Abstract:For spacecrafts and its propulsion systems, it is very difficult to apply the classical modern control technology to solve the concerned control problems owing to the complexity of systems, the uncertainty and the unknown of the operating circumstances. The implication, function and construction framework of autonomous intelligent control systems are clarified and discussed. The system architecture of remote agent is analyzed. The reconfiguration of propulsion systems for spacecrafts by autonomous control techniques is also discussed. The analyses and discussion can be available for reference in the development of autonomous control systems for our spacecrafts in the future.

Abstract:AUSMPW+ scheme is applied to numerical simulation of hypersonic thermochemical nonequilibrium flow. The third-order MUSCL scheme is used to get more accurate solutions. The present schemes combined with the LU-SGS scheme to improve the efficiency and convergence of computation. Solving axisymmetric Navier-Stokes equations with 11 species air model gets the convergent solutions of thermochemical nonequilibrium flow. The ballistic range experiment is conducted for code validation and the sphere model is made of steel. The computational results are good compared with the experimental data and reference data. Using AUSMPW+ scheme in numerical simulation of hypersonic thermochemical nonequilibrium flow can get the accuracy aerodynamics and the accuracy position of strong bow shock.

Abstract:Based on the 2nd order NND scheme, a third order WNND scheme was constructed with Jiang and Shu's weighted idea and third order TVD Runge-Kutta method.It was applied in solving linear equation,1D Euler equations and 3D Navier-Stokes equations. The numerical results indicate that WNND scheme brings about less dissipation and spurious oscillations,and it can catch the discontinuities of the flow field.

Abstract:Numerical solutions for hypersonic aerothermodynamics of Mar's Pathfinder at Mach number 10 have been computed using the one-equation Spalart-Allmaras turbulence model and the second order MUSCL upwind scheme, AUSM+ scheme combined with LU-SGS implicit iteration has been used here. The numerical results derived from calorically and thermally perfect gas models have been compared with experimental data. Computed heating rates distributions with thermally perfect model are in good agreement with the experiment, however, those in separated zones are poorly predicted. It is seen that thermodynamic properties of hypersonic flows except the separated zones can be correctly simulated with this method if the mesh is appropriately designed, in particular, when the grid resolution near wall is sufficient.

Abstract:Polycarbosilane(PC-P), which is a useful precursor for Silicon Carbide fiber with high mechanical properties and low specific resistance, was synthesized using polydimethysilane(PDMS) and 3%～7%wt polyvinychloride(PVC). The synthesizing condition for PC-P was determined. The composition, structure and property of PC-P were studied by element analysis, IR, XPS and GPC. The reaction mechanism was preliminarily probed.

Abstract:SEM, EDX and XRD were applied to analyze SiC coatings deposited on the CVD furnace wall. The results show that the coatings consist of pure β-SiC in the lower-temperature block; however, there exist a few Si and α-SiC in the CVD SiC coatings within the higher-temperature block; the nucleation process and growth rate of SiC particles in the higher-temperature block are faster than that of the lower-temperature block; therefore, we can be sure that temperature is the main effect on the composition and microstructure of CVD SiC coatings.

Abstract:The damage of different carbon fibers was studied from high temperature, infiltration and pyrolysis of Polycarbosilane (PCS), and the oxygen in PCS. The result shows that the graphitizing extent and surface status influence the damage of carbon fiber greatly. The carbon fiber M40JB with a higher graphitizing extent was damaged more seriously; the carbon fiber JC1# with an active surface was sensitive to the variation of outside condition; however, the carbon fiber JC2#, which had a lower graphitizing extent and not active surface, was damaged less and was more stable.

Abstract:β-alkoxynaphthalenel was prepared from β-naphthol and H(CH₂)_n Br under nitrogen in the supersonic waves. Sodium methoxyide and methanol was solvent.The yield was 94%. The reaction conditions: molar ratio of β-naphthol/H(CH₂)_n Br was 1,condensation of sodium methoxide was 2.0 mol/L,supersonic ratio was 33±2kHz,reaction time was 5h.

Abstract:In order to get the ISAR images of maneuvering targets, Fourier transformation is replaced by time-frequency transformation with high resolution in both time and frequency domains. Range-instantaneous Doppler images of maneuvering targets are got. The imaging result using real data shows that this method is better than R-D algorithms.

Abstract:Aiming at the restriction of detecting the acclerating target using traditional DFT method,this paper is based on the discrete Chirp-Fourier transform and the real background in signal detection using missile-borne high-PRF pulsed Doppler radar.A transform naming changing scale discrete Chirp-Fourier transform is presented,and then the performance of the transform is analyzed.Finally,a new cascaded detection method is put forward for detecting the chirp signal using radar.The theoretics and the experiments demonstrates its effectiveness in performance.

Abstract:This paper studies the TDOA estimation method using the characteristics of cycle stationary communication signal.The study indicates that the TDOA estimation method based on spectral correlationl has better anti-jamming ability than the classical method of GCC,and this method can obtain the TDOA of each emitter unambiguously in the environment of multi-emitters.

Abstract:There are respective advantages for image processing and target detection by neural network methods of fuzzy set theory methods.The paper proposes a hybrid approach by combining the two type methods,namely,Fuzzy Multilayer Self-Organizing Map(FMSOM),which utilizes fuzziness measure as objective function of neural network.The network comprises multilayer structure,every neuron in each layer corresponds to pixel of image,which just connects with the corresponding neurons in prior layer and its neighbors.Experiments using remote sensing images as input are executed and the results verify the approach is valid for target detection and extraction,simultaneously,possesses good noise immunity.

