved, and the service-safety for aircraft will also be promoted effectively.

Abstract:For the purpose of improving the training level of one to one air combat and effect of aviation combat, an evaluation of head-on assault tactics in air combat by mathematic modeling is advanced. Via analyzing and decomposing the basic process of head-on assault tactics in air combat, the mathematic model of head-on assault tactics aviation track of air combat is built up and the optimization aviation track of head-on assault tactics in air combat is defined. Using the analysis of grey relation analysis, based on the similarity of the practical aviation track and the optimization aviation track, and integrating the specific requirement of head-on assault tactics for aviation track at critical moment, the evaluation of aviation track of head-on assault tactics in air combat is gained. This method is verified by an example, the result shows that the method can reflect the tactic requirement for the aviation track effectively in the training of air combat and corresponds to reality.

Abstract:The paper summarizes the development of MHD flow control in the world and emphatically introduces three typical experiments: modifying shock wave structure of supersonic inlet; restraining separation of boundary layer; weakening shock wave intensity. The mechanism about MHD flow control is analyzed primarily, i.e. discharge plasma can produce high temperature plasma layer, which will induce new shock wave and become virtual ramp, and thus the former flow filed is changed. The use of applying magnetic field is to control discharge arc direction due to electromagnetic force. Finally, the advantage of MHD flow control is summarized, and according to the comparisons between the foreign and the domestic in research development, the prospect of MHD application and development in aeronautic engineering is performed.

Abstract:The formation process of the main particles in O2 plasma at different initial temperatures is numerically simulated. The changes of concentration of the various main particles at different time are tracked, and the law of influence on concentration of the main charged and of the neutral particles in plasma at the initial temperature is obtained in this paper. The calculation results show that the changing law of concentration of main particle in O2 plasma is similar with the increase of the initial temperature, but the influence on the change trends of concentration of them is not clear. With the time rising, the changes of concentration of e、O、O2、O+ are relatively evident and those of O-，O2-，O2+，O*，O2 * are relatively minor, but in the end they will come to equilibrium in state. The results are of a certain reference value to the theoretical study and practical application of plasma ignition and assisted combustion.

Abstract:To solve the problems that subjective factor is major in test result of test system of aeroengine and the life of aeroengine is wasted because of the slow test seed, an automatic test system is designed. Firstly, the whole project is introduced, the hardware structure of automatic test system is analyzed and the measure circuits such as the high and low pressure rotating speed signals, weak signals T1, T3, T6, etc. are designed. Next, the software flow is analyzed. For the purpose of realizing the determination of test points in the search process, a seek-self searching algorithm in time order is put forward in combination with single factor test method 0.618, the structure and flow of the algorithm are analyzed and the fundamental of the algorithm is illuminated. Finally, the test system is tested using an aeroengine. The test result shows that the design of the hardware structure of the test system is reasonable and logical, the signal collected is accurate, the error is content with the requirement, the design of the software flow is logical, the searching algorithm is fast, accurate and the measure speed is doubled which will save the service life of aeroengine.

Abstract:In order to probe into the flow mechanism in the axial-flow compressor, the nonlinear flow characteristics of the axial-flow compressor are qualitatively analyzed in this paper. Based on the multiparameter Moore-Greitzer brief model in compression systems, both stability and bifurcation of system equilibriums under bifurcation parameters can be achieved conveniently by applying the nonlinear dynamic theory. According to the analysis, the sketch maps for steady and unsteady flow of compressor are plotted in the － bifurcation parameters space in both the symmetrical and asymmetrical flow states. The results show that the nonlinear bifurcation analysis can accurately capture typical post-stall transients under bifurcation parameters. In addition, the stability analysis can be easily used for analyzing the change of stability of system equilibriums. The sketch map can be used in determining the state of axial compressor qualitatively.

