Abstract:An experimental study was conducted on the direct-connect scramjet combustor experiment system to investigate the performance optimization of scramjet combustor by adjusting the shape angles and fuel injection. An orthogonal array design of experiment method was used to organize the combination of shape angles. For every combination of shape angles, five experiments with different fuel injection arrangement were carried out, and every experiment was actualized with three equivalence ratios by adjusting a throttling venturi. The test data were used to build a response surface model of the combustor performance with respect to configuration parameters for combustor configuration optimization. The optimal combustor configuration was obtained by two successive optimizations, and the effects of configuration parameters on combustor performance were analyzed. The results showed that the thrust gain of optimal combustor configuration was increased by 10.4% relative to the baseline configuration, and the combustor performance was influenced strongly by the couple of configuration parameters.

Abstract:An ejector test facility was established to investigate the multi-nozzle supersonic ejector performance, and hot rocket exhaust gases were used as primary and secondary driving fluids. Emphases were placed on pressure matching between primary and secondary flows. The investigation indicates that the higher the total pressure of primary flow is and the lower the static pressure of on primary nozzle exit is, the more convenient it is for the performance to match with the secondary flow, and that the lower the secondary flow total pressure is, the more the critical ejector performance is required to maintain pressure matching, and that the secondary flow total temperature has little influence on pressure matching.

Abstract:Based on the back propagation and radial basis function neural network, and using the tool of Matlab and Lab Windows/CVI, the real-time fault detection algorithms for the start-up and main-stage process of a certain liquid-propellant rocket engine in ground tests are developed in this paper. The algorithms realized were verified with a great deal of historical test-data and also validated in the practical ground tests of the engine. The results show that the algorithms not only can detect the fault of the engine in time and efficiently without false alarm and missing alarm, but also can meet the real-time ability and robustness requirement.

Abstract:By way of Coupling the effects among the electric field, magnetic field and flow field in the pulsed plasma thruster, the process of the capacitor discharge, propellant ablation and plasma acceleration are characterized, and a one-dimensional time-dependent model based magnetohydrodynamic（MHD）for PPT is presented in this paper. The simulation results are analyzed and compared with the experiment. The result exhibits that the model perfectly reveals the thruster discharge process, variation of ablated mass and surface temperature of propellant.

Abstract:An improved fitting algorithm of Broadcast Ephemeris for GEO satellite with near-zero-inclination is introduced in the paper. The main idea of the algorithm requires the appropriate rotation of the coordinate reference plane to the position observations based on the general algorithm. Within the algorithm, in particularly, the corresponding coordinate transformation to the fitting initial value is proposed. According to the method, fitting problem in the correlation of orbital parameters can be resolved, and the convergence of iterations is quickly achieved. Meanwhile, the computation for the user receiver is simplified. The simulation results show that the Root-Mean-Square error reaches centimeter level and the fitting accuracy can be guaranteed, indicating the effectiveness of the method.

Abstract:Hydrogen peroxide is one of the most important directions of liquid rocket propellant. Considering the low-frequency oscillation phenomenon which occurs in experiment of hydrogen peroxide engine, simulation and analysis of the phenomenon based on the propulsion system models were made, and a stable engine was achieved. The current research is helpful for linking system simulation to experiment in hydrogen peroxide engine development.

Abstract:Visual tracking in a clutter background remains to be a challenging task by far. The particle filter based tracking algorithm proposed in this paper fuses color and texture information to build a robust measurement function. During the measurement step, the color information and texture information were represented by color histograms and gradient orientation vector respectively. Bhattacharyya coefficient and Euclidean distance were used to set up an effective connection between the estimated model parameters and the image likelihoods. Moreover, to overcome the problem of appearance changes, partial occlusions and significant clutter, an adaptive model update method was adopted. Experimental results show that the proposed method is robust and effective.