Abstract:Digital watermarking is a key technique for protecting intellectual property of digital media. Similar to the noise pollution, watermarking process may induce image degradation. Since image quality is a determinant of its worth, it is significant to adjust the parameters in watermarking algorithm to satisfy specified quality requirement. Based on the Laplacian distribution model of AC DCT coefficients, we deduce theoretical relationship between the scaling parameter in a typical watermarking algorithms and signal to noise ratio (SNR) or peak signal to noise ratio (PSNR) of watermarked images. Thus the scaling parameter can be estimated according to the assigned image degradation grade. Experimental results demonstrate that the estimation has enough accuracy.

Abstract:A new synthetic aperture radar (SAR) image filter method is proposed based on hidden Markov model (HMM). First the hidden Markov tree(HMT) model in wavelet-domain is established. The parameters can be estimated by EM algorithm.Then SAR image's statistical property is studied, the multiple speckle noise of SAR image can be approximate as white Gauss addition noise under the local area. The wavelet coefficient of signal can be estimated by minimum mean-square estimate(MMSE). Applying this method to simulated image and real SAR image, the result shows that this method can effectively reduce speckle noise, while keeping image details.

Abstract:The basic construction of H.324 is introduced first. Two DSP chips named TMS320VC5509 are selected to realize real time H.324 system by the analysis of calculating capacity and memory capacity needed in video and audio codec. In this design the resources in DSP are allocated reasonably, the key parts of video codec are optimized. In order to eliminate float operation in fixed point DSP,float-point DCT is replaced by integer transform. The experiment result is finally presented.

Abstract:One of the practical difficulties that remains in large-scale DNA fragment assembly is the correct reconstruction of DNA sequences including repeats. An approach based on the definite-sized characteristic substring for the masking-off of repeats is proposed after considering the relative position information contained in fragment data. Before pair-wise alignment the approach chose unique substrings to mark fragments for the sake of decrease in possible incorrect overlaps. We also concretely describes the determination of some parameters and finally presents the computational result to prove the effectiveness of the method.

Abstract:Watershed transform is a classical method of image segmentation in mathematical morphology, and its parallelism is an important problem. This paper starts with a mathematical model of watershed transform in topography, followed by its several formal definitions for digital case. Then some new serial watershed algorithms proposed in recent years are classified and analyzed, based on which their related parallel strategies are discussed in detail. Then we analyze some issues, which should be considered when designing parallel watershed algorithm, and give an evaluation of existing parallel algorithms, and draw some conclusions. Finally we point out the problems and challenges of future research.

Abstract:Proxy caching has been recognized as one of the effective schemes to minimize the user access latency and reduce the network traffic. This paper gives a deep research into the key techniques of a caching system, such as information filtering、stale page access and replacement algorithm,and finally presents a cache scheme based on the firewall log with little cost and a reasonable performance.

Abstract:Metadata management system is the core of construction and management and maintenance and use data warehouse system. The keys of metadata management lie in the construction a comprehensive and extended metadata model which describes all kinds of metadata. This paper presents a General Metadata Model(GMM) which can support management and maintenance of data warehouse effectively, such as management of the user view, personalized service, incremental refreshment, data lineage tracing, etc.

Abstract:Supplying geographical information to public is an important service of the digital library.The characteristics of geographical information system in the digital library are analyzed.Its design and technology of implementation are represented.A prototype system is built.

Abstract:Run-Time Infrastructure (RTI) is the core of implementing High Level Architecture (HLA) simulation. The function and the performance of RTI has a direct bearing on the success of HLA simulation system. This paper first expatiates the theory and target of RTI testing. Then it studies the method of RTI testing with samples. In the end it summarizes the test research of RTI testing.

Abstract:This paper presents a novel method for distance measurement by multi ultrasonic arrays within the Direct Sequence Spread Spectrum (DS-SS) framework of the communication system. In view of the results of ultrasonic distance measurement simulation, it can be seen that the system design considerations, which is ground on the demodulation of BPSK signals by digital correlation and the adaptive equalization of receiving channels by means of Least-Mean-Squares algorithm, lead to strong restraint of the effect of disturbance in many cases, such as the phase error of local carrier used for coherent demodulation, the jam of multipath channels, and the random drift of the gain and phase in receiving channels, hence improve greatly the signal-noise ratio and the resolving power in ultrasonic orientation system accordingly. Furthermore, since the principle of the ultrasonic measurement system adopted here is based on spread spectrum with pseudorandom sequence codes, it is easier to realize of the Code Division Multiple Access (CDMA) by allocating different codes at different testing areas, so as to distinguish different signals transmitted by different ultrasonic transmitters/receivers, which will extend the measuring scope of the system. Thus it can be said that the methods considered in this paper has expansive prospect in the measure and control field for practical purposes.

Abstract:YHCAPP system is an instrumental CAPP system oriented to middle or small enterprises. Its key question is how to select process information and create process flowsheet from CAD drawing. A method based on arithmetical expression evaluation is provided, which has successfully resolved the above question and has proved its correctness and credibility. The method also provides a new way of thoughts for general instrumental CAPP system.

Abstract:An abridged algorithm of 2D hidden Markov chain model and its parameter estimation method are made. This method is simplier compared with preceding ones. Based on this method the corresponding recognition method and parameter estimation are presented. And estimating parameters in this manner is equivalent to the maximizing of the likelihood.