Abstract:To investigate the influence of plasma actuation on film cooling efficiency, a numerical study of the distributions of the flow fields and cooling efficiency is employed with different placement of plasma actuation pole in several ratios. And their distributions are compared with the distributions of baseline holes to reveal the good effects of the plasma actuation on the film cooling performance. The results show that the plasma actuation can attract the cooling flow to form better coverage on the hot side, thus improving the film cooling efficiency. The improvement of the film cooling efficiency is significant at lower blowing ratio with shorter distance between the plasma actuation pole and the outlet of film hole.

Abstract:By solving two-dimensional Reynolds-Averaged Navier-Stokes equation and using two equation SST turbulent models, the two dimensional flow field of an airship is simulated. The influence of airship envelop vibration on the flow field is analyzed. The influence on flow separation and drag of different vibration amplitude, frequency and wave length is analyzed on the hypothesis that a wave is promulgating in the flow direction on the airship envelop upper surface. The results indicate that the vibration can make the airship flow field dramatically change: with fixed vibration amplitude and frequency, reducing wave length will result in flow separation and drag coefficient increase; with fixed wave length and frequency, increasing amplitude will have the same effect; with fixed wave length and amplitude, increasing frequency will induce flow separation and drag coefficient decrease because of the enhancement of unsteady effect. Besides, it also demonstrates that certain form of vibration with suitable vibration correlation parameters may restrain flow separation and reduce drag, which would be an approach for decreasing drag of airship.

Abstract:Outliers and noise will cause difficulties during processing and using flight data. This paper proposes an outlier detection method based on histogram analysis of wavelet transform residuals, which can locate outliers in time-domain precisely, and can recognize little outliers in succession. Then according to the characteristics of flight data noise and its denoising demand, edge detection is introduced and a two-step denoising method including dyadic wavelet coefficients product and wavelet shrinkage is put forward, which can keep the characteristic of extremum points very well. Finally the experiment shows that the method presented in this paper is effective on flight data cleaning, with which outliers can be recognized exactly and denoising effect is good. The method can also be used for reference in processing other similar data.

Abstract:The software simulation of aviation wireless navigation system is the basis of the simulation of flight check, and also is an important component of comprehensive simulation system of air force communication system. The characteristics of aviation wireless navigation system and of the simulation of it are analyzed, and simultaneously the characteristics of Matlab/Simulink in modeling simulation are analyzed. At the same time, its extensibility and reusability representing in the compatibility with HLA are also analyzed. An initiative research of the simulation of aviation wireless navigation system is made by using Matlab/Simulink. The Simulink models of the subsystems of ground course beacon, antenna distribution network, spatial signal synthesis and receiver onboard subsystems of Instrument Landing System are built and the correct signal wave-form produced by the simulation system is obtained. A resolution scheme about joining the Simulink model of Instrument Landing System into the comprehensive simulation system federation of air force communication system is put forward.

Abstract:The region passive locating system, named Beidou, nowadays is under extensive research, the inaccuracy of receiver, environmental noise, man-made interference and other factors will cause false data in the relevant measuring arrays. The difference between these data and the normal value in terms of quantity is larger and exceeds the allowed range of error, which will obviously affect the Kalman filtering process and cause the decrease of the position precision. All these will lead to instability of the system and even the disperse of filtering. This paper presents an improved algorithm, the principle of which is to reject the dynamic fault tolerant by using Kalman filter. This method upgrades the tracing ability of the filter under the airborne environment. The real-time character is improved because of the decrease in the dimension numbers of the state equation. Verified from the trying out data, the locating precision of the system can reach up to 92 meters, filtered by the algorithm, thus it can meet the general needs of the users in the air.

Abstract:In order to solve the problem that the efficiency and precision are low if air situation is displayed and reported by grid coordinates(nine-nine and five-five grid), the typical application of the Gauss-Kruger projection in air defense command and control system is studied. The station's core horizontal orthogonal coordinates converting model can be founded by transforming the geography coordinates to Gauss-Kruger coordinates, working out the meridian convergence angle and setting up converting coordinates matrix. And then by calculating the educed unitary quadratic equation, the target station vertical coordinates are worked out. The Analysis shows that the model can be used to avoid complex coordinate's transformation computation, obtain higher precision than before, and by using which, Gauss-Kruger projection can be applied to describing air situation, displaying the firing command and converting the station's core horizontal orthogonal coordinates.