Abstract:To the question of threat assessment in ELC plane's control and command system(CCS), a threat assessment method based on compensator intuitionistic fuzzy neuro system（CIFNS）is proposed. By this algorithm the dynamic information is combined with the static information of the targets and the fuzzy discursion is generalized to intuitionistic fuzzy reasoning, simultaneously, the network structure and judgment model of threat assessment based on CIFNS are founded. The corresponding algorithm of network study is proposed .The simulation results demonstrate that the algorithm based on CIFNS has high convergence speed and good adaptability when applied in the evaluation of CCS.

Abstract:Based on the characteristics of amplitude and phase between the main and auxiliary channels, the effects of antenna polarization on Adaptive Side-lobe Canceller under arbitrary polarization interference are analyzed. The polarization difference between the antennas will finally result in the amplitude and phase errors, the most serious errors occur with cross-polarization interference; the cancellation ratio is also the worst. For good performance of Adaptive Side-lobe Canceller, the antenna polarization performance must be designed well besides the channel amplitude and phase.

Abstract:Because of the high moving speed of the radar fuse carrier and the short working range of the fuse, in low latitude fight, the ground clutter is more apt to make the fuse burst ahead of the time. This paper sets up a simulation model of the ground clutter echo based on the net image method, analyzes the characteristic of the video signal of the ground clutter received by the fuse, and puts forward utilizing experience criterion to distinguish useful signal from the ground clutter, and using the narrow bandwidth filter to reject the ground clutter which can easily cause early burst of the fuse. The research result provides a technical basis for raising the anti-jamming performance of the fuse still further in the future, and it is very significant for raising the fight performance of the air defense weapon system.

Abstract:To apply the blind signal separation method to DOA estimation, the blind signal separation (BSS) algorithm based on fast fixed-point independent component analysis is introduced in this paper. By using this algorithm, the estimation of manifold matrix is deduced from the gained separated matrix. We obtain the DOA (direction-of-arrival) of signals from angle scaling based on the projection of the column vector on the real array configuration. The results of the experiment show that this algorithm has good resolution in a low SNR (Signal Noise Ratio) environment compared with the MUSIC (Multiple Signal Classification) algorithm.

Abstract:As to the high Peak to Average Power Ratio (PAPR) issue in OFDM system, the paper has proposed a clipping algorithm based on the Particle Swarm Optimization (PSO).The algorithm takes advantage of the splendid searching ability of the PSO to calculate the best threshold and takes advantages of strong controlling ability and easy implementation of the clipping to clip the signal sequences. It takes the steps of iterative searching, clipping, filtering etc. to search the best particle, i.e. the excellent threshold to obtain the lowest PAPR with the precondition of the set CCDF, achieving the target of reducing the system PAPR. It presents comparisons of BER and CCDF between the linearly decreasing weight (LDW) and fixed inertia weight. The simulations show that, compared with the simple clipping algorithm, by using the proposed algorithm no extra BER is brought but the target of reducing PAPR in the low SNR area is achieved, so the proposed algorithm is of vital significance to improving the performance of the whole system.

Abstract:A MoM-PO hybrid method is proposed to solve some unusual electromagnetic (EM) radiation problems those cannot be solved by the traditional EM computation methods. By using this method, the antennas are divided into two regions, which are meshed by trigonal patches, and then RWG basis functions are defined in two regions. The methods of moment (MoM) and Physical Optics (PO) are used respectively in two regions, and the matrix equations are obtained. By solving equations, current distributing can be obtained. The numeration results show that MoM-PO hybrid method is more accurate than the traditional methods. The computation work done by using MoM-PO is greatly decreased compared with that done by using MoM. Simultaneously the computational efficiency is increased without losing validity. It is an effective EM numerical method.

Abstract:A novel project of simulation for distance protection is presented in this paper. The simulation module library in the simulator system of microcomputer protection is established by adopting the Laboratory Virtual Instrument Engineering Workbench (LabVIEW) and MATLAB program, the common modules include boot module, algorithm module and logic processing module etc. The operation logic of microcomputer protection is implemented by LabVIEW. Spot experiments show that this idea suffices for types of relay protection simulation. The method has such advantages as convenient operation, clearly and directly observable. And it can be implemented in teaching, training and be used for ascertaining the cause of the maloperation or misoperation of protective relaying in troubles.

