Abstract:Planar laser induced hydroxyl fluorescence (OH-PLIF) technology has been used to image the hydroxyl of supersonic combustion supplied by the hydrogen fuel being ejected to the mach 1.72 freestream in the three different streamwise sections. Employing a frequency-doubled dye laser with wavelength of 283.553nm as exciting laser，the fluorescence intensity of hydroxyl is nearly indirect proportion to the mole fraction of hydroxyl. The highly turbulent flame structure of supersonic combustion has been revealed from the instantaneous PLIF images of hydroxyl. The steady combustion in the cavity can offer on-duty flame stimulating and stabilizing the supersonic combustion. The flame spreads in the radial direction as well as in the stream direction. Having bigger spreading scale of the cavity, the streamwise flame region would diminish a little.

Abstract:In this paper, the enabling technique of maintenance and reconfigurati on control of spacecraft formation flying is studied. First, the state transfer matrix of relative motion was introduced and the expression of relative motion with constant thrust control was educed. Then, 3 models of thrust were illustrated, which are impulse thrust, continuous thrust and Bang-Bang thrust. With the state transfer matrix, the differences of the thrust models in relative motion control were explored. Results show that in first order means the relative motion control effects with impulse thrust, continuous thrust and Bang-Bang thrust control are equivalent. So the problem of maintenance and reconfiguration of spacecraft formation flying could be implemented with Bang-Bang thrust control.

Abstract:The automatic differentiation method (ADM) for calculating sensitivities is presented. It is a powerful method for dealing with the system sensitivity analysis of the multidisciplinary design optimization. The theory of this method, a general procedure for the implementation of this method, and the realization in Visual C++ 6.0 of this method were described in detail. Also there is a comparison between the finite differences method (FDM) and complex variable method (CVM) in this paper. The ADM is shown to have some advantages over the others, thus having the potential to be widely used in the future.

Abstract:A steady state genetic algorithm which can deal with several criterion functions was applied to the design optimization of Space Based Radar(SBR) satellite constellations. The discontinuous coverage model, inter-satellite links geometry model and bistatic moving target detection geometry model, which can describe the working properties of the SBR constellations, were developed. Then, the statistic evaluation and comprehensive evaluation indices were put forward, and the design optimization model was established. According to the particularities of this problem, steady state co-evolutionary genetic algorithm on the basis of searching in feasible solutions was used to deal with the design optimization problem. Finally, several design examples were presented, showing that the method is effective.

Abstract:The complex inner flow-field of secondary gas injection for Solid Rocket Motor was numerically investigated by using three-dimensional average Favre equations and the turbulent models. Three-order spatial scheme and Implicit point Jacobi algorithm were used to solve these equations. It gained the structures of shockwave series of secondary gas injection vector nozzle and complex main/secondary flow image by numerical simulation. The secondary flow field includes complex vortices and shockwave series. It also has interaction by the boundary layer and shockwave, free shearing layer, shockwave, rarefaction wave and heavy gauge separation. The numerical simulation also indicates that secondary hot gas injection results in high temperature on the surface wall round the injector hole. Corresponding thermal protections should be adopted.

Abstract:Under strong crosswinds, the aerodynamic performance of box car is the worst in the universal vehicles used in the railroad. Using 2D, steady state incompressible Navier-Stokes equation and two equations k-εturbulent model for the box car under strong crosswinds, the optimization of the aerodynamic figure has been carried out by finite volume. Results obtained show that the figure of roof greatly affects the aerodynamic performance of box car. The P₆₅ box car with arch roof has better aerodynamic performance than the P₆₄ box car with slope roof. If the roof arc and the lateral wall could be connected by the round fillet, the aerodynamic performance would be much better. With a consideration of the two factors of aerodynamic performance and the effective volume, it is suggested that the roof arc radius should be 2692mm and the fillet arc radius be 500mm.