Abstract:With the development of information technology, intelligent information technology has been widely used. And the intelligent algorithms are largely applied to the multi-sensors information fusion field. The three commonly used basic methods, i.e. weighted method, modified method and related realm method, work only aiming at the case of two partial joints, but do not work in the case of rather large scale system target association problems. In view of the target association problem in the air defense system, this paper presents a heredity-based multi-sensors multi-tracks associated algorithm by using which the multi-sensors multi-tracks associated problem is transformed into a multi-dimensional allocation problem, and gives out the concrete model, algorithm and solution steps for solving the problem. Simulation experiments are done to testify the correctness and validity of this algorithm, and the results show that the algorithm is of guiding significance for the realization of the application system.

Abstract:To solve the ineffective performance of passive array tracking, this paper presents an interacting multiple model particle filter algorithm (IMM-PF) by combining the interacting multiple model with the particle filter method together. In using this algorithm, the structure of multiple models is adopted to track arbitrary maneuvering of the target, and at the same time particle filter method is employed in each model to deal with the nonlinear/non-Gaussian problems. After interaction and particle filtering, particles in each model with the fixed number are re-sampled to reduce the degeneracy of filtering. First, in the interaction stage, the particles corresponding to each model are input and interacting. Then, estimation resample is obtained by picking out N sampling points in the filtering stage, thereby the estimation output and the related function are gained. In the combination stage, the posteriori probability density functions of the state vectors are obtained, by combining the probability density functions of the different modes taking into account the mode probabilities. In the simulations, by comparison with the general interacting multiple model, the results demonstrate the correctness and efficiency of this new filtering method.

Abstract:Aimed at the air-raid target threat，the index system of the threat evaluation, quantified and indexed by the fuzzy membership function, is given based on the guideline of the threat evaluation. Usually in threat evaluation, only the information provided by the maximum is taken into account and the general values are ignored, which will bring distortion into existence. So, in this situation, it is more meaningful and significant to adopt interval-number in expression. In view of the judgment problem of the air-raid target threat, the criterion for the judgment of the air-raid target threat is analyzed and the main factors effecting on the target threat are given based on this. Then, by combining the interval number with the Grey relationship grade theory, a new multi-objective decision-making model is constructed and applied to the threat sequence of the air-raid target, which can more accurately reflect the influence of target maneuver on threat degree. In this way, the non-chief factors in the system are also taken into account，which makes the threat evaluation closer to the actual combat. Finally the model is applied to the air-raid target threat sequence, and the example shows that this method is feasible.

Abstract:As the key technique of the smart antenna, the beam-forming algorithm has enjoyed widespread popularity. In order to overcome the problem that the convergence speed of the RVSSLMS algorithm is slower though the realization of it is simpler and easier, meanwhile, the RLS algorithm's convergence speed is faster while its computation load is bigger, according to the condition that the beam-forming algorithm must have fast response speed and convergence speed in mobile communication system, the RVSSLMS algorithm is improved by combining the advantages of RVSSLMS algorithm and RLS algorithm together: the RVSSLMS algorithm's initial iteration weight is from the RLS algorithm's weight whose length of data block is 25.The improved one not only keeps less computation load, but also attains faster convergence speed. The efficiency of the improved method is verified by Matlab simulation, the result indicates that the convergence speed of this RLS-RVSSLMS algorithm is as fast as that of RLS algorithm and the operation load of it is as small as that of the RVSSLMS algorithm.

Abstract:The phase estimation of sinusoidal signal in noise environments is extensively adopted in the field of radar, navigation and DOA estimation, etc. A sinusoidal signal phase estimation method---Singular Value Decomposition (SVD), based on cross-high-order cumulant, is proposed. The signal and noise subspace are obtained using SVD of cross-high-order cumulant matrix. The signal subspace is the optimum solution for signal detection and noise suppression. The high-order cumulant matrix of signal is a conjugated symmetric matrix, its left singular vector is identical with the right one, their amplitudes and frequencies are also the same. The cross-high-order cumulant matrix of sinusoidal signals with different phases is a unconjugated symmetric matrix, its left and right singular vector are different because of the phase difference existing among the harmonic signals. A very important theorem is demonstrated in this article, i.e. the phase angle of the left and the right singular vector inner-product of harmonic signal cross-high-order cumulant matrix is equal to the phase difference of sinusoidal signals. Based on this theorem, the method of SVD for phase estimation of sinusoidal signal is deduced. The availability of the method is verified by simulation.

