Abstract:Under the assumption of perfect gas，the thin layer N-S equations are solved by alternating direction implicit NND scheme，and the space grids of complex wing-shape are generated by solving parabolic partial differential equations. Finally，the numerical simulation results of maneuvering missile with the control helm are shown under the conditions:M_∞=7.3，α=20°.The results include contours of flow-field, pressure distribution and limiting streamline along the surface.

Abstract:The newly developed Inflatable Thermal Shield(ITS) technology offers a simple, reliable and economical way to recover various vehicles from orbits and is therefore possible to be a substitute for parachute systems in the future. The selection of the aeroshell shape for the ITS recovery system is discussed. CFD methods are used to predict the subsonic, transonic and supersonic aerodynamics of the selected shape and compared with the Newtonian hypersonic estimation. The single-stage and two-stage inflation schemes are examined with the calculation of a 90kg cargo's re-entry trajectory, the latter is shown to possess better combination of deceleration and thermal protection and is therefore the ideal ITS re-entry scheme.

Abstract:With the particle simulation method employed to trace the trajectory of solid particles and NS equation solved with NND scheme, the gas-particle free jets expanding from a high pressure stagnation chamber through a sonic orfice into a quiescent low pressure chamber is numerically simulated. The results demonstrate that combination of particle simulation method with CFD is an effective approach to the two phases problem.The existence of solid particle is of strong effects on gas flow property.

Abstract:Numerical simulation of the flow field around the oscillating ideal flat plate is presented to assess the aerodynamic derivatives. The time-dependent incompressible Navier-Stokes equations are decoupled using Projection-2 method. The second order semi-implicit scheme is employed in temporal and spatial discretization for the momentum equations of intermediate velocities, while the Possion's equation for pressure is solved efficiently by using the multigrids method. Unsteady aerodynamic force on the heaving or pitching oscillated flat plate are computed and the motion of the plate is accounted by the moving grid method. The aerodynamic derivatives are extracted with the Least Square Method. The computed aerodynamic derivatives are in better agreement with Theodorsen's theoretic solutions.

Abstract:Numerical modeling has long been recognized to be a powerful method of studying the wave propagation in media with complicated structures. More interests are aroused in the anisotropic problem and heterogeneous problem. The Pseudo-Spectral Method (PSM), with which global spatial derivatives are computed by multiplication in Fourier domain, is a new numerical modeling method based on the elastic wave equation developed in recent years. The main advantage of PSM is that it requires a relatively small number of grid points to achieve a specified accuracy. The PSM and its stability are presented. A 2-D PSM code based on workstation or PC is developed to model the 2-D elastic waves propagation in anisotropic/heterogeneous media.

Abstract:A 2-D axisymmetric nonlinear explicit finite-element dynamic analysis program is applied to compute the armature expansion process of the magnetic flux compression generator (FCG). The temperature rising and thermal softening are considered as Johnson Cook material is used for the armature. The results present the picture of expansion process of the armature, the expansion angle and temperature rising.

Abstract:During the last decade，Hidden Markov Models (HMMs) have become a widespread tool for modeling sequence of dependent variables. Parameter estimation of HMMs is most important in actual application. By changing continued-time HMMs into discrete-time HMMs, we consider maximum likelihood estimation for a special HMMs which is called Markov-modulated Poisson processes. Such processes have been proposed for modeling traffic streams in complex telecommunication networks.

Abstract:Based on integrating a great deal of foreign experimental data and numerical simulation data, the driving factors and configuration factors influencing characters of the synthetic jet are analyzed and summarized. Then the influences of Re and St for synthetic jet are investigated with numerical simulation method. And a correlation function reflecting the characters of synthetic jet actuator is obtained It provides references for the actuator preliminary design.

Abstract:Ultra high resolution real-time display system is composed of graphics processing system, ultra high resolution monitor. Its displaying resolution is 2048×2048, non-interleaved, 8-bit per pixel. The image input speed is max to 240 MB/s. It can display real-time image data of n(n=8,4,2,1 )CCD cameras simultaneously, and can process sampling m pixels from every n pixels (n=8,4,2,1; m=8,4,2,1; n≥m). This system can be widely used the satellite station and real-time display of the aerial image, medical image and other sensor's high resolution image.

Abstract:A representation method for 3D topological structure based on couple is proposed in a certain divided space. The structure defines four basic topological relationships on the couple (oriented face, arc).Through these basic relationships, the implementation algorithms for four important topological query are discussed. Thus it is shown that the 3D topological can deduce all kinds of topological relationships, especially topological relationships between 3D body objects, independent of geometry embedding.

Abstract:Modifications of the 2D virtual ESPRIT algorithm are made. The new algorithms make better use of the sensors, or relaxed the requirements of the sensor array at the similar computational cost.