Abstract:The curing processes of E-51 epoxy resin with two　types of curing agents, such as a modified 2-ethyl-4-methylimidazole(MIM) and a microcapsule type curing agent with MIM as the core material (MIC), were studied in detail by the non-isothermal differential scanning calorimeter (DSC) technique respectively, and the kinetics of the curing processes were analyzed by Kissinger and Crane equations, based on which the relationship between the curing kinetic parameters of the curing systems with the storage lives of the curing agents at room temperature were discussed in detail. Compared with E-51/MIN system at different heating rates, it was found that E-51/MIC system exhibited lower exothermic heat, the same reaction order (0.89), higher apparent activation energy, higher frequency factor and longer storage life at room temperature.

Abstract:Polycarbosilane（PCS）was synthesized from the distilled fractions of liquid polysilane (LPS). By adopting the GPC technique，the influence of different distilled fractions of LPS on the molecular weight and their distribution of PCS was discussed in detail. It was found that the total average yield of PCS synthesized from the distilled fractions of LPS is about 35wt% higher than that of PCS synthesized from the untreated LPS under the same condition. In addition, PCS with a super high molecule weight can be synthesized from the distilled fractions of LPS treated below 200℃.

Abstract:Polycarbosilanes (PCSs) are synthesized at high temperature under high pressure. Synthesis processing and vacuum distillation of PCS are investigated. The results show that the molecular weight and distribution of PCS can be roughly controlled by synthesis conditions. With the increase of the reaction temperature and time, the molecular weight grows with a broadened distribution. High molecular weight PCS appears when the reaction temperature is higher than 450℃ with reaction time over 6h, or 460℃ with 4h, respectively. Super-high molecular weight PCS can be obtained if the reaction temperature and time still keep on increasing. The low molecular weight PCS content decreases while the vacuum distillation temperature increases. The molecular weight of PCS, therefore, increases with a narrow distribution. When the vacuum distillation temperature increases 50℃ from 250℃, the low molecular weight content in PCS decreases about 8% with a drop of polydisperity index about 0.3 and a grow of average molecular weight of high molecular weight about 1000.

Abstract:Si₃N₄matrix ceramics which would be applied to super-high Mach number missile radome was prepared via the reaction sintering process. Si, BN and SiO₂ powder were the main raw materials. The effects of the raw materials and the model processing parameters and the compact density on properties of the material were investigated. The experimental results showed that the material has the best mechanical properties (σ_b, K_ICis 96.7MPa, 1.80MPa.m^1/2, respectively) and better dielectric and thermal physic properties when the content (in raw mixture powder) of Si, BN, SiO₂, is 55%, 30% and 10%, respectively.

Abstract:The design of excitation sources was presented and the characteristic of waveguide was analyzed with multi-domain pseudospectral time-domain (MPSTD). The cut-off frequency of 2D waveguide and the S parameters of typical 3D waveguide model were calculated with the MPSTD. All numerical results were compared with the HFSS or the FDTD results, which display that the MPSTD is more accurate and efficient. This paper offers a scheme for analyzing the complex waveguide accurately, and extends the application field of MPSTD.

Abstract:Beam synchronization is one of synchronizations for spaceborne parasitic radar system, and this paper mainly analyzes this problem. Firstly, based on characteristics of spaceborne parasitic radar system and combined with scannable antenna and adjustable attitude of micro-satellite, three methods for beam pointing synchronization were presented. Then, beam area synchronization was analyzed, the models of beam area for the transmitting satellite and micro-satellites were established. Finally, the simulation of interferometric cartwheel as an example not only proves that these models are valid, but also indicates that the second method for beam pointing synchronization is much better.

Abstract:Termination analysis for active rules improves the design of rule set. Active rule meta-model is proposed as a basis for termination analysis and comparison. The refined triggering graph was extended to construct labeled events graph(LEG). Termination analysis algorithm of LEG was presented, whose efficiency was illustrated by an example. It can be easily seen that LEG is a general abstract model for termination analysis in comparison with other methods.