Abstract:Enthalpy change for different synthesizing route of dihydroxyldiphenoxydimethyl silane was calculated with semi-empirical-AM1 and Molecular Dynamics by means of HyperChem7.0. The theoretical calculation gave optimized synthesizing route and IR spectra of the novel target compound. It showed that synthesis of dihydroxyldiphenoxydimethyl silane by dimethydiethoxyalkoxy silane was favorable according to thermodynamic calculation　results. The target compound can be obtained in the synthesizing experiment. Hyperchenm7.0 was useful in synthesis and characterizing of novel organic compound.

Abstract:A fractal sea model based on non-fully developed full-range sea spectrum (NDFFM), which is believed to be more applicable to the real sea surface, is presented. The two-scale method is used to calculate the backscattering cross-section of the NDFFM sea surface. The distribution of the time-varying scattering amplitude is studied, and the numerical results show that the distribution satisfies K-distribution with higher significant-slope(SS) and satisfies Rayleigh distribution with lower SS. Finally, the results are compared with those of the conventional fractal model and the real radar data, which prove the accuracy and efficiency of this model.

Abstract:Due to the fact that linear prediction method is difficult to describe the nonlinear, non-stationary changes of cloud clusters, a technique of retrieval nonlinear clouds clusters forecast model, based on the idea of combining the decomposition of empirical orthogonal function (EOF) and the genetic algorithm optimization parameters, was presented. Firstly, satellite image sequences were temporal-spatially decomposed by EOF. On this basis, genetic algorithms were introduced to make the dynamic model reconstruction and model parameters optimization retrieval of EOF time coefficients sequence, and a nonlinear differential equations of EOF time coefficients were established. Then, by the EOF temporal-spatial functions synthesis, a dynamic forecast model of cloud clusters evolution was structured. The experimental results showed that the retrieved clouds dynamic forecast model was more reasonable in describing the cloud evolution of the underlying trend in particular seasons and region, and the forecast results were better accorded with the basic characteristics of actual satellite cloud pictures. Especially, a middle-long period over three hours objective cloud clusters predictions was achieved.

Abstract:In the presence of sea-surface multi-path，due to the interference of multi-path reflection, the measurement of a low elevation target by monopulse is often greatly affected. So off-axis tracking technique was adopted generally. By means of the analysis based on the model of multi-path reflection environment，both specular reflection and diffuse reflection were considered. Expression for the average bias in the mono-pulse ratio due to specular and diffuse reflections and the noise in the radar channel was derived. Algorithm was combined with bias compensation so as to adapt to the elevation measurement of off-axis tracking targets in the presence of sea-surface multi-path. This is aimed to avoid the disadvantage of both techniques employed here. Throughout the simulation in some scenarios, the results show that the method combining the two algorithms together can improve the precision of low-altitude target elevation measurement. Then it was applied in the extraction of postal data of off-line cruising flying object's elevation measurement, and a comparison was made with real time data elevation measurement by actual radar system. The results indicate that this method is effective and feasible in the off-line elevation extraction and it can remarkably improve the precision of elevation measurement

Abstract:An image can be decomposed into two parts, uniform structural part and geometric texture part. Based on this idea, this paper proposes an efficient two-layered image compression method using the second generation Bandelets and wavelets. Firstly, an original image f is decompose into u and v , where u represents the structural part and vthe texture part, then uandvare compressed by using wavelets and the second generation Bandelets respectively. The paper adopts a top-down algorithm of quadtree segmentation, which optimizes the quadtree construction of the second generation Bandelet. Numerical experiments prove that our method outperforms Bandelets or JPEG2000 compression system in both visual effect and objective SSIM value.

Abstract:The problem of discriminating active decoys and radar target was studied based on the radar data processing in the background of missile defense. On the basis of the essential difference of the dynamic model between those active decoys and the real target, the concept of dynamic model match coefficient was proposed. The analytic expression of the coefficient was presented without considering the radar measurement noise. The discrimination threshold was designed based on the radar tracking data. The computer simulation was carried out with the background of an intermediate range ballistic trajectory. The feasibility and validity of the proposed algorithm was verified by the simulation results.

