Abstract:Flows of 2-D shock propagation in single or multiple baffle systems are simulated. Euler equations are solved numerically by NND finite volume scheme in unstructured triangular grids. The results show clearly the complex structure of the flowfields and compare well with experimental data. It is demonstrated that unstructured grid method can handle these complex geometries easily and avoid probable unreasonable solution near the sharp corner.

Abstract:The interaction between shock waves and boundary layer in isolator causes a very complicated flow, to simulate the turbulent flow field in it, the time-dependent, implicit, finite volume, lower-upper numerical method was used to solve the 3D compressible Reynolds-averaged Navier-Stokes equations. Numerical results are compared with experimental data and used to describe the vortex structures in different isolator shape or different location of an isolator combined shock train structures in it. The numerical results indicate that the vortex structures in square cross section and rectangular cross section is very different.

Abstract:In order to study completely the atomization characteristics of mixing cavity of the designed new type tripropellant injectors, model injectors are designed for experiments under multiple operating conditions. Through experiments it can be seen that different curves of regularity for variations of SMD along with pressure drop of gas as well as mass ratio of gas to liquid ALR will be gain if the pressure drop of liquid remains constant while transform the pressure drop of gas. So do the other case only transforming the pressure drop of liquid. Moreover, these curves show the regularities. A great deal of experiments indicate the curves of average diameters SMD along with mass ration of gas to liquid ALR have the same trends although obvious differences exist between curves that SMD along with pressure drop.

Abstract:In this paper a normal freedom on each area is given on 8-node hexahedron isopapametric element. At the same time seven unconforming inner displacement functions and one bubble function are adopted as additional displacement in order to eliminate geometry sensitivity and gain high precision. Numerical results show that this element is of excellent properties.

Abstract:The combustion characteristics of silver-wire embeded fuel-rich propellant grain are investigated. The effect of the diameters of silver wires and the composition of the propellant on the combustion properties is studied. The test pressure-time curves show that the combustion process of silver-embedded fuel-rich grain consiss of initial part, steady part and end part. The silver-embedded fuel-rich propellant grain with coarse silver wire（diameter: 0.3mm and 0.4mm）gives up high burning rate. Furthermore, to increase the burning rate of the fuel-rich propellant is also a good way to increase the burning rate of the silver-embedded fuel-rich propellant grain.

Abstract:The fluctuating pressure distribution on the surface of the sphere-biconic reentry vehicle in a wide range of attack angles is investigated in the supersonic and hypersonic flow field. Based on the mean pressure distribution, some engineering correlation has been developed. Then utilizing the developed techniques, we investigate the effects of Mach number, attack angle and wall temperature and achieve a series of reasonable results comformable to test data.

Abstract:This paper mainly describes the method of designing a aircraft control system based on the classical control theory after creating the aircraft movement models. The control system's performance is also simulated with the effects of some nonlinear elements such as saturation and transport delay. From the results we can see that the structure and parameters are reasonable, the performance can meet the need of the task. At the same time, it can offer more creditable data and diagram for the hardware-in-the-loop simulation and the flight experiment.

Abstract:Aiming at satellite attitude system which is composed of gyroscopes, infrared earth sensors and solar sensors, we set up the model of the satellite attitude detemination by using quaternion, and build kalman filter for information fusion. The simulation result indicates that this method can provide satellite attitude parameters which satisfy the requirement.

Abstract:Taking an lunar probe around the earth and the moon from the earth parking orbit for example, we analyze some questions of navigation of the lunar probe based on ground tracking site, including the choice of tracking type, distribution of ground tracking site, adjustment of the guiding time, and accuracy of navigation. It is verified that the lunar probe can be navigated in real-time by ranging data based on the local ground tracking site. The method and result of the research may serve as reference for the practical engineering of lunar probe.

Abstract:Based on spline filtering, this paper presents a novel self-adaptive approach for trajectory determination by using velocity measurements. The spline function is adopted to express the parameters of the trajectory so that an iterative algorithm of self-adaptive Kalman filter is established. When information of velocity measurement is merely provided, this approach can give real-time trajectory parameters of the aircraft with high precision.

Abstract:Based on our research and exploration in the field of data processing and modeling of trajectory tracking data, this paper puts forward several observing data models with typical application. These models are relative to many aspects of statistics, optimization, functional approximation in theory and calculation. The investigation of these problems and models is significant to the solution of many relevant practical problems.

Abstract:By using the line of sight (LOS) measurements from space-based infrared sensors, free flight phase trajectory estimation problem of ballistic missile is studied. Taking into account poor target motion observability, maximum likelihood estimation problem of trajectory is solved by using an improved Gauss-Newton algorithm by which the position and velocity are filtered in turn. Monte Carlo stimulation verifies the efficiency of this algorithm. Besides estimation error is analyzed.

