Abstract:According to the design of aerodynamic configuration with variable forward-swept-wing, two kinds of variable forward-swept-wing configurations in which there are slight differences on the transition method of nose and canard are given. The aerodynamic results show that the delta-wing is better for breaking through a defense area in a combat, and the second configuration with integrated canard and nose leading edge is more competitive. The study of bistatic RCS of the two kinds of aerodynamic configurations shows that the RCS of the variable forward-swept-wing configuration in most ranges of azimuth is below 0dBm2, the lobe of wave peak is narrow and not easy to be discovered and tracked continuously. By comparison, the stealth characteristics of the leading edge's configuration are still better. So while optimizing the design of configuration with variable forward-swept wing, it is rational to adopt the design of configuration with integrated canard and nose leading edge.

Abstract:In order to investigate two-step detonation initiation process, the pre-detonators with different L (distance between transition section inlet and pre-detonator outlet) inserted transition section are simulated. The results indicate that the smaller the L, the more obvious the enhanced effect of the transition section is, but the effect caused by gradually outspread passage is weaker. When L turns longer, the trend is opposite. So it is necessary to choose a suitable L for the transition section and the gradually outspread passage to optimize the enhanced effect of detonation wave transition. When L is equal to 35 mm, the numerical simulated results indicate that the high temperature and high pressure area can be formed earlier to reinforce the detonation wave transition. The gradually outspread passage between pre-detonator and area expansion can form a better retardant effect on the return detonation wave, which prevents the excessively augment of the pressure in blender of the main combustor tube, then the two-step initiation of detonation can be successfully achieved.

Abstract:The thesis simulates the missile launch process by the method of the computational fluid dynamics (CFD), in order to study the aerodynamic interference and the rules of missile movement. A moving chimera grid approach is used coupled with an unsteady Euler flow solver, and a 6-DOF model is fully integrated into the CFD solution procedure to determine the body dynamics. And the paper presents the results obtained for a time-accurate missile launching from the R/S UAV by the developed numerical methods. Major trends of the separation are captured. As a result, the application shows the validity of moving chimera grid method, the use of the method of the CFD and the technology of moving chimera grid give a reference and gist to the study of the process of missile launch. The computation result shows that the effect of aerodynamic interference due to the thrust is negligible.

Abstract:A new index system of aerial warfare efficiency evaluation is proposed in this article, based on the characteristic of two great modes of modern aerial warfare within visual range and beyond visual range. In view of the weakness of single method in determination of weights in the traditional model, interval analytic hierarchy process (IAHP) is used to determine subjective weight and rough set method is used to determine objective weight. Then the subjective and objective weights are organically integrated, from which the optimal solution of interval combination weight is obtained. This method totally contains the advantages of the subjective weight evaluation method and the objective weight evaluation method, the use of it overcomes the weaknesses of the above evaluation methods and realizes the complementary advantages, which makes the result of efficiency evaluation more reasonable and scientific. Finally, the comprehensive evaluation model of aerial warfare efficiency is established. The feasibility and validity of the model are verified through the computation of an example.

Abstract:In aircraft accident and incident investigation, locating the similar accidents or incidents in the past can help investigators to find out the deep-seated reasons of the accident or the incident. CBR methodology is applied to aircraft accidents and incidents investigation. In the paper, the reasons for the aircraft accident and incident are summarized, and a frame of the accident and incident case is proposed. The historical data of accidents and incidents are used to build a case base. The nearest neighbor method is adopted to search similar cases. Finally, a similarity matching application example is given.

Abstract:Dynamic Selection of integration algorithm is usually accompanied with the situation that there is no way to avoid the misclassification when the local classifier can not classify the test pattern correctly, accordingly a novel dynamic SVM selection ensemble algorithm based on diversity-clustering is proposed. Clustering is applied to training samples firstly in this method. To every clustering, appropriate classifier ensemble is selected based on accuracy and diversity, and the sample areas which are misclassified by the classifier ensemble for every clustering is demarcated, and a set of classifier ensemble for it is designed. During testing, the test sample is classified by the appropriate classifier ensemble based on the clustering to which it belongs and the distance between it and the misclassified sample areas. Using this method can remarkably reduce the blind regions while the test sample is very close to the misclassified areas mentioned above. Experimental results show the effectiveness of this method. Compared with Bagging-SVM and literature \[10\] on UCI data set, the testing speed can be guaranteed and simultaneously the classification accuracy can be effectively improved by using this algorithm.