Abstract:The purpose of situation understanding is to identify the intention and warfare plan of enemy, which explains the current situation based on the expert knowledge and situation character vector. The battlefield circumstances in the modern aerial defence warfare become more and more intricate, and the aerial intelligence obtained is uncertain, so the effective inference of intention of the air attack is an important problem in the C4ISR system. In this paper, the uncertain aerial intelligence is expressed by the interval number. The distance formula between interval number and real number is presented. The target intention is described by the characters of position angle, distance, horizontal speed, course angle and height. Then the inference of intention model based on interval number grey relationship analysis with uncertain aerial intelligence is built. Taking the target intention to be inferred as the comparative sequence, and the known normal character vector as the reference sequence, the normal character number can be calculated by the method of fuzzy cluster analysis. The validity of this method is demonstrated by an example, which can provide scientific basis for the command decision making in the aerial defence warfare.

Abstract:The content-based image retrieval is an important research point in recent years. It can help finding images from the database exactly and quickly. Based on the image texture, this paper presents a new classification algorithm in which the wavelet analysis is performed, after the careful analysis, designs the features reasonably. Then, according to these features, the similarities of the textures are computed and the classification result is obtained. In the experiment, 100 images are searched and 75% of the results are correct. In order to further prove the robustness of the algorithm, 35 kinds of texture images are rotated to get 35 new images, then these 70 images are searched, the correct rate is 64%. The experiments show that the algorithm is effective and most of the textures can be correctly recognized by using it. Compared with other algorithms, it not only has high correct rate, but also is robust with respect to the results of the rotated images. According to the analysis of the distance between different textures, the algorithm could reflect the similarity of similar textures and meanwhile, does not necessarily require that the images are completely the same in size.

Abstract:First, the principle of matched-phase of signal of three sensor array is introduced, and the formulae of extracted signal are derived. Then, the performance of principle of matched-phase of signal in coherent interference suppression is analyzed. The effect caused by fluctuation of interference spectrum amplitude on the principle of matched-phase of signal is studied, and the formulae of relative error of extracted desired signal are derived when interference spectrum amplitudes are fluctuant. Again, the viewpoint is presented that the addictive noise can be viewed as the fluctuation of interference spectrum amplitude. Finally, based on the fact that the number of practical array elements is commonly more than three, two methods, three sub-arrays and least square method, are proposed to improve the performance of principle of matched-phase of signal by exploiting redundant elements of array. Simulation result shows that the performance of three sub-arrays and least square method is much better than that of the three sensor array. Also, a conclusion is given that the computation load of three sub-arrays is less than that of the least square method, but the three sub-array method is applicable to the uniform line array and the least square method is suited to arbitrary array.

Abstract:An algorithm of Data Mining based on fuzzy neural net is proposed in the article. The algorithm creates a new fuzzy neural net, in which Gaussian-Function is used to calculate five fuzzy memberships in fuzzy layer. The average and variance required by Gaussian-Function can be calculated in advance through the data to be collected. Using of fuzzy inference from a Max-min operation to replace commonly multiply-add operation accelerates the speed of the network. In training stage, first the centre-of-gravity method is used to resist the fuzzy of the output of the fuzzy layer, and then BP idea is adopted to calculate the error and adjust the membership function parameters. To improve the accuracy and speed of fuzzy neural network, the net, using appropriate rules, crops redundant nodes and weights to extract and simplify the rules. A simulation is performed by using the control data from the intelligent temperature control system in industrial forging, the result shows that the algorithm has higher precision and stronger robustness.

Abstract:Metamaterial for invisibility is a new class of artificial functional material. This paper takes infinite concentric cylindrical shell as stealth model. First, the distribution and high bianisotropic properties of metamaterial for invisibility are analyzed in squeezed cylindrical coordinate system. Second, the invisibility performances of cylindrical shell of the ideal、layered and lose materials are simulated according to full-wave simulation method, the distribution of relative total energy density demonstrates that the metamaterial cylindrical shells are perfect in invisibility performance. Finally, usage in other isotropic electromagnetic environment is introduced according to Pendry coordinate transformation method.

Abstract:It is a central problem in the research of coding to study the existence, structure and construction of the certain optimal property codes. In order to construct the quantum error-correcting codes, people have begun to study the self-orthogonal code that has the special self-dual distance. In this paper, two classes of sub-codes, which have optimal dual distance or intended optimal dual distance, of the binary non-decomposable self-dual codes of length n between 12 and 20, such as B12, D14, E16, F16, H18, I18, J20, K20, L20, M20 and S20, and the corresponding S-chain construction are studied. Based on the generator matrices of the self-dual codes, optimal sub-codes of dual distance 2, 3 and 4 of these self-dual codes are constructed by using a combinational method. Then code chains of these optimal sub-codes and their dual codes are discussed. Consequently, S-chains are constructed from these sub-codes with optimal dual distance or intended optimal dual distance. Finally, some very good quantum error-correcting codes are constructed from the S-chains obtained. These quantum codes are the ones that the distance reaches the maximum when their n and k are given.