Abstract:A method of boundary force is used to process rigid boundary condition in smoothed particle hydrodynamics (SPH) simulation, and a new boundary force is given. Both problems of the free surface flows: bursting dam and bore, are simulated by using the SPH method via the boundary force. The numerical results show that the method of boundary force can be successfully used to process the rigid boundary condition.

Abstract:The impulse produced by the explosion of mild detonating fuses is measured by using photoelectric method. The experimental results indicated that only a small part of all lead particles hitting the target, adher to it, and the impulse is pooduced by the interaction between exploded mild detonating fuses.

Abstract:To ensure absolute security of key distribution, each key distribution scheme must be proved. While the security of most classical cipher schemes cannot be proved, the security of quantum cipher schemes is guaranteed by quantum mechanics and can be strictly proved. Shor-Preskill's method with which the unconditional security of BB84 quantum key distribution scheme is proved is introduced first. Its techniques and features are summarized and the subtleties of using symmetrization and quantum entanglement purification (QEP) to reduce a QEP based BB84 to a CSS based BB84, and of using the property of CSS code to reduce the CSS based BB84 to standard BB84 protocol are revealed. Then it is proved that Shor-preskill's method cannot be applied to B92 protocol directly. A possible solution to prove the unconditional security of B92 using Shor-Preskill's method indirectly is proposed.

Abstract:Space-time block codes are code technologies which provide a new paradigm for transmit over Rayleigh fading channels using multiple antennas. The general decoding algorithm of Space-time block codes is deduced.

Abstract:Technology of passive location has broad prospects for application. The single observer-passive location method of phase difference rate of change is introduced based on existing methods. We can obtain the direction of the target with phase difference information of two orthogonal interferometers on the observer and the radial distance with corresponding phase difference rate of change information. Then the target can be located with high speed and precision. Some locating expressions are given when the observer is flying along a horizontal beeline without any posture change. Simulations show that this method is effective.

Abstract:At the information age, more and more affansion is paid to PCs' information protection. Firstly the principles of Personal Firewall is introduced, and the disadvantages of some typical PFW products is analysed in IP filtering, port protection, exploit protection, and process protection. Hence, the concept of enhanced personal firewall is brought out. After that, the designation and technical methods of EPFW's IP filtering, port protection, exploit protection, virus protection and process protection are illustrated. All these show that EPFW is a reasonable way to solve the problem of PCs' information protection.

Abstract:Smart antennas receive much attention recently in the communication field. The basic principle of smart antennas is first expounded. Then the uplink narrowband adaptive beamforming algorithms are introduced. The adaptive beamforming algorithms are classified, and the characteristic of each algorithm is discussed in detail. The study status and applications of smart antennas are described in the end.

Abstract:The research background is the calibration of the magnetic suspension and balance system developed in China. The paper introduces the traditional linear calibration modeling methods, discusses how to overcome its limitation after examining the calibration test data carefully. An improved method of nonlinear fitness to construct the calibration model is proposed. The proposed method uses the rational components of the concept of principal component analysis, and adopts the ideas of cubic spline fitting. Finally, We compare the results of the improved method and traditional methods, and prove the effect of the proposed one.

Abstract:Based on the property of configuration space of parallel manipulators and by using differential geometry and topology, this paper proposes a new approach for the classification of singularity of parallel manipulators, two types of singularity are obtained, i.e, topology singularity and parameterization singularity. Also comparisons with existing classification methods are made.

Abstract:In the test of high-speed precision spindle,the high speed may make error separation impossible. In this paper, model analysis is applied to testify the possibility of error separation. Then the error due to testing with precision spindle instead of precision ball is analyzed, and the setup error of sensors is analyzed as well.

Abstract:It's important to improve the performance of the weapon by compensating for errors of inertial sensors. Identification of error model is the key of compensating for errors. A multi-layer local recurrent neural networks is adopted to model the errors of inertial sensors. The framework of networks and adaptable dynamic gradient arithmetic are presented in detail. The result of simulation example shows that multi-layer local recurrent neural networks has some advantage for modeling errors of inertial sensors' output: rapid convergence, good performance of tracking and stabilization.

Abstract:The estimation of fitting probability in a circle is studied. The bootstrap method and data-fusion estimation method are given. At the same time, the accuracy of the estimator is analysed. These methods can be applied in engineering practices.

Abstract:Blind image digital watermarking, which can detect watermark without using the original image, is a key technique for the practical intellectual property protecting system. For its good performance in image analysis and image compression, wavelet based digital watermark algorithm has become the mainstream in the digital watermark research. Based on the local Gaussian model of wavelet coefficients, we propose a new blind watermark detector. A series of experimental results show that it is more robust than linear correlation detector.