Abstract:Numerical simulations for the aerodynamic characteristics of near space hypersonic projectile have been computed using the Spalart-Allmaras (SA) turbulence model and thermally perfect model, a time-dependent, finite-volume numerical method and AUSM+ scheme are adopted to solve the three dimensional Navier-Stokes equation. Numerical solutions of hypersonic projectile flow-field with attack angle are obtained, and the numerical results can be used in the further study of the near space hypersonic projectile and missile.

Abstract:In order to meet the requirement of military transport aircraft design scheme, this paper introduces an evaluation method of the military transport aircraft design scheme based on the grey relation projection. Evaluation indexes of military transport design scheme such as the mission capability, the capability of stone's throw rise and fall, availability, survivability, affordability, risk and comfort are analyzed. Then the six military transport aircraft design schemes are evaluated by the grey relation projection method. With this method, a weighed grey relation matrix of each military transport aircraft design scheme is built and the grey correlation projection values of the design schemes comparatively to the perfect scheme are calculated according to the vector projection theory. The grey relation projection values can be used for evaluation of the schemes. The result calculated shows that the grey relation projection method is feasible in application to military transport aircraft design scheme evaluation.

Abstract:Based on the basic introduction of Quality function deployment (QFD) and Failure Mode and Effects Analysis (FMEA), the virtues and limitations of QFD and FMEA are analyzed. According to the complementarity of QFD and FMEA, the frame model which measures consumers' requirements based on combination of QFD and FMEA is developed. The important quality characteristics for consumers' requirements can be selected by QFD, the failure mode and the effect of key parts can be analyzed by FMEA. Thus the Consumer's Requirements Importance based on FMEA is directly fed back to the House of Quality, and a more reasonable sequence of Consumer's Requirements Importance is acquired. Finally, the usability and advantage of the frame mode are verified through a calculation example.

Abstract:In the light of the issue of storage level of aviation spares with different requirements, the optimal models of spares storage level based on the availability centered and the cost centered are established respectively according to the benefit optimal principle of military and economy. The inventory cost model is given, in which the purchasing cost is a master cost index. Assuming that the spares demand is a Poisson distribution with intensity λ, and the spares repair time is identical distribution with mean T. Then the availability model is given by Palm's theorem, in which the expected backorder is the scale index. And spares quantity is confirmed by iterative calculation, according to the marginal analysis method, in which the return value of marginal utility is the ratio of marginal increment and unit price for spares. Finally, it shows that the model and method are effective in balancing the relation between efficiency and cost through the analysis and comparison of particular cases.

Abstract:The after-sale technical service is a vital condition of operating properly for materiel. However, how to evaluate the quality of the after-sale technical service, which has never been concerned so extensively as the consumption servicing business, now become a new subject and an important measure for assuring and improving the after-sale technical service quality. Commencing from the analysis of the contents and quality elements of the after-sale technical service for materiel, the paper builds up an evaluation index system and layer structure, and simultaneously sets up an evaluation model on the basis of Analytic Hierarchy Process and fuzzy mathematics theories. The effects of this model in application to airplanes are satisfactory

Abstract:The calculation method of equivalent modulus of elasticity of foundation is studied in the principle of displacement equivalence by elastic multi-layer theory, and the boundary conditions are identified and studied based on the analysis of the influence factors for the calculation method of equivalent modulus. The deficiencies in the present calculation methods of equivalent modulus of elasticity of foundation are analyzed. Based on the analysis of great amount of computing data, the calculation expressions are reestablished when the load radius is 15 cm, which has better precision and extension, besides, the modified coefficient of load radius is added. The calculation expressions of equivalent modulus of elasticity of foundation are applicable to the calculation when the ratio of equivalent base modulus to subgrade modulus is greater than 2 and base equivalent thickness is greater than 20cm, and the load radius ranges from 10 cm to 50 cm.

Abstract:With the development of modern weapon platform, the position of multi-sensor management is becoming more and more important in the information fusion system. In the air defense warfare under information-based condition, establishing Air-Ground air defense situation awareness network is a technical assurance to capture informational preponderance, meanwhile realizing scientific and reasonable allocation of sensors resource is an important method to improve the gathering efficiency of air defense network. We have to manage the limited sensors resource scientifically and reasonably so as to improve air defense warfare effectiveness. The optimization model based on information gain and target threat degree is proposed for multi-sensor management. This model, through calculating rough entropy of the sensor to the goal, obtains the greatest information content of each sensor to each goal. By taking this as a price function and in view of target threat degree, the optimized assignment of the multi-sensors to the multi-goals is done by using linear programming, the simulation result indicates that this model is effective and reasonable.