Abstract:After the third party has captured and detected the frequency hopping (FH) communication signals, the lack of the priori knowledge leads to that the classic supervised learning algorithm is infeasible for separating HF signals. Even if, nowadays, many unsupervised algorithms are adopted there are still that the cluster number needs referring and multiple classification parameters separation by steps carries on the validity judging and filtering according to the priori knowledge. For the difficulties met in the course of the separation of FH signals detected in electronic support measures, we make use of the performance of the statistical learning theory (SLT), which is higher than that of the others in the small sample learning and the nonlinear classification to put forward unsupervised and semi-supervised learning algorithms based on SLT, by using which FH signals got by the third party are well classified. This research provides a kind of classification method that is of higher applicable robustness and higher accuracy rate for signals separation in FH communication reconnaissance.

Abstract:According to the theory that the independence is equivalent to the uncorrelation, a description of joint probability distribution of finite discrete random variable is found. Through extending the values of two-state to that of multi-state, when two random variables' marginal distributions and right high steps correlative coefficients are given, two dimensional joint probability row can be got to make independence and uncorrelation have an integrated description and expressive form.. This method is verified through simulations. By the way, the expression obtained is applied to the analysis of data channel communications. The in-out information coupling is described by channel's port correlative coefficients, which is a fine supplement to the information theory. This method is corresponding with information theory's average mutual information and data processing theorem, and a perfect formula and ideal characteristics are obtained.

Abstract:Firstly, the methodology for building up the model for the static strength and fatigue strength reliability of cylindrical helical spring is analyzed, and the computational formulas and distributions of the stress and strength are derived. Secondly, with the individual characteristics of mechanical optimization design and reliability, taking the spring's mass as the objective function and based on the traditional constraints and reliability constraints of the spring, the mathematic model of reliability optimum design of cylindrical helical spring is established to make full use of the materials and consider the reliability of the part. At last, combing the optimal tools with the optimization model, the proposed method is applied to a practical example, the results of the reliability optimization and the traditional optimization are compared and analyzed, which show that the proposed method of the reliability optimization designing is practical, reliable and can satisfy the demands of designing to the full extent.

Abstract:In order to study the impact of decreasing illumination on distances cognition in dusk, real road experiments are performed. A certain quantity of randomly selected drivers perceives absolute space distances and relative ones in different environment illumination and depth distance in the real road. The cognition values, acquire distribution mode and character values are analyzed by using the statistical method. A mathematic model of cognition is built by regression and the cognition quantitative differences between day and dusk are compared. The results show that the cognitive values continuously augment with the environment illumination decreasing and there is a cubic expression relation between them. And the distance cognition value in dusk is larger than that in day under the same depth distance.

Abstract:Advance-retreat method is a one-dimension searching algorithm of the optimal theory and a method for single peak function, which is very simple and in common use. The main work of this paper aims at the problem of convergence and convergent speed stated as follows. Firstly, the theory and process of advance-retreat method is discussed. Secondly, an improved advance-retreat method is proposed for conquering the drawback that the original method is not convergent at some conditions. By the improved method, the alternative step changes to a function of forehead step and iterative time. Thirdly, by a strict theoretical derivation the correctness of the method is proved. Fourthly, the effectiveness of the method is verified by simulation results. Finally, the results show that the convergence speed of the advance-retreat method is changeable with the different initial parameters and by using the improved advance-retreat method, the convergence is guaranteed at any case at the cost of decreasing the convergence speed.

Abstract:In order to solve the problem that conflict evidences can not be combined with Dempster's combination rule, a weights redistribution approach to evidence combination is proposed. In this approach the disaccord of evidences and the ambiguity of evidence are measured by distance and ambiguity measure respectively. Based on this, this paper expands the weights determination principles proposed in \[7\]. Then, new weights determination algorithm and evidence combination approach are suggested, and the result in \[7\] is improved.