Abstract:Simulation of blood flow is a very important component in the virtual system of cardiac intervention system. Real-time and accurate simulation of blood flow can make the virtual surgery more realistic. This paper addresses the problem of the simulation of blood flow in virtual cardio-vascular objects. With an analysis of the physical model of cardiac-vascular blood flow in the artery based on the Windkessel model and by drawing the blood with improved particle system, this research successfully simulated the blood flow inside the vascular, thus satisfying the need of being real-time and realistic for the Cardiac intervention system.

Abstract:The problem of multi-robot simultaneous localization in an unknown environment based on relative observation was studied. Each robot was equipped with proprioceptive sensors and exteroceptive sensors. Exteroceptive sensors provided relative observations between robots, such as relative distance and bearing. Considering the nonlinear problem, we used extended Kalman filter to fuse proprioceptive and exteroceptive data. Different relative observations and the number of the robots were studied and simulated. The filter structure for each case was presented and the performances of the algorithm were compared as to the accuracy and other aspects. Simulation results prove that the location accuracy has been improved effectively by using relative observations among robots.

Abstract:Infrared image has a lot of advantages, such as strong anti-interference, independence to visible light source, defendence from camouflage and defendence against cheat. These advantages help infrared image face recognition to a large extent to make up for the shortage of visible image face recognition. Now infrared image face recognition is an important direction in the field of face recognition. Based on the analysis of characteristics of infrared image, the properties of infrared image face recognition ware analyzed and a new infrared image statistical face recognition method was proposed in this paper. Experimental results show that the recognition method is workable and has good partition capability.

Abstract:3D passive location of radar emitters plays an important part in electronic support for military surveillance. The AOA (angle of arrivals) is one popular scheme for passive emitter location. In this paper, a location scheme is proposed based on fusion of AOA measurements from two ESM (electronic support measures) sensors installed on two moving platforms, respectively. Furthermore, ILS (iterative least-squares) is also proposed to fuse AOA measurements from two ESMs. Experimental results show that the location accuracy of the radar emitter can be improved effectively by this AOA fusion algorithm.

Abstract:A new method for evaluation of ambiguity-to-signal ratio in spaceborne bistatic SAR was proposed in terms of bistatic geometry. Based on that, the ASR of the new system was analyzed in different cases. Simulation results show that due to the limited size of antenna onboard small satellite, the ASR of bistatic SAR is much higher than that of monostatic spaceborne SAR, though their changing trends are similar. Compared with the ASR in azimuth, the ASR in range is closer to that of the monostatic case because the size in height dimension of small antenna is closer to that of the big antenna than the length dimension is.

Abstract:Based on the spaceborne parasitic SAR earth observation application, the author aimed to analyse the influence of the frequency synchronization error to the bistatic SAR imaging. The “interferometric cartwheel” configuration was employed as an example, to make computer simulation of the synchronization error. Therefore, a novel frequency synchronization method was presented. This method acquires the frequency synchronization error by the correlation processing to the “direct signal” which leaked from the SAR antenna side lobe. The simulation results indicate this new synchronization method is accurate and effective.

Abstract:A low complexity asynchronous multiuser detection algorithm for on board LEO satellite receiver, which can resist strong multiuser interference and large doppler frequency drift is introduced. After chip match filter, base band signal was sampled at chip rate and used as observe signal. Then Kalman filter was used to separate multi-user signal. Doppler frequency drift and timing error were considered in state transform equations. The proposed algorithm can resist as high as 35dB near-far effect, and are senseless to frequency and timing error.