Abstract:In order to gain a clear idea of the range of OTHR first-order sea clutter backscattering coefficient and its changing law on the whole and also the change discipline of the first-order sea clutter backscattering along with the affection of OTHR frequency, wind speed on sea surface, angle between the directions of ocean wave and wind, and the spread degree of wave height spectrum with direction about the wind direction on ocean surface, considering the characteristic of OTHR detection, the paper introduces the first-order sea clutter backscattering coefficient model given by Barrick, and then, by means of simulating, obtains that the first-order sea clutter backscattering coefficient is within if the non-directional amplitude spectrum is in the state of saturation or within if the non-directional amplitude spectrum is in the state of unsaturation, in addition, the magnitude of the frequency and of the speed of wind on sea surface determine that non-directional amplitude spectrum is in the state of saturation or in a state of unsaturation. And then also through simulating the affection of every parameter on the first-order sea clutter backscattering coefficient, the paper presents the change discipline of the first-order sea clutter backscattering along with each parameter. All these are useful to OTHR detecting and father high frequency radar sea clutter modeling and filtering.

Abstract:By combining the interacting multiple model with the particle filter, a new interacting multiple model particle filter (multi-rate interacting multiple model particle filter, i.e. MRIMMPF) algorithm is proposed, in which a multi-rate technique is adopted. In the algorithm the multiple models are used for tracking arbitrary maneuvering target. To deal with the nonlinear and non-Gaussian problems, a particle filter is adopted in each model. But when the particle filter is applied in the IMM algorithm, an expensive computation appears in the whole process. In order to solve this kind of disadvantage, the multi-rate technique is adopted, by doing so, the computation is obviously reduced. The simulation results show that the MRIMMPF algorithm works as well as the IMMPF algorithm in performance.

Abstract:To solve problems of PMA's offline-work in the field of aircraft maintenance, the paper researches strategy of data processing in occasional connect mode is researched and a data accessing model of "occasional connect" is proposed .On the basis of the model, the paper expatiated the process of its implementation from two aspects which are the choice of long-term data cache and synchronization mechanism. The primary application proves that it can be adapted to complex network condition in the field and can greatly enhance the ability of aircraft maintenance support.

Abstract:The electromagnetic (EM) characteristics of log-periodic antenna (LPDA) are studied by adopting high order Method of Moment (MoM). Firstly, the antenna is segmented via generalized wire geometrical modeling. Then, electric field integral equations are formed based on EM boundary conditions. Finally, by virtue of high order MoM in which mixed-domain basis functions are adopted, the equations are made discrete and solved. The results of simulation show that this method is simple, accurate and has some practical value and theoretical meanings

Abstract:The algorithm of interference detection for Multi-band Ultra-wideband communication system is analyzed and discussed in this paper. A modified scheme named parallel multi-band UWB is presented to improve the data transmission speed of the traditional MB-UWB scheme. In order to meet the requirement for high data transmission speed, an orthogonal operation of sub-pulse is designed. The performance of interference suppression for parallel multi-band ultra-wideband communications is mathematically analyzed and described. Based on this new scheme, a new algorithm named parallel sub-pulse interference detection is proposed. This new algorithm can be realized in low level sample rate. Mathematic analysis and computer simulation for this new algorithm are made. The simulation results show that the new algorithm can detect the coexisting interference effectively in low sample rate and improve the BER performance of parallel multi-band UWB communication system evidently in combination with the interference suppression measures.

Abstract:A brief introduction to current GNSS anti-jamming research situation at home and abroad is given. In combination with the application of BLMS (Block Least Mean Square) in GNSS anti-jamming, the BLMS Algorithm's block diagram and its signal flow chart are given to show how to realize it in hardware, and some problems are analyzed in its realizing process. An in-lab anti-jamming researching method is introduced, that is, using signal generators to simulate the jamming and the satellite navigation signal, and using power divider and synthesizer to simulate the array. Finally, monochromatic jamming and swept jamming are used to test the Algorithm's anti-jamming capability, and its validity is checked by a matlab C/A code correlating program. According to the experimental data, the jamming can be mitigated at large scale when it is suppressive. This offers a valuable reference for GNSS anti-jamming research.