Abstract:Radar Jamming Cancellation system and some adaptive filtering algorithms are studied. Some variable step size LMS algorithms in literature are analyzed, based on which an improved one is presented. For this algorithm the similar sigmoid function is used to adjust the step size, thus the quantity of operation is greatly reduced and in the similar sigmoid function the self-correlation value of the error signal is used to adjust the step size, so the contradiction between the convergence speed and steady-state error is solved. At the same time, the use of LMS algorithm decreases the noise sensitivity. The computer simulation results confirm the theoretical analysis and show that the algorithm is of some feasibility and superiority.

Abstract:Modelling and characteristics analysis of two-dimensional space-time clutter for airborne MIMO radar are the key precondition for the design of airborne MIMO Space Time Adaptive Processing (STAP) algorithm. The two-dimensional space-time clutter antenna elements model and vector model are founded based on the geometric characteristics of airborne MIMO radar in this paper. The estimating method of clutter covariance matrix is researched under the condition of range ambiguities. The simulation results show that the airborne MIMO radar clutter is good in two-dimensional space-time diagonally distributing characteristics. Compared with the phased array radar, MIMO radar is wider in detecting angle of vision and greater in freedom of system, by which it can easily suppress clutters.

Abstract:In this paper， a new method is presented for finding data clusters centroids. This method is proposed based on the concept of electrostatic field in which the centroids are positioned at locations where an electrostatic equilibrium or balance can be achieved. After determining the centroids locations, criteria such as the minimum distance to centroid can be used for clustering data points. The performance of the proposed method is compared with that of the k-means algorithm through simulation experiments. The experimental results show that the proposed algorithm does not suffer from the problems associated with k-means, such as sensitivity to noise and initial selection of centroids, and tendency to converge to poor local optimum.

Abstract:In this paper, the stealth characteristics of the coated missile are studied. Through analyzing the relationship between Debye equation of and filed variable in time-domain, the shifting operator is applied to deriving the formulas of finite-difference time domain for dispersive medium, and the Maxwell's equations are modified to make the FDTD expression independent of the dispersive medium. The frequency-dependent expressions of FDTD in the dispersive medium are given. The comparison of the simulating results of this method to the results of literatures shows that the method adopted in this paper is effective in calculating the scattering characteristics of dispersive medium and that plasma plays a distinct role in decreasing RCS. The simulation results of missile coated with plasma are given. The effect of parameters selecting on stealthy characteristics is analyzed.

Abstract:In information field, one famous assertion is that performance of centralized fusion must be better than that of distributed fusion and also is optimal. It has been proven that this assertion is correct as single model filter, such as kalman filter, is adopted in fusion system. However, in case of maneuvering target tracking, in which multiple model filter, such as IMM filter, is usually applied in fusion system, is above assertion still valid? With doubtful attitude, this problem is investigated in the paper, three centralized fusion algorithms and two distributed fusion algorithms when IMM is used are presented, and simulations are made in different kinematic sceneries. Simulation results indicate that, as IMM filter is used in fusion system, performances of centralized fusion are not always better than those of distributed fusion. Analyses about this surprise result are also given in last section of the paper.

Abstract:The prediction and calculation of rain attenuation is one of the key problems of satellite communication in Ka-band. The model of DAH rain attenuation prediction in Ka-band is analyzed and its calculation procedure is summed up. Based on Wiener prediction, a new predictive model of rain attenuation, which enjoys the advantages of relatively simple structure, the ease of iteration and simple calculation amount, is established. Its concrete algorithm and procedure are also given. The simulation results show that the characteristics of this mew model are almost the same as those of DAH model under horizontal, vertical and circular polarized modes. The predictions in different regions are also consistent. The maximum deviations between this new model and DAH model are no more than 0.065 dB and 0.005 dB respectively when the orders are 2 and 3. These demonstrate that the new model proposed is available for use, effective, simple in algorithm and easy to be applied in engineering.