Abstract:In order to gain a deeper comprehension of rough set theory in arbitrary universes (not only in finite universes), definitions of R-rough set and R-accurate set are presented from the equivalence relations R in arbitrary universes. These definitions are independent of the upper and lower approximations. Based on this, the properties of R-accurate sets are investigated, a determination theorem and a closeness theorem of operations of accurate sets are put forward and proved. Then the properties of the upper and lower approximations are discussed, again, a representation theorem, a comparison theorem and a topological structure theorem of the upper and lower approximations of rough sets are presented and proved. Finally the dependency of a knowledgebase is researched; a representation theorem of positive areas and a determination theorem of dependency of the knowledgebase are given. These results enrich to a certain extent Pawlak's rough set theory. The conception of accurate set in Chinese is updated.

Abstract:Based on the fatigue test results of SAE 1045 medium carbon steel and 40CrNiMo alloy steel, the axial and multi-axial fatigue life predication models are founded respectively. Relationship between the two kinds of models is studied. It is found that, so far as the two kinds materials are concerned, if the fatigue strength exponent and the fatigue ductility exponent are constant, while the fatigue strength coefficient times1.0937 and the fatigue ductility coefficient times 0.7512, the von Mises equivalent strain amplitude replaces the axial push-pull strain amplitude, then the modified axial fatigue life predication model is equivalent to the multi-axial fatigue life predication model. In the modified prediction model of multi-axial fatigue, the fact that the elastic line shifts up while the plastic line down indicates that given the same strain amplitude, the elastic strain component in uni-axial fatigue is larger than that in multi-axial fatigue while the plastic strain component in uni-axial fatigue is smaller than that in multi-axial fatigue. Therefore the revised axial fatigue life predication model can be used to predict the multi-axial fatigue life.

Abstract:The method of constructing quantum error-correcting code by the quaternary self-orthogonal sub-code chains and L-chains are investigated in this paper. Random searching method is used to find quaternary self-orthogonal codes and these self-orthogonal codes could form some self-orthogonal code chains. By using combinatorial method, quantum error-correcting codes are constructed in light of L-chains which are constructed by dual of these self-orthogonal codes. The code chains of these self-orthogonal sub-codes and the L-chains which are obtained from the dual of these self-orthogonal sub-codes of length n between 20 and 36 and n=40,45,50,55,60 and dual distance five and six are determined. Some quantum codes of distance five and six are constructed by the obtained L-chains, some quantum error-correcting codes are new.

Abstract:CoFe2O4/TiO2 nano-composite films were prepared using the sol-gel method with tetrabutyltitanate and metallic chlorates as starting materials. The phase structure and microstructure properties of the samples were studied by X-ray diffractometer, Raman spectrum, scanning electron microscopy. The magnetic properties of the composite films were characterized by vibrating sample magnetometry. The results show that crystals of different substances grow up independently without producing new phases, and the growth of composite films is dependent on the heat treatment temperature. The grain size of Cobalt ferrite is controlled by the titanium dioxide matrix in the prepared composite films, the average size of CoFe2O4/TiO2 is 19nm in nano-composite film prepared at 800℃ and pH=2-3 of the precursor. The magnetism of the composite films is enhanced with an increase of the heat treatment temperature.

Abstract:Based on the state superposition principle of quantum mechanics, asymmetrical multimode functional superposition state light field with the superposition of four quantum states is constructed. By using multimode squeezing state theory, this paper makes a detailed study of the unequal-power higher-power amplitude-squeezing of generalized magnetic-field of 4MFSS light field in medium and it is found that 1) under certain conditions, the generalized magnetic-field of 4MFSS light field shows periodical generalized nonlinear unequal-power higher-power amplitude-squeezing; 2) the Nj-th power higher-power amplitude-squeezing shown in the generalized magnetic-field of 4MFSS light field is obviously affected by the coefficient of the gain medium or of the absorption medium. In the gain medium, when the light field spreading distance becomes farther, the extent, range and effect of Nj-th power higher-power amplitude-squeezing are intensified; in the absorption medium, when the light field spreading distance becomes farther, the extent, range and effect of Nj-th power higher-power amplitude-squeezing are decreased.