Abstract:Relying on mutual orthogonality between subcarriers of different users in Orthogonal Frequency-Division Multiple Access (OFDMA) systems and exploiting both Linear Constellation Precoding (LCP) and Group layered space-time block code (GLSTBC), a novel LCP-GLSTBC-OFDM transmitter diversity technique is proposed for wireless communications over frequency-selective fading channels. The proposed approach is based on a three-level design of user codes: the top level (based on OFDMA) deals with group interference and intersymbol interference (ISI), the middle level (based on STBC) results in space diversity, and the lower level (based on LCP) results in frequency diversity. The proposed design only needs one receive antenna to suppress the group interference and can obtain half space diversity gain , half multiplexing gain and full frequency diversity gain simultaneously. The performance merits of this design are verified by simulations.

Abstract:In recent years, laser machine has been widely applied in the military realm. However, the driving power supply is the most important factor that limits the whole performance of the laser machine. According to the request of the great power laser to the drive supply, a new design based on constant current power source is proposed, which includes a RLC quasi-resonant converter technique and a topologic structure of the whole bridge. To achieve the effective protection of laser, a constant current source driver, soft start - up, limit flow and limit electric voltage implement are taken. And, the electric circuit of temperature control is adopted to control the temperature of the laser, which can ensure the stability of output power. In addition, principle figures of the filter circuit, main power supply circuit and protection circuit are included. Finally, the high stability and the strong interference ability of the newly designed power supply are verified through experiments.

Abstract:According to the weight character of quaternary self-orthogonal codes, the relations between two dimensional optimal self-orthogonal codes and their weight distribution are discussed. By introducing two definitions of defying vector and projective weight vector of quaternary linear codes and using the matrix constructed with simplex codes, the relations between two dimensional optimal self-orthogonal codes and the non negative integral solutions of equation systems are setup. And, the existence problem of two dimensional optimal self-orthogonal codes is changed into the problem of determining the non negative integral solutions of equation systems.For the given code length, firstly, the minimum distance of two dimensional optimal self-orthogonal codes is determined by Griesmer bound, then, the generator matrices and the weight polynomials of all optimal self-orthogonal codes of this length are determined through solving integral equation systems. According to generator matrices obtained, equivalent relations among these optimal self-orthogonal codes are discussed by using elementary row transformations of matrices, coordinates permutations of vectors and conjugate transformations of elements. Finally the classification of two dimensional optimal self-orthogonal codes is solved, and the generator matrices of these non equivalent two dimensional optimal self-orthogonal codes and their weight polynomials are also presented. polynomials are also presented.

Abstract:The ZnO thin films which have unabridged fabric and are highly c-axis oriented is essential to the preparation luminescence apparatus which eradiate shortwave and piezoelectric film resonator. High quality crystal ZnO thin films have been deposited by RF magnetron sputtering on glass substrates. Strong UV photoluminescence and feeble deep energy eradiation are observed at room temperature. Under the different air pressures samples are studied by X-ray diffraction (XRD), PL (photoluminescence) spectrum and AFM. The surface, growth, crystallization condition and photoluminescence are analyzed. When the air pressure is in the range of 1.9 Pa-2.6 Pa, the diameter of grain will increase, when the air pressure augments from 2.6 Pa to 3.5 Pa, the diameter of grain will decrease. When the air pressure is 3.2 Pa, the grains are highly c-axis oriented compared with others. So the optimal air pressure is in the scope of 2.6 Pa-3.2 Pa. Highly c-axis uniquely oriented ZnO thin films with the FWHM of only 0.12° is deposited.

Abstract:Ceramics of 0.36〔BiSc(1-x)GaxO3〕—0.64PbTiO3(x=0.001、0.003、0.005、0.008、0.01、0.015、0.02) are prepared by conventional solid state reactions when Ga2O3 is doped into 0.36BiScO3—0.64PbTiO3(BSPT64) system. The analysis results of X-ray diffraction reveal that Ga3+replacing Sc3+ does not change the perovskite structure of BSPT64. The dielectric and piezoelectric properties are investigated. The results show that BGSPT64-0.01 has an optimized characterization, i.e. its piezoelectric coefficient d33,planar coupling coefficient kp, remnant polarization Prand coercive field Ecare respectively 510 pC／N,61％,49 μC／cmand 21kV／cm. The research results show that the BGSPT64—0.01 ceramics is a good candidate material for the piezoelectric actuator and transducers.