Abstract:Only the final performance of InSAR processing is evaluated in normal evaluation method. In this regard, an algorithm for interferometric phase simulation is presented in the hope that it is applicable to distributed spaceborne InSAR (Interferometric Synthetic Aperture Radar). Not only the perfect interferometric phase but also the perfect co-registration offset are generated in this algorithm. A novel method for InSAR performance evaluation is proposed, which is based on perfect interferometric phase and perfect co-registration offset. With this method, the errors of each step of InSAR processing can be isolated. Furthermore, performance of InSAR processing algorithm can be evaluated.

Abstract:The current video summarization techniques are in want of a normal and expandable summarization model. To solve this problem, Entity-Description-Utility (EDU), a general expandable model, is proposed. The model starts from video entity, gets utilities after descriptions, and finally generates video summarization by the utilities. The EDU model is described in detail, and a method of news story summarization based on this model is also produced. The experiment proves the effectiveness of the method.

Abstract:A new fast discrete time scale transformation algorithm is presented and an appropriate expression of discrete time scale transformation is supplied. The expression can be calculated fast by using the chirp transform. The performances of the proposed algorithm are analyzed by comparing with other algorithms. The validity of the algorithm is shown by simulation results.

Abstract:An improved method of plane-wave time-domain algorithm (PWTD) of scalar field based on the present PWTD algorithm is presented. With this method, computation of interpolated function was transformed to tabulation of the interpolated function, and the maximum error was presented. Additionally the derivative operation in translation operator was placed on the outermost, which reduces original (K+1)(2K+1) times operation of FFT and IFFT to one time. Consequently the cost associated with the computation was decreased. Two examples were presented to demonstrate the accuracy and high efficiency of the improved algorithm.

Abstract:TSAE-Z algorithm combines time slice autocorrelation envelope detection with step-variable Zoom-FFT detection (TSAE-Z), and achieves rapid and precise detection of cyclic-stationary signals. Results of simulation shows that, on condition of the same length of data, TSAE-Z algorithm is able to significantly decrease implementing time of detection by thousand-grade, and on condition of the same implementing time, TSAE-Z algorithm can get 6dB improvement at least on detection performance as well as on detection resolution.

Abstract:As a lower bound on mean square error of parameter estimate, the Cramér-Rao lower bound (CRLB) is generally used to decide to what degree a suboptimal estimate method is close to its optimal fashion. With the assumption of coordinated turn maneuver, a generic approach for target tracking CRLB calculation was investigated under the conditions of active and passive measurement, and the essential reason for possible CRLB's sudden increase caused by maneuver was also analyzed from the perspective of matrix theory, which provides an effective measurement for performance assessment of estimate methods used in maneuvering target tracking. Finally, simulation example for CRLB calculation was presented.

Abstract:A novel alignment method for swaying base, such as a sailing ship, is presented with the aid of a cascade of FIR filters and a transitional inertial frame. For the method, an investigation was made about the error characteristics, which shows that the alignment accuracy mainly depends upon the equivalent biases of gyroscopes in east direction and performance of FIR filter group, the aligning time rests with the orders of the FIR filter group, and the problem of large initial misalignment is resolved in theory. Results of experiments show that the proposed method converges much faster than the traditional methods at no cost of precision and also works well under any large initial misalignment.

Abstract:In order to release astronaut's pressure and guarantee the success of rendezvous and docking(RVD), a manual control RVD simulation system is highly necessary. By analyzing the dynamic models of chase spacecraft and target spacecraft, the basic frame of manual control RVD simulation system was constructed, on which corresponding experiments were made. The results of experiments show that the astronaut can control position and attitude of chase spacecraft by manipulating the hand-stick and ensure the success of RVD. For reducing the complexity of manipulation, astronauts usually control the position of chase spacecraft, and insure that attitude control task is completed by automation. In this way, the success rate of manual-control RVD is larger.

Abstract:For supplying the capability of replaying the HLA federation execution data and solving the issues demanded by playback that data must be integrated as a whole, time order must be exactly, run efficiency should be highly and the solution should be general-purpose, this paper explores the issues of data replaying in HLA federation, analyzes the requirements and the impacts of HLA on playback, points out that the essentially general purpose is a concept of federation independent, and excogitates a data processing method to deal with the replayed data by means of object. Relying on the strategy of a concentrated playback federate, the playback solution was putted forward, which is based on the technology of data's object serializing and federates' automatic-generating. The solution realizes the goal to make a general purpose data playback. In the end, this paper introduces the application of the general-purpose playback tool.