Abstract:Analyse the partition of bandwidth between uplink and downlink in CDMA cellar system on the basis of the inputting C/I of a receiver and the channel model presented by T. S. Rappaport and L. B. Milstein, and gives the method of the asymmetrical partition of bandwidth. The simulation results are also presented，showing that the frequency asymmetrical partition between uplink and downlink enhances the capacity of CDMA cellar system.

Abstract:The m-sequences are popularly used in radar and communication systems because of its character of uniform auto-correlation sidelobes.The sidelobes of the m-sequences are not bilevel any more when the m-sequences are modulated by the symbols.Researches reveal that the sidelobes of the m-sequences can be greatly different given the same generator polynominal but different initial phase modulation. The ratio of mainlobes to sidelobes can be increased by choosing special initial phase modulation and even more increased when the mismatched filter is adopted. The features of the matched and mismatched filters are discussed when the inputting m-sequences are modulated by the symbols.

Abstract:First, based on DSP, the hardware structure of radar target detecting system is studied. Then, the methods of radar target detecting based on DSP are presented. The experiments demonstrate that this system can work well with a variety of radar system and can implement radar target detecting automatically.

Abstract:Introduces an adaptive fuzzy filter based on approximate entropy and applies the filter to the digital filter of rocket telemetry signal in the wideband noise. The adaptive fuzzy filter algorithm is discussed, and the experimental filtering results of rocket telemetry signal in white noise are given. Both analysis and experiment show that the parameters of this novel filter can adjust itself according to the complexities of the signal. It filters better than the average subsection fuzzy filter for the non-steady stochastic signal in the wideband noise.

Abstract:With the exponential growth of World Wide Web, it becomes more and more time and energy consuming for users to find what they're interested in. It leads to a clear demand for personalized services, which can provide different users with different services User modeling is the key technology in implementing personalized services. Conventional user modeling methods with both positive and negative examples will either interfere users' normal browsing or bring in noises. A user modeling method without negative examples is presented. A hybrid of genetic algorithms and kNN classifier are utilized to search the words describing users' interests. The method is applied in personalized information filtering. The experiments show that the filtering ratio and precision can be 73.91% and 94.44% respectively, which demonstrates that our user modeling method is feasible and efficient.

Abstract:Large-scaled distributed simulation system is urgently required in simulation community. The rapid evolution of HLA technology urges us to connect the different federations using gateway. The bridge federate can be adopted to maintain information transfer and system consistency Furthermore, we have discussed some introduced problems about the time-space consistency. The time advancement and ownership transfer are examined broadly as two examples.

Abstract:Distributed database system is a main research direction in the database field. Maintaining the data consistency is a critical technical problem in the distributed database system. Based on analyzing in depth and comparing with many kinds of methods in data consistency maintenance, an effective method of maintaining the data consistency is presented. How to resolve the conflict caused by the parallel execution and how to maintain the consistency of all data copies by message queue are discussed in details.

Abstract:An information fusion model of integrated navigation system based on neurons is proposed, and also an on-line adaptive training algorithm of the weights of neuron is given. Moreover the fusion model of the SINS/GPS integrated navigation system for vehicle is implemented. The theoretical analysis and laboratory experimental results show that this model and adaptive training algorithm are effective and practical.

Abstract:In order to find out the cause of position deviation of the roller mechanism, the interference source is determined by comparing the feedback signals and making position test at different situations. Based on analysis of the reason that the feedback signals are interfered, several measures are adopted and their effects are given. In the end, the problem is solved by using an isolation transformer for Y-axis driver. It is shown that this solution has good effects in wind tunnel test.

Abstract:Satellite tends to be microminiaturization in the future. It needs to adopt a small, cheap and middle precision autonomous navigation system. According to the measurements of three-axis magnetometer in the body frame, the parameters of the orbit can be determined by using of Kalman Filter.The result of simulation shows that orbit determination by dint of three-axis magnetometer is of medium precision, which can satisfy some requirments of orbit determination.

Abstract:SiC fibers with good high-temperature resistance are prepared by PCS fibers with low oxygen content(LO-PCS) through thermal cross-linking(TC) reaction.The sintering of the LO-PCS with two steps and the condition of the reaction is studied by element analysis、IR、XRD、SEM. And the relation between the structure and the properties of the fibers are systematically studied.

Abstract:Make a mathematical model for a multi-population cooperative co-evolution method and analyze it,using the idea of pattern replicator equation in one population genetic algorithmFor some unsolved key problems in co-evolution,such as the evaluation method for the individual,credit assignment for the cooperation among populations and the resulting individual law increase in population, analyze them theoreticallyFinally, show that the result of the mathematical analysis is consistent with Potter's experiment result.

Abstract:In view of the strong nonlinear feature of the magnetic suspension and balance system,variable structure controller is designedTaking the Y axis as an example,the procedure of designing nonlinear variable structure controller is discussed.The aim is to keep the error as zero.The design step includes three aspects.The design consequence is emulated at the same time.The result of the emulation shows that the dynamic properties of the system are upstanding.