Abstract:The space rover shoulder is expected to have higher mobility and reliability to satisfy future space exploration mission in unknown irregular environment. Through the combination of the advantages of both the self-adaptive and active rovers, the concept of active self-adaptive suspension rover, a type of self-adaptive suspension rovers, which can reconfigure themselves according to terrain, is creatively ggproposed. In even terrain, the active self-adaptive suspension rover just works like self-adaptive suspension rovers, while in rough terrain, it can reconfigure its structure to fit terrain and promote mobility. To verify the idea, a six wheeled active self-adaptive suspension based concept rover, which can fold and stand up if it is upset, was constructed. Based on an integrated model of mobility for space rover, the configuration model and the active way to reconfigure were also proposed. It is revealed from the study that the active configuration makes the active self-adaptive suspension rover own better mobility and reliability, which enable the active self-adaptive suspension rover to fit unknown irregular environment better.

Abstract:The effect of the three kinds of material on the removal function is studied. The considering properties of the removal function include the removal profile, the removal rate, the stability of the removal function and the surface topography. A series of experiments have been done to the perfect properties of the removal function. The experiments were done on the AOCMT machine tool and the contact measurement system developed by ourselves. The results were presented as follows. Polyurethane is used in the step of the rough polish. Polishing cloth is used in the step of the finishing polish. Polishing pitch (55# polishing pitch by GuGolz Corporation ) is used in the step of the surface treatment or the finishing polish.

Abstract:In order to extract the vibration value which indicates the same frequency as rotating speed from the lower S/N ratio signal and adapts to speed variety, the method of Narrowband Tracking Filtering was deduced by the principle of correlation analysis. Based on this method a Narrowband Tracking Filter was designed and implemented by Multiplying Digital-to-Analog Converter (MDAC). The experimental results demonstrate that the filter has the good performance and is able to meet the requirements of dynamic balancing measurement, which the relative error of amplification is better than 0.2%, the absolute error of phase is better than 0.4° and its output can track the change of rotating speed when the variety ratio of speed is under 9000r/min².

Abstract:Support vector machines is a blackbox model whose knowledge is concealed in the decision function. This has not only weakened the confidence of users in building intelligent systems using support vector machines techniques, but also hindered the application of support vector machines to data mining. Since extracting rules from support vector machines help to solve those problems, this area is becoming a hot topic in both machine learning and intelligent computing communities. In this paper, the typical algorithms for rule extraction from support vector machines are introduced, and some issues valuable for future exploration in this area are indicated.

Abstract:Most of the current methods for safety analysis belong to the scope of safety pre-analyzing, which analyzes the system safety before system being in service. But the system safety is full of variety because of　the system's dynamic characteristic, such as the running status variation of system component. In order to know well the real-time safety risk, a real-time monitoring method for system safety is proposed. The safety risk model was established on the fault tree that was used to represent logic structure of system. The real-time safety risk was monitored according to the correspondence between　technical status of system component and running status of system component. Simultaneously the method could account for the change of risks, thus ensuing the taking of precautions. Finally a case monitoring the safety risk for cooling system with pre-feedback was used to demonstrate the effectiveness of the method.

Abstract:The characteristic that observation activity has variable profit in satellite scheduling is analyzed, and the upper bound and lower bound of profit of activity are discussed. An advanced tabu search algorithm with local derivational is proposed. A mechanism with layered variable evaluating functions is used in the proposed tabu search algorithm, which leads the procedure of searching solution to multiobjective optimization, and both raises the rate of coverage and reduces the consumption of energy. The result of practical example demonstrates that the algorithm proposed in this paper can be applied to the satellites scheduling problem with variable profit of activity effectively.

Abstract:As an important property of operation group, formation reflects the cooperative relationships among group members in space arrangement. It often indicates the intention of near future, identity and threat of enemy groups directly. In order to provide much more significant battlefield information and much better support for commanders' situation assessment and command activity, the problem of recognizing made-up lines of formations is researched. Based on Hough Transform, a template-based modeling method for these formations is proposed at first, then the pattern feature extraction strategy based on clustering of points in Hough Space is put forward. At the end of the paper, a formation recognition approach based on the matching between pattern features of a formation and these templates is suggested. Experiment results show that the method is effective.