Abstract:Based on the transmission line approximation, three different equivalent formulations have been proposed for evaluating the interaction between an external electromagnetic field and a transmission line. Moreover, for the line-plane transmission-line, employing the three formulations, C. A. Nucci and F. Rachidi discussed the voltages induced on an overhead line by a nearby lightning strike and, by numerical example, showed that the total induced voltages predicted by these three formulations are identical. This paper, by using an analytic method to discuss the load voltage and current response with the line-plane transmission-line Taylor and Agrawal coupling models, obtained their analytic solutions of the load response for a plane-wave excitation. In the end, it proves that the analytic solutions are equal indeed. In other words, the two coupling formulations are different expressions of the same equations.

Abstract:Cogging force is a main factor that affects the performance of permanent magnetic brushless DC linear motors (PMBLDCLM) at low speed. Since the cogging force cannot be eliminated thoroughly by design method, compensation must be introduced in the control system. Theoretical analysis of an ideal motor control system with cogging force being considered shows that cogging force can be diminished through a position feedback loop. The finite element analysis (FEA) results prove that the thrust fluctuation of the motor at low speed is mainly caused by cogging force and can be compensated for through position feedback control algorithm. A method of dividing a fundamental circle of the cogging force into sections and performing linear compensation at each section is proposed. Since this method does not need any high precision locating equipments and complicated algorithms, it is easy to be implemented. Experiment results show that the motor thrust fluctuation can be diminished effectively with the method proposed.

Abstract:There has been no mature model for expressing needs and expectations of people within the area of national defense, and it is considered as the most important business in C⁴ISR requirement analysis. In order to cope with this problem, an approach has been put forward in the paper. Firstly, basic concepts were analyzed, the concept of C⁴ISR requirement system was put forward based on concept analysis, and the idea of modeling C⁴ISR requirements was presented. Secondly, elements of C⁴ISR requirements model were studied. Metaclasses in the domain of C⁴ISR requirements and relationships among the metaclasses were distilled and defined. Therefore, C⁴ISR requirements models were designed on purpose to solve C⁴ISR requirement problems. Lastly, the paper provides the process of modeling C⁴ISR requirements based on element analysis. What C⁴ISR requirement models require and how to build the models are clarified. The approach elaborates what the real C⁴ISR requirements are and it can serve as the guideline of modeling C⁴ISR requirements.

Abstract:A new methodology of Capability Based Planning is introduced, and a bilevel programming model to allocate resources at military capability and system level is presented. The upper level of the model has two global objectives of effect and effect-cost ratio, which determines the constraint of investment scale to the lower. At the lower level, the optimal combinations of alternative systems are attained to maximize each kind of capabilities under the specified cost constraint, and then returned to the upper. To solve the bilevel programming model, the multiobjective genetic algorithm is adopted. The results of the presented example suggest that the bilevel programming model and its solution algorithm are valid to the problem of military acquisition and resource allocation.

Abstract:Considering some problems derived from the dynamic adaptation research on complex system of systems, a new design method which applies redundancy theory to effectively improving the dynamic adaptive ability of complex system of systems is presented. The concept of redundancy-based complex system of systems is firstly described. On this basis, both the dynamic game design process of redundancy-based adaptive complex system of systems and its framework are shown. Then three kinds of redundancy, such as task redundancy, system redundancy and structure redundancy, are illustrated in detail according to the structure hierarchy features and the mission performing rule of complex system of systems. Lastly, the redundancy framework existing in complex system of systems is synthetically discussed from the viewpoints of redundancy switching, redundancy material and redundancy character, which indicates that the redundancy framework is not only an adaptive strategy to dynamic environment for complex system of systems, but also the demand and result of its long-lasting evolvement. Thus, some theoretic guidance for structure design and effectiveness evaluation of the dynamic adaptation of complex system of systems and its upgrading and optimization should be conducted with this kind of analyzing methodology.