Abstract:A new combination method is introduced for solving the combination problem of experts' conflict opinions of military communication network effectiveness evaluation in this paper. For the new method, firstly, the quantification of evaluation opinions of experts is made based on multi-attribute group decision-making level evaluation model, then the basic probability distribute functions of each index are calculated based on the experts' evaluation opinions. Secondly, the basic probability distribute functions are combined based on the improved D-S model. Finally, a case is analyzed. The results show that the problem such as rejecting by one condition is solved and the new method is more reliable compared to the classic combination rule of D-S model. The opinions of experts can be reflected objectively and impersonally when the new method is used in combining the experts' opinions in the evaluation of military communication networks effectiveness.

Abstract:By the purpose of ensuring the precision positioning when the unmanned aerial vehicle (UAV) flies at a low altitude and the safe landing when it is in approaching, a fast and precise laser altimeter with lightweight and low power consumption is developed. Based on the principle of pulsed laser ranging technique, adopted continuous wave with the features of high precision and fast testing, integrated signal processing, computer-controlled simulation, virtual prototyping, precision machinery, precision optics and other advanced technology, the design and development of the device are completed by utilizing the virtue of infrared semiconductor laser, special ranging sensor module, high-speed A / D converter and high-performance SCM etc. In the experimental stage, hardware-in-the-loop simulation technology is flexibly used to avoid the complexity and error of computer modeling and simulation. The test results of the experiment show that all the technical characteristics meet the requirements of unmanned aircraft altimeter system, and the low-flying UAV can be exactly located and can safely land by using the system in the general environment.

Abstract:Information Systems Security Architecture (ISSA) has become a crucial branch and research focus of Information Security Science, and one of the key technologies in guiding the R&D of large-scale secure system (or security products) in the past ten years. The conceptual connotation of "Architecture" and the significance of Security Architecture have been proposed. The variety definition of ISSA is introduced, and its development trace is systematically overviewed. Based on the above, two different research methods and train of thoughts have been revealed. Then, the idea that "ISSA is the positive result of practicing systematic thinking in the Information Security field of investigation" has been clearly proposed. The disciplinary nature, the methodology of ISSA, and the challenges in the development of ISSA in theory, technology, education, practice and application are briefly discussed. Finally, the notion that Each Unification, of the Subjects like Information Security and Science of Systems, started from the basic science, should be the major trend and effective approach to radically solving the problems in Information Security is proposed.

Abstract:Because of the complexity of the communication equipment spare part support system, the use of technique of modeling and simulation is applicable and effective in the study of the system performance. Aimed at the scheme of spare part under two-grade support system, based on the analysis of flow for communication equipment spare part support system and regarding the spare part utilization and restoring rate as indexes, the flow simulation model of spare part support system is built by Arena. The law affecting the spare part utilization rate and restoring rate under two-grade maintenance support by the connection spare part configuration policy is analyzed through example simulation, which verifies the effectiveness of the model. Simultaneously, in the course of analyzing and describing the stochastic characteristics of variable and the dynamic process of the system, Arena is more effective and superior than the traditional modeling methods.

Abstract:Based on the coordinate transformation theory, the condition for irregular prism cloaks is deduced and the tensor expressions of electromagnetic parameters are obtained. By using the deduced tensor expressions of electromagnetic parameters, the effects of 3-sided, 4-sided and 6-sided prism cloaks are verified through full-wave simulations. The results confirm the validity of the tensor expressions of electromagnetic parameters obtained. The cloaks designed by using the deduced expressions can surely make the electromagnetic wave transmit around the inner object and resume its primary transmission direction. The work done in this paper provided a theoretical basis for the design of two-dimensional baroque cloak.

Abstract:Through strictly proving the equivalence of the least squares method and Gram-Schimdt algorithm in fitting interference wave-front with Zernike polynomials, it is demonstrated that all algorithms of solving Zernike polynomial coefficients in the solving process are the same in stability. That is, when one of these algorithms is interrupted or a mutation appears in fitted interference wave-front in the solving process, then it is also not possible for the other algorithms to fit interference wave-front correctly. The research results show that no algorithm is superior to other algorithms in fitting the interference wave surface with Zernike polynomials. All these algorithms are equivalent in reliability except that their fitting processes are different.